Wired Circuit Board Reference Hole Stepped Portion
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Solution Overview
Problem
Conventional etching methods for forming reference holes in suspension boards with circuit result in inaccurate positioning due to delamination of the etching resist, leading to increased minimum diameter of the holes and reduced connection reliability between the magnetic head and the suspension board.
Innovation Solution
A wired circuit board design featuring a metal supporting layer with a stepped portion surrounding the reference hole, ensuring improved adherence of the etching resist and preventing etchant entry, which allows for uniform and accurate formation of the reference hole.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional etching method is used to form reference hole, then etching process is simple, but etching resist delaminates from metal supporting layer causing inaccurate positioning
Solution Approach 1:
A stepped portion is formed on the metal supporting layer before the etching resist is applied. This stepped portion creates a mechanical interlocking structure that prevents delamination of the etching resist during the etching process, thereby maintaining positioning accuracy without complicating the overall manufacturing process
Solution Approach 2:
The stepped portion is formed only in the specific region where the reference hole will be etched, rather than modifying the entire metal supporting layer. This localized modification provides the necessary adhesion enhancement only where needed, maintaining simplicity in other areas of the manufacturing process
2Productivity
If etching resist is laminated on metal supporting layer, then etching can proceed, but etchant enters interface causing delamination and increased hole diameter
Solution Approach 1:
The stepped portion is formed in advance to create a physical barrier that prevents etchant from entering the interface between the etching resist and metal supporting layer. This preliminary structural modification counteracts the potential harmful effect of etchant penetration before it can occur during the etching process
Solution Approach 2:
The stepped portion acts as an intermediary structure between the etching resist and the metal supporting layer, providing a mechanical interlocking feature that enhances adhesion and prevents delamination caused by etchant penetration at the interface
3Ease of manufacture
If reference hole minimum diameter is increased due to delamination, then etching is more tolerant, but positioning accuracy and connection reliability decrease
Solution Approach 1:
The stepped portion is formed before etching to establish a mechanical interlocking structure that maintains consistent reference hole dimensions. This preliminary structural preparation ensures that the reference hole minimum diameter remains within tight tolerances, achieving both manufacturing ease and high positioning accuracy
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 enhances the accuracy of reference hole formation, improving the positioning accuracy and connection reliability between the magnetic head and the suspension board.
Implementation Method 1
an etching resist 52 is laminated first on each of the top and back surfaces of a metal supporting layer 51
Implementation Method 2
the predetermined hole formation region 54 exposed from the etching resist 52 is removed through contact with an etchant to bore the reference hole 53
Data Source
AI summary
A wired circuit board includes a metal supporting layer, an insulating layer formed on the metal supporting layer, and a conductive layer formed on the insulating layer. In the metal supporting layer, a reference hole for positioning is formed, and a stepped portion is formed so as to surround the reference hole.