The thermal resistance equations, 1 and la, men- tioned previously can be derived using Fourier's law stating that the rate of heat flow (P) through a material is proportional to the cross sectional area (A) of the material normal to the heat flow, the temperature gra- dient (T) along the thickness (x) of the material, and the thermal conductivity (K), a constant and a basic property of the material. The value of K is in units of W/IC-cm mathematically:
| l | | | | l l 1 1 | |
| | | | | | l l | |
| -2y | < | | | | | 1 00 LLS Ims | |
| | | | | | |
| | DC | 0 | ATIO | N | | 10m< | |
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