Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor – Having light transmissive window
Reissue Patent
2000-10-25
2002-02-19
Fahmy, Wael (Department: 2823)
Semiconductor device manufacturing: process
Packaging or treatment of packaged semiconductor
Having light transmissive window
C438S127000, C438S126000, C257S081000
Reissue Patent
active
RE037554
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to optoelectronic semiconductor components. More particularly, the invention pertains to a method for producing an optoelectronic semiconductor component, specifically for applications having very narrow radiation and/or reception characteristics. The components comprise a chip carrier, which has an approximately planar chip carrier surface and on which an optoelectronic semiconductor chip is fastened with predetermined alignment of its optical axis, and a base part, which is assigned to the chip carrier, supports the latter and is produced from a plastic material, the semiconductor chip being electrically conductively connected to at least two electrode terminals routed through the base part, and the semiconductor chip being assigned a lens, which covers over the base part.
Prior art optoelectronic semiconductor components, in particular those which are subject to increased demands with regard to their optical properties, have largely been produced in metal-glass housings. There, the chip carriers are, usually, baseplates produced from metal mounted with a metal cap with a glass lens fitted in. Due to the mounting by means of a metal housing, it has been possible, on the one hand, to ensure a hermetically sealed closure of the housing and, on the other hand, to provide suitability of the optoelectronic semiconductor component for specific high-temperature applications starting from about 150° C. The ageing of the semiconductor chip given such a type of mounting was slight since, on account of the metal housing type used, there was essentially no loading on the semiconductor chip on account of directly surrounding material. Finally, it has been possible to configure the optical properties of the semiconductor component favorably on account of the glass lens fitted into the metal cap.
The considerable costs necessarily incurred by the relatively complicated production are regarded as a significant disadvantage of the optoelectronic semiconductor components that have been produced to date. In this case, the metal cap with a glass lens fitted in, which requires a high production outlay, has a particular impact. Furthermore, the semiconductor components mounted in metal-glass housings have problems on account of the adjustment and manufacturing tolerances that must be estimated to be relatively large, with the result that such optoelectronic semiconductor components generally have relatively unfavorable squint angles. These are production-dictated deviations of the optical axis from the mechanical axis of the component. As a result, such semiconductor components can only be used to a limited extent in applications which involve narrow radiation and/or reception characteristics. In the prior art optoelectronic semiconductor components, a larger adjustment play during mounting consequently has an extremely unfavorable effect on the squint angle obtained, given closer tolerance specifications.
Furthermore, mass-produced plastic light-emitting diodes having lesser requirements with regard to the optical qualities are known in which the housing with a baseplate and a cap is cast in one process operation and thus produced in one part. That production process is significantly less expensive than metal-glass housings. However, as a result of the single work operation of the (pressureless) casting production, excessively high adjustment tolerances and thus high squint angles are produced. The optoelectronic semiconductor components produced in such a way have quite unsatisfactory optical properties for specific applications.
There have become known, as disclosed in Patent Abstracts of Japan, Vol. 16, No. 055 (E-1165), Feb. 12, 1992, & JP-A-03254162, a light-emitting diode with a base part made of metal and a plastic cap with a lens part. There, the object is to improve the positioning accuracy and to increase the emission rate.
Reference is also had to Patent Abstracts of Japan, Vol. 11, No. 367 (E-561), Nov. 28, 1987 & JP-A-62139367 and Patent Abstracts of Japan, Vol. 11, No. 312 (E-548), Oct. 12, 1987 & JP-A-62105486, which show further light-emitting diodes with separately configured lens caps.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a method of producing an optoelectronic semiconductor component, which overcomes the above-mentioned disadvantages of the prior art methods of this general type and which provides for a component that, given high requirements on the adjustment tolerances and thus squint angles, can be produced considerably more cost-effectively as compared to the prior art.
With the foregoing and other objects in view there is provided, in accordance with the invention, a method of producing an optoelectronic semiconductor component, in particular such a component with very narrow radiation and/or reception characteristics. The method comprises:
providing a chip carrier strip with a multiplicity of successively arranged chip carriers each having a substantially planar chip carrier surface, injection-molding a base part around an individual chip carrier of the multiplicity of chip carriers on the chip carrier strip and at least two electrode terminals extending through the base part;
fastening an optoelectronic semiconductor chip with a given optical axis on the chip carrier surface of the chip carrier;
contacting the optoelectronic semiconductor chip with the at least two electrode terminals extending through the base part;
providing an independent cap produced from plastic material and having a lens with an optical axis, and placing the independent cap on the base part such that the cap and the base part are automatically positioned with respect to one another such that the optical axis of the lens and the optical axis of the semiconductor chip substantially coincide; and
permanently fastening the cap to the base part.
In accordance with an added feature of the invention, the step of providing the independent cap comprises producing the cap as a separate structural part in an injection molding operation.
In accordance with an additional feature of the invention, a lens covering is produced between the base part and the cap, the lens covering the semiconductor chip.
In accordance with another feature of the invention, an individual optoelectronic semiconductor component is separated from the chip carrier strip only subsequently to the steps of injection-molding, fastening the semiconductor chip on the chip carrier surface, and contacting the semiconductor chip with the electrode terminals.
In accordance with a further feature of the invention, the cap is provided with a holding means and the holding means is positively locked (form-locked) to a support of the base part by placing the cap onto the base part and mutually engaging the holding means and the support, and forming the holding means and the support such that when the cap is placed onto the base part the optical axes of the lens and the semiconductor chip are automatically aligned with one another.
In other words, the objects of the invention are satisfied in that the independently configured cap produced from plastic material is produced as a separate structural part by means of an injection molding operation. The base part is produced in an injection molding operation of a chip carrier from a multiplicity of chip carriers arranged successively in a chip carrier strip. An optoelectronic semiconductor component is separated from the chip carrier strip only after the base part has been produced, after the semiconductor chip has been fastened on the chip carrier surface by means of bonding, and after the semiconductor chip has been contacted with the electrode terminals. The carrier strip encapsulated by injection molding may be produced and processed in an endless manner, so-called reel-to-reel technique. Overall, it is possible in this way to realize cost-effective mounting of the component with very close electro-optical parameter tolerances.
In accordance with a preferred embodiment of the invention,
Brunner Herbert
Haas Heinz
Waitl Günter
Berezny Neal
Fahmy Wael
Siemens Aktiengesellschaft
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