Michael J Weber

US Patent:

6351011, Feb 26, 2002

Filed:

Jan 12, 2000

Appl. No.:

09/481927

Inventors:

Stephen J. Whitney - Lake Zurich IL
Jeffrey S. Niew - Burr Ridge IL
Michael J. Weber - Wheeling IL

Assignee:

Littlefuse, Inc. - Desplaines IL

International Classification:

H01L 2362

US Classification:

257355, 257787, 257659

Abstract:

A number of integrated circuit dies having on board protection against electrical overstress (EOS) transients are provided. Generally, the devices have an integrated circuit die with an outer periphery and a functional die area. A plurality of conductive input/output pads are formed on the integrated circuit die. Typically, a first conductive guard rail is disposed on the integrated circuit die and forms a gap between each one of the input/output pads. A voltage variable material is disposed in the gaps between the conductive guard rail and the input/output pads. Typically, a plurality of electrical leads are electrically connected to a respective one of the plurality of conductive input/output pads. At normal operating voltages, the voltage variable material is non-conductive. However, in response to an EOS transient, the voltage variable material switches to a low resistance state, providing a conductive path between the conductive guard rail and the input/output pads.

US Patent:

6582647, Jun 24, 2003

Filed:

Sep 30, 1999

Appl. No.:

09/408645

Inventors:

Tom J. Hall - Arlington Heights IL
Michael J. Weber - Arlington Heights IL

Assignee:

Littelfuse, Inc. - Des Plaines IL

International Classification:

B29C 7100

US Classification:

264345, 264340

Abstract:

The present invention provides a method for heat treating a polymer PTC composition to increase the peak resistivity of the composition making it especially well suited for high voltage applications. A polymer PTC composition having a melting point temperature T is provided. The temperature of the polymer PTC composition is increased at a rate, r , to a temperature greater than T. The temperature of polymer PTC composition is held at the temperature greater than T for a predetermined period of time. Then the temperature of the polymer PTC composition is decreased to a temperature less than T at a rate, r , wherein r is greater than r.

US Patent:

59409584, Aug 24, 1999

Filed:

May 29, 1996

Appl. No.:

8/654528

Inventors:

Philip C. Shaw - Elk Grove Village IL
Donna L. Randle - Chicago IL
Michael J. Weber - Arlington Heights IL
Michael J. Hoss - Des Plaines IL
Tom J. Hall - Arlington Heights IL

Assignee:

Littlefuse, Inc. - Des Plaines IL

International Classification:

H01C 702
H01R 4302

US Classification:

29612

Abstract:

Electrical devices comprising a PTC element comprised of a polymer having conductive particles dispersed therein. The PTC element is coated with a conductive layer and has electrodes with a plurality of voids affixed to opposing surfaces. The devices are made by dispersing conductive particles into a polymer to form a polymer PTC composition. The polymer PTC composition is melt-shaped to form a laminar shaped PTC element. First and second opposing surfaces of the PTC element are coated with a conductive layer. The electrodes, characterized by a plurality of voids, are brought into contact with the coated surfaces of the PTC element, and heated while applying pressure to form a laminate. The laminate is then further shaped into a plurality of PTC electrical circuit protection devices.

US Patent:

59559365, Sep 21, 1999

Filed:

May 20, 1997

Appl. No.:

8/859624

Inventors:

Philip C. Shaw - Elk Grove Village IL
Donna L. Randle - Chicago IL
Michael J. Weber - Arlington Heights IL
Michael J. Hoss - Des Plaines IL
Tom J. Hall - Arlington Heights IL

Assignee:

Littlefuse, Inc. - Des Plaines IL

International Classification:

H01C 710

US Classification:

338 22R

Abstract:

Electrical devices having a PTC element of a polymer having conductive particles dispersed therein. The PTC element is coated with a conductive layer and has electrodes with a plurality of voids affixed to opposing surfaces. The devices are made by dispersing conductive particles into a polymer to form a polymer PTC composition. The polymer PTC composition is melt-shaped to form a laminar shaped PTC element. First and second opposing surfaces of the PTC element are coated with a conductive layer. The electrodes, characterized by a plurality of voids and made of foam, are brought into contact with the coated surfaces of the PTC element, and heated while applying pressure to form a laminate. The laminate is then further shaped into a plurality of PTC electrical circuit protection devices.