JPH09243870A - Optical module manufacturing method - Google Patents

Abstract

(57) Abstract: An optical module that can be molded by heat treatment at 100 ° C. or lower is obtained. SOLUTION: The step of aligning the optical axes of a plurality of optical components including a light emitting element, a light receiving element, an optical waveguide, and an optical fiber mounted on a base substrate, and an optical path between the optical components are formed by pre-coating with a light transmitting resin. Epoxy equivalent 1 selected from bisphenol type epoxy resin having an epoxy equivalent of 180 to 500 g / eq, novolac type epoxy resin, and epoxy resin represented by the following chemical formula 8 or 9 on the optical path.
A step of covering the optical path with a photocurable resin containing 60 to 250 g / eq of an epoxy resin, an inorganic filler, and a photo-acid generator as essential components, and irradiating the photo-hardening resin with light and heating. And a step of performing. Embedded image Embedded image

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an optical module using a novel photocurable encapsulating resin composition.

[0002]

2. Description of the Related Art With the progress of optical communication technology in recent years, construction of an optical fiber network up to home is being promoted. For sealing the optical module, metal sealing or ceramic sealing has been used to protect the semiconductor laser and the light receiving element. However, these sealing methods are expensive, and there is a demand for resin sealing at a lower cost. Resin encapsulation has already been used for semiconductor encapsulation, and in that process, a low-voltage transfer molding method is used in which resin is injected into a mold heated to about 170 ° C. to encapsulate the element (Japanese Patent Laid-Open No. 5- No. 54865). However, if this sealing technique is applied to an optical module, problems such as deterioration of the optical fiber coating due to heating and distortion of fixing the optical element occur. Therefore, it is desirable to seal at a temperature as low as possible.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing an optical module which can be sealed at a low temperature by using light irradiation together.

[0004]

In order to achieve the above object, the present invention uses the following technical means.
The first means is a step of aligning the optical axes of a plurality of optical components such as a light emitting element, a light receiving element, an optical waveguide, and an optical fiber mounted on a base substrate, and pre-coating an optical path between the optical components with a light transmitting resin. And (a) a bisphenol type epoxy resin having an epoxy equivalent of 180 to 500 g / eq, and (b) a novolac type epoxy resin on the optical path, and an epoxy resin represented by the general formula 3 or 4.

[0005]

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[0006]

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Epoxy equivalent of 160 to 2 selected from
50 g / eq of epoxy resin, (c) inorganic filler,
(D) a step of covering the optical path with a photocurable resin containing a photoacid generator as an essential component, and irradiating the photocurable resin with light,
And a step of heating the optical module.

The second means is that (a) is 5 to 30 parts by weight,
5 to 40 parts by weight of (b), 50 to 95 parts by weight of (c),
(D) is a method for manufacturing an optical module using a photocurable resin having 1 to 30 parts by weight.

In the third means, (c) is IIa genus, IIIa genus,
A method for producing an optical module using a photocurable resin which is at least one kind of inorganic chemical compound selected from Group IVa hydroxides, oxides and carbonates.

In the fourth means, (c) is calcium carbonate,
It is a method for producing an optical module using a photocurable resin that is at least one inorganic compound selected from magnesium hydroxide, aluminum hydroxide, and silicon oxide.

The fifth means is that (d) has a wavelength of 300 nm.
The above-mentioned method for producing an optical module is an acid generator that generates an acid by light. Since the epoxy resin that crosslinks with an acid catalyst has absorption at a wavelength of 300 nm or less, the concentration of the acid generated by exposure does not significantly decrease in the film thickness direction, so that a compound that generates an acid by light of 300 nm or more is required. is there.

In the resin encapsulation of a semiconductor, a thermosetting reaction at around 170 ° C. is used. As a result of studying a resin that can be cured at a low temperature, it was found that a system composed of an acid generator that generates an acid upon irradiation with light and an epoxy resin is sufficiently cured at a temperature of 100 ° C. or lower. The curing temperature in the present invention may be a temperature at which the coupling loss due to deterioration of the optical element, solder, adhesive, etc. can be suppressed. Particularly, at a curing temperature of 100 ° C. or lower, deterioration of the coating of the optical fiber and coupling loss due to thermal strain can be significantly reduced.

The bisphenol type epoxy resin as the component (a) is to improve the adhesiveness to the substrate and the crack resistance.
In particular, it has the effect of suppressing a rapid increase in the elongation (coefficient of linear expansion) above the glass transition temperature, and has an epoxy equivalent of 250
~ 500 g / eq of epoxy resin. This shortens the cross-linking point distance and raises the glass transition temperature of the cured product.
As the epoxy resin, bisphenol A, F or S
Type epoxy resins, or their halides.

The epoxy resin as the component (b) is one that increases the crosslink density of the cured product and raises the glass transition temperature, and is preferably an epoxy resin having an epoxy equivalent of 160 to 250 g / eq. For epoxy resin, phenol novolac type, cresol novolac type, or their halides, general formula 5

[0015]

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General formula

[0017]

[Chemical 6]

There is an epoxy resin represented by

Further, in these resin moldings, when molded at a normal molding temperature, the glass transition temperature becomes high, so that the amount of heat shrinkage decreases and the amount of strain can be greatly reduced.

In addition, the epoxy resin used in the encapsulating resin composition of the present invention is one which has a glass transition temperature higher than the molding temperature and has a plurality of epoxy groups in one molecule. May be. As such an epoxy resin, in addition to the epoxy resin, a bifunctional or more epoxy resin having a biphenyl skeleton or a dicyclopentadiene skeleton in the molecule, an alicyclic epoxy resin, or an epoxy resin obtained by brominated the above epoxy resin. And so on.

The inorganic filler as the component (c) is used for the purpose of reducing the thermal expansion coefficient of the epoxy molding material, and
It is used for increasing strength, and general inorganic fillers such as talc, clay, silica, calcium carbonate, aluminum hydroxide, magnesium hydroxide, glass fiber and ceramic fiber can be used.

The photoacid generator as the component (d) is one which generates an acid which is a cationic polymerization catalyst of the epoxy resin at the time of exposure. The acid generator is an onium salt represented by a triarylsulfonium salt or a diaryliodonium salt, a halide, an alkylsulfonic acid ester, an arylsulfonic acid ester, an iminosulfonic acid ester, a nitrobenzylsulfonic acid ester, or α-hydroxymethylbenzoinsulfonic acid. Examples include esters, N-hydroxyimide sulfonates, α-sulfonyloxyketones, disulfonyldiazomethanes, and disulfones. Although some of the above-mentioned acid generators have low acid generation efficiency under light having a wavelength of 300 nm or more, they can be used in the present invention by using a sensitizer. Examples of such sensitizers are Michler's ketone, dihydroxybenzene, trihydroxybenzene, hydroxyacetophenone, bisphenol A, dihydroxydiphenylmethane, dihydroxydiphenyl sulfone,
Dihydroxydiphenyl sulphate, gallic acid ester,
Examples include 9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, benzophenothiazine, methoxyphenothiazine, and trifluoromethylphenothiazine.

In the present invention, a curing agent having a phenolic hydroxyl group may be contained. Any one may be used as long as it has a plurality of phenolic hydroxyl groups in one molecule. As such a curing agent, bisphenol A, F or S, phenol novolac, cresol novolac, or bisphenol having a bisphenyl skeleton in the molecule, represented by the general formula 7.

[0024]

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Trishydroxyphenylmethane type polyfunctional phenol curing agents, those having a naphthalene skeleton, those having a dicyclopentadiene skeleton, polymers of the above resins, or a mixture of several kinds are used. These are used according to various properties such as resin reactivity and fluidity, as well as moisture absorption and mechanical properties of the cured product.

A curing accelerator for promoting the curing reaction may be added to the encapsulating resin composition used in the present invention. The curing accelerator used in the present invention is not particularly limited as long as it accelerates the curing reaction of the epoxy resin. Usually, triphenylphosphine, triphenylphosphonium-triphenylborate, tetraphonylphosphonium-tetraphenylborate, which has good storage stability and moldability of the epoxy resin composition, and electrical characteristics after curing, And those derivatives containing phosphorus in the molecule, triethylenediamine, diaminodiphenylmethane, 1,8-diazabicyclo (5,4,4)
0) -amine-based compounds such as undecene, imidazole and derivatives thereof, trifluoroborolone-amine complex,
There is a sulfonium salt, and one kind or two or more kinds may be added to the epoxy resin and used. The addition amount can be arbitrarily determined according to the moldability of the epoxy resin composition and the physical properties of the cured product. For the purpose of increasing the glass transition temperature, amine-based, particularly imidazole-based curing accelerators are suitable.

To the encapsulating resin composition used in the present invention, in addition to the above materials, if necessary, a filler, a release agent, a coloring agent, a coupling agent, a flexibilizing agent, a flame retardant, etc. may be added. There is. The filler is used for the purpose of reducing the thermal expansion coefficient of the epoxy molding material and for increasing the strength, and includes talc, clay, silica, calcium carbonate, aluminum hydroxide, magnesium hydroxide, glass fiber, ceramic fiber, etc. All inorganic fillers can be used.

The content of the filler is 50% by weight to 95% by weight.
However, if it is less than 50% by weight, a sufficient effect cannot be obtained for reducing the thermal expansion coefficient and improving the strength. Further, if the content is more than 95% by weight, the closest packing density of the filler will be less than the content of the epoxy resin matrix, making it difficult to prepare a molding material, and the viscosity after preparation will be extremely high, resulting in moldability. descend. 7 to adjust the heat shrinkage
0 to 90% by weight is suitable.

The release agent facilitates release from the molding die, and carnauba wax, montan wax, polyolefin wax may be used alone or in combination. The addition amount is preferably 0.01 to 5% by weight of the total amount. That is, if it is less than 0.01%, the releasability is not effective, and if it exceeds 5%, the adhesiveness to the light emitting element, the light receiving element and the optical waveguide is deteriorated. It is desirable to use carbon black as the colorant. Toughened cured products,
The flexibilizer, which is blended to reduce the elastic modulus, is an amino group or epoxy group that is incompatible with the epoxy resin, a butadiene-acrylonitrile copolymer having a carboxyl group terminal, or an amino group or hydroxyl group at the terminal or side chain. , Epoxy group, carboxyl group modified silicone resin type flexibilizer, etc. are used.

The above materials are blended, mixed, kneaded, pulverized and further granulated as required to obtain an epoxy resin molding material. The kneading is generally performed with a hot roll or an extruder. A solvent may be added to adjust the viscosity. The optical module of the present invention can be obtained by using the epoxy resin composition thus obtained to seal an optical element and a semiconductor chip on a carrier substrate after or while being irradiated with light. Low-pressure transfer molding is usually used as the manufacturing method, but in some cases, compression molding, casting or the like may be used.

The light-transmitting resin for precoating the optical path in the present invention varies depending on the wavelength used for optical communication to be used.
Any material can be used as long as it is transparent at the wavelength and has heat resistance at the sealing temperature or higher. Polyimide, fluorinated polyimide, polymethylmethacrylate, polyurethane, epoxy resin, etc. are available. Alternatively, a photocurable resin may be used.

By using the photo-curable encapsulant, the curing temperature can be reduced to 100 ° C. or lower.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION

(Example 1) 10 parts by weight of an ortho-cresol novolac type epoxy resin having an epoxy equivalent of 189 g / eq, 10 parts by weight of a bisphenol A type epoxy resin having an epoxy equivalent of 475 g / eq, 1 part by weight of diphenyliodonium triflate and a curing accelerator. 0.15 parts by weight of triphenylphosphine, 0.4 parts by weight of antimony trioxide as a flame retardant auxiliary, and 0.1 parts of epoxylane as a coupling agent.
5 parts by weight, 0.1 parts by weight of montanic acid ester as a release agent, and 85 parts by weight of a mixture of fused silica having an average particle diameter of 28 μm at a ratio of 3/7 as a filler, and photocurable. An epoxy resin composition material was produced. The kneading of the material was performed for 10 minutes using a biaxial hot roll (65 to 85 ° C.). As shown in FIG. 1, a semiconductor laser, a photodiode, an optical waveguide, and an optical fiber are fixed on the substrate on which the optical parts are mounted by aligning the optical axes so that the optical loss is minimized, and the optical path between the optical parts. Is coated with a polyimide solution obtained from 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride and 2,2-bis (trifluoromethyl) -4,4'-diaminodiphenyl by the potting method. Dried. The substrate on which the optical path was formed was fixed to a mold made of polymethylpentene resin, the photo-curable epoxy resin was transferred to the mold, and the light of the ultra-high pressure mercury lamp was 3 J /
It was irradiated with cm ² and then heated at 80 ° C. for 20 minutes to be molded. As a result, each element, the optical fiber, and the coating thereof were not damaged, and a resin-sealed optical module with a Bacol strength of 60 was obtained.

(Embodiment 2) The light of an ultra-high pressure mercury lamp is 3 J / cm.
² The same examination as in Example 1 was carried out except that heating was performed at 100 ° C. for 20 minutes while irradiating. As a result, a resin-sealed optical module having a Bacol strength of 70 was obtained without damaging each element, the optical fiber or the coating thereof.

Example 3 The same study as in Example 1 was conducted using bis (4-tertbutylphenyl) iodonium triflate instead of the diphenyliodonium triflate of Example 1. As a result, a resin-sealed optical module having a Bacol strength of 60 was obtained without damaging each element, the optical fiber, or the coating thereof.

Example 4 Instead of the diphenyliodonium triflate of Example 1, 2- (3,4,5-trimethoxystyryl) -4,6-bis (trichloromethyl) -1,3,5-triazine was used. The same examination as in Example 1 was carried out using. As a result, a resin-sealed optical module having a Bacol strength of 60 was obtained without damaging each element, the optical fiber, or the coating thereof.

Example 5 Instead of the diphenyliodonium triframe of Example 1, 2- (4-methoxynaphthyl) -4,6-bis (trichloromethyl) -1,3,3 was used.
The same examination as in Example 1 was conducted using 5-triazine.
As a result, a resin-sealed optical module having a Bacoal strength of 60 was obtained without damaging each element, the optical fiber or the coating thereof.

Example 6 In place of the diphenyliodonium triflate of Example 1, 2-naphthoylmethyltetramethylene sulfonium triflate was used.
The same examination was performed. As a result, the Bacol strength of 60 can be achieved without damaging each element, the optical fiber or the coating.
A resin-sealed optical module of was obtained.

Example 7 A study was conducted in the same manner as in Example 1 except that N-trifluoromethylsulfonyloxynaphthalimide was used instead of the diphenyliodonium triframe of Example 1. As a result, a resin-sealed optical module having a Bacol strength of 60 was obtained without damaging each element, the optical fiber, or the coating thereof.

Example 8 Epoxy equivalent of Example 1 18
The same examination as in Example 1 was conducted using 20 parts by weight of the 9 g / eq ortho-cresol novolak type epoxy resin instead of 10 parts by weight of the epoxy resin. As a result, a resin-sealed optical module having a Bacol strength of 65 was obtained without damaging each element, the optical fiber, or the coating thereof.

(Example 9) Epoxy equivalent of Example 1 was 18
The same examination as in Example 1 was conducted using an epoxy resin having a naphthalene skeleton having an epoxy equivalent of 163 g / eq instead of the 9 g / eq orthocresol novolac type epoxy resin.
As a result, a resin-sealed optical module having a Bacol strength of 70 was obtained without damaging each element, the optical fiber or the coating thereof.

Example 10 Epoxy equivalent of Example 1 1
Example 1 A tris (hydroxyphenyl) methane type epoxy resin having an epoxy equivalent of 176 g / eq was used in place of the 89 g / eq orthocresol novolac type epoxy resin.
The same examination was performed. As a result, a resin-sealed optical module having a Bacol strength of 65 was obtained without damaging each element, the optical fiber or the coating thereof, as in Example 1.

Example 11 Fused silica 85 of Example 1
The same examination as in Example 1 was conducted using 50 parts by weight of calcium carbonate instead of parts by weight. As a result, a resin-sealed optical module having a Bacol strength of 60 was obtained without damaging each element, the optical fiber, or the coating thereof.

Example 12 20 parts by weight of tetrahydrofuran was added to the composition of Example 1 and the same examination as in Example 1 was conducted. As a result, a resin-sealed optical module having a Bacol strength of 65 was obtained without damaging each element, the optical fiber, or the coating thereof.

Comparative Example 1 The same composition as in Example 1 was examined except that diphenyliodonium triflate was not added. As a result, curing was insufficient.

Comparative Example 2 Tris (methanesulfonyloxy) instead of diphenyliodonium triflate
The same composition as in Example 1 was investigated except that benzene was added. Since tris (methanesulfonyloxy) benzene is an acid generator that does not have a light absorption intensity of 300 nm or more, curing was insufficient.

[0047]

By using the epoxy resin composition of the present invention, encapsulation can be performed at 100 ° C. or lower, and damage to optical elements and optical fibers in an optical module can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of an optical module according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical fiber, 2 ... Fiber block, 3 ... Photocurable sealing material, 4 ... Transparent precoat material, 5 ... Laser diode, 6 ... Waveguide substrate, 7 ... Base substrate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Eguchi 7-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi Research Laboratory

Claims (5)

[Claims] 1. A step of aligning the optical axes of a plurality of optical components including a light emitting element, a light receiving element, an optical waveguide, and an optical fiber mounted on a base substrate, and pre-coating an optical path between the optical components with a light transmitting resin. Step of forming, bisphenol type epoxy resin having an epoxy equivalent of 180 to 500 g / eq on the optical path, novolac type epoxy resin, epoxy resin represented by the general formula 1 or 2. Embedded image A step of covering the optical path with a photocurable resin containing an epoxy resin having an epoxy equivalent of 160 to 250 g / eq, an inorganic filler, and a photo-acid generator as essential components,
A step of irradiating the photocurable resin with light and heating the resin. 2. The bisphenol type epoxy resin is 5 to
30 parts by weight, 5 to 40 of the novolac type epoxy resin
The method for manufacturing an optical module according to claim 1, wherein the amount of the inorganic filler is 50 to 95 parts by weight, and the amount of the photo-acid generator is 1 to 30 parts by weight. 3. The inorganic filler is IIa group, IIIa group, IVa group.
The method of manufacturing an optical module according to claim 1, wherein the optical module is at least one inorganic chemical selected from hydroxides, oxides, and carbonates of the genus. 4. The method of manufacturing an optical module according to claim 1, wherein the inorganic filler is at least one inorganic compound selected from calcium carbonate, magnesium hydroxide, aluminum hydroxide and silicon oxide. 5. The method for manufacturing an optical module according to claim 1, wherein the photo-acid generating material generates an acid with light having a wavelength of 300 nm or more.