Semiconductor Lead Frame Layout for Larger Die Pad Mounting
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Solution Overview
Problem
Existing semiconductor devices face challenges in increasing the size of the die pad without causing cracks or fractures in the inclined portions of the lead frame and defects in the sealing resin, limiting the expansion of the semiconductor element's mounting area.
Innovation Solution
The semiconductor device design includes a first lead with no bent portions formed by a depression process, featuring exposed reverse surfaces and specific resin side surface configurations, allowing for increased size of the mounting area while maintaining structural integrity and improving heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the size of the die pad is increased in plan view, then the mounting area is expanded, but the bending angle of inclined portions must be increased which causes cracks or fractures in the lead frame
Solution Approach 1:
Instead of bending the lead frame upward to expose the die pad reverse surface (which requires large bending angles and causes cracks), the patent inverts the approach by depressing the lead frame downward. This creates exposure of the die pad reverse surface through downward deformation rather than upward bending, thereby expanding the mounting area without compromising lead frame strength.
Solution Approach 2:
The patent changes the deformation direction parameter from upward bending to downward depression. This parameter change allows the die pad reverse surface to be exposed while using smaller deformation angles, preventing cracks and fractures in the lead frame during the deformation process.
2Area of moving object
If the bending angle of inclined portions is increased to expand mounting area, then more surface is exposed, but cracks or defects occur in the sealing resin between fixing portions and resin bottom surface
Solution Approach 1:
The patent inverts the deformation direction from upward bending to downward depression. This inversion reduces the exposure of sealing resin to large deformation stresses, preventing cracks and defects in the sealing resin while still achieving adequate exposure of the die pad reverse surface for heat dissipation.
Solution Approach 2:
The depression process is designed to gradually deform the lead frame downward, cushioning the stress to prevent sudden cracking in the sealing resin. The process controls deformation in a manner that protects the sealing resin integrity while achieving the desired exposure.
3Area of moving object
If the size of die pad is increased relative to package size, then mounting capacity improves, but structural integrity is compromised due to required deformation
Solution Approach 1:
By inverting the deformation direction to downward depression instead of upward bending, the patent maintains structural integrity while increasing die pad size. The downward depression creates the necessary exposure for heat dissipation without compromising the overall structural stability of the semiconductor device.
Data Source
AI summary
The semiconductor device includes a first lead on which the semiconductor element is mounted, a plurality of second leads, and a sealing resin. The sealing resin includes first resin side surfaces located on the respective sides in a first direction, and second resin side surfaces located on the respective sides in a second direction. The first lead has a first end surface exposed from one of the first resin side surfaces. The second leads protrude from the second resin side surfaces in the second direction. The first end surface includes a first edge located on a first side in the thickness direction. Each of the second leads includes a second edge located on the first side in the thickness direction, in an area where the second lead intersects one of the second resin side surfaces. The first edge is located on a second side in the thickness direction relative to the second edge.