Page 100 - Wire Bonding in Microelectronics

CHAPTER 4

Wire Bond Testing

4.1 Introduction
The measurement methods, techniques, and equations used for
evaluating wire bonds were developed many years ago and described
in earlier editions of this book. Few modern papers present new
approaches, except for the testing of fine pitch ball bonds. Therefore,
this chapter has been brought up to date, by noting changes required
by finer pitch (more fully described in Chap. 9), or by changing/adding
appropriate figures and references when needed rather than com-
pletely rewriting for the sake of change. Only when a newer figure
or reference is judged to be better or clearer, will it be added here.
Several original figures have been redrawn/modified for more com-
plete or extended understanding and the Web-available EIA shear
test specification is included and discussed. Many of the recent
advances have resulted from improvements in the test equipments’
precision and convenience, rather than fundamental new measure-
ment methods or principles. The author has added judgments and
comments thought to be helpful for those new to the field. The latest
Mil-Std 883G/H criteria are discussed in this chapter, but it is real-
ized that today there is minimal military-driven production. Com-
mercial in-house specifications vary widely but are frequently based
on the web-available military specifications and measurement meth-
ods which are used internationally. They are a good starting point,
but often have lower quantitative (compromise) specifications than
used by many organizations.
Autobonders have extended their capability to make very long
wire loops for small diameters, and techniques have been developed
to make very low loops. Both of these affect wire bond testing, but the
equations describing the bond-pull test are still valid in these extreme
cases, with a few caveats to detail their use/limits.
Although the major part of this book is concerned with the yield
and reliability of wire bonds, the normal method for evaluating these
problems involves some form of testing. The most common method
for evaluating wire bonds is still the pull test, primarily destructive,
but, to a much smaller extent, nondestructive. Details of these tests

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