Currently only on the Alloy 42 TSOP part. We have the Copper lead frame
parts from Intel now and we will continue to do this test until we prove
to ourselves that the new solder joints are effective.
----------
From: Michael Branning
To: Max Bernhardt
Subject: RE: ASSY: Fine Pitch Solder Joint Inspection Method?
Date: Tuesday, January 21, 1997 8:47AM
Is this just on Alloy42 Intel parts? Just curious....
At 07:22 AM 1/14/97 -0600, you wrote:
>With TSOP packages, we have done this test for lack of anything more
>scientific. We have found that even after temperature cycling, ICT, and
>functional testing that we still have problems with leads being loose on
>the board. Therefore, the only quick and dirty way of checking for bad
>leads is to use a dental pick on the leads. I hope this helps.
> ----------
>From: [log in to unmask]
>To: [log in to unmask]
>Subject: ASSY: Fine Pitch Solder Joint Inspection Method?
>Date: Monday, January 13, 1997 9:49PM
>
>
>Hello all,
>
> I've got a question, how many of you out there check whether or not
>a fine
>pitch solder joint is good by dragging the tip of an exacto-knife blade
>or a
>steel pick across the foot of the leads?
>
> I have seen it done back in the past by a few inspectors maybe 4 or
>5 years
>ago, but not anytime recently...until I heard about it today. Is this
>still a
>common practice?
>
> I'm pretty sure it's not the smart thing to do, but when you have
>someone
>call and tell you that the fine pitch solder joints on the board you
>built for
>them are insufficient because the leads come loose when they check them
>with an
>exacto-knife...they sure don't want to hear you tell them that they
>shouldn't be
>dragging anything across the leads.
>
> I'm almost sure it's not one of the cases where sometimes a solder
>joint
>will become plastic during wave soldering and separate from the pad,
>some of you
>may have seen that before. You know, where the fillet stays attached to
>the foot
>of the lead with a nice wetting angle and all that stuff, but it's not
>attached
>to the pad...but I haven't actually seen the actual boards that
>supposedly has
>the insufficient solder yet, the customer has to bring them to me...
>
> Oh, another thing, these boards have all been through and passed
>ICT, a
>24-hour burn-in, and a functional test after burn-in. So it would seem
>to me
>that if I have a problem with my solder joints, it would have showed
>itself for
>sure in burn-in...
>
> But before they get here, I'd thought I'd ask and see if it's a
>common
>practice to rake fine pitch leads with a steel object...by the way,
>we're
>talking about .020" pitch QFP devices here...
>
>
>(gimme' some ammo guys!) Thanks in advance!
>
>
>
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>
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>
Michael Branning
Avtec, Inc.
4335 Augusta Hwy
Gilbert, SC 29054
(803) 892-2181
(803) 892-3715 FAX
[log in to unmask]
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