Plastic and nonmetallic article shaping or treating: processes – Optical article shaping or treating – Optical fiber – waveguide – or preform
Reexamination Certificate
1999-09-07
2001-11-06
Vargot, Mathieu D. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Optical article shaping or treating
Optical fiber, waveguide, or preform
C264S272140, C264S272150, C264S275000
Reexamination Certificate
active
06312624
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The field of the invention is the production of electrooptical components or modules, which typically have a receptacle, also called a plug-in bay, for the connection and optical coupling of suitable coupling partners, such as optical lines. As the coupling partners, other optical or electrooptical elements, for instance for the sake of galvanic separations, a further electrooptical module as well, are also conceivable. For converting electrical signals into optical signals, or for converting optical signals into electrical signals, such modules have electrooptical converters, which have a light-projecting region (transmitter) or light-sensitive region (receiver) that in the context of the present invention can also be called optically active zones. For high coupling efficiency when optical signals are fed into wave guides or output from them, not only the electrooptical transformation of the signals but also a precise coupling of the signal-diverting and/or signal delivering optical wave guide (coupling partner) are necessary. As the transmitter, in optical transmission technology, light-emitting diodes (LEDs) or horizontal-beam laser diodes are for instance employed. Because of their construction, such diodes often have a high aperture number, which for high-efficiency optical coupling requires the use of lenses.
The invention relates to a method for producing an electrooptical module in which the electrooptical converter is disposed in a predetermined position on a substrate, and in which the substrate together with the converter is at least partly embedded in a molded body of a moldable material, and the molded body has at least one functional surface serving the purpose of coupling with a coupling partner.
One such production method is known from Published, European Patent Application EP 0 053 482 A2. In the known production method, a substrate (lead frame) of the desired shape is stamped out from a metal sheet (such as a copper foil) first and then gold-coated. Next, the converter (in the case of a transmitter, a laser diode, for instance, or in the case of a receiver, a photo diode) is mounted on the substrate and contacted by way of bond wires and conductive paste for the sake of electrical triggering or signal connection. Next, the substrate together with the converter and optionally other trigger circuits are placed in half shells, which form an injection mold of the desired contour. A suitable transparent, heat-curable resin is placed in the injection mold, and under temperature and pressure, a molded body that imbeds the converter is created. The molded body has at least one functional surface of a predetermined contour serving the purpose of coupling with a coupling partner. The functional surface may for instance be a convex face of a lens serving to shape the beam between the converter and an optical wave guide to be coupled. However, the functional surface may instead or in addition be embodied as a stop face or alignment face for the coupling partner (such as an optical wave guide plug). The molded body is then placed in a housing with mechanical locking elements for the coupling partner.
The known production method includes two especially critical production steps namely, positioning the converter on the substrate, and positioning the substrate in the injection mold, on whose precision the coupling and outcoupling efficiency attainable with the electrooptical module depends. The Published, European Patent Application EP 0 053 482 A2 provides no further teachings in this respect.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a method for producing an electrooptical module that overcomes the above-mentioned disadvantages of the prior art methods of this general type, which with regard to the position of the electrooptical converter or its optically active zone assures an extremely precise disposition or embodiment of the functional surface in a reliably replicable manner.
With the foregoing and other objects in view there is provided, in accordance with the invention, a method for producing an electrooptical module, which includes:
providing a substrate having at least one positioning element formed therein;
precisely positioning the substrate via the at least one positioning element in an assembly device;
disposing and fixing an electrooptical converter on the substrate in a precise position relative to the at least one positioning element;
positioning precisely and subsequently the substrate together with the electrooptical converter in an injection mold using the at least one positioning element; and
injecting a moldable material into the injection mold forming a molded body having at least one functional surface serving for coupling with a coupling partner, the molded body embedding and surrounding, at least partly, the substrate together with the electrooptical converter.
In the production method of the type defined at the outset, the object is attained according to the invention in that the substrate is provided with at least one positioning element. The substrate is precisely positioned by the positioning element in an assembly device, in which the converter is disposed and fixed on the substrate in a precise relative position to the positioning element. The substrate is subsequently positioned precisely by the positioning element in an injection mold and surrounded by the moldable material, thereby forming the molded body and the functional surface.
One substantial advantage of the production method of the invention is that by using simple parts and production techniques, an economical configuration with an extremely precise relative position of the electrooptical converter to the functional surface is assured. Since all the production steps that are critical in this respect refer to the same reference mark or marks—namely, the one or more positioning elements—an extremely precise relative alignment of the converter and the functional surface always exists, regardless of the precision for instance of the production of the outer contour of the substrate. As already noted, the functional surface may for instance be a lens surface or a stop face; however, the type of functional surface is not limited to this but can for instance instead be embodied as a mirror surface. The positioning element may advantageously be embodied as a recess or a protrusion. In principle, all structural and/or geometrical elements suitable for a replicable, positionally accurate positioning of the substrate can be employed in the context of the present invention. Especially preferably, a plurality of positioning elements are provided on or in the substrate.
A feature of the method of the invention that is especially preferred in this respect provides that the substrate is provided with two circular recesses as its positioning elements.
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 method for producing an electrooptical module, 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.
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patent: 3810300 (1974-05-01), Hulmes et al.
patent: 4410469 (1983-10-01), Katagiri et al.
patent: 5275765 (1994-01-01), Go et al.
patent: 5355018 (1994-10-01), Fierkens
patent: 0053482A2 (1982-06-01), None
“An expensive passive method of aligning fibers to laser or photodetector arrays”, Christopher K. Y. Chun et al., Technical Developments, Motrolla, Nov. 1996, pp. 152-155.
Greenberg Laurence A.
Infineon - Technologies AG
Lerner Herbert
Stemer Werner H.
Vargot Mathieu D.
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