|A simple lab for an
advanced project. Besides the oven and solder pen, this is all the
equipment you will need.
Freescales MC13192, a nasty little thing.
MC13192, without doubt the trixiest component of
this project. As you can see there are small strips of plastic dividing
the bottom and side parts of the pads. There's certainly a perfectly
good reason to why one would make them like that but so far we haven't
figured it out. As a hobbyist with limited equipment you will have a
better chance of success without those plastic edges so we'll remove
BTW, Those are paper fibers you see, not some hairy arm :)
|We have not
but this is probably not recommended by freescale. Manhandling
a component this way doesn't look very nice but so far we've done
it without mishaps. Find something sharp and remove the plastic by
gently scraping the edge. Maybe a very fine grained file will do the
|This is what what
you should get after the modding. The solder paste will now have a much
bigger chance of fusing with the pads in our home lab.
|Time for the solder
paste. The components in this project have a rather fine pitch so we
were not able to use a dispenser in the form of a standard hospital
needle. Instead we just used the leg of a ordinary resistor to dip in
the solder paste and smear it out on the pads. Maybe a more
sophisticated and professional dispenser will work but that would be
like cheating. Make sure to clean the PCB from grease and dirt with
alcohol or some such before applying the paste.
When it comes to the MC13192 experience says that it is better with too much solder than too little. When using too much it will just be pressed out from underneath the chip without causing problem but too little will give you problems. Though problems that can be solved, as we will show you later on.
|Alignment of the
components are easy, except for the (surprise!) freescale chip. This is
the only time we make use of a magnifying glass.
|Cookie time. When
you put it in the oven, make sure that there are free air underneath
the PCB, that way the board will heat faster.
|This is what will
happen if you use too much solder. The fix is really easy! Just touch
the solder beads with a clean solder iron tip and they will be gone in
|Same thing with the
AVR, just touch the pins with a clean tip and the solder bridges will
|When using too
little solder paste on the MC13192 it will be a bit harder to fix.
Make sure the metal of the track to the offending pin is clear of the coating. Put some solder paste on the track and the edge of the component. Put the clean tip of the solder pen on the track about 1-2 mm from the chip (not touching the paste mind you!). Wait for the paste to melt and fuse with the pin.