Do these antistatic wristbands really work?

How do I use an anti-static wrist strap when working on a desktop PC?


I would like to know how to properly use an anti-static bracelet. By antistatic bracelet, I mean a band with a wire attached and a metal clip on the end of the wire.

From everything I've read about them, they actually help prevent harmful static electricity from being generated. However, I am not sure what to attach the wrist strap to. Obviously, one end goes around the wrist, the other is stuck to the floor. But what exactly is the soil? Does the connection to:

  1. ... the housing of the PC, while the power plug is still connected to the housing, but the switch on the back of the PC is switched off. This seems risky to me as it is difficult to guarantee that the PC's components are really turned off.
  2. ... the case of the PC while the case is NOT connected to anything. In this case there is no ground to the actual earth.
  3. ... the plumbing work in my house, i.e. radiators or metal pipes. This doesn't seem like the ideal ground to me as the static build-up on the lines can still be different from the build-up on the computer case. Correct?
  4. ... any large metal object that is not connected to anything. Would it just lose static in the air over a large area?

In all of these cases, of course, I wouldn't bond to a painted surface as the paint might isolate and not conduct static electricity.

Is additional a wrist strap is sufficient when working with both hands? On the other hand, does the bracelet also decrease its static electricity? (Sometimes a component is stuck and it may take two hands to pull it out.)

And what do I base myself on when working on separate electronic components ? For example; Cleaning my graphics card while it's not in my computer case?

And finally a good anti-static bracelet needs a resistor ? And if so, how much resistance should it offer?






Reply:


To really answer this question, you need to understand both electrical potential and house wiring.

All objects have an electrical potential, similar to the "pressure" that the electrons cause in them. When two objects have different electrical potentials, we say that there is a "potential difference" or "voltage" between them. When these two objects touch, the electrons flow from higher to lower potential, much like liquids flow from high to low pressure.


(Image source)

This happens every time two objects touch. Usually you won't feel anything because the potential difference is so small (or the resistance is so high) but occasionally the shock is big enough to be felt. Potential differences of more than 10,000 volts are common due to the triboelectric effect. Note that electrical components can be damaged by shocks that are too small.

To prevent damaging the motherboard, you need to You just make sure you have the same electrical potential without being caused by an electric shock.

Does it work to connect the strap to the motherboard?

Yes, but I wouldn't recommend it.

It works without shocking the motherboard as the wristbands are specifically designed to slowly equalize the potential. However, motherboards are fragile and U-clamps are not. There are literally varnished wires on the motherboard that can be easily scraped off with a clamp. Nor is there a particularly good place to clamp.

If you plan to work on a single motherboard, consider using an anti-static mat that "attaches" to the motherboard by touching the bottom


(Image source)

Is the connection to the case working?

Yes, this is the recommended solution.

As long as the motherboard is screwed into the housing, the two are electrically connected by the screws. Because of this, all motherboards have metal rings that the screws are attached to (and why you shouldn't use painted screws) .


(Image source)

This applies regardless of whether the housing is connected to earth (i.e. connected to a three-prong outlet) .

I usually don't pay special attention to whether or not the PC is plugged in when I'm working on one, other than to make sure the power is off. However, if you are working on multiple computers at the same time, I would recommend plugging them all in to make sure they all have the same potential.

Does the connection to metal pipes, radiators or the bottom of a socket work?

Yes, but it's not ideal.

As long as the computer is connected to a three-pin socket, the motherboard and housing are connected to the socket with the grounding cable (Why?) . All house pipes should also be grounded and are therefore electrically connected to the motherboard.


(Make sure the pipes remain grounded in the presence of a water meter. Image source)

However, there are a few reasons why this is not ideal:

  1. It requires the computer to be connected to the wall, which is inconvenient and increases the possibility of errors. If your belt is plugged into the wall but the computer is not, you are not connected to the computer!
  2. House wiring is assumed to be correct and up to date, which unfortunately is often not the case, especially in older homes or (earlier) Homes of home improvement amateur electricians.
  3. It is assumed that the ground circuit is not broken (if a pipe connecting wire had come loose you would probably never know) .
  4. Even if everything is wired and working properly, a potential difference can build up between electrically remote hardware components. After all, wires have resistance too.

For this reason, I would only recommend connecting to pipes or to the grounding socket if for some reason you are None at all Can establish a connection to the housing.

Does connecting to large metal objects work?

No!

If this large metal object is not connected to anything, there is no reason to believe that it has the same electrical potential as the motherboard. Doing this is the same as not grounding anything.

Is a wrist strap enough when you are working with both hands?

Yes.

There's enough oil, moisture, and salt on the surface of our skin to make it a reasonably decent conductor of electricity.

I used to work for a circuit board manufacturer - they were extreme paranoid about static electricity. Every subsurface, including the floor, had to be at earth potential. We had to wear anti-static coats and our shoes had to be conductive (or wear conductive shoelaces) . Even there, the workers only used a bracelet.


(Not where I worked, but in similar outfits. Image source)

What do I ground to when working on separate components?

Place them on an anti-static mat and grind them on top.

Their concern is to make sure that you and the components all have the same potential. This happens automatically when you touch the antistatic bags that hold the components (The bags have a moderate resistance, so the potential slowly equalizes. A second should be enough) . From there, you should place the components on an anti-static mat and ground your bracelet to the mat. From then on, you and everyone on the mat have the same potential. When you're done, put them back in the anti-static bags.

If you are working with multiple ESD mats, you should ground them all to the house floor simply because that is a convenient, easily accessible reference point.







The ideal situation is to have an electronic device plugged in but turned off to the ground. Other reasons like radiators or plumbers are good second choices. Professionals sometimes use an adapter that separates the hot and neutral leads and only connects the ground. With typical PCs, it makes perfect sense to just make sure that the power switch is off.

If all else fails, you can plug it into your computer case even if it isn't connected to anything. At the very least, this way there is no static discharge between your hand and the case.

As you attach the strap to your wrist, the charge is the same over your entire body. This will remove static electricity from your entire body. Your wrists are already connected by your skin.

A static wristband should have a resistor to ensure it doesn't become a conduit for a potentially fatal line shock. A million ohms is typical. This will allow the static electricity to continue to drain, but it will prevent typical voltages from delivering enough current to shock you.







CompTIA recommends a properly grounded ESD mat. This is ideal when you want to clean some of your components. If this isn't practical for you, try finding an anti-static bag and place the part on it when you clean it. I save these bags every time I buy electronics because they are very convenient. This can go without saying: Only touch the component by the metal plates. If there is no disk (RAM or system board), grasp it by the edges furthest from the transistors and conductive metals.

There are standards that define adequate ESD protection, namely ANSI / ESD S6.1, which aims at the same potential. Wearing a grounded harness doesn't necessarily mean your other limbs have the same potential. Even after being grounded, the body does not have the same potential in all limbs. For example, you could drag your feet across the carpet, touch the computer case with both hands, and still have an imbalance. In my hardware time we used ESD floor mats and ESD table mats that were grounded as shown below.


How do I use an anti-static wrist strap when working on a desktop PC?

An anti-static wrist strap is part of a good anti-static solution. It helps on its own, but doesn't solve all of the static problems you might encounter.

First of all, you need an anti-static work surface on which all components can be placed. Then connect the strap to the work surface or a grounding point that also grounds the work surface. That way, you, the work surface, and everything you put on it have the same potential. It is not about eliminating potentials, it is not about slowly balancing potentials so that no large harmful static discharges occur.

If you have an anti-static surface, e.g. For example, an antistatic table mat, connect it to the grounding lug of an electrical outlet (the screw on the socket cover is grounded), or use a special socket adapter that connects the cable to the earth of the socket. Follow the manufacturer's instructions and local codes for this grounding point. Note that there is a resistor in this connection, usually 1M ohm.

Connect the wrist strap to the mat and attach the wrist strap to yourself. This will also have a 1M ohm resistor. These resistors allow a slow potential equalization without sparking and at the same time protect the user from possible electrical hazards if one of the wires is shorted to AC or another dangerous voltage source.

Once you and the mat are properly set up, you can start unpacking the products and assembling the computer onto the antistatic mat.

If you don't have an anti-static mat, you can cut open the anti-static bag that came with the motherboard, place the computer case on part of it, and attach the wrist strap to the case. This is far from ideal, but you and the components will quickly and safely achieve the same potential without static discharge.

If you insist that the anti-static protection is useless, please understand that most discharges are harmless and that those discharges that do harm often do not destroy the product, only damage it. The damage may be undetectable with normal use or may appear as a rare but frustrating, faulty, freezing, or faulty condition. So you may actually have put together dozens of PCs without adequate protection and had no problems that you could attribute to your lack of protection - but you or your customers may have dealt with minor, infrequent problems and just live with them because you have the problem not easy to find. The choice is yours, but you are spreading bad information if you claim that anti-static policies and procedures have no benefit. For me it is


I would recommend using anti-static measures. A company that I know no longer makes hi-tech laboratory equipment with anti-static work areas. Everything was fine for 2 years, then they noticed increasing failures.

It seems that the static discharges rarely cause an actual failure, but they can weaken the internal structure of the device and cause more failures over time.

They used anti-static measures again and failure rates returned to normal



My electrostatic belt comes with a dummy plug that only contains the ground pin. I just plug it in to the mains.

If you can find one of these, or just the connector that comes out at the end, you'll be sorted.





Have you considered using disposable rubber gloves when handling electronic components? I also find this to be a more practical anti-static solution if you are working in the field or in an environment where a wrist strap / mat properly plugged into the mains is not practical.


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