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Thread: ESD resistance

  1. #1

    Default ESD resistance

    So Iíve been reading through some Cree data sheets and noticed an interesting spec. The ESD withstand voltage. Looks like most popular cree LEDs like the xpg2 and xpl are rated for 8000v. Can anybody explain what this means in the real world?

  2. #2
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    Default Re: ESD resistance

    Electrostatic discharge ?
    ... is the archimedes peak

  3. #3

    Default Re: ESD resistance

    Quote Originally Posted by archimedes View Post
    Electrostatic discharge ?
    Correct

  4. #4
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    Default Re: ESD resistance

    I'm not sure what you are asking exactly.

    Many sensitive electronics components can be damaged by high voltage (even if current is minimal)

    I am not an expert, but I would expect that to be a rating of the particular emitter to tolerance of such.

    I think of ESD as "static electricity" and why many electronics tools are electrically isolated, as well as there is often use of "grounding straps" and such during assembly and repair.

    I'm happy to move this over to LED for you, where it will get more visibility to those who know more.
    Last edited by archimedes; 03-23-2019 at 09:55 AM.
    ... is the archimedes peak

  5. #5
    Flashaholic wosser's Avatar
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    Default Re: ESD resistance

    The 8000 Volts withstand test is a typical "Human Body Model" of an electrostatic discharge.

    Ever got a big shock from a car door handle? That was probably something in the region of 6000 - 50,000 volts. Luckily the human body doesn't have much in the way of capacitance so the total amount of energy isn't enough to do any damage. Also, this kind of discharge does not require an "electrical circuit" in order to take place, cars have rubber tyres, and you're probably wearing rubber-soled shoes. Two bodies of different charge levels will attract each other and an arc will often form that serves to equalise the two charges. It's a bit like the "nature abhors a vacuum" idea.

    Note that this HBM rating ONLY applies to a component BEFORE it is soldered into a circuit. ESD is less of a problem in a fully populated circuit because PCB and other components have the effect of spreading the energy over a larger surface area and volume.

    Power LEDs are designed to pass large, energetic pulses so they are generally fairly resilient to ESD. On the other end of the spectrum though are FETs (JFETs, MOSFETSs etc) which are very sensitive to ESD, especially on their gate pin. Even handling a FET with bare hands while using sensible common ESD precautions can destroy them.

    Things that make ESD problems more severe include, Relative Humidity (dry weather causes static charges to build up faster, achieve higher Voltages and remain in place for longer) and things like clothing material (polyester garments are basically equivalent to strapping a van deGraaf machine to your back).

    If in doubt, get a decent ESD bench mat with a quality grounding strap and wrist strap. Use them consistently and ensure you and your tools are all fully discharged before handling ESD sensitive components. If you are serious about ESD you'll want an ESD soldering iron too.
    Last edited by wosser; 03-24-2019 at 06:25 AM.
    17 is 11, 11 is 6, 6 is 3 and 3 is none. Also it's good to have some backups.

  6. #6

    Default Re: ESD resistance

    Quote Originally Posted by wosser View Post
    The 8000 Volts withstand test is a typical "Human Body Model" of an electrostatic discharge.

    Ever got a big shock from a car door handle? That was probably something in the region of 6000 - 50,000 volts. Luckily the human body doesn't have much in the way of capacitance so the total amount of energy isn't enough to do any damage. Also, this kind of discharge does not require an "electrical circuit" in order to take place, cars have rubber tyres, and you're probably wearing rubber-soled shoes. Two bodies of different charge levels will attract each other and an arc will often form that serves to equalise the two charges. It's a bit like the "nature abhors a vacuum" idea.

    Note that this HBM rating ONLY applies to a component BEFORE it is soldered into a circuit. ESD is less of a problem in a fully populated circuit because PCB and other components have the effect of spreading the energy over a larger surface area and volume.

    Power LEDs are designed to pass large, energetic pulses so they are generally fairly resilient to ESD. On the other end of the spectrum though are FETs (JFETs, MOSFETSs etc) which are very sensitive to ESD, especially on their gate pin. Even handling a FET with bare hands while using sensible common ESD precautions can destroy them.

    Things that make ESD problems more severe include, Relative Humidity (dry weather causes static charges to build up faster, achieve higher Voltages and remain in place for longer) and things like clothing material (polyester garments are basically equivalent to strapping a van deGraaf machine to your back).

    If in doubt, get a decent ESD bench mat with a quality grounding strap and wrist strap. Use them consistently and ensure you and your tools are all fully discharged before handling ESD sensitive components. If you are serious about ESD you'll want an ESD soldering iron too.
    Great explanation! Thanks for putting the voltage into perspective as well.

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