Micro-selective sintering laser systems and methods thereof

Patent metadata

Field	Value
Publication number	US-10722947-B2
Application number	US-201715475794-A
Country	US
Kind code	B2
Filing date	Mar 31, 2017
Priority date	Apr 1, 2016
Publication date	Jul 28, 2020
Grant date	Jul 28, 2020

Abstract

A microscale selective laser sintering (μ-SLS) that improves the minimum feature-size resolution of metal additively manufactured parts by up to two orders of magnitude, while still maintaining the throughput of traditional additive manufacturing processes. The microscale selective laser sintering includes, in some embodiments, ultra-fast lasers, a micro-mirror based optical system, nanoscale powders, and a precision spreader mechanism. The micro-SLS system is capable of achieving build rates of at least 1 cm3/hr while achieving a feature-size resolution of approximately 1 μm. In some embodiments, the exemplified systems and methods facilitate a direct write, microscale selective laser sintering μ-SLS system that is configured to write 3D metal structures having features sizes down to approximately 1 μm scale on rigid or flexible substrates. The exemplified systems and methods may operate on a variety of material including, for example, polymers, dielectrics, semiconductors, and metals.

First claim

What is claimed is:

1. A system for additively producing a three-dimensional workpiece, the system comprising:
an electromagnetic radiation source configured to coherently and intermittently emit an electromagnetic radiation beam;
a lens assembly having a plurality of micro-mirrors, collectively, forming a matrixed mirror array, each micro-mirror being configured to selectively direct the emitted electromagnetic radiation beam to a focus point on a sintering plane comprising a layer of particles to form one or a plurality of sintered layers, wherein each sintered layer is successively produced, in a layer-by-layer manner, to form the three-dimensional workpiece;
a multi-slot die coating assembly comprising two or more slot die coating head, including a first slot die coating head and a second slot die coating head, the first slot die coating head being configured to dispense a solvent having nanoparticles suspended therein onto a fabrication surface on a flexible substrate, and on other sintered layers thereon, such that the nanoparticles settle, upon drying of the solvent, to form a uniform thickness thereof; and
a spray washing station comprising:
one or more nozzles through which pressurized solvent is dispensed so as to remove un-sintered ink from the three-dimensional workpiece; and
a nanoparticle recycling subsystem configured to provide vacuum suction for nanoparticle ink recovery.

2. The system of claim 1 , wherein the plurality of micro-mirrors direct the plurality of emitted electromagnetic radiation beams onto an area spanning a maximum cross-sectional profile of the three-dimensional workpiece.

3. The system of claim 1 , comprising:
a build stage; and
a positioning system configured to movably position the build stage i) to a first position proximal to the electromagnetic radiation beam generated by an optical sintering system comprising the electromagnetic radiation source and the lens assembly and ii) to a second position proximal to the multi-slot die coating assembly.

4. The system of claim 3 , wherein the build stage comprises a heating element.

5. The system of claim 4 , wherein the positioning system comprises:
a nanopositioner coupled to the build stage and configured to moveably position the build stage within ±100 nm of the first position.

6. The system of claim 5 , wherein the nanopositioner comprises an X-axis flexure nanopositioner and a Y-axis flexure nanopositioner, each flexure nanopositioner being coupled to a voice coil that, when energized, moves to elastically deform a flexure body of the flexure nanopositioner in a respective direction.

7. The system of claim 1 , wherein, the electromagnetic radiation source is configured to emit the electromagnetic radiation beam at an energy level E n , wherein

E
n

=

ρ
*
π
*

D
2

4

*
h
*

[

C
p

*

(

T
i

-

T
f

)

]

n
*

(

1
-
R

)

α

wherein ρ is a powder density, CP is a specific heat of the nanoparticle, T i is an initial temperature of the powder bed, T f is a sintering temperature, R is a reflectivity of the powders, D is a spot size, h is a thickness of the layer of nanoparticles, and α is an effective power retention factor of the optical elements.

8. The system of claim 1 , comprising:
a second matrixed mirror array, the second matrixed mirror array comprising a second plurality of micro-mirrors, each configured to selectively direct the emitted electromagnetic radiation beam to the focus point on the sintering plane comprising the layer of particles.

9. The system of claim 1 , wherein the lens assembly comprises a focusing objective, the focusing objective receiving the selectively directed electromagnetic radiation beam from the matrixed mirror array and focusing the plurality of selectively directed electromagnetic radiation beams to a plurality of respective focus points on the sintering plane.

10. The system of claim 9 , wherein the focusing objective is configured to focus each of the plurality of selectively directed electromagnetic radiation beams to the respective focus points with a spot size of about 1 μm.

11. The system of claim 1 , wherein the lens assembly comprises an ultra-wide-angle optics, the ultra-wide-angle optics receiving the electromagnetic radiation beam from the electromagnetic radiation source or an intermediary optic therewith, the ultra-wide-angle optics being configured to expand the electromagnetic radiation beam across each, or a substantial portion, of the plurality of micro-mirrors.

12. The system of claim 1 , comprising:
a low-pressure atmospheric chamber that encases the system; and
a pump coupled to the low-pressure atmospheric chamber.

13. The system of claim 12 , comprising:
one or more metrology devices coupled to the chamber, the metrology device being selected from the group consisting of a high-speed infrared camera and a near-field scanning optical microscope.

14. The system of claim 1 , comprising:
a controller, the controller having a processor and a memory, the memory having instructions stored thereon, wherein, when executed by the processor, cause the processor to:
receive a computer-aid-design (CAD) file, the CAD file having geometric description of a tangible object; and
direct generation of the three-dimensional workpiece based on the geometric description of the CAD file.

15. The system of claim 3 , comprising:
a laser interferometry system, the laser interferometry system being configured to produce a control signal to substantially align the build stage to the sintering plane.

16. A system of claim 1 , comprising:
a porous vacuum chuck configured to rigidly fixture the flexible substrate onto which the plurality of sintered layers are successively producible, in a layer-by-layer manner, to form the three-dimensional workpiece.

17. The system of claim 1 , wherein the multi-slot die coating assembly includes:
an instrument configured to interrogate a fabricated layer and measure one or more thicknesses and one or more unifo

Assignees

• Univ Texas

Inventors

• Cullinan Michael A
• Roy Nilabh Kumar
• Yuksel Anil
• Foong Chee Seng

Classifications

• B22F12/22

  Driving means · CPC title

• B22F12/90

  Means for process control, e.g. cameras or sensors · CPC title

• B22F12/53

  Nozzles · CPC title

• B22F12/49

  Scanners · CPC title

• B22F12/45

  Two or more · CPC title