原文链接在这里：www.electronics-cooling.com/1998/05/conduction-heat-transfer-in-a-printed-circuit-board/

以下中文部分是我的笔记：

In this issue, we examine heat flow in a printed circuit board (PCB), which typically is a layered composite consisting of copper foil and a glass-reinforced polymer (FR-4).

A cross-sectional view of such a laminated structure is illustrated in Figure 1. The Figure indicates the numbering system that will be used for indicating the different layers, numbered 1 through to N.

Figure 1: Cross-sectional area of PCB.
 

In many thermal calculations, it is convenient to treat such a layered structure as an homogeneous material, with two different effective thermal conductivities:

这2个公式的推导如下：

1 垂直方向上的各层材料之间的热阻为串联关系，即Rthrough=∑Ri=∑（ti/Ki），又根据公式q/ΔT=Rthrough=Σt/Ktrough，则Kthrough=Σt/∑（ti/Ki）。

2 平面之内的热阻为并联关系：

The calculated values of these two quantities are presented in the graph below. In this calculation, it is assumed that the total PCB thickness is 1.59 mm and that the layers consist

 

FR4总厚度为1.59-0.07=1.52mm，铜箔总厚度为0.07mm，假设覆盖率为1。

Hence, it is clear that in most electronic applications, KIn-Plane of the PCB is much less than that of a solid plate of copper. The results show that a typical PCB is not an efficient conductor of heat, leading to significant local variations in the PCB temperature in the vicinity of heat-generating components.

References

J.E. Graebner, “Thermal Conductivity of Printing Wiring Boards”, Technical Brief, Electronics Cooling Magazine, Vol. 1, No.2, October, 1995, p. 27

K. Azar and J.E. Graebner, “Experimental Determination of Thermal Conductivity of Printed Wiring Boards,” Proceedings, SEMI-THERM XII Conference, March, 1996, pp. 169-182.

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