Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


PTH Crystal Spacer

armin

#7766

PTH Crystal Spacer | 19 January, 2000

Hi,

We have a couple of pcb's with PTH Crystal. We are looking for a spacer to be placed between the metallic body of the crystal and the via pad/land as they tend to short if wave soldered without a spacer. The spacer we are looking for is something that is permanent on the bd. which means that the operator need not remove this after wave soldering. Current process use silpads as spacers then need to be removed after wave soldering then these silpads need to be returned back to production line. we want to cut down the process by using some permanent spacers. Any advice on what material is to be used for this and is there any available spacers for pth crystals in the market? Is there some peeps out there who had this problem and able to solve.

Please help !!!

thanks and regards, armin

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CPI

#7767

Re: PTH Crystal Spacer | 20 January, 2000

Armin:

Are you washing the brds after wave? If so there are water soluble spacers out there that work great and are removed through the washing process!

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John Thorup

#7768

Re: PTH Crystal Spacer | 20 January, 2000

a good source for spacers of all kinds, including the wash aways, is Bivar in California @ 714/951-8808 John Thorup

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Brian W.

#7769

Re: PTH Crystal Spacer | 20 January, 2000

Bivar's area code has changed to 949. They also have a website...www.bivar.com.

I am using one of their water soluble spacers for a crystal, and it works great. They also have permanent ones.

Brian

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#7770

Re: PTH Crystal Spacer | 20 January, 2000

Hey Dreamguy: On stand-offs:

* "Sugar" stand-offs look nice, after washing (if you wash, as Chad said), but we find them kinda fragile. The only people that can install 'em without bustin' more than they install are the "skill people" that we don't want doin' this cretin type work anyhow. * So, we prefer the solid type. As John and Brian said Bivar is a good source. Also, some distributors like Digikey sell 'em too. * Most of the time though, we use beads from the local hobby shop. Ya know, like the kids used to make wrist bands and the like. We ended-up there, becuase we found we were too dumb to control floor stock on regular stand-offs. One caution: some bead materials don't retain their shape at 500�F. Nuff said. * As an alternative, have you considered forming the wire leads of the crystal to stand-off the component from the board? I'll have to admit that I hesitate doing that, because of the potential to damage the glass seal on the crystal packaging.

Good luck

Dave F

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RDR

#7771

Re: PTH Crystal Spacer | 20 January, 2000

Many times the crystal supplier also has a package that already has epoxy bumps on them to allow th crystal to be raised off of the board. This is my preffered way since placing spacers on components can be time consuming and operators can and will forget on occasion.

Russ

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