JP2005070558A - Optical waveguide, and light/electricity consolidated substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical waveguide which has a high heat resistance and excellent photoconduction wave performance and can be manufactured at a low cost by a simple process and a light/electricity consolidated substrate. <P>SOLUTION: At least either of a core 11 and clads 5 and 12 is formed of a resin composition containing an oligomer expressed by general formula (A) and a cured material thereof. In the formula; R<SB>1</SB>represents a glycidyl group, R<SB>2</SB>represents a glycidyl group or allyl group; R<SB>3</SB>and R<SB>4</SB>represent methyl groups or hydrogen; and (n) represents an integer of ≥0. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical waveguide used for an optical element, an optical wiring board, an optical / electrical hybrid circuit board, etc., and an optical / electrical circuit used in the optical field, micro-optical field, optical information transmission field, optical information processing field, etc. The present invention relates to a mixed substrate.

  As an optical waveguide used for information processing by light and the like, an optical waveguide using a polymer resin that can be formed by using an inexpensive material and a simple process has been studied. In this background, the light that has been the bottleneck in the past due to the fact that the frequency of information transmission is increasing and the limit of electric wiring is approaching, and the emergence of surface-emitting lasers (VCSEL), which are surface-mounted light-emitting elements. It is considered that the cost of the device is reduced and the cost of the entire system using the optical waveguide including mounting is considered to be lowered to an industrially usable level (Nikkei Electronics, December 2001). 3rd issue, see P109-).

  A surface-emitting laser (VCSEL), which is a surface-mounted light-emitting element, is also in commercial production with an emission wavelength of 850 nm, which is the wavelength of a semiconductor laser used in general long-distance optical communication. It is different from 1300nm (1.3μm) or 1550nm (1.55μm), so it will be used separately from these long-distance communication systems. Is the majority. In such a case, the optical waveguide cross section becomes a multimode optical circuit corresponding to 40 to 100 μm square, and the optical circuit and the electric circuit, preferably a printed wiring board made of an organic material, are integrated for high-density mounting. So-called optical / electrical composite circuit boards are desired. In such an application, a level of heat resistance required for a so-called printed wiring board is required for the resin forming the optical waveguide, and at the same time, the resin needs to have a small light loss. It is also necessary to arbitrarily control the refractive index of the resin forming the optical waveguide to some extent or to impart flame retardancy to the resin.

  Here, for example, in Patent Document 1, an inexpensive optical waveguide is to be formed by a method of exposing and developing using a material blended with an alicyclic polyfunctional epoxy as a core material. However, since the cycloaliphatic polyfunctional epoxy has a low refractive index, if the refractive index of the optical waveguide is to be increased, the content of the cycloaliphatic polyfunctional epoxy has to be lowered. There is a problem in that there is a tradeoff with heat resistance resulting from use. It is also difficult to impart flame retardancy.

In this way, when forming a multimode optical waveguide by photosensitive polymer resin and photolithography, high heat resistance is realized on the premise of combining with an electric circuit board, and the refractive index is controlled without sacrificing heat resistance. In reality, an optical waveguide having excellent waveguide loss has not been realized.
Japanese Patent No. 30603903

  The present invention has been made in view of the above points, and an object of the present invention is to provide an optical waveguide and an optical / electrical hybrid substrate that have high heat resistance and excellent optical waveguide performance, and can be manufactured by a simple process at low cost. It is what.

  The optical waveguide according to claim 1 of the present invention is a cured product of a resin composition containing an oligomer represented by the following general formula (A) and a curing agent thereof, wherein at least one of a core and a clad is formed. It is a feature.

(Where R ₁ is a glycidyl group, R ₂ is a glycidyl group or an allyl group, R ₃ and R ₄ are methyl groups or hydrogen, and n is an integer of 0 or more)
The invention of claim 2 is characterized in that, in claim 1, the resin composition contains an alicyclic epoxy resin.

  The invention of claim 3 is characterized in that, in claim 1 or 2, the resin composition contains an oxetane resin.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the resin composition includes a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a phenol novolak type epoxy resin, and a cresol novolak type epoxy resin. It contains at least one selected epoxy resin.

  An optical / electrical hybrid substrate according to a fifth aspect of the present invention is an optical / electrical hybrid substrate in which the optical waveguide according to any one of the first to fourth aspects is formed on a surface of an electric circuit substrate provided with an electric circuit. It is a board | substrate, Comprising: The glass transition temperature of the resin cured material which forms an optical waveguide is 140 degreeC or more, It is characterized by the above-mentioned.

  The optical waveguide according to claim 1 of the present invention is formed by the resin composition containing the oligomer represented by the general formula (A) as having excellent transparency, high heat resistance, and flame retardancy. It is something that can be done. Further, it can be manufactured at low cost by a simple process using existing techniques such as photolithography and a method of forming a core in a groove formed in a clad.

  In the invention of claim 2, the alicyclic epoxy resin contained in the resin composition can form the optical waveguide with high transparency, and the refractive index can be adjusted low, and the viscosity of the resin composition The moldability can be improved by lowering the thickness.

  In the invention of claim 3, the oxetane resin contained in the resin composition can form an optical waveguide with high transparency and good electrical characteristics, and can increase the curing speed in a cationic curing system that easily exhibits high transparency. It can be obtained quickly and the moldability can be improved.

  In the invention of claim 4, the optical waveguide can be formed with high transparency and the refractive index can be adjusted high.

  The optical / electrical hybrid substrate according to claim 5 of the present invention includes the optical waveguide having the above-mentioned excellent characteristics, and the characteristics of the optical waveguide in the solder reflow processing when the electric / electronic component is surface-mounted on the electric circuit board. Can be prevented from deteriorating.

  Hereinafter, the best mode for carrying out the present invention will be described.

  An optical waveguide according to the present invention is a resin composition containing the oligomer represented by the above general formula (A) and a curing agent thereof, in which at least one of a core and a clad is formed, and has a refractive index. It can be easily controlled to a level suitable for the core or cladding, and the core can be formed by photolithography, and it has high transparency and can keep the optical waveguide loss low. The heat resistance of the optical waveguide is high, and the reliability of the optical waveguide can be increased. Hereinafter, these contents will be described in order.

First, the oligomer represented by the general formula (A), which is the most important in the present invention, will be described. This oligomer is obtained by reacting an epoxy group of a polyfunctional epoxy compound having an isocyanuric acid skeleton with a secondary amine of a compound having a hydantoin skeleton. Examples of the polyfunctional epoxy compound having an isocyanuric acid skeleton include monoallyl diglycidyl isocyanurate (abbreviated as MADGIC) and triglycidyl isocyanurate (also abbreviated as triEPoxy IsoCyanururate: TEPIC)) Can be illustrated. In the general formula (A), R ₁ is a glycidyl group and R ₂ is a glycidyl group, and TEPIC, R ₁ is a glycidyl group, and R ₂ is an allyl group is MADGIC. MADGIC is provided by Shikoku Kasei Kogyo Co., Ltd., and TEPIC is provided by Nissan Chemical Co., Ltd. As the compound having a hydantoin skeleton, dimethylhydantoin and methylhydantoin are preferable.

  In order to make these react, it is good to melt at the temperature more than each melting | fusing point, and if necessary, add a catalyst suitably and stir-mix. It has been found by the present inventors that hydantoin has a characteristic that the number of functional groups can be controlled by controlling the molar ratio because it reacts with epoxy to produce a product extending in a linear form. For example, in the case of 2 mol of epoxy resin and 1 mol of hydantoin, n = 0 in the general formula (A). In theory, in the case of 1 mol of epoxy resin and 1 mol of hydantoin, n = infinity in the general formula (A). Practically, the upper limit of the value of n is about 10.

  This oligomer is characterized by high transparency and high heat resistance of the cured product because of its rigid molecular structure. Further, since the refractive index is higher than that of the alicyclic epoxy resin, it is possible to obtain a high degree of freedom in resin design of the core of the optical waveguide. Further, since it contains a lot of nitrogen atoms, it is difficult to burn and has high flame retardancy, so that it has favorable properties for use in laminates and electronic devices.

  In addition to this oligomer, other resins can be used in combination with the resin composition used for forming the optical waveguide in the present invention.

  For example, an epoxy resin can be used, and a commercially available liquid epoxy resin or solid epoxy resin can be used as appropriate. Specific examples of the epoxy resin include alicyclic epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, biphenyl type epoxy resin having biphenyl skeleton, naphthalene ring-containing epoxy resin, dicyclopentadiene Dicyclopentadiene type epoxy resin having a skeleton, phenol novolac type epoxy resin, cresol novolac type epoxy resin, triphenylmethane type epoxy resin, bromine-containing epoxy resin, aliphatic epoxy resin, triglycidyl isocyanurate, etc. From these, only one type or two or more types can be selected and used.

  Among these epoxy resins, it is preferable to use an alicyclic epoxy resin. By using an alicyclic epoxy resin, the transparency of the cured product can be increased and the refractive index of the cured product is adjusted to be low. In addition, the viscosity of the resin composition can be lowered and the moldability can be improved. Among the alicyclic epoxy resins, those having no ester group in the molecular structure are preferable because they are excellent in hydrolysis resistance of the cured product. For example, hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, epoxidized olefins with cyclic structure and two carbon-carbon double bonds, such as epoxidized bicyclohexene and epoxidized cyclooctadiene Can be exemplified.

  Furthermore, among the above epoxy resins, it is preferable to use at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, and cresol novolac type epoxy resin. By using it, the heat resistance of the cured product can be increased and the refractive index of the cured product can be adjusted high.

  Further, an oxetane resin having a structure similar to that of an epoxy group that is a 3-membered ring ether and having a 4-membered ring ether structure that becomes a curable composition can be used in combination. For example, 3-ethyl-3-hydroxymethyloxetane (trade name “OXT-101”), 1,4-bis {[(3-ethyl-3-oxetanyl) methoxy] methyl}, available from Toa Gosei Co., Ltd. Benzene (trade name “OXT-121”), 3-ethyl-3-phenoxymethyloxetane (trade name “OXT-211”), bis (3-ethyl-3-oxetanylmethyl) ether (trade name “OXT-221”) ), 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane (trade name “OXT-212”), and a silsesquioxane skeleton with a γ- (3-ethyl-3-oxetanylmethoxy) propyl group Oxetane resin (trade name “OX-SQ”), with a structure in which 3-ethyl-3-oxetanylmethanol and phenol ether are novolakized Kisetan resin (trade name "PNOX") and the like can be exemplified. Oxetane resin has high transparency of resin, excellent electrical properties such as insulation and moisture resistance reliability of cured products, and features that chain transfer performance is high and curing speed is high in a cationic curing system that easily exhibits high transparency. It is what has.

  As described above, in the resin composition, when the oligomer and the other resin are used in combination, the ratio of the oligomer to the other resin is preferably set in a range of 10:90 to 80:20 by mass ratio. If the ratio of the oligomer is too small, it is difficult to obtain the effect of increasing the heat resistance and the refractive index, and if it is too large, there is a possibility that the moldability may be problematic or the refractive index may be difficult to control arbitrarily.

  In the present invention, the resin composition used for forming the optical waveguide contains a curing agent for curing the above oligomer or resin as an essential component. This curing agent initiates the curing reaction of the resin with active energy rays such as light or electron beam, or heat, and is called a curing initiator. Specifically, phosphonium salts, iodonium salts, sulfonium salts, silanol-aluminum complexes that initiate cationic polymerization with light or heat, diazabicycloalkenes or salts thereof, imidazoles or salts thereof, 1 to Examples thereof include tertiary amines or salts thereof, triazoles or salts thereof, organometallic complex salts, organic acid metal salts, quaternary ammonium salts, phosphines and the like. These are also referred to as curing catalysts and may be those that cause a curing reaction of an epoxy group or an oxetane group.

  Here, although not specifically limited, it is particularly preferable that the curing catalyst is a cationic polymerization catalyst that promotes self-polymerization of a resin in a cationic curing system. By using such a cationic polymerization catalyst, a cured product composed only of a highly transparent resin can be formed. Since this cured product has a three-dimensional network formed by an ether bond, it is difficult to be colored by a high temperature during curing or a high temperature received from the environment after curing, and is more suitable for an optical waveguide.

  Moreover, the hardening | curing agent which reacts with an epoxy resin or an oxetane resin, is taken in into a hardening structure, and forms the molecular structure of a three-dimensional network can be used. Curing acid anhydrides such as methyltetrahydrophthalic anhydride and methylhexahydrophthalic anhydride having one or more hydroxyl-free groups in one molecule as long as they do not interfere with the gist of the present invention such as transparency and heat resistance. Agents, phenolic curing agents such as bisphenol A having two or more phenolic hydroxyl groups in one molecule, phenol novolak, cresol novolak, naphthol novolak, and curing agents such as primary amines can be used. The molar ratio of the above stoichiometric reactive groups between the epoxy resin or oxetane resin (this is called the main agent) and the curing agent, that is, the ratio (equivalent ratio) between the main agent equivalent and the curing agent equivalent is 100: 60-100. : 120 is preferable, and 100: 75 to 100: 100 is more preferable. When it is out of this range, that is, when the curing agent equivalent of the curing agent is less than 60 with respect to 100 equivalents of the main agent, the composition becomes difficult to cure, or even if cured, the heat resistance of the cured product decreases, There exists a possibility that the intensity | strength of hardened | cured material may fall. Conversely, if the curing agent equivalent exceeds 120, the heat resistance of the cured product may be reduced, the adhesive strength after curing may be reduced, or the moisture absorption rate of the cured product may be increased.

  In the resin composition of the present invention, at least one of a silane coupling agent or a titanate coupling agent can be used as a coupling agent. When these materials are contained in the resin composition, the adhesiveness at the interface between the cured product and the circuit board is improved, and the moisture resistance reliability of the device including the circuit board can be improved.

  Here, as the silane coupling agent, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, epoxysilane such as β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ, -Aminopropyltriethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, γ-aminopropyltrimethoxysilane, γ-ureidopropyltri Aminosilane such as ethoxysilane, mercaptosilane such as 3-mercaptopropyltrimethoxysilane, p-styryltrimethoxysilane, vinyltrichlorosilane, vinyltris (β-methoxyethoxy) silane, vinyltrimethoxysilane, vinyltriethoxysila Vinyl silanes such as γ-methacryloxypropyltrimethoxysilane, epoxy-based, amino-based, and vinyl-based polymer type silanes can be used, and epoxy silane, amino silane, and mercapto silane are particularly preferable. .

  On the other hand, titanate coupling agents include isopropyl triisostearoyl titanate, isopropyl tri (N-aminoethyl / aminoethyl) titanate, diisopropyl bis (dioctyl phosphate) titanate, tetraisopropyl bis (dioctyl phosphite) titanate, tetraoctyl bis ( Ditridecyl phosphite) titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis (ditridecyl) phosphite titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, bis (dioctyl pyrophosphate) ethylene titanate, etc. are used. be able to.

  These coupling agents may be used alone or in combination of two or more. At this time, as a content rate of a coupling agent, the range of 0.1-1 mass% is preferable with respect to the resin composition whole quantity.

  Furthermore, other substances can be added to the resin composition as necessary, as long as the object of the present invention is not impaired. Examples of such substances include photosensitizers, radical stabilizers, flame retardants, low elasticity agents, colorants, diluents, antifoaming agents, ion trapping agents, and the like.

  By molding and curing the above resin composition, an optical waveguide can be formed with this cured resin. The optical waveguide is manufactured by forming a core and a clad from two types of resins having different refractive indexes, and may be any shape as long as a low refractive index clad surrounds a high refractive index core. At this time, the core can be formed with the above resin composition adjusted to have a low refractive index and the clad can be formed with the above resin composition adjusted to have a high refractive index. You may make it form with a resin composition and may form the other with other arbitrary resin. When forming an optical waveguide having such a core and clad structure, a core is formed by pouring a resin composition for the core into a groove formed by embossing in the photolithography method or exposure / development. This can be done using existing techniques such as

  Further, by forming the optical waveguide as described above on the surface of an electric circuit substrate such as a resin substrate provided with an electric circuit on the surface or inside thereof, an optical / electrical hybrid substrate can be manufactured. At this time, it is preferable that the cured resin forming the optical waveguide of the optical / electrical hybrid substrate has a glass transition temperature (Tg) of 140 ° C. or higher. If the Tg of the cured resin forming the optical waveguide is lower than 140 ° C., the characteristics of the optical waveguide may be deteriorated in the solder reflow process when the electric / electronic component is surface-mounted on the electric circuit substrate. In the temperature cycle test and the moisture resistance reliability test for evaluating whether or not the above is ensured, a defect occurs early. On the other hand, if the Tg of the cured resin forming the optical waveguide is high, there is no problem with respect to these performances, but it is generally difficult to make Tg higher than about 250 ° C. As the electric circuit board, an organic substrate including a fiber base material such as FR4 or FR5, a build-up type organic substrate not including the fiber base material, and a substrate such as an organic film such as polyimide or polyester can be used. .

  Next, the present invention will be specifically described with reference to examples.

(Synthesis of oligomer 1)
19.7 g of triglycidyl isocyanurate (manufactured by Nissan Chemical Co., Ltd., product number “TEPIC-S”, molecular weight 297) and dimethylhydantoin (manufactured by Mitsui Chemicals Fine Co., Ltd., product number “55DMH”, molecular weight 126) are placed in a stainless steel flask. The mixture was stirred and mixed for 1 hour while being melted at 150 ° C., and then taken out from the flask and allowed to cool to room temperature to obtain oligomer 1 having a melting point of 70 ° C. When GPC analysis was performed, no monomer peak was observed and oligomerization was observed. Moreover, when the epoxy equivalent measurement based on JISK7236 was performed, the epoxy equivalent was 300.

(Synthesis of oligomer 2)
Monoallyl diglycidyl isocyanurate (manufactured by Shikoku Chemicals Co., Ltd., product number “MA-DGIC”, molecular weight 281) 56.2 g and dimethylhydantoin (manufactured by Mitsui Chemicals Fine Co., Ltd., product number “55DMH”, molecular weight 126) 12.6 g Then, the mixture was stirred and mixed for 20 minutes while being melted at 150 ° C., and then taken out of the flask and allowed to cool to room temperature to obtain oligomer 2 having a melting point of 65 ° C. When GPC analysis was performed, no monomer peak was observed and oligomerization was observed. Moreover, when the epoxy equivalent measurement based on JISK7236 was performed, the epoxy equivalent was 360.

(Clad resin 1-2, core resin 1-6)
Each component is dispersed and mixed in a blending amount (parts by mass) shown in Table 1 below using a disper (manufactured by Tokushu Kika Kogyo Co., Ltd.). Prepared. Here, the raw materials used in Table 1 are as follows.

(Epoxy resin)
Resin A: Cyclohexane alicyclic epoxy resin (manufactured by Daicel Chemical Industries, product number “Celoxide 2021P”, epoxy equivalent 136)
Resin B: Bisphenol A type epoxy resin (manufactured by Dainippon Ink and Chemicals, product number “840-9S”, epoxy equivalent 185)
Resin C: Phenol novolac type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., product number “EPPN201”, epoxy equivalent 180)
(Oxetane resin)
Resin D: 1,4-bis {[(3-ethyl-3-oxetanyl) methoxy] methyl} benzene (manufactured by Toagosei Co., Ltd., product number “OXT-121”)
(Curing agent)
Curing agent A: Methylhexahydrophthalic anhydride (MHHPA, manufactured by Dainippon Ink and Chemicals, product number “B-650”, acid anhydride equivalent 168)
(Curing catalyst)
Curing catalyst A: sulfonium salt type cationic polymerization initiator (manufactured by Asahi Denka Kogyo Co., Ltd., product number “Adekaoptomer SP-172”)
Curing catalyst B: Dioctabicycloundecene octylate (manufactured by San-Apro, product number “SA-102”)
(Flame retardants)
Flame retardant: cyclophosphazene oligomer (manufactured by Otsuka Chemical Co., Ltd., product number “SPB-100”)
About these cladding resin 1-2 and core resin 1-6, the glass transition temperature (Tg), the refractive index, and the flame retardance were evaluated in the following procedure. That is, first, the resin composition is placed in a glass plate with a spacer so that the resin thickness is 1.3 mm. The clad resin 1 is heated at 120 ° C. for 30 minutes and then heated at 150 ° C. for 1 hour to be cured. Other resins were irradiated with 5 J / cm ² of UV with an ultra-high pressure mercury lamp and then thermally cured at 150 ° C. for 1 hour to prepare a cured resin plate. And the refractive index was measured for the sample cut out from this resin hardening board using the bromo naphthalene for the intermediate | middle liquid with the refractive index measuring apparatus by an Atago company. Further, Tg was evaluated by measuring a test piece from the same cured resin plate with a viscoelastic spectrometer “DMS110” manufactured by Seiko Denshi Kogyo. Similarly, the flame retardance test in accordance with UL standards was performed to evaluate the flame retardancy. The results are shown in Table 1.

  As seen in Table 1, when the clad resin 1 containing an oligomer and the clad resin 2 containing no oligomer are compared, it can be seen that the clad resin 1 is excellent in heat resistance and flame retardancy. Moreover, when comparing the core resins 1 to 5 containing the oligomer and the core resin 6 not containing the oligomer, the core resins 1 to 5 are excellent in heat resistance, can be adjusted to have a high refractive index, and are flame retardant. It turns out that it is excellent.

(Examples 1-5, Comparative Example 1)
The surface of the 12 cm square flat plate mold 1 finished to a mirror surface is subjected to bite processing, and two V grooves 2 having a depth of 60 μm and an angle of 45 degrees are formed 10 cm apart in parallel, and the surface of the mold 1 is made of fluororesin Release processing was performed. Then, the clad resin shown in Table 2 is applied to the surface of the mold 1 in which the V-groove 2 is formed, and the glass plate 4 which has been subjected to mold release treatment with a fluororesin through a spacer having a thickness of 40 μm is placed. Cured. Here, in Table 2, “heat” means curing by heat treatment at 120 ° C. for 1 hour, and “light” is 120 ° C. for 1 hour after UV irradiation of 5 J / cm ^{2 with} an ultrahigh pressure mercury lamp. This means that the resin is cured by heat treatment, and the V-grooved lower cladding 5 is formed by curing in this way (see FIG. 1A).

  On the other hand, an electric circuit 6 provided with a 12 cm square FR5 grade four-layer resin substrate in which an electric circuit 6 is provided on the inner layer and a copper foil 7 is stretched on the surface is used, and the glass plate 4 is peeled from the lower cladding 5. Thereafter, a two-component curable araldite adhesive is applied to the peeled surface, and the surface of the electric circuit board 8 from which the copper foil 7 has been removed by etching is pressed and held at a temperature of 90 ° C. for 30 minutes. Thus, the lower clad 5 and the electric circuit board 8 were bonded (see FIG. 1B).

  Next, the integrated circuit board 8 and lower clad 5 were separated from the mold 1. Then, gold was deposited to a thickness of 0.1 μm through a mask on the portion of the microprotrusion 9 formed by transferring the V groove 2 of the lower clad 5 to form a micromirror 10 (see FIG. 1C).

Next, the core resin shown in Table 2 is applied to the surface of the lower clad 5 by a spin coater so as to have a thickness of 50 μm, and projection exposure is performed through a negative pattern mask capable of forming a waveguide having a width of 50 μm perpendicular to the micromirror 10. did. The exposure at this time was performed by irradiating UV of 3 J / cm ^{2 with} an ultra-high pressure mercury lamp, and after-curing, the core 11 was formed (see FIG. 1D).

  Thereafter, the uncured resin of the core resin is washed and removed with a solvent and dried. Further, the clad resin shown in Table 2 is spin-coated so as to have a thickness of 80 μm, and the same method as that for the lower clad 5 is used. The upper clad 12 was formed by curing. As described above, an optical / electrical hybrid substrate formed by providing the optical waveguide 13 composed of the core 11 and the clads 5 and 12 on the surface of the electric circuit substrate 8 having the electric circuit 6 formed therein was obtained (FIG. 1 (e)).

  The characteristics of the optical waveguide 13 produced as described above were measured as follows. A laser beam of 850 nm is incident in a direction perpendicular to the substrate with a 50 μmφ optical fiber from directly above one of the opposing micromirrors 10, and perpendicularly toward the substrate surface by the other micromirror 10 via the core 11 of the optical waveguide 13. The optical path is bent, this light is received by an optical fiber of 125 μmφ, and guided to a power meter to measure the received light power P2. The total loss is determined by the following equation from the ratio of the power P1 measured when the optical fiber of the light emitting side of 50 μmφ and the light receiving side of 125 μmφ is abutted.

Total loss [dB] = − 10 × log (P2 / P1)
The “initial waveguide loss” in Table 2 is a total loss value obtained by measuring the optical / electrical hybrid board before the solder reflow process and the temperature cycle test.

  Also, “loss change due to solder reflow process” in Table 2 indicates that the above-mentioned optical / electrical hybrid board for which the initial waveguide loss was measured is subjected to solder reflow process with a profile of 220 ° C. or higher for 60 seconds and a peak temperature of 260 ° C. After circulation, the total loss was measured by the above method, and the difference between the total loss before and after the solder reflow treatment was taken.

  “Temperature cycleability” in Table 2 indicates that the above-mentioned optical / electrical hybrid substrate for which the initial waveguide loss was measured was: -55 ° C. for 30 minutes, room temperature for 5 minutes, 125 ° C. for 30 minutes, and room temperature for 5 minutes. A gas phase temperature cycle test is performed for one cycle, and total loss is measured every 200 cycles up to 2000 cycles, and the number of cycles in which the total loss value is twice or more the initial value is obtained.

  As can be seen from Table 2, when Examples 1 to 5 and Comparative Example 1 are compared, all of Examples have small initial waveguide loss, good solder reflow property, and temperature cycle. It turns out that it is excellent also in property.

An example of manufacture of the optical / electrical hybrid board | substrate of this invention is shown, (a) thru | or (e) is a schematic sectional drawing, respectively.

Explanation of symbols

5 Clad 6 Electrical Circuit 8 Electrical Circuit Board 11 Core 12 Clad 13 Optical Waveguide

Claims (5)

An optical waveguide characterized in that at least one of a core and a clad is formed of a cured product of a resin composition containing an oligomer represented by the following general formula (A) and a curing agent thereof.

(Where R ₁ is a glycidyl group, R ₂ is a glycidyl group or an allyl group, R ₃ and R ₄ are methyl groups or hydrogen, and n is an integer of 0 or more)   The optical waveguide according to claim 1, wherein the resin composition contains an alicyclic epoxy resin.   The optical waveguide according to claim 1 or 2, wherein the resin composition contains an oxetane resin.   The resin composition contains at least one epoxy resin selected from bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, and cresol novolac type epoxy resin. The optical waveguide according to any one of 1 to 3. 5. An optical / electrical hybrid substrate in which the optical waveguide according to claim 1 is formed on a surface of an electrical circuit substrate provided with an electrical circuit, the glass transition temperature of a cured resin product forming the optical waveguide. An optical / electrical hybrid board characterized by having a temperature of 140 ° C. or higher.

Images