Mask Printing Machine Through Hole Alignment via Optical Imaging
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Solution Overview
Problem
Existing mask printing machines face challenges in accurately aligning through holes on a mask with printing portions on a circuit board due to mechanical errors and changes in the lifting and lowering device, leading to decreased printing accuracy when the board is lifted from a separated to a contact position.
Innovation Solution
The mask printing machine uses imaging devices to capture the movement state of target through holes at both separated and contact positions, acquiring a movement state-based correction value to align the board and mask accurately, combining this with reference mark-based correction values for precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the board is lifted from separated position to contact position using mechanical lifting device, then the board can be positioned for printing, but mechanical errors cause positional deviation between board and mask
Solution Approach 1:
The patent replaces mechanical positioning methods with optical imaging methods. Instead of relying on the mechanical lifting device to maintain precise positioning, the system uses imaging devices to capture images of through holes at different positions (separated and contact) and calculates actual displacement optically. This substitution of mechanical measurement with optical measurement resolves the contradiction by eliminating dependence on mechanical precision.
Solution Approach 2:
The patent implements a feedback mechanism where the actual displacement of through holes is measured using imaging devices, and this measured displacement is fed back to correct the positioning. The system acquires images at separated position and contact position, calculates the displacement, and uses this information to compensate for positioning errors, thereby maintaining high alignment precision despite mechanical variations.
2Measurement precision
If imaging devices are used to capture through hole positions at separated and contact positions, then movement state can be acquired, but device complexity increases
Solution Approach 1:
The imaging devices in the patent serve multiple functions: they capture images of through holes at separated position, capture images at contact position, and enable calculation of displacement. By making the imaging system multi-functional, the patent reduces the need for additional specialized devices, thereby limiting the increase in device complexity while achieving precise measurement.
Solution Approach 2:
The patent uses the through holes themselves as intermediaries for measurement. Instead of requiring complex direct measurement devices, the system images the through holes (which are already present on the mask) at different positions and uses their apparent movement to infer displacement. This intermediary approach simplifies the measurement system compared to direct mechanical measurement methods.
Data Source
AI summary
In a mask printing machine, a target through hole, which is at least one of multiple through holes formed on the mask, is imaged by an imaging device when the board is below the mask and is at a separated position that is separated from the mask, and when the board is at a contact position in which an upper surface of the board contacts a lower surface of the mask, respectively. Based on a captured image, when the board is at the separated position, and a captured image when the board is at the contact position, it is possible to acquire the movement state of at least one target through hole when the board is lifted from the separated position to the contact position.