Geometric and electric field considerations for including transient protective material in substrate devices

• US 8,362,871 B2
• Filed: 10/28/2009
• Issued: 01/29/2013
• Est. Priority Date: 11/05/2008
• Status: Active Grant

• Current Assignee: Littelfuse Incorporated
• Original Assignee: Shocking Technologies, Inc.
• Inventors: Kosowsky, Lex, Fleming, Robert, Shi, Ning
• Primary Examiner(s): LEE, KYUNG S
• Application Number:
  US12/607,952
• Publication Number:
  US 20100109834A1
• Time in Patent Office: 1,189 Days
• Field of Search: 338/314, 338/21, 338/22.R, 361/56, 361/760, 361/220, 361/117, 361/212, 257/409, 257/484, 257/605, 257/630
• US Class Current: 338/314
• CPC Class Codes: H01C 7/12 Overvoltage protection resistors series resistors structurally associated with spark gaps H01T1/16
• CPC Class Codes: H05K 1/0257 Overvoltage protection
• CPC Class Codes: H05K 1/0259 Electrostatic discharge [ESD] protection
• CPC Class Codes: H05K 1/115 Via connections; Lands around holes or via connections H05K1/112 takes precedence
• CPC Class Codes: H05K 1/167 incorporating printed resistors
• CPC Class Codes: H05K 2201/0738 Use of voltage responsive materials, e.g. voltage switchable dielectric or varistor materials
• CPC Class Codes: H05K 2201/09736 Varying thickness of a single conductor; Conductors in the same plane having different thicknesses
• CPC Class Codes: H05K 2201/09781 Dummy conductors, i.e. not used for normal transport of current; Dummy electrodes of components

Abstract

A substrate device includes a layer of non-linear resistive transient protective material and a plurality of conductive elements that form part of a conductive layer. The conductive elements include a pair of electrodes that are spaced by a gap, but which electrically interconnect when the transient protective material is conductive. The substrate includes features to linearize a transient electrical path that is formed across the gap.

Claims

1. A substrate device comprising:

one or more layers of non-linear resistive transient protective material;

a plurality of conductive elements distributed as part of a conductive layer of the substrate device so as to be in contact with at least one layer of the one or more layers of non-linear resistive transient protective material, the plurality of conductive elements including a pair of conductive elements that are spaced apart to form a gap, but which electrically connect when the transient protective material is conductive; and

wherein at least one of the conductive elements of the pair of conductive elements includes one or more structural features that vary a thickness or topology of a portion of that conductive element, the portion contacting or extending into the at least one layer of the one or more layers of non-linear resistive transient protective material.

2. The substrate device of claim 1, wherein the one or more layers of non-linear resistive transient protective material comprises voltage switchable dielectric material.

3. The substrate device of claim 1, wherein at least one of the conductive elements of the pair of conductive elements includes one or more structural features that correspond to the at least one of the conductive elements of the pair of conductive elements having a raised portion.

4. The substrate device of claim 1, wherein at least one of the conductive elements of the pair of conductive elements includes one or more structural features that correspond to the at least one of the conductive elements of the pair of conductive elements having a roughened surface on at least a portion of the at least one of the conductive elements of the pair of conductive elements.

5. The substrate of claim 4, wherein the roughened surface is a result of a mechanical or chemical etching process performed on a portion of the conductive layer that includes at least one of the conductive elements of the pair of conductive elements.

6. The substrate device of claim 1, wherein at least one of the conductive elements of the pair of conductive elements includes one or more structural features that correspond to the at least one of the conductive elements of the pair of conductive elements having an extension that extends (i) at least partially through the at least one layer of the one or more layers of non-linear resistive transient protective material, and (ii) at least partially across the gap.

7. The substrate device of claim 1, further comprising one or more layers of dielectric material, including a layer of dielectric material that is in contact with conductive elements of the conductive layer.

8. The substrate device of claim 7, further comprising a layer of resistive material that is positioned between the conductive layer and the layer of dielectric material.

9. The substrate device of claim 8, wherein the layer of resistive material is comprised of a dielectric material.

10. The substrate device of claim 1, wherein the pair of conductive elements electrically connect using a transient electrical path, and wherein at least one of the conductive elements of the pair of conductive elements include one or more structural features such that the transient electrical path is caused to become substantially more linear relative to a structural feature not having the thickness or surface topology.