Method of soldering Ti containing alloys

• US 20020087099A1
• Filed: 12/10/2001
• Published: 07/04/2002
• Est. Priority Date: 12/22/1992
• Status: Active Grant

• Current Assignee: Abbott Cardiovascular Systems Incorporated (Abbott Laboratories)
• Original Assignee: Clifford Teoh, Janet Walsh Burpee, Leonard Nanis, Randy S. Chan, Robert M Abrams
• Inventors: Teoh, Clifford, Nanis, Leonard, Burpee, Janet Walsh, Abrams, Robert M., Chan, Randy S.
• Granted Patent: US 6,602,228 B2
• Time in Patent Office: Days
• US Class Current: 600/585
• CPC Class Codes: A61L 2400/16 Materials with shape-memory or superelastic properties
• CPC Class Codes: A61L 31/022 Metals or alloys
• CPC Class Codes: A61L 31/14 Materials characterised by their function or physical properties , e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
• CPC Class Codes: A61M 2025/09083 having a coil around a core
• CPC Class Codes: A61M 2025/09141 made of shape memory alloys which take a particular shape at a certain temperature
• CPC Class Codes: A61M 2025/09175 having specific characteristics at the distal tip
• CPC Class Codes: A61M 2205/0266 Shape memory materials
• CPC Class Codes: A61M 25/09 Guide wires
• CPC Class Codes: C22C 14/00 Alloys based on titanium
• CPC Class Codes: C22C 30/00 Alloys containing less than 50% by weight of each constituent
• CPC Class Codes: C22F 1/006 Resulting in heat recoverable alloys with a memory effect

Abstract

An improved guidewire for advancing a catheter within a body lumen which has a high strength proximal portion, a distal portion formed of superelastic alloy and a connector formed of superelastic alloy to provide torque transmitting coupling between the distal end of the proximal portion and the proximal end of the distal portion. The superelastic alloy elements are preferably cold worked and then heat treated at a temperature well above the austenite-to-martensite transformation temperature, while being subjected to longitudinal stresses equal to about 5 to about 50% of the room temperature yield stress to impart to the metal a straight “memory.” The guiding member using such improved material exhibits a stress induced austenite-to-martensite phase transformation at an exceptionally high constant yield strength of at least 70 ksi for solid members and at least 50 ksi for tubular members with a broad Recoverable strain of at least about 4% during the phase transformation.

Claims

1. An intravascular guidewire having proximal and distal ends, comprising:

a) an elongated high strength proximal portion having proximal and distal ends;

b) a distal portion having proximal and distal ends formed of a superelastic alloy in an austenite phase at body temperature, which transforms to a martensite phase when subjected to stress; and

c) means for connecting the distal end of the proximal portion and the proximal end of the distal portion, which is formed at least in part of a superelastic alloy in an austenite phase which transforms to a martensite phase when subjected to stress.

2. The guidewire of claim 1 wherein the means for connecting the distal end of the proximal portion to the proximal end of the distal portion has a tubular construction with an inner lumen extended therein, with a proximal end receiving the distal end of the proximal portion and a distal end receiving the proximal end of the distal portion.

3. The guidewire of claim 1 wherein a flexible coil is disposed about the distal portion and extends to a rounded plug in the distal end of the guidewire.

4. The guidewire of claim 1 wherein the distal portion terminates short of the distal end of the guidewire and a non-superelastic shaping ribbon extends from the distal section to the rounded plug.

5. The guidewire of claim 1 wherein the superelastic distal portion has a straight memory.

6. The guidewire of claim 1 wherein the strain of the distal portion during the transformation from the austenite phase to the martensite phase is within the range of about 2% to about 8%.

7. The guidewire of claim 6 wherein the austenite-to-martensite transformation occurs at a relatively constant yield stress above about 50 ksi.

8. The guidewire of claim 6 wherein the austenite-to-martensite transformation occurs at a relatively constant yield stress above about 70 ksi.

9. The guidewire of claim 6 wherein the austenite-to-martensite transformation occurs at a relatively constant yield stress above about 90 ksi.

10. The guidewire of claim 4 wherein the distal portion is formed of a superelastic alloy consisting essentially of about 40 to 49% titanium and the balance nickel and up to 10% of other alloying elements.

11. The guidewire of claim 10 wherein the other alloying elements are selected from the group consisting of iron, cobalt, vanadium and copper.

12. The guidewire of claim 11 wherein the alloy contains vanadium or copper in amounts up to about 10% and the other alloying elements up to about 3%.

13. The guidewire of claim 1 wherein the distal portion has a section which tapers in the distal direction.

14. The guidewire of claim 1 wherein a lubricous polymer coating covers at least part of the proximal portion.

15. The guidewire of claim 1 wherein the superelastic distal portion exhibits a strain of at least 5% during the stress induced transformation from the austenite phase to the martensite phase.

16. The guidewire of claim 2 wherein the connector means having a tubular construction has an outer diameter of about 0.006 to about 0.05 inch and a wall thickness of about 0.001 to about 0.004 inch.

18. The guidewire of claim 17 wherein a flexible coil is disposed about the distal portion and extends to a rounded plug in the distal end of the guidewire.

19. The guidewire of claim 17 wherein the superelastic distal portion has a straight memory.

20. The guidewire of claim 17 wherein the strain of the distal portion during the transformation from the austenite phase to the martensite phase is within the range of about 2% to about 8%.

21. The guidewire of claim 20 wherein the austenite-to-martensite transformation occurs at a relatively constant yield stress above about 50 ksi.

22. The guidewire of claim 20 wherein the austenite-to-martensite transformation occurs at a relatively constant yield stress above about 70 ksi.

23. The guidewire of claim 17 wherein the connector means having a tubular construction has an outer diameter of about 0.006 to about 0.05 inch and a wall thickness of about 0.001 to about 0.004 inch.

25. The method of claim 6 wherein a solder is employed comprising a gold-tin alloy.

26. The method of claim 6 wherein the surface oxide is removed by treating the surface of the core member with a molten alkali metal hydroxide.

27. The method of claim 8 wherein the surface of the core member is coated with a solder after removing surface oxide therefrom.

28. The method of claim 9 wherein a bath of molten solder is maintained in a container with a layer of molten alkali metal hydroxide on an upper surface of the molten solder and the core member is thrust through the molten alkali metal hydroxide to remove surface oxide therefrom and then into the molten solder to coat the core member with the solder and then solidifying the molten solder on the surface of the core member.

17. An intravascular guidewire having proximal and distal ends, comprising:

a) an elongated high strength proximal portion having proximal and distal ends;

b) a distal portion having proximal and distal ends formed of a superelastic alloy in an austenite phase at body temperature, which transforms to a martensite phase when subjected to stress; and

c) a flexible tubular means for interconnecting the distal end of the proximal portion and the proximal end of the distal portion, has a tubular construction with an inner lumen extending therein, with a proximal end receiving the distal end of the proximal portion and a distal end receiving the proximal end of the distal portion.

24. A method for making an intravascular guidewire comprising:

a) providing a core member formed of an alloy containing significant amounts of titanium;

b) treating at least a portion of the core member to remove surface oxide material which can interfere with the soldering thereof;

c) coating the thus treated portion of the core member to prevent surface reoxidation; and

d) soldering a helical coil disposed about the thus treated portion of the core member to the treated portion of the core member.