hi,
we hot bar soldered these connectors (b3) and used the tie bar to lift the leads onto the lrm pad patterns. after soldering, we cut them off with 'tip' cutters. our operators are outstanding and, to my knowledge, never damaged the solder joints. our first approach was to leave the non-conductive tie bar on. the first z-axis vibe test taught us that that was a bad idea. we then used the tie bar to flex the tails up and down to break it off. again, a real bad idea. the cutters did the job for us.
phil
-----Original Message-----
From: Steve Gregory [mailto:[log in to unmask]]
Sent: Wednesday, March 03, 2004 4:14 PM
To: [log in to unmask]
Subject: Re: [TN] cutter for tie bars.
Hi Daan!
I guess the saying; "Misery loves company" certainly applies in this case...I
truely feel your pain. In my case, not only were solder joints affected, but
we had lifted pads that occured from the force being transferred down to the
solder connection that it took to separate the tie bars. Luckily, I had
production stop trying to separate the tie bars after only one assembly until I
figured out what was going on.
Not only are these connectors expensive, but lead-times are w-a-a-a-y-y out
there. I had to figure out something quickly, because delivery of the
assemblies were very critical to our customer.
I did at first try to cut the tie-bar off as probably Charles is thinking.
But that's no good because there is the same kind of forces transmitted to the
solder connection.
What I finally had to do was gently, and I do mean gently, flex the tie bar
back and forth, gradually increasing flex angles until the leads would finally
stress harden and become brittle enough to break at the score line. This was a
rather time consuming process. The assemblies that had these connectors had
four tie-bars that needed to be separated. These connectors that I speak of,
are the LRM series with brush contacts...the straddle mount type.
The whole connector is VERY expensive as you said, but you can buy each
component of the connector separately, since there are several pieces that make-up
these connectors. That helps cost-wise when you only need to have new
contacts, but it doesn't change the lead times.
It's interesting that there is more than just a few of us that have problems
with these connectors...
I wonder if there is anybody from Amphenol on the list listening?
-Steve Gregory-
Hi Charles,
When you ask for deeper scoring you should be very aware that they don't
score too deep: we had a situation with Amphenol where we lost the tiebar
before we had the connector mounted onto the board, and we had to scrap
several of them (and these connectors were VERY expensive).
We have also worked with a tool that was made by Amphenol to break off the
tiebar, but the operators didn't like it very much because they couldn't
feel anymore what they were doing. And if the scoring is not deep enough
you'll end up with some ruined solder joints anyhow!
Regards,
Daan Terstegge
http://www.smtinfo.net
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