Semiconductor Module Wire Bonding Joint Stress Reduction
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Solution Overview
Problem
In semiconductor devices, stress concentration at wire bonding joints can lead to crack formation, reducing the service life of the device due to inadequate sealing resin filling and thermal stress.
Innovation Solution
A semiconductor module design with a control circuit board between semiconductor elements, using a second wiring member with a convex curve shape that starts on a control electrode and ends on the circuit board, ensuring a larger bending angle at the joint to prevent voids and enhance resin filling, thereby reducing stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If stitch bonding is performed continuously from one semiconductor element through the circuit pattern to another semiconductor element, then productivity is improved by reducing bonding steps, but stress concentrates on the joint portions causing cracks to develop
Solution Approach 1:
The continuous wire is segmented by cutting it at the circuit pattern portion, dividing the bonding path into separate segments. This prevents stress concentration at joint portions while maintaining bonding efficiency, as each segment can be independently bonded without creating continuous stress paths through the circuit pattern.
Solution Approach 2:
The wire is extracted or removed from the circuit pattern portion by cutting it, eliminating the problematic joint portion where stress concentrates. This extraction prevents crack initiation at the circuit pattern interface while preserving the essential bonding function between semiconductor elements.
2Device complexity
If the wire bonding joint portion is located on the circuit pattern, then device complexity is reduced by simplifying the bonding path, but manufacturing precision deteriorates due to inadequate sealing resin filling
Solution Approach 1:
The semiconductor element surface serves as an intermediary bonding location, replacing the circuit pattern as the bonding substrate. This intermediary position provides better resin filling characteristics and thermal stress distribution, eliminating the manufacturing precision issues associated with bonding directly on circuit patterns while maintaining path simplicity.
3Ease of operation
If wire bonding is performed on the circuit pattern, then ease of operation is improved by allowing flexible wire routing, but thermal stress concentration increases leading to reduced service life
Solution Approach 1:
The bonding location is changed to the semiconductor element surface, which has different local quality characteristics compared to the circuit pattern. The semiconductor element surface provides better thermal stress distribution and heat dissipation properties, reducing thermal stress concentration while allowing flexible wire routing through the modified bonding path.
Data Source
AI summary
A semiconductor module includes at least two semiconductor elements connected in parallel; a control circuit board placed between the at least two semiconductor elements; a control terminal for external connection; a first wiring member that connects the control terminal and the control circuit board; and a second wiring member that connects a control electrode of one of the at least two semiconductor elements and the control circuit board, wherein the second wiring member is wire-bonded from the control electrode towards the control circuit board, and has a first end on the control electrode and a second end on the control circuit board, the first end having a cut end face facing upward normal to a surface of the control electrode and the second end having a cut end face facing sideways parallel to a surface of the control circuit board.