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GAISER TOOL COMPANY

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GAISER SMALL WIRE WEDGE INFORMATION   

2. WEDGE DESIGN

The design of wedges over the last ten years has changed very little with the exception of the introduction of deep access wedge bonding. Most bonder manufacturers now offer a wedge bonder that enables the wire to travel through the center or down

the back of the wedge vertically. The tip configurations on these deep access wedges are generally the same as those offered for conventional bonding. The two tip configurations of wedges Gaiser offers are the V-notch and Maxiguide style. 

GTC Figure 41-2

Figure 2. Cross-sectional view of a V-notch wedge identifying the standard dimensions. 

GTC Figure 41-3

Figure 3. Cross-sectional view of a Maxiguide wedge, identifying the standard dimensions. 

There are several advantages to wedge bonding. One advantage is the ability of wedges to accommodate the increasing demand for bond-pitch applications below 0.004in./102. Another advantage is that the wire has minimal bond deformation width so the wire can be placed on a very narrow pad. In many cases, these two are related. Likely the greatest advantage is the wedge bonding allows the bonding of aluminum wire. Another advantage of wedge bonding over ball bonding is the ability to bond down into deep cavities and packages. Standard wedge tool

lengths are available up to 1.078in./27mm as compared to 0.750in./19mm tool lengths for ceramic capillaries. The problem with conventional wedge bonding down into these deep geometry's has been that, even with a 60 wire feed angle, the wire can interfere with the package wall or another device. Deep access wedge bonding differs from conventional wedge bonding by feeding the wire down through the center of the wedge. Deep access wedge bonding allows accessibility similar to a capillary.

GTC Figure 41-4

Figure 4. Conventional wedge bonding has limited accessibility due to the wire and clamp being located behind the wedge. 

GTC Figure 41-5

Figure 5. Deep access wedge bonding utilizes a through-the-wedge design. The wire feeds down through the center of the wedge, exits the wedge and then re-enters the wedge at the tip. This design allows for accessibility similar to a capillary.  

A principle disadvantage of wedge bonding is the wire is fed at a 30, 45 or 60 horizontal angle rather than perpendicular as in ball bonding. Also, wedge bonding is unidirectional.

This is slower than ball bonding which is multi-directional. Wedge bonding requires the circuit workpiece or the bonding head to rotate to allow for the wire to bond in the appropriate direction.

GTC Figure 41-6

Figure 6. A typical integrated circuit wedge bonded with aluminum wire on an automatic bonder.

(Photo: courtesy integrated Reliability Services, Inc.)

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