Vacuum reflow furnace is to perform high-quality eutectic welding of products in a vacuum environment. Therefore, it is also known as vacuum eutectic furnace, vacuum eutectic reflow soldering furnace, vacuum sintering furnace, etc. It is used under vacuum conditions to protect the product and the solder from oxidation. At the same time, the hydrogen atoms decomposed by formic acid are used to react the product with the oxide on the surface of the solder, which improves the weldability of the welding surface, while providing solder wettability, which better reduces the void rate of welding.It is generally used in products with high precision requirements such as aerospace, optoelectronics, medical care, automobiles, etc.

The vacuum reflow oven, like the ATV vacuum reflow oven, adopts the heating principle of infrared quartz lamp directly radiating silicon carbide heating plate. It has the characteristics of high temperature control accuracy (±0.5℃), good temperature uniformity (±1%), controllable temperature rise and fall, real-time display of process curves, real-time preservation, and traceability analysis. It meets the needs of power devices, TR components, laser devices, optical devices, new sensor devices, etc. Multi-variety, small batch, and high-reliability welding.

The application principle of the vacuum reflow oven is specifically to place the solder sheet into the tube and shell, and then place the chip on the solder sheet to assist the pressure or rely on the chip's own gravity to provide the pressure, or place the solder (solder paste) on the substrate or carrier, and then place the chip. Positioning and pressure assistance can also be achieved through a fixture. After the product is placed, close the door cover of the vacuum reflow oven chamber and perform the following curve welding, as shown in the figure. Take gold-tin solder as an example; first fill with nitrogen and vacuum 2-3 times to replace the internal atmosphere of the cavity, and then heat up to 200℃. Heat preservation, at the same time, when the surface temperature of the product reaches 160-180℃, a formic acid air flow is introduced to activate and reduce the surface of the sample to improve the content wettability, and then heat up and keep warm. The main control heat preservation is set at 330℃ (because the melting point of the gold-tin solder is 283℃, according to the process characteristics, it is necessary to reserve the hot melt, that is, the temperature required for conduction from the hot plate to the surface of the sample) for heat preservation. At this time, the solder reaches the melting point and is in a molten liquid phase state, supplemented by vacuum to discharge air bubbles, so as to achieve the purpose of low-hole welding, and then cool down. According to different products, you can Rapid cooling or controllable cooling, that is, different cooling stages can be set to achieve different material properties.

During the entire process, the temperature (main control temperature, safety temperature, mobile thermocouple temperature-sample surface temperature), air pressure, lamp power, etc. can be monitored in real time, and analysis curves can be produced to improve analysis capabilities.