This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2009-076704, filed Mar. 26, 2009, the entire contents of which are incorporated herein by reference.
There have been proposed some optical wiring devices which optically connect LSIs. The feature of A optical wiring is, for example, that there is little frequency dependency, such as loss, in a wide frequency range from DC to 100 GHz or above, and that wiring of several-ten Gbps can easily be realized because of the absence of electromagnetic hindrance of wiring lines and ground potential variation noise. In the optical wiring device, a very high speed operation can be expected in the printed board level or rack level, and vigorous research and development have been promoted. JP2008-158440 describes that there is known, as an example, an optical wiring device which is configured such that optical semiconductor devices, etc. The optical semiconductor devices are aligned on an optoelectronic wiring board in which optical wiring and electric wiring are combined.
An optoelectronic wiring board according to aspect of the present invention includes,
an optical wiring including an optical waveguide;
an electrical wiring including an electrically conductive material;
an optical input/output portion which transmits and detects optical signal with and from the optical waveguide;
a dummy optical input portion provided adjacent to the optical input/output portion; and
a dummy optical waveguide which is connected to the dummy optical input portion and has an optical end portion which is provided at an end opposite to the dummy optical input portion and absorbs or scatters light which is incident on the dummy optical input portion.
A method of manufacturing optoelectronic wiring device using the optoelectronic wiring board includes,
making light incident on a first dummy optical waveguide through first dummy optical input portions;
subjecting an image, which is acquired from the first dummy optical input portions and a vicinity thereof, to a binarizing process;
recognizing a black part of the image, thereby detecting a position of the first dummy optical input portions; and
disposing an optical semiconductor device or an external light guide on optical input/output portions of an optoelectronic wiring board, by using a result of the detection as an index.
Embodiments of the present invention will now be described with reference to the accompanying drawings. In the description below, common parts are denoted by like reference numerals throughout the drawings.
In first to third embodiments and modifications thereof, a optoelectronic FPC (Flexible Printed Circuit) is described as an example of an optoelectronic wiring board. First to third embodiments of the present invention, however, is not limited to the optoelectronic FPC, and First to third embodiments of the present invention is similarly applicable to a rigid board such as an ordinary printed wiring board (PWB), and various materials are usable therefor. For example, use may be made of various materials, for example, (glass) epoxy which is a general PWB material, polyimide which is a general FPC material, Teflon (trademark) which is used for a low-dielectric-constant board, and acryl or silicone, which is used for a optical waveguide. Furthermore, ceramic materials may be used. Besides, mixture materials of these materials may be used. Optical and electrical wiring patterns and the number of wirings may be determined according to purposes of use. The terminal end structure of a optical waveguide (the structure of an optical input/output portion) may be arbitrarily chosen, and these possible variations do not depart from the spirit of the invention.
A description will now be given of an optoelectronic wiring board according to a first embodiment, and a method of manufacturing a optoelectronic wiring device using the optoelectronic wiring board.
An electric wiring 7 is formed of Cu with a thickness of, e.g. 12 μm, and metal bumps 8 is e.g. solder bumps or Au stud bumps. The optical wiring channel 2 includes a vertical upright mirror (45° mirror). The vertical upright mirror 6 is formed by processing the optical waveguide core 2 at 45° at an optical input/output portion 9, and providing the processed surface with a reflection metal 6 (e.g. Au).
An optical signal, as indicated by an arrow in
As shown in
The 45° mirror 6 may be formed by a dicing process using a blade with a 45° cross section, or by a laser ablation method in which an excimer laser beam or a CO2 laser beam is radiated in an oblique direction. After the 45° processing, Au is deposited by evaporation on the 45° processed surface, and thereby the 45° mirror 6 is completed.
At this time, 45° mirrors 12 are also formed at positions which are spaced apart by predetermined distances in the second direction from the optical wiring channels 2 on both sides of the optical semiconductor devices 4 and 5, the 45° mirrors 12 being positioned on straight lines along which the 45° mirrors 6 of the optical wiring channels 2 are disposed. The 45° mirror 12 is formed on each a dummy optical input portion 11. This dummy optical input portion 11 is formed in the same fabrication step as the optical input portion 9. The dummy mirror 12 has the same structure as the reflective metal mirror 6. In other words, the dummy mirror 12, too, is a vertical upright mirror having a 45° surface on which Au, for instance, is deposited by evaporation. Thereby, the positions of the optical input/output portions 9 of the optical wiring channels 2 can be confirmed even after the optical semiconductor devices 4 and 5 are mounted. Specifically, intersections between imaginary extension lines of the optical wiring channels 2 and the dummy optical input portions 11, which are located on both sides of the optical input/output portions 9, that is, which are closest to the optical input/output portions 9, are the positions of the optical input/output portions 9 of the optical wiring channels 2 (points 0 in
Next, referring to
Thereby, the dummy optical waveguide 3 effectively absorbs radiation light for image (pattern) recognition. Thus, at the time of pattern recognition, the dummy optical input portion 11 can surely be recognized as a black pattern. As will be described later, the “pattern recognition” means a process of binarizing a photographed image in the vicinity of the dummy optical input portion 11, and recognizing the black of the image of the dummy optical input portion 11 and the white of the image of the surrounding area of the dummy optical input portion 11. Thereby, the position (coordinates, etc.) of the image, which is recognized as black, is recognized. It is the dummy mirror 12 that is recognized as black. At this time, the light incident on the dummy optical input portion 11 is horizontally reflected by the 45° mirror 12, and is emitted from the dummy optical waveguide 3 into the cladding 2a (or 2b) at the end of the dummy optical waveguide 3. Thus, the incident light hardly returns to the dummy optical input portion 11. In short, the dummy optical input portion 11 becomes equivalent to a black pattern due to light absorption, and a black pattern with a high light/dark contrast can be realized.
As regards the optoelectronic wiring board according to the embodiment and the method of manufacturing the optoelectronic wiring device using the same, image recognition radiation light is absorbed by the optical input/output portions 9 that are provided at the end portions of the optical waveguides 2. Thereby, the shapes of the optical input/output portions 9 are detected as a positional reference. In particular, additional optical waveguides and light input/output portions, which correspond to the optical waveguides 2 and the optical input/output portions 9 provided at the end portions of the optical waveguides 2, are independently formed at parts spaced apart from the position of mounting of optical elements, etc., and the shapes of these additional dummy optical input portions 11 are detected to recognize the optical axes of the optical waveguides 2.
According to the optoelectronic wiring board of the embodiment and the method of manufacturing the optoelectronic wiring device using the same, even in the case where there is a positional displacement between the mechanically-processed dummy optical input portion 11 and the electrical wiring pattern, optical axis alignment can exactly be performed between the optical semiconductor devices 4 and 5 or external light guides (optical fibers or other optoelectronic wiring boards) and the optical waveguides. Therefore, there are provided an optoelectronic wiring board and a manufacturing method thereof, which can suppress degradation in optical wiring performance due to the positional displacement between the electric wiring pattern and the optical waveguide optical input/output portion 4, 5 (the optical semiconductor devices 4 and 5 or external light guides).
On the other hand, in a manufacturing method of an optoelectronic wiring board according to a comparative example, in many cases, positional alignment has been performed with reference to an electrical wiring pattern which is formed by a pattern process using photolithography. Thus, the precision of positional alignment is influenced by the mirror formation position precision of 45° mirror processing, as well as by the pattern alignment precision between the photolithography of the electrical wiring pattern and the photolithography of the optical waveguide pattern. In general, since the mechanical processing error of the mirror formation tends to be greater than the positional alignment error of photolithography, there is such a difficulty that the optical axis error tends to easily occur, no matter how exactly the optical waveguide pattern is formed. This being the case, as disclosed in JP2008-158440, there has been proposed a method in which optical elements, etc. are mounted by using an emission light pattern of a optical waveguide in combination as a marker. However, in this method, there are such problems that light needs to be made incident from the opposite side of the optical waveguide, and that the wavelength, at which light propagation of the optical waveguide is possible, does not agree with the light wavelength that is necessary for pattern recognition, and optimal alignment cannot be performed.
However, according to the optoelectronic wiring board of the embodiment and the method of manufacturing the optoelectronic wiring device using the same, the positions of the optical input/output portions 9 under the optical semiconductor devices 4 an 5 can surely be confirmed. Furthermore, for the illumination of image recognition, use is not made of the light of long wavelengths (in general, red to infrared) which enable easy propagation through the optical waveguide, as in JP2008-158440, but use can be made of the light of short wavelengths (e.g. blue, with wavelengths of 400 nm to 450 nm) which tends to enhance the image recognition precision. Thus, the image recognition precision itself can be enhanced. Specifically, since the light that is incident on the dummy optical input portion 11 is hardly reflected and returned in the inside, the outer boundary of the dummy optical input portion 11 can clearly be confirmed, and the exact position confirmation of the external appearance of the dummy optical input portion 11 can be realized.
Therefore, according to the optoelectronic wiring board of the embodiment and the method of manufacturing the optoelectronic wiring device using the same, the optical axis alignment between the optical waveguide 2 and the optical semiconductor device 4, 5 or external light guide can exactly be performed, while tolerating the positional error between the electrical wiring pattern by photolithography and the optical waveguide optical input/output portion by mechanical processing. With the conventional processing means being used, it is possible to remarkably improve the light transmission quality of the optical wiring part and the manufacturing yield of optoelectronic wiring devices. Therefore, the optoelectronic wiring board according to the embodiment and the method of manufacturing the optoelectronic wiring device using the same have such advantageous effects that the performance of information communication equipment, etc. can be improved by introduction/promotion of optical wiring, and this contributes to the development of industries.
As has been described above, in the optoelectronic wiring board 110 according to the present embodiment, the optical semiconductor device 4, 5 or external optical waveguide is disposed on the optoelectronic wiring board 110 including the optical wiring formed by the optical waveguide 2 and the electrical wiring 7 formed by the electrically conductive material, the optoelectronic wiring board 110 comprising the optical input/output portion 9 which transmits and detects optical signal with and from the optical waveguide 2, the dummy optical input portion 11 which is formed in the same fabrication step as the optical input/output portion 9, the dummy optical input portion 11 provided adjacent to the optical input/output portion 9, and the dummy optical waveguide 3 which is connected to the dummy optical input portion 11 and has an optical terminal end portion which is provided at an end opposite to the dummy optical input portion 11 and absorbs or scatters light that is incident on the dummy optical input portion 11.
Further, the method of manufacturing the optoelectronic wiring device 100 using the optoelectronic wiring board 110 according to the present embodiment comprises disposing the dummy optical input portion 11 on the same line as the optical input/output portion 9, and providing no electrical wiring 7 in the region that is necessary for pattern recognition of the surrounding area of the dummy optical input portion 11.
Preferably, the dummy optical input portion 11 should be provided on at least two locations in association with each optical input/output portion 9.
In addition, in the optoelectronic wiring board 110 according to the present embodiment, the optical semiconductor device 4, 5 or external light guide is disposed on the optoelectronic wiring board 110 including the optical wiring formed by the optical waveguide 2 and the electrical wiring 7 formed by the electrically conductive material, the optoelectronic wiring board 110 comprising the optical input/output portion 9 which transmits and detects optical signal with and from the optical waveguide 2, the dummy optical input portion 11 which is formed in the same fabrication step as the optical input/output portion 9, the dummy optical input portion 11 provided adjacent to the optical input/output portion 9, and the dummy optical waveguide 3 which is connected to the dummy optical input portion 11 and has an optical terminal end portion which is provided at an end opposite to the dummy optical input portion 11 and prevents light, which is incident on the dummy optical input portion 11, from being reflected to the dummy optical input portion 11.
A second embodiment of the invention relates to a process of manufacturing the optoelectronic wiring device 100 which is configured such that the optical semiconductor device 4, 5 or external light guide is disposed on the optical input/output portion 9 of the optoelectronic wiring board 110, which has been described in the first embodiment. Specifically, a description is given of the method of manufacturing the optoelectronic wiring device 100. In this method, the photographed image of the vicinity of the dummy optical input portion 11 is subjected to a binarizing process, and the position of the dummy optical input portion 11 is detected. Using the detection result as a position index, the optical semiconductor device 4, 5 or external light guide is disposed on the optical input/output portion 9.
On the other hand, even in such a case, the dummy optical input portion 11 is not affected by stray light, and is recognized as a black pattern with high contrast. The reason for this is that the end portion of the dummy optical waveguide 3 is cut off, as described above, and the light, which is incident on the dummy optical input portion 11 of the dummy optical waveguide 3, is scattered at the end portion. In short, the light, which strikes the dummy mirror 12 at the dummy optical input portion 11, is reflected. Hence, the dummy mirror 12 is recognized as black. The region including the dummy mirror 12 and its periphery is divided, with high contrast, into the black of the mirror part of the dummy mirror 12 and the white of the peripheral area thereof. Accordingly, the dummy optical input portion 11 shown in
In theoptoelectronic wiring board 110 according to the present embodiment, since the dummy optical input portion 11 serving as a marker becomes a black pattern with high contrast, it is effective in enhancing positional precision to recognize the peripheral region of the dummy optical input portion 11 as a binary image. A binary image is an image in which a light part and a black part of an image are forcibly sorted into white and black on the basis of a predetermined threshold of luminance. The use of the binary image is an effective image recognition method for improving the recognition of a pattern boundary. Since the binary image recognition is more effective in the case of an image with higher luminance contrast, the binary image recognition is very effective if it is applied to the recognition of the dummy optical input portion 11 with a high contrast, which is shown in
In general, wiring electrodes 7 of optical semiconductor devices 4 or 5, as shown in
Next, a description is given of an optoelectronic wiring board according to a third embodiment and a method of manufacturing a optoelectronic wiring device using the same. Referring to
In the example of
The present invention is not limited to the above-described first to third embodiments. Although the above-described embodiments show some concrete examples, these are merely structural examples, and other means (materials, dimensions) may be applied to the respective elements according to the spirit of the invention. The materials, shapes and dispositions, shown in the embodiments, are merely examples, and the embodiments are workable in combination. For example, although the optical waveguide is formed on the side opposite to the substrate film, the electric wiring may be formed on the optical waveguide, and the optical element may be disposed immediately near the optical input/output portion. Although one light emission part and one light detection part are connected in one-to-one correspondence, it is possible to connect light emission parts and light detection parts in one-to-plurality correspondence (plurality-to-one correspondence) or in plurality-to-plurality correspondence. Other modifications may be made without departing from the spirit of the present invention.
Other embodiments of the present invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and example embodiments be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following.
Number | Date | Country | Kind |
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2009-076704 | Mar 2009 | JP | national |