Ed Current wrote:
> My boss and I were discussing design reliability, when we realized that
> although we both have heard for years the SMT resulted in more reliable
> boards, neither could recall seeing a written confirmation of this. Can
> anyone help?

If you EVER get a written confirmation of this, I'd like to see it!
Maybe you are thinking of reliability in a different light, and if so
please clarify....
Anyway,
Attaching SMDs to a board is basically "sticking" them to a pad, and the
mechanical strength depends on the peel strength (how good the copper
land sticks to the fiberglass) and the quality of the solder joint. The
strength of a leaded component in a plated hole is incomparable, like
imagine the difference between welding a car together instead of using
bolts. A shock test on a SMT board often results in components
splattering around inside the enclosure! (protect your eyes, heheh) So
from a shock and vibration point of view, SMT basically sucks.

 From a thermal point of view, more stuff packed into a smaller area.
The same "die" in smaller packages, less thermal mass, easier to torch
components during soldering processes, etc etc etc.   and from a rework
point of view, forget it!

The advantages in automated assembly (pick and place) and reflow
soldering significantly reduce TIME and ERROR, and increase
repeatibility and predictibility, which might be related to the
"reliability" you were thinking of.

                                                                Jack

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