It could and probably does but the total gas exchange rate is so high ( since it is not a closed system) that there is probably no deposition like there could be a closed system. Paul Paul Edwards Process Engineering [log in to unmask] Tel: 408-433-4700 FAX: 408-433-9988 Surface Art Engineering 81Bonaventura Dr. San Jose, CA 95134 DUNS: 944740570 CAGE/NCAGE: 1XZ48 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard Sent: Wednesday, August 31, 2005 10:37 AM To: [log in to unmask] Subject: Re: [TN] ENIG/ Immersion Gold Plating and Pre-baking & Solderability You mean like in a nitrogen reflow oven? :) -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Paul Edwards Sent: Wednesday, August 31, 2005 12:22 PM To: [log in to unmask] Subject: Re: [TN] ENIG/ Immersion Gold Plating and Pre-baking & Solderability Dave, In the vacuum baking environment, the vacuum is used to lower the partial pressure to 0 to increase the molecular diffusion of the water out of the laminate structure.. In your experiments, the gas(N2 or Ar), serves as a thermal transfer agent so gas filled baking would be more effective than the vacuum baking, if the thermal energy source were heating coils... If laminate absorbing IR sources were used instead, a vacuum bakeout would be more effective than a "dry" gas bakeout. Again assuming the thermal energy source is a heating coil, the ideal baking method would be to use "bone-dry" or -100F (1ppm) or better Ar, assuming that the moisture in the PCAs would not raise the moisture level within the total Ar load to 0F (800ppm)... I wouldn't use N2 because of molecular acid formation when the N2 reacts with H20 and static electric charging sources that could occur in high air flow environments... Paul Paul Edwards Process Engineering [log in to unmask] Tel: 408-433-4700 FAX: 408-433-9988 Surface Art Engineering 81Bonaventura Dr. San Jose, CA 95134 DUNS: 944740570 CAGE/NCAGE: 1XZ48 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman Sent: Wednesday, August 31, 2005 7:53 AM To: [log in to unmask] Subject: Re: [TN] ENIG/ Immersion Gold Plating and Pre-baking & Solderability Hi Bev! Exactly! And most folks who use a vacuum bake process just kick on the vacuum and away they go! They don't realize that the bake/vacuum recipe they have chosen might be impeding the removal of moisture. Dave Bev Christian <[log in to unmask] OM> To Sent by: TechNet [log in to unmask] <[log in to unmask]> cc Subject 08/31/2005 09:48 Re: [TN] ENIG/ Immersion Gold AM Plating and Pre-baking & Solderability Please respond to TechNet E-Mail Forum <[log in to unmask]> ; Please respond to Bev Christian <[log in to unmask] OM> The trick is to have the evaporation process (driving the concentration gradient) to be slow enough to not comsume all the heat available so that the water stays liquid. Bev RIM -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Vladimir Igoshev Sent: August 31, 2005 10:15 AM To: [log in to unmask] Subject: Re: [TN] ENIG/ Immersion Gold Plating and Pre-baking & Solderability Hi Dave, That is a nice example of an adiabatic process, but it's "slightly different" from "pumping" moisture out of a board. :-) I'm a bit surprised with the results of your experiments. I'd expect both process to complement each other and speed up the process: vacuuming - to maintain the concentration gradient (driving force) and heating - to speed up diffusion (and prevent moisture from "freezing" :-)). Regards, Vladimir Vladimir Igoshev, Ph. D. Senior Materials Researcher Research in Motion 451 Phillip St. Waterloo, ON, N2L 3X2 Voice: (+1) 519-888-7465, ext. 5283 Fax: (+1) 519-886-0863 E-mail: [log in to unmask] -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of David D. Hillman Sent: Tuesday, August 30, 2005 6:31 PM To: [log in to unmask] Subject: Re: [TN] ENIG/ Immersion Gold Plating and Pre-baking & Solderability Hi Richard! Just a word of caution - I did some experimenting a number of years ago to see if either baking or vacuum baking was more effective in removing moisture from a pwb. I expected that the vacuum baking would be the winner but the design of experiments results demonstrated that baking was more effective. The physical process of pulling a vacuum to remove water ends up playing with the change of state (liquid to gas, gas to liquid, etc) behavior which impacts the ability to remove water from the pwb. I did some research and found a need example of pulling a vacuum on a disk of water - the change of state from a liquid to a gas resulted in the formation of ice (not exactly the result anyone wants to achieve)! The research illustrated that with the right controls and a well characterized vacuum/heating recipe you can effectively remove moisture faster than just baking but in a practical sense, having a nitrogen or argon atmosphere with a typical baking process was just as effective and lower cost. Any moisture baking process is going to degrade the pwb solderability so avoiding baking if possible is the best option. Dave Hillman Rockwell Collins [log in to unmask] "Stadem, Richard" <Richard.Stadem@G D-AIS.COM> To Sent by: TechNet [log in to unmask] <[log in to unmask]> cc Subject 08/30/2005 08:27 Re: [TN] ENIG/ Immersion Gold AM Plating and Pre-baking & Solderability Please respond to TechNet E-Mail Forum <[log in to unmask]> ; Please respond to "Stadem, Richard" <Richard.Stadem@G D-AIS.COM> I do not know the answer to that, but it sounds like a good idea. I do know that back in the 70's a major military OEM used to regularly bake pwb's at 150 F (note F, not C) at a 1/2 gravity vacuum, and they claimed the moisture was not removed if they did not have the 1/2 gravity vacuum. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Creswick, Steven Sent: Tuesday, August 30, 2005 8:24 AM To: [log in to unmask] Subject: Re: [TN] ENIG/ Immersion Gold Plating and Pre-baking & Solderability Richard, Is it an approved/acceptable process to place the PWB's into a vacuum chamber at room temp? I would not hazard a guess as to how great of a vacuum for what duration, however. Just curious if it is done in the surface mount industry. Nothing gets any more simple than a dessicantor box though! Steve Creswick - Gentex Corp -----Original Message----- From: Stadem, Richard [mailto:[log in to unmask]] Sent: Tuesday, August 30, 2005 9:05 AM To: [log in to unmask] Subject: Re: [TN] ENIG/ Immersion Gold Plating and Pre-baking & Solderability Baking of ENIG plated boards may be a requirement in order to drive out moisture even though it can exacerbate a nickel oxide formation that is already started. But there are other options for moisture removal, including lower bake temperatures at longer times. You could even lease a precision scale and see at what length of time is required for simply putting the PWB into a drybox (a dessicator box such as McDry, not a nitrogen box) and allowing it to dry at room temperature for a period long enough to reduce the moisture content by 90% or more. J-STD-030 does state that the bake times and temperatures they list for components and pwbs are guidelines. If you can prove your bake process or dessication process is removing the moisture, then you are qualifying a lower temp and longer time. You will need to use a number of pwbs in order to do this, as there is some variation in weights caused by resin content, etc. But you should be able to show a reduction in the average of weights (mean weight). -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Chris Schaefer Sent: Friday, August 26, 2005 10:10 AM To: [log in to unmask] Subject: [TN] ENIG/ Immersion Gold Plating and Pre-baking & Solderability Does baking these types of plating affect solderability? If so what factors play a part (i.e. baking temperature, plating thickness, baking time, etc...). I know that if baked it can cause the Nickel Oxide layer to become less solderable if the plating process is Poor (thanks Richard S.). Is there is a factual study that proves that baking any type of gold plated boards in any way shape or form reduces the solderability and/ or reliablity of the joints/ product? I am trying to gather data to prove to management that baking is a bad decision with this type of plating and should never be performed. Also if a Gold Plated board of any type is suspect for high level moisture content - how do you remove the moisture "IF" baking is not acceptable? Chris Schaefer Suntron Corporation --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------------------------- This transmission (including any attachments) may contain confidential information, privileged material (including material protected by the solicitor-client or other applicable privileges), or constitute non-public information. 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