Power Semiconductor Module Jointing for Heat Cycle and Overcurrent Cutoff
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Solution Overview
Problem
Solder joints in semiconductor modules hinder high-temperature operation and reduce lifespan due to heat cycles, and they fail to effectively cut off overcurrents when internal chips break, leading to larger scale failures.
Innovation Solution
A semiconductor module design using a combination of solder and ultrasonic jointing for leads, where the solder joint supports main current flow and separates upon overcurrent, while ultrasonic jointing reduces soldered connections, enabling high-temperature operation and preventing heat cycle degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solder joint is used for all terminal jointing, then ease of manufacture is improved, but high-temperature operation capability deteriorates and life with respect to heat cycle deteriorates
Solution Approach 1:
The patent segments the jointing method by applying different techniques to different leads: solder jointing for the first lead (main current path) and ultrasonic jointing for the second lead (signal/control path). This segmentation allows each lead to be jointed by the most appropriate method for its specific function, resolving the contradiction between ease of manufacture and high-temperature operation capability.
2Ease of manufacture
If solder joint is used for all terminal jointing, then ease of manufacture is improved, but life with respect to heat cycle deteriorates
Solution Approach 1:
The patent applies segmentation by using solder jointing only for the first lead that requires current-carrying capability, while using ultrasonic jointing for the second lead that is more sensitive to heat cycle degradation. This selective application preserves the ease of manufacture for current-carrying connections while improving the heat cycle life for signal connections.
3Ease of manufacture
If solder joint is used for all terminal jointing, then ease of manufacture is improved, but overcurrent cutting capability deteriorates
Solution Approach 1:
The patent segments the protection function by applying solder jointing to the first lead (main current path) which benefits from the overcurrent cutting capability of solder, while using ultrasonic jointing for the second lead (signal path) where overcurrent protection is less critical. This segmentation maintains ease of manufacture for power connections while ensuring reliability for signal connections.
Solution Approach 2:
The patent converts the harmful effect of solder melting under overcurrent conditions into a beneficial protective function. By applying solder jointing to the first lead in the main current path, the solder's melting point becomes a safety feature that automatically cuts off excessive current, protecting the semiconductor device from damage.
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
The design effectively cuts off overcurrents by separating leads from circuit patterns during high currents, allowing high-temperature operation and preventing module lifespan reduction due to heat cycles.
Implementation Method 1
a first lead solder jointed to the first circuit pattern
Implementation Method 2
a second lead ultrasonic jointed to the second circuit pattern
Implementation Method 3
the solder melts and the first lead is separated from the circuit pattern
Data Source
AI summary
An insulated substrate (2) includes first and second circuit patterns (5,4). A semiconductor device (7) includes first and second main electrodes (9,8) connected to the first and second circuit patterns (5,4) respectively and through which main currents flow. A first lead (12) is solder jointed to the first circuit pattern (5). A second lead (11) is ultrasonic jointed to the second circuit pattern (4).