Optoelectronic package with dam structure to provide fiber standoff

• US 6,655,854 B1
• Filed: 08/03/2001
• Issued: 12/02/2003
• Est. Priority Date: 08/03/2001
• Status: Active Grant

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Deane, Peter, Pham, Ken, Nguyen, Luu Thanh, Mazotti, William Paul, Roberts, Bruce Carlton
• Primary Examiner(s): Healy, Brian
• Application Number:
  US09/922,357
• Time in Patent Office: 851 Days
• Field of Search: 385/88, 385/89, 385/92, 385/94, 385/49, 438/26, 438/27, 438/29, 438/31
• US Class Current: 385/88
• CPC Class Codes: G02B 6/4202 for coupling an active element with fibres without intermediate optical elements, e.g. fibres with plane ends, fibres with shaped ends, bundles
• CPC Class Codes: G02B 6/4231 with intermediate elements, e.g. rods and balls, between the elements
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/48471 the other connecting portion not on the bonding area being a ball bond, i.e. wedge-to-ball, reverse stitch
• 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

Abstract

An optoelectronic component is described that includes a photonic device carried by a base substrate. A dam structure is formed on the base substrate by dispensing and hardening a precise amount of a flowable material. The dam structure is sized to define a desired standoff between an optical fiber and an active facet on the photonic device. In embodiments where the photonic device is wire bonded to the base substrate, it may be desirable to provide a reverse wire bond in order to permit the optical fiber to be placed closer to the photonic device. In some embodiments, the base substrate takes the form of a flexible material having electrically conductive traces thereon that are electrically connected to the photonic device. An optical component support block may be provided to support the flex material. In some implementations, a semiconductor die may be directly soldered to the traces on the flexible material.

Claims

1. An optoelectronic package comprising:

a base substrate;

a photonic device carried by the base substrate, the photonic device having an active facet thereon;

an optical fiber in optical communication with the facet on the photonic device; and

a dam structure formed by dispensing a flowable material on the substrate and hardening the dispensed material, the dam structure being sized to define a desired standoff between the optical fiber and the photonic device.

2. An optoelectronic package as recited in claim 1 wherein the dam structure is formed by dispensing and curing an epoxy based material.

3. An optoelectronic package as recited in claim 1 wherein the substrate has electrically conductive traces thereon that are electrically connected to the photonic device.

4. An optoelectronic package as recited in claim 3 further comprising a semiconductor die in electrical communication with the photonic device through the conductive traces on the substrate.

5. An optoelectronic package as recited in claim 4 wherein the die is directly soldered to the substrate.

6. An optoelectronic package as recited in claim 3 wherein the substrate is formed from a flex material.

7. An optoelectronic package as recited in claim 6 further comprising an optical component support block that supports the flex material.

8. An optoelectronic package as recited in claim 7 wherein the photonic device has at least one bond pad thereon, the bond pad being electrically connected to an associated conductive trace on the substrate by a bonding wire.

9. An optoelectronic package as recited in claim 8 wherein the bonding wire is stitch bonded to the bond pad and ball bonded to the associated conductive trace.

10. An optoelectronic package as recited in claim 1 wherein the dam structure directly contacts a cladding portion of the optical fiber.

11. An optoelectronic package as recited in claim 1 further comprising a fiber termination that supports a distal end of the optical fiber, wherein the dam structure directly contacts the fiber termination.

12. An optoelectronic package as recited in claim 1 wherein a plurality of dam structures are provided.

13. An optoelectronic package as recited in claim 1 wherein the optical fiber has a chamfered distal surface.

14. An optoelectronic package as recited in claim 1 wherein the photonic device has a plurality of facets, the package comprising a plurality of said dam structures and a plurality of optical fibers, wherein each optical fiber has at least one associated dam structure.

15. An optoelectronic package as recited in claim 1 wherein the dam structure is formed by dispensing a thermoset plastic or a silicone gel.

16. An optoelectronic package as recited in claim 1 wherein the dam structure is configured to define a desired angle between the optical fiber and the photonic device.

17. An optoelectronic package as recited in claim 1 wherein the dam structure completely surrounds the photonic device.

18. An optoelectronic package comprising:

a base substrate having at least one electrically conductive trace thereon;

a photonic device carried by the base substrate, the photonic device having an active facet and at least one bond pad thereon;

at least one reverse bonded bonding wire, each reverse bonded bonding wire being ball bonded to an associated conductive trace on the base substrate and stitch bonded to an associated bond pad;

an optical fiber in optical communication with the facet on the photonic device; and

a dam structure formed on the base substrate, the dam structure being sized to define a desired standoff between the optical fiber and the photonic device.

19. An optoelectronic package as recited in claim 18 wherein the dam structure is formed by dispensing and curing an epoxy based material.

20. An optoelectronic package as recited in claim 18 wherein the base substrate is a flex cable.

21. An optoelectronic package as recited in claim 18 wherein the dam structure directly contacts one of a cladding portion of the optical fiber or a ferrule that is attached to the optical fiber.

22. An optoelectronic package as recited in claim 18 wherein the photonic device has a plurality of facets, the package comprising a plurality of said dam structures and a plurality of optical fibers, wherein each optical fiber has at least one associated dam structure.

23. An optoelectronic component comprising:

a flexible base substrate having at least one electrically conductive trace thereon;

an optical component support block that supports the flexible base substrate;

a photonic device mounted on the base substrate, the photonic device having an active facet thereon;

an optical fiber in optical communication with the facet on the photonic device; and

a dam structure formed by dispensing a flowable material on the base substrate and hardening the dispensed material, the dam structure being sized to define a desired standoff between the optical fiber and the photonic device.

24. An optoelectronic package as recited in claim 23 wherein the photonic device has at least one bond pad thereon, the bond pad being electrically connected to an associated conductive trace on the substrate by a bonding wire.

25. An optoelectronic package as recited in claim 23 wherein a plurality of dam structures is provided.

26. A method of packaging an optoelectronic device comprising:

attaching a photonic device directly or indirectly to a base substrate;

forming a registration dam on the base substrate by dispensing an accurate volume of a flowable material on the base substrate and hardening the dispensed material to form the registration dam; and

positioning an optical fiber over the photonic device such that the registration dam sets a desired optical standoff distance between an active facet of the photonic device and the optical fiber.

27. A method as recited in claim 26 further comprising wire bonding at least one bond pad on the photonic device to an associated trace on the base substrate, the height of the registration dam being sufficiently high to prevent the optical fiber from contacting a bonding wire formed by the wire bonding.

28. A method as recited in claim 27 wherein the wire bonding is reverse wire bonding.

29. A method as recited in claim 26 wherein the registration dam is brought into direct contact with one of a cladding portion of the optical fiber or a fiber termination that carries the optical fiber.

30. A method as recited in claim 26 further comprising forming at least one additional registration dam on the base substrate, wherein each additional registration dam is formed by dispensing an additional accurate volume of the flowable material on the base substrate and hardening the dispensed additional flowable material.

31. A method as recited in claim 26 wherein the dispensed flowable material is an epoxy based material and the hardening is accomplished by curing the epoxy based material.

32. A method as recited in claim 26 wherein the dam structure is snap cured by exposing the dispensed flowable material to one of ultraviolet light or heat.

33. A method of packaging an optoelectronic device comprising:

attaching a photonic device to a base substrate;

forming a registration dam on the base substrate by dispensing an accurate volume of a flowable epoxy based material on the base substrate and curing the dispensed material to form the registration dam;

reverse wire bonding at least one bond pad on the photonic device to an associated trace on the base substrate, the height of the registration dam being sufficiently high to prevent the optical fiber from contacting a bonding wire formed by the wire bonding; and

positioning an optical fiber over the photonic device such that the registration dam sets a desired optical standoff distance between an active facet of the photonic device and the optical fiber.

34. A method as recited in claim 33 further comprising forming at least one additional registration dam on the base substrate, wherein each additional registration dam is formed by dispensing an additional accurate volume of the epoxy based material on the base substrate and hardening the dispensed additional material.