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jneutron
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Re: centroids..

Hmmm...lets break this post down step by step, and see what has actually been said...


Quote:
Well, it sounds like you probably barely passed the 3rd semester of basic physics; congratulations on some rather confused knowledge of some basic EM theory.


Denigration #1...an attempt at stepping on another without actually discussing technical content. did you think we'd miss the fact that you didn't speak on the technical??

Tell us, wise sage...what was confusing to you?

Quote:
If you ever want to sign up for some of my graduate courses in electrical engineering, we MIGHT be able to improve your knowledge in some of the areas you seem to be so theoretically weak in.


Denigration #2...another attempt at stepping on another without actually discussing technical content. you're on a roll here.

Quote:
The essential difficulty is that while you seem to have some understanding of the basic principles, when you attempt to apply them in a meaningful way to a specific case, your arguments become confused and ramble hopelessly.


Denigration #3...an attempt at stepping on another without actually discussing technical content. and again, no technical content.??

Quote:
Throwing around a bunch of ill-conceived and highly questionable allegations couched in technical terms is not strengthened by citing a few non-relevant technical references; this does not impress anyone except the ignorant, so it might be wise to give up the attempt.

Denigration #4...another attempt.

Quote:
P.S.-(since you asked) My field is communications systems; Motorola and other companies frequently employ me as a consultant in systems design and propagation studies, especially in relation to antenna design for cell sites and large-scale public-safety radio systems in urban areas. Another specialty is intermodulation issues as they affect encrypted audio transmissions for public safety communications (police, fire etc.).


Good to know.

Quote:
As an antenna design engineer, the idea that YOU would try to lecture me in electromagnetic theory (upon which I have lectured for hundreds of hours) is an incredible joke


Then why do you have absolutely no knowledge of EMC theory or applications?? You do realize I used common terms from EMC, don't you? The fact that you know nothing about it would scare me if I were a possible customer of yours.

Do you offer rebates to your students when they realize they do not have any learning on EMC, or do you just consider it somebody elses problem? Tom Van Doren makes a good living off guys like you...

Had you actually demonstrated by discussion any understanding of the topic at all in your post, you'd have even a modicum of credibility. As it appears, you are deathly afraid to discuss any technical, lest somebody else correct you with accurate information. Be afraid...

All you posted was drivel..one liners in an attempt to garner an advantage over another.fluff dude, all fluff...but no stuff..

Try to discuss the topic...leave the animosity elsewhere. Your tactic is unbecoming a professional, if that is actually what you are.

Cheers, John

jneutron
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Re: hmmm


Quote:
Re your question on the soldering course:

I took the course when employed by the Autonetics division of North American Aviation/Rockwell Corp. in the 1960s, in Los Angeles and then Orange counties. For a couple of years I was employed in the department where the Minuteman II ICBM D37 flight computers were functionally tested, and later in a department where Apollo flight electronics were assembled and tested for NASA. (interestingly, I went to an Air Force museum near Great Falls, Montana a few years ago, and they had one of those Minuteman II computers on display; they were still in use until around 1990, when they were replaced by a new generation flight computer using much more modern integrated circuit technology...the integrated circuits in the Minuteman II were the first ever produced on a production basis, and they were primitive by today's standards)

Tin/Indium solder was used for flow-soldering connectors to circuit boards (due to its low melting point; there were severe problems trying to prevent the delamination of multi-layer boards...the master interconnect board of the computer had 28 layers with 23 80-pin connectors soldered to it, and this was new technology at the time...). Conventional tin/lead solder was used to attach components to boards.

Nice, thank you.

How did they handle the visual criteria for the tin/Indium? It never gets shiny, and all the inspectors I taught really got "frosted" at the new criteria.

Were the joints over bare copper, or was there gold over nickle flash? Many of the cryo guys here just want to use indium over copper, and I worry about the intermetallic growth (Kirk' voiding) popping the lap joints. We also have issues with electromigration on the laps, as our current densities can run exceedingly high, 10 power 4 or 5 per square mm..

Cheers, John

commsysman
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Re: centroids..

I have been PAID for over 30 years by a major university to lecture on the subjects you CLAIM I know nothing about.

I have been repeatedly PAID by Motorola and several other communications companies, over a period of 30 years, for my expertise in a field that you CLAIM I know NOTHING about. I guess they should be consulting you, not me; you seem to be the expert. I strongly suggest that you apply to them, as a self-proclaimed expert in the field, and see what they think of YOUR credentials; let me know what kind of success you have!

Isn't it amazing that I can impress hundreds of experienced engineers and thousands of students with my expertise, and yet YOU claim I know nothing about my field?

It does not take a great leap of logic to determine whose credibility is lacking here; I am on solid ground and you are a loose cannon with only a lot of uninformed rhetoric and a loud mouth to back him up. Say all you want; I will reply to your ridiculous CLAIMS no further.

commsysman
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Re: hmmm

All of the circuits were gold on the surface when soldering took place. I have no way of knowing if other metals underlay the gold, since I never had anything to do with circuit board production.

ncdrawl
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Re: hmmm

jn2, you can post pics..you cannot attach them, but you can use the [image][/image] code to post website-hosted images..

jneutron
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Re: centroids..


Quote:
I have been PAID for over 30 years by a major university to lecture on the subjects you CLAIM I know nothing about.

That sentence in itself is worthless. I can fly just by flapping my arms..

Besides, I've not claimed you know nothing. I've stated that you have displayed none via any discusssion.. You have repeatedly diverted away from any technical content whatsoever with repeated attacks... The fact that you do not discuss anything of a technical nature on this topic speaks reams.

Quote:
I have been repeatedly PAID by Motorola and several other communications companies, over a period of 30 years, for my expertise in a field that you CLAIM I know NOTHING about.

hmm...motorola has paid you for EMC work?? Prove it..

Quote:
I guess they should be consulting you, not me; you seem to be the expert.


Initially, for any EMC consultation, I apparently know quite a bit more than you. You don't even know what the words mean, you called it "gobbledygook". To me, that would immediately remove you from the long list of potential experts. I would remove my name from the short list of experts remaining, as it would be far better for them to hire Tom Van Doren, or Henry Ott. AS PER MY RECOMMENDATIONS TO YOU...


Quote:
Isn't it amazing that I can impress hundreds of experienced engineers and thousands of students with my expertise, and yet YOU claim I know nothing about my field?

You haven't demonstrated any expertise. All you've done is verbal attacks..diverting away from any technical..


Quote:
It does not take a great leap of logic to determine whose credibility is lacking here; I am on solid ground and you are a loose cannon with only a lot of uninformed rhetoric and a loud mouth to back him up.


Again, I put up three posts with much detail...if you believe it inaccurate, show the world where?? Instead of the diversionary attacks..

Quote:
Say all you want; I will reply to your ridiculous CLAIMS no further.

Excellent. You have finally come up with an exit strategy. I was gonna pm you with some possible outs for you, you've not been very professional...

Last chance...try to discuss EMC or EM theory, talk about what I posted, prove me incorrect...

Cheers, John

ps..I do like the discussion on soldering, you've been quite nice there..

jneutron
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Re: hmmm


Quote:
All of the circuits were gold on the surface when soldering took place. I have no way of knowing if other metals underlay the gold, since I never had anything to do with circuit board production.

Fair enough.

I have to worry about the gold thickness and the barrier metal because we have a "gawdawful" MTBF to worry about. We need to run approximately 2,700 pieces of custom high tech gear we are purchasing build to print, the other divisions the same, and virtually all the components we need are only being made ROHS.. Downtime for the machine is VERY expensive..kinda like the last "gig" with it's megabuck per day downtime expense..

I have to worry about embrittlement and whiskers..the latter a big thing for the latest generation FPGA's..
Apparently, they've solved embrittlement by keeping the gold to a flash thickness, but it does limit the shelf life of the multilayer boards..

We're trying our best to keep lead/tin under the hood, but the parts situation is scary.

Cheers, John

jneutron
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Joined: Sep 16 2009 - 12:34pm
Re: hmmm


Quote:
jn2, you can post pics..you cannot attach them, but you can use the [image][/image] code to post website-hosted images..


Ah, thank you.. Your humble and loveable..(betcha don't know the preamble to that!!)no fair googling..

Guess I'm gonna hafta start remembering where I post pics..

Cheers, John

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