The invention discloses a vacuum
reflow soldering positive and negative pressure combined
welding process, and relates to the technical field of vacuum
reflow soldering. The process comprises the following steps that debugging preparation is carried out on vacuum cabin equipment; vacuumizing is carried out in a normal temperature state until the pressure in a vacuum cabin is smaller than or equal to a preset pressure value of 0.05-100PA of negative pressure; the vacuum cabin is filled with a
reducing agent into in a normal temperature state until the
positive pressure is 1000-500000PA; heating is carried out to reach 160-180 DEG C; then heating is carried out to reach the
melting point of
welding flux of 217 DEG C; then heating is carried out to reach 245-260 DEG C, and the constant temperature is kept for 1-30 seconds; vacuumizing is carried out for 20-30 seconds, and the vacuum degree in the vacuum cabin is maintained at the negative pressure
ranging from 0.01 PA to 100 PA; cooling is carried out; the
internal pressure of the vacuum cabin reaches normal pressure; and when it is detected that the preset
cooling temperature is reached, a weldment is taken out. According to the process, firstly, under the action of
positive pressure, bubbles in the
welding flux are removed, then when vacuumizing is carried out to reach the negative pressure, the bubbles in the welding flux are removed again, the discharging time of the bubbles is greatly shortened in a
positive pressure and negative pressure combined mode, and therefore the voidage of the welding flux is far lower than the voidage in a traditional process.