You are Here: Home >< Physics

# A2 electric fields - static electricity & earthing watch

1. Attachment 501277501279Hi,

I'm having a bit of trouble understanding earthing & charging, and in the both (see the photos), it seems to contract itself. Not quite sure exactly what "earthing" is (Google search didn't seem to give a definitive answer)

For example with the microchips;

If when the pins are touched and become earthed, surely this means they now become uncharged? So no longer remain charged as it says?

Thanks
Attached Images

2. (Original post by JohnnyDavidson)
Attachment 501277501279Hi,

I'm having a bit of trouble understanding earthing & charging, and in the both (see the photos), it seems to contract itself. Not quite sure exactly what "earthing" is (Google search didn't seem to give a definitive answer)

For example with the microchips;

If when the pins are touched and become earthed, surely this means they now become uncharged? So no longer remain charged as it says?

Thanks
The wording in the text is poor making it ambiguous.

It's trying to say:

The Earth (planet) can be considered as an infinite source or sink of electrons and as such is the reference for all other charges. Because it so overwhelmingly massive in comparison to anything else (including clouds) any charge build up on an object will try to flow back to the earth as a current through the lowest resistance conduction path.

Earthing or grounding literally means creating a conduction path to the earth.

Semiconductors or Very Large Scale Integrated Circuits (VLSI microchips) can easily be destroyed by even small amounts of current discharging to anything that creates a conduction path if a charge build up is allowed to occur.

Charge build up can be caused by handling an isolated/insulated device and when a conduction path is created (such as when a person touches the pins) the different charges try to equalise (different voltage potentials) and a current is created. That means including conduction paths from the pins to earth if a charge is allowed to build up on the pins which is not earth potential.

The way to prevent such damage is to never allow the build up of charge either more positive or more negative than earth potential. i.e. the devices are manufactured in strict conditions with all manufacturing processes at earth potential.

When the manufacturing process is complete, the devices are stored in protective anti-static bags which first and foremost prevent the build up of charge by dissipating charges to the atmosphere or ground long before they reach a damaging potential.

It means that handling devices must always be carried out at an earthed or grounded workstation since both the device and anything it then comes into contact with are at the same voltage potential and no current can flow.

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: February 12, 2016
Today on TSR

Will it ever be possible?

### University open days

1. University of Cambridge
Wed, 26 Sep '18
2. Norwich University of the Arts
Fri, 28 Sep '18
3. Edge Hill University
Faculty of Health and Social Care Undergraduate
Sat, 29 Sep '18
Poll

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE