Three dimensional microstructures and fabrication process

Patent metadata

Field	Value
Publication number	US-9796586-B2
Application number	US-201514985859-A
Country	US
Kind code	B2
Filing date	Dec 31, 2015
Priority date	Dec 31, 2014
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

A method for fabricating three-dimensional microstructures is presented. The method includes: disposing a substantially planar reflow material between two molds; heating the reflow material while the reflow material is disposed between the two molds; and reflowing the reflow material towards the bottom surface of one of the molds by creating a pressure gradient across the reflow material. At least one of molds includes geometrics features that help to shape the reflow material and thereby form a complex three-dimensional microstructure.

First claim

What is claimed is:

1. A method for fabricating three-dimensional microstructures, comprising:
disposing a substantially planar reflow material on a first mold having a recess formed therein, wherein the recess in the first mold defines a bottom surface and at least one side surface, and the at least one side surface includes a protrusion protruding into the recess, wherein the first mold further includes a pillar projecting upward from the bottom surface of the first mold, whereby the pillar shapes the reflow material;
heating the reflow material while the reflow material is disposed on the first mold; and
reflowing the reflow material towards the bottom surface of the first mold by creating a pressure gradient across the reflow material, whereby the protrusion in the at least one side surface helps to shape the reflow material and thereby form a three-dimensional microstructure.

2. The method of claim 1 further comprises controlling the pressure gradient across the reflow material independently from heating the reflow material.

3. The method claim 1 further comprises heating the reflow material using a heat source and creating a pressure gradient across the reflow material using a vacuum that differs from the heat source.

4. The method of claim 1 further comprises heating the reflow material above a glass transition temperature for a non-crystalline material or above melting temperature of the reflow material.

5. The method of claim 1 further comprises forming through holes in the bottom surface of the first mold and fluidly coupling the through holes to a pressure source.

6. The method of claim 1 further comprises detaching the reflown substantially planar reflow material from the first mold after the step of creating a pressure gradient across the reflow material.

7. The method of claim 1 wherein the reflow material is selected from a group consisting of fused silica, sapphire, ruby, silicon, glass and metal.

8. The method of claim 1 further comprises a second mold, wherein the reflow material is disposed between the first mold and the second mold.

9. A method for fabricating three-dimensional microstructures, comprising:
disposing a substantially planar reflow material on a first mold having a recess formed therein, wherein the recess in the first mold defines a bottom surface and at least one side surface, and the at least one side surface includes a protrusion protruding into the recess;
partitioning the recess in the first mold into two or more cavities and applying different pressures in one of the two or more cavities;
heating the reflow material while the reflow material is disposed on the first mold; and
reflowing the reflow material towards the bottom surface of the first mold by creating a pressure gradient across the reflow material, whereby the protrusion in the at least one side surface helps to shape the reflow material and thereby form a three-dimensional microstructure.

10. A method for fabricating three-dimensional microstructures, comprising:
disposing a substantially planar reflow material on a first mold having a recess formed therein, wherein the recess in the first mold defines a bottom surface and at least one side surface, and the at least one side surface includes a protrusion protruding into the recess;
heating the reflow material while the reflow material is disposed on the first mold; and
reflowing the reflow material towards the bottom surface of the first mold by creating a pressure gradient across the reflow material, whereby the protrusion in the at least one side surface helps to shape the reflow material and thereby form a three-dimensional microstructure,
wherein the first mold further includes one or more pockets formed in the at least one side surface of the first mold and fluidly coupling the one or more pockets via through holes to a pressure source, whereby the reflow material reflows laterally into the one or more pockets.

11. A method for fabricating three-dimensional microstructures, comprising:
micromachining a first mold with a recess formed therein;
micromachining a second mold with a recess formed therein, the recess of the second mold defining a bottom surface and at least one side surface, and the at least one side surface includes a protrusion protruding into the recess, wherein the second mold further includes a pillar projecting upward from the bottom surface of the second mold, whereby the pillar shapes the reflow material;
disposing a substantially planar reflow material between the first mold and the second mold, such that the recess in the first mold faces the recess in the second mold and thereby forms a cavity;
heating the reflow material while the reflow material is disposed between the first mold and the second mold; and
creating a pressure gradient across the reflow material to reflow the reflow material towards the bottom surface of the second mold, wherein the pressure gradient is controlled independently from the heating of the reflow material.

12. The method claim 11 further comprises heating the reflow material using a heat source and creating a pressure gradient across the reflow material using a pressure source that differs from the heat source.

13. The method of claim 11 further comprises heating the reflow material above a glass transition temperature for a non-crystalline material or above melting temperature of the reflow material.

14. The method of claim 11 further comprises forming through holes in the bottom surface of the second mold and fluidly coupling the through holes to a pressure source.

15. The method of claim 11 further comprises detaching the reflown substantially planar reflow material from the first and second molds after the step of creating a pressure gradient across the reflow material.

16. The method of claim 11 further comprises partitioning the recess in the second mold into two or more cavities and applying different pressures in one of the two or more cavities.

17. A method for fabricating three-dimensional microstructures, comprising:
micromachining a first mold with a recess formed therein;
micromachining a second mold with a recess formed therein, the recess of the second mold defining a bottom surface and at least one side surface;
disposing a substantially planar reflow material between the first mold and the second mold, such that the recess in the first mold faces the recess in the second mold and thereby forms a cavity;
heating the reflow material while the reflow material is disposed between the first mold and the second mold; and
creating a pressure gradient across the reflow material to reflow the reflow material towards the bottom surface of the second mold, wherein the pressure gradient is controlled independently from the heating of the reflow material,
wherein the second mold further includes one or more pockets formed in the at least one side surface of the second mold and fluidly coupling the one or more pockets via through holes to a pressure source, whereby the reflow material reflows laterally into the one or more pockets.

Assignees

• Univ Michigan Regents

Inventors

• Najafi Khalil
• Nagourney Tal
• Cho Jae Yoong

Classifications

• B81C2201/034

  Moulding · CPC title

• C03B23/0357

  by suction without blowing, e.g. with vacuum or by venturi effect · CPC title

• C03B23/0302

  between opposing full-face shaping moulds · CPC title

• B81C99/0085 Primary

  using moulds and master templates, e.g. for hot-embossing · CPC title

• C03B23/0355

  by blowing without suction directly on the glass sheet · CPC title