Ceramic optical sub-assembly for optoelectronic modules

• US 20030026081A1
• 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: Liu, Jia, Pham, Ken, Nguyen, Luu Thanh, Mazotti, William Paul, Briant, John P., Roberts, Bruce Carlton, Gee, Stephen Andrew
• Granted Patent: US 7,023,705 B2
• Time in Patent Office: Days
• US Class Current: 361/760
• CPC Class Codes: G02B 6/4201 Packages, e.g. shape, construction, internal or external 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 layout of balanced signal pairs H05K1/0245; superposed layout H05K2201/09672
• 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

Optoelectronic components, specifically, ceramic optical sub-assemblies are described. In one aspect, the optoelectronic component includes a ceramic base substrate having a pair of angled (or substantially perpendicular) faces. The electrical traces are formed directly on the ceramic surfaces and extend between the pair of faces. A semiconductor chip assembly is mounted on the first face of the ceramic 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 ceramic 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. It is particularly well adapted for use with vertical cavity surface emitting lasers (or laser arrays) and detectors (or detector arrays). In some embodiments, at least the cathode of the photonic device is soldered directly to a cathode pad on the base substrate. Similarly, in some embodiments, the semiconductor chip assembly is electrically connected to the base substrate by direct soldering. Specific base substrate structures are disclosed as well.

Claims

1. An optoelectronic package comprising:

a ceramic backing block having a front face and a bottom face that are angled relative to one another;

an electrical circuitry set formed on the front and bottom face, the circuitry set including a metal pad formed on the front face and traces that extend from the front face to the bottom face;

a semiconductor chip assembly mounted to the bottom face of the backing block, the semiconductor chip assembly having a first surface having a plurality of first contacts that are electrically coupled to associated traces on the bottom face of the backing block 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; and

a photonic device having at least one active facet, a cathode, and at least one anode thereon, the photonic device being mounted to the metal pad on the front face of the backing block such that the cathode is in contact with the metal pad.

2. An optoelectronic package as recited in claim 1 wherein the front and bottom face of the ceramic backing block are angled at approximately 90 degrees relative to one another and the front and bottom face interface at a 90 degree corner.

3. An optoelectronic package as recited in claim 1 wherein the anode(s) are wire bonded to associated traces on the ceramic backing block.

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

5. An optoelectronic package as recited in claim 4 further comprising:

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

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

6. An optoelectronic package as recited in claim 5 wherein each of the alignment pins are ceramic.

7. An optoelectronic package as recited in claim 6 wherein a distal tip of the optical fiber is oriented at a small angle relative to the front face of the ceramic backing block.

8. An optoelectronic package as recited in claim 5 further comprising a shim that extends from the front 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.

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

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

11. An optoelectronic package as recited in claim 1 further comprising at least one fiducial feature on the front face that is approximately the same size as an anode pad located on the photonic device.

12. An optoelectronic package as recited in claim 1 further comprising at least one ground plane embedded beneath the surface of the front and bottom faces of the ceramic backing block.

13. An optoelectronic package as recited in claim 1 wherein the ceramic backing block is formed of alumina having purity of at least 95%.

14. A ceramic backing block for use in an optoelectronic package, the backing block comprising:

a front face suitable for supporting a photonic device;

a bottom face suitable for attachment to a driver module, the bottom face being angled relative to the front face;

an electrical circuitry set formed on both the front and bottom faces;

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

an alignment slot positioned in the front face.

15. A ceramic backing block as recited in claim 14 wherein the alignment slot is arranged to align the backing block relative to a sleeve, which holds the packaged optoelectronic component.

16. A ceramic backing block as recited in claim 14 further comprising at least one ground plane embedded within the front and bottom faces.

17. A ceramic backing block as recited in claim 14 wherein the front face and the bottom face are angled at 90 degrees with respect to each other and the front face and the bottom face interface along a 90-degree corner.

18. A ceramic backing block as recited in claim 14 wherein the ceramic backing block is formed of alumina having purity of at least 95%.

19. A ceramic backing block as recited in claim 14 further comprising a shim that is attached to the front face of the backing block and positioned between the pair of alignment holes.

20. A ceramic backing block for use in an optoelectronic package, the backing block comprising:

a front wall having a front face suitable for supporting a photonic device;

a bottom wall having a bottom face suitable for attachment to a driver module, the bottom face being angled relative to the front face;

a pair of side walls that extend between the front and bottom faces;

an electrical circuitry set formed on both the front and bottom faces;

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

an alignment slot positioned in the front face.

21. A ceramic backing block as recited in claim 20 further comprising at least one ground plane embedded within the front and bottom walls.

22. A ceramic backing block as recited in claim 20 wherein the front face and the bottom face are angled at 90 degrees with respect to each other and the front face and the bottom face interface along a 90-degree corner.

23. A ceramic backing block as recited in claim 20 wherein the driver module is a semiconductor device.