it might damage your wirebonds inside cavity package, if profile and wire size not select properly. On Mar 30, 2015, at 10:38 AM, Victor Hernandez wrote: > 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, >>> >>> >>> ____________________________________________________________________ >>> __ This email has been scanned by the Symantec Email Security.cloud >>> service. >>> For more information please contact helpdesk at x2960 or >>> [log in to unmask] >>> ____________________________________________________________________ >>> __ >>> >> >> >> _____________________________________________________________________ >> _ >> This email has been scanned by the Symantec Email Security.cloud >> service. >> For more information please contact helpdesk at x2960 or >> [log in to unmask] >> _____________________________________________________________________ >> _ >> > > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud > service. > For more information please contact helpdesk at x2960 or > [log in to unmask] > ______________________________________________________________________ > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud > service. > For more information please contact helpdesk at x2960 or > [log in to unmask] > ______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. 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