JP2001215370A - Optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical module that is capable of miniaturization, that is excellent in productivity and inspectability, and that is suitable for an optical transmitting and receiving module adaptable to the future high frequency processing. SOLUTION: The optical module M1 is such that, in a groove 31 formed on an arraying substrate 30, there are arranged a non-aligning mounting substrate 10 on which a light emitting element 1 and an optical fiber 3a to be optically connected to the light emitting element 1 at one end are disposed, a ferrule 3b for holding the other end of the optical fiber 3a, and a chip carrier 20 on which a light receiving element 2 is disposed for the purpose of monitoring the outgoing beam of the light emitting element 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an optical communication system,
The present invention relates to an optical module used for an optical measuring instrument, an optical fiber sensor, and the like. In particular, the present invention relates to an optical module which can be reduced in size, has excellent productivity, can cope with a higher frequency, and is suitable for a transmitting and receiving optical module.

[0002]

2. Description of the Related Art In recent years, in optical modules used for optical communication systems and the like, attention has been paid to a so-called passive alignment technology, which is an alignment-free mounting technology using a high-precision silicon platform for the purpose of reducing the size, thickness, and cost. Have been. In particular, a surface-mount type optical module using this passive alignment technology and capable of performing solder reflow comparable to that of an electronic component has attracted particular attention as an optical module that can efficiently perform steps up to board mounting.

FIG. 4 shows the structure of such a conventional surface mount optical module J1. A silicon platform (unaligned mounting substrate) 10 on which a light emitting element 1 as a laser diode is mounted is mounted on a surface mounting type package 40 made of ceramics or the like, and a (naked) optical fiber 3a constituting a fiber stub 3 is provided. And the light emitting element 1 are mounted by passive alignment. That is, the optical fiber mounting V-groove and the light emitting element mounting electrode (or positioning marker), which are designed in advance so that the core central axis of the optical fiber 3a coincides with the central axis of the active layer of the light emitting element 1, are high. By simply mounting the optical fiber 3a and the light emitting element 1 on the non-aligned mounting substrate 10 manufactured with high precision, the positioning of both is performed. The light receiving element 2 of the monitoring photodiode for monitoring the backward light output from the light emitting element 1 is mounted on a separate chip carrier 20, and is aligned and fixed on a package 40. In addition, 3b in the figure
Is a ferrule constituting the fiber stub 3 and holds an optical fiber 3a.

Further, as shown in FIG. 5A, in order to further reduce the cost, the light emitting element 1 and the monitor receiving light are mounted on the alignmentless mounting substrate 50 without using the above-mentioned surface mounting type package. An optical module J2 in which all components such as an element 2 and a fiber stub are mounted and collectively transfer-molded with resin has been proposed.

In such an optical module J2, in order to ensure long-term reliability during molding and after mounting, FIG.
As shown in FIG. 5C, a deep V-groove 51 for holding the outer diameter of the fiber stub 3 and a shallow V-groove 52 for holding the optical fiber 3a as shown in FIG. It is considered that a structure in which the device is manufactured and mounted on a platform is preferable (see Japanese Patent Application Laid-Open No. H11-326713).

[0006]

However, the configuration of the optical module has the following problems. First, in the optical module J1 of FIG. 4, not only is the configuration of the package 40 complicated, but also because the manufacturing accuracy of the package 40 is not sufficient, the optical fiber 3a of the
However, there is a problem that the monitor light receiving element 2 must be aligned because the monitor light receiving element 2 is separately mounted on the chip carrier 20 due to microbending (small bending) in the chip.

In the optical module J2 shown in FIG. 5, the optical fiber 3a and the ferrule 3b are simultaneously connected to the non-aligned mounting substrate 5.
Since it is mounted and fixed on the substrate 0, the chip size of a substrate (silicon platform) that requires high precision increases. Furthermore, since burn-in of an optical semiconductor device is generally performed after mounting on a silicon platform, if the optical semiconductor device is defective, the silicon platform itself is also discarded. It becomes important when considering the characteristics and testability.

In the case where a surface light receiving type light receiving element is used as a monitor light receiving element, a mirror portion is formed by forming a V-groove on the surface of the substrate by anisotropic etching or by evaporating metal. However, it is necessary to adopt a configuration in which the light reflected from the mirror section is received by the light receiving element, and there is a problem that the configuration becomes extremely complicated.

Further, when high speed (higher frequency) of such an optical transmission module is required, a parasitic capacitance is increased in a configuration in which an optical semiconductor element is simply mounted directly on a silicon single crystal substrate, and particularly, a light receiving element is increased. The device cannot exhibit good light receiving characteristics. Therefore, an object of the present invention is to provide an excellent optical module that can easily mount an optical semiconductor element such as a light emitting element and a light receiving element, and is suitable for miniaturization and high frequency.

[0010]

In order to solve the above-mentioned problems, an optical module according to the present invention comprises a light emitting element and an optical fiber for optically connecting one end to the light emitting element in a groove formed in an alignment substrate. The aligned coreless mounting substrate, the ferrule holding the other end of the optical fiber, and the chip carrier provided with the light receiving element for monitoring the light emitted from the light emitting element, the chip carrier and the ferrule It is arranged so that the alignment-free mounting board is located between them.

In particular, the alignment substrate and the alignment-free mounting substrate are made of a material which can be anisotropically etched, and the grooves of the alignment substrate and the alignment-free mounting substrate are arranged by anisotropic etching. It is characterized by being formed. Further, an external electrode electrically connected to the light emitting element and the light receiving element is formed on the alignment substrate.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below in detail with reference to the drawings. The optical modules M1 and M2 schematically shown in FIGS.
The light emitting element 1 such as a semiconductor laser and one end thereof are optically connected to a groove (recess) 31 such as a V-groove formed above (naked).
A chip carrier 2 made of ceramic or the like, on which a non-aligned mounting substrate 10 on which an optical fiber 3a is disposed and a light receiving element 2 for monitoring the light output behind the light emitting element 1 are disposed on its side.
0, ferrule 3 holding the other end side of optical fiber 3a
b ((optical) fiber stub 3) are mounted and fixed in this order. In the figure, reference numeral 4 denotes a bonding wire for energizing the light emitting element 1 and the light receiving element 2.

The optical module M2 is provided on the alignment substrate 3
0, a lead terminal (external electrode) 33 electrically connected to the light emitting element 1 and the light receiving element 2 is formed, which is different from the optical module M1 in this point.

Regarding the positional relationship in the optical axis direction and the assembling method, first, the non-aligned mounting substrate 10 on which the light emitting element 1 has been previously fixed, wired, and burn-in inspected is inserted into the groove 31 of the alignment substrate 30, a marker or the like (not shown). ).

Next, the optical fiber 3a of the fiber stub 3
One end side is inserted into a V-groove 11 formed on the alignment-free mounting substrate 10 by a pressing plate (not shown) such as an adhesive and a glass plate.
Fix using Further, the outer periphery of the fiber stub 3 (the outer periphery of the ferrule 3 a) is bonded and fixed to the groove 31 of the alignment substrate 30.

Finally, the chip carrier 20 on which the light receiving element 2 is mounted in advance on its side face is bonded and fixed to the groove 31 of the alignment substrate 30. Then, the electrode 13 and the electrode 21 of the chip carrier formed on the non-aligned mounting substrate 10 and the alignment substrate 3
The electrode module 0 (not shown) is wire-bonded to complete the optical module M1.

FIG. 2 shows (a) a sectional view taken along the line AA and (b) a sectional view taken along the line BB in FIG. The positional relationship (height and horizontal direction) of each substrate and chip carrier will be described with reference to FIG. First, the alignment-free mounting substrate 10 and the chip carrier 20
Is designed such that the center of the rear output light of the light emitting element 1 and the center of the light receiving surface of the light receiving element 2 for monitoring substantially coincide with each other.

Next, the ferrule 3b which forms the fiber stub 3 with the non-aligned mounting substrate 10 comprises an optical fiber 3a which forms the fiber stub 3 is fixed to the V-groove 11 of the non-aligned mounting substrate 10, When the outer circumference of the ferrule 3 (the outer circumference of the ferrule 3b) is fixed to the groove 31 of the alignment substrate 30, the optical fiber 3a is designed at a position where a large microbend does not occur. That is, the slope 32 of the groove 31 of the alignment substrate 30 and the groove arrangement surface 12 of the alignment-free mounting substrate 10 are accurately formed, and these surfaces exactly match each other. That is, the alignment substrate 30 is brought into contact with the slope 32 of the groove 31 at an accurate position. As will be described later, if the inclined surface of the groove 31 and the groove arrangement surface of the non-aligned mounting substrate 10 are formed by anisotropic etching, it is possible to more suitably prevent the microbending of the optical fiber 3a.

FIG. 3 is a diagram for explaining a method of manufacturing the alignment-free mounting substrate 10. First, as shown in FIG. 3 (a), a substrate 10 'is prepared and a V-groove and an electrode pattern are formed on the surface thereof, and a groove pattern for forming an abutment (or fitting) inclined surface is formed on the back surface thereof. Patterning is performed using a double-sided mask aligner. As a substrate material, high-precision processing is possible by anisotropic etching with an alkaline aqueous solution, etc.
It is effective to use single crystal silicon having excellent heat dissipation.

Next, as shown in FIG.
The V-groove 11 and the electrode pattern on the front surface are formed by using a well-known semiconductor manufacturing process while covering the back surface of 0 ′.
As shown in (c), the front surface is covered, and a groove (groove arrangement surface) 12 on the rear surface is formed. At this time, regarding the groove formation, if single-crystal silicon is used for the substrate 10 ′,
Perform anisotropic etching with an aqueous alkali solution such as sodium hydroxide or potassium hydroxide. Then, as shown in FIG. 3D, if the individual chips are cut at the cutting line D by dicing at the end, the alignmentless mounting substrate 10 can be easily formed.
Can be produced.

In the optical module M1 of FIG. 1A, the alignment substrate 30 is formed of the same silicon single crystal substrate as the non-aligned mounting substrate 10, and the groove 31 is formed by performing the same anisotropic etching. Can be formed. At this time, since the crystal orientation defines the slope angle of the back surface of the alignment-free mounting substrate 10 and the groove 31 slope angle of the alignment substrate 30, the fiber stub 3 and the alignment-free mounting substrate 10 are positioned with high precision. can do. Also, the alignment substrate 30
Since the groove 31 is a simple linear concave portion, the above-described anisotropic etching may be used, or the groove 31 can be more efficiently manufactured by using machining such as dicing.

In the configuration of the optical module M1, the alignment substrate 30 is manufactured as a sub-assembly using a normal substrate, and thereafter, the component mounting portion is potted or mounted in a separately prepared package. Packaging is performed using a method such as resin molding.

Further, the optical module M shown in FIG.
In the second embodiment, a ceramic package having lead terminals (external electrodes) 33 or a structure in which the ceramic interposer for potting itself has a groove 31 like the substrate 30 for alignment may be adopted. Thereby, the configuration of the optical module can be further simplified, and the productivity of the optical module can be improved.

Further, as shown in the cross-sectional view of FIG. 2B, the height of the non-aligned mounting substrate 10 on which the light emitting element 1 is mounted and the height of the ceramic chip carrier on which the monitor light receiving element 2 is mounted are adjusted. By configuring the bonding wire 4 at substantially the same height as the surface of the surface 30, the wiring length of the bonding wire 4 can be shortened, the inductance of the wiring can be reduced, and a configuration suitable for higher frequencies can be achieved.

[0025]

As described above, according to the optical module of the present invention, a non-aligned mounting substrate such as a high-precision silicon platform on which a light emitting element and an optical fiber of a fiber stub are mounted can be made very small and simple. Can be provided.

A chip carrier on which a light-receiving element used for monitoring a light-emitting element is mounted can be formed very easily because a desired shape can be formed with high precision by, for example, ceramic powder molding. Becomes Therefore, even if the yield or mounting yield in the burn-in test after mounting the light emitting element or the monitor light receiving element itself is poor, the productivity as an optical module is not significantly affected.

Further, the alignment substrate on which these optical components including the fiber stub are mounted can be formed only by forming a simple groove such as a V-groove, so that the productivity can be improved.

By using the alignment substrate as a package material, the structure can be further simplified. In addition, since the structure is such that a ceramic chip carrier is used and the wiring length can be shortened, a high frequency operation is required. Can also be suitably handled.

[Brief description of the drawings]

FIG. 1A is a plan view (top view) schematically showing a part or all of the configuration of an optical module of the present invention, and FIG.
Is a plan view (top view) showing another optical module.

2A is a sectional view taken along line AA in FIG. 1A, and FIG. 2B is a sectional view taken along line BB in FIG.

FIG. 3 is a schematic cross-sectional view for explaining an example of a method of manufacturing an alignment-free mounting substrate constituting the optical module of the present invention.

FIG. 4 is an exploded perspective view illustrating an example of a conventional surface mount optical module.

5A is a perspective view illustrating an example of a conventional surface mount optical module, FIG. 5B is a cross-sectional view taken along line II of FIG. 5A, and FIG. 5C is a sectional view taken along line II- of FIG. It is a II line cross section.

[Explanation of symbols]

 1: light-emitting element 2: light-receiving element (for monitor) 3: (optical) fiber stub 3a: (bare) optical fiber 3b: ferrule 10: alignment-free mounting substrate 20: chip carrier 30: alignment substrate 31: groove M1, M2: Optical module

Continued on the front page F term (reference) 2H036 LA03 LA04 LA05 NA01 QA22 2H037 AA01 BA02 DA03 DA04 DA06 DA12 DA15 DA16 DA18 5F041 AA41 AA47 DA07 DA16 DC66 EE02 EE05 EE08 EE25 5F073 BA01 EA29 FA05 FA07 FA23 FA27 EA03 JA01

Claims (3)

[Claims] A non-aligned mounting substrate in which a light emitting element and an optical fiber for optically connecting one end to the light emitting element are disposed in a groove formed in the alignment substrate; An optical module comprising: a ferrule to be held; and a chip carrier having a light receiving element for monitoring light emitted from the light emitting element. 2. The alignment substrate and the alignment-free mounting substrate are made of a material that can be anisotropically etched, and the grooves of the alignment substrate and the grooves of the alignment-free mounting substrate are anisotropic. The optical module according to claim 1, wherein the optical module is formed by etching. 3. The optical module according to claim 1, wherein an external electrode electrically connected to the light emitting element and the light receiving element is formed on the alignment substrate.