JP2005049389A - Connector type optical module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a thin profile as well as enhancing reliability by improving an optical module which is of a type to bring an optical semiconductor element into direct contact with an optical connector. <P>SOLUTION: The connector type optical module is equipped with a substrate 11 which is mounted with an optical semiconductor element 13 composed of a surface-emitting laser diode, a transparent contact resin 14 which is selectively installed on the active region of the optical semiconductor element 13, and an optical connector 15 which is, positioning and holding an optical fiber 16, installed by being mechanically positioned on the mounted substrate 11. The mounted substrate 11 and the optical connector 15 are positioned vertically to the optical axis direction with a guide pin 17 and a guide hole 12 so that the tip end of the optical fiber 16 is matched in position with the active region of the optical semiconductor element 13, and are also positioned relative to the optical axis direction with a stopper part so that the tip end of the optical fiber 16 is situated between the surface of the optical semiconductor element 13 and the top of the transparent contact resin 14. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a connector-type optical module used for optical wiring and the like, and more particularly to a connector-type optical module that is reduced in thickness.
[0002]
[Prior art]
2. Description of the Related Art In recent years, several optical wiring devices that connect LSIs with light have been proposed with the dramatic improvement in operation speed of LSIs. The optical wiring has almost no frequency dependency such as loss in the frequency range from DC to 100 GHz or more, and there is no electromagnetic interference in the wiring path or ground potential fluctuation noise. Therefore, wiring of several tens of Gbps can be easily realized. In addition, unlike the electrical wiring, the optical wiring has no skin effect of the wiring, so it is not necessary to make the wiring (such as an optical fiber) thick even at several tens of Gbps. Therefore, in a high speed region of 10 Gbps or more, it is advantageous for electric wiring in terms of space saving.
[0003]
As a simple example of this space saving characteristic, there is a connector (so-called MT connector) as described in Non-Patent Document 1, and a maximum of 12-core optical fibers can be accommodated in one optical connector. Further, according to the extended standard for MT connectors, a 60-core optical fiber can be accommodated in one MT connector. At this time, if a signal of 10 Gbps is passed per optical fiber, a signal wiring of 600 Gbps is possible with the cross-sectional area (3 mm × 7 mm) shown in Non-Patent Document 1.
[0004]
When this is realized by a high-frequency coaxial cable (generally about 5 mmφ) capable of 10 Gbps transmission, a wiring cross-sectional area of 5 mm × 300 mm for a flat cable and about 1400 mm ² for a triangular grid arrangement cable is required. Therefore, the above-described optical wiring achieves space saving of 1/60 of the electrical wiring.
[0005]
As an optical module configuration for use in such an optical wiring, configurations described in Patent Documents 1 to 3 are known.
[0006]
Patent Document 1 includes a fiber array with guide holes at a coupling portion of an optical connector as a mechanism for coupling an arrayed optical element to the MT connector (Non-Patent Document 1). This fiber array with guide holes has a configuration equivalent to that obtained by cutting out the tip portion of the MT connector, that is, a relay optical fiber that connects the optical semiconductor element and the optical fiber. The repeater optical fiber is fixed to the optical module and has a function of protecting the optical semiconductor element from mechanical shock and stress when the MT connector is abutted.
[0007]
Patent Document 2 is an example in which the optical fiber tip is in direct contact with the optical semiconductor element to perform optical coupling. An optical fiber having a certain length is always fixed to the optical module, and an optical connector is attached to the tip of the fixed optical fiber. It is a form of having. Patent Document 3 is an example in which an optical semiconductor element and an optical connector are directly coupled, and introduction of a polymer sheet for suppressing optical interference due to a gap between the optical semiconductor element and the optical connector is shown.
[0008]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-202440
[Patent Document 2]
JP-A-6-237016 [0010]
[Patent Document 3]
Japanese Patent No. 2970543
[Non-Patent Document 1]
Japanese Industrial Standard (JIS) C5981
[0012]
[Problems to be solved by the invention]
However, this type of optical module for optical wiring has the following problems.
[0013]
That is, as an introduction form of the optical wiring, when the inter-board wiring is opticalized, it is relatively easy in terms of size to replace the electrical coaxial cable or the backplane wiring with an optical fiber. However, when the wiring between LSIs is made optical, it is necessary to incorporate an optical module in a space corresponding to an LSI package terminal, and it is difficult to realize in a form in which optical modules as shown in Patent Document 1 are simply gathered together. Become.
[0014]
For example, an LSI that requires an optical interface is generally intended for high-speed operation, and its calorific value is often very large. For this reason, a local heat sink (or heat spreader) of the LSI chip is often required, and a configuration is such that a mounting board is disposed at the lower part of the LSI chip and a heat sink is disposed at the upper part of the LSI chip. For this reason, it is desirable that the optical module for optical wiring is a thin module that fits in a slight gap between the mounting board and the heat sink. The ideal thickness reduction is equivalent to the thickness of the LSI chip, for example, 200 to 600 μm. This corresponds to a thickness obtained by simply stacking an optical fiber (for example, 125 μmφ) and an optical semiconductor element (for example, 100 μm thick) at the minimum value, which is not realistic.
[0015]
Next, in the case of the so-called pigtail type as in Patent Document 2, it is relatively easy to reduce the thickness of the optical module, but the optical fiber and the optical connector hang from the LSI package. The long part tends to get in the way, and the optical fiber and the optical connector are easily damaged. In addition, since the optical semiconductor element and the optical fiber are firmly fixed, there is also a problem that the optical semiconductor element is liable to be deteriorated or broken due to stress due to a difference in thermal expansion coefficient, tension on the optical fiber, or the like. In addition, there is a problem that mass productivity and practicality are poor, such as a batch high temperature process such as solder reflow is not applicable.
[0016]
Next, in the case of the direct contact type of an optical semiconductor element and an optical connector as in Patent Document 3, it can be configured only by the optical semiconductor element, its support, and a polymer sheet as constituent members, and can be made extremely thin. However, since the optical semiconductor element is directly pushed by the optical connector with the polymer sheet sandwiched therebetween, there is a problem that the optical semiconductor element is destroyed unless the pushing force of the optical connector is properly controlled.
[0017]
In addition, when the gap is controlled using an appropriate spacer, if the thickness of the polymer sheet and the gap are not adjusted properly, the optical semiconductor element may be damaged, or optical interference may occur due to poor polymer sheet contact (gap generation). There's a problem. Furthermore, in general, the polymer has a large thermal expansion, and even if it is set to an appropriate gap, an excessive contact pressure of the polymer sheet (damage of the optical element) and poor contact (poor photoconductivity) are likely to occur at high or low temperatures.
[0018]
The present invention has been made in consideration of the above circumstances, and the object of the present invention is to improve the optical module of the type in which the optical semiconductor element and the optical connector are in direct contact with each other, and to improve the reliability while reducing the thickness. An object of the present invention is to provide a connector-type optical module that can be measured.
[0019]
[Means for Solving the Problems]
(Constitution)
The essence of the present invention is that a transparent contact resin is partially formed at the contact portion between the optical semiconductor element and the optical connector (optical fiber), and a free space is left around the resin, so that the deformation of the resin against the optical connector pressing is three-dimensional. To do. The cushioning effect of the resin is enhanced by increasing the deformable amount of the resin.
[0020]
That is, the present invention provides a connector-type optical module, wherein a transparent contact resin selectively provided on an active region of an optical semiconductor element having a light emitting or receiving function, and an optical fiber tip is connected to the surface of the optical semiconductor element and the transparent Means for positioning the tip of the fiber so as to be positioned between the top of the contact resin, and means for positioning the tip of the fiber so that the tip of the optical fiber is aligned with the active region of the optical semiconductor element; It is characterized by comprising.
[0021]
The present invention also includes a mounting substrate on which an optical semiconductor element having a light emitting or receiving function is mounted, a transparent contact resin selectively provided on an active region of the optical semiconductor element, and an optical fiber for positioning and holding, In a connector-type optical module comprising an optical connector that is mechanically positioned and attached to a mounting board, the mounting board and the optical fiber are aligned so that the tip of the optical fiber is aligned with the active region of the optical semiconductor element. A guide mechanism for positioning the connector with respect to a direction perpendicular to the optical axis, and the mounting substrate and the light so that the tip of the optical fiber is located between the surface of the optical semiconductor element and the top of the transparent contact resin. An abutting portion for positioning the connector with respect to the optical axis direction is provided.
[0022]
Here, preferred embodiments of the present invention include the following.
[0023]
(1) The shape of the transparent contact resin is a hemispherical dome, and the top of the hemispherical dome is a contact portion with the tip of the optical fiber.
[0024]
(2) A protective film made of an oxide film or a nitride film is formed on the surface of the optical semiconductor element, and a silicone resin is used as the transparent contact resin.
[0025]
(3) As a guide mechanism for aligning the tip of the optical fiber and the active region of the optical semiconductor element (alignment in the direction perpendicular to the optical axis), a guide pin is provided on the optical connector side, and a pin hole is provided on the mounting substrate side. Was established.
[0026]
(4) A recess is provided on the upper surface side of the mounting substrate, the optical semiconductor element is mounted on the bottom surface of the recess, the upper surface of the semiconductor element is lower than the upper surface of the mounting substrate, and the top of the transparent contact resin is higher than the upper surface of the mounting substrate. Is also expensive.
[0027]
(5) The bottom surface of the optical connector is flush with the tip of the optical fiber, and the top surface of the mounting substrate and the bottom surface of the optical connector are abutted.
[0028]
(Function)
According to the present invention, rather than sandwiching a polymer sheet or the like between the optical semiconductor element and the optical connector, the optical semiconductor element and the optical connector are partially in contact by the transparent contact resin selectively provided on the optical semiconductor element. However, the pushing force of the optical connector is absorbed by the deformation of the transparent contact resin. Therefore, there is no possibility of destroying the optical semiconductor element due to the pushing force of the optical connector as in the case of using the polymer sheet, and a thin and highly reliable connector type optical module can be realized with a high yield.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
The details of the present invention will be described below with reference to the illustrated embodiments.
[0030]
(First embodiment)
FIG. 1 is a schematic cross-sectional view showing the principle configuration of the first embodiment of the present invention, in which 11 is a mounting substrate, 12 is a guide hole, 13 is an optical semiconductor element, 14 is a transparent contact resin, and 15 is an optical connector ferrule. (MT connector ferrule), 16 is an optical fiber, 16a is an optical fiber core, and 17 is a guide pin.
[0031]
Here, as an example, the optical semiconductor element 13 represents a four-element array of a surface emitting laser (VCSEL: Vertical Cavity Surface Emitting Laser-diodes), but this may be a single element or a light receiving element (or an array element thereof). It does not matter.
[0032]
The mounting substrate 11 is, for example, a resin substrate, and a concave portion for mounting an optical semiconductor element is provided on the upper surface side of the substrate 11. Here, the depth of the recess is set so that the upper surface of the optical semiconductor element 13 is slightly retracted from the upper surface of the mounting substrate 11 when the optical semiconductor element 13 is mounted on the bottom surface of the recess. Thereby, even if the optical connector ferrule 15 is abutted against the upper surface of the mounting substrate 11, the optical connector ferrule 15 and the optical fiber 16 do not directly hit the optical semiconductor element 13.
[0033]
Further, the transparent contact resin 14 is not provided on the entire surface of the optical semiconductor element 13, but is selectively provided on the active part of the optical semiconductor element (surface emitting laser light emitting part, light receiving element light receiving part), and the top thereof is the mounting substrate. 11 is formed so as to protrude slightly from the top surface. Thereby, when the optical connector ferrule 15 is abutted against the upper surface of the mounting substrate 11, the optical fiber 16 comes into contact with the transparent contact resin 14.
[0034]
FIG. 2 shows a top view and cross-sectional views (AA ′ and BB ′) of the mounting substrate 11. In the figure, 13a is an element electrode, 13b is an element active part, 18 is a driving IC (driver, receiver), and 19 is a bonding wire. If the transparent contact resin 14 is selectively coated with a resin (transparent) such as a silicone resin, an acrylic resin, an epoxy resin, or a polyimide resin with a dispenser or the like, a hemispherical dome shape as shown in the figure is obtained, and the optical connector ferrule 15 is obtained. The contact with becomes easy. This will be described with reference to FIG.
[0035]
FIG. 3 shows a contact state between the transparent contact resin 14 and the optical fiber 16, where (a) shows a state before contact, and (b) shows a state after contact. The optical semiconductor element 13 is, for example, an AlGaAs / GaAs VCSEL (oscillation wavelength of about 0.85 μm), and a transparent contact resin 14 is provided around the laser oscillation part (active region) 13b. As the transparent contact resin 14, a silicone resin that easily takes a large amount of elastic deformation by pressurization is suitable. With silicone rubber or the like, an elongation rate of about 100% can be obtained relatively easily. However, silicone resin generally has high moisture permeability and low gas barrier properties. In order to maintain device reliability, a protective film made of an oxide film or nitride film is provided on the surface of the optical semiconductor element 13. Is desirable.
[0036]
As the size of the transparent contact resin 14, for example, when the core diameter of the optical fiber 16 is 50 μm and the numerical aperture NA is 0.21, the diameter of the lower surface of the hemispheric dome is 120 μm, and the height of the top of the hemispheric dome is 60 μm. To do. And the level | step difference of the mounting substrate 11 and the thickness of the optical semiconductor element 13 are set so that the height after an optical fiber contact may be set to 40 micrometers. At this time, since the shape of the transparent contact resin 14 is a hemispherical dome shape, the contact area with the optical fiber 16 increases rapidly with respect to the pushing amount of the optical fiber. This not only increases the cross-sectional area of the hemispherical surface, but also the resin deformed to be pushed out in the outer peripheral direction by the pushing of the optical fiber 16 repels and pushes back the optical fiber 16, and comes in contact with the optical fiber 16 more and more. It is because the effect which comes is included (FIG.3 (b)).
[0037]
Therefore, in the connector type optical module of the present embodiment, a sufficient contact area can be obtained by a relatively small pressure, and the optical semiconductor element 13 is formed regardless of the type in which the optical semiconductor element 13 and the optical connector ferrule 15 are directly opposed to each other. Direct contact can be realized without applying excessive external force. Further, the positional accuracy of the transparent contact resin 14 may be about several μm as long as the relative positions of the optical semiconductor element 13 and the optical fiber 16 are accurately matched. That is, even if the position of the transparent contact resin 14 is shifted by several μm, the contact area between the optical fiber 16 and the transparent contact resin 14 does not change greatly, and the contact portion can be made sufficiently larger than the required optical path (50 μmφ). (For example, 90 μmφ), a positional error of several μm is not a problem.
[0038]
(Second Embodiment)
In the above, the principle configuration has been shown in an example applied to a standard connector such as an MT connector. However, the main point of the present invention is that a very thin optical module can be realized, and a specific example is shown in FIG. FIG. 4A is a cross-sectional view showing the configuration of the connector type optical module according to the second embodiment of the present invention, in which 21 to 29 correspond to 11 to 19 in FIGS. 1 and 2. is doing.
[0039]
The present embodiment is an example of an optical path right angle conversion type optical module in which the optical fiber 26 is fixed to the transparent optical connector ferrule 25 and the end portion is polished by 45 °. The optical fiber 26 is inserted into the optical connector ferrule 25 from the lateral direction. A part of the optical connector ferrule 26 is cut away, so that the lower surface of the tip of the optical fiber 26 is exposed. The exposed portion of the lower surface is in contact with the mounting substrate 21 and the transparent contact resin 24.
[0040]
Here, the guide pins that define the positional relationship between the mounting board 21 and the optical connector ferrule 25 are omitted, but positioning is performed through the guide pins in the vertical direction in the figure, or the mounting board 21 and the optical connector ferrule 25 are built in. It shall be positioned by the meshing mechanism.
[0041]
FIG. 4B is a cross-sectional configuration diagram when the connector type optical module of the present embodiment shown in FIG. At this time, the substrate thickness of the drive IC 28 is 300 μm, the recess thickness of the mounting substrate 21 is 180 μm, the substrate thickness of the optical semiconductor element 23 is 100 μm, the height of the transparent contact resin 24 is 60 μm, and the projection thickness of the mounting substrate 21 is If it is 320 micrometers, it will become the same optical positional relationship as above-mentioned embodiment of FIG. However, since the optical coupling distance becomes longer by the thickness of the clad of the optical fiber 26, it is necessary to consider this. The total thickness of the optical fiber 26 (outer diameter 125 μm) and the optical connector ferrule 25 (for example, optical fiber upper part thickness 50 μm) is totaled to realize an optical module having a thickness of about 500 μm.
[0042]
As described above, with such a thin optical module, it is possible to mount an optical interface between the heat sink on the backside of the LSI and the interposer substrate, and light can be sensed as if an optical terminal was provided instead of an electrical terminal. A wiring package can be constructed. Even if the LSI chip is thinned to about 250 μm for heat dissipation, an optical interface can be mounted between the heat sink and the interposer substrate by applying a slight cavity (digging) process (for example, 300 μm) to the interposer substrate. Is possible.
[0043]
(Third embodiment)
FIG. 5 relates to the improvement of each of the embodiments described above, and is an implementation in which the distance between the surface of the optical semiconductor element and the end face of the optical fiber is always kept constant regardless of the error in the substrate thickness of the optical semiconductor element. It is a form.
[0044]
In FIG. 5, 31 to 39 correspond to 11 to 19 in FIG. Further, in the figure, 40 is a TAB (Tape Automated Bonding) tape, 41 is a bump lead by a metal wiring of the TAB tape, and 42 is an embedded mold resin (epoxy resin or the like), which is provided on the optical semiconductor element 33 of the TAB tape 40. A portion where the transparent contact resin 34 is formed is previously perforated. Further, a hole is also made in advance in the portion of the mounting substrate 31 where the optical semiconductor element is mounted.
[0045]
In this embodiment, first, the active region side of the optical semiconductor element 33 is mounted on the TAB tape 40 and then the transparent contact resin 44 is formed on the optical semiconductor element active portion. Next, after the TAB tape 40 is mounted on the mounting substrate 31 so that the position of the optical semiconductor element 33 is aligned, a mold resin 42 is embedded in the portion where the optical semiconductor element 33 is located, and the optical semiconductor element 33 is fixed by molding. Finally, the bump lead 41 is fixed to the pad of the driving IC 38 by bonding (thermocompression bonding, ultrasonic bonding, etc.).
[0046]
Here, if the height of the transparent contact resin 34 is set to 60 μm and the thickness of the TAB tape 40 is set to 40 μm, even if the substrate thickness of the optical semiconductor element 33 is shifted by several tens of μm, the same light as in the above-described embodiment is used. Contact relationship can be realized. In addition, this embodiment has an advantage that mass production is possible by a tape carrier process.
[0047]
(Modification)
The present invention is not limited to the above-described embodiments. For example, as a material for the mounting substrate, a material such as ceramic, metal, or resin material may be determined in consideration of electrical characteristics, thermal characteristics, mechanical characteristics, and the like. Further, although it has already been described that the optical semiconductor element can be implemented in the same manner even if it is a light receiving element, it is needless to say that an optical semiconductor element of a material system different from the above-described embodiment may be used. .
[0048]
In the embodiment, the mounting substrate is provided with a recess for mounting the element so that the tip of the optical fiber is positioned between the surface of the optical semiconductor element and the top of the transparent contact resin. You may make it provide the convex part which touches in a mounting board | substrate. If the height of the convex portion is slightly higher than the substrate thickness of the optical semiconductor element, the same effect as that obtained when the concave portion is provided can be obtained. In the embodiment, the guide pin and the guide hole are provided so that the tip of the optical fiber is aligned with the active region of the optical semiconductor element. However, the guide mechanism is not limited thereto, and can be positioned with respect to the optical axis direction and the vertical direction. If it is.
[0049]
In addition, various modifications can be made without departing from the scope of the present invention.
[0050]
【The invention's effect】
As described above in detail, according to the present invention, a connector type optical module having a very thin and simple configuration can be realized, and the optical technology can be used for mounting that requires space-saving mounting such as wiring between LSI chips. This makes it possible to introduce the system, thereby promoting the significant performance improvement of various information communication devices.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a schematic configuration of a connector type optical module according to a first embodiment.
2A and 2B are a plan view and a cross-sectional view showing a schematic configuration of the connector type optical module according to the first embodiment.
FIG. 3 is a schematic diagram for explaining an operation principle of the connector-type optical module according to the first embodiment.
FIG. 4 is a cross-sectional view showing a schematic configuration of a connector type optical module according to a second embodiment.
FIG. 5 is a cross-sectional view showing a schematic configuration of a connector type optical module according to a third embodiment.
[Explanation of symbols]
11, 21, 31... Optical element mounting substrate 12, 32... Guide hole 13.23.33 .. optical semiconductor element 14, 24, 34... Transparent contact resin 15, 25, 35 ... optical connector ferrule 16, 26, 36. Fibers 17, 37 ... guide pins 18, 28, 38 ... drive ICs
19, 29, 39 ... bonding wire 40 ... TAB tape 41 ... bump lead 42 ... mold resin

Claims (4)

A transparent contact resin selectively provided on the active region of the optical semiconductor element having a light emitting or receiving function;
Means for positioning the tip of the optical fiber so that the tip of the optical fiber is located between the surface of the optical semiconductor element and the top of the transparent contact resin;
Means for positioning the tip of the optical fiber such that the tip of the optical fiber is aligned with the active region of the optical semiconductor element;
A connector-type optical module comprising: A mounting substrate on which an optical semiconductor element having a light emitting or receiving function is mounted;
Comprising a transparent contact resin selectively provided on an active region of the optical semiconductor element, an optical connector for positioning and holding an optical fiber, and mechanically positioned and attached to the mounting substrate,
The mounting substrate and the optical connector are positioned with respect to the optical axis direction and the vertical direction by a guide mechanism so that the tip of the optical fiber is aligned with the active region of the optical semiconductor element, and the tip of the optical fiber is A connector-type optical module characterized by being positioned with respect to an optical axis direction by an abutting portion so as to be positioned between a surface of the optical semiconductor element and a top portion of the transparent contact resin. 3. The connector type optical module according to claim 1, wherein the shape of the transparent contact resin is a hemispherical dome, and a top portion of the hemispherical dome is a contact portion with a tip of the optical fiber. 3. The connector type optical module according to claim 1, wherein a protective film made of an oxide film or a nitride film is formed on the surface of the optical semiconductor element, and a silicone resin is used as the transparent contact resin.

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