Printed Circuit Board Patterning for Dense Wiring Using Sequential Exposure
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Solution Overview
Problem
The challenge of manufacturing printed circuit boards with highly dense conductor patterns while minimizing line widths and spaces between them, without the need for high-performance exposure equipment that significantly increases manufacturing costs.
Innovation Solution
A method involving multiple exposure steps with different masks to form resist layer openings, followed by filling these openings with conductors, allowing for the creation of conductor patterns with high aspect ratios in narrow spaces using conventional exposure equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-performance exposure equipment is used to form conductor patterns with reduced line width and space, then manufacturing precision is improved, but manufacturing cost increases
Solution Approach 1:
The exposure process is divided into multiple sequential steps, where each step forms a subset of the final conductor pattern. First openings are formed and plated, then second openings are formed and plated, allowing conventional equipment to achieve the precision that would otherwise require expensive high-resolution equipment. This segmentation of the patterning process enables the use of lower-cost exposure tools while maintaining high manufacturing precision for the final dense conductor pattern layout.
2Productivity
If line width of conductor patterns is reduced and space between patterns is decreased, then wiring density is improved, but manufacturing precision requirements increase
Solution Approach 1:
The conductor pattern formation is segmented into multiple exposure and plating cycles. Instead of attempting to form all dense conductor patterns in a single exposure step that would require ultra-high resolution equipment, the process forms patterns in stages: first openings are created and filled with conductor material, then second openings are created and filled. This segmentation allows each exposure step to work within the capabilities of conventional equipment while achieving high overall wiring density in the final multi-layer conductor pattern structure.
Solution Approach 2:
The process transitions from a two-dimensional planar patterning approach to a three-dimensional multi-layer approach. By forming conductor patterns in multiple layers through sequential exposure and plating steps, the design can achieve high wiring density by utilizing vertical stacking rather than relying solely on reducing horizontal line widths. This dimensional transition allows conventional exposure equipment to produce high-density interconnect structures by exploiting the third dimension (layer stacking) rather than pushing the limits of lateral resolution.
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
Enables the formation of conductor patterns with reduced line widths and spaces, enhancing wiring density without the need for expensive high-resolution exposure tools, thus reducing production costs.
Implementation Method 1
exposing first areas of the resist layer spaced apart from each other; after exposing the first areas, exposing second areas of the resist layer
Implementation Method 2
forming a plurality of conductor patterns by filling the first and second openings with conductors
Data Source
AI summary
A method of manufacturing a printed circuit board includes: forming a resist layer; exposing first areas of the resist layer spaced apart from each other; after exposing the first areas, exposing second areas of the resist layer, the second areas being spaces between the first areas; forming first and second openings spaced apart from each other in the first and second areas by developing the resist layer; and forming a plurality of conductor patterns by filling the first and second openings with conductors.