JP2000187137A - Optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical module having a structure to embody the durability better than heretofore with respect to a change in the use environment. SOLUTION: The optical module is constituted by providing an inside wall surface 40 of a sleeve SL fixed via an adhesive 450 to a head part 24 formed by molding, for example, an optical device of a resin with thread grooves or subjecting this wall surface to embossing 440. As a result, the strength of adhesion of the resin molded part which is the head part 24 and the sleeve SL is improved and the adhesion durability better than heretofore is embodied.

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 in optical communication, and more particularly, to a head unit in which optical devices such as a light receiving element and a light emitting element are molded with resin, and a part of the head unit is housed. The present invention relates to a structure for providing sufficient adhesive strength between the head and a sleeve attached to the head in a state.

[0002]

2. Description of the Related Art A conventional optical module incorporates a light emitting element, a light receiving element, and other optical devices, and has a can-shaped TO (Transistor Outlier) with a condenser lens attached thereto.
ne) type standard package was provided at least, and the TO type standard package had an alignment sleeve for receiving an optical fiber ferrule attached to the tip of an optical fiber as an optical transmission line fixed through an adhesive. (See U.S. Patent No. 5,596,665).

Since the housing of the TO type standard package containing the optical device is made of metal, the cost and size of the optical module are increased, and it is difficult to process the optical module into a desired shape. It was low. Therefore, instead of such a metal package, an optical module having an integrated structure in which optical devices such as a light emitting element and a light receiving element directly mounted on a lead frame are molded with a plastic resin has been proposed (US Pat. No. 4,410,469). U.S. Pat. No. 4,539,476).

[0004]

As a method for molding a resin mold portion or a sleeve in a conventional optical module,
A transfer mold is generally used in which a plastic resin is injected into a mold having a cavity having a predetermined shape and molded. Further, the surface of the obtained resin mold portion and the sleeve was processed as smoothly as possible in consideration of die cutting and the like.

[0005] However, when the sleeve is fixed to such a resin mold portion via an adhesive such as an ultraviolet curable resin, the smooth surfaces inevitably face each other via the adhesive. It has been difficult to improve the durability against the expected change in the use environment (for example, a temperature change or a humidity change in the range of −40 ° C. to + 85 ° C.).

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and by improving the adhesive strength between a resin mold portion covering an optical device such as a light emitting element and a light receiving element and a sleeve, It is an object of the present invention to provide an optical module having a structure that achieves better durability than before.

[0007]

SUMMARY OF THE INVENTION The present invention relates to an optical module applicable to an optical data link connecting an optical fiber transmission line and an electric signal transmission line. And
An optical module according to the present invention has an integrated structure in which an alignment sleeve is attached to a head in which an optical device such as a light-emitting element and a light-receiving element is molded with resin, and the sleeve has at least a first portion of the head. The head portion is fixed to the head portion via an adhesive in a state where the protrusion portion is stored.

In particular, in the optical module according to the present invention, at least one of the sleeve and the head is used to improve the adhesion durability between the first protruding portion (resin molded portion) and the sleeve in the head. A crab is provided with an adhesive strength increasing structure for increasing the adhesive strength between the sleeve and the head portion.

More specifically, the structure for increasing the adhesive strength can be realized by providing a thread groove at least on the inner wall surface of the sleeve, mainly the sleeve fitted with the first projecting portion.
In addition, this screw groove can not only obtain an anchor effect by permeation of an adhesive. By providing a thread groove also on the surface of the first protruding portion of the facing head portion, the position of the ferrule facing the head portion via the sleeve can be adjusted. That is, by engaging the screw groove provided on the sleeve with the screw groove provided on the surface of the first projecting portion of the head portion, the position of the sleeve in the central axis direction can be adjusted, and the sleeve is supported by the ferrule. The distance between the end face of the optical fiber and the optical device in the head can be controlled accurately.

The structure for increasing the adhesive strength may be obtained by subjecting at least one of the inner wall surface of the sleeve and the surface of the first protrusion of the head portion housed in the sleeve to a surface treatment such as etching. This can also be realized by providing a convex pattern having a height.

The surface treatment may be performed after the resin molding of the sleeve or the head portion. However, since extra manufacturing steps are added, it is more preferable to apply a grain on the inner wall surface of the sleeve or the surface of the first protrusion. preferable. The adhesive penetrates the textured surface to increase the adhesive strength between the sleeve and the resin mold portion. However, this grain has a maximum depth of about 10
μm, preferably 10 μm to 20 μm. If the recess is too shallow, sufficient adhesive strength cannot be obtained, while if the recess is too deep, the sleeve or the like will not come off from the mold after resin molding. The adhesive strength between the sleeve and the head portion depends not only on the depth of the concave portion forming the grain as described above, but also on the shape of the grain surface. Therefore, in order to obtain a desired adhesive strength, in the optical module according to the present invention, the formed grain has a maximum diameter of 20 μm or more.
A plurality of recesses each having a thickness of 50 μm, and the recesses forming the grain are about 80%, preferably 60%, of the grain surface.
It accounts for 90%.

Further, in the above-mentioned structure for increasing the adhesive strength, the head portion has a first protrusion and a second protrusion surrounding the first protrusion.
It can also be realized by providing a protruding portion, and bonding and fixing the sleeve to the head portion in a state where the opening portion of the sleeve is sandwiched between the first and second protruding portions. Also according to this configuration, the bonding area in the head portion and the bonding area in the sleeve are almost doubled as compared with the conventional optical module, so that the bonding strength is further improved as compared with the conventional one. In the optical module according to the present invention, the structure in which the first and second protrusions are provided on the head portion and the structure in which the sleeve side or the head portion side is subjected to surface treatment such as embossing are combined. It is also possible to match.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an optical module according to the present invention will be described below with reference to FIGS. In addition,
In the drawings, the same parts and the same members are denoted by the same reference numerals, and redundant description will be omitted.

FIGS. 1A to 1D are views for explaining the structure of the optical module according to the present invention together with the manufacturing process.

First, a metal lead frame 10 for manufacturing the optical module MD is prepared. As shown in FIG. 1A, the lead frame 10 has a first mounting section 12 for mounting an optical device 22 such as a light emitting element and a light receiving element, and a second mounting section 12 for mounting an electronic element. The mounting portion 14 and a plurality of connecting portions (internal lead pins 16) for electrically and mechanically connecting the mounting portions 12 and 14.
In addition, a plurality of external lead pins 18 located behind the mounting portion 14 are die-cut.

A submount member 20 is fixed on the first mounting portion 12 of the lead frame 10, and an optical device 22 of a semiconductor chip (bare chip) is fixed on the submount member 20. When the optical module MD for reception is manufactured, a light receiving element such as an InGaAs-based PIN photodiode having sensitivity to an optical signal in a 1.3 μm wavelength band is used as the optical device 22, and a submount member is used. As 20, a plate-type capacitor (die cap) or the like is used. on the other hand,
An electronic element for transmitting and receiving an electric signal between the optical devices 22 is mounted on the second mounting portion 14. Next, when manufacturing the optical module MD for transmission, the optical device 22
For example, a light-emitting element such as a surface-emitting type InGaAsP light-emitting diode that emits signal light in a 1.3 μm wavelength band is used, and a diamond or aluminum nitride (AlN) material is used for the submount member 20. By using the submount member 20 of diamond or aluminum nitride, a heat sink effect can be obtained. Further, an electronic element for transmitting and receiving an electric signal to and from the optical device 22 is mounted on the second mounting portion 14.

After the necessary portions are wired with bonding wires, the lead frame 10 is housed in a resin molding die 240 having a cavity of a predetermined shape (see FIG. 1B). Then, the first mounting portion 12 and the second mounting portion 14 are respectively transfer-molded with a resin transparent to the signal light. As a result, as shown in FIG. 1C, the head portion 24 in which the first mounting portion 12, the submount member 20, and the optical device 22 are integrally molded with resin, the second mounting portion 14, and the electronic element Are integrally molded with resin to obtain a body portion 26. Note that the first and second
The connecting portions (including the internal lead pins 16) that electrically and mechanically connect the mounting portions 12 and 14 are exposed without being resin-molded.

Next, unnecessary portions of the lead frame 10 are cut to obtain an intermediate part as shown in FIG.

As described above, the transfer-molded head portion 24 has a truncated cone-shaped base portion 24a (sleeve SL) for sealing the submount member 20 and the optical device 22.
, A non-spherical lens 24b molded on the top of the base 24a, and a base 24c protruding on the back side of the first mounting portion 12 are integrally formed. It has a unique structure.

Further, the optical axes of the aspherical lens 24b and the light receiving surface of the optical device 22 coincide with each other, and
Has a side wall having a predetermined inclination angle and a truncated cone having a predetermined height so as to be concentric with the aspheric lens 24b and the light receiving surface of the optical device 22 so as to gradually become thinner toward the top. Has become. The base 24c is mounted on the base 2
It has a truncated conical shape in which the part connected to 4a is gradually reduced to the maximum diameter, and a columnar shape having the same diameter as the part connected to the base 24a.

Next, the internal lead pin 1 of the above-mentioned intermediate part
6 is bent into a hook shape, so that the converging aspheric lens 24b formed on the base 24a is
By turning the external lead pin 18 toward the opposite side of the body 26 with respect to 6, the module of the SIP (single in-line package) type as shown in FIG.

A cylindrical alignment sleeve SL for receiving an optical fiber ferrule is adhered and fixed to the base 24a of the head 24, so that the sleeve S
The optical module MD integrated with L is completed.

(First Embodiment) The optical module according to the present invention has a structure for increasing the bonding strength between these members at least on the side of the head 24 or on the side of the sleeve SL which is fixed to each other via an adhesive. It is characterized by having.

FIGS. 2A to 2C show the configuration of the optical module according to the first embodiment of the present invention and the head unit 2.
FIG. 4 is a view showing a bonding step between the sleeve 4 and the sleeve SL.
In the embodiment, a predetermined surface treatment is performed on the inner wall surface of the sleeve SL or the surface of the insertion portion of the head portion 24 to increase the adhesive strength between the sleeve and the head portion.

As shown in FIGS. 2A and 2B,
The sleeve SL is a hollow cylindrical member, and has a space 38 (insertion hole) for accommodating the optical fiber ferrule and a space 40 (insertion hole) for accommodating the base 24a of the head 24.
It has. In particular, in the first embodiment, the insertion hole 4
For example, a grain 440 is hit as a surface treatment on the inner wall surface 400 of the sleeve. This textured surface 400 is the base 2
4a so as to face the surface of 4a via an adhesive.
L is fixed to the head section 24. That is, the cylindrical sleeve SL is formed of an opaque resin,
As shown in the cross-sectional view of (b), an insertion hole 38 for inserting the ferrule from the front end side, and an insertion hole 40 for inserting the base 24a of the optical module MD from the rear end.
And a communication hole 42 communicating between the insertion holes 38 and 40.
have. The insertion hole 40 has a frusto-conical inner wall surface 440 so as to substantially match the side wall shape of the base 24a.

The bonding process between the sleeve SL and the head portion 24 of the optical module is performed by using an adjusting jig (not shown) as shown in FIG.
This is performed in a state where the head L and the head 24 are supported. That is, the base portion 24 is bonded via the adhesive 450 of the ultraviolet curing resin.
a is inserted into the insertion hole 40 of the sleeve SL,
The optical module is actually operated with the adjusting ferrule 50 receiving the multi-mode optical fiber FL inserted into the insertion hole 38 of the sleeve SL.

At this time, if the optical module is a receiving optical module, the positional relationship between the head section 24 and the sleeve SL is determined by the fact that the electric signal output from the optical module that receives the signal light emitted from the optical fiber FL is It is adjusted so as to be equal to or more than the specified value (optical axis alignment). On the other hand, in the case of an optical module for transmission, the signal light emitted from the optical module is introduced into the optical fiber FL, and the sleeve SL is connected to the optical fiber FL so that the intensity of the signal light extracted from the optical fiber FL becomes a specified value or more. The position of the head 24 is adjusted (optical axis alignment).

After the alignment of the optical axis, the ultraviolet curable resin 450 is solidified by irradiating the ultraviolet UV between the inner wall surface 400 of the sleeve SL and the surface of the pedestal 24a from diagonally behind the head 24. Thereby, the sleeve SL and the head portion 24 are fixed.

In the first embodiment, as described above, the inner wall surface 400 of the sleeve SL or the
The surface treatment is performed to form a desired concavo-convex pattern on the surface 4a. A method of manufacturing the sleeve SL (transfer molding) in which a grain 440 is formed on the inner wall surface 400 of the sleeve SL will be described below with reference to FIG. .

First, molds 501 and 502 for manufacturing an opaque resin sleeve are prepared. These molds 50
As shown in FIG. 3A, cavities 510 and 5 respectively determine the shape of the sleeve SL.
A rod member 51 for forming the insertion holes 38, 40 is provided in the cavities 510, 520.
1, 521 are installed. In addition, each mold 501, 5
02, these surfaces 541, 542
When the molds 501 and 502 are combined so that the two coincide with each other, an injection port of the plastic resin is formed.
Grooves 530a to 530d are formed respectively.

In addition, as shown in FIG. 3 (b), a mold 502 for molding the head portion 24 side of the sleeve SL has a surface (a space 40 for accommodating the base portion 24a of the head portion 24). (Corresponds to the inner wall surface to be defined)
A rod member 521 with a mark is provided in the cavity 520. Thereby, the inner wall surface 40 of the sleeve SL
The grain pattern 525 of the rod member 521 is transferred onto the zero.

FIG. 4 shows the molds 501 and 502 as described above.
5 is a photomicrograph showing an inner wall surface 400 (textured surface) of a sleeve SL molded by using FIG. In addition, FIG.
FIG. 4B is a micrograph of the grain surface provided on the sleeve SL observed at a magnification of 100 times, and FIG. 4B is a micrograph of the grain surface observed at a magnification of 200 times.

The grain 440 formed as described above is formed on the sleeve SL by the adhesive permeating the grain surface 400.
The adhesive strength between the resin and the resin mold portion (base portion 24a). However, the grain 440 is constituted by a plurality of concave portions having a maximum depth of about 10 μm, preferably 10 μm to 20 μm. If the recess is too shallow, sufficient adhesive strength cannot be obtained, while if the recess is too deep, the sleeve S
This is because L cannot be removed. The adhesive strength between the sleeve SL and the head portion 24 depends not only on the depth of the concave portion forming the grain 440 as described above, but also on the shape of the grain surface 400. Therefore, in order to obtain a desired adhesive strength, in the optical module MD according to the present invention, the formed grain 440 is constituted by a plurality of recesses having a maximum diameter of 20 μm to 50 μm, and the recess forming the grain is a grain surface. 40
It accounts for about 80%, preferably 60% to 90% of 0.

In the above description of the first embodiment, the sleeve S for forming a grain 440 on the inner wall surface 400 of the sleeve SL facing the base 24a of the head 24 is described.
L has been described, but the grain 440 is not
May be provided on the surface. Also, the grain 440 is attached to the inner wall surface 40.
Instead of providing on the surface of the base portion 24a and / or the base portion 24a, a convex pattern having a predetermined height is formed on the sleeve SL or the base portion 24a after transfer molding by etching or the like (the surface shape of the convex pattern is preferably not uniform). May be.

(Second Embodiment) Next, a second embodiment of the optical module according to the present invention will be described with reference to FIG. FIG. 5A is a perspective view showing a structure of a sleeve SL for realizing the second embodiment, and FIG.
FIG. 7 is a cross-sectional view for explaining an adhesive structure between a sleeve SL and a head portion 24 in the second embodiment.

In the optical module according to the second embodiment, as shown in FIG. 5 (a), when the adhesive is fixed to the head 24, the sleeve faces the surface of the base 24a of the head 24. Thread groove 460a on inner wall 400 of SL
Is provided. When the adhesive 450 such as an ultraviolet curable resin penetrates into the thread groove 460a, the sleeve SL is formed.
The adhesive strength between the resin and the head portion 24 as the resin mold portion increases.

The bonding process between the sleeve SL and the head portion 24 is performed as described with reference to FIG. 2C. At this time, the thread groove 460b is also provided on the surface of the base portion 24a of the head portion 24. Is provided, and by engaging with the thread groove 460a provided in the sleeve SL, the positional relationship between the sleeve SL and the head portion 24 can be accurately defined. That is, this optical axis adjustment is performed by inserting the multi-mode optical fiber FL into the adjustment ferrule 50 received in the insertion hole 38 of the sleeve SL, and at the same time, screwing the pedestal portion 24a of the head portion 24 into the thread groove 460b of the sleeve SL. 4
It is performed in a state where it is inserted so as to engage with 60a. Therefore, in the case of a receiving optical module, its signal strength,
Alternatively, in the case of an optical module for transmission, an optical fiber FL
This is performed while monitoring the output light intensity from the. With this configuration, the distance between the optical fiber FL and the light receiving surface or the light receiving surface of the optical device in the head unit 24 can be easily adjusted and maintained.

(Third Embodiment) Next, a third embodiment of the optical module according to the present invention will be described with reference to FIG. FIG. 6A is a perspective view showing a structure of a head unit 24 for realizing the third embodiment, and FIG.
FIG. 9 is a cross-sectional view for explaining a bonding structure between a sleeve SL and a head portion 24 in the third embodiment.

In the optical module according to the third embodiment, as shown in FIG. 6A, the head portion 24 is attached to the sleeve SL via the adhesive 450 while being housed in the sleeve SL. It has a base 24a (first protruding part) to be adhered and fixed, and a reinforcing part 24d (second protruding part) provided so as to surround the base 24a.
Therefore, the head part 24 and the sleeve SL of the third embodiment having the structure as shown in FIG.
As shown in (b), when the sleeve SL is fixed via the adhesive 450, the opening of the sleeve SL is sandwiched between the base 24a and the reinforcing portion 24d. At this time, the sleeve S
Since the adhesive 450 is filled between the outer peripheral surface of L and the reinforcing portion 24d and between the base portion 24a and the inner wall surface 400 of the sleeve SL, the adhesive area in the sleeve SL and the adhesive area in the head portion 24 are filled. Is about twice as large as that of the related art. According to the third embodiment, the adhesive strength between the sleeve SL and the head 24 can be increased.

The above first to third embodiments can all increase the bonding strength. However, by combining these first to third embodiments arbitrarily, the bonding durability can be further improved. Can be.

In each of the embodiments described above, the SIP (single in-line package) type optical module in which the external lead pins 18 are arranged in a line has been described. However, the present invention is not limited to this. It can also be applied to an (in-line package) type optical module. That is, instead of the external lead pins 18, the lead frame 10 shown in FIG.
By providing a plurality of external lead pins on both sides of the device, a DIP type optical module can be manufactured.

[0042]

As described above, according to the present invention, a structure for improving the adhesive strength of the sleeve and the head portion is provided on the side of the sleeve or on the side of the head portion which is fixed to each other with an adhesive, thereby improving the conventional structure. This also has the effect of improving the bonding strength and exhibiting excellent bonding durability.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a structure of an optical module according to the present invention together with a manufacturing process.

FIG. 2 is a diagram illustrating a configuration of a first embodiment of the optical module according to the present invention.

FIG. 3 is a drawing for explaining the manufacturing method of the first embodiment in the optical module according to the present invention.

FIG. 4 is a micrograph showing a grain formed on an inner wall surface of the sleeve by the manufacturing method shown in FIG. 3;

FIG. 5 is a diagram illustrating a configuration of a second embodiment of the optical module according to the present invention.

FIG. 6 is a diagram illustrating a configuration of an optical module according to a second embodiment of the present invention.

[Explanation of symbols]

MD: optical module, SL: sleeve, 24: head, 24a: base (first protrusion), 24d: reinforcement (second protrusion), 400: sleeve inner wall surface (textured surface) 450: adhesive, 460a, 460b ... thread groove.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ichiro Karauchi 1 Tayacho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Sumitomo Electric Industries, Ltd. Yokohama Works (72) Inventor Toshio Mizue 1 Tayacho, Sakae-ku, Yokohama-shi, Kanagawa Sumitomo Electric Industries, Ltd. Yokohama Works F-term (reference) 2H037 AA01 BA03 BA12 DA03 DA04 DA05 DA06 DA15 DA17 DA33 5F041 AA38 EE04 EE05 EE11 EE15 FF14 5F073 BA02 FA23 FA29 5F088 AA01 BB01 EA11 JA12 JA14 LA01

Claims (5)

[Claims] 1. An optical module comprising: a head portion formed by molding an optical device with a resin; and a sleeve fitted to a first projecting portion of the head portion and fixed to the head portion by an adhesive. An optical module, characterized in that at least one of the first protrusion and the sleeve is provided with an adhesive strength increasing structure for increasing the adhesive strength between the sleeve and the head. 2. The optical module according to claim 1, wherein the bonding strength increasing structure is a screw groove structure provided on an inner wall surface of the sleeve at a portion fitted with the first protrusion. 3. The protrusion having a predetermined height provided on at least one of an inner wall surface of a sleeve at a portion fitted with the first protrusion and a surface of the first protrusion. 2. The optical module according to claim 1, wherein the pattern is a pattern, and the surface shape of the convex pattern is not uniform. 4. The optical module according to claim 3, wherein the surface provided with the convex pattern is a textured surface. 5. The head unit further includes a second protrusion provided around the first protrusion, wherein the first protrusion and the second protrusion sandwich a wall of the sleeve and The optical module according to any one of claims 1 to 4, wherein the optical module is fixed to the sleeve via the adhesive.