Curved Insulating Substrate for Power Module Wire Bonding
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Solution Overview
Problem
The existing configuration of power modules for electric vehicles, where a curved and inclined insulating substrate is bonded to a base plate, results in varying contact angles for wire bonding, leading to unreliable connections and potential damage to semiconductor elements due to the need for frequent adjustments of the wire tool.
Innovation Solution
A semiconductor device with an insulating substrate having a curved main surface convex towards a heat dissipation member, where the first solder is thicker at the edges than at the center, and a semiconductor element bonded to an electrode plate using second solder, ensuring stable connections without the need for frequent adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the insulating substrate is curved and inclined to prevent air entrapment in heat dissipation grease, then heat dissipation efficiency is improved, but wire bonding reliability deteriorates due to varying contact angles
Solution Approach 1:
The insulating substrate is designed with a curved main surface that is convex toward the heat dissipation member. This curvature enables the substrate to conform to the spherical or curved geometry of the heat dissipation grease portion, ensuring complete contact and eliminating air gaps. The curvature is specifically designed to match the spherical shape of the heat dissipation grease, allowing the grease to be uniformly distributed and fully contact the semiconductor element without entrapment of air pockets.
Solution Approach 2:
The insulating substrate exhibits different orientations at different locations to optimize local functions. The center portion of the substrate has a different inclination angle compared to the edge portions, allowing the center to optimize heat dissipation contact while the edges accommodate wire bonding operations. This local variation in surface orientation enables simultaneous optimization of both heat dissipation efficiency and wire bonding reliability across different regions of the substrate.
2Reliability
If the wire tool contact is adjusted for each semiconductor element to ensure connection reliability, then wire bonding quality is improved, but manufacturing complexity and time increase
Solution Approach 1:
The insulating substrate is designed with differentiated surface orientations for different functional regions. The edge portions of the substrate are inclined at angles optimized for wire bonding accessibility, while the center portion maintains an orientation optimized for heat dissipation. This local quality differentiation allows the wire tool to maintain consistent contact angles during wire bonding operations across multiple semiconductor elements, eliminating the need for repeated adjustments and thereby improving manufacturing efficiency while maintaining wire bonding quality.
3Ease of manufacture
If the insulating substrate is made flat to simplify wire bonding, then manufacturing ease is improved, but heat dissipation efficiency deteriorates due to air entrapment
Solution Approach 1:
The insulating substrate is designed with a curved main surface that is convex toward the heat dissipation member, specifically matching the spherical geometry of the heat dissipation grease portion. This curvature enables the substrate to conform to the grease distribution pattern, ensuring complete contact and eliminating air gaps that would otherwise impede heat dissipation. The curved design maintains ease of manufacture by using standard curving techniques while dramatically improving thermal contact.
Solution Approach 2:
The insulating substrate exhibits spatially varying surface orientations where the center portion is inclined to optimize heat dissipation contact with the spherical grease, while the edge portions are oriented to facilitate wire bonding operations. This local differentiation of surface quality allows simultaneous optimization of both heat dissipation efficiency and manufacturing ease, with each region of the substrate tailored to its specific functional requirement.
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 configuration enhances the reliability of the semiconductor device by reducing thermal stress and preventing damage during wire bonding, while maintaining high efficiency in heat dissipation and long-term reliability.
Implementation Method 1
The insulating substrate is bonded to the heat dissipation member to cause a main surface of the insulating substrate to curve so as to have a shape convex toward the heat dissipation member
Implementation Method 2
The first solder is thicker at the edges than at the center in a plan view
Implementation Method 3
The semiconductor element is bonded to the electrode plate by second solder
Data Source
AI summary
A power module includes an insulating substrate, a heat dissipation member, and an electrode plate. An IGBT and a diode are mounted on the insulating substrate. The heat dissipation member is bonded to the insulating substrate by first solder. The electrode plate is disposed so as to overlap at least a part of the semiconductor element. The main surface of the insulating substrate is curved so as to have a shape convex toward the heat dissipation member. The first solder is thicker at the edges than at the center in a plan view. The semiconductor element is bonded to the electrode plate by second solder.