Wiring Substrate Adhesion Layer Design for Peeling Resistance
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Solution Overview
Problem
The existing wiring substrates face issues with adhesiveness between copper or copper alloy wiring patterns and protective insulation layers, leading to peeling off due to bending or thermal stress.
Innovation Solution
A wiring substrate design featuring a concave portion in the insulation layer with a wiring layer and adhesion layer interposed between the wiring layer and protective insulation layer, where the adhesion layer has higher adhesiveness than the wiring layer, and is formed to cover the pad and protrusion surfaces, enhancing the contact area and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a wiring pattern is formed of copper or copper alloy, then electrical conductivity is improved, but adhesiveness with the protective insulation layer deteriorates
Solution Approach 1:
An adhesion layer is introduced as an intermediary between the copper wiring pattern and the protective insulation layer. This adhesion layer has higher adhesiveness with the protective insulation layer than the copper wiring pattern itself, preventing peeling while maintaining the electrical conductivity of the copper layer.
Solution Approach 2:
The structure employs a composite material approach by stacking multiple layers with different properties: the copper wiring pattern provides electrical conductivity, while the adhesion layer provides bonding strength. This composite structure combines the advantages of different materials to achieve both conductivity and adhesion.
2Device complexity
If the protective insulation layer is formed directly on the wiring pattern, then manufacturing simplicity is improved, but resistance to peeling under thermal stress deteriorates
Solution Approach 1:
The adhesion layer serves as a mediator between the wiring pattern and protective insulation layer, specifically designed to withstand thermal stress and prevent peeling. This intermediate layer absorbs thermal expansion differences and maintains bonding integrity under temperature variations.
3Adaptability or versatility
If the wiring pattern is made fine for high integration, then functionality is improved, but adhesion area with the protective insulation layer is reduced
Solution Approach 1:
The adhesion layer compensates for the reduced adhesion area by providing superior adhesion properties per unit area. Even when the wiring pattern is made fine, the adhesion layer ensures sufficient bonding strength through its enhanced adhesive characteristics.
Solution Approach 2:
The invention changes the material parameters of the adhesion layer to achieve higher specific adhesion strength. By selecting materials with appropriate adhesive properties, the system maintains reliable bonding even when the total adhesion area is reduced due to finer wiring patterns.
Data Source
AI summary
A first insulation layer includes a concave portion formed in a lower surface thereof. A first wiring layer is formed in the concave portion. A protective insulation layer has an opening configured to expose a part of the first wiring layer and is stacked on the lower surface of the first insulation layer. An adhesion layer is interposed between the first wiring layer and the protective insulation layer and has higher adhesiveness with the protective insulation layer than the first wiring layer. The first wiring layer includes a pad portion formed in the concave portion and a protrusion protruding from a portion of a lower surface of the pad portion into the opening. The adhesion layer is formed to cover the lower surface of the pad portion and a side surface of the protrusion and to expose a lower end face of the protrusion.