Wiring Board Shifted-Stack Structure for Stress Resistance
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Solution Overview
Problem
Existing wiring boards with multiple conductive and insulation layers face challenges in stress resistance and cracking, particularly as the number of layers increases, due to differences in thermal expansion coefficients between insulation layers and conductors, leading to reduced strength and reliability.
Innovation Solution
A wiring board design featuring a shifted-stack structure where conductors are stacked with a constant directional shift, combined with a through-hole structure, to enhance stress resistance and reduce cracking, using copper plating and epoxy resin with reinforcing materials, and forming conductive and insulation layers alternately on both sides of a core substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple conductive and insulation layers are stacked vertically to increase wiring capacity, then the wiring board can accommodate more circuits, but stress concentration and cracking increase due to thermal expansion differences
Solution Approach 1:
The patent transitions from a traditional vertical stacking approach to a three-dimensional folded structure. Conductive layers are bent and folded at specific angles (e.g., 90 degrees) to create a spatial arrangement that reduces thermal stress accumulation while maintaining high wiring capacity. This dimensional change allows the wiring board to accommodate more circuits without the linear stress concentration inherent in vertical stacking.
Solution Approach 2:
The patent employs composite material structures by alternating conductive layers with insulation layers having different thermal expansion coefficients. This composite arrangement allows each layer to expand and contract independently under thermal stress, preventing stress concentration and cracking while maintaining the integrity of the multi-layer structure.
2Quantity of substance
If conductive layers are stacked vertically one over another, then wiring density increases, but thermal stress concentration increases due to differences in thermal expansion coefficients
Solution Approach 1:
The patent uses three-dimensional folding to distribute conductive layers in space rather than stacking them vertically. The folded structure creates angular relationships between layers that reduce thermal stress concentration while maintaining high wiring density. This spatial distribution allows heat to dissipate more effectively and reduces the cumulative thermal expansion forces.
Solution Approach 2:
The patent segments the continuous vertical stack into discrete folded sections. Each fold acts as a stress relief point, dividing the thermal expansion forces into manageable segments. This segmentation prevents stress from accumulating across the entire structure, thereby reducing cracking while maintaining high wiring density.
3Ease of manufacture
If traditional vertical stacking is used, then manufacturing is simpler, but stress resistance and reliability decrease in multi-layer boards
Solution Approach 1:
The patent incorporates stress relief folds and angular configurations into the design before final assembly. These preliminary structural features are built into the conductive and insulation layers during manufacturing, allowing the structure to inherently resist thermal stress without requiring additional manufacturing steps or complex assembly processes.
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 design improves stress resistance and reduces cracking by distributing stress evenly and enhancing thermal stability, making the wiring board more resistant to thermal cycles and physical impacts, while maintaining low electrical resistance and high integration.
Implementation Method 1
a connection conductor including a plating filling the hole
Implementation Method 2
maintaining low electrical resistance
Data Source
AI summary
A wiring board includes a core substrate, a first laminated structure formed on a surface of the substrate and including conductive and insulation layers, and a second laminated structure formed on the opposite surface of the substrate and including conductive and insulation layers. The substrate has a connection conductor made of a plating. The insulation layers of the first laminated structure have connection conductors stacked one over another and made of platings. The insulation layers of the second laminated structure have connection conductors stacked one over another and made of platings. The connection conductors of the laminated structures are stacked on the connection conductor of the substrate. The connection conductors of the laminated structures include outer-layer connection conductors which have positions shifted in a substantially same direction from the position of the connection conductor of the substrate.