KR20170098233A - Soldering flux, solder paste and method for manufacturing soldering flux - Google Patents

Abstract

The flux for solder includes rosin, a thixotropic agent, an activator, an antioxidant and a solvent, and contains rosin ester as rosin, and the content of rosin ester is set within a range of 20 mass% to 50 mass% with respect to the entire flux, As the tropic agent, at least one selected from polyamide, cured castor oil, a derivative thereof, and a hydrocarbon-based wax is included.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to solder fluxes, solder pastes, and fluxes for solder,

The present invention relates to a solder flux used during soldering, a solder paste in which flux for solder is used, and a method for manufacturing flux for solder.

Generally, for example, when electronic parts or the like are mounted on a circuit board, electronic parts and a circuit board are soldered using a reflow soldering method using the solder paste.

As shown in, for example, Patent Documents 1 and 2, a solder paste is constituted by mixing a solder powder and a flux for solder.

Conventionally, the viscosity or the thixotropic index (TI value) of the solder paste was adjusted according to the use application. On the other hand, the TI value refers to a value calculated from the viscosity when the shear rate is low and the viscosity when the shear rate is high.

Here, when electronic parts are mounted using the solder paste, the electronic parts are mounted in the following order. First, a solder paste is printed on the surface of a circuit board on which electronic components are mounted using a stencil mask or the like, and bumps are formed through reflow. Thereafter, the electronic parts are placed on the bumps formed and heat treatment is performed. As a result, electronic parts and a circuit board are soldered.

In recent years, electronic components have been mounted in a highly integrated manner, and therefore, fine pitch printing in which the solder paste is printed at minute intervals is executed.

[Patent Document 1] JP-A-07-075894 [Patent Document 2] JP-A-2011-136365

On the other hand, in order to perform fine pitch printing of the solder paste, it is preferable to set the viscosity and the TI value of the solder paste to be low in order to improve the filling property in the stencil mask or the like.

Here, in order to lower the viscosity and the TI value of the solder paste, the content of the resin component in the solder flux is reduced. However, if the content of the resin component in the solder flux is reduced, there is a problem that the solder powder and the flux for solder are easily separated, and the storage stability of the solder paste is deteriorated.

Further, when fine pitch printing is performed using a solder paste having a low viscosity and a low TI value, slump easily occurs after printing, shape retention after printing becomes insufficient, and adjacent bumps may contact each other.

Based on the above fact, it is necessary to set the viscosity to 200 Pa · s or more and the TI value to 0.6 or more, for example, in the conventional solder paste for fine pitch printing. For this reason, it has not been possible to ensure the filling property of the stencil mask and to stably print the solder paste.

Further, when fine pitch printing is performed, it is necessary to use fine powder having an average particle diameter of 12 mu m or less as the solder powder, for example. Since the fine solder powder has a large surface area and is easily oxidized, a predetermined amount of oxide tends to increase. In order to remove the oxide, it is necessary to add a strong activator to the solder flux. However, when a strong activator is used, there is a problem that the strong stability of the solder paste is impaired.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a flux for solder which is excellent in shape retentivity after printing and stability of paste storage stability after printing and securing chargeability even when the viscosity and TI value are set low, Paste, and a flux for a solder.

In order to solve the above problems and to achieve the above object, the flux for solder of the present invention is a flux for solder comprising rosin, a thixotropic agent, an activator, an antioxidant and a solvent, and contains rosin ester as the rosin, The content of the ester is set within a range of 20 mass% to 50 mass% with respect to the entire flux, and the thixotropic agent includes one or two or more selected from polyamide, cured castor oil, a derivative thereof, and hydrocarbon wax do.

In the solder flux of the present invention, the rosin contains rosin ester, and the content of rosin ester is set in the range of 20 mass% to 50 mass% with respect to the whole flux. When the amount of the rosin ester as the resin component is relatively large, separation of the solder flux from the solder flux can be suppressed and the shape stability after printing can be ensured. In addition, rosin ester can suppress the viscosity of the paste and the TI value from increasing even when the content thereof is increased.

In addition, since the thixotropic agent contains at least one kind selected from polyamide, hardened castor oil, derivatives thereof and hydrocarbon wax, viscosity and TI value can be optimized, and the shape stability after printing can be ensured .

Accordingly, it is possible to form a solder paste having a low viscosity and TI value, excellent filling property, and excellent shape retention and storage stability after printing.

On the other hand, when the content of the rosin ester is less than 20% by mass with respect to the total flux, when the resin component rosin is contained in a large amount, the viscosity may become high and it may become impossible to secure the optimum filling property. On the other hand, when the content of the rosin ester exceeds 50 mass% with respect to the entire flux, the activity of the flux for solder is not sufficient and the flux may cause the melt failure.

Based on the above facts, in the present invention, the content of the rosin ester can be set in the range of 20 mass% to 50 mass% with respect to the entire flux.

Here, in the solder flux of the present invention, it is preferable that the active agent contains at least one selected from salicylic acid, 2,3-dibromosuccinic acid and triethanolamine as an active agent.

When a fine solder powder is used, the specific surface area of the solder powder becomes large, so that the solder powder contains many oxides. Therefore, by containing at least one selected from salicylic acid, 2,3-dibromosuccinic acid and triethanolamine as the active agent contained in the solder flux, it is possible to sufficiently remove the oxide and to carry out the solder well Lt; / RTI >

In the flux for solder of the present invention, it is preferable to include butylated hydroxytoluene as an antioxidant.

A preferred example of butylated hydroxytoluene is dibutylhydroxytoluene. The dibutylhydroxyl toluene adsorbs on the surface of the solder powder, thereby effectively suppressing the oxidation of the solder powder. For this reason, when dibutylhydroxyl toluene is used as an antioxidant, surface oxidation of the solder powder can be suppressed even in the case of using fine solder powder, and solder can be satisfactorily performed.

The solder paste of the present invention comprises the above solder powder and the flux for solder, and the content of the solder powder is set to 70% by mass to 95% by mass.

Since the solder paste having the above-described constitution includes the flux for solder described above, it has a low viscosity and a low TI value, is excellent in filling property, is excellent in shape retentivity and storage stability after printing, satisfactorily performs fine pitch printing, It is possible to satisfy the high-density mounting of electronic parts.

Here, in the solder paste of the present invention, 25 ℃ and viscosity η ₁₀ of the 10 rpm is 100 Pa · s at least 150 Pa · preferably set in the range of s or less, and the viscosity at 25 ℃ and 3 rpm η _{3, the} shear rate ^{_{D 3 (= 1.8 sec -1)}} , 25 ℃ and the viscosity at 30 rpm shear rate η ₃₀ and D ₃₀ (= 18 sec ^-1) _{from, TI = log (η 3 /} η 30) / it is preferable that the TI value calculated by using log (D ₃₀ / D ₃ ) = log (? ₃ /? ₃₀ ) / log (18 / 1.8) is set within a range of 0.25 or more and 0.5 or less.

In this case, since the viscosity and the TI value are suppressed to be low, the filling property is improved, and fine pitch printing can be performed satisfactorily.

If less than 25 ℃ and 10 rpm the viscosity η is ₁₀ 100 Pa · s in, there is a fear that deterioration of the shape stability after printing. On the other hand, when the viscosity? ₁₀ exceeds 150 Pa · s, there is a fear that charging failure may occur during paste printing.

Based on the above facts, in the present invention, the viscosity? ₁₀ at 25 占 폚 and 10 rpm is set within a range of 100 Pa · s or more and 150 Pa · s or less.

The viscosity η ₃ , shear rate D ₃ (= 1.8 sec ^-1 ) at 25 ° C. and 3 rpm, viscosity η ₃₀ at 25 ° C. and 30 rpm and shear rate D ₃₀ (= 18 sec ^-1 ) _{TI = log (η 3 / η} 30) / log (D 30 / D 3) = log (η 3 / η 30) / log (18 / 1.8) when TI value is less than 0.25 that is calculated by using, in printing The stencil mask is easily clogged and printing failure may occur. In addition, there is a fear that the flux for solder and the solder powder may easily separate from each other. On the other hand, when the TI value exceeds 0.5, there is a fear that charging failure may occur at the time of paste printing.

Based on the above fact, in the present invention, the TI value is set in the range of 0.25 to 0.5.

A manufacturing method of a solder flux according to the present invention is a manufacturing method of a solder flux for manufacturing the solder flux, comprising: a solvent heating step of heating the solvent; Adding rosin to the solvent and stirring the rosin; Cooling the rosin added solvent, adding a thixotropic agent and stirring, adding a thixotropic agent; And a step of adding an activator and an antioxidant to further cool the solvent to which the thixotropic agent is added and to add the activator and the antioxidant, wherein in the step of adding the thixotropic agent, the stirring speed in the addition of the thixotropic agent , And the thixotropic agent is dispersed.

In the above-described method for producing a solder flux, the stirring speed during the addition of the thixotropic agent is set to be higher than the stirring speed in the rosin addition step, and since the thixotropic agent is sufficiently dispersed in the thixotropic agent addition step, It is possible to improve the post-shape retention.

Further, since the activator and the antioxidant are added after the solvent is cooled, the thermal decomposition of the activator and the antioxidant can be suppressed, and the oxide removing performance on the surface of the solder powder and the storage stability of the solder paste can be improved. Therefore, even when fine powder is used as the solder powder, good wettability and storage stability of the solder paste can be ensured.

Moreover, since the rosin, the thixotropic agent, the activator, the antioxidant and the solvent are mixed in the step of heating once and cooling once, the energy cost consumed in manufacturing the solder flux can be reduced.

According to the present invention, there is provided a method for producing a flux for solder, a solder paste, and a flux for solder which is excellent in shape retention after printing and storage stability of paste even when the viscosity and TI value are set low .

1 is a flow chart illustrating a method of manufacturing a solder flux according to an embodiment of the present invention.

Hereinafter, flux for solder and solder paste which are embodiments of the present invention will be described.

The flux for solder and the solder paste according to the embodiment of the present invention are used when the electronic component is mounted on the surface of the circuit board. More specifically, for example, a flux for solder and a solder paste are used to form an area array bump having a pitch of 150 mu m or less.

First, flux for solder according to an embodiment will be described. The flux for solder includes rosins, thixotropic agents, activators, antioxidants and solvents. In addition to the above-mentioned surfactants, a surfactant may be added.

The composition of the solder flux of the present embodiment is such that the rosin is 30 mass% to 70 mass%, the thixotropic agent is 1 mass% to 10 mass%, the activator is 2 mass% to 7 mass%, the antioxidant is 0.1 mass % To 2.0% by mass, and the balance is a solvent.

The rosin as the resin component contains rosin ester, and the content of the rosin ester is set within a range of 20% by mass to 50% by mass with respect to the total flux for solder.

On the other hand, the flux for solder according to the present embodiment includes two types of rosin, rosin hydrogenated rosin and rosin ester. Polymerized rosin, rosin-modified phenol resin, rosin-modified maleic acid resin, or acrylic rosin.

Examples of the thixotropic agent include one or more selected from the group consisting of polyamide, hardened castor oil, derivatives thereof (amide modified castor oil and hydrogenated castor oil), and hydrocarbon waxes (petrolatum, wax and pin wax).

On the other hand, in the solder flux of the present embodiment, polyamide and paraffin wax are used as the thixotropic agent.

Examples of the active agent include lactic acid, stearic acid, entalonic acid, oxalic acid, butyric acid, citric acid, glutaric acid, adipic acid, salicylic acid, succinic acid, 2,3- dibromosuccinic acid, diethyl phosphate, triethyl phosphate, dimethyl hydrochloride, Hydrobromic acid hydrobromide, aniline hydrochloride, 2-ethylimidazole, diethanolamine, triethanolamine and the like can be used.

In the solder flux of the present embodiment, one or two kinds selected from salicylic acid and 2,3-dibromosuccinic acid are included as active agents.

As the antioxidant, butylhydroxyanisole, dibutylhydroxytoluene, glycine, hydroquinone and the like can be used.

In the solder flux of the present embodiment, dibutylhydroxytoluene is included as an antioxidant.

Examples of the solvent include glycol solvents such as ethylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, hexylene glycol, 1,5-pentanediol, propylene glycol monomethyl ether, methylcarbitol, butylcarbitol, triethylene glycol Diethylene glycol monomethyl ether, diethylene glycol monohexyl ether, ethylene glycol monophenyl ether, diethylene glycol monophenyl ether, diethylene glycol-2-ethyl Hexyl ether, ethylene glycol monobutyl ether and diethylene glycol monobutyl ether), alcohol solvents (isopropyl alcohol and 2-butoxyethanol), and the like.

In the solder flux of the present embodiment, diethylene glycol monobutyl ether is used as a solvent.

Depending on the application, a surfactant may be added. As the surfactant, for example, levulinic acid can be used. The addition amount of the surfactant is preferably 0.1% by mass to 2.0% by mass.

Next, the solder paste of the present embodiment will be described.

The solder paste of this embodiment includes the solder powder and flux for solder of the present embodiment, and the content of the solder powder is set to 70% by mass to 95% by mass.

In the solder paste of the present embodiment, Sn-Ag-Cu alloy made of fine powder having an average particle diameter of 12 탆 or less is used as the solder powder.

In the solder paste of this embodiment, the viscosity? ₁₀ at 25 占 폚 and 10 rpm is set within the range of 100 Pa · s to 150 Pa · s.

Furthermore, from the viscosity η _3, a shear rate of ^{_{D 3 (= 1.8 sec -1)}} , the viscosity η ₃₀ and a shear rate of D ₃₀ (= 18 sec ^-1) at the 25 ℃ and 30 rpm in a 25 ℃ and 3 rpm _{TI = log (η 3 / η} 30) / log (D 30 / D 3) = TI value calculated using a _{log (η 3 / η 30)} / log (18 / 1.8) is set to 0.25 to 0.5 range .

Here, in the present embodiment, the viscosities? ₁₀ ,? _3, and? ₃₀ of the solder paste are measured using a spiral viscometer manufactured by Malcom.

Next, a method of manufacturing the solder flux of the present embodiment will be described with reference to Fig.

A container having a thermometer and a stirrer is filled with a solvent and heated (solvent heating step S01). Rosin is added to the heated solvent (rosin addition step S02).

In the solvent heating step S01, it is preferable to adjust the heating temperature according to the type and amount of the solvent, the type of rosin and the amount of the rosin added. In this embodiment, the heating temperature is set within the range of 70 占 폚 to 200 占 폚.

In the rosin addition step S02, the solvent and the rosin are stirred at a low speed so as to be uniformly mixed.

On the other hand, when rosin is added to the solvent and heated while stirring, the solvent heating step S01 and the rosin addition step S02 may be performed simultaneously.

When the rosin is uniformly dispersed in the solvent, the solvent is cooled to the addition temperature of the thixotropic agent while stirring at a low speed, and a thixotropic agent is added (thixotropic agent addition step S03).

In the thixotropic agent addition step S03, it is preferable to adjust the addition temperature depending on the kind of the thixotropic agent. In the present embodiment, the heating temperature of the thixotropic agent is set within the range of 30 占 폚 to 80 占 폚.

In the thixotropic agent addition step S03, the solvent is stirred at a high speed such that the thixotropic agent is reliably dispersed. It is preferable that the stirring speed in the thixotropic agent addition step S03 is set to twice or more the stirring speed in the rosin addition step S02. The stirring time is preferably set to 10 minutes or more.

On the other hand, in the thixotropic agent addition step S03, it is preferable to stir the solution at high speed and then stir at low speed for 10 minutes or more while maintaining the addition temperature of the thixotropic agent.

Next, the solution is cooled at low speed to the addition temperature of the activator and the antioxidant, and the active agent and the antioxidant are added (step S04 of adding the activator and the antioxidant).

In the step S04 of adding the activator and the antioxidant, it is preferable to adjust the addition temperature depending on the type and amount of the activator, and the kind and amount of the antioxidant. In the present embodiment, the addition temperature of the activator and the antioxidant is set in the range of 25 캜 to 70 캜.

After confirming that the whole solution becomes uniform, the solution is cooled to room temperature.

The solder flux of the present embodiment is manufactured using the above steps.

The solder paste of this embodiment is produced by mixing solder powder and flux for solder.

In addition, area array bumps having a pitch of 150 mu m or less are formed by printing the solder paste of the present embodiment on the surface of a circuit board on which electronic components are to be mounted by fine pitch printing using a stencil mask, Respectively.

According to the flux for solder and the solder paste of the present embodiment having the above-described configuration, rosin ester is contained as the resin component rosin, and the content of the rosin ester is set in the range of 20 mass% to 50 mass% with respect to the entire flux , Separation of the flux for solder and the solder powder can be suppressed, and the shape stability after printing can be ensured. In addition, rosin ester can suppress increase in viscosity and TI value even when the content of rosin ester is high, and the filling property with respect to the stencil mask and the like is improved, and the paste can be printed precisely.

According to the flux for solder and the solder paste of the present embodiment, since the thixotropic agent includes at least one selected from polyamide, hardened castor oil, derivatives thereof, and hydrocarbon wax, viscosity of the solder paste and TI The value can be optimized, and the shape stability after printing can be ensured.

Accordingly, it is possible to provide a solder paste having a low viscosity and a low TI value, excellent filling properties, and excellent shape retention after coating.

According to the flux for solder and the solder paste of the present embodiment, one or two or more kinds selected from salicylic acid, 2,3-dibromosuccinic acid and triethanolamine are contained as the activator, even when a fine solder powder is used , The surface oxidation of the solder powder can be sufficiently suppressed.

According to the flux for solder and the solder paste of the present embodiment, dibutylhydroxytoluene is contained as an antioxidant, oxidation of the solder powder can be effectively suppressed, and even when fine solder powder is used, Oxidation can be sufficiently suppressed.

According to the solder paste of the present embodiment, since the solder powder and the flux for solder are included and the content of the solder powder is set to 70% by mass to 95% by mass, the viscosity and the TI value are low and the filling property is excellent. It is possible to satisfactorily perform the fine pitch printing and to realize the high density mounting of the electronic parts.

According to the solder paste of the present embodiment, 25 ℃ and viscosity η ₁₀ of the 10 rpm is set to 100 Pa · s to 150 Pa · s range, and the viscosity at 25 ℃ and 3 rpm η _3, shear rate ^{_{D 3 (= 1.8 sec -1)}} , 25 ℃ and the viscosity at 30 rpm shear rate η ₃₀ and D ₃₀ (= 18 sec ^-1) from _{TI = log (η 3 / η} 30) / log (D 30 / _{D 3) = log (η 3} / η 30) / log (18 / 1.8) since the TI value is set to 0.25 to 0.5 range is calculated using, performed is improved charging property, and preferably the printing fine pitch .

According to the manufacturing method of the solder flux of the present embodiment, the solvent heating step for heating the solvent, the rosin addition step for adding and stirring the rosin to the solvent, the solvent to which the rosin is added is cooled, the thixotropic agent is added, A step of adding a thixotropic agent, and a step of further cooling the solvent to which the thixotropic agent is added and adding an activator and an antioxidant to add an activator and an antioxidant, and in the step of adding a thixotropic agent, stirring at the time of adding the thixotropic agent The speed is set to be faster than the stirring speed in the rosin addition step and the thixotropic agent is dispersed so that the thixotropic agent is sufficiently dispersed and the shape retention after printing can be improved.

Further, since the activator and the antioxidant are added after the solvent is cooled, the thermal decomposition of the activator and the antioxidant can be suppressed, and the oxide removing performance on the surface of the solder powder in the solder paste and the storage stability of the solder paste can be improved . Therefore, even when fine powder is used as the solder powder, good wettability and storage stability of the solder paste can be ensured.

Moreover, since the rosin, the thixotropic agent, the activator, the antioxidant and the solvent are mixed in the step of heating once and cooling once, the energy cost consumed in manufacturing the solder flux can be reduced.

Although the embodiments of the present invention have been described above, the present invention is not limited thereto, and can be appropriately changed within the scope of the technical idea of the invention.

For example, the raw material and the blending amount of the flux for solder and the solder paste are not limited to those described in the embodiment, and other solvent, solder powder or the like may be used.

[Examples]

Hereinafter, the results of verification tests conducted to confirm the effects of the present invention will be described.

A solder flux having the composition shown in Table 1 was produced in the order shown in Fig.

The solvent and rosin were added to a vessel equipped with a thermometer and a rotary stirrer and heated to 120 DEG C with stirring. At this time, the stirring speed (rotation speed) was set at 100 rpm.

The solution was cooled and maintained at 60 캜, and thixotropic agent was added. At this time, the solution was stirred at a stirring speed (rotation speed) of 300 rpm for 10 minutes or more and then stirred at 150 rpm for 10 minutes or more.

Next, after cooling the solution to 50 DEG C or less, an activator and an antioxidant were added, and the solution was stirred until the whole solution became uniform.

The obtained flux for solder and the solder powder were mixed to prepare the solder paste described in Table 2. [

The viscosity η _3, a shear rate of D ₃ (= 1.8 sec ^-1) of the (viscosity η ₁₀ in 25 ℃ and 10 rpm) and a TI value (25 ℃ and 3 rpm viscosity of the solder paste obtained, 25 ℃ and the viscosity at ₃₀ rpm η 30, shear rate D ₃₀ (= 18 sec ^-1) _{from, TI = log (η 3 /} η 30) / log (D 30 / D 3) = log (η 3 / η 30 ) / log (18 / 1.8)) was measured using a spiral viscometer (PCU-205 manufactured by Malcom). The measurement results are shown in Table 2.

Next, a solder ball test was performed on the obtained solder paste. The storage stability, printability, shape retention after printing, and shape retention after heat treatment were evaluated in the following manner.

(Solder ball test)

IPC-TM-650 No. 1. 2.4.43 Solder Paste - Test and evaluation based on solder ball testing.

A 6.5 mm diameter, 0.2 mm thick, stencil mask with three or more openings was used to print the solder paste to be evaluated on the alumina substrate using Spetula. The alumina substrate printed with the solder paste was heated on a hot plate at 242 占 폚 占 3 占 폚 for 20 seconds in order to perform a reflow process.

Obtained solder balls were observed and it was evaluated as "preferred" that a solder ball not showing microballs was observed around the main ball, and "allowable" , Evaluating the solder balls with many microballs in the cluster as "unacceptable: clusters", and evaluating the solder balls with many microballs as "unacceptable" to surround the main balls. On the other hand, "desirable" and "acceptable" The evaluation results are shown in Table 3.

(Storage stability)

The obtained paste was stored at 4 캜 in an atmospheric environment, and the state of separation of the flux and the solder powder in the paste after 3 months was evaluated. The paste in which the separation was observed was evaluated as "oil ", and the paste in which separation was not observed was evaluated as" no ". The evaluation results are shown in Table 3.

Similarly, the paste was stored at 4 ° C in an atmospheric air, and the viscosity (viscosity η ₁₀ at 25 ° C and 10 rpm) in the paste after 3 months was measured. A paste having a viscosity change of ± 20 Pa · s and a viscosity of 100 Pa · s or more and 150 Pa · s or less was evaluated as "possible" as compared with the viscosity measured 3 months before the measurement, Was evaluated as "invisible ". The evaluation results are shown in Table 3.

(Printability / shape retention after printing)

Solder paste was printed using Hitachi Cream Solder Printer NP-04MB manufactured by Hitachi, Ltd. At this time, three stencil masks (having a thickness of 35 mu m) having a pitch of 150 mu m (mask opening diameter of 115 mu m), a pitch of 180 mu m (mask opening diameter of 130 mu m) and a pitch of 200 mu m (mask opening diameter of 140 mu m)

And occurrence of clogging at the mask opening was checked. The shape of the printed paste in each of the masks was observed using a microscope and evaluated. A mask sufficiently filled with paste to prevent contact between adjacent bumps was evaluated as "good ", and a mask in which paste was insufficiently filled or contact was observed between adjacent bumps was evaluated as" not possible ". The evaluation results are shown in Table 3.

(Shape retention after heat treatment)

The printed solder paste was subjected to reflow treatment (under a nitrogen atmosphere at a maximum temperature of 250 DEG C for 3 minutes) to evaluate the occurrence of contact (bridges) between adjacent bumps. The evaluation results are shown in Table 3.

In the solder paste of Comparative Example 11 using the solder flux of Comparative Example 1 in which the content of rosin ester was smaller than the range of the present invention, the viscosity? ₁₀ at 25 占 폚 and 10 rpm was relatively high as 187 Pa 占 퐏. In addition, shape retention after printing at a pitch of 150 mu m was insufficient. Furthermore, it was confirmed that the storage stability was inferior due to the observation of a change with time in viscosity after storage for 3 months.

In the solder paste of Comparative Example 12 using the solder flux of Comparative Example 2 in which the content of rosin ester exceeded the range of the present invention, the result of the solder ball test was that the solder ball was entirely surrounded by the non- ".

In the solder fluxes of Examples 1 to 5 of the present invention and the solder paste of Examples 11 to 15 of the present invention, separation of the flux and the solder powder was not observed even after 3 months of storage, And storage stability was excellent. In the solder paste of Examples 11 to 15 of the present invention, the viscosity? ₁₀ at 25 占 폚 and 10 rpm was set within a range of 100 Pa · s or more and 150 Pa · s or less, and TI = log (? ₃ / η ₃₀ ) / log (18 / 1.8) were set within the range of 0.25 or more and 0.5 or less, and the printability, shape stability after printing, and shape stability after heat treatment were excellent. Also, the results of the solder ball test were also good.

As a result of the above confirmation test, it is possible to provide a flux for solder and a solder paste which are excellent in shape retention and storage stability after printing, and capable of securing the filling property.

[Industrial applicability]

Electronic circuits can be assembled more efficiently and efficiently by providing solder fluxes and solder pastes with suitable properties and high stability.

S01; Solvent heating step
S02; rosin addition step
S03; thixotropic agent addition step
S04 Step of adding activator and antioxidant

Claims (6)

As the solder flux,
Rosin;
Thixotropic agents;
An activator;
Antioxidants; And
Comprising a solvent,
The rosin contains rosin ester, the content of the rosin ester is set within a range of 20 mass% to 50 mass% with respect to the total flux, and
Wherein the thixotropic agent includes at least one selected from the group consisting of polyamide, cured castor oil, a derivative thereof, and a hydrocarbon-based wax. The method according to claim 1,
Wherein the activator comprises at least one selected from salicylic acid, 2,3-dibromosuccinic acid and triethanolamine. 3. The method according to claim 1 or 2,
Wherein the antioxidant includes butylated hydroxytoluene. As the solder paste,
Solder powder; And
A flux for solder according to any one of claims 1 to 3,
And the content of the solder powder is set to 70% by mass to 95% by mass. 5. The method of claim 4,
A viscosity η ₁₀ in 25 ℃ and 10 rpm being set in a range of 100 Pa · s to 150 Pa · s, and
25 ℃ and 3 rpm viscosity η _3, a shear rate of D ₃ in (= 1.8 sec ^-1), TI from the viscosity η ₃₀ and a shear rate of D ₃₀ (= 18 sec ^-1) at the 25 ℃ and 30 rpm = _{log (η 3 / η 30)} / log (D 30 / D 3) = log (η 3 / η 30) / log (18 / 1.8), which the TI value is set to 0.25 to 0.5 range which is calculated by using a solder Paste. A manufacturing method of a solder flux for manufacturing the solder flux according to any one of claims 1 to 3,
A solvent heating step of heating the solvent;
Adding a rosin to the solvent and stirring the rosin;
Cooling the solvent to which the rosin is added, adding a thixotropic agent and stirring the thixotropic agent; And
Further comprising the step of adding an activator and an antioxidant to further cool the solvent to which the thixotropic agent is added and to add an activator and an antioxidant,
Wherein the stirring speed in adding the thixotropic agent to the thixotropic agent is set to be faster than the stirring speed in the rosin addition step and the thixotropic agent is dispersed in the step of adding the thixotropic agent.

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