Leadframe Retaining Features for Mold Compound Delamination
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Solution Overview
Problem
The challenge in semiconductor package manufacturing is the delamination of molding compound from leadframes due to the miniaturization trend, which affects adhesion and increases production failures.
Innovation Solution
The introduction of retaining features on the leadframe surfaces, designed to interlock with the molding compound, increases adhesion by providing additional surface area and mechanical interlocking forces, reducing delamination and enhancing production yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the leadframe size is reduced to meet miniaturization trends, then the semiconductor package becomes smaller and more densely packed, but the adhesion between molding compound and leadframe decreases causing delamination
Solution Approach 1:
The patent applies dimensionality change by transitioning from a two-dimensional flat leadframe surface to a three-dimensional surface with retaining features (protrusions, recesses, or both). This adds vertical dimension to the interface between leadframe and molding compound, creating mechanical interlocking that compensates for the reduced overall package size while maintaining or improving adhesion strength.
Solution Approach 2:
The retaining features segment the continuous leadframe surface into multiple discrete interaction points (protrusions and/or recesses). This segmentation creates numerous localized bonding zones distributed across the leadframe surface, increasing the total effective adhesion area and preventing delamination even when the overall package size is reduced.
2Reliability
If retaining features are added to the leadframe surface, then adhesion and mechanical interlocking with molding compound improve, but the manufacturing process complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the surface topology parameters of the leadframe (adding protrusions and/or recesses) while keeping the base leadframe structure and material composition unchanged. This allows for improved adhesion through controlled geometric modifications that can be integrated into existing manufacturing processes without fundamentally changing the device architecture.
3Area of stationary object
If retaining features are formed by adding or removing material, then the surface area for molding compound adhesion increases, but the manufacturing steps and production time increase
Solution Approach 1:
The patent applies merging by combining the formation of retaining features with the existing leadframe manufacturing process. The retaining features are created as an integrated part of the leadframe fabrication (through stamping, embossing, or other forming techniques performed during or after leadframe production), rather than as a separate post-processing step. This merging of operations increases the effective adhesion surface area while minimizing additional manufacturing steps and maintaining production efficiency.
Data Source
AI summary
A semiconductor package that includes a leadframe having retaining features adapted to receive a molding compound is provided. As one example, an IC package includes a leadframe of a conductive material including a die attach pad and a lead finger separated from an edge of the die attach pad. The leadframe has a first surface and a second surface opposite the first surface. The IC package also includes retaining features on the lead finger at the second surface. The IC package further includes a die on the first surface at the die attach pad. The IC package yet further includes a molding compound that encapsulates the leadframe and the die and extends into and/or around the retaining features.