TECHNET Archives

May 2003

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Condense Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Sender:
X-To:
Ofer Cohen <[log in to unmask]>
Date:
Thu, 29 May 2003 11:01:16 -0400
Reply-To:
"TechNet E-Mail Forum." <[log in to unmask]>, Lee Whiteman <[log in to unmask]>
Subject:
From:
Lee Whiteman <[log in to unmask]>
Content-Transfer-Encoding:
7bit
In-Reply-To:
Content-Type:
text/plain; charset="windows-1255"
MIME-Version:
1.0
Parts/Attachments:
text/plain (93 lines)
Ofer,

Following up on what Ioan said, there is a plethora of lead free
component finishes that are being marketed right now. Basically,
component manufacturers are selecting finishes which are being defined
by the market. I've seen Ni, Pd, NiPd, SnAg, SnAgCu, Sn being marketed.

In my experience, we have not found any material compatibility issues
with using them with SnPb solder or lead free solders (SnAgCu, SnAg,
SnCu, SnAgCuSb are the ones we tested). There has been a few papers
concerning lead contamination with lead free solders, but we have not
seen any negative effects.

Ioan is correct about the soldering temperatures. For example, SnPb
reflow soldering is performed at around 220C. Depending upon the alloy
used, lead free soldering can range from 240C to 260C. The resulting
solder joint will have a dull grainy appearance. Lead free solders do
not wet as well as SnPb so you may have to use a more aggressive
(active) solder flux and / or nitrogen in you soldering process to
improve wetting. However, using a more aggressive (active) solder flux
may require you using a more aggressive cleaning process to remove the
residues left from the soldering process which are baked on due to the
higher soldering temperatures.

Suggest that you consider monitoring the IPC's Lead Free forum for
additional details.

Give me a call off line if you want to discuss lead free soldering in
more detail.

Hope this helps.

Good Luck

Lee Whiteman
Senior Manufacturing Engineer
ACI
E-Mail: [log in to unmask] <mailto:[log in to unmask]>
Ph: (610) 362-1200 x208
Fax: (610) 362-1290



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ofer Cohen
Sent: Thursday, May 29, 2003 11:06 AM
To: [log in to unmask]
Subject: [TN] Combination Leadless and SnPb


Hi all,
Lately I receive messages from components manufacturers, stating they
are moving from Tin-Lead finish to lead-less finish (not specified which
one - my regular question that regularly is not being answered). Most of
the components are still with the SnPb finish, the PCBs Tg are 145 deg
C, unless I had a specific need (extra depth, for instance to move to
what is currently called high Tg (and in the future will probably be the
standard
boards) and the pastes are, of course, SnPb, hence would not survive the
higher soldering temperature needed to tickle the lead-less finish.

Should I modify the work processes? Should I wait? Are there any
workmanship/ reliability effects to these changes? Helppppppppppp...

Regards
Ofer Cohen
Quality Assurance Manager
Seabridge Ltd.

---------------------------------------------------
Technet Mail List provided as a free 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/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 1.8e
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/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
-----------------------------------------------------

ATOM RSS1 RSS2