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From: Chuck Simmons
Organization: You jest.
X-Mailer: Mozilla 4.61 [en] (X11; U; Linux 2.0.33 i586)
Subject: Re: having SMT components mounted
Date: Sun, 29 Sep 2002 15:08:05 GMT
NNTP-Posting-Date: Sun, 29 Sep 2002 08:08:05 PDT
> NNTP-Posting-Date: Sun, 29 Sep 2002 15:28:33
> Organization: ntl Cablemodem News Service
> (Thought I'd sent this last week, Oh well...)
> I've got to the stage where I'm wanting to put several >100pin devices
> onto a board, and I don't trust my clumsy soldering - I can just about
> manage 2mm pin-headers, but 0.65mm is smaller than I can *see*, let
> alone solder!
> I've used PCB board manufacturers before for my boards, but I've never
> had the components assembled onto the board after it's been etched.
> Some questions:
> o How do you go about doing this for 1-off prototypes ? And
> what's the procedure ?
There are small companies that do assembly. We use a shop where the
owner's son does much of the assembly. The son is still young enough to
see the parts and solder them though he does have to use a microscope.
> o Who sources the components ?
This is negotiable with the shop we use. Generally we source our own
parts and a few specials from other vendors and the shop sources common
parts. It's a matter of what you and the shop find comfortable. We would
do all of the sourcing if we had a technician to do the kits but as it
is, the kits fall to the most junior engineer or the department manager
- nobody else has any time for it.
> o How much would it cost for (say) 4 100 -> 150 pin devices ? I'll
> do the other components myself - I just don't want to solder the
> SMT bits...
I think we basically pay time and materials plus some overhead. Four
parts might cost between $100 and $200 US on a one off basis. This may
seem high but it is worth it considering everything involved. It would
cost us a couple of thousand US to set up a really good soldering
station and mounting the parts would cost engineering time simply
because we don't have a tech.
> I'm in the UK, if that matters these days, and using Eagle as my
> layout s/w. Any help gratefully received :-)
If you are going to make a habit of using the fine pin pitch parts, you
should get a decent inspection microscope. We have a 20X in the lab
which works well for us. We got it for under $1000 US. A 10-20X zoom
would be better. We use it to check for solder bridges and the like on
the fine pitch parts. We have had board problems that we could not see
without the microscope.
... The times have been,
That, when the brains were out,
the man would die. ... Macbeth
Chuck Simmons email@example.com
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