T he dangers of electrostatic discharge esd although

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T HE DANGERS OF ELECTROSTATIC DISCHARGE (ESD) Although electrostatic discharge (ESD) is most clearly seen in sparks, it can take many other forms, which are less spectacular but nevertheless dangerous. Electrostatic discharge is defined as the transfer of charge between bodies at different electric potentials. <Sidebar> Electrostatic discharge is the transfer of charge between bodies at different electric potentials. In order to appreciate the danger of ESD for electronic devices, study the following case. Assume that a technician, who just walked across carpet and accumulated a static electric charge on his/her body, is going to install a memory chip in your laptop. The chip has many transistors and other electronic components, which include thin layers of insulators necessary for proper functioning. (You will learn about MOSFET transistors and flash memory further in the course). Suppose that some of the connectors of this memory chip are grounded, which means that they have zero electric potential (see below), while the technician touches another connector. Then the excess electric charges from the human body will repel each other (they are of the same sign!) and try to escape to the ground through the chip! As mentioned above, the chip includes layers of insulators, which would try to prevent this transfer of charges. The problem is that the transistors in the memory chip are very small (tens of nanometers), and their insulating layers are extremely thin. Voltages as low as 100 V can break down these insulators, producing permanent damage, which would lead to malfunction of the chip. As you remember, the voltage on the human body after walking across carpet may exceed 1,500 V thus the damage to the memory chip may be inevitable and beyond repair. Book Page 131
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EE for 21 st century 1-3 Prevent electrostatic discharge 1-3-1 Hazards of ESD for EE © 2015 Alexander Ganago Page 9 of 23 Last printed 2015-07-24 6:00 PM File: 2015 1-3-1 ESD.docx <Sidebar> Voltages as low as 100 V can cause ESD damage to electronic devices. This example highlights the necessity for precautions in handling electronics. Indeed, a good technician would first ground his/her body to get rid of possible static charges before opening the package with the memory chip and/or touching the inside of your laptop. Damage to electronic devices may cause defects of various types, including: ü Catastrophic, which immediately lead to total failure, or ü Latent, which are more difficult to identify: the device may be partially degraded, would have dramatically reduced operating life, etc. <Sidebar> ESD damage to electronic devices may be catastrophic or latent. Even worse, when a damaged memory chip is installed in your laptop, the entire laptop may fail prematurely. <Sidebar> An electronic device damaged by ESD may cause failure of the product where it is installed.
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  • Fall '07
  • Ganago
  • Electric charge, Alexander Ganago

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