How to prevent false and false soldering defects in PCB Assembly?

PCBA soldering processing mainly refers to the production process of soldering PCB circuit boards and components together through the soldering process. The soldering process is prone to welding and false welding and other welding defects, false welding and false welding will seriously affect the reliability of the product, greatly increasing the cost of product maintenance. pcb board soldering

Caused by PCBA welding processing of false soldering and false welding defects for many reasons, mainly due to the solder not being fully infiltrated pads and component pins, components, and circuit board pads can not be fully welded. In the production process, specific ways to prevent the following.

(1) Moisture-proof storage of components
Components placed in the air for too long will lead to component adsorption of moisture, and component oxidation, resulting in the welding process components not being fully cleaned up Remove the oxides, resulting in defects of false soldering and false welding. Therefore, during the soldering process, bake the components with moisture and replace the oxidized components. components to replace the oxidized components. Generally, the PCBA processing plant will be equipped with an oven, there are water vapor components for baking.

(2) the use of well-known brands of solder paste
PCBA welding process appears in the virtual welding and false welding defects, and the quality of the solder paste has a great relationship. The solder paste composition of the combined metal components and fluxes Configuration is not reasonable, easily leads to the welding process, flux activation capacity is not strong, and the solder paste can not fully infiltrate the pad, resulting in false soldering, and false soldering defects. soldering defects. Therefore, you can choose a well-known brand of solder paste such as Chisso, Alpha, Viteco, and so on.

(3) Adjustment of printing parameters
Void soldering and false soldering problems, most of which are due to less tin, in the printing process to adjust the pressure of the squeegee, the use of appropriate stencil, stencil mouth is not too small, to avoid too little tin. too small, to avoid the situation of too little tin.

(4) Adjust the reflow temperature curve
In the reflow soldering process, controlling the welding time, in the preheating zone time is not enough, can not make the flux fully activated, and remove the welding of the Surface oxides, too long or too short a time in the soldering zone will cause false soldering and false soldering.

(5) Try to use reflow soldering, reduce manual soldering
Generally in the use of soldering iron for manual welding, the technical requirements of the welder are relatively high, the temperature of the soldering iron head is too high or too low, or in the weld, The soldering components are easy to cause false soldering and false soldering, the use of reflow soldering can reduce the human external factors, improve the soldering Quality.

(6) avoid soldering iron temperature is too high or too low
In the PCBA welding after welding processing and maintenance, all need to use the soldering iron for manual welding. The use of soldering iron, is not standardized operation, leading to the soldering iron head temperature being too high. If the soldering iron tip temperature is too high or too low, is very easy to cause false soldering and false soldering. Therefore, when soldering, keep the tip of the soldering iron clean. Therefore, when soldering, keep the soldering iron tip clean, choose different power types of soldering iron according to the size of different parts and soldering joints, the shape of the device, and control the temperature of soldering between 300℃-360℃.

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