Light emitting device comprising an organic LED array on an ultra thin substrate and process for forming same

• US 5,482,896 A
• Filed: 11/18/1993
• Issued: 01/09/1996
• Est. Priority Date: 11/18/1993
• Status: Expired due to Term

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Eastman Kodak Company
• Inventors: Tang, Ching W.
• Primary Examiner(s): Picardat, Kevin M.
• Application Number:
  US08/154,368
• Time in Patent Office: 782 Days
• Field of Search: 437/209, 437/211, 437/214, 437/215, 437/217, 437/218, 437/219, 437/220, 437/2, 437/3, 437/23, 437/974, 437/905, 437/906, 148/DIG. 99, 148/DIG. 135
• US Class Current: 438/28
• CPC Class Codes: B41J 2/45 using light-emitting diode [LED] or laser arrays
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 50/805 Electrodes
• CPC Class Codes: H10K 59/00 Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
• CPC Class Codes: H10K 59/17 Passive-matrix OLED displays
• CPC Class Codes: Y10S 148/099 LED, multicolor

Abstract

A light emitting device that comprises an organic LED array containing a plurality of light emitting pixels, the pixels each being located on a common electrically insulative transparent substrate, is characterized in that the transparent support is ultra thin, having a thickness less than the pitch of the pixels. The pixels in the LED array can be arranged in intersecting columns and rows, or they can comprise a line array. A process for forming a light emitting device on an ultra thin transparent substrate comprises the following steps: (a) releasably laminating to an ultra thin electrically insulating transparent substrate a relatively thick rigid temporary support; (b) forming the LED array on the ultra thin substrate; (c) forming on a relatively thick rigid permanent support an electrical conductor patterned in conformity with the first electrode element and the second electrode element on the ultra thin substrate; (d) forming an array of electrically conductive malleable bonding bumps on the patterned electrical conductor located on the permanent support; (e) aligning the first and second electrode elements in correct registration with the patterned electrical conductor; (f) contacting the bonding bumps on the electrical conductor with the first and second electrode elements; (g) forming a physical and electrical connection between the bonding bumps and the first and second electrode elements; and (h) delaminating the temporary support from the ultra thin transparent substrate. Additionally, a transparent and electrically insulative sealant material can be introduced into the space between the ultra thin substrate and the electrical conductor on the permanent support.

Claims

1. A process for forming a light-emitting device that comprises an organic LED array containing a plurality of light emitting pixels having a pitch;

a plurality of light transmissive first electrode elements located on a common electrically insulative transparent substrate, each first electrode element being laterally spaced and electrically insulated from an adjacent first electrode element;

an organic electroluminescent medium located on a supporting surface formed by the substrate and every first electrode element; and

a second electrode element located on said organic electroluminescent medium, said pixels each including a first electrode element and a second electrode element, which comprises the following steps;

(a) releasably laminating to an ultra thin electrically insulating transparent substrate a relatively thick rigid temporary support wherein the ultra thin electrically insulating transparent substrate has a thickness less than the pitch of said pixels;

(b) forming said organic LED array on said ultra thin substrate;

(c) forming on a relatively thick rigid permanent support an electrical conductor patterned in conformity with said first and second electrode elements located on said ultra thin substrate;

(d) forming an array of electrically conductive malleable bonding bumps on said patterned electrical conductor located on said permanent support;

(e) aligning said first and second electrode elements located on said ultra thin substrate in correct registration with said patterned conductor located on said permanent support;

(f) contacting said bonding bumps on said conductor with said first electrode and second electrode elements;

(g) forming a physical and electrical connection between said bonding bumps and said first electrode and second electrode elements; and

(h) delaminating said temporary support from said ultra thin transparent substrate.

2. A process according to claim 1 wherein said pixels are arranged in a plurality of intersecting columns and rows;

said pixels in each column contain and are joined by a common first electrode element and said pixels in each row contain and are joined by a common second electrode element;

each second electrode element being laterally spaced and electrically insulated from an adjacent second electrode element.

3. A process according to claim 1 wherein said pixels are arranged in a line array.

4. A process according to claim 1 further comprising the step of introducing a transparent and electrically insulative sealant material into the space between said ultra thin substrate and said electrical conductor on said permanent support.

5. A process according to claim 1 wherein said ultra thin substrate is glass.

6. A process according to claim 5 wherein said ultra thin substrate has a thickness of up to about 150 μ

m.

7. A process according to claim 6 wherein said ultra thin substrate has a thickness of about 25 μ

m to 50 μ

m.

8. A process according to claim 1 wherein said rigid temporary and permanent supports are glass.

9. A process according to claim 8 wherein said supports have a thickness of about 1 mm to 3 mm.

10. A process according to claim 8 wherein said supports have a curved surface.

11. A process according to claim 1 wherein said ultra thin substrate is plastic.

12. A process according to claim 1 wherein said ultra thin substrate is laminated to said temporary support by means of an adhesive.

13. A process according to claim 12 wherein said adhesive is a hot melt adhesive.

14. A process according to claim 1 wherein said patterned electrical conductor is formed from indium tin oxide or an evaporated metal.

15. A process according to claim 14 wherein said metal is Cr or Al.

16. A process according to claim 1 wherein said bonding bumps are formed from a soft metal alloy.

17. A process according to claim 16 wherein said metal alloy is an indium alloy.

18. A process according to claim 1 wherein said physical and electrical connection between said bonding bumps and said first electrode element is formed by applying heat, pressure, or a combination of both heat and pressure.

19. A process according to claim 4 wherein said sealant material is introduced in a fluid state and is subsequently caused or allowed to harden.

20. A process according to claim 1 wherein said sealant material is an epoxy resin, a hot melt adhesive, or a UV-curable adhesive.