Thanks for the clarification Steve, yes, I mean reliability issues.
Rob Schetty
-----Original Message-----
From: Stephen R. Gregory <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Friday, June 05, 1998 3:27 PM
Subject: Re: [TN] Components - Exposed Cu on Component Lead Ends


>In a message dated 6/5/98 11:15:10 AM Pacific Daylight Time,
>[log in to unmask] writes:
>
>>
>>  Can anyone direct me to a technical reference detailing the work done to
>>  show that exposed copper on component lead ends do not pose a
solderability
>>  problem?
>>
>>  I've searched the Technet Archives but only found vague references to a
>>  Battelle paper with no further details.
>>
>>  Thanks in advance for any responses.
>>
>>  Rob Schetty
>>  LeaRonal Inc
>>  Freeport NY  USA
>
>Hi Rob,
>
>     Don't you mean exposed copper on lead ends doesn't pose a RELIABILITY
>problem? Because it definately poses a solderability problem. Many times
when
>the cut and form is done on QFP devices, the toe of the leads will have
>exposed copper that solder has a difficult time wetting to...sometimes it
>will, and sometimes it won't. But it's not a problem.
>
>      I've read a few articles in SMT magazine before where there's been
>stress testing performed on leads that had toe fillets and ones that
didn't,
>there was no appreciable difference in the strength or reliability of the
>joint between the two. The article I remember was written by two engineers
>from Micron.
>
>      Also in J-STD-001B on page 18, paragraph 9.2.5.3 it states: Exposed
>Basis Metal - Incomplete solder wetting at the tip of through-hole
component
>leads, and the edges and/or periphery of printed board lands and conductors
is
>acceptable. Exposed basis metal on component lead ends is permissible.
>
>-Steve Gregory-
>
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