[EVDL] Solder strength (was: Re: J1772. Solder or crimp?)

[Chris Tromley via EV]

On Mon, Apr 25, 2016 at 1:19 PM, Lee Hart via EV  wrote:

> Solder is mechanically weak, and has a low melting point. It's fine for
> little low-power stuff, when there is negligible shock and vibration. It
> is, after all, how 99.9% of all electronic connections are made on circuit
> boards. :-)
>
> But, it's a poor choice for high power, things that get hot, or where
> there is mechanical stress.


​Excellent advice, ​and something to keep in mind whenever you get tempted
to use solder for mechanical strength.  I've seen it often enough (that is,
seen these applications fail enough) to look into it a bit.  Turns out one
of the worst things you can do to a solder joint is mechanically stress it
while also gently thermal cycling it.  You don't need to get anywhere near
the solder's softening point (normal operating temps can do it) to get it
to fail quickly by doing this.

Disclaimer here, which leads to my question.  The above applies to your
regular garden-variety lead-tin solder.  Does anyone know if it also
applies to lead-free?  Time for an RoHS update on old knowledge.

Chris
-- next part --
An HTML attachment was scrubbed...
URL: 

___
UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
http://lists.evdl.org/listinfo.cgi/ev-evdl.org
Read EVAngel's EV News at http://evdl.org/evln/
Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)

Re: [EVDL] Solder strength (was: Re: J1772. Solder or crimp?)

[Michael Ross via EV]

​Eutectic alloying is a fascinating effect​ - a metal like lead melting at
621.4°F is mixed with tin melting at 449.5°F and the resulting melting
point is even lower at 361.4°F.  There is no paste phase as with
non-eutectic mixtures.  For electronics it is a great idea to use a
eutectic solder alloy.  An vibration experienced by a non eutectic alloy
while in the intermediate phase of freezing will really mess up the joint.

You can certainly use other solders at higher melting points but they will
be very expensive.  Too high and you can reasonably solder small connectors.

I​
f you want to make a deep dive you should learn about eutectic alloys:

https://en.wikipedia.org/wiki/Eutectic_system

The eutectic
​Tin/Lead
 composition is 67 / 33

From https://en.wikipedia.org/wiki/Soldering
​:​


Common solder formulations based on tin and lead are listed below. The
fraction represent percentage of tin first, then lead, totaling 100%:

63/37: melts at 183 °C (361 °F) (
*​​eutectic: the only mixture that melts at a point, instead of over a
range*)
60/40: melts between 183–190 °C (361–374 °F)
50/50: melts between 183–215 °C (361–419 °F)

​There is an enormous chart of soldering a brazing alloys and their uses at
this wiki page.​
​


On Mon, Apr 25, 2016 at 8:23 PM, Chris Tromley via EV 
wrote:

> On Mon, Apr 25, 2016 at 1:19 PM, Lee Hart via EV 
> wrote:
>
> > Solder is mechanically weak, and has a low melting point. It's fine for
> > little low-power stuff, when there is negligible shock and vibration. It
> > is, after all, how 99.9% of all electronic connections are made on
> circuit
> > boards. :-)
> >
> > But, it's a poor choice for high power, things that get hot, or where
> > there is mechanical stress.
>
>
> ​Excellent advice, ​and something to keep in mind whenever you get tempted
> to use solder for mechanical strength.  I've seen it often enough (that is,
> seen these applications fail enough) to look into it a bit.  Turns out one
> of the worst things you can do to a solder joint is mechanically stress it
> while also gently thermal cycling it.  You don't need to get anywhere near
> the solder's softening point (normal operating temps can do it) to get it
> to fail quickly by doing this.
>
> Disclaimer here, which leads to my question.  The above applies to your
> regular garden-variety lead-tin solder.  Does anyone know if it also
> applies to lead-free?  Time for an RoHS update on old knowledge.
>
> Chris
> -- next part --
> An HTML attachment was scrubbed...
> URL: <
> http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20160425/779fba13/attachment.htm
> >
> ___
> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> http://lists.evdl.org/listinfo.cgi/ev-evdl.org
> Read EVAngel's EV News at http://evdl.org/evln/
> Please discuss EV drag racing at NEDRA (
> http://groups.yahoo.com/group/NEDRA)
>
>


-- 
To invent, you need a good imagination and a pile of junk.
Thomas A. Edison


A public-opinion poll is no substitute for thought.
*Warren Buffet*

Michael E. Ross
(919) 585-6737 Land
(919) 576-0824  Mobile and
Google Phone

michael.e.r...@gmail.com

-- next part --
An HTML attachment was scrubbed...
URL: 

___
UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
http://lists.evdl.org/listinfo.cgi/ev-evdl.org
Read EVAngel's EV News at http://evdl.org/evln/
Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)

Re: [EVDL] Solder strength (was: Re: J1772. Solder or crimp?)

[len moskowitz via EV]

When we need higher mechanical strength from a solder, we use 2% silver 
solder. It's a lot stronger and not terribly more expensive. Melting 
temperature is about the same.






Len Moskowitz


___
UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
http://lists.evdl.org/listinfo.cgi/ev-evdl.org
Read EVAngel's EV News at http://evdl.org/evln/
Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)

Re: [EVDL] Solder strength (was: Re: J1772. Solder or crimp?)

[Lawrence Rhodes via EV]

All this being said, yes crimping is better and my preferred method is Molex.  
However I don't have the crimper necessary for this job so I soldered...So did 
an electrical engineer who showed me...You can get by with soldering.  There is 
an inflexible container for the solder joints.  They will never move or flex.  
I say if you can't get or don't want to pay under 6.6kw you should never have a 
problem.  When I get my Tesla and go 14.4kw I'll worry when I get there.  
Lawrence Rhodes...using my soldered Dostar J1772 happily.   
-- next part --
An HTML attachment was scrubbed...
URL: 

___
UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
http://lists.evdl.org/listinfo.cgi/ev-evdl.org
Read EVAngel's EV News at http://evdl.org/evln/
Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)