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Mike Demos

#9114

Mil-P-28809 | 7 October, 1999

Is anyone aware of a web page for military spec's? I am looking for Mil-P-28809.

Thanks, Mike Demos

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#9115

Re: Mil-P-28809 | 7 October, 1999

| Is anyone aware of a web page for military spec's? I am looking for Mil-P-28809. | | Thanks, | Mike Demos | Mike: My usual source, DSCC Columbus, gave this response to a search on "Mil-P-28809"

Search Mil Specs & Drawings No basic specs, Standards, Handbooks, or CIDs found with DocNumber Contains 'Mil-P-28809'. No subordinate specs found with DocNumber Contains 'Mil-P-28809'. No DSCC Drawings found with DocNumber Contains 'Mil-P-28809'. No SMDs found with DocNumber Contains 'Mil-P-28809'.

Then again, that was their database.

1 Your document may not be under DSCC cog 2 As you know the military is obsoleting documents

Good luck

Dave F

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#9116

Re: Mil-P-28809 | 7 October, 1999

The last time I worked with this spec (and it has been a while) it was MIL-C-28809, not 'P'. Try searching for that. There is a good chance this document has been obsoleted in favor of an IPC spec. Good luck.

Bob

| Is anyone aware of a web page for military spec's? I am looking for Mil-P-28809. | | Thanks, | Mike Demos |

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Scott S. Snider

#9117

Re: Mil-P-28809 | 7 October, 1999

| Is anyone aware of a web page for military spec's? I am looking for Mil-P-28809. | | Thanks, | Mike Demos | I'm trusting my memory on this which often times leads me astray.. Didn't that spec have something to do with cleaning. It seemed the only time I ever referenced it had to do with someone questioning OmegaMeter results. I thougth the spec was thrown away during the big Freon scare/conversion.

Scott S. Snider

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Brian

#9118

Re: Mil-P-28809 | 8 October, 1999

| Is anyone aware of a web page for military spec's? I am looking for Mil-P-28809. | | Thanks, | Mike Demos | MIL-P-28809 is definitely obsolete. Not only obsolete, it was possibly the most scientifically flawed standard ever to to be printed. It allowed contamination levels to be "adjusted" by whoever interpreted it over a range of over 10:1. My advice is forget it. The UK military spec DEF-STAN 00/10-3 was considerably better.

Both the above, and those parts incorporated into later documents applied ONLY to through-hole assemblies. There have been no revisions since which covers the requirements of SM assemblies. The IPC document effectively gives a generalised test method covering all types of commercial instrument, but is not really of much value. The limit value is to be decided in-house for each application.

When my company was making the Contaminometer (now made elsewhere under licence), we made the following recommendations as a first guideline to obtain a reasonable reliability for circuits before coating and uncoated: Through hole spacings down to 0,5 mm : 1,5 �g/cm2 eq. NaCl below 0,5 mm : 1,3 �g/cm2 eq. NaCl SMDs without components larger than SOIC16 : 1,0 �g/cm2 eq. NaCl larger than SOIC14 or closer than 0,3 mm : 0,75 �g/cm2 eq. NaCl

The user was recommended to up or down these limits according to individual circumstances.

Brian

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Mike Demos

#9119

Re: Mil-P-28809 | 11 October, 1999

Thank you all for your replies. I guess my age in this industry is showing. This military spec. does not appear to be in existance. So, let me make my request a little more to the point:

Is anyone aware of a specification specifically referencing the Zero Ion ionic contamination system? I recall an equivalency factor that showed "acceptable" limits of contamination for Zero Ion and the Omega Meter SMD. If I recall correctly, the amount for the Zero Ion was 37 micrograms per sq. inch.

Thanks, Mike.

| Is anyone aware of a web page for military spec's? I am looking for Mil-P-28809. | | Thanks, | Mike Demos |

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#9120

Re: Mil-P-28809 | 11 October, 1999

| Thank you all for your replies. I guess my age in this industry is showing. This military spec. does not appear to be in existance. So, let me make my request a little more to the point: | | Is anyone aware of a specification specifically referencing the Zero Ion ionic contamination system? I recall an equivalency factor that showed "acceptable" limits of contamination for Zero Ion and the Omega Meter SMD. If I recall correctly, the amount for the Zero Ion was 37 micrograms per sq. inch. | | Thanks, | Mike. | Mike: Contact: Mike Konrad (Aqueous Technologies) at (800) 218-8128. Mike Konrad is a frequent visitor at SMTnet. You can probably find his e-mail address, if you prefer. Ta. Dave F

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#9121

Re: Mil-P-28809 | 11 October, 1999

| | Thank you all for your replies. I guess my age in this industry is showing. This military spec. does not appear to be in existance. So, let me make my request a little more to the point: | | | | Is anyone aware of a specification specifically referencing the Zero Ion ionic contamination system? I recall an equivalency factor that showed "acceptable" limits of contamination for Zero Ion and the Omega Meter SMD. If I recall correctly, the amount for the Zero Ion was 37 micrograms per sq. inch. | | | | Thanks, | | Mike. | | | Mike: Contact: Mike Konrad (Aqueous Technologies) at (800) 218-8128. Mike Konrad is a frequent visitor at SMTnet. You can probably find his e-mail address, if you prefer. Ta. Dave F | Maybe that's not the correct direction. Let's try a different angle:

1 ANSI-J-001A, MIL-P-28809, MIL-STD-2000: LT 10.07 �gm/sg in NaCl equivalent 2 Bellcore TR-NWT-000078: LT 6.5 ugm/sq in NaCl equivalent

The conversion: 1 ugm/sq cm = 0.1550 X ugm/sq in

Trying yet a different tact: EMPF published "An In-Depth Look At Ionic Cleanliness Testers" (RR0013) 8/93. It compares various ionic contamination testers. You might be able to devine a conversion between Zero Ion and the Omega Meter SMD, if that's what you're trying to accomplish.

I'm done

Dave F

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Brian

#9122

Re: Mil-P-28809 | 12 October, 1999

| Thank you all for your replies. I guess my age in this industry is showing. This military spec. does not appear to be in existance. So, let me make my request a little more to the point: | | Is anyone aware of a specification specifically referencing the Zero Ion ionic contamination system? I recall an equivalency factor that showed "acceptable" limits of contamination for Zero Ion and the Omega Meter SMD. If I recall correctly, the amount for the Zero Ion was 37 micrograms per sq. inch. | | Thanks, | Mike. | | | Is anyone aware of a web page for military spec's? I am looking for Mil-P-28809. | | | | Thanks, | | Mike Demos | | | | Mike

I think that it was in 1978 that MIL-P-28809B introduced the notion of so-called equivalency factors for a limited number of commercial instruments. This was done by a totally artificial test method (the test boards were not even soldered, so the flux was raw) to try and equate the results to the already extremely flawed reference method.

Shortly afterwards, the UK Ministry of Defence attempted to do something similar to their reference method, which was much better than the US one, with many more parameters defined (but still not perfect). They were not able to do so, because different test boards gave widely different results. Because of this, the MoD refused to depart from their reference method (which was practical, based on a Swiss instrument, but could be determined in a lab without the instrument, albeit laboriously). This was incorporated in DEF-STAN 00/10-3 (1986). For the anecdote, the scientists at HMS Aquila research labs called the equivalency factor the "fiddle factor".

I'm not sure of the exact date - probably about 1982 - the European Space Agency (ESTEC in Holland) commissioned the IVF in Sweden to evaluate instruments and equivalency factors. They did a whole matrix of tests round several instruments and 5 or 6 flux types and cleaning methods, with a single test board. Interestingly, they found that the equivalency factors between instruments could vary according to the flux type and cleaning method by as much as a whole order of magnitude. Furthermore, if Instrument I gave a considerably higher reading than Instruments II and III when measuring a board with components soldered with Flux A and cleaned in Solvent X, it could be I II when using F B and S Y and I III with F C and S X (I think there were only two solvents in the matrix). In the conclusion of the long report (Bergendahl, C.G., and Dunn B.D. 'Evaluation of Test Equipment for the Detection of Contamination on Electronic Circuits", European Space Agency Technical Memorandum ESA STM-234, Paris [1984]), it is clearly stated that equivalency factors are totally meaningless.

Furthermore, the instruments used for determining them in the 1970s are no longer made and have been replaced by much better ones. If the flawed 1970s tests were repeated with today's instruments, even bearing the same trade names, the results would be VERY different, indeed.

I'll also state that the fiddle factors were determined long before SM techniques became the norm and take no account of modern manufacturing processes.

My advice is therefore to forget that these fiddle factors ever existed and determine your own limit value according to your process and your instrument.

Brian

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