JP5830265B2 - Method for producing dispersion-stable tin fine particles and method for producing tin ink using the same - Google Patents

Description

  The present invention relates to a method for producing dispersion-stable tin fine particles and a tin ink using the same. Specifically, the present invention relates to an ink-jet tin ink that includes tin fine particles having an average particle diameter of 1 to 100 nm and has dispersion stability that can be applied by an ink-jet head.

  As a connecting metal material used for flip mounting, a fine bump forming method using a microball having a composition containing tin as a main component is mainly used. In addition, a bump forming method using a printing technique such as a screen printing method is also known. These methods have high characteristics in terms of bump formation productivity, but in the future, it is desired that the bump pitch be narrow in order to reduce the size of electronic members and increase the mounting density.

  Recently, bumps in the microball method or screen printing method have a limit of a bump pitch of less than 80 μm, and it is technically difficult to narrow the pitch further. In addition to this, there are cases in which, for example, studies on narrowing the pitch are being carried out using electroless plating, but the method using electroless plating increases the number of manufacturing steps and increases the lead time, and the cost burden. There is a problem that there are many.

  Therefore, in the future, a bump forming technique capable of handling a narrow pitch and using a simple process is required, and the expectation of a process using a printing technique as a method to meet this demand is increasing. By using the printing technique, it is possible to produce in a simple and simple process of accurately applying the ink to the substrate, reflowing, and washing. As the printing method, the screen printing method and the ink jet printing method are attracting attention. When these printing techniques are used, it is important to select an ink that can be adapted to the printing process (coating) and the reflow process (firing).

  That is, since the ink needs to be finely coated, a form in which nano-sized tin particles are dispersed is desired. When the particles are nano-sized, not only fine pitches can be drawn, but also by optimizing the solvent, the particles float in the solvent by Brownian motion and exhibit a fluid ink form. Moreover, since the property that the melting point of the metal is lowered can be expected when the particle size is reduced to the nano-order level, if there is material processing that requires a firing process, the firing process itself can be expected to be lowered.

  However, in general, the nano metal fine particles have a large specific surface area and high surface activity, so that the metal fine particles are not stable particles as they are, and an oxide film or an organic substance (protective agent) is not present on the particle surface. It is stabilized in the state of powder formed as a protective layer. Therefore, in the reflow process in which nano metal fine particles are converted into ink and fired after coating the substrate, it is necessary to take a method for removing the surface protective layer during firing.

  When the protective agent for the metal fine particles is an organic component, there is a problem that if the firing conditions are not optimized, the organic matter on the metal surface protective layer is not completely decomposed and lost and the resin remains in and near the metal fine particles. That is, it is a problem to reduce the resin residue as much as possible in a solder material for tin-based metal bonding that requires a firing process. So far, as a method for producing tin fine particles, for example, Patent Document 1 discloses a method suitably using PVP (polyvinylpyrrolidone) or PVA (polyvinyl alcohol) as a protective agent for tin fine particles. However, the invention described in Patent Document 1 is a method for producing fine tin particles as a black material used for a black matrix material or the like of a liquid crystal display, and does not relate to a metal material for connection used for flip mounting. The residual organic matter after baking is not studied. In addition, sufficient studies have not been made on dispersion as ink.

  On the other hand, Patent Document 2 relates to an invention of an ink-like solder composition containing tin nanoparticles (tin fine particles) having an average particle diameter of 2 to 100 nm and suitable for ink jet printing. In Patent Document 2, a binder for ink preparation is disclosed. It describes that hydrogenated rosin is used as a component (flux component). However, as for the protective agent for tin fine particles, it is preferable to use a C8-C14 alkylamine or a compound having a hydroxyl group as an amine compound having an amino group at the terminal, and to provide a coating agent molecular layer. The decomposability during heating is not taken into consideration. An ink containing hydrogenated rosin (molecular weight 304) as a flux component is prepared, but this is only mixed in the ink of a nonpolar solvent, and the tin fine particles themselves are directly added from the synthesis stage. The protective layer is not formed and stably dispersed in a polar solvent.

  In addition, for example, in Patent Document 3, the surface of a metal nanoparticle such as gold, silver, platinum or the like having an average particle diameter of 1 to 100 nm is coated with an alkylamine, and a dispersion liquid containing this is intended by an inkjet method. A method of forming a metal nanoparticle sintered body layer having high conductivity on a substrate by applying it in a fine pattern and baking it is known.

JP 2005-281828 A JP 2009-6337 A JP 2009-70727 A

  An ink containing nano-order metal tin fine particles can be printed by ejecting fine droplets of picoliter or femtoliter order with a printing apparatus such as an ink jet apparatus. After printing, a step of firing to bond the tin particles is required, but since the melting point of metallic tin is about 230 ° C, the firing temperature is usually around 260 ° C, at most 300 ° C or less. It is desirable to do. However, in the firing process, if most of the organic components on the metal surface and inside are not decomposed and lost, there is a problem that the resin remains even after the next cleaning process. Therefore, the design of an ink that reduces the organic matter on the particle surface after firing the ink or the design of an ink that can remove the organic matter has been an issue.

  In addition, when rosin is used as an aqueous dispersant for fine metal particles, rosin is a resin that is insoluble in water. Therefore, in order to impart water-soluble properties, it is processed into a derivative having a structure such as sodium salt or potassium salt. Therefore, it is difficult to use the rosin itself as a dispersant for water-based ink. On the other hand, Patent Document 2 describes the necessity of inking with a nonpolar solvent because the surface of tin particles undergoes oxidation when the metal is melted in water-based tin particle inks. Polarization of the surface of tin particles, which is dispersed and stabilized by using, has become a technical problem.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a method for producing tin fine particles that are stable in dispersion in a polar solvent, and a tin ink using the same. Specifically, the present invention provides a tin ink in which unnecessary organic components are eliminated as much as possible by allowing rosin, which is an organic substance, to coexist in the stage of synthesizing tin fine particles.

  In order to solve such a problem, the present inventors investigated the influence of an organic binder and a solvent on the tin fine particles forming the tin ink from the stage of synthesizing the tin fine particles, and found the optimum as an ink-jet ink. The composition design was performed. As a result, it was found that better dispersibility and thermal decomposition characteristics can be obtained by the synthesis method in which the surface of the tin fine particles is directly protected with rosin in the ink, and the present invention has been completed.

  That is, the gist of the present invention is as follows. After rosin dissolved in alcohol coexists in an aqueous tin chloride solution to form a suspension, the suspension is reduced and coated with rosin. A method for producing tin fine particles, wherein fine particles are precipitated.

  In addition, the present invention is an ink-jet tin ink, wherein a viscosity at 23 ° C. is adjusted to 2 to 1000 mPa · s after the reduction treatment liquid in which the tin fine particles are deposited is replaced with a polar solvent.

  In the method for producing tin fine particles of the present invention, preferably, the rosin is a solid having a softening point of 120 to 160 ° C., insoluble in water, and soluble in methanol. Moreover, in the tin ink for inkjet of the present invention, it is preferable that the average particle diameter of the tin fine particles contained in the tin ink is 1 to 100 nm.

  According to the present invention, the organic substance on the surface of tin fine particles having an average particle diameter of 1 to 100 nm can be made only of rosin. In addition, tin fine particles obtained by synthesis can be dispersed in a polar solvent such as water, so that stable discharge by an electrostatic ink jet head is possible. In particular, in the tin ink of the present invention, by using rosin as a protective agent for tin particles, the thermal decomposability can be improved compared to conventional PVP (polyvinylpyrrolidone) and the like, and it can be removed by a treatment such as washing. Can be easy.

FIG. 1 is a chart showing the results of thermogravimetry of tin fine particles used in Examples 1 and 3 and Comparative Example 2. FIG. 2 is a chart showing the thermogravimetric measurement results of the tin fine particles used in Examples 2, 4, and 5. FIG. 3 is a chart showing the thermogravimetric measurement results of the tin fine particles used in Comparative Example 1.

Hereinafter, the present invention will be described in detail.
First, in the method for producing tin fine particles of the present invention, a rosin dissolved in alcohol is allowed to coexist in an aqueous tin chloride solution to obtain a suspension. Among these, rosin is insoluble in water but soluble in methanol, and it is preferable to use a solid having a softening point of 120 to 160 ° C. Uses water-insoluble rosin instead of water-soluble rosin having hydrophilic properties in the tin fine particle synthesis stage, so that tin fine particles obtained after reductive synthesis can be dispersed not only in polar solvents such as methanol but also in water. Thus, for example, a tin ink suitable for an electrostatic ink jet apparatus can be obtained.

  Of these, methanol is most preferred as the alcohol. The slurry after precipitation of the tin fine particles is centrifuged (2500 rpm × 10 minutes) to separate the precipitate and the supernatant into two layers, the supernatant is removed, methanol is added to the precipitate, and the mixture is shaken. When observed after standing, in methanol, some of the aggregated particles are removed, and a stable dispersion is observed without sedimentation, but other solvents such as aliphatic alcohols other than methanol such as 1-octanol and isopropanol. In the case of ketones such as acetone, almost all tin fine particles are precipitated, and it is difficult to stabilize the tin fine particle slurry like methanol.

  As for the rosin, natural rosin can be used as it is if it is soluble in a polar solvent, and those processed into various derivatives can also be used. For example, modification with maleated rosin by conjugated double bond, hydrogenated rosin by hydrogenating double bond, esterified rosin by esterifying carboxylic acid, other metal salts, disproportionation, etc. Derivatives can be used. On the other hand, general-purpose polymerized rosin and purified rosin are not preferable because of poor solubility. A maleic acid-modified rosin derivative is particularly preferable in that it has excellent solubility in methanol.

  However, since the tin fine particle synthesis is a reaction system using water as a mother liquor, when rosin dissolved in methanol is added to water as the reaction mother liquor, the higher the rosin concentration in methanol, the easier it is for rosin to precipitate. Become. Therefore, the amount of rosin added is preferably about 3.0 to 6.5 wt% with respect to the theoretical amount of tin fine particles obtained by this reduction reaction. If it is less than this range, dispersion stability cannot be obtained, and if it is more than this range, rosin precipitates in the mother liquor of water, which is not preferable. The concentration of the rosin-methanol solution at this time is preferably in the range of 0.5 to 10 wt%. If it is lower than this range, a large amount of rosin-methanol solution must be added, and the solubility of a water-soluble reducing agent or the like present in the reaction solution is lowered. On the other hand, if it is higher than this range, rosin tends to precipitate when the rosin-methanol solution is added, which is not preferable.

  As for the tin chloride aqueous solution used when obtaining a suspension from rosin dissolved in alcohol as described above, tin chloride may be used in any form of anhydrous or hydrate, It is preferable that the density | concentration when melt | dissolving in is the range of 0.1-25 wt% with respect to water. The reaction solution was reduced, and the metal weight of tin when 100% of tin chloride was reduced was defined as the theoretical synthesis amount. The average particle size of the tin fine particles obtained by the reduction reaction using the rosin suspension of the present invention (measured by a particle size distribution meter by dynamic light scattering method) is in the range of 10 to 100 nm, but immediately after the reaction, a larger secondary Aggregated particles may be formed. To adjust the rosin suspension, the above tin chloride aqueous solution is added to the rosin-alcohol solution while stirring, and then the pH is adjusted to neutral to obtain a stable suspension without precipitates. .

Then, the obtained suspension is subjected to a reduction treatment to precipitate tin fine particles coated with rosin. A known solution can be used for this reduction treatment. Most preferably, sodium borohydride (NaBH ₄ ) is dissolved in water to prepare an aqueous solution of NaBH _{4 of} about 2.5 wt%. The rosin suspension is dropped and mixed with stirring at, for example, 300 rpm to precipitate tin particles. At this time, the dripped liquid is mixed with the NaBH ₄ aqueous solution, and at the same time, black-brown tin fine particles are deposited. It is preferable that the temperature at this time is 35-40 degreeC. The obtained reduction treatment liquid is a dispersion liquid in which black-brown tin fine particles are dispersed. In this state, the surface of the tin fine particles is coated with rosin, and since the rosin is poor in hydrophilicity, secondary aggregation occurs. If left as it is, tin fine particles will precipitate.

  Moreover, in this invention, the tin ink for inkjets suitable for an inkjet printing method can be obtained by substituting the reduction process liquid in which the tin fine particle precipitated by the above by a polar solvent. Here, the polar solvent is preferably a high boiling point solvent in view of ejection stability. For example, ethylene glycol (b.p 197.3 ° C.), propylene glycol (b.p 188.2 ° C.), diethylene glycol (b.p 244.3 ° C.), tetraethylene glycol (b.p 314 ° C.), 1-octanol (b. p195 ° C) and glycerin (b.p290 ° C) are suitable. A highly volatile solvent such as methanol is unsuitable because even if it is a polar solvent, the drying property is too fast, and it dries on the nozzle surface of the ink jet head, and the possibility of clogging due to adhesion of pigments increases. In addition, a specific polarity solvent having a low dielectric constant is not suitable for ejection by an electrostatic ink jet apparatus.

  And according to the above example, water of the reducing treatment solution, sodium borohydride and sodium borohydride, sodium chloride formed from unreacted tin chloride, other pH adjusters and other additives such as polar solvents Replace with. For example, the reduction treatment liquid is centrifuged to remove the supernatant, washed with acetone, and then replaced with methanol. After that, an appropriate amount of the above-mentioned solvent suitable for ink jet printing is arbitrarily added, mixed well, and then the evaporator. At the same time as removing methanol by reducing the pressure using a solvent, etc., an operation of substituting the above-mentioned solvent suitable for inkjet printing is performed.

  After substituting the reducing treatment liquid with a polar solvent, the viscosity at 23 ° C. is adjusted to 2 to 1000 mPa · s, preferably 10 to 50 mPa · s, to obtain an ink-jet tin ink. In order to make a viscosity into the said range, it can adjust by methods, such as using a polar solvent as a mixed solvent.

  As for the ink jet tin ink obtained by the present invention, an ink jet printing apparatus used for ink jet printing requires precision printing technology in a narrow region with a micro solder ball pitch of less than 80 μm, so that fine droplets can be ejected. It is desirable to use a simple electrostatic capacitance type ink jet printing apparatus. If necessary, the surface of the wafer on which the micro solder balls are formed can be subjected to a liquid repellent treatment. In ink jet printing, since the droplet is a micro droplet of several fl to several pl, the solvent volatilizes quickly. By firing after the solvent volatilization, the solder balls can be formed by thermally decomposing and removing the rosin on the surface of the tin fine particles. The firing temperature needs to be equal to or higher than the melting point of tin. However, when the temperature exceeds 500 ° C., energy costs are required, and therefore it is usually preferably 300 ° C. or lower. Moreover, after baking, you may make it remove a rosin residue using a well-known flux cleaning agent, an organic solvent with a high cleaning effect, etc.

  Hereinafter, based on an Example etc., this invention is demonstrated more concretely. In addition, unless otherwise indicated, a part represents a mass part and% represents mass%. The preparation and evaluation of the primary dispersion and the evaluation method of the ink-jet ink are as follows.

  About the protective agent used for particle | grain synthesis | combination, the solubility test with respect to each solvent of water and methanol was done as judgment of the propriety of a synthesis | combination. In the solubility test, the mass ratio of the protective agent and the solvent was mixed at 1: 1, and the state after mixing was visually observed. If the obtained result is soluble in water or methanol, it can be determined that tin particles can be synthesized.

  The particles in the synthesized solution after the particle synthesis were precipitated by centrifugation, washed with acetone, and tin fine particles obtained after drying were identified with tin using an X-ray diffractometer.

The particles in the synthetic solution after the particle synthesis are precipitated by centrifugation, washed with acetone, and the tin fine particle powder obtained after drying is obtained from TG-DTA (manufactured by Seiko Denshi Kogyo Co., SSC-5200). Then, thermogravimetry was performed. The measurement conditions were a temperature increase rate of 10 ° C./min and an upper limit temperature of 500 ° C. in an N ₂ gas atmosphere. At this time, [weight reduction amount wt% at 300 ° C./weight reduction amount wt% at 500 ° C. × 100] as an index of the degree of decomposition of the organic matter on the particle surface was defined as the organic matter decomposition rate% on the tin particle surface. It can be determined that the higher the decomposition rate, the better the decomposability of the organic matter. In addition, in FIG. 1, the chart figure of the thermogravimetry result of the tin microparticles | fine-particles obtained in Example 1, 3 and the comparative example 2 is shown. In FIG. 2, the chart figure of the thermogravimetric measurement result of the tin microparticles obtained in Examples 2, 4 and 5 is shown. In FIG. 3, the chart figure of the thermogravimetry result of the tin microparticles | fine-particles obtained by the comparative example 1 is shown.

  Regarding the dispersion stability in a polar solvent, the synthesized solution was precipitated by centrifugation, washed with acetone, and observed when methanol was added. At this time, when all particles were observed to be visually observed by centrifugation (3500 rpm × 1 minute), it was evaluated as dispersion stability (unsuitable). The dispersion stability (appropriate) was evaluated except that all particles did not settle.

  The inkjet ink was measured for viscosity at 23 ° C. using an E-type viscometer (cone plate type rotational viscometer; manufactured by Toki Sangyo Co., Ltd.). If the obtained result is 2 to 1000 mPa · s, it can be determined that it is suitable for discharge of an electrostatic patterning apparatus (inkjet printing method).

  Further, whether or not the tin fine particles dispersed in the ink are more suitable for the ink jet apparatus was evaluated by measuring the particle size distribution of the ink and using a 1 μm glass filter (Whatman syringe filter GMF-150 PORESIZE 1 μm).

  The average primary particle diameter (hydrodynamic diameter) of the tin particles in the ink is actually measured with a particle size analyzer (particle size distribution meter by dynamic light scattering method; FPAR-1000 manufactured by Otsuka Electronics Co., Ltd.) and obtained by the photon correlation method. It was obtained by the cumulant method using the autocorrelation function. Further, the average value (nm) and ± standard deviation of the scattering intensity indicating the particle size distribution of tin particles in the ink were obtained by analysis by the histogram method.

  The obtained ink was evaluated for ejection with an electrostatic patterning device (inkjet printing method). At this time, when the ink can be stably discharged from the nozzle of the electrostatic patterning device, the discharge property is good (◯), and when the ink cannot be stably discharged due to clogged ink, the discharge property is poor (× ).

In addition, the relationship between each component used in the Example etc. and the symbol shown in Table 1 is shown collectively below.
Rosin A: Arakawa Chemical Industries, Ltd. Trade name; 34
Rosin B: Product name manufactured by Arakawa Chemical Industries, Ltd .; 33
Rosin C: manufactured by Arakawa Chemical Industry Co., Ltd .; China polymerized rosin 140
Rosin D: manufactured by Arakawa Chemical Industry Co., Ltd .; trade name; Shiragiku Rosin PVP: manufactured by Tokyo Chemical Industry Co., Ltd .; Polyvinylpyrrolidone K-15
Dispersant A: Product name manufactured by CRODA JAPAN Co., Ltd .; Zephrim 3300-B

Example 1
To prepare the metal component liquid, 12.5 g of tin chloride (special grade reagent manufactured by Wako Pure Chemical Industries) and 6.25 g of sodium citrate (special grade chemical reagent manufactured by Wako Pure Chemical Industries) were dissolved in 375 g of pure water and 1% in methanol. Concentrated rosin (trade name Marquide No. 34, manufactured by Arakawa Chemical Industry Co., Ltd.) 0.25 g was added and stirred in an eggplant flask. The aqueous solution was adjusted to pH 7 with a 20% aqueous sodium hydroxide solution, and then silver nitrate (Wako Pure Chemical Industries) 0.05 g of reagent special grade) was added. Thereafter, a 2.5% sodium tetrahydroborate aqueous solution was put in another container, and the prepared metal component liquid was added while stirring at 300 rpm, followed by stirring for 1 hour.

  After stirring, the tin synthesis solution obtained by the reduction reaction is separated by centrifugation (rotation speed 3500 rpm, time 10 minutes) to remove the supernatant, and the remaining precipitated particles are mixed with acetone and then centrifuged again (rotation speed). The supernatant was removed and washed at 3500 rpm for 10 minutes. Methanol was added thereto, followed by centrifugation (rotation speed 3500 rpm, time 10 minutes). Further, ethylene glycol was added to the supernatant after centrifugation, and then methanol removal treatment and solvent substitution treatment were performed with an evaporator, and the solution passed through a 1 μm filter was collected as a dispersion of tin fine particles. The obtained tin fine particles had an organic matter decomposition rate at 300 ° C. of −15.71%.

(Example 2)
The rosin of Example 1 was sold under the trade name Marquide No. A dispersion of tin particles was prepared in the same manner as in Example 1 except that it was changed to 33 (Arakawa Chemical Industries). The obtained tin fine particles had an organic matter decomposition rate at 300 ° C. of −13.57%.

(Example 3)
A dispersion of tin particles was prepared in the same manner as in Example 1 except that the demethanol treatment and solvent replacement treatment in Example 1 were changed to glycerin.

Example 4
A dispersion of tin particles was prepared in the same manner as in Example 1 except that the demethanol treatment and solvent replacement treatment in Example 2 were changed to glycerin.

(Example 5)
The rosin of Example 1 was sold under the trade name Marquide No. A dispersion of tin particles was prepared in the same manner as in Example 1, except that the amount of glycerol was changed to 1/10 of the amount of glycerin in Example 4 by changing to 33 (manufactured by Arakawa Chemical Industries).

(Comparative Example 1)
To prepare the metal component solution, 12.5 g of tin chloride (special grade reagent manufactured by Wako Pure Chemical Industries) and 6.25 g of sodium citrate (special grade reagent manufactured by Wako Pure Chemical Industries) were dissolved in 375 g of pure water, and PVP (polyvinyl 0.25 g of Pyrrolidone Tokyo Chemical Industry Reagent K-15) was added and stirred in an eggplant flask. This aqueous solution was adjusted to pH 7 with 20% aqueous sodium hydroxide solution, and then silver nitrate (reagent special grade manufactured by Wako Pure Chemical Industries) was added. 05 g was added. Thereafter, a 2.5% sodium tetrahydroborate aqueous solution was put in another container, and the prepared metal component liquid was added while stirring at 300 rpm, followed by stirring for 1 hour.

  After stirring, the tin synthesis solution obtained by the reduction reaction is separated by centrifugation (rotation speed 3500 rpm, time 10 minutes) to remove the supernatant, and the remaining precipitated particles are mixed with acetone and then centrifuged again (rotation speed). The supernatant was removed and washed at 3500 rpm for 10 minutes. Methanol was added thereto, followed by centrifugation (rotation speed 3500 rpm, time 10 minutes). The organic tin decomposition rate at 300 ° C. of the obtained tin fine particles was −1.28%.

(Comparative Example 2)
To prepare the metal component solution, 12.5 g of tin chloride (special grade reagent manufactured by Wako Pure Chemical Industries) and 6.25 g of sodium citrate (special grade reagent manufactured by Wako Pure Chemical Industries) were dissolved in 375 g of pure water, and methanol was used. Add 0.25 g of rosin adjusted to 1% concentration (trade name Marquide No. 34, manufactured by Arakawa Chemical Industries) and stir in an eggplant flask. After adjusting the aqueous solution to pH 7 with 20% aqueous sodium hydroxide solution, 0.05 g of reagent special grade manufactured by Kojun Pharmaceutical Co., Ltd. was added. Thereafter, a 2.5% sodium tetrahydroborate aqueous solution was put in another container, and the prepared metal component liquid was added while stirring at 300 rpm, followed by stirring for 1 hour.

  After stirring, the tin synthesis solution obtained by the reduction reaction is separated by centrifugation (rotation speed 3500 rpm, time 10 minutes) to remove the supernatant, and the remaining precipitated particles are mixed with acetone and then centrifuged again (rotation speed). The supernatant was removed and washed at 3500 rpm for 10 minutes. Methanol was added thereto, followed by centrifugation (rotation speed 3500 rpm, time 10 minutes).

(Comparative Example 3)
The rosin of Example 1 was changed to the trade name China Polymerized Rosin 140 (manufactured by Arakawa Chemical Industries). However, since the rosin was insoluble in water and methanol, tin particles could not be synthesized as in Example 1. .

(Comparative Example 4)
Although the rosin of Example 1 was changed to the trade name Shirokiku rosin (manufactured by Arakawa Chemical Industries), tin particles could not be synthesized in the same manner as in Example 1 because the rosin was insoluble in water and methanol.

(Comparative Example 5)
A dispersion of tin particles was prepared in the same manner as in Example 1 except that the rosin of Example 1 was changed to the trade name Zephrym3300B (manufactured by Croda Japan).

  The information regarding Examples 1-5 and Comparative Examples 1-5 is summarized in Table 1.

Claims (3)

  A rosin that is insoluble in water and soluble in methanol is dissolved in alcohol and coexisted in an aqueous solution of tin chloride to form a suspension, which is then reduced to precipitate tin particles coated with rosin. A method for producing tin fine particles, characterized by comprising: A method for producing a tin ink for ink-jet printing , wherein after the reduction treatment liquid in which the tin fine particles are deposited according to claim 1 is substituted with a polar solvent, the viscosity at 23 ° C is adjusted to 2 to 1000 mPa · s,
The method for producing a tin ink for inkjet, wherein the polar solvent is at least one selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, tetraethylene glycol, 1-octanol, and glycerin. The manufacturing method of the tin ink for inkjets of Claim 2 whose average particle diameter of the tin fine particle contained in the said tin ink for inkjets is 1-100 nm.

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