Multilayer PCB Through-Hole Conductor Stress Dispersion
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Solution Overview
Problem
Existing methods for manufacturing printed wiring boards with through-hole conductors often concentrate stress at the minimum diameter of the conductor, leading to potential cracking and peeling issues due to uneven tapering of penetrating holes.
Innovation Solution
A method involving the formation of a core substrate with a first opening portion tapering from the first surface toward the second, a second opening portion tapering from the second surface toward the first, and a third opening portion connecting them, ensuring a substantially constant diameter at the juncture to disperse stress and enhance connection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two tapered opening portions are directly connected to form a penetrating hole, then the through-hole conductor can connect the upper and lower surfaces of the core substrate, but stress concentrates at the minimum diameter location causing potential cracking and peeling
Solution Approach 1:
The penetrating hole is divided into three distinct opening portions: a first tapered opening portion from the first surface, a second tapered opening portion from the second surface, and a third substantially constant-diameter opening portion connecting them. This segmentation prevents stress concentration by avoiding direct connection of the two tapered portions, thereby resolving the contradiction between connection reliability and stress resistance
Solution Approach 2:
Different sections of the penetrating hole are given different geometric qualities: the first and second opening portions have tapered shapes for proper conductor formation, while the third opening portion has a substantially constant diameter to serve as a stress-relief zone. This local differentiation of geometric properties allows the structure to simultaneously achieve good conductor connection and stress distribution
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 approach effectively disperses stress across multiple boundaries, reducing the likelihood of cracking and peeling, thereby enhancing the reliability of the through-hole conductor connections in printed wiring boards.
Implementation Method 1
forming on a first-surface side of the core substrate a first opening portion tapering from the first surface toward the second surface, forming on a second-surface side of the core substrate a second opening portion tapering from the second surface toward the first surface
Data Source
AI summary
A method for manufacturing a printed wiring board includes preparing a core substrate having a first surface and a second surface on the opposite side of the first surface, forming on the first-surface side of the substrate a first opening portion tapering from the first toward second surface, forming on the second-surface side of the substrate a second opening portion tapering from the second toward first surface, forming a third opening portion such that a penetrating hole formed of the first opening portion, the second opening portion and the third opening portion connecting the first and second opening portions is formed in the substrate, forming a first conductor on the first surface of the substrate, forming a second conductor on the second surface of the substrate, and filling a conductive material in the penetrating hole such that a through-hole conductor connecting the first and second conductors is formed.