Multi-Focus Interleaved Writing for Uneven PCB Patterning
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Solution Overview
Problem
Current exposure systems struggle to meet stringent resolution requirements while providing a large depth of focus, especially when dealing with embedded substrates that have uneven surfaces, as the topography exceeds the optical depth of focus, leading to difficulties in maintaining focus and achieving high-resolution patterning across varying surface heights.
Innovation Solution
The technology employs a multi-focus interleaved writing method using at least two writing beams with different focal planes, interlacing exposures to achieve an extended effective depth of focus, allowing for high-resolution patterning on substrates with varying surface heights by adjusting the focal depth and exposure dose during a single pass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single focal plane is used for exposure, then the system maintains simple optical configuration, but it cannot accommodate uneven substrate surfaces with large topography steps
Solution Approach 1:
The optical system is segmented into multiple independent writing beams, each with its own focal plane. This allows the system to handle different surface heights simultaneously by assigning each beam to a specific focal depth, thereby accommodating uneven substrate surfaces without requiring a completely complex optical redesign.
Solution Approach 2:
The patent introduces the depth dimension by implementing multiple focal planes along the optical axis. Instead of trying to adjust a single beam to cover varying heights, the system adds multiple beams at different focal depths, effectively using the z-dimension to solve the topography problem.
2Manufacturing precision
If multiple writing beams with different focal planes are used, then the depth of focus is extended, but the device complexity increases
Solution Approach 1:
The patterning process is segmented into multiple independent writing beams that operate in parallel. Each beam is responsible for a specific focal plane, allowing precise patterning at different surface heights. This segmentation enables the system to maintain high manufacturing precision across uneven surfaces while managing complexity through modular beam control.
Solution Approach 2:
The system changes the focal plane parameter for each writing beam to match different surface heights. By dynamically adjusting the focal depth parameter of each beam, the system achieves precise patterning across varying topography without requiring physical reconfiguration of the entire optical system.
3Manufacturing precision
If the substrate surface is uneven with embedded devices, then the topography exceeds optical depth of focus, but using conventional single-focus systems results in loss of resolution
Solution Approach 1:
The exposure process is segmented into multiple focal plane exposures, with each writing beam dedicated to a specific depth range. This ensures that each beam operates within its optimal focus range, maintaining high resolution even when the overall substrate topography exceeds the depth of focus of any single beam.
Solution Approach 2:
The patent solves the resolution loss problem by transitioning from a single-plane exposure to a multi-plane exposure approach. By distributing the patterning task across multiple focal planes, the system maintains optimal focus and resolution at each plane while collectively covering the entire uneven substrate surface.
4Manufacturing precision
If interleaved writing passes are used to extend depth of focus, then the effective depth of focus increases, but the writing process complexity increases
Solution Approach 1:
The writing process employs periodic alternation between different focal plane exposures. Writing beams are activated in a periodic sequence, with each beam handling specific passes while others remain inactive. This periodic action pattern simplifies the control logic compared to continuous multi-beam operation, as the system can reuse the same beams in alternating cycles.
Solution Approach 2:
The writing process is segmented into alternating passes handled by different beams. Instead of requiring all beams to operate simultaneously with complex coordination, the system divides the writing task into sequential segments where each beam handles specific passes, reducing control complexity while achieving extended depth of focus.
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 enables high-complexity single-pass writing on uneven substrates with improved resolution and depth of focus, effectively handling large topography steps and averaging out irregularities across the scanning width, thereby enhancing patterning precision and stability.
Implementation Method 1
one or more laser sources configured to generate at least first and second writing beams
Implementation Method 2
one or more optics adapted to project the first and second writing beams onto the uneven workpiece with first and second focal planes of the respective writing beams
Implementation Method 3
exposing the uneven workpiece in interlaced writing passes using at least first and second writing beams
Data Source
AI summary
The technology disclosed relates to accommodating embedded substrates during direct writing onto a printed circuit board and to other patterning problems that benefit from an extended depth of focus. In particular, it relates to multi-focus direct writing of a workpiece by the continuous or step-wise movement of the workpiece during the sequence of exposures having different focus planes. In one implementation, a multi-arm rotating direct writer is configured for interleaved writing focused on two or more focal planes that generally correspond to two or more surface heights of a radiation sensitive layer that overlays the uneven workpiece. Alternating arms can produce interleaved writing to the two or more focal planes.