Multi-layer Flexible Circuit Board Thinned Bonding Areas
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Solution Overview
Problem
The thickness of conventional multi-layer flexible printed circuit boards (FPCBs) and anisotropic conductive films (ACFs) hinders thin bonding with electronic appliances, increasing defect rates due to higher pressing pressure, temperature, and bonding time, especially when connecting to camera modules.
Innovation Solution
A method to manufacture a multi-layer FPCB by removing the pressing and heating areas from the upper and lower base layers and adhesion sheets, reducing the thickness of these areas, thereby decreasing the required pressing pressure, temperature, and bonding time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of FPCB and ACF is increased to ensure bonding strength, then bonding reliability is improved, but bonding process complexity and defect rate increase due to higher pressing pressure, temperature, and time requirements
Solution Approach 1:
The FPCB is divided into multiple layers with different thickness characteristics. The pressing/heating area is segmented from the non-pressing areas, allowing localized thickness optimization. This enables the bonding interface to have reduced thickness only where needed, while maintaining overall structural integrity and reliability.
Solution Approach 2:
The patent applies different thickness characteristics to different areas of the FPCB. The pressing/heating area has reduced thickness compared to other areas, optimizing the bonding process locally without compromising the overall strength and reliability of the entire board structure.
2Productivity
If the thickness of pressing/heating areas is reduced to enable thin bonding, then bonding time and processing requirements are decreased, but manufacturing complexity increases
Solution Approach 1:
The varying thickness structure is prepared in advance during the FPCB manufacturing process, before the bonding operation. The pressing/heating areas are pre-thinned through controlled removal of material, so that when bonding occurs, the reduced thickness immediately provides the productivity benefit without adding complexity to the bonding process itself.
3Ease of manufacture
If uniform thickness is maintained across the entire FPCB, then manufacturing simplicity is preserved, but bonding efficiency is reduced due to increased pressing pressure, temperature, and time requirements
Solution Approach 1:
Instead of maintaining uniform thickness throughout, the patent applies local quality variation by thinning only the pressing/heating areas. This localized modification achieves time reduction in bonding without requiring complete redesign of the entire manufacturing process, balancing simplicity and efficiency.
Solution Approach 2:
The patent applies partial action by modifying only the specific areas that require bonding (pressing/heating areas) rather than the entire FPCB. This selective thinning achieves the necessary bonding efficiency improvement without the excessive complexity that would result from modifying the entire structure.
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 results in improved heat conduction efficiency, a 40% reduction in bonding time, and a lower defect rate for the target module, enhancing the bonding process by thinning the pressing/heating areas and optimizing heat and pressure transfer.
Implementation Method 1
an adhesion sheet, an upper base layer on the adhesion sheet, and a lower base layer under the adhesion sheet
Implementation Method 2
improved heat conduction efficiency
Data Source
AI summary
Disclosed are a multi-layer flexible printed circuit board and a method for manufacturing the same. The multi-layer flexible printed circuit board includes an adhesion sheet from which a pressing and heating area is cut, an upper base layer, from which the pressing and heating area is cut, on the adhesion sheet, and a lower base layer under to the adhesion sheet.