Analysis of the entire process of SMT patch processing production line: key equipment and technical highlights

SMT (Surface Mount Technology) is the core process of modern electronic manufacturing, and its production line is known for its high precision and high efficiency. A complete SMT patch processing production line needs to be configured with the following equipment according to the process to coordinate the production from PCB substrate to finished product.

1. Fully automatic board loader (PCB Loader)

Functional features:

- Responsible for automatically feeding the stacked PCB substrates into the production line to ensure continuous feeding.

- Use sensors to identify the PCB position to avoid stuck boards or empty board transmission.

Working principle:

Grab the PCB through a vacuum nozzle or a robotic arm, and accurately position it to the next process with the conveyor belt.

2. Solder Paste Printer

Functional Features:

- Core equipment for uniformly coating solder paste on PCB pads.

- High-precision visual alignment system (CCD camera) ensures ±0.01mm printing accuracy.

Working Principle:

After the stencil is aligned with the PCB, the scraper pushes the solder paste through the stencil opening with constant pressure to form an accurate solder paste pattern.

3. Solder Paste Inspector (SPI)

Functional Features:

- 3D laser scanning technology detects solder paste thickness, volume and coverage uniformity.

- Real-time feedback data to prevent welding defects (such as insufficient solder and bridges).

Working Principle:

Generate a three-dimensional image through multi-angle laser projection, and compare the preset parameters to judge the printing quality.

4. High-Speed Pick-and-Place Machine

Functional Features:

- Core mounting equipment, divided into "high-speed machine" and "multi-function machine":

- High-speed machine: Mount small components such as resistors and capacitors, with a speed of 60,000 CPH (pieces/hour).

- Multi-function machine: Process special-shaped components such as QFP and BGA, with an accuracy of ±0.025mm.

Working Principle:

The nozzle picks up the component from the feeder, and mounts it to the PCB after the position is corrected by the visual system.

5. Reflow Oven Machine

Functional Features:

- The temperature zone control realizes the melting and solidification of solder paste, which determines the reliability of welding.

- The nitrogen protection function reduces oxidation and improves the glossiness of solder joints.

Working Principle:

PCB passes through the preheating zone, constant temperature zone, reflow zone (peak temperature 220-250℃) and cooling zone in sequence, and the solder paste undergoes a melting-solidification process.

6. Automatic Optical Inspection (AOI, Automated Optical Inspection)

Functional Features:

- Detect defects such as component misalignment, reverse polarity, and cold solder joints after welding.

- Multi-spectral light source + high-resolution camera to achieve multi-angle imaging.

Working Principle:

After collecting PCB images, the AI ​​algorithm compares the standard template and marks abnormal points.

7. X-ray Inspection Equipment (X-Ray Inspection System)

Functional Features:

- Dedicated to detecting internal defects (such as bubbles and cracks) of hidden solder joints such as BGA and QFN.

- Micro-focus X-rays penetrate the PCB to generate layered images.

Working Principle:

After the X-rays penetrate the material, they are imaged according to the density difference to analyze the internal structure of the solder joint.

8. PCB Unloader/Separator

Functions and Features:

- Stack or cut finished PCBs into separate units.

- Laser separation technology avoids mechanical stress damage to circuits.

Working Principle:

Collect PCBs through a robotic arm or conveyor belt, and laser accurately cuts the separation area of ​​the connected boards.

9. Rework Station

Functions and Features:

- Perform local repairs on defects detected by AOI/X-Ray.

- Disassemble/resolder components with a precisely controlled temperature hot air gun.

Working Principle:

Infrared heating or hot air nozzle heats specific solder joints, and the suction pen removes defective components and re-mounts them.

Technology trends of SMT production lines: intelligence and high integration

Modern SMT production lines are developing towards "fully automated closed loop":

1. MES system integration: real-time monitoring of equipment status and production data, and optimization of process parameters.

2. AI defect analysis: AOI+SPI+X-Ray data linkage to improve detection accuracy.

      3. Flexible production: modular equipment adapts to multi-variety and small batch order requirements.