电子设备中导热衬垫的选型及散热凸台的设计

导热衬垫和散热凸台的组合使用是电子设备板卡上散热器件常见的散热方式之一。散热器件和印制板的尺寸公差较大，导致导热衬垫的选型和散热凸台的设计变得困难，因此提出一种新的导热衬垫选型和散热凸台设计的方法。首先建立散热器件与散热凸台之间间隙的两种尺寸链模型。然后利用概率法分析尺寸链，推导得到导热衬垫厚度选择的充要条件及一般准则。进一步，基于封闭环中间偏差的计算，推导了散热凸台高度的计算公式。最后进行实例分析以验证该方法的有效性，结果显示导热衬垫能够补偿散热器件与散热凸台之间间隙的置信度大于99.75%。该方法为导热衬垫的选型及散热凸台的设计提供了理论依据。

Selection of Thermal Gap Filler and Design of Cooling Block in Electronic Devices

The combination of thermal gap filler and cooling block is one of the common ways of heat dissipation in electronic devices. The large dimensional tolerance of the printed circuit board and the electronic components on it brings difficulties to the selection of thermal gap filler and the design of cooling block. Thus, a new method to select the thermal gap filler and design the cooling block is proposed. Firstly, two dimension chain models of the clearance between electronic components and cooling blocks are established. Then the necessary and sufficient conditions and general criteria for the selection of the thermal gap filler are deduced by using probability methods to analyze the dimension chain. Furthermore, the calculation formula of the height of cooling block is derived based on the calculation of the intermediate deviation of the closed loop. Finally, the proposed method is validated by an example. The results show that the confidence coefficient that the thermal gap filler can eliminate the clearance between electronic components and cooling blocks is greater than 99.75%. The proposed method could be used as a theoretical basis for the selection of thermal gap filler and the design of cooling block.