Lead Frame Deformable Section for Resin-Safe Terminal Fixing
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Solution Overview
Problem
Conventional semiconductor devices experience reliability issues due to stress-induced fractures and separations at the interface between the external connection terminal portion and the sealing resin, caused by elastic deformation during fixation, which compromises the integrity of the sealing resin and lead frame.
Innovation Solution
The semiconductor device incorporates a deformable portion at the boundary between the inner and external connection terminal portions of the lead frame, designed to concentrate stress and facilitate bending, thereby preventing excessive stress from being applied to the sealing resin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the external connection terminal portion is fixed to the terminal block by a screw, then the connection is secured, but the external connection terminal portion undergoes elastic deformation which applies stress to the sealing resin, causing fractures and separations
Solution Approach 1:
The lead frame is divided into three distinct portions: an inner portion embedded in the sealing resin, an external connection terminal portion protruding from the sealing resin, and a deformable portion at the boundary between them. This segmentation allows the deformable portion to absorb fixation stress through controlled bending, preventing stress transmission to the sealing resin and eliminating fractures and separations while maintaining secure electrical connections.
2Ease of operation
If the hole of the external connection terminal portion overlaps with the terminal block, then fixation is enabled, but a gap between the external connection terminal portion and terminal block causes elastic deformation and stress concentration
Solution Approach 1:
The deformable portion acts as an intermediary element between the inner portion (embedded in sealing resin) and the external connection terminal portion (protruding from sealing resin). This intermediary absorbs the mismatch and gap between the external connection terminal portion and terminal block during fixation, converting harmful stress into controlled bending of the deformable portion itself, thereby protecting the sealing resin from stress concentration and fractures.
3Stability of the object's composition
If the lead frame is made rigid to maintain structural stability, then positioning is improved, but stress cannot be absorbed, leading to sealing resin damage
Solution Approach 1:
Different portions of the lead frame are assigned different mechanical properties: the inner portion and external connection terminal portion maintain sufficient rigidity for stable positioning and electrical connection, while the deformable portion at the boundary is designed with controlled flexibility. This local differentiation allows the rigid portions to provide structural stability and positioning accuracy, while the deformable portion locally absorbs fixation stress through bending, preventing stress-induced damage to the sealing resin.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the reliability of the semiconductor device by suppressing resin fractures and separations, maintaining the integrity of the sealing resin and lead frame, while allowing for a smaller device size without increasing dimensions.
Implementation Method 1
The deformable portion is configured such that stress concentrates thereon in order to cause the lead frame to bend
Data Source
AI summary
A semiconductor device having high reliability and a power conversion device are obtained. A semiconductor device includes: a semiconductor element; a lead frame; and a sealing resin. The semiconductor element is mounted on the lead frame. The sealing resin seals the semiconductor element and a part of the lead frame. The lead frame includes an inner portion and an external connection terminal portion. The inner portion is in contact with the sealing resin. The external connection terminal portion protrudes outward from a surface of the sealing resin. The lead frame includes a deformable portion. The deformable portion is located at a boundary portion between the inner portion and the external connection terminal portion. The deformable portion is configured such that stress concentrates thereon in order to cause the lead frame to bend. The deformable portion and the surface of the sealing resin intersect with each other.