Rigid-Flexible PCB Lamination via Via Filling and Low-Temperature Adhesion
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Solution Overview
Problem
Conventional rigid flexible printed circuit boards face challenges in manufacturing complexity and thermal deformation during lamination, leading to alignment accuracy issues and increased defect ratios due to the close temperature difference between the base film and adhesive layer.
Innovation Solution
A method involving a flexible board with via holes filled with conductive material and a cured base substrate, where the cured base substrate is laminated onto the rigid region, eliminating the need for a plating and etching process and reducing thermal deformation by using a thermosetting resin adhesive layer with a lower adhesion temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional plating and etching processes are used to form copper layers in via holes, then electrical connectivity is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent extracts and removes the plating and etching processes from the manufacturing flow, replacing them with a direct lamination approach where copper foils are bonded to the flexible substrate through adhesive layers during the lamination process, eliminating complex metal deposition and pattern formation steps
Solution Approach 2:
The patent segments the circuit board into distinct layers (flexible substrate, adhesive layers, copper foils) that are separately prepared and then assembled through lamination, allowing each layer to be optimized independently and simplifying the overall manufacturing process
2Ease of manufacture
If base substrates are heated at adhesion temperature (140-150°C) for bonding, then base substrates are bonded together, but thermal deformation occurs in base films
Solution Approach 1:
The patent changes the temperature parameter by using a thermosetting resin adhesive layer that cures at a lower temperature (below the melting point of the polypropylene base film), preventing thermal deformation while achieving proper bonding through chemical curing rather than thermal melting
Solution Approach 2:
The patent introduces a thermosetting resin adhesive layer as an intermediary between base substrates that enables bonding through low-temperature curing, acting as a buffer that prevents direct thermal transfer to the base film and eliminates the need for high-temperature heating
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 approach simplifies the manufacturing process, reduces the risk of thermal deformation, improves alignment accuracy, and decreases the defect ratio of printed circuit boards by using a conductive material to connect internal and external circuit patterns, enhancing the reliability of multilayer printed circuit boards.
Implementation Method 1
one or more via holes formed in the flexible board and one or more via holes formed in the cured base substrate are filled with a conductive material
Implementation Method 2
an adhesive layer is provided on one or more surfaces of each of the base substrates for bonding of the base substrates
Data Source
AI summary
Disclosed are a printed circuit board manufactured by filling a via hole formed in a flexible board and a via hole formed in a cured base substrate and then laminating the flexible board and the cured base substrate and a method of manufacturing same. The method includes preparing a flexible board including a flexible region and a rigid region, preparing a cured base substrate, and laminating the cured base substrate on the rigid region of the flexible board, in which during the laminating, via holes respectively formed in the flexible board and the cured base substrate are first filled with a conductive material and then the flexible board and the cured base substrate are laminated.