PCB Assembly Sheet Warping Control via Dummy Trace Grooves
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Solution Overview
Problem
Printed circuit board assembly sheets often warp during manufacturing, leading to handling difficulties and reduced yield due to residual stress in the insulating layers and support substrates.
Innovation Solution
Incorporating a dummy trace portion with grooves in the insulating layers between printed circuit boards and the support frame, which reduces residual stress by varying the thickness between conductor traces, thereby inhibiting warping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a plurality of printed circuit boards are arranged on a support substrate to form an assembly sheet, then handling efficiency is improved, but residual stress in the insulating layers causes warping
Solution Approach 1:
The patent introduces dummy trace portions with grooves in specific locations between printed circuit boards and the support frame. These local structural modifications create regions with reduced thickness in the insulating layers, allowing differential stress distribution that compensates for warping tendencies in the overall assembly sheet.
Solution Approach 2:
The patent modifies the physical parameters of the insulating layers by introducing grooves that vary the thickness in specific regions. This changes the mechanical properties (stress distribution, flexibility) of the insulating layers in the dummy trace portions, enabling them to counteract warping forces while maintaining electrical insulation functionality.
2Productivity
If the support substrate is cut to separate assembly sheets, then individual sheets are obtained for further processing, but warping occurs during separation
Solution Approach 1:
The patent divides the support substrate into multiple assembly sheet regions, each containing printed circuit boards and dummy trace portions. The dummy trace portions are strategically positioned to provide stress relief during the cutting and separation process, enabling clean separation while maintaining flatness of the resulting individual sheets.
3Shape
If dummy trace portions are added to the assembly sheet, then warping is inhibited, but device complexity increases
Solution Approach 1:
The dummy trace portions serve multiple functions: they provide stress relief to prevent warping, maintain the electrical insulation properties of the assembly sheet, and facilitate the cutting and separation process. By making these structural elements multi-functional, the patent reduces the need for additional separate components that would increase complexity.
Data Source
AI summary
A dummy trace portion is provided in a region between at least a suspension board with circuit on one end side and a support frame of a suspension board assembly sheet with circuits. A base insulating layer is formed on a support substrate in the dummy trace portion. A plurality of conductor traces are formed on the base insulating layer, and a cover insulating layer is formed on the base insulating layer to cover each conductor trace. At least one of the base insulating layer and the cover insulating layer in the dummy trace portion has a groove.