On Mon, 29 Nov 2010 23:58:11 -0800, Smitty Two
wrote:

In article ,
wrote:

On Mon, 29 Nov 2010 19:45:54 -0800, Smitty Two
wrote:

In article ,
wrote:

Also, PROPER installation involves spreading the leads slighly when
they come through the hole so the component stays in place when you
either turn the board over to solder it, or move the board to the wave
soldering machine.

Utter nonsense. Is this ever done? Yes. Is it the only PROPER way to
install components in a PCB? Absolutely not.

Mechanically placed components virtually all have (or at least had)
that little kink that held the part in place.
All the custom boards I had made also did. (we are talking in the
computer industry) And all the automotive computers I've worked
on/repaired (up until the '90s)

And a very large number of SMTs are glued to the board (solder paste
in some cases) which does not do much for the final strength, but
keeps the part in place until it is soldered

There's no real reason to latch through-hole components to the board
prior to soldering, unless you're worried about them getting lost on the
way to the machine. High volume automated stuffing machines had that
feature built in, which is probably why you used to see it on computers
and such.

Correct.

SMDs are glued down on double sided boards, on the bottom side only so
the parts don't fall off during reflow. Otherwise, it's extra time and
money for no gain.

Nope, unless you consider "solder paste" to be "glue". The normal SMT process
uses no glue, rather does a pass through the oven for each side. Glue is
sometimes used but not generally.