Reliability Technology: Principles and Practice of Failure Prevention in Electronic Systems

Appendix 1

Physical Properties of Materials

Overview

Notwithstanding the availability of materials data from internet and other sources, experience indicates that an inordinate length of time can be spent in searching for specific material properties. The author hopes that this Appendix will provide a convenient, rapid access to information relating to materials properties relevant to the content of this book. Material property definitions are included in this Appendix in order to provide the reader with a grouped access to the laws of physics that pertain to the engineering disciplines associated with the practice of effective failure prevention.

Thermal Properties – Definitions

Thermal Conductivity. This is defined as the rate of flow of heat trough a material per unit area, per unit temperature gradient.

For a conductor of length x (m), uniform cross-sectional A (m²) and thermal conductivity k, whose opposite ends are maintained at temperatures θ₂ (K) and θ₁ (K) (θ₂ > θ₁), the quantity of heat Q (kJ s⁻¹) passing any point within the conductor in time t (s) when the steady state has been reached is given by the equation:

(A.1.1)

The unit of thermal conductivity k is W m⁻¹ K⁻¹.

Density. The density ρ of a sample of a substance of mass m and volume V is defined by the equation

(A.1.2)

Density may be expressed as mass per unit volume.

The unit of density is kg m⁻³.

Specific Heat ...