Hi Terry,

TI publish a useful "Palladium Finish User's Manual" which may give you
more information on palladium lead finish on components. According to
this, the finish is as follows (viewed with Cu leadframe at bottom of
list/outer layer at top):
        Palladium min 3u" (0.075micron)
        Nickel Plate 40 - 60u" (1.0 - 1.5micron)
        Palladium/Nickel Strike max 5u" (0.125micron)
        Nickel Strike max 5u" (0.125micron)
        Cu. Base Leadframe

The key role of the palladium is to protect the underlying layer of
nickel from oxidation during storage/assembly. The palladium dissolves
into the solder joint, and these joints can look significantly
different to those made to a solder dip finish leadframe.

The exact role of the underlying Palladium/Nickel Strike and Nickel
Strike layers I am not sure. Perhaps other TechNet Minds can advise?

Hope this helps,

Clive ffitch
Matra BAe UK
Stevenage, England

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]
Sent: 27 June 2000 08:51
To: [log in to unmask]
Cc: [log in to unmask]
Subject: [TN] Palladium query


                   *** WARNING ***

This mail has originated outside your organization,
either from an external partner or the Global Internet.
     Keep this in mind if you answer this message.


Fellow TechNetters,

Can someone please enlighten me as to the purpose of a Palladium
Barrier on
components / PCBs.

Best regards

Terry Exell
BAE SYSTEMS, Plymouth, UK

##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with
following text in
the body:
To subscribe:   SUBSCRIBE TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
additional
information.
If you need assistance - contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
##############################################################

##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in
the body:
To subscribe:   SUBSCRIBE TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information.
If you need assistance - contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
##############################################################