Method and apparatus for etching-manufacture of cylindrical elements

• US 6,086,773 A
• Filed: 05/22/1998
• Issued: 07/11/2000
• Est. Priority Date: 05/22/1998
• Status: Expired due to Fees

• Current Assignee: Buckbee-Mears Medical Technologies, LLC
• Original Assignee: BMC Industries, Inc.
• Inventors: Dufresne, Michael J., Lundblad, LeRoy J.
• Primary Examiner(s): Bueker, Richard
• Assistant Examiner(s): Powell, Alva C.
• Application Number:
  US09/083,703
• Time in Patent Office: 781 Days
• Field of Search: 156/345, 216/8-10, 216/48, 216/56, 216/94
• US Class Current: 216/8
• CPC Class Codes: A61F 2/91 made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
• CPC Class Codes: A61F 2/915 with bands having a meander structure, adjacent bands being connected to each other
• CPC Class Codes: A61F 2002/91533 characterised by the phase between adjacent bands
• CPC Class Codes: A61F 2230/0013 Horseshoe-shaped, e.g. crescent-shaped, C-shaped, U-shaped
• CPC Class Codes: C23F 1/04 Chemical milling

Abstract

A process is described for the manufacture of flexible tubular elements, particularly stents for the medical field, the process comprising the steps of:

a) providing a hollow metal tube (or metal coated tube) with an open pattern of a chemical-etch-resistant coating layer;

b) supporting the hollow metal tube with a coating thereon onto a chemical etch resistant support element;

c) contacting the open pattern with a solution capable of etching the metal of the hollow metal tube so that said metal is etched away from physically exposed surfaces of the metal tube and openings in the metal tube corresponding to the open pattern of the coating layer are created in the metal tube element without etching the chemical etch resistant support element; and

d) removing the metal tube from the chemical etch resistant support element.

Claims

1. A process for the manufacture of flexible stents comprising the steps of:

a) coating a hollow metal tube with a photosensitive resist coating layer,

b) supporting tube metal tube on a rotatable support;

c) providing radiation comprising wavelengths of radiation to which the photosensitive resist coating layer is sensitive;

d) passing said radiation through at least a first opening ion an aperture mask which is riot in contact with the coated hollow tube to expose an area on the surface of the photoresist coating on the metal tube and alter its relative solubility;

e) rotating said rotatable support to rotate the surface of the photoresist layer;

f) causing additional radiation comprising wavelengths of radiation to which the photosensitive resist coating layer is sensitive to pass through at least a second opening in said aperture mask, the shape of the second opening being different than the shape of the first opening in said aperture mask, wherein radiation passing through said second opening after radiation has passed through the first opening overlaps radiation that has passed through said first opening so that radiation passing through both said first opening and the second opening overlaps on the surface of the photosensitive resist coating layer and forms a combination of different individual shape patterns on said photosensitive resist layer from first and second openings in said aperture mask;

g) timing the position of the openings in the aperture mask and the passage of said radiation through said first and second openings so that a desired pattern of exposure of the surface of said photosensitive resist coating layer is formed, said desired pattern comprising combinations of areas exposed through at least said first opening and said second opening;

h) washing said photoresist coating layer having the desired pattern of exposure thereon with a developer which will develop either the exposed desired pattern of photoresist costing layer more readily than unexposed areas of the photoresist coating layer while leaving other areas of the photoresist coating layer on a surface of the hollow metal tube in a positive image of said desired pattern or will develop the unexposed areas of the photoresist coating layer more readily than the desired pattern of irradiated photoresist coating layer to assist in removing areas of the photoresist coating layer while leaving other areas of the photoresist coating layer on a surface of the hollow metal tube in a negative image of said desired pattern or in said desired pattern, thereby forming a cylindrical element with a physically exposed pattern of metal underneath the photoresist coating layer;

I) transferring said metal tube with a physically exposed pattern of metal onto a chemical etch resistant support element;

j) contacting the physically exposed pattern of metal with a solution capable of etching the metal of the metal of the metal tube so that said metal is etched away from physically exposed surfaces of the metal tube and openings in the metal tube corresponding to the pattern of physically exposed metal are created in the metal tube element; and

k) removing said metal tube from said chemical etch resistant support element.

2. The process of claim 1 wherein said contacting the physically exposed surface of the metal tubular element with a solution capable of etching the metal of the metal tubular element comprises spraying said solution onto said tubular element.

3. The process of claim 2 wherein said spraying is effected by having the tubular element both rotate and revolve, and by having spray which repeatedly alters its angle of spray towards said metal tube.

4. The process of claim 2 wherein said washing said photoresist coating layer having the desired pattern of exposure thereon with a developer which will develop the exposed pattern of photoresist coating layer is effected by spraying said developer onto a surface of said radiation exposed photoresist layer while said tubular metal element is rotating and with said spray being emitted from nozzles which vary their relative angle with respect to the metal tube repeatedly while spraying.

5. The process of claim 2 wherein more than one metal tube is supported within a movable support, and said movable support is passed through an area where chemical etch solution is applied by spraying.

6. The process of claim 5 wherein said spraying is performed while said metal tubular element is rotating and said support is revolving.

7. The process of claim 2 wherein said spraying of said etchant solution is performed while the supported cylindrical element both rotates on a longitudinal axis and is revolved with at least some movement in a direction perpendicular to said longitudinal axis, while said solution capable of etching the metal of the metal tubular element is sprayed onto said at a temperature between 40 and 150°

C.

8. The process of claim 2 wherein said etchant solution comprises a ferric chloride solution with a Baume between 48 and 55 degrees at a temperature between 110 and 140°

F.

9. The process of claim 8 wherein after development of the photoresist layer, a slurry of particles having average particle diameters of less than 5 microns is used to clean the developed image.

10. The process of claim 2 wherein after development of the photoresist layer, a slurry of particles having average particle diameters of less than 5 microns is used to clean the developed image.

11. The process of claim 1 wherein each of the individual shape patterns which are used to form a developable image in said photoresist coating layer which is developed into said pattern of physically exposed metal are radiation exposed by said focussed beam of radiation through one individual shape pattern at a time.

12. The process of claim 11 wherein radiation exposure by said focussed beam of radiation occurs while said metal tubular element is rotating continuously.

13. The process of claim 1 wherein said solution capable of etching the metal of the metal of the metal tube is heated above 40°

C.

14. The process of claim 13 wherein said solution comprises ferric chloride solution with a Baume'"'"' above 47.5°

.

15. The process of claim 14 wherein after development of the photoresist layer, a slurry of particles having average particle diameters of less than 5 microns is used to clean the developed image.

16. The process of claim 13 wherein said etchant solution comprises a ferric chloride solution with a Baume between 48 and 53 degrees at a temperature between 110 and 140°

F.

17. The process of claim 1 wherein said etchant solution comprises a ferric chloride solution with a Baume between 48 and 55 degrees at a temperature between 110 and 140°

C.

18. The process of claim 1 wherein after development of the photoresist layer, a slurry of particles having average particle diameters of less than 5 microns is used to clean the developed image.