Flexible PCB Paste Filling via Peelable Mask
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The refinement of flexible printed wiring boards is hindered by the difficulty in accurately printing conductive paste onto fine circuit patterns due to the expansion and contraction of flexible substrates and the need for precise positioning, which is limited by conventional screen printing methods.
Innovation Solution
A manufacturing method involving a metal foil clad laminate, where a peelable printing plate layer is formed to embed the circuit pattern, blind holes are created, and conductive paste is printed using the printing plate layer as a mask, eliminating the need for precise positioning of the screen plate and allowing for accurate filling of the paste within these holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the circuit pattern is refined by reducing the thickness of the conductive layer, then the circuit pattern density is improved, but the current capacity is reduced
Solution Approach 1:
The patent transitions from two-dimensional surface plating to three-dimensional paste filling by creating conduction holes through the insulating substrate and filling them with conductive paste. This vertical dimension allows current capacity to be increased without increasing the lateral width of the circuit pattern, thus maintaining fine pitch while improving current carrying capability.
Solution Approach 2:
The conductive paste is nested within the conduction holes that pass through the insulating substrate, creating a multi-layer structure where the paste is embedded within the hole space. This nesting approach allows the conductive material to be concentrated in the vertical dimension rather than requiring increased lateral dimensions.
2Manufacturing precision
If the width of wiring and diameter of conduction hole are reduced for refinement, then the circuit pattern density is improved, but the positioning accuracy requirement increases
Solution Approach 1:
The patent introduces a photosensitive resin layer as an intermediary that forms a relief pattern matching the circuit pattern. This relief pattern serves as a self-aligned mask for paste application, eliminating the need for separate positioning operations between the screen plate and circuit pattern. The photosensitive resin layer mediates the alignment process and enables accurate paste filling without requiring high-precision positioning.
Solution Approach 2:
The photosensitive resin layer is formed in advance with a relief pattern that precisely matches the circuit pattern before the paste filling step. This preliminary formation of the relief pattern establishes the exact positioning reference needed for subsequent paste application, ensuring accurate alignment without requiring complex positioning operations during paste filling.
3Ease of manufacture
If conventional screen printing is used for paste application, then the manufacturing process is simple, but the positioning accuracy is insufficient for fine circuit patterns
Solution Approach 1:
The photosensitive resin layer serves as a self-aligned mask that is formed directly on the circuit pattern through photolithography. This intermediary layer automatically defines the paste application areas with high precision, eliminating the need for separate screen plate positioning operations while maintaining manufacturing simplicity.
Solution Approach 2:
The patent merges the circuit pattern formation process with the paste application mask formation by using the same photosensitive resin layer for both purposes. The relief pattern of the resin layer directly defines both the circuit pattern geometry and the paste filling locations, combining multiple functions into a single integrated process.
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 method enables accurate printing of conductive paste onto fine circuit patterns, advancing the refinement of the circuit pattern and increasing the current capacity without widening the wiring, while reducing the need for high-precision positioning and specialized screen plates.
Implementation Method 1
filling the conductive paste inside the blind hole
Data Source
AI summary
The manufacturing method of the flexible printed wiring board relating to an embodiment includes a step of preparing a metal foil clad laminate 1 including an insulating substrate 2 and metal foil 3 and metal foil 4 provided on main surfaces of the substrate 2, a step of forming a circuit pattern 5 by patterning the metal foil 3, a step of forming a peelable printing plate layer 6 on the substrate 2 so as to embed the pattern 5, a step of forming blind holes 7a and 7b where the pattern 5 is exposed inside by partially removing the printing plate layer 6, a step of printing conductive paste with the printing plate layer 6 as a printing mask, and filling the conductive paste 8 inside the blind holes, and a step of peeling off the printing plate layer 6 from the metal foil clad laminate 1.