Conductive polymer device and method of manufacturing same

• US 6,429,533 B1
• Filed: 11/23/1999
• Issued: 08/06/2002
• Est. Priority Date: 11/23/1999
• Status: Expired due to Fees

• Current Assignee: Bourns Incorporated
• Original Assignee: Bourns Incorporated
• Inventors: Li, Wen Been, Yang, Kun Ming
• Primary Examiner(s): Williams, Alexander O.
• Application Number:
  US09/448,051
• Time in Patent Office: 987 Days
• Field of Search: 257/783, 257/700, 257/701, 257/758, 257/746, 257/748, 257/753, 257/759, 257/760, 257/762, 257/766, 257/773, 257/793, 338/22.R, 338/307, 338/309, 338/308
• US Class Current: 257/783
• CPC Class Codes: H01C 1/1406 Terminals or electrodes formed on resistive elements having positive temperature coefficient
• CPC Class Codes: H01C 7/021 formed as one or more layers or coatings

Abstract

An electronic device includes a first conductive polymer layer sandwiched between a first external metal foil electrode and a first internal metal foil electrode, a second conductive polymer layer sandwiched between a second internal metal foil electrode and a second external metal foil electrode, a layer of fiber-reinforced epoxy resin bonding the first and second internal electrodes together, a first terminal providing electrical contact between the first internal electrode and the second external electrode, and a second terminal providing electrical contact between the second internal electrode and the first external electrode. In a preferred embodiment, the polymer layers exhibit PTC behavior, and the terminals are formed by a solder layer applied over a plated layer of conductive metal. Insulative layers are preferably provided on the external electrodes, and located so as to insulate the first and second terminals from each other. Thus configured, the first and second polymer layers are connected in parallel between the first and second terminals by the first and second internal electrodes and the first and second external electrodes.

Claims

1. An electronic device having first and second opposed end surfaces, the device comprising:

a first conductive polymer layer sandwiched between a first external electrode and a first internal electrode;

a second conductive polymer layer sandwiched between a second internal electrode and a second external electrode;

a layer of fiber-reinforced epoxy resin bonding the first and second internal electrodes together;

a first terminal providing electrical contact between the first internal electrode and the second external electrode; and

a second terminal providing electrical contact between the second internal electrode and the first external electrode.

2. The electronic device of claim 1, wherein the electrodes are made of a metal foil.

3. The electronic device of claim 2, wherein the metal foil is made of a material selected from the group consisting of nickel and nickel-coated copper.

4. The electronic device of claim 1, wherein the first, second, and third conductive polymer layers are made of a material that exhibits PTC behavior.

5. The electronic device of claim 1, wherein the first and second terminals are formed by a solder layer applied over a plated layer of conductive metal.

6. The electronic device of any of claims 1, 2, 3, 4 , or 5, further comprising an insulative layer on each of the first and second external electrodes and located so as to insulate the first and second terminals from each other.

7. The electronic device of any of claims 1, 2, 3, 4, or 5, wherein the first and second conductive polymer layers are connected in parallel between the first and second terminals by the first and second internal electrodes and the first and second external electrodes.