If you would like to attend an ESD (ElectroStatic Discharge) Workshop at our suppliers in Germany this year, please click here for more info.
Static charge build-up is enhanced when the air is dry. So, static problems and effects are most often noticed in dry air conditions. The air outside can be very dry when the weather is cold. Indoors, central heating or air conditioning can create very dry conditions which promotes static electricity. Heating warms the air and reduces its humidity. Static shocks are most often noticed in cold dry weather, especially when in a centrally heated environment. Usually static shocks disappear when the weather gets more humid. Static shocks can also occur in air conditioned building during hot weather.
ESD Electro Static Discharge
Everyone who works with electronics has heard about static damage. Unfortunately, there is often as much miss-information as there is hard fact. First of all static electricity does no harm; it is not until there is a discharge (ESD) that we have to worry. ( It is the 'D' in ESD that blows holes in electronic gates!) Sadly, a lot of snake-oil products are sold to make you feel like you have taken care of 'The static problem'. All that you need to keep the marketing types from preying on you whether you are a hobbyist, technician or engineer, is an understanding based in science. Once you realize that the laws of physics are not suspended for ESD (electrostatic Discharge) you will find that you already know most of the basics.
What is static electricity?
Static electricity is electricity that is static; that is electricity that doesn't move. When you walk across a carpet on a dry winter day, you build up a static charge. As your shoes rub on the carpet there is a net wiping off of electrons that gives your body a potential that is different to ground. If the air were more humid, the charge would bleed off rapidly but on a dry winter day the charge stays on the surface of your skin for a few seconds. Static electricity is a surface phenomenon. The more surface area the greater the charge stored.
What is electrostatic discharge?
Static electricity doesn't do any damage until it is discharged - and is then called electrostatic discharge or ESD. Quite simply, electrostatic discharge is a spark.
When you walk across the carpet on a cold winter day, the wiping motion of your feet produces a charge separation that is collected and distributed evenly about the surface of your moist and salty (thus conductive) skin. When you reach for the doorknob a spark jumps from your conductive skin to the conductive doorknob. If you felt the spark, you had a potential of at least 3500 volts. Every day, when you touch conductive items, small sparks are produced that can't be felt yet have enough energy to damage electronics.
Requirements for electrostatic discharge
Two things are required to allow ESD:
- A charge separation.
- Two associated conductors that collect charge and are brought together initiating the discharge.
Knowing these two requirements puts us in position to rationally tackle the job of preventing ESD. The first requirement to have ESD is that there is a static charge separation; the second requirement is that there is a conductor (for the purposes of this discussion the only meaningful ones are metal, metallic carbon and our skin's sweat layer). ESD always occurs between two conductive surfaces - If you touch the enamel paint (which is non-conductive) on your computer cabinet, no spark will form. You might have noticed that over the years electronic products have gone from having spark producing exposed conductive metal cabinets, to having non conductive materials on the outside that prevents ESD. Designers have figured out that it takes a spark to have ESD, so modern electronic products now have their conductive shielding layers buried in insulating plastic.
Should you require any help or assistance with ESD drop us an email or give us a call, we will be glad to assist.
Here are some usefull items to help you in the battle against ESD
We have ESD testing video's here
Best regards
John Christensen
