Multi Dispense Head Alignment via Image Processing
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Solution Overview
Problem
Variability in the additive manufacturing process of droplet ejecting systems for chemical mechanical polishing (CMP) pads leads to misalignment of droplets, affecting the quality and repeatability of polishing pads.
Innovation Solution
A method for aligning multiple dispense heads involves forming an alignment test pattern with droplets, comparing their placement to determine offset distances, and generating timing offsets to control the dispensing process, ensuring precise droplet placement in subsequent manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If droplet ejecting dispense heads are used for additive manufacturing of polishing pads, then controlled placement of different compositions and increased control of feature sizes, shapes, and positioning is enabled, but variability in the additive manufacturing process causes differences between actual and desired droplet placement
Solution Approach 1:
The system performs preliminary alignment by dispensing test droplets from each dispense head to a test substrate, capturing images of the droplet positions, and calculating timing offsets before actual production. This preliminary calibration action ensures that subsequent manufacturing operations start with properly synchronized dispense heads, resolving the contradiction between precision and repeatability.
Solution Approach 2:
The system implements feedback by capturing images of dispensed droplets, comparing actual droplet positions to desired positions, and using the measured offsets to adjust the timing of droplet ejection from each dispense head. This closed-loop feedback mechanism continuously corrects placement variations, maintaining both precision and repeatability across manufacturing operations.
2Adaptability or versatility
If multiple dispense heads are used to dispense different compositions, then complex polishing pad features can be created, but misalignment between dispense heads affects quality and repeatability
Solution Approach 1:
The system segments the alignment calibration process by independently calibrating each dispense head separately. Each dispense head dispenses test droplets that are imaged and measured independently, allowing individual timing offsets to be calculated and applied to each head. This segmentation enables complex multi-head operations while maintaining precise alignment between all heads.
3Manufacturing precision
If timing offsets are generated to correct droplet placement, then accurate droplet placement is achieved, but additional calibration steps are required
Solution Approach 1:
The system performs self-calibration by automatically dispensing test droplets, capturing images of the droplet positions, calculating the timing offsets, and applying the corrections without requiring manual intervention. This self-service approach reduces the perceived complexity for the operator while achieving high precision through automated calibration.
Solution Approach 2:
The system creates a digital copy or model of the actual droplet positions by capturing images and comparing them to the desired pattern. This digital representation allows for precise calculation of timing offsets without physical adjustment mechanisms, simplifying the calibration process while maintaining high accuracy.
Data Source
AI summary
Embodiments of the present disclosure generally relate to droplet ejecting additive manufacturing systems used in the manufacturing of advanced polishing articles. In particular, embodiments herein provide methods for aligning a plurality of dispense heads of the additive manufacturing system. In one embodiment, a method for aligning a plurality of dispense heads of an additive manufacturing system includes forming an alignment test pattern comprising droplets dispensed from each of the plurality of dispense heads, comparing the placement of one or more of the droplets to determine offset distances therebetween, and generating one or more timing offsets based on the offset distances. In some embodiments, the method further includes using the timing offsets to control the dispensing of droplets from one or more of the plurality of dispense heads in a subsequent additive manufacturing process.