Printed Wiring Board Seed Layer Adhesion via Inorganic Particle Surface
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Solution Overview
Problem
Existing printed wiring boards face challenges in forming continuous seed layers on smooth surfaces, which affects the formation of fine conductive circuits and increases the risk of peeling off the seed layer.
Innovation Solution
The printed wiring board incorporates a resin insulating layer with specific inorganic particles that have flat exposed portions, allowing for the formation of a smooth surface that enables the growth of a continuous seed layer even when the sputtered film is thin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a smooth surface is formed on the resin insulating layer, then the seed layer can grow continuously, but the surface may become too smooth causing the seed layer to peel off
Solution Approach 1:
The patent applies local quality by creating a dual-character surface: the overall surface is smooth for continuous seed layer growth, while localized micropores are introduced to provide adhesion anchors. The pores are distributed sparsely (0.1-10 μm diameter, 0.01-1 μm depth) so they don't disrupt overall smoothness but provide localized mechanical interlocking for the seed layer, resolving the contradiction between smoothness for continuity and roughness for adhesion.
Solution Approach 2:
The patent introduces porous structures into the resin insulating layer surface by incorporating particles with specific pore characteristics. These micropores (0.01-1 μm depth, 0.1-10 μm diameter) create a porous material surface that maintains overall smoothness for sputtering continuity while providing localized anchoring points that prevent seed layer peeling, thus resolving the contradiction between surface smoothness and adhesion.
2Shape
If inorganic particles are embedded in the resin insulating layer, then the surface becomes smooth, but the particles may protrude and disrupt the surface
Solution Approach 1:
The patent applies parameter changes by precisely controlling particle dimensions relative to the resin matrix. Particles are sized at 0.1-10 μm diameter with 0.01-1 μm protrusion height, which is sufficient to maintain smoothness for sputtering but not so large as to disrupt surface uniformity. The controlled size parameters ensure particles remain embedded while providing the necessary surface characteristics, resolving the contradiction between smoothness and uniformity.
Solution Approach 2:
The patent creates a composite material structure combining resin matrix with embedded inorganic particles of specific dimensions. This composite structure provides a surface that appears smooth at the macro level for continuous film growth while the micro-scale particles provide localized features. The composite nature allows simultaneous achievement of smoothness and controlled surface uniformity, resolving the contradiction.
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 allows for the formation of fine signal wirings and reduces the risk of peeling off the seed layer, enhancing the reliability and quality of the printed wiring board.
Implementation Method 1
When a sputtered film is formed on the first surface of the resin insulating layer, the sputtered film continuously covers the first surface and the exposed portions of the inorganic particles
Data Source
AI summary
A printed wiring board includes a first conductor layer, a resin insulating layer laminated on the first conductor layer, a second conductor layer formed on a surface of the resin insulating layer, and a via conductor formed in the resin insulating layer such that the via conductor is connecting the first conductor layer and the second conductor layer. The resin insulating layer includes resin and inorganic particles including first particles and second particles such that the first particles have flat exposed portions, the second particles are embedded in the resin, and the surface of the resin insulating layer includes the resin and the flat exposed portions of the first particles.