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Subject:
From:
Ken Patel <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 28 Mar 2000 15:25:20 -0800
Content-Type:
text/plain
Parts/Attachments:
text/plain (116 lines)
Bev,
You are right in catching and educating me on Alloy 42, lead material v/s
plating. As the data sheet doesn't show the lead material & plating for 44
pin TSOP, I have assumed that the plating will be same as 32 pin TSOP which
is copper leads.

We do not see any failure visually using regular microscope, it's a big
problem for us on this thin TSOP. If any of our technetters has found
similar situation and how it was resolved will help us in getting at the
bottom of the problem. I have asked Cypress for lead related info with type
of plating and will ask our test guy if they can nail it down to particular
pin for further microscopic inspection.

re,
ken patel

At 02:19 PM 3/28/2000 -0500, Bev Christian wrote:
>Ken,
>First I don't think you really mean to say the part leads are made with
>eutectic solder or Alloy 42.  The leads are either Alloy 42 or copper, with
>a lead finish of eutectic solder, other tin/lead solder alloy or maybe even
>TI palladium.
>
>So you have sufficient pads size for good fillets, good soldering of other
>parts, good profile and heel fillets.  Hmmm.  My question would then be, do
>the failures look like the lead has pulled right out of the fillet, with
>bare lead frame material showing.  If this is the case and the leads are
>indeed Alloy 42, then this has been seen before, is related to the final
>processing of the Alloy 42 and I think has been discussed here on TechNet.
>Check the archives.
>
>regards,
>Bev Christian
>XLTEK
>
>-----Original Message-----
>From: Ken Patel [mailto:[log in to unmask]]
>Sent: March 28, 2000 1:27 PM
>To: [log in to unmask]
>Subject: [TN] Solderability of TSOP...
>
>
>Guys,
>We have encountered problem related to component solderability, looks like!
>We are using Cypress Semi TSOP (SRAM-SM 71016 64kx16, ASYNC TSOP-44). This
>part has very small foot area which make a direct contact with the pad on
>the boards.
>
>The problem we have encountered is that many boards fail at ICT but will
>pass once we touch it up using solder iron. Solder at the TSOP location
>looks good and also in the surrounding vicinity. I do not see any profile
>problem. There is no toe fillet but I can see the heel filet rising on the
>lead. Pads are designed longer so that parts made by others can fit too.
>
>What can be possible causes of the problem? I tried look at the WEB but
>looks like parts are made using eutectic solder and not Alloy 42 but can't
>ruled out it was not specifically mentioned.
>
>
>re,
>ken patel
>______________________________________________________
>Ken Patel                       Phone:  (408) 490-6804
>1708 McCarthy Blvd.             Fax:    (408) 490-6859
>Milpitas, CA 95035              Beeper: (888) 769-1808
>
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______________________________________________________
Ken Patel                       Phone:  (408) 490-6804
1708 McCarthy Blvd.             Fax:    (408) 490-6859
Milpitas, CA 95035              Beeper: (888) 769-1808

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