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too bent or not too bent...

Joe

#8233

too bent or not too bent... | 10 December, 1999

Hi,

Can anyone tell me when are bent leads too bent to be straightened again. I'm thinking about the strength of the lead where it meets the housing will be weakened the further you bend it.

thanks.

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#8234

Re: too bent or not too bent... | 10 December, 1999

Joe: It might be tough to generalize about the number of times you can reform a lead before it is weakened beyond the point of reuse, because of different lead materials, thicknesses, amount of bending etc.

It might be that "ugliness" is the answer. The more that you bend a lead the more you get kinks in it ... you can never seem to completely straighten a previously bend lead, because the bend metal is harder that the unbent metal. So you end-up with a kinky lead. After several bend / unbend cycles the lead becomes "ugly." This ugliness depend on the wire material and the amount you have tortured the poor thing.

Ta

Dave F

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#8235

Re: too bent or not too bent... | 10 December, 1999

Tell those leads not to be drinking so much. Anyway... too bent to work in a sequencer or auto insertion machine is a lot less bent than if you're trying to manually stick it into a hole. As far as where the lead exit/enters the body of the component I'd say your concern is warranted. The stress and metal fatigue encountered in a lead bent with little or no radius is considerable and simply straightening it can easily be the last bend it will tolerate not to mention possible internal damage to the component or the loss of the moisture seal. IPC-A-610-B requires "Leads must extend before the start of the bend radius at least one lead diameter or thickness but not less than 0.8mm from the body or the weld". John Thorup

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