Flexible circuit with micro-sized probe tips and a method of making the same

• US 20060071677A1
• Filed: 10/01/2004
• Published: 04/06/2006
• Est. Priority Date: 10/01/2004
• Status: Active Grant

• Current Assignee: Aptiv Technologies Limited (Aptiv PLC)
• Original Assignee: Delphi Technologies, Inc. (Aptiv PLC)
• Inventors: Feigenbaum, Haim, Hoang, Long T., Betz, Robert K., Le, Bao Q.
• Granted Patent: US 7,504,839 B2
• Time in Patent Office: Days
• US Class Current: 324/754.70
• CPC Class Codes: G01R 1/06711 Probe needles; Cantilever beams; "Bump" contacts; Replaceable probe pins
• CPC Class Codes: G01R 1/07342 the body of the probe being at an angle other than perpendicular to test object, e.g. probe card
• CPC Class Codes: G01R 3/00 Apparatus or processes specially adapted for the manufacture or maintenance of measuring instruments , e.g. of probe tips
• CPC Class Codes: H05K 1/0393 Flexible materials H05K1/038 takes precedence; specific organic compositions are classified in H05K1/0313 and subgroups
• CPC Class Codes: H05K 1/09 Use of materials for the conductive, e.g. metallic pattern
• CPC Class Codes: H05K 2201/0391 Using different types of conductors
• CPC Class Codes: H05K 3/205 using a pattern electroplated or electroformed on a metallic carrier
• CPC Class Codes: H05K 3/4092 Integral conductive tabs, i.e. conductive parts partly detached from the substrate

Abstract

A flexible circuit includes a plurality of electrical traces and a plurality of probe tips directly formed thereto. The electrical traces are made of a first electrically conductive material and the probe tips are made of a second electrically conductive material that is harder than the first electrically conductive material. The first material is copper or a copper alloy and the second matieral is nickel or a nickel alloy, where the second material may be plated with gold. Portions of the probe tips are exposed to facilitate electrical contact with contact pads of another electrical circuit. The flexible circuit may also include a ground layer to facilitate electrical correction with another electrical circuit at relatively high frequencies.

Claims

1. A flexible circuit comprising:

an insulation layer having an electrical trace composed of a first electrically conductive material; and

a probe tip that is formed directly to a portion of the electrical trace the probe tip being composed of a second electrically conductive material that is harder than the first electrically conductive material and having an exposed portion projecting outwardly of the insulation layer.

2. The flexible circuit of claim 1 wherein the probe tip is formed directly to the portion of the electrical trace by electroplating.

3. The flexible circuit of claim 1 wherein the first electrically conductive material has a Vickers hardness in the range of 100 to 120 VPN;

and

wherein the second electrically conductive material has a Vickers hardness in the range of 180 to 400 VPN.

4. The flexible circuit of claim 1 wherein the first electrically conductive material is copper or a copper alloy and wherein the second electrically conductive material is nickel or a nickel alloy.

5. The flexible circuit of claim 1 wherein the probe tip is plated with gold.

6. The flexible circuit of claim 1 further comprising a ground layer composed of a third electrically conductive material.

7. The flexible circuit of claim 6 wherein the third electrically conductive material is copper or a copper alloy.

8. The flexible circuit of claim 1 wherein the insulation layer is a laminate comprising a substrate layer and a cover layer with the electrical trace disposed between the substrate layer and the cover layer.

9. The flexible circuit of claim 8 further comprising a stiffener laminated over at least a portion of the cover layer, wherein the stiffener is made of an insulative material.

10. A method of making a flexible circuit comprising:

forming an electrical trace on a mandrel, wherein the electrical trace is composed of a first electrically conductive material;

forming a probe tip and attaching the probe tip directly to a portion of the electrical trace, wherein the probe tip is composed of a second electrically conductive material that is harder than the first electrically conductive material,

attaching the electrical trace and the probe tip to an insulation layer;

removing the mandrel; and

exposing a portion of the probe tip so that it extends outwardly of the insulation layer.

11. The method as defined in claim 10 wherein the probe tip is formed and attached to a portion of the electric trace by electroplating.

12. The method as defined in claim 10 wherein the probe tip is plated with gold.

13. The method of claim 10 wherein the first electrically conductive material has a Vickers hardness in the range of 100 to 120 VPN and wherein the second electrically conductive material has a Vickers hardness in the range of 180 to 400 VPN.

14. The method of claim 10 wherein the first electrically conductive material is copper or a copper alloy and wherein the second electrically conductive material is nickel.

15. The method of claim 10 further comprising forming a ground layer composed of a third electrically conductive material.

16. The method of claim 15 wherein the third electrically conductive material is copper or a copper alloy.

17. The method of claim 10 wherein the insulation layer comprises a laminating a cover layer.

18. The method of claim 17 further comprising laminating a stiffener over at least a portion of the cover layer wherein the stiffener is made of an insulative material.

19. The method of claim 18 wherein the insulation layer further comprises laminating a substrate layer below the electrical trace and at least a portion of the probe tip.

20. A flexible circuit comprising:

a flexible insulator;

a plurality of electrical traces each composed of a copper material;

a plurality of probe tips each composed of a nickel material formed directly to respective portions of the electrical traces;

the plurality of probe tips having exposed portions projecting outwardly of the flexible insulator;

the flexible insulator having a cover layer and a substrate layer with the plurality of electrical traces located therebetween; and

a stiffener layer composed of an insulative material laminated over at least a portion of the cover.

21. The flexible circuit of claim 20 wherein the plurality of probe tips are formed and attached directly to the respective portions of the plurality of electrical traces by electroplating.

22. The flexible circuit of claim 20 further including a ground layer located between the cover layer and the plurality of electrical traces and an intermediate insulation layer between the ground layer and the plurality of electrical traces.