Hello Tim,
Flex circuits...fun stuff huh? Well, be glad that the parts are through-
hole instead of SMT, reflow can sometimes be a REAL bear depending on how the
circuit is shaped and what's being placed on it.
Almost 99.999% of the time I've ever dealt with flex circuits they've
always had to go on a pallet or work-piece holder, and stay there from
printing until they come out of the reflow oven. They might even have to stay
on the pallet for a little while longer after they come out of the oven...darn
thing is too hot! Gotta let it cool down a little before I can take the flex
circuit off!...hehehe
Seriously, the biggest headache with flex circuits is just being able to
tool it somehow so it'll stay put in one place while you're running get
through all your machines. So, other than that "teensy" minor problem, you
just do things like you normally do with any regular FR4 PCB...'cept maybe use
tilt-racks...HAR!HAR! (Gawd, it's getting late in the afternoon...I'm actually
laughing at my own stupid jokes!)
Are you really thinking about trying to wave these puppies? For just two
connectors it kinda seems on the surface like that may take more work and
energy than say using a Airvac unit or something along those lines. I will say
that hand soldering will burn some time too, but that may depend on how many
pins are on the connector.
When you're thinking about a process for these guys, don't get locked
into focusing on JUST the soldering operation. Think about how much time it's
gonna take to load and unload them in and out of a fixture, the fixture costs,
cleaning the flux from the fixtures after using them, etc., etc. After
weighing everything against each other, it may turn out that it'll be easier
and more efficient to handsolder the darn things.
As far as using a Zevatech 700 series machine to place SMT on Flex, go
for it! I just left Zevatech about two weeks ago (I missed being on the
production floor, so now I'm working at a start-up contract assembly
company...smart move huh? LOL!!!!) and I know there's one big Zevatech
customer in which flex circuits is almost ALL of their business, the companys
name is SmartFlex Systems (www.smartflex.com). They even do Chip-on-flex, and
Flip-on-Flex! In fact, you should visit their web site if you can, download an
Adobe Acrobat reader before you go there though. There's links to some good
papers and information about design guidelines for flex circuits, and reprints
of 4 or 5 magazine articles that were published by engineers at SmartFlex.
I'm assuming you have a FM740. If you're planning to do SMT on flex
that's going to be any more complicated than just a 50-mil IC or two and a few
caps and resistors, you'll need to think about getting a vision system upgrade
if you don't already have it. It's called pattern recognition. It's a
"aftermarket" system from Datacube that will allow you to teach anything you
want as a fiducial, and with flex circuits and pallets, you'll want/need to
look at fiducials for any decent placement.
Problem is, you don't ever see any real fiducials on flex circuits, and
that's where Datacube comes in. The standard 740 can only recognize SMEMA
fiducials. Datacube can look at a SMT pad or trace pattern and use that as a
fiducial.
Good Luck!!
-St
eve Gregory-
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