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June 2010

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From:
"Thayer, Wayne - IIW" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Thayer, Wayne - IIW
Date:
Mon, 28 Jun 2010 07:54:36 -0400
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Unstable intermetallics, apparently due to Pb and Pd refusing to form any intermetallic compounds.  I recall the days of PdAg finishes on ceramic capacitors--SnPb eutectic solder had weird wetting characteristics where the joint would "bloat" far away from where the heat was applied.

I've also seen odd intermetallic behavior with Bi alloys.

Wayne

-----Original Message-----
From: Wenger, George M. [mailto:[log in to unmask]] 
Sent: Monday, June 28, 2010 7:34 AM
To: TechNet E-Mail Forum; Thayer, Wayne - IIW
Subject: RE: [TN] QFP short at top of the leads

Wayne,

What makes ENEPIG incompatible with SnPb solder?

Regards,
George
George M. Wenger
Andrew Solutions
Senior Principal FMA/Reliability Engineer
40 Technology Drive, Warren, NJ 07059
(908) 546-4531 (Office) (732) 309-8964 (cell)
[log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Thayer, Wayne - IIW
Sent: Monday, June 28, 2010 7:21 AM
To: [log in to unmask]
Subject: Re: [TN] QFP short at top of the leads

Need to know the metallurgy.  What is the lead plating spec, and what alloy are you soldering with?  Note that ENEPIG is incompatible with SnPb solder.

Wayne Thayer

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Rex Waygood
Sent: Monday, June 28, 2010 6:53 AM
To: [log in to unmask]
Subject: Re: [TN] QFP short at top of the leads

Are these virgin parts?
Are the leg to pad joints 'good'?
Rex

 Rex Waygood
Technical Manager

Hansatech EMS provides value manufacturing through engineering and
quality

Hansatech EMS Limited
Benson Road
Nuffield Industrial Estate
Poole
Dorset
BH17 0RY

+44 (0)1202 338200


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Iven, Jowan
Sent: 28 June 2010 10:08
To: [log in to unmask]
Subject: [TN] QFP short at top of the leads

Has anyone ever seen a QFP where shorts occur after soldering at the top
of the leads?
And the leads look pretty dull after soldering.  Any ideas?


A picture is available at
http://ipc-technet.groupsite.com/uploads/galleries/x/000/020/5ba/technet
01.jpg

Jowan Iven




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