JP2019155479A - Metal particle - Google Patents

Abstract

To solve such problems that in a well-known solder materials such as SAC alloy, there are such defects as the growth of a whisker-like crystal during or after deposition, occurrence of a Kirkendall void or the like and besides, defects such as crack, void and the like are apt to generate during or after deposition between the intermetallic compound layer formed near the boundary face of the object of joint or the like and a joint part or sealing part, and a cell-like Sn layer in which the intermetallic compound covers typically a coarse Sn crystal.SOLUTION: There is provided for solving the above problems, a solder material including Sn, CuSnintermetallic compound, and Cu and having a structure in which those metals and the compound disperse to exist. In the solder material, the substantially whole Cu forms a compound with Sn and the other substances at the time of deposition.SELECTED DRAWING: Figure 1A

Description

  The present invention relates to a solder material, metal particles, a paste, a metal material, a composite material, a semiconductor device, an electronic component, an electric device, an optical device, and a lighting fixture.

  With regard to bonding and sealing related to fine electric circuits typified by semiconductor devices (hereinafter, bonding and sealing may be collectively referred to as “bonding”), the metal that is the object of bonding or the like There are various main compositions such as Cu, Al, and Ni, and it is not uncommon for the surface of an object such as bonding to be covered with another metal such as Au or Ag for the purpose of preventing oxidation. As materials used for such joining, metal materials combining high melting point metals and low melting point metals such as AuSn-based materials, AgSn-based materials, CuSn-based materials, etc. in response to the social demand for lead-free. Are known.

However, for solder materials known so far, such as an alloy composed of Sn, Ag and Cu (hereinafter referred to as “SAC alloy”), at the time of welding or after welding (in the case of welding, the welded portion has an appearance. It is widely used to join or seal a target object by applying heat to the material used for joining or sealing, regardless of whether or not pressure can be applied during joining or not. Metal) formed in the vicinity of the interface between the object to be joined and the joint or seal, such as growth of whisker-like crystals and generation of Kirkendall voids. It is known that defects such as cracks and voids are likely to occur during or after welding between an intermetallic compound layer and a cellular Sn layer that typically covers a coarse Sn crystal with an intermetallic compound.
Furthermore, the metal materials containing Sn that have been known so far do not have the problem of the occurrence of defects such as subsequent bonding due to the phase transformation of the Sn crystals contained in the metal material as the temperature changes. It is out. That is, regarding the phase transformation of Sn crystal, the crystal structure of Sn is β-Sn in the normal temperature range, but the phase transformation from β-Sn to γ-Sn begins to occur in the temperature range of about 161 ° C. or higher, and about 13 It is known that the transformation from β-Sn to α-Sn begins when the temperature is below ℃, and the transformation to α-Sn proceeds as the temperature further decreases. In solving the problem of defects such as bonding, the volume change of Sn crystal due to the phase transformation from β-Sn to α-Sn is large, and α-Sn is very brittle. It is important to suppress the expression of.
Note that generally known data on the difference in density and crystal lattice due to the difference in the crystal structure of Sn is as shown in FIG.

  In addition, for metal materials used for sealing electronic devices, for example, metal materials that combine CoNi alloys and Sn, AuSn metal materials, etc. are known, but for metal materials that combine CoNi alloys and Sn, Since the formation process of the Sn layer is necessary, a material that can realize sealing by a simpler process is required. As for the AuSn-based metal material, Au is expensive, and a metal material made of a cheaper material is demanded.

  In addition, for example, a resin-based bonding material such as a deep UV LED lens and substrate bonding portion or sealing portion has a problem of deterioration, and a SAC alloy cannot realize good bonding or the like. Metal materials are sometimes used, and there is a need for cheaper metal materials that can be substituted for AuSn-based metal materials.

In order to solve the problems as described above, (1) by forming a structure in which fine metal crystals are in fine contact with each other in a metal material such as a solder material used for bonding, etc. The growth of whisker-like crystals that cause defects is prevented as much as possible, and the structure in which the metal crystals are in fine contact makes it possible to disperse stress and relieve strain, and (2) the melting point when forming a bond or the like by welding. Use intermetallic compounds that form high intermetallic compounds and maintain a solid phase even at high temperatures for holding joints or seals (as seen in conventional Sn-Ag-Cu alloys with eutectic composition) Thus, when a typical cellular structure in which an intermetallic compound is formed so as to cover a rough Sn crystal is exhibited, the intermetallic compound exhibiting such a structure is unlikely to have an effect of maintaining bonding or the like. The emergence of a typical cellular structure (3) A metal that easily diffuses into Sn (for example, a metal having the same composition as the object to be joined) and Sn are used for joining and the like. As a structure existing in a dispersed manner in a metal material such as a solder material, a metal (for example, Cu) that easily diffuses into Sn in the metal material at the time of welding is diffused into Sn in the metal material, Substantially all of them form an intermetallic compound with Sn, so that even if the metal itself that is the object of bonding or the like is exposed to a high temperature after welding, it diffuses into the metal material or a new intermetallic compound It is conceivable to suppress the formation of as much as possible.
In order to easily obtain a metal material used for such joining or sealing, it is conceivable to devise the composition of the metal used as the material and the crystal structure itself.

  The present invention relates to a solder material that solves the problems as described above, metal particles that are a material from which such a solder material can be obtained relatively easily, and a metal material containing such metal particles (solder material and other bonding materials). The present invention relates to a semiconductor device, an electronic component, an electric device, an optical device, and a lighting fixture using such a solder material or a metal material.

  On the other hand, the applicant of the present invention in Patent Document 2 includes an outer shell and a core portion, the core portion includes a metal or an alloy, and the outer shell includes an intermetallic compound and covers the core portion. The core portion includes Sn or an Sn alloy, and the outer shell includes metal particles including an intermetallic compound of Sn and Cu (hereinafter referred to as “SnCu outer shell particles” for convenience). . The joint formed by SnCu outer shell particles is used in harsh environments, such as when the high-temperature operating state continues for a long time or when the temperature changes from a high-temperature operating state to a low-temperature stopped state. However, it was possible to maintain high heat resistance, bonding strength and mechanical strength under the environment over a long period of time.

  However, SnCu outer shell particles have a two-layer structure consisting of an outer shell and a core, and the diffusion of Cu and other bonding objects is controlled by the intermetallic compound of the outer shell being interposed between the bonding objects. In order to suppress the generation of Kirkendall voids, the intermetallic compound in the outer shell is as uniform as possible on the object to be joined in a situation where the core of the metal particles melts at a high temperature in the joining process. It was not always easy to distribute the intermetallic compound so as to be in contact. Therefore, there are not many joints between Sn and SnCu except near the boundary between the outer shell and the inner shell, and the outer shell intermetallic compound is bonded in a state of non-uniform contact on the object to be joined. When used in a device having a high temperature, there is a problem that the generation of voids may not be sufficiently suppressed.

In Patent Document 3, for the purpose of maintaining the connection strength at high temperatures, the electrode of the semiconductor device and the electrode of the mounting substrate are connected by a connecting portion having Cu balls, and the Cu balls are intermetallic compound Cu _6. An electronic device connected by Sn ₅ is disclosed.
However, in the technique disclosed in Patent Document 3, Cu grows in one direction at the connection portion to generate a long-axis crystal, which becomes a whisker to cause a crack phenomenon, which inhibits electrical characteristics and has durability. There were problems such as deterioration.

JP 2007-268568 A Japanese Patent No. 6029222 JP 2002-261105 A

  An object of the present invention is to provide a solder material that can maintain good bonding or sealing in a wider temperature range than the prior art, and metal particles that are materials from which such a solder material can be obtained relatively easily. It is an object of the present invention to provide a metal material and a composite material containing metal particles as a material, and a semiconductor device, an electronic component, an electric device, an optical device, and a lighting fixture using the solder material, the metal material, or the composite material.

In order to solve the above-described problems, the present invention first has a structure in which Sn, Cu ₆ Sn ₅ intermetallic compound, and Cu are present in a dispersed state as a lead-free solder material used for joining and sealing. As a solder material in which substantially all of the Cu becomes a compound with another substance during welding, and a material that makes it possible to easily obtain such a solder material, a fine crystal of Sn and a metal Provided are metal particles having an eutectic composition, including those in which a compound crystal is bonded in an endtactic or epitaxial manner, and a metal material and a composite material containing such metal particles as a material, and such a solder material ( Regardless of whether or not the metal particles are included.), A semiconductor device, an electronic component, an electric device, an optical device, and a lighting fixture using a metal material or a composite material are provided.
In addition, as described later, for example, the above-mentioned metal particles include Sn and other metals (in addition, the same applies to other places, but when simply referred to as “metal”, not only a single composition metal but also an alloy or a metal In the atmosphere of an inert atmosphere gas at a pressure higher than atmospheric pressure, and appropriately dropped onto a plate rotating at high speed and refined by rotary spraying. it can.

The features of the solder material of the present invention according to claims 1 and 2 include Sn, Cu ₆ Sn ₅ and Cu, and Cu contained in the solder material is substantially contained when bonding or sealing is performed using the solder material. And CuSn intermetallic compound (and, if the solder material contains a substance that forms a compound with Cu other than Sn, it has a structure in which Cu is dispersed so as to form a compound with the substance) As a result, even when the joint or sealing portion formed using the solder material of the present invention is exposed to a high temperature at which a solid-liquid mixed state is formed, the solid phase CuSn intermetallic compound remains in the joint. It was confirmed that good bonding was maintained.
Next, the metal particles of the present invention are characterized in that crystals of an intermetallic compound of Sn and Cu are dispersed in Sn polycrystals inside the metal particles, and the Sn crystals In order to avoid the occurrence of a typical cellular structure in which the intermetallic compound crystal is formed so as to cover the Sn crystal, and the intermetallic compound crystal includes an endothermic or epitaxially bonded one. Furthermore, it has no eutectic composition. In this way, by dispersing the intermetallic compound crystals as having no eutectic composition, the area of the surface where the Sn crystal and the intermetallic compound are in contact (hereinafter sometimes simply referred to as “interface”). At the same time, many interfaces are finely formed in many directions, and furthermore, the interfaces are bonded in an end-tax or epitaxial manner to form a stable junction, so that it is possible to suppress metal crystal growth due to temperature changes. It was confirmed that the phase transformation from β-Sn to α-Sn accompanied by a relatively large volume change could be suppressed.
And the paste of this invention of Claim 5 which used the metal particle of this invention for the material, and the metal material and composite material of this invention of Claim 6 and 7 (limited to what is used for joining applications, such as solder) No.), even if the composition is different from that of the solder material of the present invention, due to the characteristics of the metal particles of the present invention as described above, a good joint is formed at the time of welding, and β-Sn to α- Good bonding that is not inferior to that of SAC alloy even if a temperature cycle test with a wide temperature difference of -40 ° C to 150 ° C, 175 ° C, or 200 ° C, where there is a concern of poor bonding due to phase transformation to Sn Confirmed to maintain.

  In addition, although Cu, Ag, Au, Ni and various other metals are used for the electronic component, the solder material of the present invention (not limited to the material containing the metal particles of the present invention, and the metal particles of the present invention) In addition to Cu and other metals, as well as resins, elastic bodies, carbon crystals and other substances included in the material)) and the metal materials and composites of the present invention include the composition and welding of objects such as joints. By adjusting the composition according to conditions such as temperature required at times, it is possible to form good bonds with these various metals.

  In addition to the applications described above, the solder material of the present invention and the metal material and composite material of the present invention can be used, for example, for the formation of wiring in microholes such as TSVs, and the junction between the deep UV LED lens and substrate. It can also be used for bonding with various foreign substances such as.

  Therefore, the solder material of the present invention (not limited to the material using the metal particles of the present invention as a material, and in addition to the metal particles of the present invention, other metals such as Cu, further resins, elastic bodies, carbon crystals, etc. In addition, the metal materials and composite materials of the present invention having a composition different from that of the solder material (hereinafter referred to as "the metal material of the present invention" to distinguish from the solder material of the present invention). Can maintain good bonding or the like even when stress, temperature change, or the like is applied, and can also bond well to various metals used in electronic components. Therefore, it is particularly useful for materials such as bonding at fine locations, and is a semiconductor device, electronic component, electric device, or optical device that uses the solder material of the present invention or the metal material of the present invention for electrodes, bonding portions, or sealing portions. The luminaire can obtain good performance that can withstand a wide range of temperature changes.

2 is a STEM image of a cross section obtained by thinly cutting the metal particles 1 obtained in Example 1 of the present invention with FIB (focused ion beam). 5 shows a STEM image of the cross section of the metal particle 1 and the result of element mapping analysis by EDS. 2 is a transmission electron diffraction pattern of metal particles 1. FIG. 4 is a STEM image of a cross section obtained by thinly cutting the metal particles 2 obtained in Example 2 of the present invention with a FIB (focused ion beam). 5 shows a STEM image of a cross section of the metal particle 2 and an element mapping analysis result by EDS. 2 is a TEM image of a cross section of a metal particle 2 and a transmission electron diffraction pattern of an Sn region and an intermetallic compound region. 2 is a TEM image of an interface region between the Sn region and the intermetallic compound region of the metal particle 2 and a transmission electron diffraction pattern of the interface. It is a transmission electron diffraction pattern of Sn region when the metal particles 2 are placed in a low temperature environment. It is a figure for demonstrating an example of the manufacturing apparatus suitable for manufacture of the metal particle of this invention. 3 is a result of cross-sectional SEM image, element mapping analysis by EDS, and qualitative analysis by X-ray diffraction method of a sheet-like metal material (sample 1) produced using the metal particles 3 of the present invention. 3 is a cross-sectional SEM image of a joint obtained by firing Sample 1 between a Si chip and a Cu plate, element mapping analysis by EDS, and qualitative analysis by X-ray diffraction. It is the result of the cross-sectional SEM image of the sheet-like metal material (sample 2) produced by mixing the metal particles 1 and Cu powder of the present invention, the element mapping analysis by EDS, and the qualitative analysis by the X-ray diffraction method. 3 is a cross-sectional SEM image of a joint obtained by burning Sample 2 between a Si chip and a Cu plate, element mapping analysis by EDS, and qualitative analysis by X-ray diffraction. It is a result of the cross-sectional SEM image of the sheet-like metal material (sample 3) produced by mixing the metal particles 3 of the present invention and Cu powder, element mapping analysis by EDS, and qualitative analysis by X-ray diffraction method. 3 is a cross-sectional SEM image of a joint obtained by firing Sample 3 between a Si chip and a Cu plate, element mapping analysis by EDS, and qualitative analysis by X-ray diffraction. Sheet-like joining material (sample 4) obtained by rolling and laminating a sheet-like metal material produced using the metal particles 1 of the present invention and a sheet-like 42 alloy, and a cross-sectional SEM image when sample 4 is fired with a Cu plate The results of element mapping analysis and quantitative analysis by EDS. It is the result of the elemental mapping analysis and quantitative analysis by the cross-sectional SEM image, EDS when the sample 1 and the sheet-like 42alloy are rolled and bonded together, and the sample 5 is fired with the Cu plate. . FIG. 5 shows the result of qualitative analysis by an X-ray diffraction method and an optical microscope image of a bonding material (sample 6) in which the metal particles 1 of the present invention are pasted, a cross-sectional SEM image of a bonded portion sandwiched between Cu plates and firing. FIG. 5 shows the result of qualitative analysis by an X-ray diffraction method and an optical microscope image of a bonding material (sample 7) in which metal particles 3 of the present invention are pasted, a cross-sectional SEM image of a bonded portion sandwiched between Cu plates, and firing. 2 is a STEM image and a TEM image of a cross section of a metal particle 4 used in Comparative Example 1. It is a cross-sectional SEM image of the junction part which baked the joining material (sample 8) which made the metal particle 4 paste-like between the Cu plates. 2 is an optical microscope image of a cross section of a joint obtained by firing Sample 1 and performing a thermal cycle test. FIG. 2 is an optical microscope image of a cross section of a bonded part obtained by firing Sample 2 and conducting a cooling / heating cycle test. FIG. 3 is an optical microscope image of a cross section of a bonded part obtained by firing Sample 3 and performing a thermal cycle test. FIG. 3 is an optical microscopic image of a cross section of a joint obtained by firing Sample 4 and performing a thermal cycle test. FIG. 5 is an optical microscope image of a cross section of a bonded part obtained by firing Sample 5 and conducting a thermal cycle test. FIG. 6 is an optical microscope image of a cross-section of a joint obtained by firing Sample 6 and performing a thermal cycle test. 6 is an optical microscopic image of a cross section of a joint obtained by firing Sample 7 and performing a cooling and heating cycle test. 3 is an optical microscope image of a cross section of a joint obtained by firing Sample 8 and performing a thermal cycle test. It is a generally known diagram showing volume transformation of Sn crystals with temperature.

Hereinafter, the present invention will be described in more detail.
Note that the terms used in this specification are defined as follows even if not specifically described.
(1) The term “metal” may include not only a single metal element but also an alloy or intermetallic compound containing a plurality of metal elements.
(2) When referring to a single metal element, it does not mean only a substance consisting of the metal element completely purely, but also includes a case where a slight other substance is included. That is, it does not mean to exclude impurities, impurities containing other elements invading into the metal crystal, or those in which some of the lattice points of the crystal are replaced with other elements.
(3) The term “metal material” means not only a metal material but also a material made of a metal and a material other than a metal, and also in any shape or form such as a plate, rod, powder, paste, etc. It doesn't matter if there is.
(4) For example, when referring to the Sn region, it does not mean that Sn occupies 100% but shows that the ratio of Sn is the highest among the substances constituting the region. The same applies to the Cu region and the intermetallic compound region.

  In the metal particles of the present invention, crystals of an intermetallic compound between Sn and other metals are dispersed in a polycrystal of Sn, and the crystals of the Sn crystal and the intermetallic compound are endtax or epitaxial. And having no eutectic composition.

The manufacturing method of the metal particle of this invention is demonstrated.
The metal particles of the present invention can be produced, for example, from raw materials in which 8 wt% Cu and 92 wt% Sn are combined (hereinafter referred to as “8Cu · 92Sn”). 8Cu • 92Sn is melted in a vacuum and supplied onto a dish-shaped disk that rotates at high speed in a high nitrogen gas atmosphere pressurized to, for example, about 1.1 × 10 ⁻¹ MPa, and the molten metal is removed by centrifugal force. The metal particles of the present invention can be obtained by appropriately controlling environmental conditions such as scattering as droplets and cooling and solidifying in an environment where the ambient temperature is maintained at 30 ° C to 60 ° C.
Further, if the metal particles of the present invention contain Ni, for example, a combination of 8 wt% Cu, 91.5 wt% and 0.5 wt% Ni (hereinafter referred to as “8Cu · 91.5Sn · 0.5Ni”). It can be obtained by the same method as described above using the material.
In addition, the raw material and manufacturing method of the metal particle of this invention are not limited above.

An example of a production apparatus suitable for producing the metal particles of the present invention will be described with reference to FIG. The granulation chamber 31 has a cylindrical shape at the top and a cone shape at the bottom, and has a lid 302 at the top. A nozzle 303 is inserted vertically in the center of the lid 302, and a dish-shaped rotating disk 304 is provided immediately below the nozzle 303. Reference numeral 305 denotes a mechanism for supporting the dish-shaped rotary disk 304 so as to be movable up and down. Further, a discharge pipe 306 for the generated particles is connected to the lower end of the cone portion of the granulating chamber 31. The upper part of the nozzle 303 is connected to an electric furnace (high frequency furnace) 307 for melting the metal to be granulated. The atmospheric gas adjusted to a predetermined component in the mixed gas tank 308 is supplied to the inside of the granulation chamber 31 and the upper part of the electric furnace 307 through a pipe 309 and a pipe 310, respectively. The pressure in the granulating chamber 31 is controlled by a valve 311 and an exhaust device 312, and the pressure in the electric furnace 307 is controlled by a valve 313 and an exhaust device 314, respectively. Molten metal supplied from the nozzle 303 onto the dish-shaped rotating disk 304 was scattered in the form of fine droplets by the centrifugal force of the dish-shaped rotating disk 304, and was pressurized to, for example, about 1.1 × 10 ⁻¹ MPa. Cooled in an inert atmosphere to metal particles. The generated metal particles are supplied from the discharge pipe 306 to the automatic filter 315 and separated. Reference numeral 316 denotes a particulate collection device.

Examples of the specifications of the production apparatus and the conditions for producing the metal particles of the present invention using the production apparatus include the following.
Dish-shaped rotating disk 304: A dish-shaped disk having an inner diameter of 60 mm and a depth of 3 mm is used, and the speed is 80,000 to 100,000 revolutions per minute.
Granulation chamber 31: 9 × 10 ^-2 using a vacuum chamber having a Pa of about up to vacuum and withstand 1MPa pressure resistance, creating the atmosphere of the vacuum chamber oxygen concentration 200PPM following inert gas such as, a vacuum chamber While maintaining the temperature within 25 to 60 ° C., exhausting simultaneously while supplying an inert gas or the like, the atmospheric pressure in the granulation chamber 31 is brought into a pressurized state (for example, about 1.1 × 10 ⁻¹ MPa).
The particle diameter of the metal particles produced under these conditions (hereinafter referred to as production condition 1) is about 2 μm to 30 μm in diameter.

The metal particles of the present invention thus obtained contain polycrystalline Sn, and in the polycrystalline Sn, an intermetallic compound crystal (for example, Cu ₆ Sn ₅ ) between Sn and Cu is contained. Cu _x Sn _y (where x and y are the composition ratios of the elements in the intermetallic compound crystal)) are present in a dispersed state, and at least a part of the interface between the Sn crystal and the intermetallic compound is Bonded end-taxically or epitaxially.

  The metal particles of the present invention are processed into a sheet shape, or the metal particles of the present invention are combined with other substances (for example, metals such as Cu, nonmetals such as resins, elastic bodies, and carbon crystals) to form sheets or pastes When this is processed and melted in a state where the surface is in contact with the object to be joined, which is a metal, a good joint can be formed by diffusion of the metal on the surface of the object to be joined and the sheet or paste.

  Next, the solder material of the present invention can be obtained as a sheet by, for example, pressing the metal particles of the present invention and Cu powder coated with Si with a roller as follows. That is, the metal particles of the present invention are supplied between a pair of pressure rollers rotating in opposite directions, and the metal particles are pressed by applying heat of about 100 ° C. to 150 ° C. to the metal particles from the pressure roller. Thus, a sheet made of the metal particles of the present invention can be obtained. In addition, the composite material of the present invention having a composition different from that of the solder material of the present invention is obtained by mixing the metal particles of the present invention with other substances or using a roller in the same manner as above without mixing. be able to. In addition, although the solder material of this invention can be easily obtained by using the metal particle of this invention as a material, it is not limited to what uses the metal particle of this invention as a material. Moreover, the manufacturing method of the solder material of this invention and the metal material of this invention is not limited to the above.

  Furthermore, the solder material of the present invention and the metal material of the present invention can be obtained, for example, by mixing the metal particles of the present invention with a resin, a flux or other substances to obtain a paste form. It is also possible to obtain in the form of Further, the solder material of the present invention and the metal material of the present invention should not be excluded from those having a eutectic composition such as a conventional SAC alloy, and are required to have a temperature and heat resistance during welding. Depending on the conditions, a eutectic composition to which a substance having a eutectic composition is added or Bi or other metals are added may be used.

  EXAMPLES Hereinafter, although an Example and a comparative example further demonstrate this invention, this invention is not restrict | limited to the following Example.

Example 1
8Cu · 92Sn was used as a raw material, and metal particles 1 having a diameter of about 2 to 30 μm were produced using the production apparatus shown in FIG.
FIG. 1A is an electron micrograph of a cross section obtained by thinly cutting the metal particle 1 of the present invention with FIB (focused ion beam). It can be seen that the particle size of the metal particles is approximately 10 μm, and the Sn region 121 has the Sn and Cu intermetallic compound region 111.
FIG. 1B is an analysis result when element mapping analysis is performed by EDS in the cross section of the metal particle 1. A region 10 shows the entire STEM image of the cross section of the metal particle 1. From this analysis result, it was confirmed that the region 111 is an intermetallic compound of Sn and Cu, and the region 121 is Sn.
FIG. 1C is a TEM image and a transmission electron diffraction pattern of a cross section of the metal particle 1. Reference numerals 11a, 12a, and 13a denote transmission electron diffraction patterns of 11, 12, and 13, respectively. From these results, it can be seen that 11 is a crystal of an intermetallic compound of Cu and Sn, and 12 is a crystal of Sn. In addition, from the result of 13a, it can be confirmed that the intermetallic compound crystal 11 of Cu and Sn and the Sn crystal 12 are joined in an end-tax or epitaxial manner.
Note that each of the transmission electron diffraction patterns in FIG. 1C was observed at room temperature (room temperature).

Example 2
8Cu · 91.5Sn · 0.5Ni was used as a raw material, and metal particles 2 having a diameter of about 2 to 30 μm were produced using the production apparatus shown in FIG.
FIG. 2A is an STEM image of a cross section obtained by thinly cutting the cross section of the metal particle 2 of the present invention with a FIB (focused ion beam). It can be seen that the particle size of the metal particles is approximately 10 μm, and the Sn region 22 has an Sn and Cu intermetallic compound region 21.
FIG. 2B is an analysis result when element mapping analysis is performed by EDS in the cross section of the metal particle 2. From this analysis result, the region 21 is a region of an intermetallic compound composed of two elements of Sn, Cu, and Ni, the region 22 is a region of Sn, and a small amount of Ni is present in the Sn region 22. It was confirmed to exist.
FIG. 2C is a TEM image and a transmission electron diffraction pattern of a cross section of the metal particle 2. 21a is a transmission electron diffraction pattern in the region of the intermetallic compound 21, and it was confirmed that the intermetallic compound 21 in the measurement region of the transmission electron diffraction pattern was a Cu6Sn5 crystal. 22a is a transmission electron diffraction pattern of the Sn22 region, and it was confirmed that Sn22 is a β-Sn crystal.
FIG. 2D is a TEM image and a transmission electron diffraction pattern of a cross section of the metal particle 2. A region 23 indicates an interface between Sn23 and the intermetallic compound 21. 23a is a transmission electron diffraction pattern of the interface 23, and it was confirmed that Sn22 and the intermetallic compound 21 were end-axially bonded at the interface 23.
FIG. 2E is a transmission electron diffraction pattern in the Sn region when the metal particles 2 are placed in a low temperature environment. Each image is a transmission electron diffraction pattern at a at room temperature (about 15 to 25 ° C.), b at −80 ° C., c at −120 ° C., and d at −160 ° C. From these transmission electron diffraction patterns, Sn in the metal particles 2 should retain the β-Sn crystal structure and not undergo phase transformation into α-Sn even when cooled from room temperature to at least -160 ° C. Was confirmed.

Example 3
As a raw material, a metal in which 8 wt% Cu, 91.9 wt% Sn and 0.1 wt% Ni are combined (hereinafter referred to as “8Cu · 91.9Sn · 0.1Ni”) is used, and the manufacturing apparatus shown in FIG. Then, metal particles 3 having a diameter of about 2 to 30 μm were produced.

Example 4
The metal particles 3 were directly put into a rolling roll and pressed to produce a sheet metal material (hereinafter referred to as sample 1) having a thickness of 70 μm.
FIG. 4A shows the result of elemental mapping analysis by cross-sectional SEM image of sample 1 and EDS, and FIG. 4B shows the result of qualitative analysis by X-ray diffraction method.
From these results, it was confirmed that there was no Cu crystal in the unfired sample 1.
FIG. 5A shows the result of elemental mapping analysis by cross-sectional SEM image and EDS of the bonded part of sample 1 sandwiched between Si chip 101 and Cu plate 301 and fired at 280 ° C. FIG. 5B shows qualitative results by X-ray diffraction method. It is the result of analysis.
A good bonding layer 501 was formed, and no void was observed at the interface between the Si chip 101 and the Cu plate 501.
Moreover, from the result of the qualitative analysis, it was confirmed that there was no Cu crystal in the fired sample 1.

Example 5
A metal powder obtained by mixing 77 wt% of metal particles 1 and Cu powder coated with Si at a ratio of 23 wt% is directly put into a rolling mill, compacted and rolled into a sheet metal material having a thickness of 70 μm (hereinafter, sample 2). And).
FIG. 6A shows the result of elemental mapping analysis by cross-sectional SEM image of sample 2 and EDS, and FIG. 6B shows the result of qualitative analysis by X-ray diffraction method.
From these results, it was confirmed that Cu crystal was present in the unfired sample 2.
FIG. 7A shows the result of elemental mapping analysis by cross-sectional SEM image and EDS of the joint obtained by sandwiching sample 2 between Si chip 101 and Cu plate 301 and firing at 280 ° C. FIG. 7B shows qualitative results by X-ray diffraction method. It is the result of analysis.
A good bonding layer 501 was formed, and no void was observed at the interface between the Si chip 101 and the Cu plate 301.
Moreover, from the result of the qualitative analysis, it was confirmed that there was no Cu crystal in the sample 2 after firing.

Example 6
Metal powder 3 mixed with 77 wt% of metal particles 3 and Cu powder coated with Si at a ratio of 23 wt% is directly put into a rolling mill, compacted, and rolled into a sheet metal material (hereinafter referred to as sample) with a thickness of 70 μm. 3).
FIG. 8A shows the result of elemental mapping analysis by cross-sectional SEM image and EDS of sample 3 used in Example 6, and FIG. 8B shows the result of qualitative analysis by X-ray diffraction method.
From these results, it was confirmed that Cu crystal was present in the unfired sample 3.
FIG. 9A shows the result of elemental mapping analysis using a cross-sectional SEM image and EDS of a joint obtained by sandwiching sample 3 between Si chip 101 and Cu plate 301 and firing at 280 ° C. FIG. 9B shows qualitative analysis by X-ray diffraction method. It is the result of analysis.
A good bonding layer 501 was formed, and no void was observed at the interface between the Si chip 101 and the Cu plate 301.
Moreover, from the result of the qualitative analysis, it was confirmed that there was no Cu crystal in the sample 3 after firing.

Example 7
The metal particles 1 are directly put into a rolling roll machine and compacted and rolled to produce a sheet-like metal material having a thickness of 180 μm. The metal material and a 20 μm-thick metal material (hereinafter referred to as 42 alloy) made of 42 wt% Ni and the remaining amount of Fe (which may contain trace amounts of Cu and Mn) are rolled into 2 of 70 μm thickness. A layered sheet metal material (hereinafter referred to as Sample 4) was produced.
FIG. 10A shows the results of cross-sectional SEM image of sample 4 before firing, element mapping analysis by EDS, and quantitative analysis.
FIG. 10B shows the results of cross-sectional SEM image of sample 4 after firing, element mapping analysis by EDS, and quantitative analysis. It shows that the bonding between the sheet-like metal material made of the metal particles 1 and 42alloy is good.
The results of quantitative analysis are shown in Table 1.

Example 8
Sample 1 (thickness 180 μm) and 42 alloy (thickness 20 μm) were rolled to produce a sheet metal material (hereinafter referred to as sample 5) having a two-layer structure of thickness 70 μm.
FIG. 11A shows the results of cross-sectional SEM image of sample 5 before firing, element mapping analysis by EDS, and quantitative analysis.
FIG. 11B shows the results of cross-sectional SEM image of sample 5 after firing, element mapping analysis by EDS, and quantitative analysis. It shows that the bonding between Sample 5 and 42alloy is good.
The results of quantitative analysis are shown in Table 2.

Example 9
A paste-like bonding material (hereinafter referred to as sample 6) in which metal particles 1 were mixed with a flux was produced. The flux consists of rosin, activator, thixotropic agent and the like.
FIG. 12A is an optical microscopic image of the sample 6 used in Example 9 before firing, and a cross-sectional SEM image of a bonded portion obtained by firing the sample 6 between Cu plates 301 at 280 ° C. FIG. It is the result of qualitative analysis by X-ray diffraction method.
From the result of the qualitative analysis, it was confirmed that there was no Cu crystal in the sample 6 after firing.

Example 10
A paste-like bonding material (hereinafter referred to as sample 7) in which metal particles 3 were mixed with a flux was produced. The flux consists of rosin, activator, thixotropic agent and the like.
FIG. 13A is an optical microscopic image of sample 7 used in Example 10 before firing, and a cross-sectional SEM image of a bonded portion obtained by firing sample 7 between Cu plates 301 at 280 ° C. FIG. 13B is a view after firing. It is the result of qualitative analysis by X-ray diffraction method.
From the result of the qualitative analysis, it was confirmed that there was no Cu crystal in the sample 7 after firing.

Comparative Example 1
Metal particles 4 were produced from a SAC alloy (Sn-3Ag-0.5Cu) by the atomizing method.
14A and 14B are cross-sectional STEM images of the metal particles 4. The Sn crystal 42 grows greatly and has a cell structure in which an intermetallic compound 41 exists between the Sn crystals 42.
FIG. 14C is a cross-sectional TEM image of the metal particles 4. The interface 43 between the Sn crystals 42 is amorphous.

Comparative Example 2
A paste-like bonding material (hereinafter referred to as sample 8) in which metal particles 4 were mixed with a flux was produced. The flux consists of rosin, activator, thixotropic agent and the like.
FIG. 15 is a cross-sectional SEM image of a bonded portion in which the sample 8 used in Comparative Example 2 is sandwiched between Cu plates 301 and fired at 230 ° C. It was confirmed that the void 15 was generated at the interface between the bonding layer 501 and the Cu plate 301.

Samples 1 to 8 were fired and subjected to a thermal cycle test in a temperature range of −40 ° C. to 150 ° C., −40 ° C. to 175 ° C., and −40 ° C. to 200 ° C.
The results are shown in Table 3. In Table 3, o indicates that there are no defects such as voids, cracks, cracks, and peeling, and x indicates that the above-described defects occur.

Sample 8 used in Comparative Example 2 maintains good bonding in 50 and 200 cycle tests in the temperature range of -40 ° C to 150 ° C, but peeling, voids, voids, etc. occur in other conditions. The connection cannot be maintained.
Samples 1 to 7 produced using the metal particles of the present invention maintain good bonding in the temperature ranges of -40 ° C to 150 ° C and -40 ° C to 175 ° C.
In the cycle test in the temperature range of -40 ° C to 200 ° C, there was a sample with a defect, but it was found that it can be improved by adding Ni.

FIG. 16 shows an optical microscope image of the cross section of the joint immediately after firing Samples 1 to 8, and an optical microscopic image of the cross section of the joint after 1000 cycles of a thermal cycle test in the temperature range of −40 ° C. to 200 ° C. It is.
16A: Joint cross-section immediately after the sample 1 is sandwiched between Cu plates 301 and fired at 280 ° C. and after 1000 cycle tests.
Immediately after firing, a good bonding layer 501 is formed, but peeling and voids 15 are generated after 1000 cycles.
16B: A cross-section of the joint immediately after the sample 2 is sandwiched between the Cu plates 301 and fired at 280 ° C. and after the 1000 cycle test.
Immediately after firing, a good bonding layer 501 is formed, but peeling and voids 15 are generated after 1000 cycles.
16C: Cross section of the joint immediately after the sample 3 is sandwiched between the Cu plates 301 and fired at 280 ° C. and after the 1000 cycle test.
Good bonding layer 501 is maintained after 1000 cycles.
16D: Joint cross-section immediately after firing the sample 4 (two-layer structure) sheet surface on the metal particle 1 side and the Cu plate 301 at 280 ° C. and after 1000 cycles test.
Immediately after firing, a good bonding layer 501 is formed, but peeling and voids 15 are generated after 1000 cycles.
16E: Joint cross-section immediately after firing the sheet surface of sample 5 (two-layer structure) on the sample 1 side and the Cu plate 301 at 280 ° C. and after 1000 cycles test.
Good bonding layer 501 is maintained after 1000 cycles.
16F: Joint cross section immediately after the sample 6 is sandwiched between the Si chip 101 and the Cu plate 301 and fired at 280 ° C. and after the 1000 cycle test.
Immediately after firing, a good bonding layer 501 is formed, but peeling and voids 15 are generated after 1000 cycles.
16G: Cross section of the joint immediately after the sample 7 is sandwiched between the Si chip 101 and the Cu plate 301 and fired at 280 ° C. and after the 1000 cycle test.
Good bonding layer 501 is maintained after 1000 cycles.
16H: A cross section of the joint immediately after the sample 8 is sandwiched between the Cu plates 301 and fired at 230 ° C. and after the 1000 cycle test.
Immediately after firing, a good bonding layer 501 is formed, but after 1000 cycles, peeling and voids 15 occur in a wide range.

  The present invention has been described in detail with reference to the accompanying drawings. However, the present invention is not limited to these, and various modifications can be made by those skilled in the art based on the basic technical idea and teachings. It is self-evident that you can think of it.

1, 2, 3, 4 Metal particle 11 Intermetallic compound crystal 12 Sn crystal 13 Interface between 11 and 12 Cu region 15 Void (void)
21 Intermetallic compound region 22 Sn region 101 Si chip 111 Intermetallic compound region 121 Sn region 141 Cu region 301 Cu plate 501 Bonding layer 31 Granulating chamber 302 Lid 303 Nozzle 304 Dish-shaped rotating disk 305 Nozzle 306 Discharge pipe 307 Electric furnace 308 Mixed gas tank 309 Piping 311 Valve 312 Exhaust device 313 Valve 314 Exhaust device 315 Automatic filter 316 Particulate collection device

The feature of the solder material of the present invention includes Sn, Cu ₆ Sn ₅ and Cu, and when the solder material is used for bonding or sealing, substantially all of the Cu contained therein is a CuSn intermetallic compound ( And when the solder material contains a substance that forms a compound with Cu other than Sn, the solder material has a structure in which Cu is dispersed so as to form a compound with the substance). Even when exposed to high temperatures at which a solid-liquid mixed state is formed, the solid phase CuSn intermetallic compound remains in the joint and maintains a good joint in the joint or seal formed using this solder material Confirmed to do.
Next, the metal particles of the present invention are characterized in that crystals of an intermetallic compound of Sn and Cu are dispersed in Sn polycrystals inside the metal particles, and the Sn crystals In order to avoid the occurrence of a typical cellular structure in which the intermetallic compound crystal is formed so as to cover the Sn crystal, and the intermetallic compound crystal includes an endothermic or epitaxially bonded one. Furthermore, it has no eutectic composition. In this way, by dispersing the intermetallic compound crystals as having no eutectic composition, the area of the surface where the Sn crystal and the intermetallic compound are in contact (hereinafter sometimes simply referred to as “interface”). At the same time, many interfaces are finely formed in many directions, and furthermore, the interfaces are bonded in an end-tax or epitaxial manner to form a stable junction, so that it is possible to suppress metal crystal growth due to temperature changes. It was confirmed that the phase transformation from β-Sn to α-Sn accompanied by a relatively large volume change could be suppressed.
And about the paste of this invention which used the metal particle of this invention for the material, and the metal material and composite material of this invention (it is not restricted to what is used for joining uses, such as a solder), the said invention. Even with a composition different from that of the solder material, due to the characteristics of the metal particles of the present invention as described above, a good joint is formed at the time of welding, and a joint failure due to a phase transformation from β-Sn to α-Sn occurs. It was confirmed that even when temperature cycle tests with a wide temperature difference of -40 ° C to 150 ° C, 175 ° C or 200 ° C were performed, good bonding was maintained as good as SAC alloy.

Claims (12)

A solder material comprising Sn and Cu ₆ Sn ₅ intermetallic compound and Cu, has a structure in which the said Sn and Cu ₆ Sn ₅ intermetallic compound Cu is present in a dispersed, substantially of the Cu during welding In general, all solder materials form compounds with Sn and other substances.   The solder material according to claim 1, wherein the solder material contains Ni.   β-Sn crystals and intermetallic compound crystals between Sn and Cu are metal particles including those that are bonded in an endtactic or epitaxial manner, and the melting point is lower than the melting point of Sn. Metal particles that have no eutectic composition.   The metal particle according to claim 3, wherein the metal particle contains Ni.   The paste containing the metal particle of Claim 3 or Claim 4.   A metal material obtained by compacting and rolling or rolling the metal particles of claim 3 or claim 4.   A composite material of the metal material of claim 6 and another metal.   An electrode formed by using at least one of the solder material according to claim 1, the solder material according to claim 2, the paste according to claim 5, the metal material according to claim 6, and the composite material according to claim 7, a joint or a seal Device having a portion.   An electrode formed by using at least one of the solder material according to claim 1, the solder material according to claim 2, the paste according to claim 5, the metal material according to claim 6, and the composite material according to claim 7, a joint or a seal An electronic component having a part.   An electrode formed by using at least one of the solder material according to claim 1, the solder material according to claim 2, the paste according to claim 5, the metal material according to claim 6, and the composite material according to claim 7, a joint or a seal Electrical equipment having a part.   An electrode formed by using at least one of the solder material according to claim 1, the solder material according to claim 2, the paste according to claim 5, the metal material according to claim 6, and the composite material according to claim 7, a joint or a seal Optical device having a part.   An electrode formed by using at least one of the solder material according to claim 1, the solder material according to claim 2, the paste according to claim 5, the metal material according to claim 6, and the composite material according to claim 7, a joint or a seal A lighting fixture having a section.