JP6860024B2 - Manufacturing method of stacked antenna and stacked antenna - Google Patents

Description

The present invention relates to a laminated antenna obtained by laminating a wiring pattern formed of a plurality of conductive pastes on both sides of an insulating substrate with an insulating coat layer interposed therebetween.

In recent years, with the development of wireless communication technology, there is an increasing demand for thin antenna parts incorporated in wireless communication IC cards and the like.

Generally, these antennas are manufactured by a subtractive method in which a copper foil bonded to an insulating substrate is patterned using a photoresist and an etchant, but the process is long and complicated, and a large amount of waste is generated.

In addition, in electromagnetic induction type and electromagnetic transfer type antennas, multiple antenna patterns are arranged orthogonally to detect the position, so multiple antennas can be installed at low cost, in a simple, short, and waste-free process. A stackable antenna is desired.

In addition, IC cards for wireless communication interfere with each other when two cards are stacked, and a reading error occurs. Therefore, to use them while stacking them, purchase an "error prevention sheet" or "IC card separator" separately. However, it is known that it is necessary to use it by sandwiching it between two IC cards.

Further, IC cards often have an antenna pattern formed on a PET film or the like, and these cannot be used in a metal environment. Therefore, as an IC card that can be used in a metal environment, magnetic as in Patent Document 1. The one that is laminated with the body is used. However, such a manufacturing method has a drawback that it requires a long process. Then, in order to bring the surface of the antenna pattern conductor and the magnetic material as close as possible, it is required to make the above-mentioned carrier base material thin, but the thin carrier base material has a drawback of lowering the process passability.

Further, regarding the improvement of communication characteristics, a technique for lengthening the communication distance is known due to the effect of installing a booster coil separately from the antenna for driving the IC chip as in Patent Document 2 to improve the directivity. However, it has been insufficient to study industrially inexpensive materials and a manufacturing method with a small number of man-hours for manufacturing a thin antenna having a booster coil in which a plurality of antennas need to be arranged.

Patent Document 3 discloses a printed circuit board in which a conductor material is pattern-printed on a substrate, an insulating material is pattern-printed on the conductor material, and this process is repeated as necessary. However, in order to form an insulating layer having sufficient insulating properties by pattern printing, there are problems such as thickening the layer and using an expensive resin.

For example, as an insulating material, Patent Document 4 discloses a thermosetting resin composition of a polyurethane resin and an epoxy resin having a carboxylic acid group in a side chain. Patent Document 5 discloses an impact-resistant insulating composition in which rubber fine particles or an epoxy resin in which rubber fine particles are dispersed are dispersed in an epoxy curing system. Patent Document 6 discloses an application of an acid-modified polyester resin and an epoxy resin to an adhesive for a circuit board.

However, further improvement in the mechanical properties of the insulating layer between layers, which is required when forming a multi-layer laminated structure, is desired and is still insufficient.

Japanese Unexamined Patent Publication No. 2015-117174 Japanese Unexamined Patent Publication No. 2000-138621 Japanese Unexamined Patent Publication No. 10-112586 Japanese Unexamined Patent Publication No. 2006-274258 Japanese Unexamined Patent Publication No. 9-40751 Japanese Unexamined Patent Publication No. 2006-137793

The present invention is a laminated antenna in which wiring patterns are provided on both sides of an insulating substrate. A laminated antenna that exhibits high inductance by using an inexpensive material and is miniaturized and has high performance by stacking a plurality of layers of wiring patterns. The purpose is to provide.

Another object of the present invention is to provide a method for manufacturing the laminated antenna at low cost with less man-hours than the conventional manufacturing method.

The present inventor has completed the present invention as a result of diligent studies to solve the above problems. That is, the present invention is as follows.

In the present invention, a plurality of wiring patterns formed of conductive paste are laminated on both sides of an insulating substrate with an insulating coat layer having through holes interposed therebetween, and the wiring patterns are connected via the through holes. The insulating coat layer is a through-hole antenna characterized by being a cured product of a resin containing the following (A) to (E).
(A) Polyester resin (B) Plate-like inorganic filler (C) Fused silica (D) Rubber phase (E) Epoxy resin

Further, in the laminated antenna of the present invention, the acid value of the polyester resin used is preferably 800 to 2500 equivalents per ton of resin.

Further, in the laminated antenna of the present invention, the conductive paste preferably used contains conductive particles, a binder resin and a solvent, and the conductive particles contain copper or copper as a main component.

Further, in the laminated antenna of the present invention, the wiring pattern is preferably a plane spiral coil pattern, and the coil patterns are connected via through holes to form an antenna coil.

Further, in the laminated antenna of the present invention, the insulating substrate is preferably a magnetic material.

Further, in the laminated antenna of the present invention, the insulating substrate is preferably a resin film.

Further, in the laminated antenna of the present invention, a wiring pattern is preferably formed on an insulating substrate via an adhesive layer.

Further, in the laminated antenna of the present invention, the weight loss by heating after curing of the adhesive layer is preferably 25% by weight or less in 10 minutes under a superheated steam atmosphere at 300 ° C.

Further, in the laminated antenna of the present invention, a through hole is preferably formed in the insulating substrate, and the wiring pattern formed on one surface of the insulating substrate and the wiring pattern formed on the other surface are connected via the through hole. Has been done.

In the present invention, a wiring pattern is formed by printing a conductive paste on an insulating substrate, and insulation having an opening that becomes a through hole on the wiring pattern by printing an insulating coating agent containing the following (A) to (E). This is a method for manufacturing a laminated antenna, characterized in that a pattern of a coat layer is formed, and a wiring pattern including filling of through holes is formed by printing a conductive paste on the insulating coat layer.
(A) Polyester resin (B) Plate-like inorganic filler (C) Fused silica (D) Rubber phase (E) Epoxy resin

Further, the present invention is preferably a method for manufacturing a laminated antenna in which a conductive paste is heat-treated at 130 ° C. or higher to form a wiring pattern.

Further, the present invention is preferably a method for manufacturing a laminated antenna in which an insulating coating agent is cured by a heat treatment at 120 ° C. or higher to form an insulating coating layer.

The laminated antenna of the present invention is thin, compact, and has high performance because a wiring pattern and an insulating coat layer having a predetermined composition having through holes are formed and laminated by printing.

In addition, a laminated antenna in which two or more independent antennas that are magnetically coupled by forming antennas that are miniaturized and improved in performance by stacking on both sides of a substrate made of a resin film, or magnetic A laminated antenna in which two or more independent antennas that are magnetically shielded by forming on both sides of a substrate made of a body are laminated, and an antenna arranged on both sides by forming a through hole in the substrate. By connecting in series or in parallel, it is possible to obtain a more compact and high-performance stacked antenna.

Further, according to the method for manufacturing a laminated antenna of the present invention, a laminated antenna can be manufactured at a lower cost with less man-hours than the conventional method.

It is a schematic cross-sectional view of the laminated antenna of one Embodiment of this invention. It is a schematic cross-sectional view of the laminated antenna of one Embodiment of this invention. It is a schematic cross-sectional view of the laminated antenna of one Embodiment of this invention. It is an SEM photograph of the cross section of the laminated antenna of this invention. It is an SEM photograph of the cross section of the insulating coat layer of the laminated antenna of this invention.

Hereinafter, the present invention will be described with reference to the drawings. In the drawings, illustrations of external connection terminals, communication processing circuits, etc. are omitted. The present invention is not limited to the following embodiments.

FIG. 1 is a partial cross-sectional view of a stacked antenna according to an embodiment of the present invention. In the present invention, a plurality of wiring patterns 13 formed of conductive paste via an adhesive layer 12 are laminated on both sides of the insulating substrate 11 with an insulating coat layer 14 having through holes 15 interposed therebetween, and the wiring patterns 13 pass through. It is a through-hole antenna connected via a hole 15. In order to manufacture the laminated antenna 1 of the present embodiment, after forming the adhesive layers 12 on both sides of the insulating substrate 11, the wiring pattern 13-1 is formed by printing the conductive paste on each surface, and the through hole 15- The insulating coat layer 14-1 is formed by printing an insulating coating agent so as to cover the wiring pattern 13-1 except for 1, and the wiring pattern 13-2 is printed on the insulating coating layer 14-1 by printing a conductive paste. Although it is formed, the through hole 15-1 can be filled with the conductive paste together with the formation of the wiring pattern 13-2, and the wiring patterns 13-1 and 13-2 are electrically connected. An insulating coat layer and a wiring pattern are further laminated on the wiring pattern 13-2 in the same manner to obtain a laminated antenna having a predetermined structure having antenna coils 16A and 16B. In the present embodiment, if the insulating substrate is a resin film, it becomes a laminated antenna in which two or more magnetically coupled independent antennas are laminated, and if it is a magnetic material, two or more magnetically shielded antennas are formed. It becomes a stacked antenna in which independent antennas are stacked.

FIG. 2 is a partial cross-sectional view of the stacked antenna according to the embodiment of the present invention. In the present invention, a through hole 20 is formed in the insulating substrate 21, and the wiring pattern 23-1 formed on one surface of the insulating substrate 21 and the wiring pattern 23-1 formed on the other surface form the through hole 20. It may be connected via. In order to manufacture the laminated antenna 2 of the present embodiment, a through hole is formed in the insulating base 21 provided with the adhesive layer 22 if necessary, and the wiring pattern 23-1 is formed on the through hole. Along with the formation, the through holes 20 can be filled with the conductive paste, and the wiring patterns 23-1 on both sides are electrically connected to each other. An insulating coat layer and a wiring pattern are further laminated on the wiring pattern 23-1 in the same manner to obtain a laminated antenna having a predetermined structure having an antenna coil 26. In the present embodiment, if the insulating substrate is a resin film, the coils arranged on both sides of the insulating substrate are connected to form an integrated antenna, which makes it possible to reduce the size and improve the performance of the antenna.

FIG. 3 is a partial cross-sectional view of the laminated antenna according to the embodiment of the present invention. The laminated antenna 3 has a structure in which a magnetic material 37 is attached to one side of the laminated antenna 2 shown in FIG. 2 by a double-sided tape 38. is there. For convenience of sticking, a coat layer 34-3 is provided on the outermost layer of the sticking surface of the laminated antenna 2. According to the present embodiment, the laminated antenna of the present invention can be used even in a metal environment.

FIG. 4 is an SEM photograph of a cross section of the stacked antenna of the present invention. From the bottom, the magnetic material (ferrite sintered body), the adhesive layer, the wiring pattern in which the conductive particles are sintered, the insulating coat layer, and the wiring pattern are laminated again in this order.

FIG. 5 is an SEM photograph of a cross section of the insulating coating layer of the laminated antenna of the present invention. In taking this photograph, the surface was etched with toluene to elute the rubber phase in order to observe the distribution of the rubber phase, which does not show contrast with the resin. It can be confirmed that the plate-shaped inorganic filler (kaolin), the fumed silica, and the particulate rubber phase are dispersed and present in the insulating coat layer.

Hereinafter, each component will be described in detail.

In the laminated antenna according to the present invention, a wiring pattern and an insulating coat layer are laminated on an insulating substrate.

First, the insulating substrate will be described.

The insulating substrate preferably has a sheet shape from the viewpoint of reducing the thickness of the antenna component, and a magnetic material, a resin film, or the like can be used according to a desired function.

The magnetic material used in the present invention is preferably a soft magnetic material having a large magnetic permeability real part (μ') and a small magnetic permeability imaginary part (μ ”) at the frequency used. A sheet obtained by mixing a metallic soft magnetic powder with a resin. It is preferable that the material is formed into a shape, a sintered sheet such as spinel-based magnetic ferrite, or a composite magnetic sheet in which a resin film is attached to the sintered sheet to give flexibility. In a frequency band around 13.56 MHz such as RFID. When used, Ni—Zn ferrite or the like is preferable.

In the present invention, a Ni—Zn ferrite-based sintered ferrite sheet obtained by the green sheet method is preferable because the wiring pattern is heat-treated to make it conductive. Although not limited, the sheet thickness is preferably 50 to 300 μm.

The resin film used in the present invention must withstand heat treatment. For example, a polyimide resin sheet or film, an aromatic polyamide resin sheet or film, a glass epoxy laminated board, or the like can be mentioned, and among them, a polyimide resin sheet or film is preferable.

Examples of the polyimide-based resin include a polyimide precursor resin, a solvent-soluble polyimide resin, and a polyamide-imide resin. The polyimide resin can be polymerized by a usual method. For example, a method of reacting tetracarboxylic acid dianhydride and diamine in a solution at a low temperature to obtain a polyimide precursor solution, a method of reacting tetracarboxylic acid dianhydride and diamine in a solution to obtain a solvent-soluble polyimide solution, and a raw material. There are a method using isocyanate and a method using acid polyimide as a raw material.

In the present invention, in order to form wiring patterns on both sides of the insulating substrate, through holes are provided in the insulating substrate, and the wiring pattern formed on one surface of the insulating substrate and the wiring pattern formed on the other surface are used. May be connectable via a through hole.

Next, the wiring pattern will be described.

In the present invention, the wiring pattern is formed by the conductive paste on the insulating substrate or the insulating coat layer. The wiring pattern may be wiring that constitutes an antenna, may be filled in a through hole, or may form a terminal, or may be formed in a pattern or on a surface at an arbitrary location.

The wiring constituting the antenna is a wiring formed on a single plane having all or a part of the antenna coil, and preferably has a plane spiral coil pattern. The coil pattern on each plane may be an antenna coil that is electrically independent of the coils on the other planes, and the coils formed on the plurality of planes are connected via through holes provided in the insulating coat layer. Although it may be an antenna coil, it is preferable that a plurality of plane spiral coil patterns are connected via through holes provided in the insulating coat layer to form an antenna coil. Further, a plurality of coils may be provided on one plane, and each may form a different antenna coil.

The thickness of the wiring pattern is mainly determined from the required conductivity, but is preferably 0.05 to 100 μm. If the thickness of the wiring pattern is less than 0.05 μm, sufficient conductivity may not be obtained, and if it exceeds 100 μm, the pattern is defective due to the bumping of the solvent remaining in the pattern during the heat treatment. There is a possibility, and it is not preferable from the viewpoint of thinning the antenna. The thickness of the wiring pattern is more preferably 0.2 to 50 μm. In order to obtain a sufficiently small coil resistance, the thickness of the wiring pattern is even more preferably 5 to 50 μm.

The conductive paste used in the present invention contains a conductive alloy powder and a binder resin as main components and is dispersed in a solvent. After printing a wiring pattern, it is sintered by heat treatment to exhibit high conductivity. However, it is not particularly limited as long as it exhibits a sufficiently small resistance.

Examples of the conductive particles used in the conductive paste include metals such as gold, silver, copper, nickel and aluminum. Among them, the conductive particles constituting the conductive paste used in the present invention are preferably copper or metal particles containing copper as a main component, and may be a copper alloy having a copper content of 80% by weight or more, and the copper powder. The surface of the material may be coated with silver. The silver coating on the copper powder may be completely coated or may be coated by exposing a part of copper. Further, the copper powder may have an oxide film on the surface of the particles to the extent that the conductivity is not impaired. The shape of the copper powder can be substantially spherical, dendritic, flaky or the like. As the copper powder or the copper alloy powder, wet copper powder, electrolytic copper powder, atomized copper powder, vapor phase reduced copper powder and the like can be used.

The conductive paste used in the present invention preferably contains a copper powder of 1 μm or less in order to improve the conductivity by heat treatment. The copper powder used in the embodiment of the present invention has an average particle size of 0.01 to 20 μm. If the average particle size of the copper powder is larger than 20 μm, it becomes difficult to form a fine wiring pattern on the insulating substrate. Further, when the average particle size is smaller than 0.01 μm, the occurrence of strain due to the fusion between the fine particles during the heat treatment becomes large, and the adhesion to the substrate decreases. The average particle size of the copper powder is more preferably in the range of 0.02 μm to 15 μm, still more preferably 0.04 to 4 μm, and even more preferably 0.1 to 2 μm. As long as the average particle size of the copper powder used in the present invention is 0.01 to 20 μm, two or more types of copper powder having different particle sizes may be mixed and used. In particular, in copper paste for screen printing, it is preferable to use a mixture of 0.05 to 0.5 μm powder and 1 to 10 μm powder for the purpose of imparting flow characteristics, and 1 to 10 μm size non-spherical particles. Is more preferable, and the blending ratio of the micron-sized non-spherical particles is more preferably 10 to 60% by weight of the total copper powder.

The optimum range of heat treatment conditions for the conductive paste differs depending on the target of conductivity, the characteristics of the metal powder, and the binder resin. The heat treatment temperature is 130 ° C. or higher, preferably 250 ° C. or higher, and more preferably 300 ° C. or higher. The upper limit temperature of the heat treatment varies depending on the material used, but is more preferably 400 ° C. or lower because of deterioration of the binder resin and the like. The heat treatment time is 10 seconds to 10 minutes, more preferably 20 seconds to 5 minutes. As a heat treatment method, superheated steam treatment is preferable because it has high heating efficiency and can suppress deterioration of adhesion due to treatment at high temperature. Further, in particular, superheated steam treatment is preferable in order to shorten the treatment time required for the reduction of the oxide on the surface of the copper powder and obtain sufficiently high conductivity. Superheated steam treatment is steam whose temperature is raised by further heating saturated steam, which has a larger heat capacity and specific heat than heat and air.

The conductive paste used in the present invention uses a polymer compound as a binder resin. A conductive paste using a polymer compound as a binder resin is known as a polymer-type conductive paste. In the polymer type conductive paste, the binder resin can secure the adhesion of the conductive particles and the adhesiveness to the base material, but the binder resin hinders the contact between the conductive particles, which deteriorates the conductivity. However, if the ratio of the conductive particles is increased and the ratio of the binder resin is reduced, not only the adhesiveness to the substrate is lowered, but also the wiring pattern is easily embrittled, the bending resistance is deteriorated, and the durability is deteriorated. Therefore, in the present invention, the ratio of the conductive particles in the conductive paste is preferably 90% to 98% by weight.

The solvent used in the conductive paste used in the present invention may be an organic compound or water as long as it dissolves the binder resin. The solvent has a role of adjusting the viscosity of the dispersion in addition to the role of dispersing the copper powder in the conductive paste. Examples of organic solvents include alcohols, ethers, ketones, esters, aromatic hydrocarbons, amides and the like.

Examples of the binder resin used in the conductive paste used in the present invention include resins such as polyester, polyurethane, polycarbonate, polyether, polyamide, polyamideimide, polyimide and acrylic. A resin having an ester bond, a urethane bond, an amide bond, an ether bond, an imide bond or the like in the main chain is preferable from the viewpoint of stability of the copper powder.

The ratio of each component of the conductive paste used in the present invention is preferably in the range of 5 to 400 parts by weight of the solvent and 0.5 to 20 parts by weight of the binder resin with respect to 100 parts by weight of the conductive particles. When the amount of the binder resin in the conductive paste is less than 0.5 parts by weight with respect to 100 parts by weight of the copper powder, the adhesion to the substrate becomes remarkable, which is not preferable. On the other hand, if the amount of the binder resin exceeds 20 parts by weight, conductivity cannot be ensured due to a decrease in contact opportunities between the conductive particles. The binder resin is more preferably 1 to 6 parts by weight, still more preferably 2 to 5 parts by weight.

Further, in the conductive paste used in the present invention, the ratio of conductive particles in the total non-volatile content (conducting particle content ratio) is preferably 94% by weight or more, more preferably 96% by weight or more. Here, the non-volatile component is a component of the conductive paste other than the volatile solvent, and is a conductive particle, a binder resin, a filler, a curing agent, a dispersant, or the like. Conductivity can be increased by increasing the proportion of conductive particles in the total non-volatile content. If the proportion of conductive particles in the total non-volatile content is less than 94% by weight, the effect of improving conductivity is poor. The upper limit of the proportion of conductive particles in the total non-volatile content varies depending on the binder resin used, but is preferably 99% by weight, more preferably 98% by weight.

When the ratio of the conductive particles in the total non-volatile content is increased, a small amount of the binder resin can bring out the functions required for the binder resin. Therefore, the higher the molecular weight of the binder resin, the more preferable. The desirable molecular weight varies depending on the type of binder resin, but the number average molecular weight of polyester, polyurethane or polycarbonate is 10,000 or more, preferably 20,000 or more. The upper limit of the molecular weight of the binder resin is about 500,000 depending on the viscosity of the dispersion and the like.

It is necessary for the conductive particles to maintain a good dispersed state in the conductive paste in order to exhibit good conductivity. In order to bring out the functions required for the binder resin with a small amount of the binder resin, the binder resin may contain a polymer containing a functional group capable of adsorbing to a metal such as a sulfonic acid base or a carboxylic acid base. desirable.

The content of the sulfonate base is represented by the sulfur content in the binder resin, and the sulfur content in the binder resin is preferably 0.05 to 3% by weight, more preferably 0.1 to 1% by weight. is there. The carboxylic acid base is preferably contained as the original carboxylic acid group in an amount of 30 to 500 mol per ton of the binder resin, more preferably 50 to 200 mol.

A curing agent may be added to the conductive paste used in the present invention, if necessary. Examples of the curing agent that can be used in the present invention include phenol resins, amino resins, isocyanate compounds, epoxy resins, oxetane compounds, maleimide compounds and the like. The amount of the curing agent used is preferably in the range of 1 to 50% by weight, more preferably in the range of 1 to 20% by weight of the binder resin.

The conductive paste used in the present invention may contain a dispersant. Examples of the dispersant include higher fatty acids such as stearic acid, oleic acid and myristic acid, fatty acid amides, fatty acid metal salts, phosphoric acid esters and sulfonic acid esters. The amount of the dispersant used is preferably in the range of 0.1 to 10% by weight of the binder resin.

As a method for obtaining the conductive paste, a general method of dispersing the powder in a liquid can be used. For example, a mixture consisting of conductive particles, a binder resin solution, and if necessary, an additional solvent may be mixed and then dispersed by an ultrasonic method, a mixer method, a three-roll method, a ball mill method, or the like. It is also possible to perform dispersion by combining a plurality of these dispersion means. These dispersion treatments may be carried out at room temperature or may be carried out by heating in order to reduce the viscosity of the dispersion.

Next, the insulating coat layer will be described.

In the present invention, the insulating coating layer is a layer formed by an insulating coating agent between a plurality of wiring patterns, and is a polyester resin (A), a plate-shaped inorganic filler (B), a fumed silica (C), and a rubber phase (D). ) And a cured product of the resin containing the epoxy resin (E). Through holes are provided in the insulating coat layer, and wiring patterns are connected via the through holes.

The thickness of the insulating coat layer provided in the present invention is determined from the specifications of the product incorporating the multilayer circuit board, but the thickness after drying by evaporating the solvent may be used within a range of 25 μm or less due to insulation, durability, etc. it can. If the thickness of the insulating coat layer exceeds 25 μm, the step with the non-coated portion becomes large, and the wiring pattern formed on the insulating coat layer may be cracked at the step portion. The thickness of the insulating coating layer is preferably 5 to 23 μm, more preferably 8 to 20 μm, and even more preferably 10 to 18 μm. If the thickness of the insulating coat layer is less than 5 μm, the insulating property may be unstable, and the durability under high temperature and high humidity may be inferior. The thickness of the insulating coat layer is measured in a flat portion without a wiring pattern. The insulating coat layer on the wiring pattern may be thinner than the flat portion due to dripping of the coating agent, but if the insulating coat layer is formed with the above-mentioned thickness, the upper and lower wiring patterns are sufficiently insulated.

The insulating coat layer in the present invention is provided with a through-hole portion by pattern printing when connecting wiring patterns laminated on the upper and lower sides of the insulating coat layer. It is preferable to reduce the volume of the through-hole portion so that the through-hole portion can be filled with the copper paste at the same time when the wiring pattern is printed. When the diameter of the through-hole portion is in the range of 100 to 1000 μm and the thickness of the insulating coat layer is 25 μm or less, the through-hole portion can be filled with the copper paste at the same time as printing. When the diameter and thickness of the through-hole portion are in the above range, it is not always necessary to newly provide a copper paste filling step in the through-hole portion.

Since the insulating coat layer provided in the present invention has excellent adhesiveness and heat resistance to the conductive layer, it is effective in preventing dielectric breakdown due to sintering of the wiring pattern provided on the insulating coat layer.

The insulating coating agent used in the present invention contains a polyester resin (A), a plate-shaped inorganic filler (B), fumed silica (C), and a rubber phase (D) epoxy resin (E).

The polyester resin (A) preferably has an acid value of 800 to 2500 equivalents per ton of highly oxidized polyester, more preferably 1000 to 2300 equivalents.

The preferred molecular weight of the polyester resin (A) is 5,000 to 30,000 in terms of number average molecular weight.

As the polyester resin (A), a reaction product of a polyester diol and / or a polycarbonate diol and a tetracarboxylic dianhydride is preferable. The reaction product of the polyester diol and / or the polycarbonate diol and the tetracarboxylic acid dianhydride is a hydroxyl group and a tetracarboxylic of the polyester diol and / or the polycarbonate diol having a number average molecular weight of preferably 500 to 5000, more preferably 700 to 2000. It is a product of a chain extension reaction involving an ester bond and the formation of a carboxylic acid group by reaction with an acid dianhydride group. The molecular weight and acid value are determined by the molecular weight of the polyester diol and / or the polycarbonate diol, the ratio of the hydroxyl group of the diol compound to the acid anhydride group of the tetracarboxylic dianhydride, and the like. In order to increase the acid value, glycols such as ethylene glycol and neopentyl glycol may be used as a part of the diol compound. An acid anhydride group may be reacted with the hydroxyl group of the diol compound under a slightly excessive condition to reach a predetermined molecular weight, and then the reaction of the terminal acid anhydride group may be stopped with a primary amino compound.

The insulating coating agent used in the present invention forms a crosslinked structure by the reaction of a carboxylic acid group and an epoxy group. Although the carboxylic acid group is present in the polyester, the concentration of the crosslinked points can be prevented, the strain of the crosslinked product can be reduced, and the insulating coat layer can be prevented by having the molecular weight of the ester diol and / or the polycarbonate diol used as a raw material being 500 or more. Contributes to the improvement of heat resistance and physical properties of polycarbonate.

The polyester used as the insulating coating agent in the present invention preferably has a glass transition temperature of 40 ° C. or lower, more preferably 30 ° C. or lower, in order to reduce the occurrence of curl due to cross-linking and maintain adhesiveness. The lower limit of the glass transition temperature is preferably −30 ° C., more preferably −20 ° C. from the viewpoint of the physical properties of the cured product.

The reaction of the polyester diol and / or the polycarbonate diol with the tetracarboxylic dianhydride may be carried out in a molten state, but is preferably carried out in the presence of a tertiary amino compound in an organic solvent.

Examples of the tetracarboxylic dianhydride used in the reaction of the polyesterdiol and / or the polycarbonate diol with the tetracarboxylic dianhydride include pyromellitic acid dianhydride, benzophenone tetracarboxylic dianhydride, and biphenyltetracarboxylic dianhydride. Examples thereof include diphenylsulphontetracarboxylic dianhydride, diphenyl ethertetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, pyromellitic acid dianhydride, hydrogenated biphenyltetracarboxylic dianhydride, and the like, and benzophenone-. 3,3', 4,4'-tetracarboxylic dianhydride, biphenyl-3,3', 4,4'-tetracarboxylic dianhydride, diphenylsulphon-3,3', 4,4'-tetra Acarboxylic dianhydride and a diphenyl ether-3,3', 4,4'-tetracarboxylic dianhydride are desirable. The tetracarboxylic dianhydride may be used alone or in combination.

The insulating coating agent used in the present invention further contains a plate-shaped inorganic filler (B), fumed silica (C), a rubber phase (D) and an epoxy resin (E).

The plate-shaped inorganic filler (B) provides a mechanical reinforcing effect and an improvement in heat resistance of the insulating coat layer. By using the plate-shaped inorganic filler (B) and the fumed silica (C) together, the elastic modulus, tensile strength, toughness, and heat resistance can be improved by the interaction between the silanol groups on the surface of the fumed silica and the plate-shaped inorganic filler. Further improve.

The particle size of the plate-shaped inorganic filler (B) is preferably in the range of 10 to 0.1 μm, and the aspect ratio is 5.0 or more, preferably 10.0 or more. Examples of the plate-shaped inorganic filler include talc, mica, kaolin, montmorillonite, synthetic mica, plate-shaped alumina and the like, and talc, mica and kaolin are preferable. The amount of the plate-shaped inorganic filler added is in the range of 10 to 100 parts by weight, preferably 30 to 80 parts by weight, assuming 100 parts by weight of polyester.

Further, the fumed silica (C) contributes to the improvement of the fluidity of the insulating coat in addition to the improvement of the physical properties of the insulating coat layer, and can impart a sagging prevention function. The particle size of the fumed silica (C) is preferably 50 nm or less, more preferably 30 nm or less. The amount of fumed silica added is in the range of 0.5 to 8 parts by weight, preferably 2 to 5 parts by weight, assuming 100 parts by weight of polyester.

When the amount of the plate-shaped inorganic filler (B) or fumed silica (C) added is less than the above range, the mechanical reinforcement effect is inferior, and when it is more than the above range, the interlayer adhesiveness of the insulating coat layer deteriorates. There is. Further, if the amount of fumed silica (C) added exceeds the above range, even if the leveling agent for the insulating coating is optimized, the fluidity may deteriorate and the surface roughness after coating may become severe.

The rubber phase (D) is added to the insulating coating agent used in the present invention. The rubber phase has a function of relaxing the internal stress generated when the insulating coat layer is cured or when the wiring pattern formed on the insulating coat layer is sintered. Further, the rubber phase has the thermomechanical characteristics of the insulating coat layer generated at the time of sintering the wiring pattern and the existing wiring pattern, especially when the insulating coating layer is formed on the wiring pattern and the wiring pattern is further formed. It has the function of alleviating the distortion caused by the difference and preventing the upper wiring pattern from breaking. Further, the rubber phase has a function of alleviating the strain generated at the interface between the insulating coat and the wiring pattern due to volume shrinkage in the heat treatment of the wiring pattern formed on the insulating coating layer, and preventing the wiring pattern from peeling off. These functions are more remarkable in the third layer and the upper layer than the second layer of the wiring pattern, and due to the presence of the rubber phase, there is no disconnection or short circuit even if the wiring pattern is repeatedly sintered by heat treatment. Stacked antennas can be manufactured.

Further, the insulating coat layer of the present invention has a high crosslink density of a resin made of polyester and epoxy in order to improve heat resistance and insulating properties, and has a high elastic modulus and becomes brittle because a plate-like filler and fumed silica are added. Although there is a tendency, the toughness can be improved by dispersing the rubber phase in the insulating coat, and for example, it is possible to prevent the base material from breaking or cracking. Therefore, the rubber phase is also effective in improving the toughness and heat resistance of the insulating coat layer.

Examples of the composition of the rubber phase include polybutadiene, polystyrene butadiene, polyacrylonitrile butadiene, polyacrylic acid ester, and silicone rubber. The rubber phase is selected from those that do not dissolve in the solvent of the coating agent or other components, or that the rubber phase separates after drying or curing. Examples of the form of such a rubber phase include those in which the coating agent before coating is in the form of liquid rubber, and the phase is separated to form a rubber phase at the time of curing. For example, a carboxyl group-terminated butadiene nitrile rubber ( CTBN), polybutadiene, a block polymer composed of a silicone rubber block and a block polymer of a parent epoxy at both ends thereof, and the like can be mentioned. In another form, in order to prevent blocking, the fine particles have a core-shell structure, the core is a crosslinked rubber, and the shell is a core-shell fine particle such as acrylic having a high glass transition temperature cured with, for example, a polyfunctional acrylic. It is preferably composed of a rubber component that has been subjected to an anti-blocking treatment such as cross-linking, and more preferably, rubber particles that are monodispersed in advance in an epoxy resin are mixed with a polyester resin.

The rubber phase (D) used in the insulating coating agent in the present invention preferably has an average particle size of 0.05 to 5 μm. The content of the rubber phase is 5 to 50 parts by weight, preferably 15 to 30 parts by weight, assuming 100 parts by weight of polyester. If it is less than 5 parts by weight, the improvement of heat resistance and physical properties is insufficient, and if it exceeds 50 parts by weight, deterioration of physical properties and deterioration of interlayer adhesiveness may be observed.

The epoxy resin (E) used for the insulating coating agent in the present invention is a resin having two or more epoxy groups in one molecule, and examples thereof include glycidyl ether type, glycidyl ester type, glycidyl amine type and olefin oxidation type epoxy resins. Be done. The amount of the epoxy resin added is preferably in the range from the equivalent of the acid value of the polyester used in the present invention to twice the equivalent value, and the amount of epoxy equal to or less than the acid value of the polyester depends on the unreacted carboxylic acid. Due to hydrolysis, the long-term durability of the insulating coat layer may be inferior, and if it exceeds twice the acid value of polyester, the crosslink density may decrease and the heat resistance may be inferior. Further, a catalyst that promotes the reaction between the epoxy resin and the carboxyl group may be added. Examples of the catalyst include a tertiary amine compound, an imidazole compound, a phosphine compound and the like.

Next, a method for manufacturing a laminated antenna according to the present invention will be described.

In the laminated antenna according to the present invention, a wiring pattern is formed by printing a conductive paste on an insulating substrate, and a pattern of an insulating coating layer having an opening as a through hole is formed on the wiring pattern by printing an insulating coating agent. , It can be manufactured by forming a wiring pattern including filling of through holes by printing a conductive paste on the insulating coating layer.

In order to increase the conductivity of the conductive paste used in the present invention, it is preferable to reduce the ratio of the binder component in the paste. Therefore, if the conductive paste is printed directly on the insulating substrate, the adhesiveness may be insufficient. Therefore, in order to impart adhesiveness to the insulating substrate, it is preferable to provide an adhesive layer on the insulating substrate and form a wiring pattern through the adhesive layer. Further, the adhesive layer used in the present invention has a feature of maintaining sufficient adhesive strength by heat treatment.

The resin used for the adhesive layer is selected from those having excellent adhesiveness to the insulating substrate, and examples thereof include polyester, polyurethane, polycarbonate, aromatic polyether, polyamide, polyamideimide, and polyimide. A resin having an ester bond, an imide bond, an amide bond, or the like is desirable from the viewpoint of heat resistance of the adhesive layer and adhesion to the substrate. It is also desirable that the adhesive layer contains a curing agent from the viewpoint of heat resistance of the adhesive layer and adhesiveness to the insulating substrate. Examples of the curing agent include phenol resins, amino resins, isocyanate compounds, epoxy resins, oxetane compounds, maleimide compounds and the like. The amount of the curing agent used is preferably in the range of 1 to 50% by weight based on the weight of the resin in the adhesive layer.

The adhesive layer may contain a heterocyclic compound and / or a hydrazide compound containing nitrogen in the heterocycle. Heterocyclic compounds and hydrazide compounds containing nitrogen in the heterocycle may be used as a rust preventive for copper foil and copper powder, but in the present invention, these compounds are subjected to heat treatment to form a copper powder-containing coating film. Demonstrates strong adhesion. Heterocyclic compounds and hydrazide compounds containing nitrogen have a high affinity for copper and are strongly adsorbed on the copper surface. It is necessary to give energy to adsorb nitrogen-containing heterocyclic compounds and hydrazide compounds present on the surface of copper powder, which are present in the adhesive layer having excellent adhesiveness to the insulating substrate, heat treatment is effective, and superheated steam. The treatment has the highest thermal efficiency.

Examples of the heterocyclic compound containing nitrogen in the heterocycle include pyridine, oxazole, isoquinoline, indol, thiazole, imidazole, benzimidazole, bipyridyl, pyrazole, benzothiazole, pyrimidine, purine, triazole, benzotriazole, benzoguanamine and the like, or These structural isomers are also mentioned. These may have substituents such as an alkyl group, a phenyl group, a phenol group, a carboxyl group, an amino group, a hydroxyl group, a thiol group and an aromatic ring. In addition, these may be condensed with an aromatic ring or a heterocycle. Of these, imidazole-based compounds and benzotriazole-based compounds are desirable.

The hydrazide compound is a compound having a structure in which hydrazine or a derivative thereof is condensed with a carboxylic acid, and examples thereof include salicylate hydrazide, isophthalic acid dihydrazide, and a condensate of salicylate hydrazide and dodecandicarboxylic acid.

It is desirable that the adhesive layer of the present invention contains a heterocyclic compound and / or a hydrazide compound containing nitrogen in the heterocycle in the range of 1 to 30 parts by weight with respect to 100 parts by weight of the adhesive layer resin. If the amount of the heterocyclic compound and / or the hydrazide compound containing nitrogen in the heterocycle is less than 1 part by weight with respect to 100 parts by weight of the resin for the adhesive layer, the adhesion to the copper powder-containing layer may be insufficient. If it exceeds 30 parts by weight, the physical properties of the adhesive layer may be deteriorated.

In order to form the adhesive layer on the insulating substrate, a general method used when applying or printing the resin constituting the adhesive layer on a film or a sheet can be used. For example, a screen printing method, a dip coating method, a spray coating method, a spin coating method, a roll coating method, a die coating method, a paste jet method, a letterpress printing method, an intaglio printing method and the like can be mentioned. An adhesive layer can be formed by evaporating a solvent from a coating film formed by printing or coating by heating, reducing pressure, or the like. The adhesive layer may be provided on the insulating substrate on the entire surface or partially, and it is desirable that the adhesive layer is provided at least on the portion forming the wiring pattern.

The adhesive layer formed on the insulating substrate in the present invention preferably has a thickness of 25 μm or less, particularly 20 μm or less. In particular, when the insulating substrate is a magnetic material, it is desirable that the magnetic material is close to the coil line from the viewpoint of antenna performance, and therefore, the thickness of the adhesive layer is preferably 25 μm or less. Further, from the viewpoint of adhesiveness, if the thickness of the adhesive layer exceeds 25 μm, the adhesiveness may decrease due to the sintering strain of the copper powder caused by the heat treatment. Further, if the thickness is less than 0.01 μm, the adhesion may be significantly reduced due to decomposition of the binder resin by heat treatment or the like.

Further, it is preferable that the weight loss by heating of the adhesive layer after curing is 25% by weight or less. However, here, the heating weight loss after curing means the heating weight loss after curing under the condition of 10 minutes under a superheated steam atmosphere at 300 ° C. If the weight loss by heating is more than 25% by weight, the adhesiveness cannot be maintained due to decomposition or carbonization of the adhesive layer in the step of heat-treating the conductive paste. The lower limit of the weight loss by heating is about 0.01% by weight.

To form a wiring pattern on an insulating substrate, preferably via an adhesive layer, using a liquid conductive paste, the general method used when applying or printing the conductive paste on a film or sheet is used. be able to. Examples thereof include a screen printing method, a dip coating method, a spray coating method, a spin coating method, a roll coating method, a die coating method, an inkjet method, a letterpress printing method, an intaglio printing method, and a dispenser. Above all, in order to obtain a sufficiently small coil resistance in the present invention, a screen printing method, a dispenser method or the like is preferable as a method for forming a wiring pattern of a laminated antenna.

A wiring pattern can be formed by evaporating a solvent from a pattern formed by printing or coating by heating, depressurization, or the like. Generally, in the case of a conductive paste, the wiring pattern at this stage has a specific resistance of 1 Ω · cm or more, and the conductivity required for a conductive circuit has not been obtained. Therefore, it is necessary to make the conductive paste conductive by heat treatment.

The thickness of the wiring pattern before the heat treatment is mainly determined from the required conductivity, but the thickness after drying by evaporating the solvent contained in the conductive paste is preferably 0.05 to 100 μm. If the thickness of the wiring pattern before the heat treatment is less than 0.05 μm, sufficient conductivity may not be obtained even after the heat treatment, and if it exceeds 100 μm, the solvent may remain in the pattern. The residual solvent can bump during the heat treatment, which can result in defects in the pattern. The thickness of the wiring pattern before the heat treatment is more preferably 0.2 to 50 μm. In order to obtain a sufficiently small coil resistance, the thickness of the wiring pattern before the heat treatment is even more preferably 5 to 50 μm.

In the present invention, it is preferable that the wiring pattern is made conductive by heat treatment at 130 ° C. or higher to form a conductive layer, and more preferably heat treatment is performed at 250 ° C. or higher. As the heat treatment method, superheated steam treatment is preferable from the viewpoint of heating efficiency, safety, economy, conductivity and the like. The superheated steam treatment uses superheated steam having a larger heat capacity and specific heat than air as a heat source for heat treatment, and superheated steam is steam whose temperature is raised by further heating saturated steam. The superheated steam treatment conditions vary depending on many factors, but in general, the temperature of the superheated steam treatment is preferably 300 ° C. or higher, preferably 320 ° C. or higher. The superheated steam treatment time is 10 seconds to 10 minutes, preferably 20 seconds to 5 minutes. The superheated steam treatment as a heating method is particularly preferable because the heat efficiency is good and the treatment time can be shortened, so that the deterioration of the adhesiveness due to the treatment at a high temperature can be suppressed.

In order to form an insulating coating layer on the wiring pattern with an insulating coating agent, a general method used when applying or printing a resin on a film or a sheet can be used. For example, a screen printing method, a dip coating method, a spray coating method, a spin coating method, a roll coating method, a die coating method, an inkjet method, a letterpress printing method, an intaglio printing method and the like can be mentioned. An insulating coat layer can be formed by evaporating a solvent from a coating film formed by printing or coating by heating, reducing pressure, or the like.

In order to provide a through hole in the insulating coat layer, for example, when the insulating coat layer is provided by screen printing, printing may be performed using a plate having a mask on the through hole portion. When through holes are provided in the insulating coat layer by screen printing, the above-mentioned fumed silica acts as a sagging preventive agent, but if necessary, other rheology control agents such as higher fatty acid amide may be added.

Further, a leveling agent such as an acrylic polymer or a vinyl ether polymer may be added to smooth the printed surface of the insulating coat layer.

It is desirable that the insulating coating layer provided in the present invention be cured after the insulating coating agent is applied and dried. The curing treatment can be performed by heat treatment at 120 ° C. or higher, and superheated steam treatment is desirable because it can prevent heat treatment efficiency and oxidation of the existing wiring pattern. The superheated steam treatment conditions vary depending on many factors, but in general, the temperature of the superheated steam treatment is preferably 150 ° C. or higher, preferably 200 ° C. or higher. The superheated steam treatment time is 10 seconds to 10 minutes, preferably 20 seconds to 5 minutes. The superheated steam treatment as a heating method is particularly preferable because the heat efficiency is good and the treatment time can be shortened, so that the deterioration of the adhesiveness due to the treatment at a high temperature can be suppressed.

In the present invention, by repeating the formation of the wiring pattern and the formation of the insulating coat layer on the insulating substrate, the layers are sufficiently insulated and the wiring patterns are laminated. The outermost layer may be a wiring pattern for IC mounting or other purposes, or may be an insulating coat layer. By connecting the wiring patterns with through holes, an antenna coil and wiring of a desired design can be obtained, and a laminated antenna is manufactured.

The laminated antenna manufactured by the above method functions as an antenna as it is regardless of the type of insulating substrate, but since it is necessary to laminate with a magnetic material when used in a metal environment, a resin film is used as the insulating substrate. When used, it is also possible to attach the laminated antenna to a magnetic material. When the laminated antenna is attached to a magnetic material, the adhesive layer for the film may be formed by a known method directly on the surface of the film and / or the magnetic material, or the adhesive layer may be formed on both sides of the base material. It may be adhered through a so-called double-sided adhesive film formed of. The adhesive layer for the film includes, for example, acrylonitrile butadiene rubber / phenol resin, acrylonitrile butadiene rubber / epoxy resin / phenol resin, acrylonitrile butadiene rubber / epoxy resin, epoxy resin / polyester resin, epoxy resin / acrylic resin, acrylic resin, silicone resin and the like. Used.

Examples will be given below to explain the present invention in more detail, but the present invention is not limited to the examples. The measurements and materials used in the examples were measured or manufactured by the following methods.

The conductive paste consists of 1.14 parts of a solution of copolymerized polyester (RV290 manufactured by Toyobo Co., Ltd.) (35% by weight solution of ethylcarbitol), 9.6 parts of copper powder (average particle size 0.15 μm), and 0 ethylcarbitol acetate. .25 parts dispersed in 3 rolls were used.

As the insulating coating agent, the resins shown in Table 1 were used, and the compositions shown in Tables 2 and 3 were blended.

As shown in Table 1, the polyester resins 1 to 5 are an isophorone solution of a polyester resin having a number average molecular weight of 2000 (“RV-220” manufactured by Toyo Boseki Co., Ltd.) and a polyester polyol “P-1010” manufactured by Kuraray Co., Ltd., manufactured by Asahi Kasei Co., Ltd. Polycarbonate diol "Duranol T-5651", 3,3', 4,4'-benzophenone tetracarboxylic dianhydride (BTDA) as tetracarboxylic dianhydride in a solution containing triethylamine as a reaction catalyst, pyromellitic dianhydride Anhydrous (PMDA) was added and reacted at 80 ° C. for 6 hours to obtain the polyester resin shown in Table 1.

As shown in Table 1, the comparative resin 1 is an isophorone solution of a polyester resin having a number average molecular weight of 2000 (“RV-220” manufactured by Toyo Boseki Co., Ltd.) and a polycarbonate diol “Duranol T-5651” manufactured by Asahi Kasei Co., Ltd., 4, 4 ′. -Diphenylmethane diisocyanate (MDI) and 2,2-bis (hydroxymethyl) butyric acid (DMBA) were charged and reacted at 80 ° C. for 6 hours to obtain a polyurethane resin.

Yamaguchi Mica's "Mica A-11" (average particle size 3 μm) as a plate-like inorganic filler, Imeris's Kaolin "Ecarite ED" (average particle size 0.32 μm), and Tokuyama's "Leoloseal PM-" as fumed silica 20 ”(average particle size 12 μm),“ Leoloseal MT-10 ”(average particle size 15 μm), and core-shell type acrylic rubber particles“ Zefiac F351 ”(average particle size 0.3 μm) manufactured by Aika Kogyo Co., Ltd. were selected as the rubber component. It was dispersed in polyester resin with 3 rolls. Epoxy resin (EXA-835LV: bisphenol F type epoxy manufactured by DIC), (828: bisphenol A type epoxy manufactured by Mitsubishi Chemical Co., Ltd.), and if necessary, a curing accelerator (BDMA :: benzyldimethylamine) are added to the obtained dispersion. Formulated. Alternatively, as a resin or plate-like inorganic filler, "Mica A-11" manufactured by Yamaguchi Mica (average particle size 3 μm), Kaolin "Ecarite ED" manufactured by Imeris (average particle size 0.32 μm), and as fumed silica manufactured by Tokuyama. “Leoloseal PM-20” (average particle size 12 μm) and “Leoloseal MT-10” (average particle size 15 μm) were selected and dispersed in a polyester resin or a polyurethane resin with three rolls. A curing accelerator (BDMA: benzyldimethylamine) was added to the obtained dispersion, if necessary, with "Kaneace MX-154" manufactured by Kaneka Co., Ltd. in which butadiene rubber-based core-shell type rubber particles were dispersed in a bisphenol A type epoxy resin.

As a composition for an adhesive layer, 100 parts of a polyamide-imide solution (HR-11NN manufactured by Toyo Boseki Co., Ltd.), 15 parts of a phenol novolac type epoxy resin (jER (registered trademark) 152 manufactured by Mitsubishi Chemical Co., Ltd.) as a curing agent, and triphenyl as a curing catalyst. 3 parts of phosphine (TPP), 10 parts of 2-phenylimidazole as an additive, and 200 parts of tetrahydrofuran as a diluting solvent were mixed.

(Measurement of heat loss)
The above composition for an adhesive layer was molded into a film having a thickness of 10 μm, and a test piece cut into a width of 10 mm and a length of 10 mm was heated for 10 minutes in a superheated steam atmosphere at 300 ° C., and the weight loss after heating was measured. Then, it was calculated by (weight before heating-weight after heating) / weight before heating × 100. The weight loss by heating was 1.8% by weight.

(Example 1)
Using the coating agent 1 shown in Table 2 as the insulating coating agent, two layers of 4-turn flat spiral coils are laminated on both sides of the insulating substrate by the following procedure to manufacture a laminated antenna having a structure connected in series. did.

The composition for the adhesive layer is applied to both sides of the Kaneka polyimide film "Kapton EN thickness 5 μm" so that the thickness after drying is 0.5 μm, and the adhesive layer is provided by drying and heat treating at 200 ° C. for 5 minutes. An insulating substrate was obtained. Next, a spiral wiring pattern having a thickness of 25 μm was printed with a conductive paste on one adhesive layer of the insulating substrate by screen printing, temporarily dried at 100 ° C. for 10 minutes, and the wiring pattern was similarly printed on the other adhesive layer. Was printed and temporarily dried, and then heat-treated at 350 ° C. for 2 minutes under superheated steam. An insulating coat layer pattern having a thickness of 15 μm is printed with an insulating coating agent by screen printing with the through holes masked on one wiring pattern after the heat treatment, and temporarily dried at 100 ° C. for 10 minutes, and the same applies to the other wiring pattern. The insulating coat layer pattern was printed and temporarily dried, and then heat-treated at 350 ° C. for 2 minutes under superheated steam. A spiral wiring pattern is printed on one of the obtained insulating coat layers with a conductive paste while simultaneously filling through holes, temporarily dried at 100 ° C. for 10 minutes, and the same wiring pattern is applied on the other insulating coat layer. Was printed and temporarily dried, and then heat-treated at 350 ° C. for 2 minutes under superheated steam treatment. An insulating coat layer was sequentially printed, dried, and heat-treated on each wiring pattern after the heat treatment in the same manner as described above. Finally, a wiring pattern for IC mounting is printed on one insulating coat layer with a conductive paste while simultaneously filling through holes, temporarily dried at 100 ° C. for 10 minutes, and the wiring pattern is similarly applied on the other insulating coat layer. Was printed and temporarily dried, and then heat-treated at 350 ° C. for 2 minutes under superheated steam to obtain a laminated antenna.

(Example 2)
Using various coating agents shown in Table 2 as the insulating coating agent, two layers of 4-turn flat spiral coils are laminated on both sides of the insulating substrate to manufacture a laminated antenna having a structure in which all four layers are connected in series. did. Through holes were provided by drilling holes in the insulating substrate provided with the adhesive layer obtained in the same manner as in Example 1. A laminated antenna was obtained in the same manner as in Example 1 except that the through holes of the insulating substrate were filled with the conductive paste.

(Example 3)
A sintered ferrite sheet having a thickness of 150 μm and having grid-like cuts was obtained by pre-sintering Ni-Zn-Cu ferrite powder (FRX-950 manufactured by Toda Kogyo Co., Ltd.) at 920 ° C. for 2 hours by the green sheet method. .. Using the coating agent 1 shown in Table 2 as the insulating coating agent, the antenna wiring patterns were laminated in the same manner as in Example 2, and the sintered ferrite sheet was attached with a double-sided tape having a thickness of 10 μm to obtain a laminated antenna.
(Comparative Example 1)

Using FCCL in which a copper foil having a thickness of 35 μm is laminated on a PET having a thickness of 25 μm via an adhesive layer having a thickness of 20 μm, an antenna having an area four times that of the wiring pattern laminated in Examples 1 and 2 is subjected to a normal photoresist. It was formed by an etching process using.

(Comparative Examples 2-9)
It was carried out in the same manner as in Example 2 using the insulating coating agents having various compositions shown in Table 3.

(Measurement of communication characteristics)
A reader / writer with an IC chip (IC chip I CODE SLI manufactured by NXP) mounted on one side of the stacked antenna, a capacitor for adjusting the resonance frequency connected in parallel, and the resonance frequency adjusted to 13.56 MHz. (TR3-C201 manufactured by Takaya) was used for comparative evaluation of the communication distance. The results are shown in Tables 4 to 6.

In the first embodiment, two magnetically coupled antennas that are not electrically connected are stacked, an IC chip is mounted on one antenna, and only frequency adjustment is performed by a capacitor on the other. An antenna whose resonance frequency is adjusted without mounting an IC chip functions as a booster antenna, improving the directivity of the antenna on which the IC chip is mounted, and extending the communication distance compared to the case without a booster antenna. It was.

Since the antennas of Examples 2 and 3 have a structure in which four layers of antenna wiring patterns are laminated, a communication distance equivalent to that of Comparative Example 1 can be obtained in an area of one quarter of that of the antenna of Comparative Example 1. Further, when the antenna was installed on the metal, in Example 2, reading was not possible because there was no magnetic material, but in Example 3 in which the magnetic material was laminated, the same communication distance was obtained. In the antennas of Comparative Examples 2 to 9, cracks and bleeding occur in the wiring pattern when printing and stacking, the antenna circuit becomes short-circuited or open, and the resonance frequency of the stacked antenna starts from 13.56 MHz, which is the design value. It was too far off to read.

(Temperature cycle test)
A temperature cycle test was carried out on each of the 100 stacked antennas that could be communicated based on the JIS standard (JIS C 60068-2-14).

The temperature cycle test was carried out at 125 ° C. for 30 minutes, at −40 ° C. for 30 minutes, and between each holding temperature for 5 minutes, and the communication characteristics after 100 cycles were evaluated. Table 5 shows the number of stacked antennas that became incommunicable after 100 cycles.

(Example 4)
As the insulating coating agent, the coating agent 1 shown in Table 2 was used to laminate two layers of flat spiral coils of 4 turns on both sides of the insulating substrate to manufacture a laminated antenna having a structure connected in series. As the magnetic material as the insulating substrate, a sintered ferrite sheet obtained by sintering Ni-Zn-Cu ferrite powder (FRX-950 manufactured by Toda Kogyo Co., Ltd.) at 920 ° C. for 2 hours by the green sheet method was used. The sintered ferrite sheet has a complex relative magnetic permeability real part μ'of 150, a magnetic permeability imaginary part μ'is 3, and a thickness of 150 μm at a frequency of 13.56 MHz.

The composition for an adhesive was applied to both sides of a sintered ferrite sheet so as to have a thickness of 3 μm after drying, and dried and heat-treated at 200 ° C. for 5 minutes to obtain an insulating substrate provided with an adhesive layer. A laminated antenna was obtained in the same manner as in Example 1 except that this insulating substrate was used. A total of two IC chips were mounted on each of the antennas on both sides.

As a result of performing the communication test of Example 4, when the reading test was performed from the antenna side on one side, it was confirmed that only one could be read and that it was magnetically shielded by the magnetic material. As a comparison with Example 4, it was confirmed that when a total of two IC chips were mounted on the antennas on both sides of the stacked antenna of Example 1, two ICs could be read at the same time.

The laminated antenna obtained by the present invention can be miniaturized, improved in performance, and reduced in cost by laminating a wiring pattern formed of a conductive paste with an insulating coat layer sandwiched between them. These stacked antennas can be used for RFID communication antennas, electromagnetic transfer type antennas, and the like.

1, 2, 3 Stacked antennas 20, 30 Through holes 11, 21, 31 Insulation bases 12, 22, 32 Adhesive layers 13, 23, 33 Wiring patterns 14, 24, 34 Insulation coat layers 15, 25, 35 Through holes 16, 26, 36 Antenna coil 37 Magnetic material 38 Double-sided tape

Claims (12)

A laminated antenna in which a plurality of wiring patterns formed of conductive paste are laminated on both sides of an insulating substrate with an insulating coat layer having through holes interposed therebetween, and the wiring patterns are connected via the through holes. A laminated antenna characterized in that the insulating coat layer is a cured product of a resin containing the following (A) to (E).
(A) Polyester resin (B) Plate-like inorganic filler (C) Fused silica (D) Rubber phase (E) Epoxy resin The laminated antenna according to claim 1, wherein the acid value of the polyester resin is 800 to 2500 equivalents per ton of the resin. The laminated antenna according to claim 1 or 2, wherein the conductive paste contains conductive particles, a binder resin, and a solvent, and the conductive particles contain copper or copper as a main component. The stacked antenna according to any one of claims 1 to 3, wherein the wiring pattern is a plane spiral coil pattern, and the coil patterns are connected via through holes to form an antenna coil. The laminated antenna according to any one of claims 1 to 4, wherein the insulating substrate is a magnetic material. The laminated antenna according to any one of claims 1 to 4, wherein the insulating substrate is a resin film. The stacked antenna according to any one of claims 1 to 6, wherein a wiring pattern is formed on an insulating substrate via an adhesive layer. The laminated antenna according to any one of claims 1 to 7, wherein the weight loss by heating after curing of the adhesive layer is 25% by weight or less in 10 minutes under a superheated steam atmosphere at 300 ° C. Any of claims 1 to 8 in which a through hole is formed in the insulating substrate, and a wiring pattern formed on one surface of the insulating substrate and a wiring pattern formed on the other surface are connected via the through hole. The laminated antenna described in. A wiring pattern is formed by printing a conductive paste on an insulating substrate, and a pattern of an insulating coating layer having an opening that becomes a through hole on the wiring pattern by printing an insulating coating agent containing the following (A) to (E). A method for manufacturing a laminated antenna, which comprises forming a wiring pattern including filling of through holes by printing a conductive paste on the insulating coating layer.
(A) Polyester resin (B) Plate-like inorganic filler (C) Fused silica (D) Rubber phase (E) Epoxy resin The method for manufacturing a laminated antenna according to claim 10, wherein the conductive paste is heat-treated at 130 ° C. or higher to form a wiring pattern. The method for manufacturing a laminated antenna according to claim 10 or 11, wherein the insulating coating agent is cured by heat treatment at 120 ° C. or higher to form an insulating coating layer.

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