During reflow

The solder paste melts into a liquid, and the temperature during this period has now exceeded the melting point temperature of the solder paste. Tin on component pins. During this period, the temperature should be controlled between 60 and 90 seconds when it is above 183℃. If the time is too short or too long, it will cause welding quality problems. During the time when the temperature is in the range of 220+/-10℃, it is appropriate to control it. Usually, it is best to control it within 10~20 seconds.

Reflow soldering

Reflow soldering is the most difficult process in the process of BGA devices. Therefore, to obtain a better reflow curve is the key to outstanding soldering fixtures.

Warm-up period

And affect the activity of flux. Generally, the heating rate should not be too fast, and the PCB will be heated evenly during this period of time. Prevent the circuit board from being heated too fast and causing large deformation. Try to control the heating rate below 3°C/sec. The more ambitious heating rate is 2°C/sec. The time is controlled between 60 and 90 seconds.

During cooling

The components are fixed on the circuit board. The same cooling rate should not be too fast, during which the solder paste begins to condense. Usually controlled below 4°C/sec, the more ambitious cooling rate is 3°C/sec. Because the rapid cooling rate will cause the circuit board to deform coldly, it will cause the quality problem of soldering through the tin furnace fixture, especially the virtual soldering of the BGA outer ring pins.

Moisturizing period

Furnace fixture so that the flux can fully exert its effect. The rate of temperature increase is usually between 0.3 and 0.5°C/sec. During this period, the flux started to evaporate. The temperature should be 60~120 seconds between 150℃~180℃.