JP4720713B2 - Optical module - Google Patents

Description

  The present invention relates to an optical module in which an optical device is mounted by a passive alignment method.

Conventionally, an active alignment method and a passive alignment method are known as methods for aligning optical coupling between an optical fiber and a semiconductor optical element (optical device).
The former active alignment method aligns while monitoring the output in order to determine the optimum positional relationship between the optical device and the optical fiber. The core diameter of the optical device such as a semiconductor laser or a photodiode is about 9 μm. It is suitable for optically coupling optical fibers with a precision of micron and submicron order.

  As an example of an optical module using a conventional active alignment method, Patent Document 1 discloses that the optical axis of an optical device mounted on a substrate with a flexible cable is substantially perpendicular to the end face of a ferrule in which an optical fiber is embedded. The optical module is characterized in that the light transmitted through the optical fiber with the end face of the optical device and the ferrule close to each other is directly coupled to the optical device. This optical module does not require an optical lens or the like, and the optical device and the ferrule are aligned by butting, so that the coupling efficiency can be increased.

  However, the active alignment method requires a considerable amount of time for detection of the maximum output and coupling, and the alignment device is also required to be highly accurate and expensive. Adhesion and welding are performed to fix the position after optical coupling alignment, but it is necessary to satisfy the requirements for ensuring mechanical strength and precision fixing. It was a thing.

On the other hand, the latter passive alignment method performs alignment by mechanical positioning without monitoring the output, and is suitable for automation. This passive alignment method can be mounted in a shorter time than the active alignment method.
In an optical module that optically couples an optical device and an optical fiber, it is required to reduce the manufacturing cost and the manufacturing equipment cost and to assemble efficiently. For this reason, the passive alignment method is becoming the mainstream of the alignment method for optical coupling instead of the active alignment method.

An example of a conventional optical module using a passive alignment method is disclosed in Patent Document 2. In the optical module described in Patent Document 2, a translucent resin film is laminated on a substrate piece having a through hole into which a ferrule embedded with an optical fiber is inserted, and the optical device has a translucent resin film on the through hole. By attaching a ferrule to the through hole, the light transmitted through the optical fiber is directly coupled to the optical device. Passive alignment is realized by flip-chip mounting the optical device with the through hole of the substrate piece serving as a guide for the ferrule as a reference.
JP 2004-341370 A JP 2004-361630 A

Since the optical module described in Patent Document 2 does not use an optical lens, similarly to the optical module described in Patent Document 1 using the active alignment method, the optical coupling rate can be increased. Further, since the optical device can be mounted in an array state, it is excellent in mass productivity.
However, in order to seal optical devices such as photodiodes, it is necessary to seal and protect with a sealing material using a technique such as transfer molding. Some difficulty remains.

  The present invention has been made in view of the above circumstances, and has a structure capable of coupling light transmitted through an optical fiber of an optical connector to an optical device with high coupling efficiency. From the mounting of the optical device to the sealing of the optical device. An object of the present invention is to provide an optical module having a structure capable of performing the above process in an array state.

In order to solve the above-described problems, an optical module of the present invention includes an optical device that is optically coupled to an optical fiber, and includes a sleeve that guides the ferrule of the optical connector, and one end inserted into the sleeve. A base plate comprising: a stub to be coupled; an optical fiber mounted at a central portion of the stub; a base plate that is fitted and fixed to the other end of the stub and holding a sleeve; and a sealing member that seals an open surface of the base plate. An electrical conductor path is formed on the open surface of the optical device, and the optical device and device circuit components that are optically coupled to the optical fiber mounted on the stub are mounted, and a sealing member connects the electrical conductor path and the external electrical circuit It has the connection part for this.

Na us, the sealing member may be configured to form a chip carrier type package.

In the optical module manufacturing method of the present invention, a base plate and a positioning jig each having a through-hole and a sealing member are formed in an array , and the through-hole is continuous with the base plate and the positioning jig. Fixing the stub into the through hole of the base plate and the positioning jig, fixing the stub and the base plate, and connecting the electric conductor path to the open surface of the base plate opposite to the positioning jig side. Forming the optical device and the device circuit component on the open surface side of the stub and electrically connecting to the electric conductor path, sealing the open surface of the base plate, and connecting the electric conductor path and the external electric circuit. a sealing member having a connecting portion for connecting, so that the connection portion and the external electric circuit can be connected, a step of sealing the optical device, Yusuke a step of cutting the assembly assembled up to the step of sealing the device into pieces, and removing the positioning jig, and attaching the sleeve to the portion that has been inserted into the positioning jig stub, the It is characterized by that.

According to the present invention, light from an optical fiber can be directly coupled to an optical device such as a photodiode, and the number of lenses can be reduced compared to an existing optical module, so that light can be coupled to an optical device with high optical coupling efficiency. it can. Moreover, the coupling of the optical fiber and the optical device can be carried out by passive alignment, and the investment for manufacturing equipment can be made inexpensive.
Furthermore, it can be mounted in an array state, and many optical modules can be manufactured at one time. In addition, the hermetic sealing process of optical devices and device circuit components can also be performed in an array state, and a highly reliable optical module can be manufactured.

Hereinafter, with reference to the drawings, embodiments of the present invention will be described using an example of using a photodiode (PD) as an optical device.
FIG. 1 is a diagram showing an example of an optical module of the present invention. The optical module of the present invention optically couples an optical fiber and an optical device. As shown, the optical module 1 includes, for example, a stub 2, a sleeve 3, a base plate 4, a lid plate 5, and an optical device 6. Prepare. In the following description, the side provided with the lid plate is the upper side of the optical module, and the side sealed by the lid plate on the upper surface of the base plate and the stub is the open surface.

  The stub 2 is composed of, for example, a zirconia capillary or a glass ceramic capillary, and has an optical fiber 2a at the center. The stub 2 is inserted into the sleeve 3 with the base plate 4 fitted and fixed at one end. In the example of FIG. 1, the upper surfaces of the stub 2 and the base plate 4 are continuous and flush with each other. On the upper surface (open surface) of the stub 2, an optical device (PD) 6 is mounted so that the light receiving surface of the PD 6 and the optical fiber 2a are optically coupled.

  The sleeve 3 has an optical connector ferrule (not shown) attached to the tip of the optical fiber cable and an insertion hole 3a into which the stub 2 is inserted. The sleeve 3 guides the insertion of the ferrule, abuts the stub 2 inserted in the sleeve, and optically connects the optical fiber (not shown) in the ferrule and the optical fiber 2a in the stub 2. . The sleeve 3 is bonded and fixed to the bottom surface side of the base plate 4.

  The base plate 4 has a through hole 4 a, and the upper end of the stub 2 is inserted into the through hole 4 a and is held and fixed to the stub 2. When the optical module of the present invention is configured as a light receiving module, for example, a TIA (Trans Impedance Amplifier) 7 which is a device circuit component is mounted on the upper surface of the base plate 4. Although not shown in FIG. 1, on the upper surface (open surface) of the base plate 4, there is formed an electric conductor path for supplying power and wiring for an electric yellow signal to the TIA 7 and the PD 6 mounted on the stub 2. (See, for example, FIG. 5).

  The lid plate 5 hermetically seals the PD 6 and the TIA 7 with the base plate 4 so that the optical module 1 can be connected to an external electric circuit. For this reason, the lid plate 5 is formed with a connecting portion 5a for electrically connecting the electric conductor path on the base plate 4 and the external electric circuit, for example, by metallization. The connecting portion 5 a is formed so as to reach the upper surface of the lid plate 5 from the portion of the lower bottom surface of the lid plate 5 facing the electric conductor path on the base plate 4 via the side surface of the lid plate 5. The electrical connection between the external electric circuit and the electric conductor path on the base plate 4 is, for example, by connecting the upper end surface of the connecting portion 5a of the lid plate 5 and a flexible circuit (FPC) board (for example, see FIG. 10) This is achieved by connecting the FPC board and an external electric circuit. Thus, the lid plate can take the form of a chip carrier type package having connection electrodes on its side surfaces.

  With the configuration as described above, in the optical module of the present invention, since the hermetically sealed optical device and the optical fiber are directly optically coupled without using a lens or the like, the optical module can be optically coupled with high optical coupling efficiency. it can.

Next, with reference to FIG. 2 to FIG. 10, each component of the optical module of the present invention will be described in more detail by explaining an example of the manufacturing method of the optical module of the present invention.
FIG. 2 is a diagram illustrating a pre-process for fixing the base plate and the stub. This pre-process is a process of fixing the base plate 4 to a stub positioning jig (hereinafter referred to as a positioning jig) 8 for positioning the stub, and FIG. 2 (A) shows a state before fixing. (B) shows the state after fixation.

  Through holes 4a and 8a for inserting stubs are formed in the base plate 4 and the positioning jig 8, respectively. The positioning jig 8 and the base plate 4 are attached so that both the through holes 4a and 8a coincide with each other. Fix it. As an adhesive for fixing, for example, it is conceivable to use an adhesive that can be peeled and dissolved with warm water or a special solvent. The through holes 4a and 8a may be formed by drilling after the base plate 4 and the positioning jig 8 are fixed. The through hole 4a of the base plate 4 is processed to have a clearance of about several μm with respect to the stub outer diameter (φ1.2485 to 1.2495 mm for the LC connector) because the stub needs to be accurately positioned. It is desirable. The base plate 4 is formed of an insulating material, and as the material, for example, a resin material having high heat resistance can be used in addition to ceramics and multicomponent glass.

  3A and 3B are diagrams for explaining a process of fixing the stub to the base plate. FIG. 3A shows a state before fixing, and FIGS. 3B and 3C show a state after fixing. In this step, first, the stub 2 is inserted into the through holes 4a and 8a of the base plate 4 and the positioning jig 8 (see FIGS. 3A and 3B). As shown in FIG. 3C, the stub 2 is inserted until the bottom surface of the stub 2 and the bottom surface of the positioning jig 8 coincide. Thereafter, an adhesive is applied to the joint between the base plate 4 and the stub 2, and the adhesive is inserted and fixed in the gap between the fitting portions by capillary action.

  By this step, the stub 2 is assembled so that the lower end thereof coincides with the lower end of the positioning jig 8. However, with respect to the upper surface of the stub 2, the end surface of the stub 2 may protrude from the upper surface of the base plate 4 as shown in FIGS. In addition, since the positioning jig 8 and the base plate 4 are peeled off in a later process, the adhesive is prevented from entering between the positioning jig 8 and the stub 2. It is preferable to process the inner diameter of the positioning jig 8 in advance so that the adhesive does not flow.

FIG. 4 is a diagram for explaining a stub polishing step, and FIGS. 4A and 4B both show a state after polishing.
Prior to the polishing step, for example, as shown in FIGS. 3B and 3C, the stub 2 is assembled so that the upper end of the stub 2 protrudes somewhat from the upper surface of the base plate 4. In this polishing step, the upper end portion of the stub 2 protruding from the upper surface of the base plate 4 is polished so that, for example, the state shown in FIGS. 4A and 4B is obtained, that is, the upper surface of the stub 2 and the upper surface of the base plate 4. To be flush with each other.
However, when the stub 2 is manufactured so that the length of the stub 2 and the thickness of the base plate 4 are equal, this polishing step can be omitted.

  FIG. 5 is a diagram illustrating a process of forming an electrical conductor path on the upper surface of the base plate, and shows a state where the electrical conductor path is formed. In this step, the electric conductor path 9 is formed on the upper surface of the base plate 4 by metallization. The electrical conductor path 9 is a PD or TIA power line, a signal line from the TIA, an electrode for flip-chip mounting the PD, or a signal line connecting the PD and TIA. Further, a marking (not shown) may be formed as a positioning mark when the PD is mounted by passive alignment.

  6A and 6B are diagrams for explaining a process of mounting the optical device and the device circuit component. FIG. 6A shows a state before mounting, and FIGS. 6B and 6C show states after mounting. . In the process shown in FIG. 6, the optical device or the like is mounted so that the state shown in FIGS. 6B and 6C is changed from the state shown in FIG. 6A where the optical device or the like is not mounted. That is, the device circuit component TIA 7 is mounted on the base plate 4 in a predetermined state, and the optical device PD 6 is mounted on the stub 2 in a predetermined state. This predetermined state depends on the positions of the electrodes 7 a and 6 a formed on the top surfaces of the TIA 7 and the PD 6 and the shape of the electric conductor path 9.

  6B and 6C show an example in which the light receiving surface of the PD 6 is coaxial with respect to the position of the optical fiber 2a of the stub 2. A back-illuminated PD is used as the PD 6 and the light receiving surface is mounted so as to face the stub 2. In order not to obstruct the light from the optical fiber 2a, a translucent adhesive material is used for mounting. The PD 6 is provided with an electrode 6a on the opposite surface facing the stub 2, and the electrode 6a is electrically connected to the electric conductor path 9 on the base plate 4 and the electrode 7a of the TIA 7 by wire bonding. The TIA 7 may be mounted by die bonding using silver paste or the like in addition to resin fixation. The TIA 7 and the electric conductor path 9 are also electrically connected by wire bonding.

  As another mounting method, the electric conductor path 9 is formed so as to extend to the vicinity of the optical fiber 2a of the stub 2, and the front-incident PD is flip-chip mounted so that the light receiving surface faces the stub 2. Also good. In this case, the optical fiber 2a of the stub 2 is positioned by passive alignment so that the light receiving surface of the PD is coaxial, but the end surface of the optical fiber 2a and the PD are close to each other. Can be received by the PD.

  In the case of flip chip mounting, an underfill may be applied to the gap between the PD and the stub 2 in order to relieve stress due to the difference in the linear expansion coefficient between the PD and the stub 2. The material used for the underfill needs to be translucent. By adopting a refractive index of the underfill substantially equal to that of the core of the optical fiber 2a, optical loss at the end face of the optical fiber 2a can be reduced, and PD (optical device) and optical fiber with high optical coupling efficiency. 2a can be combined.

  FIG. 7 is a diagram illustrating a process of hermetically sealing an optical device or the like. FIG. 7A shows a state before hermetic sealing, and FIGS. 7B and 7C show a state after hermetic sealing. In this step, the lid plate 5 which is a sealing member for hermetically sealing the optical device and the device circuit component and the above-described base plate 4 are bonded and fixed, and the PD 6 and the TIA 7 are hermetically sealed.

  The lid plate 5 is formed using, for example, an insulating material. For example, a resin material having high heat resistance can be used in addition to ceramics and multicomponent glass. As shown in FIGS. 7A and 7B, the lid plate 5 is formed with a connection portion 5 a that is electrically connected to an external electric circuit. The connection portion 5 a is formed on the side surface of the lid plate 5. It can be formed by metallizing into a predetermined shape so as to reach the lower surface. Further, as shown in FIG. 7C, the lid plate 5 is formed with a recess 5b. In the space formed between the recess 5b and the base plate 4 (and the stub 2), the PD 6 and TIA7 is accommodated and hermetically sealed.

  The adhesive fixing between the lid plate 5 and the base plate 4 in this hermetic sealing process will be described in more detail. The base plate 4 and the lid plate 5 are assembled so that the electrical conductor path 9 and the connecting portion 5a are electrically connected. For the connection between the electric conductor path 9 and the connecting portion 5a, a method of connecting electrodes by ultrasonic waves may be used in addition to a method of connecting by solder or silver paste. The portions other than the electric conductor path 9 and the connection portion 5a are bonded and fixed using an insulating adhesive having a low viscosity. These operations are preferably performed in a nitrogen atmosphere to hermetically seal the optical device or the like.

8A and 8B are diagrams for explaining a process of removing the stub positioning jig. FIG. 8A shows a state before removal, and FIGS. 8B and 8C show a state after removal.
In this step, the stub positioning jig 8 to which the base plate 4 is fixed is peeled off from the base plate 4 as shown in FIG. 8A, and the stub 2 is moved as shown in FIGS. 8B and 8C. Make it exposed to the outside. In addition to the stub positioning function during assembly (assembly), the positioning jig 8 can also serve as a protective component that prevents the lower end surface of the stub 2 from being contaminated during assembly (assembly). In that case, a protective plate for protecting the end surface of the stub 2 is attached below the positioning jig 8.

  FIG. 9 is a diagram illustrating a process of attaching a sleeve. In this step, the sleeve 3 that guides the ferrule of the optical connector is attached to the component assembled in the state shown in FIG. The stub 2 exposed to the outside by the removal of the stub positioning jig 8 is inserted into the insertion hole 3a of the sleeve 3 whose inner diameter is processed with high accuracy, and the bottom surface of the base plate 4 and the upper surface of the sleeve 3 are bonded and fixed. Thus, the optical module as shown in FIG. 1 is completed. A structure using a split sleeve and a sleeve shell instead of the sleeve 3 may be used. The split sleeve fulfills the positioning of the stub 2 and the ferrule described above, and the sleeve shell component that determines the outer shape does not require high-precision inner diameter processing, and the sleeve shell can be manufactured at low cost.

The optical module of the present invention may include, for example, an FPC board as a device for electrically connecting a device to which the optical module is attached and the optical module.
FIG. 10 is a diagram for explaining a process of attaching the FPC board. FIG. 10 (A) shows a state before attachment, and FIGS. 10 (B) and 10 (C) show states after attachment. In this step, the upper end of the connection portion 5a formed on the side surface of the lid plate 5 and a pad (not shown) provided on one end side of the FPC board 10 are solder-connected. Thereby, the optical module circuit formed on the base plate 4 and the FPC board 10 are electrically connected via the connection portion 5a. Then, the optical module 1 converts the optical signal received by the PD 6 through the optical fiber into an electrical signal by connecting the other end portion 10a of the FPC board 10 to a device to which the optical module is attached, and transmits the electrical signal. It becomes possible to do.

  In the manufacturing method of the optical module of the present invention described above, the steps described with reference to FIGS. 2 to 8 are performed by assembling the components (base plate and the like) of the array structure and mounting the optical device in the array state. Since it can, many optical modules can be manufactured at once. A method for manufacturing the optical module of the present invention with an array structure will be described below.

First, the base plate array in which the base plate is formed in an array is bonded and fixed to the stub positioning jig array in which the stub positioning jig is formed in an array. Next, similarly to the above-described method of manufacturing the optical modules one by one, the stub is inserted into each of the through holes of the base plate array (and the stub positioning jig array), and the stub is fixed to the base plate array. Thereafter, electric conductor paths are formed on the base plate array, PDs are mounted on the respective stubs, and TIAs are mounted in correspondence with the respective PDs.
The next process will be described with reference to FIG.

  FIG. 11 is a diagram for explaining one step in a method for manufacturing an optical module with an array structure. The base plate array 4 ′ shown in FIG. 11 is fixed on the stub positioning jig array 8 ′ by the steps so far, and an electric conductor path 9 is formed on the side opposite to the stub positioning jig array 8 ′ side. PD6 and TIA7 are mounted at predetermined positions. On the lead plate array 5 ', a connection portion 5a is formed in a penetrating state so as to be exposed on the upper and lower surfaces in a predetermined array arrangement.

  In the process described with reference to FIG. 11, the lid plate array 5 ′ in which the lid plate is formed in an array is bonded and fixed to the base plate array 4 ′, and the PD 6 and the TIA 7 are hermetically sealed with each lid plate. This hermetic sealing is performed by bonding the lid plate connecting portion 5a and the electric conductor path 9 so as to be electrically connected and bonding and fixing the other portions with an adhesive having a low viscosity. FIG. 11A shows a state before hermetic sealing, and FIG. 11B shows a state after hermetic sealing.

In the next step, the state shown in FIG. 11B is cut into individual pieces.
FIG. 12 is a diagram illustrating a state in which components assembled in an array state are cut. As shown in the drawing, the parts are cut so that the cylindrical part 5b formed on the lid plate array 5 ′ and having the connecting part 5a is cut from the center, thereby obtaining a rectangular assembly part 20. It is done. The rectangular assembly component 20 is further cut into individual pieces to obtain the one shown in FIG. These cuttings can be performed by a method using dicing or laser.

Subsequent steps are performed in the same manner as the above-described method of manufacturing the optical modules one by one, and finally an optical module as shown in FIG. 1 can be obtained.
As described above, in the method for manufacturing an optical module of the present invention, many steps can be performed in an array state, and many can be assembled at a time, so that cost reduction can be achieved.

  As mentioned above, although this invention was disclosed with reference to predetermined | prescribed embodiment, this embodiment is an illustration and does not limit this invention. The scope of the present invention is not limited to the embodiments disclosed in the present specification, but is defined by the scope of the claims, and includes all modifications within the meaning and scope equivalent to the scope of the claims.

It is a figure which shows an example of the optical module of this invention. It is a figure explaining the pre-process for fixing a baseplate and a stub. It is a figure explaining the process of fixing a stub to a baseplate. It is a figure explaining the grinding | polishing process of a stub. It is a figure explaining the process of forming an electrical conductor path on the base plate upper surface. It is a figure explaining the process of mounting an optical device and a device circuit component. It is a figure explaining the process of airtightly sealing an optical device etc. FIG. It is a figure explaining the process of removing a stub positioning jig. It is a figure explaining the process of mounting | wearing with a sleeve. It is a figure explaining the process of attaching an FPC board. It is a figure explaining 1 process in the method of manufacturing an optical module by an array structure. It is a figure which shows a mode when the components assembled in the array state are cut | disconnected.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical module, 2 ... Stub, 2a ... Optical fiber, 3 ... Sleeve, 3a ... Insertion hole, 4 ... Base plate, 4 '... Base plate array, 4a ... Through-hole, 5 ... Lid plate, 5' ... Lid plate array, 5a ... connecting portion, 5b ... cylindrical portion, 6 ... optical device (PD), 6a ... electrode, 7 ... TIA, 7a ... electrode, 8 ... stub positioning jig, 8 '... stub positioning jig array, 8a ... through hole , 9 ... Electrical conductor path, 10 ... FPC board, 10a ... End, 20 ... Assembly parts.

Claims (3)

An optical module on which an optical device optically coupled with an optical fiber is mounted,
A sleeve for guiding the ferrule of the optical connector;
A stub inserted into the sleeve and optically coupled to the ferrule;
An optical fiber mounted in the center of the stub;
A base plate that is fitted and fixed to the other end of the stub and holds the sleeve;
A sealing member for sealing the open surface of the base plate,
An electrical conductor path is formed on the open surface of the base plate, and the optical device and the device circuit component that are optically coupled to the optical fiber mounted on the stub are mounted .
The optical module according to claim 1, wherein the sealing member has a connection portion for connecting the electric conductor path and an external electric circuit . The optical module according to claim 1 , wherein the sealing member forms a chip carrier type package. It is a manufacturing method of the optical module according to claim 1 or 2 ,
A base plate and a positioning jig each having a through-hole, and the sealing member are formed in an array,
Fixing the base plate and the positioning jig such that the through holes are continuous with each other;
Inserting a stub into the through hole of the base plate and the positioning jig, and fixing the stub and the base plate;
And forming the electrical conductor to the open face opposite to the positioning jig side of the base plate,
A step of the optical device and the implement device circuitry, connected to said electrical conductor paths electrically to said open side of said stub,
Wherein a sealing member, so that the said connecting portion external electric circuit can be connected, a step of sealing the optical device,
Cutting the assembly assembled up to the step of sealing the optical device into pieces;
Removing the positioning jig;
Method of manufacturing an optical module according to claim Rukoto to have a, and attaching a sleeve inserted have a portion to the positioning jig of the stub.

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