Double-Sided Maskless Exposure System Alignment
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Solution Overview
Problem
Current double-sided maskless exposure systems face challenges in maintaining accurate alignment of optical engines due to environmental factors like vibration and temperature changes, leading to reduced productivity and yield in high-density interconnection PCB manufacturing.
Innovation Solution
A double-sided maskless exposure system incorporating a UV light source, spatial light modulator, optical systems, motion control, and a vision system with auto-calibration capabilities, using beam splitters and separate wavelength light sources for alignment and exposure, ensures precise alignment and efficient exposure on both sides of a substrate without the need for physical masks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional film mask lithography is used, then cost is low, but manufacturing precision and productivity are limited due to film deformation and alignment accuracy issues
Solution Approach 1:
The patent uses a digital maskless lithography system that projects patterns directly onto the substrate using a spatial light modulator (SLM), eliminating the need for physical film masks. This digital copying approach replaces the physical mask with a programmable optical system, achieving high alignment accuracy while reducing the complexity of mask storage and management.
Solution Approach 2:
The invention replaces the mechanical film mask system with an optical projection system using a spatial light modulator. This substitution eliminates mechanical film deformation and alignment issues, improving manufacturing precision while the automated optical control reduces overall system complexity.
2Productivity
If maskless lithography is adopted, then productivity and yield are improved, but alignment stability deteriorates due to vibration and temperature changes affecting optical engine alignment
Solution Approach 1:
The patent incorporates a feedback mechanism using a camera system to monitor and detect the positions of alignment marks on the substrate. The system continuously measures the actual positions of optical engines relative to the substrate and automatically adjusts or corrects the alignment data, compensating for vibrations and temperature changes to maintain reliable alignment stability during high-speed exposure.
Solution Approach 2:
The system performs preliminary alignment measurement and data correction before the actual exposure process. By pre-calibrating the optical engine positions and storing corrected alignment data, the system ensures stable and accurate patterning throughout the high-speed exposure run, preventing alignment drift caused by environmental factors.
3Productivity
If single-sided maskless exposure is used, then device complexity is reduced, but productivity decreases due to requiring multiple exposure passes for double-sided PCB
Solution Approach 1:
The patent divides the exposure system into two independent but coordinated optical engines, one for each side of the substrate. Each optical engine can operate independently with its own spatial light modulator and alignment system, allowing simultaneous double-sided exposure. This segmentation enables parallel processing of both sides of the PCB, doubling throughput while keeping each individual optical engine manageable in complexity.
Solution Approach 2:
The invention merges two separate single-sided maskless exposure systems into a unified double-sided exposure platform. By combining the functionality of two optical engines to work on opposite sides of the substrate simultaneously, the system achieves doubled productivity. The shared substrate stage and coordinated control system integrate the two sides into a single operational unit.
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
The system enhances productivity and quality by eliminating alignment issues, enabling high-yield, high-speed exposure with improved scaling and distortion compensation, suitable for high-density interconnection PCBs and other applications.
Implementation Method 1
spatial light modulator (SLM), such as DMD, LCOS, LCD and other 2D display panels
Implementation Method 2
UV light source... exposing both sides of a subject plate... with photo sensitive material on both sides for exposure
Implementation Method 3
beam splitters and separate wavelength light sources for alignment and exposure
Implementation Method 4
vision system with auto-calibration capabilities... alignment pattern... read the alignment position
Data Source
AI summary
A double-sided maskless exposure system and method consists of light sources which includes two light wavelength segments, maskless optical engines in which a 2D spatial light modulation (spatial light modulator) device, such as DMD, is generating a plurality of pixel array of the pattern, vision system, moving substrate and computer control system. The double-sided maskless exposure system at least includes two maskless optical engines with auto-calibration function which can correct any alignment error in-line. Each optical engine is for each side of the substrate. The optical engines are aligned each other in pairs and are simultaneously patterning on each side of the moving substrate. The system also includes a manipulator for moving, stepping or scanning the optical engines, relative to the substrate so that it can create a contiguous whole image on the both sides of the subject.