Some Important Notes In The SMT (Surface Mounter Technology) Manufacturing Line

SMT processing flow:

SMT Process Flow

1. Solder paste printing: Its function is to print the solder-free paste on the PCB pads to prepare for the soldering of components. The equipment used is a screen printing machine, located at the forefront of the SMT production line.

2. SMCs placement: Its function is to accurately install surface mount components (SMCs) to a fixed position on the PCB. The equipment used is a placement machine, located behind the screen printing machine in the SMT production line.

3. Reflow soldering: Its function is to melt the solder paste, so that the SMCs and the PCB board are firmly bonded together. The equipment used is a reflow oven, located behind the pick-and-place machine in the SMT production line.

4. AOI (Automatic Optical Inspection): Its function is to inspect the soldering quality and assembly quality of the assembled PCB board. The equipment used is an AOI machine, and the pads quantity is usually more than tens of thousands. If the pads quantity is small, manual inspection is implemented. The location can be configured in a suitable place on the production line according to the needs of inspection. Some are before reflow soldering, and some are after reflow soldering.

5. Repairing: Its function is to repair the PCB board that has failed. The tools used are soldering iron, rework station, etc. configured after AOI inspection.

Important notes for SMT manufacturing process: 

1. Confirmation of test fixtures: confirm the conditions of test fixtures and test accessories before production; collection of previous problems

2. Confirmation of special materials: confirm the materials which had flaws previously before production and other normal materials

3. First article confirmation:

(1) Make a simple understanding and test of the first article, and check the related first article records

(2) Check whether the previous problem occurs again and whether the hand is improved

(3) Confirm whether the previous SMT chip processing flow and process need to be improved

4. Analysis and confirmation of defective products

Make a simple analysis of defective products, understand the main defects distribution and main causes, and try to solve the defects

5. Information feedback

(1) Feedback to the person in charge of SMT process

(2) Collection of assembly problems in the factory, feedback to the person in charge and request for improvement. 

Le Hang