Shrinking electronic package geometries are driving continuous improvements in interconnect technologies. Wire Bonding is a mature technology that continues to meet challenges of finer geometric capability: loop shape, bond pitch, ball size, and stitch size control.
*The below rendering is a simplified representation of a wire interconnection showing the loop and change in ball and stitch geometries which occur during the ultrasonic bonding process.
Palomar engineers developed a method called "Adaptive Bond Deformation
" (ABD) method to enable the user to better improve cost-effectiveness of their wire bonding and ball bumping system (side note: unique ball bump applications where material, process and tool variations adversely affected yields due to occasional shorting of adjacent bumps were part of the motivation in developing ABD).
The essence of ABD is to improve bond geometry; to control the geometry of both ball and stitch according to process parameter inputs supplied by the user; the technique adapts to normal variations in bond surface, bond tool coupling, part fixture, and other difficult to measure influences. Using Adaptive Bond Deformation the user is able to produce bonded ball bumps, and stitches with significant improvement in geometry consistency with similar or better results for ball shear and pul strength when compared to non-adaptive bonding.
Adaptive Bond Deformation was developed to meet the challenges of the packaging industry. These challenges require a common set of improvements as geometries continue to shrink:
1) Uniformity of ball bump heigh and/or bump diameter to allow...
a. Reduced bond pitch for wires
b. Reduced bond pitch for bumps
c. Better bump co-planarity
2) Uniformity of stitch impressions to...
a. Minimize adverse impacts to sensitive materials for stitch
3) Process...
a. Reduced process develop time
b. Reduce sensitivity to material, environment, and setup variation
c. Real-time capture/qualification of production data
d. Data trending analysis of production data