JP3771169B2 - Optical communication device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical communication device.
[0002]
In recent years, attention has been focused on optical fibers mainly in the communication field. In particular, in the IT (information technology) field, communication technology using optical fibers is required to develop a high-speed Internet network.
The optical fiber has features such as (1) low loss, (2) high bandwidth, (3) small diameter and light weight, (4) no induction, and (5) resource saving. Compared with communication systems using conventional metallic cables, the number of repeaters can be greatly reduced, making construction and maintenance easier, and making communication systems more economical and more reliable. Can be planned.
[0003]
In addition, since optical fibers can simultaneously multiplex and transmit not only light of one wavelength but also light of many different wavelengths using a single optical fiber, a large-capacity transmission line that can be used for a variety of applications. It can be realized and can also support video services and the like.
[0004]
Therefore, in such network communication such as the Internet, optical communication using an optical fiber is not only performed for communication of the backbone network, but also for communication between the backbone network and terminal devices (PC, mobile, game, etc.) It has also been proposed to be used for communication between each other.
When optical communication is used for communication between the backbone network and terminal equipment in this way, it is necessary to attach an optical communication device to the terminal equipment. Examples of the optical communication device include an optical waveguide that transmits an optical signal to a substrate, optical A device having optical components such as a light receiving element and a light emitting element for processing a signal has been proposed.
[0005]
[Problems to be solved by the invention]
However, conventional optical communication devices are not fully satisfactory in terms of connection reliability.
This is a factor for achieving optical communication with excellent connection reliability, that is, connection between optical components (for example, connection between an optical fiber and an optical waveguide, connection between an optical waveguide and a light receiving element, or a light emitting element). This is probably because the low connection loss could not be sufficiently ensured.
[0006]
[Means for Solving the Problems]
Accordingly, as a result of intensive studies to ensure low connection loss in the connection between the optical components, the present inventors have determined that each optical component has a predetermined value when mounted on the substrate and / or in the substrate. It was conceived that low connection loss can be secured by mounting at the position, that is, eliminating the positional deviation of each optical component, and the optical communication device of the present invention having the following configuration was completed.
[0007]
That is, the optical communication device of the present invention includes an IC chip mounting substrate and a multilayer printed wiring board.And facing each otherAn optical communication device,
IC chip mounting boardofMulti-layer printed wiring boardA solder resist layer having a solder bump forming opening and an optical element opening;
A light receiving element and a light emitting element respectively mounted on the optical element opening via a solder paste;
A solder bump of the IC chip mounting substrate formed in the solder bump forming opening;
Solder bumps of the multilayer printed wiring board formed on the side of the multilayer printed wiring board facing the IC chip mounting substrate;
Multi-layer printed wiring boardofOn the side facing the IC chip mounting substrateFormed by the self-alignment connection between the solder bumps of the IC chip mounting board and the solder bumps of the multilayer printed wiring board,The light receiving element or the light emitting elementBetweenOptical signalA plurality of optical waveguides arranged at respective transmission positions;
WithIt is characterized by that.
[0008]
Further, in the optical communication device of the present invention, the IC chip mounting substrate is formed by laminating a conductor circuit and an interlayer resin insulating layer on the substrate, and the conductor circuits sandwiching the substrate are connected by through holes, It is desirable that the conductor circuits sandwiching the interlayer resin insulation layer are connected to each other by via holes. In the multilayer printed wiring board, the conductor circuit and the interlayer resin insulation layer are laminated on the substrate, and the substrate is sandwiched between them. It is desirable that the conductor circuits are connected to each other by a through hole, and the conductor circuits sandwiching the interlayer resin insulating layer are connected to each other by a via hole.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the optical communication device of the present invention will be described.
IC chip mounting board and multilayer printed wiring boardAnd facing each otherAn optical communication device,
IC chip mounting boardofMulti-layer printed wiring boardA solder resist layer having a solder bump forming opening and an optical element opening;
A light receiving element and a light emitting element respectively mounted on the optical element opening via a solder paste;
A solder bump of the IC chip mounting substrate formed in the solder bump forming opening;
Solder bumps of the multilayer printed wiring board formed on the side of the multilayer printed wiring board facing the IC chip mounting substrate;
Multi-layer printed wiring boardofOn the side facing the IC chip mounting substrateFormed by the self-alignment connection between the solder bumps of the IC chip mounting board and the solder bumps of the multilayer printed wiring board,The light receiving element or the light emitting elementBetweenOptical signalA plurality of optical waveguides arranged at respective transmission positions;
WithIt is characterized by that.
[0010]
The optical communication device of the present invention is composed of an IC chip mounting substrate on which a light receiving element and a light emitting element are mounted at a predetermined position, and a multilayer printed wiring board on which an optical waveguide is formed at a predetermined position. The connection loss between the mounted optical components is low, and the connection reliability is excellent as an optical communication device.
[0011]
Further, in the optical communication device of the present invention, when the IC chip mounting substrate and the multilayer printed wiring board are connected via solder bumps, the both are more reliably secured by the self-alignment action of the solder. It can be arranged at a predetermined position.
The self-alignment action refers to an action in which the solder resist layer repels 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 reflow processing. When this self-alignment action is used, when connecting the IC chip mounting substrate on the multilayer printed wiring board via the solder bumps, it is assumed that a positional deviation has occurred between the two before reflowing. In addition, the IC chip mounting substrate moves during reflow, and the IC chip mounting substrate can be attached to an accurate position on the multilayer printed wiring board.
Therefore, if the optical components such as the light receiving element, the light emitting element, and the optical waveguide are attached to the IC chip mounting substrate and the multilayer printed wiring board at accurate positions, the multilayer printed wiring is provided via the solder bumps. By connecting the IC chip mounting substrate on the plate, an optical communication device having excellent connection reliability can be manufactured.
[0012]
The IC chip mounting substrate constituting the optical communication device has the light receiving element and the light emitting element mounted on the side facing the multilayer printed wiring board so that the light receiving part and the light emitting part are exposed.
Examples of the light receiving element include PD (photodiode), APD (avalanche photodiode), and the like.
These may be properly 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.
Of these, InGaAs is desirable because of its excellent light receiving sensitivity.
[0013]
Examples of the light emitting element include LD (semiconductor laser), DFB-LD (distributed feedback type-semiconductor laser), LED (light emitting diode), and the like.
These may be properly used in consideration of the configuration and required characteristics of the optical communication device.
[0014]
Examples of the material of the light emitting element include a compound of gallium, arsenic and phosphorus (GaAsP), a compound of gallium, aluminum and arsenic (GaAlAs), a compound of gallium and arsenic (GaAs), a compound of indium, gallium and arsenic (InGaAs), Indium, gallium, arsenic and phosphorus compounds (InGaAsP) can be used.
These may be properly used in consideration of the communication wavelength. For example, when the communication wavelength is 0.85 μm band, GaAlAs can be used, and when the communication wavelength is 1.3 μm band or 1.55 μm band. InGaAs or InGaAsP can be used.
The IC chip mounting substrate preferably has solder bumps for transmitting electrical signals. This is because electrical signals can be transmitted to / from external electronic components.
[0015]
The multilayer printed wiring board constituting the optical communication device has an optical waveguide formed on the side facing the IC chip mounting substrate.
Therefore, an optical signal can be transmitted through the optical waveguide.
[0016]
Examples of the material for the optical waveguide include quartz glass, compound semiconductors, and polymer materials.
Among these, polymers are desirable from the viewpoints of excellent workability, excellent adhesion to the interlayer resin insulating layer of the multilayer printed wiring board, and low cost.
[0017]
As the polymer material, conventionally known materials can be used. Specifically, for example, acrylic resins such as PMMA (polymethyl methacrylate), deuterated PMMA, and deuterated fluorinated PMMA; Examples thereof include polyimide resins; epoxy resins; UV curable epoxy resins; silicone resins such as deuterated silicone resins; polymers produced from benzocyclobutene.
[0018]
The thickness of the optical waveguide is desirably 5 to 50 μm, and the width is desirably 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 the same material. It is desirable to consist of.
Further, it is desirable that 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 optical path conversion mirror can be formed, for example, by grinding one end of the optical waveguide, as will be described later.
The multilayer printed wiring board preferably has solder bumps for transmitting electrical signals. This is because electrical signals can be transmitted to / from external electronic components.
[0019]
In the optical communication device of the present invention, the IC chip mounting substrate and the multilayer printed wiring board are disposed so that the light receiving element, the light emitting element, and the optical waveguide face each other, and the light receiving element or the above An optical signal can be transmitted through the light emitting element and the optical waveguide.
[0020]
Specifically, for example, the light receiving element, the light emitting element, and the optical waveguide can be disposed at predetermined positions by connecting the two via solder bumps. This is because the self-alignment action of solder can be used.
[0021]
Hereinafter, an example of an embodiment of an optical communication device configured as described above will be described with reference to the drawings.
FIG. 1 is a cross-sectional view schematically showing an embodiment of an optical communication device of the present invention. FIG. 1 shows an optical communication device in a state where an IC chip is mounted.
[0022]
As shown in FIG. 1, the optical communication device 150 includes an IC chip mounting substrate 120 on which an IC chip 140 is mounted and a multilayer printed wiring board 100. The IC chip mounting substrate 120, the multilayer printed wiring board 100, and the like. Are electrically connected via a solder connection portion 141.
[0023]
In the IC chip mounting substrate 120, conductor circuits 124 (124a, 124b) and an interlayer resin insulation layer 122 are laminated on both surfaces of the substrate 121, and the conductor circuits sandwiching the substrate 121 and the interlayer resin insulation layer 122 are formed. The sandwiched conductor circuits are electrically connected through through holes 129 (129a, 129b) and via holes 127 (127a, 127b, 127c, 127d), respectively.
Further, a solder resist layer 134 having solder bumps is formed on the outermost layer of the IC chip mounting substrate 120. In addition, the outermost layer on the side facing the multilayer printed wiring board 100 includes the light receiving portion 138a and the light receiving portion 138a. A light receiving element 138 and a light emitting element 139 are provided so that the light emitting portions 139a are exposed.
[0024]
In the multilayer printed wiring board 100, the conductor circuit 104 and the interlayer resin insulating layer 102 are laminated on both surfaces of the substrate 101, and the conductor circuits sandwiching the substrate 101 and the conductor circuits sandwiching the interlayer resin insulating layer 102 are These are electrically connected through a through hole 109 and a via hole 107, respectively.
In addition, a solder resist layer 114 having an optical path opening 111 and solder bumps is formed on the outermost layer of the multilayer printed wiring board 100 facing the IC chip mounting substrate 120, and an optical path opening 111 ( 111a, 111b), optical waveguides 118 (118a, 118b) including light conversion mirrors 119 (119a, 119b) are formed immediately below.
[0025]
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, and passes through the optical path conversion mirror 119a and the optical path opening 111a. Is transmitted to the light receiving element 138 (light receiving unit 138a), and then converted into an electric signal by the light receiving element 138, and further, conductive layer 142a-conductor circuit 124a-via hole 127a-through hole 129a-via hole 127b-solder connection. It is sent to the IC chip 140 via the part 143a.
[0026]
Further, the electrical signal sent from the IC chip 140 is sent to the light emitting element 139 through the solder connection portion 143b-via hole 127c-through hole 129b-via hole 127d-conductor circuit 124b-conductive layer 142b, and then emits light. The optical signal is converted into an optical signal by the element 139, and the optical signal is introduced from the light emitting element 139 (light emitting unit 139a) into the optical waveguide 118b through the optical path opening 111b and the optical conversion mirror 119b, and further, an optical fiber (not shown) is connected. Thus, it is sent to the outside as an optical signal.
[0027]
In the device for optical communication of the present invention, the optical / electrical signal conversion is performed in the IC chip mounting substrate, that is, at a position close to the IC chip. it can.
In addition, the electrical signal sent from the IC chip is converted into an optical signal as described above, and then sent to the multilayer printed wiring board via the solder bumps as well as sent to the outside via the optical fiber. Then, it is sent to electronic components such as other IC chips mounted on the multilayer printed wiring board via the conductor circuit (including via holes and through holes) of the multilayer printed wiring board.
[0028]
Next, a method for manufacturing the optical communication device of the present invention will be described.
In the optical communication device, for example, after an IC chip mounting substrate and a multilayer printed wiring board are separately manufactured, a light receiving element and a light emitting element of the IC chip mounting substrate, and a conductor circuit of the multilayer printed wiring board are provided. Both are arranged so as to face each other, and further, by reflow processing, solder bumps are connected to each other while adjusting the position of both, and a solder connection portion is formed.
Therefore, here, first, a method for manufacturing an IC chip mounting substrate and a method for manufacturing a multilayer printed wiring board will be described separately, and then a method for connecting them will be described.
[0029]
First, a method for 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. Moreover, you may form by performing an etching process to a copper clad laminated board or a RCC board | substrate.
[0030]
In addition, in the case where connection between conductor circuits sandwiching the insulating substrate is performed through holes, for example, after forming a through hole in the insulating substrate using a drill or a laser, an electroless plating process or the like is performed. Through holes are formed by applying. In addition, the diameter of the said through-hole is 100-300 micrometers normally.
Further, when a through hole is formed, it is desirable to fill the through hole with a resin filler.
[0031]
(2) Next, the surface of the conductor circuit is roughened as necessary.
Examples of the roughening formation treatment include blackening (oxidation) -reduction treatment, etching treatment using an etchant containing a cupric complex and an organic acid salt, and treatment by Cu-Ni-P needle alloy plating. Etc.
Here, when the roughened surface is formed, the average roughness of the roughened surface is usually preferably 0.1 to 5 μm, the adhesion between the conductor circuit and the interlayer resin insulating layer, the electric signal transmission capability of the conductor circuit. 2-4 μm is more desirable in view of the influence on the above.
The roughening process may be performed before the resin filler is filled in the through hole, 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.
[0032]
(3) Next, from a substrate on which a conductor circuit is formed, a thermosetting resin, a photosensitive resin, a resin in which a part of the thermosetting resin is acrylated, or a resin composite including these and a thermoplastic resin. An uncured resin layer is formed, or a resin layer made of a thermoplastic resin is formed.
The uncured resin layer can be formed by applying uncured resin with a roll coater, curtain coater, or the like, or thermocompression bonding an uncured (semi-cured) resin film.
Moreover, the resin layer which consists of the said thermoplastic resin can be formed by thermocompression-bonding the resin molded object shape | molded on the film.
[0033]
Among these, a method of thermocompression bonding an uncured (semi-cured) resin film is desirable, and the resin film can be crimped using, for example, a vacuum laminator or the like.
In addition, the pressure bonding conditions are not particularly limited, and may be appropriately selected in consideration of the composition of the resin film. Usually, the pressure is 0.25 to 1.0 MPa, the temperature is 40 to 70 ° C., the degree of vacuum is 13 to 1300 Pa, It is desirable to carry out under conditions of a time of about 10 to 120 seconds.
[0034]
Examples of the thermosetting resin include epoxy resins, phenol resins, polyimide resins, polyester resins, bismaleimide resins, polyolefin resins, polyphenylene ether resins, polyphenylene resins, and fluorine resins.
Specific examples of the epoxy resin include, for example, novolak type epoxy resins such as phenol novolak type and cresol novolak type, dicyclopentadiene-modified alicyclic epoxy resins, and the like.
[0035]
As said photosensitive resin, an acrylic resin etc. are mentioned, for example.
Moreover, as resin which acrylated a part of said thermosetting resin, what made the acrylate reaction of the thermosetting group of the above-mentioned thermosetting resin, methacrylic acid, and acrylic acid etc. are mentioned, for example.
[0036]
Examples of the thermoplastic resin include phenoxy resin, polyether sulfone (PES), polysulfone (PSF), polyphenylene sulfone (PPS) polyphenylene sulfide (PPES), polyphenylene ether (PPE) polyetherimide (PI), and the like. It is done.
[0037]
The resin composite is not particularly limited as long as it includes a thermosetting resin or a photosensitive resin (including a resin obtained by acrylating a part of the thermosetting resin) and a thermoplastic resin. Specific examples of the combination of the curable resin and the thermoplastic resin include phenol resin / polyether sulfone, polyimide resin / polysulfone, epoxy resin / polyether sulfone, and epoxy resin / phenoxy resin. Specific examples of the combination of the photosensitive resin and the thermoplastic resin include an acrylic resin / phenoxy resin, an epoxy resin in which a part of the epoxy group is acrylated, and polyether sulfone.
[0038]
In addition, the blending ratio of the thermosetting resin or the photosensitive resin and the thermoplastic resin in the resin composite is preferably thermosetting resin or photosensitive resin / thermoplastic resin = 95/5 to 50/50. This is because a high toughness value can be ensured without impairing heat resistance.
[0039]
The resin layer may be composed of two or more different resin layers.
Specifically, for example, the lower layer is formed from a thermosetting resin or a resin composite of photosensitive resin / thermoplastic resin = 50/50, and the upper layer is a thermosetting resin or photosensitive resin / thermoplastic resin = 90/50. It is formed from 10 resin composites.
By adopting such a configuration, it is possible to ensure excellent adhesion with the insulating substrate, and it is possible to ensure ease of formation when forming a via hole opening or the like in a subsequent process.
[0040]
Moreover, you may form the said resin layer using the resin composition for roughening surface formation.
The roughened surface-forming resin composition is, for example, an acid, an alkali, in an uncured heat-resistant resin matrix that is hardly soluble in a roughened liquid consisting of at least one selected from acids, alkalis and oxidizing agents. And a substance soluble in a roughening liquid comprising at least one selected from oxidizing agents.
As used herein, the terms “slightly soluble” and “soluble” refer to those having a relatively high dissolution rate as “soluble” for convenience when immersed in the same roughening solution for the same time. The slow one is called “slightly soluble” for convenience.
[0041]
The heat-resistant resin matrix is preferably one that can maintain the shape of the roughened surface when the roughened surface is formed on the interlayer resin insulation layer using the roughening liquid, for example, a thermosetting resin. , Thermoplastic resins, and composites thereof. Further, by using a photosensitive resin, the via hole opening may be formed in the interlayer resin insulating layer by exposure and development processing.
[0042]
Examples of the thermosetting resin include an epoxy resin, a phenol resin, a polyimide resin, a polyolefin resin, and a fluororesin. Moreover, when sensitizing the said thermosetting resin, methacrylic acid, acrylic acid, etc. are used, and a thermosetting group is (meth) acrylated.
[0043]
Examples of the epoxy resin include cresol novolac type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, alkylphenol novolac type epoxy resin, biphenol F type epoxy resin, naphthalene type epoxy resin, Examples thereof include cyclopentadiene type epoxy resins, epoxidized products of condensates of phenols and aromatic aldehydes having a phenolic hydroxyl group, triglycidyl isocyanurate, and alicyclic epoxy resins. These may be used alone or in combination of two or more. Thereby, it will be excellent in heat resistance.
[0044]
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.
[0045]
The substance soluble in the roughening liquid comprising at least one selected from the acid, alkali and oxidizing agent is preferably at least one selected from inorganic particles, resin particles and metal particles.
[0046]
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.
[0047]
Examples of the aluminum compound include alumina and aluminum hydroxide. Examples of the calcium compound include calcium carbonate and calcium hydroxide. Examples of the potassium compound include potassium carbonate. Examples of the magnesium compound include magnesia, dolomite, basic magnesium carbonate, and talc. Examples of the silicon compound include silica and zeolite. These may be used alone or in combination of two or more.
[0048]
The alumina particles can be dissolved and removed with hydrofluoric acid, and calcium carbonate can be dissolved and removed with hydrochloric acid. Sodium-containing silica and dolomite can be dissolved and removed with an alkaline aqueous solution.
[0049]
Examples of the resin particles include those made of a thermosetting resin, a thermoplastic resin, and the like. When the resin particles are immersed in a roughening solution made of at least one selected from an acid, an alkali, and an oxidizing agent, the heat resistance It is not particularly limited as long as it has a faster dissolution rate than the resin matrix. Specifically, for example, amino resins (melamine resins, urea resins, guanamine resins, etc.), epoxy resins, phenol resins, phenoxy resins, polyimide resins, Examples include polyphenylene resin, polyolefin resin, fluororesin, and bismaleimide-triazine resin. These may be used alone or in combination of two or more.
The resin particles must be previously cured. This is because if the resin is not cured, the resin particles will be dissolved in a solvent for dissolving the resin matrix.
[0050]
Further, as the resin particles, rubber particles, liquid phase resin, liquid phase rubber, or the like may be used.
Examples of the rubber particles include acrylonitrile-butadiene rubber, polychloroprene rubber, polyisoprene rubber, acrylic rubber, polysulfuric rigid rubber, fluorine rubber, urethane rubber, silicone rubber, and ABS resin.
Further, for example, polybutadiene rubber, epoxy-modified, urethane-modified, (meth) acrylonitrile-modified various modified polybutadiene rubber, carboxyl group-containing (meth) acrylonitrile-butadiene rubber, and the like may be used.
[0051]
As the liquid phase resin, an uncured solution of the thermosetting resin can be used. As a specific example of such a liquid phase resin, for example, a mixed liquid of an uncured epoxy oligomer and an amine curing agent. Etc.
Examples of the liquid phase rubber include, for example, the above-mentioned polybutadiene rubber, epoxy-modified, urethane-modified, various modified polybutadiene rubbers such as (meth) acrylonitrile modification, uncured solutions such as carboxyl group-containing (meth) acrylonitrile / butadiene rubber, etc. Can be used.
[0052]
When preparing the photosensitive resin composition using the liquid phase resin or liquid phase rubber, so that the heat resistant resin matrix and the soluble substance are not compatible with each other uniformly (that is, so as to phase-separate), It is necessary to select these substances.
By mixing the heat-resistant resin matrix selected according to the above criteria and a soluble substance, the liquid-phase resin or liquid-phase rubber “islands” are dispersed in the “sea” of the heat-resistant resin matrix. Alternatively, it is possible to prepare 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.
And after hardening the photosensitive resin composition of such a state, a roughened surface can be formed by removing the liquid phase resin or liquid phase rubber of "the sea" or "the island".
[0053]
Examples of the metal particles include gold, silver, copper, tin, zinc, stainless steel, aluminum, nickel, iron, lead, and the like. These may be used alone or in combination of two or more.
In addition, the metal particles may be coated with a resin or the like in order to ensure insulation.
[0054]
When two or more kinds of the above-mentioned soluble substances are used in combination, the combination of the two kinds of soluble substances to be mixed is preferably a combination of resin particles and inorganic particles. Both of them have low conductivity, so that the insulation of the interlayer resin insulation layer can be secured, and the thermal expansion can be easily adjusted between the poorly soluble resin and the interlayer resin comprising the roughened surface forming resin composition This is because no crack occurs in the insulating layer, and no peeling occurs between the interlayer resin insulating layer and the conductor circuit.
[0055]
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 desirable 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, for example, an aqueous solution of chromic acid, chromium sulfuric acid, alkaline permanganate (such as potassium permanganate), or the like is preferably used.
Moreover, as said alkali, aqueous solution, such as sodium hydroxide and potassium hydroxide, is desirable.
[0056]
The average particle size of the soluble substance is desirably 10 μm or less.
Further, a relatively large coarse particle having an average particle diameter of 2 μm or less and a fine particle having a relatively small average particle diameter may be used in combination. That is, a soluble substance having an average particle diameter of 0.1 to 0.5 μm and a soluble substance having an average particle diameter of 1 to 2 μm are combined.
[0057]
Thus, by combining average particles, relatively large coarse particles, and fine particles having a relatively small average particle diameter, the dissolution residue of the electroless plating film is eliminated, and the amount of palladium catalyst under the plating resist is reduced. Furthermore, a shallow and complicated roughened surface can be formed.
Furthermore, by forming a complicated roughened surface, a practical peel strength can be maintained even if the roughened surface has small irregularities.
The coarse particles preferably have an average particle size of more than 0.8 μm and less than 2.0 μm, and the fine particles preferably have an average particle size of 0.1 to 0.8 μm.
[0058]
(4) Next, when forming an interlayer resin insulation layer using a thermosetting resin or a resin composite as the material, the uncured resin insulation layer is cured and a via hole opening is formed. And an interlayer resin insulation layer. In this step, a through hole may be formed as necessary.
The via hole opening is preferably formed by laser processing. Further, when a photosensitive resin is used as the material for the interlayer resin insulation layer, it may be formed by exposure and development processing.
[0059]
When an interlayer resin insulating layer using a thermoplastic resin as the material is formed, a via hole opening is formed in the 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 treatment.
Further, when forming a through hole in this step, the through hole may be formed by drilling or laser processing.
[0060]
Examples of the laser used for the laser treatment include a carbon dioxide laser, an ultraviolet laser, and an excimer laser. Among these, an excimer laser and a short pulse carbon dioxide laser are desirable.
[0061]
Among excimer lasers, it is desirable to use a hologram type excimer laser. The hologram method is a method of irradiating a target object with laser light through a hologram, a condensing lens, a laser mask, a transfer lens, and the like. By using this method, a large number of openings are formed in the resin film layer by one irradiation. Can be formed efficiently.
[0062]
When a carbon dioxide laser is used, the pulse interval is 10^-Four-10^-8It is desirable to be seconds. Moreover, it is desirable that the time for irradiating the laser for forming the opening is 10 to 500 μsec.
In addition, by irradiating laser light through an optical system lens and a mask, a large number of openings for via holes can be formed at one time. This is because laser light having the same intensity and the same irradiation intensity can be irradiated to a plurality of portions through the optical system lens and the mask.
After forming the via hole opening in this manner, desmear treatment may be performed as necessary.
[0063]
(5) Next, a conductor circuit is formed on the surface of the interlayer resin insulation layer including the inner wall of the via hole opening.
In forming the conductor circuit, first, a thin film conductor layer is formed on the surface of the interlayer resin insulation layer.
The thin film conductor layer can be formed by a method such as electroless plating or sputtering.
[0064]
Examples of the material for the thin film conductor layer 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, economical efficiency, and the like.
The thickness of the thin film conductor layer is preferably 0.3 to 2.0 [mu] m, more preferably 0.6 to 1.2 [mu] m when the thin film conductor layer is formed by electroless plating. Moreover, when forming by sputtering, 0.1-1.0 micrometer is desirable.
[0065]
In addition, a roughened surface may be formed on the surface of the interlayer resin insulation layer before forming the thin film conductor layer. By forming the roughened surface, the adhesion between the interlayer resin insulation layer and the thin film conductor layer can be improved. In particular, when an interlayer resin insulation layer is formed using a roughened surface forming resin composition, it is desirable to form a roughened surface using an acid, an oxidizing agent, or the like.
[0066]
Further, when the through hole is formed in the step (4), when the thin film conductor layer is formed on the interlayer resin insulation layer, the through hole is formed by forming the thin film conductor layer on the wall surface of the through hole. Also good.
[0067]
(6) Next, a plating resist is formed on the substrate on which the thin film conductor layer is formed.
The plating resist can be formed, for example, by sticking a photosensitive dry film, placing a photomask made of a glass substrate or the like on which a plating resist pattern is drawn, and performing exposure and development processing.
[0068]
(7) Thereafter, electroplating is performed using the thin-film conductor layer as a plating lead, and an electroplating layer is formed in the plating resist non-forming portion. As the electroplating, copper plating is desirable.
The thickness of the electroplating layer is preferably 5 to 20 μm.
[0069]
Then, a conductor circuit (including a via hole) can be formed by removing the plating resist, the electroless plating film and the thin film conductor layer under the plating resist.
The plating resist may be removed using, for example, an alkaline aqueous solution, and the thin film conductor layer may be removed using a mixed solution of sulfuric acid and hydrogen peroxide, sodium persulfate, ammonium persulfate, ferric chloride, chloride. What is necessary is just to perform using etching liquid, such as cupric.
Moreover, after forming the said conductor circuit, you may remove the catalyst on an interlayer resin insulation layer using an acid or an oxidizing agent as needed. This is because deterioration of electrical characteristics can be prevented.
Moreover, after forming this plating resist, it replaces with the method (process (6) and (7)) which forms an electroplating layer, forms an electroplating layer on the whole surface on a thin film conductor layer, and performs an etching process. A conductor circuit may be formed using a method.
[0070]
Further, when a through hole is formed in the steps (4) and (5), a resin filler may be filled in the through hole.
Moreover, when the resin filler is filled in the through hole, a lid plating layer that covers the surface portion of the resin filler layer may be formed by performing electroless plating, if necessary.
[0071]
(8) Next, when a lid plating layer is formed, if necessary, the surface of the lid plating layer is subjected to a roughening treatment, and further, if necessary, steps (3) to (7) Is repeated to form an interlayer resin insulation layer and a conductor circuit on both surfaces. In this step, a through hole may be formed or may not be formed.
[0072]
(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 are formed.
The solder resist layer can be formed using, for example, a solder resist composition made of a polyphenylene ether resin, a polyolefin resin, a fluororesin, a thermoplastic elastomer, an epoxy resin, a polyimide resin, or the like.
[0073]
Examples of solder resist compositions other than those described above include, for example, (meth) acrylates of novolak epoxy resins, imidazole curing agents, bifunctional (meth) acrylic acid ester monomers, and (meth) acrylic acid having a molecular weight of about 500 to 5,000. Examples include paste polymers containing ester polymers, thermosetting resins composed of bisphenol-type epoxy resins, photosensitive monomers such as polyvalent acrylic monomers, glycol ether solvents, and the viscosity at 25 ° C. It is desirable that the pressure is adjusted to 1 to 10 Pa · s.
[0074]
(10) Next, a solder bump forming opening and an optical element mounting opening are formed in the solder resist layer.
The formation of the solder bump forming opening can be performed by a method similar to the method of forming the via hole opening, that is, exposure development processing or laser processing.
Moreover, when forming a solder resist layer, a solder film having openings for forming solder bumps and openings for mounting optical elements is prepared by preparing a resin film having openings at desired positions in advance and pasting the resin film. A resist layer may be formed.
[0075]
(11) Next, the conductor circuit portion exposed by forming the opening for forming the solder bump is covered with a corrosion-resistant metal such as nickel, palladium, gold, silver, or platinum as necessary to form a solder pad. . In these, it is desirable to form a coating layer with metals, such as nickel-gold, nickel-silver, nickel-palladium, nickel-palladium-gold.
The coating layer can be formed by, for example, plating, vapor deposition, electrodeposition, or the like. Among these, it is desirable to form by plating from the viewpoint that the uniformity of the coating layer is excellent.
In this step, it is desirable to form a coating layer also on the conductor circuit portion exposed by forming the optical element mounting opening.
[0076]
(12) Next, a solder bump is formed by reflowing after filling the solder pad with a solder paste through a mask in which an opening is formed in a portion corresponding to the solder pad.
[0077]
(13) Further, an optical element (light receiving element and light emitting element) is 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 step (12), and soldering (conductive layer) by attaching the optical element when performing reflow. Should be implemented 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.
[0078]
Further, instead of the surface mounting method described above, when the optical element mounting opening is formed in the step (10), the opening is formed in such a size that the optical element can be accommodated. You may mount by accommodating an optical element in an opening through an agent. In this case, the light receiving element and the light emitting element are built in the solder resist layer.
Through such steps, an IC chip mounting substrate constituting the optical communication device of the present invention can be manufactured.
[0079]
Next, the manufacturing method of a multilayer printed wiring board is demonstrated.
(1) First, the same steps as (1) to (8) of the method for manufacturing an IC chip mounting substrate are performed to produce a substrate in which a conductor circuit and an interlayer resin insulating layer are repeatedly laminated on both sides. In this process as well, through holes are appropriately formed.
[0080]
(2) Next, an optical waveguide is formed in the conductor circuit non-forming portion on the interlayer resin insulating layer on the side facing the IC chip mounting substrate.
When the optical waveguide is formed by using an inorganic material such as quartz glass as the material, the optical waveguide can be formed by attaching an optical waveguide that has been previously formed into a predetermined shape via an adhesive.
The optical waveguide made of the inorganic material is, for example, LiNbO._Three LiTaO_Three It can be formed by depositing an inorganic material such as a liquid phase epitaxial method, a chemical deposition method (CVD), a molecular beam epitaxial method, or the like.
[0081]
In addition, when the optical waveguide is formed using a polymer material, an optical waveguide forming film that has been previously formed into a film shape on a substrate or a release film is pasted on the interlayer resin insulating layer, or an interlayer resin is formed. An optical waveguide can be formed by forming directly on the insulating layer.
Specifically, it can be formed using a selective polymerization method, a method using reactive ion etching and photolithography, a direct exposure method, a method using injection molding, a photo bleaching method, a method combining these, and the like. .
These methods can be used both when the optical waveguide is formed on the substrate and the release film, and when it is directly formed on the interlayer resin insulating layer.
[0082]
An optical path conversion mirror is formed in the optical waveguide.
The optical path conversion mirror may be formed before being mounted on the interlayer resin insulation layer, or may be formed after being mounted on the interlayer resin insulation layer, but the optical waveguide is directly formed on the interlayer resin insulation layer. Except for the case of forming, it is desirable to form an optical path conversion mirror in advance. The work can be easily performed, and there is no risk of scratching or damaging other members constituting the multilayer printed wiring board during the work, such as conductor circuits and interlayer resin insulation layers. It is.
[0083]
The method for forming the optical path conversion mirror is not particularly limited, and a conventionally known formation method can be used. Specifically, machining using a diamond saw or blade with a V-shaped 90 ° tip, machining by reactive ion etching, laser ablation, or the like can be used.
[0084]
(3) Next, a solder resist layer is formed on the outermost layer of the substrate on which the optical waveguide is formed.
The solder resist layer can be formed using, for example, a resin composition similar to the resin composition used when forming the solder resist layer of the IC chip mounting substrate.
[0085]
(4) Next, openings for forming solder bumps and openings for optical paths are formed in the solder resist layer on the side facing the IC chip mounting substrate.
The formation of the solder bump forming opening and the optical path opening may be performed using a method similar to the method of forming the solder bump forming opening on the IC chip mounting substrate, that is, using an exposure development process or a laser process. it can.
The formation of the solder bump formation opening and the formation of the optical path opening may be performed simultaneously or separately.
[0086]
Among these, when forming a solder resist layer, a method of forming a solder bump forming opening and an optical path opening by applying a resin composition containing a photosensitive resin as a material and performing an exposure development process. It is desirable to select.
This is because when the optical path opening is formed by exposure and development processing, there is no possibility of scratching the optical waveguide existing under the optical path opening when the opening is formed.
Moreover, when forming a solder resist layer, a solder resist layer having a solder bump forming opening and an optical path opening is prepared in advance by preparing a resin film having an opening at a desired position and pasting the resin film. May be formed.
[0087]
If necessary, solder bump forming openings may also be formed in the solder resist layer on the side opposite to the surface facing the IC chip mounting substrate.
This is because the external connection terminals can also be formed on the solder resist layer on the opposite side of the surface facing the IC chip mounting substrate through the post-process.
[0088]
(5) Next, the conductor circuit portion exposed by forming the opening for forming the solder bump is coated with a corrosion-resistant metal such as nickel, palladium, gold, silver, platinum, or the like as necessary to form a solder pad. . Specifically, a method similar to the method of forming solder pads on the IC chip mounting substrate may be used.
[0089]
(6) Next, a solder bump is formed by reflowing after filling the solder pad with a solder paste through a mask in which an opening is formed in a portion corresponding to the solder pad. In addition, in the solder resist layer opposite to the surface facing the IC chip mounting substrate, pins are arranged on the external substrate connection surface, or solder balls are formed, so that PGA (Pin Grid Array) or A BGA (Ball Grid Array) may be used.
Through such steps, a multilayer printed wiring board constituting the optical communication device of the present invention can be manufactured.
[0090]
Next, a method for manufacturing an optical communication device using the IC chip mounting substrate and the multilayer printed wiring board manufactured by the above method will be described.
First, a solder connection portion is formed by the solder bump of the IC 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 substrate and the multilayer printed wiring board are respectively arranged in a predetermined position facing each other in a predetermined direction, and are connected by reflowing.
[0091]
In this process, since the IC chip mounting substrate and the multilayer printed wiring board are connected using their solder bumps, there is a slight misalignment between the two when they are placed opposite to each other. In addition, both can be arranged at a predetermined position by a self-alignment effect by solder during reflow.
[0092]
Next, an IC chip is mounted on the IC chip mounting substrate, and then, if necessary, resin sealing is performed to obtain an optical communication device.
The IC chip can be mounted by a conventionally known method.
Also, the IC chip is mounted before connecting the IC chip mounting substrate and the multilayer printed wiring board, and the optical chip is used for optical communication by connecting the IC chip mounting substrate on which the IC chip is mounted and the multilayer printed wiring board. It may be a device.
[0093]
【Example】
Hereinafter, the present invention will be described in more detail.
(Example 1)
A. Fabrication of IC chip mounting substrate
A-1. Preparation of resin film for interlayer resin insulation layer
30 parts by weight of bisphenol A type epoxy resin (epoxy equivalent 469, Epicoat 1001 manufactured by Yuka Shell Epoxy Co., Ltd.), 40 parts by weight of cresol novolac type epoxy resin (epoxy equivalent 215, Epiklon N-673 manufactured by Dainippon Ink & Chemicals, Inc.), triazine 30 parts by weight of a structure-containing phenol novolak resin (phenolic hydroxyl group equivalent 120, Phenolite KA-7052 manufactured by Dainippon Ink & Chemicals, Inc.) was dissolved in 20 parts by weight of ethyl diglycol acetate and 20 parts by weight of solvent naphtha with stirring. Thereto, terminal epoxidized polybutadiene rubber (Nagase Kasei Kogyo Denarex R-45EPT) 15 parts by weight, 2-phenyl-4,5-bis (hydroxymethyl) imidazole pulverized product 1.5 parts by weight, finely pulverized silica 2 parts by weight , Silicon Added to prepare an epoxy resin composition agent 0.5 parts by weight.
The obtained epoxy resin composition was applied on a PET film having a thickness of 38 μm using a roll coater so that the thickness after drying was 50 μm, and then dried at 80 to 120 ° C. for 10 minutes, whereby an interlayer resin was obtained. A resin film for an insulating layer was produced.
[0094]
A-2. Preparation of resin composition for filling through-hole
100 parts by weight of bisphenol F type epoxy monomer (manufactured by Yuka Shell Co., Ltd., molecular weight: 310, YL983U), SiO having an average particle diameter of 1.6 μm and a maximum particle diameter of 15 μm or less coated with a silane coupling agent on the surface₂ 170 parts by weight of spherical particles (manufactured by Adtech, CRS 1101-CE) and 1.5 parts by weight of a leveling agent (Perenol S4, manufactured by San Nopco) are placed in a container and mixed by stirring. A 49 Pa · s resin filler was prepared. As the curing agent, 6.5 parts by weight of an imidazole curing agent (manufactured by Shikoku Kasei Co., Ltd., 2E4MZ-CN) was used.
[0095]
A-3. Manufacture of IC chip mounting substrates
(1) A copper-clad laminate in which 18 μm copper foil 28 is laminated on both surfaces of an insulating substrate 21 made of glass epoxy resin or BT (bismaleimide triazine) resin having a thickness of 0.8 mm was used as a starting material (see FIG. 2 (a)). First, the copper-clad laminate was drilled, subjected to electroless plating, and etched into a pattern to form conductor circuits 24 and through holes 29 on both surfaces of the substrate 21.
[0096]
(2) The substrate on which the through hole 29 and the conductor circuit 24 are formed is washed with water and dried, followed by NaOH (10 g / l), NaClO.₂ (40 g / l), Na_Three PO_Four Blackening treatment using an aqueous solution containing (6 g / l) as a blackening bath (oxidation bath), and NaOH (10 g / l), NaBH_Four A reduction treatment using an aqueous solution containing (6 g / l) as a reducing bath was performed to form roughened surfaces 24 a and 29 a on the surface of the conductor circuit 24 including the through holes 29 (see FIG. 2B).
[0097]
(3) After preparing the resin filler described in A-2 above, within 24 hours after preparation by the following method, the conductor circuit non-formed portion on the one side of the through hole 29 and the substrate 21 and the outer edge of the conductor circuit 24 A layer of a resin filler 30 'was formed on the part.
That is, first, a resin filler was pushed into a through hole using a squeegee, and then dried under conditions of 100 ° C. and 20 minutes. Next, a mask having an opening corresponding to the conductor circuit non-formed part is placed on the substrate, and the conductor circuit non-formed part which is a recess is filled with a resin filler using a squeegee, A layer of the resin filler 30 'was formed by drying for 20 minutes (see FIG. 2C).
[0098]
(4) The surface of the conductor circuit 24 or the land surface of the through hole 29 is applied to one surface of the substrate after the processing of (3) by belt sander polishing using # 600 belt polishing paper (manufactured by Sankyo Rikagaku Co., Ltd.). Polishing was performed so that the resin filler 30 'did not remain, and then buffing was performed to remove scratches due to the belt sander polishing. Such a series of polishing was similarly performed on the other surface of the substrate.
Subsequently, the heat processing of 100 degreeC for 1 hour, 120 degreeC for 3 hours, 150 degreeC for 1 hour, and 180 degreeC for 7 hours was performed, and the resin filler layer 30 was formed.
[0099]
In this way, the surface layer portion of the resin filler 30 and the surface of the conductor circuit 24 formed in the through hole 29 and the conductor circuit non-forming portion are flattened, and the resin filler 30 and the side surface 24a of the conductor circuit 24 are roughened. An insulating substrate was obtained in which the inner wall surface 29a of the through hole 29 and the resin filler 30 were firmly adhered through the roughened surface (see FIG. 2D). By this step, the surface of the resin filler layer 30 and the surface of the conductor circuit 24 are flush with each other.
[0100]
(5) After washing the substrate with water and acid degreasing, soft etching is performed, and then an etching solution is sprayed on both surfaces of the substrate to spray the surface of the conductor circuit 24, the land surface of the through hole 29, and the inner wall. Thus, roughened surfaces 24a and 29a were formed on the entire surface of the conductor circuit 24 (see FIG. 3A). As an etching solution, an etching solution 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 (MEC Etch Bond, manufactured by MEC) was used.
[0101]
(6) Next, a resin film for an interlayer resin insulation layer that is slightly larger than the substrate prepared in A-1 is placed on the substrate, and temporarily mounted under conditions of a pressure of 0.4 MPa, a temperature of 80 ° C., and a pressure bonding time of 10 seconds. After crimping and cutting, an interlayer resin insulation layer 22 was further formed by sticking using a vacuum laminator apparatus by the following method (see FIG. 3B).
That is, a resin film for an interlayer resin insulation layer was subjected to main pressure bonding on a substrate under conditions of a degree of vacuum of 65 Pa, a pressure of 0.4 MPa, a temperature of 80, and a time of 60 seconds, and then thermally cured at 170 ° C. for 30 minutes.
[0102]
(7) Next, CO 2 having a wavelength of 10.4 μm is passed through a mask in which a through hole having a thickness of 1.2 mm is formed on the interlayer resin insulating layer 22.₂ Via hole with a gas laser diameter of 4.0 mm, top hat mode, pulse width 8.0 μsec, mask through-hole diameter 1.0 mm, and interlayer resin insulation layer 22 with a diameter of 80 μm under conditions of one shot. 26 was formed (see FIG. 3C).
[0103]
(8) The substrate on which the via hole opening 26 is formed is immersed in an 80 ° C. solution containing 60 g / l permanganic acid for 10 minutes to dissolve and remove the epoxy resin particles present on the surface of the interlayer resin insulating layer 22. Thus, a roughened surface was formed on the surface including the inner wall surface of the via hole opening 26 (see FIG. 3D).
[0104]
(9) Next, the substrate after the above treatment was immersed in a neutralization solution (manufactured by Shipley Co., Ltd.) and washed with water.
Further, by applying a palladium catalyst to the surface of the roughened substrate (roughening depth 3 μm), catalyst nuclei are formed on the surface of the interlayer resin insulation layer 22 (including the inner wall surface of the via hole opening 26). Was attached (not shown). That is, the substrate is made of palladium chloride (PdCl₂ ) And stannous chloride (SnCl₂ The catalyst was imparted by immersing it in a catalyst solution containing) and depositing palladium metal.
[0105]
(10) Next, the substrate is immersed in an electroless copper plating aqueous solution having the following composition, and the surface of the interlayer resin insulation layer 22 (including the inner wall surface of the via hole opening 26) and the wall surface of the through hole 29 Then, an electroless copper plating film 32 having a thickness of 0.6 to 3.0 μm was formed (see FIG. 4A).
[0106]
[Electroless plating aqueous solution]
NiSO_Four                   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
[0107]
(11) Next, a commercially available photosensitive dry film is pasted on the substrate on which the electroless copper plating film 32 is formed, and a mask is placed thereon, and 100 mJ / cm.² Then, a plating resist 23 having a thickness of 20 μm was provided by developing with a 0.8% aqueous sodium carbonate solution (see FIG. 4B).
[0108]
(12) Next, the substrate is washed with 50 ° C. water and degreased, washed with 25 ° C. water and further washed with sulfuric acid, and then subjected to electrolytic plating under the following conditions to form a plating resist 23 non-formed portion. Then, an electrolytic copper plating film 33 having a thickness of 20 μm was formed (see FIG. 4C).
[0109]
[Electrolytic plating solution]
Sulfuric acid 2.24 mol / l
Copper sulfate 0.26 mol / l
Additive 19.5 ml / l
(Manufactured by Atotech Japan, Kaparaside GL)
[Electrolytic plating conditions]
Current density 1 A / dm²
65 minutes
Temperature 22 ± 2 ° C
[0110]
(13) Further, after removing the plating resist 23 with 5% NaOH, the electroless plating film under the plating resist 23 is removed by dissolution by etching with a mixed solution of sulfuric acid and hydrogen peroxide. A conductor circuit 25 (including a via hole 27) having a thickness of 18 μm composed of the plating film 32 and the electrolytic copper plating film 33 was formed (see FIG. 4D).
Further, a roughened surface was formed on the surface of the conductor circuit 25 (including the via hole 27) using the same etchant (MEC etch bond) as the etchant used in the step (5).
[0111]
(14) Next, a photosensitizing agent obtained by acrylated 50% of an epoxy group of a cresol novolac type epoxy resin (manufactured by Nippon Kayaku Co., Ltd.) dissolved in diethylene glycol dimethyl ether (DMDG) to a concentration of 60% by weight. 46.67 parts by weight of oligomer (molecular weight: 4000), 15.0 parts by weight of 80% by weight of bisphenol A type epoxy resin (trade name: Epicoat 1001 manufactured by Yuka Shell Co., Ltd.) dissolved in methyl ethyl ketone, imidazole curing agent (Shikoku Kasei Co., Ltd., trade name: 2E4MZ-CN) 1.6 parts by weight, photofunctional monomer bifunctional acrylic monomer (Nippon Kayaku Co., Ltd., trade name: R604) 4.5 parts by weight, also polyvalent acrylic monomer ( Kyoei Chemical Co., Ltd., trade name: DPE6A) 1.5 parts by weight, dispersion antifoaming agent (San Nopco, S-65) Take 1 part by weight in a container, stir and mix to prepare a mixed composition. 2.0 parts by weight of benzophenone (manufactured by Kanto Chemical Co., Inc.) as a photopolymerization initiator for this mixed composition, as a photosensitizer By adding 0.2 parts by weight of Michler's ketone (manufactured by Kanto Chemical Co., Inc.), a solder resist composition having a viscosity adjusted to 2.0 Pa · s at 25 ° C. was obtained.
The viscosity is measured with a B-type viscometer (DVL-B type, manufactured by Tokyo Keiki Co., Ltd.) for 60 minutes.^-1(Rpm), rotor No. 4, 6 min^-1(Rpm), rotor No. 3 according.
[0112]
(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 insulation layer 22 and the conductor circuit 25 (including the via hole 27) are formed, and is performed at 70 ° C. for 20 minutes. Then, a drying treatment was performed at 70 ° C. for 30 minutes to form a solder resist composition layer 34 ′ (see FIG. 5A).
[0113]
(16) Next, a photomask having a thickness of 5 mm on which patterns of openings for forming solder bumps and openings for optical elements (light receiving elements and light emitting elements) are drawn is brought into close contact with the solder resist layer to be 1000 mJ / cm.² Were exposed to UV light and developed with DMTG solution to form an opening having a diameter of 200 μm.
Further, the solder resist layer is cured by heating 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. A solder resist layer 34 having an optical element opening 31 and a thickness of 20 μm was formed (see FIG. 5B). In addition, as said solder resist composition, a commercially available solder resist composition can also be used.
[0114]
(17) Next, the substrate on which the solder resist layer 34 is formed is made of nickel chloride (2.3 × 10^-1mol / l), sodium hypophosphite (2.8 × 10^-1mol / l), sodium citrate (1.6 × 10^-1A nickel plating layer having a thickness of 5 μm was formed in the solder bump forming opening 35 and the optical element opening 31 by immersing in an electroless nickel plating solution containing 0.5 mol / l) of pH = 4.5. Further, the substrate was made of potassium gold cyanide (7.6 × 10 6^-3mol / l), ammonium chloride (1.9 × 10^-1mol / l), sodium citrate (1.2 × 10^-1mol / l), sodium hypophosphite (1.7 × 10^-1Molle-l) was immersed in an electroless gold plating solution at 80 ° C. for 7.5 minutes to form a 0.03 μm-thick gold plating layer on the nickel plating layer.
[0115]
(18) Next, a solder paste is printed on the solder bump forming opening 35 and the optical element opening 31 formed in the solder resist layer 34, and the light receiving element 38 and the solder paste printed on the optical element opening 31 The light receiving portion 38a and the light emitting portion 39a of the light emitting element 39 are attached while being aligned and reflowed at 200 ° C. to mount the light receiving element 38 and the light emitting element 39, and to attach solder bumps 37 to the solder bump forming openings 35. An IC chip mounting substrate was formed.
The light receiving element 38 was made of InGaAs, and the light emitting element 39 was made of InGaAsP (see FIG. 5C).
[0116]
B. Fabrication of multilayer printed wiring board
B-1. Preparation of resin film for interlayer resin insulation layer
The resin film for interlayer resin insulation layers was produced using the method similar to the method used by A-1.
B-2. Preparation of resin composition for filling through-hole
A resin composition for filling a through hole was produced using the same method as used in A-2.
[0117]
B-3. Manufacture of multilayer printed wiring boards
(1) A copper-clad laminate in which 18 μm copper foil 8 is laminated on both surfaces of an insulating substrate 1 made of glass epoxy resin or BT resin having a thickness of 0.6 mm was used as a starting material (see FIG. 6A). ). First, the copper-clad laminate was drilled, subjected to electroless plating, and etched into a pattern to form conductor circuits 4 and through holes 9 on both sides of the substrate 1.
[0118]
(2) The substrate on which the through hole 29 and the conductor circuit 24 are formed is washed with water and dried, and then an etching solution (MEC etch, MEC etch bond) is sprayed on the surface of the conductor circuit 4 including the through hole 9. Roughened surfaces 4a and 9a were formed (see FIG. 6B).
[0119]
(3) After preparing the resin filler described in B-2 above, within 24 hours after preparation by the following method, the conductor circuit non-formed part on the one side of the through hole 9 and the substrate 1 and the outer edge of the conductor circuit 4 A layer of resin filler 10 'was formed on the part.
That is, first, a resin filler was pushed into a through hole using a squeegee, and then dried under conditions of 100 ° C. and 20 minutes. Next, a mask having an opening corresponding to the conductor circuit non-formed part is placed on the substrate, and the conductor circuit non-formed part which is a recess is filled with a resin filler using a squeegee, The layer of resin filler 10 'was formed by drying on the conditions for 20 minutes (refer FIG.6 (c)).
[0120]
(4) One side of the substrate after the processing of (3) above is applied to the surface of the conductor circuit 4 and the land surface of the through hole 9 by belt sander polishing using # 600 belt polishing paper (manufactured by Sankyo Rikagaku). Polishing was performed so that the resin filler 10 'did not remain, and then buffing was performed to remove scratches due to the belt sander polishing. Such a series of polishing was similarly performed on the other surface of the substrate.
Subsequently, the heat processing of 100 degreeC for 1 hour, 120 degreeC for 3 hours, 150 degreeC for 1 hour, and 180 degreeC for 7 hours was performed, and the resin filler layer 10 was formed.
[0121]
In this way, the surface layer portion of the resin filler 10 and the surface of the conductor circuit 4 formed in the through hole 9 and the conductor circuit non-forming portion are flattened, and the resin filler 10 and the side surface 4a of the conductor circuit 4 are roughened. An insulating substrate was obtained in which the inner wall surface 9a of the through hole 9 and the resin filler 10 were firmly adhered through the roughened surface (see FIG. 6D). By this step, the surface of the resin filler layer 10 and the surface of the conductor circuit 4 are flush with each other.
[0122]
(5) After washing the substrate with water and acid degreasing, soft etching is performed, and then an etching solution is sprayed on both surfaces of the substrate to spray the surface of the conductor circuit 4, the land surface of the through hole 9, and the inner wall. Thus, roughened surfaces 4a and 9a were formed on the entire surface of the conductor circuit 4 (see FIG. 7A). As an etchant, MEC Etch Bond manufactured by MEC was used.
[0123]
(6) Next, a resin film for an interlayer resin insulation layer that is slightly larger than the substrate prepared in B-1 above is placed on the substrate, and temporarily mounted under the conditions of pressure 0.4 MPa, temperature 80 ° C., and pressure bonding time 10 seconds. After crimping and cutting, an interlayer resin insulating layer 2 was further formed by sticking using a vacuum laminator apparatus by the following method (see FIG. 7B). That is, a resin film for an interlayer resin insulation layer was subjected to main pressure bonding on a substrate under conditions of a degree of vacuum of 65 Pa, a pressure of 0.4 MPa, a temperature of 80, and a time of 60 seconds, and then thermally cured at 170 ° C. for 30 minutes.
[0124]
(7) Next, CO 2 having a wavelength of 10.4 μm is passed through a mask in which a through hole having a thickness of 1.2 mm is formed on the interlayer resin insulation layer 2.₂ With a gas laser, a via hole opening with a diameter of 80 μm in the interlayer resin insulation layer 2 under the conditions of a beam diameter of 4.0 mm, a top hat mode, a pulse width of 8.0 μsec, a mask through hole diameter of 1.0 mm, and one shot. 6 was formed (see FIG. 7C).
[0125]
(8) Next, plasma treatment was performed using SV-4540, manufactured by Nippon Vacuum Technology Co., Ltd., to roughen the surface of the interlayer resin insulation layer 2 (see FIG. 7D). Here, argon gas was used as an inert gas, and plasma treatment was performed for 2 minutes under the conditions of power 200 W, gas pressure 0.6 Pa, and temperature 70 ° C.
Next, using the same apparatus, after replacing the argon gas inside, using SV-4540, sputtering using Ni as a target was performed under conditions of atmospheric pressure 0.6 Pa, temperature 80 ° C., power 200 W, and time 5 minutes. A metal layer made of Ni was formed on the surface of the interlayer resin insulation layer 2. The thickness of the Ni layer is 0.1 μm.
[0126]
(9) Next, the substrate on which the Ni layer was formed was immersed in an electroless copper plating aqueous solution having the following composition to form an electroless copper plating film having a thickness of 0.6 to 3.0 μm on the Ni layer. (See FIG. 8 (a)). 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_Four                    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
[0127]
(10) Next, a commercially available photosensitive dry film is pasted on the substrate on which the thin film conductor layer 12 is formed, and a mask is placed thereon, and 100 mJ / cm.² The plating resist 3 having a thickness of 20 μm was provided by developing with a 0.8% aqueous sodium carbonate solution (see FIG. 8B).
[0128]
(11) Next, the substrate is washed with 50 ° C. water and degreased, washed with 25 ° C. water and further washed with sulfuric acid, and then subjected to electrolytic plating under the following conditions to form a plating resist 3 non-formed portion. Then, an electrolytic copper plating film 3 having a thickness of 20 μm was formed (see FIG. 8C).
[Electrolytic plating solution]
Sulfuric acid 2.24 mol / l
Copper sulfate 0.26 mol / l
Additive 19.5 ml / l
(Manufactured by Atotech Japan, Kaparaside GL)
[Electrolytic plating conditions]
Current density 1 A / dm²
65 minutes
Temperature 22 ± 2 ° C
[0129]
(12) Further, after removing the plating resist 23 with 5% NaOH, the thin film conductor layer under the plating resist 3 is dissolved and removed by etching with a mixed solution of nitric acid, sulfuric acid and hydrogen peroxide. A conductor circuit 5 (including the via hole 7) having a thickness of 18 μm composed of the layer 12 and the electrolytic copper plating film 13 was formed (see FIG. 8D).
[0130]
(13) Next, by repeating the steps (5) to (12) above, an upper interlayer resin insulation layer and a conductor circuit were laminated (see FIGS. 9A to 10A). ). Further, a roughened surface was formed on the outermost conductor circuit using the same method as used in the step (5).
[0131]
(14) Next, an optical waveguide 18 having an optical path conversion mirror 19 was formed at a predetermined position on the surface of the outermost interlayer resin insulation layer 2 using the following method (see FIG. 10B).
That is, a film-shaped optical waveguide made of PMMA in which a 45 ° optical path conversion mirror 19 is formed in advance using a diamond saw having a V-shaped 90 ° tip at one end (manufactured by Microparts: width 1 mm, thickness 20 μm) was pasted so that the side surface of the other end on the light conversion mirror non-forming side 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 adhesive surface of the optical waveguide with the interlayer resin insulation layer, and curing at 60 ° C. for 1 hour after pressure bonding. It went by.
In this embodiment, curing is performed under conditions of 60 ° C./1 hour, but step curing may be performed depending on circumstances. This is because stress is hardly generated by the optical waveguide at the time of pasting.
[0132]
(15) Next, a photosensitizing agent obtained by acrylated 50% of an epoxy group of a cresol novolac type epoxy resin (manufactured by Nippon Kayaku Co., Ltd.) dissolved in diethylene glycol dimethyl ether (DMDG) to a concentration of 60% by weight. 46.67 parts by weight of oligomer (molecular weight: 4000), 15.0 parts by weight of 80% by weight of bisphenol A type epoxy resin (trade name: Epicoat 1001 manufactured by Yuka Shell Co., Ltd.) dissolved in methyl ethyl ketone, imidazole curing agent (Shikoku Kasei Co., Ltd., trade name: 2E4MZ-CN) 1.6 parts by weight, photosensitive monomer bifunctional acrylic monomer (Nippon Kayaku Co., Ltd., trade name: R604) 3.0 parts by weight, also polyvalent acrylic monomer ( Kyoei Chemical Co., Ltd., trade name: DPE6A) 1.5 parts by weight, dispersion antifoaming agent (San Nopco, S-65). Take 1 part by weight in a container, stir and mix to prepare a mixed composition. 2.0 parts by weight of benzophenone (manufactured by Kanto Chemical Co., Inc.) as a photopolymerization initiator for this mixed composition, as a photosensitizer By adding 0.2 parts by weight of Michler's ketone (manufactured by Kanto Chemical Co., Inc.), a solder resist composition having a viscosity adjusted to 2.0 Pa · s at 25 ° C. is prepared, and both surfaces of the substrate on which the optical waveguide 18 is formed are prepared. The solder resist composition was applied to a thickness of 35 μm and dried under conditions of 70 ° C. for 20 minutes and 70 ° C. for 30 minutes to form a solder resist composition layer 14 ′ (FIG. 10 ( c)).
[0133]
(16) Next, a photomask having a thickness of 5 mm on which a pattern of openings for forming solder bumps and openings for optical paths is drawn on one surface of the substrate is brought into close contact with the solder resist layer to be 1000 mJ / cm.² Were exposed to UV light and developed with DMTG solution to form an opening having a diameter of 200 μm.
Further, the solder resist layer is cured by heat treatment at 80 ° C. for 1 hour, 100 ° C. for 1 hour, 120 ° C. for 1 hour, and 150 ° C. for 3 hours. A solder resist layer 14 having an optical element opening 11 and a thickness of 20 μm was formed (see FIG. 11A).
[0134]
(17) Next, the substrate on which the solder resist layer 14 is formed is nickel chloride (2.3 × 10^-1mol / l), sodium hypophosphite (2.8 × 10^-1mol / l), sodium citrate (1.6 × 10^-1A nickel plating layer having a thickness of 5 μm was formed in the solder bump forming opening 15 by immersing in an electroless nickel plating solution containing 0.5 mol / l) of pH = 4.5. Further, the substrate was made of potassium gold cyanide (7.6 × 10 6^-3mol / l), ammonium chloride (1.9 × 10^-1mol / l), sodium citrate (1.2 × 10^-1mol / l), sodium hypophosphite (1.7 × 10^-1A gold plating layer having a thickness of 0.03 μm was formed on the nickel plating layer as a solder pad 16 by dipping in an electroless gold plating solution containing 1 mol / l) at 80 ° C. for 7.5 minutes.
[0135]
(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. It was set as the board (refer FIG.11 (b)).
[0136]
C. Manufacture of IC-mounted optical communication devices
First, an IC chip was mounted on an IC chip mounting substrate manufactured through the above step A, and then resin sealing was performed to obtain an IC mounting substrate. .
Next, this IC chip mounting substrate and the multilayer printed wiring board manufactured through the above step B are placed opposite to each other at a predetermined position and reflowed at 200 ° C. to connect the solder bumps of both substrates to each other. The IC mounting optical communication device was manufactured (see FIG. 1).
[0137]
For 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, and the optical waveguide facing the light receiving element is separated from the multilayer printed wiring board. After attaching the detector to the exposed surface of the optical signal, sending the optical signal through the optical fiber, calculating with the IC chip and then detecting the optical signal with the detector, the desired optical signal can be detected, It has been clarified that the IC-mounted optical communication device manufactured in this example has sufficiently satisfactory performance as an optical communication device.
[0138]
【The invention's effect】
As described above, an optical communication device according to the present invention includes an IC chip mounting substrate on which a light receiving element and a light emitting element are mounted at predetermined positions, and a multilayer printed wiring board on which an optical waveguide is formed at predetermined positions. Since it is configured, 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 an embodiment of an optical communication device of 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 for 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 process 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 for 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 for 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 for 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 for manufacturing a multilayer printed wiring board constituting the device for optical communication of the present invention.
FIG. 10 is a cross-sectional view schematically showing part of a process for manufacturing the multilayer printed wiring board constituting the device for optical communication of the present invention.
FIG. 11 is a cross-sectional view schematically showing part of a process for manufacturing the multilayer printed wiring board constituting the device for optical communication of the present invention.
[Explanation of symbols]
100 multilayer printed wiring board
101 substrate
102 Interlayer resin insulation layer
104 Conductor circuit
107 Bahia Hall
109 through hole
111 Optical path aperture
114 Solder resist layer
118 Optical waveguide
119 Mirror for light conversion
120 IC chip mounting substrate
121 substrate
122 Interlayer resin insulation layer
124 conductor circuit
127 via hole
129 Through hole
131 Aperture for optical element
134 Solder resist layer
138 Light receiving element
139 Light Emitting Element
140 IC chip
141, 143 Solder connection
142 Conductive layer
150 Optical communication devices

Claims (3)

An optical communication device in which an IC chip mounting substrate and a multilayer printed wiring board are arranged to face each other.
A solder resist layer having the provided on the opposite side of the multilayer printed wiring board, openings for forming solder bumps and the opening for the optical element of the IC chip mounting board,
A light receiving element and a light emitting element respectively mounted on the optical element opening via a solder paste;
A solder bump of the IC chip mounting substrate formed in the opening for forming the solder bump;
Solder bumps of the multilayer printed wiring board formed on the side of the multilayer printed wiring board facing the IC chip mounting substrate;
Wherein formed on the side facing the IC chip mounting board of the multilayer printed wiring board by self-alignment connection between the solder bumps of the solder bumps of the IC chip mounting board multi-layer printed wiring board, the light receiving element or the A plurality of optical waveguides arranged at positions for transmitting optical signals to and from the light emitting elements ,
Optical communication devices, characterized in that it comprises a.   In the IC chip mounting substrate, a conductor circuit and an interlayer resin insulation layer are laminated on the substrate, the conductor circuits sandwiching the substrate are connected by through holes, and the conductor circuits sandwiching the interlayer resin insulation layer are connected to each other. The optical communication device according to claim 1, wherein the devices are connected by via holes.   In the multilayer printed wiring board, a conductor circuit and an interlayer resin insulating layer are laminated on a substrate, conductor circuits sandwiching the substrate are connected by through holes, and conductor circuits sandwiching the interlayer resin insulating layer are connected to each other. The device for optical communication according to claim 1, wherein the devices are connected by via holes.

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