Thermal interface material

Abstract

The invention discloses a thermal interface material. The thermal interface material is woven metal cloth which is formed by processing metal yarns through a weaving or knitting process, or the thermal interface material is non-woven metal cloth which is formed by processing metal fibers through a non-woven process, wherein the thickness of the metal cloth ranges from 0.05mm to 2.0mm, the number of the metal fibers contained in the metal cloth in the cross section direction is 5-40, the metal yarns refer to metal filament yarns and composite yarns of which the number of section fibers is not less than 5 or refer to staple fiber yarns of which the number of section fibers is not less than 10, the diameter of the metal fibers used for processing the woven cloth ranges from 0.005mm to 0.1mm,and the diameter of the metal fibers used for processing the non-woven cloth ranges from 0.005mm to 0.05mm.

Description

technical field [0001] The invention relates to a thermal interface material for electronic packaging, in particular to a thermal interface material. Background technique [0002] 5G networks refer to the fifth generation of wireless networks. At present, the transmission rate of 5G network has successfully reached 1Gbps in the 28GHz band. In the future, the transmission rate of 5G network can even reach 10Gbps, and its data processing capacity is 10 to 100 times that of 4G. The reception, processing and transmission of such massive data make radio frequency Chips, baseband chips, CPUs, GPUs, neural network chips, and other types of chips have a sharp increase in computation, resulting in a sharp increase in chip power consumption. The sharp increase in chip power consumption directly leads to a sharp increase in its calorific value, which requires higher and higher heat dissipation performance of chip packaging thermal management materials. It can be said that thermal mana...

AI Technical Summary

Problems solved by technology

Due to the restrictions on the use of lead, the commonly used solders are tin-silver and tin-copper alloys. As thermal interface materials, their disadvantages are that the soldering process is complicated and requires a reflow soldering process. Thermal stress is likely to occur during the soldering process and heat the components. Shock, in addition, because it is a solid-state connection, during use, due to the thermal expansion coefficient mismatch, it will generate a large thermal stress, which cannot be released through the adaptive compression or relaxation of the thermal interface material, in the chip and heat dissipation Large thermal stress on the surface of the device may cause fatigue cracks. On the other hand, welding defects such as virtual welding and bridging are prone to occur during the welding process, and the cost is high

[0012] In summary, the existing thermal interface materials, except metal phase change materials and brazing materials, have thermal conductivity less than 5W / (m·K), and metal phase change materials have high cost and serious problems. The pumping effect of the brazing material, the welding process of the brazing material is complicated, the cost is high, and the thermal stress caused by the mismatch of the thermal expansion coefficient cannot be relaxed

[0013] In view of the fact that the thermal conductivity of metal materials is much greater than that of other thermal interface materials, some researchers have tried to use copper foil and aluminum foil as thermal interface materials, but the effect is not good. The reason is that although copper foil and aluminum foil have high thermal conductivity, they have poor flexibility. There is no compressibility under the action of slight packaging pressure, and it cannot adapt to the uneven installation gap between the chip and the radiator, and it cannot be tightly attached to the surface of the chip and the radiator, resulting in large thermal resistance and low thermal conductivity. There are no metal-based thermal interface materials on the market (except for liquid metals and solders)

[0014] The above-mentioned problems of commonly used thermal interface materials are as follows: 1. Low thermal conductivity and large interface thermal resistance. Liquid metal and brazing material have the highest thermal conductivity, but both are expensive and inconvenient to use. The thermal conductivity of commonly used thermal paste is only between 0.4-4W / (m K), it is difficult to dissipate the heat generated by the chip in time. 2. There is a pump-out effect, and thermal paste, phase change polymer materials, and liquid metals There is a pump-out effect, and with the prolongation of the use time, the thermal conductivity and reliability drop significantly; 3. There are aging problems, thermal paste, thermal pad, thermal gel, thermal adhesive, phase change polymer materials, etc. Polymer materials such as resin or polymer as the matrix will age under the long-term temperature cycle thermal stress, resulting in a decrease in thermal conductivity and reduced reliability; 4. There is a contradiction between thermal conductivity and softness in the thermal pad. Add high thermal conductivity fillers to the polymer. If there are more thermal conductivity fillers, the softness and compressibility will be reduced, and the thermal conductivity will be low, only 0.3~3W / (m K); 6. Poor usability, thermal paste, thermal conductivity Adhesive and thermal conductive gel are coated on the surface of components when used, but once these materials are coated, they are not easy to clean up and cannot be reused. For the soldering method, the shapes and specifications of heating components are various, and reflow soldering and other complex processes, high cost

7. There is a contradiction between cost and thermal conductivity that is difficult to reconcile. Liquid metal and soldering with high thermal conductivity have high cost, while low-cost thermal conductive paste and thermal gel have low thermal conductivity.

Metal filaments do have some thermal conductivity, but they are not compressible

In addition, the Chinese patent ZL201210169313.8 requires a surface protection material layer, an adhesive material layer and a matrix material layer in addition to the heat conduction and heat dissipation layer. Although it has a certain thermal conductivity, its compressibility is low

[0017] In summary, due to the inability to solve the compressibility problem of metal materials, most of the thermal interface materials in the prior art are composed of metal materials or carbon fiber materials with high thermal conductivity and polymer materials with certain compressibility. made of

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