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Face Angle

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GAISER TOOL COMPANY

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GAISER CAPILLARY INFORMATION

4. FACE ANGLE

GTC Figure 7

Figure 7. The zero degree (0) face angle provides the greatest downward force on the stitch bond; however, it may result in heel cracking problems.
To reduce this problem, 0 face angle capillaries are designed with a larger outside radius of 0.0025"/64u or larger. 0 face angle capillaries have shown to work well for lead frames with lead planarity problems. 

 

GTC Figure 8

Figure 8. The eight degree (8 ) face angle is probably the most successful dimensional characteristic of modern capillary design. The 8 face angle provides adequate force down on the stitch bond and limits heel crack problems. This is due to the thicker cross-sectional area of the wire under the face up to where the outside radius begins. The 8 face angle capillary works well over the broadest range of moralizations; i.e., thick film, thin film, soft and hard moralizations.  

 

GTC Figure 9

Figure 9. The four degree (4) face angle provides a compromise between the 0 face angle and the 8 face angle capillary. The 4 face angle provides more force down on the stitch bond than the 8 face angle. This allows for a stronger stitch bond but can lead to the possibility of heel cracks or chopped off stitches. This is due to the thinner cross-sectional area of the wire under the face.
The 4 face angle is recommended when power and time (instead of force) are used to correct stitch bond nonsticking problems.

 

GTC Figure 10

Figure 10. Causes for a week transition from the stitch bond to the Wire include:

bullet Face angle of capillary too shallow
bullet Too small or sharp outside radius size due to design or wear
bullet Excessive force setting, causing tip to penetrate bonding pad
bullet Excessive power setting especially when force setting is too high
bullet Improper lead clamping allowing shifting of the bond

Get the BASIC CAPILLARY BONDING and DESIGN document in BASIC CAPILLARY BONDING/ DESIGN format

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