Lead Frame Recess Layout for Void-Free Resin Encapsulation
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Solution Overview
Problem
The formation of voids between the lead frame and the semiconductor chip during resin injection is a challenge in the manufacturing process of semiconductor devices, particularly when the gap between them is narrow.
Innovation Solution
The lead frame is designed with recesses between adjacent bonding areas on its terminal portions, which open on the upper surface and extend to the side surfaces, facilitating the flow of resin and reducing the likelihood of void formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the gap between the lead frame and the semiconductor chip is narrowed, then the bonding strength is improved, but the resin flow is hindered causing void formation
Solution Approach 1:
The lead frame surface is segmented into multiple bonding areas separated by recesses. This segmentation allows the resin to flow through the recesses and reach all bonding areas effectively, preventing void formation while maintaining narrow overall gap for strong bonding.
Solution Approach 2:
Different regions of the lead frame have different properties: bonding areas provide strong adhesion for electrodes, while recesses provide fluid channels for resin flow. This local differentiation resolves the contradiction between needing narrow gaps for strength and open spaces for resin flow.
2Reliability
If recesses are added to the lead frame, then the resin flow is improved, but the device complexity increases
Solution Approach 1:
The lead frame is segmented into bonding areas and recesses in a regular, repeating pattern. This systematic segmentation improves resin flow without creating excessive complexity, as the pattern can be easily manufactured and replicated.
Solution Approach 2:
The lead frame incorporates a porous-like structure with recesses that facilitate resin penetration. This approach improves resin flow characteristics while maintaining a relatively simple overall structure that can be manufactured using standard processes.
Data Source
AI summary
A lead frame includes a plurality of terminal portions including a first terminal portion, wherein the first portion has an upper surface and at least one side surface, and includes a plurality of bonding areas that are defined on the upper surface within a mounting region where a semiconductor chip is to be mounted, the bonding areas being designated for bonding with respective electrodes of the semiconductor chip, and a recess that is provided between adjacent bonding areas among the plurality of bonding areas and that opens on the upper surface, the recess reaching the at least one side surface.