The BR has two functions. The first function
is to provide the transition between the wire and the first bond or die
The second function is to provide the area on
the wedge where the wire will terminate on the lead bond.
This die bond was made by p/n2130-2525-L
with a straight BR. The length of wire not bonded on the left side is referred to as the
tail. The tail length should not extend beyond the pad due to shorting problems. The
straight BR helps provide for very consistent tailing.
diodes, transistors and GaAs devices generally have gold as their surface
layer and have small bonding pads. Some of these bonding pads measure less
than 0.002in./51µ inches across and less than 0.004in./102µ on center.
of wedge bonding over ball bonding is the ability to form bonds on such
narrow closely spaced bond pads. Typical wire diameters for microwave
applications range from 0.001in./25µ to 0.0005in./13µ. Most microwave
devices are wedge bonded with gold wire.
Shows a minor heel crack. The amount of heel cracking allowed depends on the QA standards
of the end customer. The BR shape and size may help to eliminate or reduce the problem.
This photo is a bond made with p/n2131-2525-L.
The elliptical BR on this wedge provides a stronger bond by increasing the cross-sectional
area of the heel. This helps reduce heel cracks often associated with standard
elliptical BR is standard on the 2131 series and is an available option on other Gaiser
wedges. The elliptical BR may cause inconsistent tailing as it creates a stronger heel
This bond was made by a maxiguide style p/n 2130-2525-L-CBR
(chamfered back radius) wedge. The chamfer produces a slope to the BR and helps to reduce
heel cracks. It may cause inconsistent tailing due to a stronger heel area.