+ Post New Thread
Results 1 to 11 of 11
  1. #1
    Advanced Member level 5
    Points: 28,882, Level: 41
    Achievements:
    7 years registered

    Join Date
    Sep 2008
    Location
    cambridge
    Posts
    6,052
    Helped
    446 / 446
    Points
    28,882
    Level
    41

    Cheap ESD flooring for electronics assembly lab

    Hello,
    We need ESD flooring for our electronics assembly lab.
    We will use these ESD floor tiles, they have a resistance of 100 billion ohms per metre^2...

    https://www.antistaticesd.co.uk/shop...locking-tiles/

    ...so we will put loads of strips of conductive tape beneath them and earth those.

    Please could you help review this?..it is as in the attached document

    •   Alt12th June 2018, 19:11

      advertising

        
       

  2. #2
    Super Moderator
    Points: 71,437, Level: 65
    Achievements:
    7 years registered
    Awards:
    2nd Helpful Member
    betwixt's Avatar
    Join Date
    Jul 2009
    Location
    Aberdyfi, West Wales, UK
    Posts
    11,690
    Helped
    3867 / 3867
    Points
    71,437
    Level
    65

    Re: Cheap ESD flooring for electronics assembly lab

    Looks good to me.

    Its a pity but there is a large building next door to me which burned down in February and there are miles of copper wires from the mains wiring just hanging from the ceiling and walls. All the insulation is burned off, it would make an ideal matting for under your tiles but it is all going to waste. There are three lengths (L, N & E) for each outlet and fitting of course. It is awaiting demolition at the moment.

    I have never tried it, and I would seek advice before using it, but spraying nickel conductive paint might be a quick and cheap way of laying the conductive mat. You wouldn't have to do the entire area, only a lattice but it would of course depend on the surface you are laying tile upon.

    Brian.
    PLEASE - no friends requests or private emails, I simply don't have time to reply to them all.
    It's better to share your questions and answers on Edaboard so we can all benefit from each others experiences.


    1 members found this post helpful.

  3. #3
    Super Moderator
    Points: 29,067, Level: 41
    ads-ee's Avatar
    Join Date
    Sep 2013
    Location
    USA
    Posts
    6,682
    Helped
    1604 / 1604
    Points
    29,067
    Level
    41

    Re: Cheap ESD flooring for electronics assembly lab

    Quote Originally Posted by betwixt View Post
    Its a pity but there is a large building next door to me which burned down in February and there are miles of copper wires from the mains wiring just hanging from the ceiling and walls. All the insulation is burned off, it would make an ideal matting for under your tiles but it is all going to waste. There are three lengths (L, N & E) for each outlet and fitting of course. It is awaiting demolition at the moment.
    And somebody hasn't gone in overnight and taken (stolen) that copper wiring? You must work in the most honest and safe area of town, either that or there are many guards (animals and people) patrolling the burned down building. A fence wouldn't stop the thieves around here.


    1 members found this post helpful.

  4. #4
    Advanced Member level 5
    Points: 13,753, Level: 28

    Join Date
    Nov 2012
    Posts
    2,564
    Helped
    596 / 596
    Points
    13,753
    Level
    28

    Re: Cheap ESD flooring for electronics assembly lab

    We will use these ESD floor tiles, they have a resistance of 100 billion ohms per metre^2...
    Isn't it a bit on the higher side?

    It should not be so low that the current is appreciable.

    It should not be too high so that the charge stays for a long time.

    I do not understand how loads of strips of conductive tape beneath them is going to help- you are just making a giant capacitor (bit leaky but better than many available commercially)

    But, but...

    you are giving a value that appears to be a surface resistivity whereas the value mentioned in the attached document is the volume resistivity.

    I am confused!!


    1 members found this post helpful.

  5. #5
    Advanced Member level 5
    Points: 28,882, Level: 41
    Achievements:
    7 years registered

    Join Date
    Sep 2008
    Location
    cambridge
    Posts
    6,052
    Helped
    446 / 446
    Points
    28,882
    Level
    41

    Re: Cheap ESD flooring for electronics assembly lab

    in the word document, that is the over-riding measurement....80 megohms from the persons hand to earth...going through their body, the tile, and along the conductive tape to earth.
    It would have been nice if this could have been a few megohms, but tiles with that kind of resistance just dont exist at normal prices.
    Last edited by treez; 13th June 2018 at 05:54.



    •   Alt13th June 2018, 05:43

      advertising

        
       

  6. #6
    Advanced Member level 5
    Points: 13,753, Level: 28

    Join Date
    Nov 2012
    Posts
    2,564
    Helped
    596 / 596
    Points
    13,753
    Level
    28

    Re: Cheap ESD flooring for electronics assembly lab

    in the word document, that is the over-riding measurement....80 megohms from the persons hand to earth...
    In the common test for satisfactory insulation (e.g., house wiring or a motor winding), commonly done at 500V, 80 megohm is considered "good" insulation. I do not know the test setup but this is essentially the self leakage resistance of the capacitor (please do not call that cheap) - the ESD tile.

    I cannot guess a reasonable value for the capacitance of the floor tile setup (but it will certainly be around nF range) and with a resistance of 80M, the time constant will be of the order of seconds.

    In other words, if your body has collected a static charge and got a potential of 20kV (very common), it will take about a second for the voltage to come down to 10kV.

    You need a resistance of the order of 10M or so to be effective. But installing a humidifier would have been cheaper.


    1 members found this post helpful.

  7. #7
    Super Moderator
    Points: 71,437, Level: 65
    Achievements:
    7 years registered
    Awards:
    2nd Helpful Member
    betwixt's Avatar
    Join Date
    Jul 2009
    Location
    Aberdyfi, West Wales, UK
    Posts
    11,690
    Helped
    3867 / 3867
    Points
    71,437
    Level
    65

    Re: Cheap ESD flooring for electronics assembly lab

    And somebody hasn't gone in overnight and taken (stolen) that copper wiring? You must work in the most honest and safe area of town, either that or there are many guards (animals and people) patrolling the burned down building. A fence wouldn't stop the thieves around here.
    The population is less than 10 per square Km here so everyone knows everyone else. There have only been three reported crimes within 10Km (~6 miles) of here so far this year and they were opportunist 'tourists' from the cities. Besides, the place is so well hidden and with only one escape route that I doubt thieves would ever find it. Its a good place to live!

    Returning to the topic, again, the intention isn't to discharge huge power sources, it is to prevent the build up of static. Taking a human body as a typical 'charged' capacitor plate, almost all the dielectric will be the soles of shoes and they should be bypassed with heel straps. Essentially, if you create even the slightest leak for current, and do not intentionally introduce new charges, no significant voltages will build up and existing ones will discharge. Also remember that potential difference across components causes the damage, not the absolute voltage so as long as the board being assembled, the components and the operator have a leakage path between them it is as safe as it can be.

    Assuming this lab is in the UK, a humidifier probably won't help as RH is typically >80% all year in most of the country. Keeping components dry is more of a problem than keeping things moist!

    Brian.
    PLEASE - no friends requests or private emails, I simply don't have time to reply to them all.
    It's better to share your questions and answers on Edaboard so we can all benefit from each others experiences.



  8. #8
    Full Member level 5
    Points: 1,732, Level: 9

    Join Date
    Nov 2016
    Posts
    289
    Helped
    61 / 61
    Points
    1,732
    Level
    9

    Re: Cheap ESD flooring for electronics assembly lab

    You may also want to consider the maintenance of the flooring. Using the wrong cleaners could possibly effect the mats effectiveness. From what I understand some anti static products are designed to retain a small amount of moisture. I haven't a clue as to what products would be best for your situation.



    •   Alt13th June 2018, 15:33

      advertising

        
       

  9. #9
    Full Member level 3
    Points: 1,384, Level: 8
    Relayer's Avatar
    Join Date
    Jul 2016
    Location
    Werribee, Australia
    Posts
    173
    Helped
    50 / 50
    Points
    1,384
    Level
    8

    Re: Cheap ESD flooring for electronics assembly lab

    Hello treez,
    I'm wondering if it would be cheaper to equip all your assembly workers with a retractable
    anti-static wrist strap?
    Regards,
    Relayer



  10. #10
    Advanced Member level 5
    Points: 13,753, Level: 28

    Join Date
    Nov 2012
    Posts
    2,564
    Helped
    596 / 596
    Points
    13,753
    Level
    28

    Re: Cheap ESD flooring for electronics assembly lab

    From what I understand some anti static products are designed to retain a small amount of moisture. ...
    I agree. The common floor times have a porous core but the top surface is glassy and shining. The porous tile adsorbs traces of moisture and has far greater conductivity compared to the tiles covered with the glassy finish.

    The common insulators (you see on high voltage lines) are often made of glass (these days) but older ones are still ceramic with a pre-glaze of glass surface (somewhat like the floor tiles).

    - - - Updated - - -

    I'm wondering if it would be cheaper to equip all your assembly workers with a retractable anti-static wrist strap...
    I still feel that it is worth monitoring the RH (relative humidity) in the work place over a period. If it stays around 90%, then you have nothing to worry at all.

    If the place is air-conditioned (inside cooler than the outside) then the RH value will be higher inside and you have nothing to worry. However, if the place is heated (inside is warmer than the outside), then the RH will be low and you need to worry.

    How about having a conducting surface on the work table? I am just guessing!!


    1 members found this post helpful.

  11. #11
    Member level 3
    Points: 610, Level: 5

    Join Date
    May 2017
    Location
    Canada
    Posts
    61
    Helped
    26 / 26
    Points
    610
    Level
    5

    Re: Cheap ESD flooring for electronics assembly lab

    I've used ESD (conductive) floor wax on ordinary tile and concrete floors. You have to re-apply once or twice a year. It is expensive but less cost than a new floor, with the risk of using "ordinary" flooring materials that turn out bad. A wood laminate floor in our lab was a huge mistake! Worst ever for making static electricity.

    It doesn't solve everything- manufacturing personnel still need ESD ground straps on their shoes, ESD lab coats.


    1 members found this post helpful.

--[[ ]]--