Browse Prior Art Database

Spark Gap on Module to Protect MOS LSI Chips

IP.com Disclosure Number: IPCOM000087395D
Original Publication Date: 1977-Jan-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 20K

Publishing Venue

IBM

Related People

DeBar, DE: AUTHOR [+2]

Abstract

A modification to the existing spark gap/protective diode circuit for an LSI chip causes the spark gap to discharge before the protective diode, when the magnitude of the electrostatic voltage is sufficiently high, to prevent damage to the protective diode.

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Spark Gap on Module to Protect MOS LSI Chips

A modification to the existing spark gap/protective diode circuit for an LSI chip causes the spark gap to discharge before the protective diode, when the magnitude of the electrostatic voltage is sufficiently high, to prevent damage to the protective diode.

The IBM Technical Disclosure Bulletin, Vol. 18, No. 7, December 1975, pp. 2220-2221 describes a module spark gap which can be connected in parallel with a protective diode device which, in turn, is connected between the substrate of the LSI chip and the gate of the MOSFET device to be protected. The figure shows the existing spark gap 2 which is located on the module substrate, connected in parallel with the protective diode 4, which in turn is connected in parallel between the substrate of the chip and the gate of the MOSFET device 6 to be protected.

In order to better match the response times of the protective diode 4 and the spark gap 2, a delay is introduced between the spark gap 2 and the protective diode 4 by means of the resistor 8 which may be located either on the module substrate itself or on the semiconductor chip, and is connected between the spark gap 2 and the protective diode 4. For an approximately 2pFd input capacitance, a 2 K-ohm resistor is sufficient to provide protection against a 150 pFd capacitor charged to 6000 volts and discharged through 1800 ohms. Without the resistor 8, the old combination of a spark gap 2 and a protective diode 4 can pro...