Rev.P6

10

VPN12AD1E-FU

Lead-free soldering process is a standard of electronic products production. Solder alloys like Sn/Ag,

Sn/Ag/Cu and Sn/Ag/Bi are used extensively to replace the traditional Sn/Pb alloy. Sn/Ag/Cu alloy

(SAC) is recommended for this power module process. In the SAC alloy series, SAC305 is a very

popular solder alloy containing 3% Ag and 0.5% Cu and easy to obtain. Figure 56 shows an example of

the reflow profile diagram. Typically, the profile has three stages. During the initial stage from room

temperature to 150°C, the ramp rate of temperature should not be more than 3°C/sec. The soak zone

then occurs from 150°C to 200°C and should last for 60 to 120 seconds. Finally, keep at over 217°C for

60 seconds limit to melt the solder and make the peak temperature at the range from 240°C to 250°C.

It is noted that the time of peak temperature should depend on the mass of the PCB board. The reflow

profile is usually supported by the solder vendor and one should adopt it for optimization according to

various solder type and various manufacturers’ formulae.

FIG.11 Recommendation Reflow Profile

REFLOW PARAMETERS: