ESD precaution on cheap soldering iron (?)

[Willen]

I have extremly cheap soldering iron (less than $1). I have lots of CMOS ICs, small MOSFETs, JFETs, ESD sensitive LEDs and few tiny chips. I am going to engaged on various hobbyist projects. I also going to buy an Wrist trap. But worrying about my extremely cheap soldering iron. I guess it generates ESD and my house has no earth wire. Also soldering iron has only two wires without earthen wire.

Is it serious situation? If yes then I thought an idea to clip an 'alligator clip' on soldering iron's metal body and ground it with 1Meg series resistor (same as Wrist Trap). Isn't it a good idea? If any other please!

 

[alec_t]

and ground it with 1Meg series resistor (same as Wrist Trap)

What are you going to ground it to if your house wiring has no earth wire?

 

[Willen]

What are you going to ground it to if your house wiring has no earth wire?

I have my own earth connection made by 2 feet aluminium rod placing inside the earth. I am using this earthen connection to listen my batteryless crystal radio. So I decided to connect soldering iron's hot tip or its metal body to this earthen wire through 1Meg resistor for ESD safety. Isn't it good?

 

[alec_t]

That should be better than no earth at all

 

[Willen]

That should be better than no earth at all

Hi alec_t,
I am worrying about my valuable (for me) MOSFETs and CMOS ICs to which I got from few American nice engineers.

Also my soldering iron seems so leaky so sometime it shocks me if I touched earthen and iron both at once. (And now I am whispering- can we upload 'GIF' Avatar here? Your dragon is making flames! )

 

[alec_t]

Can't you get a better (low leakage) soldering iron?

 

[Willen]

I have no money now but collecting...

 

[crutschow]

Connect the soldering iron tip directly to the earth ground, the same as if it had a 3-wire power cable with earth connection. A 1 meg resistor may be too high value to conduct away all the leakage current, especially if you can feel it. But keep the 1 meg resistor for your wrist strap since that protects you from any large currents through your body in case you touch a mains hot lead.

 

[tvtech]

Hi Willen

Here is how it rolls...you need to buy a decent Soldering Iron. I know you have no money now...but maybe try and save a little each week towards something relatively decent. That way you will prevent destroying all the parts you find valuable...

Instead of trying to fix a poor useless Soldering Iron....save your money rather and buy a proper one...

That is about all I can say after around 35 Years of Soldering. Useless Irons make you look bad. No matter hard you try.

Oh well, this did not come out the way I intended, but hopefully will inspire discussion here.

Regards,
tvtech

 

[Willen]

Hi crutschow,

Thank you! But won't it happen- if I connected iron tip directly to earth, I was thinking that if 'parts' have been charged (static charge) to few hundreds of thousands itself and if we let to touch directly earthened iron tip, then I guess it will get huge short between part and tip, won't it? so I was thinking to use 1 Meg series resistor to prevent such direct static short and direct current flow. I don't know what I am thinking.

Hi TVtech,

I have seen advanced soldering in internet included display and controller. I think nobody have such iron here around me. Now I have $0.5 soldering iron. If I tried to buy advanced one around here it just will cost maximum $4. But it has no display and controller too. This expensive one looks like a pen (slim) and tip is also slim and best SMD soldering too. My current cheapest iron has little heavy body and tip too. I don't know how safe these slim ($4) expensive irons are.

 

[crutschow]

Thank you! But won't it happen- if I connected iron tip directly to earth, I was thinking that if 'parts' have been charged (static charge) to few hundreds of thousands itself and if we let to touch directly earthened iron tip, then I guess it will get huge short between part and tip, won't it? so I was thinking to use 1 Meg series resistor to prevent such direct static short and direct current flow. I don't know what I am thinking. ....................

But your part should be on a static mat that's tied to ground through about 1 meg along with your wrist strap. Thus there is no potential difference between any of the items.

 

[Mosaic]

He may not have an antistatic mat, so perhaps a sheet of aluminum foil tied to earth via a 100K resistor? Also if he is not working in A/C and it's the wet season (humid) he may not need to worry about static at all. If he can 'feel' a charge on the soldering iron, I suspect its insulation is failing, which could mean that a direct EARTH from the tip is critical. Next thing, what size breaker or fuse is running the circuit that the iron is using and what voltage is the iron using? The earth wire must be heavy enough to trip that breaker before burning out. No #24 hookup wire here!

 

[crutschow]

Powering the bench from a ground fault interrupter (GFI) is also a good idea. That will trip if the ground current becomes more than a few tens of milliamps.

 

[alec_t]

Not sure a GFI will work if the OP's only earth point is a 2ft aluminium ground rod ?

 

[crutschow]

Not sure a GFI will work if the OP's only earth point is a 2ft aluminium ground rod ?

Actually a GFI does not use (or need) the ground wire. It just monitors the differential current in the hot and neutral wires to see that the difference is not more than about 15mA. Such a difference indicates that some of the hot wire current is flowing directly to ground instead of through the neutral wire which is a fault.

 

[Willen]

..Next thing, what size breaker or fuse is running the circuit that the iron is using and what voltage is the iron using?

The soldering iron is operating through huge 5A main circuit breaker and voltage is 230v standard.

And yes, nice idea to maintain potential difference using static mat for parts. I think I can use any metal wide plate grounded with 100k to 1Meg resistor. Can't I? Here people are not aware about static charge. Some days ago two laptop chip-level mechanics I found and they don't know how to be safe. They are just wearing shoes and they believe that it will protect from short (they are preventing to touch body from ground and making lots of static charges on their body). To one of them, I kindly said what I learnt about static charge and he decided to buy wrist-band, he was nice. Most mechanics I found here are proudy and they think themselves as an engineer!

I am a basic hobbyist who just today heard about GFI. If it is professional device then be sure I never can get this device around here.

 

[crutschow]

.......................................
I am a basic hobbyist who just today heard about GFI. If it is professional device then be sure I never can get this device around here.

They are called GFI's in the USA but their generic name is Residual-current device and they are commonly used in residential and commercial buildings to prevent electrocution at bathroom or outdoor electrical outlets where shock hazzard to ground is more likely. I would think they are available just about everywhere that has public electrical service.

 

[alec_t]

Such a difference indicates that some of the hot wire current is flowing directly to ground instead of through the neutral wire which is a fault.

I am aware of the operating mode of GFIs /RCDs, I was just wondering whether a 2ft (inevitably corroded/oxidised) aluminium rod driven into the ground would provide a low enough impedance to ground for sufficient fault current to operate the trip?

 

[crutschow]

I am aware of the operating mode of GFIs /RCDs, I was just wondering whether a 2ft (inevitably corroded/oxidised) aluminium rod driven into the ground would provide a low enough impedance to ground for sufficient fault current to operate the trip?

If the current is insufficient to trip the GFI then it's below the danger level for electrocution so he would be safe either way.

 

[alec_t]

Good point.