JP2001303294A - Plating particles and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide plated particles excellent in environmental resistance, conductive, easily deformed and excellent in bondability, and a method for producing the same. SOLUTION: The particles have a region represented by a general formula AgxCuy, in which the Ag concentration on the particle surface is higher than the average Ag concentration of the particles,
Metal particles having a multilayer structure with an alloy content of 0.0001 to 1.0% by weight of oxygen content and a central core [m] characterized by having a finely uneven surface, and plating. Forms an alloy layer with the central nucleus, and the plating thickness is 1 to
100 μm, the outermost layer [m + n] is a tin or tin alloy layer, shows a plurality of absorption peak temperatures in differential scanning calorimetry, and has a different tin concentration in tin or tin alloy on the surfaces of the central core alloy particles and the plating particles (Tin gradient alloy film).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of installing a semiconductor device or an electronic component between an electronic circuit board, flip chip (FC) connection, ball grid array (BGA) connection, chip size package (CSP) connection, Anisotropic conductive film (ACF) connection, anisotropic conductive paste (AC
P) The present invention relates to a plated particle which is installed between a package by connection and an electronic circuit board to make an electrical connection, and a method of manufacturing the same. In particular, it relates to an environment-friendly plated particle which can be connected at a relatively low temperature, has excellent fine pitch connection property, exhibits high connection reliability, is excellent in safety without lead, and is environmentally friendly. .

[0002]

2. Description of the Related Art Metal particles used for semiconductor elements, electronic components, electronic circuit boards, and the like are made of an alloy of lead and tin (generally, an alloy of lead and tin).
Eutectic solder with 3% by weight of tin and 37% by weight of lead)
Occupy the mainstream, as a special use, tin-lead alloy composition improvement, gold, silver, copper, nickel and other metals and alloys, or plastic particles as the core tin-lead alloy or gold,
In some cases, particles coated with a metal such as silver, copper, and nickel are used.

In recent years, flip chip (FC) connection for directly connecting a semiconductor element to an electronic circuit board, multi-chip module (MCM), QFP (Quad Flat Package)
Grid array (BGA), chip size package (CSP) connection method, anisotropic conductive film (ACF), anisotropic conductive paste (ACP) An electronic component maker or the like has proposed a new connection method for mounting semiconductor elements and electronic components on an electronic circuit board.

[0004] The metal particles used in these connection methods include tin-lead alloys and their composition-improved particles, or gold, silver,
The particles were particles coated with a tin-lead alloy or a metal such as gold, silver, copper, or nickel with metal or alloy such as copper or nickel, or plastic particles as nuclei. In the method of connecting a semiconductor element to an electronic circuit board, a small high-melting metal sphere such as gold, silver, or copper is sandwiched between the semiconductor element and the electronic circuit board to keep the semiconductor element and the electronic circuit board stand-off,
The contact portions between the semiconductor element and the electronic circuit board and these high-melting metal balls are soldered with solder (tin-lead alloy).

In this method, in order to prevent surface oxidation of the refractory metal sphere, a solder (tin-lead alloy) plating is pre-coated in advance or a connection by solder (tin-lead alloy) is ensured. There are cases where the plating thickness is accurately controlled, and the soldering temperature and time are also precisely controlled. In the form after connection, a small high-melting metal sphere such as gold, silver, or copper is sandwiched between a semiconductor element and an electronic circuit board in a state where a low-melting solder (tin-lead alloy) is directly thinly coated. It has become.

In the FC, BGA or CSP connection system,
A solder ball (tin-lead alloy) is connected between a package on which a semiconductor element is mounted and an electronic circuit board while the solder ball (tin-lead alloy) is sandwiched between the package and an electronic circuit board for a package called an interposer. Alloy) directly. The solder balls (tin-lead alloy) are sandwiched between the electronic circuit board and the package electronic circuit board or semiconductor element, and the solder (tin-lead alloy) is used for the electronic circuit board or the package electronic circuit board. And soldering (tin-lead alloy) by controlling the peak temperature and time with a heating device such as an inert gas reflow furnace with a bump formed on a semiconductor element or a solder ball (tin-lead alloy) The soldering is performed by melting the bumps and the solder balls (tin-lead alloy).

[0007] This method has an aspect that workability is excellent because the current can be applied and soldered by the solder (tin-lead alloy) itself. When solder (tin-lead alloy) is used for bumps in BGA or CSP bump formation, apply flux to the package electrode pattern beforehand.
A solder ball (tin-lead alloy) is placed on the flux, passed through an inert gas reflow furnace with the peak temperature and time controlled, and the solder ball (tin-lead alloy) itself is melted by heating, and the Make a connection.

In this case, a high-temperature solder (tin-lead alloy) in which the composition of tin and lead is changed may be used instead of the eutectic solder (tin-lead alloy) in order to improve the reliability after connection. That is, as the conventional metal particles, spherical high-melting metal particles themselves, or those obtained by bonding spherical high-melting metal particles to an antioxidant treatment (solder plating or the like) with solder (tin-lead alloy), Solder balls (tin-lead alloys) themselves were often used.

Further, if voids are present in the metal particles, there is a possibility that a connection failure may occur such as a decrease in strength of a connection portion, a decrease in connection reliability in a thermal cycle test, and a failure to maintain a stand-off. Means for producing multi-layered particles exhibiting ordered overlapping layers include plating, rolling, vapor deposition, sputtering, molten metal coating, and dipping of nuclear metal or alloy into molten metal. , The oxygen content of the particles, the surface physical property change of the central core metal due to the acid treatment, the presence of a nickel plating layer as a diffusion prevention film, and the like, the required characteristics and the difficulty of the production method, and the production cost thereof were many problems. .

[0010]

As a general method for producing spherical high-melting-point metal particles, there is well known a rolling method in which small pieces of high-melting-point metal are put in a mold and rolled into a spherical shape. However, the spherical high melting point metal particles are not only economically preferable because they are expensive but also the production equipment is expensive. If solder (tin-lead alloy) is plated or pre-coated as a connection material to prevent oxidation of the surface of the refractory metal particles, the mechanical strength of the soldered portion with the semiconductor element or electronic circuit board When a small load such as shock or vibration is applied, the film may easily peel off.

Since the solder ball (tin-lead alloy) can be energized and soldered (connected) with the solder (tin-lead alloy) itself, it is excellent in workability.
It is now used for P, FC connection method, but when mounted on an electronic circuit board and soldered, if any load is applied in the direction of pressing the solder ball (tin-lead alloy), it will itself whisk Solder balls (tin-
(Lead alloy) in some cases.

Further, in order to maintain the shape of the solder ball, the relationship between the ball diameter and the pad diameter to be connected (the ratio of pad diameter / ball diameter is considered to be designed in the range of 0.5 to 1.0). ) Must be designed together with the connection conditions (peak temperature and time) in an inert gas reflow furnace. If the use of a high-temperature solder composition (tin-lead alloy) is used to prevent this whisker, the solder melting temperature itself will increase, which will cause unnecessary thermal effects on the electronic circuit board, deteriorating its function. was there.

Also, since lead in solder (tin-lead alloy) has the property of emitting alpha rays, if it is placed very close to a semiconductor element, it may cause a malfunction of the semiconductor element. There were restrictions, such as the invention. Further, lead in solder (tin-lead alloy) has a drawback that its use tends to be restricted due to its high toxicity. The present invention has the disadvantages of these conventional metal particles for making an electrical connection, namely, that the material is expensive, that the stand-off is accurately maintained, the connection stability between the semiconductor element and the electronic circuit board is difficult to maintain, and that the connection is difficult. The semiconductor element is easily peeled off by a load such as shock or vibration afterwards, balls or bumps are likely to shatter when a load is applied to the semiconductor element at the time of soldering, and the α-ray emitted by the lead in the solder (tin-lead alloy) causes the semiconductor element to The present invention has been invented in order to improve the susceptibility to malfunction and the fact that the solder (tin-lead alloy) itself is toxic to the human body.

[0014]

Means for Solving the Problems The present inventors have conducted various studies on the drawbacks caused when using the conventional metal particles, and have come to understand the following matters. When making electrical connection using spherical refractory metal particles, it is often impossible to maintain an accurate standoff between the semiconductor element and the electronic circuit board because of the difference between the particle surface layer and the refractory metal particle nucleus. This is because cracks are likely to occur because the bonding is not an intermetallic bond (formation of an alloy layer).

[0015] Even if the same high melting point metal particle nuclei are plated with nickel as a diffusion preventing layer on the surface, solder (tin-lead alloy) plating to prevent oxidation, or pre-coated, they are used for electrical connection. The mechanical strength of the part soldered to the circuit board and the electronic circuit board is weakened, and it is easy to peel off with a slight load such as shock or vibration, because the high melting point metal particles and the solder (tin-lead alloy) When the load such as shock or vibration is applied because the components do not mix at the interface (not alloyed) due to a large difference in melting point, and exist as independent metals or alloys at the time of preparation. It seems to be easily peeled off.

In flip chip (FC) connection, the use of high melting point metal particle nuclei results in a long tact time and a high manufacturing cost. The reason why the solder ball (tin-lead alloy) is stiffened by the weight of the semiconductor element itself or a small load at the time of BGA, CSP or FC connection is that the melting point of the solder ball (tin-lead alloy) itself is close to the reflow temperature at the time of connection. Therefore, it is easy to soften and as a result, it seems to be easy to shake.

Based on the above fact recognition, the following invention has been attained. In other words, the plating particles according to claim 1 are composed of a multilayer plating layer ([m + 1] layers, [m
+2] layer, [m + 3] layer,..., [M + n] layer), wherein the central core [m] alloy particles have a general formula AgxCuy [0.001 ≦ x ≦ 0.
4, 0.6 ≦ y ≦ 0.999, x + y = 1 (atomic ratio)]
And has a region where the Ag concentration on the particle surface is higher than the average Ag concentration of the particles, and the oxygen content is 0.0001 to
1.0% by weight, the surface of the alloy particles has a fine uneven shape (the difference in height between the convex portion and the concave portion is 1 μm or less), and the plating layer has a plating thickness of 1 to 100 μm and a multilayer outermost layer [ m
+ N] layer is a tin or tin alloy layer, shows a plurality of absorption peak temperatures in differential scanning calorimetry, and has a different tin concentration in tin or tin alloy between the central core alloy particles and the multilayer plating layer (tin gradient alloy) (Coating).

The plating particles according to a second aspect of the present invention are the plating particles according to the first aspect, wherein the plating solution is a Sn plating solution and the [m + 1] layer of the multilayer plating layer is Cu /
Ag / Sn layer, [m + 2] layer is Ag / Sn layer, [m +
[3] The layer is a Cu / Sn layer, and the outermost [m + 4] layer is a Sn layer. The plating particles according to claim 3 are the plating particles according to claim 1, wherein the plating solution is an Sn / Bi-based plating solution, and the [m + 1] layer of the multilayer plating layer is a Cu / Ag / Sn layer; [M + 2] layer is A
g / Sn layer, [m + 3] layer is Cu / Sn layer, [m + 4]
The layer is a Sn layer, and the outermost [m + 5] layer is a Sn / Bi layer.

Further, the plating particles according to claim 4 are the plating particles according to claim 1, wherein the plating solution is Sn /
In the Cu-based plating solution, the [m + 1] layer of the multilayer plating layer is a Cu / Ag / Sn layer, the [m + 2] layer is an Ag / Sn layer,
[M + 3] layer is Cu / Sn layer, [m + 4] layer is Sn layer,
The [m + 5] outermost layer is a Sn / Cu layer. The plating particles according to claim 5 are the same as those in claim 1.
The plating particles according to the above, wherein the plating solution is Sn / Ag.
[M + 1] layer of the multilayer plating layer is C
u / Ag / Sn layer, [m + 2] layer is Ag / Sn layer, [m
The [+3] layer is a Cu / Sn layer, the [m + 4] layer is a Sn layer, and the outermost [m + 5] layer is a Sn / Ag layer.

[0020] The plating particles according to claim 6 are characterized in that:
Item 2. The plating particles according to Item 1, wherein the plating solution is Sn /
[M + 1] layer of the multilayer plating layer with a Zn-based plating solution
Is a Cu / Ag / Zn layer, and [m + 2] layer is Cu / Ag / S
n layer, [m + 3] layer is Ag / Sn layer, [m + 4] layer is C
u / Sn layer, [m + 5] layer is Sn layer, outermost layer [m + 5]
6] The layer is a Sn / Zn layer. Also,
The method for producing plated particles according to claim 7 is the method according to claims 1 to
6. The method for producing plated particles according to 6, wherein the plating solution
Before plating, acid treatment and diffusion prevention
Without pre-treatment of the ground treatment, the cathode current density is 0.01-30
A / dm ²It is characterized by intermittent energization and electrolytic plating
And

According to a eighth aspect of the present invention, there is provided a method for producing plated particles according to any one of the first to sixth aspects, wherein the plating solution contains 5 wt% of a trace element as a trace element.
It is characterized by adding one or more of the following gold, nickel, palladium, chromium, indium, antimony, aluminum, germanium, silicon, beryllium, tungsten, molybdenum, manganese, tantalum, titanium, neodymium, magnesium, and cobalt. Method for producing plated particles.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The manufacturing method of the alloy particles is AgxCuy [0.001
≦ x ≦ 0.4, 0.6 ≦ y ≦ 0.999, x + y = 1
(Atomic ratio)], a nucleus forming step of producing metal particles by spraying or scattering in a high-pressure inert gas atmosphere a metal melt, and a classification step of classifying the particle size by classification. As a gas used for the inert gas atomization, it is particularly preferable to use a nitrogen gas and a helium gas. Further, the oxygen gas concentration in the inert gas is preferably 1% by volume or less.

At this time, if the Ag content x of the alloy particles serving as the central nucleus of the plating particles is less than 0.001, sufficient oxidation resistance cannot be obtained, and if it exceeds 0.4, the production cost of the alloy particles is low. Get higher. The preferable range of the Ag amount x is 0.0
05 ≦ x ≦ 0.3, more preferably 0.02 ≦
x0.25. Further, the Ag concentration on the particle surface is higher than the average Ag concentration, and the Ag concentration on the surface is preferably 1.4 times or more, more preferably 2.1 times or more, the average Ag concentration. As the Ag concentration on the surface and near the surface of the alloy particles serving as the central nucleus of the plating particles, an X-ray photoelectron spectrometer ESCALAB200-X manufactured by VG, UK was used to measure the surface A at a depth of about 30 angstroms from the surface.
It was determined as g concentration. The Ag concentration at this time is determined by Ag3d _5/2 (Kα line of Al) and Cu3p (M
g Kα line). On the other hand, the average Ag concentration was measured by dissolving a sample in concentrated nitric acid using a high frequency inductively coupled plasma emission spectrometer (JY38P-P2 manufactured by Seiko Instruments Inc.).

The oxygen content of the plating particles in the present invention is the total oxygen content on the surface and inside, and can be measured by an oxygen / nitrogen simultaneous analyzer (EMGA650 manufactured by HORIBA, Ltd.) by an inert gas impulse heating and melting method. The oxygen content affects the connection stability at the time of mounting and the dispersibility in the organic binder. If the content exceeds 1.0% by weight, sufficient removal of the oxide film by the flux or the dispersibility with the organic binder becomes unstable. In addition, a large amount of an additive for removing an oxide film is required, which causes problems such as a decrease in conductivity.

[0025] In addition, due to air oxidation during use, usually 0.0%
An oxygen content of about 001% by weight is shown. If the oxygen content is less than 0.0001% by weight, agglomeration or the like occurs due to activation of the metal surface, and mounting becomes impossible. The preferred oxygen content is 0.00
5 to 0.5% by weight. Further, since the particle surface has a very fine uneven shape (the difference between the height of the convex portion and the concave portion is 1 μm or less), an anchor effect suitable for increasing the strength in bonding with the outer layer is provided. It was also found that the structure did not cause separation between the central core alloy particles and the outer layer.

In the present invention, the irregular shape of the alloy particles and the plating thickness of the plated particles were measured by using a scanning electron microscope (SEM: S-2700 manufactured by Hitachi, Ltd.) after embedding the sample in an epoxy resin and polishing the sample. . The outermost [m + n] layer is a tin or tin alloy layer.
It is a binary alloy layer of tin / silver, tin / copper, tin / bismuth, tin / zinc, etc., such as tin / silver / copper, tin / silver / indium, tin / silver / bismuth, tin / zinc / bismuth, etc. Ternary alloy layers, quaternary alloy layers such as tin / silver / copper / bismuth, and ternary alloy layers such as tin / silver / copper / bismuth / zinc and tin / silver / copper / bismuth / germanium also have the effect. Is known to occur. The outermost layer is preferably a tin-only layer, tin / silver, tin /
It is a binary alloy layer of copper, tin / bismuth, and tin / zinc, and more preferably a binary alloy layer of tin alone, tin / silver, tin / copper, and tin / bismuth.

In other words, since the outermost layer is a tin or tin alloy layer, the connection resistance at the contact is small, and it is soft. Deformation, ensuring a sufficient contact area, etc.
It has sufficiently excellent characteristics for high-density pitches that require dispersibility. The concentration of tin, copper, bismuth, silver, and zinc on the surface and near the surface of the plating particles was determined by using an X-ray photoelectron spectrometer ESCALB200-X manufactured by VG of the United Kingdom at a surface concentration of about 30 angstroms from the surface. It was obtained as. In this case, the tin concentration is Sn3d (Kα line of Mg), the copper concentration is Cu3p (Kα line of Mg), the bismuth is Bi4f (Kα line of Mg), and the silver concentration is Ag3d (Mα line).
g Kα line) and the zinc concentration were determined by using the peak of Zn3p (Mg Kα line) and converting the energy count value to% by weight. On the other hand, the average concentration of each element in the plating particles is measured by dissolving the sample in concentrated nitric acid and using a high-frequency inductively coupled plasma emission spectrometer (JY38P-P2 manufactured by Seiko Instruments Inc.). It was done.

Differential Scanning Calorimetry (Differential Scan)
nig Calorimetry) is a DSC-50 manufactured by Shimadzu Corporation.
The sample was put in an alumina cell by using the method described above, and the measurement was performed in a nitrogen gas atmosphere under the conditions that the temperature was raised to 720 ° C. for 10 minutes after the temperature was raised to 720 ° C. All absorption peaks (endothermic peaks) obtained by the measurement are observed. In addition, no pretreatment with acid is required, and no underlying treatment is required to prevent diffusion.
There has been proposed a method of producing plated particles, characterized by intermittently supplying a current at a cathode current density of 0.01 to 30 A / dm ² for electrolytic plating. Surface Ag of alloy particles serving as central nucleus
It is characterized by having a region where the concentration is higher than the average Ag concentration of the particles, so that oxidation resistance is improved, and a nickel base treatment (formation of a diffusion prevention layer, which is generally called) is not required. This shows a feature that an alloy layer can be formed by a -Cu alloy layer and a layer outside thereof.

The cathode current density is uniform in the composition of the deposit
Properties, particle size, denseness, plating thickness, production time, etc.
However, the preferred cathode current density is 0.05 to 10 A /
dm ²And more preferably 0.1 to 5 A / dm.²
It is. Plating particles can be obtained by using Sn plating solution
The [m + 1] layer is a Cu / Ag / Sn layer, and the [m + 2] layer is A
g / Sn layer, [m + 3] layer is Cu / Sn layer, outermost layer
The [m + 4] layer is characterized in that an Sn layer is formed. During ~
AgxCuy is the alloy particle of the heart nucleus,
To perform Sn plating without undercoating to prevent scattering
Thus, Ag, Cu, and Sn are mutually diffused,
It seems that an alloy layer was formed.

Generally, it is considered that the composition of the plating deposit is controlled by the electronegativity, the standard electrode potential in the aqueous solution, the complex formation constant in the plating solution, the cathode current density, the anode electrode material, and the like. . In the present invention, since the Ag concentration on the surface of the alloy particles serving as the central nucleus is characterized by having a region higher than the average Ag concentration of the particles, the respective alloy layers are formed by the synergistic effect of Ag and Cu. I believe. However, in the alloy plating layer, since the precipitate composition changes sequentially according to the plating thickness, it is considered that the alloy layer is formed by a synergistic effect of Ag and Cu.

Similarly, by using the Sn / Bi-based plating solution, the [m + 1] layer becomes a Cu / Ag / Sn layer and the [m + 2] layer.
The layer was an Ag / Sn layer, the [m + 3] layer was a Cu / Sn layer, and the [m
+4] layer is an Sn layer, and the outermost [m + 5] layer is Sn / Bi.
The [m + 1] layer is a Cu / Ag / Sn layer, the [m + 2] layer is an Ag / Sn layer, the [m + 3] layer is a Cu / Sn layer, and a [m + 3] layer is formed by a Sn / Cu-based plating solution. m +
The feature is that the [4] layer is a Sn layer, and the outermost [m + 5] layer is a Sn / Cu layer.

Further, [m
+1] layer is Cu / Ag / Sn layer, and [m + 2] layer is Ag /
The Sn layer and the [m + 3] layer are characterized in that a Cu / Sn layer, the [m + 4] layer is a Sn layer, and the outermost [m + 5] layer is a Sn / Ag layer. m +
1] layer is Cu / Ag / Zn layer, [m + 2] layer is Cu / A
g / Sn layer and [m + 3] layer are Ag / Sn layer and [m + 4]
It is characterized in that the layer is a Cu / Sn layer, the [m + 5] layer is a Sn layer, and the outermost [m + 6] layer is a Sn / Zn layer.

In the case of an alloy-based plating solution, the solution is often adjusted so that the alloy composition of the plating precipitate and the concentration of each metal in the plating solution are matched. However, since the present invention is characterized in that the Ag concentration on the surface of the alloy particles serving as the central nucleus has a region higher than the average Ag concentration of the particles, the respective alloy layers are formed by the synergistic effect of Ag and Cu. Therefore, regardless of the metal concentration in the plating solution, a stable plating precipitate alloy composition can be obtained as long as the added metal species is not an unstable plating solution composition that precipitates in the plating solution. .

In addition, detoxification was achieved by removing highly toxic lead from the constituent elements of the metal particles. It emits α-rays that may cause malfunctions of semiconductor elements, is toxic to the human body, and is a lead-free plating particle that has been claimed to be an environmental issue. In addition, gold with an addition amount of 5 wt% or less as a trace element,
Nickel, palladium, chromium, indium, antimony, aluminum, germanium, silicon, beryllium, tungsten, molybdenum, manganese, tantalum,
Of titanium, neodymium, magnesium and cobalt,
It is characterized by adding one or more types.

Preferred trace elements are gold, nickel, palladium, chromium, indium, antimony, aluminum, germanium and cobalt, more preferably gold, nickel, palladium, indium, antimony,
Aluminum and germanium. In BGA, CSP and FC which are connection methods in recent years, the diameter of metal particles has been reduced. Due to the further miniaturization of electronic component size, finer lines / spaces, and smaller pad diameters, for example, in the relationship between particle diameter and pad diameter, solder balls (tin-lead alloy) spread on pads due to reflow temperature. It is often observed that the spherical shape cannot be maintained.

However, in the plated particles according to the present invention, it is easy to obtain high connection reliability while maintaining a spherical shape without worrying about the reflow temperature. That is,
In reducing the size of electronic components, the pad diameter can be designed without restriction on the size of the metal particles used (pad diameter /
The ratio of the ball diameters can be freely designed), and further, the whiskers and poor connection of the metal particles are eliminated.

[0037]

Example 1 Next, the present invention will be described in detail based on examples and comparative examples, but the present invention is not limited to these examples. Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. (1) Production of Alloy Particles 16 kg of Cu particles (purity of 99% by weight or more) and 4 kg of Ag particles (purity of 99% by weight or more) were put into a graphite crucible, melted and heated to 1400 ° C. by a high frequency induction heating device.
The atmosphere was performed in nitrogen of 99% by volume or more. Next, after introducing the molten metal from the tip of the crucible into a spray tank in a helium gas atmosphere, helium gas (purity of 99% by volume or more, oxygen concentration of 0.1% by volume) is supplied from a gas nozzle provided near the tip of the crucible. , And a pressure of 2.5 MPaG) to perform atomization (manufactured by Makabe Giken) to produce alloy particles.
The obtained alloy particles were scanned with a scanning electron microscope (S
-2700), it was spherical (volume average particle diameter 0.025 mm, maximum particle diameter 0.2 mm).

The Ag concentration on the surface of the alloy particles was measured by X-ray photoelectron spectroscopy (X-ray photoelectron spectroscopy ES, manufactured by VG, UK).
The average Ag concentration of the alloy particles was dissolved in concentrated nitric acid, and measured by plasma emission spectrometry (JY38P-P2 manufactured by Seiko Instruments Inc.). The average ratio of Ag concentration to the surface of the obtained alloy particles was 2.2. In addition, the sample was embedded in an epoxy resin, and the section of the alloy particle was observed with an electron microscope. It was confirmed that there was no void inside the alloy particle. Further, the difference in height between the convex portion and the concave portion was 0.5 μm.

(2) Classification of Alloy Particles The obtained alloy particles were divided into openings of 0.13 mm and 0.18 mm.
Using a stainless steel test sieve (manufactured by Taiyo Seimitsu Kogyo). When 100 particles were observed with a scanning electron microscope, the volume average particle diameter was 0.15 mm. The oxygen content of the alloy particles was 0.02% by weight. (3) Plating layer formation Using the alloy particles obtained by the above-described method as nuclei, a rotary plating apparatus (flow slulator RP- manufactured by Uemura Kogyo Co., Ltd.)
In 1), the Sn pre-plating was performed only by washing with water. The Sn plating solution is a composition obtained by removing the Pb component from the solution composition for Sn / Pb eutectic solder plating, the plating temperature is 25 ° C., the current density is 0.15 A / dm ² , and the plating time is 4
Went on time. The anode material was Sn, and the cathode material was a Ti alloy. Washing after plating was performed only with water washing. The plated particles after water washing were replaced with an organic solvent, and then dried with a dryer at 60 ° C.

(4) Measurement of Physical Properties of Plating Particles As a result of observing 100 plating particles by a scanning electron microscope, the volume average particle diameter was 0.17 mm. Also, the obtained plated particles were embedded in an epoxy resin, and after polishing, a cross section was observed with a scanning electron microscope. The plating thickness was 0.008 to 0.013 mm.

Further, when the elemental analysis of the particle surface and center (EMAX-5770 manufactured by Horiba, Ltd.) was carried out, the following results were obtained. The line types used in the analysis were Ag; Lα line, Cu; Kα line, and Sn; Lα line, and the energy count value was converted to% by weight. Central part 0.03 mm 0.07 mm 0.08 mm Ag 20 20 15 10 (% by weight) Cu 80 80 755 (% by weight) Sn 0 0 10 85 (% by weight)

Next, elemental analysis of the outermost surface (depth 3 from the surface)
(About 0 Angstroms)) by X-ray photoelectron spectroscopy. The peak used in the analysis was Ag3d _3/2 (M
g Kα ray), Cu3p (Mg Kα ray), Sn3d
_5/2 (Kα line of Mg). As a result, the outermost surface has S
It was confirmed that only n existed. Finally, the endothermic peak temperature (indicating the melting point) of the plated particles was measured under a nitrogen atmosphere by DSC-50 manufactured by Shimadzu Corporation. as a result,
An Sn layer as an [m + 4] layer at 232 ° C., a Cu / Sn layer as an [m + 3] layer at 353 ° C., and an [m +
2] There was an endothermic peak of an Ag / Sn layer as a layer, and an endothermic peak at 606 ° C. of a Cu / Ag / Sn layer as an [m + 1] layer.

The upper limit of the operating temperature of the measuring device was 720 ° C., and the melting point of the alloy particles used as the central nucleus was unknown. As a result of the measurement, it was observed that the alloy particles could not maintain a spherical shape at around 780 ° C, and that the alloy particles were completely dissolved at 990 ° C. It was confirmed that the endothermic peak obtained by DSC measurement was derived from the plating layer.

(5) Evaluation of mounting characteristics The obtained plated particles were mounted on 0.25 mmΦ copper lands patterned on an FR-4 substrate. After applying the RMA type flux, the plated particles were mounted and connected in a nitrogen reflow furnace at 230 ° C. Observation of the shape after connection and measurement of the dimension in the vertical direction were performed on the prepared 100 samples. As a result, the shape after connection maintains a spherical shape,
None of the plating particles were deformed. The average value of the dimension in the vertical direction after connection is 0.16 mm ± 0.005.
mm.

Further, it was similarly connected to a 1.00 mmΦ copper land in a nitrogen reflow furnace at 230 ° C. Created 10
Observation of the shape after connection and measurement of the dimension in the vertical direction were performed on 0 samples. As a result, the shape after connection maintained a spherical shape, and no plated particles were deformed. The average dimension in the vertical direction after connection is 0.16 m
m ± 0.006 mm. In addition, it was connected with a nitrogen reflow furnace at 280 ° C. with a 1.00 mmΦ copper land. Observation of the shape after connection and measurement of the dimension in the vertical direction were performed on the prepared 100 samples. As a result, the shape after connection maintains a spherical shape, and the number of deformed metal plating particles is one.
I didn't. Moreover, the dimension average value in the vertical direction after the connection was 0.16 mm ± 0.006 mm.

[0046]

Example 2 Sn / Bi plating was carried out in a rotary plating apparatus using the alloy particles obtained in (1) and (2) of Example 1 as nuclei, with plating only being washed with water. The Sn / Bi plating solution has a composition obtained by adding 5% by weight of Bi to the Sn plating solution, the plating temperature is 25 ° C., and the current density is 0.15 A / d.
m ² and a plating time of 4 hours. The anode material was Sn, and the cathode material was a Ti alloy. The plated particles after water washing were replaced with an organic solvent, and then dried with a dryer at 60 ° C.

(1) Measurement of Physical Properties of Plating Particles As a result of observing 100 plating particles using a scanning electron microscope, the volume average particle diameter was 0.17 mm. Further, the plating particles were embedded in an epoxy resin, and after polishing, the cross section was observed with a scanning electron microscope. The plating thickness was 0.007 to 0.012 mm. Further, when the elemental analysis of the particle surface and the center was performed, the following results were obtained. The line type used in the analysis was Ag; Lα
Line, Cu; Kα line, Sn; Lα line, Bi; Mα line, and the energy count value was converted to% by weight. Central part 0.03 mm 0.07 mm 0.08 mm Ag 20 20 15 10 (% by weight) Cu 80 80 705 (% by weight) Sn 0 0 10 45 (% by weight) Bi 0 0 540 (% by weight)

Next, an elemental analysis of the outermost surface (depth 3 from the surface)
(About 0 Angstroms)) by X-ray photoelectron spectroscopy. The peak used in the analysis was Ag3d _3/2 (M
g Kα ray), Cu3p (Mg Kα ray), Sn3d
_5/2 (Kα line of Mg) and Bi4f (Kα line of Mg). As a result, it was confirmed that Sn and Bi existed on the outermost surface. The abundance ratio was 46% by weight of Sn and 54% by weight of Bi. Further, the endothermic peak temperature (indicating the melting point) of the metal particles was measured by DSC under a nitrogen atmosphere. As a result, at 138 ° C., Sn /
Bi layer, Sn layer as [m + 4] layer at 232 ° C., 35
Cu / Sn layer as [m + 3] layer at 3 ° C, Ag / Sn layer as [m + 2] layer at 490 ° C, [m + 3] at 610 ° C
1] There was an endothermic peak of the Cu / Ag / Sn layer as a layer. The upper limit of the operating temperature of the measuring device is 720 ° C. When the melting point of the alloy particles used as the central nucleus is separately measured with a high-temperature microscope under a nitrogen atmosphere, the alloy particles can maintain a spherical shape at around 780 ° C. It disappeared and it could be observed that it completely dissolved at 990 ° C., and it was confirmed that the endothermic peak obtained by DSC measurement was derived from the plating layer.

(2) Evaluation of Mounting Characteristics The obtained plated particles were mounted on 0.25 mmφ copper lands patterned on an FR-4 substrate. After applying the RMA type flux, the plated particles were mounted and connected in a nitrogen reflow furnace at 230 ° C. Observation of the shape after connection and measurement of the dimension in the vertical direction were performed on the prepared 100 samples. As a result, the shape after connection maintains a spherical shape,
None of the plating particles were deformed. The average dimension in the vertical direction after connection is 0.16 mm ± 0.004.
mm.

Further, it was similarly connected to a 1.00 mmφ copper land in a nitrogen reflow furnace at 230 ° C. Created 10
Observation of the shape after connection and measurement of the dimension in the vertical direction were performed on 0 samples. As a result, the shape after connection maintained a spherical shape, and no plated particles were deformed. The average dimension in the vertical direction after connection is 0.16 m
m ± 0.005 mm. In addition, it was connected with a nitrogen reflow furnace at 280 ° C. with a 1.00 mmΦ copper land. Observation of the shape after connection and measurement of the dimension in the vertical direction were performed on the prepared 100 samples. As a result, the shape after connection maintained a spherical shape, and no plated particles were deformed. In addition, the dimension average value in the vertical direction after connection is 0.1.
16 mm ± 0.006 mm.

[0051]

Example 3 Sn / Cu plating was carried out in a rotary plating apparatus using the alloy particles obtained in (1) and (2) of Example 1 as nuclei, with plating pretreatment only by washing with water. The Sn / Cu plating solution has a composition in which 1% by weight of Cu is added to the Sn plating solution, the plating temperature is 25 ° C., and the current density is 0.15 A / d.
m ² and a plating time of 4 hours. The anode material was Sn, and the cathode material was a Ti alloy. The plated particles after water washing were replaced with an organic solvent, and then dried with a dryer at 60 ° C.

(1) Measurement of Physical Properties of Plating Particles As a result of observing 100 plating particles by a scanning electron microscope, the volume average particle diameter was 0.17 mm. Further, the plating particles were embedded in an epoxy resin, and after polishing, the cross section was observed with a scanning electron microscope. The plating thickness was 0.007 to 0.012 mm. Further, when the elemental analysis of the particle surface and the center was performed, the following results were obtained. The line type used in the analysis was Ag; Lα
Line, Cu; Kα line, Sn; Lα line, and the energy count value was converted to% by weight. Central part 0.03 mm 0.07 mm 0.08 mm Ag 20 20 155 (% by weight) Cu 80 80 70 15 (% by weight) Sn 0 0 15 80 (% by weight)

Next, elemental analysis of the outermost surface (depth 3 from the surface)
(About 0 Angstroms)) by X-ray photoelectron spectroscopy. The peak used in the analysis was Ag3d _3/2 (M
g Kα ray), Cu3p (Mg Kα ray), Sn3d
_5/2 (Kα line of Mg). As a result, the outermost surface has S
It was confirmed that n and Cu were present. The abundance ratio was 95% by weight of Sn and 5% by weight of Cu.

Further, the endothermic peak temperature (indicating the melting point) of the plated particles was measured by DSC under a nitrogen atmosphere. As a result, at 227 ° C., Sn /
Cu layer, Sn layer as [m + 4] layer at 232 ° C., 35
Cu / Sn layer as [m + 3] layer at 3 ° C, Ag / Sn layer as [m + 2] layer at 490 ° C, [m + 3] at 610 ° C
1] There was an endothermic peak of the Cu / Ag / Sn layer as a layer. The upper limit of the operating temperature of the measuring device is 720 ° C. When the melting point of the alloy particles used as the central nucleus is separately measured with a high-temperature microscope under a nitrogen atmosphere, the alloy particles can maintain a spherical shape at around 780 ° C. It disappeared and it could be observed that it completely dissolved at 990 ° C., and it was confirmed that the endothermic peak obtained by DSC measurement was derived from the plating layer.

(2) Evaluation of Mounting Characteristics The obtained plated particles were mounted on 0.25 mmφ copper lands patterned on an FR-4 substrate. After applying the RMA type flux, the plated particles were mounted and connected in a nitrogen reflow furnace at 230 ° C. Observation of the shape after connection and measurement of the dimension in the vertical direction were performed on the prepared 100 samples. As a result, the shape after connection maintains a spherical shape,
None of the plating particles were deformed. The average dimension in the vertical direction after connection is 0.16 mm ± 0.004.
mm.

Further, it was similarly connected to a 1.00 mmΦ copper land in a nitrogen reflow furnace at 230 ° C. Created 10
Observation of the shape after connection and measurement of the dimension in the vertical direction were performed on 0 samples. As a result, the shape after connection maintained a spherical shape, and no plated particles were deformed. The average dimension in the vertical direction after connection is 0.16 m
m ± 0.005 mm. In addition, it was connected with a nitrogen reflow furnace at 280 ° C. with a 1.00 mmΦ copper land. Observation of the shape after connection and measurement of the dimension in the vertical direction were performed on the prepared 100 samples. As a result, the shape after connection maintained a spherical shape, and no plated particles were deformed. In addition, the dimension average value in the vertical direction after connection is 0.1.
16 mm ± 0.006 mm.

[0057]

Example 4 Sn / Ag plating was carried out in a rotary plating apparatus using the alloy particles obtained in (1) and (2) of Example 1 as nuclei, with plating only being washed with water. The Sn / Ag plating solution has a composition in which 4% by weight of Ag is added to the Sn plating solution, the plating temperature is 25 ° C., and the current density is 0.15 A / d.
m ² and a plating time of 4 hours. The anode material was Sn, and the cathode material was a Ti alloy. The plated particles after water washing were replaced with an organic solvent, and then dried with a dryer at 60 ° C.

(1) Measurement of Physical Properties of Plating Particles As a result of observing 100 obtained plating particles with a scanning electron microscope, the volume average particle diameter was 0.17 mm. Further, the plating particles were embedded in an epoxy resin, and after polishing, the cross section was observed with a scanning electron microscope. The plating thickness was 0.007 to 0.012 mm. Further, when the elemental analysis of the particle surface and the center was performed, the following results were obtained. The line type used in the analysis was Ag; Lα
Line, Cu; Kα line, Sn; Lα line, and the energy count value was converted to% by weight. Central part 0.03 mm 0.07 mm 0.08 mm Ag 20 20 15 15 (% by weight) Cu 80 80 705 (% by weight) Sn 0 0 15 80 (% by weight)

Next, elemental analysis of the outermost surface (depth 3 from the surface)
(About 0 Angstroms)) by X-ray photoelectron spectroscopy. The peak used in the analysis was Ag3d _3/2 (M
g Kα ray), Cu3p (Mg Kα ray), Sn3d
_5/2 (Kα line of Mg). As a result, the outermost surface has S
It was confirmed that n and Ag were present. The abundance ratio was 96% by weight of Sn and 4% by weight of Ag. Further, the endothermic peak temperature (indicating the melting point) of the plated particles was measured by DSC under a nitrogen atmosphere. As a result, [m
+5] Sn / Ag layer as a layer, [m + 4] at 232 ° C.
Sn layer as layer, C as [m + 3] layer at 353 ° C.
u / Sn layer, Ag / S as [m + 2] layer at 490 ° C.
n layer, Cu / Ag / S as [m + 1] layer at 606 ° C.
There was an endothermic peak for the n-layer.

The upper limit of the operating temperature of the measuring device was 720 ° C., and the melting point of the alloy particles used as the center nucleus was measured separately under a nitrogen atmosphere using a high-temperature microscope.
At around ℃, the alloy particles can not maintain the spherical shape, 990 ℃
And complete dissolution was observed, and it was confirmed that the endothermic peak obtained by DSC measurement was derived from the plating layer. (2) Evaluation of mounting characteristics The obtained plated particles were mounted on 0.25 mmΦ copper lands patterned on an FR-4 substrate. After applying the RMA type flux, the plated particles were mounted and connected in a nitrogen reflow furnace at 230 ° C. Observation of the shape after connection and measurement of the dimension in the vertical direction were performed on the prepared 100 samples. As a result, the shape after connection maintains a spherical shape,
None of the plating particles were deformed. The average dimension in the vertical direction after connection is 0.16 mm ± 0.004.
mm.

Further, it was similarly connected to a 1.00 mmφ copper land in a nitrogen reflow furnace at 230 ° C. Created 10
Observation of the shape after connection and measurement of the dimension in the vertical direction were performed on 0 samples. As a result, the shape after connection maintained a spherical shape, and no plated particles were deformed. The average dimension in the vertical direction after connection is 0.16 m
m ± 0.005 mm. In addition, it was connected with a nitrogen reflow furnace at 280 ° C. with a 1.00 mmΦ copper land. Observation of the shape after connection and measurement of the dimension in the vertical direction were performed on the prepared 100 samples. As a result, the shape after connection maintained a spherical shape, and no plated particles were deformed. In addition, the dimension average value in the vertical direction after connection is 0.1.
16 mm ± 0.006 mm.

[0062]

Fifth Embodiment Sn / Zn plating was carried out in a rotary plating apparatus by using the alloy particles obtained in (1) and (2) of Example 1 as nuclei, with plating pretreatment only by washing with water. The Sn / Zn plating solution has a composition in which 10% by weight of Zn is added to the Sn plating solution, the plating temperature is 25 ° C., and the current density is 0.15 A /
dm ² and a plating time of 4 hours. The anode material was Sn, and the cathode material was a Ti alloy. The plated particles after water washing were replaced with an organic solvent, and then dried with a dryer at 60 ° C.

(1) Measurement of Physical Properties of Plating Particles As a result of observing 100 of the obtained plating particles with a scanning electron microscope, the volume average particle diameter was 0.17 mm. Further, the plating particles were embedded in an epoxy resin, and after polishing, the cross section was observed with a scanning electron microscope. The plating thickness was 0.007 to 0.012 mm. Further, when the elemental analysis of the particle surface and the center was performed, the following results were obtained. The line type used in the analysis was Ag; Lα
Line, Cu; Kα line, Sn; Lα line, Zn; Kα line, and the energy count value was converted to% by weight. Central part 0.03 mm 0.07 mm 0.08 mm Ag 20 20 130 (% by weight) Cu 80 80 705 (% by weight) Sn 0 0 1585 (% by weight) Zn 0 0 210 (% by weight)

Next, elemental analysis of the outermost surface (depth 3 from the surface)
(About 0 Angstroms)) by X-ray photoelectron spectroscopy. The peak used in the analysis was Ag3d _3/2 (M
g Kα ray), Cu3p (Mg Kα ray), Sn3d
_5/2 (Kα line of Mg) and Zn3p (Kα line of Mg). As a result, it was confirmed that Sn and Zn were present on the outermost surface. The abundance ratio was 85% by weight of Sn and 15% by weight of Zn.

The endothermic peak temperature (indicating the melting point) of the plated particles was measured by DSC under a nitrogen atmosphere. As a result, at 195 ° C., the Sn /
Zn layer, Sn layer as [m + 5] layer at 232 ° C., 35
Cu / Sn layer as [m + 4] layer at 3 ° C., Ag / Sn layer as [m + 3] layer at 490 ° C., [m + 4] at 610 ° C.
2] Cu / Ag / Sn layer as layer, [m +
1] There was an endothermic peak of the Cu / Ag / Zn layer as a layer. The upper limit of the operating temperature of the measuring device is 720 ° C. When the melting point of the alloy particles used as the central nucleus is separately measured with a high-temperature microscope under a nitrogen atmosphere, the alloy particles can maintain a spherical shape at around 780 ° C. It disappeared and it could be observed that it completely dissolved at 990 ° C., and it was confirmed that the endothermic peak obtained by DSC measurement was derived from the plating layer.

(2) Evaluation of mounting characteristics The obtained plated particles were mounted on 0.25 mmΦ copper lands patterned on an FR-4 substrate. After applying the RMA type flux, the plated particles were mounted and connected in a nitrogen reflow furnace at 230 ° C. Observation of the shape after connection and measurement of the dimension in the vertical direction were performed on the prepared 100 samples. As a result, the shape after connection maintains a spherical shape,
None of the plating particles were deformed. The average dimension in the vertical direction after connection is 0.16 mm ± 0.004.
mm.

Further, it was similarly connected to a copper land of 1.00 mmΦ by a nitrogen reflow furnace at 230 ° C. Created 10
Observation of the shape after connection and measurement of the dimension in the vertical direction were performed on 0 samples. As a result, the shape after connection maintained a spherical shape, and no plated particles were deformed. The average dimension in the vertical direction after connection is 0.16 m
m ± 0.005 mm. In addition, it was connected with a nitrogen reflow furnace at 280 ° C. with a 1.00 mmΦ copper land. Observation of the shape after connection and measurement of the dimension in the vertical direction were performed on the prepared 100 samples. As a result, the shape after connection maintained a spherical shape, and no plated particles were deformed. In addition, the dimension average value in the vertical direction after connection is 0.1.
16 mm ± 0.006 mm.

[0068]

Comparative Example 1 A Sn / Pb eutectic solder ball having a diameter of 0.15 mm was purchased and 100 particles were observed with a scanning electron microscope. As a result, the volume average particle diameter was 0.16 mm. This solder ball was mounted on a 0.25 mmΦ copper land patterned on an FR-4 substrate. After applying the RMA type flux, mount the solder ball,
Connection was made with a nitrogen reflow furnace. Observation of the shape after connection and measurement of the dimension in the vertical direction were performed on the prepared 100 samples. As a result, there was no ball maintaining the spherical shape after the connection, and all of the ball spread on the copper land. In addition, the dimension average value in the vertical direction after connection is 0.03 mm ±
The spherical shape was hardly maintained at 0.003 mm.

[0069]

Comparative Example 2 A Sn / Pb eutectic solder ball having a diameter of 1.00 mm was purchased, and 100 particles were observed with a scanning electron microscope. As a result, the volume average particle diameter was 1.05 mm. This solder ball was mounted on a 1.0 mmΦ copper land patterned on an FR-4 substrate. After applying the RMA type flux, the solder balls were mounted and connected in a nitrogen reflow furnace at 230 ° C. Observation of the shape after connection and measurement of the dimension in the vertical direction were performed on the prepared 100 samples. As a result, the shape after connection maintained a spherical shape.
Vertical dimension after connection is 0.85mm ± 0.0
5 mm. However, when the connection was made even in a 280 ° C. nitrogen reflow furnace, there was no ball maintaining the spherical shape after the connection, and the ball was reduced to half and spread on the copper land. The average dimension in the vertical direction after connection is 0.55 m.
The spherical shape was hardly maintained at m ± 0.05 mm.

[0070]

EFFECTS OF THE INVENTION By using the plated particles according to the present invention, the disadvantages of metal particles for making an electrical connection, namely, that the material is expensive, that the standoff is accurately maintained, and that the connection between the semiconductor element and the electronic circuit board is stabilized. Is difficult to maintain, it is easy to peel off due to shock or vibration after connection, balls or bumps are easy to shatter when a load is applied to the semiconductor element at the time of soldering, lead in solder (tin-lead alloy) The semiconductor element is liable to malfunction due to the emitted α-rays,
It has improved that the solder (tin-lead alloy) itself is toxic to the human body, and has made it possible to achieve highly reliable electrical connection.

In addition, since the pre-plating process is only water washing, the conventional acid washing has an adverse effect on metal particle nuclei, and a nickel base treatment is not required. The connection reliability has improved, and the cost advantage of the mass production process has emerged.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01B 1/00 H01B 1/00 CG 1/22 1/22 AZ H01L 23/12 H01L 23/12 Q F term (reference) 4K018 BA02 BC22 BD10 4K023 AA17 AB28 AB33 AB38 AB40 CA09 4K024 AA07 AA21 AA24 AB04 BA01 BB09 BB28 BC08 5G301 DA03 DA06 DA13 DD01 DD08

Claims (8)

[Claims] 1. A multilayer plating layer ([m + 1] layer, [m + 2] layer, [m + 3] layer,...,...) Formed from a plating solution on a central core [m] alloy particle by a plating solution.
[M + n] layer), wherein the central core [m] alloy particles have a general formula of AgxCuy
[0.001 ≦ x ≦ 0.4, 0.6 ≦ y ≦ 0.999,
x + y = 1 (atomic ratio)] and Ag on the particle surface
The alloy particles have a region where the concentration is higher than the average Ag concentration of the particles, the content of oxygen is 0.0001 to 1.0% by weight, and the surface of the alloy particles has a fine uneven shape (the difference between the height of the protrusion and the recess is 1 μm or less) )
Wherein the plating layer has a plating thickness of 1 to 100 μm.
Wherein the outermost [m + n] layers are tin or tin alloy layers,
Plating particles exhibiting a plurality of absorption peak temperatures in differential scanning calorimetry and having a coating (tin-graded alloy coating) having different tin concentrations in tin or a tin alloy between the central core alloy particle and the multilayer plating layer . 2. The plating particles according to claim 1, wherein the plating solution is a Sn plating solution, the [m + 1] layer of the multilayer plating layer is a Cu / Ag / Sn layer, and the [m + 2] layer is A.
A plated particle, wherein the g / Sn layer, the [m + 3] layer is a Cu / Sn layer, and the outermost [m + 4] layer is a Sn layer. 3. The plating particles according to claim 1, wherein the plating solution is an Sn / Bi-based plating solution, the [m + 1] layer of the multilayer plating layer is a Cu / Ag / Sn layer, and [m + 2].
The layer was an Ag / Sn layer, the [m + 3] layer was a Cu / Sn layer, [m
+4] layer is Sn layer, and the outermost [m + 5] layer is Sn / Bi
Plating particles characterized by being a layer. 4. The plating particles according to claim 1, wherein the plating solution is a Sn / Cu-based plating solution, the [m + 1] layer of the multilayer plating layer is a Cu / Ag / Sn layer, and [m + 2].
The layer was an Ag / Sn layer, the [m + 3] layer was a Cu / Sn layer, [m
+4] layer is Sn layer, and the outermost [m + 5] layer is Sn / Cu
Plating particles characterized by being a layer. 5. The plating particles according to claim 1, wherein the plating solution is a Sn / Ag-based plating solution, the [m + 1] layer of the multilayer plating layer is a Cu / Ag / Sn layer, and [m + 2].
The layer was an Ag / Sn layer, the [m + 3] layer was a Cu / Sn layer, [m
+4] layer is Sn layer, and the outermost [m + 5] layer is Sn / Ag
Plating particles characterized by being a layer. 6. The plating particles according to claim 1, wherein the plating solution is a Sn / Zn-based plating solution, the [m + 1] layer of the multilayer plating layer is a Cu / Ag / Zn layer, and [m + 2].
Layer is Cu / Ag / Sn layer, [m + 3] layer is Ag / Sn
Layer, [m + 4] layer is Cu / Sn layer, [m + 5] layer is Sn
The plated particles, wherein the [m + 6] layer as the outermost layer is a Sn / Zn layer. 7. The method for producing plated particles according to claim 1, wherein before the plating treatment with the plating solution,
A method for producing plated particles, comprising intermittently applying a current at a cathode current density of 0.01 to 30 A / dm ² and performing electroplating without performing a pretreatment of an acid treatment and a base treatment for preventing diffusion. 8. The method for producing plated particles according to claim 1, wherein gold, nickel, palladium, chromium, indium, antimony, aluminum, germanium and the like are added as a trace element in the plating solution in an amount of 5 wt% or less.
A method for producing plated particles, characterized by adding one or more of silicon, beryllium, tungsten, molybdenum, manganese, tantalum, titanium, neodymium, magnesium, and cobalt.