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Analysis of qualified test standards for thermal silica gel sheets

2019-08-01(50)次浏览

The test standards and methods for thermal conductive materials (thermal silica gel, thermal grease, thermal double-sided adhesive), etc., are well-known for many people. Lian Tengda Technology Co., Ltd. wrote this article for everyone to share.
First, why use thermal conductive materials (thermal grease, thermal silica film, thermal ceramic sheet)
The main reason is to improve the heat dissipation efficiency of the heat-generating products and reduce the impact of high temperature rise.
1. Reduced life: Long-term use of heat-generating products does not pay attention to heat dissipation. The temperature of the components inside the product will continue to rise, which will reduce the life of the product. The temperature rise of 50 degrees Celsius is only half of the temperature rise of 25 degrees Celsius.
2. Reliability reduction: every 2 degrees Celsius rise, the reliability of product use is reduced by 10%.
3. Processing speed is reduced, signal delay
4. Idle power dissipation increases
2. The key characteristics of the thermal conductive material (silicone sheet, thermal grease, thermal ceramic sheet) to be tested
Thickness
2. Hardness
3. Tear strength
4. Tensile strength
5. Breakdown voltage
6. Dielectric constant
7. Volume resistivity
8. Thermal conductivity and resistance


How to measure the thickness:
Measuring instruments needed: thickness gauge, caliper
Test reference standard: ASTM D374
Test focus: Because the softness of the silicone sheet product itself plays a key role in the measurement of human factors, we generally test it by a highly skilled tester with a caliper operation, and the force should not be too large when testing. Otherwise, it will cause compression, so it reminds the thermal designer that the choice of thermal conductive material should be at least 20%-30% larger than the size of the structural part gap.


2. Method of measuring hardness
Test instrument: hardness tester
Test standard: ASTM D2240
Main content: The standards used in testing by different companies are different. Due to the softness of thermal conductive materials (Zhi thermal silica gel), type C hardness is recommended. The thickness requirement of the sample is generally required to be 6MM during the test.



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3. Method for measuring tear strength
Test equipment: material testing machine
Test standard: ASTM D412
The test points: the material is formed into a standard sample according to the requirements, the universal material testing machine is connected to the computer through the data line, according to the stroke and power changes, the computer calculates the product cracking strength and presents the test result in the form of numerical value.

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4. Measurement method of breakdown voltage
Test instrument: pressure tester
Test reference standard: ASTM D149
Tensile strength testing is similar to tearing, and is also tested using a universal material testing machine, except that the shape of the sample has special requirements (as shown on the left). The computer will command the testing machine to break the material to calculate the tensile strength.


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5. Thermal conductivity
The thermal conductivity refers to the material with a thickness of 1 m under stable heat transfer conditions. The temperature difference between the two sides is 1 ° C. The heat transferred through the area of 1 m 2 in 1 second is expressed by λ, and the unit is watt / (m·· Degree), w/(m·k)
The thermal conductivity is the same as the quality, which is the nature of the material itself and is not affected by external factors.
Thermal conductivity test method (1)
Test instrument: thermal conductivity tester
Testing under vacuum effectively removes the effects of air on the test. The standard thickness and pressure of the test sample are all issues to be considered in the test.

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