PCB Solder Printing Control for Cleaning-Cycle Uniformity
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Solution Overview
Problem
Existing solder printing apparatuses face challenges in achieving uniformity of solder paste on printed circuit boards, which affects the reliability of semiconductor chip connections, due to variations in printing parameters and cleaning cycles.
Innovation Solution
A solder printing apparatus with a control unit that adjusts printing parameters based on a cleaning cycle count, classifying printed circuit boards into groups and setting specific parameters for each group to ensure consistent solder paste distribution and cleaning, thereby enhancing uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If solder paste is printed using a fixed printing parameter for all printed circuit boards, then the printing process is simple and fast, but the uniformity of solder paste volume varies due to cleaning cycle effects
Solution Approach 1:
The patent applies dynamics by making the printing parameter adjustable and variable based on the cleaning cycle count. The control unit dynamically selects different printing parameters (such as squeegee pressure, speed, or number of passes) depending on whether the solder mask has been cleaned and how many cleaning cycles have occurred. This dynamic adjustment compensates for the varying adhesion characteristics of solder paste to the solder mask surface at different cleaning stages, thereby maintaining uniform solder paste volume across all printed circuit boards regardless of cleaning status.
2Manufacturing precision
If the solder mask is cleaned after every printing cycle, then the solder paste adhesion is consistent, but the production efficiency decreases due to frequent cleaning
Solution Approach 1:
The patent implements periodic action by establishing a predetermined cleaning cycle count (e.g., clean every 5th printed circuit board) rather than cleaning after every single printing cycle. The control unit tracks the cleaning cycle count and only triggers the cleaning unit when this count reaches the predetermined value. This periodic cleaning approach maintains sufficient solder paste adhesion consistency while significantly reducing the frequency of cleaning operations, thereby preserving production efficiency.
Solution Approach 2:
The patent applies parameter changes by adjusting the printing parameter based on the cleaning cycle count to compensate for reduced cleaning frequency. When the solder mask has not been cleaned for multiple cycles, the control unit modifies printing parameters (such as increasing squeegee pressure or number of printing passes) to ensure that solder paste adhesion and volume uniformity remain within acceptable ranges, thus maintaining manufacturing precision without frequent cleaning.
3Manufacturing precision
If different printing parameters are applied to different printed circuit board groups, then the solder paste uniformity is improved, but the control complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the sequence of printed circuit boards into groups based on the cleaning cycle count. The control unit classifies printed circuit boards into different groups (e.g., those printed before cleaning, those printed after 1st cleaning, after 2nd cleaning, etc.) and assigns specific printing parameters to each group. This segmentation approach systematically manages the complexity by creating discrete, manageable categories rather than requiring continuous real-time adjustment for each individual board.
Solution Approach 2:
The patent implements feedback by using the cleaning cycle count as a feedback signal to determine the appropriate printing parameter. The control unit continuously monitors the cleaning cycle count and uses this information to automatically select and apply the correct printing parameter for the current group of printed circuit boards. This feedback mechanism simplifies control complexity by establishing a clear, rule-based relationship between cleaning status and printing parameters, eliminating the need for complex real-time analysis.
Data Source
AI summary
A solder printing apparatus including a printed circuit board feeding unit configured to sequentially feed a plurality of printed circuit boards, a solder paste printing unit configured to locate a solder mask on each of the printed circuit boards fed by the printed circuit board feeding unit and print solder paste on each of the printed circuit boards through an opening of the solder mask, a solder mask cleaning unit configured to clean residual solder from the solder mask after the solder paste is printed by the solder paste printing unit, and a control unit configured to control the solder paste printing unit and the solder mask cleaning unit, wherein the control unit is further configured to differently set a printing parameter of the solder paste printing unit for each of the printed circuit boards according to a cleaning cycle count set for the solder mask may be provided.