Optical sub-assembly for optoelectronic modules

• US 20030026556A1
• Filed: 06/06/2002
• Published: 02/06/2003
• 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: Clarke, Roger William, Deane, Peter, Liu, Jia, Nelson, Michael R., Koh, Yongseon, Smith, Christopher J., Pham, Ken, Nguyen, Luu Thanh, Mazotti, William Paul, Briant, John P., Roberts, Bruce Carlton, Townsend, Janet E.
• Granted Patent: US 6,916,121 B2
• Time in Patent Office: Days
• US Class Current: 385/92
• CPC Class Codes: G02B 6/4201 Packages, e.g. shape, construction, internal or external details
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• 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 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: H05K 1/0219 Printed shielding conductors for shielding around or between signal conductors, e.g. coplanar or coaxial printed shielding conductors
• CPC Class Codes: H05K 1/189 characterised by the use of a flexible or folded printed circuit H05K3/326 takes precedence
• CPC Class Codes: H05K 2201/0715 provided by an outer layer of PCB
• CPC Class Codes: H05K 2201/09236 Parallel layout
• CPC Class Codes: H05K 2201/10121 Optical component, e.g. opto-electronic component
• CPC Class Codes: H05K 3/403 Edge contacts; Windows or holes in the substrate having plural connections on the walls thereof H05K3/4092 takes precedence

Abstract

Concepts for conveniently arranging devices for the transduction of signals to and from voltage and current domains to infrared radiation domains is described. Specifically, optoelectronic components and methods of making the same are described. In one aspect, the optoelectronic component includes a base substrate having a pair of angled (or substantially perpendicular) faces with electrical traces extending therebetween. A semiconductor chip assembly is mounted on the first face of the base substrate and a photonic device is mounted on the second face. Both the semiconductor chip assembly and the photonic device are electrically connected to traces on the base substrate. The semiconductor chip assembly is generally arranged to be electrically connected to external devices. The photonic devices are generally arranged to optically communicate with one or more optical fibers. The described structure may be used with a wide variety of photonic devices. In some embodiments the base substrate is formed from a ceramic material having the electrical traces formed thereon. In other implementations the substrate includes a backing block having a flexible printed circuit substrate adhered thereto.

Claims

1. An optoelectronic package comprising:

a base substrate having a first face and a second face that are angled relative to one another and electrical traces that extend from the first face to the second face;

a semiconductor chip assembly mounted on the first face of the base substrate, the semiconductor chip assembly having a plurality of first contacts that are electrically coupled to associated traces on the base substrate; and

a photonic device mounted on the second face of the base substrate, the photonic device having at least one active facet thereon and having a plurality of second contacts that are electrically coupled to associated traces on the base substrate.

2. An optoelectronic package as recited in claim 1 wherein the first face and the second face of the base substrate are angled at approximately 90 degrees relative to one another.

3. An optoelectronic package as recited in claim 1 wherein the base substrate is formed from a ceramic material having the electrical traces formed thereon.

4. An optoelectronic package as recited in claim 1 wherein the base substrate includes a backing block and a flexible printed circuit interface having the electrical traces formed thereon, the flexible printed circuit interface being adhered to the backing block.

5. An optoelectronic package as recited in claim 4 wherein the first face and the second face of the base substrate are substantially perpendicular to one another, the optoelectronic package further comprising a smoothly rounded corner between the first face and the second face.

6. An optoelectronic package as recited in claim 5 wherein the radius of the rounded corner between the first and second faces is between approximately 50 and 100 microns.

7. An optoelectronic package as recited in claim 1 wherein the photonic device has a cathode and at least one anode, wherein the cathode is soldered directly to a cathode pad on the base substrate.

8. An optoelectronic package as recited in claim 7 wherein the anode(s) are wire bonded to associated traces on the base substrate.

9. An optoelectronic package as recited in claim 1 wherein the photonic device has bond pads thereon and at least some of the bond pads are reverse wire bonded to associated traces on the base substrate.

10. An optoelectronic package as recited in claim 1 further comprising an optical fiber in optical communication with the facet on the photonic device.

11. An optoelectronic package as recited in claim 10 further comprising:

a fiber termination device that carries an end of the optical fiber; and

at least one alignment pin that extends from the second face of the base substrate, wherein the alignment pin is arranged to engage the fiber termination device to position the optical fiber relative to the photonic device.

12. An optoelectronic package as recited in claim 10 wherein a distal tip of the optical fiber is oriented at a small angle relative to the second face of the base substrate.

13. An optoelectronic package as recited in claim 11 further comprising a shim that extends from the second face of the base substrate wherein the shim is in contact with the fiber termination device and maintains a standoff distance between the optical fiber and the photonic device.

14. An optoelectronic package as recited in claim 1 wherein the electrical path between a selected first contact and a selected second contact that serves as an anode for the photonic device is less than approximately 2 mm.

15. An optoelectronic package as recited in claim 1 wherein the photonic device includes a vertical cavity surface emitting laser or laser array.

16. An optoelectronic package as recited in claim 1 wherein the active facet is a detector or a detector array.

17. An optoelectronic package as recited in claim 1 wherein the semiconductor chip assembly is soldered directly to the base substrate to electrically connect the semiconductor chip assembly to the base substrate.

18. An optoelectronic package as recited in claim 1 wherein the semiconductor chip assembly is or includes a die having contacts on opposing top and bottom surfaces, wherein contacts on the top surface are coupled to the base substrate and contacts on the bottom surface are coupled to external devices.

19. An optoelectronic package as recited in claim 1 further comprising a smoothly rounded corner between the first face and the second face.

20. An optoelectronic package as recited in claim 18 wherein the radius of the rounded corner between the first and second faces is between approximately 50 and 100 microns.

21. An optoelectronic package as recited in claim 1 further comprising a shim that is attached to second face of the base substrate at a position proximate to the photonic device.

22. A support block for use in an optoelectronic package, the support block comprising:

a first wall having a first face suitable for supporting a semiconductor device;

a second wall having a second face that is angled relative to the first face, there being a smoothly rounded corner between the first face and the second face wherein the radius of the rounded corner between the first and second faces is between approximately 25 to 200 microns;

a pair of side walls that extend between the first and second walls;

a pair of alignment holes in the second wall, the alignment holes being suitable for receiving associated alignment pins suitable for engaging an optical fiber termination; and

an alignment slot positioned in the second wall.

23. A support block as recited in claim 22 wherein the second and side walls each have a thickness that is within 20 percent of the thickness of the first wall.

24. A support block as recited in claim 22 wherein the alignment slot is arranged to align the support block relative to a sleeve, which holds the packaged optoelectronic component.

25. An optoelectronic package comprising:

a base having a first wall having a first face and a second wall having a second face, the first and second faces being substantially perpendicular to one another, there being a smoothly rounded corner between the first face and the second face;

a flexible substrate adhered to the first and second faces, the flexible substrate having electrical traces formed thereon;

a driver module mounted on the flexible substrate at a location over the first face, the driver module having a plurality of first contacts that are electrically coupled to associated traces on the flexible substrate;

a photonic device mounted on the flexible substrate at a location over the second face, the photonic device having at least one active facet thereon and having a plurality of second contacts that are electrically coupled to associated traces on the flexible substrate; and

an optical fiber in optical communication with the facet on the photonic device.

26. An optoelectronic package as recited in claim 25 wherein the distance between the driver module and the photonic device is less than approximately 1000 microns.

27. An optoelectronic package as recited in claim 25 wherein the driver module has third contacts opposite the first contacts and wherein the first contacts are soldered directly to the base substrate and the third contacts are positioned for electrical connected to an external device.

28. An optoelectronic package as recited in claim 25 further comprising a shim that is attached to the flexible substrate at a position proximate to the photonic device.

29. A method of forming a component for use in an optoelectronic package, the method comprising:

adhering a flexible substrate to a block having a first wall having a first face and a second wall having a second face, the first and second faces being substantially perpendicular to one another, there being a smoothly rounded corner between the first face and the second face;

attaching a photonic device to the flexible substrate at a location over the first wall; and

attaching a driver device to the flexible substrate at a location over the second wall.

30. An optoelectronic package comprising:

a base substrate having a first face and a second face and electrical traces that extend from the first face to the second face, the first and second faces being substantially perpendicular to one another;

a semiconductor chip assembly mounted on the first face of the base substrate, the semiconductor chip assembly having a first surface having a plurality of first contacts that are electrically coupled to associated traces on the base substrate by direct soldering and a second surface opposite the first surface, the second surface of the semiconductor chip assembly having plurality of second contacts that are suitable for electrical connection to external devices;

a photonic device mounted on the second face of the base substrate, the photonic device having at least one active facet thereon and having a cathode and at least one anode, wherein the cathode is directly soldered to an associated cathode trace on the base substrate; and

an optical fiber in optical communication with the facet on the photonic device.

31. An optoelectronic package as recited in claim 30 wherein the base substrate is one selected from the group consisting of:

a base unit formed from a ceramic material having the electrical traces formed thereon; and

a structure includes a backing block and a flexible printed circuit interface adhered to the backing block, the flexible printed circuit interface having the electrical traces formed thereon.

32. An optoelectronic package as recited in claim 30 further comprising:

a fiber termination that carries an end of the optical fiber; and

a pair of alignment pins that extend from the second face of the base substrate, wherein the alignment pins are arranged to engage the fiber termination to position the optical fiber relative to the photonic device.

33. An optoelectronic package as recited in claim 30 wherein the electrical path between a selected first contact and a selected second contact that serves as an anode for the photonic device is less than approximately 2 mm.

34. An optoelectronic package as recited in claim 30 wherein the photonic device includes a vertical cavity surface emitting laser or laser array.