JP4163909B2 - Optical module and optical module assembly using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technology relating to the mounting of a surface type optical semiconductor element such as a VCSEL (Vertical Cavity Surface Emitting Laser), a PIN type photodiode, or an avalanche photodiode, for example, for operating such a surface type optical semiconductor element. And an optical module assembly that is mounted on an external circuit board and can be assembled in a small size and with high reliability.
[0002]
[Prior art]
In recent years, large-capacity optical fiber communication has become widespread and developed in the fields of public communication and local area communication (LAN). As a result, the transmission speed has been increased, and high-speed optical transmission using optical fibers is required even at close distances of up to about 500 meters, and it has been used for optical transmission over a distance of several kilometers to several hundred kilometers conventionally used. In addition, the importance of very short distance (VSR) optical transmission and applications called Gigabit Ethernet (R) (GbE) are increasing. In these VSR and GbE applications, an optical transmission rate of 10 gigabits per second is being required. In such transmission, an unspecified number and a wide variety of uses are assumed. Miniaturization and improvement of mass productivity are considered industrially important.
[0003]
In conventional optical communication systems, 1.55 micron and 1.33 micron band semiconductor lasers with low optical fiber loss and dispersion have been widely used. However, in short-distance fields such as LANs, As a new optical semiconductor device having excellent characteristics and capable of high-speed optical transmission, a surface-type light emitting element called VCSEL of 0.85 micron band has been used. On the other hand, in the light receiving element, in order to electrically convert a high-speed optical signal as in the conventional case, a light receiving element such as a PIN type photodiode or an avalanche photodiode is used as the light receiving element of the VCSEL.
[0004]
In a LAN or the like using Gigabit Ethernet (R), for example, as disclosed in Japanese Patent Application Laid-Open No. 2000-214351, an optical transceiver in which a transmitter and a receiver are mounted in one package is generally used. The size is also standardized. In recent years, the downsizing of optical transceivers has progressed in order to reduce the size of the entire device, and has changed to a form called SFF (Small Form Factor), which is about half the size of the conventional one. In general, these planar optical semiconductor elements are accommodated in a cylindrical casing formed of a metal casing called a TO-CAN package and lead pins, and are formed into an optical module, and an electronic circuit on which an electronic circuit for controlling the optical module is mounted. Used by being fixedly mounted on a circuit board.
[0005]
[Problems to be solved by the invention]
However, in the conventional TO-CAN type optical module package, when the electronic module is mounted on the electronic circuit board on which the electronic circuit is mounted with the lead pin of the optical module package, the lead pin is in the air between the optical module package and the electronic circuit board. Since wiring is performed, discontinuity in the characteristic impedance of the wiring greatly occurs, resulting in deterioration of high frequency characteristics.
[0006]
In order to solve this problem, it is conceivable to shorten the lead pin as much as possible and mount it on an electronic circuit board so that the lead pin is not exposed to the air. It is difficult to ensure period reliability, and the high frequency characteristics are not stable due to variations in the lead pin length and the amount of solder when the optical module is mounted and fixed, resulting in poor mass productivity. Furthermore, since the TO-CAN type optical module package is standardized to φ5.6 mm, further miniaturization is difficult.
[0007]
In addition, since the lead pins are arranged concentrically from the center of the package, in order to mount on the electronic circuit board, the pins are bent in the middle of the lead pins, holes are made in the electronic circuit board, the lead pins are inserted, and soldering is performed. It was a structure with poor mass productivity that was not suitable for the electronic component mounting process.
[0008]
Therefore, the present invention has been proposed in view of the above-described problems, and is particularly suitable for mounting of a planar optical semiconductor element, and is excellent in mass productivity, small in size, high in frequency characteristics and reliable. An object of the present invention is to provide an optical module assembly using the same.
[0009]
[Problems to be solved by the invention]
In order to achieve the above object, an optical module of the present invention has a planar optical semiconductor element disposed on a substrate on which a wiring for energizing the planar optical semiconductor element is formed. The optical waveguide to be connected is attached, and an external wiring for energizing the surface type optical semiconductor element is formed on the surface of the substrate excluding the arrangement surface of the surface type optical semiconductor element and its back surface. fixed to an external circuit board, and a wiring formed on the external circuit formed external wiring substrate and the base body to allow electrical connection, the surfaces were provided with surface optical semiconductor element of the substrate, wherein It is made of a metal for supporting the optical waveguide and is provided with a support that surrounds the planar optical semiconductor element .
[0010]
Further, in the above-described configuration, it is preferable that an internal wiring that can electrically connect the planar optical semiconductor element and an external wiring formed on the external circuit board is formed in the base. In addition, a support made of a metal for supporting the optical waveguide may be provided on the surface of the base on which the surface type optical semiconductor element is disposed.
[0011]
The optical waveguide includes an optical fiber and a ferrule that holds the optical fiber.
[0012]
The optical module assembly of the present invention is characterized in that any one of the above optical modules is mounted on the external circuit board via solder.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of an optical module of the present invention and an optical module assembly using the optical module will be described in detail with reference to the drawings schematically showing the embodiments.
[0014]
1 is a perspective view of an optical module M1 according to the present invention, FIG. 2 is an exploded perspective view of the optical module M1, and FIG. 3 is a diagram for explaining a wiring structure and the like in a base 1 portion constituting the optical module M1 according to the present invention. 4 is a perspective view showing a VCSEL 2 which is a surface type optical semiconductor element constituting the optical module M1, FIG. 5 is a perspective view showing a state of a base 1 part constituting the optical module M1, and FIG. 6 is a perspective view in FIG. It is sectional drawing cut | disconnected by the surface containing the optical axis of the optical waveguide body which comprises the optical module M1.
[0015]
The optical module M1 of the present invention includes an optical waveguide (mainly an optical fiber 42 and an optical fiber 42) optically connected to the VCSEL 2 on the VCSEL 2 arrangement surface 16 side of the base 1 on which the VCSEL 2 is arranged and wiring for energizing the VCSEL 2 is formed. It is made up of a ferrule 41 that accommodates and holds this. Then, an external circuit (not shown) in which external wiring for energizing the VCSEL 2 is formed on the surface excluding the VCSEL 2 arrangement surface 16 and the back surface 20 of the base 1, that is, any one of the side surfaces of the base 1. The external wiring formed on the external circuit board and the wiring formed on the base 1 can be electrically connected to each other by being fixed to the substrate.
[0016]
Further, as will be described later, internal wirings (12b, 13b, 13c, 12c, 13d) are formed in the base 1 so that the VCSEL 2 and the external wiring formed on the external circuit board can be electrically connected. ing. Further, the base body 1 has a support 16 made of a metal for supporting the optical waveguide on the surface 16 on which the VCSEL 2 is disposed, that is, a metal fitting 17, a first metal protector 4, and a second metal protector. A body 9 is provided. Here, in the drawing, lead electrodes 14, 15a, and 15b having a coplanar structure are provided on a surface 30 (a mounting surface of the optical module on the external circuit substrate) 30 of the base 1 that is fixed to the external circuit substrate. Instead of the lead electrode, a terminal electrode group composed of a plurality of grid-like terminal electrodes may be formed in at least three regions. The terminal electrode group is formed along the optical axis direction of the optical waveguide.
[0017]
Specifically, as shown in the figure, in the optical module M1, the VCSEL 2 is arranged on one main surface 16 of the substrate 1 which is an optical component mounting substrate, and the VCSEL 2 is enclosed on the same main surface 16 of the substrate 1. An annular metal fitting 17 is provided, and a spherically formed lens 34 is closed in an upper opening of the metal fitting 17, and the metal annular body 3 provided with the lens 34 in the center is attached to the metal fitting 17. A first metal protector 4 that is disposed on the metal fitting 17 and covers the upper part of the metal annular body 3 so as to cover the upper part of the metal annular body 3 is formed on the one end side. 4a is disposed on the base 1 side. Further, in the same manner as the first metal protector 4, an optical fiber 42 that is optically connected to the VCSEL 2 is disposed inside a second metal protector 9 that is cylindrical and has a flange 9 a formed at one end. A columnar ferrule 41 is accommodated, and the second metal protector 9 is accommodated in the first metal protector 4. As described above, the first and second metal protectors 4 and 9 are provided with the flange portions 4a and 9a so that an optical connector receptacle (not shown) can be fitted.
[0018]
In the base 1, electrode patterns 12 a and 13 a for transmitting electrical signals to the VCSEL 2 are formed on the arrangement surface 16 of the VCSEL 2. The electrode patterns 12 a and 13 a are electrically connected by via conductors 12 b, 13 b and 13 c of internal wiring formed inside the substrate 1. Furthermore, lead electrodes 14, 15a and 15b, which are external pads for electrical connection to the outside, are provided on the surface 30 which is the lower surface side when the substrate 1 is erected, and are electrically connected to each of these lead electrodes. External conductive patterns 18 and 19 are formed on a surface 30 on the side of the substrate 1 on the external circuit board. The external conductive patterns 18 and 19 are connected to internal conductor patterns 12c and 13d formed inside the base 1, respectively. The internal conductor patterns 12c and 13d are connected to the via conductors 12b, 13b and 13c, respectively. It is connected to the.
[0019]
The electrode patterns 12a, 13a, the via conductors 12b, 13b, 13c, the internal conductor patterns 12c, 13d, and the like are high-frequency lines for transmitting an electrical signal of 10 Gbps. In particular, the electrode patterns 12a, 13a, the internal conductor pattern 12c, 13d is a coplanar electric wiring whose impedance is matched to 25Ω or 50Ω, and the lead electrodes 14, 15a and 15b are formed in a grid array in which three electrodes of a ground electrode, a signal electrode, and a ground electrode are arranged. A coplanar electrode is preferable, and the high-speed transmission of 10 Gbps can be achieved with this configuration.
[0020]
Here, instead of the lead electrodes 14, 15 a, 15 b, by using a ball-shaped grid array to which solder balls are added, the convenience in mounting the optical module M <b> 1 can be further improved.
[0021]
The substrate 1 has a multilayer wiring structure in which ceramic materials such as alumina and aluminum nitride are laminated. The electrode patterns 12a and 13a and the internal conductor patterns 12c and 13d are made of any one of Au, Ni, W, and the like. A conductor thick film including at least is formed by printing or the like, or made of metallization such as Cu, and the via conductors 12b, 13b, and 13c are made of W or the like.
[0022]
The metal fitting 17 is made of Kovar or the like, and is brazed to the base 1. Furthermore, the metal annular body 3 provided with the lens 34 made of Kovar, stainless steel or the like is easily hermetically sealed by resistance welding or the like to the metal fitting 17 after the VCSEL 2 is mounted. Thereby, VCSEL2 can be protected for a long lifetime.
[0023]
The VCSEL 2 includes an active layer 21 which is a light emitting portion on the surface, and electrodes 22, 23 a and 23 b made of Ti / Pt / Au metal or the like in the lower layer / upper layer in order to apply an electric signal to the active layer 21, and the VCSEL 2 Alignment markers 24a and 24b made of Au metal or the like used for mounting on the substrate 1 are formed.
[0024]
In the VCSEL 2, the active layer 21 is mounted on the optical semiconductor element arrangement surface 16 of the base 1 on the upper surface. The electrodes 22, 23a, and 23b of the VCSEL 2 are electrically connected to electrode patterns 12a and 13b that are coplanar electric wirings of the substrate 1 through ribbons 31, 32, and 33 such as Au ribbons. Thereby, an optical signal can be generated from the active layer 21 by inputting an electric signal to the lead electrodes 14, 15 a, 15 b which are coplanar electrodes of the substrate 1.
[0025]
The first metal protectors 4 and 9 are made of Kovar or stainless steel.
[0026]
In this embodiment, the light emitting module using the VCSEL has been described. However, it is also possible to function as a light receiving module by using a light receiving semiconductor element such as a PIN photodiode or an avalanche photodiode as a planar optical semiconductor element. it can.
[0027]
Thus, according to the optical module M1 of this embodiment, the optical waveguide that is optically connected to the VCSEL 2 is attached to the base 1 on which the VCSEL 2 is provided, and the VCSEL 2 mounting surface 16 and the back surface 20 of the base 1 are connected. The surface to be removed is fixed to an external circuit board on which external wiring for energizing the VCSEL 2 is formed, and the external wiring formed on the external circuit board and the wiring formed on the base 1 can be electrically connected. Therefore, a simple configuration can be obtained, the assembly is simplified, and good optical connection can be efficiently performed.
[0028]
In particular, since the internal wiring (12b, 13b, 13c, 12c, 13d) that allows the VCSEL 2 and the external wiring formed on the external circuit board to be electrically connected is provided in the base 1, the electrical wiring is shortened. It is possible to reduce the electrical transmission loss and to generate and receive an optical signal capable of high output and high speed transmission.
[0029]
Further, in particular, on the surface 16 on which the VCSEL 2 of the substrate 1 is disposed, a support (metal fitting 17, metal annular body 3, metal support for the optical waveguide (the optical fiber 42 and the ferrule 41 that accommodates the optical waveguide)) is formed. Since the first metal protector 4 and the second metal protector 9) are provided, the optical waveguide can be metal-welded, and a structure capable of easily obtaining highly reliable and highly efficient optical coupling characteristics is obtained. Therefore, stable light emitting and receiving characteristics can be obtained over a long period of time.
[0030]
In particular, by forming a terminal electrode group composed of lead electrodes (14, 15a, 15b) and a plurality of terminal electrodes arranged in a grid on the surface fixed to the external circuit board of the substrate 1 in at least three regions. A coplanar high-frequency electrode structure of ground (for grounding), signal (for signal), and ground (for grounding) can be obtained, and high-speed optical transmission characteristics exceeding 10 Gbps can be easily obtained. Furthermore, by forming the lead electrode and the terminal electrode group along the optical axis direction of the optical waveguide, the external circuit board surface for mounting the optical module and the position for emitting and receiving the optical signal are made the same plane. Therefore, a small and low-profile optical module can be obtained.
[0031]
In addition, since the optical waveguide includes an optical fiber and a ferrule that holds the optical fiber, a receptacle structure that can be attached and detached by an optical connector can be easily obtained, and the operability of the optical module is excellent.
[0032]
Next, the optical module assembly will be described. As shown in FIG. 7, the optical module assembly includes a light emitting module T in which a VCSEL is mounted as a planar optical semiconductor element on one end side of a mounting substrate 8 that is an external circuit board, and a PIN photodiode as a planar optical semiconductor element. A driver IC 5 for driving the light emitting module T, a TIA (transimpedance amplifier) 6 for amplifying and shaping the electric signal obtained from the light receiving module R, and a capacitor And a mounting substrate 8 on which an additional electronic device 7 such as a resistor is mounted.
[0033]
In this way, by adopting a structure in which the electrodes are arranged in parallel with the optical axes of the light emitting module T and the light receiving module R, solder such as cream solder is applied in advance to the mounting electrodes of the mounting base 8, and the light emitting module T In addition, by arranging the light receiving module R, the electronic device 7, the driver IC 5, the TIA 6, and the like, a solder reflow process of about 260 ° C. can be performed, and the optical module assembly that is mounted and fixed in a lump is completed.
[0034]
Further, by forming a gap 10 (space) between the optical module and the mounting substrate 8, it is not necessary to form an insulating layer in the gap 10 to perform impedance matching.
[0035]
Here, as shown in FIG. 8, the step portion 11 is formed on the base 1 of the optical module M2, and the external electrode pad 82 for connecting the step portion 11 is substantially parallel to the optical axis and is an external circuit board. The mounting surface of the mounting substrate 81 and the optical axis can be placed in a horizontal position by being disposed substantially horizontally with respect to the mounting substrate 81 and at one end of the mounting substrate 81 on which the electronic device 71 and the control IC 61 are mounted. In addition, an optical module assembly with a lower profile can be provided.
[0036]
As described above, according to the optical module assembly of the present embodiment, the optical module can be automatically assembled to the external circuit board together with the additional electronic circuit by solder reflow or the like, which is excellent in mass productivity and consequently. An inexpensive optical module assembly can be provided.
[0037]
【The invention's effect】
According to the optical module and the optical module assembly of the present invention, the following remarkable effects can be obtained.
[0038]
According to the optical module of claim 1, an optical waveguide optically connected to the planar optical semiconductor element is attached to the substrate on which the planar optical semiconductor element is disposed and wiring for energizing the planar optical semiconductor element is formed. The surface excluding the surface and the back surface of the planar optical semiconductor element is fixed to an external circuit board on which external wiring for energizing the planar optical semiconductor element is formed, and formed on the external circuit board Since the external wiring and the wiring formed on the substrate can be electrically connected to each other, a simple configuration can be obtained, the assembly is simplified, and good optical connection can be efficiently performed.
[0039]
According to the optical module of the second aspect, the internal wiring that enables the electrical connection between the planar optical semiconductor element and the external wiring formed on the external circuit board is formed in the base. Therefore, it is possible to reduce the electric transmission loss and to generate and receive an optical signal that can be transmitted at high power and at high speed.
[0040]
According to the optical module of the third aspect, since the support body made of metal for supporting the optical waveguide is provided on the surface of the base on which the surface type optical semiconductor element is disposed, the optical waveguide is metal-welded here. Therefore, it is possible to easily obtain a highly reliable and highly efficient optical coupling characteristic, and to obtain a stable light emitting / receiving characteristic over a long period of time.
[0041]
According to the optical module of the fourth aspect, since the optical waveguide includes an optical fiber and a ferrule that holds the optical fiber, a receptacle structure that can be attached and detached by an optical connector can be easily obtained, and the operability of the optical module is improved. Excellent.
[0042]
According to the optical module assembly of claim 5, the optical module can be automatically assembled to the external circuit board together with the additional electronic circuit by solder reflow or the like, and is excellent in mass productivity and consequently inexpensive. A module assembly can be provided.
[Brief description of the drawings]
FIG. 1 is a perspective view schematically illustrating an embodiment of an optical module according to the present invention.
2 is an exploded perspective view of the optical module in FIG. 1. FIG.
3 is a perspective view for explaining a wiring structure or the like in a base portion constituting the optical module in FIG. 1. FIG.
4 is a perspective view of a planar optical semiconductor element constituting the optical module in FIG. 1. FIG.
5 is a perspective view of a base portion constituting the optical module in FIG. 1. FIG.
6 is a view for explaining the optical module in FIG. 1, and is a cross-sectional view cut along a plane including an optical axis of an optical waveguide constituting the optical module. FIG.
FIG. 7 is a perspective view schematically illustrating an embodiment of an optical module assembly according to the present invention.
FIG. 8 is a side view schematically illustrating another embodiment of the optical module assembly according to the present invention.
[Explanation of symbols]
1: Substrate 2: VCSEL (Surface type optical semiconductor element)
3: Lens 4: First metal protector (constituting support)
5: Driver IC
6: TIA
7, 71: Electronic device 8, 81: Mounting substrate (external circuit board)
9: Second metal protector (constructs a support)
12-13, 18, 19: Electric wiring 12b, 13b, 13c: Internal wiring 14-15, 82: External electrode pad (lead electrode)
16: Arrangement surface 17 of the surface type optical semiconductor element 17: Metal fitting (constituting support)
20: Back surface 21: Active layers 22-23: Electrode pattern 24: Alignment marker 30: Mounting surface 31-33 on optical circuit board of optical module Ribbon 41: Ferrule (configures optical waveguide)
42: Optical fiber (constructs an optical waveguide)
61: Control IC
M1, M2: Optical module R: Light receiving module (optical module)
T: Light emitting module (optical module)

Claims (4)

An optical waveguide that is optically connected to the planar optical semiconductor element is attached to a substrate on which a planar optical semiconductor element is disposed and wiring for energizing the planar optical semiconductor element is formed. The surface excluding the surface-type optical semiconductor element mounting surface and its back surface is fixed to an external circuit board on which external wiring for energizing the surface-type optical semiconductor element is formed, and is formed on the external circuit board To be able to electrically connect external wiring and wiring formed on the base,
A light having a support made of a metal for supporting the optical waveguide and surrounding a side portion of the planar optical semiconductor element is provided on a surface of the substrate on which the planar optical semiconductor element is disposed. module. 2. The optical module according to claim 1, wherein an internal wiring capable of electrically connecting the planar optical semiconductor element and an external wiring formed on the external circuit board is formed in the base. 3. The optical module according to claim 1, wherein the optical waveguide includes an optical fiber and a ferrule that holds the optical fiber. The optical module according to any one of claims 1 to 3, wherein the optical module assembly, characterized in that it is implemented via a solder to an external circuit board.

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