JP2002014260A - Planar mounting optical module and transmission substrate using such module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planar mounting optical module that can prevent an optical fiber or ferrule from deviating from a designed position and that can withstand solder reflow. SOLUTION: The module is equipped with a cap-attached housing 10 formed of epoxy resin or the like, a Si substrate 12 provided inside the housing 10, a semiconductor laser element 14 installed on the Si substrate 12, a ferrule 16 stuck to a notched part of the housing 10 and designed to hold an optical fiber 18 inside, and the optical fiber 18 stuck to the Si substrate 12 in a state that the fiber is inserted from the outside of the housing to the inside through the ferrule 16 and arranged with one end face oppositely facing the active layer of an LD 14. The ferrule 16 and the optical fiber 18 are stuck to each other with an adhesive having a glass transition temperature Tg higher than that of the adhesive joining the housing 10 with the ferrule 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat-mount optical module and a transmission board using the same, and more particularly, to a flat-mount optical module for converting an electric signal and an optical signal to each other or unilaterally, and a light-emitting module. It relates to the transmission board used.

[0002]

2. Description of the Related Art A planar mounting type optical module is an electronic component for converting an electric signal and an optical signal to each other or one of them, and is mainly used for a core device for optical communication. Such a planar mounting type optical module is generally shown in FIGS.
The configuration is as shown in FIG.

That is, a housing 50 with a lid made of epoxy resin or the like (the lid is shown by a broken line in FIG.
0, a semiconductor laser device 54 (hereinafter, referred to as an LD) provided on the Si substrate 52, a ferrule 56 bonded by an adhesive while being inserted into the housing 50, Adhesively held in the ferrule 56,
Further, an optical fiber 58 bonded to the Si substrate 52 is provided in a state where one end face is opposed to the active layer of the LD 54.

The Si substrate 52 has an optical fiber mounting portion 52a and an LD mounting portion 52b separated by a separating groove 52c, and the optical fiber mounting portion 52a is provided along a direction perpendicular to the separating groove 52c. A V-groove for mounting an optical fiber is formed. An LD 54 for converting an external electric signal into an optical signal is fixedly provided on the LD mounting portion 52b.

[0005] The optical fiber 58 is positioned so that one end face thereof accurately faces the LD active layer. The optical fiber 58 is held in the ferrule 56 in the cutout portion of the housing 50, and the V-groove is formed in the housing 50 from the V groove. A V-groove (not shown) whose peripheral surface is provided in the optical fiber mounting portion 52a in a state where a glass plate 60 for preventing floating of the optical fiber is provided above the optical fiber 58 is provided.
Inside, it is bonded and fixed with a UV-curable adhesive 67 or the like. One end face of this optical fiber 58 facing the LD active layer is stress-ruptured to a mirror surface, and the other end face is polished to a convex spherical surface.

The ferrule 56 for holding the optical fiber 58 in the cutout portion of the housing 50 is formed in a substantially cylindrical shape. The optical fiber 58 is adhered and held on the inner peripheral surface with an adhesive, and the outer peripheral surface is adhered on the outer peripheral surface. Is fixed to the housing 50 with an adhesive. An adhesive for fixing the ferrule 56 to the housing 50,
The adhesives for fixing the optical fiber 58 in the ferrule 56 have a glass transition temperature Tg of 125, respectively.
It is an epoxy resin adhesive at about ° C.

[0007] The planar mounting type optical module 7 having the above configuration.
0 is, for example, as shown in FIG.
After the electrodes 82 and the lead portions 72 are overlapped via the solder balls 84, solder reflow is performed. That is, 240
When left in a high temperature environment of about 30 ° C. for about 30 seconds, as shown in FIG.
2 and the lead 72 are electrically joined.

[0008]

In the planar mounting type optical module having the above-described structure, the housing and the ferrule, and the ferrule and the optical fiber are bonded by resin adhesives, respectively. Temperature Tg is 100
C. to about 125.degree.

That is, when bonding with solder balls or the like,
When placed in a high-temperature environment of 40 ° C. for 30 seconds, the adhesive for bonding the housing and the ferrule and the adhesive for bonding the ferrule and the optical fiber loosen almost simultaneously, and then undergo glass transition. To cure.

At this time, if the adhesive for adhering the housing and the ferrule and the adhesive for adhering the ferrule and the optical fiber are loosened almost at the same time and fixed, when the adhesive is once loosened, FIG. As shown in (B), there is a case where the optical fiber is shifted in a direction of being drawn into the housing.

[0011] Further, when the planar mounting type optical module having the above-described configuration is joined to the wiring board by performing solder reflow, the adhesive for bonding the optical fiber and the Si substrate is once loosened, so that the optical fiber and the LD can be separated. Distance may shift.

When such an optical fiber misalignment occurs, the output fluctuation from the optical fiber exceeds 1 dB, and the noise increases. Since such a problem may occur, it is difficult to join a conventional planar mounting type optical module to a wiring board by solder reflow.

In view of the above, the present invention provides a planar mounting type optical module which can prevent an optical fiber or a ferrule from being shifted from a design position at the time of solder reflow or an optical fiber being moved and shifted within a ferrule. With the goal. Another object of the present invention is to provide a transmission board in which a planar mounting type optical module is mounted on a wiring board, which can prevent the distance between the optical fiber and the LD from changing at the time of solder reflow.

[0014]

According to a first aspect of the present invention, there is provided a planar mounting type optical module comprising: a housing; a pedestal provided in the housing; and a pedestal provided in the housing. In addition, a conversion element for mutually or unidirectionally converting an electric signal and an optical signal, a holding member provided on a housing, and a conversion element are placed on a pedestal such that one end face faces the conversion element, and An optical fiber fixed to the housing and extending from the inside of the housing to the outside, wherein the housing and the holding member are adhered to each other by a first adhesive having a predetermined glass transition temperature;
The holding member and the optical fiber are bonded by a second adhesive having a higher glass transition temperature than that of the adhesive.

According to the first aspect of the present invention, the glass transition temperature of the first adhesive for bonding the housing and the holding member is higher than the glass transition temperature of the first adhesive.
The glass transition temperature of the second holding member that bonds the holding member and the optical fiber is increased. Therefore, when the solder reflow is performed, the first adhesive for bonding the housing and the holding member is first hardened, and then the second adhesive for bonding the holding member and the optical fiber is hardened. As described above, the timing at which the adhesive cures between the housing and the holding member and between the holding member and the optical fiber is shifted.

Therefore, in an environment higher than the glass transition temperature of the adhesive, such as at the time of solder reflow, it is possible to prevent the optical fiber from moving and shifting within the holding member, thereby suppressing output fluctuation from the optical fiber. it can.

The adhesive is preferably a thermoplastic resin-based adhesive. As the thermoplastic resin, for example, an epoxy resin adhesive is preferable.

According to a fourth aspect of the present invention, there is provided a transmission board, wherein a housing, a pedestal provided in the housing, and an electric signal and an optical signal provided in the housing are mutually or unidirectionally converted. A conversion element, a holding member provided in the housing, and a light that is placed on the pedestal such that one end face faces the conversion element, is fixed to the holding member, and further extends from the inside of the housing to the outside. A transmitter version in which a planar mounting type optical module including a fiber is mounted on a wiring board using solder, wherein the optical fiber and the pedestal are made of an adhesive having a glass transition temperature higher than the melting point of the solder. Glued.

In the fourth aspect of the present invention, the Si substrate and the optical fiber are bonded with an adhesive having a glass transition temperature higher than the melting point of the solder. Therefore, at the time of solder reflow, the adhesive for bonding the optical fiber and the Si substrate does not loosen. Therefore, it is possible to prevent a change in the distance between the optical fiber and the LD, and it is possible to suppress output fluctuation from the optical fiber.

The adhesive is preferably a polyimide resin or a glass having a low melting point.

It is preferable that the holding member extends from the inside of the housing to the outside, as described in the third and sixth aspects.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the planar mounting type optical module according to the present embodiment is provided in a housing 10 with a lid made of epoxy resin or the like (the lid is not shown in FIG. 1) and inside the housing 10. Si substrate 1
2. Semiconductor laser element 14 provided on Si substrate 12
(Hereinafter referred to as an LD), a ferrule 16 adhered to a cutout provided in the housing 10 and holding an optical fiber 18 therein, and inserted through the ferrule 16 from outside the housing to the inside of the housing. An optical fiber 18 bonded to the Si substrate 12 is provided in a state where one end face is opposed to the active layer of the LD 14. Furthermore, case 1
0 to the LD 14 from the outside, or vice versa.
The lead 3 electrically connected to the LD 14 to transmit an electric signal generated from the outside 14 to the outside of the housing 10.
2 are arranged through the housing 10. Ferrule 1
6 is, for example, a holding member in the present invention,
Respectively correspond to pedestals.

As shown in FIG. 2, the upper surface of the Si substrate 12 is separated into an optical fiber mounting portion 12a and an LD mounting portion 12b by a separation groove 12c. Optical fiber receiver 12
A is formed with a V-groove 28 extending in a direction perpendicular to the separation groove 12c at the center, and an optical fiber is placed in the V-groove 28. In addition, in the LD mounting portion 12b,
The LD 14 for converting an external electric signal into an optical signal is
The LD active layer is fixed to the groove 28 with high precision alignment so as to have a predetermined arrangement. This alignment is performed in sub-micron units using an infrared transmitting die bonder or the like.

As shown in FIG. 3, the optical fiber 18 is positioned so that one end face thereof accurately faces the LD active layer of the LD 14, and is held in the ferrule 16 at the cutout portion of the housing 10. In the case 10, the glass plate 20 for preventing lifting is adhered to the inside of the V groove 28 by a UV-curable adhesive 27 in a state of being adhered upward. One end face of the optical fiber 18 facing the LD active layer is mirror-stress-ruptured and the other end face is polished to a convex spherical surface.

The ferrule 16 for holding the optical fiber 18 in the cutout portion of the housing 10 is formed in a substantially cylindrical shape, for example, a glass transition temperature such as # 9390 (trade name; manufactured by NTT Advanced Technology Co., Ltd.). Tg is 90 degrees or more and 1
The optical fiber 18 is adhered and held on the inner peripheral surface side by an epoxy resin adhesive 26 of about 30 degrees or less. The epoxy resin adhesive 26 having a glass transition temperature Tg of about 90 degrees or more and about 130 degrees or less corresponds to, for example, the second adhesive in claim 1 of the present invention.

Here, # 93 is used as the adhesive 26.
90 is used, but the glass transition temperature T of the adhesive 26 is
g may be higher than an adhesive 24 for bonding between the casing 10 and the ferrule 16 described below. However, the glass transition temperature Tg is preferably about 90 degrees or more and 130 degrees or less. For example, other types of adhesives such as # UV1100 (trade name; manufactured by Optodyne Co., Ltd.) can be used.

The ferrule 16 is, for example, # 58
13 (trade name; manufactured by NTT Advanced Technology Co., Ltd.) such as epoxy resin adhesive 24 having a glass transition temperature Tg of about 65 to 90 degrees.
0. The glass transition temperature Tg is 65
Epoxy resin adhesive 24 of about 90 degrees or less,
For example, it corresponds to the first adhesive in claim 1 of the present invention.

Here, # 58 is used as the adhesive 24.
13 is used, but the glass transition temperature T of the adhesive 24 is used.
g may be lower than the adhesive 26 for bonding between the ferrule 16 and the optical fiber 18. However, it is preferable that the glass transition temperature Tg is about 65 degrees or more and about 90 degrees or less. For example, other types of adhesives such as # 5814 (trade name; manufactured by NTT Advanced Technology Co., Ltd.) and # 5815 (trade name; manufactured by NTT Advanced Technology Co., Ltd.) can be used.

After the electrodes 82 of the wiring board 80 and the lead portions 72 of the planar mounting type optical module 30 having such a configuration are overlapped via the solder balls 84, solder reflow is performed. That is, it was left in a high temperature environment of 240 ° C. for about 30 seconds. As a result, as shown in FIGS. 3A and 3B, the optical fiber was able to sufficiently withstand the solder reflow without moving and shifting within the ferrule.

As described above, the planar mounting type optical module according to the first embodiment of the present invention can prevent the optical fiber from moving within the ferrule during the solder reflow, and thus can reduce the output fluctuation from the optical fiber. Can be suppressed.

The planar mounting type optical module according to the first embodiment is a transmitting module using the LD 14 for converting an external electric signal into an optical signal, but the present invention is limited to the transmitting module. Not to do, LD14
Instead, the present invention can be applied to a light receiving module using a photodiode as a light receiving element.

Hereinafter, a second embodiment of the present invention will be described with reference to FIG. A second embodiment of the present invention
Since the same planar mounting type optical module as that of the first embodiment of the present invention is used, description of the planar mounting type optical module is omitted. As shown in FIG. 6, the second embodiment of the present invention is a transmission board in which the planar mounting type optical module 30 of the first embodiment is mounted on a wiring board 80 using solder balls 84.

However, as the UV-curable adhesive 27, an adhesive whose glass transition temperature Tg exceeds the melting point of the solder ball is used. As the UV-curable adhesive 27, it is desirable to use a polyimide resin or a glass having a low melting point. When a polyimide resin is used, a glass transition temperature Tg of about 270 ° C. can be used, and when a glass having a low melting point is used, a glass transition temperature of about 300 ° C. can be used. Note that the glass transition temperature Tg of the adhesive 26 that bonds the ferrule 16 to the optical fiber 18 may not be higher than the glass transition temperature Tg of the adhesive 24 that bonds the housing 10 to the ferrule 16. UV curable adhesive 27
Corresponds to the adhesive in claim 4 of the present invention, for example.

After the planar mounting type optical joule 30 having such a configuration is overlaid on the electrode 82 of the wiring board 80 and the lead portion 72 via the solder ball 84, solder reflow is performed, that is, 240 ° C. Leave for about 30 seconds in a high temperature environment. Thus, the transmission board according to the second embodiment of the present invention is completed.

As described above, in the transmission board according to the second embodiment of the present invention, since the optical fiber and the Si board are bonded by the adhesive having a glass transition temperature higher than the melting point of the solder, the solder reflow At times, the adhesive bonding the optical fiber and the Si substrate does not loosen. Therefore, at the time of solder reflow, it is possible to prevent the distance between the optical fiber and the LD from being deviated, so that output fluctuation from the optical fiber can be suppressed.

[0036]

As described above, according to the first aspect of the present invention, the timing at which the adhesive is cured is shifted between the housing and the holding member and between the holding member and the optical fiber. In a high temperature environment such as this, it is possible to prevent the optical fiber from moving within the holding member and shifting.

As a result, the optical fiber does not retract into the ferrule due to the solder reflow, so that the effect of suppressing output fluctuation from the optical fiber can be obtained.

According to the fourth aspect of the present invention, the adhesive for bonding the optical fiber and the Si substrate does not loosen once in a high temperature environment such as at the time of solder reflow.
It is possible to prevent the distance between the optical fiber and the LD from shifting.

As a result, it is possible to prevent the distance between the optical fiber and the LD from changing, and it is possible to obtain an effect of suppressing output fluctuation from the optical fiber.

[Brief description of the drawings]

FIG. 1 is a partial perspective view illustrating the structure of a planar optical module according to a first embodiment of the present invention.

FIG. 2 is a perspective view illustrating the structure of the Si substrate shown in FIG.

3 (A) is a partial cross-sectional view taken along line AA of FIG. 1, and FIG. 3 (B) is an enlarged view taken along line BB of FIG. 3 (A).

FIG. 4 is a partial perspective view illustrating the structure of a conventional planar mount optical module.

5 (A) is a partial cross-sectional view taken along the line CC of FIG. 4, and FIG. 5 (B) is an enlarged view of the line DD of FIG. 5 (A).

FIG. 6 is an explanatory diagram for explaining a conventional method for mounting a planar mounting type optical module and a method for manufacturing a transmission board according to a second embodiment of the present invention. FIG. 6A is an explanatory diagram showing a state before mounting the planar mounted optical module, and FIG. 6B is an explanatory diagram showing a state after mounting the planar mounted optical module.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Case 12 Si substrate 12a Optical fiber mounting part 12b LD mounting part 12c Separation groove 14 Semiconductor laser element (LD) 16 Ferrule 18 Optical fiber 20 Glass plate 24, 26 Epoxy resin adhesive 27 UV curable adhesive 28 V-groove 30 Flat mounting optical module

Claims (6)

[Claims] A housing, a pedestal provided in the housing, a conversion element provided in the housing for converting an electrical signal and an optical signal to each other or unidirectionally, and provided in the housing. A holding member, and an optical fiber mounted on the pedestal such that one end face faces the conversion element, fixed to the holding member, and further extending from the inside of the housing to the outside, The housing and the holding member are bonded by a first adhesive having a predetermined glass transition temperature, and the holding member and the holding member are bonded by a second adhesive having a glass transition temperature higher than the first adhesive. A planar mounting type optical module characterized by being bonded to an optical fiber. 2. The optical module according to claim 1, wherein the first or second adhesive is a thermoplastic resin-based adhesive. 3. The optical module according to claim 1, wherein the holding member extends from the inside of the housing to the outside. 4. A housing, a pedestal provided in the housing, a conversion element provided in the housing for mutually or unidirectionally converting an electric signal and an optical signal, and provided in the housing. A holding member, and an optical fiber mounted on the pedestal such that one end face faces the conversion element, fixed to the holding member, and further extending from the inside of the housing to the outside. A transmission board in which a planar mounting type optical module is mounted on a wiring board using solder, wherein the optical fiber and the pedestal are bonded with an adhesive having a glass transition temperature higher than the melting point of the solder. A transmission board, characterized in that: 5. The transmission board according to claim 4, wherein the adhesive is a polyimide resin or glass. 6. The transmission board according to claim 4, wherein the holding member extends from the inside of the housing to the outside.