Wiring Board Insulating Layer Warping Reduction
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Solution Overview
Problem
Wiring boards with interlayer insulating layers containing inorganic fibers face challenges in thermal expansion and adhesion issues, leading to warping and reliability problems, especially when high-density wiring is required.
Innovation Solution
A wiring board design that includes interlayer insulating layers made of resin with inorganic fillers, where the filler is not in contact with the conductive layers, and a manufacturing method that forms a thin resin layer without inorganic fillers on the surface to improve adhesion and reduce warping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If inorganic fiber base material is used in interlayer insulating layer, then mechanical strength is improved, but thermal expansion mismatch and adhesion problems occur causing warping
Solution Approach 1:
The patent removes inorganic fiber base material from the interlayer insulating layer, extracting the problematic component that causes thermal expansion mismatch and adhesion issues. The insulating layer is reformulated to contain only resin and inorganic filler particles, eliminating the source of warping while maintaining necessary insulating properties.
Solution Approach 2:
The patent changes the compositional parameters of the insulating layer by specifying that it must not contain inorganic fiber base material. Instead, the layer comprises resin with dispersed inorganic filler particles, fundamentally altering the material structure to achieve better thermal expansion matching and adhesion with conductive layers.
2Stability of the object's composition
If inorganic filler is present in interlayer insulating layer, then thermal expansion is reduced, but adhesion to conductive layer deteriorates
Solution Approach 1:
The patent applies local quality by creating a dual-layer structure where the lower portion contains inorganic filler for thermal stability, while the upper surface portion is filler-free to ensure adhesion. This spatial differentiation of material properties allows each region to fulfill its specific function without compromising the other.
Solution Approach 2:
The patent introduces a resin-rich intermediate layer at the surface that acts as a mediator between the filler-containing insulating layer and the conductive layer. This intermediate resin layer provides a smooth, adhesive surface for conductive material deposition while the underlying filler-containing structure maintains thermal expansion stability.
3Productivity
If high-density wiring is implemented, then circuit functionality is improved, but warping and connection reliability problems increase
Solution Approach 1:
The patent performs preliminary action by pre-forming the insulating layer with optimized composition and surface characteristics before depositing conductive layers. The surface is prepared in advance to be free of inorganic filler, ensuring optimal adhesion conditions are established before high-density wiring patterns are created, preventing warping and connection issues.
Data Source
AI summary
A wiring board includes a core structure including a core substrate, and a buildup structure formed on the core structure and including an interlayer insulating layer and a conductive layer. The interlayer insulating layer does not contain inorganic fiber and includes a resin and an inorganic filler, and the conductive layer is formed on the interlayer insulating layer such that the inorganic filler in the interlayer insulating layer is not in contact with the conductive layer.