Under-Bump Pad Structure for Crack-Resistant Semiconductor Packaging
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Solution Overview
Problem
Existing semiconductor packages face challenges in achieving structural stability and efficient stress distribution, particularly in the under-bump pad region, which can lead to crack propagation and instability during connection terminal attachment.
Innovation Solution
The semiconductor package incorporates an under-bump pad design with a first pad part and a second pad part, where the second pad part has a greater width than the first, and a via part connecting them, providing enhanced structural stability and stress alleviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a conventional under-bump pad design is used, then the manufacturing process is simple, but the structural stability is insufficient and crack propagation occurs
Solution Approach 1:
The under-bump pad is divided into multiple segments including a first pad part, a second pad part, and a via part. This segmentation allows each part to perform specific functions: the first pad part provides electrical connection, the second pad part increases connection area for stress distribution, and the via part provides vertical electrical connection between layers, thereby improving structural stability without excessive complexity
Solution Approach 2:
The under-bump pad structure transitions from a two-dimensional planar pad to a three-dimensional multi-layer structure by adding the via part that protrudes vertically and the stacked first and second pad parts. This dimensional change enables better stress distribution and crack propagation blocking while maintaining manufacturing feasibility
2Stress or pressure
If the under-bump pad width is increased to improve stress distribution, then stress distribution improves, but the area available for wiring patterns is reduced
Solution Approach 1:
The pad structure is segmented into first and second pad parts with different widths. The second pad part has a greater width than the first pad part, creating a stepped configuration. This segmentation allows the wider second pad part to handle stress distribution while the narrower first pad part preserves area for wiring patterns, resolving the contradiction between stress distribution and wiring space
Solution Approach 2:
Different regions of the under-bump pad are assigned different widths locally. The second pad part is locally widened to improve stress distribution and crack propagation resistance, while the first pad part maintains a narrower width to preserve wiring pattern area. This local quality variation optimizes both stress distribution and wiring space utilization
Data Source
AI summary
A semiconductor device including a redistribution substrate and a semiconductor chip on the redistribution substrate. The redistribution substrate includes an under-bump pad on a bottom surface of the redistribution substrate. The under-bump pad comprises a first pad part, a second pad part on the first pad part, and a via part that protrudes from the second pad part and contacts the first pad part. The first pad part has a first width in a first direction parallel to a top surface of the redistribution substrate. The second pad part has a second width in the first direction. The second width is greater than the first width.