Lead Frame Thin-Weld Structure for Heat Sink Bonding
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Solution Overview
Problem
The bonding of a heat sink to a frame member in semiconductor devices can cause deformation or damage due to thermal effects from laser welding, especially when the frame member is thin and the heat sink is thicker, leading to reduced quality of the lead frame and semiconductor device.
Innovation Solution
A lead frame design with support portions featuring thin thickness portions that are welded to a heat sink, using laser welding on these thinner areas to minimize thermal deformation and damage, while ensuring strong bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If laser welding is applied to bond the heat sink to the frame member, then bonding strength is improved, but thermal deformation and damage occur due to heat transmission
Solution Approach 1:
The support portion is designed with non-uniform thickness, featuring a first thickness in the overlapping region and a second (smaller) thickness in the welding region. This local variation in thickness allows the laser heat to be concentrated and rapidly conducted away in the thinner welding region, preventing thermal deformation while maintaining bonding strength.
Solution Approach 2:
The thickness parameter of the support portion is changed spatially to optimize welding performance. By reducing the thickness in the welding region compared to the overlapping region, the thermal mass is reduced, enabling faster heat dissipation and shorter laser application time, thus preventing thermal damage while achieving adequate bonding.
2Manufacturing precision
If laser application time is reduced to prevent thermal deformation, then manufacturing precision is improved, but bonding quality deteriorates
Solution Approach 1:
The support portion is designed with non-uniform thickness, featuring a first thickness in the overlapping region and a second (smaller) thickness in the welding region. This local variation in thickness allows the laser heat to be concentrated and rapidly conducted away in the thinner welding region, preventing thermal deformation while maintaining bonding strength.
Solution Approach 2:
The thickness parameter of the support portion is changed spatially to optimize welding performance. By reducing the thickness in the welding region compared to the overlapping region, the thermal mass is reduced, enabling faster heat dissipation and shorter laser application time, thus preventing thermal damage while achieving adequate bonding.
3Manufacturing precision
If the frame member is made thin to reduce heat absorption, then thermal deformation is reduced, but structural strength decreases
Solution Approach 1:
The support portion is designed with non-uniform thickness, featuring a first thickness in the overlapping region and a second (smaller) thickness in the welding region. This local variation in thickness allows the laser heat to be concentrated and rapidly conducted away in the thinner welding region, preventing thermal deformation while maintaining bonding strength.
Solution Approach 2:
The support portion is segmented into different thickness regions: a first thickness region for structural support and overlap functionality, and a second (thinner) thickness region for welding. This segmentation allows each region to perform its specific function optimally without compromising the overall structure.
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
Prevents unnecessary deformation and damage during welding, maintaining the integrity of the lead frame and semiconductor device by rapidly melting the thin thickness portions, thereby improving bonding performance and reducing laser application time.
Implementation Method 1
laser welding may be used, but due to long time application of laser to the frame member and the heat sink to be bonded together, heat may be transmitted even to the vicinity of a bonded portion
Implementation Method 2
the thin thickness portions... rapidly melting the thin thickness portions
Implementation Method 3
it rapidly melts the thin thickness portions such that the frame member and the heat sink are welded together
Implementation Method 4
a heat sink that has a larger plate thickness than a frame member that is formed of a thin plate made of metal may be bonded in the center of the frame member... to efficiently dissipate heat that is generated by the semiconductor element
Data Source
AI summary
A lead frame includes a support portion that has one end on which a first part and a second part that has a smaller thickness than the first part are arranged, a lead, and a heat sink that is welded to the support portion in the second part. A method of manufacturing the lead frame includes forming, from a metal plate, a frame member that includes a support portion and a lead, where the support portion has one end on which a first part and a second part that has a smaller thickness than the first part are arranged, and welding a heat sink to the support portion in the second part.