Screen Printer Standby Control for Solder Paste Drying
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Solution Overview
Problem
Conventional screen printers require a significant holding time for the stencil to be separated from the board after solder paste filling, leading to inefficiencies in manufacturing circuit boards due to the need for viscosity integration of residual and new solder pastes, which complicates the process and reduces production efficiency.
Innovation Solution
A screen printer configuration that includes a conveyance device, board holding device, stencil holding device, squeegee device, and a control device with a standby printing processing section to raise and lower the board in synchronization with a board conveyance signal, ensuring the stencil is contacted and separated at optimal times to prevent residual solder drying and maintain efficient printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the board is separated from the stencil after a preset holding time with pattern holes filled with solder paste, then the residual solder paste integrates with new solder paste to prevent printing errors, but the print processing time is significantly reduced
Solution Approach 1:
The invention applies preliminary action by filling the pattern holes with solder paste before board separation, then maintaining this filled state during standby. The control unit keeps the squeegee device in position and prevents board conveyance, ensuring solder paste is already in the pattern holes before the next board arrives. This eliminates the need for waiting periods and viscosity integration time, as the solder paste is prepared in advance and remains stable during the standby period.
2Productivity
If the holding time is automatically calculated based on various parameters, then the print processing is optimized, but the configuration and handling become complicated
Solution Approach 1:
The invention extracts and eliminates the complex holding time calculation system from the control unit. Instead of calculating optimal holding times based on various parameters, the system simply maintains the board-stencil contact state with pattern holes filled with solder paste during standby. The control unit only needs to prevent board conveyance and keep the squeegee device in position, removing the need for complex timing calculations and parameter-based optimization algorithms.
3Reliability
If the board remains in contact with the stencil during standby, then residual solder paste does not dry and printing is improved, but the system requires precise control of board positioning
Solution Approach 1:
The invention applies self-service by using the board's own weight and the stencil's positioning structure to maintain contact during standby. The board holding device simply needs to position the board initially, and the board-stencil contact is maintained passively without requiring active control mechanisms. The control unit only needs to prevent board removal or conveyance, leveraging the existing mechanical arrangement to maintain the beneficial contact state throughout the standby period.
Data Source
AI summary
A screen printer comprising: a conveyance device configured to convey a board; a board holding device configured to position a conveyed board at a printing position; a stencil holding device configured to attach a stencil above the held board; a squeegee device configured to fill pattern holes of the stencil with solder paste; a board raising and lowering device configured to raise and lower the board positioned by the board holding device; and a control device configured to perform drive control of each the above devices, the control device including a standby printing processing section configured to raise the board from below with respect to the stencil such that the board contacts the stencil, stand by in a state with solder paste filled in the pattern holes, and lower the board to separate the board from the stencil in accordance with a board conveyance signal.