Wiring Substrate Interposed Insulating Layer Adhesion
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Solution Overview
Problem
Existing wiring substrates face issues with adhesion between the solder resist layer and metal posts, leading to potential peeling defects under external forces, particularly due to a small contact area between the solder resist layer and the conductor pads.
Innovation Solution
A wiring substrate design featuring a resin insulating layer, a conductor pad, a coating insulating layer that covers the conductor pad and metal post, and an interposed portion of the coating insulating layer between the metal post and conductor pad at their connection edge, which enhances adhesion and stress dispersion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the metal post is made to protrude from the solder resist layer to reduce diameter and prevent short circuits, then the risk of short circuits is reduced, but the contact area between the solder resist layer and conductor pad becomes small leading to poor adhesion
Solution Approach 1:
The patent divides the solder resist layer into multiple segments: a first solder resist layer covering the conductor pad, and a second solder resist layer covering the metal post. This segmentation allows each layer to serve specific functions - the first layer ensures adhesion at the conductor pad interface, while the second layer provides insulation and protection at the metal post, resolving the contradiction between maintaining small diameter and ensuring adhesion.
Solution Approach 2:
The patent introduces an intermediary structure - the first solder resist layer with its specific contact area with the conductor pad - that mediates between the metal post and the substrate. This intermediary ensures proper adhesion and stress distribution, preventing peeling while allowing the metal post to maintain a reduced diameter profile.
2Area of stationary object
If the contact area between solder resist layer and conductor pad is reduced to maintain compact structure, then device compactness is improved, but adhesion strength deteriorates leading to peeling defects
Solution Approach 1:
The solder resist system is segmented into two functional layers with different contact areas and roles. The first solder resist layer maintains adequate contact area with the conductor pad for strong adhesion, while the overall structure remains compact. This segmentation resolves the contradiction by assigning different area requirements to different functional layers.
Solution Approach 2:
The patent applies local quality by giving the first solder resist layer specific properties - adequate contact area with the conductor pad - precisely where adhesion is needed, while allowing other regions to be more compact. This localized optimization ensures strong adhesion at the critical interface without compromising overall device compactness.
3Object-affected harmful factors
If the solder resist layer completely covers the metal post for insulation, then insulation performance is improved, but adhesion to the conductor pad deteriorates due to small contact area
Solution Approach 1:
The patent segments the insulation function between two layers: the first solder resist layer provides adhesion and electrical connection at the conductor pad interface, while the second solder resist layer provides the insulation covering for the metal post. This segmentation resolves the contradiction by separating the adhesion function from the insulation function into different layers.
Solution Approach 2:
The first solder resist layer acts as an intermediary that maintains both electrical connection and mechanical adhesion at the conductor pad, while allowing the second layer to provide insulation. This intermediary structure enables the metal post to be covered for insulation while maintaining connection reliability through the first layer's adhesion.
Data Source
AI summary
A wiring substrate includes a resin insulating layer, a conductor pad formed on the resin insulating layer, a coating insulating layer formed on the resin insulating layer such that the coating insulating layer is covering the conductor pad, and a metal post connected to the conductor pad and protruding from the coating insulating layer such that a gap is formed between the metal post and the conductor pad at a peripheral edge of the metal post. The coating insulating layer is formed such that the coating insulating layer has an interposed portion formed in the gap between the metal post and the conductor pad at the peripheral edge of the metal post.