Lead Frame Edge Geometry to Prevent Resin Package Separation
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Solution Overview
Problem
Conventional semiconductor devices with resin packages face issues of separation between the conductor and sealing resin, leading to potential corrosion and leakage, which can result in device defects.
Innovation Solution
A semiconductor device design where the conductor has an obverse surface, a reverse surface exposed from the sealing resin, and an intermediate surface with specific edge configurations, ensuring the first edge is outward from the second edge, and the intermediate surface's geometry prevents easy separation from the sealing resin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the reverse surface of the lead frame is exposed from the sealing resin, then the lead frame can be easily manufactured and assembled, but separation between the lead frame and sealing resin occurs leading to corrosion and leakage
Solution Approach 1:
A resin non-adhesive portion is formed in advance on the reverse surface of the lead frame at the separation prevention portion before the molding process. This preliminary action prevents the sealing resin from adhering to this specific area, creating a barrier that stops separation propagation while allowing the rest of the lead frame to be securely held by the resin.
Solution Approach 2:
A specific portion of the lead frame reverse surface is excluded from the sealing resin adhesion zone. By extracting or removing the adhesive property from this specific area (creating a non-adhesive portion), the patent prevents the resin from bonding there, thereby stopping separation while maintaining bonding in other critical areas.
2Reliability
If the intermediate surface is fully covered with sealing resin, then separation is prevented, but the reverse surface cannot be exposed for electrical connection
Solution Approach 1:
The lead frame reverse surface is divided into different functional zones: a separation prevention portion with resin non-adhesive properties for exposed electrical connections, and other portions with normal adhesive properties for secure bonding. This local differentiation allows simultaneous achievement of exposure for connectivity and prevention of separation.
3Device complexity
If separation between lead frame and sealing resin occurs, then manufacturing is simplified, but corrosion and leakage current can intrude causing device defects
Solution Approach 1:
The resin non-adhesive portion is created in advance to counteract the harmful effect of separation before it can occur. By pre-establishing a barrier at the separation prevention portion, the patent proactively prevents corrosion and leakage current intrusion that would otherwise result from separation between the lead frame and sealing resin.
Data Source
AI summary
A semiconductor device includes a conductor, a semiconductor element, and a sealing resin. The conductor includes an obverse surface including a first edge, a reverse surface spaced apart from the obverse surface in a thickness direction and including a second edge, and an intermediate surface connected to the first edge and the second edge. The semiconductor element is supported on the obverse surface. The sealing resin covers the obverse surface, the semiconductor element, and at least a portion of the intermediate surface. The reverse surface of the conductor is exposed from the sealing resin. The first edge is located outward from the second edge as viewed in the thickness direction. In a cross section orthogonal to the first edge, the intermediate surface includes a first point located between the first edge and the second edge and a second point located between the first edge and the first point. The first distance from the obverse surface to the first point in the thickness direction is smaller than the second distance from the obverse surface to the second point in the thickness direction.