Bevelled Substrate Edge in Molded Semiconductor Packages

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Solution Overview

Problem

Molded semiconductor packages with vertically linear edges are prone to delamination, allowing humidity to penetrate and reducing package lifetime, while vertical step edges improve adherence but increase manufacturing costs.

Innovation Solution

A substrate with a bevelled edge, featuring a metal body and electrically insulative material, where the bevelled edge has sloped side faces extending between surfaces, enhancing adherence with the molding compound and providing improved thermal performance without additional cutting processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a vertically linear edge shape is used for the substrate, then the manufacturing process is simple, but the substrate separates from the molding compound allowing humidity penetration and reducing package lifetime

Engineering Contradiction:

Improvesubstrate edge fabricationVSAvoidpackage lifetime

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The substrate edge transitions from a symmetric vertically linear shape to an asymmetric bevelled shape with specific slope angles (e.g., 45 degrees), creating an asymmetric interface with the molding compound that enhances mechanical interlocking and prevents delamination while maintaining manufacturing simplicity

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The substrate edge is modified from a sharp vertical corner to a bevelled shape with gradual slopes, creating a curved transitional surface that improves stress distribution and adhesion to the molding compound, preventing humidity penetration pathways

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Reliability

If a vertical step shape is used for the substrate edge, then adherence between substrate and molding compound is improved, but the overall package cost increases due to additional cutting processes

Engineering Contradiction:

Improvesubstrate-molding compound adherenceVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The substrate edge geometry is modified by changing the angle parameters from vertical (90 degrees) to bevelled angles (e.g., 45 degrees), achieving improved adhesion through geometric parameter optimization rather than adding complex manufacturing steps

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Instead of adding a vertical step feature that requires additional cutting, the invention inverts the approach by removing material at an angle to create a bevelled edge, achieving the same adhesion improvement through a simplified single-pass manufacturing process

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS11848243B2Molded semiconductor package having a substrate with bevelled edge

Publication Date: 2023.12.19 INFINEON TECH AUSTRIA AG

AI summary

A molded semiconductor package includes: semiconductor dies attached to a first side of a leadframe and electrically interconnected to form a power electronic circuit; a substrate attached to a second side of the leadframe opposite the first side, and including a metal body and electrically insulative material that separates the metal body from the leadframe; and a molding compound encapsulating the dies. The metal body includes a first surface in contact with the electrically insulative material, a second surface opposite the first surface and which is not covered by the molding compound, and a bevelled edge extending between the first and second surfaces. The bevelled edge of the metal body has a first sloped side face that extends from the first surface to an apex of the bevelled edge, and a second sloped side face that extends from the apex to the second surface. Methods of producing the package are also described.