Nondestructive Pull Testing Reshaping The Wire Bonds - Unitek MICROPULL IV MP4/115 Operation And Maintenance Manual

CHAPTER 1: SYSTEM DESCRIPTION
hook is allowed to pivot through a limited angular range in the front-to-back plane and is not allowed to
pivot from side-to-side. The MIL-STD also requires that the Non-Destruct pull should start with the
hook positioned midway between the two bonds. Assuming single level bonds, the result is that the
wire bond is reformed into an isosceles triangle wherein the pull force on each bond is equal, as shown
in figure 1-2.
Model B100R Rotatable Hook Beam - This beam has a 360 degree manually rotatable hook affixed to
the end of the beam. This design facilitates testing of long "stick-type" lead frames. The coupling
design quickly dampens any swinging motion of the hook. This beam will meet the accuracy
requirements of the MIL-STD when used with the supplied hooks, however the wire bonds are not
always reformed in accordance with the MIL-STD.
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Figure 1-2. Nondestructive Pull Testing Reshaping the Wire Bonds
The Hook Assembly for the B10 and B100 beams is inserted into the beam using a special insertion tool
(figure 1-3). The hook assembly for the B100R consists of several parts which are assembled using a T-
handle insertion tool (figure 1-4). The hook on the 1000gf beam, figure 1-5, is attached to the bottom of
the hook shaft. The weight of the hook assembly is critical to both the operation and the accuracy of the
measuring system. Because of inertia, large massive hooks, whose weight typically exceeds 0.2 grams,
cannot meet the accuracy requirements of the MIL-STD when used at normal speeds in the 0.5 to 10 gf
pull range, on either the 10gf or 100gf beams. Hooks weighing up to 10 grams can be used on the
1000gf beam.
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MICROPULL IV WIRE BOND PULL TESTER
990-180 1-5