PCB Substrate Modified Layer Inhibits Metal Diffusion
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Solution Overview
Problem
Current substrates for printed circuit boards face challenges in maintaining high adhesion between metal layers and resin films, especially in high-density boards, where finer conductive patterns are prone to peeling due to metal atom diffusion, and existing solutions like chromium layer deposition require costly vacuum equipment.
Innovation Solution
A substrate with a modified layer on the resin film, containing a metal ion or compound different from the main metal layer, formed using an alkali solution and rinsed to leave the ion in the layer, inhibiting metal diffusion and improving adhesion at a lower cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a metal layer is directly deposited on a resin film, then the manufacturing process is simple, but the adhesion between the metal layer and resin film decreases over time due to metal atom diffusion
Solution Approach 1:
A modified layer is formed on the resin film surface before metal layer deposition. This preliminary modification creates a barrier that prevents metal atom diffusion into the resin film, thereby maintaining adhesion over time while keeping the overall process simple
Solution Approach 2:
The modified layer acts as an intermediary between the resin film and the metal layer. It contains metal ions that create a diffusion barrier, preventing direct contact and diffusion between the main metal layer and the resin film, thus preserving adhesion
2Reliability
If a thin chromium layer is deposited by sputtering to prevent metal diffusion, then adhesion is improved, but costly vacuum equipment is required
Solution Approach 1:
The patent uses a chemical modification process that can be performed with simple equipment instead of expensive vacuum sputtering equipment. The modified layer is formed through chemical treatment rather than physical vapor deposition, eliminating the need for costly vacuum systems
Solution Approach 2:
The patent replaces the mechanical/physical sputtering process with a chemical modification process. Instead of using vacuum equipment to deposit chromium, the resin film is chemically treated to form a modified layer with metal ions that provide the same diffusion barrier function
3Productivity
If finer conductive patterns are formed for higher density, then board performance is improved, but the patterns become more liable to peel from the resin film
Solution Approach 1:
The modified layer is formed on the resin film surface before the metal patterns are created. This preliminary modification creates a durable adhesion barrier that remains effective even when the metal patterns are made very fine, preventing peeling in high-density configurations
Solution Approach 2:
The modified layer serves as an intermediary that strengthens the bond between the resin film and fine metal patterns. The metal ions in the modified layer create a robust interface that prevents diffusion and peeling, enabling the use of finer conductive patterns for higher density boards
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a cost-effective substrate with improved adhesion between the metal layer and resin film, preventing peeling and maintaining high adhesion even after weathering tests, while avoiding the limitations of vacuum equipment usage.
Implementation Method 1
forming a modified layer on a surface of a resin film by using an alkali solution containing a metal ion
Implementation Method 2
in the rinse step, the metal ion is left in the modified layer
Implementation Method 3
depositing a metal different from the metal ion in the alkali solution on the resin film
Data Source
AI summary
According to an embodiment of the present invention, a substrate for a printed circuit board, the substrate including a resin film and a metal layer deposited on at least one surface of the resin film, includes a modified layer on the surface of the resin film on which the metal layer is deposited, the modified layer having a composition different from another portion, in which the modified layer contains a metal, a metal ion, or a metal compound different from a main metal of the metal layer. The content of a metal element of the metal, the metal ion, or the metal compound on a surface of the modified layer is preferably 0.2 atomic % or more and 10 atomic % or less.