JP3964835B2 - Three-dimensional wiring board and optical semiconductor module - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical semiconductor device used for an optical communication technology, an optical transmission technology, an optical information recording technology, and the like, and more particularly to a three-dimensional wiring board and an optical semiconductor module in which electric wiring is improved.
[0002]
[Prior art]
In recent years, in optical communication, optical transmission, optical information recording technology, and the like, it has been widely performed to transmit a signal by intensity modulation or phase modulation using light as a carrier wave. Among them, by using a light emitting diode or a semiconductor laser as a light source and an optical semiconductor element such as a photodiode as a light receiving element, it is possible to reduce the size and weight of the entire apparatus.
[0003]
In addition, since a wideband signal can be transmitted by performing high-speed modulation, high-speed information processing is possible, and broadband and moving image recording are also possible. However, the signal transmission bandwidth of the current technology is not always sufficient, and higher throughput is required from the trunk line to terminals or consumer products, and at the same time, low-cost technology is essential for the spread. .
[0004]
As a method of optically coupling an optical transmission line with an optical semiconductor element that inputs / outputs light in the direction perpendicular to the mounting surface, the optical coupling method by directly facing each other can shorten the coupling distance. Is a method that can provide a simple, low-cost structure. In this case, the optical axis direction of the optical fiber is substantially perpendicular to the optical element mounting substrate.
[0005]
On the other hand, when a module is configured, the module mounting surface (board) is arranged in parallel with other boards and is so-called rack-mounted, and therefore the mounting volume is smaller when the distance between the boards is close. Therefore, there is a demand to arrange the optical fiber in a direction parallel to the board surface on which the module is mounted, rather than the form in which the optical fiber protrudes vertically from the mounting board. In order to satisfy this requirement, the optical element mounting substrate and the mounting surface (mounting base material surface) of the optical fiber holding member need to be three-dimensionally wired.
[0006]
Conventionally, there are various methods such as an example in which a thick film extending over two surfaces of a ceramic substrate is provided and a flexible wiring board is used in order to perform three-dimensional right-angle wiring. However, if the wiring pattern is miniaturized and the speed is increased and the control of the shape of the electrical connection portion becomes important, the application becomes difficult in terms of pattern accuracy. In addition, since the electrodes are also required on the side surfaces, it is necessary to manufacture them individually, and mass production is difficult.
[0007]
Therefore, recently, a method has been proposed in which the mounting surface of the optical semiconductor element and the mounting substrate surface are arranged orthogonally, and then three-dimensionally wired by wire bonding (see, for example, Patent Document 1). This method has a feature that the wiring length can be shortened because the electrode pad on the mounting surface and the electrode on the mounting substrate surface are connected by a wire. In addition, there is a method for realizing three-dimensional wiring by forming a slope on the substrate and forming a part of the electrical wiring on the slope and then facing another substrate similarly provided with the slope wiring (for example, patents) Reference 2). In this case, since a highly accurate wiring is formed and combined in substantially the same manner as a plane, it can be applied to fine patterns and high-speed wiring. Moreover, since the wafer process can be applied, it is suitable for mass production.
[0008]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-162004
[Patent Document 2]
Japanese Patent Laid-Open No. 2002-299743
[Problems to be solved by the invention]
However, the above documents have the following problems. In the method of Patent Document 1, since wire bonding can be performed only on a flat surface, after bonding one end of the wire, it is necessary to rotate the bonding tool or the substrate 90 ° to bond the other wire end. It is necessary for a long time and the mounting cost tends to increase. In addition, the positioning of the rotating system is likely to take a long time, and it is necessary to rotate the wire while one of the wires is connected. Therefore, the shape that can be bonded is limited. There is.
[0011]
Further, in the method of Patent Document 2, both the pair of substrates need to be processed, and the wiring length to the edge portion is necessary, so that the wiring length tends to be long. In addition, when connecting the facing wirings, the solder material or the adhesive may be crushed, resulting in a short circuit between the adjacent wirings, and there is a problem that adjustment is required at the time of assembly and the process cost increases. Similarly, since the shape of the joint depends on the conditions during assembly and adjustment of the pressure, further fine adjustment may be necessary to obtain the desired shape, which increases the mounting cost. was there.
[0012]
The present invention has been made in consideration of the above-described circumstances, and the object of the present invention is to mount the electrical wiring of the wiring board vertically mounted on the mounting board without requiring wire bonding. An object of the present invention is to provide a three-dimensional wiring board that can be electrically connected to the upper electric wiring and can easily realize three-dimensional wiring, and an optical semiconductor module using the same.
[0013]
[Means for Solving the Problems]
(Constitution)
In order to solve the above problems, the present invention adopts the following configuration.
[0014]
That is, the present invention relates to a three-dimensional wiring board, a substrate, an insulating layer provided on one main surface of the substrate, and provided on the insulating layer, one end side being in close contact with the insulating layer and the other end side being the insulating layer. It is characterized by comprising a plurality of electrical wirings formed apart from each other and an insulating support provided so as to mechanically connect the other end sides of the respective electrical wirings.
[0015]
Here, preferred embodiments of the present invention include the following.
[0016]
(1) The other end side of the electrical wiring rises substantially perpendicular to one main surface of the substrate and is mechanically connected by the insulating support at a location away from the substrate.
[0017]
(2) A bump for bonding is formed on the other side of the electrical wiring on the side opposite to the surface where the insulating support is connected.
[0018]
(3) An optical semiconductor element is mounted on one main surface of the substrate.
[0019]
In the present invention, an insulating layer is formed on one main surface of the substrate, and a plurality of electrical wirings are formed on the insulating layer such that one end side is in close contact with the insulating layer and the other end side is separated from the insulating layer. A three-dimensional wiring board provided with an insulating support so as to mechanically connect the other end of each electric wiring, an optical semiconductor element mounted on the three-dimensional wiring board, and the three-dimensional wiring board perpendicular to the main surface And a mounting substrate provided with an optical transmission line and an external connection electrical wiring that are mounted on the main surface and optically coupled to the active region of the optical semiconductor element on the main surface, and an optical semiconductor module comprising: The other end side of the electrical wiring of the three-dimensional wiring board rises substantially perpendicular to one main surface of the board and is electrically connected to the external connection electrical wiring.
[0020]
Here, preferred embodiments of the present invention include the following.
[0021]
(1) A through hole is provided in a part of the substrate on the three-dimensional wiring board side at a position corresponding to the active region of the optical semiconductor element, and the active region of the optical semiconductor element and the optical transmission line are optically coupled through the through hole. To be done.
[0022]
(2) The other end of the electrical wiring shall be directly connected to the external connection electrical wiring.
[0023]
(3) The other end side of the electrical wiring is connected to other semiconductor elements mounted on the mounting substrate and indirectly connected to the external connection electrical wiring.
[0024]
(Function)
According to the present invention, when the other end side of the electric wiring on the three-dimensional wiring board side is floated from the insulating layer and formed, for example, substantially perpendicular to the main surface of the board, the three-dimensional wiring board is mounted vertically on the mounting board. The other end side of the electrical wiring of the three-dimensional wiring board can be directly connected to the external connection wiring on the mounting board and other semiconductor elements. That is, three-dimensionally perpendicular wiring can be applied without requiring wire bonding or the like, and three-dimensionally upright wiring is formed in the state of the substrate. Accordingly, since it is possible to deal with substantially only by planar mounting, it is possible to simplify the process and realize a structure capable of manufacturing a substrate at low cost using a wafer process.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
The details of the present invention will be described below with reference to the illustrated embodiments.
[0026]
(First embodiment)
FIG. 1 is a perspective view showing a schematic configuration of a three-dimensional wiring board according to the first embodiment of the present invention.
[0027]
In the figure, reference numeral 10 denotes a wiring board on which an optical semiconductor element or the like is mounted, and an insulating layer 11 is formed on the surface (one main surface) of the wiring board 10. On the surface of the insulating layer 11, a plurality of electrical wirings 12 made of a metal material are formed. Each electrical wiring 12 has a structure in which one end side 12-1 is in close contact with the surface of the insulating layer 11 and the other end side 12-2 is floated from the insulating layer 11.
[0028]
A portion 12-2 that floats from the insulating layer 11 stands up from the substrate 10 in a substantially vertical direction. An insulating support 13 is provided on a part of the portion 12-2 floating from the insulating layer 11 so as to extend over the plurality of electric wires 12, and the electric wires 12 are mechanically connected to each other by the insulating support 13. Yes. This insulating support 13 has the effect of aligning the pitch of each electrical wiring 12. With this structure, a plurality of integrated wiring structures that rise almost vertically from the substrate 10 can be obtained.
[0029]
With such a configuration, for example, as shown in FIG. 2, even when the LSI 14 mounted on the mounting substrate 16 and the wiring substrate 10 are arranged three-dimensionally orthogonally, using a normal bonder, Multiple wires can be connected at a short distance. Note that reference numeral 15 in FIG. 2 denotes an electrode pad of the LSI 14 and is electrically connected to the electric wiring 12.
[0030]
The structure of the present embodiment can be realized as follows. Here, as shown in FIG. 3A, the wafers are not formed on a chip basis, but are collectively formed on a silicon wafer in a wafer state. 3 (b) and 3 (c) show enlarged details.
[0031]
First, as shown in FIG. 3B, a wiring substrate 10 made of silicon or the like and having various wirings formed on the surface is prepared. An insulating layer 11 made of an oxide film or the like as a protective film is formed on the surface (one main surface) of the wiring board 10. Then, a polysilicon layer 18 serving as a sacrificial layer is formed on part of the insulating layer 11. Next, it is made of, for example, a metal such as gold, titanium, platinum, nickel, aluminum, copper or a multilayer metal made of a plurality of combinations so that a part thereof adheres to the insulating layer 11 and a part thereof covers the polysilicon layer 18. A plurality of electrical wirings 12 are formed. Thereafter, an insulating film (insulating support) 13 is formed so as to extend over the plurality of electric wirings 12. At this time, the sputtering conditions and the like are adjusted so that the tensile stress in the normal direction increases from the surface in close contact with the wafer.
[0032]
Next, as shown in FIG. 3B, the sacrificial layer 18 is etched with KOH or the like and removed, whereby a part of the electric wiring 12 is floated from the insulating layer 11. At this time, warping occurs due to the residual stress, and a part of the electric wiring 12 rises. Since this rising amount is determined by the stress distribution, it can be designed according to sputtering conditions, metal type, and the like. It is also possible to control the stress using a metal multi-layer structure. Finally, it is separated into pieces by dicing or the like. In this way, since the wafer process can be applied, mass production is possible, and manufacturing is possible at low cost.
[0033]
As described above, according to the present embodiment, the electrical wiring 12 of the wiring substrate 10 mounted vertically on the mounting substrate 16 can be electrically connected to the electrode pads 15 of the LSI 14 on the mounting substrate 16 without the need for wire bonding. Therefore, the three-dimensional wiring can be easily realized.
[0034]
In this case, unlike the method of wire bonding, it is not necessary to rotate the bonding tool or the substrate, and the tact time can be shortened to prevent an increase in mounting cost. Furthermore, since the wiring routing becomes unnecessary, the wiring length can be shortened.
[0035]
(Second Embodiment)
4A and 4B are diagrams for explaining a schematic configuration of a three-dimensional wiring board according to the second embodiment of the present invention. FIG. 4A is a cross-sectional view, and FIG. 4B is a perspective view. The insulating layer 21 is formed on the surface (one main surface) of the wiring substrate 20, and a plurality of electrical wirings 22 are formed on the surface of the insulating layer 21. Each electric wiring 22 has a structure in which one end side is in close contact with the surface of the insulating layer 21 and the other end side is floated from the insulating layer 21. A portion floating from the insulating layer 21 stands up from the substrate 10 in a substantially vertical direction. A part of the portion floating from the substrate 10 is connected by an insulating support 23 so as to straddle a plurality of electric wirings.
[0036]
Bumps 24 for bonding are formed on the side opposite to the insulating support 23 in the vicinity of the end on the floating side of the electrical wiring 22. By this bump 24, it is possible to more stably connect to an LSI or an external connection wiring. The bumps 24 are made of, for example, Au or a solder alloy, and are provided separately for each wiring. In the realization method, the bump metal may be formed on the sacrificial layer 18 before the electric wiring is formed in the step shown in FIG. 2A, and the others can be manufactured in the same manner as in the first embodiment.
[0037]
(Third embodiment)
FIG. 5 is a sectional view showing a schematic configuration of an optical semiconductor module according to the third embodiment of the present invention.
[0038]
As the three-dimensional wiring board, the one having the structure shown in FIG. 4 was used.
[0039]
On the surface (main surface) of the mounting substrate 34, the optical transmission path holding member 33 and the LSI 35 are mounted together with the wiring substrate 20. An optical transmission path 32 such as an optical fiber is fixed on the optical transmission path holding member 33 in the substrate plane direction. The LSI 35 is connected to an external connection wiring 38 to which data signals, control signals, power supply, and the like are supplied.
[0040]
The wiring board 20 stands vertically to the mounting board 34 and is electrically connected to the LSI 35 by the bumps 24. On the other hand, an optical semiconductor element 31 is mounted on one main surface of the wiring board 20 by flip chip mounting or the like, and the optical semiconductor element 31 is electrically connected to the electrical wiring 22. The wiring board 20 is provided with a through hole 36 at a position corresponding to the input / output light of the optical semiconductor element 31, and light from the optical semiconductor element 31 is input / output through the wiring board 20, and the optical transmission path 32. And optically coupled.
[0041]
In the figure, reference numeral 37 denotes a package sealing member, which is installed for the purpose of protecting the optical module. Reference numeral 39 denotes an electrode pad provided on the surface of the LSI 35. A part of the optical transmission path 32 penetrates the package sealing member 37 and is led out of the package, and a part of the external connection wiring 38 is also led out of the package.
[0042]
With such a structure, the optical transmission line 34 arranged in the substrate plane direction of the optical semiconductor element 31 provided on the outside air plate and the mounting substrate 34 with respect to the three-dimensional wiring substrate mounted vertically on the mounting substrate 34. Can be optically coupled. In this case, since the electrical wiring 22 of the three-dimensional wiring board and the electrode bump 39 on the LSI 35 can be directly connected, the wiring length from the optical semiconductor element 31 to the LSI 35 can be extremely shortened. In addition, a connection that does not require the supply of a new connection member from the outside, such as a bonding wire, is possible, and since it can be manufactured only by planar mounting, a low-cost optical module capable of high-speed operation can be manufactured. .
[0043]
(Modification)
In addition, this invention is not limited to each embodiment mentioned above. In the embodiment, the other end side of the electrical wiring on the wiring board is raised substantially perpendicular to the board surface, but it is not always necessary to bend it vertically, and in short, it can be connected to wiring or bumps on the mounting board. Bend to the extent. Furthermore, although the electrical wiring is connected to the semiconductor element on the mounting substrate, it is needless to say that it may be directly connected to the external connection wiring on the mounting substrate.
[0044]
Further, the manufacturing method of the three-dimensional wiring board is not limited to the example shown in FIG. 3. One end side of the electric wiring on the wiring board is closely attached to the insulating layer, and the other end side is separated from the insulating layer. Any method can be used as long as it can be formed. In addition, various modifications can be made without departing from the scope of the present invention.
[0045]
【The invention's effect】
As described above in detail, according to the present invention, one end side of the plurality of electric wirings on the wiring board is formed in close contact with the insulating layer and the other end side is formed apart from the insulating layer. By adopting a configuration in which the end side is mechanically connected by an insulating support, the electric wiring of the wiring board mounted vertically on the mounting board can be connected to the electric wiring on the mounting board without requiring wire bonding. Electrical connection can be achieved, and three-dimensional wiring can be easily realized.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a schematic configuration of a three-dimensional wiring board according to a first embodiment.
2 is a cross-sectional view showing a configuration of an optical semiconductor module on which the three-dimensional wiring board of FIG. 1 is mounted.
FIG. 3 is a cross-sectional view showing a manufacturing process of the three-dimensional wiring board in the first embodiment.
FIG. 4 is a perspective view showing a schematic configuration of a three-dimensional wiring board according to a second embodiment.
FIG. 5 is a cross-sectional view showing a schematic configuration of an optical semiconductor module according to a third embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10,20 ... Wiring board | substrate 11,21 ... Insulating layer 12,22 ... Electric wiring 13,23 ... Insulating film (insulation support body)
14, 35 ... LSI
DESCRIPTION OF SYMBOLS 15 ... Pad 16, 34 ... Mounting board 18 ... Sacrificial layer 24 ... Bump 31 ... Optical semiconductor element 32 ... Optical transmission path 33 ... Optical transmission path holding member 37 ... Package sealing member 38 ... External connection wiring 39 ... Electrode pad

Claims (5)

A substrate,
An insulating layer provided on one main surface of the substrate;
A plurality of electrical wirings provided on the insulating layer, wherein one end side is in close contact with the insulating layer and the other end side is spaced apart from the insulating layer;
An insulating support provided so as to mechanically connect the other end of each electrical wiring;
A three-dimensional wiring board comprising: 2. The other end side of the electrical wiring rises substantially perpendicular to one main surface of the substrate and is mechanically connected by the insulating support at a location away from the substrate. Three-dimensional wiring board. 3. The three-dimensional wiring board according to claim 1, wherein a bonding bump is formed on the other side of the electrical wiring on the side opposite to the surface where the insulating support is connected. The three-dimensional wiring board according to claim 1, wherein an optical semiconductor element is mounted on one main surface of the substrate. 5. The three-dimensional wiring board according to claim 4, and the optical transmission line and the external connection electric wiring, wherein the three-dimensional wiring board is vertically mounted on the main surface, and is optically coupled to the active region of the optical semiconductor element on the main surface. An optical semiconductor module comprising: a mounting substrate provided with:
The other end side of the electrical wiring of the three-dimensional wiring board rises substantially perpendicular to one main surface of the substrate and is electrically connected to the external connection electrical wiring.

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