WO2010116971A1 - Solder particles and method for producing same, and solder paste and method for producing same - Google Patents

Abstract

Conventional solder pastes contain an activator containing a halogen for the purpose of increasing the wettability to an object to be soldered. Halogens, however, are highly toxic to the human body and cause the formation of dioxin. Consequently, there has been demand for a solder paste that is free from halogens or has a significantly reduced halogen content. In order to meet the demand, a solder paste is produced by mixing solder particles, on the surfaces of which an extremely small amount of a halogen is present, into a flux composition which does not contain an activator and is composed of an adhesive, a solvent, a thixotropic agent and the like. Although the amount of halogen contained in this solder paste is extremely small, the wettability to an object to be soldered is practically sufficient.

Description

Solder particles and manufacturing method thereof, and solder paste and manufacturing method thereof

The present invention is an invention relating to a halogen-free solder paste in which the activator halogen added to the solder paste is extremely reduced in order to improve the wettability with the bonding object when soldering.

With the recent miniaturization and high density of electronic components, solder paste that can be mounted easily and with high precision is widely recognized as an indispensable technology in the electronic device assembly process.

Solder paste is made by melting a solder ingot containing Sn as a main component and making it into a powder having a particle size of several to several tens of μm by a method such as atomization or centrifugation, and after classification, from pine resin component, thixotropic agent, solvent, etc. It is made by mixing the flux.

The surface of the Sn fine particle that becomes the base of the solder is covered with an oxide film. If the oxide remains at the time of solder formation, contact resistance is generated, and if it is present at the interface with the substrate metal, it causes peeling. Therefore, in order to form a solder that melts the solder paste by heating and maintains a uniform and high wettability to the object to be bonded, the oxide film is removed from the surface of the solder fine particles by a reduction reaction or a dissolution reaction at the stage of the heat treatment. There is a need. For these reasons, the solder paste contains a rosin component and an activator in the flux as a material for removing the oxide film. Among them, the activator mainly composed of halogen is a particularly important component for causing such a reaction to proceed.

For example, Patent Documents 1 and 2 disclose that halogen is used as an activator. In particular, Patent Document 1 discloses that a specific organic halogen compound is effective as a flux component that does not decompose during storage but decomposes under reflow conditions to improve the wettability of solder.

These organic halogen compounds are added at a ratio of 0.01 wt% to 2 wt% with respect to the solder paste.

Japanese Patent Laid-Open No. 10-175093 JP-A-10-128573

In recent years, global interest in environmental pollution has increased, and high safety has been demanded for products used around us. One example is dioxin. Dioxin is known to be extremely toxic to the human body and is one of the environmental problems. Dioxins are a kind of halogen compounds and may be generated when they are burned.

Solder mounting on an electronic board is performed by applying a solder paste containing a halogen component as described above to the electronic board and heating. In this way, halogens are present in the substrate using the solder paste, and when these are incinerated, dioxins are generated and the environment is deteriorated. From such a viewpoint, in recent years, it has been required to develop a solder paste (halogen-free solder paste) that does not contain halogen or has a very low content.

However, when the halogen content is reduced by a simple method such as reducing the halogen-containing flux amount in the solder paste, the characteristics of the solder paste are remarkably reduced, for example, the wettability of the solder is reduced. Therefore, there is a need for technological development that can achieve both halogen-free and characteristic maintenance.

The present invention has been conceived in view of the above-mentioned problems, and in order to prepare a solder paste containing only the minimum necessary halogen, an extremely small amount of halogen necessary for removing the oxide film on the surface of the fine particles is obtained. The present invention provides a solder paste prepared by causing seeds to exist on the surface of solder particles and blending such particles with an organic component such as a flux containing no halogen.

Specifically, the present invention provides a solder paste comprising a solder powder having a halide on its surface and a flux.

The present invention also provides:
This is a solder particle characterized in that the surface is coated with a halide. In the XPS spectrum obtained by X-ray photoelectron spectroscopic analysis after an acceleration voltage of 10 kV, a current of 10 mA, and Ar etching for 3 seconds, it depends on the oxide. Provided is a solder particle characterized by having a metal / oxide ratio of 1 or more as a relative ratio of peak intensity to metal-dependent peak intensity, a solder paste containing the solder particle, and a method for producing the solder paste. .

The solder paste of the present invention is obtained by mixing a solder powder in which a halogen compound is present on the surface to be an oxide film and a flux, and the oxide film on the solder surface can be sufficiently removed with a small amount of the halogen compound. . In the present invention, the amount of the halogen compound is only 200 ppm or less with respect to the solder powder, and a solder paste having almost no halogen compound (halogen-free) is provided. Therefore, the solder paste of the present invention has an effect that the wettability to the object to be bonded is good, the toxicity to the human body is low, and the generation of dioxins is very small.

It is a graph which shows the measurement result of the amount of halogen contained in the residue after a heating of the solder paste processed from the solder particle processed with various density | concentration, and a halogen-free flux. It is a photograph which shows the mounting result to a board | substrate. It is a graph which shows the XPS measurement result of the raw material particle | grains and the particle | grains which processed by the density | concentration of 750 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 3000 ppm, 5000 ppm. It is the graph which put together only the thing of an etching process in FIG. It is a graph which shows the measurement result of the amount of halogen contained in the residue after a heating of the solder paste processed from the solder particle processed with various density | concentration, and a halogen-free flux. It is a photograph which shows the mounting result to an electronic substrate. It is a graph which shows the evaluation result of the tin by XPS of unused raw material particle | grains Fig.6 (a) (upper stage) and the processed particle | grains collect | recovered by soldering paste FIG.6 (b) (lower stage). It is a surface photograph of solder particles. It is a photograph which shows the mounting result to an electronic substrate.

The solder paste of the present invention comprises a solder powder with an activator and a flux composition. The solder powder is a binary, ternary, or quaternary alloy made of elements such as Ag, Cu, Bi, and Zn based on Sn. In addition, you may add another element and a trace amount addition element to an alloy.

Solder powder is obtained by melting ingots of these alloys and pulverizing them into a size of several μm to several tens of μm by a method such as an atomizing method or a centrifugal separation method.

As the activator, an organic acid having a halogen element such as bromine or chlorine, an amine hydrohalide, or an organic halogen compound can be used.

The flux composition can contain an adhesive, a solvent, a thixotropic agent, and the like as components. As the adhesive, rosin or synthetic resin can be suitably used. As the rosin, rosins such as natural rosin, polymerized rosin, and modified rosin can be used. As the synthetic resin, polyester, polyurethane, acrylic resin, or the like can be used.

As the solvent, alcohol, ether, ester, and aromatic solvents can be suitably used. Specifically, butanol, butyl cellosolve, pendyl alcohol, ethyl cellosolve, butyl carbitol, xylene, glycol and the like can be used alone or in combination.

As the thixotropic agent, silica particles, kaolin particles, hydrogenated castor oil, amide compounds, and the like can be suitably used. A surfactant may be added.

In order to make the activator present on the surface of the solder powder, a halogen compound is dissolved in a solvent, and the solder powder is immersed therein. The immersion time is preferably 3 days or more, and more preferably 10 days or more. By this immersion treatment, the activator is adsorbed on the surface of the solder. In addition, the time to be immersed can be shortened by applying heat in the middle. The solder powder after immersion is pulled up from the solvent and dried. The halide that can be used in the present invention is not only one that uses one element selected from the halogen elements F, Cl, Br, and I, but also one or more that uses a plurality of halogen elements from these elements. Different types of halogen compounds may be used.

The solder powder having the halogen compound adsorbed on the surface is mixed with the flux composition and dispersed with a planetary mixer. This is because the solder is soft as a metal, so that the powder is slowly dispersed so that the powder is not crushed.

Also, as another form, it is possible to obtain a solder powder in which halogen is adsorbed on the surface by washing the solder paste already produced. The solder paste containing halogen often changes with time, and is stored in a container in a prescribed amount in a low-temperature dark place. Therefore, after opening and using once, if there is a remainder, it is discarded as it is.

In such a waste solder paste, since the solder powder is immersed in a flux having a concentration of about 1 wt% of halogen for a long period of time, halogen is adsorbed on the surface of the solder powder.

こ の This waste solder paste is washed with an organic solvent and separated into organic substances and solder powder in the paste. The organic solvent that can be used is not particularly limited. For example, benzene, toluene, hexane, cyclohexane, diethyl ether, chloroform, ethyl acetate, methyl acetate, methylene chloride, tetrachloroethylene, petroleum ether, thinner, gasoline, light oil, tetrahydrofuran, acetone, Acetonitrile, dimethylformamide, dimethyl sulfoxide, methanol, ethanol, propanol, acetic acid, formic acid, oleic acid, stearic acid, isopropyl alcohol, hexyl glycol, hexyl diglycol, 2 ethylhexyl glycol, 2 ethylhexyl diglycol, phenyl glycol, phenyl diglycol, Benzyl glycol, benzyl diglycol, methyl propylene glycol, methyl propylene diglycol, methyl Propylene glycol, propylpropylene glycol, propylpropylene glycol, butylpropylene glycol, butylpropylene glycol, phenylpropylene glycol, dimethyl glycol, dimethyldiglycol, dimethyltriglycol, diethyldiglycol, dibutyldiglycol, dimethylpropylenediglycol, Examples include terpineol.

廃 Put the waste solder paste into these solvents while stirring. In this case, it is preferable to stir with a relatively soft material fin such as a rubber fin. This is because the solder powder is crushed if it is a hard metal fin. Further, the stirring may be performed by adding ultrasonic waves to the mixed solution. Organic components adhering to the surface can be washed off more effectively than physical stirring.

Next, the mixed solution is separated into solder powder, insoluble material, soluble material and solvent. Specifically, the mixed solution is allowed to stand to precipitate the solder powder. And the settled solder powder and a supernatant component are isolate | separated. The supernatant component is a state in which an insoluble substance floats in a solvent in which a soluble substance is dissolved.

The mixing step and the separation step may be performed a plurality of times. This is because the flux component is adsorbed on the surface of the alloy particles of the solder powder, and may not be washed out once.

In this example, the surface state of the solder was determined by analyzing the Sn 3d orbit by a combination of sputter etching with argon and XPS (X-ray photoelectron spectroscopy: X-ray photoelectron spectroscopy). Both sputtering with argon and measurement of XPS were performed under conditions of 10 KV and 10 mA.

Further, the amount of halogen adhering to the surface of the solder particles in the treatment solution and treatment was measured using a potentiometric automatic titrator. The concentration of the treatment solution was calculated from the obtained halogen amount.

Example 1
A nonionic halogen activator (tris (2.3-dibromopropyl) isocyanurate) was dissolved in hexyl diglycol, 30 g of Sn3.0Ag0.5Cu particles were added, and the mixture was allowed to stand for 10 days. The treatment temperature was room temperature or 35 ° C. The nonionic halogen activator concentration was adjusted to 750 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, 4000 ppm, 5000 ppm, 7500 ppm and 15000 ppm with respect to Sn3.0Ag0.5Cu particles. After treatment, the particles were thoroughly washed with toluene and dried. “Sn3.0Ag0.5Cu” is a solder having a composition of 3.0% Ag and 0.5% Cu in the molar ratio, with the remainder being Sn.

Fig. 1 shows the measurement results of the amount of halogen contained in the post-heating residue of solder paste processed from various concentrations and solder paste prepared from a halogen-free flux. The horizontal axis represents the halogen-containing nonionic active agent concentration (ppm) in the treatment solution, and the vertical axis represents the amount of halogen (ppm) added on the surface of the solder particles by the treatment. Since a halogen-free flux is used as the activator, the detected amount of halogen suggests the amount of halogen added on the surface of the solder particles by the treatment.

When treated with a nonionic halogen activator solution having a concentration of 750 ppm to 1500 ppm, the solder particle surface contained about 30 to 50 ppm of halogen. On the other hand, when treated with a nonionic halogen activator solution having a concentration of 2000 ppm, the amount of halogen contained in the solder particles increased to about 150 to 160 ppm. Even when the treatment was performed at a concentration higher than that, the amount of halogen present on the surface of the solder particles did not change and was in an equilibrium state in the range of 150 to 200 ppm.

FIG. 2 shows the mounting results on an electronic substrate using untreated raw material particles, particles treated with a halogen-containing nonionic activator solution having a concentration of 750 ppm and 3000 ppm, and a solder paste prepared using a halogen-free flux. Show.

Fig. 2 (a) shows the case of raw material particles, Fig. 2 (b) shows the case of treatment at 750 ppm, and Fig. 2 (c) shows the case of treatment at 3000 ppm. When raw material particles and particles treated with 750 ppm (solder particles contain about 30 to 50 ppm of halogen) are dissolved by heating in the circled circles (also indicated by arrows). Solder balls that flowed out were observed.

On the other hand, in the case of particles treated at 3000 ppm (the solder particles themselves contain about 150 to 200 ppm of halogen), the molten solder was completely integrated and no solder balls were present. If the wettability is poor, it is considered that the molten solder cannot be integrated and a lot of solder balls are generated. Therefore, it is clear that the pace using particles treated with halogen of 3000 ppm is higher in characteristics such as wettability than a normal solder paste and can effectively act as a solder paste.

However, it can be seen that even when the treatment is performed at 750 ppm, the generation of solder balls is reduced as compared with the case of raw material particles. Therefore, particles treated with a nonionic halogen activator solution having a concentration of 750 ppm also exhibit the effects of the present invention. Table 1 shows numbers obtained by counting the number of solder balls generated in FIGS. 2 (a) to 2 (c).

FIG. 3 shows the results of XPS measurement of untreated raw material particles (a) and particles processed at concentrations of 750 ppm (b), 1000 ppm (c), 1500 ppm (d), 2000 ppm (e), and 5000 ppm (f). Indicates. The horizontal axis represents binding energy (eV), and the vertical axis represents strength. Etching was performed using Ar gas, and etching was performed for 3 seconds per trial. That is, as the number of times of etching increases, information in the depth direction is obtained from the particle surface to the inside of the particle. The applied voltage and current for etching were 10 KV and 10 mA as described above. 3A to 3F, trials are performed from 0 to 7 times, and the profiles of the trials are vertically arranged in each graph. FIG. 4 shows a summary of only one-time etching profiles in FIGS. 3A to 3F.

Referring to FIG. 3A, when etching is not performed with untreated raw material particles, only an oxide peak (energy band of 486 to 488 eV) is observed, and the oxide peak increases as the number of etching increases. The metal peak (energy band of 484 to 485.7 eV) increased and decreased. That is, the raw material particle surface is covered with oxide.

On the other hand, when the treatment was performed at 750 ppm to 5000 ppm (FIGS. 3B to 3F), a metal peak was observed without etching, and the intensity increased with an increase in the concentration of the solution used for the treatment. A tendency to do so was observed. Referring to FIG. 4, in the case of these samples, only the metal peak was clearly observed in one etching process. That is, when the treatment is performed with a nonionic halogen activator solution having a concentration of 750 ppm to 5000 ppm, if argon sputter etching is performed once at 10 KV and 10 mA for 3 minutes and the metal / oxide ratio exceeds 1. It can be seen that there is an effect of forming halogen on the surface, and the thickness of the oxide film of the solder particles is reduced.

Considering the increasing tendency of the halogen amount due to the treatment, it is considered that the flux component is consumed mainly to reduce the thickness of the oxide film up to 1000 ppm. That is, since halogen is consumed in the oxide film removal reaction, it cannot be present on the particle surface.

On the other hand, when the concentration is 1500 ppm or more (FIGS. 3D to 3F), halogens that have not participated in the oxide film removal reaction are present on the particle surface. It is considered that the amount of the oxide film is reduced by this treatment and is made constant by an amount capable of maintaining a stable state. Therefore, it can be inferred that the surface halogen amount is also constant.

The peak positions of tin halide and tin oxide are very close. Therefore, the reason why the peak intensity of metallic tin is reduced at a concentration of 2000 ppm or more is presumed that the peak intensity of metallic tin is relatively reduced because the peak of halide is added to the peak of oxide. I can do it.

Next, the solder particles containing 180 ppm of halogen obtained by the above treatment were further washed twice with an organic solvent (toluene, acetone, methanol, hexane, tetrahydrofuran). Table 2 shows the results of measuring the amount of halogen contained in the residue after heating, in which a solder paste was prepared from the rewashed particles and the halogen-free flux.

When the Br-containing flux is present on the surface of the solder particle as a surface adsorbing species, when immersed in an organic solvent, an equilibrium state is established between the particle surface and the solvent, and depending on the state, a part of the Br-containing flux is dissolved, The Br concentration on the particle surface decreases. Since the Br-containing flux used in this example is soluble in the above five types of organic solvents, if it is present as a surface adsorbed species, its concentration should be reduced when re-washing twice. However, as is apparent from the result of rewashing with toluene, the concentration hardly decreases. That is, the sample synthesized in this example shows that the solder particle surface and Br have a stronger bonding state than simple surface adsorption.

From the above results, it was revealed that when halogen was added to the metal particle surface using a low-concentration halogen-containing nonionic activator solution, the treated particles exhibited properties as halogen-free solder. Here, the term “halogen-free” refers to a halogen-free solder specified by the IPC standard, and has a halogen concentration of 900 ppm or less. As described above, the solder particles of the present invention have a halogen concentration of 900 ppm.

(Example 2)
A halogen-containing ionic activator (diphenylguanidine hydrobromide) was dissolved in hexyl diglycol, 30 g of Sn3.0Ag0.5Cu particles were added, and the mixture was allowed to stand for 10 days. The treatment temperature was room temperature or 35 ° C. The halogen-containing ionic activator concentration was adjusted to 2000 ppm, 3000 ppm, 4000 ppm, 5000 ppm and 15000 ppm with respect to Sn3.0Ag0.5Cu particles. After the treatment, the particles were thoroughly washed with toluene, dried and used for the subsequent analysis.

FIG. 5 shows the measurement results of the amount of halogen contained in the post-heating residue of solder paste processed from various concentrations and solder paste prepared from a halogen-free flux. The horizontal axis represents the halogen-containing nonionic active agent concentration (ppm) in the treatment solution, and the vertical axis represents the amount of halogen (ppm) added on the surface of the solder particles by the treatment. Since a halogen-free flux is used as the activator, the detected amount of halogen suggests the amount of halogen added on the surface of the solder particles by the treatment.

As the halogen-containing ionic activator concentration in the treatment liquid increased, the amount of halogen adhering to the surface of the solder particles increased. However, the proportion of the amount of halogen adhering to the particle surface was moderate as compared with the case of using a halogen-containing nonionic activator. Under the condition of 15000 ppm at a concentration equal to or higher than that of the saturated solution, the amount of halogen adhering to the solder particle surface was about 140 ppm. In this case, since the treatment solution is saturated, the activator adheres to the solder particles, and sufficient cleaning is required to take out only the solder particles.

FIG. 6 shows the result of mounting on an electronic substrate using particles treated with a halogen-containing ionic activator solution having concentrations of 750 ppm and 15000 ppm and a solder paste prepared using a halogen-free flux. 6A shows the case of 750 ppm, and FIG. 6B shows the case of 15000 ppm. The primary particles are those shown in FIG. The portion where the solder ball is observed is indicated by an arrow as in the case of the first embodiment. When the treatment was performed under the condition of 15000 ppm, no solder balls were observed, and it became clear that the wettability, which is an essential condition for the solder paste, was satisfactory.

From the above results, it has been clarified that when halogen is added to the surface of metal particles using a low-concentration halogen-containing ionic activator solution, the treated particles exhibit characteristics as halogen-free solder. However, the reaction was slower than when a low-concentration halogen-containing nonionic activator solution was used.

(Example 3)
Next, an example in which solder particles recovered from an already synthesized solder paste are used will be described. In such a system, since it is a dense system, halogen species are adsorbed or remain as compounds on the surface of the metal particles. Therefore, in accordance with a normal solder paste preparation method, a solder paste was prepared and washed with a solvent to recover metal particles.

FIG. 7 shows the evaluation results of tin by XPS of unused raw material particle FIG. 7 (a) (upper) and treated particles recovered by solder paste FIG. 7 (b) (lower). The vertical axis represents the peak intensity of tin metal (black circle) and tin oxide (white circle), and the horizontal axis represents the number of etchings. Etching was performed using Ar gas, and etching was performed for 5 seconds per trial. That is, as the number of times of etching increases, information in the depth direction is obtained from the particle surface to the inside of the particle.

In the case of the raw material particles shown in FIG. 7 (a), the outermost surface that was not etched was an oxide, and as the number of etchings increased, the oxide strength decreased and the metal strength increased. In addition, compared with the case where the number of etching trials is 0, the peak intensity of the oxide is increased when the number of trials is 1 because the surface adsorbed species (gas etc.) are removed by etching. . In addition, the peak of the oxide species remains even when the number of etching trials is increased because the particles are spherical and an oxide layer is always present on the side even if etching is performed from the surface.

On the other hand, in the case of the treated particles of FIG. 7B, a metal peak was already observed before the etching, and the metal was exposed on the surface after one or two etching trials. Since the adsorbed species are present on the particle surface due to the treatment, the peak intensity when etching is not performed is lower than that of the raw material. Further, since the peak intensity is remarkably increased by one etching, it can be seen that the amount of adsorbed species is small and exists only on the surface.

Next, a solder paste was prepared using the treated particles and a flux not containing halogen, and heated to measure the amount of halogen contained in the residue (that is, the amount of halogen present in the treated particles). As a result, the amount of halogen (bromine) contained in the heated residue was in the range of 130 ppm to 180 ppm. That is, by the treatment, about 130 ppm of halogen could be present on the particle surface.

The abundance of 130 ppm halogen present on the particle surface will be described. The above solder particles have an average diameter of 32 μm. The surface area S and volume V of this single solder particle are represented by 4πr ² (cm ² ) and 4 / 3πr ³ (cm ³ ), respectively, where r is the radius. The specific gravity of Sn3.0Ag0.5Cu is ρ (g / cm ³ ), and the weight per mole is ξ (g / mol).

Since the weight per solder particle is ρV (g), there are (ρV) / ξ (mol) atoms in one solder particle. Of these, assuming that 130 ppm (0.0013 at%) is halogen (bromine), one solder particle contains (ρV × 0.00013) / ξ (mol) of halogen atoms. Since the halogen atoms are present on the surface of the solder particles, the number of halogen atoms per unit area can be obtained as (ρV × 0.00013) / (ξS) (mol).

Here, when r = 1.6 × 10 ⁻³ (cm), ρ = 7.359 (g / cm ³ ), and ξ = 117.4097 (g / mol) are entered, 130 ppm of halogen exists. This means that there are 0.435 × 10 ⁻⁸ (mol / cm ² ) halogen atoms per unit area. Considering that the amount of halogen on the surface of the solder particles does not exceed 200 ppm and that the size of the solder particles actually varies, the surface of the solder particles of the present invention is 1.0 in terms of halogen element. It can be said that a halide of x10 ⁻⁹ to 1.0 × 10 ⁻⁸ (mol / cm ² ) exists.

Also, the surface of the solder particles of the present invention is not uniform and has irregularities. In FIG. 8, the photograph of the solder particle of this invention by an electron microscope is shown. The photograph is a 1800 × photograph, and the length of the white line is 10 μm. There are irregularities on the surface of the particles. This unevenness is a phenomenon called “sink”, and halide is hardly present in this portion. Therefore, the halogen compound determined above may exist not only on the surface of the solder particles but also as a second layer on the halogen compound on the first layer of the surface.

Fig. 9 shows the state of mounting on the electronic board using the solder paste created using this method. The solder was mounted on the substrate from the solder paste prepared using the treated particles and the halogen-free flux, and no solder balls were observed. The primary particles are those shown in FIG. That is, it was found that characteristics such as wettability were improved as compared with the conventional product.

Here, considering the composition and specific gravity of the particles used, the crystal lattice spacing, etc., the ratio of tin in the first layer of the particle surface to halogen (bromine) present on the surface is Sn: Br = 1: 2 to 3 (The ratio varies depending on the crystal orientation of the oxide phase). From the XPS results, it is considered that the function was developed even with such a small amount of halogen since the thickness of the oxide layer was reduced by this treatment.

From the above results, it has been clarified that the solder particles recovered by washing the solder paste prepared according to the normal production method exhibit the characteristics as the halogen-free solder of the present invention.

The present invention can be used not only for halogen-free solder paste but also for use when recycling the solder paste.

Claims (12)

1. This is a solder particle characterized in that the surface is coated with a halide. In the XPS spectrum obtained by X-ray photoelectron spectroscopic analysis after an acceleration voltage of 10 kV, a current of 10 mA, and Ar etching for 3 seconds, it depends on the oxide. Solder particles characterized in that the metal / oxide is 1 or more as a relative ratio between the peak intensity and the metal-dependent peak intensity.
2. The solder particles are an alloy containing Sn, and in the XPS spectrum obtained by X-ray photoelectron spectroscopy after Ar etching for 3 seconds with an acceleration voltage of 10 kV, a current of 10 mA, the oxide-dependent 486 of Sn 3d orbital. The solder according to claim 1, characterized in that Sn metal / Sn oxide is 1 or more as a relative ratio of the peak intensity existing at 488 to 488 eV and the peak intensity existing at 484 to 485.7 eV depending on metal Sn. particle.
3. 3. The solder particles according to claim 1, wherein the solder particles have an average particle size of 3 to 200 μm, and the halide is 10 ppm or more and 900 ppm or less with respect to the solder powder.
4. 3. The solder particles according to claim 1, wherein the solder particles have an average particle size of 25 to 35 μm, and the halide is 30 ppm or more and 200 ppm or less with respect to the solder powder.
5. 3. The solder particle according to claim 1, wherein the halide is present in one to four layers in the form of Sn halide on the surface of the solder powder.
6. The solder particles according to claim 5, wherein the halide is one or two layers in the form of Sn halide on the surface of the solder powder.
7. ^{3. The} halide according to claim 1, wherein the halide is present on the surface of the solder powder in an amount of 1 × 10 ⁻⁹ to 1 × 10 ⁻⁸ mol / cm ^{2 in} terms of a halogen element. Solder particles.
8. The halogen element of the halide is composed of one element selected from F, Cl, Br, and I, or a combination of two or more elements. Solder particles.
9. The method for producing solder particles according to any one of claims 1 to 8, further comprising a step of treating with a nonionic halogen activator.
10. A solder paste comprising the solder particles according to any one of claims 1 to 7 and a flux.
11. The solder paste according to claim 10, wherein the halogen content is 900 ppm or less.
12. A method for producing a solder paste, comprising a step of obtaining the solder particles according to any one of claims 1 to 8 and a step of mixing and dispersing a flux in the solder particles.

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