Dave,
The temperatures were actually lower than 183. They ranged any where
from 120 to 165. The three solder pastes that passed the test melted at
183 +/- 5.
Kathy Palumbo
> ----------
> From: David Anderson[SMTP:[log in to unmask]]
> Sent: Tuesday, March 24, 1998 6:10 PM
> To: [log in to unmask]
> Subject: Re: [TN] FAb: Solderlevel -Reply
>
> Kathy,
>
> How far off from 183 degrees C were the other solder pastes? When I
> look
> at the tin lead phase diagrams in my text books, it looks like the
> true
> eutectic point is at 61.9 wt% tin and 38.1% lead. If a vendor
> supplied
> solder that was actually Sn63Pb37, the melt point should be slightly
> higher
> than 183 degrees C. Maybe someone out there knows how much the melt
> temperature would be affected - It's been a while since I used the
> lever
> rule on a phase diagram. Would this small variation in composition be
> enough to explain your test results?
>
> Just curious.
>
> Dave Anderson
> Medtronic, Inc.
>
> >>> Kathy Palumbo <[log in to unmask]> 03/24/98 07:17pm >>>
> Ed,
>
> We recently did some Solder Paste qualification testing. Part of the
> test was to check the eutectic point of the solder. Out of the ten
> solder pastes we evaluated, there was only three that melted at the
> right eutectic point (183 degrees C). They were OMG (formally known
> as
> SCM), Qualtek, and Alpha Metals. I am not sure what the metal content
> was of the other 7 brands, but it was not Sn63Pb37. I wonder if this
> would be a sign of using recycled solder?
>
> We did recently change our solder paste supplier, and as a result we
> are
> seeing an improvement in our first pass yields. They have shot up a
> full 1 to 1.5%. Our over all yield is now hovering around 98.8% to
> 99.1%.
>
> Kathy Palumbo
>
> > ----------
> > From: Ed Cosper[SMTP:[log in to unmask]]
> > Sent: Tuesday, March 24, 1998 11:43 AM
> > To: [log in to unmask]
> > Subject: [TN] FAb: Solderlevel
> >
> > I have been reading some articles lately on effects different solder
> > has on uniformity ( flatness ). I have also read where some solder
> may
> > be being sold as "pure" solder but in actuality the solder was
> blended
> > with recycled solder resulting in organic contaminates. Based on
> this
> > information I have 2 questions.
> >
> > 1. Has anyone found improved results by changing the solder
> supplier?
> > 2. If positive results where found, what solder did you change to?
> (
> > Please respond to this question off forum so as not to
> > invoke inappropriate advertisement)
> >
> > All helps is appreciated.
> >
> >
> > Ed Cosper
> > Director Quality Assurance and Engineering
> > Graphic Electronics Inc.
> >
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