How are the specifications and parameters of the thermal silica film tested?

Regardless of whether it is the staff of the thermal conductive silicone sheet manufacturer or the customer, everyone knows the thermal conductive silicone sheet, and the specifications of the thermal conductive silicone sheet can also know a little bit, but how are the specifications of the thermal conductive silicone sheet tested? I believe that few people can fully answer it, so I think it is necessary to popularize the knowledge of this thermal conductive silicone gasket physical property test standard for everyone here, my friends, come and watch!

Why use thermally conductive silicone gaskets? The main reason is to improve the heat dissipation efficiency of heating products and reduce the impact of high temperature rise.

1. Reduced service life: The long-term use of heating products will not pay attention to the heat dissipation problem, which will cause the temperature of the internal parts of the product to continue to rise, thereby reducing the product life. The life of a temperature rise of 50 degrees Celsius is only half of a temperature rise of 25 degrees Celsius;

2. Reliability reduction: every 2 degrees Celsius rise, the reliability of the product usage drops by 10%;

3. The processing speed is reduced and the signal is delayed;

4. Idle power dissipation increases.

Therefore, when users are purchasing thermally conductive silicone sheets, the following very important specifications should not be ignored when customers choose: thermal conductivity, thermal resistance, thickness, hardness, tensile strength, tear strength, impact Breakthrough voltage, dielectric constant, volume resistivity and other physical properties; the following editor will explain in detail what instrument, what standard, what method and how to test these specifications and parameters.

Test method for thermal conductivity of thermal silica sheet

Thermal conductivity: Under stable heat transfer conditions, a 1mm thick thermally conductive silicone sheet with a temperature difference of 1°C on both sides of the surface, in 1 second, the heat transferred through an area of 1 square meter, expressed by λ, the unit is W/ mk, the thermal conductivity is the same as the quality, it is the nature of the material itself and is not affected by external factors.

Apparent thermal conductivity: This value is different from the thermal conductivity because the apparent thermal conductivity also includes the thermal contact resistance during measurement.

Test method for thermal conductivity of thermally conductive silicone sheet (1)

Test equipment: thermal conductivity tester

Test reference standard: ASTM D5470

Testing under vacuum can effectively remove the influence of air on the test. The standard thickness and pressure of the test sample are issues that need attention in the test.

Test method for thermal conductivity of thermal silica gel sheet (2)

Test instrument: HOT DISK thermal conductivity tester

Test reference standard: TPS

Thermal resistance test method of thermal silica sheet

Testing equipment: material thermal resistance tester

Test reference standard: ASTM D5470

This standard can simulate structural parts to apply pressure on thermally conductive materials for testing. The temperature conduction changes are monitored by the probes (six) attached to the upper and lower parts of the thermal conductive material, and then the computer calculates to obtain the thermal resistance.

Method for measuring the thickness of thermally conductive silicone sheet

Measuring instruments: thickness gauge, caliper

Test reference standard: ASTM D374

Due to the flexibility of the product itself, the human operation factor plays a key role in the thickness test process. Try to be inspected by a skilled caliper inspection worker. The product is subject to contact. Excessive force will cause the product to compress, so here is a reminder of the thermal design work Personnel: When designing, the selection of thermal conductive materials should be at least 20%~30% larger than the size of the voids of the structural parts.

Method for measuring the hardness of thermal silica gel sheet

Testing instrument: Shore hardness tester

Test reference standard: ASTM D2240

There are currently three types of Shore hardness testers commonly used: shore00, shoreA, and shoreC. Different companies use different standards. Due to the softness of the thermally conductive silicone sheet, type C hardness is recommended. Note that the thickness of the sample is at least 6mm.

Measuring method of tensile strength of thermally conductive silicone sheet

Testing equipment: universal material testing machine

Test reference standard: ASTM D412

The test of tensile strength is similar to that of tearing. It also uses universal material testing machine to test. The difference is that the shape of the sample has special requirements. The computer will instruct the testing machine to pull the material until it breaks, thereby calculating the tensile strength.

Method for measuring the tear strength of thermally conductive silicone sheet

Testing equipment: universal material testing machine

Test reference standard: ASTM D412

The thermal conductive silicone sheet must be formed into a standard sample according to the requirements (usually die-cutting is used). The universal material testing machine is connected to the computer through a data cable. According to the change of stroke and force, the computer will calculate the tearing strength of the product and present it in the form of a value .

Method for measuring breakdown voltage of thermally conductive silicone sheet

Test equipment: withstand voltage tester

Test reference standard: ASTM D149

Test method for dielectric constant of thermal silica gel sheet

Permittivity: also known as the permittivity. The applied electric field of the medium will produce induced charges and weaken the electric field. In the same original electric field, the ratio of the permittivity in a certain medium to the permittivity in vacuum is the relative permittivity, also known as Relative permittivity, if a material with a high dielectric constant is placed in an electric field, the strength of the field will be greatly reduced in the dielectric.

Permittivity is an important data to characterize the electrical properties of dielectrics or insulating materials. It is often expressed by ε. The dielectric constant of vacuum is 1.0, the dielectric constant of thermally conductive products is 2-10, and the dielectric constant of superconductors is infinite.

Test equipment: WY2851Q meter

Test reference standard: ASTM D150

Test method introduction: It is composed of two micrometer capacitors. The flat capacitor is used to hold the sample. The cylindrical capacitor is equipped with a Q meter as an indicator. The loss tangent of the thermally conductive silicone sheet is put into the flat capacitor through the tested sample and not The Q value of the sample is converted from the change in the scale reading of the cylindrical capacitor, and the dielectric constant is converted from the change in the scale value of the plate capacitor.

Test method for volume resistivity of thermally conductive silicone sheet

Test equipment: high resistance meter

Test reference standard: ASTM D257

Keep a standard volume of thermally conductive silicone sheet at a specified voltage for the required time, measure the current generated, and calculate the resistance of the material itself through the generated current. The higher the volume resistivity, the higher the effectiveness of the material as an electrical insulating part.