Electronic – Is the ESD safety procedure sufficient

esd

I will soon be assembling multiple computers and want to reduce the danger of ESD as much as possible. Not an expert myself so I'm looking for people with knowledge in ESD safety to comment on my planned procedure.

The ESD tools I will buy is an antistatic wrist wrap and an antistatic mat. The surface of my table is melamine laminate so I think the mat is required.

The most common advice I have seen is to install the PSU into the cabinet, connecting power cord to wall socket while turned off and attaching antistatic wrist wrap to cabinet. However, this will not have any effect in my case as the systems I'm building are using picoPSUs with external 12V power bricks and these have no ground wire.

The following are the steps I will follow while assembling a computer:

  1. Attach antistatic mat and wrist wrap to cabinet.
  2. Put on wrist wrap.
  3. Place screwdriver and other tools on mat.
  4. Unpack motherboard from ESD bag and place it on mat.
  5. Mount CPU, CPU cooler and M.2 SSD on motherboard.
  6. Install motherboard in cabinet.
  7. Install RAM and picoPSU.

The flooring is linoleum or vinyl and I will be assembling the computers barefoot while sitting on a wooden stool.

Is the above enough to reduce the risk of component damage from ESD, or is the procedure completely wrong?

Best Answer

ESD is not just prevention from becoming ungrounded. ESD events are most destructive when there is a low resistance path to follow. The mats and straps have resistance in them to prevent a sudden discharge path when the hands touch other objects or when new components are brought into the work area.

The bare feet would be exactly wrong. As you stand up and sit down on the stool, for example, you will now have a path for rapid discharge to the floor and secondary current flow can be rather chaotic. Also, the bare feet make for a path for dangerous electric current in fault conditions through your body. Really, the stool should be ESD coated and you should wear an ESD smock so that your natural movements on the stool don't become an electrostatic generator.

Keep the tabletop + computer + human as close together as possible ... electrically speaking. The straps and mats do this. Keep that work group as far from other unprotected objects as possible. 1 meter is a typical figure given for distance through air that friends, dogs, file cabinets and the like must be kept away.

Don't plug anything into mains any time during the assembly. First it is dangerous due to mains coming too close to the human; and secondly, it provides a path for rapid conductivity. The most standard approach is to connect the mat to building earth. For this, you will have to find plumbing or other metal that gets into the ground beneath the building. No, you can't use the ground lug of the wall outlet, that has horrible inductance to real earth and there are cases where it has been mis-wired by the original contractors.

At all times, consider your personal safety above the safety of the equipment.