How to do high and low temperature test? Product high and low temperature test standard
Date：2021-07-26 11:35:00 Views：1996
Before leaving the factory, the chip needs environmental test to simulate the adaptability of the chip to operation and storage in the climate environment, so as to ensure that it can work normally in extreme environments. High and low temperature test is a method used to determine the adaptability of products to storage, transportation and use under high temperature climate and environmental conditions. The severity of the test depends on the temperature of the high temperature and the duration of exposure. The test equipment is mainly used to conduct environmental simulation test on the physical and other relevant characteristics of the product under low temperature, high temperature and other conditions according to the requirements of national standards or user-defined requirements. After the test, it can judge whether the performance of the product can still meet the predetermined requirements for product design, improvement, identification and delivery inspection.
Effects of high temperature and low temperature on electronic (plastic) products:
1、 High temperature may overheat the product, affect the safety and reliability of use, and even damage it. For example:
1. The insulating or sealing grouting glue is melted and lost, and the lubricating grease is melted and lost, resulting in tower damage
2. Change material properties
3. The elastic or mechanical properties of elastic elements reduce the strength and shorten the service life of products
4. Accelerate the deterioration and aging process of polymer materials and insulating materials and shorten the service life of products.
2、 The influence of low temperature on mechanical, electrical and electronic products is multifaceted, and varies according to the characteristics of products relying on energy and auxiliary structure, such as:
1. Freeze the electrolyte, t resulting in abnormal use of electrolytic capacitors and batteries
2. The viscosity of lubricating oil increases, even condenses and freezes, which affects the starting performance of the product
3. Affect the normal start of electronic products and increase the instrument error
4. Make materials brittle, such as plastics and steel are prone to brittle damage at low temperature, the hardness of rubber materials increases and the elasticity decreases.
Detailed flow of high and low temperature test
1. When the sample is powered off, first reduce the temperature to - 50 ℃ and keep it for 4 hours; It is very important not to conduct low-temperature test when the sample is powered on, because the chip itself will produce a temperature above + 20 ℃, so it is usually easier to pass the low-temperature test when the sample is powered on. It must be "frozen through" and powered on again for test.
2. Start up and test the performance of the sample to compare whether the performance is normal compared with that at normal temperature.
3. Conduct aging test and observe whether there is data comparison error.
4. Raise the temperature to + 90 ℃ and keep it for 4 hours. Contrary to the low-temperature test, the heating process is powered continuously to keep the internal temperature of the chip at high temperature. After 4 hours, perform test steps 2, 3 and 4.
5. The high temperature and low temperature tests were repeated 10 times respectively.
If the test process fails to work normally for any time, it shall be regarded as a test failure.
High and low temperature testTest equipment and test parameters
1。 High and low temperature cycle test equipment
High temperature test is generally conducted by placing the product in a constant temperature box or chamber. The temperature of the medium is measured at different positions with a thermometer, and its arithmetic mean value is taken. However, the temperature in the box shall be as uniform as possible, the product shall be heated by hot air flow, and the test sample shall not be close to the heat source. In order to reduce the influence of radiation, the wall temperature of the test chamber shall not be higher than the ambient temperature by 3%.
The low temperature test is generally carried out in the low temperature box (chamber), and its temperature is generally obtained by manual refrigeration. In the effective working space of the low-temperature box, forced air circulation is used to maintain the uniformity of low-temperature conditions.
2。 Test parameters
Gb2423.1-81 and gb2423.2-81 specify the priority values of different temperature levels according to different regions and application occasions.
Low temperature ambient temperature: 65 ℃ - 55 "C, 45" C, 40 ℃, 30 ℃, 25 ℃, 15 ℃, 10 ℃, 5 ℃, 0 ℃ and + 5 ℃;
High temperature ambient temperature: + 200 ℃, + 17s ℃, + 155 ℃, + 125 ℃, + 100 ℃, + 8s ℃, + 70 ℃, + 65 ℃, + 60 ℃, + 55 ℃, + 50 ℃, + 45 ℃, + 40 ℃, + 3S ℃, + 30 ℃.
The allowable deviation range of temperature is ± 2 ℃.
After the temperature of the test sample is stable, the test duration under high and low temperature conditions shall be selected from the following data as required: 2, 16, 72 and 95 (H).
Basic requirements of products after high and low temperature test
The product quality after high and low temperature test is generally inspected according to the requirements specified in the product technical conditions or technical agreement. For example, the influence of high temperature environment on the performance of motor products is reflected in the increase of the resistance of conductive materials, resulting in the change of current. For motors with accuracy requirements, it will also affect the accuracy. Therefore, after the high temperature test, the insulation resistance shall be measured in the test chamber, and its value shall not be less than 5m Ω. At the same time, other properties of the motor shall be tested. Generally, after the temperature test, if the product can meet the following basic requirements, it is considered that the product meets the high and low temperature requirements.
(1) The product surface shall be free of damage, deformation and other defects. In case of coated surface, there shall be no peeling, blistering or discoloration of the coating.
(2) For plastic parts, there are no cracks, bubbles and deformation on the surface.
(3) Rubber products shall be free from aging, bonding, softening and cracking.
(4) There is no flow at the welding part of product parts.
(5) The product performance data, structure and function shall meet the requirements of technical conditions, and there shall be no other defects that hinder the normal operation of the product.