No, I didn't expect you to, George. I was just wondering outloud about the relationship of the wire diameter with respect to time and whether it is a linear relationship. I am sure there are other factors such as the exact alloy type, etc, but I was just trying to get my mind around the general relationship of different sizes of solder joints (and more specifically, geometries) and the effect on time to failure for a given loading factor. Maybe I'm nuts, but I find the topic very interesting. I do know that even minor impurities, and different types, can play a huge role in the creep rate of solder. -----Original Message----- From: George Wenger [mailto:[log in to unmask]] Sent: Wednesday, November 15, 2017 8:50 AM To: Stadem, Richard D; 'TechNet E-Mail Forum' Subject: RE: [TN] Question on Loading Solder Joints Sorry. It was so long ago I don't remember what diameter solder wire he used. -----Original Message----- From: Stadem, Richard D [mailto:[log in to unmask]] Sent: Wednesday, November 15, 2017 9:43 AM To: TechNet E-Mail Forum <[log in to unmask]>; George Wenger <[log in to unmask]> Subject: RE: [TN] Question on Loading Solder Joints I wonder what diameter of solder is most useful to demonstrate the property within two or three hours, and with what weight? -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of George Wenger Sent: Tuesday, November 14, 2017 4:42 PM To: [log in to unmask] Subject: Re: [TN] Question on Loading Solder Joints I'm about to go out to dinner with my youngest son and my two youngest grandsons otherwise I would be downstairs in my work shop hanging weights. What I would like to do is hang three solder wires (1ft, 2ft, and 3ft) and time the creep elongation for each. I'm pretty sure the weight used by the teacher was a 1Kg weight. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of David Hillman Sent: Tuesday, November 14, 2017 5:37 PM To: [log in to unmask] Subject: Re: [TN] Question on Loading Solder Joints 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 > > >