Re: gEDA-user: SMT/Through Hole Mix

[Bill Sloman <bill.sloman@xxxxxxxxx>]

At 15:38 16-5-2006, you wrote:
> I have a design that's very low production quantity(~50 pieces per 
> year) that has a couple of chips that only come in surface mount 
> versions.   Does anyone have any opinions on what the lowest cost 
> assembly option is with the design, is it better to attempt to do 
> the whole board in SMT with just a few components through 
> hole(things like power components) or do you do the board mostly 
> through hole except the 2 surface mount chips(noting that one is 48 
> pin tqfp).  Or do you go with two boards, one with all surface 
> mount(except for perhaps the connector between the boards) and then 
> do a second board with all the through hole components.
>
> We've managed to keep things strictly through hole until this point 
> in time. Unfortunately it's no longer viable to go all through hole 
> with new designs of any complexity.

I'm with Stuart. There is no real problem in mixing SMT and 
through-hole components on the same board, and nowadays I go for as 
much SMT as possible - it makes the layout much easier, and on 
multilayer boards it frees up a lot more of the inner layers for 
signal routing.

A cheap binocular microscope is useful if you have to rework an SMT 
board, and a hot-air reworking tool is handy for removing multi-pin 
components and putting them back, but I've put SMT components on 
prototyping boards without benefit of either.

Bill Sloman, Nijmegen