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February 1999

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Subject:
From:
"Stephen R. Gregory" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 18 Feb 1999 19:05:32 EST
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In a message dated 2/18/99 2:17:55 PM Pacific Standard Time,
[log in to unmask] writes:


<< I have an assembly problem and would like to impose upon the tremendous
source of knowledge available out there.

 I have a through hole part that is .25 in. in diameter and about .40 in.
tall, with a lead spacing of .140 in..  The problem is that the part has the
wires from the internal winding showing below and between the through hole
leads.  This can cause manufacturing problems trying to keep those wires away
from the pads.  I am currently using a dab of RTV between the leads, letting
that dry and then stuffing the part.  I must let the RTV dry first in order to
not contaminate the plated holes.  Cumbersome as well as time consuming.

 Does anyone have a source that sells some kind of spacer, such as the ones
some manufactures make for crystals, that can fit the dimensional requirements
of this size part?  Or perhaps some other solution?

 Thanks in advance

 Tom Burek
 [log in to unmask] >>

Hi Tom!

      One of the better known suppliers of spacers is Bivar (949) 951-8808.
They make permanent or wash-away spacers (if your process can tolerate a wash-
away spacer) of any size you need. Another supplier is Amatom (1-800)
243-6032, they carry the same stuff. BUT, if you wanna know how I dealt with
my spacer problem, I'll tell ya'. I needed to stand a small two-leaded oval
shaped crystal up offa the board not because of the body shorting to a pad,
but because there was a 0805 cap that was too close and the little lip of the
crystal can would contact the cap...so I had to raise it above it. As you
know, anytime you attach the words "printed circuit assembly" to anything you
wanna buy, the price goes up about 1000%. For example:

Man in store: "I wanna buy some needle nosed pliers"
Customer Service person: "Oh, here's these at $5.00 a pair."
Man in store: "Those look good, but I need smaller tipped ones for my printed
circuit rework people."
Customer service person: "Well, you'll need these ESD safe, Hi-Tech ones that
are $50.00 a pair."
Man in store: "They look like the same pair!"
Customer service person: "Oh no, these are ESD, Hi-Tech, printed circuit
pliers!"

I needed spacers right away and didn't have time to wait even on something
fed-ex'd to me. So, what I did was go to a place called Michaels which is a
hobby and craft store and bought some tiny glass embroidery beads....didn't
have any sort of "printed circuit" label on them, gave me a .055" stand-off
height, and cost me a whopping .59 cents a bag (had at least 1,000 beads in
each bag). Plus,if I wanted to get fancy, I coulda bought those stunning
chartreuse ones...they kinda went with the shade of green that the board
was....(GRIN)

-Steve Gregory-

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