Plastic packaging of LED arrays

• US 20030160256A1
• Filed: 03/14/2003
• Published: 08/28/2003
• Est. Priority Date: 09/01/2000
• Status: Active Grant

• Current Assignee: Current Lighting Solutions, LLC (f/k/a GE Lighting Solutions, LLC) (American Industrial Partners)
• Original Assignee: General Electric Company
• Inventors: Saia, Richard Joseph, Balch, Ernest Wayne, Krishnamurthy, Vikram B., Durocher, Kevin Matthew, Cole, Herbert Stanley, Kolc, Ronald Frank
• Granted Patent: US 6,730,533 B2
• Time in Patent Office: Days
• US Class Current: 257/88
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/81 using a bump connector
• CPC Class Codes: H01L 2224/85 using a wire connector
• CPC Class Codes: H01L 2224/85399 Material
• CPC Class Codes: H01L 2224/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• CPC Class Codes: H01L 23/13 characterised by the shape
• CPC Class Codes: H01L 23/3677 Wire-like or pin-like cooling fins or heat sinks
• CPC Class Codes: H01L 23/49833 the chip support structure consisting of a plurality of insulating substrates
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• 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 2924/00012 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 2924/01005 Boron [B]
• CPC Class Codes: H01L 2924/01006 Carbon [C]
• CPC Class Codes: H01L 2924/01013 Aluminum [Al]
• CPC Class Codes: H01L 2924/01015 : Phosphorus [P]
• CPC Class Codes: H01L 2924/01023 : Vanadium [V]
• CPC Class Codes: H01L 2924/01027 : Cobalt [Co]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01039 : Yttrium [Y]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/01058 : Cerium [Ce]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/07811 : Extrinsic, i.e. with electrical conductive fillers
• CPC Class Codes: H01L 2924/10329 : Gallium arsenide [GaAs]
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 2924/12042 : LASER
• CPC Class Codes: H01L 2924/1433 : Application-specific integrated circuit [ASIC]
• CPC Class Codes: H01L 2924/15153 : the die mounting substrate comprising a recess for hosting the device
• CPC Class Codes: H01L 2924/15157 : Top view
• CPC Class Codes: H01L 2924/15165 : Monolayer substrate
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/19041 : being a capacitor
• CPC Class Codes: H01L 2924/19042 : being an inductor
• CPC Class Codes: H01L 2924/19043 : being a resistor
• CPC Class Codes: H01L 2924/207 : Diameter ranges
• CPC Class Codes: H01L 33/46 : Reflective coating, e.g. dielectric Bragg reflector
• 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: Y10S 362/80 : Light emitting diode
• CPC Class Codes: Y10T 29/49155 : Manufacturing circuit on or in base
• CPC Class Codes: Y10T 29/49169 : Assembling electrical component directly to terminal or elongated conductor
• CPC Class Codes: Y10T 29/49171 : with encapsulating

Abstract

There is provided a flexible circuit module, including at least one rigid carrier, at least one solid state device mounted over a first side of the at least one rigid carrier, a flexible base supporting a second side of the at least one rigid carrier, a conductive interconnect pattern on the flexible base, and a plurality of feed through electrodes extending from the first side to the second side of the at least one rigid carrier and electrically connecting the conductive interconnect pattern with the at least one of a plurality of the solid state devices. The solid state devices may be LED chips to form an LED array module.

Claims

1. A flexible circuit module, comprising:

at least one rigid carrier;

at least one solid state device mounted over a first side of the at least one rigid carrier;

a flexible base supporting a second side of the at least one rigid carrier;

a conductive interconnect pattern on the flexible base; and

a plurality of feed through electrodes extending from the first side to the second side of the at least one rigid carrier and electrically connecting the conductive interconnect pattern with the at least one of a plurality of the solid state devices.

2. The module of claim 1, wherein the at least one solid state device comprises a plurality of semiconductor light emitting devices.

3. The module of claim 2, wherein the plurality of semiconductor light emitting devices comprises a plurality of light emitting diode chips.

4. The module of claim 3, wherein the at least one rigid carrier comprises a plurality of rigid carriers.

5. The module of claim 4, wherein the plurality of rigid carriers each contain at least one cavity containing at least one light emitting diode chip.

6. The module of claim 5, wherein the at least one cavity comprises a plurality of cavities each containing a light emitting diode chip.

7. The module of claim 5, wherein side walls of the at least one cavity are inclined at an angle of about 35 to about 70 degrees with respect to a bottom surface of the at least one cavity.

8. The module of claim 5, further comprising:

a reflective material deposited onto at least the side walls of the at least one cavity;

an encapsulating material in the at least one cavity over the at least one light emitting diode chip; and

at least one lens over the at least one light emitting diode chip.

9. The module of claim 8, further comprising a phosphor material over the at least one light emitting diode chip.

10. The module of claim 3, wherein the at least one rigid carrier is substantially thicker than the flexible base.

11. The module of claim 10, wherein the flexible base comprises a sheet having a thickness of 0.5 to 3 mils and the at least one rigid carrier comprises a plastic body having a first thickness of 10 to 50 mils in the at least one cavity portion and a second thickness of 40 to 80 mils in at least one other portion.

12. The module of claim 3, wherein the interconnect pattern comprises a first portion located on a second surface of the flexible base and a plurality of second portions extending through the flexible base to the first surface of the flexible base.

13. The module of claim 12, further comprising an adhesive layer between the second surface of the at least one rigid carrier and a first surface of the flexible base.

14. The module of claim 13, wherein the adhesive layer comprises an anisotropic adhesive which is electrically conductive substantially along a first axis between the rigid carrier and the flexible base, but is electrically insulating substantially along a direction perpendicular to the first axis.

15. The module of claim 14, wherein:

the second portions of the interconnect pattern contact the anisotropic adhesive layer;

the anisotropic adhesive layer contacts the plurality of feed through electrodes; and

the plurality of the feed through electrodes contact bonding pads of the plurality of the light emitting diode chips either directly or through lead wires.

16. The module of claim 13, wherein:

the second portions of the interconnect pattern extend through the adhesive layer and contact the plurality of the feed through electrodes; and

the plurality of the feed through electrodes contact bonding pads of the plurality of the light emitting diode chips either directly or through lead wires.

17. The module of claim 3, further comprising at least one feed through heat sink contacting the at least one solid state device and extending from the first side to the second side of the at least one rigid carrier.

18. The module of claim 3, wherein:

the at least one rigid carrier comprises a plurality of molded plastic rigid carriers, each containing at least one cavity;

the at least one solid state device comprises a plurality of light emitting diode chips located in the cavities in the plurality of rigid carriers;

the flexible base comprises a polyimide sheet having a thickness of 0.5 to 3 mils which is substantially thinner than the plurality of the rigid carriers;

the interconnect pattern comprises a first portion located on a second surface of the flexible base and a plurality of second portions extending through the flexible base and;

i) extending through an adhesive layer located between the second surfaces of the plurality of rigid carriers and a first surface of the flexible base, and further extending to the plurality of feed through electrodes;

or

ii) extending to an anisotropic adhesive layer, which is electrically conductive substantially along a first axis between the plurality of rigid carriers and the flexible base, but is electrically insulating substantially along a direction perpendicular to the first axis, wherein the adhesive layer is located between the second surfaces of the plurality of rigid carriers and a first surface of the flexible base, and the adhesive layer contacts the plurality of the feed through electrodes; and

the plurality of the feed through electrodes contact bonding pads of the plurality of the light emitting diode chips either directly or through lead wires.

19. An illumination device, comprising:

the module of claim 3;

a power source; and

a shell enclosing the module and the power source.

20. A method of forming a flexible circuit module, comprising:

adhering a first side of at least one rigid carrier over a first side of a flexible module base;

forming a conductive interconnect pattern having a first portion over a second side of the flexible module base and a plurality of second portions extending through the flexible module base toward the at least one rigid carrier; and

forming at least one solid state device on a second side of the at least one rigid carrier and in electrical contact with the conductive interconnect pattern through the at least one rigid carrier.

21. The method of claim 20, wherein the step of forming at least one solid state device comprises forming at least one light emitting diode chip in at least one cavity in the at least one rigid carrier.

22. The method of claim 21, further comprising forming a plurality of light emitting diode chips in a plurality of cavities in a plurality of rigid carriers.

23. The method of claim 22, wherein the step of adhering comprises forming an adhesive layer between the first side of the at least one rigid carrier and the first side of the flexible module base.

24. The method of claim 23, wherein the step of adhering comprises forming the adhesive layer over the first side of the plurality of rigid carriers and adhering the plurality of rigid carriers to flexible module base.

25. The method of claim 23, wherein the step of forming the conductive interconnect pattern comprises:

forming vias in the flexible module base;

depositing at least one metal layer over the second side of the flexible module base and in the vias; and

patterning the metal layer to form the interconnect.

26. The method of claim 25, wherein:

the step of forming vias comprises laser drilling the vias up to a plurality of feed through electrodes embedded in the plurality of rigid carriers after the step of adhering; and

the step of depositing the at least one metal layer comprises plating or sputtering a nickel or copper metal layer to contact the plurality of the feed through electrodes.

27. The method of claim 26, wherein:

the step of forming vias further comprises laser drilling the vias through the rigid carrier after the step of adhering; and

the step of depositing the at least one metal layer comprises plating or sputtering a nickel or copper metal layer after the step of adhering such that a portion of the at least one metal layer is exposed on the second side of the plurality of rigid carriers.

28. The method of claim 25, wherein:

the step of depositing comprises forming the at least one metal layer prior to the step of adhering; and

the step of adhering comprises adhering the at least one rigid carrier to the flexible module base such that the second portions of the patterned conductive interconnect contact the adhesive layer;

wherein the adhesive layer comprises an anisotropic adhesive layer which is electrically conductive substantially along a first axis between the carriers and the base, but is electrically insulating substantially along a direction perpendicular to the first axis.

29. The method of claim 22, wherein the step of forming a plurality of light emitting diode chips comprises:

placing a plurality of light emitting diode chips with the chip pads toward the second side of the plurality of rigid carriers; and

contacting a plurality of embedded feed through electrodes exposed in the second side with the chip pads.

30. The method of claim 22, wherein the step of forming a plurality of light emitting diode chips comprises:

placing a plurality of light emitting diode chips with the chip pads away from the second side of the plurality of rigid carriers; and

wire bonding a plurality of lead wires between the chip pads and a plurality of embedded feed through electrodes exposed in the second surface.

31. The method of claim 22, further comprising:

forming a reflective material at least on the side walls of the plurality of cavities;

forming an encapsulating layer in the plurality of cavities over the plurality of light emitting diode chips; and

forming a plurality of lens structures over the plurality of light emitting diode chips.

32. The method of claim 31, further comprising forming a phosphor material over the plurality of light emitting diode chips.

33. The method of claim 20, further comprising:

placing at least two conductive posts into a mold cavity;

filling the mold cavity with a fluid insulating material;

solidifying the fluid insulating material to form the at least one rigid carrier, wherein at least two surfaces of the at least two conductive posts are exposed to form at least two feed through electrodes in the at least one rigid carrier.

34. The method of claim 33, further comprising placing at least three conductive posts into the mold cavity to form at least one feed through heat sink in addition to the at least two feed through electrodes.

35. A method of forming a packaged solid state device, comprising:

placing at least one conductive element into a mold cavity;

filling the mold cavity with a fluid insulating material;

solidifying the fluid insulating material to form an insulating carrier, wherein at least two surfaces of the at least one conductive element are exposed after solidification; and

placing at least one solid state device on the insulating carrier in contact with one surface of the at least one conductive element.

36. The method of claim 35, wherein the at least one conductive element comprises a metal heat sink.

37. The method of claim 35, wherein the at least one conductive element comprises at least two metal electrodes.

38. The method of claim 37, wherein the at least one solid state device comprises at least one light emitting diode chip in electrical contact with the at least two metal electrodes.

39. The method of claim 38, wherein:

the step of filling comprises filling the mold with a fluid plastic or epoxy material;

the step of solidifying comprises heating or cooling the fluid plastic material to form a rigid plastic insulating carrier containing at least one cavity; and

the step of placing at least one solid state device comprises placing at least one light emitting diode chip into the at least one cavity in contact with the exposed top surfaces of the two electrodes.

40. The method claim 38, wherein

the step of filling comprises filling the mold with a powder plastic material and fluidizing the powder plastic material;

the step of solidifying comprises heating the fluidized material under pressure to form a rigid plastic insulating carrier containing at least one cavity; and

the step of placing at least one solid state device comprises placing at least one light emitting diode chip into the at least one cavity in contact with the exposed top surfaces of the two electrodes.

41. The method of claim 38, further comprising:

adhering a first side of the insulating carrier to a first side of a flexible module base; and

forming a conductive interconnect pattern over a second side of the flexible module base extending through the flexible module base toward the insulating carrier to form an electrical connection with the at least one light emitting diode chip.