Printed Wiring Board Plating and Etch Process
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Solution Overview
Problem
The fabrication of printed wiring boards (PWBs) with multiple plating operations and fine line etch requirements is challenging due to the interdependence between etch accuracy and plating thickness, leading to yield and reliability issues, labor intensity, and wastage of PWBs.
Innovation Solution
A process that separates critical and non-critical portions of the PWB, allowing for precise etching and plating in critical areas while relaxing tolerances in non-critical areas, using multiple photo masks and reducing the need for sanding and planarization steps, enabling the fabrication of PWBs with fine line etch and space requirements and multiple plating steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sanding is used to control final top layer plating thickness, then plating thickness can be controlled, but yield and reliability decrease and labor intensity increases
Solution Approach 1:
The patent applies preliminary protection by coating certain areas with a protective layer before plating. This prevents plating material from depositing in areas where it is not desired, eliminating the need for post-plating sanding operations. The protective coating is applied in advance, allowing precise control of plating thickness without subsequent mechanical removal that could compromise reliability.
Solution Approach 2:
The patent extracts the problematic sanding operation from the manufacturing process by using selective protective coatings. Instead of applying plating uniformly and then removing excess material through sanding, the solution removes the need for sanding entirely by preventing plating in unwanted areas through the protective coating layer.
2Manufacturing precision
If sanding is used to control final top layer plating thickness, then plating thickness can be controlled, but labor intensity increases
Solution Approach 1:
The protective coating is applied in advance before plating operations, establishing precise boundaries for where plating should occur. This preliminary action eliminates the need for labor-intensive sanding operations after plating, significantly reducing manual intervention and increasing production efficiency.
Solution Approach 2:
The patent removes the sanding step from the manufacturing process entirely by using protective coatings to define plating areas. This extraction of the sanding operation eliminates the associated labor intensity and productivity issues while maintaining precise plating thickness control.
3Manufacturing precision
If tight etch accuracy is required for fine lines, then conductor dimensions are precise, but fabrication difficulty increases when multiple plating steps are needed
Solution Approach 1:
The patent segments the PWB into different zones with different plating requirements. Critical areas requiring fine etch accuracy are protected from plating, allowing tight tolerance etching to be performed first. Non-critical areas can then receive plating without affecting the precision of the fine conductor lines. This segmentation allows both tight etch accuracy and multiple plating steps coexist.
Solution Approach 2:
The patent applies different treatments to different areas of the PWB. Critical areas with fine conductor lines receive protective coating to prevent plating, ensuring tight etch accuracy is maintained. Non-critical areas without fine lines can undergo normal plating operations. This local differentiation resolves the conflict between etch accuracy requirements and multiple plating needs.
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 enhances the yield and reliability of PWBs by allowing for accurate etching and plating in critical areas while reducing waste and labor costs, enabling the production of PWBs with complex filter structures like RF edge-coupled filters.
Implementation Method 1
completing all plating steps
Implementation Method 2
etching a first conductor in the first portion of the printed wiring board
Data Source
AI summary
A process for manufacturing a printed wiring board includes specifying overlapping etches for a first portion of the printed wiring board and a second portion of the printed wiring board, the first portion of the printed wiring board having disposed thereon a printed circuit having at least one dimension critical to printed wiring board operation, etching a first conductor in the first portion of the printed wiring board when a first conductor thickness is a predetermined thickness, completing all plating steps, and etching a second conductor in the second portion of the printed wiring board.