JP4850148B2 - Optical module - Google Patents

Description

The present invention relates to an optical module .

  In recent years, it has become important to economically manufacture parts for optical communication systems, and in particular, cost reduction of long wavelength laser modules has been demanded.

The present inventors have proposed an optical transmission medium with an optical element that can be expected to be applied to various uses such as an optical module (see Patent Document 1). In this optical transmission medium with an optical element, an adhesive is attached to an end face of an optical transmission medium such as an optical fiber, and an optical element is attached to the end face, thereby providing a self-alignment effect, that is, the optical element's own weight and the surface tension of the adhesive. Thus, the optical element moves by itself to coincide with the center position of the optical transmission medium, thereby easily realizing highly accurate alignment of the optical axis.
Japanese Patent Laid-Open No. 2007-17808

  However, a specific configuration of an optical module using the optical transmission medium with an optical element has not yet been proposed, and can be easily and inexpensively manufactured by appropriately using the optical transmission medium with an optical element. The realization of a highly reliable optical module has been desired.

  The present invention has been made in view of the circumstances as described above, and it is an object of the present invention to provide a highly reliable optical module that is easy to connect optically and electrically and can be manufactured at low cost. Yes.

  The present invention is characterized by the following in order to solve the above problems.

First, the optical module of the present invention, the end face of the optical transmission medium, the center of the optical element coincides with the center of the optical transmission medium, the back electrode of the optical element is the optical element so as to be exposed to the outside comprising an optical element with optical transmission medium which is fixed with an adhesive, the optical element and a wiring substrate provided with the driver integrated circuit device is mounted for optical element driving, which is electrically connected through the back electrode, said driver The integrated circuit device is mounted on a flexible substrate disposed on a rigid substrate, and the optical element of the optical transmission medium with an optical element has an electrode on the bent surface of the flexible substrate. Are connected to the driver integrated circuit device so that the back surface of the optical element is perpendicular to the electric wiring surface of the rigid substrate, and the flexible substrate is connected to the BGA. Ri, characterized in that attached to the rigid substrate.

Second, in the first optical module, an end of the optical transmission medium is inserted into a ferrule, and the adhesive attached to the end surface of the ferrule on the outer periphery of the optical transmission medium and the optical transmission medium The optical element is fixed .

According to the present invention, optical connection requiring high alignment accuracy can be easily performed by matching the center of the optical element with the center of the optical transmission medium by the weight of the optical element and the surface tension of the adhesive. Since the optical transmission medium with the optical element that has completed the optical connection is electrically connected to the driver integrated circuit device mounted on the wiring board through the back electrode of the optical element, the optical transmission medium with the optical element is It can be easily electrically connected to the driver integrated circuit device. Therefore, an inexpensive optical module with high reliability of optical connection and electrical connection is provided.
Further , according to the present invention, optical connection requiring high alignment accuracy can be easily performed by matching the center of the optical element with the center of the optical transmission medium by the weight of the optical element and the surface tension of the adhesive. Since the optical transmission medium with the optical element that has completed this optical connection is connected to the flexible board on which the driver integrated circuit device is mounted, which is disposed on the rigid board, through the back electrode of the optical element. The optical transmission medium with an element can be easily electrically connected to the driver integrated circuit device. Therefore, an inexpensive optical module with high reliability of optical connection and electrical connection is provided.
Further , according to the present invention, the optical transmission medium with an optical element can be connected so that the optical wiring of the optical transmission medium with the optical element and the electric wiring surface of the rigid substrate are on the same plane.
Furthermore, according to the present invention, by inserting the end of the optical transmission medium into the ferrule, the center of the optical element can be accurately aligned with the center of the optical transmission medium by the weight of the optical element and the surface tension of the adhesive. The reliability of the optical module can be increased.

  In the present invention, the “optical transmission medium” includes glass or resin optical fibers, optical waveguides, optical waveguides, and the like. In the following embodiment, an example using an optical fiber will be described. However, the optical transmission medium applied in the present invention is not limited to this, and various types of optical transmission lines can be applied. . A plurality of optical transmission media may be arranged.

  The optical element used in the present invention includes various light emitting / receiving elements having electrodes provided in the form of bumps or the like on the back surface. Specific examples thereof include a vertical cavity surface-emitting laser (VCSEL) in which both anode and cathode electrodes are provided on the back surface of the light emitting surface, a surface light emitting device such as a light emitting diode, and a light receiving surface. Examples thereof include a surface light receiving element such as a photodiode having both anode and cathode electrodes on the back surface. Alternatively, a plurality of optical elements arranged in an array may be used.

  As the optical transmission medium with an optical element used in the present invention, for example, various media described in JP-A-2007-17808 can be used. The optical transmission medium with an optical element used in the present invention has a self-alignment effect, that is, an optical element's own weight and adhesion by attaching an adhesive to the end face of the optical transmission medium such as an optical fiber and attaching the optical element thereto. The optical element moves by itself due to the surface tension of the agent to coincide with the center position of the optical transmission medium, thereby aligning the optical axis.

  In the present invention, various materials can be used without particular limitation as long as they can be obtained by the above-described action. As an adhesive, for example, a Newtonian fluid or a fluid close thereto is used at the time of alignment of an optical element. Thus, the self-alignment effect can be easily achieved by using a material having an appropriate viscosity. For example, a hydrophilic adhesive, a hydrophobic adhesive, a thermosetting adhesive, a photocurable adhesive, a hot melt adhesive, or the like can be used.

  The mode of attaching the adhesive to the end face of the optical transmission medium in a substantially hemispherical shape is not particularly limited. For example, the optical transmission medium is provided with appropriate hydrophilicity or hydrophobicity in the core, cladding, and adhesive to transmit the optical transmission medium. Examples include an aspect in which an adhesive is attached only to the core of the medium, an aspect in which an adhesive is attached to the entire end surface of the optical transmission medium, or the entire end surface of the ferrule provided on the outer periphery of the end of the optical transmission medium and the optical transmission medium. It is done.

  There is no particular limitation on the method of attaching an adhesive to the end face of the optical transmission medium in a substantially hemispherical shape, and attaching and fixing the optical element thereto. For example, a method of attaching the adhesive by dip coating; A method of attaching an adhesive by attaching; using a mold having an opening having substantially the same shape as the end face of the optical transmission medium formed on the surface of the adhesive-repelling property, and attaching the end face of the optical transmission medium to the opening. Place the adhesive on this formwork by spin coating, roll coating, brush coating, mask printing, etc., and adhesive the adhesive on the surface of the formwork from the opening to the end face of the optical transmission medium And then remove the formwork; after applying a hot melt adhesive to the end face of the optical transmission medium to temporarily fix the optical transmission medium and the optical element, the viscosity is reduced by heating, and self-strength due to surface tension. Araime A method of aligning by applying the effect of light; using a photocurable resin as an adhesive, an adhesive of a photocurable resin by exposure from an optical transmission medium or from both an optical transmission medium and an optical element The light guide core is self-formed, and then the entire adhesive is irradiated with the clad forming light and cured to form a clad portion around the light guide core; Using a resin that is a mixture of a refractive index photocurable resin and a low refractive index thermosetting resin as an adhesive, the light for core formation at a certain wavelength is first transmitted to this mixed resin adhesive. By irradiating from one or both of the medium and the optical element, the high refractive index resin in the mixed resin is cured to form the light guide core by exposure, and then the entire adhesive is heated to Cured with low refractive index resin And a method for forming a tract clad and the like.

  As the optical transmission medium, a single-core type or a multi-core type may be used. In this case, a multi-channel optical element corresponding to a multi-core fiber is used, and each core and each light receiving and emitting point are connected. An optical transmission medium with an optical element can be produced by matching with the above method. Alternatively, transmission media with optical elements that are produced one by one may be arranged and fixed in an arbitrary arrangement such as one-dimensional or two-dimensional.

  A multicore polymer waveguide may be used as the optical transmission medium. Since the polymer waveguide can form a plurality of waveguides at the same time, it is preferable in the case of a multi-core.

  Further, as an optical transmission medium with an optical element, a ferrule made of zirconia ceramics, plastic, glass, or the like, or a ferrule for MT (Mechanically Transferable) connector may be used. FIG. 1 shows an example using an optical transmission medium with a ferrule made of zirconia ceramics. In the optical transmission medium 2 with an optical element, a ferrule 4 having a diameter of 2.5 mm is attached to the outer periphery of an end portion of an optical fiber 3 that is an optical transmission medium. A tapered surface is formed so that the end surface diameter is 2 mm. A hardened adhesive 8 is disposed on the entire end face 5 of the optical fiber 3 and the ferrule 4, and an optical axis is attached to the optical fiber 7 by a self-alignment effect at a lower end portion of the adhesive 8 separated from the end face 5 by about 300 μm. Is fixed with the light receiving / emitting surface facing the optical fiber 3 side. On the back surface of the optical element 6, a back electrode 7 is provided with a distance between pads of about 300 μm.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. 2A and 2B are diagrams showing a schematic configuration of an optical module in a reference example . FIG. 2A shows a state before connection of an optical transmission medium with an optical element, and FIG. 2B shows optical transmission with an optical element. The state which connected the medium and completed the optical module is shown. The optical module 1 of this reference example includes an optical transmission medium 2 with an optical element, and a wiring board 30 on which a package 10 containing a driver integrated circuit device 20 for driving the optical element is mounted.

  In the optical transmission medium 2 with an optical element, the optical element 6 is fixed to the end face of the optical fiber 3 having the ferrule 4 attached to the outer periphery with an adhesive 8, and the center of the optical element 6 is the center of the optical fiber 3. These bumps are arranged so that the bumps constituting the back electrode 7 of the optical element 6 are exposed to the outside.

  A package 10, which is a ceramic BGA (Ball Grid Array) package, is electrically connected to the wiring board 30 by soldering ball terminals on the lower surface of the package 10 and pad electrodes on the wiring board 30. Yes.

  Note that the connection method of the package 10 to the wiring board 30 may be an electrical connector connection, a socket connection, or the like.

  A driver integrated circuit device 20 is housed in the package 10, and an electrode 11 electrically connected to the driver integrated circuit device 20 is provided on a side surface of the package 10.

  When the optical module 1 is manufactured, the back electrode 7 of the optical element 6 of the optical transmission medium 2 with the optical element that is manufactured in advance is connected to the electrode 11 on the side surface of the package 10 by a method such as soldering. For soldering, for example, laser soldering capable of local heating can be applied.

  Thus, since the optical connection requiring high alignment accuracy has already been completed, the back surface electrode 7 of the optical element 6 of the optical transmission medium 2 with the optical element is connected to the electrode 11 of the package 10 so that the optical element is attached. The optical transmission medium 2 can be easily electrically connected to the driver integrated circuit device 20.

  Further, since the back electrode 7 of the optical element 6 of the optical transmission medium 2 with the optical element is connected to the electrode 11 on the side surface of the package 10, the optical wiring of the optical transmission medium 2 with optical element and the electrical wiring of the wiring substrate 30 are provided. The optical transmission medium 2 with an optical element can be connected so that the planes are on the same plane.

  After connecting the optical transmission medium 2 with an optical element to the package 10, the package 10 and the optical transmission medium 2 with an optical element 2 are integrally sealed with a sealing material 12 as shown in FIG. Since the optical element 6 is sealed with the adhesive 8, a resin sealing material containing a filler generally used as a sealing material can be used. In addition, the driver integrated circuit device 20 can be hermetically sealed, whereby the reliability of the optical module 1 can be further improved.

FIG. 3 is a diagram showing a schematic configuration of an optical module according to an embodiment of the present invention. In the optical module 1 of the present embodiment, the driver integrated circuit device 20 for driving the optical element is mounted on a flexible substrate 32. The flexible substrate 32 is formed on a rigid substrate 31 that is a wiring substrate on the lower surface of the flexible substrate 32. The ball terminal and the pad electrode on the rigid substrate 31 are electrically connected by soldering.

  In addition, the connection method of the flexible substrate 32 to the rigid substrate 31 includes connection by an electrical connector, wire bonding, an anisotropic conductive film, an anisotropic conductive adhesive, a conductive adhesive, or a socket. Also good.

  In the optical transmission medium 2 with an optical element, the optical element 6 is fixed to the end face of the optical fiber 3 having the ferrule 4 attached to the outer periphery with an adhesive 8, and the center of the optical element 6 is the center of the optical fiber 3. These bumps are arranged so that the bumps constituting the back electrode 7 of the optical element 6 are exposed to the outside.

  The optical transmission medium 2 with an optical element is prepared by soldering the back electrode 7 of the optical element 6 of the optical transmission medium 2 with an optical element, which is prepared in advance, to the electrode on the folded back surface 34 of the flexible substrate 32. By connecting, the driver integrated circuit device 20 is electrically connected so that the back surface of the optical element 6 is perpendicular to the electric wiring surface of the rigid substrate 31. As the flexible substrate 32, a substrate in which the electrical wiring on the front surface is electrically connected to the electrode on the back surface 34 through a through hole penetrating the substrate is used.

  Thus, since the optical connection requiring high alignment accuracy has already been completed, the optical transmission with the optical element can be performed by connecting the back electrode 7 of the optical element 6 of the optical transmission medium 2 with the optical element to the flexible substrate 32. The medium 2 can be easily electrically connected to the driver integrated circuit device 20.

  Further, since the back electrode 7 of the optical element 6 of the optical transmission medium 2 with the optical element is connected to the electrode on the bent back surface of the flexible substrate 32, the optical wiring and the rigid substrate of the optical transmission medium 2 with the optical element are connected. The optical transmission medium with optical elements 2 can be connected so that the electrical wiring surface 31 is on the same plane.

FIG. 4 is a diagram showing a schematic configuration of an optical module in another reference example . In the optical module 1 of this embodiment, a driver integrated circuit device 20 for driving an optical element is mounted on a flexible substrate 32 of a rigid flexible substrate 33 that is a wiring substrate, and the driver integrated circuit is mounted on the rigid substrate 31. An LSI (Large Scale Integration) device 21 that transmits and receives electrical signals to and from the device 20 is mounted.

  The rigid flexible substrate 33 is formed by connecting a rigid substrate 31 made of a hard material such as glass epoxy and a flexible substrate 32 using a flexible and bendable material so as to form the same surface. A generally used one can be used.

  In the optical transmission medium 2 with an optical element, the optical element 6 is fixed to the end face of the optical fiber 3 having the ferrule 4 attached to the outer periphery with an adhesive 8, and the center of the optical element 6 is the center of the optical fiber 3. These bumps are arranged so that the bumps constituting the back electrode 7 of the optical element 6 are exposed to the outside.

  In the optical transmission medium 2 with an optical element, the back electrode 7 of the optical element 6 of the optical transmission medium 2 with the optical element prepared in advance is connected to the electrode on the bent surface of the flexible substrate 32 by a method such as soldering. As a result, the back surface of the optical element 6 is electrically connected to the driver integrated circuit device 20 so as to be perpendicular to the electric wiring surface of the rigid flexible substrate 33. 4A shows a case where the back electrode 7 of the optical element 6 is connected to an electrode on the back surface 34 that is bent above the flexible substrate 32, and FIG. 4B shows the back electrode 7 of the optical element 6. Is connected to the electrode on the surface 35 bent below the flexible substrate 32. As shown in FIG. 4A, when the back electrode 7 of the optical element 6 is connected to the electrode on the back surface 34 bent above the flexible substrate 32, the flexible substrate 32 has a surface through a through hole penetrating the substrate. The electrical wiring is electrically connected to the electrode on the back surface 34.

  Thus, since the optical connection requiring high alignment accuracy has already been completed, the optical transmission with the optical element can be performed by connecting the back electrode 7 of the optical element 6 of the optical transmission medium 2 with the optical element to the flexible substrate 32. The medium 2 can be easily electrically connected to the driver integrated circuit device 20.

  Since the back electrode 7 of the optical element 6 of the optical transmission medium 2 with the optical element is connected to the electrode on the bent surface of the flexible substrate 32, the optical wiring and the rigid substrate of the optical transmission medium 2 with the optical element are connected. The optical transmission medium 2 with an optical element can be connected so that the electrical wiring surface 31 is on the same plane, and the optical transmission medium 2 with an optical element can be connected to the end face of the rigid flexible substrate 33. .

Although the combination of the rigid substrate and the flexible substrate has been described above, the rigid substrate or the flexible substrate can be used alone. 5 (a) is also shows a schematic configuration of an optical module according to another reference example, FIG. 5 (b) is a diagram showing a schematic configuration of an optical module in still another reference example, Fig. 5 In the optical module 1 of FIG. 2A, the driver integrated circuit device 20 is mounted on a flexible substrate 32, and the back surface electrode 7 of the optical element 6 of the optical transmission medium 2 with an optical element is an electrode on the flexible substrate 32. Is electrically connected to the driver integrated circuit device 20. 5B, the driver integrated circuit device 20 is mounted on a rigid substrate 31, and the back surface electrode 7 of the optical element 6 of the optical transmission medium 2 with an optical element is a rigid substrate. It is electrically connected to the driver integrated circuit device 20 by being connected to the electrode on 31.

  Even with this configuration, the optical transmission medium 2 with an optical element that has already been optically connected can be easily electrically connected to the driver integrated circuit device 20, and the reliability of the optical connection and the electrical connection can be improved. A high-priced and inexpensive optical module can be obtained.

  Further, as shown in FIGS. 5A and 5B, after the optical transmission medium 2 with the optical element is connected, the driver integrated circuit device 20 and the optical transmission medium 2 with the optical element are integrated with the sealing material 12. Seal. Since the optical element 6 is sealed with the adhesive 8, a resin sealing material containing a filler generally used as the sealing material 12 can be used. In addition, the driver integrated circuit device 20 can be hermetically sealed, whereby the reliability of the optical module 1 can be further improved.

  The present invention has been described above based on the embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

It is the figure which showed the optical transmission medium which attached the ferrule. It is the figure which showed schematic structure of the optical module in the reference example of this invention. It is the figure which showed schematic structure of the optical module in one Embodiment of this invention. It is the figure which showed schematic structure of the optical module in another reference example . FIG. 5A is a diagram illustrating a schematic configuration of an optical module in still another reference example , and FIG. 5B is a diagram illustrating a schematic configuration of the optical module in still another reference example .

DESCRIPTION OF SYMBOLS 1 Optical module 2 Optical transmission medium with an optical element 3 Optical fiber 4 Ferrule 5 End face 6 Optical element 7 Back surface electrode 8 Adhesive 10 Package 11 Electrode 12 Sealing material 20 Driver integrated circuit device 21 LSI device 30 Wiring board 31 Rigid board 32 Flexible Substrate 33 Rigid flexible substrate 34 Folded back surface 35 Folded surface

Claims (2)

The end face of the optical transmission medium, the center of the optical element coincides with the center of the optical transmission medium, a fixed optical element with optical transmission back electrode of the optical element in the optical element is adhesive so as to be exposed to the outside with medium and, and a wiring substrate provided with the driver integrated circuit device is mounted for optical element driving the optical element is electrically connected through the back electrode,
The driver integrated circuit device is mounted on a flexible substrate disposed on a rigid substrate, and the optical element of the optical transmission medium with an optical element has the back electrode on the folded surface of the flexible substrate. Is connected to the electrode, and is electrically connected to the driver integrated circuit device such that the back surface of the optical element is perpendicular to the electric wiring surface of the rigid substrate,
The optical module, wherein the flexible substrate is attached to the rigid substrate by BGA . An end portion of the optical transmission medium is inserted into a ferrule, and the optical element is fixed to an adhesive attached to the end surface of the ferrule on the outer peripheral portion of the optical transmission medium and the optical transmission medium. The optical module according to claim 1.

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