smd

[Krister Wikstrom]

>> To mount a component, put little solder on each pad,
>Actually, you are better off only putting solder on one pad, then 
>soldering that one to hold the part while you solder the rest of the 
>part.  Remember to heat the joint between the pad and the pin, not 
>just the pin, then apply solder to the joint, not the iron.  If the 
>joint is not hot enough to melt the solder, then you will get a 
>cold-joint.  It is pretty safe to re-heat all your SMT joints after 
>the component is mounted.

Thats how I also did it, but then I noticed, that it was easier (for me 
that is) to first put some solder, and add it only as needed. This helps
to avoid solder bridges as I don't have the correct "thin" solder,
and it is very easy to put too much solder.

>> It is very easy to remove smd resistors etc by using two soldering
>> irons, or by shortly warming both pads many times.
>Careful because often times the parts are glued to the board as well 
>as being soldered.  Dunno if this applies to car electronics, but 

True, most are glued, but usually the glue seems to be quite weak.

On removing parts I forgot to mention (like noticed..) that first
you really should remove all the solder possible.

I got a large box of obsolete computer boards, and my short experience
on smd is mostly based on removing useful components of them. At first 
it seemed difficult, but soon you learn to work with them.
 
If there is someone afraid of doing anything with smd parts, 
just go for it, but it might be a good idea to first practice on 
something cheap ;-)

 Krister Wikstrom
 kwi at mamma.icl.fi