JP2004327516A - Multilayered substrate effective for optical and electrical utility and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively provide a multilayered substrate 1 effective for optical and electrical utility the whole body of which can be driven at a high speed and which is high in yield. <P>SOLUTION: This multilayered substrate 1 effective for optical and electrical utility is constituted by laminating a substrate 10 containing an electric element, a substrate 11 containing an optical element, and an optical waveguide substrate 12 upon another by using an insulating adhesive material 20 and, at the same time, electrically connecting the electric and optical elements to each other in the adhesive material 20 by using bumps 101 and 201 formed in the substrates 10 and 11 containing the elements. In addition, the substrate 11 containing the optical element and an optical waveguide is optically connected to each other. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an opto-electric hybrid board and a method for manufacturing the same.
[0002]
[Prior art]
2. Description of the Related Art In recent years, the capacity and speed of communication data have been rapidly increasing, and the demand for faster communication of larger capacity data has been increasing day by day.
In order to transmit large volumes of data at high speeds, optical communication, which has a high transmission speed, is used, especially for long-distance communications, and optical waveguides are used in relatively long wiring sections inside printed wiring boards and semiconductor packages. Wave paths are provided, and an interconnection device or the like that converts an optical signal into an electric signal using a laser diode, a photodiode, or the like is used for a CPU or the like. The current interconnection device has a configuration in which a substrate having an optical element and an optical waveguide is mounted on a substrate on which an electric element is mounted, and electrical wirings are electrically connected to each other by wire bonding.
[0003]
Also, a configuration in which an electric element and an optical element are mounted on the same substrate and both elements are connected by electric wiring, and in Patent Document 1, a part of electric terminals of the electric element and the optical element are mounted by flip-chip connection, Patent Document 2 proposes a configuration in which an optical substrate is mounted on one side of a printed circuit board and an electric element is surface-mounted on the other side.
[0004]
[Patent Document 1]
JP 2001-7352 A [Patent Document 2]
JP-A-9-26530
[Problems to be solved by the invention]
In order to drive at high speed on a substrate on which optical elements and electric elements are mixedly mounted, it is necessary to make the wiring length of the electric wiring as short as possible. When the electric element and the optical element are mounted on the same substrate as described above, the wiring of the electric wiring is performed two-dimensionally in the same plane, and the wiring is affected by the chip size, the electrode position, and the fine wiring. It is difficult to shorten the length.
[0006]
Further, in the invention of Patent Literature 1, since the optical element and a part of the electric element are directly connected and mounted by flip chip bumps, the number of input / output electric signals is restricted. Further, in the optical element, it is necessary to concentrate the electrodes at a position where the optical element is to be flip-chip bonded to the electric element, and furthermore, there arises a problem that a design considering the number and arrangement of the electrodes of the electric element is required. In addition, in the case of this mounting format, the operation cannot be confirmed until after all the elements have been mounted, and the board assembly process involves the risk of device defects. However, it became a big failure cost and was a problem.
[0007]
In the invention of Patent Document 2, an electric element is surface-mounted on one side of a multilayer printed wiring board, and an optical element is surface-mounted on the other side. Therefore, in order to receive and emit an optical signal, an optical signal is applied to the electric element on one side. Therefore, it is necessary to form a sensor unit for receiving (emitting) light, and to provide an input / output terminal for electric wiring on the other surface, which limits the configuration of the optical element and increases the manufacturing cost.
[0008]
An object of the present invention is to provide an opto-electric hybrid board that can drive the entire board at a high speed, has a high yield, and is inexpensive, with respect to the above-described problems of the related art.
[0009]
[Means for Solving the Problems]
The present inventor has conducted intensive studies in order to solve the above-mentioned problems, and has reached the present invention. That is, according to claim 1, a substrate having a built-in electric element, a substrate having a built-in optical element, and a plurality of optical waveguide substrates are laminated by using an insulating adhesive, and the electrical connection between the elements is a substrate having the built-in elements. A multilayer opto-electric hybrid board characterized by being connected in an insulating adhesive using bumps formed on the substrate, and being optically connected to the substrate incorporating the optical element and the optical waveguide. is there.
[0010]
As described above, since the substrate on which each element is incorporated is stacked using the connection bumps formed near the chip, the electrical wiring between the elements can be three-dimensionally routed, and the wiring length can be shortened. , Transmission loss and transmission delay can be reduced. Further, it is preferable that the electric element and the optical element are arranged so that the center positions of the respective elements are overlapped with each other when they are stacked in a state of a substrate having the respective elements built therein, since the wiring length is shorter.
[0011]
Further, since the number of electrical connections and the position can be matched on the substrate on which each element is built, the number and arrangement of the electrodes of each element are not restricted, and the optical element is electrically connected to the input / output surface of the optical signal. Since normal elements with signal input / output surfaces formed on the same plane can be used, there is no need to use dedicated elements with different light and electric input / output planes, and low-cost elements can be used. it can.
[0012]
Further, in claim 2, at least one of the substrates having the electric element built therein is electrically connected to the substrate having the optical element built therein, and the substrate having the electric element built therein is a substrate having another element built therein. 3. The multilayer opto-electric hybrid board according to claim 1, wherein the multi-layer opto-electric hybrid board is electrically connected to the substrate.
[0013]
Thus, even with the multilayer opto-electric hybrid board having a configuration using the multi-layered board incorporating the element, the same function and effect as the multi-layer opto-electric hybrid board according to claim 1 can be obtained.
[0014]
According to a third aspect of the present invention, there is provided the multilayer opto-electric hybrid board according to the first or second aspect, wherein the heat sink layer is interposed between the substrates in which the respective elements are incorporated.
[0015]
By inserting the heat sink layer between the substrates as described above, it is possible to avoid an unstable operation due to heat generated from each element. Further, by patterning this heat sink so as not to contact the connection bumps provided on each substrate, the heat sink can be laminated by using an insulating adhesive when the opto-electric hybrid board of the present invention is multi-layered. Thus, a multilayer opto-electric hybrid board having excellent heat dissipation can be obtained.
[0016]
Further, as the heat sink, it is desirable to use a metal having high thermal conductivity, such as copper, silver, gold, aluminum, and nickel, and a material in which these metals are dispersed in a resin may be used as the heat sink.
According to the fourth aspect of the present invention, after manufacturing a substrate incorporating each element and an optical waveguide substrate, inspecting each substrate to remove defective products, each substrate is multilayered using an insulating adhesive, and laminated. 4. The method for manufacturing a multilayer opto-electric hybrid board according to claim 1, further comprising a step of connecting between insulating adhesives using bumps formed on each of the substrates. is there.
[0018]
As described above, when laminating the substrates incorporating the respective elements, electrical connection can be simultaneously made by using the connection bumps, so that there is no need to separately provide a connection step, thereby simplifying the manufacturing steps and making it inexpensive. It is possible to do.
[0019]
Further, it is possible to mount a passive component or the like on a substrate having a built-in electric element, and then further stack a semiconductor package, which is suitable for manufacturing a high-density module.
[0020]
In addition, since the board containing each element is inspected before multi-layering, and a multi-layer opto-electric hybrid board can be assembled using a non-defective substrate that does not contain element defects, the overall yield can be improved. .
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory view showing a cross section of an embodiment of an opto-electric hybrid board according to the present invention. In the opto-electric hybrid multilayer substrate 1 of the present invention shown in the drawing, a substrate 10 on which an electric element 100 is mounted and a substrate 11 on which an optical element is mounted are formed by connecting bumps 101 formed on the respective substrates. It has a basic configuration connected between insulating adhesives 20 used for bonding. Light 2 input to the core layer of the waveguide substrate 12 is reflected by a mirror and input to the optical element 200 of the optical element built-in substrate 11.
[0022]
FIG. 2 is an explanatory view showing a cross section of another embodiment of the opto-electric hybrid board according to the present invention. This is an example in which a heat sink 21 is formed in the insulating adhesive 20 of the embodiment shown in FIG.
[0023]
FIG. 3 is an explanatory view showing an example of an embodiment of a method of manufacturing a device-embedded substrate according to the multilayer opto-electric hybrid board of the present invention in the order of steps in cross section.
[0024]
FIG. 4 is an explanatory diagram showing in cross section an example of an embodiment of the method for manufacturing a multilayer opto-electric hybrid board according to the present invention.
[0025]
FIG. 5 is an explanatory view showing an example of an embodiment of a method of manufacturing an optical waveguide substrate according to the multilayer opto-electric hybrid board of the present invention in the order of steps in cross section.
[0026]
【Example】
Hereinafter, embodiments of the present invention will be described.
《Method of manufacturing optical element embedded substrate and electric element embedded substrate》
As shown in FIG. 3A, a polyimide film (Upilex 75S: trade name, manufactured by Ube Industries) 501 having a thickness of 75 μm was prepared. A hole for forming a connection bump and a hole for mounting an optical element or an electric element were punched out using a mold, and unnecessary portions of the polyimide film were removed (FIG. 3B).
[0027]
Next, a copper foil 502 having a thickness of 18 μm was bonded to one surface of the polyimide film 501 (FIG. 3C). Thereafter, a 15 μm-thick photosensitive resist 503 is applied by a roll coating method (FIG. 3D), and after forming, a wiring layer having a predetermined pattern shape by patterning the copper foil 502 using a known photoetching method. Was formed [FIG. 3 (e)]. Thereafter, the resist pattern was stripped (FIG. 3 (f)). Again, a 15 μm-thick photosensitive resist is applied and formed by a roll coating method, and then a plating mask 506 is formed by a known photoetching method (FIG. 3G), and electrolytic copper using a known copper sulfate is used. After forming connection bumps 504: having a height of 100 μm by plating, the plating mask was stripped (FIG. 3 (h)). Next, the optical element 505 was mounted as shown in FIG. In the same process, an electric element built-in substrate 10 on which electric elements were mounted instead of optical elements was obtained.
[0028]
<< How to make an optical waveguide substrate >>
As shown in FIG. 5A, a silicon substrate 401 is prepared, a 10 μm-thick photosensitive resist 402 is applied and formed on the substrate 401 by spin coating, and then a predetermined pattern is formed using a known photo-etching method. Exposure, development [FIG. (B)], and etching to form a tapered step 403 on the surface of the silicon substrate [FIG. (C)]. Next, as shown in FIG. 5D, polyimide (OPI-N1005: trade name of Hitachi Chemical Co., Ltd.) was spin-coated as the cladding layer 301 and imidized in a nitrogen atmosphere at 350 ° C. At this time, the film thickness was 3 μm.
[0029]
Next, aluminum was vapor-deposited (FIG. 5E), a predetermined pattern was formed with a photoresist, and the micromirror 302 was formed by using a known photo-etching method, leaving the aluminum on the side surfaces of the above-described steps [FIG. (F)].
Further, polyimide (OPI-N1305: trade name of Hitachi Chemical Co., Ltd.) was similarly spin-coated as the core layer 300 and imidized in a nitrogen atmosphere at 350 ° C. The film thickness at this time was 8 μm [FIG. 5 (g)].
[0030]
Next, as shown in FIG. 5 (h), polyimide (OPI-N1005: trade name of Hitachi Chemical Co., Ltd.) was spin-coated as the cladding layer 301 and imidized in a nitrogen atmosphere at 350 ° C. At this time, the film thickness is 3 μm. The optical waveguide substrate 12 was obtained by the above steps.
[0031]
<< How to make a multilayer opto-electric hybrid board >>
As shown in FIG. 4, an electric element built-in substrate 10, an optical element built-in substrate 11, and an optical waveguide substrate 12 obtained by the above method are provided with an adhesive layer 20 (AS-2700: trade name, manufactured by Hitachi Chemical Co., Ltd.) between the substrates. Each substrate was laminated using a scissor vacuum lamination method to obtain a multilayer opto-electric hybrid board 1 shown in FIG.
[0032]
At this time, the layers were laminated so that the connection bumps of each substrate were electrically connected in the adhesive layer 20, and the optical waveguide and the optical element substrate were optically connected.
[0033]
As the adhesive layer used for lamination, a prepreg used in a lamination process of a printed wiring board is preferable, and the thickness and the number of prepregs according to the height of the connection bump protruding from the insulating resin layer Is desirably selected as appropriate.
[0034]
Furthermore, a device-embedded substrate provided with connection bumps may be prepared and laminated on the multilayer opto-electric hybrid board. As a manufacturing method, for example, in FIG. 4, connection bumps of the electric element built-in substrate 10 are formed on the upper and lower sides, and the element built-in substrate is further thermocompression-bonded using a vacuum laminator or the like, and laminated by an adhesive.
[0035]
Further, in the above embodiment, the heat sink layer may be laminated between the substrates with an adhesive layer interposed therebetween. In this case, as a manufacturing method, a copper foil having a connection portion opened in advance by punching or laser is prepared, and this is sandwiched between prepreg sheets. Alternatively, the connection portion of the copper foil with the adhesive is opened in advance, and the adhesive is again attached to the heat sink to mount the upper substrate.
[0036]
The embodiments of the present invention have been described above, but the present invention is not limited to the configurations and conditions described in the embodiments, and various modifications are possible.
For example, in the above embodiment, the bumps for performing the electrical connection are formed by electrolytic copper plating. However, if the respective substrates can be electrically connected, the bumps are formed by screen printing using a metal paste. Alternatively, a metal ball, a metal-coated ball, or the like may be embedded and used.
[0037]
In addition, in the above-described embodiment, the prepreg sheet is used for the bonding of the substrates, but the substrate has an insulating property, and if the substrates can be bonded to each other, dip using a varnish of an insulating adhesive. After being formed on a substrate using a known technique such as a coating method, a spin coating method, a roll coating method, or the like, they may be bonded together.
[0038]
【The invention's effect】
As described above, according to the present invention, a substrate having a built-in optical element and a substrate having a built-in electric element can be wired with a short electrical distance, and an external optical signal can be processed at a high speed. It is possible to provide a multilayer opto-electric hybrid board. Further, according to the present invention, the substrate on which each element is mounted and the waveguide substrate can be inspected before laminating them in multiple layers, so that the yield can be improved. That is, the defective products of each element and each substrate can be removed before lamination, so that the overall yield after lamination can be improved.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a cross section of an embodiment of an opto-electric hybrid board according to the present invention.
FIG. 2 is an explanatory view showing a cross section of another embodiment of the opto-electric hybrid board of the present invention.
FIG. 3 is an explanatory view showing an example of an embodiment of a method of manufacturing a device-embedded substrate according to the multilayer opto-electric hybrid board of the present invention in the order of steps in cross section.
FIG. 4 is an explanatory view showing in cross section an example of an embodiment of a method for manufacturing a multilayer opto-electric hybrid board of the present invention.
FIG. 5 is an explanatory view showing an example of an embodiment of a method of manufacturing an optical waveguide substrate according to the multilayer opto-electric hybrid board of the present invention in the order of steps in cross section.
[Explanation of symbols]
1: Optical hybrid board 2: Optical signal path 10: Electric element embedded substrate 11: Optical element embedded substrate 12: Waveguide substrate 20: Insulating adhesive 21: Heat sink 100: Electric element 101: Connection bump 102: Insulation Resin 200: Optical element 201: Connection bump 300: Core layer 301: Cladding layer 302: Micro mirror 401: Silicon substrate 402: Photosensitive resist 403: Step 501: Insulating resin 502: Copper foil 503: Photosensitive resist 504: Connection Bump 505: Optical or electrical element 505: Optical or electrical element 506: Plating mask

Claims (4)

A plurality of substrates including an electric element, a substrate including an optical element, and an optical waveguide substrate are laminated using an insulating adhesive, and electrical connections between the elements are formed on the substrate including the respective elements. A multilayer optical / electrical hybrid substrate, wherein the substrate and the optical waveguide are optically connected to each other and are connected in an insulating adhesive using an optical element. At least one of the boards containing the electric element is electrically connected to the board containing the optical element, and the board containing the electric element is connected electrically to the board containing the other element. 2. The multilayer opto-electric hybrid board according to claim 1, wherein 3. The multi-layer opto-electric hybrid board according to claim 1, wherein a heat sink layer is interposed between the boards in which the respective elements are incorporated. After fabricating the substrate incorporating each element and the optical waveguide substrate, removing each defective by inspecting each substrate, each substrate is multilayered using an insulating adhesive, and formed on each substrate at the time of lamination 4. The method for manufacturing a multilayer opto-electric hybrid board according to claim 1, further comprising a step of connecting between insulating adhesives using bumps.

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