Power Semiconductor Device with External Connecting Member Projections
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Solution Overview
Problem
Conventional power semiconductor devices face reliability issues due to increased current density and size reduction, leading to deteriorated connection reliability between semiconductor elements and their wiring, particularly with Al wire bonding, which requires additional space and increases thermal stress.
Innovation Solution
A power semiconductor device configuration featuring an insulating substrate with conductor layers, semiconductor elements joined via anchoring layers, an external connecting member with projections for precise positioning, and a frame member with a fitting portion to stabilize the connection and reduce size, allowing for improved joint reliability without the need for jig tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Al wire bonding is used to connect upper surface electrodes, then current capacity and connection reliability are achieved, but wiring space is required and current density increases with size reduction
Solution Approach 1:
The patent extracts the wire bonding process and replaces it with direct bonding of external connecting members to the upper surface electrodes. This eliminates the need for Al wire bonding and the associated wiring space, while maintaining electrical connection functionality.
Solution Approach 2:
The patent introduces an external connecting member with an element coupler as an intermediary component that directly bonds to the upper surface electrodes. This mediator eliminates the need for wire bonding while providing stable electrical connection and reducing overall device volume.
2Productivity
If semiconductor element size is reduced, then cost is reduced through increased wafer yield, but current density per unit volume increases leading to deteriorated connection reliability
Solution Approach 1:
The patent changes the connection method from wire bonding to direct bonding with external connecting members. This parameter change in the connection approach allows for smaller element sizes with improved current density distribution, maintaining connection reliability while enabling higher wafer yield.
Solution Approach 2:
The external connecting members are designed with predetermined geometries and bonding surfaces that prepare the connection interface in advance. This preliminary design ensures reliable connection even when element sizes are reduced, allowing cost reduction through increased wafer yield without sacrificing reliability.
3Ease of manufacture
If anchoring layer thickness is not precisely controlled, then manufacturing is simpler, but thermal stress increases and crack growth occurs
Solution Approach 1:
The patent specifies precise thickness ranges for the anchoring layer (first anchoring layer and second anchoring layer) to optimize the balance between manufacturing ease and thermal stress resistance. This parameter control prevents crack growth while maintaining manufacturability.
Solution Approach 2:
The patent designs the anchoring layers with specific thickness parameters that beforehand cushion against thermal stress and prevent crack growth. This preventive design approach ensures joint reliability without significantly complicating the manufacturing process.
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 connections between semiconductor elements and external connecting members by precise determination of anchoring layer thickness, reducing thermal stress and preventing crack growth, thus improving the overall reliability and productivity of the power semiconductor device.
Implementation Method 1
The semiconductor element includes the lower surface electrode connected by soldering or the like
Implementation Method 2
reliability improvement through material improvement is reaching a limit. Recently considered is application of joining or the like by a CuSn compound, by Ag sintering, by Cu sintering
Data Source
AI summary
Provided is a power semiconductor device which is able to have improved connection reliability between a wiring line and an electrode of a power semiconductor element in comparison to conventional power semiconductor devices. This power semiconductor device is provided with: a semiconductor element; an insulating substrate having an electrode layer to which the semiconductor element is bonded; an external wiring line which is solder bonded to an upper surface electrode of the semiconductor element and has an end portion for external connection, said end portion being bent toward the upper surface; and a frame member which is affixed to the electrode layer of the insulating substrate. The frame member has a fitting portion that is fitted with the end portion for external connection; and the external wiring line has at least two projected portions that protrude toward the semiconductor element.