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How to join two wires


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#1 steve6375

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Posted 23 July 2015 - 05:34 PM

If you thought that joining two wires was pretty straightforward, have a read of NASA's 114 page guide!

http://www.hq.nasa.g...ctree/87394.pdf


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#2 ambralivio

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Posted 23 July 2015 - 08:31 PM

@ steve6375,

 

Just only to not excessively alarm simple amateurs in electronic assembly, really speaking the document covers process and end-item requirements for NASA's suppliers, so it is intended to be used for suppliers' qualification and quality audits, in order to have product's reliability guaranteed. 

 

ambralivio



#3 Wonko the Sane

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Posted 24 July 2015 - 09:47 AM

@ambralivio

More than that, it is supposed that anything manufactured for NASA needs to be resistant to:

  • crazy accelerations and decelerations
  • extreme temperatures, both low and high
  • variable conditions of atmosphere, including no atmosphere at all or surroundings contaminated by whatever gas or chemical
  • vibrations both at very low and extremely high frequency
  • high exposure to radio waves, including light and X-rays
  • conditions of absence of gravity or lower or higher gravity than what you experience on earth

 

It is unlikely that any other field besides  some military sectors and maybe civil avionics will ever have the same strict requirements for components and their assemblies than something that is intended to go to the space or to other planets.

 

Basically, that is rocket science. :whistling:

 

And now, just in order to actually alarm simple amateurs in electronic assembly ;), let me introduce you to the tin whisker issue :w00t: :ph34r:

http://nepp.nasa.gov...sker/index.html

 

Now, why would, in their simplicity ;)  the medical and the military have managed to be exempted from RoHs and similar directives?  :dubbio:

 

 

:duff:

Wonko



#4 steve6375

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Posted 24 July 2015 - 11:03 AM

It strikes me that rather than trying to prevent them, we should find out how to make them to any desired length, as this could be a very useful way of 'growing' tracks between components.

 

On the other hand, it could be a really good way of building in obsolescence!

 

Now wonder TVs only last a few years now!



#5 Wonko the Sane

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Posted 24 July 2015 - 11:38 AM

It strikes me that rather than trying to prevent them, we should find out how to make them to any desired length, as this could be a very useful way of 'growing' tracks between components.

 

You do understand that following step would be a T-1000, don't you? :w00t: :ph34r:

https://en.wikipedia.org/wiki/T-1000

 

:duff:

Wonko



#6 IAmTheTrueMeaningOfCovfefe

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Posted 24 July 2015 - 12:56 PM

 

More than that, it is supposed that anything manufactured for NASA needs to be resistant to: 

 

being leaked to the public.



#7 Wonko the Sane

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Posted 24 July 2015 - 01:10 PM

being leaked to the public.

Well, it is not like the document is on WikiLeaks, it is on the official NASA site and also linked to on several pages on Wikipedia, basically if you search for "wire splice" before or later you get to that NASA manual.

 

Publishing does not mean "leak to the public", there is nothing abnormal in this, unless the good NASA guys put together and published the manual to keep us busy and distract us from investigating on the real world issues like the Area 51 and the Roswell incident, of course. 

 

:duff:

Wonko



#8 IAmTheTrueMeaningOfCovfefe

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Posted 24 July 2015 - 01:48 PM

Well, if you ask conspiracy theorists, they may tell you that NASA tried to recruit Stanley Kubrick into helping them cover up the moon landings. Given his stature as a master film maker, he would have been the perfect man for the job.

 

In any case, I'm not inclined to buy into most of the claims made by conspiracy theorists.



#9 ambralivio

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Posted 24 July 2015 - 04:12 PM

 

Now, why would, in their simplicity ;)  the medical and the military have managed to be exempted from RoHs and similar directives?  :dubbio:

 

 

Really speaking RoHS (which is applicable only in Europe, even if it has been more or less extended/accepted in other countries)  was (and will be in the next future) gradually extended also for medical devices/applications.

 

Anyway, the only reason is due to the fact that soldering without lead (ref. RoHS and its exemptions) does not guaranteed the same reliability level for products.

 

 

And now, just in order to actually alarm simple amateurs in electronic assembly ;), let me introduce you to the tin whisker issue :w00t: :ph34r:

http://nepp.nasa.gov...sker/index.html

 

 

A good example on how in US, where RoHS was never accepted (I'd say digested), they tried to take the mickey out of people,  dragging up this  phenomenon, (well known by technicians, on the other hand).

 

P.S. - JFYI, I've worked on the above topics for more than 20 years...



#10 Wonko the Sane

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Posted 24 July 2015 - 06:54 PM

Anyway, the only reason is due to the fact that soldering without lead (ref. RoHS and its exemptions) does not guaranteed the same reliability level for products.

Sure :thumbsup:, and this actually confirms Steve6375's note:

 

Now wonder TVs only last a few years now!

 

as I see it, besides any consideration about the quality of solder and solder joints the real issue is that lead free soldering has raised noticeably temperatures during the manufacture, and this tends to be a big issue when electronic components are involved (though many have been re-designed/modified to bear higher soldering temperatures).

 

I have notoriously failed in my diplomatic career ;) but the whole RoHs directives on electronics are in my perverted mind some of the most stupid and ineffective ways to prevent lead waste and consequently saturnism :ph34r: (the amount of lead in soldering in electronics is a negligible amount overall), while having disastrous effects on the reliability of electronics and making life a lot more tough for anyone involved in electronics manufacturing and assembling/repairing:

https://en.wikipedia...ctive#Criticism

 

Hopefully :) it seems than in latest years the industry is re-gaining some reliability, but it took several years and still a lead-free soldering has a tendency to crack due to vibrations or shocks that the minimum amount of lead in eutectic alloys effectively prevented.

 

If you want a practical example a large number of BMW owners have (or have had) an issue with the knob control of their navigation system iDrive ceasing to work properly.

These cases normally happen after warranty period has expired and the good guys (official BMW shops) replace the whole thingy for a mere € 350-400 or so, while the issue in - say - 99.99% of cases is a cracked solder joint on a microswitch, something that can be fixed, including disassembling from the car, disassembling the knob, re-soldering the failed joint and re-assembling, no more than 3/4 of an hour.

 

:duff:

Wonko



#11 ambralivio

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Posted 24 July 2015 - 08:06 PM

 

Hopefully :) it seems than in latest years the industry is re-gaining some reliability, but it took several years and still a lead-free soldering has a tendency to crack due to vibrations or shocks that the minimum amount of lead in eutectic alloys effectively prevented.

 

Sorry Wonko, but I do not think that 37 % of lead (in the eutectic Sn-Pb alloy system) can be considered as a minimum amount !



#12 Wonko the Sane

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Posted 25 July 2015 - 09:33 AM

Sorry Wonko, but I do not think that 37 % of lead (in the eutectic Sn-Pb alloy system) can be considered as a minimum amount !

Well, 37% is the minimum amount of Pb that is (was) normally used for electronics solder alloys, AFAICR the 60/40 is (was) much more common than the 63/37.

However you are welcome to replace the "minimum" with "adequate" :).

 

:duff:

Wonko



#13 ambralivio

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Posted 25 July 2015 - 10:16 AM

Well, 37% is the minimum amount of Pb that is (was) normally used for electronics solder alloys, AFAICR the 60/40 is (was) much more common than the 63/37.

However you are welcome to replace the "minimum" with "adequate" :).

 

:duff:

Wonko

 

Nahhhh....sorry but, this time, you are mixing things.

 

In your previous post you referred to "eutectic" and the only eutectic composition within Sn-Pb binary alloy system is 63Sn37Pb.

 

ambralivio



#14 Wonko the Sane

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Posted 25 July 2015 - 10:39 AM

Nahhhh....sorry but, this time, you are mixing things.
 
In your previous post you referred to "eutectic" and the only eutectic composition within Sn-Pb binary alloy system is 63Sn37Pb.
 
ambralivio

Feel free to also replace eutectic with "eutectic or nearly eutectic" :)
 
I will gladly rephrase the whole thing as:
 
 

Hopefully :) it seems than in latest years the industry is re-gaining some reliability, but it took several years and still a lead-free soldering has a tendency to crack due to vibrations or shocks (that the minimum adequate amount of lead in eutectic eutectic or nearly eutectic alloys effectively prevented).

to further highlight how the most relevant part of the sentence is the first one.

 

You happy? :unsure:

 

Anything else that needs nit-picking? :dubbio:

 

 

:duff:
Wonko



#15 ambralivio

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Posted 25 July 2015 - 11:05 AM

You happy? :unsure:

 

Anything else that needs nit-picking? :dubbio:

 

 

No, I think that's enough.

 

You see, from your Post #10, it seemed you had a certain expertise in soldering/RoHS topics and so I insisted on the matter with technical data, also refining certain your statements...but my initial impressions were wrong !

 

ambralivio

 

But now your limited experti



#16 Wonko the Sane

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Posted 25 July 2015 - 11:29 AM

I thereby claim that my experience in soldering is BOTH "certain" and "limited", as I declare myself to be - at the most - a simple amateur in electronic assembly. (but still I have re-soldered and attempted to repair - often but not always successfully ;) -  more electronics thingies that you may imagine, including doing poor man's re-flowing of BGA chips and some SMT repairs with absolutely inadequate tools)

 

 

:duff:

Wonko



#17 ambralivio

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Posted 25 July 2015 - 11:38 AM

I thereby claim that my experience in soldering is BOTH "certain" and "limited", as I declare myself to be - at the most - a simple amateur in electronic assembly. (but still I have re-soldered and attempted to repair - often but not always successfully ;) -  more electronics thingies that you may imagine, including doing poor man's re-flowing of BGA chips and some SMT repairs with absolutely inadequate tools)

 

 

Good. I can only appreciate your audacity on repair BGAs.

 

Only a question : "Where those BGAs packaged or bare die with balls ?"  ;)

 

ambralivio



#18 Wonko the Sane

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Posted 25 July 2015 - 12:52 PM

Packaged, namely stupid video card (geforce go) GPU's, JFYI:
http://reboot.pro/to...-meet-you-guys/
http://reboot.pro/to...u-guys/?p=49498
of which there was at the time an epidemic on Acer laptops.

The updated statistics are four of similar cards reflowed, three actually working ;) after the reflow, though one did not last very long (like a couple months) and I had not the guts/will/time to attempt to re-reflow it, but I managed to get an used card that would fit and replaced it.

AFIAK of the three, two are still running (while two were sold/decommissioned/replaced/whatever), though cannot say if they are "two reflowed" or "1 reflowed + 1 with card replaced"

:duff:
Wonko

#19 sbaeder

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Posted 26 July 2015 - 12:09 AM


And now, just in order to actually alarm simple amateurs in electronic assembly ;), let me introduce you to the tin whisker issue :w00t: :ph34r:

http://nepp.nasa.gov...sker/index.html


:duff:

Wonko

 

Back to the whiskers...it's not just in space...these things killed a LOT of power supplys in our data center a few years back...they got sucked off where-ever they were growing, and landed in the power supplies!   Seemed to always happen after a power failure, when the AC really kicked on, and happened to suck more air out of the space under the raised flooring.  Next time they did a swap out of some racks, they had to lift up all the raised flooring, and really "clean" the heck out of it...After that - no more failed power supplies...



#20 Wonko the Sane

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Posted 26 July 2015 - 12:39 PM

It sounds logical, from what I understand the issue is more evident, besides in space, at higher altitudes on Earth (in other words where pressure is lower) and usually at a relatively high environment temperature it is well possible :unsure: that some (suction) vent/fan helps in "growing them" inside "heated" power supplies, and then maybe the increased fan speed at a restart helps in making them loose :dubbio:

Some of the professional equipment I have seen have fans that could be used to build vacuum cleaners, and while they normally (though rather loud) rotate at a decent speed, when they are re-powered they start at a ludicrous speed ;), I remember, besides Cisco routers/hubs a particular PoE power supply that when powered or repowered sounds like a jet taking off :ph34r:.

 

:duff:

Wonko






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