JP2001318283A - Optical module - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To prevent breakage of an optical fiber as much as possible with a simple configuration, to accurately connect an optical fiber to an optical element, to achieve miniaturization, and to achieve long-term reliability. To provide an optical module that can withstand high speed. SOLUTION: An optical fiber 2, an optical semiconductor element 1 to be optically connected to the optical fiber 2, a first base 3 provided with a conductor connected to the optical semiconductor element 1, and the first base 3 are placed. An optical module M comprising: a second substrate 5 provided with a conductor for supplying electricity to the conductor, wherein at least a gap between the optical fiber 2 and the optical semiconductor element 1 is sealed with a moisture-resistant transparent resin; and Transparent resin 17 should be at least opaque resin 1
8 coated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical module used for transmitting and receiving optical transmission such as optical fiber communication and optical interconnection.

[0002]

2. Description of the Related Art In recent years, in an optical module used for transmitting and receiving an optical signal, a metal electrode for power supply of an optical semiconductor element or the like has been proposed in order to simplify the component structure and reduce the cost and to improve the assemblability thereof. A mounting substrate in which V-grooves for fixing optical fibers are precisely formed is used.

Conventionally, a condensing lens has been used to connect an optical semiconductor element and an optical fiber in order to obtain a desired coupling efficiency. However, by fixing the two to a precision-processed mounting substrate. The optical semiconductor element and the optical fiber can be arranged very close to each other, and the condenser lens can at least obtain a desired coupling efficiency.

In the case of an optical coupling system using a mounting substrate, an optical fiber to be optically connected to an optical semiconductor element is pulled out to a housing as it is, and a gap between the optical fiber and a hole formed in a package through which the optical fiber is inserted is sealed by some method. I have to stop.

For example, in a conventional optical package J shown in the drawing, a notch 81 formed on the upper surface of a package 71 is provided.
An optical fiber 82 partially covered with a protective coating 83 and a glass pipe groove 78 covering the protective coating 83 are provided in the pipe groove 75 and a semiconductor laser 72 as an optical semiconductor element on the mounting substrate 80. Is fixed and the optical fiber 8
2 and the semiconductor laser 72 are optically connected.

Then, on the upper surface of the package 71,
After the sealing metal plate 77 and the lid 85 are sealed, the loss (not shown) of the low melting point glass disposed in the notch 81 is heated and melted to realize an airtight structure. In order to heat the low melting point glass, it has been proposed to perform partial heating by means such as a CO 2 (carbon dioxide gas) laser (for example,
See JP-A-7-63957).

In an optical coupling system between an optical element and an optical fiber, an optically transparent gel resin having a refractive index higher than that of air and lower than that of the optical fiber is filled, and moisture around the gel resin is passed through. There has been proposed an airtight sealing structure covered with a resin (see, for example, JP-A-10-227953).

In an optical module used for transmitting and receiving an optical signal, in order to ensure stable operation, a temperature rise due to heat generation of an optical semiconductor element or an electronic circuit is suppressed, and the temperature of the optical semiconductor element is lowered. And must be kept constant.

For example, in the optical module K shown in FIG.
A semiconductor laser 5 as an optical semiconductor element in a package 51;
A substrate 53 on which the circuit 2 is mounted and a substrate 55 on which the drive circuit 54 is mounted are mounted, respectively, and an optical fiber 56 is optically coupled to the semiconductor laser 52 via a lens 57.
The semiconductor laser 52 includes electrodes 58, 5 formed on a substrate 53.
9 and a driving circuit 54 mounted on a substrate 55 via a bonding wire 60 and driven (see Japanese Patent Laid-Open No.
The above driving circuit generates a current for driving and controlling the semiconductor laser, so that the driving circuit becomes high temperature and generates heat. Similarly, when a current is injected and light is output to the semiconductor laser, the heat generated by the drive circuit causes the semiconductor laser to further generate heat, which causes a change in the oscillation wavelength and a decrease in the optical output, thereby causing a failure of the semiconductor laser. In the optical module J, in order to solve this problem, a semiconductor laser and a substrate on which a drive circuit is mounted are separated.

[0010]

However, the structure of the optical module J shown in FIG. 6 employs a structure in which the optical fiber 82 and the glass pipe 78 attached thereto are disposed in the package 71. In a commonly used multilayer ceramic package, since a manufacturing method of laminating thin plates is used, a notch 81 in which an optical fiber 82 is provided and a pipe groove 7 in which a glass pipe 78 is provided.
The central axis of 5 is largely shifted with respect to the package 71.

A semiconductor laser 7 is provided in a package 71.
2 and the mounting substrate 80 on which the optical fiber 82 is mounted, the V-groove 86 formed on the mounting substrate 80 is notched in the V-groove 86 by a fixing method based on the outer shape.
The positional relationship between the central axis of the first and the central axis of the V-groove 86 is greatly shifted. That is, a mounting substrate such as silicon is generally formed with a V-groove by etching a wafer of several inches in size,
Although the substrate is divided into individual substrates by dicing, it is difficult to process the outer shape with high precision based on the V-groove by such a dicing method.

Therefore, when the optical fiber is mounted on the basis of the V groove, the positional relationship between the notch of the package, the pipe groove, and the V groove is largely displaced, and the optical fiber and the axis of the ferrule mounted on the optical fiber are not fixed linearly. . This allows
There is a serious problem that unnecessary bending, so-called microbending, occurs in the optical fiber and the optical module breaks from the bending position due to an environmental change.

In order to prevent the micro-bend, it is conceivable to precisely position the shaft with respect to the notch 81 and the pipe groove 75 by cutting the optical fiber and the ferrule. In addition, it is necessary to easily provide a complicated and high-performance device for performing surface treatment on the optical fiber itself and positioning the axis. This is a problem because the assembly of the optical module becomes complicated.

As another means for preventing the micro-bend, a configuration in which a V-groove for mounting an optical fiber on a silicon substrate and a V-groove for mounting and fixing a ferrule are preliminarily formed may be considered. The width of the V-groove for mounting the optical fiber is usually about 140 μm, whereas the width of the V-groove for mounting the ferrule is as large as about 1500 μm and the depth is as large as about 600 μm. Therefore, the steps for forming these are also complicated, and the silicon substrate itself is also large, which is not practical, and it is difficult to reduce the cost.

As a means for easily performing airtight sealing, an optical coupling system between an optical element and an optical fiber is filled with an optically transparent gel resin having a refractive index higher than that of air and lower than that of optical fiber. However, an airtight sealing structure in which the periphery of the gel resin is covered with a resin impermeable to humidity has been proposed, but by filling the optical coupling portion with a transparent gel resin higher than air and lower than the optical fiber. Improving the tolerance of optical coupling is not common because optical coupling efficiency is reduced.

Although the airtight sealing is performed by covering the periphery of the transparent resin with a resin impermeable to humidity, the humidity may penetrate through a gap between the substrate and the optical fiber and the resin, which is not sufficient.

Further, as a packaging method using a resin, an optical module using a transfer mold has been proposed. However, there is a problem that a large distortion is generated inside by molding using a resin.

FIG. 5 is a graph showing the relative displacement between the optical element mounted inside and the optical fiber after molding as a deformation amount with respect to the Young's modulus of the resin as 0 before molding. It can be seen that the deformation increases as the Young's modulus of the resin increases.

Further, a resin which can be usually transfer-molded has a large Young's modulus of about 20,000 N / mm ² , and further large distortion occurs around the optical coupling portion due to a filling pressure at the time of filling the resin or a high temperature at the time of molding. However, there is also a problem that the optical coupling characteristic is greatly deteriorated.

In a structure such as the optical module K of FIG. 7, the substrate on which the optical semiconductor element is mounted and the substrate on which the drive circuit is mounted are mounted separately in the same package. Since the same base is used, heat generated in the drive circuit and heat generated in the optical semiconductor element are transmitted to the package. At this time, if a package made of a material having a high thermal resistance (for example, a resin such as epoxy or glass) is used, the heat of the optical semiconductor element and the driving circuit cannot be efficiently dissipated, and a stable operation cannot be obtained. Or cause serious problems such as destruction due to temperature rise.

When a package made of a material having a low thermal resistance (for example, a metal such as copper or aluminum or a ceramic such as alumina or aluminum nitride) is used, the heat generated in the drive circuit is transmitted to the optical semiconductor element. The heat generated in the elements is transmitted to the drive circuit, which may cause the respective temperatures to rise. This is relatively mitigated if the package is used in a low temperature atmosphere, but poses a problem when used in a high temperature atmosphere.

In the optical module K, since the optical semiconductor element and the drive circuit must be mounted separately from each other, the electric wiring becomes long, and it is difficult to operate the optical semiconductor element at high speed. In addition, miniaturization of the optical module itself cannot be expected.

Further, since the optical semiconductor element and the optical fiber are mounted on different substrates, there is a problem that the optical coupling characteristics fluctuate due to a difference in thermal expansion of the substrate due to a temperature change.

Therefore, according to the present invention, the optical connection between the optical fiber and the optical semiconductor element can be accurately performed, the size can be reduced to the same degree as the mounting substrate, and the long-term reliability and the high speed are excellent. An object is to provide an optical module.

Therefore, according to the present invention, not only the above-mentioned breakage of the optical fiber can be prevented as much as possible with a simple configuration, but also the above-described problem of heat radiation can be prevented as much as possible, and the optical connection between the optical fiber and the optical element can be accurately performed. It is another object of the present invention to provide an optical module which can be reduced in size as much as a mounting substrate and has excellent long-term stability.

[0026]

In order to solve the above problems, an optical module according to the present invention comprises an optical fiber, an optical semiconductor device optically connected to the optical fiber, and a conductor connected to the optical semiconductor device. A first base provided respectively, and a second base provided with a conductor on which the first base is mounted and a conductor for supplying a current to a conductor connected to the optical semiconductor element is provided, and at least the optical fiber and the second base are provided. A gap with the optical semiconductor element is sealed with a moisture-resistant transparent resin, and at least the transparent resin is covered with an opaque resin.

In particular, the transparent resin also sealed the periphery of the optical semiconductor element and the conductor connected to the optical semiconductor element. Also,
The first base is made of single crystal silicon capable of anisotropic etching, and the second base is made of ceramics. Further, the transparent resin is a thermosetting resin having a refractive index equal to or higher than that of the optical fiber and lower than the optical waveguide layer of the optical semiconductor element.

The opaque resin is composed of bisphenol type epoxy resin 15 to 20%, acid anhydride hardener 10 to 15%, phenol resin hardener 3 to 10%, silicone resin modifier 3 to 10%, anhydrous Silicic acid 60-65%
Young's modulus after solidification with sushi solidified resin is 5000 N / mm
^It is good to be ² or less.

Here, the terms “transparent” and “opaque” indicate whether the light transmitted between the optical semiconductor element and the optical fiber is transparent or opaque. Further, the optical fiber may be supported by a ferrule mainly made of ceramic such as zirconia or alumina, and a ferrule fixing portion may be formed on the second base.

Further, the optical semiconductor element may be mounted on a third base provided with a conductor connected to the optical semiconductor element, and may be mounted on the first base. Here, the first base is provided with a recess for accommodating the third base on which the optical semiconductor element is mounted, and the recess is preferably filled with a transparent resin.

Further, in particular, the first base is provided on one main surface side of the second base, and a concave portion on which an electric circuit for an optical semiconductor element is formed is provided on the other main surface side. It is preferable to dispose a heat dissipation base to be connected. In addition, it is preferable that a through hole is formed in the concave portion of the second base, and the heat dissipation base is accommodated in the through hole. Thereby, heat generated in the electric circuit can be released to the one main surface side of the second base, and the heat radiation effect can be enhanced.

[0032]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective perspective view schematically showing an optical module M according to the present invention, and FIG.
3 shows an exploded perspective view, FIG. 3 shows a perspective sectional perspective view, and FIG. 4 shows a perspective view of the completed optical module.

The optical module M is composed of a first base 3 made of silicon single crystal or the like which can be anisotropically etched and a second base 5 made of ceramic or the like provided with wiring. A light emitting element 1 such as a semiconductor laser which is at least an optical semiconductor element and a light emitting element 1
The optical fiber 2 which is an optical waveguide optically connected to the optical fiber 2 is provided. The second base 5 is provided with a plurality of external conductor leads 4, in contrast, and a specific one of the leads 4 is connected to the electric wiring of the second base 5.

A light receiving element 11 for monitoring, such as a photodiode, is disposed on the first base 3 in the vicinity of the light emitting element 1, and monitors light emitted from the rear side of the light emitting element 1. On the light emitting side, a V groove 9 is formed by anisotropic etching or the like, and the optical fiber 2 is mounted in the V groove 9. As a result, high-precision fiber mounting can be performed, and mass production can be performed simply and quickly by a wafer process.

The first base 3 has current-carrying patterns (electrode pads) 6a and 6b of the light-emitting element 1 and light-receiving elements 11
Electrode patterns (electrode pads) 12a, 12b
Are formed, and these conductor patterns 6a, 6b, 1
2a and 12b are formed by performing Au (gold) metallization by a thin film manufacturing process or the like in order to transmit and receive electric signals.

The light emitting element 1 is passively aligned on the conductor pattern 6a at an accurate position with respect to the V groove 9, and is mounted and fixed by melting a solder made of an Au-Sn alloy formed on the conductor pattern 6a in advance. You. Similarly, the light receiving element 11 is mounted and fixed on the conductor pattern 12a. Further, in each optical element, a chip upper surface electrode of each optical element and the conductor patterns 6b and 12b are connected by a bonding wire such as an Au wire having a diameter of about 25 μm, for example.

The optical fiber optically connected to the light emitting element 1 is
For example, a quartz-based single mode optical fiber having a diameter of about 125 μm is applied, and a part thereof is precisely formed with zirconia or the like for optically connecting to an external optical connector (not shown). An optical fiber stub that is supported and fixed by a ceramic ferrule 10 of a certain degree is mounted.

The second base 5 is provided with conductor patterns 7a, 7b, 14a, 14b connected to the leads 4,
To accommodate the first base 3, a recess 13 having a depth about the thickness of the first base 3 and a ferrule supporting recess 16 for mounting and fixing the ferrule 10 are formed.
A microbend suppressing groove 15 having a length of 1 mm and a depth of 0.4 mm is formed to eliminate the microbend of the optical fiber generated when the first base 3 and the ferrule 10 are mounted and accommodated in the second base 5. ing.

Here, by forming the second base 5 from a ceramic mainly composed of, for example, alumina, the mechanical strength of the first base 3 formed of silicon single crystal or the like can be compensated. Also, since it is excellent in thermal conductivity, it is optimal as a structure having external electrodes, and an optical module with excellent reliability can be provided.

The conductor pattern connected to the lead 4 formed on the second base 5 is optimized by high-frequency electrical design, and is wired in the shortest path, so that an optical module having excellent high-frequency characteristics can be obtained. it can.

The gap and periphery between the light emitting element 1 and the end face of the optical fiber 2 optically connected thereto, the periphery of the light receiving element 11 and the periphery of the wiring of each optical element, the first base 3 and the second base Moisture absorption rate of 1% around the wiring area between 5
The following humidity is difficult to pass through, and the refractive index is the same as or higher than that of the optical fiber and lower than the optical waveguide layer of the light emitting element (for example, 1.4 to 3): a thermosetting transparent silicone resin, acrylic resin, or , And is solidified by covering with an epoxy resin or the like. This reduces the reflection on the optical fiber,
Optical coupling characteristics and optical coupling tolerance can be improved. Further, the thermosetting resin is easy to handle and has no problem in deterioration at the optical coupling portion.

Further, the upper surface of the second substrate 5 is coated with the above-mentioned silicone resin, a low stress opaque epoxy resin having a Young's modulus of 5000 N / mm ² or less so as to cover the ferrule 17 mounted on the second substrate 5, Potted and solidified with resin or silicone resin. Thereby, the displacement between the light emitting element and the optical fiber in the optical coupling portion can be suppressed to 0.5 μm or less as is clear from FIG.
Here, the resin is colored or the like to make it opaque resin so as to absorb the wavelength of light used in the optical semiconductor element.

Next, an example of an assembling procedure of the optical module M will be described. First, the light emitting element 1 and the light receiving element 11 are mounted and fixed on the first base 3, and wiring is performed on these optical elements.

The first base 3 is mainly fixed to the recess 13 of the second base 5 with solder or epoxy resin.

The optical fiber 2 is mounted in the V-shaped groove 9 of the first base 3, and the adhesive is cured while being pressed by a pressing plate 8 made of quartz glass or the like using an ultraviolet curing adhesive or an epoxy resin. . Thus, the optical fibers 2 are aligned and supported on the V-grooves 9 and fixedly mounted. The ferrule 10 is also accommodated in a ferrule supporting recess 16 provided in the second base 5 and is similarly fixedly mounted with an ultraviolet-curing adhesive, an epoxy resin or the like.

The conductor pattern 7 provided on the second base 5
a, 7b, 14a, 14b and the conductor patterns 6a, 6b, 12a, 12b on the first base 3 are wired.

The part including the optical fiber optically connected to the light emitting element 1, the light receiving element 11, and the part including the wiring is hardly permeable to humidity, and the refractive index is the same as or higher than that of the optical fiber and the optical waveguide of the light emitting element. Cover with a thermosetting silicone resin or the like lower than the layer and solidify.

Then, the upper surface of the second base 5 is covered with, for example, an epoxy-based opaque resin and solidified, whereby the optical module M as shown in FIG. 4 is completed.

Thus, the gap between the optical semiconductor element and the optical fiber to be optically connected to the optical semiconductor element and the periphery of the optical semiconductor element are sealed with a transparent resin impermeable to humidity, and the periphery of the transparent resin and the upper surface of the second substrate 5 are sealed with an opaque resin. , The reliability can be ensured for a long time. Although not shown, it is preferable to form a structure (for example, a notch) in the second base member 5 that matches the optical connector to be fitted to the ferrule 17.

Further, in the embodiment of the present invention, the form of the electrical connection by the wiring has been described. However, it is possible to further increase the frequency by performing the wiring such as a ribbon wire having excellent high frequency characteristics.

[0051]

Next, an optical module M1 according to a first embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 8 is a perspective view of the optical module M1 according to the first embodiment of the present invention, and FIG.
FIG. 10 is a transparent cross-sectional view around the optical coupling portion.

As a first base, a silicon single crystal substrate 103 whose surface has a (100) orientation was used. On the main surface side, a V-groove 109 for mounting an optical fiber was formed by anisotropic etching.
Fabry-Perot type semiconductor laser 1 with a corner thickness of 150 μm 1
01 for accommodating and mounting recess 01 and recess 10
6b was formed. The recess 106b is made of ceramics mainly composed of alumina as a third base, on which a PIN type photodiode 111 which is a light receiving element for monitoring light output from behind a Fabry-Perot type semiconductor laser is mounted. 800 μm square chip carrier 1 produced
19 is accommodated and mounted. The Fabry-Perot semiconductor laser 101 is mounted and fixed in the recesses 106a and 106b.
In order to fixedly mount the chip carrier 119 and electrically connect to the external conductor, Au-S
A Cr / Au (however, lower / upper) electrode on which an n alloy (thickness: 3 μm) was formed was formed by a photolithography process (not shown).

The Fabry-Perot semiconductor laser 101 is
The optical waveguide layer side is arranged on the upper surface side, and is visually aligned and fixed on the silicon substrate 103 by flip-chip mounting with a junction up, and the distance between the electrodes is φ25 μm.
(Not shown).

At this time, the depth of the concave portion 106a was previously set to 180 μm so that the optical waveguide layer was 30 μm below the main surface of the silicon substrate 103.

V-groove 109 on which optical fiber 102 is mounted
Is to set the width of the V-groove 109 to 196 μm so that the core center (not shown) coincides with the center of the optical waveguide layer (not shown) of the Fabry-Perot semiconductor laser 101 when the optical fiber 102 is mounted. Accordingly, optical coupling is performed at a position 30 μm below the main surface in the concave portion 106a of the silicon substrate 103.

Similarly, PIN type photodiode 111
Is mounted and fixed on the chip carrier 119, and the light receiving surface side electrode and the chip carrier side electrode are connected to the Au wire 120 of φ25 μm.
Wired at b.

Further, the chip carrier 111 was mounted and fixed in the concave portion 106b of the silicon substrate 103. The silicon substrate 103 is mounted and accommodated in the recess 113 of the ceramic multilayer wiring substrate 105 mainly made of alumina as the second substrate with an epoxy resin (Epotech 353ND).
An electrode 112 formed on a silicon substrate 103 and electrically connected to an optical semiconductor device and a ceramic multilayer wiring substrate 105
The electrodes 114 electrically connected to the solder balls 104, which are external wirings formed in the above, were connected by wiring with Au wires 120a having a diameter of 25 μm.

The optical fiber 102 has a fiber stub structure mounted on a ceramic ferrule having a diameter of 1.25 mm and a length of 6 mm made of zirconia, and a quartz glass pressing plate 108 is used for a V groove 109 formed in a silicon substrate 103. Mounting and mounting, UV curable adhesive (UV
1100: manufactured by Daikin Industries, Ltd.).

The gap between the semiconductor laser 101 in the recess 106a of the silicon substrate 103 and the optical fiber optically coupled thereto, the gap between the PIN type photodiode and the semiconductor laser 101 in the recess 106b, and the recess 106a and 106b were filled with a transparent silicone resin having a refractive index of 1.47, and were solidified under the thermosetting conditions of 150 degrees and 60 minutes.

Further, the main surface side of the ceramic multilayer wiring substrate is made of 10% of a bisphenol type epoxy resin, 15% of an acid anhydride curing material, 5% of a phenol resin curing material, 10% of a silicone resin modifier, and 60% of silicic anhydride. Using a mixed resin,
The optical module M1 was completed by solidifying under the thermosetting conditions of 150 degrees for 4 hours.

When the characteristics of the optical module M1 were evaluated, good characteristics were obtained. As an example, -4
FIG. 11 shows the result of tracking error when observing light output fluctuation under a temperature condition of 0 to 85 degrees. From this result, it was confirmed that the optical output fluctuation was very good, within ± 0.3 dB.

Furthermore, the presence of the concave portions 106a and 106b allows the height to be reduced, and the structure to which external stress is less likely to be applied, thereby enabling stable optical connection.

Next, an optical module M2 according to a second embodiment of the present invention will be described in detail.

FIG. 12 is a perspective view of a surface-emitting type optical semiconductor device according to a second embodiment of the present invention, FIG. 13 is a perspective view of a third substrate according to the second embodiment of the present invention, and FIG. FIG. 14 is an exploded perspective view of the optical subassembly according to the second embodiment;
FIG. 15 shows an optical module M according to the second embodiment of the present invention.
2 shows a perspective view of FIG. The optical module M2 is a parallel transmission optical module that can obtain four optical outputs.

An array type VCSEL chip 201 having four light-emitting portions 220a, 220b, 220c, and 220d and having a width of 250 μm, a length of 1000 μm, a thickness of 100 μm, and a light-emitting portion interval of 250 μm was used as a surface-emitting type optical semiconductor device. The VCSEL chip has electrodes 20 on the light emitting surface side.
6a, 206b, 206c, and 206d are provided, and have a structure having a common electrode (not shown) on the back surface side. Metal (Au) markers 221a and 221 serving as marks when the VCSEL chip 201 is mounted on the light emitting surface side.
b, 221c and 221d are formed in a 10 μm square.

As a third base, a chip carrier 219 made of ceramics mainly composed of alumina was used.
The chip carrier 219 is provided with a VC by a thin film process.
Ti (0.1 μm thick) Pd (0.2 μm thick) Au (2 μm thick) coplanar electrodes 207 a, 207 b, 207 c, and 207 d that conduct electricity with the SEL chip 201 are formed. The width of the signal electrode was 200 μm, and the distance between the signal electrode and the ground electrode 212 was 50 μm.

The VCSEL chip 201 is aligned by visual alignment on the chip carrier ground electrode 212, and an Au—Sn alloy solder (thickness: 3 μm) (not shown) previously formed on the ground electrode 212 is melted and fixedly mounted. did.

Thereafter, the V wire was connected to a φ25 μm Au wire.
The CSEL chip side electrode and the chip carrier side electrode were connected by wiring.

As a first base, a silicon single crystal substrate having a surface having a (100) orientation was used, and anisotropic etching was used to mount optical fibers 202 at intervals of 250 μm.
V-groove 209 for mounting two optical fibers and concave portion 20 for accommodating a 2 mm square VCSEL chip 201 having a depth of 1 mm
The silicon substrate 203 on which 6a was formed was used. The inclined surface of the concave portion 206a forms an inclined surface of {111} plane of 54.7 degrees by anisotropic etching. Further, on the surface side of the concave portion, the chip carrier 219 is fitted and mounted.
The concave portion 206b was formed by dicing over a width of 1 mm and a depth of 10 μm.

The optical fiber 202 is a multi-mode optical fiber of GI50, and a resin ferrule 210 in which four cores of tape at intervals of 250 μm are formed of epoxy resin in advance.
It has a fiber stub structure inserted into the stub. The fiber interval is 250 μm. Further, a fitting pin hole for fitting with an external connector is arranged on an end face of the resin ferrule 210.

The optical fiber 202 is mounted in the V groove 209,
When the chip carrier 219 is fitted and mounted in the concave portion 206b, the V groove width of the silicon substrate is set in advance so that the center of the core of the optical fiber and the center of the light emitting portion of the VCSEL chip coincide.
It was 24 μm. At this time, the center of the light emitting portion of the VCSEL chip is located 50 μm below the main surface of the silicon substrate.

The optical fiber 202 is mounted and fixed with an ultraviolet curing adhesive (UV1100) using a quartz pressing plate (not shown), the chip carrier 219 is bonded and fixed with an epoxy resin adhesive (Epotek 353ND), Assembly S1 was made.

As the second substrate, a ceramic multilayer wiring substrate 205 having a length of 14 mm, a width of 10 mm, and a thickness of 2.5 mm, which was mainly made of alumina, was used. The ceramic multilayer wiring substrate 205 has a concave portion for mounting and housing the optical subassembly S1 on the main surface side, a signal line width of 200 μm for electrical connection with the optical semiconductor element, and a ground electrode interval of 100 μm.
A BGA structure (not shown) in which a coplanar electrode having a length of m is formed, a back surface side is electrically connected to the outside through internal wiring, and solder balls for fixing and mounting the substrate to a circuit mounting substrate is provided. I have. Further, a terrace 221 for fixing the resin ferrule was provided.

The optical subassembly S1 is fixedly mounted on the concave portion of the ceramic multilayer wiring substrate 205 with an epoxy resin adhesive (Epotech 353ND), and the gap between the coplanar electrode of the chip carrier 219 and the coplanar electrode of the ceramic multilayer substrate is 175 μm. Wiring connection was made with an Au ribbon wire 220.

The resin ferrule was also fixedly mounted on the terrace with 210 epoxy resin adhesive (Epotek 353ND).

VC in silicon substrate 203 recess 206a
A gap between the SEL chip 201 and the optical fiber 202 optically coupled to the SEL chip 201 was filled with a transparent silicone resin having a refractive index of 1.47, and was solidified under a thermosetting condition of 150 degrees and 60 minutes (not shown).

Further, the main surface side of the ceramic multilayer wiring substrate 205 is composed of 10% of bisphenol type epoxy resin, 15% of acid anhydride curing material, 5% of phenol resin curing material, 10% of silicone resin modifier, 60% of silicic anhydride. The optical module M2 was completed by using the mixed resin (not shown) of the above and solidifying it under a thermosetting condition of 150 ° C. for 4 hours.

When the characteristics of the optical module M2 were evaluated, it was found that the optical module M2 had reliability satisfying the Bellcore standard which is standardly tested in the industry. Furthermore, since an array type VCSEL chip is used, a parallel multi-core optical module can be realized, and small and high-speed optical transmission is realized.

Next, an optical module M3 according to a third embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 16 is an exploded perspective view of an optical module M3 according to a third embodiment of the present invention, and FIG.
FIG. 18 is a perspective view showing the back surface side of a second base, which will be described later, which is a component of No. 3, FIG. 18 is a perspective view of the completed optical module M, and FIG. 19 is a sectional view taken along line AA in FIG.

The optical module M3 is an anisotropically-etchable silicon single crystal having a Fabry-Perot semiconductor laser as a light-emitting semiconductor device and a PIN photodiode as a light-receiving semiconductor device (thermal conductivity: 168 W / m · K)
A base 303 and alumina having wiring as a main raw material;
It mainly comprises a ceramic multilayer wiring substrate 306.

On a silicon single crystal substrate 303, a Fabry-Perot semiconductor laser 301, a PIN photodiode 302, and a single mode optical fiber 304 as an optical waveguide optically connected to the Fabry-Perot semiconductor laser 301 are provided.

On the ceramic multilayer wiring substrate 306, solder balls 309 and 31 which are a plurality of external conductors (that is, electrically connected to an external circuit (not shown)) are provided.
0 and the like, and a specific one of the solder balls 309 and 310 was connected to the electric wiring of the ceramic multilayer wiring substrate 306.

The silicon single crystal substrate 303 has a PIN photodiode 3 serving as a light receiving element for monitoring.
Numeral 02 is disposed near the Fabry-Perot type semiconductor laser 301, and the emission intensity of the laser 301 is controlled by monitoring the light emitted from the rear side of the laser 301. Then, a V-groove 316 was formed on the front side of the laser 301 by anisotropic etching, and the optical fiber 304 was fixedly mounted on the V-groove 316 with a pressing plate 305 made of quartz glass and mounted. As a result, high-precision fiber mounting could be performed, and mass production could be performed easily and quickly by a wafer process.

On the silicon single crystal substrate 303, the current supply patterns (electrode pads) 317a,
The conductive patterns (electrode pads) 318a, 318b of the photodiode 17b and the photodiode 302 are formed. These conductive patterns 317a, 317b, 318a, 318b are formed by a thin film process or the like in order to transmit and receive electric signals.
(Gold) Metallized and formed.

The laser 301 is passively aligned at an accurate position with respect to the V-groove 316 on the conductor pattern 317a, and Au-formed in advance on the conductor pattern 317a.
It was mounted and fixed by melting a solder made of a Sn alloy. Similarly, the photodiode 302 was mounted and fixed on the conductor pattern 318a. Further, each optical element is connected to a chip upper surface electrode of each optical element and a conductive pattern 31 by a bonding wire of Au wire of about φ25 μm.
7b and 318b, respectively.

Optical fiber 3 optically connected to laser 301
Reference numeral 04 is a quartz single-mode optical fiber having a diameter of 125 μm, and a part thereof is precisely molded with zirconia or the like for optically connecting to an external optical connector (not shown). An optical fiber stub supported and fixed by a ceramic ferrule 319 using zirconia as a main raw material was mounted.

The ceramic multilayer wiring substrate 306 has electrodes and internal wiring patterns formed thereon and is made of alumina (thermal conductivity:
20W / m · K) or aluminum nitride (thermal conductivity: 15
(0 W / m · K) as a main material, and was constituted by a ceramic multilayer substrate manufactured by laminating ceramic thin film sheets. Then, as described later, a concave portion 329 for accommodating the silicon single crystal substrate 303 is provided on one main surface side.
On the other main surface side, a concave portion 313 in which a drive circuit IC 308 which is a circuit element for driving the optical semiconductor elements 302 and 303 is mounted. Heat dissipation base 3
21 are provided in advance.

In the ceramic multilayer wiring substrate 306, a concave portion 329 having a depth of the thickness of the substrate 303 and a concave portion 330 for fixing and supporting the ferrule 319 are formed to accommodate the silicon single crystal substrate 303. Also, the recess 32
In the vicinity of 9, an electrode pattern for making electrical connection with the silicon single crystal substrate 303 and electrode patterns 331a and 331b for mounting and fixing electronic components 314 and 315, which are chip capacitors and chip resistors, are provided. Formed. These electrode patterns are connected to the electrode patterns formed in the concave portions 313 for mounting the drive circuit ICs 308 formed on the ceramic multilayer wiring substrate 306 by the internal wiring patterns of the ceramic multilayer wiring substrate 306. Similarly, solder balls 309 and 310 as external conductors are also connected by the internal wiring pattern. The concave portion 313 has CuW (heat conductivity: 250 W / m.
K), the heat dissipating base 321 was formed in advance on the ceramic multilayer wiring base 306 by brazing.

As the heat dissipation base, aluminum (thermal conductivity: 240 W / m · K), copper (thermal conductivity: 390 W)
/ M · K) or the like, and solder may be used as a bonding agent. In order to further improve the heat dissipation, the heat dissipation base 321 was connected to an external heat dissipation body 7 made of aluminum with a paste material mixed with a metal powder having excellent heat conductivity.

In the concave portion 329 for accommodating the silicon single crystal substrate 303, a heat radiation pad made of Au is provided to radiate heat generated in the silicon single crystal substrate 303. This heat radiation pad is connected in advance to a thermal via 323 connected to an external heat radiator 322 made of CuW.

The solder balls 310a, which are the external conductors, are recessed through the internal wiring patterns 324e and 325d.
Connected to an electrode pad (not shown) formed in the
It was connected to the drive circuit IC 308 by an Au bonding wire. The conductor pattern 317a of the silicon single crystal substrate 303 is Au and the conductor pattern 331b of the substrate 306.
Connection was made with a bonding wire. Conductor pattern 331
b denotes electronic components 15 such as chip resistors and chip capacitors.
Is mounted and fixed, and the electronic component 315 is
24a, 325a, and 324b, and is connected to the electronic component 314.
24c, 325b, 324d, 325c
13 and is electrically connected to the drive circuit IC 308 by bonding wires. Similarly, specific electrodes of the drive circuit IC 308 are connected to the solder balls 3 via the internal wiring patterns 327 and 326.
10b, so that signals can be transmitted and received to and from the outside.

Depression 3 of ceramic multilayer wiring base 306
No. 13 was seam-welded with a metal cap 328 made of Kovar. It should be noted that there is no problem in sealing with a cap made of glass, ceramic, or the like, or by filling and solidifying a resin.

A part of the optical fiber optically connected to the laser 301, the part including the photodiode 302 and the wiring is hardly permeable to humidity, has a refractive index equal to or higher than that of the optical fiber, and has an optical waveguide layer of the laser. It was covered with a lower thermosetting type silicone resin (not shown) or the like to be solidified.

Then, the ceramic multilayer wiring substrate 306
Around the mounting portion of the base 303 is an epoxy-based opaque resin 3
By solidifying with covering with 12, the optical module M3 as shown in FIG. 17 was completed.

Thus, since the drive circuit IC 308 is mounted on the heat dissipation base 321 in the recess formed in the ceramic multilayer wiring base 306, the high heat generated in the drive circuit IC 308 is mounted on the silicon single crystal base 303. It was possible to operate without transmitting to the optical semiconductor elements 302 and 303.

On the other hand, the heat generated by the optical semiconductor elements 302 and 303 of the silicon single crystal substrate 303 can be radiated by the external heat radiator through the heat radiating pad and the thermal via formed in the concave portion 329. A configuration in which deterioration is unlikely to occur can be achieved, and the heat generated in the optical semiconductor element does not stay inside, and a highly reliable optical module with good heat dissipation can be obtained.

Although not described, the wiring pattern formed on the silicon single crystal substrate 303, the wiring pattern formed on the ceramic multilayer wiring substrate 306, and the internal wiring pattern are microstrip lines and coplanar lines having excellent high-frequency characteristics. By using a ribbon wire at a key point, it is excellent in high-frequency characteristics, 2.5 Gbps and 10 Gbps.
A high frequency characteristic of Gbps was obtained.

[0100]

As described above, according to the optical module of the present invention, the first substrate provided with the optical semiconductor element and the optical fiber optically connected to the optical semiconductor element is electrically connected to the optical semiconductor element. The optical semiconductor element and the optical fiber optically connected to the optical semiconductor element are protected with a transparent resin that is not easily permeable to moisture, and further covered with a low-stress opaque resin. Thereby, a very excellent sealing structure can be obtained.

Further, by providing a concave portion for filling the first substrate with the transparent resin, and accommodating the optical semiconductor element in the concave portion and covering it with the transparent resin, it is possible to further improve the sealing property.

Further, the surface-emitting type optical semiconductor element and the surface-receiving type optical semiconductor element are fixedly mounted on the third base, accommodated and mounted on the first base provided with a concave portion in advance, and the concave portion is filled with a transparent resin. This enabled a sealing structure.

A first substrate and a concave portion for accommodating the first substrate on one main surface are provided, and a driving circuit or a signal processing circuit for driving an optical semiconductor element is provided on the other main surface. The concave portion in which the circuit element is mounted, and the concave portion for accommodating the drive circuit or the signal processing circuit, further comprising a second base provided with an electric terminal which is an external conductor of the drive circuit or the signal processing circuit. A heat dissipation base having a higher thermal conductivity than the second base is provided, and a drive circuit or a signal processing circuit is mounted and accommodated in the heat dissipation base, so that heat generated in the optical semiconductor element is transmitted to the drive circuit, It is possible to provide an optical module which does not transmit heat generated in the drive circuit to the optical semiconductor element, has excellent heat dissipation, and does not deteriorate characteristics.

Further, it is possible to provide an optical module which can reduce the size and weight of a substrate such as a silicon substrate which requires high precision as much as possible and which is excellent in high frequency characteristics.

Further, since the first base is made of single-crystal silicon and the second base and the third base are made of ceramics, it is possible to provide an optical module excellent in high-frequency characteristics, easy to manufacture, and excellent in reliability. .

The transparent resin has a refractive index equal to or higher than that of the optical fiber, and is of a thermosetting type lower than the optical waveguide layer of the optical semiconductor element. 20%, acid anhydride hardener 10 to 15%, phenolic resin hardener 3 to 1
By using a mixed resin of 0%, a silicone resin modifier of 3 to 10%, and a silicic anhydride of 60 to 65%, the Young's modulus can be reduced to 5,000 N / mm ² or less, which is excellent in reliability and weight reduction. An optical module that can be provided 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.

FIG. 2 is an exploded perspective view in FIG. 1.

FIG. 3 is a perspective sectional view of FIG.

FIG. 4 is a perspective view schematically illustrating an embodiment of the optical module according to the present invention.

FIG. 5 is a graph showing a relationship between a Young's modulus and a deformation amount.

FIG. 6 is an exploded perspective view for schematically explaining a conventional optical module.

FIG. 7 is a perspective view schematically illustrating a conventional optical module.

FIG. 8 is an optical module M according to the first embodiment of the present invention.
1 is a perspective view of FIG.

FIG. 9 is an exploded perspective view of FIG.

FIG. 10 is a perspective cross-sectional view around the optical coupling unit in FIG.

FIG. 11 is a graph showing a tracking error evaluation result of the optical module M1.

FIG. 12 is a perspective view of a surface-emitting type optical semiconductor device according to a second embodiment of the present invention.

FIG. 13 is a perspective view of a third base according to the second embodiment of the present invention.

FIG. 14 is an exploded perspective view of an optical subassembly according to a second embodiment of the present invention.

FIG. 15 is a perspective view of an optical module M2 according to a second embodiment of the present invention.

FIG. 16 is an exploded perspective view schematically illustrating an optical module M3 according to a third embodiment of the present invention.

FIG. 17 is an exploded bottom perspective view of FIG. 16;

FIG. 18 is a perspective view of an optical module M3 according to a third embodiment of the present invention.

FIG. 19 is a sectional view of an optical module M3 according to a third embodiment of the present invention.

[Explanation of symbols]

1: light emitting element (optical semiconductor element) 2: optical fiber 3: first base 4: lead 5: second base 6a, 6b, 7a, 7b, 12a, 12b, 14a, 1
4b: Conductor pattern 8: Quartz plate 10: Ferrule 11: Light receiving element (optical semiconductor element) 17: Silicone resin (transparent resin) 18: Epoxy resin (opaque resin) M, M1 to M3: Optical module

Claims (5)

[Claims] An optical fiber, an optical semiconductor device optically connected to the optical fiber, a first substrate provided with a conductor connected to the optical semiconductor device, and a first substrate mounted on the first substrate. An optical module comprising: a second base provided with a conductor for conducting electricity to a conductor connected to the optical semiconductor element,
An optical module, wherein at least a gap between the optical fiber and the semiconductor element is sealed with a moisture-resistant transparent resin, and at least the transparent resin is covered with an opaque resin. 2. The optical module according to claim 1, wherein the transparent resin also seals around the optical semiconductor element and a conductor connected to the optical semiconductor element. 3. The optical module according to claim 1, wherein said first base is made of single-crystal silicon, and said second base is made of ceramics. 4. The optical module according to claim 1, wherein the transparent resin is a thermosetting resin having a refractive index equal to or higher than that of an optical fiber and being lower than an optical waveguide layer of the optical semiconductor element. 5. The opaque resin has a Young's modulus of 5000N.
^2. The optical module according to claim 1, wherein the optical module is a resin of not more than / mm ² .