Introduction
Proper maintenance of the SMT solder paste printer is essential to extend machine lifespan, ensure stable SMT production, and guarantee product quality. This guide provides a comprehensive maintenance checklist and troubleshooting procedures for common faults.
Daily, Weekly, and Monthly Maintenance Checklist
Work Table Area
- Guide Rail: Clean and spray oil lubrication weekly; check for looseness and rust monthly.
- Ball Screw: Clean and apply grease lubrication weekly and monthly. Check for grease presence and solder paste splatter contamination; check flexible coupling for looseness or gaps.
- Belt: Check tension and wear condition weekly.
- Cable: Check cable sheathing for damage weekly.
Squeegee Area
- Lead Screw: Clean and spray oil lubrication weekly and monthly. Check for grease and solder paste contamination; check flexible coupling.
- Guide Rail: Clean and apply oil lubrication weekly.
- Belt: Check tension and wear condition weekly.
- Cable: Check cable sheathing for damage weekly.
Cleaning Device
- Cleaning Paper: Replace when depleted daily.
- Alcohol: Check fluid level and refill daily.
Vision System
- Ball Screw: Clean and spray oil lubrication monthly; apply grease once per month.
- Guide Rail: Clean and apply oil lubrication weekly.
- Cable: Check cable sheathing for damage weekly.
Stencil
- Placement Position: Ensure correct placement and secure storage on stencil rack weekly.
- Top/Bottom Surface: Check cleanliness and wear weekly.
PCB Transport
- Ball Screw: Clean and spray oil lubrication weekly and monthly (two each at entry and exit).
- Board Stop Cylinder: Check wear condition weekly.
- Stop Screw: Check wear condition weekly.
- Belt, Pulley, Bearing: Check proper tension, slipping, wear, and rotation weekly. Do not disassemble without cause.
Air Pressure System
- Pressure Gauge: Check pressure settings weekly. Printer main body: 0.45-0.5 MPa; Board upper edge clamp: 0.12-0.15 MPa; Board edge clamp: 0.06-0.22 MPa.
- Air Filter: Clean and check normal operation weekly. Check for water accumulation, dirt, clogging; replace filter element if needed.
- All Air Circuits: Check for leaks weekly.
Electrical and Control
- Computer: Check for loose boards or cards weekly.
- Electrical Connections: Check for loose or disconnected wires weekly (caution: electrical shock protection required).
- Machine Overall: Clean weekly. Prohibited: corrosive cleaning agents.
Common Faults and Repair Procedures
Fault: Solder Paste Clogging Holes
Possible causes include solder paste used too long with high viscosity, foreign material blocking stencil apertures, squeegee pressure too high, excessive stencil wiping solvent, or rough stencil aperture walls. Solutions include cleaning the stencil and replacing with fresh solder paste, adjusting squeegee pressure, turning off solvent and using dry wiping, or re-manufacturing the stencil.
Fault: Machine Freezes During Printing, Display Blank
Check for abnormal main power supply, blown 3FU fuse (replace if needed), abnormal computer host power (check switch and power supply, replace if no output), or abnormal computer motherboard or card that cannot boot (replace faulty board or card).
Fault: Cannot Auto-Clean Stencil
Inspect cleaning paper sensor, verify correct installation of cleaning paper, check cleaning sensor circuit and adjust baffle plate, re-fix or replace loose or broken guide rod fixing screws, replace broken winding shaft, inspect drive chain, and inspect drive motor and its driver card. Also check if the squeegee is raised properly by examining the air circuit and solenoid valve.
Fault: Y-Axis Vision Not Reaching Position
Enter I/O to check Y-axis vision sensor status and circuit, or adjust sensor position.
Fault: Board Stop Not in Position
Adjust rail width and check rail belt; clean or replace board stop sensor. Check for machine parameter or program errors. Adjust positioning pin and pallet fixture position. Check sensor power circuit and I/O board interface connections.
Fault: Cannot Measure Stencil Height or Squeegee Level
Clean the probe, check probe lift sensor circuit, inspect probe sensor motor drive circuit, replace driver card if needed, organize wiring if too tight, or replace damaged probe sensor motor.
Fault: Signal Not Found
Re-write PCB fiducial mark, clean camera prism surface, darken the fiducial mark or lower reception level for poor stencil fiducial contrast, inspect camera illumination circuit for poor contact, and replace burned-out illumination lamp.
Fault: Board Jam
Adjust rail width to be consistent, replace damaged rail belt, or inspect conveyor motor and driver card (ensure control card jumpers are correct and connectors are locked tight).
Fault: Irregular X-Direction Offset During Printing
Replace damaged X-axis control card, inspect or replace loose or broken X-axis coupling, or replace damaged X-axis motor.
Fault: X-Y Axis Cannot Return to Zero
Replace X-Y axis control card if faulty, inspect or replace coupling, correct and adjust deformed or misaligned limit switch sensor baffle, check limit switch status and circuit, or inspect motor circuit and replace damaged motor.
Fault: Air Pressure Drop
Check total air pressure indicator above 85 PSI and notify utilities department if insufficient, inspect main intake valve and air circuit for leaks, or check air pressure sensor status and its circuit.
Fault: Rail Hits Sensor, Software Alarm
Adjust rail width, check pallet fixture and vacuum partition fixed position, check rail sensor and its circuit, or adjust rail sensor position if loose.
