Printing Solder Paste Test
To ensure the quality of the printing, it needs to monitor the printing press parameters: printing speed / squeegee pressure / printing gap / separation distance / clean frequency / paste thickness / the viscosity. All these parameters should be met the specification.
Paste neither is a solid, not a liquid, it is a mixed paste objects, the main component is the solder powder (tin powder) and the flux (flux)
(1) Printing Red Glue
The red glue is usually kept in the refrigerator at the optimum temperature. It should be remove thawed at room temperature before using. And then open and stir to use.The dosage shoulbe be not to exceed two hours. It also needs to check if the red glue printed on the bottom of the PCB mounting components with full and moderate. So that there is no infiltration of red glue mount to the the pad and connectors (or pins). At the same time, the red glue can make the components bonding and fastening. So that when wave soldering, the components are not easy to fall.
(2) Printing Solder Paste
The solder paste is usually kept in the at the refrigerator proper temperature. Be fore using, it should be removed from the refrigerator and thawed to room temperature. And then open and stir until uniform, smooth and put into use. It also needs to check after printing the solder paste is uniform amount printed on the PCB pads, with or without collapse and scattered at the surface of the PCB to ensure good reflow soldering components. And there is no beads scattered on the plate surface.