Wiring Board Through-Hole Conductor Anchoring
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Solution Overview
Problem
The adhesion of through-hole conductors in wiring boards with glass fibers is weakened due to poor adhesion between the glass fibers and the conductors, leading to reliability issues caused by thermal expansion differences, resulting in strain and loss of conduction reliability.
Innovation Solution
A through-hole conductor is designed with a first portion on the inner wall and second portions inside the glass fibers, which are shorter in length along specific directions, providing an anchoring effect to enhance adhesion and distribute stress uniformly, thereby improving conduction reliability without affecting insulating reliability between adjacent conductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If glass fibers are included in the core board to improve strength, then the mechanical strength of the core board is improved, but the adhesion of the through-hole conductor decreases
Solution Approach 1:
The patent applies local quality by creating a specific plating structure where the second portions of the through-hole conductor have different lengths in different directions. The conductor has shorter lengths in first and second directions (along glass fiber orientations) and longer lengths in other directions, creating directionally-dependent adhesion properties that accommodate thermal expansion while maintaining strong overall bonding
Solution Approach 2:
The patent changes the geometric parameters of the through-hole conductor by controlling the lengths of its second portions in different directions. By making the conductor portions shorter along the glass fiber directions (first and second directions) and longer in other directions, the design optimizes the balance between adhesion strength and thermal expansion accommodation
2Strength
If glass fibers are used as reinforcing members, then the strength of the core board is improved, but stress concentration and slippage occur due to different coefficients of thermal expansion, resulting in loss of conduction reliability
Solution Approach 1:
The patent creates directionally-dependent conductor geometry where the second portions have shorter lengths specifically in the first and second directions (along glass fiber orientations) and longer lengths in other directions. This local variation in conductor dimensions provides stress distribution that accommodates thermal expansion differences between glass fibers, insulating resin, and conductor materials
Solution Approach 2:
The patent designs the through-hole conductor with preemptive stress accommodation features. The varied lengths of the second portions are configured beforehand to cushion against thermal expansion stress that will occur during temperature changes, preventing slippage and maintaining conduction reliability before thermal stress problems can arise
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
The solution ensures stronger adhesion of the through-hole conductor to the glass fibers, enhancing conduction reliability while maintaining the integrity of the insulating reliability between adjacent conductors, even under stress conditions.
Implementation Method 1
second portions connected to the first portion and located inside the glass fibers. The second portions include portions in a first direction and a second direction intersecting the first direction in a planar direction of the core board, the portions having a shorter length in the planar direction from the inner wall of the through-hole than portions, of the second portions, in directions other than the first direction and the second direction
Data Source
AI summary
A wiring board according to the present disclosure includes a core board including an upper surface, a lower surface, a through-hole penetrating from the upper surface to the lower surface, and a plurality of glass fibers located inside, and a through-hole conductor located in the through-hole. The through-hole conductor includes a first portion located on an inner wall of the through-hole, and second portions connected to the first portion and located inside the glass fibers. The second portions include portions in a first direction and a second direction intersecting the first direction in a planar direction of the core board, the portions having a shorter length in the planar direction from the inner wall of the through-hole than portions, of the second portions, in directions other than the first direction and the second direction.