Vacuum reflow soldering is the main purpose of soldering products in a vacuum environment to protect the product and solder from being oxidized. The vacuum reflow soldering system is relatively closed and requires vacuum assistance for soldering. Under this condition, vacuum reflow soldering can pass Efficiently discharge the bubbles generated when the flux volatilizes, reduce the void rate of the product's welding surface, and improve the product's welding quality.

Vacuum reflow soldering technology:

The vacuum reflow soldering process is a reflow soldering technology that introduces a vacuum environment during the reflow soldering process. Compared with the traditional reflow soldering, the vacuum reflow soldering creates a vacuum environment in the latter part of the product entering the reflow area, and the atmospheric pressure can be reduced to 5mbar (500pa) or less, and keep it for a certain time, so as to realize the combination of vacuum and reflow soldering. At this time, the solder joint is still in a molten state, and the external environment of the solder joint is close to vacuum. The air bubbles inside can easily overflow from it, and the void rate of the solder joints is greatly reduced. Low void ratio is especially important for power devices with large-area pads. Since high-power devices need to conduct current and thermal energy through these large-area pads, reducing voids in solder joints can fundamentally improve the electrical and thermal conductivity of the device. performance.

The process parameters of vacuum reflow soldering technology, compared with the traditional reflow soldering, on the basis of parameters such as temperature and chain speed, four vacuum parameters are added, including vacuum degree, vacuuming time, vacuum holding time and normal pressure inflation time. Step-by-step vacuuming can be used to gradually reduce the atmospheric pressure to prevent the abnormality of the molten solder joint caused by the vacuum impact of the device, and to prevent the pressure difference between the internal bubble and the vacuum cavity from changing too fast when the solder is in the molten state. It is too large to cause the phenomenon of fried tin, which leads to the problem of tin beads around the device.

The process risks existing in the actual production application of the vacuum reflow soldering process need to be identified and avoided by process technicians. And strengthen the control of personnel operation to ensure the final welding quality of the product.