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GAISER SMALL WIRE WEDGE INFORMATION   

6. BACK RADIUS PAGE 1 (2)

The BR has two functions. The first function is to provide the transition between the wire and the first bond or die bond.

The second function is to provide the area on the wedge where the wire will terminate on the lead bond.  

GTC Figure 43-13

Figure 13. This die bond was made by p/n 2130-2525-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. 

Microwave 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./51 inches across and less than 0.004in./102 on center. The advantage

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./25 to 0.0005in./13. Most microwave devices are wedge bonded with gold wire.

GTC Figure 43-14

Figure 14. 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.

GTC Figure 43-15

Figure 15. This photo is a bond made with p/n 2131-2525-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 wedges. The 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 area.

GTC Figure 43-16

Figure 16. 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.

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Last modified: 2016-08-22