Optical waveguides – With optical coupler – Particular coupling structure
Reexamination Certificate
1999-11-05
2001-12-04
Ngo, Hung N. (Department: 2874)
Optical waveguides
With optical coupler
Particular coupling structure
C385S088000
Reexamination Certificate
active
06327408
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the connection of optical and electrical components on an integrated package and particularly the electrical interconnection of optical components to electrical components.
2. Technical Background
As optical fibers increase in their use in communication systems, there is an ever increasing need for a higher degree of integration of optical components and electrical components in fiber optic applications. Also, the components themselves have become increasingly complex. Conventional wire interconnections typically employ gold wires having a diameter from 25 to 33 micrometers (&mgr;m) connecting electrical lines of, for example, a planar lightwave circuit to the pin connections for the package. The mechanical resonant frequency of a wire of, for example, 25 micrometers in diameter and 2.5 mm in length is approximately 2.2 kHz. Quality control tests, such as the Bellcore qualification test, requires vibration testing in the frequency range of from 10 Hz to 2 kHz. With relatively long wires of the prior art, as the resonant frequency is approached or reached, there is a tendency for the wire bonds to break loose due to vibration, thereby causing failure of the packaged component. In order to alleviate this problem, the length of interconnecting conductors have been shortened to approximately 1 mm to raise the resonant frequency of such conductors to about 5 kHz. This technique of the prior art is known as “stitching” and, although reducing or eliminating the failure of components due to vibration, it increases the number of bonds as well as requiring island pads for the interconnection of series coupled shorter conductors.
Another approach in connection optical components to electrical components is the use of feed lines which are conductors printed on a substrate extending across a package. For components such as a thermal-optic 8×8 switch can result in over 200 electrical connections. The lines must have a size sufficient to maintain their resistance relatively low in order to avoid parasitic heating while at the same time there must be sufficient spacing between adjacent lines to prevent electrical cross talk. These factors lead to the consumption of a considerable amount of the surface area of a package, and, while reducing some of the problems inherent with separate electrical conductors, the use of parallel feed lines does not result in a compact hybrid package.
There exists a need, therefore, for packaging technique and structure for optical/electrical devices in a single package which alleviates the problems with wire bonds and connection techniques of the prior art.
SUMMARY OF THE INVENTION
The interconnection system of the present invention provides a package for an optical/electrical component including an optical component and one or more bridges of insulating material in spaced relationship to the optical component. Electrical components are mounted on the bridge on a side opposite the optical component. Electrical connection from the electrical component to conductors on the side of the bridge facing the optical component is made by plated through-hole connections extending through the bridge. Relatively short electrical conductors are employed to interconnect the optical component with the electrical component and the optical or electrical components to connecting pins extending from the package.
In another embodiment of the invention, one or more bridges are positioned with electrical conductors of a bridge coupled in direct electrical contact with the connector pins using a conductive bonding agent, such as a conductive adhesive material or solder. Electrical contacts on the second side of the bridge are coupled to the first side using plated through-hole connections extending through the bridge and to electrical components, which are coupled to the optical component by relatively short wire connections.
In a further embodiment of the invention, the bridge includes a plurality of electrical conductors or contacts on a side facing an optical component within the package. Electrical contacts between the optical device and the contacts on the surface of the bridge facing the optical component and the connector pins are directly made using a conductive bonding agent, such as a conductive adhesive, or solder. Through-hole connections couple the conductors on the first side of the bridge with an electrical component mounted on the second side of the bridge. This structure eliminates wire connections between the electrical component and optical component and between both of the components and the connector pins. In each embodiment, the number of wire bonds is greatly reduced or eliminated in an electro/optical package resulting in a less expensive more reliable component.
Additional features and advantages of the invention will be set forth in the detailed description which follows and will be apparent to those skilled in the art from the description or recognized by practicing the invention as described in the description which follows together with the claims and appended drawings.
It is to be understood that the foregoing description is exemplary of the invention only and is intended to provide an overview for the understanding of the nature and character of the invention as it is defined by the claims. The accompanying drawings are included to provide a further understanding of the invention and are incorporated and constitute part of this specification. The drawings illustrate various features and embodiments of the invention which, together with their description serve to explain the principals and operation of the invention.
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Corning Incorporated
Ngo Hung N.
Price Heneveld Cooper DeWitt & Litton
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