Chapter 4

Heat Transfer – Theory and Practice

Science is built up of facts, as a house is built of stones; but an accumulation of facts is no more a science than a heap of stones is a house.

Science and Hypothesis (1950 ch. 9)

4.1 Overview

An understanding of the physical mechanisms involved in the transfer of heat within a material and from one material to another is an essential attribute for the design of reliable electronic hardware. The material contained within this chapter will, hopefully, also help to provide a clearer understanding of the principles of heat transfer that make such an important contribution to the development of effective reliability growth programmes. In order to generate realistic thermal stresses, and stimulate effective thermal responses within electronic hardware for the purpose of achieving effective qualification, accelerated ageing, and Stress Screening objectives, the essential physics of heat transfer and thermomechanical ageing must be properly understood.

This chapter deals with the basic principles of heat transfer and temperature measurement for those design, test, and reliability engineers who seek to strengthen their understanding of the influence of cyclic thermomechanical behaviour on product robustness and durability. The thermal management of electronic hardware, and the forced stimulation of cyclic thermomechanical stress reversals within electronic hardware, are treated as two distinctly different topics of concern.

There are two ...

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