Multilayer PCB Adhesion via Localized Metal Segmentation
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Solution Overview
Problem
The existing multilayer printed circuit board manufacturing process is complicated due to the need for additional protective layers and the potential damage to circuit patterns during photolithography, and the nickel-chromium layer used for adhesion can lower interlayer electrical characteristics and durability.
Innovation Solution
A multilayer board design where a second metal layer with a different composition or crystal structure is formed between the interlayer insulating layer and the upper metal layer in wiring areas, and a third metal layer with the same composition or crystal structure as the first metal layer is used in via areas, simplifying the process and improving reliability and resistance characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a nickel-chromium layer is formed to improve adhesion between interlayer insulating layer and conductive layer, then adhesion is improved, but interlayer electrical characteristics and durability are lowered
Solution Approach 1:
The patent applies different metal materials in different regions: copper is used in via holes for electrical connection, while nickel-chromium is used only in wiring areas for adhesion. This local differentiation allows each region to have optimal properties without compromising the other.
Solution Approach 2:
The metal layer is segmented into different materials based on function: the via hole region uses copper for conductivity, while the wiring area uses nickel-chromium for adhesion. This segmentation resolves the contradiction by separating the conflicting requirements of adhesion and electrical performance.
2Reliability
If additional protective layer is formed to prevent damage to exposed pattern during etching, then pattern protection is improved, but manufacturing process becomes complicated
Solution Approach 1:
The nickel-chromium layer serves dual functions: it provides adhesion between the interlayer insulating layer and conductive layer, and simultaneously protects exposed patterns during etching. This multi-functionality eliminates the need for separate protective layers, simplifying the manufacturing process.
Solution Approach 2:
The protective function is merged into the adhesion layer by using nickel-chromium, which inherently provides both adhesion and protection during etching. This combines multiple functions into a single layer, reducing process complexity.
Data Source
AI summary
Provided are a multilayer board and a method for manufacturing same, in which a different kind of metal layer is formed between an upper metal layer and an interlayer insulating layer, the different kind of metal layer being formed only in a wiring area without being formed in a via area. The multilayer board comprises: a substrate layer; a plurality of first metal layers sequentially stacked on the substrate layer; an interlayer insulating layer formed between two different first metal layers, having a first via hole, and electrically connecting the two different first metal layers through a third metal layer formed in the first via hole; and a second metal layer formed between the upper layer of the two different first metal layers and the interlayer insulating layer.