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Subject:
From:
David Hillman <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, David Hillman <[log in to unmask]>
Date:
Tue, 14 Nov 2017 16:36:37 -0600
Content-Type:
text/plain
Parts/Attachments:
text/plain (117 lines)
LOL - I have the "test" in progress in my office right now - but the solder
wire length is one one foot long!

Dave

On Tue, Nov 14, 2017 at 4:31 PM, George Wenger <[log in to unmask]>
wrote:

> Richard,
>
> Although I have a good analytical mind and remember this demonstration
> very well I may have not gotten the dimension exact.  The more I think
> about it I think the blackboard was 4 ft tall and the solder wire may have
> only been 2.5 to 3 ft long and the class was all morning (9:00am-11:30) so
> the solder wire broke before the class was over so it might have broken
> closer to two hours then one hour.  Nevertheless, the demo made its point.
>
> George
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D
> Sent: Tuesday, November 14, 2017 5:21 PM
> To: [log in to unmask]
> Subject: Re: [TN] Question on Loading Solder Joints
>
> I can just hear Bev cutting the 4 ft section of wire solder as I write
> this.......LOL!
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of BEV CHRISTIAN
> Sent: Tuesday, November 14, 2017 3:37 PM
> To: [log in to unmask]
> Subject: Re: [TN] Question on Loading Solder Joints
>
> George, Ioan and Dave.
> Thx!
>
> Regards,
> Bev
>
> Sent from Mail for Windows 10
>
> From: George Wenger
> Sent: Tuesday, November 14, 2017 4:00 PM
> To: 'Bev Christian'
> Cc: 'TechNet E-Mail Forum'; 'David Hillman'
> Subject: RE: [TN] Question on Loading Solder Joints
>
> Bev,
>
> I'm really an old timer with lots of practical experience and I can
> remember back in the early 70's taking a class at The Western Electric
> Corporate Education Center in Hopewell NJ and the teach said that you
> should never have a solder joint under a tensile load.  He continued to say
> that rather than give you a 1000 words to tell you why not that he would
> show us a very simple and very graphic demonstration.  He pulled a roll of
> solid solder wire out of his desk and said it was Sn60 but it really didn't
> matter what the solder alloy was.  He cut off a 4 foot length of the solder
> wire and tied one end to a hook at the top of the blackboard and then tied
> a weight to the other end of solder wire.  He took a chalk and marked a
> line on the blackboard just where the bottom of the weight was.  He then
> continued teaching the days lesson but every 15 minutes of class, without
> saying anything, he would take the chalk and mark where the bottom of the
> weight was.  After about a little over an hour, while he was busy
> instructing us on the days lesson, we heard a loud "bang".  The solder wire
> had continued to elongate while it was under the tensile load of the weight
> and finally the solder wire broke approximately in the middle and the
> weight dropped onto the floor.  Right after every one heard the loud "bang'
> of the weight hitting the floor he stopped what he was talking about and
> simply said "that is why you never what a solder joint to be subjected to a
> continuous tensile load".  Although it's been almost 45 years since I
> attended that class I'll never forget what he said.
>
> George
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of David Hillman
> Sent: Tuesday, November 14, 2017 3:33 PM
> To: [log in to unmask]
> Subject: Re: [TN] Question on Loading Solder Joints
>
> Hi Bev - I would point them to RJ Klein Wassink's book "Soldering In
> Electronics", ISBN 0-901150-24. In the Mechanical Properties Section 8.4 it
> states "From the data in section 4.7.2 it is obvious that a normal soldered
> connection on a printed board is not well suited to withstanding a
> permanent mechanical load."
>
> And in Section 4.7.2 Creep, there is some good data on the creep
> properties of solder backing up that statement.
>
> Dave Hillman
> Rockwell Collins
> [log in to unmask]
>
> On Tue, Nov 14, 2017 at 2:12 PM, BEV CHRISTIAN <[log in to unmask]
> >
> wrote:
>
> > TechNetters,
> > A fellow ex-BlackBerry employee sent me the following query. I
> > obviously no longer have access ot the search capabilities I had at
> > BB.  Can anyone offer any suggestions for papers that will meet his
> > needs?  I mean I know the reason why, but he wants a paper that proves
> it.
> >
> > I need help with locating a couple of good papers and research studies
> > that explain why designs that place a constant tensile or shear load
> > on board connectors(USB, HDMI, RCA, AC inlet etc.) are a bad idea. Can
> > you point me to a couple of papers on this ? Thanks.
> >
> > Regards,
> > Bev
> >
> > Sent from Mail for Windows 10
> >
>

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