Silicone rubber sheet is the electronics industry to use more of the kind of product, it is mainly used for sensing thermal conductivity, is specially designed for use of transfer heat crack and choose one of the best materials, in use process not only does it take to fill the gaps, well versed in hot parts and cooling parts of the channel, also can effectively refreshing the efficiency and stability of the heat transfer system, And the use of silica gel material can be used for certain insulation, shock absorption, sealing and protection, can meet a variety of small and medium-sized electronic equipment has a good thermal conductivity system, is currently a more traditional type of thermal conductivity filling material.

However, in the actual use process, there are also different product quality problems, of which the most common is thermal conductivity sensor failure and the aging life of the product decline, and the aging life of these problems occupy the main factor, so what are the phenomena that affect the service life of thermal conductivity silica gel sheet?

First, what is the "aging and hardening" of heat conduction gaskets?

In the process of use, the hardness of silicone thermal conductivity gasket will increase because it is in a high temperature environment for a long time, which will seriously affect the use effect and service life of the gasket, and will also cause damage to electronic and electrical equipment.

Second, what is the harm of the late hardening of heat conduction gaskets?

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

1. After the gasket becomes hard, it is not only inconvenient for construction, but also decreases the fitting degree, seriously increases the thermal resistance and reduces the heat dissipation effect.
2. After construction, the gasket itself is easy to crack or even pulverize. The life of the gasket is shortened and the heat dissipation effect is seriously reduced.
3, late hardening will also appear gasket and protected components separation, resulting in direct exposure of components, which is easy to cause short circuit or thermal oxidation, rust, affect the life of components.

Third, what factors caused the late hardening?

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

1. Too much cross-linking agent (this factor is the largest and most likely to cause problems) :
Generally speaking, when adding hydrogen silicone oil, the molar ratio of hydrogen and vinyl should be controlled at (1.2-1.8) : 1, where hydrogen includes side hydrogen and end hydrogen silicone oil. Many people mistakenly think that the end hydrogen is a little more, the strength will be higher, the hardness will be reduced, so the excessive addition of the end hydrogen silicone oil, the result is that the colloid resilience decreases, the surface viscosity decreases, and the hardness rises quickly after aging.
2. The volatiles in hydrogen-containing silicone oil are generally relatively high, even reaching about 12%. Part of these volatiles is cyclosiloxane monomer (DMC), and part is hydrogen containing small molecule monomer (straight chain or ring). The resulting phenomenon is increased hardness in later stages or after aging.
3. When the volatiles in vinyl silicone oil and hydrogen silicone oil are high, these small molecules will run out in the aging process, which is equivalent to the reduction of the amount of oil in the system, 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 factor, different additives are added to raw materials, and the quality of each powder and the standard method of refining are different.

Therefore, the factors leading to the quality problems of silicone rubber gaskets also occupy one of them.

Forth, how to solve this problem?

The molar ratio of hydrogen and vinyl should be calculated and controlled at (1.2-1.8) : 1. The addition amount of hydrogen silicone oil should not be too high, which is generally lower than 0.9 relative to vinyl. This can ensure the stability of hardness, but also maintain the resilience of the product.