Solder paste is a necessary material for SMT processing, it is used for flux, it is good for isolating air to prevent oxidation, on the other hand, it can prevent virtual welding.Solder paste consists of solder powder and flux.Here are some notes to use solder paste during SMT processing in FASTPCBA.
(1) try to make the solder paste "return to temperature" as far as possible during the "tempering" process, and do not force heating.
(2) before use, the solder paste that has been "warmed back" shall be uniformly stirred to increase the wettability of the solder paste.When stirring manually, use solder paste special metal shovel until smooth.When using the machine, the stirring time should be paid attention to, the time should be appropriate, excessive stirring will cause the viscosity of solder paste to decrease, the temperature will rise, the welding powder and the solder reaction will affect the quality of solder paste.The mixing time is different according to the stirring device, and the time is different.
(3) the viscosity of solder paste will change according to temperature and humidity.The temperature rises and the viscosity decreases.As the humidity increases, the solder paste absorbs moisture and affects the quality.
(4) after opening to SMT processing, the solder paste used multiple times when must fully confirm quality if there is a change, because after opening the used solder paste used again is not in the scope of the quality.
(5) do not lick the solder paste when using;Avoid solder paste contact with the skin.When the skin is not carefully glued to the skin, it can be wiped with dry paper towel and alcohol, and then washed with soap.
(6) solder paste contains flammable solvents, so keep away from fire during SMT processing and avoid fire.
(7) a ventilation installation must be installed in the workshop where solder paste is used, and fresh air is often imported.
(8) when reflow soldering, the local exhaust device must be installed because the solder paste can generate waste gas due to the decomposition of solvents and other solvents.
(9) different types of solder paste cannot be used in combination.
(10) clean the cleaning fluid used in cleaning circuit boards and templates, and do not mix in solder paste.
(11) waste solder paste should be treated in strict accordance with relevant regulations.
(12) 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 finish SMT processing and welding within days.