Fellow TechNetters:

   Thanks to all who contributed with their experience.   What a wealth of knowledge is out there.   Never seems to amaze me.   On another note, will an ultrasonic environment loosen the component lead so that it will works itself out of the LF solder joint.

Victor,

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David Hillman
Sent: Monday, March 30, 2015 8:46 AM
To: [log in to unmask]
Subject: Re: [TN] Leaded component, lead pull test

Hi Wayne - But I didn't say "solder" was indestructible, plated thru holes are indestructible. The clinched lead acts as the mechanical connection and the solder acts as the electrical connection. I completely agree with you that solder is a very poor mechanical material - any time we use a material that actively recrystalizes in its use environment, we had better be very good with our designs. As an industry, we "re-learned" that lesson when Leadless Ceramic Chip Carriers (LCCCs) were introduced and in some sense, we again went back to school with the introduction of BGAs (we all got "Fs"
for LCCCs and "B-" for BGAs). As you detailed, good design uses materials intelligently within their limits with an understanding of the product use environment constraints. Not understanding the limits of a material can result in a predicted failure, as demonstrated by your PTH spring example.

Dave

On Mon, Mar 30, 2015 at 8:30 AM, Wayne Thayer wrote:

> I can't agree that "Plate thru hole solder joints are truly
> indestructible."
>
> Solder is a strange material to use for mechanical connection. As a
> metal, it is pretty weak under the best of circumstances. Depending on
> temperature and rate of stress, it is EXTREMELY weak. Years ago we had
> a mechanical engineer who used a through-hole solder joint to maintain
> stress on a spring. Held for about a year! I suggest you repeat that
> experiment, with the through hole solder joint suspending a weight
> about 600mm above your keyboard and let us know how long it lasts!
>
> But we all design modules which depend on the solder as a mechanical
> connection. As long as the time constant of the stress is low enough
> (shock loads, diurnal temperature stress, etc.), it works pretty well
> when compared with organic adhesives (until grain growth and cyclic
> fatigue do their work).
>
> Wayne Thayer
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of David Hillman
> Sent: Monday, March 30, 2015 8:47 AM
> To: [log in to unmask]
> Subject: Re: [TN] Leaded component, lead pull test
>
> Hi Victor - not much data in the public domain on that topic. About
> the best you can do is get a copy of the International Tin Research
> Institute's Publication 656 titled "Solder Alloy Data". Publication
> 565 contains tensile, fatigue and shear data for a number of solder
> alloys over various temperature and stress/strain rates. The testing
> we completed back in the early 1990's at Rockwell Collins on plated
> thru hole strength nearly always resulted in failure of the plated
> thru hole/laminate rather than the solder joint itself using slow
> tensile speeds (unpublished). Plate thru hole solder joints are truly
> indestructible.
>
> Dave Hillman
> Rockwell Collins
> [log in to unmask]
>
> On Fri, Mar 27, 2015 at 3:10 PM, Victor Hernandez <
> [log in to unmask]> wrote:
>
> > Fellow TechNetters;
> >
> > Does anyone have information on the following:
> > Finish hole size, lead diameter, solder type, thickness of
> > board and lead length. How much force does it require to pull out a
> lead
> > from the solder joint. Will the lead come out cleanly or elongated and
> > snap,
> >
> > Victor,
> >
> >
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