JP6488539B2 - Optical element module - Google Patents

Description

  The present invention relates to an optical element module. In particular, the optical element is accommodated in a casing, and the optical fiber introduced into the casing is optically coupled to the optical element. The present invention relates to an optical element module in which a portion to be introduced into a housing is hermetically sealed with a solder material.

Optical elements such as optical modulators are frequently used in the optical communication field and the optical measurement field. Many of these optical elements are used as an optical element module in which an optical element is accommodated in a metal casing. In the optical element module, an optical fiber is introduced through a through hole provided in the side wall of the housing, and the optical element in the housing is optically coupled to the optical fiber, and the through hole is sealed with a solder material. It is configured to

  In Patent Document 1, an optical fiber is introduced into a case from an introduction hole provided in a wall surface of the case constituting the casing, and the optical fiber is attached to an optical device (functional member) disposed inside the case by an optical adhesive. An optical element module that is bonded and fixed (optical connection) is disclosed.

  In such an optical element module, an electrode or an electronic component for controlling a high-frequency signal is disposed inside the case, and high reliability is required. Therefore, a package to be used requires high airtightness. For this reason, in Patent Document 1, an introduction hole on the wall surface of the case and an introduction pipe material communicating with the introduction hole are arranged as an optical fiber introduction portion, and hermetically sealed with a solder material having extremely low moisture permeability.

  1A and 1B are diagrams showing an outline of a conventional optical element module, in which FIG. 1A is a top view and FIG. 1B is a side view, each showing a cross-sectional view at a position where an optical fiber is disposed. Yes. In conventional optical element modules, the positional relationship of optical devices (such as LN elements) and other optical components arranged inside the package changes due to the influence of deformation of the package (case) due to mechanical external force or heat, and the optical characteristics and The structure is designed to be as rigid as possible so as not to affect the fluctuation. Specifically, only the part mounting part and the space necessary for mounting the part are cut with a machining center, and the remaining part (the side and bottom of the package) is left as thick as possible (thickness D). A highly rigid package is used.

  Further, an optical fiber introducing portion for guiding and holding the optical fiber and preventing damage is joined to the casing. The tip of the optical fiber is directly bonded or optically connected to an optical device disposed inside the housing by a spatial optical system. Although omitted in FIG. 1, electrical wiring or terminals for driving the optical device (LN element) are separately provided.

  The opening of the housing is covered with a cover as shown in FIG. 1B, and the through-hole into which the optical fiber is introduced is hermetically sealed with a solder material. Note that the thickness D of the side wall (the side wall of the optical fiber introduction surface or the side wall perpendicular to it) or the bottom wall of the housing varies depending on the shape of the optical device or the relay substrate accommodated in the housing, and is not necessarily the same. It is not thickness.

  By the way, in the conventional case shape, since the vicinity of the optical fiber introduction part (introduction hole) hermetically sealed with the solder material is thick, the heat given by the soldering iron is transferred to the optical fiber introduction part (introduction hole). ), And the heat hardly concentrates on the optical fiber introduction part (introduction hole). As a result, there has been a problem that the solder material disposed in the optical fiber introduction portion (introduction hole) is sufficiently melted and a long time is required for hermetic sealing (for example, 20 to 30 seconds are required).

  In order to melt the solder material and hermetically seal it, it is necessary to apply a soldering iron of 200 to 300 ° C. to the optical fiber introduction portion and sufficiently heat and melt the solder material arranged in the optical fiber introduction portion (introduction hole). is there. However, for bonding optical devices (such as LN elements) placed inside the package to optical fibers and fixing many other optical components, the melting point of the solder material (low melting point is 120 to 150 ° C) is equal to or lower than that. An optical adhesive or a resin adhesive having a glass transition temperature (Tg = 100 to 150 ° C.) is used. Therefore, if the package is continuously heated with a high-temperature (200 to 300 ° C.) soldering iron for a long time, the cured optical adhesive or resin-based adhesive deteriorates (softens) due to heat, and the optical device (LN element, etc.) Causes displacement and peeling of optical components. Moreover, deterioration of an optical fiber strand or its coating | cover etc. generate | occur | produces by heating for a long time. As a result, the optical element module has failed during manufacture and the characteristics of the optical element module have deteriorated.

  As means for solving such a problem, Patent Document 2 proposes hermetic sealing with a resin adhesive having a low melting point instead of a solder material, but the resin adhesive is made of metal. Since the moisture permeability is very high compared to the solder material, the reliability of the optical element module is deteriorated. For example, if the amount of moisture in the package increases, it may cause a failure such as an electrode short circuit.

JP 2004-317840 A Japanese Patent No. 5086755

  The problem to be solved by the present invention is to solve the above-mentioned problems, efficiently concentrate the heat of the soldering iron on the solder material, and optically bond the optical fiber strand or coating, or the inside of the package (housing). It is to provide a highly reliable optical element module by reducing the amount of heat transfer to the adhesive and resin adhesive so as not to deteriorate, reducing the failure of the optical element module during manufacturing, and high reliability.

In order to solve the above problems, the optical element module of the present invention has the following technical features.
(1) A housing for storing an optical element, and the optical element is optically coupled to an optical fiber introduced into the housing through a through-hole provided in a side wall of the housing. The optical element is held from the side wall portion where the through hole is formed in the optical element module in which the optical fiber led out from the through hole is held by the optical fiber introducing portion joined to the housing. In order to reduce the amount of heat transfer to the casing portion, there is a portion between the side wall portion and the casing portion where the thickness of the wall surface of the casing is thinner than the thickness of the casing portion. In addition , the thickness of the side wall portion in which the through hole is formed is set to be thicker than the side wall in the vicinity of the side wall portion .

(2) In the optical element module according to the above (1), with the inner diameter of the cylinder constituting the front Symbol optical fiber introducing section is set to gradually narrow tapered toward the through hole, the tube of The wall thickness is set so as to gradually increase toward the through hole.

According to the present invention, a housing for storing an optical element, and the optical element are optically coupled to an optical fiber introduced into the housing through a through-hole provided in a side wall of the housing. Outside of the body, in the optical element module in which the optical fiber led out from the through hole is held by the optical fiber introducing portion joined to the housing, the optical element is removed from the side wall portion where the through hole is formed. In order to reduce the amount of heat transfer to the holding casing portion, a portion where the thickness of the wall surface of the casing is thinner than the thickness of the casing portion between the side wall portion and the casing portion is The thickness of the side wall portion having the through hole is set to be thicker than the side wall in the vicinity of the side wall portion, so that the heat of the soldering iron is the portion of the through hole where the solder material is disposed. The airtight sealing work can be performed reliably in a short time. Theft is possible. Thereby, it becomes possible to reduce the failure of the optical element module at the time of manufacture and to provide a highly reliable optical element module.

It is a figure which shows the outline of the conventional optical element module, (a) is a top view, (b) shows a side view. It is a figure which shows the 1st Example of the optical element module of this invention, (a) is a top view, (b) shows a side view. It is a figure which shows the 2nd Example of the optical element module of this invention. It is an enlarged view of the part of the dotted line A of FIG. It is a figure which shows the 3rd Example of the optical element module of this invention. It is a figure which shows the 4th Example of the optical element module of this invention. It is a figure which shows the 5th Example of the optical element module of this invention. It is a figure which shows the 6th Example of the optical element module of this invention. It is a figure which shows the 7th Example of the optical element module of this invention. It is a figure explaining "the side wall of the vicinity in which the through-hole was formed" in the optical element module of this invention.

Hereinafter, the present invention will be described in detail using preferred examples.
FIG. 2 shows an embodiment of the optical element module of the present invention.
The present invention provides a housing for storing an optical element (LN element), and the optical element is optically coupled to an optical fiber introduced into the housing through a through hole provided in a side wall of the housing. In the optical element module in which the optical fiber led out from the through hole is held by the optical fiber introducing portion joined to the housing, the outside of the housing is from the side wall portion where the through hole is formed. In order to reduce the amount of heat transfer to the casing portion holding the optical element, the thickness of the wall surface of the casing between the side wall portion and the casing portion is smaller than the thickness of the casing portion. The thickness of the side wall portion having the thinned portion and forming the through hole is set to be thicker than the side wall in the vicinity of the side wall portion .

  In the optical element module of the present invention, the heat of the soldering iron is efficiently transmitted to the solder material, and the heat of the soldering iron is suppressed as much as possible from propagating through the housing to the optical element or the like. ing.

The heat transfer amount E of an object having a temperature difference can be obtained by the following equation.
E = (S × C × ΔT) / X
Where E is the amount of heat transfer [W], C is the thermal conductivity [W / m · K], S is the cross-sectional area [m ² ] of the object in the direction of heat conduction, X is the length [m] in the direction of heat conduction, ΔT is a temperature difference [° C.] between the lengths X.

  Since the thermal conductivity C is determined by the material of the package that is the casing (16.7 [W / m · K] in the case of SUS303 or SUS304), it is constant unless the material is changed. The temperature difference ΔT is constant because it is related to manufacturing conditions such as the soldering iron used. Further, the length X is a distance between two points causing a temperature difference, and the position of the soldering iron and the length to the through hole, from the through hole or the soldering iron to the place where the optical element is disposed. Is a constant value set in advance. Therefore, in order to increase the heat transfer amount E, it can be considered that the cross-sectional area S of the object is increased, for example, the thickness is increased, instead of using a material having high thermal conductivity. On the other hand, in order to reduce the heat transfer amount E, it is conceivable to reduce the cross-sectional area S or reduce the thickness, for example, instead of using a material having a low thermal conductivity.

  The meaning of “lowering the heat transfer amount” in the present invention means reducing the heat transfer amount E propagating in the heat conduction direction.

  In the first embodiment shown in FIG. 2, as the “configuration for reducing the amount of heat transfer”, the thickness d1 of the side wall in the vicinity of the through hole (solder sealing portion) is set to a housing holding the optical element (LN element). It is set to be thinner than the thickness D of the body part (the bottom wall in FIG. 2B). Not only the thickness d1 of the side wall in which the through hole is formed, but also the thickness d2 of another side wall from the side wall to the portion holding the optical element (see FIG. 2A) and the thickness d3 of the bottom wall (FIG. 2). Similarly, with respect to (b), by setting it thin, it is possible to effectively suppress heat conduction to the optical element.

  In FIG. 2 used for the description of the first embodiment, the thickness of the side wall and the bottom wall of the package body up to the adhesive fixing part using the optical adhesive or the resin adhesive is uniform (d1 to d3). It has become. However, as in the third embodiment shown in FIG. 4, the wall surface and bottom surface of the package main body of the adhesive fixing portion in which the optical adhesive or the resin-based adhesive is used, even in the case where the projection is partially formed. As long as there is at least a locally thin portion (thickness d1) compared to the thickness (thickness D), the thickness may not be uniform. Further, such a convex portion can be used for providing a screw hole for fixing the optical element module.

  FIG. 5 shows a fourth embodiment and shows an application example of FIG. It is also possible to add a configuration in which a further thinner portion (see the portion indicated by the thickness d4 in FIG. 5B) is formed on a part of the bottom wall thickness d3 to locally lower the heat transfer amount. is there.

  In addition, as in the fifth embodiment shown in FIG. 6, the configuration in which the amount of heat transfer is reduced is such that the thermal conductivity of the material forming the side wall in the vicinity of the through hole (housing B) is the housing that holds the optical element. It can be set to be lower than the thermal conductivity of the material forming the body part (housing A).

As described above, the thickness of the package is reduced in order to reduce the heat transfer amount E to the adhesive fixing part using the optical adhesive or the resin adhesive used for the optical element or the like. The same effect can be obtained by using a material having a small C content. For example, the material of the package body excluding the solder sealing portion may be a plastic material having a low thermal conductivity C (10 [W / m · K] or less).

The present invention is focused on "the side walls near the through holes are formed", which, as shown in FIG. 9, the holding portion of the housing holding the LN element is an optical element from the through hole ( LN element holding portion) (for example, the left side of the alternate long and short dash line in FIG. 9B). In the present invention, the “neighboring side wall” is expressed so as to reduce the amount of heat transfer. However, this does not mean that all the “neighboring side walls” are set in such a state. A case where the heat transfer amount is set low with respect to a part of the “side wall” and the effect of the present invention is achieved as a result is included in the technical scope of the present invention.

  Next, as a feature of the optical element module according to the present invention, the optical fiber introducing portion relates to the heat of the soldering iron disposed in contact with the optical fiber introducing portion, and conducts heat toward the side wall provided with the through hole. Is set to be highly efficient.

  As shown in FIG. 3, the configuration for increasing the efficiency of heat conduction is such that the inner diameter of the cylinder constituting the optical fiber introduction portion is set to a tapered shape gradually narrowing toward the through hole, and The wall thickness is set to gradually increase toward the through hole. In particular, the optical fiber is introduced so that the portion where the pre-melting solder material (see FIG. 3) of the optical fiber introduction portion is disposed is thin and the thickness near the through hole that is hermetically sealed with the solder material is thick. The inside of the part is tapered. As a result, the heat of the soldering iron is efficiently transmitted to the solder material, so that the solder material is instantaneously melted and also efficiently transmitted to the solder material that has melted and flowed (flows into the through-hole due to capillary action).

  In addition, as shown in FIG. 7, another configuration for increasing the efficiency of heat conduction with respect to the optical fiber introduction part is that the material forming the optical fiber introduction part has a side wall (housing) provided with a through hole. Is set to be higher than the thermal conductivity of the material forming the. By using a material having high thermal conductivity C, such as aluminum (237 [W / m · K]) or copper (398 [W / m · K]), for the optical fiber introduction part (introduction hole), It becomes possible to increase the heat transfer amount E and to melt the solder material in a shorter time.

  Further, as shown in FIG. 8, the optical element module of the present invention is characterized in that the thickness (d1 ′) of the side wall portion provided with the through hole is set to be thicker than the side wall (thickness d1 ″) of the through hole. With this configuration, the heat of the soldering iron is concentrated in the vicinity of the through hole, and heat is easily accumulated, so that the solder material can smoothly enter the through hole.

  As a specific example of the optical element module of the present invention, the inner shape of the optical fiber introduction portion is a tapered shape in which the thickness of the portion where the soldering iron is brought into contact is thin and the processing hole is narrow toward the through hole (φ0.5 mm) Cutting was performed so that (φ1.5 decreased to φ0.5 mm). Further, the base shape of the optical fiber introduction part was cut so as to have a diameter (φ2 mm) smaller than the outer diameter (φ2.5 mm) of the optical fiber introduction part. Furthermore, the wall thickness and bottom surface of the package body from the base of the optical fiber introduction part to the adhesive fixing part using the optical adhesive or resin adhesive closest to the base is made as thin as 1 mm to 1.5 mm, Other parts (parts on which optical devices and optical components are mounted) were cut so as to leave thick parts.

  In such an optical element module, the heat of the soldering iron is efficiently transmitted to the solder material while maintaining the same high rigidity as in the conventional parts where the deformation of the package due to mechanical external force or heat is a problem. In addition, it was confirmed that the heat of the soldering iron was difficult to be transmitted to the adhesive fixing portion where the optical adhesive or resin adhesive inside the package was used.

  By reducing the thickness of the package (housing) around the solder sealing portion (through hole) as in the present invention, the time for heating the optical fiber introducing portion with the soldering iron is shortened (previously 20-30). Productivity can be improved). In addition, since the time during which the optical fiber passing through the optical fiber introduction section is affected by the heat of the soldering iron at a high temperature (200 to 300 ° C.) is shortened, there is also a risk of damage due to heat of the optical fiber strand or coating. Can be reduced. Furthermore, the amount of heat transferred by the package or optical fiber is reduced by the heat applied by the soldering iron to the bonded portion of the LN element and the optical fiber and other optical components. Therefore, it is possible to provide a highly reliable optical module.

  As described above, according to the optical element module of the present invention, the heat of the soldering iron is efficiently concentrated on the solder material, and the optical fiber or coating, or the optical adhesive or resin inside the package (housing). It is possible to provide a highly reliable optical element module by reducing the amount of heat transfer to these so that the system adhesive does not deteriorate, reducing the failure of the optical element module during manufacturing, and providing high reliability.

Claims (2)

A housing for storing optical elements;
The optical element is optically coupled with an optical fiber introduced into the housing through a through hole provided in a side wall of the housing;
The through hole for introducing the optical fiber is hermetically sealed with a solder material;
Outside of the housing, in the optical element module in which the optical fiber led out from the through hole is held by the optical fiber introduction portion joined to the housing,
In order to reduce the amount of heat transferred from the side wall portion in which the through hole is formed to the housing portion holding the optical element, the thickness of the wall surface of the housing is between the side wall portion and the housing portion. However, the thickness of the side wall portion having a portion thinner than the thickness of the housing portion and the through hole is set to be thicker than the side wall in the vicinity of the side wall portion. Optical element module.   2. The optical element module according to claim 1, wherein an inner diameter of a cylinder constituting the optical fiber introduction portion is set to a tapered shape gradually narrowing toward the through hole, and a wall thickness of the cylinder is An optical element module, characterized in that the optical element module is set so as to gradually become thicker toward the through hole.

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