Multi-Layer Circuit Board Alignment Using Concentric-Circle Patterns
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Solution Overview
Problem
The accumulation of alignment errors during the lamination process of multi-layer circuit boards leads to significant deviations in interlayer alignment accuracy, limiting the miniaturization of conductive holes and bonding pads due to the inherent errors in photolithography and milling processes.
Innovation Solution
A manufacturing method that uses concentric-circle patterns as alignment targets, forming through holes using CO2 laser drilling or direct laser drilling, and utilizing these patterns across subsequent layers to maintain alignment accuracy, allowing for the separation of core layers to form individual multi-layer circuit boards and reduce error accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography process is used to form alignment targets in previous stacking layer, then alignment targets can be formed, but alignment errors are introduced that accumulate with each layer
Solution Approach 1:
The patent divides the multi-layer circuit board manufacturing into independent pairs of layers, where each pair is processed separately with its own alignment reference. This segmentation prevents error accumulation across all layers by resetting the alignment reference for each pair, thereby maintaining consistent alignment accuracy without compounding errors from previous layers.
Solution Approach 2:
The patent performs preliminary formation of alignment references (conductive holes and bonding pads) on the bottom layer before adding subsequent layers. This preliminary action establishes a stable, pre-defined alignment基准 that prevents error propagation, as the alignment reference is created once with high precision and then used consistently for all subsequent layer alignments in that pair.
2Productivity
If number of circuit layers is increased to improve integration, then more electronic components can be mounted, but accumulated alignment errors increase causing large deviation
Solution Approach 1:
The patent segments the multi-layer structure into multiple pairs of layers, where each pair maintains independent alignment references. This allows the circuit board to achieve high integration through multiple layers while preventing error accumulation by resetting alignment baselines for each pair, thus maintaining precision despite increased layer count and integration capability.
3Ease of manufacture
If conventional lamination process is used, then manufacturing process is established, but alignment error accumulation limits miniaturization of conductive holes and bonding pads
Solution Approach 1:
The patent modifies the conventional lamination process by segmenting it into independent processing stages for different layer pairs. Each stage uses its own alignment references formed through photolithography, allowing the use of standard manufacturing processes while preventing error accumulation that would otherwise limit miniaturization. This segmentation enables smaller conductive holes and bonding pads by maintaining consistent alignment accuracy.
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 achieves improved interlayer alignment accuracy, enabling the miniaturization of conductive holes and bonding pads, with single-side alignment accuracy up to less than 50 μm, and increases wiring density and circuit layer capability by reducing alignment errors and layer deviations.
Implementation Method 1
forming through holes using CO2 laser drilling or direct laser drilling
Data Source
AI summary
A manufacturing method for a multi-layer circuit board includes the following steps. Firstly, two core layers are compressed to form a substrate having two surfaces opposite to each other. Then, a via connecting the surfaces is formed. A patterned circuit layer including a concentric-circle pattern is then formed on each surface by using the via as an alignment target. Next, a first stacking layer is formed on each surface. Then, a first through hole penetrating regions of the first stacking layer and the substrate where a first concentric circle from the center of the concentric-circle pattern is orthogonally projected thereon is formed. A second stacking layer is then formed on each first stacking layer. Afterward, a second through hole penetrating regions of the first, the second stacking layers and the substrate where a second concentric circle from the center of the concentric-circle pattern is orthogonally projected thereon is formed.