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 > > >