OSP coating is over a metal, usually Cu. It preserves the solderability by
inhibiting oxidation of metal; hence the name 'organic solder preservative'.
The bond that forms during soldering is still metal to metal and
intermetallic in nature. Rob Schetty's answer to the query clears the air.

Srinivas Chada, Ph.D.
Senior Materials Scientist
Motorola
Plantation, FL 33322
(954) 723-5293 (phone)
(954) 723-5584 (fax)
1-888-695-9053 (pager)


-----Original Message-----
From: Kirk D Mueller [mailto:[log in to unmask]]
Sent: Wednesday, July 12, 2000 1:28 PM
To: [log in to unmask]
Subject: Re: [LF] lead free terminations


     The short answer is that metal to metal bonds, through intermetallic
formation, are stronger, usually more reliable and more electrically
conductive than just about any other type.  For the long answer you'll need
to do some reading.  I suggest starting with these:

"Solders and Soldering" by Howard H. Manko,  published by McGraw-Hill Book
Co., Copyright 1979, ISBN 0-07-039897-6
 "Surface Mount Technology - Principles and Practice" edited by Ray P.
Prasad and published by Chapman & Hall, now known as Kluwer Academic
Publishers.

Kirk Mueller
Raytheon Systems Co.
El Segundo, CA






Chris Hunt <[log in to unmask]>@IPC.ORG> on 07/12/2000 09:46:51 AM

Please respond to "Leadfree Electronics Assembly E-Mail Forum."
      <[log in to unmask]>; Please respond to Chris Hunt
      <[log in to unmask]>

Sent by:  Leadfree <[log in to unmask]>


To:   [log in to unmask]
cc:
Subject:  [LF] lead free terminations


I am interested to learn why component terminations are all metal finishes
and haven't taken a leaf out of the PCB industry and used an organic
coating
as a solderability preservative.
Any offers?

Chris Hunt
NPL

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