Hi Kenny!
You say they're not pressed in hard, but are they snug?
I imagine that they are snug enough so they stand-up straight, no?
I have something similar happening here, but it's with some terminal
lugs. They've got four leads to them with a screw in the top to attach
some wire. The 4-leads splay out a bit so that the lug snaps into the
holes. It's a snug fit, but not overly tight.
As in your case, everything is fine till after wave. We hand built the
first few boards and didn't notice any measles, but after we started
production, here they are. We're not rejecting them however. We
told our customer about them and they said not to reject them either.
What I think is happening, is that the board is expanding during pre-
heat and wave, and because of the snug fit of the lug leads, they aren't
giving the board any place to go, so it measles.
The holes for the lug leads are fairly large....probably around .100".
Kind regards,
-Steve Gregory-
Senior Process Engineer
LaBarge Incorporated
Tulsa, Oklahoma
(918) 459-2285
(918) 459-2350 FAX
|---------+---------------------------->
| | "Morse, Carrie" |
| | <CMorse@CIRTRONIC|
| | S.COM> |
| | Sent by: TechNet |
| | <[log in to unmask]>|
| | |
| | |
| | 06/16/2005 01:10 |
| | PM |
| | Please respond to|
| | TechNet E-Mail |
| | Forum; Please |
| | respond to |
| | "Morse, Carrie" |
| | |
|---------+---------------------------->
>--------------------------------------------------------------------------------------------------------------|
| |
| To: [log in to unmask] |
| cc: |
| Subject: Re: [TN] Measling Conundrum |
>--------------------------------------------------------------------------------------------------------------|
My recommendation is to try to figure out where within the wave process
the measling is happening (preheat? Or over the Wave?)
Also...attach some TC's and see what the time and temps are.
-Carrie
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bloomquist, Ken
Sent: Thursday, June 16, 2005 9:54 AM
To: [log in to unmask]
Subject: [TN] Measling Conundrum
My question of the day sort of reminds me of a Steve Gregory type
question. It just doesn't make sense but still it's happening ;-)
We have a board that has standoff's cone swaged into it. They are not
roll swaged or pressed in hard. They still spin after they are swaged
in. We mask the hole in the center with temporary solder mask to protect
the threads. We run it through the wave solder with the following
parameters:
The topside board temp through wave is about 280 degrees F.
Conveyer speed of 2.5 FPM
Solder temp at 460 degrees F
Bottom preheater 2 is at 275 F
Bottom preheater 1 is at 360 F
Top preheater is at 300 F
When the boards come out we have measling around the standoffs.
Now for the Steve part of the equation. If we hand solder the standoffs
into the board they do not develop measles. We tried to make measles and
using two soldering irons and staying on the solder joint for about 38
seconds we finally got a few around the pad but not enough to be
rejectable.
So... Why is the wave solder causing these standoffs to measle and not
hand soldering?
Thanks,
KennyB
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