Re: Future: 0603 versus 0402 parts

On Sat, 17 Mar 2007 20:51:28 GMT, "Jeff L" <levy_jeff@xxxxxxxxxxx>
Gave us:


"DJ Delorie" <dj@xxxxxxxxxxx> wrote in message
news:xntzwo64y0.fsf@xxxxxxxxxxxxxx

dalai lamah <antonio12358@xxxxxxxxxxx> writes:
Un bel giorno Joerg digit?:
I use 3x glasses and do it sans microscope.
And at the end of the day you can still find the way home? ;)

I use 2x and 3.5x mag visors, and after a while with the 3.5x on, I
can't focus on regular things any more. It takes a few minutes to
re-adjust. So, I try to use the *weakest* lens that works for the
part sizes I'm working with.

Same here, SOIC is becoming quite a rarity in my designs, almost
everything is TSSOP.

My last design (still debugging it ;) is primarily 0603 and tssop,
with sot-323 transistors. The occasional ssop (0.65mm pitch) seems
big to me now.

I know what you mean - after working with a bunch of 0402's, I sometimes
confuse 0603's with them!

I had SOICs on my last board, but only because it was
a RAM array and I wanted to run traces between the pins without
horrendously expensive fab costs, and it was a 5v design which limited
chip selection.

So, there is nothing wrong with using larger parts - the suppliers keep
pushing smaller is better (I think to push sales of new assembly equipment,
and to cover the investment costs of the production of smaller components).
I see no benefit in going smaller unless there is no room. I do however see
lots of problems in going smaller. Mostly reliability concerns and
production costs (especially hidden ones - ie change this resistor for this
mod now takes 5x longer and may be less reliable).


But, I've done boards by hand with tvssop (0.4mm pitch) and 01005
parts. It can be done, and it puts the larger (hah) parts in
perspective.

That's nasty!

I once resoldered my entire old laptop's motherboard (P2 233) littered with
0201's with a 1/8" chisle tip soldering iron! This fixed the intermittant
problem when you twisted it a bit.

It probably had nothing to do with any of the "soldering" you
performed and more to do with the interconnects between all the parts
you dis-assembled, and re-assembled. D'oh!
.

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