Electronic component and method for manufacturing the same

Abstract

To provide an electronic component with high adhesive strength and a manufacturing method thereof, facilitating a formation of metal wiring and a mounting of electronic elements.SOLUTION: A manufacturing method of an electronic component according to the present invention includes a first step of applying a metal paste containing metal particles in a predetermined pattern onto a polymer molded body to form a metal paste layer, a second step of forming metal wiring by sintering the metal particles, a third step of applying a solder paste containing solder particles and a resin component onto the metal wiring to form a solder paste layer, a fourth step of placing an electronic element on the solder paste layer, and a fifth step of heating the solder paste layer to form a solder layer that joins the metal wiring and the electronic element, and a resin layer that covers at least a portion of the solder layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an electronic component and a method for manufacturing the same.

Background Art

[0002] In recent years, a method of forming a metal layer by plating has been studied for the purpose of functional and / or decorative surface treatment on the surface of a polymer molded body. For example, when forming metal wiring on a polymer molded body, since it is necessary to form the metal wiring in a predetermined pattern, laser direct structuring (LDS) is useful as a method of selectively plating metal. For example, when forming copper wiring by LDS, by irradiating a laser to a portion of the polymer molded body containing a catalyst where the copper wiring is to be formed to activate the catalyst, electroless copper plating can be selectively applied (only to the portion where the copper wiring is to be formed) to the catalyst, and as a result, copper wiring having a predetermined pattern can be formed (for example, Patent Document 1). On the other hand, a method has been proposed in which a paste containing copper is applied onto a polymer molded body and fired to easily form copper wiring (for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the method of forming copper wiring by LDS, since the polymer containing a catalyst is expensive and the processes of laser irradiation and electroless copper plating are required, there are problems in terms of productivity. On the other hand, in the method of easily forming metal wiring by applying a metal paste on a polymer molded body and firing it, sufficient adhesiveness between the polymer molded body and the metal wiring cannot be obtained, and the adhesive strength of electronic components tends to decrease.

[0005] Therefore, one aspect of the present invention aims to provide an electronic component with high adhesive strength and a method for manufacturing the electronic component, which can easily form metal wiring and mount electronic elements.

Means for Solving the Problems

[0006] One aspect of the present invention includes a first step of applying a metal paste containing metal particles on a polymer molded body in a predetermined pattern to form a metal paste layer; a second step of forming metal wiring by sintering the metal particles; a third step of applying a solder paste containing solder particles and a resin component on the metal wiring to form a solder paste layer; a fourth step of disposing an electronic element on the solder paste layer; and a fifth step of heating the solder paste layer to form a solder layer that joins the metal wiring and the electronic element, and forming a resin layer that covers at least a part of the solder layer. It is a method for manufacturing an electronic component.

[0007] In this manufacturing method, since the metal paste is applied in a predetermined pattern (a pattern corresponding to the metal wiring), a polymer containing a catalyst is unnecessary, and the processes of laser irradiation and electroless copper plating can be omitted. In addition, in this manufacturing method, after applying a solder paste on the metal wiring formed by firing the metal paste and disposing an electronic element, the solder paste is heat-treated, so that the metal wiring and the electronic element are joined via a solder layer, and a resin layer is formed on the outer periphery of the solder layer, thereby improving the adhesiveness between the polymer molded body and the metal wiring.

[0008] In the second step, the metal wiring may have voids. In the third step, at least a part of the voids in the metal wiring may be filled with a resin component.

[0009] The solder particles may be a component containing tin. The solder particles may be an alloy composed of an In-Sn alloy, an In-Sn-Ag alloy, a Sn-Bi alloy, a Sn-Bi-Ag alloy, a Sn-Ag-Cu alloy, or a Sn-Cu alloy.

[0010] The metal particles may be composed of at least one metal selected from the group consisting of copper, nickel, palladium, gold, platinum, silver, and tin. The metal particles may include first metal particles having a particle size of 2.0 μm or more and second metal particles having a particle size of 0.8 μm or less.

[0011] The polymer molded body may be made of a liquid crystal polymer or polyphenylene sulfide.

[0012] The electronic element has an electrode containing at least one selected from the group consisting of copper, nickel, palladium, gold, platinum, silver, and tin on the outermost surface, and in the fourth step, the electronic element may be arranged so that the electrode is in contact with the solder paste layer.

[0013] Another aspect of the present invention is an electronic component including a polymer molded body, a metal wiring provided on the polymer molded body and composed of a sintered body of metal particles, an electronic element disposed on the metal wiring, a solder layer for joining the metal wiring and the electronic element, and a resin layer composed of a cured product of a resin component covering at least a part of the solder layer.

Advantages of the Invention

[0014] According to one aspect of the present invention, the formation of the metal wiring and the mounting of the electronic element can be easily performed, and good adhesiveness between the metal wiring and the polymer molded body can be obtained.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

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Figure 13

Mode for Carrying Out the Invention

[0016] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and duplicate explanations are omitted.

[0017] The manufacturing method of the electronic component of the present embodiment includes: a first step of forming a metal paste layer by applying a metal paste containing metal particles on a polymer molded body in a predetermined pattern; a second step of forming a metal wiring by sintering the metal particles; a third step of forming a solder paste layer by applying a solder paste containing solder particles and a resin component on the metal wiring; a fourth step of disposing an electronic element on the solder paste layer; and a fifth step of heating the solder paste layer to form a solder layer that joins the metal wiring and the electronic element, and forming a resin layer that covers at least a part of the solder layer.

[0018] The metal particles preferably contain at least one metal selected from the group consisting of copper, nickel, palladium, gold, platinum, silver, and tin. Since sintering easily occurs at a low temperature, the metal particles preferably contain copper or silver, and more preferably contain copper from the viewpoint of suppressing migration when forming fine wiring. Considering firing at a low temperature and the cost of materials, it is more preferable to use silver-coated copper particles as the metal particles. The metal particles may be used alone or in combination of two or more. Further, the metal particles may contain two or more types of metal particles having different particle sizes. For example, the metal particles may contain first metal particles having a particle size of 2.0 μm or more and second metal particles having a particle size of 0.8 μm or less.

[0019] FIG. 1 is a schematic diagram showing a manufacturing method of an electronic component according to an embodiment. The case where copper particles are used as the metal particles for forming the metal wiring will be described. In this manufacturing method, first, a copper paste containing copper particles is applied on a polymer molded body in a predetermined pattern to form a metal (copper) paste layer (the first step). In the first step, first, as shown in FIG. 1(a), a polymer molded body 1 is prepared (preparation step).

[0020] The polymer molded body 1 is a molded body formed by a known method using a polymer such as polyamide (PA), polybutylene terephthalate (PBT), polycarbonate (PC), polyetherimide (PI), polyphenylene sulfide (PPS), polyetheretherketone (PEEK), liquid crystal polymer (LCP), etc. The shape and size of the polymer molded body are arbitrary. The polymer molded body 1 preferably consists of a liquid crystal polymer (LCP) or polyphenylene sulfide (PPS).

[0021] (First step) In the first step, following the preparation step, as shown in FIG. 1(b), a copper paste is applied in a predetermined pattern (to the portion where the copper wiring is to be formed) on the polymer molded body 1 to form a copper paste layer 2 (formation step). The copper paste is applied, for example, by screen printing, transfer printing, offset printing, jet printing method, dispenser, jet dispenser, needle dispenser, comma coater, slit coater, die coater, gravure coater, slit coat, letterpress printing, intaglio printing, gravure printing, stencil printing, soft lithography, bar coater, applicator, particle deposition method, spray coater, spin coater, dip coater, electroplating, etc.

[0022] The thickness of the copper paste layer may be 1 μm or more, 2 μm or more, 3 μm or more, 5 μm or more, 10 μm or more, 15 μm or more, or 20 μm or more, and may be 3000 μm or less, 1000 μm or less, 500 μm or less, 300 μm or less, 250 μm or less, 200 μm or less, 150 μm or less, or 100 μm or less.

[0023] In the forming process, from the viewpoint of suppressing the flow of copper particles during sintering and the generation of voids, the copper paste layer 2 provided on the polymer molded body 1 may be appropriately dried. The gas atmosphere during drying may be in the air, in an oxygen-free atmosphere such as nitrogen or noble gas, or in a reducing atmosphere such as hydrogen or formic acid. The drying method may be drying by leaving at room temperature, heating drying, or vacuum drying. For heating drying or vacuum drying, for example, a hot plate, a hot air dryer, a hot air heating furnace, a nitrogen dryer, an infrared dryer, an infrared heating furnace, a far-infrared heating furnace, a microwave heating device, a laser heating device, an electromagnetic heating device, a heater heating device, a steam heating furnace, a hot plate press device, etc. can be used. The drying temperature and time may be appropriately adjusted according to the type and amount of the dispersion medium used. The drying temperature may be, for example, 50°C or higher and 180°C or lower. The drying time may be, for example, 1 minute or longer and 120 minutes or shorter.

[0024] The copper paste contains, as copper particles, for example, first copper particles having a particle size (maximum diameter) of 2.0 μm or more. The particle size (maximum diameter) of the first copper particles is 2.0 μm or more, and may be, for example, 3.0 μm or more. The particle size of the first copper particles may be 20 μm or less, or may be 10 μm or less. The average particle size (average maximum diameter) of the first copper particles may be 1.0 μm or more or 3 μm or more, and may be 20 μm or less or 10 μm or less from the viewpoint of further suppressing disconnection due to thermal stress of the resulting wiring.

[0025] The particle size and average particle size of the first copper particles can be obtained, for example, from the SEM image of the particles. A method for calculating the particle size (maximum diameter) of the first copper particles from the SEM image will be exemplified. The powder of the first copper particles is placed on a carbon tape for SEM with a spatula to form a sample for SEM. This sample for SEM is observed at 5000 times with an SEM apparatus. A rectangle circumscribing the first copper particles in the SEM image is drawn by image processing software, and the long side of the rectangle is taken as the particle size (maximum diameter) of the particle. Using a plurality of SEM images, this measurement is performed on 50 or more first copper particles, and the average value (average maximum diameter) of the particle sizes is calculated.

[0026] The volume average particle diameter of the first copper particles may be 2.0 μm or more, or 3.0 μm or more, and may be 50 μm or less, 20 μm or less, or 10 μm or less. In the present specification, the volume average particle diameter means the 50% volume average particle diameter. When determining the volume average particle diameter of the copper particles, copper particles as raw materials or dried copper particles from which volatile components have been removed from the copper paste are dispersed in a dispersion medium using a dispersant, and are measured by a light scattering method particle size distribution measuring device (for example, a method of measuring with a Shimadzu nanoparticle size distribution measuring device (trade name: SALD-7500nano, manufactured by Shimadzu Corporation)). When using a light scattering method particle size distribution measuring device, hexane, toluene, α-terpineol, etc. can be used as the dispersion medium.

[0027] The first copper particles are preferably flake-shaped. In this case, when the first copper particles are oriented substantially parallel to the coating surface of the copper paste, volume shrinkage when sintering the copper particles in the copper paste is suppressed, and disconnection due to thermal stress of the resulting wiring is more suppressed. Also, although the reason is not clear, the adhesion between the copper wiring and the polymer molded body is further improved.

[0028] The aspect ratio of the first copper particles may be 4 or more, or may be 6 or more. If the aspect ratio is within the above range, the first copper particles in the copper paste are likely to be oriented parallel to the coating surface of the copper paste, and volume shrinkage when sintering the copper particles in the copper paste can be suppressed. Therefore, disconnection due to thermal stress of the resulting wiring can be further suppressed. The aspect ratio (major axis / minor axis) of the copper particles in the copper paste can be determined, for example, by observing the SEM image of the particles and measuring the major axis and the minor axis.

[0029] The copper paste preferably contains first copper particles having a particle diameter of 2.0 μm or more and 50 μm or less and an aspect ratio of 4 or more. If the average particle diameter and aspect ratio of the first copper particles are within the above ranges, volume shrinkage when sintering the copper particles in the copper paste can be sufficiently reduced, and disconnection due to thermal stress of the resulting wiring can be more suppressed.

[0030] The copper paste may contain copper particles having a particle size of 2.0 μm or more and 50 μm or less and an aspect ratio of less than 2. However, the content of the copper particles having a particle size of 2.0 μm or more and 50 μm or less and an aspect ratio of less than 2 is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, based on 100 parts by mass of the first copper particles having a particle size of 2.0 μm or more and 50 μm or less and an aspect ratio of 4 or more. By limiting the content of the copper particles having an average particle size of 2.0 μm or more and 50 μm or less and an aspect ratio of less than 2, the first copper particles in the copper paste are more likely to be oriented substantially parallel to the coating surface of the copper paste, and the volume shrinkage when the copper particles in the copper paste are sintered can be more effectively suppressed. Thereby, it becomes easier to suppress disconnection due to thermal stress of the obtained wiring. In terms of making such an effect more easily obtained, the content of the copper particles having an average particle size of 2.0 μm or more and 50 μm or less and an aspect ratio of less than 2 may be 20 parts by mass or less, 10 parts by mass or less, or even 0 parts by mass, based on 100 parts by mass of the first copper particles having a particle size of 2.0 μm or more and 50 μm or less and an aspect ratio of 4 or more.

[0031] The content of the first copper particles in the copper paste may be 1% by mass or more, 10% by mass or more, or 20% by mass or more, and may be 90% by mass or less, 70% by mass or less, or 50% by mass or less, based on the total mass of the metal particles contained in the copper paste. If the content of the first copper particles is within the above range, it becomes easy to form a wiring having excellent conduction reliability.

[0032] The first copper particles may be treated with a surface treatment agent from the viewpoints of dispersion stability and oxidation resistance. The surface treatment agent may be removed during wiring formation (when the copper particles are sintered). Examples of the surface treatment agent include aliphatic carboxylic acids such as palmitic acid, stearic acid, arachidic acid, and oleic acid; aromatic carboxylic acids such as terephthalic acid, pyromellitic acid, and o-phenoxybenzoic acid; aliphatic alcohols such as cetyl alcohol, stearyl alcohol, isobornyl cyclohexanol, and tetraethylene glycol; aromatic alcohols such as p-phenylphenol; alkylamines such as octylamine, dodecylamine, and stearylamine; aliphatic nitriles such as stearonitrile and decanenitrile; silane coupling agents such as alkylalkoxysilane; and polymer treatment agents such as polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, and silicone oligomer. The surface treatment agent may be used alone or in combination of two or more.

[0033] The treatment amount of the surface treatment agent may be an amount of one molecular layer or more on the particle surface. Such a treatment amount of the surface treatment agent varies depending on the specific surface area of the first copper particles, the molecular weight of the surface treatment agent, and the minimum coating area of the surface treatment agent. The treatment amount of the surface treatment agent is usually 0.001 mass% or more.

[0034] The treatment amount of the surface treatment agent is related to the number of molecular layers (n) attached to the surface of the first copper particles, the specific surface area (A p )(unit: m 2 / g) of the first copper particles, the molecular weight (M s )(unit: g / mol) of the surface treatment agent, the minimum coating area (S S )(unit: m 2 / particle) of the surface treatment agent, and Avogadro's number (N A )(6.02×10 23 particles). Specifically, the treatment amount of the surface treatment agent is calculated according to the formula: treatment amount of the surface treatment agent (mass%) = { (n·A p ·M s ) / (S S ·N A + n·A p ·M s )} × 100%.

[0035] The specific surface area of the first copper particles can be calculated by measuring the dried copper particles using the BET specific surface area measurement method. The minimum coating area of the surface treatment agent is 2.05×10 -19 m 2 / molecule when the surface treatment agent is a straight-chain saturated fatty acid. In the case of other surface treatment agents, it can be measured, for example, by calculation from a molecular model or by the method described in "Chemistry and Education" (Katsuhiro Ueda, Sumio Inafuku, Iwao Mori, 40(2), 1992, p114-117). An example of a method for quantifying the surface treatment agent is shown. The surface treatment agent can be identified by thermodesorption gas-gas chromatography-mass spectrometer of the dry powder obtained by removing the dispersion medium from the copper paste, and thereby the carbon number and molecular weight of the surface treatment agent can be determined. The carbon content ratio of the surface treatment agent can be analyzed by carbon analysis. Examples of the carbon analysis method include, for example, high-frequency induction furnace combustion / infrared absorption method. The amount of the surface treatment agent can be calculated from the carbon number, molecular weight, and carbon content ratio of the identified surface treatment agent using the above formula.

[0036] As the first copper particles, commercially available ones can be used. Examples of commercially available first copper particles include MA-C025 (manufactured by Mitsui Mining & Smelting Co., Ltd., average particle size 4.1 μm), 3L3 (manufactured by Fukuda Metal Foil Powder Industry Co., Ltd., average particle size 7.3 μm), 1110F (manufactured by Mitsui Mining & Smelting Co., Ltd., average particle size 5.8 μm), and 2L3 (manufactured by Fukuda Metal Foil Powder Industry Co., Ltd., average particle size 9 μm).

[0037] In the production of the copper paste, first copper particles having a particle size of 2.0 μm or more and 50 μm or less and an aspect ratio of 4 or more are included, and the content of copper particles having a particle size of 2.0 μm or more and 50 μm or less and an aspect ratio of less than 2 is 50 parts by mass or less, preferably 30 parts by mass or less, based on 100 parts by mass of the first copper particles having a particle size of 2.0 μm or more and 50 μm or less and an aspect ratio of 4 or more. Commercially available products composed of such copper particles can be selected and used.

[0038] In one embodiment, the copper paste may include first copper particles and second copper particles having a particle size (maximum diameter) of 0.8 μm or less. In this case, when the copper particles are sintered, the second copper particles are interposed between the first copper particles, and thus the conductivity of the resulting wiring tends to be improved. In particular, when the first copper particles are used as the copper particles, it is preferable to use the first copper particles and the second copper particles in combination. That is, when preparing the copper paste only from the second copper particles, since the volume shrinkage and sintering shrinkage accompanying the drying of the dispersion medium are large, when sintering the copper particles, the sintered body (wiring) is likely to peel off from the adhered surface, and it is difficult to obtain sufficient conduction reliability. However, by using the first copper particles and the second copper particles in combination, the volume shrinkage when sintering the copper paste is suppressed, and the adhesiveness between the resulting wiring and the polymer molded body as the adhered body is improved. Therefore, disconnection due to the thermal stress of the wiring is less likely to occur.

[0039] The second copper particles act as copper particles that preferably join between the first copper particles. In addition, the second copper particles are superior in sinterability to the first copper particles and have a function of promoting the sintering of the copper particles. For example, compared with the case where the first copper particles are used alone, it becomes possible to sinter the copper particles at a lower temperature.

[0040] The particle size of the second copper particles may be 0.5 μm or less, 0.4 μm or less, or 0.3 μm or less. The particle size of the second copper particles may be 0.01 μm or more, 0.05 μm or more, 0.1 μm or more, or 0.2 μm or more. The average particle size of the second copper particles may be 0.01 μm or more, 0.05 μm or more, 0.1 μm or more, or 0.2 μm or more, and may be 0.8 μm or less, 0.5 μm or less, 0.4 μm or less, or 0.3 μm or less.

[0041] The volume average particle diameter of the second copper particles may be 0.01 μm or more and may be 0.8 μm or less. If the volume average particle diameter of the second copper particles is 0.01 μm or more, effects such as suppression of the synthesis cost of the second copper particles, good dispersibility, and suppression of the amount of the surface treatment agent used are likely to be obtained. If the volume average particle diameter of the second copper particles is 0.8 μm or less, an effect that the second copper particles are excellent in sinterability is likely to be obtained. From the viewpoint of further achieving the above effects, the volume average particle diameter of the second copper particles may be 0.05 μm or more, 0.1 μm or more, or 0.2 μm or more, and may be 0.5 μm or less, 0.4 μm or less, or 0.3 μm or less.

[0042] The second copper particles may contain 10% by mass or more of copper particles having a particle diameter of 0.01 μm or more and 0.8 μm or less. From the viewpoint of the sinterability of the copper paste, the second copper particles may contain 20% by mass or more, 30% by mass or more, or 100% by mass of copper particles having a particle diameter of 0.01 μm or more and 0.8 μm or less. When the content ratio of the copper particles having a particle diameter of 0.01 μm or more and 0.8 μm or less in the second copper particles is 20% by mass or more, the dispersibility of the copper particles is further improved, and an increase in viscosity and a decrease in paste concentration can be further suppressed.

[0043] The content of the second copper particles in the copper paste may be 20% by mass or more, 30% by mass or more, 35% by mass or more, or 40% by mass or more, and may be 90% by mass or less, 85% by mass or less, or 80% by mass or less based on the total mass of the metal particles contained in the copper paste. If the content of the second copper particles is within the above range, disconnection due to thermal stress of the obtained wiring is less likely to occur.

[0044] The content of the second copper particles in the copper paste may be 20% by mass or more and 90% by mass or less based on the total mass of the first copper particles and the second copper particles. If the content of the second copper particles is 20% by mass or more, the space between the first copper particles can be sufficiently filled, and disconnection due to thermal stress of the resulting wiring is less likely to occur. If the content of the second copper particles is 90% by mass or less, volume shrinkage during sintering of the copper particles can be sufficiently suppressed, and disconnection due to thermal stress of the resulting wiring is less likely to occur. From the viewpoint of further achieving the above effects, the content of the second copper particles may be 30% by mass or more, 35% by mass or more, or 40% by mass or more, and may be 85% by mass or less or 80% by mass or less based on the total mass of the first copper particles and the second copper particles.

[0045] The shape of the second copper particles may be, for example, spherical, massive, needle-like, flaky, substantially spherical, etc. The second copper particles may be an aggregate of copper particles having these shapes. From the viewpoints of dispersibility and fillability, the shape of the second copper particles may be spherical, substantially spherical, or flaky, and from the viewpoints of flammability and miscibility with the first copper particles, etc., it may be spherical or substantially spherical.

[0046] The aspect ratio of the second copper particles may be 5 or less, and may also be 3 or less from the viewpoints of dispersibility, fillability, and miscibility with the first copper particles.

[0047] The second copper particles may be treated with a specific surface treatment agent. Examples of the specific surface treatment agent include organic acids having 8 to 16 carbon atoms. Examples of the organic acids having 8 to 16 carbon atoms include caprylic acid, methylheptanoic acid, ethylhexanoic acid, propylpentanoic acid, pelargonic acid, methyloctanoic acid, ethylheptanoic acid, propylhexanoic acid, capric acid, methylnonanoic acid, ethyloctanoic acid, propylheptanoic acid, butylhexanoic acid, undecanoic acid, methyldecanoic acid, ethyldecanoic acid, propyloctanoic acid, butylheptanoic acid, lauric acid, methylundecanoic acid, ethyldecanoic acid, propylnonanoic acid, butyloctanoic acid, pentylheptanoic acid, tridecanoic acid, methyldodecanoic acid, ethylundecanoic acid, propyldecanoic acid, butylnonanoic acid, pentyloctanoic acid, myristic acid, methyltridecanoic acid, ethyldodecanoic acid, propylundecanoic acid, butyldecanoic acid, pentylnonanoic acid, hexyl octanoic acid, pentadecanoic acid, methyltetradecanoic acid, ethyltridecanoic acid, propyldodecanoic acid, butylundecanoic acid, pentyl decanoic acid, hexylnonanoic acid, palmitic acid, methylpentadecanoic acid, ethyltetradecanoic acid, propyltridecanoic acid, butyldodecanoic acid, pentylundecanoic acid, hexyl decanoic acid, heptylnonanoic acid, methylcyclohexanecarboxylic acid, ethylcyclohexanecarboxylic acid, propylcyclohexanecarboxylic acid, butylcyclohexanecarboxylic acid, pentylcyclohexanecarboxylic acid, hexylcyclohexanecarboxylic acid, heptylcyclohexanecarboxylic acid, octylcyclohexanecarboxylic acid, nonylcyclohexanecarboxylic acid and other saturated fatty acids; unsaturated fatty acids such as octenoic acid, nonenoic acid, methylnonenoic acid, decenoic acid, undecenoic acid, dodecenoic acid, tridecenoic acid, tetradecenoic acid, myristoleic acid, pentadecenoic acid, hexadecenoic acid, palmitoleic acid, and sabienic acid; aromatic carboxylic acids such as terephthalic acid, pyromellitic acid, o-phenoxybenzoic acid, methylbenzoic acid, ethylbenzoic acid, propylbenzoic acid, butylbenzoic acid, pentylbenzoic acid, hexylbenzoic acid, heptylbenzoic acid, octylbenzoic acid, nonylbenzoic acid. The organic acid may be used alone or in combination of two or more kinds.By combining such an organic acid with the second copper particles, it tends to be possible to achieve both the dispersibility of the second copper particles and the desorbability of the organic acid during sintering.

[0048] The treatment amount of the surface treatment agent may be an amount that adheres to the surface of the second copper particles in a monolayer to a trilayer. The treatment amount of the surface treatment agent may be 0.07% by mass or more, 0.10% by mass or more, or 0.2% by mass or more, and may be 2.1% by mass or less, 1.6% by mass or less, or 1.1% by mass or less. The surface treatment amount of the second copper particles can be calculated by the method described above for the first copper particles. The same applies to the specific surface area, the molecular weight of the surface treatment agent, and the minimum coating area of the surface treatment agent.

[0049] As the second copper particles, commercially available ones can be used. Examples of commercially available second copper particles include CH-0200 (manufactured by Mitsui Mining & Smelting Co., Ltd., volume average particle diameter 0.36 μm), HT-14 (manufactured by Mitsui Mining & Smelting Co., Ltd., volume average particle diameter 0.41 μm), CT-500 (manufactured by Mitsui Mining & Smelting Co., Ltd., volume average particle diameter 0.72 μm), and Tn-Cu100 (manufactured by Taiyo Nippon Sanso Corporation, volume average particle diameter 0.12 μm).

[0050] The total content of the first copper particles and the second copper particles in the copper paste may be 80% by mass or more based on the total mass of the metal particles contained in the copper paste. If the total content of the first copper particles and the second copper particles is within the above range, disconnection due to thermal stress of the resulting wiring is less likely to occur. From the viewpoint of further achieving the above effects, the total content of the first copper particles and the second copper particles may be 90% by mass or more, 95% by mass or more, or 100% by mass based on the total mass of the metal particles.

[0051] The copper paste may further contain other metal particles other than copper particles. Examples of the other metal particles include particles such as nickel, silver, gold, palladium, and platinum. The volume average particle diameter of the other metal particles may be 0.01 μm or more or 0.05 μm or more, and may be 10 μm or less, 5.0 μm or less, or 3.0 μm or less. When the other metal particles are included, the content may be less than 20% by mass, or may be 10% by mass or less, based on the total mass of the metal particles contained in the copper paste, from the viewpoint of obtaining sufficient bonding properties. The other metal particles may not be included. The shape of the other metal particles is not particularly limited.

[0052] By including metal particles other than copper particles, it is possible to obtain a wiring in which a plurality of types of metals are solid-solved or dispersed. Therefore, mechanical properties such as the yield stress and fatigue strength of the wiring are improved, and the conduction reliability is likely to be improved. In addition, by adding a plurality of types of metal particles, the bonding strength of the formed wiring to a specific adherend (for example, LCP) is likely to be improved, and the conduction reliability is likely to be improved.

[0053] The dispersion medium contained in the copper paste is not particularly limited and may be, for example, volatile. Examples of the volatile dispersion medium include monohydric and polyhydric alcohols such as pentanol, hexanol, heptanol, octanol, decanol, ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, α-terpineol, and isobornyl cyclohexanol; ethers such as ethylene glycol butyl ether, ethylene glycol phenyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, diethylene glycol isobutyl ether, diethylene glycol hexyl ether, triethylene glycol methyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol butyl methyl ether, diethylene glycol isopropyl methyl ether, triethylene glycol dimethyl ether, triethylene glycol butyl methyl ether, propylene glycol propyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol propyl ether, dipropylene glycol butyl ether, dipropylene glycol dimethyl ether, tripropylene glycol methyl ether, and tripropylene glycol dimethyl ether; esters such as ethylene glycol ethyl ether acetate, ethylene glycol butyl ether acetate, diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, dipropylene glycol methyl ether acetate (DPMA), ethyl lactate, butyl lactate, γ-butyrolactone, and propylene carbonate; acid amides such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide; aliphatic hydrocarbons such as cyclohexane, octane, nonane, decane, and undecane; aromatic hydrocarbons such as benzene, toluene, and xylene; mercaptans having an alkyl group with 1 to 18 carbon atoms; and mercaptans having a cycloalkyl group with 5 to 7 carbon atoms.Examples of mercaptans having an alkyl group with 1 to 18 carbon atoms include ethyl mercaptan, n-propyl mercaptan, i-propyl mercaptan, n-butyl mercaptan, i-butyl mercaptan, t-butyl mercaptan, pentyl mercaptan, hexyl mercaptan, and dodecyl mercaptan. Examples of mercaptans having a cycloalkyl group with 5 to 7 carbon atoms include cyclopentyl mercaptan, cyclohexyl mercaptan, and cycloheptyl mercaptan.

[0054] The content of the dispersion medium may be 5 parts by mass or more and 50 parts by mass or less, with the total mass of the metal particles contained in the copper paste being 100 parts by mass. If the content of the dispersion medium is within the above range, the copper paste can be adjusted to a more appropriate viscosity, and it is difficult to inhibit the sintering of the copper particles.

[0055] To the copper paste, wetting improvers such as nonionic surfactants and fluorosurfactants; defoamers such as silicone oil; ion trappers such as inorganic ion exchangers, etc. may be appropriately added as needed.

[0056] The above-described copper paste can be prepared by mixing copper particles and optional components (additives, other metal particles, etc.) in a dispersion medium. After mixing each component, a stirring treatment may be performed. The maximum diameter of the dispersion may be adjusted by a classification operation.

[0057] The copper paste may be prepared by previously mixing the second copper particles, a surface treatment agent, and a dispersion medium, performing a dispersion treatment to prepare a dispersion of the second copper particles, and further mixing the first copper particles, other metal particles, and optional additives. By adopting such a procedure, the dispersibility of the second copper particles is improved, the miscibility with the first copper particles is improved, and the performance of the copper paste is further improved. Aggregates may be removed by subjecting the dispersion of the second copper particles to a classification operation.

[0058] (Second step). As shown in FIG. 1(c), the copper wiring 3 is formed by sintering the copper particles.

[0059] Sintering can be carried out by heat treatment. For heat treatment, for example, heating means such as a hot plate, a hot air dryer, a hot air heating furnace, a nitrogen dryer, an infrared dryer, an infrared heating furnace, a far-infrared heating furnace, a microwave heating device, a laser heating device, an electromagnetic heating device, a heater heating device, and a steam heating furnace can be used.

[0060] The atmosphere during sintering may be an oxygen-free atmosphere from the viewpoint of suppressing oxidation of the sintered body, or may be a reducing atmosphere from the viewpoint of removing the surface oxide of the copper particles in the copper paste layer 2. Examples of the oxygen-free atmosphere include introduction of an oxygen-free gas such as nitrogen or a noble gas, or under vacuum. Examples of the reducing atmosphere include in pure hydrogen gas, in a mixed gas of hydrogen and nitrogen typified by forming gas, in nitrogen containing formic acid gas, in a mixed gas of hydrogen and a noble gas, and in a noble gas containing formic acid gas.

[0061] From the viewpoint of reducing thermal damage to each member and improving the yield, the maximum temperature reached during the heat treatment may be 150°C or higher, and may be 350°C or lower, 300°C or lower, or 260°C or lower. If the maximum temperature reached is 150°C or higher, sintering tends to proceed sufficiently when the maximum temperature holding time is 60 minutes or less. From the viewpoint of volatilizing all of the dispersion medium and improving the yield, the maximum temperature holding time may be 1 minute or longer, and may be 60 minutes or less, 40 minutes or less, or 30 minutes or less.

[0062] The copper content (volume ratio) in the copper wiring 3 is preferably 65% by volume or more, more preferably 70% by volume or more, and even more preferably 80% by volume or more, based on the total volume of the copper wiring. By setting the copper content in the copper wiring 3 to 65% by volume or more, good conduction reliability can be obtained. The copper content (volume ratio) in the copper wiring 3 is preferably 95% by volume or less, based on the total volume of the copper wiring. In this case, the copper wiring 3 has voids. When the copper wiring 3 has appropriate voids, when a solder paste containing a resin component is applied to the surface of the copper wiring 3 opposite to the surface in contact with the polymer molded body 1, the resin component is easily filled into the voids inside the copper wiring 3, and the resin also reaches and cures in the void portion 3a between the copper wiring 3 in contact with the polymer molded body, thereby further improving the adhesion strength between the polymer molded body 1 and the copper wiring 3.

[0063] In addition, when the composition of the material constituting the copper wiring 3 is known, for example, the copper content in the copper wiring 3 can be determined by the following procedure. First, the copper wiring 3 is cut out into a rectangular parallelepiped, and the volume of the copper wiring 3 is calculated by measuring the longitudinal and transverse lengths of the copper wiring 3 with a vernier caliper or an external shape measuring device and measuring the thickness with a film thickness gauge. The apparent density M1 (g / cm 3 ) is obtained from the volume of the cut-out copper wiring 3 and the weight of the copper wiring 3 measured with a precision balance. Using the obtained M1 and the density of copper 8.96 g / cm 3 , the copper content (volume %) in the copper wiring 3 can be determined from the following formula (A). Copper content (volume %) in copper wiring 3 = [(M1) / 8.96] × 100 (A)

[0064] The copper wiring 3 may have a copper element ratio of 95% by mass or more, 97% by mass or more, 98% by mass or more, or 100% by mass among the elements excluding light elements among the constituent elements. If the above ratio of the copper element in the copper wiring 3 is within the above range, the formation of intermetallic compounds or the precipitation of foreign elements at the grain boundaries of metallic copper crystals can be suppressed, the properties of the metallic copper constituting the copper wiring 3 tend to be strengthened, and more excellent connection reliability is likely to be obtained. Further, when the ratio of the copper element among the elements excluding light elements in the copper wiring 3 is 100% by mass, the above volume ratio of copper can be regarded as the density (%).

[0065] The copper wiring 3 preferably includes a structure derived from first copper particles oriented substantially parallel to the bonding interface with the polymer molded body 1 (for example, the bonding surface between the polymer molded body 1 and the copper wiring 3). In this case, by orienting the first particles substantially parallel to the polymer molded body 1, cracking of the copper wiring 3 formed by sintering can be suppressed. Further, although the reason is not clear, the adhesiveness between the copper wiring 3 formed by sintering and the polymer molded body 1 can be improved.

[0066] (The third step) Subsequent to the second step, as shown in Fig. 1(d), a solder paste containing solder particles 4 and a resin component 5 is applied onto the copper wiring 3 in a predetermined pattern to form a solder paste layer 6. A part of the resin component 5 penetrates into the voids 3a of the copper wiring 3 to form a resin-filled portion 7 filled in at least a part of the copper wiring 3.

[0067] The particle size of the solder particles 4 may be, for example, 0.4 to 30 μm, 0.5 to 20 μm, or 0.6 to 15 μm. When the particle size of the solder particles 4 is 0.4 μm or more, it is less likely to be affected by oxidation of the solder surface, and it is easier to improve conduction reliability. On the other hand, when the particle size of the solder particles 4 is 30 μm or less, it is easier to improve insulation reliability.

[0068] The particle size of the solder particles 4 can be measured by observation using a scanning electron microscope (SEM). That is, the average particle size of the solder particles is obtained by measuring the particle sizes of any 300 solder particles by observation using SEM and taking their average value.

[0069] The solder particles 4 contain tin. As the solder particles 4, at least one tin alloy selected from the group consisting of In-Sn alloy, In-Sn-Ag alloy, Sn-Bi alloy, Sn-Bi-Ag alloy, Sn-Ag-Cu alloy, and Sn-Cu alloy may be used. Examples of the tin alloy include In-Sn (In 52% by mass, Bi 48% by mass, melting point 118°C), In-Sn-Ag (In 20% by mass, Sn 77.2% by mass, Ag 2.8% by mass, melting point 175°C), Sn-Bi (Sn 43% by mass, Bi 57% by mass, melting point 138°C), Sn-Bi-Ag (Sn 42% by mass, Bi 57% by mass, Ag 1% by mass, melting point 139°C), Sn-Ag-Cu (Sn 96.5% by mass, Ag 3% by mass, Cu 0.5% by mass, melting point 217°C), and Sn-Cu (Sn 99.3% by mass, Cu 0.7% by mass, melting point 227°C).

[0070] The tin alloy can be selected according to the bonding temperature. For example, when using a tin alloy with a low melting point such as In-Sn alloy or Sn-Bi alloy, bonding can be performed at 150°C or lower. When using a tin alloy with a high melting point such as Sn-Ag-Cu or Sn-Cu, a high reliability tends to be achieved even after high-temperature standing.

[0071] The tin alloy constituting the solder particles 4 may contain at least one selected from Ag, Cu, Ni, Bi, Zn, Pd, Pb, Au, P, and B. Among these elements, Ag or Cu may be contained from the following viewpoints. That is, when the solder particles 4 contain Ag or Cu, the melting point of the solder particles can be lowered to about 220°C, and the bonding strength with the electrode is improved, resulting in good conduction reliability.

[0072] The Cu content of the solder particles 4 may be, for example, 0.05 to 10% by mass, 0.1 to 5% by mass, or 0.2 to 3% by mass. If the Cu content is 0.05% by mass or more, it is easy to obtain good solder connection reliability. If the Cu content is 10% by mass or less, the melting point of the solder particles becomes low, the solder wettability is improved, and as a result, the connection reliability of the joint is likely to be good.

[0073] The Ag content of the solder particles 4 may be, for example, 0.05 to 10% by mass, 0.1 to 5% by mass, or 0.2 to 3% by mass. If the Ag content is 0.05% by mass or more, it is easy to obtain good solder connection reliability. On the other hand, if it is 10% by mass or less, the melting point becomes low, the solder wettability is improved, and as a result, the connection reliability of the joint is likely to be good.

[0074] The resin component 5 may contain a thermosetting compound. Examples of the thermosetting compound include an oxetane compound, an epoxy compound, an episulfide compound, a (meth)acrylic compound, a phenol compound, an amino compound, an unsaturated polyester compound, a polyurethane compound, a silicone compound, and a polyimide compound. Among them, an epoxy compound is preferable from the viewpoint of further improving the curability and viscosity of the resin component and further enhancing the adhesiveness between the polymer molded body 1 and the copper wiring 3.

[0075] The resin component 5 may further contain a curing agent. Examples of the curing agent include an imidazole curing agent, an amine curing agent, a phenol curing agent, a polythiol curing agent, an acid anhydride, a thermal cation initiator, and a thermal radical generator. The curing agent may be used alone or in combination of two or more. From the viewpoint of being able to cure quickly at a low temperature, an imidazole curing agent, a polythiol curing agent, or an amine curing agent is preferable. Also, from the viewpoint of enhancing the storage stability when the thermosetting compound and the curing agent are mixed, a latent curing agent may be used as the curing agent. The latent curing agent is preferably a latent imidazole curing agent, a latent polythiol curing agent, or a latent amine curing agent. Note that the above curing agent may be coated with a polymer substance such as a polyurethane resin or a polyester resin.

[0076] Examples of the imidazole curing agent include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, and 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct.

[0077] Examples of the polythiol curing agent include trimethylolpropane tris-3-mercaptopropionate, pentaerythritol tetrakis-3-mercaptopropionate, and dipentaerythritol hexa-3-mercaptopropionate. The solubility parameter of the polythiol curing agent is preferably 9.5 or more and preferably 12 or less. The solubility parameter is calculated by the Fedors method. For example, the solubility parameter of trimethylolpropane tris-3-mercaptopropionate is 9.6, and the solubility parameter of dipentaerythritol hexa-3-mercaptopropionate is 11.4.

[0078] Examples of the amine curing agent include hexamethylenediamine, octamethylenediamine, decamethylenediamine, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraspiro[5.5]undecane, bis(4-aminocyclohexyl)methane, metaphenylenediamine, and diaminodiphenylsulfone.

[0079] Examples of the thermal cationic curing agent include iodonium-based cationic curing agents, oxonium-based cationic curing agents, and sulfonium-based cationic curing agents. Examples of the iodonium-based cationic curing agent include bis(4-tert-butylphenyl)iodonium hexafluorophosphate. Examples of the oxonium-based cationic curing agent include trimethyloxonium tetrafluoroborate. Examples of the sulfonium-based cationic curing agent include tri-p-tolylsulfonium hexafluorophosphate.

[0080] Examples of the thermal radical generator include azo compounds and organic peroxides. Examples of the azo compound include azobisisobutyronitrile (AIBN). Examples of the organic peroxide include di-tert-butyl peroxide and methyl ethyl ketone peroxide.

[0081] The resin component 5 may further contain a flux. The flux melts the oxide on the solder surface, causes the particles to fuse together, and improves the solder wettability to the copper wiring 3.

[0082] As the flux, those generally used for solder bonding or the like can be used. Examples of the flux include zinc chloride, a mixture of zinc chloride and an inorganic halide, a mixture of zinc chloride and an inorganic acid, a molten salt, phosphoric acid, a derivative of phosphoric acid, an organic halide, hydrazine, an organic acid, and rosin. The flux may be used alone or in combination of two or more.

[0083] Examples of the molten salt include ammonium chloride. Examples of the organic acid include lactic acid, citric acid, stearic acid, glutamic acid, and glutaric acid. Examples of the rosin include activated rosin and non-activated rosin. Rosin is rosins mainly composed of abietic acid. By using an organic acid or rosin having two or more carboxyl groups as the flux, the effect that the conduction reliability between electrodes becomes even higher is exhibited.

[0084] The melting point of the flux is preferably 50°C or higher, more preferably 70°C or higher, still more preferably 80°C or higher. The melting point of the flux is preferably 200°C or lower, more preferably 160°C or lower, still more preferably 150°C or lower, and particularly preferably 140°C or lower. When the melting point of the flux is within the above range, the flux effect is more effectively exerted, and the solder particles are more efficiently arranged on the electrodes. The melting point range of the flux is preferably 80 to 190°C, and more preferably 80 to 140°C or lower.

[0085] Examples of fluxes having a melting point in the range of 80 to 190°C include dicarboxylic acids such as succinic acid (melting point 186°C), glutaric acid (melting point 96°C), adipic acid (melting point 152°C), pimelic acid (melting point 104°C), and suberic acid (melting point 142°C), benzoic acid (melting point 122°C), and malic acid (melting point 130°C).

[0086] (Fourth step) Subsequent to the third step, as shown in Fig. 1(e), an electronic device 8 having an electrode 9 is placed (mounted) at a predetermined position of the solder paste layer 6 (fourth step). Examples of the electronic device 8 include power modules composed of diodes, rectifiers, thyristors, MOS gate drivers, power switches, power MOSFETs, IGBTs, Schottky diodes, fast recovery diodes, etc., transmitters, amplifiers, LED modules, capacitors, gyro sensors, etc.

[0087] Examples of the method of placing the electronic device 8 on the solder paste layer 6 include methods using a chip mounter, a flip chip bonder, a positioning jig made of carbon or ceramics, etc.

[0088] The electrode 9 may be an electrode containing at least one metal selected from the group consisting of copper, nickel, palladium, gold, platinum, silver, and tin on its outermost surface. From the viewpoint of enabling highly reliable mounting without forming impurities (intermetallic compounds) between the solder layer 11 and the electrode 9 even after high-temperature storage, it is preferably an electrode containing at least one metal selected from the group consisting of copper, nickel, and palladium on its outermost surface. The electrode 9 may be composed of a single-layer or multi-layer metal-containing layer containing these metals.

[0089] (Fifth step) Subsequent to the fourth step, as shown in Fig. 1(f), the solder particles 4 are melted to form the solder layer 11, and the copper wiring 3 and the electrode 9 of the electronic element 8 are joined (fifth step). Thereby, the electronic component 10 is obtained.

[0090] As a method for melting the solder particles 4, it can be carried out by heat treatment. For heat treatment, for example, heating means such as a hot plate, a hot air dryer, a hot air heating furnace, a nitrogen dryer, an infrared dryer, an infrared heating furnace, a far-infrared heating furnace, a microwave heating device, a laser heating device, an electromagnetic heating device, a heater heating device, and a steam heating furnace can be used.

[0091] The solder particles 4 are melted to form the solder layer 11, the copper wiring 3 and the electrode 9 of the electronic element 8 are joined, and the resin component 5 is cured to form a resin layer 12 covering at least a part of the solder layer 11. Specifically, taking Sn-Bi (Sn 43% by mass, Bi 57% by mass) with a melting point of 138°C as an example, by holding at 150°C, the solder layer 11 is formed, and the resin component 5 covers the outer peripheral portion of the solder layer 11 and cures to become the resin layer 12. At this time, the resin component filled in at least a part of the void portion 3a of the copper wiring 3 is cured to form a resin filling portion 13.

[0092] The atmosphere during soldering may be an oxygen-free atmosphere from the viewpoint of suppressing oxidation of the sintered body, or may be a reducing atmosphere from the viewpoint of removing the surface oxide of the copper wiring 3. Examples of the oxygen-free atmosphere include introduction of an oxygen-free gas such as nitrogen or a noble gas, or under vacuum. Examples of the reducing atmosphere include in pure hydrogen gas, in a mixed gas of hydrogen and nitrogen typified by forming gas, in nitrogen containing formic acid gas, in a mixed gas of hydrogen and a noble gas, in a noble gas containing formic acid gas, and the like.

[0093] The maximum temperature reached during the heat treatment may be 150°C or higher, 350°C or lower, 300°C or lower, or 260°C or lower from the viewpoint of reducing thermal damage to each member and improving the yield. If the maximum temperature reached is 150°C or higher, the melting of the solder particles 4 tends to proceed sufficiently when the maximum temperature holding time is 60 minutes or less.

[0094] The soldering may be performed with pressure applied to the electronic element 8, or may be performed only by the self-weight of the electronic element 8 and other members on the solder paste layer 6. The pressure may be 0.01 MPa or less or 0.005 MPa or less. If the pressure received during sintering is within the above range, a special pressurizing device is not required, so that the yield is not impaired, and the reduction of voids, the bonding strength, and the connection reliability can be further improved. Examples of the method of applying pressure to the electronic element 8 include a method of placing a weight on the uppermost electronic element 8.

[0095] The electronic component 10 obtained by the manufacturing method described above includes a polymer molded body 1, a copper wiring 3 provided on the polymer molded body 1, a solder layer 11 that joins the copper wiring 3 and the electronic element 8, and a resin layer 12 that covers at least a part of the solder layer 11. At least a part of the void portion 3a of the copper wiring 3 is filled with a cured product of the same resin component as the resin layer 12.

[0096] Figure 2 is a diagram showing details of the joint portion between the copper wiring 3 and the polymer molded body 1 in the electronic component 10. A void portion 3a of the copper wiring 3 is formed at the interface with the polymer molded body 1, and the void portion 3a is filled with a resin component and cured to form a resin-filled portion 13, thereby making it possible to improve the adhesiveness between the copper wiring 3 and the polymer molded body 1.

[0097] Figure 3 is a schematic cross-sectional view showing a method of manufacturing an electronic component according to another embodiment. Hereinafter, this embodiment will be described, but descriptions overlapping with those of the above-described embodiment will be omitted. In this manufacturing method, in the preparation step of the first step, as shown in Fig. 3(a), a polymer molded body 1 is prepared (preparation step). In the first step, following the preparation step, as shown in Fig. 3(b), a copper paste is applied on the polymer molded body 1 in a predetermined pattern (to the portion where the copper wiring is to be formed) to form a copper paste layer 2 (forming step). Then, as shown in Fig. 3(c), the copper particles are sintered to form the copper wiring 3 (second step).

[0098] Subsequently, as shown in Fig. 3(d), a resin layer 14 containing a resin component is formed on a part of the copper wiring 3. The resin component is filled in at least a part of the void portion 3a of the copper wiring 3 to obtain a resin-filled portion 15. The resin component may be the same as the resin component 5 of the solder paste described above. When the resin component and the resin component 5 are the same, the resin layer 14 may be applied to the entire surface of the copper wiring 3 and the polymer molded body 1. A solder paste containing solder particles 4 and a resin component 5 may be applied on the upper part of the resin layer 14 applied on the copper wiring 3. The resin layer 14 may or may not be formed and pre-cured at locations other than the copper wiring 3 to which the electronic element 8 is to be joined. The atmosphere during the curing of the resin layer 14 may be an oxygen-free atmosphere or a reducing atmosphere from the viewpoint of suppressing the oxidation of the copper wiring 3. Examples of the oxygen-free atmosphere include introduction of oxygen-free gases such as nitrogen and rare gases, or under vacuum. Examples of the reducing atmosphere include in pure hydrogen gas, in a mixed gas of hydrogen and nitrogen typified by forming gas, in nitrogen containing formic acid gas, in a mixed gas of hydrogen and rare gas, in rare gas containing formic acid gas, etc.

[0099] Subsequently, as shown in FIG. 3(e), solder paste is applied onto a predetermined copper wiring 3 in a predetermined pattern (third step). The resin component 5 penetrates into the voids 3a of the copper wiring 3 and fills at least a part of the copper wiring 3. Following the third step, as shown in FIG. 3(f), an electronic element 8 having an electrode 9 is placed (mounted) at a predetermined position of the solder paste layer 6 (fourth step). Following the fourth step, as shown in FIG. 3(g), the solder particles 4 are melted to form a solder layer 11, thereby joining the copper wiring 3 and the electrode 9 of the electronic element 8 (fifth step). Also, the resin layer 14 hardens to become a resin layer 16. Thereby, an electronic component 18 is obtained.

[0100] The electronic component 18 obtained by the manufacturing method described above includes a polymer molded body 1, a copper wiring 3 provided on the polymer molded body 1, a solder layer 11 that joins the copper wiring 3 and the electrode 9 of the electronic element 8, a resin layer 12 that covers at least a part of the solder layer 11, and a resin layer 16 that covers a part of the copper wiring 3. At least a part of the voids 3a of the copper wiring 3 is filled with a cured product of the same resin component as the resin layer 12 or the resin layer 16.

[0101] In the manufacturing method of the electronic component according to the present embodiment, since the copper paste is applied in a predetermined pattern (a pattern corresponding to the copper wiring 3), a polymer containing a catalyst is unnecessary, and the steps of laser irradiation and electroless copper plating can be omitted. In addition, in these manufacturing methods, after forming the paste layer 6 on the copper wiring 3, the electronic element 8 is placed and heat-treated to join the copper wiring 3 and the electronic element 8 to each other with solder, and at least a part of the solder layer 11 is covered by the resin layer 12, and the resin component filled in at least a part of the voids of the copper wiring 3 hardens to form a resin filling portion 13 or a resin filling portion 17, whereby the adhesiveness between the polymer molded body and the copper wiring can be improved.

[0102] In the manufacturing method according to the present embodiment, by making the resin layer 14 containing a resin component that coats a part of the copper wiring 3 and the resin component 5 in the solder paste the same component, it is possible to perform the solder bonding between the electronic element 8 and the copper wiring 3 and the formation of the surface protective film of the copper wiring 3 in the same process. Compared with the conventional processes (solder resist formation process (coating of an organic film on the copper wiring and the front surface of the polymer molded body, exposure, development to form openings for solder bonding), application of solder paste to the wiring openings, solder bonding process by heat treatment (component mounting), etc.), the processes and the time required for manufacturing can be significantly shortened.

[0103] FIG. 4 is an SEM image showing an example of a cross-section of a copper wiring made of a sintered body of copper particles. The copper wiring 24 shown in FIG. 4 has a structure derived from flake-shaped copper particles oriented substantially parallel to the bonding interface (for example, the bonding surface between the polymer molded body and the wiring). When the wiring has the above copper wiring 24, by orienting the flake-shaped copper particles substantially parallel to the bonding interface direction, cracking of the wiring can be suppressed. Further, although the reason is not clear, the adhesiveness between the wiring and the polymer molded body can be improved.

[0104] The wiring having the copper wiring 24 shown in FIG. 4 may further include, in addition to the sintered copper 24a derived from the flake-shaped copper particles, voids 24b and sintered copper derived from copper particles (for example, spherical copper particles) that join the flake-shaped copper particles to each other. The wiring having the above copper wiring 24 can be formed, for example, by sintering a copper paste containing flake-shaped copper particles and, optionally, copper particles (for example, spherical copper particles) that join the flake-shaped copper particles to each other.

[0105] Here, the flake shape includes flat shapes such as plate shapes and scaly shapes. In the sintered copper 24a derived from the flaky copper particles included in the above structure, the ratio of the major axis (maximum diameter) to the thickness (major axis / thickness, aspect ratio) may be 5 or more. The number average diameter of the major axis may be 2.0 μm or more, may be 3.0 μm or more, or may be 4.0 μm or more. When the sintered copper 24a derived from the flaky copper particles has such a shape, the reinforcing effect by the copper wiring 24 included in the wiring is improved, and the adhesiveness (bonding strength) between the wiring and the polymer molded body and the conduction reliability of the wiring become even more excellent.

[0106] The major axis and thickness of the sintered copper 24a derived from the flaky copper particles can be obtained, for example, from the SEM image of the cross-section of the wiring. Hereinafter, a method for measuring the major axis and thickness of the sintered copper derived from the flaky copper particles from the SEM image will be exemplified. First, cut out the wiring in a rectangular parallelepiped shape to make a measurement sample. Place the sample in a casting cup, pour epoxy casting resin into the cup so that the entire sample is filled, and cure it. Cut near the cross-section to be observed of the cast sample, shave the cross-section by polishing, and perform CP (Cross Section Polisher) processing. Observe the cross-section of the sample with an SEM device at 5000 times magnification. When obtaining the cross-sectional image of the wiring (for example, 5000 times), in the dense continuous part, in the linear, rectangular parallelepiped-shaped, and ellipsoidal parts, the one with the maximum length among the straight lines included in this part is defined as the major axis, and the one with the maximum length among the straight lines included in this part and orthogonal to it is defined as the thickness. When the length of the major axis is 1.0 μm or more and the ratio of the major axis / thickness is 4 or more, it is regarded as the sintered copper derived from the flaky copper particles, and the major axis and thickness of the sintered copper derived from the flaky copper particles are measured with image processing software having a length measurement function. The average value thereof can be obtained by calculating the number average at 20 or more randomly selected points.

[0107] In the above embodiment, an aspect of using copper particles as the metal particles is described. However, the metal particles according to this embodiment are not limited to copper particles. Particles containing a sinterable metal can be used. Even when metal particles other than copper particles are used, the manufacturing process of the above-described electronic components can be applied.

Example

[0108] Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

[0109] [Preparation of Copper Paste] (Copper Paste a1) 5.2 g of α-terpineol (manufactured by Fujifilm Wako Pure Chemical Corporation) and 6.8 g of isobornyl cyclohexanol (manufactured by Nippon Terpene Chemical Co., Ltd.) as a dispersion medium, and 52.8 g of "CH-0200" (manufactured by Mitsui Mining & Smelting Co., Ltd., 50% volume average particle size: 0.36 μm, content of copper particles with a particle size of 0.01 to 0.8 μm: 95% by mass) as sub-micro copper particles were mixed in a poly bottle, and treated with an ultrasonic homogenizer (trade name "US-600" manufactured by Nippon Seiki Co., Ltd.) at 19.6 kHz, 600 W for 1 minute to obtain a dispersion liquid. To this dispersion liquid, 35.2 g of "MA-C025" (manufactured by Mitsui Mining & Smelting Co., Ltd., content of copper particles with a maximum diameter of 1 to 20 μm: 100% by mass) as flaky micro copper particles was added, and stirred with a spatula until the dry powder disappeared. The poly bottle was sealed, and stirred at 2000 rpm for 2 minutes using a planetary vacuum mixer (trade name "Planetry Vacuum Mixer ARV-310" manufactured by Shinki Co., Ltd.), and stirred at 2000 rpm for 2 minutes under reduced pressure to obtain copper paste a1.

[0110] (Copper Paste a2) Copper paste a2 was obtained in the same manner as the preparation of copper paste a1, except that "10% Ag-coated Cu-HWQ 5 μm" (manufactured by Fukuda Metal Foil Powder Industry Co., Ltd., 50% volume average particle size: 5.89 μm) of silver-coated copper particles was used instead of sub-micro copper particles, and "10% Ag-coated 2L3" (manufactured by Fukuda Metal Foil Powder Industry Co., Ltd., 50% volume average particle size: 10.86 μm) of silver-coated copper particles was used instead of flaky micro copper particles.

[0111] [Preparation of Solder Paste] 70 parts by mass of solder particles (“Sn42 - Bi58 particles”, average particle diameter: 20 μm), 25.2 parts by mass of bisphenol F type epoxy resin (trade name “YDF - 170” manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., epoxy equivalent: 170), 1.3 parts by mass of an imidazole compound (trade name “2PZ - CN” manufactured by Shikoku Kasei Kogyo Co., Ltd.), and 3.5 parts by mass of 2,2 - bis(hydroxymethyl)propionic acid were mixed to prepare a solder paste.

[0112] [Example 1] (Fabrication of Electronic Component 40) A polymer molded body (trade name “Sumika Super LCP E6000HF” manufactured by Sumitomo Chemical Co., Ltd.) made of liquid crystal polymer with a size of 40 mm × 40 mm and a thickness of 3 mm was prepared. Subsequently, as shown in Fig. 5(a), a stainless - steel metal mask (thickness: 50 μm) having two rectangular openings of 1.5 mm × 1 mm was placed on the polymer molded body 31, and a copper paste a1 was applied by stencil printing using a metal squeegee to obtain a member having a copper paste layer 32 formed.

[0113] The above - mentioned member was set in a tube furnace (manufactured by ABC Co., Ltd.), and argon gas was flowed at 1 L / min to replace the air with argon gas. Then, while flowing hydrogen gas at 300 mL / min, the temperature was raised for 10 minutes and sintering treatment was carried out under the conditions of 180 °C for 60 minutes to sinter the copper paste layer 32, and as shown in Fig. 5(b), a copper wiring 33 was formed.

[0114] Subsequently, as shown in Fig. 5(c), a solder paste was applied on the copper wiring 33 to form a solder paste layer 34, and then, as shown in Fig. 5(d), a ceramic capacitor 35 (2 mm × 1.2 mm × 0.6 mmt, trade name “GQM series” manufactured by Murata Manufacturing Co., Ltd.) having electrodes 36 formed thereon was placed (mounted) on the solder paste layer 34 to obtain a member. The electrodes 36 were formed of copper at both ends of the ceramic capacitor 35.

[0115] Subsequently, the member shown in Fig. 5(d) was placed on a hot plate heated to 170°C in the atmosphere for 15 minutes to obtain an electronic component 40. The cross-sectional shape of the electronic component 40 is shown in Fig. 5(e). Fig. 5(e) is a cross-sectional view taken along line IVc-IVc in Fig. 5(d). The electrode 36 of the ceramic capacitor 35 and the copper wiring 33 were joined by a solder layer 37, and the outer periphery of the solder joint was reinforced by a resin layer 38.

[0116] The electronic component 40 was embedded in a casting resin 42 to prepare a sample for cross-sectional observation. The observation result of the cross-section of the electronic component 40 by an optical microscope is shown in Fig. 6. The electrode 36 of the ceramic capacitor 35 and the copper wiring 33 are joined via a solder layer 37, and a resin layer 38 is formed on the outer periphery of the solder layer 37. The observation result of the cross-sections of the polymer molded body 31, the copper wiring 33, and the solder layer 37 by an optical microscope is shown in Fig. 7. The copper wiring 33 has voids, and the void portions are filled with a resin component to form a resin-filled portion 43.

[0117] (Evaluation of Adhesion) For the electronic component 40, the connection strength (shear strength) was measured using a bond tester (product name: Universal Bond Tester Series 4000 manufactured by Dage). Specifically, as shown in Figs. 10(a) and 10(b), for the electronic component 40, a shear tool 45 was arranged at a shear height of 50 μm, and shear was performed at a speed of 0.5 mm / min in the direction of the arrow to measure the shear strength. Note that Fig. 10(b) is a cross-sectional view taken along line IVc-IVc in Fig. 5(d). The adhesion between the polymer molded body 31 and the copper wiring 33 was evaluated from the average value of the shear strengths at 20 locations where the polymer molded body 31 and the copper wiring 33 are joined. The results are shown in Table 1.

[0118] (Fabrication of Electronic Component 44) The above polymer molded body was prepared. As shown in Fig. 8(a), a stainless-steel metal mask (thickness: 50 μm) having one square opening of 0.9 mm × 0.9 mm was placed on the polymer molded body 31, and a copper paste a1 was applied by screen printing using a metal squeegee to obtain a member having a copper paste layer 32 formed thereon. The obtained member was set in a tube furnace (manufactured by ABC Co., Ltd.), and argon gas was flowed at 1 L / min to replace the air with argon gas. Then, while flowing hydrogen gas at 300 mL / min, the temperature was raised for 10 minutes and sintering treatment was performed under the conditions of 180 °C for 60 minutes to sinter the copper paste layer, and as shown in Fig. 8(b), a copper wiring 33 was formed.

[0119] Subsequently, as shown in Fig. 8(c), a solder paste was applied on the copper wiring to form a solder paste layer 34. Subsequently, as shown in Fig. 8(d), a copper substrate 39 (1 mm × 1 mm × 0.3 mm t) was placed (mounted) on the upper part of the solder paste layer 34 to obtain a member. Subsequently, in the atmosphere, the member shown in Fig. 8(d) was placed on a hot plate heated to 170 °C and left for 15 minutes. The shape of the cross-section of the electronic component 44 obtained by leaving it is shown in Fig. 8(e). The copper substrate 39 and the copper wiring 33 were joined by a solder layer 37, and the outer peripheral portion of the solder layer 37 was reinforced by a resin layer 38.

[0120] The observation result of the cross-section of the electronic component 44 by an optical microscope is shown in Fig. 9. The copper substrate 39 and the copper wiring 33 are joined via a solder layer 37, and a resin layer 38 is formed on the outer periphery of the solder layer 37.

[0121] (Evaluation of Adhesion) Regarding the electronic component 44, the connection strength (shear strength) was measured using a bond tester. Specifically, as shown in Fig. 11, for the electronic component 44, a shear tool 45 was arranged at a shear height of 50 μm, and shear was performed at a speed of 0.5 mm / min in the direction of the arrow to measure the shear strength. The adhesion between the polymer molded body 31 and the copper wiring 33 was evaluated from the average value of the shear strengths at 20 locations where the polymer molded body 31 and the copper wiring 33 were joined. The results are shown in Table 1.

[0122] [Example 2] Electronic components 40 and 44 were fabricated in the same manner as in Example 1, except that the sintering temperature of the copper paste layer 32 was changed from 180°C to 225°C, and the adhesiveness was evaluated.

[0123] [Example 3] Electronic components 40 and 44 were fabricated in the same manner as in Example 1, except that the copper paste layer 32 was formed using copper paste a2 instead of copper paste a1, and the copper paste layer 32 was baked in the air at 180°C for 10 minutes, and the adhesiveness was evaluated.

[0124] [Comparative Example 1] Electronic components 48 shown in FIG. 12 and electronic components 49 shown in FIG. 13 were fabricated in the same manner as in Example 1, except that the solder layer 37 was formed using only solder particles "Sn42-Bi58 particles" instead of the solder paste, and the adhesiveness was evaluated.

[0125] [Comparative Example 2] Electronic components 48 and 49 were fabricated in the same manner as in Example 2, except that the solder layer 37 was formed using only solder particles "Sn42-Bi58 particles" instead of the solder paste, and the adhesiveness was evaluated.

[0126] [Comparative Example 3] Electronic components 48 and 49 were fabricated in the same manner as in Example 3, except that the solder layer 37 was formed using only solder particles "Sn42-Bi58 particles" instead of the solder paste, and the adhesiveness was evaluated.

[0127]

Table 1

Explanation of Reference Signs

[0128] 1,31… Polymer molded body, 2,32… Copper paste layer, 3,24,33… Copper wiring, 3a… Void, 4… Solder particles, 5… Resin component, 6,34… Solder paste layer, 7,13,15,17,43… Resin-filled part, 8… Electronic element, 35… Ceramic capacitor, 9,36… Electrode, 10,40,44,48,49… Electronic components, 11,37… Solder layer, 12,14,16,38… Resin layer, 39… Copper substrate, 42… Casting resin, 45… Share tool.

Claims

1. A first step of forming a metal paste layer by applying a metal paste containing metal particles containing copper particles and a volatile dispersion medium in a predetermined pattern on a polymer molded body; A second step of forming a metal wiring by sintering the metal particles; A third step of forming a solder paste layer by applying a solder paste containing solder particles and a resin component on the metal wiring; A fourth step of disposing an electronic element on the solder paste layer; A fifth step of heating the solder paste layer to form a solder layer joining the metal wiring and the electronic element and to form a resin layer covering at least a part of the solder layer, the method for manufacturing an electronic component comprising: In the second step, the metal wiring has voids, and in the third step, at least a part of the voids is filled with the resin component, a method for manufacturing an electronic component.

2. The method for manufacturing an electronic component according to claim 1, wherein the solder particles contain tin.

3. The method for manufacturing an electronic component according to claim 2, wherein the solder particles are composed of at least one tin alloy selected from the group consisting of In - Sn alloy, In - Sn - Ag alloy, Sn - Bi alloy, Sn - Bi - Ag alloy, Sn - Ag - Cu alloy, and Sn - Cu alloy.

4. The method for manufacturing an electronic component according to any one of claims 1 to 3, wherein the polymer molded body is made of a liquid crystal polymer or polyphenylene sulfide.

5. The electronic element has an electrode containing at least one selected from the group consisting of copper, nickel, palladium, gold, platinum, silver, and tin on the outermost surface, In the fourth step, the electronic element is disposed so that the electrode is in contact with the solder paste layer, the method for manufacturing an electronic component according to any one of claims 1 to 4.

6. The method for manufacturing an electronic component according to any one of claims 1 to 5, wherein the resin component contains at least one thermosetting compound selected from the group consisting of an oxetane compound, an epoxy compound, an episulfide compound, a (meth)acrylic compound, a phenol compound, an amino compound, a polyurethane compound, a silicone compound, and a polyimide compound.

7. The method for manufacturing an electronic component according to any one of claims 1 to 6, wherein the metal particles include first copper particles having a particle size of 2.0 μm or more and second copper particles having a particle size of 0.8 μm or less.

8. A polymer molded body, A metal wiring provided on the polymer molded body and composed of a sintered body of metal particles containing copper particles, An electronic element disposed on the metal wiring, A solder layer that joins the metal wiring and the electronic element, A resin layer composed of a cured product of a resin component that covers at least a part of the solder layer, Comprising, The metal wiring has voids, and at least a part of the voids is filled with a cured product of the resin component, The resin component contains at least one thermosetting compound selected from the group consisting of an oxetane compound, an epoxy compound, an episulfide compound, a (meth)acrylic compound, a phenol compound, an amino compound, a polyurethane compound, a silicone compound, and a polyimide compound. Electronic component.

9. The solder layer contains tin. The electronic component according to claim 8.

10. The solder layer is composed of at least one tin alloy selected from the group consisting of an In-Sn alloy, an In-Sn-Ag alloy, a Sn-Bi alloy, a Sn-Bi-Ag alloy, a Sn-Ag-Cu alloy, and a Sn-Cu alloy. The electronic component according to claim 9.

11. The polymer molded body is made of a liquid crystal polymer or polyphenylene sulfide. The electronic component according to any one of claims 8 to 10.

12. The electronic element has an electrode containing at least one selected from the group consisting of copper, nickel, palladium, gold, platinum, silver, and tin on the outermost surface, The electrode is joined to the solder layer. The electronic component according to any one of claims 8 to 11.

13. The metal particles include first copper particles having a particle size of 2.0 μm or more and second copper particles having a particle size of 0.8 μm or less. The electronic component according to any one of claims 8 to 12.

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