In PCBA processing, many engineers are trying to control flux usage.However, in order to obtain good soldering properties, sometimes more flux is required.In the selective welding process of PCBA machining, because engineers often care about the welding result, but not the flux residue.
Most flux systems use a drip device.To avoid stability risks, the flux used for selective welding should be inert in an inactive state -- an inactive state.
Applying a large amount of flux creates a potential risk of it seeping into the SMD zone and producing residues.There are several important parameters in the welding process that affect the stability. The key is the formation of a non-open portion when the flux is infiltrated into the SMD or other process at low temperatures.Although it may not have a bad effect on welding during the process, the unopened flux portion in combination with humidity produces electromigration when the product is in use, making the flux expansion a critical parameter.
A new trend of selective welding with flux is to increase the solid content of flux, so that a relatively small amount of flux can be applied to form a welding with a higher solid content.Typically welding processes require a flux solid content of 500-2000μg/ In2.The actual situation can be complicated, except that the flux amount can be controlled by adjusting the parameters of the welding equipment.Spread properties of flux are important for its stability because the total amount of solids after flux drying can affect the quality of the weld.
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