JP2020198394A - Method for manufacturing electronic component and electronic component - Google Patents

Abstract

To provide a method which can simply form a metal wire and mount an electric element on a polymer molding having low heat resistance, and manufactures an electronic component having sufficient conductive reliability even when receiving heat stress with good productivity.SOLUTION: A method for manufacturing an electronic component 100 includes: a step b of coating a metal paste 2 containing metal particles to a polymer molding 1 with a predetermined pattern, and forming a metal paste layer; a step c of sintering the metal particles and forming a metal wire 3; a step d of coating a solder paste containing solder particles and a resin component onto the metal wire and forming a solder paste layer 6; a step e of arranging an electric element 8 on the solder paste; and a step f of heating the solder paste layer, forming a solder layer 11 joining the electric element, and forming a resin layer 12 covering the solder layer. The polymer molding is a molding of crystalline plastic having a melting point of 280°C or lower or amorphous plastic having a glass transition temperature of 160°C or lower.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for manufacturing an electronic component and an electronic component.

Metal plating is used as a method of providing a metal layer on the surface of a polymer molded product for the purpose of functional and / or decorative surface processing. When the metal layer has a predetermined pattern such as metal wiring, metal plating is selectively performed. For example, a method using laser direct structuring (LDS) is known, and when copper wiring is formed by LDS, the portion of the polymer molded body containing the catalyst that forms the copper wiring is irradiated with a laser to provide the catalyst. By activating, the catalyst can be selectively subjected to electroless copper plating (only in the portion where the copper wiring is formed), and as a result, the copper wiring having a predetermined pattern can be formed (for example, Patent Document 1). .. However, such a method has a problem that the polymer containing the catalyst is expensive.

On the other hand, a method of metal plating a polymer molded body formed of a general-purpose plastic such as ABS resin and polypropylene is also being studied. For example, Patent Document 2 below discloses a method of forming a Ni-P metal film on a base material of an ABS resin that has been subjected to a surface treatment including ozone water treatment. Further, in Patent Document 3 below, a predetermined swelling treatment is performed for the purpose of selectively forming an electroless Ni plating film having excellent adhesion only at a desired location of polypropylene resin, which is a substitute material for ABS resin. A method of irradiating UV only to the area to be plated with the polypropylene resin molded product has been proposed.

Japanese Unexamined Patent Publication No. 2012-149347 Japanese Patent No. 5096273 Japanese Unexamined Patent Publication No. 2016-160506

However, the methods described in Patent Documents 2 and 3 also require an electroless plating step, which poses a problem in terms of productivity. Further, according to the study by the present inventors, an electronic component obtained when a metal wiring is formed on a polymer molded body containing a plastic having low heat resistance as a main component by the above plating method and an electronic element is mounted on the metal wiring. Was found to be prone to disconnection due to thermal stress (eg, temperature cycle test at -40 ° C to 80 ° C). Regarding the adhesion between the plating film and the polymer molded body, even if it is good immediately after plating, the polymer molded body easily expands and contracts when heat stress is applied, but the metal layer does not easily expand and contract. It is considered that the adhesion is lowered due to the stress between the layers. Then, the present inventors presume that when the polymer molded product contains a plastic having low heat resistance as a main component, a decrease in conduction reliability becomes apparent especially after the temperature cycle test.

Therefore, one aspect of the present invention is a case where metal wiring can be easily formed and electronic elements can be mounted on a polymer molded body containing a plastic as a main component having low heat resistance, and a thermal stress is applied. However, it is an object of the present invention to provide a method for manufacturing an electronic component capable of producing an electronic component having sufficient conduction reliability with high productivity, and an electronic component obtained by the method.

One aspect of the present invention is a first step of applying a metal paste containing metal particles to a polymer molded body in a predetermined pattern to form a metal paste layer, and metal wiring by sintering the metal particles. The second step of forming the solder paste layer by applying the solder paste containing the solder particles and the resin component on the metal wiring, and the third step of forming the solder paste layer, and arranging the electronic element on the solder paste layer. The fourth step and the fifth step of heating the solder paste layer to form a solder layer for joining the metal wiring and the electronic element and forming a resin layer covering at least a part of the solder layer. This is a method for producing an electronic component in which the polymer molded body is a molded body of a crystalline plastic having a melting point of 280 ° C. or lower or an amorphous plastic having a glass transition temperature of 160 ° C. or lower.

According to the above method for manufacturing electronic components, since the metal paste is applied in a predetermined pattern (pattern corresponding to metal wiring), a polymer containing a catalyst is unnecessary, and the electroless copper plating step can be omitted. .. In addition, in this manufacturing method, a solder paste containing solder particles and a resin component is applied onto the metal wiring formed by firing the metal paste, and the solder paste is heated after the electronic elements are arranged to cover the outer periphery of the solder layer. While forming the resin layer, the resin component can be filled in the voids of the metal wiring which is a sintered body of the metal particles. As a result, the adhesiveness between the polymer molded body and the metal wiring can be improved, the metal wiring can be made difficult to break, and sufficient conduction reliability can be obtained even when subjected to thermal stress. Electronic components can be manufactured with high productivity.

In the third step, a solder resist may be formed so that at least a part of the metal wiring is exposed, and a solder paste may be applied on the exposed portion of the metal wiring to form a solder paste layer.

One aspect of the present invention is also a first step of applying a metal paste containing metal particles to a polymer molded body in a predetermined pattern to form a metal paste layer, and a metal by sintering the metal particles. The second step of forming the wiring, the third step of applying the resin composition containing the resin component on the metal wiring to form the resin layer, and the resin layer so that at least a part of the metal wiring is exposed. The fourth step of removing the above, the fifth step of applying the solder paste containing the solder particles to the exposed portion of the metal wiring to form the solder paste layer, and the fifth step of arranging the electronic element on the solder paste layer. A step 6 and a seventh step of heating the solder paste layer to form a solder layer for joining the metal wiring and the electronic element are provided, and the polymer molded body is a crystalline plastic having a melting point of 280 ° C. or lower. This is a method for manufacturing an electronic part which is a molded body of an amorphous plastic having a glass transition temperature of 160 ° C. or less.

According to the above method for manufacturing electronic components, since the metal paste is applied in a predetermined pattern (pattern corresponding to metal wiring), a polymer containing a catalyst is unnecessary, and the electroless copper plating step can be omitted. .. In addition, in this production method, the resin component can be filled in the voids of the metal wiring, which is a sintered body of the metal particles, by applying the resin composition onto the metal wiring formed by firing the metal paste. it can. As a result, the adhesiveness between the polymer molded body and the metal wiring can be improved, the metal wiring can be made difficult to break, and sufficient conduction reliability can be obtained even when subjected to thermal stress. Electronic components can be manufactured with high productivity.

The solder paste may further contain a resin component to form a solder layer and a resin layer covering at least a part of the solder layer in the seventh step. In this case, by applying the solder paste, arranging the electronic elements, and then heat-treating the solder paste, the metal wiring and the electronic elements are joined via the solder layer, and a resin layer is formed on the outer periphery of the solder layer. This makes it possible to further improve the adhesiveness between the polymer molded body and the metal solder.

One aspect of the present invention is also a first step of applying a metal paste containing metal particles to a polymer molded body in a predetermined pattern to form a metal paste layer, and by sintering the metal particles. The second step of forming the wiring, the third step of applying the solder paste containing the solder particles on the metal wiring to form the solder paste layer, and the fourth step of arranging the electronic element on the solder paste layer. The process, the fifth step of heating the solder paste layer to form a solder layer that joins the metal wiring and the electronic element, and the polymer molded body are connected to the polymer molded body via the metal wiring and the solder layer. A sixth step of impregnating and curing a sealing material containing a curable resin component is provided between the polymer molded product and the polymer molded product having a melting point of 280 ° C. or lower and a crystalline plastic or glass transition temperature. This is a method for manufacturing an electronic component which is a polymer of an amorphous plastic having a temperature of 160 ° C. or lower.

According to the above method for manufacturing electronic components, since the metal paste is applied in a predetermined pattern (pattern corresponding to metal wiring), a polymer containing a catalyst is unnecessary, and the electroless copper plating step can be omitted. .. In addition, in this manufacturing method, a sealing material containing a curable resin component is impregnated between the metal wiring bonded by the solder layer and the electronic element and cured to cure the resin on the outer periphery of the solder layer. It is possible to fill the voids of the metal wiring, which is a sintered body of metal particles, with the cured resin while forming the object. As a result, the adhesiveness between the polymer molded body and the metal wiring can be improved, the metal wiring can be made difficult to break, and sufficient conduction reliability can be obtained even when subjected to thermal stress. Electronic components can be manufactured with high productivity.

In each of the above-described methods for manufacturing electronic components according to the present invention, the polymer molded product may contain polypropylene, ABS resin, or polycarbonate.

Further, metal particles can be sintered by laser irradiation or heating at 120 ° C. or lower in an atmosphere containing formic acid to form metal wiring. In this case, the effect of heat on the polymer molded product can be made smaller.

Further, the metal paste may contain a first copper particle having a particle size of 2.0 μm or more and a second copper particle having a particle size of 0.8 μm or less. In this case, copper wiring having excellent conductivity and thermal conductivity and appropriately containing voids can be easily formed.

Further, the thickness of the metal wiring may be 10 μm or more. In this case, it becomes easy to secure the continuity reliability of the electronic component.

Other aspects of the present invention include 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 arranged on the metal wiring, the metal wiring and electrons. The polymer molded body is a molded body of a crystalline plastic having a melting point of 280 ° C. or lower or an amorphous plastic having a glass transition temperature of 160 ° C. or lower, and the metal wiring has voids, comprising a solder layer for joining the elements. It is an electronic component in which the voids are filled with a resin component.

Such electronic components are sufficient even when they are subjected to thermal stress, even though metal wiring is formed and electronic elements are mounted on a polymer molded body containing a plastic as a main component having low heat resistance. It can be conductive and reliable. Further, since it can be manufactured by the method for manufacturing an electronic component according to the present invention described above, it is also excellent in productivity.

The electronic component may further include a resin layer that covers at least a part of the solder layer. Further, the thickness of the metal wiring may be 10 μm or more.

According to one aspect of the present invention, it is possible to easily form a metal wiring and mount an electronic element on a polymer molded product containing a plastic having low heat resistance as a main component, and it is a case where a thermal stress is applied. However, it is possible to provide a method for manufacturing an electronic component capable of manufacturing an electronic component having sufficient conduction reliability with high productivity. Further, according to one aspect of the present invention, there is a case where an electronic element is mounted on a polymer molded body containing a plastic having low heat resistance as a main component, but the productivity is excellent and heat stress is applied. Even so, it is possible to provide an electronic component having sufficient conduction reliability.

It is a schematic cross-sectional view which shows the manufacturing method of the electronic component of one Embodiment. It is a schematic cross-sectional view for demonstrating the joint part of a metal wiring and a polymer molded body in an electronic component. It is a schematic cross-sectional view which shows the manufacturing method of the electronic component of one Embodiment. It is a schematic cross-sectional view which shows the manufacturing method of the electronic component of one Embodiment. It is a schematic cross-sectional view which shows the manufacturing method of the electronic component of one Embodiment. 6 is an SEM image showing an example of a cross section of a metal wiring composed of a sintered body of metal particles. It is a schematic diagram which shows the manufacturing method of the electronic component in an Example.

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 designated by the same reference numerals, and duplicate description will be omitted.

The method for manufacturing an electronic component of the present embodiment includes a first step of applying a metal paste containing metal particles in a predetermined pattern on a polymer molded body to form a metal paste layer, and soldering the metal particles. As a result, the second step of forming the metal wiring, the third step of applying the solder paste containing the solder particles and the resin component on the metal wiring to form the solder paste layer, and the solder paste layer. The fourth step of arranging the electronic element and the first step of heating the solder paste layer to form a solder layer for joining the metal wiring and the electronic element and forming a resin layer covering at least a part of the solder layer. It includes 5 steps.

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 is likely to occur at a low temperature, the metal particles preferably contain copper or silver, and more preferably contain copper from the viewpoint of suppressing migration when finely wired. Considering firing at a low temperature and the cost of the material, it is more preferable to use silver-coated copper particles as the metal particles. One type of metal particles may be used alone, or two or more types may be used in combination. Further, the metal particles may include two or more kinds of metal particles having different particle sizes, for example, a first metal particle having a particle size of 1.0 μm or more and a second metal particle having a particle size of 0.8 μm or less. Metal particles and may be included.

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

The polymer molded product 1 may be a molded product of a crystalline plastic having a melting point of 280 ° C. or lower or an amorphous plastic having a glass transition temperature of 160 ° C. or lower.

In the present specification, the melting point of a crystalline plastic means the external melting start temperature (Tim) at the crystal melting peak when measured according to JIS K-7121 by differential scanning calorimetry (DSC). The glass transition temperature of an amorphous plastic means the intermediate point glass transition temperature calculated by a method according to JIS K 7121 from the calorific value change measured by the differential scanning calorimetry (DSC).

The polymer molded body 1 is, for example, amorphous such as polyvinyl chloride (PVC), polystyrene (PS), AS resin (SAN), ABS resin, methacrylic resin (PMMA), polycarbonate (PC), and modified polyphenylene ether (mPPE). Molded plastics and crystalline properties such as polyethylene (PE), polypropylene (PP), polyamide 6 (PA6), polyamide 66 (PA66), polyacetal (POM), polybutylene terephthalate (PBT), polyethylene terephthalate (PET) A plastic molded body can be used. The shape and size of the polymer molded product are arbitrary. The polymer molded product 1 preferably contains polypropylene, ABS resin, or polycarbonate as a main component. The content ratio of the main component may be 50% by mass or more, 70% by mass or more, 90% by mass or more, or 100% by mass.

(First step)
In the first step, following the preparatory step, as shown in FIG. 1 (b), a copper paste is applied onto the polymer molded body 1 in a predetermined pattern (to the portion where the copper wiring is formed) to form a copper paste layer. 2 is formed (forming step). Copper paste is used, for example, 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, concave printing, gravure printing, stencil. It is applied by printing, soft lithograph, bar coat, applicator, particle deposition method, spray coater, spin coater, dip coater, electrodeposition coating, etc.

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. , 150 μm or less, or 100 μm or less.

In the forming step, the copper paste layer 2 provided on the polymer molded product 1 may be appropriately dried from the viewpoint of suppressing the flow and generation of voids during sintering of the copper particles. The gas atmosphere at the time of drying may be in the atmosphere, in an oxygen-free atmosphere such as nitrogen or rare gas, or in a reducing atmosphere such as hydrogen or formic acid. The drying method may be drying by leaving at room temperature, heat drying, or vacuum drying. For heat 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 wave. A heating device, a heater heating device, a steam heating furnace, a hot plate pressing device, or the like 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 140 ° C. or lower. The drying time may be, for example, 1 minute or more and 120 minutes or less.

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

The particle size and the average particle size of the first copper particles can be obtained from, for example, an SEM image of the particles. A method of calculating the particle size (maximum diameter) of the first copper particles from the SEM image will be illustrated. The powder of the first copper particles is placed on a carbon tape for SEM with a spatula to prepare a sample for SEM. This SEM sample is observed with an SEM device at a magnification of 5000. A rectangle circumscribing the first copper particles of the SEM image is drawn by image processing software, and the long side of the rectangle is the particle size (maximum diameter) of the particles. 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 size is calculated.

The volume average particle diameter of the first copper particles may be 1.0 μm or more, 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 a 50% volume average particle diameter. When determining the volume average particle size of copper particles, the particle size distribution measurement by the light scattering method is obtained by dispersing the copper particles as a raw material or dried copper particles obtained by removing volatile components from a copper paste in a dispersion medium using a dispersant. It can be obtained by a method of measuring with an apparatus (for example, Shimadzu nanoparticle size distribution measuring apparatus (trade name: SALD-7500 nano of Shimadzu Manufacturing Co., Ltd.). When a light scattering method particle size distribution measuring apparatus is used, the dispersion medium is , Hexene, toluene, α-terpineol and the like can be used.

The first copper particles are preferably flaky. In this case, since the first copper particles are oriented substantially parallel to the coated surface of the copper paste, the volume shrinkage when the copper particles in the copper paste are sintered is suppressed, and the resulting thermal stress of the wiring is suppressed. The disconnection due to is further suppressed. Moreover, although the reason is not clear, the adhesiveness between the copper wiring and the polymer molded product is further improved.

The aspect ratio of the first copper particles may be 4 or more, and may be 6 or more. When the aspect ratio is within the above range, the first copper particles in the copper paste are likely to be oriented parallel to the coated surface of the copper paste, and the volume when the copper particles in the copper paste are sintered. Shrinkage can be suppressed. Therefore, it is possible to further suppress disconnection due to thermal stress of the obtained wiring. The aspect ratio (major axis / thickness) 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 thickness.

The copper paste preferably contains first copper particles having a particle size of 1.0 μm or more and 50 μm or less and an aspect ratio of 4 or more. When the average particle size and aspect ratio of the first copper particles are within the above ranges, the volume shrinkage when the copper particles in the copper paste are sintered can be sufficiently reduced, and the resulting wiring can be disconnected due to thermal stress. It can be more suppressed.

The copper paste may contain copper particles having a particle size of 1.0 μm or more and 50 μm or less and an aspect ratio of less than 2, but the particle size is 1.0 μm or more and 50 μm or less and the aspect ratio is less than 2. The content of the copper particles is preferably 50 parts by mass or less with respect to 100 parts by mass of the first copper particles having a particle size of 1.0 μm or more and 50 μm or less and an aspect ratio of 4 or more. It is more preferably 30 parts by mass or less. By limiting the content of copper particles having an average particle size of 1.0 μm or more and 50 μm or less and an aspect ratio of less than 2, the first copper particles in the copper paste can be attached to the coated surface of the copper paste. It becomes easy to align substantially in parallel, and the volume shrinkage when the copper particles in the copper paste are sintered can be more effectively suppressed. This makes it easier to suppress disconnection due to thermal stress of the obtained wiring. In terms of making it easier to obtain such an effect, the content of copper particles having an average particle size of 1.0 μm or more and 50 μm or less and an aspect ratio of less than 2 is such that the particle size is 1.0 μm or more and 50 μm or less. Yes, it may be 20 parts by mass or less, 10 parts by mass or less, or 0 parts by mass with respect to 100 parts by mass of the first copper particles having an aspect ratio of 4 or more.

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 90% by mass, based on the total mass of the metal particles contained in the copper paste. % Or less, 70% by mass or less, or 50% by mass or less. When the content of the first copper particles is within the above range, it becomes easy to form a wiring having excellent conduction reliability.

The first copper particles may be treated with a surface treatment agent from the viewpoint of dispersion stability and oxidation resistance. The surface treatment agent may be one that is removed at the time of wiring formation (sintering of copper particles). Examples of the surface treatment agent include fatty 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; cetyl alcohol and stearyl alcohol. , Isobornylcyclohexanol, aliphatic alcohols such as tetraethyleneglycol; aromatic alcohols such as p-phenylphenol; alkylamines such as octylamine, dodecylamine, stearylamine; aliphatic nitriles such as stearonitrile and decanenitrile. Silane coupling agents such as alkylalkoxysilanes; polymer treatment agents such as polyethylene glycols, polyvinyl alcohols, polyvinylpyrrolidones and silicone oligomers. As the surface treatment agent, one type may be used alone, or two or more types may be used in combination.

The treatment amount of the surface treatment agent may be an amount of one molecular layer or more on the particle surface. The treatment amount of such a 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% by mass or more.

The treatment amount of the surface treatment agent is the number of molecular layers (n) adhering to the surface of the first copper particles, the specific surface area ( _Ap ) of the first copper particles (unit: m ² / g), and the surface treatment agent. of molecules _(M s) (unit g / mol), the minimum coverage area of the surface treatment agent _(S S) (unit ^{m 2} / piece), from Avogadro's number ^{_{(N a) (6.02 × 10}} 23 pieces) Can be calculated. Specifically, the processing amount of the surface treatment agent, the process amount of the surface treatment agent _{(wt%) = {(n · A} p · M s) / (S S · N A + n · A p · M s)} It is calculated according to the formula of × 100%.

The specific surface area of the first copper particles can be calculated by measuring the dried copper particles by the BET specific surface area measuring method. Minimum coverage of the surface treatment agent, if the surface treatment agent is a straight-chain saturated fatty acids, is 2.05 × ¹⁰ -19 ^m 2/1 molecule. In the case of other surface treatment agents, for example, calculation from a molecular model, or "Chemistry and Education" (Akihiro Ueda, Sumio Inafuku, Iwao Mori, 40 (2), 1992, p114-117). It can be measured by the method described. An example of a method for quantifying a surface treatment agent is shown. The surface treatment agent can be identified by a thermal desorption gas / gas chromatograph mass spectrometer of the dry powder obtained by removing the dispersion medium from the copper paste, whereby 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 content analysis. Examples of the carbon content analysis method include a high-frequency induction heating 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 by the above formula.

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

At the time of producing the copper paste, the particle size is 1.0 μm or more and 50 μm or less, the first copper particles having an aspect ratio of 4 or more are contained, and the particle size is 1.0 μm or more and 50 μm or less, and the aspect ratio is The content of copper particles less than 2 is 50 parts by mass or less, preferably 30 parts by mass with respect to 100 parts by mass of the first copper particles having a particle size of 1.0 μm or more and 50 μm or less and an aspect ratio of 4 or more. Copper particles having a mass or less of parts can be used. A commercially available product containing such copper particles may be selected and used.

In one embodiment, the copper paste may include a first copper particle and a second copper particle 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, so that the conductivity of the obtained 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 the copper paste is prepared only from the second copper particles, the volume shrinkage and the sintering shrinkage due to the drying of the dispersion medium are large. Therefore, when the copper particles are sintered, the sintered body (wiring) is formed from the adherend surface. Is easy to peel off and it is difficult to obtain sufficient conduction reliability, but by using the first copper particles and the second copper particles in combination, the volume shrinkage when the copper paste is sintered can be reduced. It is suppressed and the adhesiveness between the obtained wiring and the polymer molded body as an adherend is improved. Therefore, disconnection due to thermal stress of the wiring is less likely to occur.

The second copper particles act as copper particles that suitably bond the first copper particles to each other. Further, the second copper particles have a higher sinterability than the first copper particles and have a function of promoting the sintering of the copper particles. For example, it is possible to sinter the copper particles at a lower temperature as compared with the case where the first copper particles are used alone.

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 0.005 μm or more, 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 0.005 μm or more, 0.01 μm or more, 0.05 μm or more, 0.1 μm or more or 0.2 μm or more, 0.8 μm or less, 0.5 μm or less, It may be 0.4 μm or less or 0.3 μm or less.

The volume average particle diameter of the second copper particles may be 0.005 μm or more, 0.01 μm or more, and 0.8 μm or less. When the volume average particle diameter of the second copper particles is 0.01 μm or more, the effects of suppressing the synthesis cost of the second copper particles, good dispersibility, and suppressing the amount of the surface treatment agent used can be easily obtained. .. When the volume average particle diameter of the second copper particles is 0.8 μm or less, the effect of excellent sinterability of the second copper particles can be easily obtained. From the viewpoint of further exerting the above effect, the volume average particle size of the second copper particles may be 0.05 μm or more, 0.1 μm or more or 0.2 μm or more, and 0.5 μm or less, 0.4 μm or less or It may be 0.3 μm or less.

The second copper particles may contain 10% by mass or more of copper particles having a particle size of 0.005 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 of copper particles having a particle size of 0.005 μm or more and 0.8 μm or less, and may contain 30% by mass or more. It may contain 100% by mass. When the content ratio of the copper particles having a particle size of 0.005 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, the viscosity is increased, and the paste concentration is decreased. Can be further suppressed.

The content of the second copper particles in the copper paste is 20% by mass or more, 30% by mass or more, 35% by mass or more, or 40% by mass or more, based on the total mass of the metal particles contained in the copper paste. It may be 90% by mass or less, 85% by mass or less, or 80% by mass or less. When 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.

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 of the mass of the first copper particles and the mass of the second copper particles. Good. When 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 obtained wiring is less likely to occur. When the content of the second copper particles is 90% by mass or less, the volume shrinkage when the copper particles are sintered can be sufficiently suppressed, so that disconnection due to thermal stress of the obtained wiring is less likely to occur. From the viewpoint of further exerting the above effect, the content of the second copper particles is 30% by mass or more and 35% by mass or more based on the total of the mass of the first copper particles and the mass of the second copper particles. , 40% by mass or more, 85% by mass or less, or 80% by mass or less.

The shape of the second copper particle may be, for example, spherical, lumpy, needle-like, flake-like, substantially spherical, or the like. The second copper particle may be an agglomerate of copper particles having these shapes. From the viewpoint of dispersibility and filling property, the shape of the second copper particles may be spherical, substantially spherical, or flake-like, and from the viewpoint of flammability, mixing with the first copper particles, etc., the shape of the second copper particles may be spherical or substantially spherical. It may be substantially spherical.

The aspect ratio of the second copper particles may be 5 or less, and may be 3 or less, from the viewpoint of dispersibility, filling property, and mixing property with the first copper particles.

The second copper particles may be treated with a specific surface treatment agent. Specific surface treatment agents include, for example, organic acids having 8 to 16 carbon atoms. Examples of organic acids having 8 to 16 carbon atoms include caprylic acid, methylheptanic acid, ethylhexanoic acid, propylpentanoic acid, pelargonic acid, methyloctanoic acid, ethylheptanic acid, propylhexanoic acid, capric acid, methylnonanoic acid, and ethyl. Octanoic acid, propylheptanic acid, butylhexanoic acid, undecanoic acid, methyldecanoic acid, ethylnonanoic acid, propyloctanoic acid, butylheptanic acid, lauric acid, methylundecanoic acid, ethyldecanoic acid, propylnonanoic acid, butyloctanoic acid, pentalargonic 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, hexyloctanoic acid, pentadeconic acid , Methyltetradecanoic acid, ethyltridecanoic acid, propyldodecanoic acid, butylundecanoic acid, pelargonic acid, hexylnonanoic acid, palmitic acid, methylpentadecylic acid, ethyltetradecanoic acid, propyltridecanoic acid, butyldodecanoic acid, pentylundecanoic acid, hexyldecane Acids, heptylnonanoic acid, methylcyclohexanecarboxylic acid, ethylcyclohexanecarboxylic acid, propylcyclohexanecarboxylic acid, butylcyclohexanecarboxylic acid, pentalcyclohexanecarboxylic acid, hexylcyclohexanecarboxylic acid, heptylcyclohexanecarboxylic acid, octylcyclohexanecarboxylic acid, nonylcyclohexanecarboxylic acid, etc. Saturated fatty acids in Aromas such as acid, pyromellitic acid, o-phenoxy benzoic acid, methyl benzoic acid, ethyl benzoic acid, propyl benzoic acid, butyl benzoic acid, pentyl benzoic acid, hexyl benzoic acid, heptyl benzoic acid, octyl benzoic acid, nonyl benzoic acid, etc. Group carboxylic acids can be mentioned. One type of organic acid may be used alone, or two or more types may be used in combination. By combining such an organic acid with the second copper particles, the dispersibility of the second copper particles and the desorption of the organic acid at the time of sintering tend to be compatible with each other.

The treatment amount of the surface treatment agent may be an amount that adheres to the surface of the second copper particles in a single-layer to a triple-layer. 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 is 2.1% by mass or less, 1.6% by mass or less, or 1 It may be 1% by mass or less. The surface treatment amount of the second copper particles can be calculated for the first copper particles by the method described above. 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.

As the second copper particles, commercially available ones can be used. Examples of the second copper particles on the market include CH-0200 (manufactured by Mitsui Metal Mining Co., Ltd., volume average particle size 0.36 μm) and HT-14 (manufactured by Mitsui Metal Mining Co., Ltd., volume average particle size 0). .41 μm), CT-500 (manufactured by Mitsui Metal Mining Co., Ltd., volume average particle size 0.72 μm), Tn-Cu100 (manufactured by Taiyo Nisshi Co., Ltd., volume average particle size 0.12 μm).

The total content of the first copper particles and the content of 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. When the total content of the first copper particles and 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. From the viewpoint of further exerting the above effect, the total content of the first copper particles and the content of the second copper particles may be 90% by mass or more based on the total mass of the metal particles. It may be 95% by mass or more, or 100% by mass.

The copper paste may further contain other metal particles other than the copper particles. Examples of 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 other metal particles are contained, the content thereof may be less than 20% by mass and 10% by mass based on the total mass of the metal particles contained in the copper paste from the viewpoint of obtaining sufficient bondability. It may be as follows. Other metal particles may not be included. The shapes of the other metal particles are not particularly limited.

By including metal particles other than copper particles, it is possible to obtain wiring in which a plurality of types of metals are solid-dissolved or dispersed, so that mechanical properties such as yield stress and fatigue strength of the wiring are improved, and conduction reliability is improved. Easy to improve. Further, 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.

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 monovalent and polyvalent alcohols such as pentanol, hexanol, heptanol, octanol, decanol, ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, α-terpineol and isobornylcyclohexanol. 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, tripropylene glycol dimethyl ether and other ethers; 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, lactic acid. Ethers such as butyl, γ-butyrolactone, propylene carbonate; acid amides such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide; cyclohexane, octane, nonane, decane, undecane and the like. Examples thereof include aliphatic hydrocarbons; aromatic hydrocarbons such as benzene, toluene and xylene; mercaptans having an alkyl group having 1 to 18 carbon atoms; and mercaptans having a cycloalkyl group having 5 to 7 carbon atoms. Examples of mercaptans having an alkyl group having 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, and hexyl mercaptan. And dodecyl mercaptan. Examples of mercaptans having a cycloalkyl group having 5 to 7 carbon atoms include cyclopentyl mercaptan, cyclohexyl mercaptan and cycloheptyl mercaptan.

The content of the dispersion medium may be 5 parts by mass or more and 50 parts by mass or less, assuming that the total mass of the metal particles contained in the copper paste is 100 parts by mass. When 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 copper particles.

If necessary, a wetting improver such as a nonionic surfactant or a fluorine-based surfactant; a defoaming agent such as silicone oil; an ion trap agent such as an inorganic ion exchanger is appropriately added to the copper paste. May be good.

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

In the copper paste, the second copper particles, the surface treatment agent, and the dispersion medium are mixed in advance, and the dispersion treatment is performed to prepare a dispersion liquid of the second copper particles, and further, the first copper particles and other metal particles. And any additive may be mixed and prepared. By performing 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.

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

Sintering can be performed by heat treatment. For heat treatment, 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, etc. Heating means such as a heater heating device and a steam heating furnace can be used.

The atmosphere at the time of sintering may be an oxygen-free atmosphere from the viewpoint of suppressing oxidation of the sintered body, and may be a reducing atmosphere from the viewpoint of removing surface oxides of copper particles in the copper paste layer 2. Good. Examples of the anoxic atmosphere include the introduction of an oxygen-free gas such as nitrogen and a rare gas, or under vacuum. Examples of the reducing atmosphere include pure hydrogen gas, a mixed gas of hydrogen and nitrogen typified by a forming gas, nitrogen containing formic acid gas, a mixed gas of hydrogen and rare gas, and a rare gas containing formic acid gas. Can be mentioned.

The maximum temperature reached during the heat treatment may be 80 ° C. or higher, 180 ° C. or lower, 150 ° C. or lower, or from the viewpoint of reducing heat damage to each member (particularly the polymer molded product) and improving the yield. It may be 120 ° C. or lower. When the maximum temperature reached is 80 ° C. or higher, sintering tends to proceed sufficiently when the maximum temperature reached is held for 60 minutes or less. The maximum temperature retention time may be 1 minute or more, 60 minutes or less, 40 minutes or less, or 30 minutes or less from the viewpoint of volatilizing all the dispersion medium and improving the yield.

From the viewpoint of reducing heat damage to the polymer molded product, the temperature during the heat treatment is preferably lower than the melting point of the crystalline plastic, and is preferably (melting point -20) ° C. or lower. When the polymer molded product is an amorphous plastic, it is preferably (the glass transition temperature +20) ° C. or lower, and more preferably the glass transition temperature or lower.

From the viewpoint of reducing heat damage to the polymer molded product, the metal particles are preferably sintered by laser irradiation or heating at 120 ° C. or lower in an atmosphere containing formic acid, and more preferably by heating at 100 ° C. or lower in a formic acid atmosphere. It is preferable to let it.

The copper content (volume ratio) in the copper wiring 3 is preferably 65% by volume or more, more preferably 70% by volume or more, still more preferably 80% by volume or more, based on the total volume of the copper wiring. Good conduction reliability can be obtained by setting the copper content in the copper wiring 3 to 65% by volume or more. 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 a gap. Since the copper wiring 3 has an appropriate gap, 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 filled in the gap inside the copper wiring 3. Is easy to fill, and the resin reaches the gap 3a between the copper wiring 3 in contact with the polymer molded body and hardens, so that the adhesive strength between the polymer molded body 1 and the copper wiring 3 is further improved. Can be done.

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 into a rectangular body, the vertical and horizontal lengths of the copper wiring 3 are measured with a caliper or an external shape measuring device, and the thickness is measured with a film thickness meter to calculate the volume of the copper wiring 3. The apparent density M ₁ (g / cm ³ ) is obtained from the volume of the cut copper wiring 3 and the weight of the copper wiring 3 measured with a precision balance. Using the obtained M ₁ and the copper density of 8.96 g / cm ³ , the copper content (volume%) in the copper wiring 3 can be obtained from the following formula (A).
Copper content (volume%) in copper wiring 3 = [(M ₁ ) /8.96] × 100 (A)

In the copper wiring 3, the ratio of the copper element in the elements excluding the light element among the constituent elements may be 95% by mass or more, 97% by mass or more, or 98% by mass or more. It may be 100% by mass. When the above ratio of the copper element in the copper wiring 3 is within the above range, the formation of an intermetallic compound or the precipitation of dissimilar elements at the metal copper crystal grain boundary can be suppressed, and the properties of the metallic copper constituting the copper wiring 3 are It tends to be strong, and even better connection reliability can be easily obtained. Further, when the ratio of the copper element in the element excluding the light element in the copper wiring 3 is 100% by mass, the volume ratio of the copper can be regarded as the density (%).

The copper wiring 3 may include a structure derived from the 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). preferable. 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, it is possible to improve the adhesiveness between the copper wiring 3 formed by sintering and the polymer molded product 1.

(Third step)
Following the second step, as shown in FIG. 1D, a solder paste containing the solder particles 4 and the resin component 5 is applied onto the copper wiring 3 in a predetermined pattern to form the solder paste layer 6. To do. A part of the resin component 5 penetrates into the gap portion 3a of the copper wiring 3 and forms a resin filling portion 7 filled in at least a part of the copper wiring 3.

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 not easily affected by the oxidation of the solder surface, and the conduction reliability is easily improved. On the other hand, when the particle size of the solder particles 4 is 30 μm or less, the insulation reliability can be easily improved.

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 can be obtained by measuring the particle size of 300 arbitrary solder particles by observation using SEM and taking the average value thereof.

The solder particles 4 can contain tin. As such a solder particle 4, at least one tin alloy selected from the group consisting of an In-Sn alloy, an In-Sn-Ag alloy, a Sn-Bi alloy, and a Sn-Bi-Ag alloy may be used. Examples of the tin alloy include In-Sn (In 52% by mass, Bi48% by mass, melting point 118 ° C.), Sn-Bi (Sn43% by mass, Bi57% by mass, melting point 138 ° C.), Sn-Bi-Ag (Sn42% by mass). , Bi57% by mass, Ag1% by mass, melting point 139 ° C.).

The tin alloy can be selected according to the joining temperature. For example, when a tin alloy having a low melting point such as an In—Sn alloy or a Sn—Bi alloy is used, it can be bonded at 150 ° C. or lower.

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.

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. When the Ag content is 0.05% by mass or more, good solder connection reliability can be easily obtained, while when it is 10% by mass or less, the melting point is lowered and the solder wettability is improved, and as a result, the joint portion Connection reliability tends to be good.

The resin component 5 may contain a thermosetting compound. Examples of the thermosetting compound include oxetane compounds, epoxy compounds, episulfide compounds, (meth) acrylic compounds, phenol compounds, amino compounds, unsaturated polyester compounds, polyurethane compounds, silicone compounds and polyimide compounds. One type of thermosetting compound may be used alone, or two or more types may be used in combination. 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 product 1 and the copper wiring 3.

The resin component 5 may further contain a thermosetting agent. Examples of the heat 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. One type of thermosetting agent may be used alone, or two or more types may be used in combination. An imidazole curing agent, a polythiol curing agent, or an amine curing agent is preferable because it can be cured quickly at a low temperature. Further, a latent thermosetting agent may be used as the thermosetting agent in terms of enhancing the storage stability when the thermosetting compound and the thermosetting agent are mixed. The latent thermosetting agent is preferably a latent imidazole curing agent, a latent polythiol curing agent, or a latent amine curing agent. The thermosetting agent may be coated with a polymer substance such as a polyurethane resin or a polyester resin.

Examples of the imidazole curing agent include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimerite, and 2,4-diamino-. Addition of 6- [2'-methylimidazolyl- (1')] -ethyl-s-triazine and 2,4-diamino-6- [2'-methylimidazolyl- (1')] -ethyl-s-triazine isocyanuric acid Things can be mentioned.

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, 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.

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

Examples of the thermal cation curing agent include an iodonium-based cation curing agent, an oxonium-based cation curing agent, and a sulfonium-based cation curing agent. 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.

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

The resin component 5 may further contain a flux. The flux melts the oxide on the surface of the solder, the particles are fused to each other, and the solder wettability to the copper wiring 3 is improved.

As the flux, a flux 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 pine fat. Can be mentioned. One type of flux may be used alone, or two or more types may be used in combination.

Examples of the molten salt include ammonium chloride. Examples of organic acids 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 a rosin containing abietic acid as the main component. By using an organic acid or pine resin having two or more carboxyl groups as the flux, the effect of further increasing the conduction reliability between the electrodes is achieved.

The melting point of the flux is preferably 50 ° C. or higher, more preferably 70 ° C. or higher, and even 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 in the above range, the flux effect is exhibited more effectively, and the solder particles are arranged more efficiently on the electrode. The melting point range of the flux is preferably 80 to 190 ° C, more preferably 80 to 140 ° C or less.

Examples of fluxes having a melting point in the range of 80 to 190 ° C. include 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. Examples thereof include dicarboxylic acids (melting point 142 ° C.), succinic acid (melting point 122 ° C.) and pimelic acid (melting point 130 ° C.).

(4th step)
Following the third step, as shown in FIG. 1 (e), the electronic element 8 having the electrode 9 is arranged (mounted) at a predetermined position of the solder paste layer 6. Examples of the electronic element 8 include a power module including a diode, a rectifier, a thyristor, a MOS gate driver, a power switch, a power MOSFET, an IGBT, a Schottky diode, a fast recovery diode, a transmitter, an amplifier, an LED module, a capacitor, a gyro sensor, and the like. Can be mentioned.

Examples of the method of arranging the electronic element 8 on the solder paste layer 6 include a method using a chip mounter, a flip chip bonder, a positioning jig made of carbon or ceramics, and the like.

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 the outermost surface, and may be left at a high temperature after being bonded to the solder layer. At least one selected from the group consisting of copper, nickel and palladium is preferable from the viewpoint that mounting with high bonding reliability can be performed without forming impurities (intermetal compounds) between the solder layer and the electrode. It is an electrode containing the metal of the above on the outermost surface. The electrode 9 may consist of a single layer or a multi-layer metal-containing layer containing these metals.

(Fifth step)
Following 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. As a result, the electronic component 100 is obtained.

As a method of melting the solder particles 4, it can be carried out by heat treatment. For heat treatment, 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, etc. Heating means such as a heater heating device and a steam heating furnace can be used.

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 cover at least a part of the solder layer 11. 12 is formed. Specifically, for example, Sn-Bi (Sn43% by mass, Bi57% by mass) having a melting point of 138 ° C. is held at 150 ° C. to form a solder layer 11, and the resin component 5 is a solder layer 11. It is preferable that the outer peripheral portion of the solder is covered and cured to form the resin layer 12. Further, at this time, the resin component filled in at least a part of the gap portion 3a of the copper wiring 3 is cured to form the resin filling portion 13.

The atmosphere at the time of solder bonding may be an oxygen-free atmosphere from the viewpoint of suppressing oxidation of the sintered body, and may be a reducing atmosphere from the viewpoint of removing the surface oxide of the copper wiring 3. Examples of the anoxic atmosphere include the introduction of an oxygen-free gas such as nitrogen and a rare gas, or under vacuum. Examples of the reducing atmosphere include pure hydrogen gas, a mixed gas of hydrogen and nitrogen typified by a forming gas, nitrogen containing formic acid gas, a mixed gas of hydrogen and rare gas, and a rare gas containing formic acid gas. Can be mentioned.

The maximum temperature reached during the heat treatment may be 150 ° C. or higher, 350 ° C. or lower, 300 ° C. or lower, or from the viewpoint of reducing heat damage to each member (particularly the polymer molded product) and improving the yield. It may be 260 ° C. or lower. When the maximum ultimate temperature is 150 ° C. or higher, the melting of the solder particles 4 tends to proceed sufficiently when the maximum ultimate temperature holding time is 60 minutes or less.

From the viewpoint of reducing thermal damage to the polymer molded product, when the polymer molded product is a crystalline plastic, the bonding temperature is preferably equal to or lower than the melting point, and more preferably (melting point -20) ° C. or lower. Preferably, when the polymer molded product is an amorphous plastic, it is preferably (the glass transition temperature +20) ° C. or lower, and more preferably the glass transition temperature or lower. In this case, solder particles such as In—Sn alloy, In—Sn—Ag alloy, Sn—Bi alloy, and Sn—Bi-Ag alloy can be used.

The solder bonding may be performed with pressure applied to the electronic element 8, or may be performed only by the 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. When the pressure received during sintering is within the above range, voids can be reduced, joint strength and connection reliability can be further improved without impairing the yield because a special pressurizing device is not required. Examples of the method of applying pressure to the electronic element 8 include a method of placing a weight on the electronic element 8 located at the top.

The electronic component 100 obtained by the manufacturing method described above includes the polymer molded body 1, the copper wiring 3 provided on the polymer molded body 1, the solder layer 11 for joining the copper wiring 3 and the electronic element 8, and the solder. It includes a resin layer 12 that covers at least a part of the layer 11. At least a part of the gap 3a of the copper wiring 3 is filled with a cured product having the same resin component as the resin layer 12.

FIG. 2 is a diagram showing details of a joint portion between the copper wiring 3 and the polymer molded body 1 in the electronic component 100. The gap 3a of the copper wiring 3 is formed at the interface with the polymer molded body 1, and the gap 3a is filled with a resin component and cured to become the resin filled portion 13, and the adhesiveness between the copper wiring 3 and the polymer molded body 1 It is possible to improve.

FIG. 3 is a schematic cross-sectional view showing a method of manufacturing an electronic component of another embodiment. Hereinafter, the present embodiment will be described, but the description overlapping with the above-described embodiment will be omitted. In this manufacturing method, in the preparation step of the first step, as shown in FIG. 3A, the polymer molded product 1 is prepared (preparation step). In the first step, following the preparatory step, as shown in FIG. 3B, a copper paste is applied on the polymer molded body 1 in a predetermined pattern (to the portion where the copper wiring is formed) to form a copper paste layer. 2 is formed (forming step). Then, as shown in FIG. 3C, the copper wiring 3 is formed by sintering the copper particles with each other. (Second step).

Subsequently, as shown in FIG. 3D, a resin layer 14 containing a resin component is formed in a part of the copper wiring 3. The resin component is filled in at least a part of the gap portion 3a of the copper wiring 3 to obtain the resin filling 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 the solder particles 4 and the resin component 5 may be applied to the upper portion of the resin layer 14 applied on the copper wiring 3. The resin layer 14 may or may not be formed in a portion other than the copper wiring 3 to which the electronic element 8 is bonded and cured by exposure or heat in advance. Further, in some cases, the resin layer 14 may be protected from being cured by masking the upper portion of the copper wiring 3, and the upper portion of the copper wiring 3 may be removed by development or the like to form an opening.

The atmosphere at the time of curing of the resin layer 14 may be an oxygen-free atmosphere or a reducing atmosphere from the viewpoint of suppressing oxidation of the copper wiring 3. Examples of the anoxic atmosphere include the introduction of an oxygen-free gas such as nitrogen and a rare gas, or under vacuum. Examples of the reducing atmosphere include pure hydrogen gas, a mixed gas of hydrogen and nitrogen typified by a forming gas, nitrogen containing formic acid gas, a mixed gas of hydrogen and rare gas, and a rare gas containing formic acid gas. Can be mentioned.

The resin layer 14 containing the resin component may be a solder resist. The solder resist can be provided by a conventionally known method. For example, it can be formed by applying, exposing, and developing a photosensitive liquid solder resist on the copper wiring 3 and the polymer molded body 1. Further, as the solder resist, a thermosetting type or an ultraviolet curable type can be used, but an ultraviolet curable type capable of finishing the resist shape with high accuracy is preferable. For example, epoxy-based, polyimide-based, epoxy acrylate-based, fluorene-based materials and the like can be used. These patterns can be formed by printing as long as they are varnish-like materials, but in order to secure more accuracy, it is preferable to use a photosensitive solder resist, a coverlay film, a film-like resist, or the like. ..

Subsequently, as shown in FIG. 3E, the solder paste is applied onto the predetermined copper wiring 3 in a predetermined pattern (third step). The resin component 5 penetrates into the gap 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), the electronic element 8 having the electrode 9 is arranged (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 the solder layer 11, and the copper wiring 3 and the electrode 9 of the electronic element 8 are joined (the fourth step). Step 5). Further, the resin layer 14 is cured to become the resin layer 16. As a result, the electronic component 101 is obtained.

The electronic component 101 obtained by the manufacturing method described above is the solder layer 11 that joins the polymer molded body 1, the copper wiring 3 provided on the polymer molded body 1, 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 are provided. At least a part of the gap 3a of the copper wiring 3 is filled with a cured product having the same resin component as the resin layer 12 or the resin layer 16.

In the method for manufacturing electronic parts according to the present embodiment, since the copper paste is applied in a predetermined pattern (the pattern corresponding to the copper wiring 3), a polymer containing a catalyst is not required, and laser irradiation and electroless copper plating are not required. Step can be omitted. In addition, in these manufacturing methods, after the paste layer 6 is formed on the copper wiring 3, the electronic element 8 is arranged and heat-treated to bond the copper wiring 3 and the electronic element 8 to each other by soldering. At least a part of the solder layer 11 is covered with the resin layer 12, and the resin component filled in at least a part of the gap portion of the copper wiring 3 is cured to form the resin filling portion 13 or the resin filling portion 17. , The adhesiveness between the polymer molded body and the copper wiring can be improved.

In the manufacturing method according to the present embodiment, the electronic element 8 and the copper wiring 3 are formed by using the same component as the resin layer 14 containing the resin component that covers a part of the copper wiring 3 and the resin component 5 in the solder paste. It is possible to perform the solder bonding with the copper wiring 3 and the production of the surface protective coating of the copper wiring 3 in the same process. In this case, the conventional steps (solder resist forming step (copper wiring and forming an opening for solder bonding by coating, exposing, and developing the front surface of the polymer molded body), solder paste wiring opening). Compared with the solder joining process (part mounting) by coating and heat treatment), the process and time for manufacturing can be significantly shortened.

FIG. 4 is a schematic cross-sectional view showing a method of manufacturing an electronic component of another embodiment. Hereinafter, the present embodiment will be described, but the description overlapping with the above-described embodiment will be omitted. In this manufacturing method, in the preparation step of the first step, as shown in FIG. 4A, the polymer molded product 1 is prepared (preparation step). In the first step, following the preparatory step, as shown in FIG. 4B, a copper paste is applied onto the polymer molded body 1 in a predetermined pattern (to the portion where the copper wiring is formed) to form a copper paste layer. 2 is formed (forming step). Then, as shown in FIG. 4 (c), the copper wiring 3 is formed by sintering the copper particles (second step).

Following the second step, as shown in FIG. 4D, a resin composition containing a resin component is applied onto the metal wiring 3 to form a resin layer 14 (third step). By applying the resin composition, at least a part of the void portion 3a of the copper wiring 3 is filled with the resin component to obtain the resin-filled portion 15.

The resin composition can contain a resin component to be blended in the above-mentioned solder paste. The same means as in the case of applying the copper paste described above can be used for applying the resin composition.

The atmosphere at the time of curing may be an oxygen-free atmosphere or a reducing atmosphere from the viewpoint of suppressing oxidation of the copper wiring 3. Examples of the anoxic atmosphere include the introduction of an oxygen-free gas such as nitrogen and a rare gas, or under vacuum. Examples of the reducing atmosphere include pure hydrogen gas, a mixed gas of hydrogen and nitrogen typified by a forming gas, nitrogen containing formic acid gas, a mixed gas of hydrogen and rare gas, and a rare gas containing formic acid gas. Can be mentioned.

Following the third step, the resin layer is removed so that at least a part of the metal wiring is exposed (fourth step). The resin layer can be removed by, for example, a method of scraping with a laser or the like. In this way, the opening 18 is formed as shown in FIG. 4 (e).

Further, the resin layer may be a solder resist. The solder resist can be provided by a conventionally known method. In this case, for example, the opening 18 can be formed by applying, exposing, and developing a photosensitive liquid solder resist. As the solder resist, those described above can be used.

Following the fourth step, as shown in FIG. 4 (f), a solder paste containing solder particles is applied to the upper portion of the copper wiring having the opening 18 (on the exposed portion of the copper wiring) to form a solder paste layer. (Fifth step). In the present embodiment, as shown in FIG. 4 (f), the solder paste 6 contains the solder particles 4 and the resin component 5. In this case, the solder layer and the resin layer covering at least a part of the solder layer can be formed in the seventh step described later.

Following the fifth step, as shown in FIG. 4 (g), the electronic element 8 having the electrode 9 is arranged (mounted) at a predetermined position of the solder paste layer 6 (sixth step).

Following the sixth step, as shown in FIG. 4H, 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 (the sixth step). Step 7). Further, the resin component 5 is cured to become a resin layer 12. As a result, the electronic component 102 is obtained.

FIG. 5 is a schematic cross-sectional view showing a method of manufacturing an electronic component of another embodiment. Hereinafter, the present embodiment will be described, but the description overlapping with the above-described embodiment will be omitted. In this manufacturing method, in the preparation step of the first step, as shown in FIG. 5A, the polymer molded product 1 is prepared (preparation step). In the first step, following the preparatory step, as shown in FIG. 5B, a copper paste is applied onto the polymer molded body 1 in a predetermined pattern (to the portion where the copper wiring is formed) to form a copper paste layer. 2 is formed (forming step). Then, as shown in FIG. 5C, the copper wiring 3 is formed by sintering the copper particles (second step).

Following the second step, as shown in FIG. 5D, a solder paste containing solder particles is applied onto the metal wiring 3 to form a solder paste layer 6 (third step).

Following the third step, the electronic element 8 having the electrode 9 is arranged (mounted) at a predetermined position of the solder paste layer 6 (fourth step). Following the fourth step, as shown in FIG. 5 (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 (the fourth step). Step 5).

Following the fifth step, a sealing material containing a curable resin component between the polymer molded body 1 and the electronic element 8 connected to the polymer molded body 1 via the metal wiring 3 and the solder layer 11. Is impregnated and cured (sixth step). As a result, the electronic component 103 is obtained. In the electronic component 103, at least a part of the gap portion 3a of the copper wiring 3 is filled with a curable resin component to obtain a resin-filled portion 19, and the polymer molded body 1 and the electronic element 8 are cured of the curable resin component. It is adhered by the resin layer 12 which is a thing. Further, the solder layer 11 can be covered with the resin layer 12.

As the curable resin component of the sealing material, the resin component blended in the above-mentioned solder paste can be used.

In the electronic component obtained by the method for manufacturing an electronic component according to the present embodiment described above, the flake-shaped copper particles in which the copper wiring is oriented substantially parallel to the bonding interface (for example, the bonding surface between the polymer molded body and the wiring) It is preferable to include a structure derived from.

FIG. 6 is an SEM image showing an example of a cross section of a copper wiring composed of a sintered body of copper particles. The copper wiring 24 shown in FIG. 6 has a structure derived from flaky 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 copper wiring 24, cracking of the wiring can be suppressed by orienting the flake-shaped copper particles substantially parallel to the bonding interface direction. Further, for unknown reasons, the adhesiveness between the wiring and the polymer molded product can be improved.

In the wiring having the copper wiring 24 shown in FIG. 6, in addition to the sintered copper 24a derived from the flake-shaped copper particles, the pores 24b and the copper particles for joining the flake-shaped copper particles to each other (for example, spherical copper particles) ), And the sintered copper derived from) may be further contained. The wiring having the copper wiring 24 is obtained by sintering a copper paste containing, for example, flake-shaped copper particles and, in some cases, copper particles for joining the flake-shaped copper particles (for example, spherical copper particles). Can be formed.

Here, the flake shape includes a flat plate shape such as a plate shape or a scale shape. In the sintered copper 24a derived from the flake-shaped 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, 3.0 μm or more, or 4.0 μm or more. When the sintered copper 24a derived from the flake-shaped copper particles has such a shape, the reinforcing effect of 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 continuity reliability of the wiring is further improved.

The major axis and thickness of the sintered copper 24a derived from the flake-shaped copper particles can be obtained from, for example, an SEM image of a cross section of the wiring. The following is an example of a method of measuring the major axis and thickness of sintered copper derived from flake-shaped copper particles from an SEM image. First, the wiring is cut out into a rectangular parallelepiped shape and used as a measurement sample. The sample is placed in a casting cup, and the epoxy casting resin is poured into the cup so that the entire sample is filled and cured. Cut the cast sample near the cross section you want to observe, grind the cross section by polishing, and perform CP (cross section polisher) processing. The cross section of the sample is observed with an SEM device at a magnification of 5000. A cross-sectional image of the wiring (for example, 5000 times) is acquired, and it is a dense continuous part, which is a linear, rectangular, or elliptical part, and has the longest length of the straight lines contained in this part. The length of the major axis is 1.0 μm or more and the ratio of the major axis / thickness is 4 when the one with the major axis and the one with the longest length among the straight lines included in this part orthogonal to the major axis are defined as the thickness. The above is regarded as sintered copper derived from flake-shaped copper particles, and the major axis and thickness of sintered copper derived from flake-shaped copper particles are measured by image processing software having a length measuring function. The average value thereof can be obtained by calculating the number average with 20 points or more randomly selected.

In the above embodiment, an embodiment in which copper particles are used as the metal particles is described, but the metal particles according to the present embodiment are not limited to copper particles. Particles containing a sinterable metal can be used. The above-mentioned manufacturing process of electronic components can also be applied when metal particles other than copper particles are used.

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.

[Preparation of copper paste]
(Copper paste 1)
Add 150 mL of 1-propanol (Kanto Chemical Co., Inc., special grade) to 91.5 g (0.94 mol) of copper hydroxide (Kanto Chemical Co., Inc., special grade) and stir, to which nonanoic acid (Kanto Chemical Co., Inc., purity 90) % Or more) 370.9 g (2.34 mol) was added. The resulting mixture was heated and stirred at 90 ° C. for 30 minutes in a separable flask. The obtained solution was filtered while being heated to remove undissolved substances. After that, the mixture was allowed to cool, and the produced copper nonanoate was suction filtered and washed with hexane until the washing liquid became transparent. The obtained powder was dried in an explosion-proof oven at 50 ° C. for 3 hours to obtain copper (II) nonanoate. The yield was 340 g (yield 96% by mass).

15.01 g (0.040 mol) of copper (II) nonanoate and 7.21 g (0.040 mol) of copper (II) acetate anhydride (Kanto Chemical Co., Inc., special grade) obtained above were placed in a separable flask. To this, 22 mL of 1-propanol and 32.1 g (0.32 mol) of hexylamine (Tokyo Kasei Kogyo Co., Ltd., purity 99%) were added, and the mixture was dissolved by heating and stirring at 80 ° C. in an oil bath. After transferring to an ice bath and cooling to an internal temperature of 5 ° C., 7.72 mL (0.16 mol) of hydrazine monohydrate (Kanto Chemical Co., Inc., special grade) was added while stirring in the ice bath. The molar ratio of copper to hexylamine (copper: hexylamine) is 1: 4. Then, it was heated and stirred at 90 ° C. in an oil bath. At that time, the reduction reaction accompanied by foaming proceeded, and the reaction was completed within 30 minutes. The inner wall of the separable flask had a copper luster and the solution turned dark red. Centrifugation was performed at 9000 rpm (rotation / min) for 1 minute to obtain a solid.
The step of washing the solid substance with 15 mL of hexane was repeated three times to remove the acid residue to obtain a powder of spherical copper particles having copper luster (copper particles A, second copper particles).

The 50% volume average particle diameter of the copper particles A synthesized above was measured by a Shimadzu nanoparticle size distribution measuring device (SALD-7500 nano, manufactured by Shimadzu Corporation). The 50% volume average particle diameter of the copper particles A was 0.01 μm. The content of the copper particles having a particle size of 0.005 μm or more and 0.8 μm or less in the copper particles A was 100% by mass.

As a dispersion medium, 5.2 g of α-terpineol (manufactured by Wako Pure Chemical Industries, Ltd.), 6.8 g of isobornylcyclohexanol (MTPH, manufactured by Nippon Terpen Chemical Co., Ltd.), and 52.8 g of copper particles A are placed in a poly bottle. The mixture was mixed and treated with an ultrasonic homogenizer (US-600, manufactured by Nippon Seiki Co., Ltd.) at 19.6 kHz and 600 W for 1 minute to obtain a dispersion. Flake-shaped copper particles B (first copper particles, trade name: 1100-YP, manufactured by Mitsui Metal Mining Co., Ltd., 50% volume average particle size 1.5 μm, maximum diameter 1.0 μm or more and 20 μm) are added to this dispersion. 35.2 g (100% by mass of the following copper particles) was added, and the mixture was stirred with a spatula until the dry powder was eliminated. The plastic bottle is tightly closed, and the copper paste 1 is stirred at 2000 rpm for 2 minutes under reduced pressure using a rotating and revolving stirring device (Plantery Vacuum Mixer ARV-310, manufactured by Shinky Co., Ltd.). Obtained.

(Copper paste 2)
1200-YP (trade name, manufactured by Mitsui Mining & Smelting Co., Ltd., 50% volume average particle size 3.1 μm, maximum diameter 1.0 μm or more and 20 μm or less) instead of 1100-YP which is flake-shaped copper particles B Copper paste 2 was obtained in the same manner as copper paste 1 except that the particle content (100% by mass) was used.

(Copper paste 3)
Instead of 1100-YP, which is a flake-shaped copper particle B, MA-C025KFD (trade name, manufactured by Mitsui Metal Mining Co., Ltd., 50% volume average particle size 4.7 μm, maximum diameter 1.0 μm or more and 20 μm or less copper Copper paste 3 was obtained in the same manner as copper paste 1 except that the particle content (100% by mass) was used.

(Copper paste 4)
Instead of 1100-YP, which is flake-shaped copper particles B, MA-C08JF (trade name, manufactured by Mitsui Metal Mining Co., Ltd., 50% volume average particle size 11.9 μm, maximum diameter 1.0 μm or more and 20 μm or less copper A copper paste 4 was obtained in the same manner as the copper paste 1 except that the particle content (100% by mass) was used.

[Preparation of polymer molded product with copper wiring]
(Example 1)
<Preparation of polymer molded product>
As a polymer molded product, a flat substrate-shaped polypropylene resin plate (size 80 mm × 40 mm, thickness 3 mm) made of polypropylene (trade name: PP P-2127 for molding, manufactured by Sekisui Molding Co., Ltd.) was prepared.

<Applying copper paste>
As shown in FIG. 7, a screw dispenser (manufactured by Musashi Engineering Co., Ltd.) is used on a polypropylene resin plate (polymer molded body) 40 to form a wiring 41 having a width of 1 mm and a length of 5 cm and a terminal 42 having a size of 5 mm. Copper paste 1 was placed by coating so as to have a shape. As a result, a polypropylene resin plate with a copper paste layer was obtained.

<Sintering of copper paste layer>
The polypropylene resin plate with the copper paste layer obtained above was set in a formic acid reduction furnace (manufactured by Ayumi Kogyo Co., Ltd.). Wiring (copper wiring) composed of a sintered body of copper particles was produced by holding in formic acid at 100 ° C. for 30 minutes. The copper content in the wiring was 80% by volume, and the thickness of the wiring after sintering was 50 μm.

<Formation of solder resist>
Photosensitive liquid solder resist (trade name: SR7300, manufactured by Hitachi Kasei Co., Ltd.) is applied by screen printing so as to cover the front surface of the polypropylene resin plate provided with wiring (copper wiring), and dried at 80 ° C. for 20 minutes. Was done. Except for the 42 parts of the 5 mm square terminal, it was exposed with an exposure device (UX-5 series, manufactured by Ushio, Inc.) (exposure amount: 300 mJ / cm ₂ ), and developed with a 1 mass% Na ₂ CO ₃ solution to 5 mm. The corner terminals 42 were exposed. Then, it was exposed (exposure amount: ² J / cm ² ) by an exposure apparatus (UX-5 series, manufactured by Ushio, Inc.). In this way, a polypropylene resin plate with copper wiring was obtained.

[Evaluation of initial conductivity (initial volume resistivity)]
The initial conductivity was evaluated based on the volume resistivity of the wiring (unit: μΩ · cm). The volume resistivity is obtained by the surface resistance value measured by the 4-end needle surface resistance measuring device and the non-contact surface / layer cross-sectional shape measurement system (VertScan, Ryoka System Co., Ltd.) for the wiring of the polypropylene resin plate with copper wiring. It was calculated from the layer thickness of the wiring.

[Evaluation of conduction reliability]
Using the polypropylene resin plate with copper wiring obtained above, the continuity reliability after the temperature cycle test was evaluated. For the temperature cycle test, a thermal shock device (manufactured by ESPEC, TSA-73ES) is used, and the minimum temperature -40 ° C / maximum temperature + 100 ° C is repeated for 30 minutes each, after 100, 500, 1000, 2000, 3000 cycle tests. The continuity reliability of was investigated. The conduction reliability was evaluated by the volume resistivity of the wiring (unit: μΩ · cm). Specifically, 20 polypropylene resin plates with copper wiring after the temperature cycle test were measured and evaluated according to the following criteria.
A: Average volume resistivity is less than 5 μΩ · cm B: Average volume resistivity is 5 μΩ · cm or more and less than 20 μΩ · cm C: Average volume resistivity is 20 μΩ · cm or more and less than 50 μΩ · cm D: Average volume resistivity However, 50 μΩ ・ cm or more and less than 100 μΩ ・ cm E: Average volume resistivity is 100 μΩ ・ cm or more

(Example 2)
A polypropylene resin plate with copper wiring was produced in the same manner as in Example 1 except that the copper paste 2 was used instead of the copper paste 1, and the initial conductivity and continuity reliability were evaluated.

(Example 3)
A polypropylene resin plate with copper wiring was produced in the same manner as in Example 1 except that the copper paste 3 was used instead of the copper paste 1, and the initial conductivity and continuity reliability were evaluated.

(Example 4)
A polypropylene resin plate with copper wiring was produced in the same manner as in Example 1 except that the copper paste 4 was used instead of the copper paste 1, and the initial conductivity and continuity reliability were evaluated.

(Example 5)
As the polymer molded body, a flat substrate-shaped ABS resin plate (size 80 mm × 40 mm, thickness 3 mm) made of ABS resin is used instead of the flat substrate-shaped polymer molded polypropylene made of polypropylene and baked. An ABS resin plate with copper wiring was produced in the same manner as in Example 1 except that the forming temperature was changed from 100 ° C. to 85 ° C., and the initial conductivity and conduction reliability were evaluated.

(Example 6)
As the polymer molded body, a flat substrate-shaped ABS resin plate (size 80 mm × 40 mm, thickness 3 mm) made of ABS resin is used instead of the flat substrate-shaped polymer molded polypropylene made of polypropylene, and copper is used. An ABS resin plate with copper wiring was produced in the same manner as in Example 1 except that copper paste 2 was used instead of paste 1 and the sintering temperature was changed from 100 ° C. to 85 ° C., and initial conductivity and continuity reliability were obtained. Sexual evaluation was performed.

(Example 7)
As the polymer molded body, a flat substrate-shaped ABS resin plate (size 80 mm × 40 mm, thickness 3 mm) made of ABS resin is used instead of the flat substrate-shaped polymer molded polypropylene made of polypropylene, and copper is used. An ABS resin plate with copper wiring was produced in the same manner as in Example 1 except that the copper paste 3 was used instead of the paste 1 and the sintering temperature was changed from 100 ° C. to 85 ° C., and the initial conductivity and continuity reliability were obtained. Sexual evaluation was performed.

(Example 8)
As the polymer molded body, a flat substrate-shaped ABS resin plate (size 80 mm × 40 mm, thickness 3 mm) made of ABS resin is used instead of the flat substrate-shaped polymer molded polypropylene made of polypropylene, and copper is used. An ABS resin plate with copper wiring was produced in the same manner as in Example 1 except that the copper paste 4 was used instead of the paste 1 and the sintering temperature was changed from 100 ° C. to 85 ° C., and the initial conductivity and continuity reliability were obtained. Sexual evaluation was performed.

(Example 9)
As a polymer molded product, a flat substrate-shaped polycarbonate resin plate (size 80 mm × 40 mm, thickness 3 mm) made of polycarbonate was prepared.

Using a screw dispenser (manufactured by Musashi Engineering Co., Ltd.), copper paste 1 is applied onto a polycarbonate resin plate so that it has the shape of a wiring 41 with a width of 1 mm and a length of 5 cm and a terminal 42 of 5 mm square. (See FIG. 7). As a result, a polymer molded product with a copper paste layer provided with a copper paste layer having a thickness of 20 μm was obtained.

The polycarbonate resin plate with a copper paste layer obtained above is subjected to laser firing (835 nm, 1 W, speed 2 cm / S) under 5% H ₂ / 95% N ₂ , and is composed of a sintered body of copper particles. Wiring (copper wiring) to be used was produced. The copper content in the wiring was 82% by volume, and the thickness of the wiring after sintering was 10 μm.

Subsequently, a solder resist was formed in the same manner as in Example 1 to obtain a polycarbonate resin plate with copper wiring. The obtained polycarbonate resin plate with copper wiring was evaluated for initial conductivity and continuity reliability in the same manner as in Example 1.

(Comparative Example 1)
As a polymer molded product, a flat substrate-shaped polypropylene resin plate (size 80 mm × 40 mm, thickness 3 mm) made of polypropylene was prepared in the same manner as in Example 1, and this was put into xylene heated to 80 ° C. 10 It was soaked for minutes and dried in the air for 10 minutes. Further, heat treatment was performed at 80 ° C. to obtain a polypropylene resin plate having a xylene content of 3% by mass.

Next, using a UV device, the distance from the light source lamp (300.0 mW / cm ² , main wavelength 253.7 nm, sub-wavelength 184.9 nm) to the surface of the polypropylene resin is set to 70 mm, and UV light irradiation for 3 minutes is performed. The entire surface of the polypropylene resin plate was surface-modified. The surface modification was selectively modified so as to have a shape similar to the pattern of the copper paste in Example 1.

The surface-modified polypropylene resin plate was subjected to an alkali treatment and a conditioner treatment, and was subjected to a Sn—Pd mixed catalyst treatment. Then, an electroless Ni plating film having a thickness of 0.2 μm was formed under the following electroless Ni plating bath composition and plating conditions to obtain a polypropylene resin plate with an electroless Ni plating film. By selectively depositing the electroless Ni plating film on the surface-modified portion, the electroless Ni plating film was formed in the same shape as the copper paste layer of Example 1. Then, electrolytic copper plating was performed using a copper sulfate plating solution to form a copper wiring having a thickness of 20 μm.

<Electroless Ni plating bath composition>
Nickel sulfate hexahydrate 25 g / L
Glycine 8g / L
Ammonium sulphate 25 g / L
Citric acid anhydride 20 g / L
Sodium hypophosphate / monohydrate 20 g / L
Bismuth 1ppm
Sodium thiosulfate 2ppm
Bath temperature: 45 ° C, pH: 8.0

Subsequently, a solder resist was formed in the same manner as in Example 1 to obtain a polypropylene resin plate with copper wiring. The obtained polypropylene resin plate with copper wiring was evaluated for initial conductivity and continuity reliability in the same manner as in Example 1.

(Comparative Example 2)
As a polymer molded product, a flat substrate-shaped ABS resin plate (size 80 mm × 40 mm, thickness 3 mm) made of ABS resin is prepared as in Example 5, and the following pre-etching step, alkali treatment step, and predip are performed. A step, a catalyst treatment step, an activation treatment step, and a plating treatment step were performed. By covering the portion other than the surface modification portion with a polyimide tape before the pre-etching step and peeling off the polyimide tape before the plating treatment step, a plating film having the same shape as the copper paste pattern in Example 1 was obtained.

<Pre-etching process>
A solution containing 600 g / L of N, N-dimethylformamide (DMF) and 200 g / L of ethylene glycol was prepared, and the ABS resin plate was immersed at 30 ° C. for 5 minutes. Next, the ABS resin plate after immersion was heat-treated at 70 ° C. under heating conditions for 2 hours. After the heat treatment step, the ABS resin plate was immersed in ozone water at 30 ppm and 20 ° C. for 8 minutes.

<Alkaline treatment process>
A mixed aqueous solution prepared by dissolving 50 g / L of NaOH and 1 g / L of sodium lauryl sulfate was prepared, and the ABS resin plate subjected to the pre-etching step was immersed in this solution at 50 ° C. for 3 minutes.

<Pre-dip process>
The ABS resin plate that had undergone the alkali treatment step was immersed in 35% by mass hydrochloric acid at room temperature for 1 minute.

<Catalyst treatment process>
A catalyst solution was prepared by dissolving 0.1% by mass of palladium chloride and 5% by mass of tin chloride in a 3N hydrochloric acid aqueous solution. The ABS resin plate that had undergone the predip step was immersed in the catalyst solution heated to 35 ° C. for 4 minutes.

<Activation process>
Next, in order to activate palladium, the ABS resin plate that had undergone the catalytic treatment step was immersed in 35% by mass of hydrochloric acid at room temperature for 4 minutes.

<Plating process>
An electroless Ni plating film having a thickness of 0.2 μm was formed on the activated ABS resin plate under the same electroless Ni plating bath composition and plating conditions as in Comparative Example 1, and the ABS resin with the electroless Ni plating film was formed. I got a board. The electroless Ni plating film was selectively deposited on the surface-modified portion, so that the electroless Ni plating film was formed in the same shape as the copper paste layer of Example 1. Then, electrolytic copper plating was performed using a copper sulfate plating solution to form a copper wiring having a thickness of 20 μm.

Subsequently, a solder resist was formed in the same manner as in Example 1 to obtain an ABS resin plate with copper wiring. The obtained ABS resin plate with copper wiring was evaluated for initial conductivity and continuity reliability in the same manner as in Example 1.

1,40 ... Polymer molded body, 2 ... Copper paste layer, 3,24 ... Copper wiring, 3a ... Voids, 4 ... Solder particles, 5 ... Resin components, 6 ... Solder paste layer, 7,13,15,17, 19 ... Resin filling part, 8 ... Electronic element, 9 ... Electrode, 11 ... Solder layer, 12, 14, 16 ... Resin layer, 18 ... Opening, 41 ... Wiring, 42 ... Terminal, 100, 101, 102, 103 ... Electronic components.

Claims (12)

The first step of applying a metal paste containing metal particles to a polymer molded product in a predetermined pattern to form a metal paste layer, and
The second step of forming the metal wiring by sintering the metal particles, and
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, and
The fourth step of arranging the electronic element on the solder paste layer and
A fifth step of heating the solder paste layer to form a solder layer for joining the metal wiring and the electronic element, and forming a resin layer covering at least a part of the solder layer.
With
A method for producing an electronic component, wherein the polymer molded product is a molded product of a crystalline plastic having a melting point of 280 ° C. or lower or an amorphous plastic having a glass transition temperature of 160 ° C. or lower. The third step, the solder resist is formed so that at least a part of the metal wiring is exposed, and the solder paste is applied on the exposed portion of the metal wiring to form a solder paste layer. The method for manufacturing an electronic component according to 1. The first step of applying a metal paste containing metal particles to a polymer molded product in a predetermined pattern to form a metal paste layer, and
The second step of forming the metal wiring by sintering the metal particles, and
A third step of applying a resin composition containing a resin component onto the metal wiring to form a resin layer, and
A fourth step of removing the resin layer so that at least a part of the metal wiring is exposed.
A fifth step of applying a solder paste containing solder particles onto the exposed portion of the metal wiring to form a solder paste layer, and
The sixth step of arranging the electronic element on the solder paste layer and
A seventh step of heating the solder paste layer to form a solder layer for joining the metal wiring and the electronic element.
With
A method for producing an electronic component, wherein the polymer molded product is a molded product of a crystalline plastic having a melting point of 280 ° C. or lower or an amorphous plastic having a glass transition temperature of 160 ° C. or lower. The method for manufacturing an electronic component according to claim 3, wherein the solder paste further contains a resin component to form the solder layer and a resin layer covering at least a part of the solder layer in the seventh step. The first step of applying a metal paste containing metal particles to a polymer molded product in a predetermined pattern to form a metal paste layer, and
The second step of forming the metal wiring by sintering the metal particles, and
A third step of applying a solder paste containing solder particles onto the metal wiring to form a solder paste layer, and
The fourth step of arranging the electronic element on the solder paste layer and
A fifth step of heating the solder paste layer to form a solder layer for joining the metal wiring and the electronic element.
A sixth that impregnates and cures a sealing material containing a curable resin component between the polymer molded product and the electronic element connected to the polymer molded product via the metal wiring and the solder layer. Process and
With
A method for producing an electronic component, wherein the polymer molded product is a molded product of a crystalline plastic having a melting point of 280 ° C. or lower or an amorphous plastic having a glass transition temperature of 160 ° C. or lower. The method for producing an electronic component according to any one of claims 1 to 5, wherein the polymer molded product contains polypropylene, ABS resin, or polycarbonate. The method for manufacturing an electronic component according to any one of claims 1 to 6, wherein the metal particles are sintered by laser irradiation or heating at 120 ° C. or lower in an atmosphere containing formic acid to form the metal wiring. .. Any one of claims 1 to 7, wherein the metal paste contains 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 method for manufacturing electronic components according to the section. The method for manufacturing an electronic component according to any one of claims 1 to 8, wherein the thickness of the metal wiring is 10 μm or more. Polymer molding and
A metal wiring provided on the polymer molded body and composed of a sintered body of metal particles,
Electronic elements arranged on the metal wiring and
A solder layer that joins the metal wiring and the electronic element,
With
The polymer molded product is a molded product of a crystalline plastic having a melting point of 280 ° C. or lower or an amorphous plastic having a glass transition temperature of 160 ° C. or lower.
An electronic component in which the metal wiring has a gap and the gap is filled with a resin component. The electronic component according to claim 10, further comprising a resin layer that covers at least a part of the solder layer. The electronic component according to claim 10 or 11, wherein the thickness of the metal wiring is 10 μm or more.