High Temperature Furnace Inspection Index
What is the high temperature furnace test standard? What metrics are tested? How long is the detection cycle? Which items are tested?
Test items (reference) :
Temperature uniformity test, system accuracy test, temperature, system accuracy, temperature uniformity, high temperature furnace verification and calibration, high temperature furnace (tube furnace) verification and calibration, box resistance furnace (high temperature furnace, heat treatment furnace) verification and calibration, high temperature furnace (box resistance furnace, dry furnace, heat treatment furnace) verification and calibration, silica
List of testing standards:
1, NCS/ CJ M61; SAE AMS 2750; JJF1376 High temperature furnace calibration specification NCS/ CJ M61, high temperature furnace calibration method SAE AMS 2750E, box type resistance furnace calibration specification JJF1376
2, AMS 2750F High temperature measurement AMS 2750F
3, GB 25576-2010 Food safety national standard Food additive silica (high temperature furnace method)
4, JJF 1184 thermocouple verification furnace temperature field test technical specification
5, AMS 2750E high temperature measurement AMS 2750E
6, AMS 2750F high temperature determination method 3.5
7, AMS 2750G high temperature measurement AMS 2750G
8, AMS 2750E high temperature determination method 1
9. JJF 1376; AMS 2750; JJG 276 Calibration specification for box type resistance furnace JJF 1376, high temperature measurement method AMS 2750E, high temperature creep, durable strength testing machine verification regulation JJG 276
10, JJF 1376 box type resistance furnace calibration specification
11, GB/T 9452-2012 heat treatment furnace effective heating zone determination method 1
12. SAE AMS 2750 high-temperature calibration method F
How Long Is the Xenon Lamp Weathering Test Chamber Equivalent to a Year of Outdoor Exposure?
How long is the xenon lamp weathering test chamber equivalent to a year of outdoor exposure? How to test out its durability? This is a technical problem, but also a lot of users are concerned about the problem. Today's engineers of Lab Companion are going to explain this problem.
This problem looks very simple, in fact, it is a complex problem.We can not just get a simple number, let this number and the test time of the xenon lamp weathering test chamber to multiply, so as to get the outdoor exposure time, nor is the quality of our xenon lamp weathering test chamber not good enough! No matter how good the quality of the xenon lamp weathering test chamber is, how advanced it is, it is still impossible to find only a number to solve the problem. The most important thing is that the outdoor exposure environment is complex and changeable, affected by many factors, what are the specific?
1. The influence of geographical latitude
2. The influence of altitude
3. The influence of geographical environment when testing, such as wind speed.
4. The impact of the season, winter and summer will be different, summer exposure is 7 times the damage of winter exposure.
5. Direction of the test sample
6. Is the sample insulated or uninsulated? Samples placed on insulators will generally age much faster than those not placed on insulators.
7. Test cycle of xenon lamp weathering test chamber
8. Xenon lamp weathering test chamber operating temperature, the higher the temperature, the faster the aging
9. Testing of special materials
10. Spectrum distribution in the laboratory
LED Traffic Light Test
Light-emitting Diode, referred to as LED, is the abbreviation of the English name Light Emitting Diode, through the combination of electrons and holes to release energy light, can efficiently convert electrical energy into light energy, has a wide range of uses in modern society, such as lighting, flat panel display and medical devices. With the continuous progress of technology, this electronic component from the early can only emit low-light red light to develop other monochromatic light, has been widely used in visible light, infrared and ultraviolet light, is widely used in indicators and display boards, and then extended to traffic lights. It is known as a new light source in the 21st century, with high efficiency, long life, material is not easily affected by the environment and relatively stable, with the advantages of traditional light sources can not be comparable.
The traffic on the zebra crossing is heavy every day, as the guide of the traffic rules - the traffic light is also working hard every day, because it is placed outdoors all year round, so it must accept the strict reliability test before it can work. The test conditions include: Voltage electric, failure protection, electromagnetic noise, dust and waterproof, high temperature test, vibration test, salt spray test, insulation voltage, insulation resistance test...
Note: Before other tests, LED traffic lights need to undergo dry heat tests before other tests can be carried out.
Lamp surface test: dry heat test: 60℃/24 hours/applied voltage
Failure judgment: no deformation, loosening, falling off
Temperature resistance test: 70℃(16 hours)→-15℃(16 hours)→R.T., RAMP:≦1℃/min, 2cycle, power supply
Temperature and humidity test: 40℃→RAMP:≦1℃/min→40℃/95%(24 hours), power on
Continuous switching action: 40℃/60~80%, ON(1sec)←→OFF(1sec), 10000 times
Voltage electric: 80 ~ 135V(AC), 170 ~ 270V(AC)
Failure judgment: Light intensity drift ≦20%(110V, 220V light intensity as the benchmark)
Waterproof and dustproof meet IP54 class requirements
Insulation resistance test:
Insulation resistance: 500V
Failure determination: not less than 2MΩ
Insulation withstand voltage test: 1000V/60Hz/1min(after insulation resistance test)
Light chamber test:
High temperature test: 130℃/1 hour
Failure judgment: no deformation, loosening, falling off, cracking... Etc.
Vibration test: XYZ three-way, each 12min for 36min, 10 ~ 35 ~ 10Hz sine wave, each cycle for 3min, total vibration of 2mm
Failure judgment: no deformation, loosening, falling off, cracking, and the LED light surface can be normally lit and operated
Wind tunnel test: Wind speed 16 (51.5-56.4m /s), forward (0 degrees) and side (45 degrees), each blowing for 2 hours
Failure judgment: no deformation, loosening, falling off, cracking
Salt spray test: 96 hours
Failure determination: less than 8 embroider points on the area of 10,000mm^2, LED signal light surface insulation resistance >2MΩ, voltage 1000V/1min, no abnormality
Recommended model 1: high temperature and high humidity test chamber
High temperature and high humidity test chamber is suitable for electrical, electronic, instruments and other products, parts and materials in high and low temperature alternating wet and hot environment storage, transportation, use adaptability test; It is a reliability test equipment for all kinds of electronic, electrical, electrical, plastic and other raw materials and devices to carry out cold resistance, heat resistance, wet resistance, dry resistance test and quality control engineering; Especially suitable for fiber, LCD, crystal, inductance, PCB, battery, computer, mobile phone and other products of high temperature resistance, low temperature resistance, moisture resistance cycle test.
Recommended model 2: vibration of the comprehensive chamber
Vibration of the comprehensive chamber combined with temperature, humidity, vibration function in one, suitable for aerospace products, information electronic instruments, materials, electrical, electronic products, all kinds of electronic components in a comprehensive harsh environment to test their performance indicators. Vibration of the comprehensive chamber mainly for aerospace, aviation, petroleum, chemical, electronics, communications and other scientific research and production units to provide temperature and humidity change environment, at the same time in the test chamber will be electric vibration stress according to the specified period of the test on the test, for the user of the whole machine (or components), electrical appliances, instruments, materials for temperature and humidity, vibration comprehensive stress screening test. In order to assess the adaptability of the test product or to evaluate the behavior of the test product. Compared with the effect of a single factor, it can more truly reflect the adaptability of electrical and electronic products to temperature, humidity and vibration complex environment changes in transportation and actual use, and expose product defects, which is an essential and important test means for the whole process of new product development, prototype test and product qualification test.
Recommended model 3: salt spray test chamber
The salt spray test chamber is suitable for all kinds of communication electronic products, electronic appliances, hardware parts to do neutral salt spray test (NSS) and corrosion test (AASS, CASS), omplied with CNS, ASTM, JIS, ISO and other standards. The salt spray test is to test the corrosion resistance of the products on the surface of various materials after anti-corrosion treatment such as coating, electroplating, anodic treatment and anti-rust oil.
Recommended model 4: waterproof and dustproof test chamber
Waterproof and dustproof test chamber is suitable for outdoor terminals such as metering automation terminals and distribution network automation terminals to carry out rain and dust tests to ensure that the tested products can withstand the impact of harsh environmental changes, so that the products can operate safely and reliably, and are suitable for external lighting and signal devices and automotive lamp shell protection. It can provide realistic simulation of various environments such as water, spray and dust tests that electronic products and their components may be subjected to during transportation and use. In order to detect the waterproof and dustproof performance of various products.
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
PCB Performs Accelerated Tests of Ion Migration and CAF Through HAST
PCB In order to ensure its long-term use quality and reliability, need to carry out SIR (Surface Insulation Resistance) surface insulation resistance test, through its test method to find out whether the PCB will occur MIG(ion migration) and CAF(glass fiber anode leakage) phenomenon, Ion migration is performed in a humidified state (e.g. 85℃/85%R.H.) with a constant bias (e.g. 50V), the ionized metal moves between the opposite electrodes (cathode to anode growth), the relative electrode is reduced to the original metal and precipitated dendritic metal phenomenon, often resulting in short circuit, ion migration is very fragile, the current generated at the moment of power will make the ion migration itself dissolves and disappears, MIG and CAF commonly used norms: IPC-TM-650-2.6.14., IPC-SF-G18, IPC-9691A, IPC-650-2.6.25, MIL-F-14256D, ISO 9455-17, JIS Z 3284, JIS Z 3197... But its test time is often 1000h, 2000h, for the cyclical products slow emergency, and HAST is a test method is also the name of the equipment, HAST is to improve environmental stress (temperature, humidity, pressure), in the unsaturated humidity environment (humidity: 85%R.H.) Speed up the test process to shorten the test time, used to assess PCB pressing, insulation resistance, and the moisture absorption effect of related materials, shorten the test time of high temperature and humidity (85℃/ 85%R.H. /1000h→110℃/ 85%R.H. /264h), the main reference specifications of PCB HAST test are: JESD22-A110-B, JCA-ET-01, JCA-ET-08.
HAST Accelerated Life Mode:
★ Increase temperature (110℃, 120℃, 130℃)
★ Maintain high humidity (85%R.H.)
Taken the pressure (110 ℃ / / 0.12 MPa, 120 ℃, 85% / 85% / 85% 0.17 MPa, 130 ℃ / / 0.23 MPa)
★ Extra bias (DC)
HAST test conditions for PCB:
1. Jca-et-08:110, 120, 130 ℃/85%R.H. /5 ~ 100V
2. High TG epoxy multilayer board: 120℃/85%R.H./100V, 800 hours
3. Low inductance multilayer board: 110℃/85% R.H./50V/300h
4. Multi-layer PCB wiring, material: 120℃/85% R.H/100V/ 800h
5. Low expansion coefficient & low surface roughness halogen-free insulation material: 130℃/ 85% R.H/12V/240h
6. Optically active covering film: 130℃/ 85% R.H/6V/100h
7. Heat hardening plate for COF film: 120℃/ 85% R.H/100V/100h
Lab Companion HAST High Acceleration Stress Test System (JESD22-A118/JESD22-A110)
The HAST independently developed by Macro Technology fully owns independent intellectual property rights, and the performance indicators can fully benchmark foreign brands. It can provide single-layer and double-layer models and two series of UHAST BHAST. It solves the problem of long-term dependence on imports of this equipment, long delivery time of imported equipment (up to 6 months) and high price. High Accelerated Stress Testing (HAST) combines high temperature, high humidity, high pressure, and time to measure the reliability of components with or without electrical bias. HAST testing accelerates the stress of more traditional testing in a controlled way. It is essentially a corrosion failure test. Corrosion-type failure is accelerated, and defects such as packaging seals, materials and joints are detected in a relatively short time.
Temperature and Humidity Terms
Dew Point temperature Td, in the air water vapor content unchanged, maintain a certain pressure, so that the air cooling to reach saturation temperature called dew point temperature, referred to as dew point, the unit is expressed in ° C or ℉. It's actually the temperature at which water vapor and water are in equilibrium. The difference between the actual temperature (t) and the dew point temperature (Td) indicates how far the air is saturated. When t>Td, it means that the air is not saturated, when t=Td, it is saturated, and when t<Td, it is supersaturated.
dew is the liquid water in the air that condenses on the ground. In the evening or at night, due to the radiation cooling of the ground or ground objects, the air layer close to the surface will also cool down. When the temperature drops below the dew point, that is, when the water vapor content in the air is susaturated, there will be condensation of water vapor on the surface of the ground or ground objects. If the dew point temperature is above 0 ° C at this time, tiny water droplets appear on the ground or ground objects, which are called dew.
frost refers to the white ice crystals formed on the ground or objects after the air close to the ground is cooled to the frost point (meaning the dew point is below 0) under the influence of radiation cooling on the ground.
fog refers to the condensation of water vapor suspended in the atmosphere near the Earth's surface, composed of small water droplets or ice crystals. When the temperature reaches the dew point temperature (or is close to the dew point), the water vapor in the air condenses to form fog.
snow is solid water in the form of snowflakes that falls to the ground from mixed clouds. Precipitation consisting of a large number of white opaque ice crystals (snow crystals) and their polymers (snow masses). Snow is the natural phenomenon of water condensing and falling in the air, or falling snow;
There is a limit to the amount of water vapor that can be contained in a unit volume of air under a certain pressure and a certain temperature. If the water vapor contained in the volume of air exceeds this limit, the water vapor will condense and produce precipitation, and the actual value of water vapor in the volume of air. In terms of absolute humidity. The more water vapor there is, the higher the absolute humidity of the air.
Relative Humidity refers to the percentage of water vapor pressure in the air and saturated water vapor pressure at the same temperature, or the ratio of the absolute humidity of wet air to the maximum absolute humidity that can be reached at the same temperature, and can also be expressed as the ratio of the partial pressure of water vapor in wet air to the saturation pressure of water at the same temperature.
Humidity: wet and dry bulb measurement
The dry and wet bulb thermometer is used to detect the [relative humidity] in the air, the dry bulb temperature is the temperature measured by the general temperature sensor, and the wet bulb temperature is tied on the temperature sensor with a wet cloth, and then soaked in a small cup of water, so that the water is wrapped in the whole sensor, because the relative humidity in the air must be less than or equal to 100% (the water vapor in the air is not saturated). Therefore, the moisture of the wet bulb will be evaporated, and the heat will be taken away during evaporation, resulting in a drop in the wet bulb temperature (the dry bulb temperature is the real air temperature), which means that the greater the difference in the readings of the dry and wet bulb thermometer, the more vigorous the evaporation of water, and the smaller the relative humidity in the air, as long as the temperature of the dry and wet bulb is measured, Then compare [relative humidity table] you can know the relative humidity of the environment at that time.
Temperature Cyclic Stress Screening (1)
Environmental Stress Screening (ESS)
Stress screening is the use of acceleration techniques and environmental stress under the design strength limit, such as: burn in, temperature cycling, random vibration, power cycle... By accelerating the stress, the potential defects in the product emerge [potential parts material defects, design defects, process defects, process defects], and eliminate electronic or mechanical residual stress, as well as eliminate stray capacitors between multi-layer circuit boards, the early death stage of the product in the bath curve is removed and repaired in advance, so that the product through moderate screening, Save the normal period and decline period of the bathtub curve to avoid the product in the process of use, the test of environmental stress sometimes lead to failure, resulting in unnecessary losses. Although the use of ESS stress screening will increase the cost and time, for improving the product delivery yield and reduce the number of repairs, there is a significant effect, but for the total cost will be reduced. In addition, customer trust will also be improved, generally for electronic parts of the stress screening methods are pre-burning, temperature cycle, high temperature, low temperature, PCB printed circuit board stress screening method is temperature cycle, for the electronic cost of the stress screening is: Power pre-burning, temperature cycling, random vibration, in addition to the stress screen itself is a process stage, rather than a test, screening is 100% of the product procedure.
Stress screening applicable product stage: R & D stage, mass production stage, before delivery (screening test can be carried out in components, devices, connectors and other products or the whole machine system, according to different requirements can have different screening stress)
Stress screening comparison:
a. Constant high temperature pre-burning (Burn in) stress screening, is the current electronic IT industry commonly used method to precipitate electronic components defects, but this method is not suitable for screening parts (PCB, IC, resistor, capacitor), According to statistics, the number of companies in the United States that use temperature cycling to screen parts is five times more than the number of companies that use constant high temperature prefiring to screen components.
B. GJB/DZ34 indicates the proportion of temperature cycle and random vibrating screen selection defects, temperature accounted for about 80%, vibration accounted for about 20% of the defects in various products.
c. The United States has conducted a survey of 42 enterprises, random vibration stress can screen out 15 to 25% of the defects, while the temperature cycle can screen out 75 to 85%, if the combination of the two can reach 90%.
d. The proportion of product defect types detected by temperature cycling: insufficient design margin: 5%, production and workmanship errors: 33%, defective parts: 62%
Description of fault induction of temperature cyclic stress screening:
The cause of product failure induced by temperature cycling is: when the temperature is cycled within the upper and lower extremal temperatures, the product produces alternating expansion and contraction, resulting in thermal stress and strain in the product. If there is a transient thermal ladder (temperature non-uniformity) within the product, or the thermal expansion coefficients of adjacent materials within the product do not match each other, these thermal stresses and strains will be more drastic. This stress and strain is greatest at the defect, and this cycle causes the defect to grow so large that it can eventually cause structural failure and generate electrical failure. For example, a cracked electroplated through-hole eventually cracks completely around it, causing an open circuit. Thermal cycling enables soldering and plating through holes on printed circuit boards... Temperature cyclic stress screening is especially suitable for electronic products with printed circuit board structure.
The fault mode triggered by the temperature cycle or the impact on the product is as follows:
a. The expansion of various microscopic cracks in the coating, material or wire
b. Loosen poorly bonded joints
c. Loosen improperly connected or riveted joints
d. Relax the pressed fittings with insufficient mechanical tension
e. Increase the contact resistance of poor quality solder joints or cause an open circuit
f. Particle, chemical pollution
g. Seal failure
h. Packaging issues, such as bonding of protective coatings
i. Short circuit or open circuit of the transformer and coil
j. The potentiometer is defective
k. Poor connection of welding and welding points
l. Cold welding contact
m. Multi-layer board due to improper handling of open circuit, short circuit
n. Short circuit of power transistor
o. Capacitor, transistor bad
p. Dual row integrated circuit failure
q. A box or cable that is nearly short-circuited due to damage or improper assembly
r. Breakage, breakage, scoring of material due to improper handling... Etc.
s. out-of-tolerance parts and materials
t. resistor ruptured due to lack of synthetic rubber buffer coating
u. The transistor hair is involved in the grounding of the metal strip
v. Mica insulation gasket rupture, resulting in short circuit transistor
w. Improper fixing of the metal plate of the regulating coil leads to irregular output
x. The bipolar vacuum tube is open internally at low temperature
y. Coil indirect short circuit
z. Ungrounded terminals
a1. Component parameter drift
a2. Components are improperly installed
a3. Misused components
a4. Seal failure
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)
Temperature Cycling Test
Temperature Cycling, in order to simulate the temperature conditions encountered by different electronic components in the actual use environment, changing the ambient temperature difference range and rapid rise and fall temperature change can provide a more stringent test environment, but it must be noted that additional effects may be caused to material testing. For the relevant international standard test conditions of temperature cycle test, there are two ways to set the temperature change. Macroshow Technology provides an intuitive setting interface, which is convenient for users to set according to the specification. You can choose the total Ramp time or set the rise and cooling rate with the temperature change rate per minute.
List of international specifications for temperature cycling tests:
Total Ramp time (min) : JESD22-A104, MIL-STD-8831, CR200315
Temperature variation per minute (℃/min) : IEC 60749, IPC-9701, Bellcore-GR-468, MIL-2164
Example: Lead-free solder joint reliability test
Instructions: For the reliability test of lead-free solder joints, different test conditions will also be different in terms of the temperature change setting mode. For example, (JEDEC JESD22-A104) will specify the temperature change time with the total time [10min], while other conditions will specify the temperature change rate with [10℃/ min], such as from 100 ℃ to 0℃. With a temperature change of 10 degrees per minute, that is to say, the total temperature change time is 10 minutes.
100℃ [10min]←→0℃[10min], Ramp: 10℃/ min, 6500cycle
-40℃[5min]←→125℃ [5min], Ramp: 10min,
200cycle check once, 2000cycle tensile test [JEDEC JESD22-A104]
-40℃(15min)←→125℃(15min), Ramp: 15min, 2000cycle
Example: LED Automotive lighting (High Power LED)
The temperature cycle test condition of LED car lights is -40 ° C to 100 ° C for 30 minutes, the total temperature change time is 5 minutes, if converted into temperature change rate, it is 28 degrees per minute (28 ° C /min).
Test conditions: -40℃(30min)←→100℃(30min), Ramp: 5min
Reliability Environmental Test Equipment Combined with Multi-track Temperature Control and Detection Applications
Environmental test equipment includes constant temperature and humidity test chamber, hot and cold shock test chamber, temperature cycle test chamber, no wind oven... These test equipment are all in the simulated environment of temperature, humidity impact on the product, to find out the design, production, storage, transportation, use process may appear product defects, previously only simulated test area air temperature, but in the new international standards and the new test conditions of the international factory, the beginning of the requirements based on the air temperature is not. It is the surface temperature of the test product. In addition, the surface temperature should also be measured and recorded synchronously during the test process for post-test analysis. The relevant environmental test equipment should be combined with surface temperature control and the application of surface temperature measurement is summarized as follows.
Constant temperature and humidity test chamber test table temperature detection application:
Description: Constant temperature and humidity test chamber in the test process, combined with multi-track temperature detection, high temperature and humidity, condensation (condensation), combined temperature and humidity, slow temperature cycle... During the test process, the sensor is affixed to the surface of the test product, which can be used to measure the surface temperature or internal temperature of the test product. Through this multi-track temperature detection module, the set conditions, actual temperature and humidity, the surface temperature of the test product, and the same measurement and record can be integrated into a synchronous curve file for subsequent storage and analysis.
Thermal shock test chamber surface temperature control and detection applications: [dwell time based on surface temperature control], [temperature shock process surface temperature measurement record]
Description: The 8-rail temperature sensor is attached to the surface of the test product and applied to the temperature shock process. The dwell time can be counted backward according to the arrival of the surface temperature. During the impact process, the setting conditions, the test temperature, the surface temperature of the test product, and the same measurement and record can be integrated into a synchronous curve.
Temperature cycle test chamber surface temperature control and detection application: [Temperature cycle temperature variability and dwell time are controlled according to the test product surface temperature]
Description: Temperature cycle test is different from temperature shock test. Temperature shock test uses the maximum energy of the system to carry out temperature changes between high and low temperatures, and its temperature change rate is as high as 30 ~ 40℃ /min. Temperature cycle test requires a process of high and low temperature changes, and its temperature variability can be set and controlled. However, the new specification and the test conditions of international manufacturers have begun to require that the temperature variability refers to the surface temperature of the test product, not the air temperature, and the current temperature cycle specification temperature variability control. According to the test product surface specifications are [JEDEC-22A-104F, IEC60749-25, IPC9701, ISO16750, AEC-Q100, LV124, GMW3172]... In addition, the residence time of high and low temperatures can also be based on the test surface, rather than the air temperature.
Temperature cyclic stress screening test chamber surface temperature control and detection applications:
Instructions: Temperature cycle stress screening testing machine, combined with multi-rail temperature measurement, in the temperature variability of stress screening, you can choose to use [air temperature] or [test product surface temperature] to control the temperature variability, in addition, in the high and low temperature resident process, the time reciprocal can also be controlled according to the surface of the test product. In accordance with the relevant specifications (GJB1032, IEST) and the requirements of international organizations, according to the definition of GJB1032 in the stress screening residence time and temperature measurement point, 1. The number of thermocouples fixed on the product shall not be less than 3, and the temperature measurement point of the cooling system shall not be less than 6, 2. Ensure that the temperature of 2/3 thermocouples on the product is set at ±10℃, in addition, according to the requirements of IEST(International Association for Environmental Science and Technology), the residence time should reach the temperature stabilization time plus 5min or performance test time.
No air oven (natural convection test chamber) surface temperature detection application:
Description: Through the combination of a windless oven (natural convection test chamber) and a multi-track temperature detection module, the temperature environment without fan (natural convection) is generated, and the relevant temperature detection test is integrated. This solution can be applied to the actual ambient temperature test of electronic products (such as: Cloud server, 5G, electric vehicle interior, indoor without air conditioning environment, solar inverter, large LCD TV, home Internet sharer, office 3C, laptop, desktop, game console....... Etc.).
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