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GAISER TOOL COMPANY

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GAISER SMALL WIRE WEDGE INFORMATION   

10. FINE PITCH WEDGE BONDING PAGE 1 (2)

Many new packages are incorporating pad pitches of 0.004in./102m and less. These new fine-pitch designs limit the accessibility of a capillary to form a ball bond. Without reducing the capillary tip diameter to below 0.005in.127/m many applications cannot be bonded successfully. When the tip diameter is reduced to this size and smaller, the resulting length of the lead bond becomes shorter. When this occurs, non-sticks on the lead or poor pull strengths may result.

With wedge bonding, the lead bond is not degraded as the pitch become narrower. The average small wire wedge has a foot width (W) of 0.004in./102m. A "W" dimensions of 0.003in./76m or smaller may be called out if necessary. The 0.003in./76m W allows for bonding in fine-pitch packages. Wedge bonding is a slower process, but with the continued miniaturization of packages and die, it offers a viable option to capillary bonding.

GTC Figure 47-36

Figure 36. The two wedges above vary in the size of the W dimension. The right wedge has the standard W=0.004in./102, the left wedge has the W=0.003in./76. This modification can be requested by adding "W=003" to the end of the p/n. 

GTC Figure 47-37

Figure 37. These two drawings show the wire profile produced from typical looping parameters used for wedges. Note that the already bonded wire does not collide with the side of the wedge because the apex of the loop is behind the wedge. Since the majority of the looping profiles are at a low angle, the primary fine pitch problem is clearing the adjacent bond. 

GTC Figure 47-38

Figure 38. This drawing shows the primary problem with fine-pitch wedge applications. An option to provide clearance for the adjacent bonds is to call out a smaller W dimension as shown in Figure 36. 

The 45 side chamfer modification may also be used on fine-pitch wedge applications. The primary benefit of the 45 side chamfer is the wedge maintains the majority of its mass.

This allows for transferring ultrasonics more efficiently and the 45 side chamfer can be added to the maxiguide-style wedge without weakening the guiding slow walls.

GTC Figure 47-39

Figure 39. This drawing shows a wedge that has the 45 side chamfer. This modification can be requested by adding "45SC (W=specify)" to the end of the p/n. 

Get the FINE PITCH WEDGE BONDING Document (in FINE PITCH WEDGE BONDING format).

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