Andre,
Here's my take on things. Lead Free solders do not wet as well as SnPb.
So, if you use a more active flux to achieve the same level of wetting,
the more residues on the hardware, which could be hardened by the higher
soldering temperatures. The more residues, the more difficult it would
be to clean the hardware. You may have to go to a more aggressive
cleaning process than you normally would not need with SnPb.
Depending upon the flux chemistry used by the solder manufacturers, you
may find that the SnPb hardware is as clean as their SnPb counterparts.
However, you will have to confirm this in you process development
activities. For example, a few years ago, ACI checked on Lead Free
soldering cleanliness. We found that except for 1 supplier (the name has
been changed to protect the innocent and not to embarrass the guilty),
the hardware was as clean as SnPb. With that one supplier, we found a
high concentration of bromides. We discovered that the flux used was a
water soluble flux, which had good wetting, but left bromide residues on
the hardware. With the new flux technologies being developed, I'm sure
that solder manufacturers can achieve positive wetting without leaving
residues. Caveat Emptor - Let the buyer beware! For additional details
call me off line.
Hope this helps.
Good Luck.
Lee Whiteman
Senior Manufacturing Engineer
American Competitiveness Institute
E-Mail: [log in to unmask]
Ph: (610) 362-1200 x208
Fax: (610) 362-1290
This message is for informational purposes only and does not supersede,
modify, or create any agreements with ACI. Information contained in this
message does not bind ACI or its affiliates to any commitment, either
express or implied, unless ratified in writing by an authorized
representative.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Andre Leclair
Sent: Wednesday, May 12, 2004 9:57 AM
To: [log in to unmask]
Subject: [TN] Aqueous Washes & lead free
Morning all
I have been noticing lately a number of Wash manufactures advertising
their
machines for Lead Free assembly processes.
Are boards assembled using fluxes designed for the higher reflow temps
(Wave or SMT) harder to remove with older washes ?? or is this an
advertising gimic to try and sell new machines??
We currently have 2 older Westkleen (Triton IV & Formula 3MT) and are
looking at introducing a lead free line next yr.
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text
in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at:
http://listserv.ipc.org/archives
Please visit IPC web site
http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700
ext.5315
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
-----------------------------------------------------
|
