Wiring Substrate Pad Treatment for Corrosion-Resistant Connections
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Solution Overview
Problem
Existing methods for manufacturing wiring substrates face challenges in effectively connecting multiple electronic components with different shapes on the same surface, as metal posts are formed on all connection pads, leading to potential corrosion and oxidation issues.
Innovation Solution
A method involving the formation of a protective film on some conductor pads and direct formation of conductor posts on others using the same material, ensuring reliable connections without protective film intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal posts are formed on all connection pads, then connectivity is achieved, but corrosion and oxidation issues occur
Solution Approach 1:
The patent applies different treatments to different conductor pads: some pads receive a protective film ( nickel, palladium, or gold) to prevent corrosion and oxidation, while other pads have metal posts formed directly on them for connectivity. This local differentiation resolves the contradiction by protecting vulnerable areas while maintaining functionality in areas where posts are formed.
2Object-affected harmful factors
If protective film is formed on conductor pads, then corrosion prevention is achieved, but bonding strength may be reduced
Solution Approach 1:
The protective film is selectively applied only to conductor pads where metal posts will not be formed, or where posts are formed after the protective film is removed from specific areas. This ensures corrosion protection is provided where needed while maintaining direct metal-to-metal bonding strength where posts are required.
Solution Approach 2:
The protective film is formed on conductor pads in advance before metal post formation. This preliminary protective layer prevents corrosion during subsequent processing steps, and can be selectively removed or penetrated to allow post formation on specific pads, thus preventing corrosion while maintaining bonding strength where needed.
3Reliability
If metal posts are formed on all connection pads, then connectivity is achieved, but material consistency is compromised
Solution Approach 1:
The patent maintains material consistency by forming metal posts using the same material as the conductor layer (e.g., copper) on selected pads, while applying protective films made of different materials (nickel, palladium, gold) only on pads where posts are not formed. This local differentiation preserves material consistency in the conductive paths while providing protection where needed.
Data Source
AI summary
A method for manufacturing a wiring substrate includes forming a conductor layer including first and second pads, forming a resin insulating layer on the conductor layer, forming, in the insulating layer, a first opening exposing the first pad and a second opening exposing the second pad, forming a covering layer on the insulating layer such that the covering layer covers the first and second openings, forming a third opening in the covering layer such that the third opening communicates with the first opening and the first pad is exposed in the third opening, forming, on a surface of the first pad, a protective film formed of material different from material forming the conductor layer, removing the covering layer from the insulating layer, and forming a conductor post on the second pad such that the conductor post is formed of material that is same as the material forming the conductor layer.