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Views: 0 Author: Site Editor Publish Time: 2025-09-25 Origin: Site
SMT (Surface Mount Technology) is a widely used technology in the modern electronics assembly industry. SMT equipment primarily includes glue dispensers, printers, pick and place machines, reflow soldering ovens, and automatic inspection machines. Proper use and maintenance of these devices are crucial to ensure product quality and improve production efficiency.
Worktable: Made of cast aluminum, ensuring a high flatness to ensure effective working area for screen printing.
Template Fixture: Used to secure the metal template, keeping the template and worktable on the same horizontal plane.
Operating Steps: Secure the template face up on the fixture, adjust the relative position between the worktable and the template for precise alignment, scoop solder paste using a clean spoon or spatula, apply it on one side of the squeegee blade at a 60-degree angle, and scrape slowly while lifting the template smoothly without shaking it.
Notes: Solder paste should not be frozen for more than 10 hours; storage temperature should be between 0-10°C. Too low pressure can cause omissions and rough edges, while too high pressure may damage the squeegee and template.
Positioning: Ensure that the MARK marks and positioning holes on the FPC (Flexible Printed Circuit) match the positioning pins of the pick and place machine.
Tray: Use high-quality FR-4 material or other premium materials, approximately 2mm thick, ensuring thermal stability.
Securing: Fix the FPC on the tray with thin high-temperature tape to ensure it does not shift.
Operating Steps: Cover the positioning pins with the tray, place the FPC on the exposed pins, secure it with high-temperature tape, and separate the tray and FPC positioning template for solder paste printing and assembly.
Notes: The FPC should be secured to the tray for as short a time as possible to avoid warpage due to moisture. Ensure moderate adhesion of the tape, which should easily peel off without leaving residue after exposure to high temperatures.
Recommended Type: Use forced hot air convection infrared reflow soldering ovens to ensure uniform temperature changes on the FPC.
Operating Steps: Set suitable reflow soldering temperatures and times based on different trays and component types, place the secured FPC in the oven, and start the soldering program.
Notes: Excessive temperature or duration may damage components; too low temperature or short time may lead to poor soldering. Record temperature and time for each soldering session for future reference and optimization.
Hardware Design: Uses four-phase mixed stepper motors to control X and Y direction movements, implementing control with GAL 16V8 programmable logic devices and AT 89C55 microcontrollers, utilizing two seven-channel Darlington driver arrays NM1413 to drive stepper motors, and using MAX 813L watchdog/reset chips to protect data from interference.
Software Design: Utilizes ABEL language and Lattice Semiconductor’s logic programmer for programming, employing software traps with guiding instructions to prevent program malfunctions.
Operating Steps: Place the PCB to be tested into the inspection machine, start the detection program, record results after testing, and perform rework if necessary.
Notes: Regularly maintain inspection equipment to ensure normal operation, and keep the environment clean during the inspection to avoid dust and impurities affecting results.
Baking Conditions: Temperature: 100-120°C, Time: 4-8 hours, Supplementary Baking: 1-21 hours.
Notes: After baking, vacuum seal packaging or place in a drying cabinet. Maintain a distance of 5mm between every spice tray, stack height should not exceed 10 layers, and maintain spacing between materials in each layer. Ensure the oven is well grounded, and personnel wear anti-static wristbands.
Some materials, like FR-4 and certain batteries/electrolytic capacitors, cannot withstand prolonged high-temperature baking.
Low Humidity Drying: Conditions: Dry in a drying box with humidity ≤ 10%RH for 5 times the exposure time. No limit on the number of low humidity drying sessions but ensure proper marking on the material tray. The tray must not touch the walls or bottom of the oven or dehumidifying cabinet where temperatures are high.
Single-Sided SMT Component Assembly: The process includes printing solder paste on the top side → SMT component placement → reflow soldering → TH (through-hole) component insertion → wave soldering.
Features: The top side is not subjected to any soldering processes, ensuring a smooth PCB for improved soldering accuracy. The bottom-side wave soldering does not affect SMT components, and larger component footprints are suitable for SMT packages with pin spacing larger than 0.3mm.
Mixed Assembly of Double-Sided SMT Components and Single-Sided TH Components: The process includes printing solder paste on the top side → SMT component placement → reflow soldering → flipping the board → applying glue on the bottom side → SMT component placement → drying → TH component insertion on the top side → wave soldering.
Features: Fine-pitched SMT component layout on the top side with controlled solder paste application; wide-pitched SMT components on the bottom side like resistors, capacitors, diodes, and transistors. Wave soldering can simultaneously complete soldering of bottom SMT components and TH components, optimizing space with two soldering processes.
Mixed Assembly of Single-Sided SMT Components and Double-Sided TH Components: The process includes printing solder paste on the top side → SMT component placement → reflow soldering → TH component insertion on the top side → wave soldering → manual supplementary soldering for bottom TH components.
Features: TH components are arranged on both sides of the PCB, mixed with SMT components. Top SMT components are soldered through reflow, while bottom TH components are soldered by wave soldering and manual supplementary soldering, efficiently utilizing space in two soldering processes.
Regular Inspection: Periodic checks and maintenance on equipment to ensure normal operation.
Cleaning and Maintenance: Keep equipment clean; regularly remove dust and debris.
Part Replacement: Timely replacement of worn or damaged parts to ensure precision and reliability of equipment.
Training Operators: Regular training for operators to improve their skills and safety awareness.
Electrostatic Discharge Prevention: Operators should wear anti-static wristbands to avoid damage to components from static electricity.
Temperature Control: Strictly control baking and soldering temperatures to prevent overheating damage to components.
Operating Environment: Maintain a clean and dry operating environment to avoid dust and moisture affecting production.
Emergency Handling: In case of equipment malfunction, stop immediately and inform maintenance personnel for handling.
Equipment Check: Ensure all equipment is in good condition, with no damage or wear.
Material Preparation: Prepare required materials such as PCB boards, solder paste, SMT components, and TH components.
Environment Preparation: Keep the operating environment clean and dry, with temperature and humidity meeting requirements.
Fix Template: Secure the metal template face up on the template fixture of the screen printer.
Alignment: Adjust the relative position between the worktable and the template to ensure accurate alignment of the PCB pads and the template.
Printing: Scoop solder paste using a clean spoon or spatula, apply it on one side of the squeegee blade, maintaining a 60-degree angle, and scrape uniformly and slowly. Lift the template smoothly to avoid any lateral movement that could smear the solder paste.
Storage: Place the printed PCB boards in a safe position awaiting component placement to prevent accidental damage.
Positioning: Determine positioning data based on the FPC’s CAD data to create high-precision FPC positioning templates.
Securing: Secure the FPC on the tray using thin high-temperature tape to avoid any displacement.
Placement: Cover the positioning pins with the tray, secure the FPC on the exposed pins using tape, and separate the tray from the FPC positioning template for solder paste printing and assembly.
Notes: The FPC should remain on the tray for as short a time as possible to prevent warping due to moisture.
Temperature Setting: Set appropriate reflow soldering temperature and time according to different trays and component types.
Soldering: Place the secured FPC into the reflow soldering oven and start the soldering program while monitoring the operation to ensure temperature and timing requirements are met.
Recording: Maintain detailed records of temperature and time for each soldering cycle for future reference and optimization.
Place PCB: Insert the PCB to be inspected into the inspection machine, ensuring correct placement.
Start Inspection: Initiate the detection program for automated inspection.
Record Results: Document inspection outcomes and conduct rework as necessary.
Maintenance: Regularly maintain the inspection equipment to ensure proper functioning.
Conditions: 100-120°C for 4-8 hours.
Supplementary Baking: 1-21 hours.
Notes: Vacuum seal packaging or place in a drying cabinet post-baking. Maintain a 5mm gap between spice trays, and avoid exceeding ten layers per stack. Ensure effective grounding of the oven and that personnel use anti-static wristbands while handling materials. Some materials like FR-4 and certain batteries/capacitors cannot endure prolonged high-temperature baking.
Conditions: Dry in a drying box with humidity ≤ 10%RH for a period equivalent to five times the exposure time.
Notes: There are no limits on low humidity drying occurrences, but ensure proper labeling on trays. Avoid touching the upper and lower surfaces of the oven or drying cabinets to prevent heat exposure.
Process: Print solder paste on PCB top ↔ SMT component placement ↔ reflow soldering ↔ Insert TH components on top ↔ Wave soldering.
Features: No soldering processes on the top; a smooth board aids soldering accuracy. Wave soldering on the bottom does not affect SMT components.
Process: Print solder paste on PCB top ↔ SMT placement on top ↔ Reflow soldering ↔ Flip board ↔ Glue application on bottom ↔ SMT placement on bottom ↔ Drying ↔ Insert TH components on top ↔ Wave soldering.
Features: Precise control of solder paste for fine-pitch SMT components on top side, while wider pitch components (resistors, capacitors, etc.) lie on the bottom. Wave soldering completes bottom SMT and TH component soldering simultaneously, utilizing space efficiently.
Process: Print solder paste on PCB top ↔ SMT placement on top ↔ Reflow soldering ↔ Insert TH components on top ↔ Wave soldering ↔ Manual supplementary soldering for bottom TH components.
Features: TH components are on both sides, mixed with SMT components. Top SMT is soldered through reflow, while bottom components are soldered with wave and manual techniques for effective space usage.
Regular Inspections: Routine checks to ensure machinery operates effectively.
Cleaning and Maintenance: Regular cleaning of equipment to eliminate dust and debris.
Part Replacement: Timely replacement of worn or broken components to maintain device accuracy and reliability.
Operator Training: Regular training sessions to enhance operator skills and safety standards.
Electrostatic Measures: Operators should wear anti-static wristbands to prevent electrostatic damage to components.
Temperature Management: Strict regulation of baking and soldering temperatures to prevent overheating.
Working Environment: Maintain cleanliness and dryness in the operating environment, ensuring temperature and humidity are within acceptable ranges.
Emergency Procedures: Equipment should be shut down immediately upon failure, with maintenance personnel notified for resolution.
By adhering to these operating specifications and guidelines, smooth SMT production processes can be ensured, improving product quality and production efficiency.
