JPH11125751A - Optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical module which is capable of mounting an optical element with satisfactory positional accuracy and easily and is excellent in productivity and whose mounting reliability is high by mounting a flip chip. SOLUTION: This optical module is provided with a groove 4 being for mounting an optical fiber 2, a substrate 1 which has an optical element mounting part on which an optical element positioning member 5 and connecting pads 6 are formed on its upper surface and has the optical fiber 2 mounted in the groove 4 and has electrode pads 9 on its lower surface and an optical element 3 which is to be mounted on the optical element mounting part while being allowed to abutt its one corner on the optical element position member 5 and to align its optical axis to that of the optical fiber 2 and is an optical module in which the optical element positioning member 5 is constituted of a pedestal part 5a and a first side wall 5b and a second side wall 5c and the connection pads 6 are formed at positions where are shifted by one fourth-one half of the size of the electrode pad 9 in the direction of the optical element positioning member 5 with respect to the positions of the electrode pads 9. Thus, the optical element 3 can be easily mounted with satisfactory positional accuracy.

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 an optical signal in an optical communication system or a computer / exchanger, etc., and a mounting method thereof, and more particularly, to an optical module capable of easily performing high-accuracy alignment of optical elements. And its mounting method.

[0002]

2. Description of the Related Art In an optical signal transmission system such as an optical communication system or a computer / exchanger, a light transmission path such as an optical fiber or an optical waveguide and a light transmission element such as a light emitting element such as a semiconductor laser or a light receiving element such as a photodiode are used. An optical module in which elements are connected with high positional accuracy is used. In such an optical module, precise optical axis alignment between the light transmission path and the optical element is required.To eliminate the need for manual optical axis adjustment for this, the optical element must be solder bumped to the substrate. There has been proposed a passive alignment method in which a so-called flip-chip mounting is performed via self-alignment, and positioning is performed by self-alignment using surface tension when a bonding ball such as a solder bump is melted.

When an optical element is mounted on a substrate by such a passive alignment method, the height of a core portion, which is an optical signal transmission portion of an optical fiber or an optical waveguide, and the height of a light receiving / emitting portion of the optical element are set on the substrate. For example, a method of adjusting the height of the optical element by applying a certain pressure when mounting the optical element and crushing the bonding ball is used.

[0004] In addition, in order to accurately and easily perform positioning in the height direction, for example, "Assembly and Wiring T"
echnologies in PLC Platforms for Low-Cost and High
-Speed Applications "IEEE 1997 Electronic Componen
ts and Technology Conference Proceedings (ETCT 199
7), p632 is provided with a step called a silicon terrace having a predetermined height on the silicon substrate, and when the pressure in the direction of crushing the bonding ball is applied to the optical element, the lower surface of the optical element is brought into contact with this silicon terrace. Accordingly, a structure and a method for performing alignment in the height direction of the optical element have been proposed.

[0005] Also, "Wafer Scale Photonic-die Attach"
ment "ETCT 1997, p763, proposes a structure and method for performing passive alignment between an optical fiber and a semiconductor laser using a positioning step. According to this, an optical fiber mounting portion for an optical module is proposed. When mounting a semiconductor laser on a silicon V-groove substrate, the direction of the optical axis of the optical fiber is set in the x direction, the direction parallel to the top surface of the optical fiber is parallel to the y direction, and the direction perpendicular to the top surface of the substrate (height direction) is the z direction. And a step (forward pedestal) for positioning the semiconductor laser in the x direction with respect to the optical fiber and y
Step (left pedestal) for positioning in the direction and z
A step (stand-off) for positioning in the direction and a solder layer for bonding are provided on the substrate, and the optical axis alignment is performed by mechanically pressing the semiconductor laser against these steps. That is, the semiconductor laser is first placed on the standoff, and the position in the x direction is determined by striking the forward pedestal, and then the position in the y direction is determined by striking the left pedestal.
Thereafter, while holding down and fixing the semiconductor laser, the solder layer for joining is melted by local heating to join the semiconductor laser to the substrate, thereby realizing high-precision passive alignment.

[0006]

However, according to the optical modules using the conventional passive alignment method as described above, pressure is applied in the direction of crushing the bonding ball when mounting the optical element. The ball has a drum-shaped or barrel-shaped shape with a thicker central part. When such a drum-shaped or barrel-shaped ball is mounted on an optical element, it can be mounted on a substrate when a thermal load such as a temperature cycle is applied. The mechanical stress is concentrated on the contact portion between the ball and the ball, and the ball is broken or peeled off, so that there is a problem that the reliability of mounting is lowered.

In an optical module, generally, several tens to several hundreds of optical elements are mounted on one substrate. According to the method proposed in the above-mentioned "Wafer Scale Photonic-die Attachment", It is necessary to perform solder bonding by local heating while individually holding optical elements, and it takes about 15 seconds to bond one optical element, which causes a problem of low productivity when manufacturing an optical module. There was a point.
In addition, advanced local heating technology is required to prevent the solder of the mounted optical element from re-melting during subsequent mounting of other optical elements and displacing the mounted optical element. In addition, since there is a limit in shortening the mounting distance between optical elements, there is a problem that there is a limitation in mounting optical elements with high density.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art. It is an object of the present invention to enable an optical element to be mounted with high positional accuracy and easily by flip-chip mounting. An object of the present invention is to provide an optical module having excellent mounting properties and high mounting reliability.

[0009]

An optical module according to the present invention has, on an upper surface thereof, a groove for mounting an optical fiber or an optical waveguide for connecting an optical fiber, and an optical element located at one end of the groove or the optical waveguide. A substrate having an optical element mounting portion on which a positioning member and a plurality of connection pads are formed; an optical fiber mounted in the groove or connected to the optical waveguide; a quadrangular shape having a plurality of electrode pads on a lower surface; Then, one corner is brought into contact with the optical element positioning member, the electrode pad and the connection pad are connected by a conductive interconnecting member, and the optical element is mounted by aligning the optical axis with the optical fiber or the optical waveguide. An optical module comprising an optical element mounted on a portion, wherein the optical element positioning member includes a pedestal section on which a lower surface of the optical element is mounted, and the optical fiber or the optical fiber. A first side wall and a second side wall having a side surface parallel to and perpendicular to the optical axis of the waveguide, and wherein the connection pad has one corner of the optical element brought into contact with the optical element positioning member; Are formed at positions shifted by 1/4 to 1/2 of the size of the electrode pad in the direction of the optical element positioning member with respect to the position of the electrode pad.

Further, in the optical module of the present invention, in the optical module having the above-mentioned structure, the conductive interconnecting member has a cross-sectional area at a central portion smaller than a cross-sectional area at a connection portion between the electrode pad and the connection pad. It is characterized by the following.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the optical module of the present invention,
An optical element positioning member and a plurality of connection pads are formed on an optical element mounting portion located on one end side of an optical fiber mounting groove or an optical waveguide for connecting an optical fiber on the upper surface of the substrate. And a first side wall having a side surface perpendicular to the upper surface of the substrate and parallel to the optical axis of the optical fiber or the optical waveguide, and the side surface of the optical element parallel to the optical axis being abutted. And a second side wall having a top surface of the substrate and a side surface perpendicular to the optical axis of the optical fiber or the optical waveguide, and a side surface of the optical element perpendicular to the optical axis being in contact with the second side wall. The position of the plurality of electrode pads on the lower surface of the optical element in a state where one corner of the optical element is in contact with the optical element positioning member is そ れ ぞ れ of the size of the electrode pad in the direction of the optical element positioning member.
Since it is formed at a position shifted by 〜, the mounting position of the optical element can be accurately defined by the optical element positioning member, and the conductive interconnection such as a solder ball for connecting the electrode pad and the connection pad. Due to the tension of the member, one corner of the optical element can be brought into close contact with the optical element positioning member, and as a result, the optical element can be mounted with extremely high positional accuracy, and the optical axis of the optical element can be connected to the optical fiber or the optical fiber. The alignment of the optical waveguide with the optical axis can be performed accurately and easily.

According to the optical module of the present invention, the cross-sectional area of the conductive interconnecting member at the central portion is larger than the cross-sectional area of the electrode pad of the optical device and the connecting portion with the connection pad of the optical device mounting portion of the substrate. In the case of a so-called drum-shaped shape with a narrow central part, the tension at the time of connecting the electrode pad and the connection pad is increased, and the optical element is more reliably brought into contact with the optical element positioning member. In addition to this, the mechanical stress generated when a thermal load such as a temperature cycle is applied after mounting the optical element is concentrated at the center of the conductive interconnect member, and the conductive interconnect Destruction of the member and peeling from the electrode pad or the connection pad are eliminated, and the mounting reliability of the optical element can be improved.

Further, according to the optical module of the present invention,
When mounting optical elements, there is no need to locally heat the individual optical elements while holding them down as in conventional optical modules. Since the optical elements are placed with a conductive interconnection member such as a solder ball interposed therebetween, and then all the optical elements can be connected and mounted simultaneously with high alignment accuracy by performing a batch solder reflow. By flip-chip mounting, the optical element can be mounted easily and with high positional accuracy, the productivity is excellent, the optical element can be mounted at high density, and the mounting reliability is high.

Hereinafter, an optical module according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view showing an example of an embodiment of an optical module according to the present invention, and FIG. 2 is a sectional view showing a part thereof. For easy understanding, FIG. 1 shows a partially transparent state, and FIG. 2 shows a partially broken and omitted state.

1 and 2, reference numeral 1 denotes a substrate made of a silicon substrate or various ceramic substrates, etc., 2 denotes an optical fiber mounted on the substrate 1, and 3 denotes a semiconductor mounted on an optical element mounting portion of the substrate 1. An optical element such as a light emitting element such as a laser or a light receiving element such as a photodiode. Note that a plurality of optical fibers 2 and optical elements 3 may be mounted according to the specifications of the optical module.

Reference numeral 4 denotes a groove for mounting the optical fiber 2 such as a V-groove formed on the upper surface of the substrate 1, and 5 denotes an optical element positioning formed on an optical element mounting portion located at one end of the groove 4 on the upper surface of the substrate 1. Reference numeral 6 denotes a plurality of connection pads formed on the optical element mounting portion. 7 is connected to the optical element 3 via the connection pad 6,
It is an electric wiring for transmitting an electric signal between the optical element 3 and an external electric circuit and for supplying power and grounding. These electric wires 7 may be formed in a multilayer structure inside the substrate 1.
Reference numeral 8 denotes an optical element positioning assisting member for assisting the positioning of the optical element 3 formed on the optical element mounting portion, and is provided as necessary according to the specifications of the optical element 3 and the optical module.

The connection pad 6 may be formed only for positioning and mounting the optical element 3 as described later, without making an electrical connection with the optical element 3. The optical fiber 2 mounted on the groove 4 of the substrate 1 and the optical element 3 mounted on the optical element mounting portion of the substrate 1 face the core 2a of the optical fiber 2 and the optical waveguide 3a of the optical element 3. As a result, the optical fibers are mounted so that their optical axes are aligned. On the upper surface of the substrate 1 between the optical fiber 2 and the optical element 3, an optical waveguide (not shown) for connecting the optical fiber 2 to the optical element 3 is provided. ) Is formed, and the optical element 3 is aligned with the optical waveguide.
May be mounted. At this time, the optical fiber 2 may not be mounted in the groove 4 and may be connected to the optical waveguide on the substrate 1 using an auxiliary substrate for mounting the optical fiber.

The optical element 3 has a quadrangular shape and has a plurality of electrode pads 9 on the lower surface. One corner of the optical element 3 is brought into contact with the optical element positioning member 5 so that the electrode pad 9 and the optical element mounting portion are formed. The connection pad 6 is mounted on the optical element mounting portion by connecting the optical fiber 2 or the optical waveguide with the optical axis by connecting the connection pad 6 with a conductive interconnection member 10 made of a solder ball, a low melting point brazing material or the like. The electrode pad 9
When connected to the connection pad 6 that is not connected to an external electric circuit or the like, the connection pad 6 may not contribute to electrical connection.

Here, the optical element positioning member 5 includes a pedestal portion 5a on which the lower surface of the optical element 3 is mounted, and a substrate 1
A first side wall 5b having a side surface perpendicular to the upper surface and parallel to the optical axis of the optical fiber 2 or the optical waveguide for connecting the optical fiber, and a side surface of the optical element 3 parallel to the optical axis,
It has a top surface and a side surface perpendicular to the optical axis of the optical fiber 2 or the optical waveguide for connecting the optical fiber, and the side surface of the optical element 3 perpendicular to the optical axis (the side surface on the input / output side of the optical signal) is brought into contact. And the second side wall 5c. By providing such an optical element positioning member 5 and bringing one corner of the optical element 3, preferably one corner on the connection side with the optical fiber 2 or the optical waveguide for connecting the optical fiber, into contact therewith, the optical fiber 2 or The optical axis direction of the optical waveguide for connecting the optical fiber is the x direction,
When the direction perpendicular to the upper surface of the substrate 1 and the direction perpendicular to the upper surface of the substrate 1 perpendicular to the x direction and the y direction is the z direction, the second side wall 5c positions the optical element 3 in the x direction. Is positioned in the y direction by the first side wall 5b.
The positioning in the z direction can be accurately performed by the pedestal portion 5a, and the optical element 3 and the optical fiber 2 or the optical waveguide for connecting the optical fiber can be accurately aligned and mounted.

Such an optical element positioning member 5 is formed, for example, by processing a silicon substrate, or a material for forming an optical waveguide, for example, quartz glass, siloxane polymer, polyimide or the like, or epoxy resin, benzocyclobutene, or the like. It may be formed of an insulating resin such as polynorbornene or a metal such as copper, gold, or silver. The position, the height of the pedestal portion 5a, and the position of the side surface of the first side wall 5b are determined by the optical axis of the optical element 3 after mounting and the optical axis of the optical fiber 2 or the optical waveguide for connecting the optical fiber. What is necessary is just to set according to the position which matches.

The position of the side surface of the second side wall 5c defines the gap between the optical element 3 and the optical fiber 2 or the optical waveguide for connecting the optical fiber. In this case, the optical element 3 may be damaged, and if the gap is too large, the luminous coupling efficiency deteriorates. Generally, a thickness of about 2 to 10 μm is desirable.

Base 5a, first side wall 5b, second side wall 5c
May be large enough that the respective ends of the optical element 3 do not come into contact with each other enough to come off, but chipping occurs due to chipping in dicing when the optical element 3 is cut from a wafer to a chip. Therefore, it is necessary to set the size so that the chipping does not cause a problem. Generally, a size of about 5 μm is sufficient.

When the optical element positioning assisting member 8 is provided for accurately positioning the optical element 3 in parallel with the upper surface of the substrate 1, the optical element positioning member 5 is placed at a position where the optical element 3 can be stably supported. What is necessary is just to form suitably like the optical element positioning member 5 so that it may become the same height as the pedestal part 5a.

The connection pads 6 formed on the optical element mounting portion on the upper surface of the substrate 1 are electrically connected to the respective connection pads 6 when one corner of the optical element 3 is in contact with the optical element positioning member 5. Relative to the position of the electrode pad 9 connected by the sexual interconnecting member 10, the direction of the optical element positioning member 5, preferably, the upper surface of the pedestal 5 a and the contact side surface of the first side wall 5 b in the optical element positioning member 5. The electrode pad 9 is formed at a position shifted by a distance corresponding to 1/4 to 1/2 of the size of the electrode pad 9 in the direction of the origin where the contact side surface of the second side wall 5c intersects. The connection pad 6 and the electrode pad 9 are connected by the conductive interconnecting member 10 to the optical element 3 by the tension of the conductive interconnecting member 10, that is, the surface tension of the conductive interconnecting member 10 at the time of melting. For electrodes A pulling force acts in the direction of the optical element positioning member 5 and downward (in a direction close to the upper surface of the substrate 1) so that the pad 9 is located directly above the connection pad 6, and such a self-alignment effect is obtained. As a result, the optical element 3 can be brought into close contact with the optical element positioning member 5, and the optical element 3 can be accurately positioned.

Moreover, according to such a mounting structure of the present invention, even when a plurality of optical elements 3 are mounted, the connection pads 6 and the electrode pads 9 are formed on the optical element mounting portion of the substrate 1. The optical element 3 is placed with, for example, a solder ball interposed therebetween as the conductive interconnecting member 10, and then, a batch solder reflow (solder melting) is performed using a furnace, a hot plate, or the like, thereby reducing the conventional mounting method. In addition, all the optical elements 3 can be connected and mounted simultaneously with high alignment accuracy at a low temperature, and the optical elements can be mounted easily and with high positional accuracy by flip-chip mounting, and the optical elements 3 can be mounted. In such a case, it is not necessary to use an advanced local heating method while individually pressing and fixing the optical elements 3 as in the conventional optical module, so that the productivity is excellent, and the position of the optical element 3 It without the fit member 5 deteriorates the positional accuracy of the optical element 3 is deformed, it is possible to high-density mounting of the optical element, the reliability of the mounting is high light module.

The connection pad 6 is connected to the electrode pad 9 as described above.
When formed at a position displaced in the direction of the optical element positioning member 5 with respect to the optical element positioning member 5, if the amount of displacement is less than 1/4 of the size of the electrode pad 9, sufficient tension by the conductive interconnecting member 10 is applied. There is a tendency that it is difficult to obtain the optical element 3 in close contact with the optical element positioning member 5 and to correct the position to an accurate position by the self-alignment effect.

On the other hand, if the amount of displacement of the connection pad 6 exceeds one half of the size of the electrode pad 9, the conductive interconnection member 10 will be in sufficient contact with the connection pad 6 and the electrode pad 9 to be good. It tends to be difficult to make a simple connection.

The connection pads 6 and the electrode pads 9
May be a polygonal shape such as a quadrangle or a hexagon other than the circular shape as shown in the figure, and the amount of positional deviation between the connection pad 6 and the electrode pad 9 may vary in the direction of the optical element positioning member 5. What is necessary is just to set with the deviation | shift amount on the going straight line.

Further, the conductive interconnection member 10 is connected to the electrode pad 9 of the optical element 3 having the cross-sectional area at the center at both ends.
If the cross-sectional area of the connection portion with the connection pad 6 on the substrate 1 is smaller than the cross-sectional area of the connection portion, the conductive interconnection member 10 connects the electrode pad 9 with the conductive interconnection member 10. The tension at the time of connection with the pad 6 is increased, so that the optical element 3 can be more reliably brought into contact with the optical element positioning member 5, and a thermal load such as a temperature cycle is applied after the optical element 3 is mounted. The mechanical stress generated when the conductive interconnect member 10 is concentrated at the central portion of the conductive interconnect member 10, causing the conductive interconnect member 10 to break or from the electrode pad 9 or the connection pad 6 of the conductive interconnect member 10. Is eliminated, and the mounting reliability of the optical element 3 can be improved.

In order to form the conductive interconnection member 10 in such a shape, for example, a cylindrical or truncated cone formed by linearly connecting the electrode pads 9 and the connection pads 6 when mounting the optical element 3 is used. The volume of the conductive interconnect member 10 may be smaller than the volume.

[0031]

Next, a specific example in which an optical module of the present invention as shown in FIG. 2 is manufactured will be described with reference to a case where a silicon substrate is used as the substrate 1.

First, a silicon substrate 1 on the surface of which a silicon thermal oxide film made of SiO ₂ is formed, a resist pattern is formed by a well-known photolithography method, and using this as a mask, SiO ₂ is formed by HF (hydrofluoric acid). _Two
Is etched, and KOH is used as a mask with the SiO ₂ film as a mask.
(Potassium hydroxide) anisotropic etching,
A V-groove, which is a groove 4 for mounting an optical fiber, was formed in the silicon substrate 1.

Thereafter, the SiO ₂ film used as a mask was removed, and a SiO ₂ film was formed again on the surface of the silicon substrate 1 to a thickness of about 2 μm by a known thermal oxidation method.

Next, after a Cr (0.03 μm) / Au (2 μm) film is formed on the upper surface of the silicon substrate 1 by a sputtering method, a predetermined pattern is formed by a photolithography method to form a circular connection pad having a diameter of 60 μm. 6 and electric wiring 7 were formed. At this time, the position of the connection pad 6 was shifted as described above.

Next, a polyimide resin is applied to the upper surface of the substrate 1 by a spin coating method, and is then applied at 400 ° C. in a nitrogen atmosphere.
A 60-μm-thick polyimide layer was formed by curing for 1 hour. Thereafter, a Cu (1 μm) film is formed on the polyimide layer by a sputtering method, and then the pedestal portion 5 of the optical element positioning member 4 is formed by a photolithography method.
A pattern having a shape a was formed, and the polyimide layer was etched by 60 μm by dry etching using the pattern as a mask.

Further, this Cu pattern is formed on the first side wall 5b and the second side wall 5c by photolithography again.
With a pattern of the shape, using these as a mask, the polyimide layer is etched by 20 μm by a dry etching method,
Thus, the optical element positioning member 5 including the pedestal portion 5a having a height of 40 μm and the first side wall 5b and the second side wall 5c having a height of 20 μm on the pedestal portion 5a is formed on the optical element mounting portion. did.

The electrode pad 9 of the optical element 3 having the circular electrode pad 9 having a diameter of 40 μm on the lower surface is provided with a conductive interconnecting member 10 having a volume of about 12600 μm ³ (40 μm diameter ×
A solder (Pb: 97 / Sn: 3) ball having a diameter of about 50 μm is adhered using a solder (Pb: 97 / Sn: 3) layer having a thickness of 10 μm, and then each solder ball is connected to each connection pad 6.
The optical element 3 was mounted on the optical element mounting portion while being in contact with the optical element positioning member, and solder reflow was performed to mount and mount the optical element 3.

At this time, the volume of the conductive interconnection member 10 composed of the solder layer and the solder ball is about 78050 μm ³ ,
Since the volume of the truncated cone formed by the electrode pad 9 having a diameter of 0 μm, the connection pad 6 having a diameter of 60 μm, and the distance between them (the height of the pedestal portion 5a) is 40 μm, the volume is smaller than about 81640 μm ^3. The shape of the member 10 was a drum shape with a constricted central portion, and the optical element 3 was brought into close contact with the optical element positioning member 5.

When a light emitting optical element is mounted as the optical element 3, the mounted optical element 3 and the optical fiber 2
The coupling loss was measured, and it was confirmed that the components were mounted with a positional accuracy within ± 1 μm. Also, the optical element 3
As the reliability evaluation of this part mounted with the optical fiber 2 and
When a constant temperature and humidity test was performed under the conditions of 85 ° C / 85% RH,
The change in the intensity of the emitted light after elapse of 600 hours was within ± 1 dB, and sufficient reliability was obtained. No abnormality was confirmed in the solder connection.

The above is merely an example of the embodiment of the present invention, and the present invention is not limited to the embodiment. Various changes and improvements may be made without departing from the gist of the present invention. No problem.

For example, in the above example, the optical element positioning assisting member 8 is composed of only the pedestal portion. However, the first side wall of the optical element positioning member 5 is also used for auxiliary positioning of the optical element. What corresponds to 5b and the 2nd side wall 5c may be formed.

Although a silicon substrate is used as the substrate in the specific example, a ceramic substrate, a multilayer ceramic substrate, or the like may be used. The solder having a composition of Pb: 60 / Sn: 40 is used as a conductive interconnecting member. Mono and Au: 80 / S
n: 20, Au / Ge or the like may be used.

[0043]

As described above, according to the optical module of the present invention, the optical element is mounted on the optical element mounting portion located at one end of the optical fiber mounting groove or the optical fiber connecting optical waveguide on the upper surface of the substrate. And a first side wall having a side surface perpendicular to the upper surface of the substrate and parallel to the optical axis of the optical fiber or the optical waveguide, and the side surface of the optical element parallel to the optical axis being abutted. And an optical element positioning member having a substrate upper surface and a side surface perpendicular to the optical axis of the optical fiber or the optical waveguide, and a second side wall to which the side surface of the optical element perpendicular to the optical axis is abutted, In addition, with respect to the positions of the plurality of electrode pads on the lower surface of the optical element in a state where one corner of the optical element is brought into contact with the optical element positioning member, the size of each of the connection pads is set in the direction of the optical element positioning member. Sano 1
Since the optical element is formed at a position shifted by ４ to ２, the mounting position of the optical element can be accurately defined by the optical element positioning member, and the conductive interconnection member for connecting the electrode pad and the connection pad can be formed. Due to the tension, one corner of the optical element can be brought into close contact with the optical element positioning member, and as a result, the optical element can be mounted with extremely high positional accuracy. The alignment with the optical axis of the optical waveguide can be performed accurately and easily.

Further, according to the optical module of the present invention, the cross-sectional area of the conductive interconnecting member at the center thereof is larger than the cross-sectional area of the electrode pad of the optical device and the connecting portion with the connection pad of the optical device mounting portion of the substrate. When the optical element is smaller, the tension at the time of connecting the electrode pad and the connection pad is increased, so that the optical element can be more reliably brought into contact with the optical element positioning member. The mechanical stress that occurs when a thermal load such as a cycle is applied will be concentrated in the narrow central part of the conductive interconnect member,
Destruction of the conductive interconnect member and peeling from the electrode pad or the connection pad are eliminated, and the mounting reliability of the optical element can be improved.

Further, according to the optical module of the present invention,
The optical element is mounted on the optical element mounting portion of the substrate with the conductive interconnect member interposed between the connection pad and the electrode pad, and then the conductive interconnect member is melted all at once. Optical elements can be connected and mounted with high alignment accuracy at the same time, so that the optical elements can be mounted easily and accurately with flip-chip mounting. An optical module that is superior in productivity to that in which advanced local heating is performed while individually pressing and fixing optical elements, enables high-density mounting of optical elements, and has high mounting reliability.

As described above, according to the present invention, it is possible to provide an optical module which can easily and easily mount an optical element by flip-chip mounting, has high productivity, and has high mounting reliability. did it.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of an embodiment of an optical module according to the present invention.

FIG. 2 is a sectional view of a part of FIG.

[Explanation of symbols]

 1 ······················ Optical fiber 2a ····· Core part (optical axis) 3 ······ Optical element 3a ······ Optical axis 4 ····· Optical fiber mounting Grooves for optical element 5 Optical element positioning member 5a Base 5b First side wall 5c Second side wall 6 Connection pad 9 Electrode pad 10 Conductive interconnect

Claims (2)

[Claims] An optical fiber mounting groove or an optical fiber connecting optical waveguide, and an optical element positioning member and a plurality of connection pads located at one end of the groove or the optical waveguide are formed on an upper surface. A substrate having an optical element mounting portion, an optical fiber mounted in the groove or connected to the optical waveguide, formed in a rectangular shape, having a plurality of electrode pads on a lower surface, and one corner corresponding to the optical element positioning member. And an optical element mounted on the optical element mounting portion in such a manner that the electrode pad and the connection pad are brought into contact with each other to connect the electrode pad and the connection pad by a conductive interconnection member, and the optical axis is aligned with the optical fiber or the optical waveguide. In the optical module, the optical element positioning member includes a pedestal portion on which a lower surface of the optical element is mounted, and a side surface and a vertical side parallel to an optical axis of the optical fiber or the optical waveguide. A first side wall having a surface and a second side wall having a surface, and the connection pad is provided with respect to a position of the electrode pad in a state where one corner of the optical element is in contact with the optical element positioning member. 1/4 of the size of the electrode pad in the direction of the optical element positioning member
An optical module formed at a position shifted by １ ／. 2. The optical module according to claim 1, wherein a cross-sectional area of a center portion of the conductive interconnect member is smaller than a cross-sectional area of a connection portion between the electrode pad and the connection pad.