Lou, here is my 2 cents worth,  I was taught early on that if you take a
component lead made of copper and dip it into a solder bath of tin/lead that
some of the copper from the lead will be left in the solder bath.  Also more
tin will leave the solder bath than will lead.  Tin and copper like each
other and that is why we have the intermetallic growth in solder
connections.  You supposedly can measure a lead (copper) and measure it
after dipping it in a solder bath and it will measure smaller and the length
of time in the bath will have effect. If you leave the lead in there long
enough it will dissolve or become part of the bath.  Jon

 -----Original Message-----
From:   Lou Hart [mailto:[log in to unmask]]
Sent:   Wednesday, December 06, 2000 2:03 PM
To:     [log in to unmask]
Subject:        [TN] Copper contamination is wave solder

TechNetters,

I've made SPC charts to track tin, copper, gold, and antimony in our wave
solder machine.  The operator skims dross from the solder pot every morning.
We send a solder sample the first of each month to Kester for analysis.
Over the past 7 months, there has been a monotonic increase in copper
concentration and the past two months have been above the upper control
limit.  The copper concentration is still well within spec (0.3%, if I am
correct, according to the relevant IPC standard) at 0.14%, but I want to
make sure we know what is happening.

Any comments on these observations?  Some years back I had charts for a HASL
machine and over perhaps 12 months the semimonthly copper concentration
wandered between 0.21 and 0.24 %.

Lou Hart

----------------------------------------------------------------------------
-----
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
Search previous postings at: www.ipc.org > On-Line Resources & Databases >
E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or 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 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------