Composite Circuit Board Manufacturing with Integrated COF Stability
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Solution Overview
Problem
The manufacturing method of composite circuit boards is lengthy and results in poor dimensional stability of the inner Chip on Flex (COF) due to its inherent properties, which do not meet the requirements of surface mount technology (SMT).
Innovation Solution
A method involving a coiled copper-clad substrate with a two-sided adhesive layer, where the substrate is etched to form inner and outer conductive circuits, and metal protection layers are applied, followed by solder mask treatment and separation into composite circuit board units with conductive holes, ensuring simultaneous manufacturing of inner and outer circuits with improved stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the conventional manufacturing method is used to integrate COF with flexible circuit boards, then the composite circuit board can be produced, but the manufacturing process becomes lengthy and the dimensional stability of the inner COF deteriorates
Solution Approach 1:
The patent merges the manufacturing processes of the flexible circuit board and COF into a single integrated process. The copper-clad substrate and adhesive layer are formed as one combined structure, allowing simultaneous processing of both components. This eliminates the need for separate manufacturing and assembly steps, thereby reducing the overall manufacturing time while maintaining dimensional stability through unified process control.
Solution Approach 2:
The patent applies preliminary action by forming the copper-clad substrate and adhesive layer in advance as an integrated structure before the COF is fully processed. The adhesive layer is pre-applied to the copper-clad substrate, and the outer conductive circuit is formed on the adhesive layer beforehand. This preliminary preparation enables faster subsequent processing and assembly, reducing the total manufacturing cycle time while ensuring dimensional stability is maintained from the outset.
2Reliability
If separate manufacturing processes are used for inner and outer circuits, then each circuit can be processed independently, but the process complexity increases and the risk of damaging inner circuits increases
Solution Approach 1:
The patent combines the manufacturing of inner and outer circuits into a single integrated process. The copper-clad substrate with adhesive layer forms the base structure, and the outer conductive circuit is formed directly on the adhesive layer in the same processing sequence. This unified approach reduces the number of separate manufacturing steps, lowering process complexity while providing inherent protection to the inner circuit structure through the integrated design.
Solution Approach 2:
The patent applies the nested doll principle by placing the inner circuit structure within the layered construction of the copper-clad substrate and adhesive layer. The inner conductive circuit is formed on the copper-clad substrate, which is then covered by the adhesive layer, and the outer conductive circuit is formed on the adhesive layer. This nested arrangement protects the inner circuit during subsequent processing steps while maintaining a relatively simple overall manufacturing process.
Data Source
AI summary
A composite circuit board includes a composite circuit board unit, a first solder mask formed on a first metal protection layer of the composite circuit board unit, and a second solder mask formed on a second metal protection layer of the composite circuit board unit. Two ends of a first outer conductive circuit are bent back toward each other and spaced apart a predetermined distance to form a first window. Two ends of a second outer conductive circuit are bent back toward each other and spaced apart a predetermined distance to form a second window.