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March 2015

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Subject:
From:
Yuan-chia Joyce Koo <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Yuan-chia Joyce Koo <[log in to unmask]>
Date:
Mon, 30 Mar 2015 17:56:39 -0400
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text/plain
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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,
>>>
>>>
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>>
>>
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>
>
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