Surface Mount Soldering
One of the questions which comes up often as I talk about my hobby
is how to solder surface mount components. Thus I wanted to touch
briefly on the subject as it is very easy. The first step is to get
the right soldering iron. I personally prefer my Pace soldering irons.
In addition to having a good soldering iron, and
more important is having the right tip for the soldering
iron. Specifically pace calls their tips mini-wave tips.
These tips are unique in that they have a concave end kind
of like a horse`s hoof.
The tip is very important as the heat will pull the solder up
into the concave tip and help prevent solder bridges. The next
step is to place the component on the PCB and use a liberal
amount of liquid flux. When you have the component aligned
correctly you can tack opposite corners.
Liquid flux will soon be your best friend. I personally purchased a
gallon of no clean liquid flux about 5 years ago and have not gone
through ¼ of it yet. I also have used flux pens, but have found
the liquid flux cheaper.
Once the corners of the component are secure the next step is to put
just the right amount of solder on the tip of the iron. The solder
should form a bump that looks like a small pimple.
The you can simply drag the tip down the pins and solder them.
If they start to create solder bridges you either have too much
solder on the iron or not enough flux.
The process is repeated for each side of the chip resulting in a
perfect soldering job that only takes about 10-20 second for this chip.
After I solder all the components on a circuit board I will take the
board and wash it using kitchen soap and an old tooth brush.
After the board has fully dried I solder the connectors on the board.
Using the same soldering technique with large pads I also soldered
the QFN USB to UART chip on this project.