How can I solder an SMD component with a pad on the bottom?

The absolute best way to do this is to preheat everything with a large high-flow hot air source or oven. Apply paste first, if you have it, or a little bit of wire solder to the pad. Then pre-heat. The pre-heat temperature is around 125C or so.

Often, you will notice the part kind of self-aligns itself and snaps into place when the solder is all melted. This is a good indication that it is hot enough. The temperature should be hot enough to melt the solder, but not overheat the part. Once everything is heat soaked at 125C, apply localized hot air directly to the part to be soldered and immediately around it.

Small parts will probably reflow much faster than large parts, and may not need as high a temperature either. Your first efforts may not work well. So keep track of the time, temperature and results. Once you find a winning recipe, stick to it.

Read More: SMT Assembly

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