What is Environmental Testing?
The electronic devices and industrial products we rely on every day are affected by the environment in many ways, including temperature, humidity, pressure, light, electromagnetic waves and vibration. Environmental testing analyzes and evaluates the impact of these environmental factors on the product to determine its durability and reliability.
Guangdong Lab Companion LTD., has 10 million yuan registered capital and 3 R & D manufacturing plants in Dongguan, Kunshan and Chongqing. Lab Companion has been specialized in high and low temperature test equipment technology for 19 years, operating according to ISO9001, ISO14001, ISO 45001, ISO27001 four systems, setting sales and maintenance service centers in Shanghai, Wuhan, Chengdu, Chongqing, Xi 'an and Hong Kong. We work closely with International Organization of Leg al Metrology, Chinese Academy of Sciences, State Grid, China Southern Power Grid, Tsinghua University, Peking University, Hong Kong University of Science and Technology and other research institutions.
Main products of Lab Companion includes high and low temperature test chamber, constant temperature and humidity test chamber, rapid temperature cycling test chamber, thermal shock test chamber, high and low temperature and low pressure test chamber, vibration of the comprehensive chamber, industrial oven, vacuum oven, nitrogen oven, etc, providing high quality experimental equipment for universities, research institutes, medical health, inspection and quarantine, environmental monitoring, food and drugs, automobile manufacturing, petrochemical, rubber and plastic products, IC semiconductor, IT manufacturing and other fields.
Thermal Cycling Test(TC) & Thermal Shock Test(TS)
Thermal Cycling Test(TC):
In the life cycle of the product, it may face various environmental conditions, which makes the product appear in the vulnerable part, resulting in product damage or failure, and then affect the reliability of the product.
A series of high and low temperature cycling tests are done on the temperature change at the temperature variation rate of 5~15 degrees per minute, which is not a real simulation of the actual situation. Its purpose is to apply stress to the test piece, accelerate the aging factor of the test piece, so that the test piece may cause damage to the system equipment and components under environmental factors, in order to determine whether the test piece is correctly designed or manufactured.
Common ones are:
Electrical function of the product
The lubricant deteriorates and loses lubrication
Loss of mechanical strength, resulting in cracks and cracks
The deterioration of the material causes chemical action
Scope of application:
Module/system product environment simulation test
Module/System Product Strife test
PCB/PCBA/ Solder Joint Accelerated Stress Test (ALT/AST)...
Thermal Shock Test(TS):
In the life cycle of the product, it may face various environmental conditions, which makes the product appear in the vulnerable part, resulting in product damage or failure, and then affect the reliability of the product.
High and low temperature shock tests under extremely harsh conditions on rapid temperature changes at a temperature variability of 40 degrees per minute are not truly simulated. Its purpose is to apply severe stress to the test piece to accelerate the aging factor of the test piece, so that the test piece may cause potential damage to the system equipment and components under environmental factors, in order to determine whether the test piece is correctly designed or manufactured.
Common ones are:
Electrical function of the product
The product structure is damaged or the strength is reduced
Tin cracking of components
The deterioration of the material causes chemical action
Seal damage
Machine specifications:
Temperature range: -60 ° C to +150 ° C
Recovery time: < 5 minutes
Inside dimension: 370*350*330mm (D×W×H)
Scope of application:
PCB reliability acceleration test
Accelerated life test of vehicle electric module
LED parts accelerated test...
Effects of temperature changes on products:
The coating layer of components falls off, the potting materials and sealing compounds crack, even the sealing shell cracks, and the filling materials leak, which causes the electrical performance of components to decline.
Products composed of different materials, when the temperature changes, the product is not evenly heated, resulting in product deformation, sealing products cracking, glass or glassware and optics broken;
The large temperature difference makes the surface of the product condense or frost at low temperature, evaporates or melts at high temperature, and the result of such repeated action leads to and accelerates the corrosion of the product.
Environmental effects of temperature change:
Broken glass and optical equipment.
The movable part is stuck or loose.
Structure creates separation.
Electrical changes.
Electrical or mechanical failure due to rapid condensation or freezing.
Fracture in a granular or striated manner.
Different shrinkage or expansion characteristics of different materials.
The component is deformed or broken.
Cracks in surface coatings.
Air leak in the containment compartment.
Lab Companion-Rapid Temperature Cycling Test Chamber
Introduction of Lab Companion
With over 20 years of experience, Lab Companion is a world class manufacturer of environmental chambers and an accomplished supplier of turn-key test systems and equipment. All our chambers build on Lab Companion’s reputation for long life and exceptional reliability.
With a scope of design, manufacture and service, Lab Companion has established a quality management system that complies with the International Quality System Standard ISO 9001:2008. Lab Companion’s equipment calibration program is accredited to the International Standard ISO 17025 and the American National Standard ANSI/NCSL-Z-540-1 by A2LA. A2LA is a full member and signatory of the International Laboratory Accreditation Cooperation (ILAC), the Asia Pacific Laboratory Accreditation (APLAC) and the European Cooperation for Accreditation (EA).
Lab Companion’s SE-Series Environmental Test Chambers offer a significantly enhanced airflow system, which provides better gradients and improved product temperature change rates. These chambers utilize Thermotron’s flagship 8800 Programmer/Controller featuring a high resolution 12.1” flat panel display with touch screen user interface, expanded capabilities to graph, data log, edit, access on-screen help, and long term hard drive data storage.
Not only do we offer the highest quality products, we also provide ongoing support designed to keep you up and running long after the initial sale. We provide factory direct local service with an extensive inventory of the parts you might need.
Performance
Temperature range: -70°C to +180°C
Performance: With 23 Kg aluminum load (IEC60068-3-5), the rising rate from +85°C to -40°C is 15℃/min; the cooling rate from -40°C to +85°C is15℃/min too.
Temperature control：± 1°C Dry bulb temperatures from control point after stabilization at the control sensor
Performance is based on an ambient condition of 75°F (23.9°C) and 50% RH
Cooling/Heating Performance based on measurement at the control sensor in the supply air stream
Constructure
Interior
Nonmagnetic Series 300 stainless steel with a high nickel content
Internal seams heliarc welded for hermetic sealing of the liner
Corners and seams designed to allow for expansion and contraction under the temperature extremes encountered
Condensate drain located in the liner floor and under the conditioning plenum
Chamber base is fully welded
“Ultra-Lite” non-settling fiberglass insulation
One adjustable interior stainless steel shelf is standard
Exterior
Die-formed treated sheet steel
Metal access covers provided for easy opening doors to electrical components
Finish water-based, air dry lacquer, sprayed over a cleaned and primed surface
Easy lift-off hinged access doors for servicing the refrigeration system
One 12.5 cm diameter access port with interior weld and removable insulating plug mounted in right hand side wall accessories on hinged door for easy access
Features
Chamber Operation clearly displays helpful run-time information
Graphing Screen offers expanded capabilities, enhanced programming and reporting
System Status displays crucial refrigeration system parameters
Program Entry makes it easy to load, view and edit profiles
Set Up quick-step wizards make profile entry easy
Pop-up Refrigeration Charts for handy reference
Therm-Alarm® provides over & under temperature alarm protection
Activity Log Screen provides comprehensive equipment history
Web Server allows internet access to equipment via Ethernet
User-Friendly Pop-up Key Pad makes data entry quick and easy
Includes:
- Four USB Ports-two External & two Internal
- Ethernet
- RS-232
Technical specifications
1-4 independently programmable channels
Measuring Accuracy: 0.25% of span typical
Selectable °C or °F temperature scale
12.1” (30 cm) color flat panel touch screen display
Resolution: 0.1°C, 0.1%RH, 0.01 for other linear applications
Real time clock included
Sample Rate: Process variable sampled every 0.1 seconds
Proportional Band: Programmable 1.0° to 300°
Control Method: Digital
Intervals: Unlimited
Interval Resolution: 1 sec to 99 hrs,59 min with 1 second resolution
- RS-232
- 10+ Years Data Storage
- Product Temperature Control
- Event Relay Board
Operating Modes: Automatic or Manual
Program Storage: Unlimited
Program Loops:
- Up to 64 loops per program
Loops can be repeated up to 9,999 times program
- Up to 64 nested loops are allowed per
Smart Watch Reliability Test Conditions
In today's society, elementary school students and even kindergarten children have a smart watch. So, what is a smartwatch? In the late period of sports watch promotion due to the rapid takeoff of smart phones, the smart table has no intention to provide the same PIM effect as PDA and smart phones, and appeals to the smart phone agent assistant accessories, similar to Bluetooth headphones are voice AIDS of smart phones, smart tables become information and data AIDS, providing more convenient and fast information display and operation. There are also other names such as Smart Accessory and Android Remote. Positioned as a mobile phone assistant, the idea is that "the reason why the pocket watch is extinct is because it is simply to look at the time, but also take out the pocket, about 2-3 seconds, but the watch is less than 1 second, which is more convenient than the pocket watch." And after observation, now everyone takes out a smartphone and slides open, just to confirm the message, so that about dozens of times, these confirmation even typing reply do not need, if the dozens of confirmation changed on the watch, you do not always have to pull the machine slide unlock, because this is as time-consuming as a pocket watch. Therefore, after becoming the assistant of the mobile phone, the remote control, if you do not take the mobile phone to go out, the watch is useless in addition to showing the time, and the Bluetooth headset without a mobile phone, almost scrap metal.
Combined with smart bracelet to sell better!!
Smart watch from "smaller than the PDA independent computer" to "smart phone remote control AIDS", seems to have been a more successful positioning, but this CES 2014 can be seen, combined with smart bracelet positioning is better. The smart wristband uses acceleration sensors (and gyroscopes, magnetoresistive sensors, etc.) to sense the user's running speed, step count, etc., and can even detect deep sleep and provide suggestions for exercise and sleep. When the wristband is added to the display, it can display the time and information on the mobile phone. Appeal to mobile phone information, if there is no urgent information needs, in fact, only similar to the Bluetooth headset is regarded as an option (Courier, driver need), if everyone can accept the information access speed of sliding, then the market will be limited. However, in addition to the appeal for exercise and sleep record supervision, and emphasize information tips, rather than emphasizing the remote control of the watch on the mobile phone, it is equivalent to a little sacrifice or almost no sacrifice to the end user, but it brings immediate and new application value (sports, sleep assistance), rather than completely repeating the efficacy value of the mobile phone, which further increases the market success of the smart watch. After constantly adjusting the efficacy, application and positioning, and integrating with the smart ring, we believe that we can have a higher market than in the past.
Smart watch for people and functions:
1. Smart watches for adults
Functions: Bluetooth synchronous mobile phone calls, send and receive text messages, monitor sleep, monitor heart rate, sedentary reminder, running, remote photography, music playback, video, compass and other functions, designed for fashion trend people!
2, Smart watch for the elderly
Functions: ultra-accurate GPS positioning, family calls, emergency calls, heart rate monitoring, sedentary reminders, medicine reminders and other customized functions for the elderly, providing an umbrella for the elderly's travel, bring this watch, refuse to lose the elderly!
3, Children positioning smart watch
Functions: multiple positioning, two-way call, SOS SOS, remote monitoring, intelligent anti-loss, historical track, electronic fence, pedometer, love reward and other functions, to ensure the safety of children, give children a healthy and safe growth environment!
Smart watch specification:
IEC 60086-3: Watch batteries
ISO 105-A02: Colour fastness test -A02 - Grey scale assessment for discoloration
ISO 105-A03-1993: Tests for colour fastness -A03- Grey scale assessment of dyeing
ISO 764: Horological anti-magnetic watches
ISO 1413: Horological shockproof watches
ISO 2281: Horological waterproof watches
ISO 11641-1993: Leather - tests for colour fastness - Colour fastness to perspiration
ISO 14368-3: Impact resistance test of table glass
MIL 810G: Environmental engineering considerations and laboratory testing
QB/T 1897-1993: Waterproof watch inspection
QB/T 1898-1993: Inspection of shockproof watches
QB/T 1908-1993: Key reliability test
QB/T 1919-2012: Type inspection of digital quartz watches with hands and liquid crystal
QB/T 2047-2007: Inspection of metal watchbands
GB/T 2537-2001: leather color fastness test reciprocating grinding color fastness
QB/T 2540-2002: Leather strap inspection
GB/T 6048-1985: digital quartz electronic watch
GB/T 18761-2007: electronic digital display indicator
GB/T 18828-2002: Standard for diving watches
GB/T 22778-2008: LCD digital quartz stopwatch type inspection
GB/T 22780-2008: Type inspection of LCD quartz watches
GB/T 26716-2011 idt ISO 764-2002: Inspection of anti-magnetic watches
HJ216-2005: Eco-Drive watch
Smart watch pilot project:
Reliability, time period measurement accuracy, instantaneous daily difference, operating temperature, voltage range, average temperature coefficient, voltage coefficient, moisture resistance, shock resistance, waterproof performance, battery replacement cycle, key fatigue resistance, light and weather resistance, antistatic performance Ambient temperature range: -25℃ ~ 55℃ Operating temperature: -5 ~ 50℃/80%R.H.(Requirements: each function and liquid crystal display should be complete and normal) High and low working temperature test: 50±1℃/24h→RT/1h→-5±1℃ Temperature change test conditions: (IEC60068-2) High temperature: 30, 40, 55℃ Low temperature: 5, -5, -10, -25℃ Nb residence time (including rising and cooling time) : 10min, 30min, 1hr Nb temperature variability: 3±0.6℃/min, 5±1℃/min.
Wet heat test:
1.40±1℃/85 ~ 95%R.H./24h
2.8±1℃/85 ~ 95%R.H./4h
Warehouse storage humidity test:
40℃/20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%
49℃/10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%
Each step37 hours
Air transport temperature change simulation test:
Specification: IEC60721.2 Electrical and electronic products application environmental conditions - transport national standard
Category: 2K5 (Applicable to the climatic range of unventilated and unpressurized internal transport worldwide)
Temperature range: -65℃←→85℃
RAMP: 5℃/min
Air transport temperature change simulation test:
Specification: IEC60721.6 Electrical and electronic products application environmental conditions - Marine
Category: 6K5 (subject to cold weather, installed in weather-protected but unheated parts)
Temperature range: -25℃←→40℃
RAMP: 3℃/min
Water temperature change resistance test:
5min in 40℃ water → 5min in 20℃ water, 5min in 40℃ water, water depth of 10cm
Water pressure resistance test:
Soak the watch in a container of water, apply an overpressure of 2*10^5Pa[or 20m water depth] within 1 minute, maintain 10 minutes, and then in 1 minute the pressure will be to the standard pressure of the surrounding environment
Salt water resistance test:
Put the watch under test into 30g/L sodium chloride solution at 18 ° C ~ 25 ° C for 24h. Check the case and accessories after the test should not have significant changes; Check the moving parts, especially the rotating front ring should be able to maintain normal function
Underwater reliability test:
The watch under test is immersed in 30cm±2cm of water and placed at a temperature of 18 ° C ~ 25 ° C for 50h, and all mechanical devices should still work normally. During the test, mechanical devices that need to be operated in water, such as time presetting devices and light switches, should be able to work normally; Do condensation test, the inner surface of the table glass shall not appear condensation fog, and the mechanical function should not be damaged
Thermal shock resistance test:
Immerse the watch in water of different temperatures with a depth of 30cm±2cm successively: place it in water of 40 ° C ±2 ° C for 10 minutes; Put in 5℃±2℃ water for 10 minutes; Put in water at 40 ° C ± 2 ° C for 10 minutes (the watch shall not be removed from the water and re-immersed in another water temperature for more than 1 minute). Do condensation test, the inner surface of the table glass shall not appear condensation fog, and should operate normally.
Chemical resistance test:
Citation Specifications: ASTM F 1598-95, ASTM D 1308-87, ASTM D 1308-02
Ingredients: Household chemicals (dirt, dust, oil, fumes and peanut butter, cosmetics, hand cream... Etc.)
Time: 24 hours
Corrosion resistance to artificial sweat test:
QB/T 1901.2-2006 "Gold alloy covers of shell and its accessories - Part 2 Test for purity, thickness, corrosion resistance and adhesion"
Test principle: The artificial sweat is used to contact the object under high temperature (40±2) ℃, and after a long time (not less than 24 hours), the condition of its surface is observed to determine its resistance to sweat corrosion.
Vibration test:
Acceleration (19.6m/s^2), frequency 30Hz ~ 120Hz, scanning cycle 1min
Requirements: The functions and the LCD display should be complete and normal, and the parts should not be loose and fall off
Drop test:
1m drop lithographic hardwood, once watch side, once surface glass
Requirements: Normal function after each impact, no appearance damage [broken glass, case foot bent, case component bent, case broken, button damaged]
Impact test:
Impact cone pad material: polytetrafluoroethylene, impact speed 4.43m/s, impact height 1m
Arm swing test:
2 to 10Hz
Natural Convection Test (No Wind Circulation Temperature Test) and Specification
Home entertainment audio-visual equipment and automotive electronics are one of the key products of many manufacturers, and the product in the development process must simulate the adaptability of the product to temperature and electronic characteristics at different temperatures. However, when the general oven or constant temperature and humidity test chamber is used to simulate the temperature environment, both the oven and constant temperature and humidity test chamber have a test area equipped with a circulating fan, so there will be wind speed problems in the test area. During the test, the temperature uniformity is balanced by rotating the circulating fan. Although the temperature uniformity of the test area can be achieved through the wind circulation, the heat of the product to be tested will also be taken away by the circulating air, which will be significantly inconsistent with the actual product in the wind-free use environment (such as the living room, indoor). Because of the relationship of wind circulation, the temperature difference of the product to be tested will be nearly 10 ° C, in order to simulate the actual use of environmental conditions, many people will misunderstand that only the test machine can produce temperature (such as: oven, constant temperature and humidity test chamber) can carry out natural convection test, in fact, this is not the case. In the specification, there are special requirements for wind speed, and a test environment without wind speed is required. Through the natural convection test equipment (no forced wind circulation test), the temperature environment without fan is generated (natural convection test), and then the test integration test is carried out to detect the temperature of the product under test. This solution can be applied to the actual ambient temperature test of household related electronic products or confined Spaces (such as: Large LCD TV, car cockpit, car electronics, laptop, desktop computer, game console, stereo... Etc.).
The difference of the test environment with or without wind circulation for the test of the product to be tested:
If the product to be tested is not energized, the product to be tested will not heat itself, its heat source only absorbs the air heat in the test furnace, and if the product to be tested is energized and heated, the wind circulation in the test furnace will take away the heat of the product to be tested. Every 1 meter increase in wind speed, its heat will be reduced by about 10%. Suppose to simulate the temperature characteristics of electronic products in an indoor environment without air conditioning, if an oven or a constant temperature and humidity test chamber is used to simulate 35 ° C, although the environment in the test area can be controlled within 35 ° C through electric heating and freezing, the wind circulation of the oven and the constant temperature and humidity test chamber will take away the heat of the product to be tested, making the actual temperature of the product to be tested lower than the temperature in the real state of no wind. Therefore, it is necessary to use a natural convection testing machine without wind speed to effectively simulate the actual windless environment (such as: indoor, non-starting car cockpit, instrument chassis, outdoor waterproof box... Such environment).
Indoor environment without wind circulation and solar radiant heat irradiation:
Through the natural convection tester, simulate the client's actual use of the real air conditioning convection environment, hot spot analysis and heat dissipation characteristics of the product evaluation, such as the LCD TV in the photo not only to consider its own heat dissipation, but also to evaluate the impact of thermal radiation outside the window, thermal radiation for the product may produce additional radiant heat above 35 ° C.
Comparison table of wind speed and IC product to be tested:
When the ambient wind speed is faster, the IC surface temperature will also take away the IC surface heat due to the wind cycle, resulting in faster wind speed and lower temperature, when the wind speed is 0, the temperature is 100℃, but when the wind speed reaches 5m/s, the IC surface temperature has been below 80℃.
Unforced air circulation test:
According to the specification requirements of IEC60068-2-2, in the high temperature test process, it is necessary to carry out the test conditions without forced air circulation, the test process needs to be maintained under the wind-free circulation component, and the high temperature test is carried out in the test furnace, so the test cannot be carried out through the constant temperature and humidity test chamber or oven, and the natural convection tester can be used to simulate the free air conditions.
Description of test conditions:
Test specification for unforced air circulation: IEC-68-2-2, GB2423.2, GB2423.2-89 3.3.1
Unforced air circulation test: The test condition of unforced air circulation can simulate the free air condition well
GB2423.2-89 3.1.1:
When measuring under free air conditions, when the temperature of the test sample is stable, the temperature of the most hot spot on the surface is more than 5℃ higher than the temperature of the surrounding large device, it is a heat dissipation test sample, otherwise it is a non-heat dissipation test sample.
GB2423.2-8 10(Test heat dissipation test sample temperature gradient test) :
A standard test procedure is provided to determine the adaptability of thermal electronic products (including components, equipment level other products) to use at high temperatures.
Test requirements:
a. Testing machine without forced air circulation (equipped with a fan or blower)
b. Single test sample
c. The heating rate is not greater than 1℃/min
d. After the temperature of the test sample reaches stability, the test sample is energized or the home electrical load is carried out to detect the electrical performance
Natural convection test chamber features:
1. Can evaluate the heat output of the product to be tested after power, to provide the best distribution uniformity;
2. Combined with digital data collector, effectively measure the relevant temperature information of the product to be tested for synchronous multi-track analysis;
3. Record the information of more than 20 rails (synchronous record the temperature distribution inside the test furnace, multi-track temperature of the product to be tested, average temperature... Etc.).
4. The controller can directly display the multi-track temperature record value and record curve; Multi-track test curves can be stored on a USB drive via the controller;
5. The curve analysis software can intuitively display the multi-track temperature curve and output EXCEL reports, and the controller has three kinds of display [Complex English];
6. Multi-type thermocouple temperature sensor selection (B, E, J, K, N, R, S, T);
7. Scalable to increase heating rate & control stability planning.
Temperature Cyclic Stress Screening (2)
Introduction of stress parameters for temperature cyclic stress screening:
The stress parameters of temperature cyclic stress screening mainly include the following: high and low temperature extremum range, dwell time, temperature variability, cycle number
High and low temperature extremal range: the larger the range of high and low temperature extremal, the fewer cycles required, the lower the cost, but can not exceed the product can withstand the limit, do not cause new fault principle, the difference between the upper and lower limits of temperature change is not less than 88°C, the typical range of change is -54°C to 55°C.
Dwell time: In addition, the dwell time can not be too short, otherwise it is too late to make the product under test produce thermal expansion and contraction stress changes, as for the dwell time, the dwell time of different products is different, you can refer to the relevant specification requirements.
Number of cycles: As for the number of cycles of temperature cyclic stress screening, it is also determined by considering product characteristics, complexity, upper and lower limits of temperature and screening rate, and the screening number should not be exceeded, otherwise it will cause unnecessary harm to the product and cannot improve the screening rate. The number of temperature cycles ranges from 1 to 10 cycles [ordinary screening, primary screening] to 20 to 60 cycles [precision screening, secondary screening], for the removal of the most likely workmanship defects, about 6 to 10 cycles can be effectively removed, in addition to the effectiveness of the temperature cycle, Mainly depends on the temperature variation of the product surface, rather than the temperature variation inside the test box.
There are seven main influencing parameters of temperature cycle:
(1) Temperature Range
(2) Number of Cycles
(3) Temperature Rate of Chang
(4) Dwell Time
(5) Airflow Velocities
(6) Uniformity of Stress
(7) Function test or not (Product Operating Condition)
Stress screening fatigue classification:
The general classification of Fatigue research can be divided into High-cycle Fatigue, Low-cycle Fatigue and Fatigue Crack Growth. In the aspect of low cycle Fatigue, it can be subdivided into Thermal Fatigue and Isothermal Fatigue.
Stress screening acronyms:
ESS: Environmental stress screening
FBT: Function board tester
ICA: Circuit analyzer
ICT: Circuit tester
LBS: load board short-circuit tester
MTBF: mean time between failures
Time of temperature cycles:
a.MIL-STD-2164(GJB 1302-90) : In the defect removal test, the number of temperature cycles is 10, 12 times, and in the trouble-free detection it is 10 ~ 20 times or 12 ~ 24 times. In order to remove the most likely workmanship defects, about 6 ~ 10 cycles are needed to effectively remove them. 1 ~ 10 cycles [general screening, primary screening], 20 ~ 60 cycles [precision screening, secondary screening].
B.od-hdbk-344 (GJB/DZ34) Initial screening equipment and unit level uses 10 to 20 loops (usually ≧10), component level uses 20 to 40 loops (usually ≧25).
Temperature variability:
a.MIL-STD-2164(GJB1032) clearly states: [Temperature change rate of temperature cycle 5℃/min]
B.od-hdbk-344 (GJB/DZ34) Component level 15 ° C /min, system 5 ° C /min
c. Temperature cyclic stress screening is generally not specified temperature variability, and its commonly used degree variation rate is usually 5°C/min
IEC-60068-2 Combined Test of Condensation and Temperature and Humidity
Difference of IEC60068-2 damp heat test specifications
In the IEC60068-2 specification, there are a total of five kinds of humid heat tests, in addition to the common 85℃/85%R.H., 40℃/93%R.H. In addition to fixed-point high temperature and high humidity, there are two more special tests [IEC60068-2-30, IEC60068-2-38], these two are alternating wet and humid cycle and temperature and humidity combined cycle, so the test process will change temperature and humidity, and even multiple groups of program links and cycles, applied in IC semiconductors, parts, equipment, etc. To simulate the outdoor condensation phenomenon, evaluate the material's ability to prevent water and gas diffusion, and accelerate the product's tolerance to deterioration, the five specifications were organized into a comparison table of the differences in the wet and heat test specifications, and the test points were explained in detail for the wet and heat combined cycle test, and the test conditions and points of GJB in the wet and heat test were supplemented.
IEC60068-2-30 alternating humid heat cycle test
This test uses the test technique of maintaining humidity and temperature alternating to make moisture penetrate into the sample and cause condensation (condensation) on the surface of the product to be tested, so as to confirm the adaptability of the component, equipment or other products in use, transportation and storage under the combination of high humidity and temperature and humidity cyclic changes. This specification is also suitable for large test samples. If the equipment and the test process need to keep the power heating components for this test, the effect will be better than IEC60068-2-38, the high temperature used in this test has two (40 ° C, 55 ° C), the 40 ° C is to meet most of the world's high temperature environment, while 55 ° C meets all the world's high temperature environment, the test conditions are also divided into [cycle 1, cycle 2], In terms of severity, [Cycle 1] is higher than [Cycle 2].
Suitable for side products: components, equipment, various types of products to be tested
Test environment: the combination of high humidity and temperature cyclic changes produces condensation, and three kinds of environments can be tested [use, storage, transportation ([packaging is optional)]
Test stress: Breathing causes water vapor to invade
Whether power is available: Yes
Not suitable for: parts that are too light and too small
Test process and post-test inspection and observation: check the electrical changes after moisture [do not take out the intermediate inspection]
Test conditions: Humidity: 95%R.H.[Temperature change after high humidity maintenance](low temperature 25±3℃←→ high temperature 40℃ or 55℃)
Rising and cooling rate: heating (0.14℃/min), cooling (0.08 ~ 0.16℃/min)
Cycle 1: Where absorption and respiratory effects are important features, the test sample is more complex [humidity not less than 90%R.H.]
Cycle 2: In the case of less obvious absorption and respiratory effects, the test sample is simpler [humidity is not less than 80%R.H.]
IEC60068-2 damp heat test specification difference comparison table
For component type parts products, a combination test method is used to accelerate the confirmation of the test sample's resistance to degradation under high temperature, high humidity and low temperature conditions. This test method is different from the product defects caused by respiration [dew, moisture absorption] of IEC60068-2-30. The severity of this test is higher than that of other humid heat cycle tests, because there are more temperature changes and [respiration] during the test, the cycle temperature range is larger [from 55℃ to 65℃], and the temperature change rate of the temperature cycle is faster [temperature rise: 0.14 ° C /min becomes 0.38 ° C /min, 0.08 ° C /min becomes 1.16 ° C /min], in addition, different from the general humid heat cycle, the low temperature cycle condition of -10 ° C is added to accelerate the breathing rate and make the water condensed in the gap of the substitute freeze, which is the characteristic of this test specification. The test process allows the power test and the applied load power test, but it can not affect the test conditions (temperature and humidity fluctuation, rising and cooling rate) because of the heating of the side product after power. Due to the change of temperature and humidity during the test process, there can not be condensation water droplets on the top of the test chamber to the side product.
Suitable for side products: components, metal components sealing, lead end sealing
Test environment: combination of high temperature, high humidity and low temperature conditions
Test stress: accelerated breathing + frozen water
Whether it can be powered on: it can be powered on and external electric load (it can not affect the conditions of the test chamber because of power heating)
Not applicable: Can not replace moist heat and alternating humid heat, this test is used to produce defects different from respiration
Test process and post-test inspection and observation: check the electrical changes after moisture [check under high humidity conditions and take out after test]
Test conditions: damp heat cycle (25 please - 65 + 2 ℃ / 93 + / - 3% R.H.) please - low temperature cycle (25 please - 65 + 2 ℃ / 93 + 3% R.H. - - 10 + 2 ℃) X5cycle = 10 cycle
Rising and cooling rate: heating (0.38℃/min), cooling (1.16 ℃/min)
Heat and humidity cycle (25←→65±2℃/93±3%R.H.)
Low temperature cycle (25←→65±2℃/93±3%R.H. →-10±2℃)
GJB150-09 damp heat test
Instructions: The wet and heat test of GJB150-09 is to confirm the ability of equipment to withstand the influence of hot and humid atmosphere, suitable for equipment stored and used in hot and humid environments, equipment prone to high humidity, or equipment that may have potential problems related to heat and humidity. Hot and humid locations can occur throughout the year in the tropics, seasonally in mid-latitudes, and in equipment subjected to combined pressure, temperature and humidity changes, with special emphasis on 60 ° C /95%R.H. This high temperature and humidity does not occur in nature, nor does it simulate the dampness and heat effect after solar radiation, but it can find the parts of the equipment with potential problems, but it cannot reproduce the complex temperature and humidity environment, evaluate the long-term effect, and can not reproduce the humidity impact related to the low humidity environment.
Relevant equipment for condensation, wet freezing, wet heat combined cycle test: constant temperature and humidity test chamber
Purpose of Temperature Shock Test
Reliability environmental test In addition to high Temperature, low temperature, high temperature and high humidity, temperature and humidity combined cycle, temperature Shock (cold and hot Shock) is also a common test project, temperature shock Testing (Thermal Shock Testing, Temperature Shock Testing, referred to as: TST), the purpose of the temperature shock test is to find out the design and process defects of the product through the severe temperature changes that exceed the natural environment [temperature variability greater than 20℃/min, and even up to 30 ~ 40℃/min], but there is often a situation where the temperature cycle is confused with the temperature shock. "Temperature cycle" means that in the process of high and low temperature change, the temperature change rate is specified and controlled; The temperature change rate of "temperature shock" (hot and cold shock) is not specified (Ramp Time), mainly requires Recovery Time, according to the IEC specification, there are three kinds of temperature cycle test methods [Na, Nb, NC]. Thermal shock is one of the three [Na] test items [rapid temperature change with specified conversion time; medium: air], the main parameters of temperature shock (thermal shock) are: High temperature and low temperature conditions, residence time, return time, number of cycles, in high and low temperature conditions and residence time the current new specification will be based on the surface temperature of the test product, rather than the air temperature in the test area of the test equipment.
Thermal shock test chamber:
It is used to test the material structure or composite material, in an instant under the continuous environment of extremely high temperature and extremely low temperature, the degree of tolerance, so as to test the chemical changes or physical damage caused by thermal expansion and contraction in the shortest time, the applicable objects include metal, plastic, rubber, electronic.... Such materials can be used as the basis or reference for the improvement of its products.
The cold and thermal shock (temperature shock) test process can identify the following product defects:
Different expansion coefficient caused by the stripping of the joint
Water enters after cracking with different expansion coefficient
Accelerated test for corrosion and short circuit caused by water infiltration
According to the international standard IEC, the following conditions are common temperature changes:
1. When the equipment is transferred from a warm indoor environment to a cold outdoor environment, or vice versa
2. When the equipment is suddenly cooled by rain or cold water
3. Installed in the outside airborne equipment (such as: automobile, 5G, outdoor monitoring system, solar energy)
4. Under certain transport [car, ship, air] and storage conditions [non-air-conditioned warehouse]
Temperature impact can be divided into two types of two-box impact and three-box impact:
Instructions: Temperature impact is common [high temperature → low temperature, low temperature → high temperature] way, this way is also called [two-box impact], another so-called [three-box impact], the process is [high temperature → normal temperature → low temperature, low temperature → normal temperature → high temperature], inserted between the high temperature and low temperature, to avoid adding a buffer between the two extreme temperatures. If you look at the specifications and test conditions, there is usually a normal temperature condition, the high and low temperature will be extremely high and very low, in the military specifications and vehicle regulations will see that there is a normal temperature impact condition.
IEC temperature shock test conditions:
High temperature: 30, 40, 55, 70, 85, 100, 125, 155℃
Low temperature: 5, -5, -10, -25, -40, -55, -65℃
Residence time: 10min, 30min, 1hr, 2hr, 3hr(if not specified, 3hr)
Temperature shock residence time description:
The Dwell Time of temperature shock in addition to the requirements of the specification, some will depend on the weight of the test product and the surface temperature of the test product
The specifications of the thermal shock residence time according to weight are:
GJB360A-96-107, MIL-202F-107, EIAJ ED4701/100, JASO-D001... Let's wait.
The thermal shock residence time is based on the surface temperature control specifications: MIL-STD-883K, MIL-STD-202H(air above the test object)
MIL883K-2016 requirements for [temperature shock] specification:
1. After the air temperature reaches the set value, the surface of the test product needs to arrive within 16 minutes (residence time is not less than 10min).
2. High temperature and low temperature impact are more than the set value, but not more than 10℃.
Follow-up action of IEC temperature shock test
Reason: The IEC temperature test method is best considered as part of a series of tests, because some failures may not be immediately apparent after the test method is completed.
Follow-up test items:
IEC60068-2-17 Tightness test
IEC60068-2-6 Sinusoidal vibration
IEC60068-2-78 Steady Humid heat
IEC60068-2-30 Hot and humid temperature cycle
Tin whisker (whisker) temperature impact test conditions finishing:
1. - 55 (+ 0 / -) 10 ℃ please - 85 (+ / - 0) 10 ℃, 20 min / 1 cycle (500 cycle check again)
1000 cycles, 1500 cycles, 2000 cycles, 3000 cycles
2. 85(±5)℃←→-40(+5/-15)℃, 20min/1cycle, 500cycles
3.-35±5℃←→125±5℃, dwell for 7min, 500±4cycles
4. - 55 (+ 0 / -) 10 ℃ please - 80 (+ / - 0) 10 ℃, 7 min reside, 20 min / 1 cycle, 1000 cycles
Thermal shock testing machine product features:
Defrosting frequency: defrosting every 600cycles [Test condition: +150℃ ~ -55℃]
Load adjustment function: The system can automatically adjust according to the load of the product to be tested, without manual setting
High weight load: Before the equipment leaves the factory, use aluminum IC(7.5Kg) for load simulation to confirm that the equipment can meet the demand
Temperature shock Sensor location: The air outlet and return air outlet in the test area can be selected or both can be installed, which conforms to the MIL-STD test specification. In addition to meeting the requirements of the specification, it is also closer to the impact effect of the test product during the test, reducing the test uncertainty and distribution uniformity.
VMR- plate Temperature Cycle Transient Break Test
Temperature cycle test is one of the most commonly used methods for reliability and life test of lead-free welding materials and SMD parts. It evaluates the adhesive parts and solder joints on the surface of SMD, and causes plastic deformation and mechanical fatigue of solder joints materials under the fatigue effect of cold and hot temperature cycle with controlled temperature variability, so as to understand the potential hazards and failure factors of solder joints and SMD. The Daisy chain diagram is connected between the parts and the solder joints. The test process detects the on-off and on-off between the lines, parts and solder joints through the high-speed instantaneous break measuring system, which meets the demand for the reliability test of electrical connections to evaluate whether the solder joints, tin balls and parts fail. This test is not really simulated. Its purpose is to apply severe stress and accelerate the aging factor on the object to be tested to confirm whether the product is designed or manufactured correctly, and then evaluate the thermal fatigue life of the component solder joints. The reliability test of the electrical high-speed instantaneous break connection has become a key link to ensure the normal operation of the electronic system and avoid the failure of the electrical connection caused by the failure of the immature system. The resistance changes over a short period of time were observed under accelerated temperature changes and vibration tests.
Purpose:
1. Ensure that products designed, manufactured and assembled meet predetermined requirements
2. Relaxation of solder joint creep stress and SMD fracture failure caused by thermal expansion difference
3. The maximum test temperature of the temperature cycle should be 25℃ lower than the Tg temperature of the PCB material, so as to avoid more than one damage mechanism of the substitute test product
4. Temperature variability at 20℃/min is a temperature cycle, and temperature variability above 20℃/min is a temperature shock
5. The welding joint dynamic measurement interval does not exceed 1min
6. The high temperature and low temperature residence time for failure determination needs to be measured in 5 strokes
Requirements:
1. The total temperature time of the test product is within the range of the rated maximum temperature and the minimum temperature, and the length of the residence time is very important for the accelerated test, because the residence time is not enough during the accelerated test, which will make the creep process incomplete
2. The resident temperature must be higher than Tmax temperature and lower than Tmin temperature
Refer to the list of specifications:
IPC-9701, IPC650-2.6.26, IPC-SM-785, IPCD-279, J-STD-001, J-STD-002, J-STD-003, JESD22-A104, JESD22-B111, JESD22-B113, JESD22-B117 , SJR-01
Inverter- Reliability Test
Inverter- reliability test also known as voltage converter, its function is to convert DC low voltage into AC high voltage, some electronic equipment must be driven by AC power, but we provide is DC power, at this time you must use the Inverter, direct current into alternating current to drive the electronic parts. Inverter- reliability test also known as voltage converter, its function is to convert DC low voltage into AC high voltage, some electronic equipment must be driven by AC power, but we provide is DC power, at this time you must use the Inverter, direct current into alternating current to drive the electronic parts.
Relevant test conditions:
Item
temperature
time
other
Initial test at normal temperature
25 ℃
TIME≥2 hours
-
Low temperature initial test
0 ℃ or -5 °C
TIME≥2 hours
-
High temperature initial test
60℃
TIME≥2 hours
-
High temperature and high humidity test
40℃/95%RH
240 hours
-
High temperature storage test
70℃
TIME≥96 hours or 240 hours
-
Low temperature storage test -1
-20°C
TIME≥96 hours
-
Low temperature storage test -2
-40℃
240 hours
-
High temperature and high humidity storage test
40℃/90%RH
TIME≥96 hours
-
Temperature cycle test
-20℃~ 70℃
5 cycle
Room temperature ↓-20 ℃(4 hours)↓ Room temperature (90%RH.4 hours)↓70°C(4 hours)↓ Room temperature (4 hours)
High temperature load test
55 ℃
equivalent load, 1,000 hours
-
Life test
40°C
MTBF≥40000 hours
-
on/off test (power cycle)
-
-
1min:on, 1min:off, 5,000 cycles using equivalent load
Vibration test
-
-
Acceleration 3q, frequency 10~55HZ, X, Y, Z three directions 10 minutes each, a total of 30 minutes
Impact test
-
-
Acceleration of 80g, 10 ms each time, Three times in X, Y, Z directions
Note 1: The tested module should be placed at normal (15~35° C,45~65%RH) for one hour before testing
Applicable equipment:
1. High and low temperature test chamber
2. High temperature and high humidity test chamber
3. Rapid temperature cycle test chamber
Application of TCT Temperature Cycle Chamber in Optical Communication Industry
The arrival of 5G makes people feel the rapid development of mobile Internet, and optical communication technology as an important basis has also been developed. At present, China has built the world's longest optical fiber network, and with the continuous advancement of 5G technology, optical communication technology will be more widely used. The development of optical communication technology not only allows people to enjoy faster network speed, but also brings more opportunities and challenges. For example, new applications such as cloud gaming, VR, and AR require more stable and high-speed networks, and optical communication technology can meet these needs. At the same time, optical communication technology has also brought more innovation opportunities, such as intelligent medical care, intelligent manufacturing and other fields, will use optical communication technology to achieve more efficient and accurate operation. But you know what? This amazing technology cannot be achieved without the credit of macro environmental test equipment, especially the TC temperature cycle test chamber, which is a rapid temperature change test chamber. This article introduces you to the optical communication product reliability test quality manager - rapid temperature change laboratory.
First, let's talk briefly about optical communication. Some people also say that it is called optical communication, so they are two in the end is not a concept. In fact, they are two of the same concept. Optical communication is the use of optical signals for communication technology, and optical communication is based on optical communication, through optical devices such as optical fibers, optical cables to achieve data transmission. Optical communication technology is widely used, such as our daily use of fiber optic broadband, mobile phone optical sensors, optical measurement in aerospace and so on. It can be said that optical communication has become an important part of modern communication field. So why is optical communication so popular? In fact, it has many advantages, such as high-speed transmission, large bandwidth, low loss and so on.
Common optical communication products include: optical cable, fiber switch, fiber modem, etc., used to transmit and receive optical signals of optical fiber communication equipment; Temperature sensor, strain sensor, displacement sensor, etc., can measure various physical quantities in real time and other optical fiber sensors; Erbium-doped optical amplifier, erbium-doped ytterbium-doped optical amplifier, Raman amplifier, etc., used to expand the intensity of optical signals and other optical amplifiers; Helium-neon laser, diode laser, fiber laser, etc., are light sources in optical communication, used to produce high brightness, directional and coherent laser light and other lasers; Photodetectors, optical limiter, photodiodes, etc., for receiving optical signals and converting them into electrical signals and other optical receivers; Optical switches, optical modulators, programmable optical arrays, etc. are used to control and adjust optical signal transmission and routing and other optical controllers. Let's take mobile phones as an example and talk about the application of optical communication products on mobile phones:
1. Optical fiber: Optical fiber is generally used as a part of the communication line, due to its fast transmission speed, communication signals are not easily affected by external interference and other characteristics, has become an important part of mobile phone communication.
2. Photoelectric converter/optical module: photoelectric converter and optical module are devices that convert optical signals into electrical signals, and are also a very important part of mobile phone communication. In the era of high-speed communication such as 4G and 5G, the speed and performance of such equipment need to be continuously improved to meet the needs of fast and stable communication.
3. Camera module: In the mobile phone, the camera module generally includes CCD, CMOS, optical lens and other parts, and its quality and performance also have a significant impact on the quality of optical communication of the mobile phone.
4. Display: Mobile phone displays generally use OLED, AMOLED and other technologies, the principle of these technologies are related to optics, but also an important part of mobile phone optical communication.
5. Light sensor: Light sensor is mainly used in mobile phones for environmental light sensing, proximity sensing and gesture sensing, and is also an important mobile phone optical communication product.
It can be said that optical communication products fill all aspects of our life and work. However, the production and use environment of optical communication products is often changeable, such as high or low temperature weather environment when working outdoors, or the use of a long time will also encounter changes in thermal expansion and contraction. So how is the reliable use of these products achieved? That has to mention our protagonist today - rapid temperature change test chamber, also known as TC box in the optical communication industry. In order to ensure that optical communication products still work normally under various environmental conditions, it is necessary to carry out rapid temperature change tests on optical communication products. The rapid temperature change test chamber can simulate a variety of different temperature and humidity environments, and simulate instantaneous extreme environmental changes in the real world within a rapid range. So how is the rapid temperature change test chamber applied in the optical communication industry?
1. Optical module performance test: Optical module is a key component of optical communication, such as optical transceiver, optical amplifier, optical switch, etc. The rapid temperature change test chamber can simulate different temperature environments and test the performance of the optical module at different temperatures to evaluate its adaptability and reliability.
2. Reliability test of optical devices: optical devices include optical fibers, optical sensors, grating, photonic crystals, photodiodes, etc. The rapid temperature change test chamber can test the temperature change of these optical devices and evaluate their reliability and life based on the test results.
3. Optical communication system simulation test: The rapid temperature change test chamber can simulate various environmental conditions in the optical communication system, such as temperature, humidity, vibration, etc., to test the performance, reliability and stability of the entire system.
4. Technology research and development: The optical communication industry is a technology-intensive industry, which needs to constantly develop new technologies and new products. The rapid temperature change test chamber can be used to test the performance and reliability of new products, helping to accelerate the development and market of new products.
In summary, it can be seen that in the optical communication industry, the rapid temperature change test chamber is usually used to test the performance and reliability of optical modules and optical devices. Then when we use the rapid temperature change test chamber for testing, different optical communication products may require different standards. The following are rapid temperature change test standards for some common optical communication products:
1. Optical fiber: Common test standards There are common optical fiber rapid temperature change test standards are the following: IEC 61300-2-22: The standard defines the stability and durability test method of optical fiber components, section 4.3 of which specifies the thermal stability test method of optical fiber components, in the case of rapid temperature changes to the optical fiber components for measurement and evaluation. GR-326-CORE: This standard specifies reliability test requirements for fiber optic connectors and adapters, including thermal stability tests to assess the reliability of fiber optic connectors and adapters in temperature changing environments. GR-468-CORE: This standard defines the performance specifications and test methods for fiber optic connectors, including temperature cycle testing, accelerated aging testing, etc., to verify the reliability and stability of fiber optic connectors under various environmental conditions. ASTM F2181: This standard defines a method for fiber failure testing under high temperature and high humidity environmental conditions to evaluate the long-term durability of the fiber. And the above standards such as GB/T 2423.22-2012 are tested and evaluated for the reliability of optical fiber in rapid temperature changes or long-term high temperature and high humidity environments, which can help the majority of manufacturers to ensure the quality and reliability of optical fiber products.
2. Photoelectric converter/optical module: The common rapid temperature change test standards are GB/T 2423.22-2012, GR-468-CORE, EIA/TIA-455-14 and IEEE 802.3. These standards mainly cover the test methods and specific implementation steps of photoelectric converters/optical modules, which can ensure the performance and reliability of products in different temperature environments. Among them, the GR-468-CORE standard is specifically for the reliability requirements of optical converters and optical modules, including temperature cycle test, wet heat test and other environmental tests, requiring optical converters and optical modules to maintain stable and reliable performance in long-term use.
3. Optical sensor: The common rapid temperature change test standards are GB/T 27726-2011, IEC 61300-2-43 and IEC 61300-2-6. These standards mainly cover the test methods and specific implementation steps of the temperature change test of the optical sensor, which can ensure the performance and reliability of the product in different temperature environments. Among them, the GB/T 27726-2011 standard is the standard for the performance test method of optical sensors in China, including the environmental test method of optical fiber sensors, which requires the optical sensor to maintain stable performance in a variety of working environments. IEC 60749-15 standard is the international standard for the temperature cycle test of electronic components, and it also has reference value for the rapid temperature change test of optical sensors.
4. Laser: Common rapid temperature change test standards are GB/T 2423.22-2012 "Electrical and electronic products environmental test Part 2: Test Nb: temperature cycle test", GB/T 2423.38-2002 "Basic test methods for electrical components Part 38: Temperature resistance test (IEC 60068-2-2), GB/T 13979-2009 "Laser product Performance test method", IEC 60825-1, IEC/TR 61282-10 and other standards mainly cover the laser temperature change test method and specific implementation steps. It can ensure the performance and reliability of products in different temperature environments. Among them, the GB/T 13979-2009 standard is the standard for the performance test method of laser products in China, including the environmental test method of the laser under temperature changes, requiring the laser to maintain stable performance in a variety of working environments. The IEC 60825-1 standard is a specification for the integrity of laser products, and there are also relevant provisions for the rapid temperature change test of lasers. In addition, the IEC/TR 61282-10 standard is one of the guidelines for the design of optical fiber communication systems, which includes methods for the environmental protection of lasers.
5. Optical controller: The common fast temperature change test standards are GR-1209-CORE and GR-1221-CORE. GR-1209-CORE is a reliability standard for optical fiber equipment, mainly for the reliability test of optical connections, and specifies the reliability experiment of optical connection systems. Among them, the rapid temperature cycle (FTC) is one of the test projects, which is to test the reliability of optical fiber modules under rapidly changing temperature conditions. During the test, the optical controller needs to perform temperature cycling in the range of -40 ° C to 85 ° C. During the temperature cycle, the module should maintain normal function and not produce abnormal output, and the test time is 100 temperature cycles. GR-1221-CORE is a reliability standard for fiber optic passive devices and is suitable for the testing of passive devices. Among them, the temperature cycle test is one of the test items, which also requires the optical controller to be tested in the range of -40 ° C to 85 ° C, and the test time is 100 cycles. Both of these standards specify the reliability test of the optical controller in the environment of temperature change, which can determine the stability and reliability of the optical controller under harsh environmental conditions.
In general, different rapid temperature change test standards may focus on different test parameters and test methods, it is recommended to choose the corresponding test standards according to the use of specific products.
Recently, when we discuss the reliability verification of optical modules, there is a contradictory indicator, the number of temperature cycles of optical module verification, there are 10 times, and 20 times, 100 times, or even 500 times.
Frequency definitions in two industry standards:
The references to these standards have clear sources and are correct.
For the 5G forward optical module, our opinion is that the number of cycles is 500, and the temperature is set at -40 °C ~85 °C
The following is the description of the 10/20/100/500 above in the original text of GR-468(2004)
Because of the limited space, this article introduces the use of rapid temperature change test chamber in the optical communication industry. If you have any questions when using rapid temperature change test chamber and other environmental test equipment, welcome to discuss with us and learn together.
Comparison of Climatic Test and Environmental Test
Climate environment test -- constant temperature and humidity test chamber, high and low temperature test chamber, cold and hot shock test chamber, wet and heat alternating test chamber, rapid temperature change test chamber, linear temperature change test chamber, walk-in constant temperature and humidity test chamber, etc. They all involve temperature control.
Because there are multiple temperature control points to choose from, the climate chamber temperature control method also has three solutions: inlet temperature control, product temperature control and "cascade" temperature control. The first two are single-point temperature control, and the third is two-parameter temperature control.
Single point temperature control method has been very mature and widely used.
Most of the early control methods were "ping-pong" switch control, commonly known as heating when it's cold and cooling when it's hot. This control mode is a feedback control mode. When the temperature of the circulating air flow is higher than the set temperature, the electromagnetic valve of refrigeration is opened to deliver cold volume to the circulating air flow and reduce the temperature of the air flow. Otherwise, the circuit switch of the heating device is switched on to directly heat the circulating air flow. Raise the temperature of the air stream. This control mode requires that the refrigeration device and heating components of the test chamber are always in a standby working state, which not only wastes a lot of energy, but also the controlled parameter (temperature) is always in an "oscillation" state, and the control accuracy is not high.
Now the single-point temperature control method is mostly changed to the universal proportional differential integral (PID) control method, which can give the controlled temperature correction according to the past change of the controlled parameter (integral control) and the change trend (differential control), which not only saves energy, but also the "oscillation" amplitude is small and the control accuracy is high.
Dual-parameter temperature control is to collect the temperature value of the air inlet of the test chamber and the temperature value near the product at the same time. The air inlet of the test chamber is very close to the installation position of the evaporator and heater in the air modulation room, and its magnitude directly reflects the air modulation result. Using this temperature value as the feedback control parameter has the advantage of quickly modulating the status parameters of the circulating air.
The temperature value near the product indicates the real temperature environmental conditions suffered by the product, which is the requirement of the environmental test specification. Using this temperature value as the parameter of feedback control can ensure the effectiveness and credibility of the temperature environmental test, so this approach takes into account the advantages of both and the requirements of the actual test. The dual-parameter temperature control strategy can be the independent "time-sharing control" of the two groups of temperature data, or the weighted two temperature values can be combined into one temperature value as a feedback control signal according to a certain weighting coefficient, and the value of the weighting coefficient is related to the size of the test chamber, the wind speed of the circulating air flow, the size of the temperature change rate, the heat output of the product work and other parameters.
Because heat transfer is a complex dynamic physical process, and is greatly affected by the atmospheric environment conditions around the test chamber, the working state of the tested sample itself, and the complexity of the structure, it is difficult to establish a perfect mathematical model for the temperature and humidity control of the test chamber. In order to improve the stability and accuracy of control, fuzzy logic control theory and method are introduced in the control of some temperature test chambers. In the control process, the thinking mode of human is simulated, and the predictive control is adopted to control the temperature and humidity space field more quickly.
Compared with the temperature, the selection of humidity measurement and control points is relatively simple. During the circulation flow of the well-regulated humid air into the high and low temperature cycle test chamber, the exchange of water molecules between the wet air and the test piece and the four walls of the test chamber is very small. As long as the temperature of the circulating air is stable, the circulating air flow from entering the test chamber to exiting the test chamber is in the process. The moisture content of wet air changes very little. Therefore, the relative humidity value of the detected air at any point of the circulating air flow field in the test box, such as the inlet, the middle stream of the flow field or the return air outlet, is basically the same. Because of this, in many test chambers that use the wet and dry bulb method to measure humidity, the wet and dry bulb sensor is installed at the return air outlet of the test chamber. Moreover, from the structural design of the test box and the convenience of maintenance in use, the wet and dry bulb sensor used for relative humidity measurement and control is placed at the return air inlet for easy installation, and also helps to regularly replace the wet bulb gauze and clean the temperature sensing head of the resistance PT100, and according to the requirements of the GJB150.9A wet heat test 6.1.3. The wind speed passing through the wet-bulb sensor should not be lower than 4.6m/s. The wet-bulb sensor with a small fan is installed at the return air outlet for easier maintenance and use.
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