Semiconductor Package Stepped Pad Opening for High-Voltage Wire Bonding
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Solution Overview
Problem
High-voltage electrical isolation is challenging near the contact pads of semiconductor chips due to the risk of bond wire quality deterioration and package reliability issues when the capillary vessel contacts the polymer layer during wire bonding.
Innovation Solution
A semiconductor package design featuring a polymer layer with a stepped opening structure, where the upper segment is thicker than the lower segment, preventing the capillary vessel from contacting the polymer layer during bonding, and using a conductive base attached to the bond pad through the insulating and polymer layer openings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick polymer layer is applied around the bond pad opening for high-voltage insulation, then electrical isolation is improved, but the capillary vessel may contact the polymer layer during wire bonding which deteriorates bond wire quality and package reliability
Solution Approach 1:
The polymer layer is segmented into two distinct segments: a first segment with a first opening and a second segment with a second opening. This segmentation allows the capillary vessel to pass through the openings without contacting the polymer material, thereby maintaining electrical isolation while preventing harmful contact during bonding.
Solution Approach 2:
Different regions of the polymer layer are given different properties through the segmented opening structure. The areas around the openings are designed to be open (no polymer) to allow capillary access, while other areas maintain thick polymer coverage for electrical isolation. This local differentiation resolves the contradiction between isolation and accessibility.
2Reliability
If the bond pad opening is made small to improve electrical isolation, then insulation performance is improved, but wire bonding becomes more difficult and bond wire quality may deteriorate
Solution Approach 1:
The polymer layer is divided into segments with strategically positioned openings. The first opening allows access to the bond pad for wire bonding, while the second opening provides an escape route for the capillary vessel. This segmentation enables small overall opening dimensions for isolation while maintaining adequate access points for manufacturing.
Solution Approach 2:
The segmented opening structure acts as an intermediary between the conflicting requirements of small opening size (for isolation) and adequate access (for bonding). The openings provide controlled access paths that mediate between the insulation requirement and the manufacturing requirement.
Data Source
AI summary
A semiconductor package includes a semiconductor die having a bond pad, an insulating layer covering the bond pad and having an opening with sidewalls, a polymer layer formed over the insulating layer and covering the sidewalls of the opening in the insulating layer, the polymer layer having an opening, and an electrical conductor having a conductive base attached to a part of the bond pad exposed by the insulating layer opening and the polymer layer opening. The polymer layer includes an upper segment and a lower segment. The polymer layer opening is larger in the upper segment than in the lower segment.