Chapter 1: Description; Section I. Features - Unitek MICROPULL IV MP4/115 Operation And Maintenance Manual

CHAPTER 1
DESCRIPTION
Section I: Features
The Micropull IV (herein called the MP4) is a semiautomatic machine designed to perform wire bond pull
tests in the 0.5 to 1000 gram-force range, using three interchangeable beams, at rates of up to one test per
second. The operator needs only to position the hook under the wire bond to be tested, and the MP4 will
automatically center itself and perform DESTRUCTIVE or NONDESTRUCTIVE wire bond pull tests and
display the test results, as well as transmit them to an optional RS-232C serial interface output connector.
The MP4 can automatically detect wire bond failures which occur during the test as well as excessive wire
bond loop height. This information is part of the output test data.
Bond pull tests are used routinely to evaluate and/or control the mechanical strength of wire bonds in
microcircuit devices. The bond pull test is performed by placing the microelectronic device in an
appropriate holder and positioning a hook under the wire midway between the two bonds. The hook is then
raised until the wire bond breaks (destructive pull test - DPT), or until the bond is stressed to a
predetermined value (nondestructive pull test-NDPT). The term "wire bond" commonly refers to the entire
interconnection consisting of both welds and the wire span. The term "bond" is used to identify a welded
area.
According to industry statistics, insufficient bond strength is a major cause of device failure. The intent of
the NDPT is to use a force great enough to cause weak bonds to fail, yet insufficient to damage good bonds.
Recommended values for the maximum safe forces for NDPT may be found in MIL-STD 883, Method 2011
and 2023. See Appendix B.
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MICROPULL IV WIRE BOND PULL TESTER
990-180 1-1