TECHNET Archives

March 2010

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:
Hernefjord Ingemar <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Hernefjord Ingemar <[log in to unmask]>
Date:
Thu, 25 Mar 2010 09:02:21 +0100
Content-Type:
text/plain
Parts/Attachments:
text/plain (260 lines)
Guys, what is the general conclusion? Is it recommended to always use ionized method or is it enough with what most have, i.e. dry Nitrogen or just air? The opinions seem to diverge.

Inge 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Gene Felder
Sent: onsdag 24 mars 2010 15:50
To: [log in to unmask]
Subject: Re: [TN] air or nitrogen for drying

From ESD Handbook ESD TR20.20 section 2.5 "Virtually all materials, including water and dirt particles in the air, can be triboelectrically charged."  Per section 5.5.5 Tribocharging "Tribocharging from equipment can be caused by conveyer belts, hardware sliding on surfaces, and moving fluids
(sprays) or solids (sandblasters). Moving gases that are free of particulates, e.g. from air guns, fans, or heat guns do not tribocharge an insulator or conductor. If rapid air movement causes parts or dust particles to rub together, tribocharging might occur. Grounded conductive surfaces can tribocharge an insulative surface. An insulative surface can charge an ungrounded conductor, which is the greatest ESD hazard."

"There is sometimes a need to provide static control in a small defined area or location. This may be done to provide static control within production equipment, in mini-environments, or to facilitate particle removal from part of a product. Ionizers used for this purpose may be blow-off guns or nozzles that work with a supply of compressed air or nitrogen. They may use either nuclear, soft x-ray or any of the previously described types of corona ionization technology. It will be important to choose a method of ionization and cleanliness of the gas supply that is appropriate to the work area."
[ESD handbook ESD TR20.20 section 5.3.6.5.2.4 Point-Of-Use Ionization]

Gene Felder
[log in to unmask]


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Thayer, Wayne - IIW
Sent: 2010 - 03 - 24 6:52 AM
To: [log in to unmask]
Subject: Re: [TN] air or nitrogen for drying

Many thanks for the insight and observations on this subject.  This is VERY helpful!

Wayne

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Hernefjord Ingemar
Sent: Wednesday, March 24, 2010 8:45 AM
To: [log in to unmask]
Subject: Re: [TN] air or nitrogen for drying

Then it's the dust that builds up the charge by friction, and not the air in itself ? 
We did not succeed to cause any charges with either nitrogen or air. Maybe the speed of nitrogen was not enough. If so, what is the gas flow limit which will cause electrostatic charge? Obviously, you dare walk with a board in your hand or open a door. Air is never standing still. And the gas speed is probably decreasing exponentially with the distance to the object. And depending on the air nozzle diameter and geometry. 

In some of our military electronic equipments that come home for modification or general service, we have found the boards covered with yellow dust from the desert. It's nearly impossible to stop it from getting in. The fans for cooling are blowing the dust across the boards day and night. Have never heard of ESD charging issues. 

Interesting. Has anyone had semiconductor (e.g. 0.3 V gates)issues caused by nitrogen blowing in the factory  or dust in field, as described above? 

Inge

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bob Landman
Sent: onsdag 24 mars 2010 13:13
To: [log in to unmask]
Subject: Re: [TN] air or nitrogen for drying

Googled the following:

ElectroStatic Discharge : PRACTICAL ANALOG SEMICONDUCTOR CIRCUITS Moving air can also generate substantial staticcharges. When you blow dust off your electronics their will be static generated. ...
www.allaboutcircuits.com/../1.html - Options


Moving air can also generate substantial static charges. When you blow dust off your electronics their will be static generated. An industrial solution to the problem to this issue is two fold: Firstly, air guns have a small, well shielded radioactive material implanted within the airgun to ionize the air. Ionized air is a conductor, and will bleed off static charges quite well. Secondly, use high voltage electricity to ionize the air coming out of a fan, which has the same effect as the air gun. This will effectively help a workstation reduce the potential for ESD generation by a large amount.

-Bob Landman

Sent from my iPhone

On Mar 24, 2010, at 5:14 AM, Mike Fenner <[log in to unmask]> wrote:

> I'm not an ESD expert... so treat the following with caution, as it 
> may not be the same situation.
>
> A similar concern was raised by a customer after I recommended forced 
> air cooling after reflow. "Floating body charging" or similar words.
> Not being an expert and thinking this could be of more general 
> concern, I got a static expert and his gear and we spent an 
> interesting few hours with meters, ionizers, blowers, factory airlines 
> and so on and found .....
> nothing.
> We rationalised that the stream carrying charges to the work, would 
> similarly allow a path from the work. That accidental gas ionizing was 
> no different (apart from the cash) to deliberate ionising.
>
> Does this make sense?
>
>
>
> Regards
>
> Mike
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Thayer, Wayne - 
> IIW
> Sent: Tuesday, March 23, 2010 9:51 PM
> To: [log in to unmask]
> Subject: [TN] air or nitrogen for drying
>
> We have a number of "airbrush" low pressure nozzles around here for 
> spraying solvents on reworked boards and for drying them off.  I know 
> that nozzles can create static, but I have had no problems to date and 
> have had no problem with dust sticking to the boards when I dry them 
> off this way.
>
> I haven't been able to find anything on trying to quantify static from 
> nozzles used in this way.  Does anyone have data?  Moving to ionized 
> blow-off for drying the boards would be painful, as that means yet 
> more equipment in our small cleaning stations.
>
> Wayne Thayer
>
> ________________________________
> This e-mail and any files transmitted with it may be proprietary and 
> are intended solely for the use of the individual or entity to whom 
> they are addressed. If you have received this e-mail in error please 
> notify the sender.
> Please note that any views or opinions presented in this e-mail are 
> solely those of the author and do not necessarily represent those of 
> ITT Corporation. The recipient should check this e-mail and any 
> attachments for the presence of viruses. ITT accepts no liability for 
> any damage caused by any virus transmitted by this e-mail.
>
> ______________________________________________________________________
> This email has been scanned by the MessageLabs Email Security System.
> For more information please contact helpdesk at x2960 or 
> [log in to unmask] 
> ______________________________________________________________________
>
> ---------------------------------------------------
> Technet Mail List provided as a service by IPC using LISTSERV 15.0 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
> -----------------------------------------------------
>
>
> ***This email, its content, and any files transmitted with it, are 
> intended solely for the addressee(s) and may be legally privileged 
> and/or confidential. If you are not the intended recipient, please 
> contact the sender by return and delete the material from any 
> computer. Any review, retransmission, dissemination, or other use of, 
> or taking of any action in reliance upon this information by persons 
> or entities other than the intended recipient is prohibited.
>
>
> ______________________________________________________________________
> This email has been scanned by the MessageLabs Email Security System.
> For more information please contact helpdesk at x2960 or 
> [log in to unmask] 
> ______________________________________________________________________
>
> ---------------------------------------------------
> Technet Mail List provided as a service by IPC using LISTSERV 15.0 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
> -----------------------------------------------------
>

______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0 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
-----------------------------------------------------

______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
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
-----------------------------------------------------

______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
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
-----------------------------------------------------



______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
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
-----------------------------------------------------

______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
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