Semiconductor Terminal Plating Sequence to Prevent Film Cracking
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Solution Overview
Problem
Conventional semiconductor module manufacturing methods often result in cracks in the plated film of terminals due to folding, leading to oxidation and impaired appearance, which necessitates prevention of such cracks.
Innovation Solution
A semiconductor module design featuring a resin case with a through hole opposite the terminal, where a supporting resin portion supports the fastening nut without resin between the nut and terminal, and ultrasonic welding of the supporting portion to the resin case, eliminating the need for terminal folding and subsequent plating after bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the terminal is folded so as to overlap the fastening portion inside the resin case, then the terminal can be positioned correctly, but a crack of the plated film is easily generated in the bent portion
Solution Approach 1:
The patent applies preliminary action by forming the plated film on the terminal before the folding process. The terminal is plated while in its unfolded state, ensuring the plated film is formed on a flat surface without stress. Only after plating is the terminal folded into its final position, preventing cracks in the plated film that would occur if folding were done first.
2Ease of manufacture
If the terminal is plated after folding, then the manufacturing process can be simplified, but the plated film develops cracks leading to oxidation and impaired appearance
Solution Approach 1:
The patent reverses the conventional sequence by performing plating before folding rather than after. This preliminary plating ensures the metal film is formed on the terminal in its stress-free, unfolded state, preventing subsequent cracking and oxidation that would compromise appearance quality.
3Strength
If a supporting portion is added inside the through hole to support the fastening portion, then bonding strength and airtightness are enhanced, but the device complexity increases
Solution Approach 1:
The patent merges the supporting portion with the resin case by forming them as a single integrated component during the same molding process. The supporting portion is created as an internal feature of the resin case itself, eliminating the need for separate parts and assembly steps, thus enhancing bonding strength and airtightness without significantly increasing device complexity.
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 approach prevents cracks in the metal film of the terminal, maintaining its appearance by avoiding oxidation and enhancing bonding strength and airtightness, thus improving the module's reliability and appearance.
Implementation Method 1
A plated film is formed as a metal film on a surface of the terminal
Implementation Method 2
ultrasonic welding of the supporting portion to the resin case
Data Source
AI summary
A semiconductor module in which no crack of a metal film exists in a terminal is provided. A semiconductor module is provided, including: a semiconductor element; a terminal with a metal film formed on a surface and including a bent portion; a resin case to which the terminal is fixed and in which a through hole is formed opposite to the terminal, the resin case housing a semiconductor element; a fastening portion provided inside the through hole; and a supporting portion provided inside the through hole and supporting the fastening portion.