High-Angle Wire Bonding With Non-Gold Wires in Semiconductor Packages
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Solution Overview
Problem
Semiconductor device packages require high angle wire bonds to prevent electrical arcing between high voltage and low voltage components, but existing lower cost bond wires like palladium coated copper (PCC) are unable to form high angle stitch bonds, necessitating the use of gold bond wires for certain connections, increasing costs.
Innovation Solution
The use of non-gold bond wires, such as PCC, bare copper, or gold coated copper, in combination with flex stud bumps and high angle stitch bonds on bump connections, allows for the formation of high angle wire bonds without the need for gold, reducing costs and manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lower cost bond wires like PCC are used, then cost is reduced, but high angle stitch bonds cannot be formed
Solution Approach 1:
A flexible stud bump is introduced as an intermediary element between the bond pad and the bond wire. The flex stud bump has an asymmetric shape with a peak offset from the center, allowing the bond wire to approach at a high angle while maintaining reliable electrical connection. This mediator enables lower cost bond wires like PCC to achieve high angle stitch bonds that previously required gold wire.
2Reliability
If gold bond wires are used for high angle connections, then reliable high angle stitch bonds are achieved, but package cost increases
Solution Approach 1:
The invention replaces expensive gold bond wires with lower cost alternatives like PCC (palladium coated copper) bond wires. The flex stud bump structure compensates for the reduced ductility and bonding capability of cheaper materials, enabling reliable high angle connections without gold wire, thus reducing package cost while maintaining reliability.
3Quantity of substance
If two different bond wire types are used together, then some cost reduction is achieved, but manufacturing complexity increases
Solution Approach 1:
The flex stud bump structure provides a universal solution that works with various lower cost bond wire types (PCC, bare copper, gold coated copper). By standardizing on the flex stud bump approach, the manufacturing process can use a single bond wire type for all connections, eliminating the need for multiple wire types and the associated complexity of switching between them during the bonding operation.
Data Source
AI summary
In a described example, an apparatus includes: a package substrate having a die mount portion and lead portions spaced from the die mount portion; a semiconductor die over the die mount portion having bond pads on an active surface facing away from the package substrate; non-gold bond wires forming electrical connections between at least one of the bond pads and one of the lead portions of the package substrate; a bond stitch on bump connection formed between one of the non-gold bond wires and a bond pad of the semiconductor die, comprising a stitch bond formed on a flex stud bump; and dielectric material covering a portion of the package substrate, the semiconductor die, the non-gold bond wires, the stitch bond and the flex stud bump, forming a packaged semiconductor device.