JP4334482B2 - Manufacturing method of composite member - Google Patents

Description

The present invention relates electrical, electronic, the method of producing a composite member for use in the wiring board or the like in the fields of communication.

  In recent years, high integration and miniaturization of various electric and electronic parts including semiconductors have been progressing. It is certain that this trend will intensify in the future. Along with this, miniaturization of metal wiring and formation of three-dimensional wiring have been attempted for high-density mounting on printed wiring boards.

  In particular, three-dimensional wiring is indispensable for high-density mounting, and various methods have been proposed for manufacturing a wiring board having three-dimensional wiring. In forming a three-dimensional wiring on a wiring board, a multilayer wiring board structure is configured by stacking two-dimensional wiring boards, as represented by, for example, a build-up wiring board. In such a multilayer wiring board structure, adjacent wiring layers are coupled by conductive columns called vias.

Conventionally, in order to form a via, a method is generally used in which an insulator is provided with a via hole of a predetermined size using a drill or a CO ₂ laser, and the hole is plated or filled with a conductive paste. Has been.
As another method, a method of forming a via by filling a conductor in an insulator made of a porous substrate has been proposed (for example, see Patent Documents 1 and 2). Since a porous substrate is used, in such a method, it is not necessary to form a through hole by photolithography or a drill or a laser. However, in these methods, since the via is formed by exposing the porous substrate serving as an insulator, exposure light is scattered in the porous substrate. Since the porous substrate is exposed beyond the range of the opening portion of the mask pattern that is actually used during exposure, there is a problem that it is difficult to make the conductor layer fine.
JP-A-7-207450 Japanese Patent Laid-Open No. 11-25755

  As described above, when exposure light scatters, the exposure pattern spreads as compared to the case where scattering does not occur.

  Therefore, if scattering of exposure light can be prevented, a merit that a finer conductor layer pattern can be formed is expected. However, if the scattering of the exposure light is reduced, the intensity of the scattering component of the exposure light is reduced, and the intensity of the non-scattering component that goes straight increases. As a result, the penetration of the wiring into the porous base material becomes deep, and it becomes difficult to form the wiring on the back surface of the portion where the surface wiring is formed. In addition, when the base material on which the wiring is formed is laminated, there is a problem that it is difficult to ensure insulation on the back surface. Furthermore, when the substrate has irregularities, the pattern exposure becomes non-uniform, and it becomes extremely difficult to stably form particularly fine wiring.

The present invention has been made in view of the above circumstances, and can be used to manufacture a composite member that can stably form a pattern of a fine conductor layer that prevents exposure light from being scattered and has less penetration into the porous substrate. It aims to provide a method.

The method for producing a composite member according to one aspect of the present invention includes a continuous pore formed three-dimensionally, forming a photosensitive layer in a pore of a porous substrate made of an insulating material, Filling the filler from at least one of the surface and the back surface of the porous substrate, leaving an unfilled layer inside, and at least one of the surface and the back surface is 40% or less of the total thickness of the porous substrate Alternatively, the step of forming a filling layer at a depth of 15 μm or less and 1 μm or more to produce a composite member-forming substrate;
From the side having the filling layer of the composite member forming substrate, pattern exposure to a predetermined region,
Removing the filler from the composite member-forming substrate after pattern exposure;
A step of selectively filling a conductive material into an exposed part or an unexposed part of the composite member forming base material from which the filler has been removed,
The filler satisfies the condition represented by the following mathematical formula.

(In the above formula (1), εA is the refractive index of the insulating material constituting the porous substrate, εB is the refractive index of the filler, and the refractive index of air is 1. )

According to an aspect of the present invention, there is provided a method for producing a composite member that can stably form a fine conductor layer pattern that prevents exposure light from being scattered and has less penetration into a porous substrate.

  A method for manufacturing a composite member according to an embodiment of the present invention will be described below with reference to the drawings.

  First, a photosensitive layer is formed in the pores of the porous substrate to prepare a porous substrate having a photosensitive layer as shown in FIG. The porous substrate may be made of any insulating material as long as it has three-dimensionally formed continuous pores, and specifically includes polymers and ceramics.

  Examples of the polymer include epoxy resins, bismaleimide-triazine resins, PEEK resins, butadiene oils and the like, resins conventionally used as insulating base materials for printed wiring boards, other polyolefins such as polyethylene and polypropylene, polybutadiene, poly Polydienes such as isoprene and polyvinylethylene, acrylic resins such as polymethyl acrylate and polymethyl methacrylate, polystyrene derivatives, polyacrylonitrile derivatives such as polyacrylonitrile and polymethacrylonitrile, polyacetals such as polyoxymethylene, polyethylene terephthalate, poly Polyamides such as polyesters including butylene terephthalate and aromatic polyesters, polyarylates, aromatic polyamides such as aramid resin, and nylons. , Polyimides, epoxy resins, aromatic polyethers such as poly-p-phenylene ether, polyethersulfones, polysulfones, polysulfides, fluorine-based polymers such as polytetrafluoroethylene (PTFE), polybenzoxazoles , Polybenzothiazoles, polyphenylenes such as polyparaphenylene, polyparaphenylene vinylene derivatives, polysiloxane derivatives, novolac resins, melamine resins, urethane resins, polycarbodiimide resins, and the like.

The organic material as described above can be prepared and used in a sheet shape by, for example, a stretching method or a phase change method. Specifically, it is a PTFE stretched sheet or a porous sheet formed by a phase change method such as polysulfone, polyamide, polyimide, polyamideimide, etc. Among these porous substrates, polymers having low dielectric constant and excellent heat resistance are used. In particular, it is preferable to use liquid crystalline polymers such as polyimides and aromatic polyamides, and fluorine-based polymers such as polytetrafluoroethylene.

  In addition, since the porous sheet prepared by selectively removing a specific phase from the three-dimensional network microphase separation structure of the block copolymer has the same pore size in the same sheet, it forms a fine conductive portion. And most preferred. The method for selectively removing a specific phase from the microphase separation structure is not particularly limited. For example, after decomposing a polymer of a specific phase by ozone oxidation or β-ray irradiation, the decomposition product is removed by a method such as solvent washing. And making it porous.

  Examples of the material for the porous sheet produced from the microphase separation structure include a polycarbooxysilane sheet, a crosslinked polybutadiene sheet, and a polycyclohexene sheet. Moreover, you may remove by decomposing | dissolving and volatilizing the specific phase of a micro phase-separation structure, and the porous sheet of heat resistant polymers, such as a polyimide, can be produced.

  Examples of the ceramic include metal oxides such as silica, alumina, titania and potassium titanate, silicon carbide, silicon nitride, aluminum nitride and the like. Using such an inorganic material, for example, a porous ceramic sheet produced by a sol-gel method, an emulsion templating method, or the like can be used.

  Furthermore, a porous sheet modified by a surface treatment such as a hydrophilization treatment as described above may be used as the porous substrate.

  The average pore diameter of the pores in the porous substrate is preferably in the range of 0.05 μm to 10 μm, more preferably in the range of 0.05 μm to 5 μm, and further 0.1 to 0.5 μm. It is desirable to be in the range. When the average pore diameter is too small, it is difficult to fill the conductive material into the porous substrate. On the other hand, if it is too large, it is difficult to form a fine conductive part. When the pore diameter is too large, the plating nucleus distribution density becomes insufficient when it is formed by plating, and it becomes difficult to form fine conductive portions. The average pore diameter of the porous substrate can be measured by small-angle X-ray scattering measurement, light scattering measurement, observation of a cross-sectional optical microscope, scanning electron microscope, transmission electron microscope, or the like.

  A photosensitive layer is formed in the pores of such a porous substrate as shown in FIG. The photosensitive layer is used to selectively form a conductive portion by filling a conductive material in a later step, and by exposure, either an exposed portion or an unexposed portion is subjected to cation exchange groups and anion exchange. It is a layer capable of forming at least one of the groups. This photosensitive layer is formed of a material composed of a photosensitive reducing agent, a metal salt, or the like.

The cation exchange group is a group capable of adsorbing a cation or a group capable of reacting with a base to be cationized to express hydrophilicity, and includes an anionic group and an acidic group. For example, carboxyl group and its salt (—COOX group), sulfoxyl group and its salt (—SO ₃ X group), phosphoric acid group and its salt (—PO ₃ X ₂ group), silanol group and its salt (—SiOX group) ), A phenolic hydroxyl group and a salt thereof (-φ-OX group (X is selected from a hydrogen atom, an alkali metal or alkaline earth metal, a typical metal belonging to Periodic Tables I and II, and an ammonium group. Φ is And divalent aromatic rings)).

When electroless plating is performed by adsorbing metal ions, metal compounds or metal colloids to ion exchange groups, cation exchange groups exhibiting a pKa value of 7.2 or less determined from ion dissociation constants in water. Is more preferable. When the pKa value exceeds 7.2, the amount of adsorption per unit area when adsorbing metal ions or metal colloids is small, and electroless plating may not be performed sufficiently. The cation exchange group is most preferably a —COOX group that provides a sufficient amount of adsorption. Furthermore, although the —SO ₃ X group has a sufficient amount of adsorption, it may corrode the conductive part by generating a strong acid after the production of the composite member.

  An anion exchange group is a group capable of adsorbing an anion, or a group that can be anionized by reacting with an acid to express hydrophilicity, and includes a cationic group and a basic group. . Examples of the cationic group include aliphatic amines such as ammonium groups, quaternary ammonium salt derivative groups of aromatic amines, or quaternary nitrogen-containing heterocycles such as pyridinium groups and imidazolium groups. An ammonium salt derivative group is mentioned.

  As described above, not only those that selectively form ion exchange groups, but also the photosensitive layer formed on the inner surface of the porous substrate pores and the insulating material that forms the porous substrate by exposure to the chemicals. The photosensitive layer may be formed of a photosensitive material that reacts and acts in such a manner that the insulating substance constituting the porous substrate changes to selectively form an ion exchange group in the exposed portion. Examples of such a material include a hydroxyl group and a carboxyl group that have a property of easily binding a porous substrate made of a hydrophobic fluororesin to a fluorine atom and trapping a fluorine atom released from the resin by exposure. And compounds having an ion exchange group such as an amino group. In this case, ion exchange groups are introduced into the fluororesin, and this portion can be selectively filled with a conductive material by plating or the like.

  As described above, the photosensitive layer needs to be exposed to light to form a plating nucleus that is a reaction start point of electroless plating.

  “By exposure” refers to a trigger for causing a chemical reaction, and includes exposure performed when a chemical reaction occurs when the photosensitive layer is exposed to form an ion exchange group alone. Further, when the photosensitive layer is exposed to a chemical reaction, a precursor of some ion exchange group is generated, and when this precursor further causes a chemical reaction to form an ion exchange group, so-called exposure is performed. It also includes exposure performed when ion exchange groups are formed by a multistage reaction triggered by a chemical reaction.

  Examples of the molecule that independently generates an ion exchange group by exposure include o-nitrobenzyl ester derivatives and p-nitrobenzyl ester sulfonate derivatives of carboxylic acid or silanol. Furthermore, peroxide esters such as peroxides of tert-butyl ester are also used, and when these peroxide esters are exposed, carboxyl groups of cation exchange groups are formed.

  Examples of molecules that generate ion exchange groups by a multi-step reaction triggered by a chemical reaction by exposure include quinonediazides and azide derivatives. The quinonediazides are converted into indene carboxylic acids by the reaction of an intermediate produced by exposure with water to generate a carboxyl group. Specific examples include o-quinonediazide derivatives such as benzoquinonediazide, naphthoquinonediazide, and anthraquinonediazide. The azide group generates nitrene by exposure, and generates an amino group and the like by subsequent hydrogen abstraction reaction.

  Furthermore, a chemically amplified photosensitizer containing a photoacid generator and a molecule containing a group that generates an ion exchange group in the presence of an acid can also be used. When such a photosensitizer is used, heat treatment is performed after exposure. As a result, the sensitivity can be increased and the exposure wavelength can be shifted to the longer wavelength side. For example, a compound obtained by introducing a tetrahydropyranyl group or a tert-butyl group as a protecting group into an acrylic resin, and naphthalimide trifluoromethanesulfonate as a photoacid generator may be used.

  A group or molecule that loses an ion-exchange group by exposure is a group or molecule that has an ion-exchange group before irradiation and this ion-exchange group is eliminated by exposure or changes to a hydrophobic group. Specific examples include groups and molecules containing a carboxyl group that can be decomposed by causing a decarboxylation reaction. Examples include α-cyanocarboxylic acid derivatives, α-nitrocarboxylic acid derivatives, α-phenylcarboxylic acid derivatives, α-nitrocarboxylic acid derivatives, α-phenylcarboxylic acid derivatives, β, γ-olefin carboxylic acids, and the like. As the basic compound, any compound can be used as long as it is neutralized by the acid released from the photoacid generator and acts as a catalyst for the decarboxylation reaction of the carboxyl group-containing compound. Any compound may be used. Preferably, ammonia, primary amines, secondary amines, tertiary amines and the like are used.

  The content of the photobase generator and the basic compound is 0.1 wt% to 30 wt%, preferably 0.5 wt% to 15 wt% in the photosensitive layer. If the amount is less than 0.1% by weight, the decarboxylation reaction does not proceed. If the amount exceeds 30% by weight, deterioration of the carboxyl group-containing compound remaining in the unexposed area may be promoted.

  The photosensitive layer is exposed to an alkaline or acidic aqueous solution when a metal ion, a metal compound, or a metal colloid is adsorbed in a later step or filled with a conductive material. In order to avoid easily dissolving in such an aqueous solution, the group that generates or disappears the ion exchange group contained in the photosensitive layer forming material is desirably supported or bonded to a polymer or a polymer compound. . Examples of polymers and polymer compounds include phenolic resins such as phenol novolac resins, xylenol novolac resins, vinylphenol resins, cresol novolac resins, polyamide resins, polyimide resins, polyester resins, polyolefin resins, polyacrylic acid ester derivatives, and Examples thereof include polysiloxane derivatives.

  If the introduction amount of the group that generates or disappears an ion exchange group in the polymer is too small, it becomes difficult to sufficiently adsorb the metal ion, the metal compound, or the metal colloid. As a result, when metal ions, metal compounds or metal colloids are adsorbed or filled with a conductive material, dissolution or swelling is likely to occur in the alkali or acidic liquid used. Furthermore, the produced composite member is likely to absorb moisture, and problems such as poor insulation are likely to occur. The introduction amount of a group that generates or disappears an ion exchange group into the polymer is preferably 5% to 300%, more preferably 30% to 70%. The introduction rate here is expressed by the following equation.

Introduction rate (%) = (number of groups that generate or disappear ion exchange groups) ÷ (number of monomer units of polymer) × 100
Various sensitizers may be added to the photosensitive layer forming material. By adding a sensitizer, the sensitivity can be improved and the photosensitive wavelength can be changed variously according to the light source used. Moreover, it is preferable to sensitize with light having a wavelength that easily transmits through the substrate, such as light having a wavelength other than the absorption wavelength of the insulating material constituting the porous substrate.

  Furthermore, various crosslinking agents may be added to the photosensitive layer forming material. As the crosslinkable compound or crosslinkable group, one that is polymerized by three-dimensional crosslinking upon exposure is used.

  The introduction amount of the crosslinking group in the polymer is preferably 1% to 300%, more preferably 20% to 200%. The introduction rate here is expressed by the following equation.

Introduction rate (%) = (number of crosslinking groups) / (number of monomer units of polymer) × 100
The addition amount of the crosslinkable compound to the photosensitive layer is preferably 1% to 50% by weight, and more preferably set to a range of 10% to 30%. When the amount is too small, crosslinking is insufficient, and the metal ions, metal compounds, and metal colloids are adsorbed or easily dissolved or swollen in an alkali or acidic liquid used when filling a conductive material. On the other hand, if it is too much, there is a risk of causing shrinkage due to curing and deformation of the substrate.

  The polymer chain into which ion-exchange groups for filling or dissipating conductive materials, crosslinkable groups, and sensitizing groups are introduced has good solution applicability, resistance to acid and alkali, and wettability. It is preferable that it is excellent, has high adhesion to the substrate, and is excellent in heat resistance. From these viewpoints, preferred polymer chains include the following.

Novolac resins and derivatives thereof, polyacrylate esters and derivatives thereof, polystyrene derivatives, copolymers of styrene derivatives and maleimide derivatives, polynorbornene and derivatives thereof, polycyclohexene and derivatives thereof, polycyclohexane and derivatives thereof, polyphenylene and derivatives thereof, silicone Resins, polyamides, polyimides, polyarylates.
Of these, novolak resins such as phenol novolak and cresol novolak, silicone resins, and copolymers synthesized using the following monomers as raw materials are preferable.

  The molecular weight of the polymer into which the ion exchange group for filling the conductive material is generated or disappeared and the polymer introduced with the crosslinking group and the sensitizing group is not particularly limited, but the weight average molecular weight is preferably 500 to 5,000,000. It is more desirable to be 50,000. If it is too small, the film formability is poor, and the resistance to alkaline or acidic liquids used when metal ions, metal compounds or metal colloids are adsorbed or filled with a conductive material is also lowered. On the other hand, when the molecular weight is too large, solubility in a coating solvent is lowered and coating properties are also deteriorated.

  As the material for forming the photosensitive layer, a polymer containing at least a cation exchange group or an anion exchange group generated or disappeared by exposure is used. Among these ion exchange groups, the ion exchange group for filling the conductive material is an ion exchange group that is generated or disappears by exposure, and is opposite to the ion exchange group for filling the conductive material by a crosslinking reaction. Most preferred are those containing a cross-linking group that involves the formation of ion exchange groups. Preferred examples of the combination of the photosensitive layer and the photosensitive layer forming material include the following.

  For example, a naphthoquinone-1,2-diazido-4-sulfonic acid ester group, o-nitrobenzyloxycarbonylmethyl group or o-nitrobenzyl which generates a cation exchange group on the phenolic hydroxyl group of a phenol novolak resin or cresol novolak resin It is a combination of a polymer in which an oxycarbonylethyl group is introduced and a compound in which an azide group is introduced as a group that generates an anion exchange group.

  A polymer in which a carboxyl group is introduced as a cation exchange group into a phenolic hydroxyl group of a phenol novolak resin or a cresol novolak resin, and an azide group capable of forming an anion exchange group and capable of crosslinking is also preferably used. It is done.

  The photosensitive layer was formed on the inner surface of the pores of the porous substrate as well as those that selectively form ion exchange groups in the exposed or unexposed areas by changing the material forming the photosensitive layer. A method in which a photosensitive layer causes a chemical reaction with an insulating material constituting a porous substrate by exposure, and the insulating material constituting the porous substrate is changed to selectively form an ion exchange group in the exposed portion. It can also be formed of a photosensitive material acting in For example, when a porous substrate made of a hydrophobic fluororesin is used, a hydroxyl group or a carboxyl has a property of easily binding to a fluorine atom and has a function of trapping a fluorine atom released from the resin by exposure. You may form as a photosensitive layer with the compound which has ion exchange groups, such as a group and an amino group. In this case, ion exchange groups are introduced into the fluororesin, and this portion can be selectively filled with a conductive material by plating or the like.

  In the porous base material in which the photosensitive layer as described above is formed in the pores, at least one of the front surface and the back surface is filled with a filler to form a filling layer having a predetermined depth.

Filler is a material with a smaller absolute value of the difference in refractive index between the insulating material constituting the porous substrate and the absolute value of the difference in refractive index between the air and the insulating material constituting the porous substrate. Is used. Specifically, it is necessary to satisfy the relationship represented by the following mathematical formula (1).

(In the above formula (1), εA is the refractive index of the insulating material constituting the porous substrate, εB is the refractive index of the filler, and the refractive index of air is 1. )
The filler as described above is a material that can be impregnated and filled in the pores of the porous substrate, and does not hinder the reaction caused by the exposure of the photosensitive layer formed on the porous substrate, and is conductive after exposure. Any material that can be removed so as not to deteriorate the filling property of the conductive substance before the substance is filled can be used. Specifically, a polyether compound such as polyethylene glycol or a reactant-containing compound of a polyether compound and a polyisocyanate compound, polyvinyl alcohol, poly (acrylic acid-2-hydroxyethyl), poly (methacrylic acid-2-hydroxy) Examples thereof include polymers such as ethyl), poly (acrylic acid-polyethylene glycol), poly (methacrylic acid-polyethylene glycol), and propylene glycol alginate, and copolymers with the above-described water-soluble monomers.

  Moreover, in addition to the above-mentioned polymer, additives, such as a hygroscopic material, antiseptic | preservative, or an antifungal material, may be added to the filler. However, if the addition amount is too large, light scattering may occur due to the additive, or the exposure wavelength may be absorbed, and the transparency during exposure may be significantly reduced. In order to avoid remaining unremoved in the step of removing the filler and deteriorating the filling property of the conductive material, it is desirable that the amount of filler added be 50% by weight or less with respect to the polymer.

  Furthermore, a small amount of an alcohol solvent or a surfactant may be added for the purpose of adjusting the viscosity or improving the impregnation property into the porous substrate. Examples of the alcohol solvent include methanol, ethanol, propyl alcohol, ethylene glycol, diethylene glycol, and the like. As the surfactant, nonionic activity such as ethylene oxide 9-mol adduct of lauryl alcohol having good permeability is used. Agents and the like.

  As described above, the filler used in the embodiment of the present invention is an insulating material that constitutes the porous substrate as compared with the absolute value of the refractive index difference between air and the insulating material that constitutes the porous substrate. It is necessary that the absolute value of the difference in refractive index between and is small. This represents the following. Since the refractive index differs depending on the insulating material constituting the porous base material, the refractive index of the filler cannot be generally defined. However, the filler is a material that can be impregnated and filled in the pores of the porous substrate, and does not inhibit the reaction caused by exposure of the photosensitive layer formed on the porous substrate, and is filled with a conductive material after exposure. However, there is a limit to what can be used due to restrictions such as the ability to remove the conductive material without degrading the filling property before the process.

  In most cases, the refractive index of the filler is in the range of 1.4 to 1.6. For example, when filling a porous substrate composed of an insulating material having a refractive index greater than 1.6, the above-mentioned condition is inevitably satisfied, but the refractive index difference is 0.3 or more. The transparency is not sufficient. In addition, when using a porous substrate made of an insulating material having a refractive index close to 1.4 and having a refractive index smaller than that of the filler, the air and the insulating material constituting the porous substrate The condition regarding the refractive index difference that is smaller than the absolute value of the refractive index difference is satisfied, and the refractive index difference is less than 0.3, so that a composite member-forming base material with good transparency is obtained.

  Therefore, it is desirable to select an appropriate filler according to the refractive index of the insulating material that constitutes the porous substrate. For example, a porous base material made of ceramics having a refractive index of 1.7 usually contains air having a refractive index of about 1.0 in its pores. The pores are filled with polyethylene glycol having a refractive index of 1.5. As a result, a composite made by filling polyethylene glycol (PEG) as a filler with a refractive index difference of 0.2, which is smaller than that of air and polytetrafluoroethylene (PTFE), which is smaller than 0.2. A member forming substrate is formed. Further, the porous base material composed of PTFE having a refractive index of 1.36 usually contains air having a refractive index of about 1.0 in its pores. The pores are filled with polyethylene glycol having a refractive index of 1.5. In this case, a composite member forming base material is formed by filling PEG as a filler with a refractive index difference of 0.14 smaller than that of PTFE, which is smaller than that of air and PTFE of 0.36. be able to.

  Since the porous substrate is filled with a specific filler at a predetermined depth, the composite member-forming substrate obtained in any combination should sufficiently prevent light scattering during exposure. Can do.

  The filler can be heated and melted and applied directly to the porous substrate, or the filler may be softened by laminating and filled inside the porous substrate. Alternatively, it can be used by applying a solution in which the filler is dissolved in a solvent such as water or an organic solvent. When used as a solution, the filler is preferably 5% by weight or more in consideration of drying property, workability, and transparency. Furthermore, the filling method is not particularly limited, for example, a method using an apparatus such as a bar coater, a method using a roller, a brush, or the like, application by spraying, a dipping method, a vacuum impregnation method and the like.

  For example, when PTFE (polytetrafluoroethylene) having a photosensitive layer formed thereon is used as the porous substrate and a polyvinyl alcohol (PVA) sheet is used as the filler, the filling layer is formed as follows. be able to. First, a PVA sheet is placed on PTFE on which a photosensitive layer is formed, and a layer in which the PVA sheet is filled on the inner surface of the PTFE hole by lamination is formed.

  When formed in this manner, a composite member-forming substrate having a porous substrate and a non-filled layer (scattering layer) that is not filled with a filler is obtained. Light scattering is reduced by the filled layer filled with the filler, and exposure light can be scattered by the layer not filled with the filler to reduce the intensity.

  The surface of the porous substrate on which the filling layer is formed may be covered with a protective film. The protective film can be formed of, for example, polyester, polyolefin, acrylic, etc., and the thickness can be about 1 to 100 μm. In addition, when the filling layer is formed on both the front surface and the back surface of the porous substrate, when the resin as described above is used, the filling layer expands and contracts by heating. Therefore, when heat laminating and the porous material is filled with the filler expanded, the filler shrinks during cooling, and the substrate may be warped. Such deformation of the base material can be reduced by forming symmetrically on both sides as well as on one side. However, in the composite member to be manufactured, if the region requiring a fine pattern is sufficiently small, for example, 10% or less of the total area, only the necessary portion or only one side of the porous substrate is filled. It is advantageous to provide a layer because it is simple, inexpensive and advantageous. This also applies when warping concerns as described above are almost ignored.

  In the embodiment of the present invention, the filling depth of the filler into the porous substrate is defined to be 40% or less of the total thickness of the porous substrate. If this depth is exceeded, the light transmittance increases, and it becomes easier for light to be transmitted to the back surface during pattern exposure, resulting in inconvenience that wiring is formed through the inside of the porous substrate to the back surface. . In particular, when wiring is formed on both surfaces of the porous substrate, there is a disadvantage that the wirings are connected to each other inside the porous material and short-circuited. Even when wiring is formed only on one side of the porous substrate, the wiring formed inside the porous substrate is a composite with an insulating material that forms the substrate, so that the porous substrate surface The resistance value is higher than that of a wiring made of only a conductive material. Therefore, the thinner the wiring formed inside the porous base material is, the more advantageous for lowering the resistance. Therefore, the filling depth is limited to 40% or less of the total thickness of the base material.

  Alternatively, the maximum depth of the packed bed is 15 μm. Since the thickness of the porous base material used in the embodiment of the present invention is usually about 500 μm at the maximum, it is included within the above-mentioned 15 μm. This was confirmed from the result of the simulation using the light absorption / scattering model in the porous body. Specifically, in a base material filled with PFE (polyvinyl alcohol) in PTFE (polytetrafluoroethylene), it was confirmed that light scattering was sufficiently reduced by providing a filling layer having a thickness of 15 μm. Yes.

  In addition, when forming the filling layer on both sides of the front and back surfaces of the porous substrate, the total thickness (filling depth) of the filling layer provided on both sides is the total thickness of the porous substrate. It is desired to be 80% or less. In this case, the depth of each filling layer is preferably 15 μm at the maximum. In the base material for forming a composite member according to the embodiment of the present invention, a layer having no filler (scattering layer) must be present inside the base material. In particular, the thickness of the scattering layer may be at least 20% or more of the entire porous substrate, considering the short circuit of the wiring formed on the front and back surfaces described above, the reduction of the resistance value of each wiring, and the like. desired.

  The composite member forming base material is formed into a composite member by performing pattern exposure on a predetermined region and then filling a conductive material to form a conductive portion such as a wiring. In most cases, the wiring formed in this way is composed of a part of a composite of an insulating substance and a conductive substance constituting a porous substrate inside the porous body, and a single conductive substance formed on the surface layer. It consists of the part which becomes. About the site | part formed in a porous base material, since it becomes a composite_body | complex of the insulating substance and electroconductive substance which comprise a porous base material, compared with the electroconductive substance single-piece | unit, resistance value becomes high. Therefore, even if the wiring part formed inside the porous substrate is formed deeply, the effect of dramatically reducing the resistance value of the wiring itself can hardly be expected. The depth that can maintain the adhesion to the wiring portion formed on the surface layer, that is, at least 1 μm is necessary. In order to ensure a filling depth of at least 1 μm or more, for example, the following control may be performed to fill the filler. In the case of filling by lamination, the filling layer can be formed with a depth of 1 μm or more by controlling the thickness of the filler, the lamination temperature, the number of times of lamination, or the like.

  The base material for forming a composite member may not be one in which at least one whole surface of the front surface and the back surface is filled with the filler. That is, among the areas of the composite member forming base material, there is no filler in some areas where it is not necessary to prevent the exposure light from being scattered, and some areas where it is necessary to prevent the exposure light from being scattered. It may be filled with a filler. Further, the composite member forming base material is not limited to a material in which the pores 2 of the porous base material are completely filled with the filler in a volume fraction of 100%, but at least a volume fraction of 50% or more, preferably The volume fraction may be 80% or more filled with a filler.

  The filling rate of the filler can be calculated as follows. First, from the density of the filler, the weight of the porous substrate after filling the filler (measured value), and the weight of the porous substrate before filling the filler (measured value) as follows, The volume of the filler filled in the pores of the porous substrate is calculated.

Volume of filler filled in pores of porous substrate = {(total weight of porous substrate after filling with filler) − (weight of porous substrate before filling with filler)} ÷ filler When the obtained value is divided by the total volume of the porous substrate and calculated as follows, the filling rate (%) at the volume fraction of the filler is obtained.

Filling rate of filler (%) = {(volume of filler filled in pores of porous substrate) / (total volume of pores)} × 100
Here, a method of filling the filler on both surfaces of the porous substrate by lamination will be described. As shown in FIG. 2, the filler sheet 13 is disposed on both surfaces of the porous substrate 10. In the pores of the porous substrate 10, the photosensitive layer 12 as described above is formed. The filler sheet 13 has a smaller absolute value of the refractive index difference between the air and the insulating material constituting the porous base material than the insulating material constituting the porous base material. Consists of fillers. For example, such a filler is heated and melted, and the filler sheet 13 is produced by a bar coater method. Alternatively, a commercially available filler sheet may be used. Specific examples include Kuraray Co., Ltd. and Claria 112. The thickness of the filler sheet 13 is preferably in the range of 1 to 100 μm. When the thickness is less than 1 μm, it is difficult to form a filling layer having a depth of 1 μm or more. On the other hand, when the thickness exceeds 100 μm, there is a possibility that the unfilled layer remains on the surface and the distance between the mask on which the pattern is drawn and the substrate is widened, and the pattern is widened due to the influence of diffraction.

  The filler sheet 13 is disposed on both surfaces of the porous substrate 10 and is filled in the porous substrate by heating and pressing. The heating temperature is limited to a temperature that does not cause deformation of the porous substrate. Moreover, it is necessary to avoid as much as possible that the photosensitive layer in the porous substrate reacts or decomposes due to heating. For example, when the porous substrate is made of PTFE and a photosensitive layer made of naphthoquinonediazide is formed inside, the upper limit of the heating temperature is about 120 ° C. On the other hand, when the heating temperature is too low, the filler softens and fills the pores of the porous substrate. However, since this softening and filling tends to be insufficient, the filler is added to the porous substrate. It becomes difficult to fill. It is desirable to heat to at least 80 ° C. or higher. Moreover, it is preferable that a pressure shall be in the range of 0-20 kg / cm. Heating and pressurization under such conditions can be performed using an apparatus such as a laminator.

  Although depending on the characteristics of the filler used (softening temperature, etc.), the thickness of the filler layer filled with the filler can be controlled mainly by the lamination temperature and speed. Specifically, the laminating speed can be controlled by changing the rotational speed of the roller of the apparatus.

  The filler is filled in the pores of the substrate by being softened and crushed by the laminate. Since the reaction has not occurred and is not in a bonded state, the filler can be easily removed after exposure.

  By filling the porous base material with the filler as described above, the composite member forming base is excellent in light scattering suppression effect of exposure light, has no surface stickiness, and can be removed after exposure. You can get the material.

  In the base material for forming a composite member according to the embodiment of the present invention, a filling layer is formed at a predetermined depth on the exposed surface. Since this filling layer contains a filler having a predetermined refractive index, light scattering during exposure can be reduced. Moreover, it can be said that there is a layer that does not contain a filler in the inner region of such a packed layer, and air is filled in the pores of the inner layer. The refractive index of air is about 1, and the refractive index of the insulating material forming the porous substrate is about 1.4 to 1.6. Since the refractive index difference between air and the insulating material is large, this layer acts as a scattering layer in which light scattering occurs. Due to the presence of the scattering layer inside the filling layer, the light intensity decreases, and as a result, the filling layer improves the ratio of the non-scattering component of the exposure light, so that it extends laterally beyond the mask pattern. Reduces exposure to fat. In addition, since the exposure light is scattered by the scattering layer and the intensity is reduced, an effect of reducing the exposure intensity in the depth direction can be obtained.

  The obtained composite member-forming substrate is shown in FIG. As shown in the figure, the composite member forming base material 15 according to the embodiment of the present invention has three-dimensionally formed continuous pores, and the inside of the pores 11 of the porous substrate 10 made of an insulating material. A photosensitive layer 12 is formed on the surface. Furthermore, the filler 13 has a smaller absolute value of the refractive index difference between the insulating material constituting the porous base material and the absolute value of the refractive index difference between the air and the insulating material constituting the porous base material. There is a filled layer 14 that is filled at a depth of 40% or less of the total thickness of the porous substrate 11.

  In the composite member forming base material according to the embodiment of the present invention, a filling layer may be formed only on one of the front surface and the back surface. In this case, as shown in FIG. 4, the filler sheet 13 as described above is disposed on one side of the porous substrate 10, and heating and pressurization are performed for lamination. It is desirable that the other surface of the porous substrate is supported by a film such as PET, for example, to avoid deformation and the like. As a result, a composite member forming base material in which a filling layer is formed only on one side as shown in FIG. 5 is obtained.

  As shown in FIG. 3, the exposed portion of the photosensitive layer is selectively activated by irradiating light onto a predetermined region of the composite member forming base material 15 on which the filling layer 14 is formed on both sides. . For example, as shown in FIG. 6, the composite member forming base material 15 is irradiated with ultraviolet rays 17 through an exposure mask 16. In the composite member forming base material 15, 15 a is a region to be filled with a conductive material, and the exposure mask 5 has an opening 16 a corresponding to the region 15 a. A non-opening portion 16 b is formed in the exposure mask 16 corresponding to the insulating region 15 b of the composite member forming base material 15.

  By performing the exposure, a group that generates or disappears an ion exchange group for filling the conductive material, a crosslinking group, and a sensitizing group are activated in the photosensitive layer of the exposed portion. Alternatively, plating nuclei that are reaction start points of electroless plating are formed in the exposed portion. The exposure light source is not particularly limited to ultraviolet light, visible light, infrared light, and the like, but it is easy to perform pattern exposure that selectively exposes a desired region of the composite member forming substrate at a low cost. UV and visible light are excellent.

  Pattern exposure can be performed through an exposure mask 16 having a predetermined pattern as shown in FIG. 6 or by scanning a beam such as a laser beam. Alternatively, pattern exposure may be performed using a laser diode array. Furthermore, the light from the light source can be exposed by being modulated by a micromirror array. A micromirror array is a light modulation device in which a number of micromirrors, which are minute mirrors, are arranged in a matrix. For example, tens of thousands to millions of square micromirrors each having a side of about 5 μm to 20 μm are arranged in a matrix. The angles of the individual micromirrors can be independently modulated, and the reflection angle of the exposure light incident from the light source can be individually changed. For this reason, one mirror becomes one pixel, and the angle of each mirror is modulated in accordance with the pattern of wiring or via to be exposed to form an exposure pattern. It is possible to expose the pattern of wiring or via on the porous substrate without mask. An example of the micromirror array is a digital micromirror device manufactured by Texas Instruments, Inc., Dallas, Texas, USA.

  The porous substrate can be exposed so that all the two-dimensional patterns of wiring and vias penetrate the porous substrate in the thickness direction. Further, the inside of the porous substrate may be exposed three-dimensionally.

  The method for three-dimensional exposure is not particularly limited. For example, the focal point where the laser beam is condensed can be scanned three-dimensionally within the porous substrate. Alternatively, even when exposure is performed using a two-dimensional pattern exposure mask, three-dimensional exposure is possible by adjusting the exposure amount or selecting an exposure wavelength. For example, if the via portion is exposed through the thickness direction and the wiring portion is exposed only near the surface, both the wiring and the via connecting the wiring to the electrode of the electronic device are connected to a single porous substrate. Can be made into wood. For example, in order to adjust the exposure amount, a mask such as a halftone mask in which the transmittance is adjusted between the via portion and the wiring portion can be used.

  After the pattern exposure, the exposure mask 16 is removed as shown in FIG. 7, and the filler is removed from the pores of the porous substrate 11. For example, the filler can be removed by peeling off from the end face or by leaving the substrate in a warm water of about 40 ° C. and washing it to remove the filler. Alternatively, the filler may be removed by washing with a suitable cleaning agent. As the cleaning liquid, water or a solution containing water is used, and the solution containing water may be either an acidic solution or an alkaline solution. Specifically, examples of the solution containing water include an aqueous sodium hydroxide solution and an aqueous sodium carbonate solution adjusted to have a pH of 9 to 13.

  Even when the filler is removed by peeling, it is desired that the filler residue be reliably removed by washing with a cleaning agent. Here, an acidic solution is a solution having a pH <7, and an alkaline solution is a solution having a pH> 7.

  Cleaning can be performed by immersing the composite member-forming substrate after exposure in a predetermined cleaning solution for 10 seconds to 5 hours. From the viewpoint of the removal rate of the filler and the process cost, the cleaning time is more preferably in the range of 1 minute to 1 hour. The filler removal rate is expressed by the following formula.

Removal rate (%) = (weight of porous substrate filled with filler−weight of porous substrate after removing filler by washing) × 100
The cleaning agent as described above may be replaced with a solution that is convenient in terms of permeability and reactivity in terms of process, such as water or another solution, until the subsequent conductive material filling step.

  After that, as shown in FIG. 8, a plating nucleus such as a metal ion, a metal compound, or a metal colloid, preferably a metal cation is formed on the ion exchange group generated in the light absorbing portion 15a on the inner surface of the pore 12 of the porous substrate 11 Then, a plating nucleus such as a metal compound cation or a positively charged metal colloid is adsorbed, and electroless plating is performed. As a result, the light absorbing portion 15 a selectively formed on the composite member forming substrate 5 is filled with the conductive material 19.

  It should be noted that the photosensitive layer formed on the inner surface of the porous substrate pores undergoes a chemical reaction with the insulating material constituting the porous substrate by exposure, and the insulating material constituting the porous substrate changes to expose. In the case where the photosensitive layer is formed of a photosensitive material that selectively forms ion exchange groups on the part, the ion exchange groups are introduced into the fluororesin, and the conductive material is selectively applied to the part by plating or the like. It becomes possible to fill.

  In addition, a plating nucleus that is the reaction starting point of electroless plating is formed by exposure on a material composed of a photosensitive reducing agent, a metal salt, etc., and electroless plating is applied as described above to fill the conductive material. May be.

  Conductive substances include metals such as gold, silver, palladium, copper, nickel, chromium, cobalt and tin, alloys such as copper-nickel, nickel-cobalt and tin-nickel, or substituted and unsubstituted conductive polyaniline and polyparaffin. Conductive polymers such as phenylene, polyparaphenylene vinylene, polythiophene, polyfuran, polypyrrole, polyselenophene, polyisothianaphthene, polyphenylene sulfide, polyacetylene, polypyridyl vinylene, and polyazine. These may be used alone or in combination of two or more.

  Further, a polymer having no electrical conductivity can be added, and these may be used as a monomer or a copolymer. By selecting the conductive polymer and the ion exchange group formed by exposure of the photosensitive layer formed on the inner surface of the porous substrate so that they adsorb in the relationship of cation and anion, Conductive polymers can be adsorbed as counter ions. For example, when carboxylic acid is selected as the ion exchange group and thiophene is selected as the conductive polymer, polythiophene having a carboxyl group as the counter anion is formed.

  In order to adsorb metal ions and metal colloids to the ion exchange group, the composite member forming substrate on which the ion exchange groups are formed may be brought into contact with the metal ion solution or the metal colloid solution. For contact, it is most preferable to immerse the composite member-forming substrate, but it can also be applied by spraying the solution onto the substrate. As the metal ion solution, an aqueous solution of an organic salt or an inorganic salt such as gold, silver, platinum, palladium, copper, or an alcohol solution that is used as a catalyst for electroless plating by reduction or the like is used. Metal ions are adsorbed on the ion exchange groups as counter ions. The adsorbed metal ion is used as a catalyst for electroless plating as it is or by reduction and metallization. Metal ions having a smaller ionization tendency than the metal to be plated are reduced by the ions of the plating metal in the plating solution without being reduced. For example, in the case of copper plating, ions such as gold, platinum and palladium can be used as they are. Copper ions are reduced to copper fine particles and used as a catalyst for electroless plating. As the reducing agent, known reducing agents such as formaldehyde, sodium borohydride, dimethylamine borane, trimethylamine borane, hydrazine, hypophosphites such as sodium hypophosphite, and the like can be used.

  The reducing agent is reduced as a solution such as an aqueous solution by immersing the substrate in the solution. Prior to the reduction, it is preferable to remove excess metal ions by washing the substrate with water or the like.

  As the metal colloid solution, an aqueous solution of a colloid such as gold, silver, platinum or palladium, or a solution of an organic solvent such as alcohol is used. The metal colloid is preferably a protective colloid protected by a protective substance such as a surfactant or a polymer from the viewpoint of storage stability of the metal colloid solution. In many cases, the metal colloid is positively or negatively charged, and the charged polarity can be changed by a protective substance. In many cases, ion exchange groups are charged in a liquid. Metal colloids are adsorbed by electrostatic attraction with ion exchange groups. The metal colloid does not need to be reduced and can be used as a catalyst for electroless plating as it is. In the case of a protective colloid, the activity as a catalyst is improved by removing the protective substance by etching using an acid, alkali solution, oxidant solution, or the like.

  The concentration of the metal ion solution or metal colloid solution is preferably 0.1 to 30% by weight, and more desirably 1 to 15% by weight. If the concentration is too small, it becomes difficult to adsorb a sufficient amount of metal ions and colloids to the ion exchange group, and the adsorption rate is slow and a long time is required for the adsorption. On the other hand, if the concentration is too high, metal ions and colloids may be adsorbed randomly in addition to the target ion exchange group, and it becomes difficult to form a good composite member. The time for contacting the solution and the composite member forming base material by immersing the base material in a metal ion solution or a metal colloid solution is not particularly limited, but is generally between 10 seconds and 5 hours. . Copper ions are particularly preferable because they have good selectivity and are less likely to adsorb in a random manner other than the region where ion exchange groups exist compared to other metal ions.

  After the composite member-forming substrate is brought into contact with the metal ion solution or the metal colloid solution, it is desirable to remove excess metal ions or metal colloids by washing. Specifically, by washing with metal ions such as water or the same solvent as the solvent of the colloidal solution, the solution adhering to a region other than the region where the ion exchange group to be filled with the conductive material is removed is removed. Accordingly, it is possible to prevent the plating from being randomly performed in a region other than the region where the ion exchange group to be filled with the conductive material is present.

  Hereinafter, the present invention will be described in more detail with reference to specific examples.

Example 1
Using a PTFE porous substrate (Sumitomo Electric Co., Ltd., average pore diameter 0.1 μm, film thickness 50 μm) as the porous substrate, a composite member was produced by the following method. The refractive index of this porous substrate is 1.38.

  First, about 20% by weight of diazide chalcone is added to a 2 mmol% THF solution of a naphthoquinone diazide-containing phenol resin (naphthoquinone diazide content; 46 equivalents mol%) with respect to the naphthoquinone diazide-containing phenol resin, and the photosensitive layer. The material was prepared. This photosensitive layer material was coated on the inner surface of the pores of the porous substrate by a dip method to form a photosensitive layer.

  After drying for 30 minutes at room temperature, the porous inner surface was coated with a naphthoquinonediazide-containing phenol resin and diazide chalcone, and two porous substrates on which a photosensitive layer was formed were prepared. One porous substrate was exposed as it was to obtain a porous substrate (A) of a comparative example.

  The other porous substrate was filled with a filler by the following method to form a packed layer, and a composite member-forming substrate (B) of this example was obtained.

  As a filler, PVA (Kuraray Co., Ltd., Claria 112, 35 μm thickness) was prepared. The refractive index of this filler is 1.49. The filler was passed three times through a laminator (Fujitec Co., Ltd., Fuji LAMIPACKER LPD 3206City) at 100 ° C. and 0.3 m / min. Specifically, the above-described filler PVA was placed on both the front and back surfaces of the porous substrate, and the PVA surface was covered with a PTFE film and passed through a laminator. Thus, on the front and back surfaces of the porous base material, a porous material (filling layer is formed by filling with a filler, and a layer (scattering layer) not filled with the filler is left inside the base material ( B) was obtained.

  The thickness before and after lamination was measured, the thickness change before and after lamination of the porous substrate and the PVA sheet was removed, and the penetration depth of the PVA sheet into the porous substrate was calculated. As a result, a packed layer having a thickness of 5 μm is formed on the front and back surfaces of the porous substrate (B), and a scattering layer is sandwiched between the packed layers at a thickness of 40 μm. It was confirmed.

  The exposure was performed by CANON PLA 501 using two masks in which conductive patterns (width 10 μm, length 2 cm) were arranged at a pitch of 30 μm. One mask was placed on one side of the porous substrate (A), and another mask was placed on the other side so that the pattern directions were orthogonal. In this way, the porous substrate is sandwiched between the two masks, and the latent image is exposed on the front and back surfaces under the condition of a light amount of 500 mJ (made by USHIO, UIT-100, 405P detector). Formed. Similarly, pattern exposure was performed on both surfaces of the porous substrate (B).

  The base material (B) was washed with water for 10 minutes to remove the filler filled in the pores of the composite member forming base material. A part of the base material (B) after removing the filler was cut out and dried, and then SEM observation was performed. As a result, it was confirmed that the structure was the same as before the formation of the filler, and that the filler was removed cleanly from the pores of the composite member forming base material.

  The substrate (A) on which the pattern latent image was formed and the substrate (B) washed with water were each dipped in a 0.01 M aqueous solution of sodium borohydride for 10 minutes to be wetted. Thereafter, washing with distilled water was repeated three times. Washing was performed by leaving the substrate in still water for about 5 minutes. Furthermore, after being immersed in an aqueous copper acetate solution adjusted to 0.5 M for 10 minutes to adsorb copper ions, washing with distilled water was repeated three times. Subsequently, it was immersed in a 0.01 M aqueous solution of sodium borohydride for 10 minutes and then washed with distilled water. Then, it was immersed in the electroless copper plating solution PB-503 for 60 minutes, and the copper plating was performed to the site | part in which the pattern latent image was formed.

  When observed with a microscope, in the base material (B), conductive portions of lines having a width of 15 μm, a length of 2 cm, and a pitch of 30 μm were formed on the front surface and the back surface to constitute a composite member. On the other hand, in the base material (A), adjacent lines are connected and short-circuited, and a 30 μm pitch line could not be formed on either the front surface or the back surface.

  This line was embedded with an epoxy resin (Sankei Co., Ltd., EPO-KWICK RESIN), cut out and ground to obtain a cross section, and the cross section was observed with an optical microscope. For both of the base materials (A) and (B), the depth of penetration of the conductive portions on the front and back surfaces is about 10% of the base material, and the line of the base material (B) is the conductive portion on the front and back surfaces. Insulation was maintained without being connected.

(Example 2)
A plurality of similar porous substrates on which the same photosensitive layer as in Example 1 was formed were prepared. Filling material was filled under various conditions to form a filling layer and a scattering layer, and a composite member forming substrate of this example was produced. In filling, the number of times of lamination and the temperature were changed. Further, pattern exposure and conductive material filling were performed under the same conditions as in Example 1 to manufacture a composite member, and the state of the line was observed. The results are summarized in Tables 1 and 2 below together with the filling conditions and the thickness of each layer.

For comparison, the substrate (A) having no filling layer was similarly subjected to pattern exposure and filling with a conductive material to try to form a line. The results are also shown in Tables 1 and 2 below.

  As shown in the above table, only for the base material (B), a composite member in which conductive parts of lines having a length of 2 cm and a pitch of 30 μm were formed on the front surface and the back surface was obtained. On the other hand, in (A), adjacent lines were connected and short-circuited, and a 30 μm pitch line could not be formed on either the front surface or the back surface.

  The line was embedded with an epoxy resin (Sankei Co., Ltd., EPO-KWICK RESIN), cut and polished to obtain a cross section, and the cross section was observed with an optical microscope. As a result, for both the base materials (A) and (B), the penetration depth of the conductive portions on the front and back surfaces is about 10% of the base material, and the line of the base material (B) is on the front and back surfaces. Insulating property was maintained without connecting the conductive parts.

  In addition, as Table 2 shows, when the temperature at the time of filling a filler is 70 degreeC, a filled layer cannot be formed on both surfaces of a porous base material. In this example, the material of the porous base material is PTFE, a photosensitive layer is formed on the inner surface of the pores of the porous base material, and the material of the filler is PVA. Heating temperatures to the extent are acceptable. Considering the heat resistance of these materials and the filling property of the filler into the porous substrate, the substrate for forming a composite member according to the embodiment of the present invention is manufactured by filling the filler with a predetermined depth. It is required to perform heating at 80 ° C. or more at least.

(Example 3)
A plurality of porous base materials on which the same photosensitive layer as in Example 1 was formed were prepared and filled with a filler to prepare a composite member forming base material of this example.

  As a filler, polyethylene glycol (PEG) (Kanto Chemical Co., Inc., weight average molecular weight 1500) was prepared. The refractive index of this filler is 1.46. 2 g of the filler was heated and melted, and a 20 μm thick filler sheet was produced with a bar coater. This filler sheet was passed through a laminator three times at 100 ° C. and 0.3 m / min. Specifically, the above-described filler PEG was placed on both the front and back surfaces of the porous substrate, the PEG surface was covered with a PTFE film, and passed through a laminator. In this way, the porous substrate is filled with a filler to form a packed layer on the front surface and back surface, and a porous layer in which a filler is not filled (scattering layer) is left inside the substrate. Substrate B was obtained.

  Each thickness before and after lamination was measured, thickness changes before and after lamination of the porous substrate and the PEG sheet were removed, and the depth of penetration of the PEG sheet into the porous substrate was calculated. As a result, a packed layer having a thickness of 8 μm is formed on the front and back surfaces of the porous substrate (B), and a scattering layer is sandwiched between these packed layers at a thickness of 42 μm. It was confirmed.

  Next, pattern exposure is performed under the same conditions as in Example 1 to form latent images on the front and back surfaces of the porous substrate (B), and then washed with water for 10 minutes to fill the pores. The material was removed. A part of the base material (B) after removing the filler was cut out and dried, and then SEM observation was performed. As a result, it was confirmed that the structure was the same as that before the filler was formed, and that the filler was removed cleanly from the pores of the composite member forming base material.

  The part where the pattern latent image of the base material (B) washed with water was formed was subjected to copper plating in the same manner as in Example 1. When the cross section was observed, the penetration depth of the conductive parts on the front and back surfaces was about 15% of the total thickness of the base material, and the lines were kept insulating without connecting the conductive parts on the front and back surfaces. It was. Thus, a composite member was obtained in which conductive portions of lines having a width of 15 μm, a length of 2 cm, and a pitch of 30 μm were formed on the front surface and the back surface.

(Example 4)
As the porous base material, the same PTFE porous base material and polyimide base material (Ube Industries, Upilex) as in Example 1 were prepared, and as the filler, the same PVA and the same as in Example 1 were carried out. The same PEG as in Example 3 was prepared. By combining these, the surface or one surface of the porous substrate was filled with a filler, and the composite member forming substrate of this example was produced. Note that the photosensitive layer as described above is formed on any porous substrate.

  The filler was filled into the porous substrate basically by the same method as in Example 1. That is, laminating was performed by passing a laminator three times at 100 ° C. and 0.3 m / min. When filling both surfaces of the porous substrate, the same method as in Example 1 was used. When filling only one surface, the other surface was supported by a PET film to prepare a substrate (C). Further, pattern exposure and conductive material filling were performed under the same conditions as in Example 1 to manufacture a composite member, and the state of the line was observed. The results are summarized in Tables 3 and 4 below, along with the types of porous substrate and filler used.

For comparison, the substrate (A) having no filling layer was similarly subjected to pattern exposure and filling with a conductive material to try to form a line. The results are also shown in Tables 3 and 4 below.

  As shown in the above table, with respect to the base material (B), a composite member in which conductive parts of lines having a length of 2 cm and a pitch of 30 μm were formed on the front surface and the back surface was obtained. Moreover, about the base material (C), the composite member in which the electroconductive part of the line of length 2cm and a 30 micrometer pitch was formed in one surface was obtained.

  About these base materials (B) and (C), when the cross section was observed by SEM after pattern exposure and before filling the conductive material, the structure was the same as that before the filler formation, and the pores of the base material for composite member formation It was confirmed that the filler was removed cleanly from the inside.

  On the other hand, in (A), adjacent lines were connected and short-circuited, and a 30 μm pitch line could not be formed on either the front surface or the back surface. In addition, this line was embedded with an epoxy resin (Sankei Co., Ltd., EPO-KWICK RESIN), cut out and ground to obtain a cross section, and then observed with an optical microscope to obtain a substrate (A). In both cases, the penetration depth of the conductive parts on the front and back surfaces is about 10% of the base material, and the line of the base material (B) is insulated without connecting the conductive parts on the front and back surfaces. Sex was maintained.

Process sectional drawing which shows the manufacturing method of the composite member concerning one Embodiment of this invention. Sectional drawing showing the process of following FIG. Sectional drawing showing the process of following FIG. Process sectional drawing which shows the manufacturing method of the composite member concerning other embodiment of this invention. Sectional drawing showing the process of following FIG. Sectional drawing showing the process of following FIG. Sectional drawing showing the process of following FIG. Sectional drawing showing the process of following FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Porous base material; 11 ... Porous; 12 ... Photosensitive layer; 13 ... Filler sheet 14 ... Filling layer; 15 ... Base material for composite member formation; 15a ... Light absorption part 15b ... Insulating region; 16a ... Opening part; 16b ... Non-opening part 17 ... Exposure light; 18 ... Base material for forming a composite member from which filler is removed; 19 ... Conductive substance.

Claims (1)

Three-dimensionally formed continuous pores, a photosensitive layer is formed in the pores of the porous substrate made of an insulating material, and a filler is formed from at least one of the front and back surfaces of the porous substrate. And at least one of the front and back surfaces is filled with a filled layer at a depth of 40% or less, 15 μm or less, and 1 μm or more of the total thickness of the porous substrate. Forming a composite member-forming substrate by forming;
From the side having the filling layer of the composite member forming substrate, pattern exposure to a predetermined region,
Removing the filler from the composite member-forming substrate after pattern exposure;
A step of selectively filling a conductive material into an exposed part or an unexposed part of the composite member forming base material from which the filler has been removed,
The method for producing a composite member, wherein the filler satisfies a condition represented by the following mathematical formula.

(In the above formula (1), εA is the refractive index of the insulating material constituting the porous substrate, εB is the refractive index of the filler, and the refractive index of air is 1. )

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