Printed Wiring Board Insulating Layer for Fine Seed-Layer Circuits
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Solution Overview
Problem
Existing printed wiring boards face challenges in forming a continuous seed layer on interlayer insulating layers with rough surfaces, leading to difficulties in creating fine conductor circuits due to increased etching requirements and thickness of the sputtering film.
Innovation Solution
A printed wiring board design featuring a resin insulating layer with inorganic particles, where first inorganic particles protrude and second inorganic particles are fully embedded, resulting in a smooth surface that allows for a thin, continuous seed layer formation via sputtering, enabling fine conductor circuit production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermosetting resin mixture with inorganic filler is used as an interlayer insulating layer, then the insulating layer provides electrical insulation and structural support, but the surface becomes rough making it difficult to form a continuous seed layer
Solution Approach 1:
The patent changes the particle size distribution parameter of the inorganic filler, specifically using fine particles with an average diameter of 0.1 μm or less. This parameter change transforms the surface morphology from rough to smooth while maintaining the electrical insulation properties of the thermosetting resin mixture.
Solution Approach 2:
The patent creates a composite material system consisting of thermosetting resin combined with specifically sized inorganic filler particles. This composite approach allows the material to simultaneously provide electrical insulation, structural support, and a smooth surface finish that enables continuous seed layer formation.
2Strength
If a rough surface is used for the interlayer insulating layer, then the inorganic filler provides structural reinforcement, but the sputtering film thickness must be increased to achieve continuity
Solution Approach 1:
The patent changes the particle size parameter of the inorganic filler to 0.1 μm or less, which maintains the structural reinforcement function while creating a smooth surface. This allows the sputtering film to be deposited as a thin, continuous layer without requiring excessive thickness to bridge surface irregularities.
3Reliability
If a thick sputtering film is deposited to ensure continuity on a rough surface, then the seed layer provides adequate coverage, but the etching amount increases making fine conductor circuit formation difficult
Solution Approach 1:
The patent changes the surface morphology parameter by using fine inorganic filler particles (average diameter 0.1 μm or less), which enables the formation of a smooth surface. This allows deposition of a thin, continuous sputtering film that requires minimal etching, thereby enabling the formation of fine conductor circuits while maintaining seed layer continuity.
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 design enables the formation of high-quality, fine conductor circuits with reduced etching amounts, ensuring reliable connections and reduced connection resistance, even in larger boards.
Implementation Method 1
a thin, continuous seed layer formation via sputtering
Data Source
AI summary
A printed wiring board includes a first conductor layer, a resin insulating layer laminated on the first conductor layer and including resin material and inorganic particles, a second conductor layer formed on a first surface of the insulating layer such that the first conductor layer is facing a second surface of the insulating layer, and a via conductor formed in an opening extending through the insulating layer and connecting the first and second conductor layers. The insulating layer is formed such that the inorganic particles include first inorganic particles partially embedded in the resin and second inorganic particles completely embedded in the resin, the first inorganic particles have first portions protruding from the resin and second portions embedded in the resin respectively, and the first surface of the resin insulating layer includes a surface of the resin and surfaces of the first portions exposed from the surface of the resin.