Hardware Reference
In-Depth Information
Figure 8-4.
Adapter and SO-8 chip
First you need to get some solder onto the pads on the SO-8 adapter board. This method is called sweat
soldering. Hold the RTC chip on top of the solder and apply a small amount of heat to the legs of the RTC. If your
adapter board has pin numbers, line up pin 1 of the SO-8 chip with pin 1 on the adapter board. Pad 1 is the pad with
the little circle next to it on the SO-8 package. I never seem to be this lucky; my board has no pad numbers so just go
ahead and solder it on anyway; later on I'll show you how to identify the pads once they are soldered.
It's a wise idea to solder opposite sides first. So solder the top left-hand-side pin first, then solder the last right-
hand-side pin. This anchors the component on each corner. By doing this you will prevent the RTC chip from moving
when you are trying to solder the rest of the pads. In Figure
8-5
you can see the finished job. Don't be afraid of adding
too much solder; I often do (if not, I accidentally join legs together). In fact it happens a lot when I am working with
SMT. If this happens get your desoldering wick and apply a small amount of solder to it. Then place it across the pins
that have been accidentally joined together and apply heat to the desoldering wick. This will remove the excess solder
away and leave the solder between the PCB and chip in place. Do check your solder joints with the magnifying glass.
There is nothing worse than missing a connection.
Figure 8-5.
RTC soldered into the adapter board
