Apparatus, system, and method for electrostatic discharge protection

• US 7,567,419 B2
• Filed: 06/10/2005
• Issued: 07/28/2009
• Est. Priority Date: 06/10/2005
• Status: Expired due to Fees

• Current Assignee: Kyocera Corporation
• Original Assignee: Kyocera Wireless Corporation (Kyocera Corporation)
• Inventors: Lu, Lin, Poynot, Andrew Stephen
• Primary Examiner(s): Leja; Ronald W
• Application Number:
  US11/150,559
• Publication Number:
  US 20060279887A1
• Time in Patent Office: 1,509 Days
• Field of Search: 361/56, 361/112, 361/220
• US Class Current: 361/220
• CPC Class Codes: H01H 2239/008 Static electricity considerations
• CPC Class Codes: H04M 1/23 Construction or mounting of dials or of equivalent devices; Means for facilitating the use thereof by improving visibility H04M1/22
• CPC Class Codes: H05K 1/0256 Electrical insulation details, e.g. around high voltage areas
• CPC Class Codes: H05K 1/0259 Electrostatic discharge [ESD] protection
• CPC Class Codes: H05K 9/0067 Devices for protecting against damage from electrostatic discharge

Abstract

An apparatus, system, and method provide electrostatic discharge (ESD) protection in electronic devices by guiding electrostatic charges to a ground through ESD channels within electrical insulation sheet. The ESD channels are positioned within the electrical insulation sheet to provide electrical paths to ground having a lower impedance than electrical paths to protected areas covered by the electrical insulation sheet. Accordingly, an ESD follows the path of least resistance safely to ground rather than to a critical component within the electronic device. In the exemplary embodiment, the ESD channels are openings in a dome contact layer of a keypad where the openings are positioned over one or more ground areas of a printed circuit board (PCB) and the insulting material of the dome contact layer covers areas of the PCB that are protected from ESD. By implementing dedicated GPIO lines, grounded metal domes cover the signal pads in the target discharge area to protect the GPIO lines from ESD. Device components are protected from ESD without additional ports or insulation.

Claims

1. An electrostatic discharge (ESD) protection device comprising:

an electrical insulation sheet having an insulation electrical impedance and having a discharge channel comprising a layer of electrical insulation material within the electrical insulation sheet that is thinner than other regions of the electrical insulation sheet and extending to a ground area of a printed circuit board, having a channel electrical impedance less than the insulation electrical impedance and configured to direct an electrostatic discharge to the ground area.

2. An ESD protection device in accordance with claim 1, wherein the discharge channel further comprises an opening within the electrical insulation sheet positioned adjacent to the ground area of the printed circuit board.

3. An ESD protection device in accordance with claim 1, wherein the electrical insulation sheet is a dome contact sheet comprising a plurality of dome contacts configured to make electrical connections on the printed circuit board when deformed.

4. An ESD protection device in accordance with claim 1, wherein the electrical insulation sheet has a plurality of discharge channels having channel impedances less than the insulation electrical impedance.

5. An electronic portable device comprising:

a printed circuit board comprising a ground area;

an electrical insulation sheet having an insulation electrical impedance and having a discharge channel comprising a layer of electrical insulation material within the electrical insulation sheet that is thinner than other regions of the electrical insulation sheet and having an channel electrical impedance less than the insulation electrical impedance, the electrical insulation sheet positioned adjacent to the printed circuit board to align the discharge channel over at least a portion of the ground area.

6. An electronic portable device in accordance with claim 5, wherein the discharge channel is configured to direct an electrostatic discharge originating on a side opposite the printed circuit board to the ground area.

7. An electronic portable device in accordance with claim 5, wherein the electrical insulation sheet comprises a plurality of dome contacts positioned adjacent to a plurality of contact pads on the printed circuit board, each dome contact configured to form an electrical connection between a center contact pad and a peripheral contact pad when deformed.

8. An electronic portable device in accordance with claim 7, wherein peripheral contact pad comprises a ground potential contact area.

9. An electronic portable device in accordance with claim 8, further comprising:

a housing at least partially enclosing the printed circuit board and the electrical insulation sheet; and

device circuitry within discharge avoidance areas, the portable electronic device having at least one device discharge path extending from an exterior of the housing through the discharge channel to the ground area and having a path impedance less than any undesired discharge path passing through the device circuitry.

10. An electronic portable device in accordance with claim 9, wherein the device circuitry comprises signal traces on the printed circuit board.

11. An electronic portable device in accordance with claim 9, wherein the device circuitry comprises electrical components on the printed circuit board.

12. An electronic portable device in accordance with claim 9, wherein the device circuitry comprises wires extending from the printed circuit board.

13. An electronic portable device in accordance with claim 5, wherein the discharge channel further comprises an opening within the electrical insulation sheet positioned adjacent to the ground area of the printed circuit board.

14. A portable communication device comprising:

a printed circuit board comprising a ground area and a plurality of contact pad sets comprising a center contact area and a peripheral contact area;

an electrical insulation sheet comprising a plurality of dome contacts positioned over the contact area pairs and configured to form an electrical connection between a corresponding center contact area and a corresponding peripheral contact area, the electrical insulation sheet having a plurality of discharge channels comprising a layer of electrical insulation material within the electrical insulation sheet that is thinner than other regions of the electrical insulation sheet and having electrical impedances less than a sheet electrical impedance of the electrical insulation sheet, the discharge channels positioned adjacent to at least portions of the ground area.

15. A portable communication device in accordance with claim 14, wherein the discharge channels are configured to direct an electrostatic discharge originating on a side opposite the printed circuit board to the ground area.

16. A portable communication device in accordance with claim 14, wherein the peripheral contact pad comprises a ground potential contact area.

17. A portable communication device in accordance with claim 14, further comprising:

a housing at least partially enclosing the printed circuit board and the electrical insulation sheet; and

device circuitry within discharge avoidance areas, the portable communication device having at least one device discharge path extending from an exterior of the housing through the discharge channel to the ground area and having a path impedance less than any undesired discharge path passing through the device circuitry.

18. A portable communication device in accordance with claim 17, wherein the device circuitry comprises signal traces on the printed circuit board.

19. A portable communication device in accordance with claim 17, wherein the device circuitry comprises electrical components on the printed circuit board.

20. A portable communication device in accordance with claim 17, wherein the device circuitry comprises wires extending from the printed circuit board.

21. A portable communication device in accordance with claim 17, further comprising an electrically conductive button, device discharge path passing through electrically conductive button.

22. A portable communication device in accordance with claim 14, wherein each of the discharge channels further comprises an opening within the electrical insulation sheet positioned adjacent to the ground area of the printed circuit board.