What should notice when using auxiliary material (solder paste)?
Solder paste is a necessary material for PCB assembly. It is used as a solder to help insulate air and prevent oxidation.Solder paste consists of solder powder and solder.Here’s what FASTPCBA summarizes: what are the considerations for using solder paste during PCB assembly.
Try to let the solder paste “return temperature” naturally during the “return temperature” process, and do not force the solder paste.
The solder paste that has been “heated back” should be stirred evenly before use to increase the wettability of solder paste.Manual stirring, solder paste special metal spatula should be used until the stirring until uniform.When using the machine to stir, pay attention to stirring time, time should be appropriate, excessive stirring will cause the paste viscosity decline, temperature rise, solder powder and solder flux reaction, affect solder paste quality.The stirring time varies according to the stirring device.
The viscosity of solder paste changes according to temperature and humidity.When the temperature goes up, the viscosity goes down.As humidity increases, solder paste will absorb moisture and affect quality.
When PCB assembly should be carried out after unsealing, the solder paste should be used for many times to fully confirm whether there is any change in quality, because the solder paste used after unsealing is not within the warranty range when being used again.
Do not lick solder paste when using;Avoid direct contact between solder paste and skin.Accidentally stick to the skin when, can use dry paper towel successively, alcohol cotton cloth is wiped, clean carefully with soap finally.
Solder paste contains flammable solvents, so keep away from fire during PCB assembly and use to avoid fire
The solder paste used in the factory must be equipped with an air change device, which often leads in fresh air.
When reflow soldering, local exhaust devices must be installed due to waste gas generated by decomposition of solvent in solder paste.
Different types of solder paste cannot be mixed.
Do not mix the cleaning liquid used for cleaning circuit boards, templates into solder paste.
Waste solder paste should be treated in strict accordance with relevant regulations.
In the case of long time printing, the solder paste in the flux will evaporate, and thus affect the release properties of solder paste printing, so the storage containers of solder paste, solder paste, the rest of the printed on the screen after application of other clean containers safekeeping, next time, should check the left solder paste in the presence of agglomerate or solidification condition, if too dry, solder paste should add suppliers thinner, reoccupy after the thin.In addition, the printed substrate shall be assembled into PCB in a day.