Semiconductor Pad Configuration for Stress Relief
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Solution Overview
Problem
Existing semiconductor devices face issues with pad configuration, leading to reduced adhesion, poor mechanical performance, stress concentration, and reliability in temperature cycling and drop tests due to varying methods of pad formation and exposure.
Innovation Solution
A semiconductor device configuration incorporating a combination of solder mask defined (SMD) and non-solder mask defined (NSMD) pads, where NSMD pads are isolated from the solder mask and SMD pads are partially covered, optimizing pad placement to reduce stress concentration and enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pads are formed by different methods (SMD or NSMD), then pad functionality is achieved, but reliability varies under different stress conditions (drop test, thermal cycling, bending)
Solution Approach 1:
The pad array is segmented into corner pads and non-corner pads, with each segment having a different configuration (NSMD for corner pads, SMD for non-corner pads). This segmentation allows optimization of each segment for its specific functional requirements, improving overall reliability while maintaining configuration adaptability.
Solution Approach 2:
Different pad configurations are applied to different locations based on local stress requirements. Corner pads use NSMD configuration to withstand drop and bending stresses, while non-corner pads use SMD configuration for thermal cycling resistance. This local quality approach optimizes reliability at each specific location.
2Strength
If corner pads are configured as NSMD pads, then resistance to drop and bending stress is improved, but manufacturing complexity increases
Solution Approach 1:
The pad structure is divided into corner pads with NSMD configuration and non-corner pads with SMD configuration. This segmentation enables corner pads to provide enhanced stress resistance while maintaining overall manufacturing feasibility through standardized processes.
Solution Approach 2:
NSMD configuration is applied locally only to corner pads where stress resistance is critical, rather than uniformly to all pads. This localized application reduces the overall complexity increase while maintaining the strength benefits where most needed.
3Ease of manufacture
If all pads are configured as SMD pads, then manufacturing simplicity is maintained, but adhesion and mechanical performance deteriorate
Solution Approach 1:
SMD configuration is applied to non-corner pads where manufacturing simplicity is prioritized, while NSMD configuration is applied to corner pads where adhesion and mechanical performance are critical. This local quality differentiation balances manufacturing ease with reliability requirements.
Data Source
AI summary
A semiconductor device includes a substrate, a plurality of pads disposed over the substrate, and a solder mask disposed over the substrate. The substrate includes a pair of first edges parallel to each other, a pair of second edges orthogonal to the pair of first edges, and a center point. The solder mask includes four recess portions exposing an entire top surface and sidewalls of four of the pads in four corners of the regular array, and a plurality of second recess portions exposing a portion of a top surface of other pads in the regular array. A pad size of the four pads in the four corners of the regular array exposed through the first recess portions and a pad size of the other pads exposed through the second recess portions are the same.