JP2848447B2 - Hermetic sealing of optical semiconductor device module - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to hermetically sealing an optical semiconductor device module.

[0002]

2. Description of the Related Art In an optical semiconductor device module, if a package is not hermetically sealed, moisture entering from the outside of the module condenses inside the optical semiconductor device module due to a temperature difference between the inside and outside of the module. In particular, in the case of a cooled optical semiconductor device module in which the temperature of a semiconductor laser is controlled by an electronic cooling device, dew condensation is particularly likely to occur because the semiconductor laser and optical components are cooled by the electronic cooling device.

When dew condensation occurs inside the optical semiconductor element module, the following trouble occurs. First, when condensation forms on a lens or an end face of an optical fiber, coupling loss between the optical semiconductor element and the optical fiber increases. Further, when dew forms between electrodes of an optical semiconductor element or the like, an operation failure occurs due to an electric short circuit. In order to solve these problems, the optical semiconductor element module is hermetically sealed.

FIG. 3 is a longitudinal sectional view showing an example of a conventional hermetically sealed structure of an optical semiconductor element module. The hermetic sealing structure includes an optical fiber lead-out hole 2, an optical fiber 3, and a solder 4 provided in a package 1.
The inner surface of the optical fiber lead-out hole 2 and the surface of the optical fiber 3 are metallized such as gold plating. The solder 4 is melted by high-frequency heating by the high-frequency heating electrode 20 or the like, and the metallized portion 2b on the inner surface of the optical fiber lead-out hole 2 and the metallized portion 3a of the optical fiber 3 are joined with the solder 4 to perform hermetic sealing.

[0005]

In this conventional hermetic sealing technique, it is necessary to partially metalize the soldered portion of the optical fiber with gold plating or the like. for that reason,
There is a problem in that the manufacturing cost of the optical fiber increases, and as a result, the optical semiconductor element module becomes expensive.

Further, during the solidification of the solder, an extra residual stress remains in the optical fiber. When the environmental temperature fluctuates, the stress is further concentrated on the optical fiber due to the thermal expansion and contraction of the package, and the optical transmission loss of the optical fiber increases, or in the worst case, the optical fiber breaks.

SUMMARY OF THE INVENTION An object of the present invention is to provide an easy-to-manufacture and inexpensive optical semiconductor element module in which airtight sealing is performed while eliminating stress concentration on an optical fiber.

[0008]

According to the present invention, in an airtight sealing structure of an optical semiconductor device module in which an optical fiber is drawn out of a package through an optical fiber lead-out hole, an inner wall of the optical fiber lead-out hole and the light By injecting a foamable plastic base material and a foaming agent that generate closed cells at the time of foaming between the fiber and the foam, and foaming in the optical fiber lead-out hole, the foamed plastic is introduced into the optical fiber and the optical fiber is led out. A structure in which the water-absorbing polymer particles are mixed with at least one of the expandable plastic base material and the foaming agent, and the water-absorbing polymer particles are filled in the fiber lead-out hole when plastic is foamed. Thus, an airtight sealing structure of the optical semiconductor element module characterized by being uniformly dispersed is obtained.

Further, according to the present invention, in an optical semiconductor device module in which an optical fiber is drawn out of a package through an optical fiber lead-out hole, closed cells are generated between the inner wall of the optical fiber lead-out hole and the optical fiber when foaming. A foamed plastic matrix is injected into at least one of the foamable plastic matrix and the foaming agent, and the foamed plastic matrix is foamed in the optical fiber lead-out hole. An optical semiconductor element module is obtained in which the optical fiber lead-out hole is hermetically sealed by being brought into close contact with the optical fiber and the inner wall of the optical fiber lead-out hole.

According to the present invention, there is provided a method for sealing an optical semiconductor element module in which an optical fiber is drawn out of a package through an optical fiber lead-out hole. Injecting a mixture of water-absorbing polymer particles into at least one of a foaming plastic base material and a foaming agent that generates closed cells, and foaming the foaming plastic base material in the optical fiber outlet hole. Sealing the optical fiber lead-out hole by bringing foamed plastic into close contact with the optical fiber and the inner wall of the optical fiber lead-out hole, thereby obtaining an optical semiconductor element module sealing method. Can be

[0011]

In the optical fiber lead-out portion of the optical semiconductor element module, a foamable plastic base material and a foaming agent that generate closed cells when foaming are injected into the optical fiber lead-out hole from the injection port and foamed. By foaming, the outer circumference of the optical fiber and the inner wall of the fiber lead-out hole are filled without gaps, and the outer circumference of the optical fiber and the plastic are brought into close contact with each other, and the inner wall of the optical fiber lead-out hole and the plastic are brought into close contact to prevent humid air from entering.
At the same time, by blending the water-absorbing polymer particles with the foamable plastic and / or the foaming agent, the water-absorbing polymer particles are evenly dispersed in the optical fiber lead-out hole at the time of foaming, so that the air-permeable plastic slightly penetrates the foamed plastic. Absorbs moisture. At that time, the water-absorbing polymer particles absorb water molecules and swell, but because they are covered with soft foamed plastic, the volume change of the water-absorbing polymer particles is not hindered and can always maintain water absorption, Higher hermetic sealing is possible.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing an optical fiber lead-out portion of an optical semiconductor device module according to an embodiment of the present invention.

The optical fiber lead-out portion of the optical semiconductor element module package 1 has a fiber lead-out hole 2 having an inner diameter slightly larger than the outer diameter of the optical fiber 3 on both sides.
The optical fiber 3 is led out through the fiber lead-out hole 2.

The optical fiber outlet hole 2 has an injection nozzle 2
The foamable plastic base material 5a containing the water-absorbing polymer particles 7 and the foaming agent 5b are injected from the injection port 2c using the inlets 1 and 22, and foamed. As a result, the optical fiber outlet hole 2
Foamed plastic 5c is made of water-absorbing polymer particles 7
Is filled in a state of being uniformly dispersed, and adheres to the outer peripheral surface of the optical fiber 3 and the inner wall 2 d of the optical fiber lead-out hole 2. Further, the water-absorbing polymer particles 7 are made of soft foamed plastic 5
c. In addition, bubbles 6 are naturally generated in the foamed plastic 5c.

As shown in FIG. 2, one injection nozzle 2
1 is for injecting the foamable plastic base material 5a containing the water-absorbing polymer particles 7 from the injection port 2c. The other injection nozzle 22 is for injecting the foaming agent 5b containing the water-absorbing polymer particles 7 from the injection port 2c.

The foamed plastic 5c is the optical fiber 3
And the inner wall 2 d of the fiber outlet hole 2. Therefore, humid air outside the module is prevented or suppressed from entering the inside of the module. That is, the optical fiber lead-out portion of the optical semiconductor element module is hermetically sealed.

Further, since the foamed plastic 5c is blended with the water-absorbing polymer particles 7, the slight amount of moisture in the air that permeates the foamed plastic is reduced by the water-absorbing polymer particles 7.
Is absorbed by Therefore, the water-absorbing polymer particles 7 change from the water-absorbing polymer particles 7b containing no water to the water-absorbing polymer particles 7a that have absorbed water, and enhance the effect of preventing the entry of water into the module.

The water-absorbing polymer particles 7 may be incorporated only into the foamable plastic base material 5a,
b may be blended only, or both may be blended, that is, it may be blended in at least one of these.

[0020]

As described above, according to the present invention,
Filling the foamed plastic with closed cells between the optical fiber and the optical fiber lead-out hole, and dispersing the water-absorbing polymer particles in the foaming agent in the plastic prevents the humid air from entering the module. This can prevent dew condensation between the electrodes of the optical system unit and the optical semiconductor element. The thermal stress on the optical fiber caused by the thermal expansion / contraction of the package can be reduced by elastically deforming the foamed plastic.

In addition, since the water-absorbing polymer particles are preliminarily blended into the foamable plastic base material and the foaming agent, and then injected into the fiber lead-out hole and foamed, the pre-compression in the application of the adhesive or the heat curing process is performed. Since there is no need for a step or the like and no pretreatment such as adhesion of a metal film to the optical fiber is required, there is an advantage that the production is easy and the cost is low.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an optical fiber lead-out portion of an optical semiconductor element module according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a longitudinal sectional view showing an example of an optical fiber lead-out part of a conventional optical semiconductor element module.

[Explanation of symbols]

 Reference Signs List 1 optical semiconductor element module package 2 optical fiber lead-out hole 2c inlet 2d inner wall of optical fiber lead-out hole 3 optical fiber 5a foamable plastic base material 5b foaming agent 5c foamed plastic 6 bubble 7 water-absorbing polymer particles 7a absorbed water Water-absorbing polymer particles 7b Water-absorbing polymer particles containing no water 20 Electrode for high frequency heating 21, 22 Injection nozzle

Claims (4)

(57) [Claims] In an airtight sealing structure of an optical semiconductor device module in which an optical fiber is drawn out of a package through an optical fiber lead-out hole, a closed cell is formed between the inner wall of the optical fiber lead-out hole and the optical fiber when foaming. Injecting a foamable plastic base material and a foaming agent that generates a foam, and foaming in the optical fiber lead-out hole, a structure in which the foamed plastic is brought into close contact with the optical fiber and the inner wall of the optical fiber lead-out hole, Water-absorbing polymer particles are blended into at least one of the expandable plastic base material and the foaming agent, and the water-absorbing polymer particles are uniformly dispersed in the fiber lead-out hole during foaming of the plastic. Hermetically sealed structure of an optical semiconductor element module. 2. An optical semiconductor device module in which an optical fiber is drawn out of a package through an optical fiber lead-out hole, wherein a foamable plastic mother member that generates closed cells when foaming is formed between an inner wall of the optical fiber lead-out hole and the optical fiber. A mixture of at least one of a material and a foaming agent with water-absorbing polymer particles is injected, the foamable plastic base material is foamed in the optical fiber lead-out hole, and the foamed plastic is applied to the optical fiber. An optical semiconductor element module, wherein the optical fiber lead-out hole is hermetically sealed by closely contacting an inner wall of the optical fiber lead-out hole. 3. The optical semiconductor device module according to claim 2, wherein the water-absorbing polymer particles are uniformly dispersed in the fiber outlet hole. 4. A method for sealing an optical semiconductor element module in which an optical fiber is drawn out of a package through an optical fiber lead-out hole, wherein a closed cell is generated between the inner wall of the optical fiber lead-out hole and the optical fiber during foaming. Injecting a mixture of water-absorbing polymer particles into at least one of a foamable plastic base material and a foaming agent, and foaming the foamable plastic base material in the optical fiber lead-out hole, to form a foamed plastic. A method for sealing an optical semiconductor element module, comprising: sealing the optical fiber lead-out hole by hermetically contacting the optical fiber and the inner wall of the optical fiber lead-out hole.