antistatic mat for K3 assembly

[Franki ON5ZO]

With my K3 anticipated less than 4 weeks (as much fingers crossed as
anatomically possible) I am preparing the assembly line.

I don't have an antistatic mat but do have a bracelet available with a
crocodile clamp lead. Would it be wise to use a big aluminum plate to
replace the antistatic mat and clamp the crocodile on that sheet?
I found a antistatic thingy at an online salespoint for 80 Euro (+50$) ex
S/H, so I'm a bit reluctant because I have no further use for such a thing.

TNX for the input and 73,
Franki ON5ZO
http://on5zo.spaces.live.com/ 

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[Julian, G4ILO]

Franki ON5ZO wrote

With my K3 anticipated less than 4 weeks (as much fingers crossed as
anatomically possible) I am preparing the assembly line.

I don't have an antistatic mat but do have a bracelet available with a
crocodile clamp lead. Would it be wise to use a big aluminum plate to
replace the antistatic mat and clamp the crocodile on that sheet?
I found a antistatic thingy at an online salespoint for 80 Euro (+50$) ex
S/H, so I'm a bit reluctant because I have no further use for such a thing.

I got one at Maplin (maplin.co.uk) for about GBP 20, though that may not be too much help to you in Blegium.

I wouldn't use a metal plate since a) you could scratch or damage the paint in some of the assembly operations and b) the static mat is supposed to dissipate the static gently not through a low resistance path as aluminium would.

I never used an anti-static mat before, and probably it is possible to assemble a K3 taking the same care I have for most of my life when handling static sensitive components, but given the cost of the K3 components I decided it wasn't worth risking it.

[KBG Luxford]

Hi Franki,

I would suggest that you find a way of connecting the crocodile clip to
mains Earth in some way.  Maybe you have a piece of equipment with a
metal case which is connected to your electrical supply by a three prong
plug (hot, neutral and earth).  You do need to make sure that the case
is connected to the earth prong on your plug which you can do by an
ohmmeter connected to the case and the earth prong after the plug has
been withdrawn from the electrical outlet.  Once you have established
that the connection from the metal case to the earth prong is intact,
then put the plug back into the supply outlet, (no need to switch on the
equipment) and clip the crocodile clip to an unpainted part of the case.

I can not advise you on how essential would be an anti-static mat,
however, they are not expensive and certainly far less than the cost of
replacing sensitive components.

In my own case, I have mounted a number of power boards on a metal case,
and power to the whole lot is controlled by a 15 amp rocker switch
containing a neon light.  The power boards are used to supply power to
test equipment, soldering irons and so forth, not more than two or three
items are actually on at the same time.  I have also included a 15 Amp
moving iron meter to monitor the total current drawn from the power
supply system.

This means only one switch is needed to control all the power to my
workshop.  And other family members can see whether the old man has left
the power on or not - especially when we are all vacating the house for
some time.

Now down at the bottom of the metal panel, I have three, green coloured
4 mm banana sockets for plugging in anti-static mats and wrist straps.
The banana sockets, of course, are all connected to mains earth.

The anti-static wrist-strap should have something like a 1 megohm
resistor between the conductive strap and its connector at the end of
its spiral cord.  The resistor does not impede the draining of charge,
and it is there to help protect you in case you touch something at a
dangerous potential.

I hope that this is of some help to you.

73
Kevin
VK3DAP / ZL2DAP



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[M0XDF]

In my experience, all the leads of ESD equipment have a 1M ohm  
resistor in them, normally moulded into the banana plug.

And Yes you need an antistatic wrist strap and a mat (I also connected  
the earth of the motherboard to my ESD point while building).
All the leads need to go to one point (not a daisy chain) and that  
needs to be connected to Mains Safety Earth.
I modified my Soldering station (which has an earthed tip) to add 4  
banana plug sockets connected directly to the mains earth of the  
station. now I have a convenient set-up with the ESD leads terminating  
at one point.

Even if it might be possible to assemble the K3 without the mat, the  
manual stresses in many places you must take ESD precautions, so if  
something was faulty, you might not get a warranty repair in you  
didn't. Besides, you've waited all this time for the K3, is it worth  
the £20 or so to have to wait again if something does blow?
And, if you ever work on the K3, take a board out or fit another  
option (the KRX3 for example), you'll need to use it again. The mats  
are slightly soft and make a good working surface and help prevent  
scratches etc.

It's worth the small investment.


73 de M0XDF, K3 #174
--
Hofstadter's Law: The time and effort required to complete a project are
always more than you expect, even when you take into account  
Hofstadter's
Law.

On 12 May 2008, at 09:05, KBG Luxford wrote:

> The anti-static wrist-strap should have something like a 1 megohm  
> resistor between the conductive strap and its connector at the end  
> of its spiral cord.  The resistor does not impede the draining of  
> charge, and it is there to help protect you in case you touch  
> something at a dangerous potential.

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