JP6900148B2 - Silver paste and semiconductor devices using it - Google Patents

Description

The present invention relates to a silver paste and a semiconductor device using the silver paste. More specifically, silver paste used for adhering semiconductor elements such as power semiconductors, LSIs, and light emitting diodes (LEDs) to support members such as lead frames, ceramic wiring boards, glass epoxy wiring boards, and polyimide wiring boards, and silver pastes thereof. The present invention relates to a semiconductor device using.

When manufacturing a semiconductor device, as a method of adhering a semiconductor element and a support member to each other, a binder resin such as an epoxy resin or a polyimide resin, a filler such as silver powder, a solvent composition, or the like is mixed to form a paste. There is a way to use as an adhesive. In recent years, the power density (W · cm ^-3 ) has increased with the high integration of semiconductor packages, and in order to ensure the operational stability of semiconductor elements, the adhesive is required to have high heat dissipation. Further, since the operating environment temperature of the semiconductor element is high, the adhesive is also required to have heat resistance. Further, an adhesive containing no Pb is required in order to reduce the environmental load. From the above background, a sintered type silver paste that does not contain a binder resin component has been studied.

As a method of using the silver paste, for example, a dispenser, a printing machine, a stamping machine or the like is used to apply the silver paste to the die pad of the support member, then the semiconductor element is die-bonded and bonded by heat sintering to the semiconductor device. There is a way to do it. The characteristics required for the silver paste are roughly classified into the contents related to the construction method at the time of bonding and the contents related to the physical properties of the silver sintered body after bonding.

As for the contents related to the construction method at the time of bonding, in order to prevent damage to the semiconductor member, it is required that the semiconductor member can be bonded at a low temperature (for example, about 300 ° C.) and with low pressure (for example, about 0.1 MPa) or no pressure. Further, from the viewpoint of improving throughput, it is required to shorten the time required for adhesion. On the other hand, as the content related to the physical properties of the silver sintered body after adhesion, high adhesiveness (high die shear strength) is required in order to secure adhesion with the semiconductor member. Further, high heat dissipation characteristics (high thermal conductivity) of the silver sintered body are also required. Further, in order to ensure the connection reliability for a long period of time, the heat resistance and high density of the silver sintered body (there are few pores in the silver sintered body) are required.

As a silver paste of the prior art, for example, a silver paste in which silver particles and a solvent as disclosed in Patent Documents 1 to 4 are mixed has been proposed.

Japanese Patent No. 4353380 Japanese Unexamined Patent Publication No. 2012-84414 Japanese Patent No. 4414145 Japanese Unexamined Patent Publication No. 2012-119132

The problem with the silver paste of the prior art is that it is not always possible to satisfy all of the adhesive strength, conductivity and thermal conductivity.

In view of these problems, the present invention is well-balanced in all of adhesive strength, conductivity and thermal conductivity even when sintered at low temperature and low pressure (or no pressure). An object of the present invention is to provide a silver paste and a semiconductor device using the silver paste.

The present invention comprises plate-shaped silver particles having a centerline average surface roughness Ra of 1 nm or less, and silver particles having a centerline average surface roughness Ra of 2 nm to 20 nm and a particle diameter of 1 μm to 20 μm. Provided is a silver paste containing a solvent.

It is desirable that the center line average surface roughness Ra of the plate-shaped silver particles is 0.5 nm or less.

It is desirable that the plate-shaped silver particles are single crystals.

It is desirable that the ratio of the maximum length a in the thickness direction and the maximum length b in the plane direction of the plate-shaped silver particles satisfies 2 ≦ b / a.

It is desirable that the maximum length a in the thickness direction and the maximum length b in the plane direction of the plate-shaped silver particles satisfy a ≦ 500 nm and 100 nm ≦ b ≦ 10000 nm, respectively.

It is desirable that the content of silver particles having a particle size of 1 μm to 20 μm is 80% by mass or less based on the total amount of silver particles.

It is desirable that the silver paste further contains spherical silver particles having a particle size of 0.01 μm or more and less than 1 μm.

The silver paste is Mg, Al, Si, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd. , Cd, In, Sn, Sb, Ta, W, Re, Os, Ir, Pt, Au, and Bi. It is desirable to contain 01 to 5.0% by mass.

The present invention also provides a semiconductor device having a structure in which a semiconductor element and a support member for mounting a semiconductor element are adhered to each other via a sintered body obtained by sintering the silver paste.

According to the present invention, a silver paste having an excellent balance in all of adhesive strength, conductivity and thermal conductivity even when sintered at low temperature and low pressure (or no pressure) was used. A semiconductor device can be provided.

It is an SEM photograph of silver particle LM1. It is an SEM photograph of silver particle AgC239. It is an SEM photograph of silver particle AgC212D. It is an SEM photograph of silver particles TC-20E-L. It is an SEM photograph of the connection cross section of the semiconductor member of Example 1. It is an SEM photograph of the connection cross section of the semiconductor member of Example 2. It is an SEM photograph of the connection cross section of the semiconductor member of Example 3. It is an SEM photograph of the connection cross section of the semiconductor member of Comparative Example 1. It is an SEM photograph of the connection cross section of the semiconductor member of Comparative Example 2. It is an SEM photograph of the connection cross section of the semiconductor member of Comparative Example 3. It is an SEM photograph of the connection cross section of the semiconductor member of Comparative Example 4. It is a schematic cross-sectional view which shows one Embodiment of the semiconductor device which concerns on this invention. It is a schematic cross-sectional view which shows the other embodiment of the semiconductor device which concerns on this invention.

Hereinafter, preferred embodiments of the present invention will be described in detail.

The silver paste according to the present embodiment has plate-shaped silver particles having a center line average surface roughness Ra of 1 nm or less (hereinafter, also referred to as “silver particles A”) and a center line average surface roughness Ra of 2 nm or more. It contains silver particles having a particle size of 20 μm and a particle size of 1 μm to 20 μm (hereinafter, also referred to as “silver particles B”) and a paste.

The silver particles A used in the present embodiment are plate-shaped silver particles having a centerline average surface roughness Ra of 1 nm or less. The Ra of the silver particles A is preferably 0.5 nm or less, more preferably 0.1 nm or less. The term "plate-like" in the present specification means a shape in which the aspect ratio (particle diameter / thickness) of silver particles is in the range of 2 to 1000.

The "center line average surface roughness" in the present specification is also referred to as "arithmetic mean roughness" and means "arithmetic mean roughness" defined in JIS B0601: 2001. As a method for measuring the center line average surface roughness Ra of silver particles, a method using a BET method, a brain method, an atomic force microscope (AFM), which is a method obtained from the specific surface area, and a laser microscope are used. A known method such as the method to be used may be used.

The particle size of the silver particles A is not particularly limited, but is preferably 1 to 20 μm, more preferably 1 to 10 μm, and even more preferably 1 to 5 μm. The particle size of the silver particles is, for example, the square root of the area of the silver particles when the silver particles are viewed in a plan view using SEM.

The ratio of the maximum length a in the thickness direction to the maximum length b in the plane direction of the silver particles A preferably satisfies 2 ≦ b / a, more preferably 5 ≦ b / a, and 10 ≦ b. It is more desirable to satisfy / a. When b / a satisfies the above conditions, the adhesive area between the silver paste and the adherend surface can be secured, and the adhesive strength can be further improved. Further, it is desirable that a and b satisfy a ≦ 500 nm and 100 nm ≦ b ≦ 10000 nm, respectively, and it is more desirable that a ≦ 300 nm and 300 nm ≦ b ≦ 6000 nm are satisfied, and a ≦ 100 nm and 500 nm ≦ b ≦ 3000 nm. It is even more desirable to meet. If b satisfies the above conditions, it can also be suitably used when forming a thin silver sintered body. Further, although it depends on the value of b, it is desirable that a satisfies the above conditions in order to secure a sufficient aspect ratio. In addition, a can be set, for example, a ≧ 10 nm.

It is desirable that the silver particles A are single crystals. As a method for producing silver particles A which are single crystals, for example, JP-A-2012-167378, Benjamin Wiley et al., NANO LETTERS, Vol. 4, No. The known methods described in 9,1733-1739, 2004, Ryusuke Ueyama et al., Journal of the Ceramic Society of Japan, 107, [1], 60-65, 1999 may be used.

The content of the silver particles A is preferably 20% by mass or more, more preferably 50% by mass or more, and further preferably 70% by mass or more based on the total amount of silver particles. The content of the silver particles A is preferably 99% by mass or less, more preferably 95% by mass or less, and further preferably 90% by mass or less.

The silver paste according to the present embodiment contains, in addition to the silver particles A, silver particles B having a centerline average surface roughness Ra of 2 nm to 20 nm and a particle size of 1 μm to 20 μm. By containing the silver particles A and the silver particles B, the filling property between the silver particles can be enhanced, and the adhesive strength, conductivity and thermal conductivity of the formed silver sintered body can be improved.

As the silver particles B, plate-shaped silver particles can be used. The center line average surface roughness Ra of the silver particles B is 2 nm to 20 nm, preferably 2 nm to 15 nm, and more preferably 2 nm to 10 nm. The particle size of the silver particles B is 1 to 20 μm, preferably 1 to 15 μm, and more preferably 1 to 10 μm.

The content of the silver particles B is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 20% by mass or more based on the total amount of silver particles. On the other hand, the content of the silver particles B is preferably 80% by mass or less, more preferably 75% by mass or less, and further preferably 70% by mass or less based on the total amount of silver particles. When the content of the silver particles B is within the above range, the conductivity and the thermal conductivity can be further improved.

The silver paste according to the present embodiment may further contain silver particles other than silver particles A and silver particles B, and for example, further contains spherical silver particles having a particle size of 0.01 μm or more and less than 1 μm. You may be. By containing spherical silver particles having a particle size of 0.01 μm or more and less than 1 μm, it is possible to further improve the packing property of the silver particles and improve the density of the formed silver sintered body, and as a result. , The physical characteristics of the silver sintered body can be brought close to that of bulk silver.

The surface of silver particles is usually coated with an organic substance. Hereinafter, this organic substance will be referred to as a protective agent. The desorption temperature of the protective agent in the silver particles used in the present embodiment is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, and even more preferably 230 ° C. or lower.

In order to obtain a dense silver sintered body by sintering the silver particles used in the present embodiment almost at the same time, it is desirable that the desorption temperatures of the protective agents of the silver particles are close to each other. Specifically, the difference in the desorption temperature of the protective agent for each silver particle is preferably within 50 ° C, and preferably within 30 ° C.

The desorption temperature of the protective agent for silver particles can be determined by performing differential thermal-thermogravimetric simultaneous measurement (Thermogravimetric-Differential Thermal Analysis; TG-DTA) in the atmosphere.

The amount of the protective agent in the silver particles is preferably such that the mass of the protective agent: the mass of the silver particles is 0.1: 99.9 to 20:80. When the amount of the protective agent is not more than the above lower limit value, it becomes easy to sufficiently coat the silver particles. As a result, it is possible to suppress the aggregation of the silver particles and the deterioration of the dispersibility of the silver particles in the solvent. On the other hand, when the amount of the protective agent is not more than the above upper limit value, the degree of volume shrinkage when the silver particles are sintered can be suppressed. As a result, the density of the silver sintered body can be ensured.

As the type of protective agent for silver particles, a carboxylic acid compound can be particularly preferably used, and more preferably, an aliphatic monocarboxylic acid having 2 to 20 carbon atoms.

The amount of silver particles in the silver paste can be appropriately determined according to the viscosity and thixotropic property of the target silver paste. In order to further improve the adhesive strength and thermal conductivity of the silver sintered body, it is desirable that the silver particles are 80% by mass or more based on the total amount of silver paste.

The silver paste according to the present embodiment contains, as metal elements or metalloid elements other than silver, Mg, Al, Si, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Contains at least one element selected from Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Cd, In, Sn, Sb, Ta, W, Re, Os, Ir, Pt, Au and Bi. May be.

These elements improve the adhesive strength between the silver paste and a specific adherend metal, achieve adhesion at low temperature by adding a low melting point element, improve the mechanical properties of the silver sintered body, and sulfide resistance of the silver sintered body. The type is appropriately selected and added according to the purpose such as imparting sex.

The content of these elements is preferably 0.01 to 5.0% by mass based on the total amount of silver paste. When it is 0.01% by mass or more, the desired effect can be easily obtained. Further, when it is 5.0% by mass or less, it is possible to suppress inhibition of sintering of the silver paste and deterioration of characteristics such as adhesive strength, thermal conductivity and electrical conductivity of the silver sintered body.

These elements are preferably contained in the form of particles in order to be mixed with silver particles to form a silver paste, and the particle size is preferably 0.01 to 10 μm.

Further, the surface of the base metal element and the metalloid element is usually oxidized, and even if they are added to the silver paste as they are, a sufficient effect may not be obtained. Therefore, it is desirable to add flux together with these elements. A known type of flux can be used, and the amount of flux may be appropriately selected. Further, as a more effective method, there is a method of using particles whose surface is silver-plated as particles containing the above elements. The use of silver-plated particles improves the oxidation resistance of the silver paste during storage and sintering. As the silver-plated particles, commercially available particles may be used, or particles produced by a known method may be used.

The solvent in this embodiment is not particularly limited, and a known solvent can be used. The solvent can be selected from alcohols, aldehydes, carboxylic acids, ethers, esters, amines, monosaccharides, polysaccharides, linear hydrocarbons, fatty acids, aromatics and the like. , It is also possible to use a combination of a plurality of solvents. It is desirable to select a solvent suitable for dispersing silver particles from the above. Specifically, a solvent having an alcohol structure, an ether structure or an ester structure is used to determine the thermal conductivity of the silver sintered body after sintering. It is particularly desirable because the conductivity and adhesive strength can be further improved.

The boiling point of the solvent is not particularly limited, but is preferably 100 ° C. to 350 ° C. It is desirable that the solvent is a solvent that evaporates and does not remain in the silver sintered body in the temperature range in which the semiconductor element is connected to the support member. When the boiling point of the solvent is 100 ° C. or higher, it is possible to suppress the evaporation of the solvent even at room temperature when the silver paste is used, and as a result, the viscosity stability and coatability of the silver paste can be ensured. Further, when the boiling point of the solvent is 350 ° C. or lower, the solvent is easily evaporated at the temperature at which the semiconductor element is connected, and it is possible to prevent the solvent from remaining in the silver sintered body and deteriorating the characteristics of the silver sintered body.

Moreover, you may add an organic component other than a solvent as an additive. Examples of the type of additive include an anti-sedimentation agent for silver particles in the paste, a flux agent for promoting sintering of silver particles, and the like. As with the solvent, it is desirable that the additive is desorbed from the system at the temperature at which the silver paste is sintered.

The amount of solvent in the silver paste is preferably less than 20% by mass based on the total amount of silver paste. When the amount of the solvent is less than 20% by mass, the volume shrinkage due to evaporation of the solvent when the silver paste is sintered can be suppressed, and the denseness of the formed silver sintered body can be ensured.

In order to produce the silver paste according to the present embodiment, silver particles and a solvent are collectively or divided together with various additives added as necessary, and a stirrer, a raider, three rolls, and a planetary mixer. The above-mentioned dispersion / dissolution devices may be appropriately combined, and if necessary, heated to mix, dissolve, pulverize and knead, or disperse to form a uniform paste.

As a method for heating and sintering the silver paste according to the present embodiment, a known method can be used. In addition to external heating by a heater, an ultraviolet lamp, a laser, a microwave, or the like can be preferably used. It is desirable that the heating temperature of the silver paste is equal to or higher than the temperature at which organic components such as solvents and additives in the silver paste are desorbed from the system. Specifically, the heating temperature range is preferably 150 ° C. or higher and 300 ° C. or lower, and more preferably 150 ° C. or higher and 250 ° C. or lower. When connecting a general semiconductor member by setting the heating temperature to 300 ° C or lower, damage to the member can be avoided, and by setting the heating temperature to 150 ° C or higher, the protective agent can be desorbed. Is more likely to occur.

The heating time of the silver paste may be the time during which the desorption of organic substances such as protective agents and solvents is completed at the set temperature. The range of suitable heating temperature and heating time can be estimated by performing TG-DTA measurement of silver paste.

In addition, the process for heating the silver paste can be appropriately determined. In particular, when sintering is performed at a temperature exceeding the boiling point of the solvent, preheating is performed at a temperature below the boiling point of the solvent, the solvent is volatilized to some extent in advance, and then sintering is performed. Easy to get. The rate of temperature rise when heating the silver paste is not particularly limited when sintering is performed at a temperature lower than the boiling point of the solvent. When sintering at a temperature exceeding the boiling point of the solvent, it is desirable to set the temperature rise rate to 1 ° C./sec or less or perform a preheating step.

The silver sintered body obtained by sintering the silver paste as described above has ^{a volume resistivity of 1 × 10-5} Ω · cm or less, a thermal conductivity of 30 W / m · K or more, and a thermal conductivity of 65% or more. It is desirable to have a high density. The density of the silver sintered body is calculated based on the following formula.
Dense density [%] = Silver sintered body density [g / cm ³ ] x 100 / Theoretical density of silver [10.49 g / cm ³ ]

Further, the adhesive strength of the silver sintered body obtained by sintering the silver paste as described above is preferably 10 MPa or more, and more preferably 15 MPa or more.

In the semiconductor device according to the present embodiment, the semiconductor element and the support member for mounting the semiconductor element are adhered to each other via a sintered body obtained by sintering the silver paste according to the present embodiment.

FIG. 12 is a schematic cross-sectional view showing an example of the semiconductor device according to the present embodiment. As shown in FIG. 12, the semiconductor device 10 includes a lead frame 2a, a lead frame (heat radiator) 2b, 2c, and a silver paste sintered body 3 according to the present embodiment, as a support member for mounting a semiconductor element. A semiconductor element 1 connected to a lead frame 2a via a lead frame 2a and a mold resin 5 for molding the semiconductor elements 1 are provided. The semiconductor element 1 is connected to the lead frames 2b and 2c via two wires 4, respectively.

FIG. 13 is a schematic cross-sectional view showing another example of the semiconductor device according to the present embodiment. As shown in FIG. 13, the semiconductor device 20 includes a substrate 6, a lead frame 7 which is a support member for mounting a semiconductor element formed so as to surround the substrate 6, and a silver paste sintered body 3 according to the present embodiment. It includes an LED chip 8 which is a semiconductor element connected on a lead frame 7 via a light-transmitting resin 9 and a translucent resin 9 for sealing the LED chip 8. The LED chip 8 is connected to the lead frame 7 via a wire 4.

In these semiconductor devices, for example, a silver paste is applied on a support member for mounting a semiconductor element by a dispensing method, a screen printing method, a stamping method, or the like, and the semiconductor element is mounted on a portion to which the silver paste is applied to mount a heating device. By using and sintering the silver paste, the semiconductor element and the support member for mounting the semiconductor element can be adhered to each other. Further, a semiconductor device can be obtained by performing a wire bonding step and a sealing step after sintering the silver paste.

Examples of the support member for mounting the semiconductor element include a lead frame such as a 42 alloy lead frame, a copper lead frame, and a palladium PPF lead frame, a glass epoxy substrate (a substrate made of a glass fiber reinforced epoxy resin), and a BT substrate (cyanate monomer and its). Examples thereof include an organic substrate (a substrate using a BT resin composed of an oligomer and a bismaleimide).

Examples will be shown below, and the present invention will be described in more detail. The present invention is not limited by these examples.

The measurement of each characteristic in each Example and Comparative Example was carried out as follows.

(1) Morphological observation of silver particles A carbon double-sided tape was attached on a sample grid, and silver powder was placed on the carbon tape to prepare an observation sample. Observation was performed with an electron acceleration voltage of 10 kV using a desktop scanning electron microscope (JEOL Ltd., NeoScop JCM-5000), and SEM photographs were taken.

(2) Centerline average surface roughness of silver particles Using AFM (SI Nanotechnology, SPI4000), the surface roughness of silver particles was measured in dynamic force mode (DFM). Specifically, about 10 mg of silver particles were added to 10 mL of acetone to prepare a dispersion. About 100 μL of the dispersion was dropped onto a circular sample grid having a diameter of 2 cm, and the mixture was dried at 25 ° C. for about 24 hours to obtain a measurement sample. The sample grid was set in AFM (SI Nanotechnology, SPI4000) and measured by DFM. A visual field range containing a plurality of silver particles was used as a scanning target, and a surface shape image of the silver particles was obtained. This operation was repeated to obtain surface shape images of 10 to 20 silver particles. Surface roughness analysis was performed on the surface shape image of each of the obtained silver particles with respect to a length of about 90% of the maximum particle diameter. The average value of the obtained surface roughness was calculated, and the average value was taken as the center line average surface roughness of the silver particles.

(3) Density and Denseness of Silver Sintered Silver paste is preheated on a hot plate (Inuchi Seieidou, SHAMAL HOTPLATE HHP-401) at 110 ° C. for 10 minutes, and further heated at 200 ° C. for 1 hour to perform silver sintering. A body (about 10 mm × 10 mm × 1 mm) was obtained. The produced silver sintered body was polished with sandpaper (No. 800), and the volume and mass of the polished silver sintered body were measured. The density of the silver sintered body was calculated from these values, and the density was further calculated according to the following formula.
Dense density [%] = Silver sintered body density [g / cm ³ ] x 100 / Theoretical density of silver [10.49 g / cm ³ ]

(4) Die shear strength 0.1 mg of silver paste is applied on an Ag-plated Cu lead frame (land part: 10 x 5 mm), and a 1 mm x 1 mm Ag-plated Si chip (Ag plating thickness: 0.1 μm, chip) is coated on the silver paste. Thickness: 400 μm) or Au-plated Si chip (Au plating thickness: 0.1 μm, chip thickness: 400 μm) was adhered. This was heated on a hot plate (Inuchi Seieidou, SHAMAL HOTPLATE HHP-401) at 200 ° C. for 1 hour. The adhesive strength of the obtained silver sintered body was evaluated by the die shear strength [MPa]. Using a universal bond tester (4000 series manufactured by Daige Co., Ltd.), the Si chip was pushed horizontally at a measurement speed of 500 μm / s and a measurement height of 100 μm to measure the die shear strength [MPa] of the silver sintered body. The evaluation results will be described using A, B, and C according to the following criteria.
(Substrate: In the case of Ag-plated Si chip)
A: 20 MPa or more and B: 10 MPa or more and less than 20 MPa C: 0 MPa or more and less than 10 MPa (attached body: in the case of Au-plated Si chip)
A: 10 MPa or more and B: 5 MPa or more and less than 10 MPa C: 0 MPa or more and less than 5 MPa

(5) Thermal conductivity The silver paste is preheated on a hot plate (Inuchi Seieidou, SHAMAL HOTPLATE HHP-401) at 110 ° C. for 10 minutes, and further heated at 200 ° C. for 1 hour to obtain a silver sintered body (about 10 mm × 10 mm). × 1 mm) was obtained. The thermal diffusivity of this silver sintered body was measured by a laser flash method (Netch, LFA 447, measurement temperature 25 ° C.), and further obtained by this thermal diffusivity and a differential scanning calorimetry device (Perkin Elmer, Pyris 1). The thermal conductivity [W / m · K] of the silver sintered body at 25 ° C. was calculated from the product of the specific heat capacity and the sintering density. The evaluation results will be described using A, B, and C according to the following criteria.
A: 100 W / m ・ K or more B: 80 W / m ・ K or more and less than 100 W / m ・ K C: 0 W / m ・ K or more and less than 80 W / m ・ K

(6) Volume resistivity A silver paste is applied onto a glass plate, preheated on a hot plate (Inuchi Seieidou, SHAMAL HOTPLATE HHP-401) at 110 ° C. for 10 minutes, and further heated at 200 ° C. for 1 hour to obtain glass. A silver sintered body having a size of 1 × 50 × 0.03 mm was obtained on a plate. The volume resistivity [μΩ · cm] of this silver sintered body was measured by a 4-terminal method (Advantest Co., Ltd., R687E DIGTAL MULTIMETER). The evaluation results will be described using A, B, and C according to the following criteria.
A: 0 μΩ ・ cm or more and less than 5.5 μΩ ・ cm B: 5.5 μΩ ・ cm or more and less than 6.5 μΩ ・ cm C: 6.5 μΩ ・ cm or more

(7) Observation of cross section of silver sintered body 0.1 mg of silver paste was applied on an Ag-plated Cu lead frame (land portion: 10 × 5 mm, Ag plating thickness: about 4 μm), and 1 mm × 1 mm Au was applied thereto. A plated Si chip (Au plating thickness: 0.1 μm, chip thickness: 400 μm) was adhered. This was heated at 200 ° C. for 1 hour using a hot plate (Inuchi Seieidou, SHAMAL HOTPLATE HHP-401). The connected sample was embedded in an epoxy resin and polished until the cross section of the Au-plated Si chip / silver sintered body / Ag-plated Cu lead frame could be confirmed. Platinum is vapor-deposited on the polished sample with an ion sputtering device (Hitachi High-Technologies Corporation, E1045), and this is subjected to an electron acceleration voltage of 10 kV and a magnification of 5000 times by a desktop scanning electron microscope (JEOL Ltd., NeoScope JCM-5000). The SEM photograph was taken.

In Examples 1 to 22 and Comparative Examples 1 to 4, silver pastes were prepared as follows. The silver particles used in each Example and Comparative Example (LM1 (Tokusen Kogyo Co., Ltd.), AgC239 (Fukuda Metal Foil Co., Ltd.), AgC212D (Fukuda Metal Foil Co., Ltd.), TC-20EL (Tokuriki Chemical Co., Ltd.) Table 1 shows the properties of AgS050 (Tokuriki Kagaku Kenkyusho Co., Ltd.) and C-34 (Tokuriki Kagaku Kenkyusho Co., Ltd.). In addition, SEM photographs of LM1, AgC239, AgC212D, and TC-20E-L are shown in FIGS. 1, 2, 3, and 4, respectively. Table 2 shows the types and blending amounts of silver particles and other particles (particles other than silver) in Examples 1 to 22 and Comparative Examples 1 to 4.

(Example 1)
75 parts by mass of LM1 (Tokusen Kogyo Co., Ltd.) and 25 parts by mass of AgC239 (Fukuda Metal Leaf Co., Ltd.) as silver particles, 13.6 parts by mass of terpineol (Wako Pure Chemical Industries, Ltd., isomer mixture) as a solvent, and stearer as an additive. 1 part by mass of acid (Shin Nihon Rika Co., Ltd.) was used. The silver particles, solvent, and additives were kneaded with a rake for 15 minutes to prepare a silver paste. The characteristics of this silver paste are shown in Table 3. Further, FIG. 5 shows an SEM photograph of a cross section of the connection portion between the Au-plated Si chip and the silver sintered body in the Au-plated Si chip / silver sintered body / Ag-plated Cu lead frame produced according to (7) above. ..

(Example 2)
A silver paste was prepared in the same procedure as in Example 1 except that LM1 and AgC239 were mixed and used as silver particles at the ratios shown in Table 2. The characteristics of this silver paste are shown in Table 3. Further, FIG. 6 shows an SEM photograph of a cross section of the connection portion between the Au-plated Si chip and the silver sintered body in the Au-plated Si chip / silver sintered body / Ag-plated Cu lead frame produced according to (7) above. ..

(Example 3)
A silver paste was prepared in the same procedure as in Example 1 except that LM1 and AgC239 were mixed and used as silver particles at the ratios shown in Table 2. The characteristics of this silver paste are shown in Table 3. Further, FIG. 7 shows an SEM photograph of a cross section of the connection portion between the Au-plated Si chip and the silver sintered body in the Au-plated Si chip / silver sintered body / Ag-plated Cu lead frame produced according to (7) above. ..

(Example 4)
A silver paste was prepared in the same procedure as in Example 1 except that 1 part by mass of Al particles (Alfa Aeser) was further added. The characteristics of this silver paste are shown in Table 3.

(Example 5)
A silver paste was prepared in the same procedure as in Example 1 except that 1 part by mass of Si particles (High Purity Chemical Laboratory Co., Ltd.) was used. The characteristics of this silver paste are shown in Table 3.

(Example 6)
A silver paste was prepared in the same procedure as in Example 1 except for 1 part by mass of Ti particles (Wako Pure Chemical Industries, Ltd.). The characteristics of this silver paste are shown in Table 3.

(Example 7)
A silver paste was prepared in the same procedure as in Example 1 except that 1 part by mass of V particles (Wako Pure Chemical Industries, Ltd.) was further added. The characteristics of this silver paste are shown in Table 3.

(Example 8)
A silver paste was prepared in the same procedure as in Example 1 except that 1 part by mass of Mn particles (Wako Pure Chemical Industries, Ltd.) was further added. The characteristics of this silver paste are shown in Table 3.

(Example 9)
A silver paste was prepared in the same procedure as in Example 1 except that 1 part by mass of Fe particles (Wako Pure Chemical Industries, Ltd.) was further added. The characteristics of this silver paste are shown in Table 3.

(Example 10)
A silver paste was prepared in the same procedure as in Example 1 except that 1 part by mass of Co particles (Wako Pure Chemical Industries, Ltd.) was further added. The characteristics of this silver paste are shown in Table 3.

(Example 11)
A silver paste was prepared in the same procedure as in Example 1 except that 1 part by mass of Ni particles (METAL FOIL & POWDERS MFG CO., Ni-HWQ) was further added. The characteristics of this silver paste are shown in Table 3.

(Example 12)
A silver paste was prepared in the same procedure as in Example 1 except that 1 part by mass of Zn particles (Alfa Aeser) was further added. The characteristics of this silver paste are shown in Table 3.

(Example 13)
A silver paste was prepared in the same procedure as in Example 1 except that 1 part by mass of Pd particles (Alfa Aeser) was further added. The characteristics of this silver paste are shown in Table 3.

(Example 14)
A silver paste was prepared in the same procedure as in Example 1 except that 1 part by mass of In particles (Wako Pure Chemical Industries, Ltd.) was further added. The characteristics of this silver paste are shown in Table 3.

(Example 15)
A silver paste was prepared in the same procedure as in Example 1 except that 1 part by mass of Sn particles (Wako Pure Chemical Industries, Ltd.) was further added. The characteristics of this silver paste are shown in Table 3.

(Example 16)
A silver paste was prepared in the same procedure as in Example 1 except that 1 part by mass of Sb particles (Wako Pure Chemical Industries, Ltd.) was further added. The characteristics of this silver paste are shown in Table 3.

(Example 17)
A silver paste was prepared in the same procedure as in Example 1 except that 1 part by mass of Ag-plated Cu particles (Fukuda Metal Leaf Co., Ltd.) was further added. The characteristics of this silver paste are shown in Table 3.

(Example 18)
A silver paste was prepared in the same procedure as in Example 1 except that LM1 and AgC212D were mixed and used as silver particles at the ratios shown in Table 2. The characteristics of this silver paste are shown in Table 3.

(Example 19)
A silver paste was prepared in the same procedure as in Example 1 except that LM1 and AgC212D were mixed and used as silver particles at the ratios shown in Table 2. The characteristics of this silver paste are shown in Table 3.

(Example 20)
A silver paste was prepared in the same procedure as in Example 1 except that LM1 and AgC212D were mixed and used as silver particles at the ratios shown in Table 2. The characteristics of this silver paste are shown in Table 3.

(Example 21)
A silver paste was prepared in the same procedure as in Example 1 except that LM1, AgC239, and AgS050 were mixed and used as silver particles at the ratios shown in Table 2. The characteristics of this silver paste are shown in Table 3.

(Example 22)
A silver paste was prepared in the same procedure as in Example 1 except that LM1, AgC239 and C-34 were mixed and used as silver particles at the ratios shown in Table 2. The characteristics of this silver paste are shown in Table 3.

(Comparative Example 1)
A silver paste was prepared in the same procedure as in Example 1 except that 100 parts by mass of AgC239 was used as the silver particles. The characteristics of this silver paste are shown in Table 3. Further, FIG. 8 shows an SEM photograph of a cross section of the connection portion between the Au-plated Si chip and the silver sintered body in the Au-plated Si chip / silver sintered body / Ag-plated Cu lead frame produced according to (7) above. ..

(Comparative Example 2)
A silver paste was prepared in the same procedure as in Example 1 except that 100 parts by mass of AgC212D (Fukuda Metal Leaf Co., Ltd.) was used as the silver particles. The characteristics of this silver paste are shown in Table 3. Further, FIG. 9 shows an SEM photograph of a cross section of the connection portion between the Au-plated Si chip and the silver sintered body in the Au-plated Si chip / silver sintered body / Ag-plated Cu lead frame produced according to (7) above. ..

(Comparative Example 3)
A silver paste was prepared in the same procedure as in Example 1 except that 100 parts by mass of TC-20EL (Tokuriki Chemical Laboratory Co., Ltd.) was used as the silver particles. The characteristics of this silver paste are shown in Table 3. Further, FIG. 10 shows an SEM photograph of a cross section of the connection portion between the Au-plated Si chip and the silver sintered body in the Au-plated Si chip / silver sintered body / Ag-plated Cu lead frame produced according to (7) above. ..

(Comparative Example 4)
A silver paste was prepared in the same procedure as in Example 1 except that 100 parts by mass of LM1 was used as the silver particles. The characteristics of this silver paste are shown in Table 3. Further, FIG. 11 shows an SEM photograph of a cross section of the connection portion between the Au-plated Si chip and the silver sintered body in the Au-plated Si chip / silver sintered body / Ag-plated Cu lead frame produced according to (7) above. ..

1 ... Semiconductor element, 2a, 2b, 2c ... Lead frame, 3 ... Silver paste sintered body, 4 ... Wire, 5 ... Mold resin, 6 ... Substrate, 7 ... Lead frame, 8 ... LED chip, 9 ... Translucent Resin, 10, 20 ... Semiconductor device.

Claims (8)

Plate-shaped silver particles A having a center line average surface roughness Ra of 1 nm or less and a particle size of 0.1 to 5 μm, and a center line average surface roughness Ra of 2 nm to 20 nm and a particle size of 2 nm to 20 nm. A method for producing a silver paste , comprising a step of blending a plate-shaped silver particle B having a size of 1 μm to 20 μm and a solvent. The method for producing a silver paste according to claim 1, wherein the center line average surface roughness Ra of the silver particles A is 0.5 nm or less. The method for producing a silver paste according to claim 1 or 2, wherein the silver particles A are single crystals. The production of the silver paste according to any one of claims 1 to 3, wherein the ratio of the maximum length a in the thickness direction to the maximum length b in the plane direction of the silver particles A satisfies 2 ≦ b / a. Method . The silver paste according to any one of claims 1 to 4, wherein the maximum length a in the thickness direction and the maximum length b in the plane direction of the silver particles A satisfy a ≦ 500 nm and 100 nm ≦ b ≦ 10000 nm, respectively. Manufacturing method . The method for producing a silver paste according to any one of claims 1 to 5, wherein the content of the silver particles B is 80% by mass or less based on the total amount of silver particles. In the step, further blending silver spherical particles having a particle diameter of less than 1μm than 0.01 [mu] m, the manufacturing method of the silver paste according to any one of claims 1 to 6. In the above step, Mg, Al, Si, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Metal or semi-metal particles containing at least one selected from the group consisting of Cd, In, Sn, Sb, Ta, W, Re, Os, Ir, Pt, Au, and Bi are 0.01 based on the total amount of silver paste. The method for producing a silver paste according to any one of claims 1 to 7, which comprises ~ 5.0% by mass.

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