Wired Circuit Board Ion Migration Prevention
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Solution Overview
Problem
Conventional suspension boards with circuits experience increased transmission loss and ion migration phenomena due to direct formation of insulating layers on conductive patterns, leading to defective adhesion and conductivity issues.
Innovation Solution
A wired circuit board structure featuring a metal supporting board, a first metal thin film, a metal foil, a second metal thin film, and an insulating layer, where the second metal thin film is interposed between the metal foil and the insulating layer, made of copper and nickel or chromium alloys, to prevent ion migration and enhance adhesion and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal supporting board made of stainless steel is used, then structural strength is improved, but transmission loss increases
Solution Approach 1:
The patent segments the supporting board into two parts: a stainless steel board for structural strength and a copper foil layer for low transmission loss. This segmentation allows each material to perform its optimal function - stainless steel provides mechanical support while copper minimizes signal loss.
Solution Approach 2:
The patent uses a composite structure combining stainless steel and copper foil. The stainless steel supporting board provides strength, while the copper foil layer reduces transmission loss. This composite approach resolves the contradiction by integrating materials with complementary properties.
2Loss of energy
If a lower conductor made of copper or copper alloy is formed on stainless steel to reduce transmission loss, then transmission loss is reduced, but ion migration phenomenon occurs causing defective adhesion and conductivity
Solution Approach 1:
The patent introduces an insulating layer as an intermediary barrier between the copper lower conductor and the upper conductor. This insulating layer prevents direct contact that would cause ion migration, while still allowing the copper conductor to reduce transmission loss. The intermediary layer resolves the contradiction by blocking the harmful ion migration path.
Solution Approach 2:
The patent extracts the problematic direct metal-to-metal contact interface by inserting an insulating layer between the copper lower conductor and the upper conductor. This extraction of the direct contact path eliminates the ion migration phenomenon while preserving the low transmission loss benefit of copper.
3Device complexity
If an insulating layer is formed directly on the lower conductor, then layer structure is simplified, but ion migration phenomenon occurs
Solution Approach 1:
The insulating layer serves as an intermediary barrier that prevents ion migration between conductors. By positioning this layer between the copper lower conductor and the upper conductor, the patent achieves both structural simplicity and prevention of ion migration phenomena.
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
This structure reduces transmission loss and prevents ion migration, ensuring improved adhesion and conductivity, thus providing excellent long-term reliability with a simple layer structure.
Implementation Method 1
an ion migration phenomenon occurs in which the copper or the copper alloy containing mainly copper of the lower conductor migrates to a surface of the insulating layer or to the inner portion thereof with moisture or water absorption by the insulating layer in the presence of an electric current or voltage
Data Source
AI summary
A wired circuit board is provided which can reduce transmission loss with a simple layer structure and also features excellent long-term reliability by preventing the occurrence of an ion migration phenomenon between a metal foil and an insulating layer to improve the adhesion between the metal foil and the insulating layer and the conductivity of a conductor. A metal supporting board is prepared and a first metal thin film is formed on the metal supporting board by sputtering or electrolytic plating. A metal foil is formed on the first metal thin film by electrolytic plating. A second metal thin film is formed over the metal foil and the metal supporting board by electroless plating or sputtering. An insulating base layer is formed on the second metal thin film. A conductive pattern is formed as a wired circuit pattern on the insulating base layer. An insulating cover layer is formed on the insulating base layer to cover the conductive pattern.