Wiring Substrate Heat Sink Flatness via Brazing Frame
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Solution Overview
Problem
The existing bonding process for heat dissipation members in wiring substrates often results in a deterioration of the flatness of the component mounting surface, affecting the connection reliability and heat dissipation properties.
Innovation Solution
A wiring substrate design featuring a frame-shaped metal portion with a projecting portion that overlaps the heat dissipation member, creating a space for the brazing material and supporting the heat dissipation member, thereby reducing the material's flow to the component mounting surface and enhancing flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heat dissipation member is bonded to the peripheral edge portion of the through hole by a bonding material, then the heat dissipation member is secured in position, but the flatness of the component mounting surface deteriorates due to bonding material overflow
Solution Approach 1:
The bonding structure is segmented into two distinct zones: an inner peripheral region where bonding material is permitted to overflow for secure bonding, and an outer peripheral region where the component mounting surface remains flat and free of bonding material. This segmentation resolves the contradiction by allowing bonding material to be contained within a specific zone without affecting the overall surface flatness required for component mounting.
Solution Approach 2:
Different surface quality requirements are applied to different regions of the component mounting surface. The inner peripheral portion adjacent to the through hole allows bonding material presence for secure bonding, while the outer peripheral portion maintains high flatness for component mounting. This local differentiation resolves the contradiction by permitting bonding material overflow only where it does not interfere with component mounting.
2Strength
If the heat dissipation member is bonded using a bonding material, then the bonding strength is sufficient, but the component mounting surface becomes uneven affecting heat dissipation properties
Solution Approach 1:
The bonding structure is segmented into two distinct zones: an inner peripheral region where bonding material is permitted to overflow for secure bonding, and an outer peripheral region where the component mounting surface remains flat and free of bonding material. This segmentation resolves the contradiction by allowing bonding material to be contained within a specific zone without affecting the overall surface flatness required for component mounting.
Solution Approach 2:
Different surface quality requirements are applied to different regions of the component mounting surface. The inner peripheral portion adjacent to the through hole allows bonding material presence for secure bonding, while the outer peripheral portion maintains high flatness for component mounting. This local differentiation resolves the contradiction by permitting bonding material overflow only where it does not interfere with component mounting.
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 improves the flatness of the component mounting surface, enhances connection reliability, and maintains effective heat dissipation by minimizing the brazing material's presence on the mounting surface.
Implementation Method 1
bonded to the frame-shaped metal portion by a brazing material
Data Source
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AI summary
An object of the present disclosure is to improve connection reliability between a wiring substrate and an electronic component by improving the flatness of a component mounting surface of a heat dissipation member. A wiring substrate includes a wiring conductor extending from a first surface to a second surface of an insulating substrate, a frame-shaped metal layer located on a bottom surface of a recessed portion of the insulating substrate and surrounding a through hole, and a heat dissipation member located in the recessed portion of the insulating substrate so as to close the through hole, bonded to the frame-shaped metal layer by a brazing material, and having a component mounting surface on the through hole side. The frame-shaped metal layer has a projecting portion protruding toward the heat dissipation member, and the projecting portion is located so as to overlap the heat dissipation member in a transparent plan view.