Lead Frame Groove Design for Semiconductor Adhesion
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Solution Overview
Problem
Existing semiconductor devices face challenges in achieving high reliability and reduced size while maintaining high performance, especially in severe environments, due to limitations in lead frame design and material properties.
Innovation Solution
A lead frame with a clad material structure and a unique groove design that allows for direct bonding to semiconductor elements, featuring a stacked-layer structure with different metal layers and a resin member to enhance adhesion and reduce stress, enabling efficient heat dissipation and self-alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lead frame uses a clad material with stacked-layer structure, then electrical conductivity and hardness are improved, but manufacturing complexity increases
Solution Approach 1:
The lead frame employs a clad material consisting of a copper base layer and an iron alloy plating layer. The copper layer provides high electrical conductivity, while the iron alloy layer enhances hardness and adhesion to the semiconductor element. This composite structure resolves the contradiction by combining materials with complementary properties to simultaneously improve conductivity and mechanical strength.
Solution Approach 2:
The lead frame is divided into functionally distinct layers: a copper base layer for electrical conductivity and an iron alloy plating layer for hardness and adhesion. This segmentation allows each layer to optimize its specific function, resolving the contradiction between conductivity and hardness requirements.
2Volume of moving object
If the lead frame is downsized, then device size is reduced, but adhesion between lead and semiconductor element becomes insufficient
Solution Approach 1:
The element mounting region features a surface roughness of 0.3 µm to 3 µm, creating localized adhesion enhancement zones. This local quality change provides sufficient adhesion strength even when the overall lead frame size is reduced, resolving the contradiction between downsizing and maintaining adhesion.
Solution Approach 2:
The surface roughness parameter of the element mounting region is specifically controlled within 0.3 µm to 3 µm to optimize adhesion. This parameter change enables strong bonding in compact designs, resolving the contradiction between reduced size and sufficient adhesion.
3Ease of manufacture
If the lead frame structure is simplified, then manufacturing ease is improved, but heat dissipation performance deteriorates
Solution Approach 1:
The copper base layer with high thermal conductivity is combined with the iron alloy plating layer, creating a composite structure that maintains excellent heat dissipation performance while enabling straightforward manufacturing through conventional plating processes.
Data Source
AI summary
A lead frame of high quality which can endure direct bonding to a semiconductor element, and a semiconductor device of high reliability which utilizing the lead frame. A lead frame includes a plurality of connected units, each unit including a pair of lead portions arranged spaced apart and opposite from each other, for mounting a semiconductor element and electrically connecting to a pair of electrodes of the semiconductor element respectively. The lead portions respectively include an element mounting region arranged on a surface thereof to mount the semiconductor element, and a groove extending from opposing end surfaces of each of the pair of lead portions, in a direction away from the end surfaces and bending in a surrounding manner along outer periphery of the element mounting region.