GEOMETRIC AND ELECTRIC FIELD CONSIDERATIONS FOR INCLUDING TRANSIENT PROTECTIVE MATERIAL IN SUBSTRATE DEVICES

• US 20100109834A1
• Filed: 10/28/2009
• Published: 05/06/2010
• 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
• Granted Patent: US 8,362,871 B2
• Time in Patent Office: Days
• 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 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;

wherein the pair of conductive elements that form the gap include one or more structural features that vary a thickness or surface topology of one or both of the pair of conductive elements.

2. The substrate device of claim 1, wherein the transient protective material comprises voltage switchable dielectric material.

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

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

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 the pair of conductive elements.

6. The substrate device of claim 1, wherein the pair of conductive elements include one or more structural features that correspond to at least one of the conductive elements in the pair having an extension that extends (i) at least partially through the at least one layer of 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. 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 transient protective material, the plurality of conductive elements including a pair of conductive elements that are spaced apart by a gap, but which electrically connect when the transient protective material is conductive; and

one or more additional conductive elements that are positioned to vertically align over and/or extend through the gap without being in contact with the pair of conductive elements.

11. The substrate device of claim 10, wherein the one or more additional conductive elements are separated from the conductive layer by at least a portion of the layer of transient protective material, so as to align over or under the gap.

12. The substrate device of claim 10, wherein the one or more additional conductive elements include a via that extends through the gap.

13. The substrate device of claim 10, wherein at least one of the via or the pair of conductive elements form part of the ground for the substrate device in absence of a corresponding portion of the layer transient protective material being conductive.

14. The substrate device of claim 10, 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.

15. The substrate device of claim 14, further comprising a layer of resistive material that is positioned between the conductive layer and the layer of dielectric material.

16. The substrate device of claim 15, wherein the layer of resistive material is comprised of a dielectric material.

17. The substrate device of claim 10, wherein the layer of transient protective material comprises voltage switchable dielectric material.

18. 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 transient protective material, the plurality of conductive elements including a pair of conductive elements that are spaced apart by a gap, but which electrically connect when the transient protective material is conductive;

one or more layers of dielectric, non-conductive material that are in contact with at least one of the transient protective layer or conductive elements of the conductive layer, the one or more layers of dielectric, non-conductive material including a layer of material that has high breakdown strength.

19. The substrate device of claim 18, wherein the conductive layer is at least partially embedded within the layer of transient protective material, so that the transient protective material occupies at least a portion of a volume of the gap;

and

wherein at least one of the layers of dielectric, non-conductive material is in contact with at least one of the conductive layer or the layer of transient protective material.

20. A substrate device comprising:

a layer 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 the layer transient protective material, the plurality of conductive elements including a pair of conductive elements that are spaced apart by a gap, but which electrically connect when the transient protective material is conductive;

wherein the conductive layer is embedded within the layer of transient protective material, so that the transient protective material occupies a volume of the gap.

21. The substrate device of claim 20, wherein the layer of transient protective material is comprised of a first layer that is coated or bonded on one side of the conductive layer, and a second layer that is coated on another side of the conductive layer.

22. The substrate device of claim 20, 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.

23. The substrate device of claim 20, further comprising a layer of resistive material that is positioned between the conductive layer and the layer of dielectric material.

24. The substrate device of claim 21, wherein the layer of resistive material is also a dielectric with high breakdown strength.

25. The substrate device of claim 20, wherein the conductive layer is a grounding plane.

26. The substrate device of claim 20, wherein the transient protective material corresponds to voltage switchable dielectric material.

27. A substrate device comprising:

one or more layers of transient protective material, the transient protective material being (i) non-conductive in absence of a voltage that exceeds a characteristic trigger voltage of the transient protective material, and (ii) conductive when a voltage that exceeds the characteristic trigger voltage is applied to the 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 transient protective material, the plurality of conductive elements including a pair of conductive elements that are spaced apart by a gap, but which electrically connect when the transient protective material is conductive; and

wherein individual conductive elements in the plurality of conductive elements include a footprint that defines a boundary that is in contact with material from the layer of transient protective material, and wherein at least one of the conductive elements is in contact with either a void or a filler, other than transient protective material, wherein the void or filler is formed into the later of transient protective material so that the void or filler is within that conductive elements'"'"' footprint.

28. The substrate device of claim 27, wherein at least one of the conductive elements is in contact with the filler, and wherein the filler increases or decreases a capacitance of a region that is occupied by the at least one of the conductive elements.

29. The substrate device of claim 27, wherein at least one of the conductive elements is in contact with the filler, and wherein the filler increases or decreases a dielectric constant of a region that is occupied by the at least one of the conductive elements.

30. The substrate device of claim 27, wherein at least one of the conductive elements is in contact with the filler, and wherein the filler includes material that is provided from a lamination process.

31. The substrate device of claim 27, wherein the transient protective material is comprised of voltage switchable dielectric material.

32. The substrate device of claim 27, 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.