TABLE OF CONTENTS The reliability of an adhesive and its impact on the performance of an electronic assembly should be considered in the initial selection of the adhesive and the design of the system. The function that the adhesive must perform for a specific application, the environment it is expected to encounter, and its duration are all important. Various approaches may be used to predict and assure reliability. Key among these approaches is a basic under-standing of possible failure modes and mechanisms. Most failure modes attributed to adhesives are now well understood and documented so that they can be avoided in the initial selection and qualification of the adhesive and in its processing.
Secondly, accelerated tests can be used to qualify adhesives for specific applications, and the data from them can sometimes be extrapolated to long-term, real-time performance. Accelerated tests are also valuable as screen tests and as acceptance tests and are specified in material-procurement documents or in hardware acceptance specifications. Adherence to material and process specifications and their quality-control provisions is an essential element in assuring reliability. Life prediction through modeling is yet another approach, but it is outside the scope of this chapter.
Lastly, there are extensive databanks of real-time performance for adhesives that have been used in numerous applications, various environments, and for extended periods of time the so-called heritage data.
The major failure modes of adhesives include loss of adhesion, high thermal impedance, loss of electrical contact, and corrosion. To a lesser extent, failures...
