Working Principle and Classification of Vacuum Pump in Vacuum Drying Oven
1, The working pressure of the vacuum pump should meet the limit vacuum and working pressure requirements of the vacuum equipment, and the best value of the vacuum degree of the selected vacuum pump is 133pa=-0.1 mpa. Usually, the vacuum degree of the selected pump is half to an order of magnitude higher than the vacuum degree of the vacuum equipment.
2, Correctly select the working point of the vacuum pump. Each pump has a certain operating pressure range.
3, The vacuum pump under its working pressure, should be able to discharge all the gas generated in the process of vacuum equipment.
4, Correctly combine the vacuum pump. Because the vacuum pump has selective pumping, sometimes a pump can not meet the pumping requirements, and several pumps need to be combined to complement each other to meet the pumping requirements, such as titanium sublimation pump has a high pumping speed for hydrogen, but can not pump helium, and the three-pole sputtering ion pump, (or bipolar asymmetric cathode sputtering ion pump) has a certain pumping speed for argon, the combination of the two, It will make the vacuum device get a better vacuum degree. In addition, some vacuum pumps can not work at atmospheric pressure, need pre-vacuum; Some vacuum pump outlet pressure is lower than atmospheric pressure, the need for the front pump, so it is necessary to combine the pump to use.
5, Vacuum equipment for oil pollution requirements. If the equipment is strictly required to be oil-free, a variety of non-oil pumps should be selected, such as: water ring pumps, molecular sieve adsorption pumps, sputtering ion pumps, cryogenic pumps, etc. If the requirements are not strict, you can choose to have a oil pump, plus some anti-oil pollution measures, such as cooling trap, baffle, oil trap, etc., can also meet the clean vacuum requirements, our company's vacuum drying oven selection is rotary vane oil pump, its main characteristics: large force, fast speed, high efficiency.
6, Understand the composition of the gas being pumped, whether the gas contains condensable steam, whether there is particulate dust, whether there is corrosion, etc. When selecting a vacuum pump, you need to know the gas composition, select the appropriate pump for the gas being pumped. If the gas contains steam, particles, and corrosive gases, it should be considered to install auxiliary equipment on the pump inlet line, such as condenser, dust collector, or liquid water filter.
7, What is the impact of the oil steam discharged from the vacuum pump on the environment? If the environment is not allowed to have pollution, you can choose an oil-free vacuum pump, or exhaust the oil steam to the outside.
8, Whether the vibration generated by the vacuum pump during operation has an impact on the process and the environment. If the process does not allow, should choose non-vibration pump or take anti-vibration measures.
9, The price of vacuum pump, operation and maintenance costs.
Burn-in Testing
Burn-in testing is the process by which a system detects early failures in semiconductor components (infant mortality), thereby increasing a semiconductor component reliability. Normally burn-in tests are performed on electronic devices such as laser diodes with an Automatic Test Equipment laser diode burn-in system that runs the component for an extended period of time to detect problems.
A burn-in system will use cutting-edge technology to test the component and provide precision temperature control, power and optical (if required) measurements to ensure the precision and reliability required for manufacturing, engineering evaluation, and R&D applications.
Burn-in testing may be conducted to ensure that a device or system functions properly before it leaves the manufacturing plant or to confirm new semiconductors from the R&D lab are meeting designed operating requirements.
It is best to burn-in at the component level when the cost of testing and replacing parts is lowest. Burn-in of a board or an assembly is difficult because different components have different limits.
It is important to note that burn-in test is usually used to filter out devices that fail during the “infant mortality stage” (beginning of bathtub curve) and does not take into count the “lifetime” or wearout (end of the bath tub curve) – this is where reliability testing comes into play.
Wearout is the natural end-of-life of a component or system related to continuous use as a result of materials interaction with the environment. This regime of failure is of particular concern in denoting the lifetime of the product. It is possible to describe wearout mathematically allowing the concept of reliability and, hence, lifetime prediction.
What Causes Components to Fail During Burn-in?
The root cause of fails detected during burn-in testing can be identified as dielectric failures, conductor failures, metallization failures, electromigration, etc. These faults are dormant and randomly manifest into device failures during device life-cycle. With burn-in testing, an Automatic Test Equipment (ATE) will stress the device, accelerating these dormant faults to manifest as failures and screen out failures during the infant mortality stage.
Burn-in testing detects faults that are generally due to imperfections in manufacturing and packaging processes, which are becoming more common with the increasing circuit complexity and aggressive technology scaling.
Burn-in Testing Parameters
A burn-in test specification varies depending on the device and testing standard (military or telecom standards). It usually requires the electrical and thermal testing of a product, using an expected operating electrical cycle (extreme of operating condition), typically over a time period of 48-168 hours. The thermal temperature of the burn-in test chamber can range from 25°C to 140°C .
Burn-in is applied to products as they are made, to detect early failures caused by faults in manufacturing practice.
Burn In Fundamentally performs the following:
Stress + Extreme Conditions + Prolong Time = Acceleration of “Normal/Useful life”
Types of Burn-in Tests
Dynamic Burn-in : the device is exposed to high voltage and temperature extremes while being subjected to various input stimuli .
A burn-in system applies various electrical stimuli to each device while the device is exposed to extreme temperature and voltage. The advantage of dynamic burn-in is its ability to stress more internal circuits, causing additional failure mechanisms to occur. However, dynamic burn-in is limited because it cannot completely simulate what the device would experience during actual use, so all the circuit nodes may not get stressed.
Static Burn-in : Device under test (DUT) is stressed at elevated constant temperature for an extended period of time.
A burn-in system applies extreme voltage or currents and temperatures to each device without operating or exercising the device. The advantages of static burn-in are its low cost and simplicity.
How is a Burn-In Test Performed?
The semiconductor device is placed onto special Burn-in Boards (BiB) while the test is executed inside special Burn-in Chamber (BIC).
Know more about Burn-in Chamber（Click here）
Lab Ovens and Lab Furnaces
Design with sample protection as the primary goal
Lab ovens are an indispensable utility for your daily workflow, from simple glassware drying to very complex temperature-controlled heating applications. Our portfolio of heating and drying ovens provides temperature stability and reproducibility for all your application needs. LABCOMPANION heating and drying ovens are designed with sample protection as a primary goal, contributing to superior efficiency, safety and ease of use.
Understand natural and mechanical convection
Principle of natural convection:
In a natural convection oven, hot air flows from bottom to bottom, so that the temperature is evenly distributed (see figure above). No fan actively blows the air inside the box. The advantage of this technology is ultra-low air turbulence, which allows for mild drying and heating.
Principle of mechanical convection:
In a mechanical convection (forced air drive) oven, an integrated fan actively drives the air inside the oven to achieve uniform temperature distribution throughout the chamber (see figure above). A major advantage is excellent temperature uniformity, which enables reproducible results in applications such as material testing, as well as for drying solutions with very demanding temperature requirements. Another advantage is that the drying rate is much faster than natural convection. After opening the door, the temperature in the mechanical convection oven will be restored to the set temperature level more quickly.
Comparison of Natural Convection Test Chamber, Constant Temperature and Humidity Test Chamber and High Temperature Oven
Instructions:
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 using a general oven or thermal and humidity chamber to simulate the temperature environment, either the oven or thermal and humidity chamber has 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℃. In order to simulate the actual use of environmental conditions, many people will misunderstand that only the test chamber can produce temperature (such as: oven, constant temperature humidity 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 and software, the temperature environment without passing through the fan (natural convection) is generated, and the test integration test is performed for the temperature detection of the product under test. This solution can be used for home related electronics or real-world ambient temperature testing in confined Spaces (e.g., large LCD TV, car cockpits, automotive electronics, laptops, desktops, game consoles, stereos, etc.).
Unforced air circulation test specification :IEC-68-2-2, GB2423.2, GB2423.2-89 3.31 The difference between the test environment with or without wind circulation and the test of products to be tested:
Instructions:
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 humidifier is used to simulate 35 °C, although the environment can be controlled within 35 °C through electric heating and compressor, the wind circulation of the oven and the thermal and humidify test chamber will take away the heat of the product to be tested. So that the actual temperature of the product to be tested is lower than the temperature under the real windless state. It is necessary to use a natural convection test chamber without wind speed to effectively simulate the actual windless environment (indoor, no starting car cockpit, instrument chassis, outdoor waterproof chamber... Such environment).
Comparison table of wind speed and IC product to be tested:
Description: 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 the faster the wind speed and the lower the temperature.
AEC-Q200 Passive Component Stress Test Certification Specification for Automotive Industry
In recent years, with the progress of multi-functional in-vehicle applications, and in the process of popularization of hybrid vehicles and electric vehicles, new uses led by power monitoring functions are also expanding, miniaturization of vehicle parts and high reliability requirements under high temperature environmental conditions (-40 ~ +125℃, -55℃ ~ +175℃) are increasing. A car is composed of many parts. Though these parts are large and small, they are closely related to the life safety of car driving, so every part is required to achieve the highest quality and reliability, even the ideal state of zero defects. In the automotive industry, The importance of quality control of auto parts is often over the functionality of parts, which is different from the needs of consumer electronics for the general people's livelihood, that is to say, for auto parts, the most important driving force of the product is often not [the latest technology], but [quality safety]. In order to achieve the improvement of quality requirements, it is necessary to rely on strict control procedures to check, the current automotive industry for parts qualification and quality system standards is AEC(Automotive Electronics Committee). The active parts designed for the standard [AEC-Q100]. The passive components designed for [AEC-Q200]. It regulates the product quality and reliability that must be achieved for passive parts.
Classification of passive components for automotive applications:
Automotive grade electronic components (compliant with AEC-Q200), commercial electronic components, power transmission components, safety control components, comfort components, communication components, audio components
Parts summary according to AEC-Q200 standard:
Quartz oscillator: Application range [tire pressure monitoring systems (TPMS), navigation, anti-lock brakes (ABS), airbags and proximity sensors In-vehicle multimedia, in-vehicle entertainment systems, backup camera lenses]
Automotive thick film chip resistors: Application [automotive heating and cooling systems, air conditioning, infotainment systems, automatic navigation, lighting, door and window remote control devices]
Automotive sandwich metal oxide varistors: Application [Surge protection of motor components, surge absorption of components, semiconductor overvoltage protection]
Low and high temperature surface mount solid molded chip tantalum capacitors: Application [fuel quality sensors, transmissions, throttle valves, drive control systems]
Resistance: SMD resistor, film resistor, thermistor, varistor, automotive vulcanization resistance, automotive precision film wafer resistance array, variable resistance
Capacitors: SMD capacitors, ceramic capacitors, aluminum electrolytic capacitors, film capacitors, variable capacitors
Inductance: Reinforced inductance, inductor
Other: LED thin film alumina ceramic cooling substrate, ultrasonic components, overcurrent protection SMD, overtemperature protection SMD, ceramic resonator, automotive PolyDiode semiconductor ceramic electronic protection components, network chips, transformers, network components, EMI interference suppressors, EMI interference filters, self-recovery fuses
Passive device stress test grade and minimum temperature range and typical application cases:
Class
Temperature range
Passive device type
Typical application case
Minimum
Maximum
0
-50 ℃
150℃
Flat core ceramic resistor, X8R ceramic capacitor
For all cars
1
-40 ° C
125 ° C
Network capacitors, resistors, inductors, transformers, thermistors, resonators, quartz oscillators, adjustable resistors, ceramic capacitors, tantalum capacitors
For most engines
2
-40 ℃
105℃
Aluminum electrolytic capacitor
Cockpit high temperature point
3
-40 ℃
85℃
Thin capacitors, ferrites, network low-pass filters, network resistors, adjustable capacitors
Most of the cockpit area
4
0 ° C
70 ° C
Non-automotive
Note: Certification for applications in higher grade environments: Temperature grades must have a product life worst-case and application design, i.e. at least one batch of each test must be validated for applications in higher grade environments.
Number of certification tests required:
High temperature storage, high temperature working life, temperature cycle, humidity resistance, high humidity: 77 thermal shock: 30
Number of certification tests Note:
This is a destructive test and the component cannot be reused for other certification tests or production
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