TECHNET Archives

December 2006

TechNet@IPC.ORG

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

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

Print Reply
Subject:
From:
"Stadem, Richard D." <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Stadem, Richard D.
Date:
Mon, 18 Dec 2006 15:28:01 -0600
Content-Type:
text/plain
Parts/Attachments:
text/plain (71 lines)
IPC can only provide guidelines to achieve an acceptable yield. If a
company can demonstrate that it has control over the solderability of
its components and pwbs such that it can achieve 6 sigma DPMO without
nitrogen, why would they be "required" to use nitrogen? If IPC were to
"require" nitrogen, how much of a ppm of oxygen is acceptable? While the
use of a nitrogen blanket is a good practice in most cases, many
companies find the decrease in DPMO is so small that it is not cost
effective to run nitrogen. There are many other variables that need to
be controlled, nitrogen is just one of the factors and it is not
anywhere close to being the most important, unless, of course there are
little or no controls put in place to preserve the solderability of the
parts and pwbs. Some ovens use nitrogen so excessively that they are
useless, so why bother to turn it on? Other ovens with a properly
designed reflow chamber use the nitrogen efficiently such that you can
achieve an O2 level of less than 75 ppm inside the reflow chamber,
without having to go through 10 billion liters of nitrogen per hour to
achieve that reading. This is why there is no "requirement" for
nitrogen.
Most of the newer solder pastes are actually formulated to do away with
the nitrogen requirement. If you are not using one, I would suggest you
get a sample and start performing a qualification.
As to tombstoning, it has been my experience that the addition of
nitrogen increases tombstoning (does not make it better), for the very
reason it improves the surface tension which leads to improved wetting.
In the industry, many companies turn off the nitrogen for assemblies
heavily populated with 0402's or smaller. This is a common practice.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Russ Nowland
Sent: Monday, December 18, 2006 12:07 PM
To: [log in to unmask]
Subject: [TN] Nitrogen usage

Hello Technetter's,

Sometimes in life you find yourself in a pickle and wonder how the heck
you got there.  It always brings me to that famous quote "It is hard to
soar with the eagles when you work with a bunch of turkeys".

I have a question:  I am working with and "MAJOR" EMS that does not use
nitrogen with either Sn/Pb or Pb-free reflow.  In this day and age I
have never heard of this.  They have it available but will only use it
if I require it.  At a price, of course. They don't seem to take into
account it will improve their yields as well.

Is there an IPC, NEMI, or any other standard that requires/recommends N2
usage for either Sn/Pb or Pb-free reflow process?

---------------------------------------------------
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
847-615-7100 ext.2815
-----------------------------------------------------

---------------------------------------------------
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 847-615-7100 ext.2815
-----------------------------------------------------

ATOM RSS1 RSS2