What are the steps for welding and testing the first PCB assembly board

What are the steps for welding and testing the first PCB assembly board

The first piece refers to the first PCBA processing assembly plate meeting the requirements of patch processing and welding quality. The first finished board of the first batch of each new model is named as "first article" in SMT processing plant. Compared with subsequent products, the first article is not only an actual inspection of product performance, but also a quality inspection of engineering process.

The first piece refers to the first PCBA processing assembly plate meeting the requirements of patch processing and welding quality. The first finished board of the first batch of each new model is named as "first article" in SMT processing plant. Compared with subsequent products, the first article is not only an actual inspection of product performance, but also a quality inspection of engineering process. What are the welding and testing contents of the first PCB assembly board?

1. Welding of first PCBA assembly plate

Place the surface assembly plate that has passed the installation and inspection horizontally on the mesh conveyor belt or chain guide rail. The surface assembly plate slowly enters the furnace with the conveyor belt at the set speed, and then passes through the heating zone, insulation zone, reflux zone and cooling zone to complete reflow welding. Connect the surface assembly plate at the outlet in time. Wear an anti-static wrist strap during operation.

What are the steps for welding and testing the first PCB assembly board

2. Inspect the welding quality of the first pcb assembly plate

(1) Inspection method of pcb board

The welding quality of the first pcb assembly board is generally inspected by visual inspection, and 2~5 times magnifying glass or 3~20 times microscope are selected for inspection according to the assembly density

(2) Inspection content

① Inspect whether the welding is sufficient and whether there are traces of insufficient melting of solder paste. ② Inspect whether the surface of the welding spot is smooth, whether there is hole defect, and the size of the hole. ③ Inspect whether the amount of solder is appropriate and whether the shape of solder joint is half moon. ④ Check the number of solder balls and residues. ⑤ Check the defect rate of the monument, faulty welding, bridging, element displacement, etc. ⑥ Also check the color change of PCB surface, and allow PCB to have a little but uniform color change after reflow soldering.

(3) Inspection standard

According to the enterprise standards formulated by the unit or other standards. At present, IPC-A-610E is mostly adopted for implementation.

3. Adjust the parameters according to the welding quality inspection results of the first pcb assembly plate

① The parameters shall be adjusted item by item to facilitate analysis and summary.

② First, adjust (fine tune) the speed of the conveyor belt, retest the temperature curve, and conduct test welding.

③ If the welding quality cannot meet the requirements, adjust the temperature of each temperature zone until the welding quality meets the requirements.