Vehicle Power Module Lead Frame Bonding with Protruding Pattern Layer
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Solution Overview
Problem
The existing bonding methods for lead frames to substrates in vehicle power modules, such as ultrasonic welding, often damage the insulating layer due to excessive force and vibration, leading to mechanical strength issues and increased costs with the use of high-strength silicon nitride ceramics.
Innovation Solution
A vehicle power module design where the lead frame is bonded to a substrate with a pattern layer that protrudes beyond the insulating layer, reducing the force applied to the insulating layer during ultrasonic welding, and incorporating a support member and molding member to reinforce bonding and prevent bending, using alumina ceramic for the insulating layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ultrasonic welding is used to bond the lead frame to the substrate, then bonding efficiency is improved, but the insulating layer is damaged due to excessive force and vibration
Solution Approach 1:
The pattern layer is designed to protrude beyond the insulating layer before the bonding process, creating a protective overhang that prevents the insulating layer from being damaged during ultrasonic welding. This preliminary structural arrangement ensures that the insulating layer is not exposed to excessive force and vibration during the bonding process.
2Strength
If silicon nitride ceramics are used to improve the mechanical strength of the insulating layer, then mechanical strength is improved, but manufacturing cost increases
Solution Approach 1:
The patent uses alumina ceramic, which is a more cost-effective material compared to silicon nitride ceramics. By designing the pattern layer to protrude and protect the insulating layer, the patent achieves adequate mechanical strength without requiring expensive materials, thus reducing manufacturing costs while maintaining functionality.
3Reliability
If the pattern layer protrudes beyond the insulating layer, then the insulating layer is protected from damage, but the structural complexity increases
Solution Approach 1:
The pattern layer serves dual functions: it provides electrical connection between the lead frame and the substrate, and it protrudes to protect the insulating layer during bonding. By merging these two functions into a single structural element, the patent reduces overall device complexity while achieving insulating layer protection.
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 design minimizes breakage of the insulating layer, reduces manufacturing costs, and enhances the durability of the power module by stabilizing the bonding process and preventing peeling between layers.
Implementation Method 1
ultrasonic welding (UW) has been attempted for bonding the pattern layer and the lead frame
Data Source
AI summary
A vehicle power module for converting power includes a lead frame configured to receive power from outside or to output power to the outside and a substrate configured to be bonded with the lead frame. The substrate includes a pattern layer disposed to be electrically connected to the lead frame, a conductive layer disposed apart from the pattern layer and configured to be electrically grounded, and an insulating layer disposed between the conductive layer and the pattern layer to insulate the pattern layer from the conductive layer. The pattern layer further protrudes toward the lead frame than the insulating layer.