Question

Material selection is one of the design considerations for electronic packages. Explain how each of the material properties below can affect the reliability of a Plastic Quad Flat Package (PQFP) subjected to accelerated thermal cycling (ATC) test. a) Glass Transition Temperature of Encapsulant b) Coefficient of Thermal Expansion of Encapsulant

Answer 1

Answer:

The explanations are provided below.

Explanation:

a) The accelerated thermal cycling test is a test that is performed to evaluate the fatigue strength of electronic solder connections. The glass transition temperature given as $T_{g}$ is a frequently used parameter to test the degree of cure of an epoxy encapsulant.

b) The Coefficient of Thermal Expansion of Encapsulant

This is an important parameter to prevent crackling. Crackling occurs when a joint is subjcted to high temperatures during reflow soldering. Thus, the property is important in determining the limits of the joint.