System and method for determining the polarity of an electrostatic event

• US 6,396,255 B2
• Filed: 01/05/2001
• Issued: 05/28/2002
• Est. Priority Date: 09/18/1995
• Status: Expired due to Fees

• Current Assignee: James P. Karins, Niels F. Jacksen
• Original Assignee: James P. Karins, Niels F. Jacksen
• Inventors: Jacksen, Niels F., Karins, James P.
• Primary Examiner(s): KARLSEN, ERNEST F
• Application Number:
  US09/755,713
• Publication Number:
  US 20010002103A1
• Time in Patent Office: 508 Days
• Field of Search: 324/96,72,102,103 P,122,133,244.1 340/600 359/280,282,295
• US Class Current: 324/96
• CPC Class Codes: G01R 31/002 where the device under test is an electronic circuit
• CPC Class Codes: G01R 5/28 Electrostatic instruments
• CPC Class Codes: H05K 1/0254 High voltage adaptations; Electrical insulation details; Overvoltage or electrostatic discharge protection electrostatic discharge protection for electric apparatus in general H05K9/0067, H05K9/0079; Arrangements for regulating voltages or for using plural voltages
• CPC Class Codes: H05K 1/0266 Marks, test patterns or identification means

Abstract

A reusable miniaturized detector that utilizes magneto-optic elements to detect the occurrence of an electrostatic discharge during the manufacture or handling of electrostatic discharge sensitive electronic components and circuit boards. The device may also be used to determine the polarity and magnitude of the electrostatic discharge. The device may be manually or automatically read, either by removing the device from the environment being monitored or continuously monitoring in situ. The device can also be configured to provide protection to some electrostatic discharge events which could damage sensitive components being monitored.

Claims

1. An electrostatic discharge event detector comprising:

a substrate;

at least one conductor patterned from a metal layer deposited on the substrate, the conductor acting as an antenna for receiving a voltage produced by an electrostatic discharge, the received voltage inducing a current to flow through the conductor sufficient to generate a magnetic field having a field polarity around the conductor;

a first magneto-optic element having a first magnetic state having a first polarity;

a second magneto-optic element having a first magnetic state having a second polarity, the second polarity being opposite from the first polarity of the first magnetic state of the first magneto-optic element, the first and second magneto-optic elements being formed from a film deposited on the substrate and patterned such that the first and second magneto-optic elements are formed on opposite sides of the conductor, the first and second magneto-optic elements being capable of switching from the first magnetic state to a second magnetic having a polarity opposite of the polarity of the first magnetic state in response to a magnetic field having a polarity opposite of the polarity of the first magnetic state and having a field strength that exceeds a predetermined field strength at the location of the magneto-optic element.

2. The detector claim 1 wherein the first and second magneto-optic elements form a first pair of magneto-optic pixels, and further comprising at least one additional pair of magneto-optic pixels located on opposite sides of the conductor.

3. An electrostatic discharge event detector for detecting the occurrance and polarity of an electrostatic event comprising:

a substrate;

at least one conductor formed on the substrate, the conductor forming an antenna capable of receiving a voltage induced by an electro-static event having a polarity, the received voltage causing a current to flow in the conductor in a direction related to the polarity of the electrostatic event, the current flow in the conductor causing a magnetic field to be formed about the conductor, the magnetic field having a field polarity related to the polarity of the electro-static event;

a set of magneto-optic elements formed on the substrate and located adjacent to the conductor, each magneto-optic element having a first magnetic state having a first polarity and being capable of switching to a second magnetic state having a second polarity different from the first polarity in response to the field polarity of the magnetic field formed about the conductor when the magnetic field has a field strength that exceeds a predetermined field strength at the location of the magneto-optic element and a field polarity opposite to the first polarity of the magneto-optic element;

a second set of magneto-optical elements formed on the substrate and located adjacent to the conductor on a side opposite the first set of magneto-optical elements, each magneto-optic element of the second set having a first magnetic state having a first polarity and being capable of switching to a second magnetic state having a second polarity different from the first polarity in response to the field polarity of the magnetic field formed about the conductor when the magnetic field has a field strength that exceeds a predetermined field strength at the location of the magneto-optic element and a field polarity opposite to the first polarity of the magneto-optic element.

4. The detector of claim 3, wherein the first magnetic state of the magneto-optic elements has a first direction and the second magnetic state of the magneto-optic elements has a second direction and the magnetic field around the conductor has a direction dependent on the polarity of the electrostatic event, and wherein the magneto-optic elements change from the first magnetic state to the second magnetic state in response to the magnetic field when the direction of the magnetic field is different from the first direction of the first magnetic state of the magneto-optic elements.

5. A method for determining the polarity of an electrostatic discharge comprising the steps of:

providing an electrostatic discharge event detector having a conductor and a pair of magneto-optic elements located on opposite sides of the conductor, the elements having a first magnetic state and a second magnetic state and capable of switching between the first and second magnetic states in response to an electro-magnetic field generated in the conductor by an electrostatic discharge;

detecting an electrostatic discharge in a general area of the location of the detector by sensing when a current is induced in the conductor by the electrostatic discharge, the induced current generating the electro-magnetic field around the conductor, the generated electromagnetic field having a polarity and a field strength representative of the polarity and magnitude of the electrostatic discharge;

determining the magnetic state of the magneto-optic elements by illuminating the magneto-optic elements with polarized light and observing the light from the elements, wherein the polarity of the electrostatic discharge is determined by observing which one of the elements has the second magnetic state and which element has the first magnetic state.