Flexible PCB Coating Method for Circuit Protection
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Solution Overview
Problem
Flexible printed circuit boards face challenges in manufacturing costs, operational reliability, and thickness due to complex processes, high costs, and damage from bending, especially in large digitizer applications, where adhesion issues and deformation occur.
Innovation Solution
A flexible printed circuit board with a protective coating layer formed by applying and curing a coating solution on the circuit pattern, which includes via holes filled with conductors for electrical connection, and a method involving printing conductive paste and firing at specific temperatures to ensure strong adhesion and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coverlay is utilized to protect the circuit pattern, then protection is provided, but manufacturing costs increase and thickness cannot be reduced to predetermined level
Solution Approach 1:
The patent merges the protective coating function with the existing insulating film structure. The coating solution is applied directly onto the circuit pattern and insulating film assembly, combining protection and insulation functions into a single integrated layer, thereby eliminating the need for separate coverlay components and reducing manufacturing costs.
Solution Approach 2:
The coating solution serves multiple functions simultaneously: it protects the circuit pattern from damage, provides additional insulation, and can be configured to have different thicknesses to meet specific requirements. This multi-functional approach replaces the dedicated coverlay, reducing overall thickness while maintaining protection.
2Manufacturing precision
If etching or plating processes are used to manufacture flexible printed circuit boards, then circuit patterns are formed, but manufacturing processes become complicated and costs increase
Solution Approach 1:
The patent replaces traditional mechanical etching processes with a coating-based approach. The circuit pattern is formed by applying a coating solution that contains conductive materials, which is then cured to create the circuit pattern. This substitution of mechanical etching with coating application simplifies the manufacturing process while maintaining precision.
Solution Approach 2:
The patent changes the manufacturing approach from subtractive (etching) to additive (coating application). By controlling the parameters of the coating solution (conductive material concentration, coating thickness, curing conditions), the circuit pattern is formed with precise control, eliminating the need for complex etching and plating sequences.
3Adaptability or versatility
If the flexible printed circuit board is subjected to repeated bending and warping, then flexibility is achieved, but the circuit pattern is damaged and deformed
Solution Approach 1:
The patent applies a protective coating onto the circuit pattern before final assembly. This coating acts as a cushioning layer that absorbs and distributes the stress of bending and warping, preventing direct mechanical damage to the circuit pattern. The coating is applied in advance to ensure protection is already in place before the board undergoes flexibility testing or service.
4Manufacturing precision
If the adhesion process is performed during plating, then circuit pattern is formed, but adhesion between circuit pattern and insulating film decreases
Solution Approach 1:
The patent performs adhesion promotion as a preliminary action before circuit pattern formation. The coating solution is applied to the insulating film surface beforehand, allowing the conductive coating to bond directly to the prepared surface. This preliminary coating application ensures strong adhesion is established before the circuit pattern is fully formed, preventing subsequent delamination.
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
The solution maintains firm attachment of the circuit pattern to the substrate, prevents damage from bending, reduces manufacturing costs, and ensures stable operational reliability, allowing for thinner, more compact designs with improved merchantability.
Implementation Method 1
a protective coating layer which is formed by applying and curing a coating solution so as to cover the circuit pattern
Implementation Method 2
printing a circuit pattern with a conductive paste or conductive ink on a flexible insulating film and then plating the circuit pattern
Data Source
AI summary
A flexible printed circuit board includes a substrate, a circuit pattern formed on the substrate, and a protective coating layer formed on the substrate by applying and curing a coating solution to cover and protect the circuit pattern. A method for manufacturing forming a circuit pattern on a substrate and forming a protective coating layer for covering and protecting the circuit pattern by applying a coating solution on the substrate. The circuit pattern may be securely attached to the substrate, and damage and deformation of the circuit pattern due to repeated bending or warping of the substrate may be prevented, ultimately improving operational reliability.