PCBA Tech - What are the factors that affect the quality of SMT processing and placement?

In SMT patch processing, the placement quality of components is very important, which affects the stability of the product. The main factors affecting the placement quality in SMT patch processing are as follows:

1, the components must be correct

During the patch processing, the type, model, nominal value, polarity and other characteristic marks of each assembly tag component are required to meet the requirements of the product assembly drawing and schedule, and the wrong position cannot be pasted.

2, the location must be accurate

(1) The ends or pins of the components should be aligned and centered with the land pattern as much as possible, and ensure that the solder ends of the components contact the solder paste pattern accurately;

(2) The component placement position must meet the process requirements.

3, the pressure (patch height) should be appropriate

The pressure of the patch is equivalent to the height of the Z axis of the suction nozzle, and its height should be appropriate and appropriate. If the mounting pressure is too low, the solder ends or pins of the components float on the surface of the solder paste, and the solder paste cannot stick to the components, and it is prone to position shifts during transfer and reflow soldering. In addition, because the height of the Z axis is too high, the components are dropped from a high place during the placement process, which will cause the placement of the placement to shift. If the pressure of the patch is too high and the amount of solder paste squeezed out is too much, it is easy to cause the solder paste to stick, and it is easy to cause bridging during reflow soldering. At the same time, the position of the patch will be shifted due to sliding, and the components will be damaged in severe cases.

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