GAISER TOOL COMPANY

PREVIOUS PAGE

NEXT PAGE

GAISER CAPILLARY INFORMATION

Figure 2. Besides two capillaries, one with a tip diameter (T dimension) of 0.0090in./229µm; the other T dimension is 0.0065in./165µm. The larger T dimension provides a longer bond length for a successful second bond; however the larger T dimensions limits access into fine-pitch applications.

Figure 3. Picture to the right shows an example of a weak/chopped-off second bond. The primary reasons for weak/chopped-off bonds are: 

Figure 4. The stitch bond on the left is made with a capillary having the T=0.0059in./150µm. The middle stitch bond is made with a  T=0.0065in./165µm. The stitch bond on the right is made with a T=0.009in./229µm. A larger T dimension provides a longer bond length and therefore a larger surface area for a superior intermetallic weld. 

Figure 5. A tool with the same capillary tip may provide stitch bonds with different widths. A stitch bond made in the East-to-West direction will be wider than a stitch bond made in the North-South direction. This is due to the ultrasonic motion of the capillary scrubbing across the wire. A stitch bond made in the North-to-South direction will be because the ultrasonic motion scrubs in-line with the wire.
Many of the newer wire-bonding machines are capable of counteracting some of the effect of the direction of the ultrasonic's by stage motion and other techniques. The goal of these innovations is to minimize the difference in stitch-bond strengths. To date, the scrub direction issue has not been completely resolved.

Figure 6. There are several reasons for second bond nonsticking. Some of these are:

Get the BASIC CAPILLARY BONDING and DESIGN document in format

PREVIOUS PAGE

NEXT PAGE