Embedded Electrode Pad Neck Design for Circuit Board Peeling
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Solution Overview
Problem
The existing circuit boards face issues with the insufficient thickness of insulating resin leading to reduced contact area and fixing strength of electrode pads, which can cause peeling off during connection with another circuit board.
Innovation Solution
The circuit board design includes an electrode pad with a neck formed on its outer surface, where the neck is in contact with the insulating resin, and features a first conductor layer with exposed end surfaces and a second conductor layer having different grain boundary densities, ensuring secure contact even with insufficient insulating resin thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the insulating layer includes a reinforcing member to improve board strength, then the board strength is improved, but the thickness of insulating resin adjacent to the reinforcing member is reduced, causing reduced contact area and fixing strength of the electrode pad
Solution Approach 1:
The electrode pad is designed with a neck portion at its peripheral edge that extends toward the insulating resin. This local structural modification creates a specific region (the neck) that enhances contact with the insulating resin, compensating for the reduced resin thickness caused by the reinforcing member. The neck portion is specifically positioned to maximize contact area with the available insulating resin, thereby maintaining fixing strength despite the overall thickness reduction in that region.
2Adaptability or versatility
If the thickness of insulating resin is reduced to accommodate reinforcing member, then the board can be manufactured with reinforcing structure, but the contact area between insulating resin and electrode pad is reduced, causing peeling off
Solution Approach 1:
Instead of relying solely on the vertical thickness dimension of the insulating resin, the electrode pad design extends into the horizontal dimension by creating a neck portion that protrudes toward the insulating resin. This dimensional transition allows the electrode pad to establish contact with the insulating resin through a lateral extension rather than solely through vertical thickness, thereby maintaining contact area even when the resin thickness is reduced by the reinforcing member.
Data Source
AI summary
A circuit board includes: an insulating layer having at least a part formed of an insulating resin; and an electrode pad embedded in the insulating layer and having a neck formed on an outer side surface, the neck being held in contact with the insulating resin of the insulating layer. The electrode pad includes: a first conductor layer having an end surface exposed from one surface of the insulating layer; and a second conductor layer formed on the first conductor layer and having a grain boundary density different from a grain boundary density of the first conductor layer. The neck is formed in a region of the outer side surface, the region corresponding to a boundary part between the first conductor layer and the second conductor layer.