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Author Topic: soldering question  (Read 1873 times)

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Offline 5282Topic starter

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soldering question
« on: December 09, 2016, 07:31:38 am »
when i soldering stm32 100pin tqfp .
some  smd led is light up when i soldering stm32 chip and no power in my board why ?  :popcorn:
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Online ataradov

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Re: soldering question
« Reply #1 on: December 09, 2016, 08:25:22 am »
Tip of the iron is grounded and your body is not, so EMI induces enough current to light up the LED. LED will only light up if you also touch the board.

Modern LEDs light up from minuscule currents, like in the 100-500 nA range.
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Alex
 

Offline 5282Topic starter

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Re: soldering question
« Reply #2 on: December 09, 2016, 08:55:28 am »
ok so it's emi or esd ?
my iron not grounded it's only 2pin 220vac
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Online ataradov

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Re: soldering question
« Reply #3 on: December 09, 2016, 08:57:47 am »
EMI. ESD will not cause a sustained effect.

Quote from: 5282 on December 09, 2016, 08:55:28 am
my iron not grounded it's only 2pin 220vac
That probably contributes to the effect. And may be the primary source of it.

I would not solder MCUs with an iron like that.
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Alex
 
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