PCB First Metal Layer Etching Barrier Design
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Solution Overview
Problem
Existing printed circuit boards face challenges in preventing metal layer etching during the etching process and require separate surface treatments, which can complicate the manufacturing process and affect the integrity of the circuit pattern.
Innovation Solution
A printed circuit board design featuring an insulating layer with a circuit pattern embedded, including a first metal layer exposed through the surface, which serves as an etching barrier and surface treatment layer, and a second metal layer, potentially with a third metal layer, preventing alloying and eliminating the need for a separate surface treatment by using materials like palladium or tin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate surface treatment layer is added to prevent etching, then the metal layer is protected from etching, but the device complexity and manufacturing process become more complicated
Solution Approach 1:
The patent combines the etching barrier function and surface treatment function into the first metal layer itself. By selecting materials with appropriate etching resistance and surface properties, the first metal layer simultaneously serves as both the conductive layer and the protective surface layer, eliminating the need for separate treatment layers while maintaining etching prevention capability.
Solution Approach 2:
The first metal layer is designed to perform multiple functions: it provides electrical conductivity, acts as an etching barrier, and provides the necessary surface properties for subsequent processing. This multi-functional design reduces the overall layer structure complexity while achieving the required protection against etching.
2Reliability
If a separate surface treatment is applied, then the surface properties are improved, but the manufacturing process time and complexity increase
Solution Approach 1:
The surface treatment requirements are integrated into the material selection and formation process of the first metal layer. By choosing materials that inherently possess the desired surface properties and etching resistance, the separate surface treatment step is eliminated, reducing manufacturing time while maintaining reliable surface characteristics.
3Reliability
If the first metal layer is fully covered by insulating layer, then the circuit pattern is protected, but the connection conductor cannot be directly connected to the metal layer
Solution Approach 1:
The insulating layer is applied selectively rather than uniformly covering the entire first metal layer. By leaving certain regions of the first metal layer exposed, the patent enables direct connection between connection conductors and the metal layer in those specific areas, while maintaining protection in other regions. This localized approach balances protection requirements with connection needs.
Data Source
AI summary
A printed circuit board includes an insulating layer, a circuit pattern embedded in the insulating layer and including a first metal layer, a second metal layer and a third metal layer disposed between the first metal layer and the second metal layer, and a connection conductor disposed on one surface of the insulating layer and connected to the circuit pattern, wherein the first metal layer is exposed through the one surface of the insulating layer.