Silicone rubber sheet is currently used in the electronics industry a large number of a class of products, it is mainly used for sensing heat conduction, is specifically for the use of gaps to transfer heat and one of the best materials selected, in the process of use it can not only fill the gap, through the heating part and heat dissipation part of the channel, but also can effectively refresh the efficiency and stability of the heat transfer system. And the use of silica gel material can obtain a certain insulation, shock absorption, sealing and protection effects, can meet a variety of small and medium-sized electronic equipment has a good thermal conductivity system, is currently a more traditional class of thermal filler materials.

However, in the actual use of the process, there are also different product quality problems, which is more common is the thermal conductivity sensing failure and product aging life decline, and in these problems, the aging life of the problem occupies the main factor, so what do the thermal silicone sheet affect the service life of the phenomenon?

First, what does the "aging hardening" of the thermal gasket mean?

In the process of use, due to the long-term high temperature environment, the hardness will increase, which will seriously affect the use effect and service life of the gasket, and also cause damage to electronic and electrical equipment.

Second, what is the harm of later hardening of thermal gaskets?

Since such thermal conductivity materials are mostly used in sophisticated electronic and electrical products, once such problems occur, the common hazards are as follows:

1. After the gasket hardens, it is not only inconvenient for construction, but also reduces the fit degree, seriously increases the thermal resistance, and decreases the heat dissipation effect.
2. After construction, it becomes hard, the gasket itself is easy to crack and even powder, the gasket life becomes shorter, and the heat dissipating effect is seriously reduced.
3, later hardening will also appear gasket and protected components separation, resulting in direct exposure of components, which is easy to cause product short circuit or thermal oxidation, rust, etc., affecting the life of components.

Third, what factors cause late hardening?

Silicone thermal gasket is a composite material, which is prepared by mixing the additive silicone elastomer which provides high elasticity and the thermal conductive filler which provides thermal conductivity. Therefore, the main influencing factors are as follows:


1, too much crosslinker (this factor is the largest, but also the most prone to problems) :
In general, when hydrogen silicone oil is added, the molar ratio of hydrogen to vinyl should be controlled at (1.2-1.8) : 1, and the hydrogen content here includes side hydrogen and end hydrogen silicone oil. Many people mistakenly think that a little more end hydrogen, the strength will be higher, the hardness will be reduced, so the excessive addition of end hydrogen silicone oil, the result is that the colloidal resilience decreases, the surface viscosity decreases, and the hardness rises quickly after aging.


2, the volatile content of hydrogen-containing silicone oil is generally relatively high, and the high will even reach about 12%, some of these volatile components are cyclosiloxane monomer (DMC), and some are hydrogen-containing small molecular monomer (straight chain or ring), the characteristics of these hydrogen-containing small molecules are not high activity at low temperature, and the reaction will be slow at high temperature. The resulting phenomenon is that the hardness becomes larger in the later period or after aging.


3. When the volatile content of vinyl silicone oil and hydrogen-containing silicone oil is high, these small molecules will run out during the aging process, which is equivalent to the reduction of the amount of system oil, which will not only cause the gasket to harden, but also reduce the thermal conductivity. After volatilization, the gasket contact interface will become dry and the surface viscosity will decrease.


4, powder factors, the chemical additives added to the raw materials are different, the quality of each powder and the extraction standard method are different, so the factors that lead to the quality problems of silicone rubber gaskets also occupy one of them.


Fourth, how to solve this problem?


Calculate the molar ratio of hydrogen and vinyl, control at (1.2-1.8) : 1, and the amount of hydrogen silicone oil added should not be too high, generally less than 0.9 relative to vinyl. This not only ensures the stability of the hardness, but also maintains the resilience of the product.