hi,

palladium is not normally thought of as a barrier layer.  like gold, it can be used to preserve the solderabilty of a true barrier layer (nickel for example).  that nickel barrier layer is used to prevent copper from migrating to the surface and impeding the soldering process.

in the '70s, palladium was considered (and even used by ibm) as a substitute for gold on card edge connector fingers.  gold was unusually expensive at that time.  although palladium was more expensive per ounce it is much less dense than gold (12.0/19.3).  thus for a given thickness (which is what counts) less palladium (per ounce) is required.  this more than made up for the higher cost per ounce of palladium.

confused?  so am i.

phil

-----Original Message-----
From: Victor Arghyrou [mailto:[log in to unmask]]
Sent: Thursday, June 29, 2000 7:37 AM
To: [log in to unmask]
Subject: [TN] Palladium Barrier


With regard to surface mount components/boards can anyone enlighten me as to the
purpose of a palladium barrier.  A short statement is all that is required.

Thanks in advance.
Victor Arghyrou

##############################################################
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
##############################################################