ESD: Truths, myths, and flat out lies

Discussion in 'Electronics' started by SarverSystems, Sep 25, 2004.

  1. SarverSystems

    SarverSystems [H]ardness Supreme

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    I've been seeing a lot of posts about ESD, what it is, and how to control it. Therefore, I am writing this post.

    What exactly is ESD anyways?
    ESD is Electro-Static Discharge. It is the rapid exchange of electricity from one object to another.

    What causes ESD?
    Static electricity builds up on the surface of any non-conductive object that rubs against another similar non-conductive object. Wool rubbing against rubber will cause static to build up on BOTH surfaces. One of the objects will become positively charged while the other object will be negatively charged. Even objects you wouldn't expect to hold a charge can be culprits of ESD. This includes wood and wood products (desks, cardboard boxes), styrofoam (packing peanuts, cushioning foam), and other items such as clothing. Even our own skin holds a charge (which is how those touch lamps work).

    A static charge can jump from one object to another as well. You can cause ESD damage to a CPU just by waving your hand a few inches from it. Have you ever noticed, the spark that occurs by touching a doorknob actually jumps a few centimeters to your hand BEFORE you touch the doorknob?

    ESD damage can occur to static senstive devices with as little as 1 volt of electricity. Most devices need about 100 volts before they are damaged beyond repair. People can't feel the static discharge until about 2,000 volts and higher. So just because you didn't feel the zap, doesn't mean it didn't occur.

    So what can we do to prevent ESD?
    There is no way to completely prevent it. All we can do is minimize it.

    Ok, so how do we minimize it?
    There are all sorts of things we can do. Working on an ESD mat, while wearing an ESD wrist strap is the best way. Keep your work area clear of all styrofoam, plastic and even paper, and work on a hardwood floor if possible.

    So now on to the truths, myths, and lies.

    ESD only occurs in the winter. MYTH. ESD occurs at all times of the year, but humans feel it in the winter because of the drier air.

    Even if ESD occurs to a device, it will still work. TRUE and FALSE. If the ESD damage is high enough, the device will completely fail. If the ESD damage is low enough, the device will not function properly. Things like BSoD's, memory errors, and corrupt data are often caused by ESD, but are diagnosed as bad hardware. Often a "bad" stick of RAM was good when it shipped, but then the installer zapped it with ESD unknowingly, and now it doesn't work.

    If I work in my barefeet I will lessen the ESD. TRUE. You will still build up a charge, but at a slower rate. Cotton or wool socks are more similar to carpetting than bare skin is to carpetting, so you will build up a charge at a slower rate if you are barefoot.

    I can just ground myself to my case instead of using an anti-static mat or wristband. TRUE. However, you must be in contact at ALL times with the case, and the case must be grounded to your home's electrical system. If the case is just sitting on your floor and not plugged in, then grounding yourself to the case does no good at all.

    Compressed air can cause ESD. TRUE. Remember, ESD is caused by 2 similar objects rubbing together. The air is rubbing against the air, causing ESD. However, air particles are so small that they lose most of their charge before they hit the surface of whatever you are spraying it on.

    I can just lay my motherboard on an ESD bag when I need to work on it. FALSE. An ESD bag will only work if the item is completely enclosed in the bag. The object must be completely surrounded by the bag, and the bag must be sealed for it to do any good.

    When I mount my motherboard inside my case, I like to mount the piece of foam that ships in the box in between the case and the motherboard as an insulator. WRONG. While that piece of foam is ESD foam, it is meant to cushion the board while in shipment. The ESD foam is a semi-conductor, and it can conduct just enough electricity to short out your motherboard.

    The styrofoam peanuts that Newegg (and other places) ships their products in must be safe then, right? FALSE. There is no such thing as ESD-safe packing peanuts. Ever notice how they want to stick to your arm, and everything else when you pull your items out of the box? Yup, you guessed it. That's static electricity making them stick to your skin.

    This guide is not meant to be an end-all on the ESD subject. Please feel free to add anything I may have missed.
     
    Lag likes this.
  2. SarverSystems

    SarverSystems [H]ardness Supreme

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    Oh, and to make ESD even more clear, let me post some numbers.

    Walking across carpet generates 35,000 volts at 10-25% humidity, down to 1,500 volts at 65-90% humidity.

    Walking across vinyl tile generates 12,00 volts at 10-25% humidity, down 250 volts at 65-90% humidity.

    Simply shifting around in yoru ccushioned chair generates 18,000 volts at 10-25% humidity down to 1,500 volts at 65-90% humidity.

    Common computer components and the voltage they can typically withstand:

    MOSFETS: 0-2000 volts
    Charged Coupled Devices: 0-2000 volts
    surface mount resistors: 0-2000 volts
    Integrated circuits: 0-2000 volts
     
  3. EPS Sniper

    EPS Sniper Gawd

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    Great write up. Valuable information indeed :cool:
     
  4. Impulse

    Impulse [H]ardForum Junkie

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    Hey, there's actually an upside to living in this horrid humidity? Who would've thought... [​IMG] But seriously now, good write up, a heads up for many I'm sure.
     
  5. Elledan

    Elledan [H]ard|DCer of the Month - April 2010

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    This is not entirely correct. 'Ground', can be any arbitrary potential (voltage). That's why there's such a thing as negative voltages.

    The goal is to minimize the potential between you and the devices you're working on. If the device is installed in a metal (conductive) case (like a PC case), then the ground potential for the device is that of the case. By touching this case, you lower your potential to this ground potential as well.

    Connecting oneself and/or the case to an outlet's ground does not offer any additional benefit.
     
  6. gee

    gee Electronics Wizard

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    Not really; strapping yourself to the case puts you and the case at the same potential. It's safe... sort of. The only thing is, you can't let your computer's guts touch anything grounded!

    If you do something like touch a grounded-tip soldering iron to your mobo when your case isn't grounded, static charge will go through you, through the motherboard, through the iron and to ground. And the same thing can happen if you plug in an audio cable from a grounded set of speakers before you plug in the power cable...
     
  7. fat-tony

    fat-tony [H]ard|Gawd

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    Also sketchily worded.

    If BOTH you and your case are hooked to an outlet's ground, then you will be forcing your body to be at the same potential as the case. However, hooking only one of them to the outlet is less effective.
     
  8. SarverSystems

    SarverSystems [H]ardness Supreme

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    I completely disagree with that statement, and I would be willing to bet that just about any electronics engineer would disagree as well.

    The goal with ESD is to get everything to the same voltage as Earth Ground.
     
  9. gee

    gee Electronics Wizard

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    EE here :D earth ground is ideal, but in situations where earth ground isn't available the goal is to get everything at the same potential so current from ESD can't flow where it shouldn't.

    Grounding yourself to your case without an earth ground still puts you and your computer case at close to the same potential, and that's what matters. An earth ground is better (especially when you're touching other stuff) but it's not absolutely crucial.

    Things like AM radio transmitter towers can put ground waves with tens of volts of amplitude into the earth ground around the site. Because of this, radio transmission sites always have a single ground peg (station ground) which all equipment is grounded to. It floats, but since all the equipment is grounded to that point, there's no chance of current flowing between anything. If you had multiple ground pegs (earth grounds), all hell would break loose because of the voltage differential.
     
  10. SarverSystems

    SarverSystems [H]ardness Supreme

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    Thanks for the input gee.
     
  11. mustang_steve

    mustang_steve c[H]ewbacca

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    This was all cut and paste from posts I made in another thread regarding wrist traps and how people handle their motherboards:

    ------------------------------------------------------------------------

    the wireless ESD bands usually are not clean room accepted, and to me if it's not acceptable for a clean room, then it's not acceptable for general use.

    Just get a $30 sed portable kit.

    Myself I went ghetto, and use a 2ftx2ft aluminum panel to rest my hardware on. The panel has a lug for a ground strap as well as snap-ons for grounding plugs, and to ground my case, etc. The whole rig with strap cables was about $20. That panel is NOT safe for working with voltage though, that's where the actual portable ESD kits are best.

    I work in a level 2 clean room, so I have to know this stuff...oh, and heel straps are worthless if your flooring is not static dissipative, just so nobody goes and buys one and feels protected.


    --as far as hardware, a shock may not kill a chip, but it might screw it up. So if you noticed your "hot OC card_01" cant OC worth crap, maybe you shocked one of the chips and it's not exactly functioning properly anymore as a result. Sometimes ESD damage is very subtle, and expensive to diagnose. Basically just be safe about it.

    --ESD bags are not ESD mats
    --Straps are a must, preferably the cable type (yes, even folks who wear one everyday hate them, just deal)
    --remember to ground your esd mats, wriststraps, and computer chassis (if it's plugged to the wall it's in most cases grounded)
    --take your ESD kits to an electronic supply shop once in a while to test their functionality...these kits will go bad eventually.

    ----------------------------------------------------

    (regarding what kits I use, and some pointers on a good wrist-strap)

    The portable kits we use are made by statico.

    Basically all the kits have to meet an industry standard, so quality is the only variable.

    For wriststraps, go for the stretchy blue cloth kind, and not the velcro. The stretch cloth type are far more confortable, but do wear out faster...but for a home user will last plenty long. My straps last over 6 months and I put them on hundreds of times.

    --------------------------------------------------------

    (in response to a guy who said he's never damaged anything due to ESD, but doesn't use any static control measures whatsoever outside of the "touch the case" bit)

    The thing is that you can't prove you didnt damage anyhting, since the minimum required to fry a component is far below what we can feel. So you may not know that discharge even happened.

    Having a portable ESD kit is not overkill, actually it's a good thing to be doing. It's a small investment that if used right, can rule out an entire item from your possible issues list, if in fact something does get messed up.

    Most ESD damage cases are not "oh my video card doesnt work at all" It's more like "when ever I run this v-ram demanding game, it keeps crashing out" kind of issues. Like my previous post, the board is rarely trashed, but some logic circuit got jumbled just enough to cause a problem only when that portion of the IC is utilized.

    Either way, all us techs hate the "dork strap"...honestly I want to wrap it around the neck of the freaking engineer that came up with it, but I use it at home anyways since it's cheap insurance.
     
  12. starhawk

    starhawk [H]ardForum Junkie

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    (1) i like those wriststraps.
    (2) i had heard that most components can only stand 300V. i guess my a+ cert prof was wrong tho.
     
  13. sev

    sev Limp Gawd

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    Just let common sense prevail and you will have safe and enjoyable computer DIY ;-)

    Ive seen under an electron microscope static punch huge (relative to the slice of silicon) through it. In some cases the potential between you and the device can be many thousands of volts as already stated. Grounding yourself to the mains earth via the case is a good thing. This will help discharge the static and prevent damage.
     
  14. mikeblas

    mikeblas [H]ard|DCer of the Month - May 2006

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  15. Tordek

    Tordek [H]ard|Gawd

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    another ee here. And i second.

    What he said about AM is true cause AM transmissions require a lot of power to reach large distances and for the recievers to actually understand any of it. But basically any transmiter uses a single ground peg because of this.


    But its my honest opinion that it would be pretty difficult for anyone to actually generate ESD if you are strapped to your case.

    Still i remember in the game Space Quest 6 how Roger Wilco disabled a robot by moonwalking on a carpet and then touching an input jack on the back of the robot's neck...
     
  16. Ice Czar

    Ice Czar Inscrutable

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    in for a dime in for a dollar :p

    from my ESD & Electromigration Rant (2 part)


    ESD Precautions and Practices
    The ATX motherboard specification maintains +5VSB power to the motherboard
    unlike PC/XT, AT, Baby AT and LPX form factors that employed a manual switch to turn on the power to the motherboard, the ATX form factor employs a "soft power" scheme
    allowing software control of power, allowing the OS or other ap to turn the computer off, it also allows wake on LAN or Wake on WAN. Since there is a low level of power supplied to the board at all times, you need to address this whenever your swapping out components

    the ideal solution is to unplug the power supply from the socket then ground the case with an alligator clip to a seperate ground point and use a wristrap to ground you

    the alternative method is to turn off the PSU with its own switch
    reliable only if the board has a 5VSB LED indicator on it
    at which point you know the board is unpowered, yet the case is still grounded via the AC Socket

    the alternative method if there is no switch on the PSU and LED mobo power indicator is to unplug the PSU from the wall socket, then disconnect the main power connector and plug the PSU back into the AC Socket, where once again you have the case grounded

    keep in mind that typically the PSU physically contacts the case with a metal to metal contact, at least in the past, and would have at least some contact via the screws, but these adys with painted cases and supplies, some augment that with a grounding strap for the PSU itself (very typical in server supplies where they take no chances with contact)

    and religously touch a bare metal surface in the case to ground yourself when swapping componets (this is very typical in here with enthusiasts)
    but all in all wristraps are cheap and so are alligator clips and a bit o wire
    a grounded work pad is also a good investment, as is being aware of how large a role the lack of humidity has in ESD events, especially in Winter when hot air heating desiccates the moisture out of the air

    (see I live on the Rocky Mountain High Dessert Plateau, where its already dry and in Winter with central home heating I humidify the environment when working on components)

    ESD Reference
    http://www.ewh.ieee.org/r10/bombay/news2/story11.htm
    "According to (not so) recent studies conducted by the AT & T Bell labs, 25 % of all component failures today are related to E.S.D and out of all defective components that arrive 50%are damaged by E.S.D. the annual damage due to these failures is estimated at 25 Billion dollars"

    An Integrated Circuit (IC) consists of several transistors fabricated on one chip. Due to the advances in L.S.I and V.L.S.I thousands of transistors are crowded on a single chip. By decreasing the thickness of the gate oxides and interconnecting lines the manufacturers hope to achieve much higher speeds at very low power consumption. But under these conditions if the Electrostatic Discharge passes through an IC and the current that results is not diverted or diminished by a suitable protective mechanism, the discharge may raise the temperature of the junction inside the component to melting point which will cause damage to the junction or interconnecting lines. Since surface mount devices are smaller than conventional ICs they are even more susceptible to E.S.D damage. E.S.D causes two main types of failures: -

    1. Immediate failure where the effect can be readily seen by the equipment manufacturer.

    2. Delayed failure where the device is damaged only upto the point where it may pass quality control tests, but wears out sooner than its rated time


    http://www.esda.org/esdbasics1.htm

    Table 2
    Examples of Static Generation
    Typical Voltage Levels

    Means of Generation .........10-25% RH ......65-90% RH
    Walking across carpet ......,35,000V ...........1,500V
    Walking across vinyl tile ....12,000V ............250V
    Worker at bench ................6,000V .............100V
    Chair with urethane foam ..18,000V ...........1,500V

    ESD Damage—How Devices Fail
    Electrostatic damage to electronic devices can occur at any point from manufacture to field service. Damage results from handling the devices in uncontrolled surroundings or when poor ESD control practices are used. Generally damage is classified as either a catastrophic failure or a latent defect.

    Catastrophic Failure
    When an electronic device is exposed to an ESD event it may no longer function. The ESD event may have caused a metal melt, junction breakdown, or oxide failure. The device's circuitry is permanently damaged causing the device fail. Such failures usually can be detected when the device is tested before shipment. If the ESD event occurs after test, the damage will go undetected until the device fails in operation.

    Latent Defect
    A latent defect, on the other hand, is more difficult to identify. A device that is exposed to an ESD event may be partially degraded, yet continue to perform its intended function. However, the operating life of the device may be reduced dramatically. A product or system incorporating devices with latent defects may experience premature failure after the user places them in service. Such failures are usually costly to repair and in some applications may create personnel hazards.

    It is relatively easy with the proper equipment to confirm that a device has experienced catastrophic failure. Basic performance tests will substantiate device damage. However, latent defects are extremely difficult to prove or detect using current technology, especially after the device is assembled into a finished product.


    Static Electricity - Electrostatic Discharge (ESD)

    "Most books or articles indicate that a spark can't be seen until the voltage on your body reaches between 450 to 750 VDC. Others indicate that they are very hard to notice until it reaches 1000 VDC. For most people, to feel a shock from a static electricity discharge the voltage is between 2,000-4,000V. A 0.5mm arch of static electricity carries approximately 2850V."

    Semiconductor Electromigration In-Depth

    Ground that mat, wriststrap and if possible humidify the environment

    when handling components, avoid touching any chips, circuitry and the slot contact fingers, hold PCB boards by the edges wherever possible



    --------------------------------------------------------------------------------------------------------

    ESD Susceptibility Analysis

    "ESD votages sufficient to damage semiconductor devices are often lower than the threshold of human sensory perception, making a person unaware that a static discharge has taken place"


    thats the basic proceedure most employ, its best if you do that like every other move, and be aware of exactly how much RH (Relative Humidity) influences Static Discharge
    Taking great care to never touch any chip or lead, handling only the PCB, perferably by the edges.

    the other point of my post is that while the immediate cause and effect relationship of catastrophic failure, using the "typical" proceedure is low...

    This board is filled every day with people who have developed RAM errors, data corruption problems (generally RAM) ect, Most of which can be traced to either poor power regulation (Transient Response) of the PSU, or ESD

    Latent defects caused by ESD in any IC (and they are just everywhere from HDDs to NIC, CPU, RAM ect) are massively underated as a cause of problems. If you have eliminated power fluctuation problems (PSU voltage regulation and power conditioning) and still experience a component failure, odds are that it was a latent defect, either from installation, or one that wasnt caught during manufacturing.
    the membership displays a cavalier attitude towards this issue for 2 reasons, RMA's are pretty easy, and they rarely employ the same component for its fully rated lifespan, upgrading before the eventual premature failure becomes appearent.

    But
    a latent defect, not only effects the lifespan, it degrades the performance of the IC as well, and is often the difference between the "Golden Chip" benchmark leader, the norm, and "why cant I get the same OC as this guy? Ive got the same components"
     
  17. Ice Czar

    Ice Czar Inscrutable

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    Electromigration is the mechanisim that typically first degrades and then kills IC Chips (Integrated Circuits)

    Semiconductor Electromigration In-Depth @ DWPG.com < the totally understandable link (if somewhat dated these days in particulars)

    Electromigration and Voids @ Cornell
    the Arrhenius equation

    roughly translating to this rule of thumb
    Each 10°C (18°F) temperature rise reduces component life by 50%
    Conversely, each 10°C (18°F) temperature reduction increases component life by 100%.


    however there is more to it
    http://www.triquint.com/company/quality/faqs/faq_07.cfm (caution heavy wading)
    "Electromigration mechanisms are accelerated by current density as well as temperature. The general relationship is sometimes referred to as Black's Equation. Just as with the Arrhenius equation, we can observe the electromigration effects on lifetimes using a graphical approach."

    so, both elevated temperature, and voltage, can cause voids to form in the circuits of any chip, a problem that becomes more and more important as the number of atoms that comprise the width of that circuit decrease, (that first link was written when the manufacturing scale was at 0.18 microns we are now at .09 microns (90nm) with some chips) in addition the clock rates that the power is cycled through is all that much higher as well, making the chips all that more suceptible to ESD, voltage irregularities and temperature.

    In short, Im very serious about my ESD precautions, power conditioning, power supplies and my thermal solution (under 40C CPU at full load w\ 30C SYS minimum) , and considering the price Ive paid for my workstation I want to squeeze every last hour out of it that I can, unlike a gaming rig, that may or maynot find another role in life once its yesterdays news, mine will be retired to a nice animation cluster to live out its full lifespan, but these cautions are just as important for anyone aspiring to a record overclock, or killer benchmark ;)
     
  18. IndianScout

    IndianScout Gawd

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    another EE here,,,

    some of the posts and hardware handeling that you read about on alot of boards just makes ya laugh...

    wrist straps will not do ANY good if not properly attached to whatever ground potential your working with..

    ESD mats are a great way to go whether they are workspace or floor mats,,

    great posts guys keep up the good work

    Ojibewa

    btw I am an EE at Pemstar

    great place to work all you electronics people

    :)
     
  19. mustang_steve

    mustang_steve c[H]ewbacca

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    Cool, I'm still not an EE, but after enough years of decent tech work, it's second nature.

    I still get driven nuts about the stuff people do...worst I saw was a guy rested a board on standard bubble wrap....grr

    ..thing to know is SOME of the pink buble wrap is static-dissipative...but don't count on it...some pink bubble-wrap is NOT static-dissipative. Don't assume and take chances. You would have to electronically test it to verify, and the gear for that is not cheap.

    Basically, leave things in the ESD bags until needed.

    Oh, and ESD scotch tape is great for closing those bags :)
     
  20. Techx

    Techx [H]ardness Supreme

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    Awesome info I'm going to do this next time I work on my rig.. Thinking back I cringe when I think I installed my 6800gt with no protection at all.. I guess you really don't think about ESD that much, it's almost like an afterthought, but I'm definately going to be more careful in the future.
     
  21. Ice Czar

    Ice Czar Inscrutable

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    incremental (latent defect) damage doesnt generally have an immediately observable cause and effect relationship
    that is till you start to wonder why your benchmarks are so poor :p

    and Id like to extend an invitation to all EEs and wannabe EEs to come play in the PSU forum ;)
     
  22. mustang_steve

    mustang_steve c[H]ewbacca

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    oh dear god, I'm half afraid to hear what lies in there, it could be about as bad as some of the things from Computer Audio....no offense to them, but I'm sick of explaining the details of how "item X" cannot do what it calims, or how "feature Y" is irrelevant....
     
  23. 3-Phase

    3-Phase Limp Gawd

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    I am about to build a computer for the first time. Should I be ok if it is done by setting the case on a table while wearing a wrist strap that is connected to the case? I will be on a hard floor.
     
  24. mustang_steve

    mustang_steve c[H]ewbacca

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    If you cannot get a mat, at the very least make sure the PC is grounded, and you use ground straps between you and the PC, and keep things in anti-static bags until installation, that means the motherboard goes into the case before the cpu goes on the motherboard. This way the chance for the motherboard to get shocked is minimal.
     
  25. Techx

    Techx [H]ardness Supreme

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    if i were to wear those latex gloves (the ones doctors wear) would that be enough protection without having to bother with anti-static devices, mats, straps, etc?
     
  26. starhawk

    starhawk [H]ardForum Junkie

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    Those are actually more static-prone. Stick with the tried-and-true static strap.
     
  27. DudeItsMe

    DudeItsMe [H]ardForum Junkie

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    Wow guys, thanks a lot for all this information. I read all the way down to Ice's post and felt informed enough to thank you guys [​IMG]

    I've built my own computer, and worked on it many times also. Lots of the time it has been on the carpet, unplugged, or even with me on the carpet and it on the desk. Yes, I was naive enough to believe that I was doing my computer no harm. After reading all this I realize it's important to stop ESD... especially since it can happen without you knowing. I guess I always assumed a shock to the components would mean a shock to me too.

    Well, this baby has minimal problems, but insuring myself against ESD seems like the wise thing to do in the future.
     
  28. killxswitch

    killxswitch Limp Gawd

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    ugh, this info makes me want to be sick. I'm one of the ignorant many that hasn't bothered much with ESD protection. I wonder if this is why my ram sticks keep crapping out.

    I guess I'll be making a run to Fry's soon.
     
  29. SarverSystems

    SarverSystems [H]ardness Supreme

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    RAM is the most suseptible to ESD damage from what I've found. It appears to be the smaller the circuitry, the more damaged it is. CPU, RAM, and chipset seem to be the worst at getting zapped by ESD.
     
  30. Ice Czar

    Ice Czar Inscrutable

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    and RAM has:

    ! a higher number of exposed IC chips in a smaller package
    2. are more often handled

    more chips that have more chances of getting fried
     
  31. mustang_steve

    mustang_steve c[H]ewbacca

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    Yes, a basic ESD mat kit with straps may be costly, but think of it this way....drop the cost of 1gb of ram, for a few years of use, and that mat will outlast that 1gig ram stick :)

    The good ESD mats have pockets to hold stuff...I stick boards in them if they are not going to be immediately installed.

    Another tip: NEVER just disconnect the cord from your wriststrap when you need to leave the area, What will happen is you will forget to plug it back in when you return. Instead, just remove the entire band, and put it back on when you retrun.
     
  32. SarverSystems

    SarverSystems [H]ardness Supreme

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    ESD mats with pockets? Linky?
     
  33. mustang_steve

    mustang_steve c[H]ewbacca

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  34. SarverSystems

    SarverSystems [H]ardness Supreme

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    Hmmmm. Apparently the 2 that I've been using as tble mats are actually floor mats.
     
  35. mustang_steve

    mustang_steve c[H]ewbacca

    Messages:
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    Those ARE table mats, just not portable mats. I am a fan of the portable variety for home use.

    The mat you have is for everyday use. The pocket mats are made for field service and the like.
     
  36. redeyes

    redeyes Limp Gawd

    Messages:
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    Feb 16, 2002
    So have any of you seen anything get fried from ESD? I have been around comptuers for 20 years and I have not seen anything happen. :rolleyes:
     
  37. gee

    gee Electronics Wizard

    Messages:
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    Have you ever encountered a piece of hardware that simply didn't work? Or a bad stick of RAM which makes a computer go unstable? I have, far too many times. What causes this... bad chips? maybe. bad designs? maybe. ESD? maybe. You'll never know for sure, but ESD is always a possibility.

    If you look at pictures (factory tours, etc) of electronics manufacturing companies, you'll see static precautions taken EVERYWHERE. Conductive floors, carts with ground straps that drag on the floors, people wearing wrist straps and having ground straps on their shoes, special furniture. ESD exists in a big way, and personal computers are certainly susceptible to it.
     
  38. mustang_steve

    mustang_steve c[H]ewbacca

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    If you understood exactly what level of discharge can damage a component, and what level of ddischarge you can feel, you wouldn't ask that question.

    To even feel the discharge, means that the jolt is at least 1,000 times what is needed to destroy an IC....not just damage, but completely demolish that IC.

    I've been around computers for 20 years as well, but I've been working as a professional in the electronic manufacturing field for nearly 7 years now, and pretty much what is covered here is the bare minimum....you don't even have to touch anything for electrostatic discharge to fry a component.

    It's not just a jolt...it's an actual field around the charged person/object. The rule of thumb for a manufacturing facility is nothing that is not properly safeguarded can be within 3ft of a board. This means the technician has to be constantly grounded as well. That means we have to either wear static dissipative shoes or heel-straps, ESD safe labcoats (which are also connected to ourselves by a wrist-strap, as well as a wriststrap that is to be used with the grounding cables attatched to the tech benches. The benches themselves have a 1/4" thick soft ESD mat covering the entire benchtop, as well as being grounded to the floor. The floor itself is earth grounded every 100sq ft. That is what the most basic of manuifacturing level ESD protections are like, in this case a system-level fabrication. You don't even want to think how bad a board-level fabrication is like.

    As for never seeing it...you can't see it, since it's going to be damage inside of the chip. And I bet you have seen it....if you had a soundcard that was literally sitting in a desk drawer in an unsealed ESD bag, and it doesn't work anymore...that's probably your root cause.
     
  39. Ice Czar

    Ice Czar Inscrutable

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    while seeing is believing, as a criteria of scientific investigation it predates the computer by a century or two :p

    luckily there are electron microscopes

    so I can answer truthfully yes Ive seen it :p
     
  40. Frank4d

    Frank4d Gawd

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    Oct 29, 2005
    I work for a company that makes $$$$$ military electronics. If you get caught not wearing ESD protection once or twice you might get a warning. Next time get fired. Good enough reason to wear ESD protection.