What is ESD?
Accumulation of electrostatic charges on an insulated surface which stay at rest is what we call static electricity, these charges, once given particular environmental
conditions and depending of the type of materials involved may discharge with an abrupt dissipation of energy giving existence to the ESD mechanism, ESD stands for ElectroStatic Discharge. ESD is a physics
phenomena inherent to the very elementary particles in the atoms, the electrons. Electrons move in between atoms in the
lattice structure of a body or
in between bodies, atoms exhibit lack or excess of electrons. A common static charge generation mechanism is friction produced in between surfaces of bodies, the heat produced contributes to agitate the atoms and hence making it easier for electrons to detach. Similarly, but without the heat component, two surfaces briefly touching and then abruptly separating make electrons to transfer in between the surfaces generating static charges in both surfaces
(triboelectricity). The effect of
electrostatic discharges is known to most people as in large lightning bolts during storms or in a much reduced scale as a zap when reaching for a metallic door knob.
Materials which allow for an easy transfer of electrons in between atoms are called conductors, the electrons in good conductors roam quite freely in the lattice of the materials, particularly in metals. Those materials
known to oppose electron movements are called insulators and there is a range of materials in between these two extremes. The human body on average and through the skin will not feel an ESD spark under 3,000V as de current involved will be under the skin perception threshold, however many
electronic devices can be damaged with discharges with potentials under 100V and even under 10V.
When too many charges of the same polarity reside on a small surface their repulsion from each other is so great that an ESD spark will happen in order to alleviate the excessive repulsive forces. The spark or
arc bridges the gap in between materials allowing for an even redistribution of the electrons on both surfaces, after the spark lower repulsive forces in between the charges is achieved due to a more distant redistribution, a precise equidistance in between charges only occurs over an sphere. The bridging arc
or spark is of very short duration (in the ps range) and produces high frequencies' interference , sometimes in
the 30+ gigahertz region. The size of the energy transferred will be limited by the media in between the two bodies for example if this is air then relative humidity, air contaminants, temperature, etc… will limit the size of the energy discharge. Nevertheless the spark
represents a transfer of energy dissipation and can be approximated in the lab.
|ESD has a very damaging effect on electronic circuitry and has been proven to produce many latent flaws which in the end translate into catastrophic failure of the devices, hence a shorter lifespan. Electronic devices are exposed to damage along their entire path from the manufacturing line to their installation, mainly due to personnel handling. A catastrophic failure makes the device to stop working or malfunction due to possible internal metallic run melting perhaps by creating a short circuit between the conductive runners through isolating strips, or by vaporising a conductive track which creates an open circuit, in such a case the device is permanently damaged.|