The real purpose of the 1 Meg resistor is safety, to prevent electrical shock when being connected to ground via a wrist strap. The mats are naturally dissipative, and dissipative is defined as 1 ohm x 10>6 to 10>9, so no 1 meg resistor should be used to connect the mats to electrical ground.



-----Original Message-----

From: TechNet [mailto:[log in to unmask]] On Behalf Of James Head

Sent: Friday, August 17, 2018 4:41 PM

To: [log in to unmask]

Subject: Re: [TN] ESD



You need the 1MEG resistor. It's purpose is to dissipate the charge at a

non-instantaneous rate, protecting the electronic assembly and protecting

the operator.



James Head BEng MIET CID+



James Head PCB Design and Engineering

11 Charmind Walk,Winterbourne Road, SWINDON, SN25 1QA

Telephone: 01793 266237

Mobile: 07870 945579

Skype: headjames

E-mail: [log in to unmask]

Website: www.jameshead.co.uk





On Fri, 17 Aug 2018 at 21:32, Vargas, Stephen M <[log in to unmask]>

wrote:



> All:

>

>       A quick ESD question. We would like to use 3'x4' static dissipated

> anti-fatigue mats at our SMT lines. The floor under these mats are coated

> with ESD wax and verified regularly. The question is whether the mats need

> to be grounded with a 1 megohm resistor or will the static charge dissipate

> naturally through the mat into the floor? Wiring is an option, but the

> wires tend to get damaged frequently through normal operator movement.

> Thanks in advance.

>

> Regards,

> Steve Vargas

>