Optical waveguides – Planar optical waveguide – Thin film optical waveguide
Reexamination Certificate
1999-06-16
2001-11-27
Healy, Brian (Department: 2874)
Optical waveguides
Planar optical waveguide
Thin film optical waveguide
C385S014000, C385S129000, C385S130000
Reexamination Certificate
active
06324328
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a circuit carrier including several layers of at least one insulating material and conductor structures located on or in the layers.
Such circuit carriers are known and are generally constructed as circuit boards which simultaneously act as mechanical carriers of components that are fixed to the circuit board through diverse soldering processes and are connected electrically with the conductor structures. Mostly multilevel circuit boards are used which have conductor structures at least on both of their outer surfaces and often on their inner surfaces as well and feedthroughs are frequent. Depending on the requirements set by climatic conditions, component density, etc., such circuit carriers are made from epoxy-resin glass fabrics or from other synthetic materials such as polyester, polyamide or polytetrafluoroethylene. Equipping the circuit boards, usually with so-called SMD components, is mostly performed with full automation.
In view of the advantages of optical methods of transmitting information there is an increasing trend toward the use of optoelectronic components which emit and/or receive light. Flexible optical fibers are also used for connecting such optoelectronic components on circuit boards. Although a diversity of connection and plug-in techniques have been developed for connecting the optical fibers with the optoelectronic components, it is clear that none of those techniques is really suitable for automated equipping of the circuit board, in which the optical connections function outside the actual circuit board or circuit carrier.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a circuit carrier with integrated, active, optical functions, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and which provides a fundamental improvement that represents progress with respect to both mechanical strength and a possibility of automated assembly.
With the foregoing and other objects in view there is provided, in accordance with the invention, in a circuit carrier, comprising several layers of at least one insulating material and conductor structures located on or in the layers, at least one optical layer having two sides; and other layers in which both of the sides of the at least one optical layer are embedded.
As a result of the invention, the assembly of printed circuits with optoelectronic components is considerably simplified and in addition the range of application for optoelectronic systems is expanded. It is possible to dispense with complicated connections over optical fibers on the surface of the circuit board, which connections have to be made after the automated assembly.
In accordance with another feature of the invention, it is advantageous if the optical layer is adjoined on at least one side by an electrically conducting layer, especially if the electrically conducting layer is formed of an electrically conductive polymer and if the optical layer is an optically active, electrically excitable layer. In this way it is also possible to generate optical signals within the circuit carrier through excitation of the optical layer. The electrical excitation can also be used advantageously in this way, for example to actuate an optical switch, to connect optical signals between several optical layers disposed in the conductor structure if these optical layers are connected with each other, or to control a splitter which distributes the optical signals between several optical layers.
In accordance with a further feature of the invention, in order to achieve a good packing density, at least one side of the optical layer is adjoined by a circuit board layer with conductor structures.
In accordance with an added feature of the invention, the circuit board layer has a metal carrier coated by a layer of plastic. This improves both strength and thermal conductivity characteristics.
In accordance with an additional feature of the invention, there is provided a thin layer of a thermally conducting prepreg disposed between the optical layer and an adjoining layer in order to improve stability and thermal conductivity. For example, this prepreg may be placed between the layers as a film before the structure is laminated and then remains in the finished circuit carrier as just a very thin, but thermally conducting layer.
In accordance with yet another feature of the invention, the optical layer is provided with perpendicular feedthroughs which connect conductor structures on both sides of the optical layer. Such feedthroughs can thus also be used in a circuit carrier in accordance with the invention and do not interfere as long as the optical layer has a sufficient width.
In accordance with yet a further feature of the invention, the optical layer is a polyimide layer. This material has both electrical and mechanical properties which are favorable for the purpose at hand.
In accordance with yet an added feature of the invention, for the purpose of light transmission within the circuit carrier, the optical layer is constructed as a multimode waveguide, since it is less critical with regard to coupling and decoupling the optical signals due to its generally larger diameter.
In accordance with yet an additional feature of the invention, at least one side is constructed for surface mounting of SMD components.
In accordance with again another feature of the invention, there are provided optoelectronic components mounted on at least one side/surface, and an optical or fiber-optic waveguide leading from the optoelectronic components to the at least one optical layer.
In accordance with again a further feature of the invention, since the intention is to reach into the optical layer from the optoelectronic component by the shortest path, it is useful to make the optical connection between the optical waveguide and the optical layer through the use of a ground angle, preferably of less than 90°. In the same way the deflection can be realized through a prism or a partly transparent beam splitter.
In accordance with again an added feature of the invention, with regard to the laminating techniques being used, it is also recommended that the optical layer be constructed as a film or contained in a film.
In accordance with again an additional feature of the invention, the optical layer is produced by hot stamping or by visible optical patterning.
In accordance with a concomitant feature of the invention, there is provided at least one plug-in connection with electrical and optical contacts so that an electro-optical hybrid plug-in connection is provided with suitable mating contacts. The circuit carriers in accordance with the invention can therefore be used in the same way as known circuit carriers.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a circuit carrier with integrated, active, optical functions, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
REFERENCES:
patent: 5396363 (1995-03-01), Valette
patent: 5572619 (1996-11-01), Maruo et al.
patent: 5598501 (1997-01-01), Maruo et al.
patent: 5887116 (1999-03-01), Grote
patent: 5892859 (1999-04-01), Grote
patent: 6140009 (2000-10-01), Wolk et al.
Birkholtz Peter
Mehlhorn Torsten
Pröbster Walter
Greenberg Werner H.
Healy Brian
Laurence Herbert L.
Siemens Aktiengesellschaft
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