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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