Semiconductor Dam Bar Cutting Punch with Groove Portions
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Solution Overview
Problem
The existing methods for cutting dam bars in semiconductor devices often result in excess resin portions being punched through, leading to stress on the resin body and potential cracks, especially in miniaturized devices, due to the large overlapping area between the punches and excess resin, which also generates debris and complicates the cutting process.
Innovation Solution
A punch with a cutting edge featuring two convex portions and a concave portion is used to minimize the overlap with the excess resin portion, forming groove portions that reduce the stress on the resin body and prevent cracking by limiting the cut region, thereby ensuring reliable dam bar cutting with minimal stress on the excess resin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If punches are used to cut dam bars with large overlapping area with excess resin portions, then reliable cutting of dam bars is achieved, but stress is imparted to the resin body causing cracks and debris generation
Solution Approach 1:
The punch is divided into multiple cutting edges arranged in a specific pattern. The punch includes a first cutting edge that cuts the dam bar and a second cutting edge that cuts the excess resin portion, separating these functions into distinct edges to reduce stress concentration on the resin body while maintaining reliable cutting
Solution Approach 2:
The invention transitions from considering only the cutting depth dimension to incorporating the horizontal arrangement of cutting edges. By positioning cutting edges at different locations and angles on the punch surface, the stress distribution is optimized across multiple dimensions, reducing the harmful stress concentration that causes cracks
2Reliability
If punches overlap with excess resin portions to ensure dam bar cutting, then cutting reliability is improved, but debris is generated and removal steps are required
Solution Approach 1:
The invention extracts only the necessary portion of the excess resin for cutting by designing the punch to create groove portions that limit the cut region. The second cutting edge is positioned to cut only the minimal required amount of excess resin, separating the useful cutting function from the harmful debris generation
Solution Approach 2:
Different regions of the excess resin are treated differently: the groove portions are cut to remove debris-prone areas, while other regions are left intact. This localized cutting approach maintains reliability where needed while minimizing debris generation in other areas
3Object-generated harmful factors
If the gap between dam bar and resin body is reduced to minimize excess resin portion, then debris generation is reduced, but the excess resin portion may drop off inconveniently
Solution Approach 1:
The groove portions are formed within the excess resin portion in a nested manner, creating contained cut regions that prevent the excess resin from dropping off while still removing enough material to minimize debris. The groove structure provides mechanical support to the excess resin
Data Source
AI summary
A partly finished product of a semiconductor device includes a resin body encapsulating a semiconductor chip, first and second leads extended outwardly from the resin body, a dam bar connected between said first and second leads, and an excess resin portion protruding from the resin body between the first and second leads and the dam bar. The excess resin portion is cut off at two limited portions, and thereby two groove portions are formed in the excess resin portion. An apparatus for cutting the dam bar includes a punch having a cutting edge for cutting connection portions between the first and second leads and the dam bar and for cutting off the two limited portions of the excess resin portion. Since the cut region of the excess resin portion becomes smaller, a stress imparted to the resin body and/or the semiconductor chip through the excess resin portion can be smaller.