Question on Nitrogen Consumption during Reflow

Yer welcome.

The cats & kitties at SMTnet like to keep us guessing. [I don�t think they did well in �dodge-ball� in their younger years.] They offer two "search tools" at the top of the page and each produces substantially different results. I used the one from the blue button => 49 hits on nitrogen, you probably used the one with the entry window => 13 or whatever hits on nitrogen. Here is my take on what you missed by using the other seach:

Date: May 26, 2001 04:57 AM Author: Brian Sloth Bentzen Subject: Nitrogen Reflow

Dear Frang.

The right O2 level are mostly determined by the products you produce (E.i. PCB surface and component solderability).

In reflow I would say the window is between 100 and 1000 ppm, depending on the issues above. Personal I choose a maximum O2 level on 500 ppm for my Ersa Hotflow 7.

You can read more about my considerations in my article on Nitrogen in reflow soldering on: http://www.smtinfocus.com/technical_papers_list.html

Date: May 24, 2001 03:07 PM Author: caldon Subject: Nitrogen Reflow

You should be able to get assistance from http://www.airliquide.com/us/ep&a/TechPapers.htm

Caldon W. Driscoll ACI USA 610-362-1200 cdriscoll@aciusa.org

Date: December 21, 2000 01:08 AM Author: Bentzen Subject: Re: N2 vs. Air Reflow Soldering Check out my article about reflow soldering in nitrogen atmosphere on http://www.smtinfocus.com Hopefully you will find some answers and more detailes on my web-site.

Date: May 23, 2000 08:37 PM Author: Dave F Subject: Re: Nitrogen reflow

Gabby: Trying to avoid accusations of plowing new ground eh?

Inert soldering: R Curthers et al, "Optimizing A No-Clean Circuit Board Process Using Nitrogen Inerting In A Conventional Wave Solder Machine," NEPCON West 1991 T Walsh, "The benefits Of Establishing A No-Clean Wave Solder System In Reducing Soldering Defects," NEPCON West 1991 G Schouten, "Benefits Of Inert Gas Soldering In Reducing Soldering Defects," NEPCON West 1991 H Hartmann, "Nitrogen Atmosphere Soldering," Circuits Assembly 2 (1), 60-66, 1991

SEHO was the first company to produce machines with nitrogen inerting. Now, all machine suppliers do. Check with machine suppliers. Also, check with inert gas suppliers. Some of them talk about retrofitting older machines.

Good luck Dave F

Date: October 16, 2000 08:33 PM Author: Dave F Subject: Re: N2 reflow

MK: If you are getting good product with air, here�s what you should do: * Turn off the N2. * Sell that N2 cracker machine. * Pat yourself on the back. * Go out for beers. [Not any of that Canadian Fosters crap, tho][Did you know that Ozzies don�t even drink that stuff???? Right, Dreamster????] * Live well and live long.

Now, if that�s not the correct answer, here�s some thoughts: * Is 900 ppm your N2 purge rate? What is the duration of your purge? * Is 1000 ppm your O2 maintenance level? If so, that�s approaching "thin" * Is someone turning the N2 off? * Are your N2 curtains in place and working properly?

Think about: * Checking Marc and Earl�s comments on N2 reflow in the fine SMTnet archives. Altho, there does seem to be an echoecho inin herehere * Talking to techietypes at BTU * Searching SMT Magazine. There�s at least 20 nitrogen soldering articles on their site. * "Circuits Assembly" lists the following as Top 100 Articles: - Nitrogen Atmosphere: Who Needs It? By Dr. L. Lawton July 1998 - Reducing the Cost of Inert Soldering By M. Theriault and P. Blostein July 1998 * SMTA Journal - Inerting The Wave Soldering Process With Membrane-Generated Nitrogen, C. Shea 09/12/1999 - Solderability Of Different Board Finishes Under Nitrogen Atmospheres With Different Rols, J. Tauchmann 09/12/1999 - Solderability Of Printed Wiring Boards With Organic Solder Preservation Under Nitrogen Atmosphere, T. Zachert 08/23/1998 - Technical Advance Improves Reflow Process Reliability And Consistency, B. Bailey 04/28/1997 - Reducing Solder Defects Under Nitrogen With Varying Oxygen Concentrations, H. Hsiao 04/28/1997 - Implementation And Production Test Results Of A Closed Loop Control Of Atmospheres For Soldering, N. Saxena 09/10/1996

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