JP2002296435A - Device for optical communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for optical communication which has low connection loss between mounted optical components and has excellent connection reliability. SOLUTION: In the device for optical communication consisting of a substrate for mounting an integrated circuit chip and a multilayer printed circuit board, a light receiving element and a light emitting element are mounted at the side of the board for mounting the integrated circuit chip opposed to the multilayer printed circuit board so that the light receiving part and the light emitting part are exposed, respectively. An optical waveguide is formed at the side of the multilayer printed circuit board opposed to the substrate for mounting the integrated circuit chip. An optical signal is transmitted through the optical waveguide and the light receiving element or the light emitting element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a device for optical communication.

In recent years, attention has been focused on optical fibers mainly in the field of communications. In particular, in the field of IT (information technology), communication technology using optical fibers is required for maintenance of a high-speed Internet network. Optical fiber has low loss,
It has features such as high bandwidth, small diameter and light weight, no induction, and resource saving.A communication system using optical fibers with this feature has a higher number of repeaters than a communication system using a conventional metallic cable. Can be greatly reduced, construction and maintenance become easier, economical communication system,
High reliability can be achieved.

In addition, since an optical fiber can simultaneously multiplex not only light of one wavelength but also light of many different wavelengths through one optical fiber, a large-capacity optical fiber can be used for various applications. A transmission path can be realized, and it is possible to support video services and the like.

[0004] In such network communication such as the Internet, optical communication using an optical fiber is used not only for communication on the backbone network but also for communication between the backbone network and terminal equipment (PC, mobile, game, etc.). It has also been proposed to use it for communication between terminal devices. In the case where optical communication is used for communication between the backbone network and the terminal equipment, it is necessary to attach an optical communication device to the terminal equipment. The optical communication device includes an optical waveguide for transmitting an optical signal to a substrate, an optical waveguide, and the like. There has been proposed one provided with optical components such as a light receiving element and a light emitting element for processing a signal.

[0005]

However, the conventional optical communication device has not been sufficiently satisfactory in connection reliability. This is a factor for achieving optical communication with excellent connection reliability, that is, in connection between optical components (for example, connection between an optical fiber and an optical waveguide or connection between an optical waveguide and a light receiving element or a light emitting element). This is considered to be because the low connection loss could not be sufficiently ensured.

[0006]

Means for Solving the Problems Accordingly, the present inventors have:
As a result of intensive studies to ensure a low connection loss in the connection between the optical components, when mounting the optical components on the substrate and / or in the substrate, each optical component is mounted at a predetermined position, By conceiving that a low connection loss can be ensured by eliminating the displacement of the optical components, the optical communication device of the present invention having the following configuration has been completed.

That is, the optical communication device of the present invention comprises an IC
An optical communication device comprising a chip mounting board and a multilayer printed wiring board, wherein the IC chip mounting board has a light receiving portion and a light emitting portion exposed on a side facing the multilayer printed wiring board. A light receiving element and a light emitting element are mounted on the multilayer printed wiring board, and an optical waveguide is formed on the side facing the IC chip mounting substrate, and the optical waveguide and the light receiving element or the light emitting element are It is characterized in that it is configured to be able to transmit an optical signal through the optical disc.

In the optical communication device according to the present invention, the substrate for mounting an IC chip is formed by laminating a conductor circuit and an interlayer resin insulating layer on the substrate, and the conductor circuits sandwiching the substrate are formed by through holes. Preferably, the conductor circuits connected to each other with the interlayer resin insulation layer interposed therebetween are connected by via holes, and the multilayer printed wiring board is formed by laminating a conductor circuit and an interlayer resin insulation layer on a substrate, It is desirable that the conductor circuits sandwiching the substrate be connected by through holes, and the conductor circuits sandwiching the interlayer resin insulation layer be connected by via holes.
In the optical communication device according to the present invention, it is preferable that the IC chip mounting substrate and the multilayer printed wiring board have solder bumps formed thereon for transmitting electric signals.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical communication device according to the present invention will be described. The optical communication device according to the present invention comprises an IC
An optical communication device comprising a chip mounting board and a multilayer printed wiring board, wherein the IC chip mounting board has a light receiving portion and a light emitting portion exposed on a side facing the multilayer printed wiring board. A light receiving element and a light emitting element are mounted on the multilayer printed wiring board, and an optical waveguide is formed on the side facing the IC chip mounting substrate, and the optical waveguide and the light receiving element or the light emitting element are It is characterized in that it is configured to be able to transmit an optical signal through the optical disc.

An optical communication device according to the present invention comprises an IC chip mounting substrate having a light receiving element and a light emitting element mounted at predetermined positions, and a multilayer printed wiring board having an optical waveguide formed at a predetermined position. Therefore, the connection loss between the mounted optical components is low, and the connection reliability is excellent as an optical communication device.

In the optical communication device of the present invention, when the substrate for mounting an IC chip and the multilayer printed wiring board are connected via solder bumps, the two are connected by a self-alignment action of the solder. It can be more reliably arranged at a predetermined position. Note that the self-alignment action refers to an action in which the solder resist layer repels the solder so that the solder tends to exist in a more stable shape near the center of the solder bump forming opening due to its own fluidity during the reflow process. When this self-alignment action is used, when connecting the IC chip mounting substrate to the multilayer printed wiring board via the solder bumps, it is assumed that a positional shift has occurred between the two before the reflow. Also, at the time of reflow, the IC chip mounting substrate moves, and the IC chip mounting substrate can be mounted at an accurate position on the multilayer printed wiring board.
Therefore, if optical components such as a light receiving element, a light emitting element, and an optical waveguide are mounted at precise positions on the IC chip mounting substrate and the multilayer printed wiring board, respectively, the multilayer printed wiring is formed via solder bumps. By connecting the substrate for mounting an IC chip on a board, an optical communication device having excellent connection reliability can be manufactured.

A light receiving element and a light emitting element are mounted on an IC chip mounting substrate constituting the optical communication device on a side facing the multilayer printed wiring board so that the light receiving section and the light emitting section are exposed. I have. As the light receiving element, for example, PD (photodiode), APD
(Avalanche photodiode). These may be appropriately used in consideration of the configuration of the optical communication device, required characteristics, and the like. Examples of the material for the light receiving element include Si, Ge, and InGaAs. Among them, InGaAs is preferred because of its excellent light receiving sensitivity.
Is desirable.

Examples of the light emitting element include an LD (semiconductor laser), a DFB-LD (distributed feedback semiconductor laser), and an LED (light emitting diode). These may be appropriately used in consideration of the configuration, required characteristics, and the like of the optical communication device.

As a material of the light emitting device, gallium,
Arsenic and phosphorus compounds (GaAsP), gallium, aluminum and arsenic compounds (GaAlAs), gallium and arsenic compounds (GaAs), indium, gallium and arsenic compounds (InGaAs), indium, gallium, arsenic and phosphorus compounds ( InGaAs
P) and the like. These may be used properly in consideration of the communication wavelength. For example, when the communication wavelength is in the 0.85 μm band, GaAlAs can be used, and when the communication wavelength is in the 1.3 μm band or 1.55 μm band. Is InGa
As or InGaAsP can be used. Also,
It is preferable that the IC chip mounting substrate is formed with solder bumps for transmitting electric signals. Thereby, electric signals can be transmitted to and from the external electronic component.

In the multilayer printed wiring board constituting the optical communication device, an optical waveguide is formed on the side facing the IC chip mounting substrate. Therefore, transmission of an optical signal can be performed via the optical waveguide.

Examples of the material of the optical waveguide include quartz glass, a compound semiconductor, and a polymer material. Among these, polymers are desirable because they are excellent in workability, have excellent adhesion to the interlayer resin insulating layer of the multilayer printed wiring board, and are low in cost.

As the polymer material, conventionally known materials can be used. Specifically, for example, PMMA
(Polymethyl methacrylate), acrylic resin such as deuterated PMMA, deuterated fluorinated PMMA, etc .; polyimide resin such as fluorinated polyimide; epoxy resin; UV-curable epoxy resin; silicone resin such as deuterated silicone resin; And polymers produced from butene.

The optical waveguide has a thickness of 5 to 50 μm.
And its width is preferably 1 to 50 μm. In the multilayer printed wiring board, the optical waveguide formed at a position facing the light receiving element of the IC chip mounting substrate and the optical waveguide formed at a position facing the light emitting element of the IC chip mounting substrate are made of the same material. Desirably, it consists of Preferably, an optical path conversion mirror is formed in the optical waveguide. This is because the optical path can be changed to a desired angle by forming the optical path conversion mirror. The formation of the optical path conversion mirror can be performed, for example, by grinding one end of the optical waveguide, as described later. It is preferable that the multilayer printed wiring board has solder bumps for transmitting electric signals. Thereby, electric signals can be transmitted to and from the external electronic component.

In the optical communication device of the present invention, the substrate for mounting an IC chip and the multilayer printed wiring board are arranged so that the light receiving element, the light emitting element, and the optical waveguide face each other, and The optical signal is transmitted through the element or the light emitting element and the optical waveguide.

Specifically, for example, by connecting the two via solder bumps, the light receiving element and the light emitting element can be arranged at a predetermined position facing the optical waveguide. This is because the self-alignment action of the solder can be used.

Hereinafter, an example of an embodiment of the optical communication device having the above configuration will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing one embodiment of the optical communication device of the present invention. FIG. 1 shows an IC
2 shows an optical communication device with a chip mounted.

As shown in FIG. 1, the optical communication device 15
0 is composed of an IC chip mounting substrate 120 on which an IC chip 140 is mounted and a multilayer printed wiring board 100;
IC chip mounting substrate 120 and multilayer printed wiring board 10
0 is electrically connected via the solder connection portion 141.

The IC chip mounting substrate 120 is a substrate 12
The conductor circuits 124 (124 a, 124 b) and the interlayer resin insulation layer 122 are formed on both surfaces of the substrate 1, and the conductor circuits sandwiching the substrate 121 and the conductor circuits sandwiching the interlayer resin insulation layer 122 are respectively Through hole 129
(129a, 129b) and via hole 127 (1
27a, 127b, 127c, and 127d). Also, the mounting substrate 120 for the IC chip
A solder resist layer 134 having solder bumps is formed on the outermost layer, and the outermost layer on the side facing the multilayer printed wiring board 100 is such that the light receiving section 138a and the light emitting section 139a are exposed. And light receiving element 1
38 and a light emitting element 139.

The multilayer printed wiring board 100 includes a substrate 101
A conductor circuit 104 and an interlayer resin insulation layer 102 are laminated on both surfaces of the substrate, and the conductor circuits sandwiching the substrate 101 and the conductor circuits sandwiching the interlayer resin insulation layer 102 have through holes 109 and via holes, respectively. 107
Are electrically connected to each other. In addition, a solder resist layer 114 having an optical path opening 111 and a solder bump is formed in the outermost layer on the side of the multilayer printed wiring board 100 facing the IC chip mounting substrate 120, and the optical path opening 111 ( 111a, 111b) Optical waveguide 1 provided with optical conversion mirror 119 (119a, 119b) immediately below
18 (118a, 118b) are formed.

In the optical communication device 150 having such a configuration, an optical signal sent from the outside via an optical fiber (not shown) is introduced into the optical waveguide 118a.
After being sent to the light receiving element 138 (light receiving section 138a) via the optical path conversion mirror 119a and the optical path opening 111a,
The light receiving element 138 converts the electric signal into an electric signal.
It is sent to the IC chip 140 via the through hole 129a, the via hole 127b, and the solder connection part 143a.

The electric signal sent from the IC chip 140 is supplied to the solder connection portion 143 b and the via hole 127.
c-through hole 129b-via hole 127d-conductor circuit 124b-light emitting element 13 via conductive layer 142b
9, is converted to an optical signal by the light emitting element 139,
This optical signal is introduced from the light emitting element 139 (light emitting portion 139a) into the optical waveguide 118b via the optical path opening 111b and the optical conversion mirror 119b, and further sent out as an optical signal via an optical fiber (not shown). Will be done.

In the optical communication device according to the present invention, the optical / optical communication is performed within the IC chip mounting substrate, that is, at a position close to the IC chip.
The transmission distance of the electric signal is short because it performs electric signal conversion,
Higher speed communication can be supported. Further, the electric signal sent from the IC chip is converted into an optical signal as described above, and then sent not only to the outside via an optical fiber but also to a multilayer printed wiring board via a solder bump. Then, it is sent to another electronic component such as an IC chip mounted on the multilayer printed wiring board via a conductor circuit (including a via hole and a through hole) of the multilayer printed wiring board.

Next, a method for manufacturing the optical communication device of the present invention will be described. In the optical communication device, for example, after separately manufacturing an IC chip mounting board and a multilayer printed wiring board, the light receiving element and the light emitting element of the IC chip mounting board and the conductor circuit of the multilayer printed wiring board are separated. Both are arranged so as to face each other, and further, the solder bumps are connected to each other while adjusting the positions of both by reflow processing to form a solder connection portion. Therefore, here, first, a method for manufacturing an IC chip mounting substrate and a method for manufacturing a multilayer printed wiring board will be separately described.
After that, a method of connecting both will be described.

First, a method of manufacturing an IC chip mounting substrate will be described. (1) Using an insulating substrate as a starting material, first, a conductor circuit is formed on the insulating substrate. Examples of the insulating substrate include a glass epoxy substrate, a polyester substrate, a polyimide substrate, a bismaleimide-triazine (BT) resin substrate, a thermosetting polyphenylene ether substrate, a copper-clad laminate, and an RCC substrate. Further, a ceramic substrate such as an aluminum nitride substrate or a silicon substrate may be used. The conductor circuit can be formed, for example, by forming a solid conductor layer on the surface of the insulating substrate by electroless plating or the like and then performing an etching process. Further, it may be formed by performing an etching process on a copper-clad laminate or an RCC substrate.

In the case where the connection between the conductor circuits sandwiching the insulating substrate is made by through holes, for example, a through hole is formed in the insulating substrate by using a drill or a laser, and then the electroless plating is performed. Through-holes are formed by performing processing or the like. In addition, the diameter of the said through-hole is 100-300 micrometers normally. When a through hole is formed, it is desirable to fill the through hole with a resin filler.

(2) Next, if necessary, the surface of the conductor circuit is subjected to a roughening process. As the roughening forming process,
For example, a blackening (oxidation) -reduction treatment, an etching treatment using an etching solution containing a cupric complex and an organic acid salt, and the like;
A treatment by u-Ni-P needle-like alloy plating can be exemplified. Here, when the roughened surface is formed, the average roughness of the roughened surface is usually desirably 0.1 to 5 μm, and the adhesion between the conductive circuit and the interlayer resin insulating layer, the electric signal transmission performance of the conductive circuit The thickness is more preferably 2 to 4 μm in consideration of the effect on The roughening process may be performed before filling the through-hole with the resin filler, and a roughened surface may be formed on the wall surface of the through-hole. This is because the adhesion between the through hole and the resin filler is improved.

(3) Next, a thermosetting resin, a photosensitive resin, a resin in which a part of the thermosetting resin is acrylated, or a resin containing these and a thermoplastic resin is formed on the substrate on which the conductive circuit is formed. An uncured resin layer made of a composite is formed, or a resin layer made of a thermoplastic resin is formed. The uncured resin layer can be formed by applying the uncured resin with a roll coater, a curtain coater, or the like, or by thermocompression bonding an uncured (semi-cured) resin film. Further, the resin layer made of the thermoplastic resin,
It can be formed by thermocompression bonding a resin molded body molded on a film.

Of these, the method of thermocompression bonding of an uncured (semi-cured) resin film is desirable, and the compression of the resin film can be performed using, for example, a vacuum laminator. The pressure-bonding conditions are not particularly limited, and may be appropriately selected in consideration of the composition of the resin film and the like. Usually, the pressure is 0.25 to 1.0 MPa, the temperature is 40 to 70 ° C,
It is desirable to perform the process under the conditions of a degree of vacuum of 13 to 1300 Pa and a time of about 10 to 120 seconds.

Examples of the thermosetting resin include an epoxy resin, a phenol resin, a polyimide resin, a polyester resin, a bismaleimide resin, a polyolefin resin, a polyphenylene ether resin, a polyphenylene resin, and a fluororesin. Specific examples of the epoxy resin, for example, phenol novolak type, novolak type epoxy resin such as cresol novolak type,
An alicyclic epoxy resin modified with dicyclopentadiene is exemplified.

The photosensitive resin includes, for example, an acrylic resin. Examples of the resin obtained by partially acrylifying the thermosetting resin include those obtained by subjecting the thermosetting group of the thermosetting resin to methacrylic acid or acrylic acid to undergo an acrylation reaction.

Examples of the thermoplastic resin include phenoxy resin, polyether sulfone (PES), polysulfone (PSF), and polyphenylene sulfone (P
PS) polyphenylene sulfide (PPES), polyphenylene ether (PPE) polyetherimide (P
I) and the like.

The resin composite is not particularly limited as long as it contains a thermosetting resin or a photosensitive resin (including a resin obtained by partially acrylizing the thermosetting resin) and a thermoplastic resin. Examples of specific combinations of a thermosetting resin and a thermoplastic resin include, for example, phenol resin / polyethersulfone, polyimide resin / polysulfone,
Epoxy resin / polyether sulfone, epoxy resin / phenoxy resin, and the like. Specific combinations of the photosensitive resin and the thermoplastic resin include, for example, an acrylic resin / phenoxy resin, an epoxy resin in which a part of an epoxy group is acrylated, and polyether sulfone.

The mixing ratio of the thermosetting resin or the photosensitive resin to the thermoplastic resin in the resin composite is as follows: thermosetting resin or photosensitive resin / thermoplastic resin = 95/5 to 5
0/50 is desirable. This is because a high toughness value can be secured without impairing the heat resistance.

Further, the resin layer may be composed of two or more different resin layers. Specifically, for example,
Lower layer is thermosetting resin or photosensitive resin / thermoplastic resin =
For example, the upper layer is formed of a thermosetting resin or a photosensitive resin / thermoplastic resin = 90/10 resin composite, and the like. With such a configuration, excellent adhesion to the insulating substrate can be ensured, and ease of formation in forming a via hole opening or the like in a later step can be ensured.

The resin layer may be formed by using a resin composition for forming a roughened surface. The resin composition for forming a roughened surface includes, for example, an acid, an alkali, and the like in an uncured heat-resistant resin matrix that is hardly soluble in a roughening liquid composed of at least one selected from acids, alkalis, and oxidizing agents. And a substance that is soluble in a roughened liquid comprising at least one selected from oxidants. Note that the terms "sparingly soluble" and "soluble" are referred to as "soluble" for convenience when a substance having a relatively high dissolution rate is immersed in the same roughening solution for the same time, and the relative dissolution rate is relatively low. The slower one is called "poorly soluble" for convenience.

The heat resistant resin matrix is preferably a matrix capable of maintaining the shape of the roughened surface when the roughened surface is formed on the interlayer resin insulating layer using the roughening solution. Curable resins, thermoplastic resins, and composites thereof are exemplified. Further, by using a photosensitive resin, an opening for a via hole may be formed in the interlayer resin insulating layer by using exposure and development processes.

The thermosetting resin includes, for example, epoxy resin, phenol resin, polyimide resin, polyolefin resin, fluororesin and the like. When the thermosetting resin is photosensitized, the thermosetting group is subjected to a (meth) acrylation reaction using methacrylic acid, acrylic acid, or the like.

Examples of the epoxy resin include cresol novolak type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolak type epoxy resin, alkylphenol novolak type epoxy resin, biphenol F type epoxy resin, and naphthalene type epoxy resin. Resin, dicyclopentadiene type epoxy resin, epoxidized product of condensate of phenols and aromatic aldehyde having phenolic hydroxyl group,
Triglycidyl isocyanurate, alicyclic epoxy resin and the like. These may be used alone or in combination of two or more. Thereby, it becomes excellent in heat resistance and the like.

Examples of the thermoplastic resin include phenoxy resin, polyether sulfone, polysulfone, polyphenylene sulfone, polyphenylene sulfide, polyphenyl ether, polyether imide and the like. These may be used alone or in combination of two or more.

The substance soluble in the roughening solution comprising at least one selected from the above-mentioned acids, alkalis and oxidizing agents is preferably at least one selected from inorganic particles, resin particles and metal particles.

Examples of the inorganic particles include aluminum compounds, calcium compounds, potassium compounds, magnesium compounds, and silicon compounds. These may be used alone or in combination of two or more.

Examples of the aluminum compound include alumina and aluminum hydroxide. Examples of the calcium compound include calcium carbonate and
Calcium hydroxide and the like, as the potassium compound, for example, potassium carbonate and the like, as the magnesium compound, for example, magnesia, dolomite, basic magnesium carbonate, talc and the like,
Examples of the silicon compound include silica and zeolite. These may be used alone or 2
More than one species may be used in combination.

The alumina particles can be dissolved and removed with hydrofluoric acid, and calcium carbonate can be dissolved and removed with hydrochloric acid. Further, sodium-containing silica and dolomite can be dissolved and removed with an alkaline aqueous solution.

Examples of the resin particles include those made of a thermosetting resin, a thermoplastic resin and the like. When immersed in a roughening liquid comprising at least one selected from acids, alkalis and oxidizing agents, There is no particular limitation as long as the dissolution rate is faster than the heat-resistant resin matrix,
Specifically, for example, amino resin (melamine resin, urea resin, guanamine resin, etc.), epoxy resin, phenol resin, phenoxy resin, polyimide resin, polyphenylene resin, polyolefin resin, fluororesin, bismaleimide-triazine resin and the like can be mentioned. . These may be used alone or in combination of two or more. It is necessary that the resin particles have been previously cured. If not cured, the resin particles will be dissolved in a solvent that dissolves the resin matrix.

Further, as the resin particles, rubber particles, liquid phase resin, liquid phase rubber and the like may be used. As the rubber particles, for example, acrylonitrile-butadiene rubber,
Examples include polychloroprene rubber, polyisoprene rubber, acrylic rubber, polysulfur-based rigid rubber, fluorine rubber, urethane rubber, silicone rubber, and ABS resin. Further, for example, various modified polybutadiene rubbers such as polybutadiene rubber, epoxy-modified, urethane-modified, (meth) acrylonitrile-modified, and (meth) acrylonitrile-butadiene rubber containing a carboxyl group may be used.

As the liquid phase resin, an uncured solution of the thermosetting resin can be used. Specific examples of such a liquid phase resin include, for example, an uncured epoxy oligomer and an amine curing agent. And the like. Examples of the liquid phase rubber include the above-mentioned polybutadiene rubber, various modified polybutadiene rubbers such as epoxy-modified, urethane-modified, (meth) acrylonitrile-modified, and uncured solutions such as (meth) acrylonitrile-butadiene rubber containing a carboxyl group. Can be used.

When the photosensitive resin composition is prepared using the liquid resin or the liquid rubber, the heat-resistant resin matrix and the soluble substance are not uniformly compatible (that is, the phases are separated). As such, these materials need to be selected. By mixing a heat-resistant resin matrix and a soluble substance selected according to the above criteria, a state in which "islands" of liquid-phase resin or liquid-phase rubber are dispersed in the "sea" of the heat-resistant resin matrix Alternatively, a photosensitive resin composition in which "islands" of a heat-resistant resin matrix are dispersed in a "sea" of a liquid phase resin or a liquid phase rubber can be prepared. Then, after the photosensitive resin composition in such a state is cured, the roughened surface can be formed by removing the liquid phase resin or liquid phase rubber of "sea" or "island".

Examples of the metal particles include gold, silver,
Examples include copper, tin, zinc, stainless steel, aluminum, nickel, iron, lead, and the like. These may be used alone or in combination of two or more. The metal particles may have a surface layer coated with a resin or the like in order to ensure insulation.

When two or more of the above-mentioned soluble substances are used in combination, the combination of the two soluble substances to be mixed is preferably a combination of resin particles and inorganic particles. Both have low conductivity, so that the insulation of the interlayer resin insulation layer can be ensured, the thermal expansion can be easily adjusted with the poorly soluble resin, and the interlayer resin made of the resin composition for forming a roughened surface can be easily obtained. This is because no crack occurs in the insulating layer, and no peeling occurs between the interlayer resin insulating layer and the conductor circuit.

Examples of the acid used as the roughening solution include phosphoric acid, hydrochloric acid, sulfuric acid, nitric acid, and organic acids such as formic acid and acetic acid. Among these, it is preferable to use an organic acid. This is because when the roughening treatment is performed, the metal conductor layer exposed from the via hole is hardly corroded. As the oxidizing agent, it is desirable to use, for example, an aqueous solution of chromic acid, chromic sulfuric acid, or an alkaline permanganate (such as potassium permanganate). As the alkali, an aqueous solution of sodium hydroxide, potassium hydroxide or the like is desirable.

The average particle size of the soluble substance is 10 μm
The following is desirable. Further, coarse particles having a relatively large average particle diameter of 2 μm or less and fine particles having a relatively small average particle diameter may be used in combination. That is, a soluble substance having an average particle size of 0.1 to 0.5 μm and an average particle size of 1
Combination with a soluble substance of ２2 μm, and the like.

As described above, the combination of the coarse particles having a relatively large average particle size and the fine particles having a relatively small average particle size eliminates the dissolution residue of the electroless plating film and reduces the amount of the palladium catalyst under the plating resist. In addition, a shallow and complicated roughened surface can be formed. Further, by forming a complicated roughened surface, a practical peel strength can be maintained even if the unevenness of the roughened surface is small. The coarse particles have an average particle size of more than 0.8 μm and 2.0 μm.
m, the fine particles have an average particle size of 0.1 to 0.8 μm
It is desirable that

(4) Next, when forming an interlayer resin insulating layer using a thermosetting resin or a resin composite as the material, an uncured resin insulating layer is subjected to a curing treatment and a via hole is formed. An opening is formed to form an interlayer resin insulation layer. In this step, a through-hole may be formed as necessary. The via hole opening is desirably formed by laser processing. When a photosensitive resin is used as the material of the interlayer resin insulating layer, the photosensitive resin may be formed by exposure and development.

When forming an interlayer resin insulating layer using a thermoplastic resin as the material, an opening for a via hole is formed in a resin layer made of the thermoplastic resin to form an interlayer resin insulating layer. In this case, the via hole opening can be formed by performing laser processing. Also,
When a through hole is formed in this step, the through hole may be formed by drilling, laser processing, or the like.

Examples of the laser used for the laser processing include a carbon dioxide gas laser, an ultraviolet laser, and an excimer laser. Of these, excimer lasers and short-pulse carbon dioxide lasers are desirable.

It is desirable to use a hologram type excimer laser among the excimer lasers. The hologram method is a method of irradiating a laser beam to a target object through a hologram, a condensing lens, a laser mask, a transfer lens, and the like. Can be formed efficiently.

When a carbon dioxide laser is used, the pulse interval is desirably 10 ⁻⁴ to 10 ⁻⁸ seconds. The time for irradiating the laser for forming the opening is preferably 10 to 500 μsec. Further, by irradiating a laser beam through an optical lens and a mask, a large number of via hole openings can be formed at once. This is because a plurality of portions can be irradiated with laser light having the same intensity and the same irradiation intensity through the optical lens and the mask. After forming the via hole openings in this manner, desmearing may be performed as necessary.

(5) Next, a conductor circuit is formed on the surface of the interlayer resin insulating layer including the inner wall of the via hole opening. In forming a conductive circuit, first, a thin-film conductive layer is formed on the surface of the interlayer resin insulating layer. The thin film conductor layer can be formed by a method such as electroless plating and sputtering.

As the material of the thin film conductor layer, for example,
Examples include copper, nickel, tin, zinc, cobalt, thallium, lead and the like. Among these, those made of copper, copper and nickel are desirable from the viewpoint of excellent electrical characteristics, economic efficiency and the like. When the thin film conductor layer is formed by electroless plating, the thickness of the thin film conductor layer is 0.3 to
2.0 μm is desirable, and 0.6 to 1.2 μm is more desirable. Also, when formed by sputtering,
0.1 to 1.0 μm is desirable.

Before forming the thin film conductor layer, a roughened surface may be formed on the surface of the interlayer resin insulating layer.
By forming the roughened surface, the adhesion between the interlayer resin insulating layer and the thin film conductor layer can be improved. In particular, when the interlayer resin insulating layer is formed using the roughened surface forming resin composition, it is desirable to form the roughened surface using an acid, an oxidizing agent, or the like.

In the case where the through hole is formed in the step (4), when the thin film conductor layer is formed on the interlayer resin insulating layer, the thin film conductor layer is also formed on the wall surface of the through hole. It may be a through hole.

(6) Next, a plating resist is formed on the substrate having the thin film conductor layer formed on the surface thereof. The plating resist can be formed, for example, by adhering a photosensitive dry film, placing a photomask composed of a glass substrate or the like on which a plating resist pattern is drawn, in close contact, and performing exposure and development processing.

(7) Thereafter, electroplating is performed using the thin film conductor layer as a plating lead, and an electroplating layer is formed on the portion where the plating resist is not formed. As the electroplating,
Copper plating is preferred. Further, the thickness of the electroplating layer,
5 to 20 μm is desirable.

Thereafter, by removing the plating resist and the electroless plating film and the thin film conductor layer under the plating resist, a conductor circuit (including a via hole) can be formed. The removal of the plating resist may be performed using, for example, an alkaline aqueous solution, and the removal of the thin film conductor layer may be performed using a mixed solution of sulfuric acid and hydrogen peroxide, sodium persulfate, ammonium persulfate, ferric chloride, and chloride. It may be performed using an etching solution such as cupric copper. After the formation of the conductor circuit, the catalyst on the interlayer resin insulating layer may be removed using an acid or an oxidizing agent, if necessary. This is because a decrease in electrical characteristics can be prevented. After forming the plating resist, instead of the method of forming an electroplating layer (steps (6) and (7)), an etching process is performed after the electroplating layer is formed on the entire surface of the thin film conductor layer. The conductor circuit may be formed using a method.

When a through hole is formed in the steps (4) and (5), a resin filler may be filled in the through hole. When a resin filler is filled in the through hole, a cover plating layer covering the surface layer of the resin filler layer may be formed by performing electroless plating, if necessary.

(8) Next, when a cover plating layer is formed, the surface of the cover plating layer is subjected to a roughening treatment, if necessary, and further, if necessary, (3) to (7). By repeating the step of (1), an interlayer resin insulating layer and a conductive circuit are laminated on both surfaces thereof. In this step, a through hole may or may not be formed.

(9) Next, a solder resist layer is formed on the outermost layer of the substrate on which the conductor circuit and the interlayer resin insulating layer have been formed. The solder resist layer can be formed using, for example, a solder resist composition comprising a polyphenylene ether resin, a polyolefin resin, a fluororesin, a thermoplastic elastomer, an epoxy resin, a polyimide resin, or the like.

Examples of the solder resist composition other than those described above include, for example, (meth) acrylate of novolak type epoxy resin, imidazole curing agent, bifunctional (meth) acrylate monomer, and molecular weight of 500 to 50.
A paste-like fluid containing a polymer of about 00 (meth) acrylate, a thermosetting resin such as a bisphenol-type epoxy resin, a photosensitive monomer such as a polyvalent acrylic monomer, a glycol ether-based solvent, and the like. It is desirable that the viscosity is adjusted to 1 to 10 Pa · s at 25 ° C.

(10) Next, an opening for forming a solder bump and an opening for mounting an optical element are formed in the solder resist layer. The opening for forming the solder bump can be formed by the same method as the method for forming the opening for the via hole, that is, by using exposure and development processing or laser processing. Also,
When forming the solder resist layer, a resin film having an opening at a desired position is prepared in advance, and the resin film is attached to form a solder resist layer having an opening for forming a solder bump and an opening for mounting an optical element. May be formed.

(11) Next, the conductor circuit portion exposed by forming the above-mentioned opening for forming a solder bump is covered with a corrosion-resistant metal such as nickel, palladium, gold, silver, platinum or the like, if necessary. Pad. Among these, it is desirable to form the coating layer with a metal such as nickel-gold, nickel-silver, nickel-palladium, and nickel-palladium-gold. The coating layer can be formed, for example, by plating, vapor deposition, electrodeposition, or the like. Among these, it is preferable to form the coating layer by plating because of excellent uniformity of the coating layer. In this step, it is desirable to form a covering layer also on the conductor circuit portion exposed by forming the optical element mounting opening.

(12) Next, the solder pad is filled with a solder paste through a mask having an opening at a portion corresponding to the solder pad, and then reflowed to form a solder bump.

(13) Further, optical elements (light receiving elements and light emitting elements) are mounted on the solder resist layer. The optical element is mounted by, for example, filling the optical element mounting opening with a solder paste in the above step (12) and further attaching the optical element when performing reflow to form a solder (conductive layer). What is necessary is just to implement via. Further, the optical element may be mounted using a conductive adhesive or the like instead of the solder paste. When these methods are used, the light receiving element and the light emitting element are mounted on the surface of the solder resist layer.

Instead of the surface mounting method described above, when forming the optical element mounting opening in the step (10), the opening is formed in a size capable of accommodating the optical element. The mounting may be performed by housing the optical element in the opening via a conductive adhesive. In this case, the light receiving element and the light emitting element are built in the solder resist layer. Through these steps, an IC chip mounting substrate constituting the optical communication device of the present invention can be manufactured.

Next, a method for manufacturing a multilayer printed wiring board will be described. (1) First, the same steps as (1) to (8) of the method of manufacturing a substrate for mounting an IC chip are performed to manufacture a substrate in which a conductor circuit and an interlayer resin insulating layer are repeatedly formed on both surfaces. Note that, also in this step, through holes are appropriately formed.

(2) Next, an optical waveguide is formed on the portion of the interlayer resin insulating layer on the side facing the IC chip mounting substrate where no conductive circuit is formed. When the optical waveguide is formed using an inorganic material such as quartz glass as the material, the optical waveguide can be formed by attaching an optical waveguide formed in a predetermined shape in advance via an adhesive. The optical waveguide made of the inorganic material is, for example, LiNbO ₃ , LiTaO
It can be formed by forming a film of an inorganic material such as ₃ by a liquid phase epitaxy method, a chemical deposition method (CVD), a molecular beam epitaxy method, or the like.

When the optical waveguide is formed using a polymer material, an optical waveguide forming film previously formed into a film on a substrate or a release film may be attached to the interlayer resin insulating layer. The optical waveguide can be formed by forming the optical waveguide directly on the interlayer resin insulating layer.
Specifically, it can be formed by using a selective polymerization method, a method using reactive ion etching and photolithography, a direct exposure method, a method using injection molding, a photobleaching method, a method combining these, and the like. . In addition, these methods can be used when the optical waveguide is formed on a substrate or a release film, or when it is formed directly on an interlayer resin insulating layer.

An optical path conversion mirror is formed in the optical waveguide. The optical path conversion mirror may be formed before mounting on the interlayer resin insulating layer, or may be formed after mounting on the interlayer resin insulating layer, but the optical waveguide is directly formed on the interlayer resin insulating layer. Except for the case where it is formed, it is desirable to form an optical path conversion mirror in advance. The work can be performed easily, and there is no risk of damaging or damaging other members constituting the multilayer printed wiring board during the work, for example, a conductor circuit or an interlayer resin insulation layer. It is.

The method for forming the optical path conversion mirror is not particularly limited, and a conventionally known forming method can be used. Specifically, machining with a diamond saw having a V-shaped tip of 90 ° or a blade, machining with reactive ion etching, laser ablation, or the like can be used.

(3) Next, a solder resist layer is formed on the outermost layer of the substrate on which the optical waveguide has been formed. The solder resist layer can be formed, for example, using the same resin composition as that used when forming the solder resist layer of the IC chip mounting substrate.

(4) Next, an opening for forming a solder bump and an opening for an optical path are formed in the solder resist layer on the side facing the IC chip mounting substrate. The formation of the opening for forming the solder bump and the opening for the optical path can be performed by the same method as the method for forming the opening for forming the solder bump on the IC chip mounting substrate, that is, by using exposure and development processing, laser processing, or the like. it can.
The formation of the openings for forming the solder bumps and the formation of the openings for the optical path may be performed simultaneously or separately.

Of these, when forming a solder resist layer, a resin composition containing a photosensitive resin is applied as a material for the solder resist layer, and an exposure and development process is performed to form a solder bump forming opening and an optical path opening. It is desirable to select the method of formation. This is because, when the opening for the optical path is formed by the exposure and development processing, there is no possibility that the optical waveguide existing under the opening for the optical path is damaged when the opening is formed. Further, when forming the solder resist layer, a resin film having an opening at a desired position is prepared in advance, and the resin film is adhered to form a solder resist layer having an opening for forming a solder bump and an opening for an optical path. May be formed.

If necessary, an opening for forming a solder bump may be formed in the solder resist layer on the side opposite to the surface facing the IC chip mounting substrate. This is because external connection terminals can be formed on the solder resist layer on the side opposite to the surface facing the IC chip mounting substrate by performing the post-process.

(5) Next, the conductor circuit portion exposed by forming the above-mentioned opening for forming a solder bump is covered with a corrosion-resistant metal such as nickel, palladium, gold, silver or platinum as required. Pad. Specifically, I
What is necessary is just to carry out using the same method as the method of forming a solder pad on a C-chip mounting substrate.

(6) Next, the solder pads are filled with a solder paste through a mask having openings formed in portions corresponding to the solder pads, and then reflowed to form solder bumps. In the solder resist layer on the side opposite to the surface facing the IC chip mounting substrate, pins are arranged on the external substrate connection surface, or solder balls are formed, thereby forming a PGA (Pin Grid Array) or the like. BG
A (Ball Grid Array) may be used. Through these steps, a multilayer printed wiring board constituting the optical communication device of the present invention can be manufactured.

Next, a method of manufacturing an optical communication device using the IC chip mounting substrate and the multilayer printed wiring board manufactured by the above-described method will be described. First, I
A solder connection portion is formed by the solder bump of the C chip mounting substrate and the solder bump of the multilayer printed wiring board, and the two are electrically connected. That is, the IC chip mounting board and the multilayer printed wiring board are respectively disposed at predetermined positions in a predetermined direction so as to face each other, and are connected by reflow.

In this step, since the IC chip mounting board and the multilayer printed wiring board are connected to each other by using the solder bumps, there is a slight misalignment between the two when they are opposed to each other. However, both can be arranged at predetermined positions by the self-alignment effect of the solder during reflow.

Next, an IC chip is mounted on the IC chip mounting substrate, and thereafter, if necessary, is sealed with a resin to obtain an optical communication device. The mounting of the IC chip can be performed by a conventionally known method. Also, IC
The chip is mounted before connecting the IC chip mounting board and the multilayer printed wiring board, and the IC chip mounted with the IC chip is mounted.
An optical communication device may be obtained by connecting a C-chip mounting substrate and a multilayer printed wiring board.

[0093]

The present invention will be described in more detail below. Example 1 A. Production of IC chip mounting substrate A-1. Preparation of Resin Film for Interlayer Resin Insulation Layer Bisphenol A type epoxy resin (Epoxy equivalent 46
9. Yuka Shell Epoxy Epicoat 1001) 30
Parts by weight, 40 parts by weight of a cresol novolak type epoxy resin (epoxy equivalent: 215, Epicron N-673 manufactured by Dainippon Ink and Chemicals, Inc.) Light KA-705
2) 30 parts by weight were dissolved by heating in 20 parts by weight of ethyl diglycol acetate and 20 parts by weight of solvent naphtha while stirring, and epoxidized polybutadiene rubber (Denalex R-45EPT manufactured by Nagase Kasei Kogyo Co., Ltd.) was added thereto.
15 parts by weight, 1.5 parts by weight of a crushed product of 2-phenyl-4,5-bis (hydroxymethyl) imidazole, 2 parts by weight of finely divided silica, and 0.5 part by weight of a silicon-based antifoaming agent are added, and an epoxy resin composition is added. Was prepared. The resulting epoxy resin composition is applied on a 38 μm-thick PET film using a roll coater so that the thickness after drying becomes 50 μm, and then dried at 80 to 120 ° C. for 10 minutes to form an interlayer resin. A resin film for an insulating layer was produced.

A-2. Preparation of Resin Composition for Filling Through Holes 100 parts by weight of a bisphenol F type epoxy monomer (manufactured by Yuka Shell Co., Ltd., molecular weight: 310, YL983U), the average particle size of which surface is coated with a silane coupling agent is 1.6 μm, S whose maximum particle diameter is 15 μm or less
iO ₂ spherical particles (CRS 1101- manufactured by Adtech Co., Ltd.)
CE) 170 parts by weight and 1.5 parts by weight of a leveling agent (Perenol S4 manufactured by San Nopco Co.) are placed in a container, and the mixture is stirred and mixed to have a viscosity of 45-4 at 23 ± 1 ° C.
A 9 Pa · s resin filler was prepared. In addition, as a curing agent, an imidazole curing agent (2E4MZ- manufactured by Shikoku Chemicals Co., Ltd.)
6.5 parts by weight (CN).

A-3. Manufacture of IC chip mounting substrate (1) 0.8 mm thick glass epoxy resin or BT
A copper clad laminate in which an 18 μm copper foil 28 was laminated on both surfaces of an insulating substrate 21 made of (bismaleimide triazine) resin was used as a starting material (see FIG. 2A). First, the copper clad laminate was drilled, subjected to an electroless plating treatment, and etched in a pattern to form conductor circuits 24 and through holes 29 on both surfaces of the substrate 21.

(2) The substrate on which the through holes 29 and the conductor circuits 24 are formed is washed with water and dried, and then the NaOH (1
0 g / l), NaClO ₂ (40 g / l), Na ₃ PO
₄ A blackening treatment using an aqueous solution containing (6 g / l) as a blackening bath (oxidizing bath), NaOH (10 g / l), NaBH
₄ A reduction treatment was performed using an aqueous solution containing (6 g / l) as a reducing bath to form roughened surfaces 24a and 29a on the surface of the conductor circuit 24 including the through holes 29 (see FIG. 2B).

(3) After preparing the resin filler described in the above A-2, within 24 hours after preparation by the following method,
A layer of a resin filler 30 ′ was formed in the through-hole 29, on a portion of the substrate 21 where no conductor circuit was formed, and on the outer edge of the conductor circuit 24. That is, first, the resin filler is pushed into the through hole using a squeegee,
It was dried under the condition of 0 minutes. Next, a mask having an opening corresponding to the conductive circuit non-forming portion is placed on the substrate, and the resin filling material is also filled in the conductive circuit non-forming portion which is a concave portion using a squeegee. By drying under the condition of 20 minutes, a layer of the resin filler 30 'was formed (FIG. 2).
(C)).

(4) One surface of the substrate after the treatment of the above (3) is subjected to belt sander polishing using # 600 belt polishing paper (manufactured by Sankyo Rikagaku Co., Ltd.) to form the surface of the conductor circuit 24 and the through holes 29. Polishing was performed so that the resin filler 30 'did not remain on the land surface, and then buffing was performed to remove the scratches caused by the belt sander polishing. Such a series of polishing was similarly performed on the other surface of the substrate. Then, at 100 ° C for 1 hour, at 120 ° C for 3 hours,
Heat treatment was performed at 50 ° C. for 1 hour and at 180 ° C. for 7 hours to form the resin filler layer 30.

In this way, the surface layer of the resin filler 30 and the surface of the conductor circuit 24 formed in the through hole 29 and the portion where the conductor circuit is not formed are flattened, and the resin filler 30 and the side surface 24a of the conductor circuit 24 are formed. Was firmly adhered through the roughened surface, and an insulating substrate in which the inner wall surface 29a of the through hole 29 and the resin filler 30 were firmly adhered through the roughened surface was obtained (FIG. 2D). reference). By this step, the surface of the resin filler layer 30 and the surface of the conductor circuit 24 become flush with each other.

(5) After the above substrate was washed with water and acid degreased,
The surface of the conductor circuit 24, the land surface of the through hole 29, and the inner wall are etched by spraying an etching solution onto both surfaces of the substrate by spraying, so that the entire surface of the conductor circuit 24 is roughened. , 29
a was formed (see FIG. 3A). As an etching solution, an etching solution (Mec etch bond, manufactured by Mec Co.) containing 10 parts by weight of imidazole copper (II) complex, 7 parts by weight of glycolic acid, and 5 parts by weight of potassium chloride was used.

(6) Next, a resin film for an interlayer resin insulating layer slightly larger than the substrate prepared in the above A-1 was placed on the substrate, and the pressure was 0.4 MPa, the temperature was 80 ° C., and the pressing time was 1
After pre-pressing and cutting under the condition of 0 second, the film was further bonded by using a vacuum laminator by the following method to form an interlayer resin insulating layer 22 (see FIG. 3B). That is, a resin film for an interlayer resin insulation layer is placed on a substrate, with a degree of vacuum of 65 Pa, a pressure of 0.4 MPa, a temperature of 80,
The final pressure bonding is performed for 60 seconds,
Heat cured for minutes.

(7) Next, through a mask in which a through hole having a thickness of 1.2 mm is formed on the interlayer resin insulating layer 22, a CO ₂ gas laser having a wavelength of 10.4 μm is used.
Under the conditions of 0 mm, top hat mode, pulse width of 8.0 μsec, through-hole diameter of the mask of 1.0 mm, and one shot, a via hole opening 26 having a diameter of 80 μm was formed in the interlayer resin insulating layer 22 (FIG. c)).

(8) The substrate on which the via hole opening 26 is formed is immersed in a solution containing 60 g / l of permanganic acid at 80 ° C. for 10 minutes to remove the epoxy resin particles present on the surface of the interlayer resin insulating layer 22. By dissolving and removing, a roughened surface was formed on the surface including the inner wall surface of the via hole opening 26 (see FIG. 3D).

(9) Next, the substrate after the above treatment was immersed in a neutralizing solution (manufactured by Shipley) and washed with water. Further, by applying a palladium catalyst to the surface of the substrate subjected to the surface roughening treatment (roughening depth: 3 μm), catalyst nuclei are added to the surface of the interlayer resin insulating layer 22 (including the inner wall surface of the via hole opening 26). (Not shown). That is, palladium chloride (PdCl ₂ ) and stannous chloride (S
nCl ₂ ) to deposit a palladium metal to provide a catalyst.

(10) Next, the substrate is immersed in an electroless copper plating aqueous solution having the following composition, and the surface of the interlayer resin insulating layer 22 (including the inner wall surface of the via hole opening 26) and the through hole An electroless copper plating film 32 having a thickness of 0.6 to 3.0 μm was formed on the wall surface of the substrate 29 (see FIG. 4A).

[Electroless plating aqueous solution] NiSO ₄ 0.003 mol / l tartaric acid 0.200 mol / l copper sulfate 0.030 mol / l HCHO 0.050 mol / l NaOH 0.100 mol / l α, α ' -Bipyridyl 100 mg / l Polyethylene glycol (PEG) 0.10 g / l [Electroless plating conditions] 40 minutes at a liquid temperature of 30 ° C

(11) Next, a commercially available photosensitive dry film is attached to the substrate on which the electroless copper plating film 32 has been formed, a mask is placed, and exposure is performed at 100 mJ / cm ² .
By performing development processing with a 0.8% aqueous sodium carbonate solution, a plating resist 23 having a thickness of 20 μm was provided (FIG. 4).
(B)).

(12) Next, the substrate was washed with water at 50 ° C., degreased, washed with water at 25 ° C., further washed with sulfuric acid, and then subjected to electrolytic plating under the following conditions. In the forming part, a 20 μm thick electrolytic copper plating film 33
Was formed (see FIG. 4C).

[Electrolytic plating solution] Sulfuric acid 2.24 mol / l Copper sulfate 0.26 mol / l Additive 19.5 ml / l (Atotech Japan, Capparaside GL) [Electroplating conditions] Current density 1 A / dm ² hours 65 minutes Temperature 22 ± 2 ℃

(13) Further, the plating resist 23 is
% NaOH, the plating resist 23
The lower electroless plating film is dissolved and removed by etching with a mixed solution of sulfuric acid and hydrogen peroxide, and a 18 μm thick conductor circuit 25 (via hole) composed of an electroless copper plating film 32 and an electrolytic copper plating film 33 is formed. 27 (see FIG. 4).
(D)). Further, the same etchant (mech etch bond) as the etchant used in the above step (5).
, A roughened surface was formed on the surface of the conductor circuit 25 (including the via hole 27).

(14) Next, a cresol novolak-type epoxy resin (manufactured by Nippon Kayaku Co., Ltd.) dissolved in diethylene glycol dimethyl ether (DMDG) so as to have a concentration of 60% by weight was used. Oligomer for imparting properties (molecular weight: 4000) 46.6
7 parts by weight, 80% by weight dissolved in methyl ethyl ketone
Of bisphenol A type epoxy resin (manufactured by Yuka Shell Co., Ltd.
Trade name: Epicoat 1001) 15.0 parts by weight, imidazole hardener (manufactured by Shikoku Chemicals, trade name: 2E4MZ-C)
N) 1.6 parts by weight, a bifunctional acrylic monomer which is a photosensitive monomer (trade name: R604, manufactured by Nippon Kayaku Co., Ltd.) 4.5
Parts by weight, also polyvalent acrylic monomer (manufactured by Kyoei Chemical Co.,
A trade name: 1.5 parts by weight of DPE6A) and 0.71 parts by weight of a dispersion defoaming agent (manufactured by San Nopco, S-65) are placed in a container, stirred and mixed to prepare a mixed composition, and the mixed composition is prepared. Of benzophenone (manufactured by Kanto Chemical Co., Ltd.) as a photopolymerization initiator and 0.2 part by weight of Michler's ketone (manufactured by Kanto Chemical Co., Ltd.) as a photosensitizer at 25 ° C. A solder resist composition adjusted to 2.0 Pa · s was obtained. The viscosity was measured using a B-type viscometer (DVL-B type, manufactured by Tokyo Keiki Co., Ltd.) for 60 min ^-1 (rpm).
m), the rotor No. 4.6 min ^-1 (rpm)
In the case of the rotor No. According to 3.

(15) Next, the solder resist composition is applied in a thickness of 30 μm on both surfaces of the substrate on which the interlayer resin insulating layer 22 and the conductor circuit 25 (including the via hole 27) are formed, and For 20 minutes and at 70 ° C. for 30 minutes to form a layer 34 ′ of the solder resist composition.
Was formed (see FIG. 5A).

(16) Next, a 5 mm-thick photomask on which a pattern of the openings for forming the solder bumps and the openings for the optical elements (light receiving elements and light emitting elements) is drawn is brought into close contact with the solder resist layer so as to have a thickness of 1000 mJ / cm ² . It was exposed to ultraviolet light and developed with a DMTG solution to form an opening having a diameter of 200 μm. Then, at 80 ° C. for 1 hour,
Heat treatment is performed at 00 ° C. for 1 hour, at 120 ° C. for 1 hour, and at 150 ° C. for 3 hours to cure the solder resist layer, and has a solder bump forming opening 35 and an optical element opening 31; A solder resist layer 34 having a thickness of 20 μm was formed (see FIG. 5B). In addition, a commercially available solder resist composition can also be used as the solder resist composition.

(17) Next, the substrate on which the solder resist layer 34 is formed is coated with nickel chloride (2.3 × 10 ^-1 mol).
/ L), sodium hypophosphite (2.8 × 10 ^-1 mol)
/ L), sodium citrate (1.6 × 10 ^-1 mol /
2) in the electroless nickel plating solution having pH = 4.5 containing l)
By immersing for 0 minutes, a nickel plating layer having a thickness of 5 μm was formed in the openings 35 for forming solder bumps and the openings 31 for optical elements. Further, the substrate was placed on potassium potassium cyanide (7.6 ×
10 ⁻³ mol / l), ammonium chloride (1.9 × 10
^-1 mol / l), sodium citrate (1.2 × 10 ^-1
mol / l), sodium hypophosphite (1.7 × 10 ⁻¹⁾
(mol / l) and immersed in an electroless gold plating solution containing 80 mol / l for 7.5 minutes at a temperature of 80 ° C. to form a film having a thickness of 0.1 mm on the nickel plating layer.
A gold plating layer having a thickness of 03 μm was formed to form a solder pad 36.

(18) Next, the opening 35 for forming the solder bump and the opening 3 for the optical element formed in the solder resist layer 34
1 is printed with a solder paste.
Attach the light receiving element 38 and the light emitting element 39 to the solder paste printed thereon while aligning the light receiving section 38a and the light emitting section 39a of the light receiving element 38, and reflow at 200 ° C. to mount the light receiving element 38 and the light emitting element 39. Then, the solder bumps 37 were formed in the solder bump formation openings 35 to obtain an IC chip mounting substrate. The light-receiving element 38 was made of InGaAs, and the light-emitting element 39 was made of InGaAsP (see FIG. 5C).

B. Production of multilayer printed wiring board B-1. Production of Resin Film for Interlayer Resin Insulation Layer A resin film for interlayer resin insulation layer was produced using the same method as that used in A-1. B-2. Preparation of Resin Composition for Filling Through Holes A resin composition for filling through holes was prepared using the same method as that used in A-2.

B-3. Manufacture of multilayer printed wiring boards (1) 0.6 mm thick glass epoxy resin or BT
A starting material was a copper-clad laminate in which 18 μm copper foils 8 were laminated on both sides of an insulating substrate 1 made of resin (see FIG. 6A). First, the copper-clad laminate was drilled, subjected to an electroless plating treatment, and etched in a pattern to form conductor circuits 4 and through holes 9 on both surfaces of the substrate 1.

(2) The substrate on which the through-holes 29 and the conductor circuits 24 are formed is washed with water, dried, and then sprayed with an etching solution (Mec etch bond, manufactured by Mec Co.) to spray the conductor circuits 4 including the through-holes 9. The roughened surfaces 4a and 9a were formed on the surface of (see FIG. 6B).

(3) After preparing the resin filler described in the above B-2, within 24 hours after preparation by the following method,
A layer of a resin filler 10 ′ was formed in the through-hole 9, on a portion of the substrate 1 where no conductive circuit was formed, and on the outer edge of the conductive circuit 4. That is, first, the resin filler was pushed into the through holes using a squeegee, and then dried at 100 ° C. for 20 minutes. Next, a mask having an opening corresponding to the conductive circuit non-forming portion is placed on the substrate, and the resin filling material is also filled in the conductive circuit non-forming portion which is a concave portion using a squeegee. By drying under the condition of 20 minutes, a layer of the resin filler 10 'was formed (see FIG. 6C).

(4) One surface of the substrate after the treatment of the above (3) is subjected to belt sander polishing using # 600 belt polishing paper (manufactured by Sankyo Rikagaku Co., Ltd.) to form the surface of the conductor circuit 4 and the through holes 9. Polishing was performed so that the resin filler 10 'did not remain on the land surface, and then buffing was performed to remove scratches caused by the belt sander polishing. Such a series of polishing was similarly performed on the other surface of the substrate. Then, at 100 ° C for 1 hour, at 120 ° C for 3 hours, at 150 ° C
For 1 hour and at 180 ° C. for 7 hours to form a resin filler layer 10.

In this manner, the surface layer of the resin filler 10 formed in the through-hole 9 and the portion where the conductor circuit is not formed and the surface of the conductor circuit 4 are flattened, and the resin filler 10 and the side surface 4a of the conductor circuit 4 are removed. Was firmly adhered through the roughened surface, and an insulating substrate in which the inner wall surface 9a of the through hole 9 and the resin filler 10 were firmly adhered through the roughened surface was obtained (FIG. 6).
(D)). By this step, the surface of the resin filler layer 10 and the surface of the conductor circuit 4 become flush with each other.

(5) After the above substrate is washed with water and acid degreased,
The surface of the conductive circuit 4 and the land surface and the inner wall of the through hole 9 are etched by spraying an etching solution onto both surfaces of the substrate by spraying, so that the entire surface of the conductive circuit 4 is roughened 4a. , 9a (see FIG. 7A). In addition, as an etching solution,
A Mech etch bond manufactured by Mec Co. was used.

(6) Next, a resin film for an interlayer resin insulating layer slightly larger than the substrate prepared in B-1 was placed on the substrate, and the pressure was 0.4 MPa, the temperature was 80 ° C., and the pressing time was 1 hour.
After pre-pressing and cutting under the condition of 0 seconds, the interlayer resin insulating layer 2 was formed by bonding using a vacuum laminator by the following method (see FIG. 7B).
That is, a resin film for an interlayer resin insulation layer is placed on a substrate,
Degree of vacuum 65 Pa, pressure 0.4 MPa, temperature 80, time 6
This was completely press-bonded under the condition of 0 second, and then thermally cured at 170 ° C. for 30 minutes.

(7) Next, a CO ₂ gas laser having a wavelength of 10.4 μm is used to form a beam having a beam diameter of 4.0 through a mask having a through hole having a thickness of 1.2 mm formed on the interlayer resin insulating layer 2.
7 mm, a top hat mode, a pulse width of 8.0 μs, a diameter of a through hole of the mask of 1.0 mm, and a one-shot condition, a via hole opening 6 having a diameter of 80 μm was formed in the interlayer resin insulating layer 2 (FIG. c)).

(8) Next, SV-4 manufactured by Japan Vacuum Engineering Co., Ltd.
Plasma processing is performed using 540, and the interlayer resin insulation layer 2 is formed.
Was roughened (see FIG. 7D). Here, argon gas was used as an inert gas, and plasma treatment was performed for 2 minutes at a power of 200 W, a gas pressure of 0.6 Pa, and a temperature of 70 ° C. Next, after replacing the argon gas inside using the same apparatus, sputtering with Ni as a target was performed using SV-4540 at a pressure of 0.6 Pa and a temperature of 8 Pa.
The process was performed under the conditions of 0 ° C., power of 200 W, and time of 5 minutes, and a metal layer made of Ni was formed on the surface of the interlayer resin insulating layer 2. The thickness of the Ni layer is 0.1 μm.

(9) Next, the substrate on which the Ni layer was formed was immersed in an electroless copper plating aqueous solution having the following composition, and an electroless copper plating film having a thickness of 0.6 to 3.0 μm was formed on the Ni layer. Was formed (see FIG. 8A). In FIG. 8, a layer composed of a Ni layer and an electroless copper plating film is shown as a thin-film conductor layer 12. [Electroless plating aqueous solution] NiSO ₄ 0.003 mol /
l tartaric acid 0.200 mol / l copper sulfate 0.030 mol / l HCHO 0.050 mol / l NaOH 0.100 mol / l α, α'-bipyridyl 100 mg / l polyethylene glycol (PEG) 0.10 g / l [Electroless plating conditions] 40 minutes at a liquid temperature of 30 ° C

(10) Next, a commercially available photosensitive dry film is adhered to the substrate on which the thin film conductor layer 12 is formed, a mask is placed, and exposure is performed at 100 mJ / cm ² ,
By performing development processing with an aqueous solution of sodium carbonate, a plating resist 3 having a thickness of 20 μm was provided (see FIG. 8B).

(11) Then, the substrate was washed with water at 50 ° C., degreased, washed with water at 25 ° C., further washed with sulfuric acid, and then subjected to electrolytic plating under the following conditions to remove plating resist 3 An electrolytic copper plating film 3 having a thickness of 20 μm was formed on the formation portion (see FIG. 8C). [Electroplating solution] Sulfuric acid 2.24 mol / l Copper sulfate 0.26 mol / l Additive 19.5 ml / l (Atotech Japan, Capparaside GL) [Electroplating conditions] Current density 1 A / dm ² hours 65 minutes Temperature 22 ± 2 ℃

(12) Further, the plating resist 23 is
% NaOH, the thin film conductor layer under the plating resist 3 is etched and dissolved and removed with a mixed solution of nitric acid, sulfuric acid and hydrogen peroxide to remove the thin film conductor layer from the thin film conductor layer 12 and the electrolytic copper plating film 13. 18 μm thick conductor circuit 5
(Including via holes 7) were formed (see FIG. 8D).

(13) Next, by repeating the above steps (5) to (12), an upper interlayer resin insulating layer and a conductor circuit are formed in a laminated manner (FIGS. 9A to 10).
(A)). Further, a roughened surface was formed on the outermost conductive circuit by using the same method as the method used in the step (5).

(14) Next, the outermost interlayer resin insulation layer 2
An optical waveguide 18 having an optical path conversion mirror 19 was formed at a predetermined position on the surface of the optical waveguide by the following method (FIG. 10).
(B)). That is, a film-shaped optical waveguide made of PMMA (manufactured by Microparts Co., Ltd .: width 1 mm, thickness 20μ
m) was attached such that the side surface of the other end on the side where the light conversion mirror was not formed and the side surface of the interlayer resin insulating layer were aligned. The optical waveguide is attached by applying an adhesive made of a thermosetting resin to a thickness of 10 μm on the surface of the optical waveguide to be bonded to the interlayer resin insulating layer, and after pressing, curing at 60 ° C. for 1 hour. Was performed. In the present embodiment, the curing is performed under the condition of 60 ° C./1 hour, but step curing may be performed in some cases. This is because stress is not easily generated by the optical waveguide at the time of sticking.

(15) Next, a cresol novolak type epoxy resin (manufactured by Nippon Kayaku Co., Ltd.) dissolved in diethylene glycol dimethyl ether (DMDG) to a concentration of 60% by weight was used. Oligomer for imparting properties (molecular weight: 4000) 46.6
7 parts by weight, 80% by weight dissolved in methyl ethyl ketone
Of bisphenol A type epoxy resin (manufactured by Yuka Shell Co., Ltd.
Trade name: Epicoat 1001) 15.0 parts by weight, imidazole hardener (manufactured by Shikoku Chemicals, trade name: 2E4MZ-C)
N) 1.6 parts by weight, bifunctional acrylic monomer as photosensitive monomer (trade name: R604, manufactured by Nippon Kayaku Co., Ltd.) 3.0
Parts by weight, also polyvalent acrylic monomer (manufactured by Kyoei Chemical Co.,
A trade name: 1.5 parts by weight of DPE6A) and 0.71 parts by weight of a dispersion defoaming agent (manufactured by San Nopco, S-65) are placed in a container, stirred and mixed to prepare a mixed composition, and the mixed composition is prepared. Of benzophenone (Kanto Chemical Co., Ltd.) as a photopolymerization initiator and 0.2 part by weight of Michler's ketone (Kanto Chemical Co., Ltd.) as a photosensitizer at 25 ° C. A solder resist composition adjusted to 2.0 Pa · s was prepared, and the above solder resist composition was applied to both sides of the substrate on which the optical waveguide 18 was formed.
μm thickness, 70 ° C for 20 minutes, 70 ° C for 30 minutes
A drying treatment was performed under the conditions of minutes to form a layer 14 'of the solder resist composition (see FIG. 10C).

(16) Next, a 5 mm-thick photomask on which a pattern of an opening for forming a solder bump and an opening for an optical path is drawn on one side of the substrate is brought into close contact with the solder resist layer and exposed to ultraviolet light of 1000 mJ / cm ² . Exposure, DMTG
The solution was developed to form an opening having a diameter of 200 μm. Then, the solder resist layer is further heated at 80 ° C. for 1 hour, at 100 ° C. for 1 hour, at 120 ° C. for 1 hour, and at 150 ° C. for 3 hours to cure the solder resist layer.
A solder resist layer 14 having an opening 15 for forming a solder bump and an opening 11 for an optical element and having a thickness of 20 μm was formed (see FIG. 11A).

(17) Next, the substrate on which the solder resist layer 14 has been formed is coated with nickel chloride (2.3 × 10 ^-1 mol).
/ L), sodium hypophosphite (2.8 × 10 ^-1 mol)
/ L), sodium citrate (1.6 × 10 ^-1 mol /
2) in the electroless nickel plating solution having pH = 4.5 containing l)
After immersion for 0 minutes, a thickness of 5 μm
m of nickel plating layer was formed. Furthermore, the substrate gold potassium cyanide ^{(7.6 × 10 -3 mol / l} ), ammonium chloride ^{(1.9 × 10 -1 mol / l} ), sodium citrate (1.2 × 10 ^-1 mol / l), immersed in an electroless gold plating solution containing sodium hypophosphite (1.7 × 10 ^-1 mol / l) at 80 ° C. for 7.5 minutes to form a layer having a thickness of 0 on the nickel plating layer. A gold plating layer of 0.03 μm was formed to form a solder pad 16.

(18) Next, a solder paste is printed in the solder bump forming opening 15 formed in the solder resist layer 14 and reflowed at 200 ° C. to form the solder bump 17 in the solder bump forming opening 15. This was a multilayer printed wiring board (see FIG. 11B).

C. Manufacture of IC mounting optical communication device First, an IC chip is mounted on the IC chip mounting substrate manufactured through the above step A, and then resin sealing is performed.
An IC mounting substrate was obtained. . Next, this IC chip mounting board and the multilayer printed wiring board manufactured through the above-mentioned step B are arranged at predetermined positions so as to face each other, and are reflowed at 200 ° C. to connect the solder bumps of both boards to each other to perform solder connection. Part was formed, and an IC-mounted optical communication device was manufactured (FIG. 1).
reference).

With respect to the IC mounted optical communication device thus obtained, an optical fiber is attached to the exposed surface of the optical waveguide facing the light receiving element from the multilayer printed wiring board.
After attaching a detector to the exposed surface of the optical waveguide facing the light receiving element from the multilayer printed wiring board, an optical signal was sent through an optical fiber and operated by an IC chip, and then the optical signal was detected by the detector. However, it was found that a desired optical signal could be detected, and that the IC-mounted optical communication device manufactured in this example had sufficiently satisfactory performance as an optical communication device.

[0138]

As described above, the optical communication device of the present invention comprises an IC chip mounting substrate on which a light receiving element and a light emitting element are mounted on a predetermined position, and a multilayer having an optical waveguide formed on a predetermined position. Since it is composed of a printed wiring board, the connection loss between the mounted optical components is low, and the connection reliability is excellent as an optical communication device.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing one embodiment of an optical communication device according to the present invention.

FIG. 2 is a cross-sectional view schematically showing a part of a process of manufacturing an IC chip mounting substrate constituting the optical communication device of the present invention.

FIG. 3 is a cross-sectional view schematically showing a part of a process of manufacturing an IC chip mounting substrate constituting the optical communication device of the present invention.

FIG. 4 is a cross-sectional view schematically showing a part of a process of manufacturing an IC chip mounting substrate constituting the optical communication device of the present invention.

FIG. 5 is a cross-sectional view schematically showing a part of a step of manufacturing an IC chip mounting substrate constituting the optical communication device of the present invention.

FIG. 6 is a cross-sectional view schematically showing a part of a process of manufacturing a multilayer printed wiring board constituting the optical communication device of the present invention.

FIG. 7 is a cross-sectional view schematically showing a part of a process of manufacturing a multilayer printed wiring board constituting the optical communication device of the present invention.

FIG. 8 is a cross-sectional view schematically showing a part of a process of manufacturing a multilayer printed wiring board constituting the optical communication device of the present invention.

FIG. 9 is a cross-sectional view schematically showing a part of a process of manufacturing a multilayer printed wiring board constituting the optical communication device of the present invention.

FIG. 10 is a cross-sectional view schematically showing a part of a process of manufacturing a multilayer printed wiring board constituting the optical communication device of the present invention.

FIG. 11 is a cross-sectional view schematically showing a part of a process of manufacturing a multilayer printed wiring board constituting the optical communication device of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 multilayer printed wiring board 101 substrate 102 interlayer resin insulation layer 104 conductor circuit 107 via hole 109 through hole 111 optical path opening 114 solder resist layer 118 optical waveguide 119 light conversion mirror 120 IC chip mounting substrate 121 substrate 122 interlayer resin insulation layer 124 Conductor circuit 127 Via hole 129 Through hole 131 Opening for optical element 134 Solder resist layer 138 Light receiving element 139 Light emitting element 140 IC chip 141, 143 Solder joint 142 Conductive layer 150 Optical communication device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) H05K 3/46 G02B 6/12 BF Term (Reference) 2H047 KA03 KB09 LA09 MA05 MA07 5E336 AA04 AA16 BB03 CC31 CC57 EE01 GG25 5E338 AA03 BB75 CC10 CD32 5E344 AA01 AA22 BB02 BB06 DD02 EE06 EE23 5E346 AA12 AA15 AA22 AA32 AA43 AA51 BB20 FF45 HH01 HH11

Claims (4)

[Claims] 1. An optical communication device comprising an IC chip mounting substrate and a multilayer printed wiring board, wherein the IC chip mounting substrate has a light receiving portion and a light emitting portion on a side facing the multilayer printed wiring board. A light receiving element and a light emitting element are mounted so that the portions are exposed, and an optical waveguide is formed on the multilayer printed wiring board on a side facing the IC chip mounting substrate, and the optical waveguide and the light receiving element are formed. Alternatively, an optical communication device is configured to transmit an optical signal via the light emitting element. 2. The substrate for mounting an IC chip, wherein a conductor circuit and an interlayer resin insulating layer are laminated on the substrate, and the conductor circuits sandwiching the substrate are connected by through holes.
The optical communication device according to claim 1, wherein the conductor circuits sandwiching the interlayer resin insulation layer are connected to each other by via holes. 3. The multilayer printed wiring board, wherein a conductor circuit and an interlayer resin insulation layer are formed on a substrate by lamination, the conductor circuits sandwiching the substrate are connected to each other by through holes, and the interlayer resin insulation layer is sandwiched between the conductor circuits. 3. The optical communication device according to claim 1, wherein the conductor circuits are connected to each other by via holes. 4. The optical communication device according to claim 1, wherein the IC chip mounting substrate and the multilayer printed wiring board are formed with solder bumps for transmitting an electric signal. .