Printed Wiring Board Circuit Cross-Section Shapes
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Solution Overview
Problem
Existing printed wiring boards face challenges in filling narrow spaces between conductor circuits with resin insulating layers due to the difficulty in achieving adequate adhesion and preventing peeling off during heat cycles, especially when conductor circuit widths are small and side walls have rough surfaces.
Innovation Solution
A printed wiring board design featuring a first resin insulating layer, a conductor layer with specific circuit configurations and spacings, and a second resin insulating layer that fills spaces between conductor circuits, utilizing a combination of rectangular and trapezoidal cross-sectional shapes to enhance adhesion and reduce peeling, with controlled surface roughness to facilitate resin filling and withstand thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the conductor circuit width is reduced to increase circuit density, then the number of circuits per unit area increases, but the resin insulating layer cannot adequately fill the narrow spaces between conductor circuits
Solution Approach 1:
The patent applies different cross-sectional shapes to different conductor circuits based on their local spacing conditions. Conductor circuits with narrow spacing (≤15μm) use rectangular cross-sections, while those with wider spacing (>15μm) use trapezoidal cross-sections. This local differentiation allows the resin insulating layer to be properly filled in narrow spaces while maintaining adequate adhesion and preventing peeling during heat cycles.
2Productivity
If the space between conductor circuits is narrowed to increase circuit density, then more circuits fit in the same area, but adhesion between the resin insulating layer and conductor circuits deteriorates
Solution Approach 1:
The patent implements local quality by assigning different cross-sectional shapes to conductor circuits based on their specific spacing conditions. For narrow spaces (≤15μm), rectangular cross-sections provide stable adhesion. For wider spaces (>15μm), trapezoidal cross-sections with inclined side walls enhance resin filling and adhesion. This localized adaptation maintains reliable adhesion across varying circuit densities.
3Productivity
If the conductor circuit width is reduced to increase circuit density, then the number of circuits per unit area increases, but transmission loss increases
Solution Approach 1:
The patent applies different cross-sectional shapes to different conductor circuits based on their local spacing conditions. Conductor circuits with narrow spacing (≤15μm) use rectangular cross-sectional shapes, while those with wider spacing (>15μm) use trapezoidal cross-sectional shapes. This local differentiation allows the resin insulating layer to be properly filled in narrow spaces, reducing transmission loss while maintaining high circuit density.
4Productivity
If the space between conductor circuits is narrowed to increase circuit density, then more circuits fit in the same area, but insulation resistance decreases
Solution Approach 1:
The patent implements local quality by assigning different cross-sectional shapes to conductor circuits based on their specific spacing conditions. For narrow spaces (≤15μm), rectangular cross-sections ensure proper resin filling and adequate insulation. For wider spaces (>15μm), trapezoidal cross-sections with inclined side walls provide sufficient insulation while maintaining circuit density.
Data Source
AI summary
A printed wiring board includes a first resin insulating layer, a conductor layer on the first resin insulating layer, and a second resin insulating layer formed on the first resin insulating layer such that the second resin insulating layer is covering the conductor layer. The conductor layer includes a first circuit having a width of 15 μm or less and a rectangular cross-sectional shape, a second circuit having a trapezoidal cross-sectional shape, a third circuit, a fourth circuit, a fifth circuit, and a sixth circuit, a space between the first and third circuits has a width of 14 μm or less, a space between the first and fourth circuits has a width of 14 μm or less, a space between the second and fifth circuits has a width of 20 μm or more, and a space between the second and sixth circuits has a width of 20 μm or more.