Printed mesh defining pixel areas for printed inorganic LED dies

• US 9,368,549 B1
• Filed: 09/02/2015
• Issued: 06/14/2016
• Est. Priority Date: 09/02/2015
• Status: Active Grant

• Current Assignee: NthDegree Technologies Worldwide Inc.
• Original Assignee: NthDegree Technologies Worldwide Inc.
• Inventors: Oraw, Bradley S., Ogonowsky, Brian D.
• Primary Examiner(s): Tran, Minh-Loan
• Application Number:
  US14/843,818
• Time in Patent Office: 286 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H01L 2224/24137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/73267 Layer and HDI connectors
• CPC Class Codes: H01L 2224/82 by forming build-up interconnects at chip-level, e.g. for high density interconnects [HDI]
• CPC Class Codes: H01L 2224/92244 the second connecting process involving a build-up interconnect
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 27/156 two-dimensional arrays
• CPC Class Codes: H01L 2933/0058 relating to optical field-shaping elements
• CPC Class Codes: H01L 2933/0066 relating to arrangements for conducting electric current to or from the semiconductor body
• CPC Class Codes: H01L 33/00 Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof H10K50/00 takes precedence; devices consisting of a plurality of semiconductor components formed in or on a common substrate and including semiconductor components having potential barriers, specially adapted for light emission H01L27/15; semiconductor lasers H01S5/00
• CPC Class Codes: H01L 33/005 Processes
• CPC Class Codes: H01L 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil
• CPC Class Codes: H01L 33/507 the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body
• CPC Class Codes: H01L 33/52 Encapsulations
• CPC Class Codes: H01L 33/60 Reflective elements
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Abstract

Over a flexible substrate are formed column lines for a display. Over the substrate and column lines are formed a reflective hydrophobic mesh defining pixels. Over the mesh and column lines is printed an LED ink containing microscopic LED dies. The LED ink de-wets from the mesh. The ink is then cured to electrically connect the bottom electrodes of the LEDs to the column lines within the openings (cells) of the mesh. A dielectric then encapsulates the LEDs while exposing the top electrodes of the LEDs. Transparent row lines are then formed along the rows of the mesh to electrically contact the top electrodes in each row. The LEDs within any cell can be turned on by address in a pair of row and column lines. Phosphor dots may be printed to over blue-emitting LEDs to create red, green, and blue sub-pixels for a full color display.

Claims

1. A method for fabricating an addressable display comprising:

forming a plurality of first conductor lines over a substrate;

forming a mesh over the first conductor lines and the substrate, the mesh having walls defining an array of openings as pixel areas, wherein the first conductor lines are exposed through the openings;

printing a light emitting diode (LED) ink within the array of openings, the LED ink containing inorganic LED dies having bottom electrodes and top electrodes;

curing the LED ink such that the bottom electrodes electrically contact the first conductor lines within the pixel areas; and

forming a plurality of second conductor lines electrically contacting the top electrodes, such that energizing combinations of the first conductor lines and the second conductor lines turns on LEDs within a selected pixel area.

2. The method of claim 1 wherein the mesh is formed of a reflective material.

3. The method of claim 1 wherein the mesh is formed of a material that is hydrophobic with respect to the LED ink so as to repel the LED ink from adhering to top surfaces of the mesh.

4. The method of claim 1 wherein the first conductor lines are column lines and the second conductor lines are row lines.

5. The method of claim 1 wherein the first conductor lines are row lines and the second conductor lines are column lines.

6. The method of claim 1 wherein the LED dies emit blue light, the method further comprising printing wavelength-converting materials overlying some pixel areas to generate a plurality of colors for a color display.

7. The method of claim 1 further comprising depositing a dielectric material within the pixel areas to encapsulate sides of the LED dies.

8. The method of claim 7 further comprising forming holes in the dielectric material over the pixel areas to expose the top electrodes of the LEDs in the pixel areas for contact by the second conductor lines.

9. The method of claim 1 wherein all steps are performed under atmospheric conditions.

10. A display comprising:

a substrate;

a plurality of first conductor lines formed over the substrate;

a mesh formed over the first conductor lines and the substrate, the mesh having walls defining an array of openings as pixel areas, wherein the first conductor lines are exposed through the openings;

printed inorganic LED dies within the array of openings, the LED dies having bottom electrodes and top electrodes, wherein the mesh openings define the locations of the LED dies, and wherein the bottom electrodes electrically contact the first conductor lines within the pixel areas; and

a plurality of second conductor lines electrically contacting the top electrodes, such that energizing combinations of the first conductor lines and the second conductor lines turns on LEDs within a selected pixel area.

11. The display of claim 10 wherein the mesh is formed of a reflective material.

12. The display of claim 10 wherein the mesh is formed of a material that is hydrophobic with respect to the LED ink used to print the LED dies so as to repel the LED ink from adhering to top surfaces of the mesh.

13. The display of claim 10 wherein the first conductor lines are column lines and the second conductor lines are row lines.

14. The display of claim 10 wherein the first conductor lines are row lines and the second conductor lines are column lines.

15. The display of claim 10 wherein the LED dies emit blue light, the display further comprising wavelength-converting materials overlying some pixel areas to generate a plurality of colors for a color display.

16. The display of claim 10 further comprising a dielectric material within the pixel areas encapsulating sides of the LED dies.

17. The display of claim 16 further comprising holes in the dielectric material over the pixel areas to expose the top electrodes of the LEDs in the pixel areas, wherein the second conductor lines electrically contact the top electrodes through the holes.