Arrays of optoelectronic devices and method of making same

• US 5,660,461 A
• Filed: 12/08/1994
• Issued: 08/26/1997
• Est. Priority Date: 12/08/1994
• Status: Expired due to Term

• Current Assignee: Quantum Devices Inc.
• Original Assignee: Quantum Devices Inc.
• Inventors: Ignatius, Ronald W., Martin, Todd S.
• Primary Examiner(s): CARIASO, ALAN B
• Application Number:
  US08/351,813
• Time in Patent Office: 992 Days
• Field of Search: 228/179.1, 257/88, 257/98, 257/99, 257/666, 257/668, 257/675, 257/676, 257/701, 257/704, 257/723, 257/725, 313/500, 313/114, 362/800, 362/240, 362/241, 362/247, 362/249, 362/226, 362/294, 362/250, 362/346, 29/827, 29/854, 29/856, 29/860
• US Class Current: 362/241
• CPC Class Codes: F21S 2/005 of modular construction
• CPC Class Codes: F21V 21/005 for several lighting devices in an end-to-end arrangement, i.e. light tracks
• CPC Class Codes: F21V 29/70 characterised by passive heat-dissipating elements, e.g. heat-sinks
• CPC Class Codes: F21V 29/76 with essentially identical parallel planar fins or blades, e.g. with comb-like cross-section
• CPC Class Codes: F21V 29/89 Metals
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 2924/00014 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 2924/01322 Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• 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
• CPC Class Codes: H01L 33/642 characterized by the shape
• CPC Class Codes: H01L 33/647 the elements conducting electric current to or from the semiconductor body
• CPC Class Codes: Y10S 362/80 Light emitting diode
• CPC Class Codes: Y10T 29/49121 Beam lead frame or beam lead device
• CPC Class Codes: Y10T 29/49172 by molding of insulating material
• CPC Class Codes: Y10T 29/49179 by metal fusion bonding

Abstract

A low cost LED array is formed from a plurality of modular units that are snapped together. Each modular unit consists of one or more U-shaped lead frame substrates which are overmolded with a thermoplastic insulator material. The lead frame substrates act as heat dissipators. The LEDs are then bonded onto the upper surfaces of the lead frame substrates. A reflector unit is separately molded and has one cone-shaped reflector for each light emitting diode. The reflector unit is aligned and affixed to the top of the lead frame unit such that the LED is disposed in the center of each cone. Each of the reflector units has several dovetail-shaped connectors which enable the completed module to be connected to adjacent modules to form the array. The modules are then electrically connected together in series or in parallel according to the particular application. The arrays may be used for plant growth or in photodynamic therapy.

Claims

1. A module having at least one optoelectronic device, comprising:

at least one electrically and thermally conductive lead frame substrate having an upper surface and being adapted to act as a heat sink;

at least one optoelectronic device electrically connected to said upper surface of said lead frame substrate; and

at least one connector interconnected with said lead frame substrate that is adapted to interconnect said lead frame substrate with at least one other lead frame substrate of another module.

2. The module of claim 1, wherein said at least one lead frame substrate comprises a plurality of lead frame substrates separated and held together by an insulator material.

3. The module of claim 2, wherein at least one of said lead frame substrates has an input electrical terminal, and wherein another of said lead frame substrates has an output electrical terminal.

4. The module of claim 3, wherein said optoelectronic device has a rated forward current associated therewith, and wherein said input electrical terminal receives an amount of current that exceeds the rated forward current of said optoelectronic device.

5. The module of claim 2, wherein at least some of said lead frame substrates have an optoelectronic device affixed thereto, and wherein each optoelectronic device is also electrically connected to another lead frame substrate in said module.

6. The module of claim 1, further comprising:

a reflector unit, having at least one reflector, affixed to said lead frame substrate such that said reflector is adjacent to said optoelectronic device.

7. The module of claim 6, wherein said reflector unit includes a plurality of reflectors, each of said reflectors having a coating of a reflective material.

8. The module of claim 6, wherein said at least one connector is affixed to said reflector unit.

9. The module of claim 8, wherein said reflector unit has a male connector and a female connector that are adapted to connect said reflector unit with a reflector unit of another module.

10. The module of claim 1, wherein said optoelectronic device is a light emitting diode.

11. The module of claim 1, wherein said lead frame substrate is U-shaped in cross-section.

12. The module of claim 1, wherein at least a portion of the lead frame substrate to which an optoelectronic device is affixed is coated with a metal.

13. An array of optoelectronic devices, comprising:

a plurality of modules of optoelectronic devices, each of said modules including

a plurality of electrically and thermally conductive lead frame substrates, each of said substrates being adapted to act as a heat sink, at least one of said substrates having an input electrical terminal and at least one other substrate having an output electrical terminal;

an optoelectronic device electrically connected to at least some of said lead frame substrates;

means for mechanically connecting two of said modules together; and

means for electrically connecting an input terminal of one of said modules to an output terminal of another module.

14. The array of claim 13, wherein each of said optoelectronic devices has a rated forward current associated therewith, and wherein said input electrical terminal receives an amount of current that exceeds the rated forward current of said optoelectronic devices.

15. The array of claim 13, wherein each module also includes:

a reflector unit interconnected with said lead frame substrates and having a plurality of reflectors thereon, each of said reflectors being adjacent to an optoelectronic device.

16. The array of claim 15, wherein each of said modules includes at least two registration members that are used to align said reflector unit.

17. The array of claim 13, wherein the lead frame substrates in each module are held together by an insulator material.

18. The array of claim 13, wherein said lead frame substrates are U-shaped in cross-section.

19. The array of claim 13, wherein each optoelectronic device is also electrically connected to an adjacent lead frame substrate.

20. The array of claim 13, wherein said mechanically connecting means comprises:

at least one male connector interconnected with each module; and

at least one female connector interconnected with each module.

21. The array of claim 13, wherein said electrical connecting means comprises a lead wire connected between an input terminal of a module and an output terminal of another module.

22. A method of manufacturing a module having at least one optoelectronic device, comprising;

forming at least one lead frame substrate;

applying an insulator material onto portions of said lead frame substrate to create a lead frame unit;

affixing said at least one optoelectronic device onto said lead frame unit; and

forming at least one connector that connects said module to an adjacent module.

23. The method of claim 22, wherein said lead frame forming step includes:

creating a lead frame substrate; and

bending said lead frame substrate into a U-shape.

24. The method of claim 22, wherein said insulator applying step includes:

placing said at least one lead frame substrate into a mold; and

molding a thermoplastic insulator material onto portions of said lead frame substrate.

25. The method of claim 22, wherein said device affixing step includes:

bonding an optoelectronic device onto said lead frame substrate; and

affixing a lead wire between said bonded optoelectronic device and another lead frame substrate.

26. The method of claim 22, further comprising:

coating said optoelectronic device with a transparent protective layer.

27. The method of claim 22, wherein lead frame forming step includes:

forming at least one electrical terminal on said lead frame substrate.

28. The method of claim 22, further comprising:

forming a reflector unit having at least one reflector; and

affixing said reflector unit to said lead frame unit such that said at least one reflector is disposed adjacent to said at least one optoelectronic device.

29. The method of claim 28, wherein said reflector unit forming step includes:

applying a layer of a reflective material onto said reflector.

30. The method of claim 28, wherein said reflector unit forming step includes:

forming a plurality of connectors on said reflector unit such that each of said connectors may be connected with an adjacent reflector unit.

31. The method of claim 28, wherein said reflector unit affixing step includes:

bonding said reflector unit onto an upper surface of said lead frame unit.

32. The method of claim 28, further comprising:

forming at least two registration members on said lead frame unit that are used to align said reflector unit with said lead frame unit.

33. A method of manufacturing an array of optoelectronic devices, comprising:

creating a plurality of modules of optoelectronic devices, each of said modules being created by

forming a plurality of lead frame substrates such that at least one of said substrates has an input electrical terminal and at least one of said lead frame substrates has an output electrical terminal;

applying an insulator material onto portions of said lead frame substrates to create a unit of spaced lead frame substrates;

forming at least one connector that is interconnected with said lead frame unit;

mechanically connecting said at least one connector on each module with a connector of another module; and

electrically connecting the output electrical terminal of at least one of said modules with the input electrical terminal of another module.

34. The method of claim 33, further comprising:

electrically connecting the input terminal of at least one of said modules with a power supply.

35. The method of claim 33, wherein said module creating step further comprises:

forming a reflector unit having a plurality of reflectors; and

affixing said reflector unit to said unit of spaced lead frame substrates such that a reflector is disposed adjacent to each of said optoelectronic devices.

36. The method of claim 35, wherein said reflector unit forming step includes:

forming at least one male connector on each reflector unit; and

forming at least one female connector on each reflector unit.

37. The method of claim 33, wherein said electrically connecting step includes:

affixing a lead wire between the output electrical terminal of at least one of said modules and the input electrical terminal on another module.