Roll-to-roll fabricated light sheet and encapsulated semiconductor circuit devices

• US 7,427,782 B2
• Filed: 01/04/2005
• Issued: 09/23/2008
• Est. Priority Date: 03/29/2004
• Status: Expired due to Fees

• Current Assignee: Articulated Technologies, LLC
• Original Assignee: Articulated Technologies, LLC
• Inventors: Nelson, Gregory Victor, Daniels, John James
• Primary Examiner(s): Luu; Chuong Anh
• Application Number:
  US11/029,137
• Publication Number:
  US 20050212007A1
• Time in Patent Office: 1,358 Days
• Field of Search: 257/98, 257/99, 257/100, 257/80, 257/88, 257/79, 257/103, 257/443, 438/46, 438/455, 438/604
• US Class Current: 257/80
• CPC Class Codes: B32B 17/10036 comprising two outer glass sheets
• CPC Class Codes: B32B 17/10174 Coatings of a metallic or dielectric material on a constituent layer of glass or polymer
• CPC Class Codes: B32B 17/10321 Laminated safety glass or glazing containing liquid layers
• CPC Class Codes: F21K 9/00 Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
• CPC Class Codes: F21V 5/04 of lens shape
• CPC Class Codes: H01L 21/67132 Apparatus for placing on an insulating substrate, e.g. tape
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/32257 the layer connector connecting to a bonding area disposed in a recess of the surface of the item
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 27/14625 Optical elements or arrangements associated with the device
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00011 Not relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01015 Phosphorus [P]
• CPC Class Codes: H01L 2924/01033 Arsenic [As]
• CPC Class Codes: H01L 2924/01047 Silver [Ag]
• CPC Class Codes: H01L 2924/12044 OLED
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/3025 : Electromagnetic shielding
• 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

A method of making a light active sheet. A bottom substrate having an electrically conductive surface is provided. A hotmelt adhesive sheet is provided. Light active semiconductor elements, such as LED die, are embedded in the hotmelt adhesive sheet. The LED die each have a top electrode and a bottom electrode. A top transparent substrate is provided having a transparent conductive layer. The hotmelt adhesive sheet with the embedded LED die is inserted between the electrically conductive surface and the transparent conductive layer to form a lamination. The lamination is run through a heated pressure roller system to melt the hotmelt adhesive sheet and electrically insulate and bind the top substrate to the bottom substrate. As the hotmelt sheet is softened, the LED die breakthrough so that the top electrode comes into electrical contact with the transparent conductive layer of the top substrate and the bottom electrode comes into electrical contact with the electrically conductive surface of the bottom substrate. Thus, the p and n sides of each LED die are automatically connected to the top conductive layer and the bottom conductive surface. Each LED die is encapsulated and secured between the substrates in the flexible, hotmelt adhesive sheet layer. The bottom substrate, the hotmelt adhesive (with the embedded LED die) and the top substrate can be provided as rolls of material. The rolls are brought together in a continuous roll fabrication process, resulting in a flexible sheet of lighting material.

Claims

1. A light active sheet comprising:

a bottom substrate flexible sheet having an electrically conductive surface;

a top transparent substrate flexible sheet having a transparent conductive layer disposed thereon;

an electrically insulative adhesive flexible sheet;

light active semiconductor elements fixed to the electrically insulative adhesive sheet, said light active semiconductor elements each having an n-side and a p-side, the electrically insulative adhesive sheet having the light active semiconductor elements fixed thereon being inserted between the electrically conductive surface and the transparent conductive layer to form a lamination and activated so that the electrically insulative adhesive electrically insulates and binds the top substrate sheet to the bottom substrate sheet so that one of said n-side or said p-side of the light active semiconductor elements is in electrical communication with the transparent conductive layer of the top substrate sheet and so that the other of said n-side or said p-side of each said light active semiconductor element is in electrical communication with the electrically conductive surface of the bottom substrate sheet to form a light active device,

wherein the bottom substrate, the electrically insulative adhesive and the top substrate are provided as respective rolls of material; and

the step of inserting comprising bringing the bottom substrate, the electrically insulative adhesive and the top substrate together in a continuous roll fabrication process.

2. A light active sheet according to claim 1;

wherein the electrically insulative adhesive comprises a hotmelt material activatable by applying heat and pressure to the lamination to soften the hotmelt material.

3. A light active sheet according to claim 1;

wherein the adhesive is activatable by at least one of solvent action, evaporation, catalytic reaction and radiation curing.

4. A light active sheet according to claim 1;

wherein the light active semiconductor elements are light emitting diode die.

5. A light active sheet according to claim 1;

wherein the light active semiconductor elements are light-to-energy devices.

6. A light active sheet according to claim 1;

wherein a first portion of the light active semiconductor elements emit a first wavelength of radiation and a second portion of the light active semiconductor elements emit a second wavelength of radiation.

7. A light active sheet according to claim 1;

wherein the electrically insulative adhesive comprises a hotmelt sheet; and

the light active semiconductor elements are embedded into the hotmelt sheet before forming the lamination.

8. A light active sheet according to claim 1;

wherein the light active semiconductor elements are formed into a predetermined pattern.

9. A light active sheet according to claim 8;

wherein the light active semiconductor elements are formed into the predetermined pattern by electrostatically attracting a plurality of said light active semiconductor elements on a transfer member and transferring the predetermined pattern onto the insulative adhesive.

10. A method of making a light active sheet according to claim 8;

wherein the light active semiconductor elements are formed into the predetermined pattern by magnetically attracting a plurality of said light active semiconductor elements on a transfer member and transferring the predetermined pattern onto the insulative adhesive.

11. A light active sheet according to claim 1;

wherein the transparent conductive layer comprises a transparent conductive material formed as conductive light transmissive connecting lands, each said land for connecting with a respective light active semiconductor.

12. A light active sheet according to claim 11;

further comprising a relatively higher conducting line pattern formed on at least one of the top substrate and the bottom substrate for providing a relatively lower path of resistance from a power supply source to each said light active semiconductor element.

13. A light active sheet according to claim 1;

wherein the electrically conductive surface and the electrically conductive pattern comprise a respective x and y wiring grid for selectively addressing individual said light active semiconductor elements for forming a display.

14. A light active sheet according to claim 1;

further comprising a phosphor provided in the lamination, said phosphor being optically stimulated by a radiation emission of a first wavelength from the light active semiconductor element to emit light of a second wavelength.