JP4347381B2 - Paste silver composition for adhesion of metal-based adherend, method for producing the same, and method for bonding metal-based adherend - Google Patents

Description

【００４１】
【表２】

【００４２】
以上の結果により、本発明のペースト状銀組成物が、加熱焼結性に優れ、被着体を電気伝導性と熱伝導性よく強固に接着させるのに有用であり、耐磨耗性を基板への接着性と電気伝導性と熱伝導性が優れた銀回路を形成するのに有用であることがわかる。
【産業上の利用可能性】
【００４３】
本発明の金属系被着体接着用ペースト状銀組成物および金属系被着体の接着方法は、プリント回路基板上の導電性回路の形成、抵抗器やコンデンサ等の各種電子部品及び各種表示素子の電極の形成、電磁波シールド用導電性被膜の形成、コンデンサ、抵抗、ダイオード、メモリ、演算素子（ＣＰＵ）等のチップ部品の基板への接着、太陽電池の電極の形成、積層セラミックコンデンサ、積層セラミックインダクタ、積層セラミックアクチュエータ等のチップ型セラミック電子部品の外部電極の形成等に有用である。本発明の金属系被着体接着用ペースト状銀組成物の製造方法は、該ペースト状銀組成物を効率よく製造するのに有用である。 【Technical field】
[0001]
The present invention comprises substantially spherical silver particles and a volatile dispersion medium, and is sintered by heating to form solid silver having excellent strength, electrical conductivity and thermal conductivity.For bonding metal adherendsPasty silver composition, method for producing the same,and,Using the pasty silver compositionOf metallic adherendThe present invention relates to an adhesion method.
[0002]
Conductive paste made by dispersing silver powder in thermosetting resin composition is cured by heating to form a conductive film, so that conductive circuit formation on printed circuit boards, resistors, capacitors, etc. Electrode formation of various electronic parts and display elements, formation of a conductive film for electromagnetic wave shielding, adhesion of chip parts such as capacitors, resistors, diodes, memories and arithmetic elements (CPUs) to substrates, solar cell electrodes, In particular, it is used for forming electrodes of solar cells that cannot be processed at high temperature using amorphous silicon semiconductors, forming external electrodes of chip-type ceramic electronic components such as multilayer ceramic capacitors, multilayer ceramic inductors, multilayer ceramic actuators, and the like.
In recent years, the amount of heat generated from chip parts has increased due to the high performance of chip parts, and it is required to improve the thermal conductivity as well as the electrical conductivity. When trying to improve the thermal conductivity, there is a problem that the viscosity of the paste increases and the workability is remarkably lowered.
[0003]
On the other hand, highly dispersible spherical silver powder that is optimal for the production of conductive paste that can form electrodes and circuits for chip parts, plasma display panels, etc. with significant fineness, high density, high precision, and high reliability, and the like Patent Document 1 teaches a silver paste using In addition to the screen printing method, an ink jet method has been used as a method for applying the conductive paste to the circuit board. For this reason, the average particle diameter D of the primary particles obtained by image analysis of a scanning electron microscope image._IAA silver ink composed of silver powder and polyols having a particle size of 0.6 μm or less and, if necessary, a viscosity modifier or the like has been proposed (see Patent Document 2).
[0004]
In Patent Literature 1, silver powder is mixed with an aqueous solution of silver nitrate and aqueous ammonia to obtain a silver ammine complex aqueous solution, which is contacted with an aqueous solution of hydroquinone, anhydrous potassium sulfite or ammonium and gelatin to reduce the silver powder. And the residue is washed with water and dried under heating. Patent Document 1 describes that a silver paste was prepared using the silver powder prepared as described above, but its prescription is unknown. Therefore, when the present inventors mixed a small amount of water with the silver powder and heated it to a paste, there was a problem that the silver powder was not sufficiently sintered, or solid silver was produced by sintering. However, I realized that there was a problem that strength, electrical conductivity and thermal conductivity were unexpectedly small. In Patent Document 2, silver powder is obtained by mixing a silver nitrate aqueous solution and aqueous ammonia to react to obtain a silver ammine complex aqueous solution, which is contacted with an organic reducing agent (hydroquinone, ascorbic acid, glucose, etc.), in particular, an aqueous solution of hydroquinone. The silver powder is reduced and precipitated by reaction, filtered, and the residue is washed with water and methanol and dried under heating. However, when the present inventors heated the silver ink comprising the silver powder and polyols prepared in this way (for example, 1,4-butanediol, dipropylene glycol), the silver powder was not sufficiently sintered. I noticed that there was a problem that even if solid silver was formed by sintering, the strength, electrical conductivity, and thermal conductivity were unexpectedly small.
[0005]
[Patent Document 1]
JP 2001-107101 A
[Patent Document 2]
JP 2005-93380 A
DISCLOSURE OF THE INVENTION
[Problems to be solved by the invention]
[0006]
As a result of earnest research to develop a spherical silver particle paste without the above problems, that is, a paste-like silver composition, the present inventors have determined that the carbon content of the spherical silver particles is formed by sintering and sintering. It has been found that the strength, electrical conductivity, and thermal conductivity of shape silver are affected, and the present invention has been completed. The object of the present invention is that when heated, the spherical silver particles are easily sintered to form solid silver having excellent strength, electrical conductivity and thermal conductivity.For bonding metal adherendsPasty silver composition, method for producing the same,and,Using the pasty silver compositionMetallicA method of firmly bonding adherends with good electrical and thermal conductivityThe lawIt is to provide.
[0007]
This purpose is
[1] (A) Spherical silver particles produced by a reduction method having an average particle diameter of 0.1 to 6 μm and a carbon content of 0.50% by weight or less; and (B) a boiling point of 70 to 250 ° C. InTheWater, volatile monohydric alcohol, volatile aliphatic hydrocarbon, volatile ketone, volatile lower aliphatic carboxylic acid esterandSelected from volatile silicone oilVolatile dispersion mediumThe volatile dispersion medium is volatilized by heating at 100 ° C. or more and 250 ° C. or less, and the spherical silver particles are sintered with each other, and the volume resistivity is 1 × 10.^-FourMetal system characterized in that it is solid silver having Ω · cm or less and thermal conductivity of 5 W / m · K or more.ofAdherendJoining each otherPasty silver composition.
[2] Volume resistivity is 1 × 10^-FiveThe metal system according to [1], characterized in that it is a solid silver having an Ω · cm or less and a thermal conductivity of 10 W / m · K or more.ofAdherendJoining each otherPasty silver composition.
[3] The carbon content is 0.25% by weight or less, according to [1]For joining metal substratesPasty silver composition.
[4] The volatile monohydric alcohol is ethyl alcohol, propyl alcohol, butyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol or benzyl alcohol, and volatile aliphatic hydrocarbons are lower n -Metal system according to [1] or [2], characterized in that it is paraffin or lower isoparaffinofAdherendJoining each otherPasty silver composition.
[5] The volatile dispersion medium is a mixture of water and butyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol or benzyl alcohol, [1] or [2] Metal system describedofAdherendJoining each otherPasty silver composition.
[6] Spherical silver particles produced by a reduction method having an average particle diameter of 0.1 to 6 μm are washed to reduce their carbon content to 0.50% by weight or less, and (B) a boiling point of 70 to 250 ° C. InTheWater, volatile monohydric alcohol, volatile aliphatic hydrocarbon, volatile ketone, volatile lower aliphatic carboxylic acid esterandSelected from volatile silicone oilVolatile dispersion mediumThe volatile dispersion medium is volatilized by heating at 100 ° C. or more and 250 ° C. or less, and the spherical silver particles are sintered with each other.^-FourMetal system that becomes solid silver with Ω · cm or less and thermal conductivity of 5 W / m · K or moreofAdherendJoining each otherFor producing a paste-like silver composition.
[7] Volume resistivity is 1 × 10^-FiveThe metal system according to [6], wherein the solid silver is Ω · cm or less and has a thermal conductivity of 10 W / m · K or more.ofAdherendJoining each otherFor producing a paste-like silver composition.
[8] The metal system according to [6], wherein the carbon content of the spherical silver particles is 0.25% by weight or less.ofAdherendJoining each otherFor producing a paste-like silver composition.
[9] The metal system according to [6], wherein the cleaning agent is water, a volatile hydrophilic solvent or an aliphatic hydrocarbon solvent.ofAdherendJoining each otherFor producing a paste-like silver composition.
[10] (A) Spherical silver particles produced by a reduction method having an average particle diameter of 0.1 to 6 μm and a carbon content of 0.50% by weight or less, and (B) a boiling point of 70 to 250 ° C. InTheWater, volatile monohydric alcohol, volatile aliphatic hydrocarbon, volatile ketone, volatile lower aliphatic carboxylic acid esterandSelected from volatile silicone oilVolatile dispersion mediumThe volatile dispersion medium is volatilized by heating at 100 ° C. or more and 250 ° C. or less, and the spherical silver particles are sintered with each other, and the volume resistivity is 1 × 10.^-FourA paste-like silver composition that becomes solid silver having a Ω · cm or less and a thermal conductivity of 5 W / m · K or more is interposed between a plurality of metal-based adherends, and is 100 ° C. or more and 250 ° C. The metal system characterized in that the volatile dispersion medium is volatilized by heating at the following, the spherical silver particles are sintered together, and a plurality of metal-based adherends are bonded to each other.ofAdherendMutualofJoiningMethod.
[11] The pasty silver composition has a volume resistivity of 1 × 10^-FiveThe metal system according to [10], characterized in that it is a paste-like silver composition that becomes solid silver having an Ω · cm or less and a thermal conductivity of 10 W / m · K or more.ofAdherendMutualofJoiningMethod.
[12] The metal system according to [10], wherein the spherical silver particles have a carbon content of 0.25% by weight or less.ofAdherendMutualofJoiningMethod.
[13] The volatile monohydric alcohol is ethyl alcohol, propyl alcohol, butyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol or benzyl alcohol, and volatile aliphatic hydrocarbons are lower n -The metal system according to [10] or [11], which is paraffin or lower isoparaffinofAdherendMutualofJoiningMethod.
[14] The volatile dispersion medium is a mixture of water and butyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol or benzyl alcohol, [10] or [ 11] Metal system describedofAdherendMutualofJoiningMethod.
[15]MetallicThe metal system according to [10] or [11], wherein the adherend is an electronic component having a metal memberofAdherendMutualofJoiningMethod. Achieved by;
[0008]
Of the present inventionFor bonding metal adherendsIn the paste-like silver composition, the volatile dispersion medium is volatilized by heating, and the spherical silver particles are sintered by heating at 100 ° C. or more, and the solid, excellent in strength, electrical conductivity, and thermal conductivity. Shape silver. Of the present inventionFor bonding metal adherendsThe method for producing a paste-like silver composition is such that the volatile dispersion medium is volatilized by heating, and particularly when the spherical silver particles are sintered by heating at 100 ° C. or higher, strength, electrical conductivity and thermal conductivity are obtained. Excellent solid silverFor bonding metal adherendsPasty silver composition can be easily manufactured. BookInventionOf metallic adherendThe bonding method is to paste a pasty silver composition into a plurality ofMetallicInterpose between adherends, 100 ° C or higher250 ° C or lessThe volatile dispersion medium is volatilized by heating at a temperature, and the spherical silver particles are sintered to form a plurality ofMetallicAdherents can be firmly bonded with good electrical and thermal conductivity.The
[Brief description of the drawings]
[0009]
FIG. 1 is a plan view of a test specimen A for measurement of adhesion strength in an example. The chip capacitor terminal electrode 3 and the electrode land (pad) portion 4 are soldered, so that the chip capacitor 2 fixes the test body A for fixing strength mounted on the glass fiber reinforced epoxy resin substrate 1, and the chip capacitor 2 is pressed in the direction of the arrow to measure the fixing strength of the joint portion between the chip capacitor 2 and the glass fiber reinforced epoxy resin substrate 1.
2 is a cross-sectional view taken along line YY ′ in FIG.
Explanation of symbols
[0010]
A Test specimen for measuring bond strength
1 Glass fiber reinforced epoxy resin substrate
2 Chip capacitor
3 Terminal electrode of chip capacitor
4 Electrode land (pad) part
5 Pasty silver composition
BEST MODE FOR CARRYING OUT THE INVENTION
[0011]
The pasty silver composition of the present invention comprises (A) spherical silver particles having an average particle diameter of 0.1 to 6 μm and a carbon content of 0.50% by weight or less, (B) water and a boiling point of 70. It consists of a volatile monohydric alcohol having ˜250 ° C. and a volatile dispersion medium selected from non-alcoholic volatile dispersion media having a boiling point of 70 to 250 ° C. The average particle size of the spherical silver particles is the average particle size of primary particles obtained by image analysis of a scanning electron microscope image.The flatWhen the average particle size exceeds 6 μm, the sinterability between spherical silver particles becomes small, and it is difficult to obtain excellent strength, electrical conductivity, thermal conductivity, and adhesiveness. Therefore, it is more preferable that the average particle size is small, and it is particularly preferable that the average particle size is 3 μm or less. When the so-called nano-size is less than 0.1 μm, the surface activity of the spherical silver particles is too strong, and the storage stability of the pasty silver composition may be lowered.
The carbon content of the spherical silver particles is 0.50% by weight or less, and the lower limit is 0% by weight. In terms of the sinterability of spherical silver particles during heating and the strength, electrical conductivity, and thermal conductivity of the solid silver obtained by sintering, it is preferably 0.25% by weight or less, more preferably 0.13% by weight. % Or less. Here, the carbon content is determined by an infrared absorption spectrum method in which spherical silver particles are heated in an oxygen stream and carbon in an organic compound adhering to the spherical silver particles is changed to carbon dioxide. Note that the carbon content may be calculated from the decrease by thermogravimetry (TGA).
[0012]
The spherical silver particles are particularly spherical silver particles produced by a reduction method. As described in the above-mentioned patent document, in the reduction method, an aqueous silver ammine complex solution is usually obtained by mixing and reacting an aqueous silver nitrate solution and aqueous ammonia, and an aqueous solution of hydroquinone, anhydrous potassium sulfite or ammonium and gelatin. The silver powder is reduced and deposited by contact reaction, filtered, and the residue is washed with water and dried under heating. Alternatively, a silver nitrate aqueous solution and aqueous ammonia are mixed and reacted to obtain a silver ammine complex aqueous solution, which is contacted with an aqueous solution of an organic reducing agent (hydroquinone, ascorbic acid, glucose, etc.) to cause silver powder to be reduced and precipitated, and filtered. It is prepared by washing and drying. The filtration residue contains ammonia, hydroquinone, anhydrous potassium sulfite or ammonium, and gelatin. Since ammonia, hydroquinone, anhydrous potassium sulfite, ammonium, and gelatin adhere to the silver powder surface, it is repeatedly washed with clean water. . Alternatively, the filtration residue contains ammonia and an organic reducing agent (hydroquinone, ascorbic acid or glucose), and since ammonia and an organic reducing agent (hydroquinone, ascorbic acid or glucose) are attached to the surface of the silver particles, the filtration residue is clean. Washed repeatedly with water and methanol.
[0013]
However, the organic reducing agent can be sufficiently removed even if spherical silver particles with a small water solubility such as hydroquinone and poorly soluble in methanol adhere to water or repeatedly washed with water and methanol. It is not a thing. In particular, hydroquinone present between aggregated spherical silver particles has low solubility in water and methanol, and thus cannot be easily removed even by repeated washing with water and methanol. Further, ascorbic acid and glucose are water-soluble, but ascorbic acid or glucose present between the aggregated spherical silver particles cannot be easily removed even by repeated washing with water or water and methanol.
[0014]
Commercially available spherical silver particles obtained by the reduction method are spherical silver particles that have been washed well with water, or spherical silver particles that have been washed with water and methanol. In the present invention, the carbon content is 0.50% by weight or less, preferably by washing with a lower alcohol having 2 or more carbon atoms such as ethanol, or by washing with water and methanol. Spherical silver particles having a concentration of 0.25% by weight or less are used. It is not only washed, but also washed with physical and mechanical force so that the aggregates are dispersed in or near the primary particles, filtered and discarded, and the residue again like ethanol. By washing with a lower alcohol having 2 or more carbon atoms, or water and methanol, the carbon content is 0.50% by weight or less, preferably 0.25% by weight or less, more preferably 0.13% by weight or less. The resulting spherical silver particles are used. In particular, the primary particles of spherical silver particles or those washed in the vicinity thereof are used by stirring so as to break up aggregates of spherical silver particles with a mortar or the like. The spherical silver particles after washing are preferably dried. The drying conditions are not limited, but it is preferable to dry at less than 100 ° C., particularly at room temperature, in order to prevent fusion of spherical silver particles during drying. It may be placed under reduced pressure or ventilation to promote drying.
[0015]
However, some of the well-cleaned spherical silver particle products that are commercially available by the reduction method have a carbon content of less than 0.50% by weight in some of the lots. Therefore, in the present invention, the carbon content of the obtained spherical silver particle product is inspected and selected to be 0.50% by weight or less, and used to prepare a paste-like silver composition. May be.
[0016]
The carbon content of the spherical silver particles thus obtained is 0.50% by weight or less, preferably 0.25% by weight or less, and more preferably 0.13% by weight or less. The sinterability of silver particles and the strength, electrical conductivity, and thermal conductivity of solid silver obtained by sintering are excellent. The surface of the spherical silver particles may be slightly oxidized. If the ratio of silver oxide is high, a large amount of oxygen is generated during heating, which may cause voids in the solid silver produced by sintering. 50% or less of the entire surface is preferable, particularly 20% or less, and more preferably 2% or less. In particular, in use cases such as a die bond agent that becomes a semi-sealed system with a relatively large bonding area for connecting a large chip such as a memory or a CPU, the presence of silver oxide is not preferable because it causes a decrease in adhesive strength due to the generation of voids.
[0017]
The pasty silver composition of the present invention has substantially spherical silver particles and volatility having a carbon content of 0.50% by weight or less, preferably 0.25% by weight or less, more preferably 0.13% by weight or less. It is a mixture with a dispersion medium, and powdery spherical silver particles are made into a paste by the action of a volatile dispersion medium. By making a paste, it becomes easy to discharge from a cylinder or nozzle in a thin line shape, and it becomes easy to apply to the shape of an electrode. The volatile dispersion medium is used instead of the non-volatile dispersion medium because the spherical silver particles are easily sintered when the dispersion medium volatilizes when the spherical silver particles are sintered by heating. This is because strength, electrical conductivity, and thermal conductivity tend to increase. The volatile dispersion medium does not alter the surface of the spherical silver particles and has a boiling point of 70 ° C. or higher and preferably 250 ° C. or lower. When the boiling point is less than 70 ° C., the solvent easily evaporates during the preparation of the paste-like silver composition, and when the boiling point is greater than 250 ° C., the volatile dispersion medium remains after the spherical silver particles are sintered. Because it might be. As such a volatile dispersion medium, water; volatile monohydric alcohols such as ethyl alcohol, propyl alcohol, butyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, benzyl alcohol; -Volatile aliphatic hydrocarbons such as paraffin and lower isoparaffin; volatile ketones such as acetone and methyl ethyl ketone; volatile lower aliphatic carboxylic acid esters such as ethyl acetate, and low molecular weight volatile silicone oils. Water is most preferable in terms of safety when mixed with spherical silver particles and heating, and generation of VOC is substantially zero, followed by ethyl alcohol, propyl alcohol, butyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, Volatile monohydric alcohols such as octyl alcohol, nonyl alcohol, decyl alcohol and benzyl alcohol are preferred. This is because these volatile monovalent linear alcohols having 2 to 10 carbon atoms are excellent in extrudability and dischargeability from a metal mask or syringe when made into a paste-like silver composition. Then volatile aliphatic hydrocarbons such as lower n-paraffins and lower isoparaffins are preferred. The water is preferably pure water, and its electric conductivity is preferably 100 μs / cm or less, more preferably 10 μs / cm or less, and even more preferably 3 μs / cm or less. A pure water production method may be a normal method, and examples include an ion exchange method, a reverse osmosis method, and a distillation method.
When the volatile dispersion medium is water, adding monohydric alcohol having 4 to 10 carbon atoms to water increases the surface tension in the high temperature range (Marangoni effect), making it easy to control the coating shape retention. Become. Illustrative is adding 0.01 to 5 times the amount of butyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol or benzyl alcohol in a weight ratio to the water in the pasty silver composition. Is done.
[0018]
The blending amount of the volatile dispersion medium may be an amount sufficient to make the spherical silver particles into a paste, and as a guide, it is 5 to 20 parts by weight, preferably 6 to 16 parts per 100 parts by weight of the spherical silver particles. Parts by weight. The paste-like silver composition of the present invention may be added with a small amount or a small amount of additives such as metal-based or non-metallic powder other than silver, thixotropic agent, stabilizer, colorant, etc., unless it is contrary to the object of the present invention. May be.
[0019]
The paste-like silver composition of the present invention is a solid silver having excellent strength, electrical conductivity, and thermal conductivity by volatilization of the volatile dispersion medium by heating and sintering of the spherical silver particles. Become. At this time, the volatile dispersion medium is volatilized, and then the spherical silver particles may be sintered together, or the spherical silver particles may be sintered together with the volatilization of the volatile dispersion medium. The property is excellent. Since silver inherently has high strength and extremely high electrical and thermal conductivity, the sintered product of the spherical silver particles of the present invention also has high strength and extremely high electrical and thermal conductivity. The heating temperature at this time should just be the temperature which a volatile dispersion medium volatilizes and a spherical silver particle can be sintered, and is 100 degreeC or more normally, 150 degreeC or more is more preferable, 180 degreeC or more is further more preferable. However, at 300 ° C. or higher, the volatile dispersion medium may suddenly evaporate and the solid silver shape may be adversely affected.
Solid silver made by sintering the spherical silver particles has an electrical conductivity of volume resistivity.1 × 10 ^{- 4} Ω · cm or less, preferably1 × 10^-FiveΩ · cm or less. Its thermal conductivity is5W / m · K or more, preferably10 W / m · K or more. The shape of the solid silver formed by sintering the spherical silver particles is not particularly limited, and examples thereof include a sheet shape, a film shape, a tape shape, a circuit shape, a disk shape, and a block shape.
[0020]
When the paste-like silver composition of the present invention is heated at 100 ° C. or higher, the volatile dispersion medium is volatilized and the spherical silver particles are sintered together, so that the solid silver paste has a large strength, extremely high electrical conductivity and thermal conductivity. Since it becomes silver, a silver circuit excellent in wear resistance and adhesion to the substrate can be formed by applying to a circuit board substrate and heating. The manufacturing method of the circuit board of this invention consists of apply | coating the pasty silver composition of this invention to the board | substrate for circuit boards, and heating at 100 degreeC or more. The heating temperature is more preferably 150 ° C. or higher, and further preferably 180 ° C. or higher. However, when the temperature is 300 ° C. or higher, the volatile dispersion medium may be suddenly evaporated to adversely affect the shape of the silver circuit. The method of applying is not particularly limited, and includes dispensing application, printing application, spray application, brush application, and the like. A typical example of the circuit board substrate is a glass fiber reinforced epoxy resin plate, but other examples include a polyimide film, a polyamideimide film, a BT resin plate, an alumina ceramic plate, and a glass plate.
[0021]
When the paste-like silver composition of the present invention is heated at 100 ° C. or higher, the volatile dispersion medium is volatilized and the spherical silver particles are sintered, whereby the strength, electrical conductivity, and thermal conductivity are excellent, and the contacted group Since it becomes solid silver having adhesiveness to a material, for example, a silver plate or a silver-plated metal plate, it is interposed between a plurality of adherends and heated at 100 ° C. or more, so that a plurality of adherends, particularly silver Metal system like gold, copper, silver plating, gold platingCoveredThis is useful for firmly bonding and joining the kimonos. Therefore, the bonding method of the present invention is useful for bonding / joining electronic components and electronic devices having metal members such as silver, gold, copper, silver plating, and gold plating. 1 and 2 also show an embodiment of such adhesion and bonding. Such bonding includes bonding of chip components such as capacitors and resistors and circuit boards; bonding of semiconductor chips such as diodes, memories, and CPUs to lead frames or circuit boards; bonding of high heat generating CPU chips and cooling plates. Is exemplified. Examples of the circuit board include a single-layer printed wiring board and a multilayer printed wiring board.
[0022]
The pasty silver composition of the present invention does not require cleaning after heating to sinter the silver particles, but it can dissolve the organic additive if it contains a small or trace amount of organic additive. It is preferable to wash with an appropriate solvent. In particular, when the volatile dispersion medium is water, it can be washed with water, and there is no problem of VOC generation as in the case of washing with an organic solvent such as alcohol. Basically, each component of the pasty silver composition of the present invention can be easily cleaned because it contains few impurities.
[0023]
Since the pasty silver composition of the present invention contains a volatile dispersion medium, it is preferably stored in a sealed container. When used after long-term storage, it is preferable to use the container after shaking or stirring the container. Refrigerated storage may be performed for the purpose of improving storage stability, and the storage temperature is exemplified by 5 ° C. or less.
【Example】
[0024]
Examples and comparative examples of the present invention will be given. In the examples and comparative examples, “parts” means “parts by weight”. The carbon content in the spherical silver particles, and the fixing strength, volume resistivity and thermal conductivity of the solid silver produced by heating and sintering the paste-like silver composition are 25 ° C. by the following methods. It was measured.
[0025]
[Carbon content]
Spherical silver particles were heated by high frequency in an oxygen stream, and carbon in the organic compound adhering to the spherical silver particles was changed to carbon dioxide gas and quantified by infrared absorption spectroscopy.
[0026]
[Fixing strength]
A 150 μm-thick metal mask is used for two 0.8 mm × 1.2 mm electrode land (pad) portions (silver plating finish) provided on a 100 mm × 40 mm glass fiber reinforced epoxy resin substrate with a 1 mm interval. After applying a paste-like silver composition and mounting a 2012 chip capacitor (silver plated on both ends) with a chip mounter, heating in a forced circulation oven at 200 ° C. for 30 minutes resulted in water, lower isoparaffin or alcohol. The spherical silver particles were sintered together with the volatilization, and the land (pad) part and the 2012 chip capacitor (both ends silver plating finish) were joined. The bonded specimen thus obtained was pressed at a pressing speed of 23 mm / min with a bond strength tester, and the load when sheared was used as the bond strength (unit: kgf).
[0027]
[Volume resistivity]
Using a metal mask having a thickness of 10 mm and an opening having a length of 50 mm and a thickness of 100 μm, a paste-like silver composition is printed and applied onto an electrically insulating FR-4 glass fiber reinforced epoxy resin substrate. When heated in an oven at 200 ° C. for 30 minutes, spherical silver particles were sintered together with a volatilization of water, lower isoparaffin or alcohol to form a film. About film-form silver, the voltage of 10 volts was applied between the measurement ends of 50 mm length, resistance was measured, and volume resistivity (unit; ohm * cm) was computed.
[0028]
[Thermal conductivity]
A pasty silver composition was applied between 10 mm × 10 mm square silicon wafers to a thickness of 40 μm or 80 μm and heated in a forced circulation oven at 200 ° C. for 30 minutes. Sintered into a film. The film-like silver was measured for thermal resistance (unit: ° C./W) at each thickness. The relationship between each thickness (unit: m) and thermal resistance was plotted on a graph, a straight line was drawn, and the slope was calculated as thermal conductivity (unit: W / mK).
[0029]
[Example 1]
Products obtained by inspecting the carbon content of a large number of spherical silver particles produced by a commercially available reduction method, that is, obtained by image analysis of a scanning electron microscope image produced by the reduction method and washed well The primary particles have an average particle size of 0.4 μm and substantially spherical silver particles (carbon content is 0.21% by weight and no silver oxide is detected on the silver surface). 20 parts of ethanol (reagent primary ethanol sold by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was stirred and mixed for 1 minute using a mortar. After standing for 1 minute, the supernatant liquid was extracted out of the system with a dropper as much as possible. Thereafter, it was further washed twice using ethanol having a purity of 99.5%, and then allowed to stand at room temperature and air-dried until no ethanol odor was found. The carbon content of the spherical silver particles was 0.11% by weight.
To this spherical silver particle powder, 1.5 parts of ion-exchanged water having an electric conductivity of 5 μs / cm was added and mixed uniformly using a spatula to prepare a pasty silver composition.
When this pasty silver composition was applied onto a glass fiber reinforced epoxy resin substrate using a metal mask, it could be applied in a good shape without sagging or flowing. When the coated glass fiber reinforced epoxy resin substrate was heated at 200 ° C. for 30 minutes in a forced circulation oven, the solid silver as the heat-sintered product had a strength comparable to silver by a refining method. About the said paste-form silver composition, the fixed strength, volume resistivity, and thermal conductivity of solid silver which is a heat-sintered product were measured, and the results are shown in Table 1. From the above results, this pasty silver composition is useful for firmly adhering an adherend with good electrical and thermal conductivity, and has excellent wear resistance, adhesion to a substrate, electrical conductivity and thermal conductivity. It can be seen that it is useful for forming a silver circuit having excellent properties.
[0030]
[Example 2]
Paste silver in the same manner as in Example 1 except that substantially spherical silver particles (carbon content is 0.21% by weight and silver oxide is not detected on the silver surface) are not washed with ethanol in Example 1. A composition was prepared.
When this pasty silver composition was applied onto a glass fiber reinforced epoxy resin substrate using a metal mask, it could be applied in a good shape without sagging or flowing. When the coated glass fiber reinforced epoxy resin substrate was heated at 200 ° C. for 30 minutes in a forced circulation oven, the solid silver as the heat-sintered product had a strength comparable to silver by a refining method. About the said paste-form silver composition, the fixed strength, volume resistivity, and thermal conductivity of solid silver which is a heat-sintered product were measured, and the results are shown in Table 1. From the above results, this pasty silver composition is useful for firmly adhering an adherend with good electrical and thermal conductivity, and has excellent wear resistance, adhesion to a substrate, electrical conductivity and thermal conductivity. It can be seen that it is useful for forming a silver circuit having excellent properties.
[0031]
[Example 3]
In Example 1, paste was used in the same manner as in Example 1 except that lower isoparaffin having a distillation range of 106 ° C. to 202 ° C. (trade name Isosol 300, manufactured by Nippon Petrochemical Co., Ltd.) was used instead of ion-exchanged water. A silver-like composition was prepared.
When this pasty silver composition was applied onto a glass fiber reinforced epoxy resin substrate using a metal mask, it could be applied in a good shape without sagging or flowing. When the coated glass fiber reinforced epoxy resin substrate was heated at 200 ° C. for 30 minutes in a forced circulation oven, the solid silver as the heat-sintered product had a strength comparable to silver by a refining method. About the said paste-form silver composition, the fixed strength, volume resistivity, and thermal conductivity of solid silver which is a heat-sintered product were measured, and the results are shown in Table 1. From the above results, this pasty silver composition is useful for firmly adhering an adherend with good electrical and thermal conductivity, and has excellent wear resistance, adhesion to a substrate, electrical conductivity and thermal conductivity. It can be seen that it is useful for forming a silver circuit having excellent properties.
[0032]
[Example 4]
In the same manner as in Example 1 except that 0.5 part of n-decyl alcohol (1-decanol) and 1.0 part of ion exchange water were used instead of 1.5 parts of ion exchange water in Example 1. A pasty composition was prepared.
When this pasty silver composition was applied onto a glass fiber reinforced epoxy resin substrate using a metal mask, it could be applied in a good shape without sagging or flowing. When the coated glass fiber reinforced epoxy resin substrate was heated at 200 ° C. for 30 minutes in a forced circulation oven, the solid silver as the heat-sintered product had a strength comparable to silver by a refining method. About the said paste-form silver composition, the fixed strength, volume resistivity, and thermal conductivity of solid silver which is a heat-sintered product were measured, and the results are shown in Table 1. From the above results, this paste-like silver composition is useful for firmly adhering adherends with good electrical and thermal conductivity, and wear resistance, adhesion to substrates, electrical conductivity and thermal conductivity. It can be seen that it is useful for forming a silver circuit having excellent properties.
[0033]
[Example 5]
The primary particles produced by a commercially available reduction method and obtained by image analysis of a scanning electron microscope image have an average particle diameter of 1.8 μm and are substantially spherical silver particles (B company product, carbon content is 0.5. 20 parts of pure water having an electric conductivity of 5 μs / cm was added to 20 parts, and the mixture was stirred and mixed for 1 minute using a mortar. After standing for 1 minute, the supernatant liquid was extracted out of the system with a dropper as much as possible. Thereafter, spherical silver particles were washed five times with pure water in the same manner. Thereafter, 20 parts of methanol having a purity of 99.8% was added and stirred and mixed in the same manner. After allowing to stand for 1 minute, the supernatant was taken out of the system with a dropper as much as possible. When it was allowed to stand at room temperature and air-dried until it did not smell of methanol, the carbon content of the spherical silver particles was 0.46% by weight.
To 20 parts of these substantially spherical silver particles, 2 parts of 1-octanol having a purity of 99% was added and mixed uniformly using a spatula to prepare a pasty silver composition.
When this pasty silver composition was applied onto a glass fiber reinforced epoxy resin substrate using a metal mask, it could be applied in a good shape without sagging or flowing. When the coated glass fiber reinforced epoxy resin substrate was heated at 200 ° C. for 30 minutes in a forced circulation oven, the solid silver as the heat-sintered product had a strength comparable to silver by a refining method. About the said paste-form silver composition, the fixed strength, volume resistivity, and thermal conductivity of solid silver which is a heat-sintered product were measured, and the results are shown in Table 1. From the above results, this pasty silver composition is useful for firmly adhering an adherend with good electrical and thermal conductivity, and has excellent wear resistance, adhesion to a substrate, electrical conductivity and thermal conductivity. It can be seen that it is useful for forming a silver circuit having excellent properties.
[0034]
[Example 6]
In Example 5, instead of the substantially spherical silver particles having a carbon content of 0.46% by weight, the substantially spherical silver particles 10 having a carbon content of 0.11% by weight prepared in Example 1 were used. Except that 20 parts of spherical silver particles having an average carbon content of 0.285% by weight obtained by mixing 10 parts of substantially spherical silver particles having a carbon content of 0.46% by weight were used. Then, a paste-like silver composition was prepared under the same conditions as in Example 5, and coating properties, sintering properties, fixing strength after heat curing, volume resistivity, and thermal conductivity were measured. The results are summarized in Table 1. Indicated. From the above results, this pasty silver composition has excellent adherence to the adherend with good electrical and thermal conductivity, and excellent wear resistance, adhesion to the substrate, electrical and thermal conductivity. It can be seen that it is useful for forming a silver circuit.
[0035]
[Comparative Example 1]
85 parts by weight of ethanol-washed substantially spherical silver particles obtained in Example 1 (carbon content is 0.21 wt%, silver oxide is not detected on the silver surface), and the viscosity is 2500 mmPa · s An attempt was made to prepare a pasty silver composition in which 14 parts of an epoxy resin (bisphenol A: bisphenol F = 1: 1) and 1 part of 2-methylimidazole were mixed and the epoxy resin was a binder. Was highly viscous and difficult to mix uniformly. The results are summarized in Table 2.
[0036]
[Comparative Example 2]
80 parts by weight of ethanol-washed substantially spherical silver particles obtained in Example 1 (carbon content is 0.21 wt%, silver oxide is not detected on the silver surface), and the viscosity is 2500 mmPa · s 19 parts of epoxy resin (bisphenol A: bisphenol F = 1: 1) and 1 part of 2-methylimidazole were uniformly mixed to prepare a pasty silver composition in which the epoxy resin is a binder.
This pasty silver composition had a very high viscosity (300 Pa · S or more), but when applied to a glass fiber reinforced epoxy resin substrate with a metal mask, it could be applied in a good shape without sagging or flowing. When heated at 200 ° C. for 30 minutes, it was an epoxy resin-like hard cured product.
The fixing strength, volume resistivity, and thermal conductivity after heat curing were measured, and the results are summarized in Table 2.
[0037]
[Comparative Example 3]
A primary particle produced by a reduction method, which is a product of Company B, obtained by image analysis of a scanning electron microscope image and having an average particle diameter of 1.8 μm and substantially spherical silver particles (carbon content is 0.88 wt. 20 parts of a mixed cleaning solution in which methanol having a purity of 99.8% and pure water having an electric conductivity of 5 μs / cm is 1: 1 in a weight ratio is 20 parts. The mixture was added and stirred and mixed for 1 minute using a mortar. After standing for 1 minute, the supernatant liquid was extracted out of the system with a dropper as much as possible. Thereafter, the mixture was further washed twice in the same manner as described above, and then allowed to stand at room temperature and air-dried until it did not smell of methanol. As a result, the carbon content of the substantially spherical silver particles was 0.61% by weight. .
To the substantially spherical silver particles, 1.5 parts of ion-exchanged water having an electric conductivity of 5 μs / cm was added and mixed uniformly using a spatula to prepare a pasty silver composition.
When this pasty silver composition was applied onto a glass fiber reinforced epoxy resin substrate with a metal mask, it could be applied in a good shape without sagging or flowing. However, even when heated at 200 ° C. for 30 minutes, the spherical silver particles did not sinter sufficiently, and although they were film-like, they were easily broken when touched with a fragile finger. The results are summarized in Table 2.
[0038]
[Comparative Example 4]
In Example 1, a substantially spherical silver particle having a carbon content of 0.11% by weight was coated on a glass fiber reinforced epoxy resin substrate without adding ion exchange water and heated at 200 ° C. for 30 minutes. The substantially spherical silver particles did not sinter and remained particulate. The results are summarized in Table 2.
[0039]
[Comparative Example 5]
In Example 5, instead of substantially spherical silver particles having a carbon content of 0.46% by weight, substantially spherical silver particles having an unwashed carbon content of 0.88% by weight were used. Prepared a pasty silver composition in the same manner as in Example 5.
When this pasty silver composition was applied onto a glass fiber reinforced epoxy resin substrate using a metal mask, it could be applied in a good shape without sagging or flowing. However, even when heated at 200 ° C. for 30 minutes, the substantially spherical silver particles did not sinter sufficiently and became a film, but they were easily broken when touched with a finger. The results are summarized in Table 2.
[0040]
[Table 1]

[0041]
[Table 2]

[0042]
Based on the above results, the paste-like silver composition of the present invention has excellent heat sinterability, is useful for firmly bonding an adherend with good electrical and thermal conductivity, and has excellent wear resistance. It can be seen that it is useful for forming a silver circuit having excellent adhesion, electrical conductivity and thermal conductivity.
[Industrial applicability]
[0043]
Of the present inventionFor bonding metal adherendsPasty silver compositionAnd metal-based adherendsBonding methods include the formation of conductive circuits on printed circuit boards, the formation of various electronic components such as resistors and capacitors and the electrodes of various display elements, the formation of conductive films for electromagnetic shielding, capacitors, resistors, diodes, memories, Useful for bonding chip components such as arithmetic elements (CPU) to substrates, forming electrodes for solar cells, forming external electrodes for chip-type ceramic electronic components such as multilayer ceramic capacitors, multilayer ceramic inductors, multilayer ceramic actuators, etc. . Of the present inventionFor bonding metal adherendsThe manufacturing method of the paste-like silver composition is:TheUseful for efficient production of pasty silver compositionThe

Claims (15)

(A) an average particle size of 0.1～6Myuemu, spherical silver particles carbon content was made by reduction method is 0.50 wt% or less, Ri (B) having a boiling point of 70 to 250 ° C. der , A paste-like material comprising a volatile dispersion medium selected from water, volatile monohydric alcohol, volatile aliphatic hydrocarbon, volatile ketone, volatile lower aliphatic carboxylic acid ester and volatile silicone oil, When heated at 100 ° C. or more and 250 ° C. or less, the volatile dispersion medium is volatilized, the spherical silver particles are sintered together, and the volume resistivity is 1 × 10 ⁻⁴ Ω · cm or less, and the thermal conductivity There characterized by comprising a solid silver is 5W / m · K or more, the bonding paste like silver composition adherend each other metallic. And a volume resistivity of less than 1 × 10 ^-5 Ω · cm, and wherein the thermal conductivity becomes solid silver is 10 W / m · K or more, the metal-based of claim 1, wherein A paste-like silver composition for bonding between bonded bodies. The paste-like silver composition for joining metal-based adherends according to claim 1, wherein the carbon content is 0.25% by weight or less. Volatile monohydric alcohol is ethyl alcohol, propyl alcohol, butyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol or benzyl alcohol, and volatile aliphatic hydrocarbon is lower n-paraffin or It characterized in that it is a lower isoparaffins, claim 1 or claim 2 for bonding paste silver composition adherends each other metallic described. 3. The volatile dispersion medium is a mixture of water and butyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol or benzyl alcohol. bonding paste silver composition adherends each other metallic described. Washing the spherical silver particles made of an average particle diameter of 0.1~6μm reduction method, the carbon content was 0.50 wt% or less, Ri (B) having a boiling point of 70 to 250 ° C. der , water, volatile monohydric alcohols, volatile aliphatic hydrocarbons, volatile ketones, comprising mixing a volatile dispersion medium is selected from volatile lower aliphatic carboxylic acid esters and volatile silicone oils, When heated at 100 ° C. or more and 250 ° C. or less, the volatile dispersion medium is volatilized, the spherical silver particles are sintered together, and the volume resistivity is 1 × 10 ⁻⁴ Ω · cm or less, and the thermal conductivity method of manufacturing but bonding paste silver composition adherends each other metallic become solid silver is 5W / m · K or more. And a volume resistivity of less than 1 × 10 ^-5 Ω · cm, and thermal conductivity becomes solid silver is 10 W / m · K or more, the bonding adherends each other metallic claim 6, wherein For producing a paste-like silver composition. The carbon content of the spherical silver particles, characterized in that 0.25 wt% or less, the production method of the joining paste like silver composition adherend between metal system according to claim 6. Detergent water, characterized in that it is a volatile hydrophilic solvent or aliphatic hydrocarbon solvents, the production method of the joining paste like silver composition adherend between metal system according to claim 6, wherein. (A) an average particle size of 0.1～6Myuemu, spherical silver particles carbon content was made by reduction method is 0.50 wt% or less, Ri (B) having a boiling point of 70 to 250 ° C. der , A paste-like material comprising a volatile dispersion medium selected from water, volatile monohydric alcohol, volatile aliphatic hydrocarbon, volatile ketone, volatile lower aliphatic carboxylic acid ester and volatile silicone oil, When heated at 100 ° C. or more and 250 ° C. or less, the volatile dispersion medium is volatilized, the spherical silver particles are sintered together, and the volume resistivity is 1 × 10 ⁻⁴ Ω · cm or less, and the thermal conductivity The volatile dispersion medium is obtained by interposing a paste-like silver composition that becomes solid silver having a W of 5 W / m · K or more between a plurality of metal-based adherends and heating at 100 ° C. or more and 250 ° C. or less. It volatilizes and the spherical silver particles sinter to bond multiple metal adherends together. Wherein the method of bonding adherends each other metallic. The paste-like silver composition is a paste-like silver composition that becomes solid silver having a volume resistivity of 1 × 10 ⁻⁵ Ω · cm or less and a thermal conductivity of 10 W / m · K or more. wherein the method of bonding adherends to each other of the metal system of claim 10, wherein. Wherein the carbon content of spherical silver particles is 0.25 wt% or less, the joining method of the adherend between metal system of claim 10, wherein. Volatile monohydric alcohol is ethyl alcohol, propyl alcohol, butyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol or benzyl alcohol, and volatile aliphatic hydrocarbon is lower n-paraffin or characterized in that it is a lower isoparaffins, claim 10 or claim 11 method of bonding adherends each other metallic described. 12. The volatile dispersion medium is a mixture of water and butyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol or benzyl alcohol. method of bonding adherends to each other in the metal-based. Wherein the adherend metal system is an electronic component having a metal member, according to claim 10 or claim 11 method of bonding adherends each other metallic described.

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