Stencil Mask Position Correction via SPI Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The reliability of the screen printing process is compromised due to position errors in the stencil mask, caused by misalignment or coordinate mismatches between the stencil mask, camera, and board, which affects the accuracy of solder formation on printed circuit boards.
Innovation Solution
A method is implemented where a solder paste inspection apparatus receives fiducial information from the screen printer, estimates and transmits x, y offset values and rotating amounts of the stencil mask to correct its position, using error minimization formulas and weight-based reliability calculations, and divides the board into blocks for more precise corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a stencil mask is used in screen printing, then solder can be formed on the board, but position errors occur due to misalignment or coordinate mismatches
Solution Approach 1:
The patent implements a feedback mechanism where the SPI apparatus measures the actual solder positions and communicates offset information back to the screen printer. This closed-loop feedback system allows the screen printer to correct its positioning based on actual measurement data, resolving the contradiction between achieving precise solder formation and maintaining mounting reliability despite stencil mask alignment issues.
Solution Approach 2:
The patent replaces reliance on mechanical alignment precision with an optical measurement and computational correction system. Instead of depending solely on precise mechanical positioning of the stencil mask, the system uses optical measurement (SPI) and coordinate transformation algorithms to compensate for mechanical errors, substituting mechanical precision requirements with computational correction.
2Manufacturing precision
If coordinate correction is applied to compensate for misalignment, then position accuracy can be improved, but complexity of the printing system increases
Solution Approach 1:
The patent introduces an intermediary coordinate transformation system that bridges the screen printer's coordinate system and the actual board coordinate system. This intermediary layer performs mathematical coordinate conversions based on fiducial mark measurements, allowing accurate positioning without requiring direct mechanical precision or complex hardware modifications to the existing printing system.
Solution Approach 2:
The patent creates a virtual model of the board and solder positions through coordinate transformation, copying the physical positioning problem into a computational domain. By working with coordinate data and transformation matrices rather than directly manipulating physical alignment, the system achieves precision while keeping hardware complexity manageable.
3Measurement precision
If inspection is performed after printing, then solder quality can be verified, but time for the manufacturing process increases
Solution Approach 1:
The patent implements rapid feedback measurement using SPI technology that provides quick assessment of solder positions. The system captures images and calculates offset values in real-time, enabling fast verification that minimizes the time added to the manufacturing cycle while maintaining high measurement precision for quality control.
Data Source
AI summary
The present invention relates to a method of correcting a position of a stencil mask which comprises receiving fiducial information from a screen printer, extracting position information of a pad and position information of a solder formed on a board through measuring by a solder paste inspection apparatus, estimating an x, y offset value and a rotating amount of a stencil mask based on the fiducial information by using the position information of the pad and the solder, and transmitting the x,y offset value and the rotating amount of the stencil mask to the screen printer. Thus, a reliability of solder forming process may be increased by correcting a stencil mask position by transmitting a feedback of an x,y offset value and a rotating amount of the stencil mask from a solder paste inspection apparatus, in which the x,y offset value and the rotating amount are estimated based on fiducial information transmitted from the screen printer.