JP6002947B2 - Metal filler, solder paste, and connection structure - Google Patents

Description

  The present invention relates to a metal filler used for, for example, solder bonding of electronic components and electronic devices, and more particularly to a solder paste, a conductive adhesive, and a connection structure.

  With the development of the information society in recent years, electronic devices such as mobile phones are required to be highly functional, light and thin, and high-density mounting technology has also made rapid progress.

  Various mounting technologies have been developed to make effective use of the limited volume by incorporating components on a board or packaging multiple LSIs into one package. As a result, the solder joints of components built into the board or package are frequently subjected to heat treatment in the subsequent process, and the short-circuit problem due to solder remelting that occurs in the gap between the component and the sealing resin has become apparent. Yes. In recent years, lead-free solder has been demanded in response to environmental problems.

  For this reason, it is desired to develop a lead-free solder material having heat resistance that does not remelt even if it is subjected to a plurality of heat treatments in a subsequent process in connecting components incorporated in the substrate or package.

  The present inventors have proposed a lead-free solder material that can be melt-bonded under reflow heat treatment conditions for lead-free solder and that does not re-melt under the same heat-treatment conditions after bonding (see Patent Document 1).

  The reflow heat treatment conditions for lead-free solder are typical Sn-3.0Ag-0.5Cu (melting point: 217 ° C), and are general reflow heat treatment conditions for solder connection, and have a peak temperature of 240-260 ° C. It is a range.

  The metal filler of the solder material is composed of a mixture of the first metal particles based on Cu and the second metal particles that melt in the reflow heat treatment, and forms a new stable alloy phase in the reflow heat treatment, Even in the reflow heat treatment again, it had the characteristic of not being remelted.

  On the other hand, a solder material using a mixture of Cu particles and Sn particles as a metal filler has been proposed (see Patent Document 2).

  The solder material is characterized in that a compound containing Cu6Sn5 is formed by heat treatment, and the Cu particles are bonded to each other by a compound containing Cu6Sn5.

  Furthermore, a solder material is proposed in which a mixture of particles obtained by plating the surface of Cu particles with Ni and Sn particles is used as a metal filler (see Patent Document 3).

  The solder material is provided with a metal coating that inhibits diffusion to Sn on the surface of Cu particles, thereby inhibiting the formation of a CuSn compound and ensuring wettability by ensuring the time for Sn to wet the electrodes and component terminals. It is characterized by improvement.

International Publication No. 2006/109573 Pamphlet JP 2002-254194 A International Publication No. 2007/125861 Pamphlet

  However, in the techniques described in Patent Documents 1 and 2, the solder material has an excellent feature that it does not remelt in the reflow heat treatment, but the connection reliability against thermal fatigue after soldering is known. There was room for further improvement. Further, in the solder material described in Patent Document 3, since the Ni coating on the Cu particles must be formed by electrolysis or electroless plating, it involves a wet plating process, which leads to productivity, cost, and environmental load. There was room for improvement in terms of

  The present invention has been made in view of the above problems, and can be melt-bonded under reflow heat treatment conditions for lead-free solder. After bonding, it has heat resistance that does not remelt even if subjected to multiple heat treatments in the subsequent process. An object of the present invention is to provide a lead-free solder material or a conductive adhesive excellent in connection reliability against thermal fatigue.

As a result of intensive studies to solve the above-mentioned problems and repeated experiments, the present inventors have reached the present invention.
That is, the present invention is as follows.

[1] A metal filler comprising a mixture of Cu alloy particles and solder particles, wherein the mixture includes 54 to 567 parts by mass of solder particles with respect to 100 parts by mass of Cu alloy particles,
The Cu alloy particles contain 1 to 50% by mass of one or more elements selected from the group consisting of Sn, Ag, Bi, In and Ge, and one or more elements selected from the group consisting of Ni, Fe and Co. 0.01-1% by mass , the balance being Cu alloy particles made of Cu,
The metal filler , wherein the solder particles are Sn particles or Sn alloy particles containing Sn 90 mass% or more .
[ 2 ] The Cu alloy particles are Sn 13.5 to 16.5% by mass, Ag 0.1 to 10% by mass, Bi 4.5 to 5.5% by mass, In 0.1 to 5% by mass, Fe 0.01 to 1%. Cu alloy particles consisting of the remaining mass Cu and the remaining Cu, or Sn 13.5 to 16.5 mass%, Ag 9 to 11 mass%, Bi 4.5 to 5.5 mass%, Ge 0.1 to 5 mass%, Fe 0.01 Any one of the above [1] to [3], which is a Cu alloy particle composed of ˜1 mass% and the balance Cu, or a Cu alloy particle composed of Sn 1 to 25 mass%, Fe 0.01 to 1 mass%, and the balance Cu. Metal filler according to crab.
[ 3 ] A solder paste containing the metal filler according to [1] or [ 2 ].
[4] [1] or a conductive adhesive seen including, reflowed heat treated metal filler described in [2].
[ 5] It has a solder joint that joins the first electronic component and the second electronic component with the solder paste according to [3 ] or the conductive adhesive according to [ 4 ], and the solder joint is A connection structure in which a stable alloy phase having a melting point higher than the melting point of the solder particles is formed .
[ 6 ] A component mounting board having a board and the connection structure according to the above [ 5 ] mounted on the board.
[ 7 ] A component built-in module having a substrate and the connection structure according to [ 5 ] mounted on the substrate.

  The metal filler of the present invention and the solder material or conductive adhesive containing the same can be melt-bonded under reflow heat treatment conditions of lead-free solder, and after bonding, heat resistance that does not remelt even if subjected to multiple heat treatments in the subsequent process Have sex. Moreover, it is excellent in connection reliability against thermal fatigue after soldering.

  Hereinafter, modes for carrying out the present invention (hereinafter abbreviated as embodiments) will be described in detail. In addition, this invention is not limited to the following embodiment, It can deform | transform and implement within the range of the summary.

<Metal filler>
The metal filler of the present embodiment is a metal filler made of a mixture of Cu alloy particles and solder particles, and the Cu alloy particles contain one or more elements selected from the group consisting of Ni, Fe and Co. 0.01 to 1% by mass is contained. This content is the total amount of Ni, Fe and Co present. In the present disclosure, when “consisting of” regarding a constituent element is intended not to exclude the possibility that other elements (for example, inevitable impurities) may be included within a range not impairing the effects of the present invention. The metal filler of the present embodiment is particularly advantageously applied to solder joints due to the characteristics described in detail below.

(Cu alloy particles)
In the present disclosure, Cu alloy particles mean particles containing a Cu-containing alloy, and are typically particles made of a Cu-containing alloy. In a more typical embodiment, the Cu content is the highest among the constituent elements of the Cu alloy particles. In the present embodiment, one or more elements selected from the group consisting of Ni, Fe, and Co contained in the Cu alloy particles are concentrated at the bonding interface with the molten solder particles during the heat treatment, so that the bonding interface The crystal grains of the intermetallic compound produced in the step are refined to suppress the growth of the intermetallic compound. Therefore, according to the metal filler of the present embodiment, it is possible to prevent an increase in internal stress in a solder joint formed using a solder paste or a conductive adhesive containing the metal filler and improve connection reliability. it can.

  In the present embodiment, the content in the Cu alloy particles of one or more elements selected from the group consisting of iron group elements Ni, Fe, and Co is 0.01% by mass or more, so that The effect of suppressing the growth of intermetallic compounds is suitably obtained, and when it is 1% by mass or less, for example, the generation of voids in the solder joints of the solder paste or conductive adhesive is suppressed, and high mechanical strength is obtained. be able to. The content of one or more elements selected from the group consisting of Ni, Fe and Co in the Cu alloy particles is preferably 0.02% by mass or more, more preferably 0.03% by mass or more, preferably Is 0.9 mass% or less, more preferably 0.8 mass% or less.

  In a more typical embodiment, the Cu alloy particles contain Fe in an amount in the above range from the viewpoint of availability of metal raw materials and product safety.

  The content of each element described in the present disclosure can be confirmed by ICP emission analysis. Usually, the content ratio of each element in the Cu alloy particles corresponds to the compounding ratio of the material metals used in the production of the particles.

  The Cu alloy particles are selected from the group consisting of Sn, Ag, Bi, In, and Ge from the viewpoint of obtaining good electrical and mechanical bonding by good alloying by thermal diffusion between the Cu alloy particles and the solder particles. It is preferably composed of 1 to 50% by mass of one or more elements, 0.01 to 1% by mass of one or more elements selected from the group consisting of Ni, Fe and Co, and the balance Cu.

  In particular, as a preferred embodiment for the above reasons, Sn 13.5 to 16.5% by mass, Ag 0.1 to 10% by mass, Bi 4.5 to 5.5% by mass, In 0.1 to 5% by mass, Fe0 Cu alloy particles composed of 0.01 to 1% by mass and the balance Cu are included, and as another preferred embodiment, Sn 13.5 to 16.5% by mass, Ag 9 to 11% by mass, Bi 4.5 to 5.5% by mass. %, Ge 0.1 to 5% by mass, Fe 0.01 to 1% by mass, and Cu alloy particles composed of the balance Cu, and yet another preferred embodiment includes Sn 1 to 25% by mass, Fe 0.01 to 1% by mass. %, And Cu alloy particles composed of the balance Cu.

  The Cu alloy particles preferably have a metastable alloy phase inside. Since the metastable alloy phase is highly reactive, it can be rapidly alloyed with the solder particles melted in the heat treatment. The metastable alloy phase can be confirmed as an exothermic peak in differential scanning calorimetry (DSC). Heat generation in differential scanning calorimetry is detection of latent heat generated when a new alloy phase is formed, and indicates that a metastable alloy phase is present in Cu alloy particles. The metastable alloy phase can be formed by, for example, a rapid solidification method.

  In a typical embodiment, the melting point of the Cu alloy particles (however, when there are a plurality of melting points, the lowest melting point) is 300 ° C. or higher. The melting point is preferably 350 ° C. or higher, more preferably 400 ° C. or higher, and still more preferably 450 ° C. or higher. When the melting point is 300 ° C. or higher, heat resistance is exhibited after solder joining.

(Solder particles)
In the present disclosure, the solder particles mean particles having a melting point of less than 300 ° C. made of one or more metal elements. The solder particles typically include Sn. In a preferred embodiment, the solder particles are substantially free of lead. The melting point of the solder particles is preferably 100 ° C. or higher and 260 ° C. or lower, more preferably 150 ° C. or higher and 250 ° C. or lower, and still more preferably 180 ° C. or higher and 240 ° C. or lower. If the melting point is 100 ° C. or higher, good solder bonding is possible, and if it is 260 ° C. or lower, solder bonding is possible under general reflow heat treatment conditions. The total content of one or more elements selected from the group consisting of Ni, Fe and Co in the solder particles is less than 0.01% by mass in that the wettability at the time of melting the solder is good. preferable.

  As the solder particles, Sn particles (that is, particles made of Sn) or Sn from the viewpoints of wettability between the solder particles, the Cu alloy particles and the substrate electrode surface, and promotion of alloying by thermal diffusion between the solder particles and the Cu alloy particles. Alloy particles are preferred. As the Sn alloy particles, Sn alloy particles containing 90% by mass or more of Sn are preferable from the above viewpoint, and Sn alloy particles containing 90 to 99.5% by mass of Sn are particularly preferable. Since Sn alloy particles generally have a lower melting point than Sn particles, the alloying reaction with Cu alloy particles during heat treatment tends to be faster. Specifically, particles of Sn—Cu eutectic solder, Sn—Ag eutectic solder, and Sn—Ag—Cu eutectic solder are preferable, or one kind of metal such as In, Zn, or Bi is added thereto. Solder particles added as described above can also be used. By adding In, the melting point can be lowered without significantly reducing the metal properties of the alloy. Zn and Bi, as well as In, have the effect of lowering the melting point due to their addition.

  Illustrative examples of the preferred composition of the Sn alloy particles include Sn-0.3Ag-0.7Cu, Sn-0.7Cu, Sn-3.0Ag-0.5Cu, Sn-3.5Ag, Sn-4.0Ag-0. .5Cu, Sn-2.5Ag-0.5Cu-1Bi and the like. Moreover, you may use these individually by 1 type or in mixture of 2 or more types. Although Sn alone is excellent in terms of price, for example, Sn—Ag alloy and Sn—Ag—Cu alloy have a melting point lower by 10 ° C. or more than Sn alone, so that the heat treatment temperature can be set low.

The particle size of the Cu alloy particles and solder particles of the metal filler of the present embodiment is preferably in the range of 5 to 30 μm in average particle size. When the average particle size is 5 μm or more, the specific surface area of the particles becomes small. For example, when a solder paste is formed using a flux described later, the contact area between the particles and the flux is small, so the life of the solder paste is extended. . Further, when the average particle size is 5 μm or more, outgas generated in the reflow heat treatment due to the reduction reaction (particle oxide film removal) by the flux is reduced, so that voids generated inside the connection can be reduced. The average particle size is preferably 30 μm or less from the viewpoint of paste characteristics. When the average particle size is 30 μm or less, the gap between the particles becomes appropriate, the adhesive force is less likely to be impaired, and the removal of components can be prevented in the process from mounting of components to be soldered to completion of reflow heat treatment. .
The particle size distribution can be determined according to the paste application. For example, in screen printing applications, it is preferable to make the particle size distribution broader, with emphasis on plate slippage, and in dispensing applications and via filling applications, emphasis is placed on ejection fluidity and hole filling properties, and the particle size distribution is sharpened. Is preferred.

  From the viewpoint of heat resistance, the mixing ratio of the Cu alloy particles and the solder particles of the metal filler of the present embodiment is preferably 567 parts by mass or less, more preferably 100 parts by mass of the Cu alloy particles. It is 400 parts by mass or less, more preferably 300 parts by mass or less. On the other hand, from the viewpoint of improving the initial bonding state with the solder paste or conductive adhesive containing the metal filler of the present embodiment, the solder particles are preferably 54 parts by mass or more with respect to 100 parts by mass of the Cu alloy particles. Yes, more preferably 82 parts by mass or more.

  As a method for producing Cu alloy particles and solder particles, a known method can be adopted as a method for producing fine powder, but a rapid solidification method is preferred. Examples of the method for producing fine powder by the rapid solidification method include a water spray method, a gas spray method, a centrifugal spray method, and the like. From the point that the oxygen content of particles can be suppressed, a gas spray method and a centrifugal spray method are used. More preferred. In the gas spray method, an inert gas such as nitrogen gas, argon gas, or helium gas can be usually used. However, when producing fine particles having a smaller particle diameter, the linear velocity during gas spray is increased. In order to increase the cooling rate, it is preferable to use helium gas having a low specific gravity. The cooling rate is preferably in the range of 500 to 5000 ° C./second. In the centrifugal spraying method, from the viewpoint of forming a uniform molten film on the upper surface of the rotating disk, the disk material is preferably sialon, and the disk rotation speed is preferably in the range of 60,000 to 120,000 rpm.

<Solder paste>
The present embodiment also provides a solder paste including the metal filler of the present embodiment described above. The solder paste can be lead-free. In the present embodiment, lead-free means that the lead content is 0.1% by mass or less in accordance with EU environmental regulations (RoHS). The solder paste preferably includes a metal filler component and a flux component, and typically includes a metal filler component and a flux component. The metal filler component is the metal filler described above, but may contain a small amount of other metal filler as long as the effects of the present invention are not impaired.

  The content of the metal filler component in the solder paste is preferably in the range of 84 to 94% by mass based on the total mass of the solder paste (that is, 100% by mass) from the viewpoint of paste characteristics. A more preferable range of the content of the metal filler component in the solder paste can be determined according to the use of the paste. For example, in screen printing applications, the ability to remove the plate is important, so the content of the metal filler component in the solder paste is preferably in the range of 87 to 92% by mass, based on the total mass of the solder paste, More preferably, it is the range of 88-91 mass%. Also, in dispensing applications, discharge fluidity is important, so the content of the metal filler component in the solder paste is preferably in the range of 85 to 89% by mass, based on the total mass of the solder paste, and more Preferably, it is the range of 86-88 mass%.

  In general, flux refers to a material that melts faster than solder and cleans the metal surface. The flux component used in the present embodiment preferably contains rosin, a solvent, an activator and a thixotropic agent. Such a flux component is suitable for the surface treatment of the metal filler. That is, the flux component removes the oxide film of the metal filler component in the solder paste during the reflow heat treatment and suppresses reoxidation, thereby promoting alloying by melting and thermal diffusion of the metal. As the flux component, a known material can be used.

<Conductive adhesive>
The present embodiment also provides a conductive adhesive containing the metal filler of the present embodiment described above. In general, the conductive adhesive refers to an adhesive formed by adding a material having good conductivity such as silver, copper, or carbon fiber to a thermosetting resin composition. The conductive adhesive of the present embodiment includes the metal filler of the present embodiment and a thermosetting resin. The conductive adhesive of the present embodiment may or may not include a flux component. The conductive adhesive of the present embodiment may optionally further contain silver, copper, nickel or the like as a metal filler other than the metal filler of the present embodiment. In one aspect, the conductive adhesive can comprise a metal filler, a thermosetting resin, and optionally a flux component. The content of the metal filler component in the conductive adhesive is preferably in the range of 40 to 95% by mass, more preferably in the range of 60 to 94% by mass, and still more preferably in the range of 80 to 93% by mass. When the content of the metal filler is 95% by mass or less, the viscosity of the paste is optimized, and the printability in screen printing or the like is improved. When the content of the metal filler is 40% by mass or more, precipitation of the metal filler can be suppressed.

  Examples of thermosetting resins include epoxy resins, phenolic resins, amino resins, silicon resins, polyurethane resins, unsaturated polyester resins, etc. Among them, excellent compatibility with metal surfaces, and viewpoints of less volume shrinkage during curing To epoxy resins are preferred.

  In general, the conductive adhesive can have characteristics such as lead-free, volatile organic compound (VOC) -free, flux-less, easy low-temperature mounting, and the like. It is suitable for parts that are desired to be soldered but cannot be soldered (for example, devices related to semiconductor chips, liquid crystals, organic EL, LEDs, etc.).

<Connection structure>
The present embodiment is a connection structure having a first electronic component, a second electronic component, and a solder joint that joins the first electronic component and the second electronic component. Also provided is a connection structure in which the solder joint is formed by reflow heat treatment of the solder paste of the present embodiment or the conductive adhesive of the present embodiment.

  For example, when a solder paste is used to connect a mounting component electrode such as an electronic device and a substrate electrode, if the thermal history above the melting point of the solder particles is given under the reflow heat treatment conditions of lead-free solder, the solder The particles are melted, and the mounted component electrode and the substrate electrode are joined via the Cu alloy particles described above. As a result, the thermal diffusion reaction between the metals proceeds at an accelerated rate, and a new stable alloy phase having a melting point higher than the melting point of the solder particles is formed, and the component electrode and the substrate electrode are connected via the Cu alloy particles. A connection structure is formed.

  The melting point of this new stable alloy phase is higher than the reflow heat treatment temperature of lead-free solder, and does not melt even when subjected to multiple heat treatments in the subsequent process. Therefore, according to the solder paste of the present embodiment, it is possible to suppress a short circuit due to solder remelting.

  Examples of the combination of the first electronic component and the second electronic component include a combination of a substrate electrode and a mounted component electrode. As a method of joining the first electronic component and the second electronic component for forming the connection structure according to the present embodiment, a solder paste is applied to the substrate electrode, and then the mounting component electrode is placed and joined by reflow heat treatment. And a method in which a solder paste is applied to the mounting component electrode or the substrate electrode, bumps are formed by reflow heat treatment, the mounting component electrode and the substrate electrode are overlapped, and then reflow heat treatment is performed again. In the above case, the electrodes can be connected by solder bonding between the electrodes.

  The heat treatment peak temperature during reflow is preferably in the range of 240 to 260 ° C, more preferably in the range of 250 to 260 ° C. The peak temperature during this heat treatment is typically set to be equal to or higher than the melting point of the solder particles.

  In particular, when the mounting component electrode such as an electronic device and the substrate electrode are connected using the lead-free solder according to the present embodiment, the solder particles are melted when a thermal history equal to or higher than the melting point of the solder particles is given. The alloying reaction by thermal diffusion proceeds between the alloy particles and the solder particles, and a stable alloy phase having a melting point higher than that of the solder particles as described above is formed.

  The melting point of this new stable alloy phase is higher than the general reflow heat treatment temperature (for example, about 260 ° C.) of lead-free solder composed of Sn-3.0Ag-0.5Cu. Even the solder does not melt. Therefore, according to the present embodiment, it is possible to prevent a short circuit occurring between the component electrodes due to remelting of the solder.

  On the other hand, in the conductive adhesive of the present embodiment, in addition to the heat resistance of the solder joint obtained by using the metal filler of the present embodiment and the connection reliability against thermal fatigue, the adhesion supplement by the thermosetting resin Thus, a stronger connection can be obtained.

<Component mounting board>
The present embodiment also provides a component mounting board having a substrate and the connection structure of the present embodiment mounted on the substrate. The component mounting board is preferably a board on which an electronic component is mounted, and can be used in various conventionally known methods for manufacturing various conventionally known electronic devices.

<Component built-in module>
The present embodiment also provides a component built-in module having a substrate and the connection structure of the present embodiment mounted on the substrate. The component-embedded module is preferably a resin-sealed module, and can be used in a conventionally known manner for manufacturing various known electronic devices.
The various parameters described above are measured according to the measurement method in the examples described later unless otherwise specified.

Next, the present embodiment will be described more specifically by way of examples and comparative examples. However, the present embodiment is not limited to the following examples as long as it does not exceed the gist thereof.
The physical properties of each metal particle, metal filler, and solder paste were evaluated by the methods shown below.

(A) Differential scanning calorimetry (DSC)
Using “DSC-60” manufactured by Shimadzu Corporation, the temperature was increased within a temperature range of 30 to 600 ° C. under a nitrogen atmosphere under a temperature rising temperature of 10 ° C./min. Those having an exotherm or endotherm of ± 1.5 J / g or more were quantified as peaks derived from the measurement object, and peaks below that were excluded from the viewpoint of analysis accuracy.

(B) Average particle diameter A volume integrated average value was measured by a laser diffraction particle size distribution measuring apparatus “HELOS & RODOS” manufactured by Sympatec (Germany), and was defined as an average particle diameter value.

(C) Particle size distribution The particle size distribution was measured using a laser diffraction particle size distribution measuring apparatus “HELOS & RODOS” manufactured by Sympatec (Germany). The measurement range can measure the cumulative distribution in the range of 0.9 μm to 175 μm [R3: 0.5 / 0.9. . . 175 μm] was selected, the trigger condition was set to dry standard, the disperser was set to RODOS, and the dispersion pressure was 3.0 bar. The calculation mode was LD, and the shape factor was 1.0. It was confirmed that the element of the HELOS detector was 10% or more, and the measurement concentration was 5 to 10%.

[Example 1]
(1) Production of Cu alloy particles Cu 6.5 kg (purity 99.9 mass% or more), Sn 1.5 kg (purity 99.9 mass% or more), Ag 1.0 kg (purity 99.9 mass% or more), Bi 0.5 kg (Purity 99.9% by mass or more), In 0.5kg (Purity 99.9% by mass or more), and Fe0.001kg (Purity 99.9% by mass or more) are put in an alumina crucible and are subjected to high-frequency induction heating apparatus in a vacuum. After heating and melting, Cu alloy particles were produced by nitrogen gas atomization.

  The Cu alloy particles were classified at a setting of 5 μm using an airflow classifier “TC-15N” manufactured by Nissin Engineering Co., Ltd. After collecting the large particles, they were classified again at a setting of 30 μm, and the small particles were collected. . When the average particle diameter of the recovered Cu alloy particles was measured, it was 11.2 μm.

  Next, when differential scanning calorimetry of the Cu alloy particles was performed, endothermic peaks were detected at 497 ° C. and 517 ° C., and from a plurality of melting points (that is, 493 ° C. and 512 ° C., both melting start temperatures: solidus temperature), The presence of multiple alloy phases could be confirmed. Further, an exothermic peak was detected at 251 ° C. and 269 ° C., and the presence of a metastable alloy phase could be confirmed.

(2) Solder Particles Yamaishi Metal Co., Ltd. Sn particles “Y-Sn100-Q2510” were used as solder particles. The average particle diameter of the Sn particles was measured and found to be 20.4 μm.
Next, when differential scanning calorimetry of the Sn particles was performed, an endothermic peak was detected at 242 ° C., and it was confirmed that it had a melting point of 232 ° C. (melting start temperature: solidus temperature). A characteristic exothermic peak was not detected.

(3) Production of solder paste The Cu alloy particles and solder particles were mixed at a mass ratio of 100: 186 to obtain a metal filler.
Next, 89.5% by mass of the metal filler and 10.5% by mass of the rosin-based flux are mixed, and this is applied to a solder softener “SPS-1” manufactured by Malcolm Co., Ltd. and a defoaming kneader “SNB-350” manufactured by Matsuo Sangyo Co., Ltd. Solder paste was produced in sequence.

(4) Measurement of 1005R component bonding strength Next, the above solder paste is printed on the Cu electrode of a printed circuit board made of high heat-resistant epoxy resin glass cloth, and a 1005 size 0Ω resistance component (hereinafter referred to as 1005R) is mounted. Thereafter, a reflow heat treatment was performed at a peak temperature of 250 ° C. in a nitrogen atmosphere to prepare a sample. For the printing pattern formation, a screen printer (MT-320TV) manufactured by Microtech Co., Ltd. was used. The printing mask was made of metal, and the squeegee was made of urethane. The mask opening size was set to 400 μm × 500 μm according to the 1005R electrode portion, and the mask thickness was 0.08 mm. The printing conditions were a speed of 50 mm / second, a printing pressure of 0.1 MPa, a squeegee pressure of 0.2 MPa, a back pressure of 0.1 MPa, an attack angle of 20 °, a clearance of 0 mm, and a printing frequency of once.

  Next, when the component bonding strength in the shearing direction of the sample produced as described above was measured with a push-pull gauge at a pushing speed of 10 mm / min, the average value of 30 points was 8.5 N. The bonding strength of the 1005R component is sufficiently practical if it is 5N or more.

(5) Confirmation of thermal fatigue characteristics Next, thermal fatigue characteristics were evaluated by a thermal shock test.
The sample produced as described above (that is, 1005R component mounting sample) is put into “HC-120” manufactured by Espec, and -40 ° C., 125 ° C. for 30 minutes each is set as one cycle, and is taken out after the end of 3000 cycles. When the component bonding strength was measured in the same manner as in (4) above, the average value of 30 points was 6.9 N, and the reduction rate of the bonding strength was 18.8%.

(6) Confirmation of 260 ° C. strength (heat resistance) After the above solder paste is printed on a Cu substrate having a size of 25 mm × 25 mm and a thickness of 0.25 mm, and a Cu chip having a size of 2 mm × 2 mm and a thickness of 0.5 mm is mounted A sample was prepared by reflow heat treatment at a peak temperature of 250 ° C. in a nitrogen atmosphere.

  The heat treatment apparatus used was a reflow simulator “SRS-1C” manufactured by Malcolm Corporation. The temperature profile was raised from the start of heat treatment (room temperature) to 140 ° C. at 1.5 ° C./second, gradually increased from 140 ° C. to 170 ° C. over 110 seconds, and then from 170 ° C. to 250 ° C. The temperature was raised at a rate of 0.0 ° C./second, and the conditions were maintained at a peak temperature of 250 ° C. for 15 seconds.

  For the printing pattern formation, a screen printer “MT-320TV” manufactured by Microtech Co., Ltd. was used. The printing mask was made of metal, and the squeegee was made of urethane. The printing mask opening size was 2 mm × 3.5 mm, and the thickness was 0.1 mm. The printing conditions were a speed of 50 mm / second, a printing pressure of 0.1 MPa, a squeegee pressure of 0.2 MPa, a back pressure of 0.1 MPa, an attack angle of 20 °, a clearance of 0 mm, and a printing frequency of once.

  Next, at room temperature (25 ° C.), the sample prepared as described above was heated to 260 ° C. on a hot plate and held for 1 minute, and then the chip bonding strength in the shear direction was pushed by a push / pull gauge at a pushing speed of 10 mm / min. And measured in terms of unit area. The average value of 30 pieces was 1.7 MPa, and heat resistance capable of maintaining the bonding strength even at 260 ° C. was confirmed.

[Examples 2 and 3, Comparative Examples 1 and 2]
Using the mixture in which the composition of the Cu alloy particles described in Example 1 was changed as a metal filler, pasting and sample preparation were performed in the same manner as in Example 1, and each evaluation was performed. The results are shown in Table 1 as Examples 2-3 and Comparative Examples 1 and 2.

  In addition, the Fe content (5 ppm) of the Cu alloy particles in Comparative Example 1 is not a compound as a raw material metal in nitrogen gas atomization, but is an impurity derived from Sn and Bi raw materials. The metal composition was measured by ICP emission analysis.

  As can be seen from Table 1, in the case where Fe is contained in a predetermined amount of the present invention (Examples 1 to 3), the bonding strength decrease in the thermal shock test (that is, the reduction rate in the table) is about 25 compared with Comparative Example 1. ~ 30% improvement. Moreover, in the state heated to 260 degreeC, there existed joint strength of 0.2 Mpa or more, and sufficient heat resistance which hold | maintains a connection state was confirmed.

[Example 4]
Instead of the solder particles in Example 2, Yamauchi Metal Co., Ltd. Sn-3.5Ag particles “Y-SnAg3.5-Q2510” were used. The average particle size of the particles was measured and found to be 20.1 μm. Next, when differential scanning calorimetry of the particles was performed, it was confirmed that the particles had a melting point of 221 ° C. (melting start temperature: solidus temperature). A characteristic exothermic peak was not detected. Using these particles, pasting and sample preparation were performed in the same manner as in Example 1, and each evaluation was performed. The results are shown in Table 2.

[Example 5]
Instead of the solder particles in Example 2, Sn-3.0Ag-0.5Cu particles “Y-SnAg3Cu0.5-Q2510” manufactured by Yamaishi Metal Co., Ltd. were used. The average particle size of the particles was measured and found to be 20.2 μm. Next, when differential scanning calorimetry of the particles was performed, it was confirmed that the particles had a melting point of 217 ° C. (melting start temperature: solidus temperature). A characteristic exothermic peak was not detected. Using these particles, pasting and sample preparation were performed in the same manner as in Example 1, and each evaluation was performed. The results are shown in Table 2.

  As can be seen from Table 2, in the present embodiment, it was confirmed that the same effect was exhibited even when the solder particles were changed.

[Examples 6 to 10, Comparative Example 3]
Using the mixture in which the mixing ratio of Cu alloy particles and solder particles in Example 2 was changed as a metal filler, pasting and sample preparation were performed in the same manner as in Example 1, and each evaluation was performed. The results are shown in Table 3 as Examples 6 to 10 and Comparative Example 3.

  As can be seen from Tables 1 to 3, in Comparative Example 3, the solder joint was melted and the strength was not obtained in the state heated to 260 ° C., whereas in Examples 1 to 10, the pressure was 0.2 MPa or more. There was bonding strength, and sufficient heat resistance to maintain the connected state was confirmed.

[Example 11]
Cu 9.9 kg (purity 99.9% by mass or more) and Fe 0.01 kg (purity 99.9% by mass or more) were put in an alumina crucible, heated and melted by a high-frequency induction heating device under vacuum, and then by nitrogen gas atomization. Cu alloy particles were prepared.

  The Cu alloy particles were classified using an airflow classifier “TC-15N” manufactured by Nissin Engineering Co., Ltd. at a setting of 20 μm, and after collecting the large particles, they were classified again at a setting of 30 μm, and the small particles were collected. . The average particle diameter of the recovered Cu alloy particles was measured and found to be 15.4 μm. In addition, since this particle | grain is about 100 mass% of Cu, it does not have an endothermic peak and an exothermic peak in the temperature range (30-600 degreeC) of differential scanning calorimetry.

  Using the Cu alloy particles instead of the Cu alloy particles in Example 1, pasting and sample preparation were performed in the same manner as in Example 1, and each evaluation was performed. The results are shown in Table 4.

[Examples 12 to 17]
Using the mixture in which the composition of the Cu alloy particles in Example 11 was changed as the metal filler, pasting and sample preparation were performed in the same manner as in Example 11, and each evaluation was performed. The results are shown in Table 4.
As can be seen from Table 4, in the present embodiment, it is confirmed that the same effect can be obtained when Cu alloy particles of different types of Cu main component are used or when Ni is contained. It was.

  The present invention provides a metal filler used for solder joining of electronic components, electronic devices and the like, and a solder paste or a conductive adhesive containing the same. The present invention is preferably applied to an application (for example, a connection material used for an electronic device such as a component built-in module) that undergoes a plurality of heat treatments in a subsequent process.

Claims (7)

A metal filler comprising a mixture of Cu alloy particles and solder particles, wherein the mixture includes 54 to 567 parts by mass of solder particles with respect to 100 parts by mass of Cu alloy particles,
The Cu alloy particles contain 1 to 50% by mass of one or more elements selected from the group consisting of Sn, Ag, Bi, In and Ge, and one or more elements selected from the group consisting of Ni, Fe and Co. 0.01-1% by mass , the balance being Cu alloy particles made of Cu,
The metal filler , wherein the solder particles are Sn particles or Sn alloy particles containing Sn 90 mass% or more . The Cu alloy particles are Sn 13.5 to 16.5% by mass, Ag 0.1 to 10% by mass, Bi 4.5 to 5.5% by mass, In 0.1 to 5% by mass, Fe 0.01 to 1% by mass, And Cu alloy particles composed of the remaining Cu, or Sn 13.5 to 16.5% by mass, Ag 9 to 11% by mass, Bi 4.5 to 5.5% by mass, Ge 0.1 to 5% by mass, Fe 0.01 to 1% by mass The metal filler according to claim 1, which is Cu alloy particles made of Cu and the balance Cu, or Cu alloy particles made of Sn 1 to 25 mass%, Fe 0.01 to 1 mass%, and the balance Cu. To claim 1 or 2 containing a metal filler described, the solder paste. Conductive adhesive seen including, reflowed heat treated metal filler according to claim 1 or 2. It has the solder joint which joined the 1st electronic component and the 2nd electronic component with the solder paste according to claim 3 , or the conductive adhesive according to claim 4 , and the solder joint is the solder A connection structure in which a stable alloy phase having a melting point higher than the melting point of the particles is formed . A component mounting board comprising: a board; and the connection structure according to claim 5 mounted on the board. The component built-in module which has a board | substrate and the connection structure of Claim 5 mounted on the said board | substrate.