Corre . That is what I mentioned about 'surface charges' which ones can
cause real disaster. Use to take place in the chip passivation, either in
the primary oxide or in the added polymeric layer. Of what I have read, the
semi manufacturers do not apply the highest range of dielectric today, but
use a slighly doped passivation. Don't remember what Ohm cm. If this is the
case, maybe you need not be afraid of using ordinary nitrogen even on such
chips or wafers. Right?
Inge
--------------------------------------------------
From: "Thayer, Wayne - IIW" <[log in to unmask]>
Sent: den 25 March 2010 04:34
To: <[log in to unmask]>
Subject: Re: [TN] air or nitrogen for drying
> I hope everyone realizes I was generalizing! The caveat is that I assume
> you are drying off an assembly, post soldering, that was designed for a
> typical office or outside environment, where a bit of static charge won't
> cause a failure. If this doesn't apply, for instance if you are blowing
> at something like GaAsFET LNAs designed without protection, then you will
> need much tighter controls!
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Thayer, Wayne - IIW
> Sent: Thursday, March 25, 2010 7:18 AM
> To: [log in to unmask]
> Subject: Re: [TN] air or nitrogen for drying
>
> Hi Inge!
>
> The way I've decided to interpret the consensus is that if there are no
> particulates in the gas stream then there should be no static generated by
> the blow off. However, there is concern that using an insulative or
> ungrounded nozzle could build up a charge for the random particle which
> happens to get through the nozzle anyway, so grounding is recommended and
> also checking using static sensing equipment, particularly if the RH<50%.
>
> Wayne
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Hernefjord Ingemar
> Sent: Thursday, March 25, 2010 4:02 AM
> To: [log in to unmask]
> Subject: Re: [TN] air or nitrogen for drying
>
> 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
> -----------------------------------------------------
>
> ______________________________________________________________________
> 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
-----------------------------------------------------
|
