Wiring Board Slit Geometry to Prevent Solder Resist Damage
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Solution Overview
Problem
Conventional methods of dicing wiring boards result in damage, such as chipping or cracking, to the solder resist layer and detachment of the solder resist layer from the wiring structure due to increased load when cutting through a wider slit in the solder resist layer, and the wiring structure is not protected by the solder resist layer.
Innovation Solution
The solder resist layer includes slits with edge portions that meander in a wave-like manner, reducing the contact area and frictional force during cutting, thereby preventing detachment and damage to the solder resist layer and the wiring structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a linear slit with wider width than cutting tool is formed on the solder resist layer to avoid contact during cutting, then damage to the solder resist layer is prevented, but the solder resist layer and wiring structure detach from each other due to increased load on the exposed wiring structure
Solution Approach 1:
The patent applies curvature by forming the edge portion of the solder resist layer in a wave-like manner instead of a straight line. This curved configuration reduces the contact area with the cutting tool during dicing, thereby minimizing frictional force and preventing both damage to the solder resist layer and detachment from the wiring structure. The wave-like edge portion allows the cutting tool to pass through with reduced mechanical stress concentration.
2Object-affected harmful factors
If the wiring structure is cut in the exposed region from the linear slit, then the solder resist layer avoids contact with the cutting tool, but the load on the wiring structure increases in a direction away from the solder resist layer causing detachment
Solution Approach 1:
The wave-like edge portion of the solder resist layer creates a curved interface that reduces the effective contact area with the cutting tool. This curvature distributes the cutting load more evenly and reduces the frictional force in the direction away from the solder resist layer, preventing the wiring structure from detaching while still allowing the cut to proceed through the exposed region.
Data Source
AI summary
A wiring board assembly includes a wiring structure and an insulating layer. The insulating layer covers a surface of the wiring structure and includes a slit that exposes a predetermined region on the surface of the wiring structure. An edge portion of the outermost insulating layer corresponding to the edge portion of the slit meanders in a wave-like manner.