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Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Stenciling chipbonder.....

#23096

Stenciling chipbonder..... | 22 January, 2003

We're considering stenciling SMT adhesive to increase throughput. This is an as-of-yet unproven process and for that matter pcb design (we've never done anything with more than about 50 SMT parts on the bottom, this board has in excess of 1200, but no SMT on top, only pth), so we're sort of starting from scratch.

Any things to look out for as far as stencil design, i.e., stencil thickness (I'm guessing about 8 mil to get enough volume and height), aperture design, material advantages, etc.? Do you prefer round apertures for chips, or elongated slots, or...?

Anything out of the ordinary as far as layout, i.e., plating/mask/silkscreen thicknesses (I'm speculating about gasketing problems) that would be different than boards layed out for dispensing?

Thanks, as usual, in advance.....

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Jon Fox

#23097

Stenciling chipbonder..... | 22 January, 2003

Elongated slots!! Our older runs are a pain sometimes with parts (1206, 0805 chips) twisting as they go through cure. I'm sure that its not all due to the dots, but I'm sure that it doesn't help either. We don't see this effect on our runs that use slots. I would think that the more surface area, the better the alignment will stay true to its initial resting place in the pick and place machine. We do have a stencil with double-dots for 1206s and that worked well also.

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Stephen

#23098

Stenciling chipbonder..... | 22 January, 2003

Most of the design considerations will be for the wave soldering of the SMT parts. Have you considered selective soldering pallets or masking as an alternative? One problem I have seen with the epoxy process is parts that are high off the board and the epoxy barely touches them.

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#23100

Stenciling chipbonder..... | 22 January, 2003

Hey "Dispenser Boy" does this mean we can have your machine? ;P

I'll be out to supervise the packing with a Hook in my hand.

Poke around the fine SMTnet Archives to get started on aperture design. 7525, Stencil Design Guidelines is pretty much of a waste.

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#23103

Stenciling chipbonder..... | 22 January, 2003

Ya know, I got that thing because I was told, once upon a time, that besides some typical low density passive bottom sided stuff, we'd eventually be building products with SOJ's and QFP240's on both sides and short of hand dispensing big tall gobs of glue, it was the only way I could see how to do it without them falling off......

and you've never let me live it down, either. :P

"7525, Stencil Design Guidelines is pretty much of a waste."

Well, good, because I've lost mine. I don't remember much mention of adhesive stencil design stuff there, as you say.

Whatta they stick you for for a 6'er of ESB out there, ol' buddy? Har......

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#23106

Stenciling chipbonder..... | 22 January, 2003

Now that's hitting low!!!! "Whatta they stick you for for a 6'er of ESB out there, ol' buddy?" Now that's watcha call "comin' out swinging". You know how to hurt a fella.

Maybe, 6 and change.

Yever do any Pyramid?

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#23107

Stenciling chipbonder..... | 22 January, 2003

You probably pay the same as me. Ours is just fresher. ;) So fresh, in fact, that sometimes we can smell the brewery, when it's breezin' southerly. Not particularly appetizing, actually, although not as bad as the Stock Pot soup factory. City-wide onion soup at 6:30 a.m. is just not my idea of a reasonable wakeup call.

Pyramid? A few. Personally I think their Hewefeizen (I have some in my fridge at home right now) is a little on the "huh, what was that....was that beer or just pure mountain spring water?" side for me. I like body with my cloudy beer.....

Obligatory on-topic comment.....the Camalot 2800 functions nicely as a pass-through about 98% of the time. I'll let you know when we liquidate. Until then, we also use it for one of our programmers to work on his path optimisation software. He took about 30 seconds off of a 7 minute run for 1250 dots that we did with Camalot's optimisation software.

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#23112

Stenciling chipbonder..... | 22 January, 2003

First, wheat beer is not intended to be consumed at this time of the year in the northern hemishpere. It is ment to be consumed on the back porch, while smoking the LARGEST cigar you own, after mowing the lawn on a day that is so hot that the dog cannot stop panting [and slobbering on the floor]. This is the time of the year to be drinking some BIG syrupy brew that sticks to your teeth, like a McEwan's Scottish Ale.

Second, hefe is not Thomas Kemper's finest moment. Maybe try: * Amber Ale * Dark Ale

... both are dark Munich style beers that are pretty good, but if you decided to send me a case, I'd ask for the "Redhook Double Bock Stout" or even the "Redhook ESB".

OBLIGATORY TECHNICAL COMMENT. Don't you people have something better to do [other than figuring-out how to print glue]? I can't belive that your line in running at capacity. I can't believe your going to improve quality / lower cost by printing. What the blank are you guys trying to accomplish?

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Brian Doyle

#23120

Stenciling chipbonder..... | 23 January, 2003

There's a Red Hook brewery about 40 minutes south of here. I've taken that tour a few times.

Don't let Dave fool you though, he's changing tastes and is beginning to import beer from Maine.

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#23121

Stenciling chipbonder..... | 23 January, 2003

Yes, my favorite Down Easter beers are: * Casco Bay Pils * DL Geary's Pale Ale * Kennybunkport Magic Hat Blind Faith IPA

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#23123

Stenciling chipbonder..... | 23 January, 2003

Re: Brews:

I'll remember that.

Ob. Tech. Reply:

#1) No. #2) You're right not to believe that. #3) There you go thinking logically again....STOP THAT. #4) That is an unknown. Didn't I tell you about all this already? check your email.

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TriGuy

#23154

Stenciling chipbonder..... | 24 January, 2003

Chipbonder is best applied with a stencil. Too bad on the dispenser purchase.

Little hint, use a Kapton Stencil. You can have them laser cut and can get them as thick as you want. Another advantage is the ability to make shapes etc for cleaning.

Sounds like your PCB designer is killing you, heheehe

PS the Beers fresh here in St. Louie.

Good Luck

Forget about the selective pallets unless you want to go fishing for parts.

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Jon Fox

#23160

Stenciling chipbonder..... | 24 January, 2003

Good comment about the "passthrough" CAMALOT. I like that one. About the beer...when I was in field service, I was a microbrew nut, and still one of my favorites is Fat Tire from the Boulder, CO area. honorable mentions out West are (yes) Pyramid and Rougue River (Dead Guy Ale) and down South, Blackened Voodoo (though not really a micro anymore)is really good. Up in Woodbridge, NJ, a small place called J.J. Biddings, and equally good over in Somerville, NJ the Somerville Brewery.

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