JP6643744B1 - Solder paste and flux for solder paste - Google Patents

Abstract

An object of the present invention is to provide a solder paste which hardly changes with time, has excellent wettability of molten solder, has high mechanical properties, and has an increased solder wettability. A solder paste containing a specific solder powder and a flux is employed. Solder powder, As: 25 to 300 mass ppm, Pb: 0 mass ppm to 5100 mass ppm or less, and Sb: 0 mass ppm to 3000 mass ppm or less, and Bi: 0 mass ppm to 10000 mass ppm or less, And a solder alloy having an alloy composition consisting of the balance Sn and satisfying the expressions (1) and (2). The flux contains a thixotropic agent, an aromatic guanidine compound, rosin, an organic acid, and a solvent. 275 ≦ 2As + Sb + Bi + Pb (1) 0.01 ≦ (2As + Sb) / (Bi + Pb) ≦ 10.00 (2) [Selection] None

Description

  The present invention relates to a solder paste and a flux for a solder paste.

  In recent years, electronic devices having a solder joint such as a CPU (Central Processing Unit) have been required to be smaller and have higher performance. Accordingly, it is necessary to reduce the size of the printed circuit board and the electrodes of the electronic device. Since an electronic device is connected to a printed circuit board via an electrode, the size of the electrode is reduced and the size of a solder joint for connecting the two is also reduced.

In order to connect an electronic device and a printed board via such fine electrodes, a solder paste is generally used.
The solder paste is supplied on the electrodes of the printed circuit board by printing or the like. Solder paste printing consists of placing a metal mask with an opening on a printed circuit board, moving the squeegee while pressing it against the metal mask, and applying the solder paste to the electrodes on the printed circuit board from the metal mask opening. It is performed by Thereafter, the electronic component is placed on the solder paste printed on the printed circuit board and held by the solder paste until the soldering is completed.

  If, for example, several hours are required after the electronic component is placed on the printed circuit board until it is introduced into the reflow furnace, the solder paste may not be able to maintain the shape at the time of printing. In this case, it may cause a tilt of the electronic component or a bonding failure. In addition, when the solder paste is purchased, usually, the entire amount is not used up in one printing, so that the solder paste must maintain an appropriate viscosity at the beginning of manufacturing so as not to deteriorate the printing performance.

  However, in recent years, as the size of the electrode has been reduced, the printed area of the solder paste has also been reduced, so that the time until the purchased solder paste has been used has been prolonged. Solder paste is a mixture of solder powder and flux.If the storage period is long, the viscosity of the solder paste will increase depending on the storage conditions, and the printing performance at the time of purchase cannot be exhibited. Sometimes.

  Therefore, for example, Patent Document 1 includes Sn and one or more selected from the group consisting of Ag, Bi, Sb, Zn, In, and Cu in order to suppress a temporal change of the solder paste, Further, a solder alloy containing a predetermined amount of As is disclosed. The document shows that the viscosity after 2 weeks at 25 ° C. is less than 140% as compared with the viscosity at the beginning of production.

  On the other hand, the flux used for soldering chemically removes the metal oxides present on the metal surface of the solder and the joining object to be soldered, and enables the movement of metal elements at the boundary between the two. have. Therefore, by performing soldering using a flux, an intermetallic compound can be formed between the solder and the metal surface of the object to be joined, and a strong joint can be obtained.

  In a solder paste containing such soldering flux and solder powder, thixotropy is imparted by a thixo agent contained in the flux. The thixotropic agent builds a network in the flux and imparts thixotropic properties.

JP-A-2005-98052

  As described above, the invention described in Patent Document 1 is a solder alloy that can selectively contain six types of elements in addition to Sn and As. In addition, the document shows that when the As content is large, the meltability is poor.

  Here, the meltability evaluated in Patent Document 1 is considered to correspond to the wettability of the molten solder. The meltability disclosed in this document is evaluated by observing the appearance of the melt with a microscope and by the presence or absence of solder powder that cannot be melted completely. This is because if the wettability of the molten solder is high, the solder powder that cannot be melted hardly remains.

  Generally, in order to improve the wettability of molten solder, it is necessary to use a highly active flux. In the flux described in Patent Document 1, it is considered that a highly active flux may be used in order to suppress the deterioration of wettability due to As. However, when a highly active flux is used, the rate of increase in the viscosity of the flux increases. Also, in view of the description of Patent Document 1, it is necessary to increase the As content in order to suppress the increase in the rate of increase in viscosity. In order for the solder paste described in Patent Document 1 to exhibit a lower viscosity increase rate and excellent wettability, it is necessary to keep increasing the flux activation power and As content, which causes a vicious cycle.

  In recent years, solder pastes have been required to maintain stable performance for a long period of time irrespective of use environment and storage environment, and further higher wettability has been required due to miniaturization of solder joints. When trying to respond to recent demands using the solder paste described in Patent Document 1, a vicious cycle is inevitable as described above.

  Furthermore, in order to join fine electrodes, it is necessary to improve the mechanical properties and the like of the solder joint. If the content of some elements increases, the liquidus temperature increases, the liquidus temperature and the solidus temperature increase, and segregation occurs during solidification to form a non-uniform alloy structure. When the solder alloy has such an alloy structure, mechanical properties such as tensile strength are inferior, and the solder alloy is easily broken by an external stress. This problem has become remarkable with recent miniaturization of electrodes.

  In addition, the solder paste is required to have a high solder wetting speed and a good solder wettability with respect to the metal surface of the joining object.

  The present invention has been made in order to solve the above-described problems, and is unlikely to cause a change with time such as an increase in viscosity, has excellent wettability of molten solder, has high mechanical properties, and has a metal to be joined. It is an object of the present invention to provide a solder paste in which the wetting speed of the solder on the surface is increased.

  When the suppression of the change over time of the solder paste and the excellent wettability are simultaneously improved, it is necessary to use a flux having a high activity and avoid a vicious cycle due to an increase in the As content. The present inventors have focused on the alloy composition of the solder powder, and have conducted intensive studies in order to achieve both suppression of the change over time of the solder paste and excellent wettability.

  First, the present inventors studied a solder powder containing As as a basic composition based on Sn, SnCu, and SnAgCu solder alloys conventionally used as solder alloys. Then, when this solder powder was used, attention was paid to the reason for suppressing the temporal change of the solder paste, and the As content was examined.

  It is considered that the reason why the viscosity of the solder paste increases with time is that the solder powder reacts with the flux. When the results of Example 4 and Comparative Example 2 in Table 1 of Patent Document 1 are compared, it is found that the case where the As content exceeds 100 ppm by mass has a lower viscosity increase rate. In view of these, it was considered that the As content may be further increased when attention is paid to the effect of suppressing the temporal change of the solder paste (hereinafter, referred to as the “viscosity suppressing effect” as appropriate). When the As content was increased, the effect of suppressing thickening slightly increased with the As content, but it was confirmed that when the As content was too large, the wettability of the solder alloy deteriorated.

  Then, the present inventors came to the conclusion that it was necessary to add an element exhibiting a thickening suppressing effect in addition to As, and examined various elements. As a result, Sb, Bi and Pb were found to be As Obtained the same effect as described above. The reason for this is not clear, but is presumed as follows.

  Since the effect of suppressing thickening is exhibited by suppressing the reaction with the flux, an element having a low reactivity with the flux includes an element having a low ionization tendency. Generally, the ionization of an alloy is considered based on the ionization tendency as an alloy composition, that is, the standard electrode potential. For example, a SnAg alloy containing Ag which is noble to Sn is less likely to ionize than Sn. For this reason, an alloy containing an element nobler than Sn is less likely to be ionized, and is presumed to have a high effect of suppressing the viscosity increase of the solder paste.

  Here, in Patent Document 1, Bi, Sb, Zn, and In are listed as equivalent elements in addition to Sn, Ag, and Cu. However, In and Zn have a lower ionization tendency than Sn. Element. In other words, Patent Literature 1 describes that the effect of suppressing thickening can be obtained even when an element more noble than Sn is added. For this reason, it is considered that a solder alloy containing an element selected according to the ionization tendency can obtain a thickening suppression effect equal to or greater than that of the solder alloy described in Patent Document 1. Further, as described above, when the As content increases, the wettability deteriorates.

  The present inventors have studied in detail Bi and Pb found as a thickening suppressing effect. Since Bi and Pb lower the liquidus temperature of the solder alloy, when the heating temperature of the solder alloy is constant, the wettability of the solder alloy is improved. However, the solidus temperature is significantly reduced depending on the content thereof, so that ΔT, which is the temperature difference between the liquidus temperature and the solidus temperature, becomes too wide. If ΔT is too wide, segregation occurs at the time of solidification, leading to a decrease in mechanical properties such as mechanical strength. Since the phenomenon that ΔT is widespread appears remarkably when Bi and Pb are added simultaneously, it has also been found that strict control is necessary.

  In addition, the present inventors reviewed the Bi content and the Pb content in order to improve the wettability of the solder alloy. However, when the content of these elements increased, ΔT became wider. Therefore, the present inventors have selected Sb as an element whose ionization tendency is noble with respect to Sn and also as an element for improving the wettability of a solder alloy, and set an allowable range of the Sb content. The relationship regarding the content of each of As, Bi, Pb and Sb including Sb was examined in detail. As a result, by chance, when the content of these elements satisfies the predetermined relational expression, it is found that there is no practical problem in all of the excellent thickening suppression effect, wettability, and narrowing of ΔT. Was.

  Further, the present inventors have found that when soldering is performed using a flux containing an aromatic guanidine compound, the wetting rate of the solder to the metal surface of the joining object increases.

The present invention obtained based on these findings is as follows.
[1] A solder paste containing a solder powder and a flux, wherein the solder powder contains As: 25 to 300 mass ppm, Pb: more than 0 mass ppm, 5100 mass ppm or less, and Sb: 0 mass ppm. Over 3000 mass ppm, and Bi: at least one of over 0 mass ppm to 10,000 mass ppm, and a balance having an alloy composition consisting of Sn, including a solder alloy satisfying the following formulas (1) and (2); The solder paste, wherein the flux contains a thixotropic agent, an aromatic guanidine compound, rosin, an organic acid, and a solvent.
275 ≦ 2As + Sb + Bi + Pb (1)
0.01 ≦ (2As + Sb) / (Bi + Pb) ≦ 10.00 (2)
In the above formulas (1) and (2), As, Sb, Bi and Pb each represent the content (ppm by mass) in the alloy composition.

[2] The solder paste according to [1], wherein the alloy composition satisfies the following formula (1a).
275 ≦ 2As + Sb + Bi + Pb ≦ 25200 (1a)
In the above formula (1a), As, Sb, Bi and Pb each represent the content (mass ppm) in the alloy composition.

[3] The solder paste according to [1], wherein the alloy composition satisfies the following formula (1b).
275 ≦ 2As + Sb + Bi + Pb ≦ 5300 (1b)
In the above formula (1b), As, Sb, Bi and Pb each represent the content (mass ppm) in the alloy composition.

[4] The solder paste according to any one of [1] to [3], wherein the alloy composition satisfies the following formula (2a).
0.31 ≦ (2As + Sb) / (Bi + Pb) ≦ 10.00 (2a)
In the above formula (2a), As, Sb, Bi and Pb each represent the content (mass ppm) in the alloy composition.

[5] The alloy composition according to any one of [1] to [4], wherein the alloy composition contains at least one of Ag: 0 to 4% by mass and Cu: 0 to 0.9% by mass. Solder paste.

[6] The solder paste according to any one of [1] to [5], wherein the aromatic guanidine compound is at least one selected from the group consisting of diphenylguanidine and ditolylguanidine.

[7] The solder paste according to any one of [1] to [6], including the aromatic guanidine compound in an amount of from 0.2% by mass to 15% by mass.

[8] The solder paste according to any one of the above [1] to [7], which contains the organic acid and the aromatic guanidine compound in a total amount of 3% by mass or more and 18% by mass or less.

[9] The solder paste according to any one of [1] to [8], wherein the thixotropic agent contains at least one selected from the group consisting of an amide compound and an ester compound.

[10] The solder paste according to the above [9], wherein the amide compound contains at least one selected from the group consisting of polyamide, bisamide and monoamide.

[11] The solder paste according to [9] or [10], wherein the thixotropic agent contains at least the amide compound and contains the amide compound in an amount of 0.1% by mass or more and 15% by mass or less.

[12] The solder paste according to any one of [9] to [11], wherein the ester compound includes a castor hardened oil.

[13] The solder according to any one of [9] to [12], wherein the thixotropic agent contains at least the ester compound and contains the ester compound in an amount of 0.2% by mass or more and 10% by mass or less. paste.

[14] The solder paste according to any one of [1] to [13], including the rosin in an amount of 15% by mass to 70% by mass.

[15] The organic acid according to any one of [1] to [14], wherein the organic acid includes at least one selected from the group consisting of succinic acid, glutaric acid, adipic acid and hydrogenated dimer acid. Solder paste as described.

[16] The solder paste according to any one of [1] to [15], including the organic acid in an amount of 0.1% by mass to 15% by mass.

[17] Furthermore, 0 to 8% by mass of an amine, 0 to 8% by mass of an organic halogen compound, 0 to 8% by mass of an amine hydrohalide, and an antioxidant. The solder paste according to any one of the above [1] to [16], which contains 0% by mass to 8% by mass.

[18] A flux used for a solder paste, wherein the flux contains a thixotropic agent, an aromatic guanidine compound, rosin, an organic acid, and a solvent,
The solder paste contains at least one of As: 25 to 300 mass ppm, Pb: more than 0 mass ppm to 5100 mass ppm, and Sb: more than 0 mass ppm to 3000 mass ppm, and Bi: more than 0 mass ppm to 10,000 mass ppm. And a solder paste flux having an alloy composition consisting of Sn, and a solder powder containing a solder alloy satisfying the following formulas (1) and (2).
275 ≦ 2As + Sb + Bi + Pb (1)
0.01 ≦ (2As + Sb) / (Bi + Pb) ≦ 10.00 (2)
In the above formulas (1) and (2), As, Sb, Bi and Pb each represent the content (ppm by mass) in the alloy composition.

According to the present invention, a solder that hardly undergoes a change over time such as an increase in viscosity, has excellent wettability of molten solder, has high mechanical properties, and has an increased solder wetting speed on a metal surface of an object to be joined A paste can be provided.
Further, according to the present invention, it is possible to provide a solder paste flux having a high solder wettability with respect to a metal surface of an object to be joined and having good solder wettability.

The present invention is described in more detail below.
In this specification, “ppm” regarding the solder alloy composition is “mass ppm” unless otherwise specified. “%” Is “% by mass” unless otherwise specified.

<Solder paste>
The solder paste of the present embodiment contains a specific solder powder and a specific flux.

≪Solder powder≫
The solder powder used in the solder paste of the present embodiment includes As: 25 to 300 mass ppm, Pb: more than 0 mass ppm to 5100 mass ppm, and Sb: more than 0 mass ppm to 3000 mass ppm, and Bi: 0 mass ppm. At least one of not more than 10,000 mass ppm and a solder alloy having an alloy composition consisting of Sn in the balance and satisfying the following formulas (1) and (2) are included.
275 ≦ 2As + Sb + Bi + Pb (1)
0.01 ≦ (2As + Sb) / (Bi + Pb) ≦ 10.00 (2)
In the above formulas (1) and (2), As, Sb, Bi and Pb each represent the content (ppm by mass) in the alloy composition.

1. Alloy composition (1) As: 25 to 300 mass ppm
As is an element capable of suppressing a change with time in the viscosity of the solder paste. It is presumed that As has low reactivity with flux and is an element noble to Sn, so that it can exert a thickening suppressing effect. When As is less than 25 ppm by mass, the effect of suppressing thickening cannot be sufficiently exhibited. The lower limit of the As content is 25 ppm by mass or more, preferably 50 ppm by mass or more, and more preferably 100 ppm by mass or more. On the other hand, if the content of As is too large, the wettability of the solder alloy deteriorates. The upper limit of the As content is 300 ppm by mass or less, preferably 250 ppm by mass or less, and more preferably 200 ppm by mass or less.

(2) Pb: at least one of 0 mass ppm to 5100 mass ppm or less, and Sb: at least one mass of more than 0 mass ppm to 3000 mass ppm and Bi: more than 0 mass ppm to 10000 mass ppm Sb has low reactivity with flux. It is an element that exhibits a thickening suppressing effect. When the solder alloy in this embodiment contains Sb, the lower limit of the Sb content is more than 0 mass ppm, preferably 25 mass ppm or more, more preferably 50 mass ppm or more, and further preferably 100 mass ppm. ppm or more, particularly preferably 300 ppm by mass or more. On the other hand, if the Sb content is too large, the wettability deteriorates, so it is necessary to make the Sb content appropriate. The upper limit of the Sb content is 3000 ppm by mass or less, preferably 1150 ppm by mass or less, more preferably 500 ppm by mass or less.

  Bi and Pb, like Sb, are elements having low reactivity with flux and exhibiting a thickening suppressing effect. Further, Bi and Pb are elements that can lower the liquidus temperature of the solder alloy and reduce the viscosity of the molten solder, thereby suppressing the deterioration of wettability due to As.

  If at least one element of Pb, Sb, and Bi is present, deterioration of wettability by As can be suppressed. When the solder alloy in the present embodiment contains Bi, the lower limit of the Bi content is more than 0 mass ppm, preferably 25 mass ppm or more, more preferably 50 mass ppm or more, and still more preferably 75 mass ppm or more. ppm or more, particularly preferably 100 ppm or more, and most preferably 250 ppm or more. The lower limit of the Pb content is more than 0 mass ppm, preferably 25 mass ppm or more, more preferably 50 mass ppm or more, still more preferably 75 mass ppm or more, and particularly preferably 100 mass ppm or more. And most preferably at least 250 ppm by mass.

  On the other hand, if the content of these elements is too large, the solidus temperature is remarkably lowered, so that ΔT, which is the temperature difference between the liquidus temperature and the solidus temperature, becomes too wide. If ΔT is too wide, a liquid phase Bi or Pb is concentrated in the solidification process of the molten solder because a high melting point crystalline phase having a low content of Bi or Pb is deposited. Thereafter, when the temperature of the molten solder further decreases, a low melting point crystal phase having a high concentration of Bi or Pb segregates. For this reason, the mechanical strength and the like of the solder alloy are deteriorated, and the reliability is deteriorated. In particular, since the crystal phase having a high Bi concentration is hard and brittle, the segregation in the solder alloy significantly lowers the reliability.

  From such a viewpoint, when the solder alloy in the present embodiment contains Bi, the upper limit of the Bi content is 10,000 mass ppm or less, preferably 1000 mass ppm or less, more preferably 600 mass ppm or less. , More preferably 500 ppm by mass or less. The upper limit of the Pb content is 5100 mass ppm or less, preferably 5000 mass ppm or less, more preferably 1000 mass ppm or less, still more preferably 850 mass ppm or less, and particularly preferably 500 mass ppm or less. is there.

(3) Formula (1) The solder alloy in the present embodiment needs to satisfy the following formula (1).

275 ≦ 2As + Sb + Bi + Pb (1)
In the above formula (1), As, Sb, Bi and Pb each represent the content (mass ppm) in the alloy composition.

  As, Sb, Bi, and Pb are all elements that exhibit a thickening inhibiting effect, and their total needs to be 275 mass ppm or more. In the formula (1), the reason why the As content is doubled is that As has a higher effect of suppressing thickening than Sb, Bi, or Pb.

  If the value of the expression (1) is less than 275, the effect of suppressing thickening is not sufficiently exhibited. The lower limit of the formula (1) is 275 or more, preferably 350 or more, and more preferably 1200 or more. On the other hand, the upper limit of the formula (1) is not particularly limited in terms of the effect of suppressing thickening, but is preferably 25200 or less, more preferably 10200 or less, from the viewpoint of setting ΔT in a suitable range. , More preferably 5300 or less, particularly preferably 3800 or less.

  The following formulas (1a) and (1b) are those in which the upper and lower limits are appropriately selected from the above preferred embodiments.

275 ≦ 2As + Sb + Bi + Pb ≦ 25200 (1a)
275 ≦ 2As + Sb + Bi + Pb ≦ 5300 (1b)
In the above formulas (1a) and (1b), As, Sb, Bi and Pb each represent the content (mass ppm) in the alloy composition.

(4) Formula (2) The solder alloy in the present embodiment needs to satisfy the following formula (2).

0.01 ≦ (2As + Sb) / (Bi + Pb) ≦ 10.00 (2)
In the above formula (2), As, Sb, Bi and Pb each represent the content (mass ppm) in the alloy composition.

  When the content of As and Sb is large, the wettability of the solder alloy is deteriorated. On the other hand, Bi and Pb suppress the deterioration of wettability due to the inclusion of As. However, if the content is too large, ΔT increases, so strict management is required. In particular, in an alloy composition containing Bi and Pb simultaneously, ΔT tends to increase. In view of these, if the content of Bi and Pb is increased to improve the wettability excessively, ΔT will be widened. On the other hand, when the content of As or Sb is increased to improve the effect of suppressing thickening, wettability deteriorates. Therefore, in the present embodiment, it is divided into As and Sb groups and Bi and Pb groups, and when the total amount of both groups is within an appropriate predetermined range, the thickening suppression effect, the narrowing of ΔT, and the wetting All of sex is satisfied at the same time.

  If the expression (2) is less than 0.01, the total content of Bi and Pb becomes relatively larger than the total content of As and Pb, so that ΔT is widened. The lower limit of the formula (2) is 0.01 or more, preferably 0.02 or more, more preferably 0.41 or more, further preferably 0.90 or more, and particularly preferably 1.00 or more. And most preferably 1.40 or more. On the other hand, if the expression (2) exceeds 10.00, the total content of As and Sb becomes relatively larger than the total content of Bi and Pb, so that the wettability deteriorates. The upper limit of the formula (2) is 10.00 or less, preferably 5.33 or less, more preferably 4.50 or less, still more preferably 2.67 or less, and still more preferably 2.50. And particularly preferably 2.30 or less.

Note that the denominator of the expression (2) is “Bi + Pb”, and the expression (2) is not satisfied unless these are included. That is, the solder alloy in the present embodiment always contains at least one of Bi and Pb. As described above, the alloy composition containing neither Bi nor Pb has poor wettability.
The following formula (2a) is obtained by appropriately selecting the upper and lower limits from the above preferred embodiments.

0.31 ≦ (2As + Sb) / (Bi + Pb) ≦ 10.00 (2a)
In the above formula (2a), Bi and Pb each represent the content (mass ppm) in the alloy composition.

(5) Ag: 0 to 4 wt% and Cu: at least one of Ag 0 to 0.9% by weight, with optional elements which can improve the reliability of the solder to form a _Ag 3 Sn in the crystal interface alloy is there. Ag is an element having a higher ionization tendency than Sn, and promotes the effect of suppressing thickening of these elements by coexisting with As, Pb and Bi. The Ag content is preferably 0 to 4% by mass, more preferably 0.5 to 3.5% by mass, and still more preferably 1.0 to 3.0% by mass.

  Cu is an optional element that can improve the bonding strength of the solder joint. Further, Cu is an element having a higher ionization tendency than Sn and coexists with As, Pb, and Bi to promote the effect of suppressing thickening of these elements. The Cu content is preferably from 0 to 0.9% by mass, more preferably from 0.1 to 0.8% by mass, and still more preferably from 0.2 to 0.7% by mass.

(6) Remainder: Sn
The balance of the solder alloy in the present embodiment is Sn. Inevitable impurities may be contained in addition to the aforementioned elements. Even if unavoidable impurities are contained, the effects described above are not affected. Further, as described later, even if an element which is not contained in the present invention is contained as an unavoidable impurity, the above-mentioned effect is not affected. If the content of In is too large, ΔT is widened. Therefore, if the content is 1000 ppm or less, the above-mentioned effect is not affected.

2. Solder Powder The solder powder in the present embodiment preferably satisfies a size (particle size distribution) satisfying the symbols 1 to 8 in the powder size classification (Table 2) in JIS Z 3284-1: 2014. More preferably, it is a size (particle size distribution) that satisfies the symbols 4 to 8, and still more preferably a size (particle size distribution) that satisfies the symbols 5 to 8. When the particle size satisfies this condition, the surface area of the powder is not too large and the increase in viscosity is suppressed, and the aggregation of the fine powder is suppressed and the increase in viscosity may be suppressed. For this reason, soldering to finer components becomes possible.

≪Flux≫
The flux used for the solder paste of the present embodiment contains a thixotropic agent, an aromatic guanidine compound, rosin, an organic acid, and a solvent.

  Examples of the thixotropic agent used in the present embodiment include amide compounds, ester compounds, sorbitol-based thixotropic agents, and the like.

Examples of the amide compound as a thixotropic agent include monoamide, bisamide, and polyamide.
For example, such amide compounds include lauric amide, palmitic amide, stearic amide, behenic amide, hydroxystearic amide, saturated fatty amide, oleic amide, erucamide, unsaturated fatty amide, p-toluamide, p-toluamide, Monoamides such as toluenemethane amide, aromatic amide, hexamethylenehydroxystearic amide, substituted amide, methylolstearic amide, methylolamide, fatty acid ester amide; methylenebisstearic amide, ethylenebislauric amide, ethylenebishydroxy fatty acid (C 6-24 carbon number of fatty acid) amide, ethylenebishydroxystearic acid amide, saturated fatty acid bisamide, methylenebisoleic acid amide, unsaturated fatty acid bisamide, m-xylylenebis Bisamides such as aramide and aromatic bisamide; saturated fatty acid polyamide, unsaturated fatty acid polyamide, aromatic polyamide, 1,2,3-propanetricarboxylic acid tris (2-methylcyclohexylamide), cyclic amide oligomer, acyclic amide oligomer And the like.

  The cyclic amide oligomer is an amide oligomer in which a dicarboxylic acid and a diamine are cyclically polycondensed, an amide oligomer in which a tricarboxylic acid and a diamine are cyclically polycondensed, an amide oligomer in which a dicarboxylic acid and a triamine are cyclically polycondensed, and a tricarboxylic acid. Oligomer obtained by cyclic polycondensation of diamine and triamine, amide oligomer obtained by cyclic polycondensation of dicarboxylic acid and tricarboxylic acid and diamine, amide oligomer obtained by cyclic polycondensation of dicarboxylic acid and tricarboxylic acid and triamine, dicarboxylic acid and diamine Amide oligomers obtained by cyclic polycondensation of triamine and triamine, amide oligomers obtained by cyclic polycondensation of tricarboxylic acid and diamine and triamine, amide oligomers obtained by cyclic polycondensation of dicarboxylic acid and tricarboxylic acid with diamine and triamine Goma, and the like.

  When the non-cyclic amide oligomer is an amide oligomer in which a monocarboxylic acid and a diamine and / or a triamine are non-cyclically polycondensed, the amide in which a dicarboxylic acid and / or a tricarboxylic acid and a monoamine are non-cyclically polycondensed is used. For example, it may be an oligomer. When the amide oligomer contains a monocarboxylic acid or a monoamine, the monocarboxylic acid or the monoamine functions as terminal molecules and becomes an acyclic amide oligomer having a reduced molecular weight. In addition, when the acyclic amide oligomer is an amide compound in which a dicarboxylic acid and / or a tricarboxylic acid and a diamine and / or a triamine are acyclicly polycondensed, the acyclic amide oligomer becomes a noncyclic high molecular amide polymer. Furthermore, the acyclic amide oligomer also includes an amide oligomer in which a monocarboxylic acid and a monoamine are acyclicly condensed.

  Examples of the ester compound as a thixotropic agent include castor hardened oil.

  Examples of the sorbitol thixotropic agent include dibenzylidene sorbitol, bis (4-methylbenzylidene) sorbitol, (D-) sorbitol, monobenzylidene (-D-) sorbitol, mono (4-methylbenzylidene)-(D-) sorbitol. And the like.

One or more thixotropic agents can be used.
The thixotropic agent preferably contains at least one selected from the group consisting of an amide compound and an ester compound.
The content of the thixotropic agent is preferably from 0.1 to 15.0% by mass, more preferably from 0.2% by mass to 10% by mass, based on the total amount of the entire flux.

  It is preferable to use a compound containing at least one selected from the group consisting of polyamide, bisamide and monoamide as the amide compound. The flux of the present embodiment preferably contains the amide compound in an amount of from 0.1% by mass to 15% by mass, more preferably from 0.2% by mass to 10% by mass, based on the total amount of the entire flux. preferable.

  It is preferable to use a compound containing a castor hardened oil as the ester compound. The flux of the present embodiment preferably contains the ester compound in an amount of 0.2% by mass or more and 10% by mass or less, more preferably 0.5% by mass or more and 6% by mass or less, based on the total amount of the entire flux. preferable.

Examples of the aromatic guanidine compound used in the present embodiment include diphenylguanidine, ditolylguanidine, and the like.
As the aromatic guanidine compound, one type may be used alone, or two or more types may be used in combination.
The aromatic guanidine compound is preferably at least one selected from the group consisting of diphenylguanidine and ditolylguanidine, and more preferably contains diphenylguanidine.
The flux of the present embodiment preferably contains the aromatic guanidine compound in an amount of 0.2% by mass or more and 15% by mass or less, more preferably 0.5% by mass or more and 7.0% by mass or less of the aromatic guanidine compound. .

  Examples of the rosin used in the present embodiment include natural rosin, derivatives obtained from the natural rosin, and the like. Examples of the natural rosin include gum rosin, wood rosin, and tall oil rosin. Examples of the derivative include purified rosin and modified rosin. Examples of the modified rosin include hydrogenated rosin, polymerized rosin, disproportionated rosin, acid-modified rosin, rosin ester, phenol-modified rosin, and α, β unsaturated carboxylic acid-modified products (acrylated rosin, maleated rosin, fumarated rosin, Acrylic acid-modified hydrogenated rosin, etc.), and purified, hydrogenated and disproportionated products of the polymerized rosin, and purified, hydrogenated and disproportionated products of the α, β unsaturated carboxylic acid modified product, One or more of these can be used.

  The flux of the present embodiment preferably contains rosin in a range of 15% to 70% by mass, and more preferably 35% to 60% by mass of rosin.

  Examples of the organic acid used in the present embodiment include glutaric acid, adipic acid, azelaic acid, eicosane diacid, citric acid, glycolic acid, succinic acid, salicylic acid, diglycolic acid, dipicolinic acid, dibutylaniline diglycolic acid, and suberin. Acid, sebacic acid, thioglycolic acid, terephthalic acid, dodecanedioic acid, parahydroxyphenylacetic acid, picolinic acid, phenylsuccinic acid, phthalic acid, fumaric acid, maleic acid, malonic acid, lauric acid, benzoic acid, tartaric acid, isocyanuric acid Tris (2-carboxyethyl), glycine, 1,3-cyclohexanedicarboxylic acid, 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (hydroxymethyl) butanoic acid, 2,3-dihydroxybenzoic acid, 2,4-diethylglutaric acid, 2-quinolinecarboxylic acid, 3 Hydroxybenzoic acid, malic acid, p- anisic acid, stearic acid, 12-hydroxystearic acid, oleic acid, linoleic acid, and linolenic acid.

Examples of the organic acid include dimer acid, trimer acid, hydrogenated dimer acid which is a hydrogenated product obtained by adding hydrogen to dimer acid, and hydrogenated trimer acid which is a hydrogenated product obtained by adding hydrogen to trimer acid.
For example, dimer acid which is a reaction product of oleic acid and linoleic acid, trimer acid which is a reaction product of oleic acid and linoleic acid, dimer acid which is a reaction product of acrylic acid, trimer acid which is a reaction product of acrylic acid, and methacrylic acid Dimer acid, which is a reactant of methacrylic acid, dimer acid which is a reactant of acrylic acid and methacrylic acid, trimer acid which is a reactant of acrylic acid and methacrylic acid, and a reactant of oleic acid Certain dimer acids, trimer acid which is a reaction product of oleic acid, dimer acid which is a reaction product of linoleic acid, trimer acid which is a reaction product of linoleic acid, dimer acid which is a reaction product of linolenic acid, and a reaction product of linolenic acid Certain trimer acids, dimer acid which is a reaction product of acrylic acid and oleic acid, trimer acid which is a reaction product of acrylic acid and oleic acid, Dimer acid which is a reaction product of lylic acid and linoleic acid, trimer acid which is a reaction product of acrylic acid and linoleic acid, dimer acid which is a reaction product of acrylic acid and linolenic acid, and a trimer which is a reaction product of acrylic acid and linolenic acid Acid, dimer acid which is a reaction product of methacrylic acid and oleic acid, trimer acid which is a reaction product of methacrylic acid and oleic acid, dimer acid which is a reaction product of methacrylic acid and linoleic acid, a reaction product of methacrylic acid and linoleic acid Certain trimer acid, dimer acid which is a reaction product of methacrylic acid and linolenic acid, trimer acid which is a reaction product of methacrylic acid and linolenic acid, dimer acid which is a reaction product of oleic acid and linolenic acid, reaction of oleic acid and linolenic acid Dimer acid, a reaction product of linoleic acid and linolenic acid, and a reaction product of linoleic acid and linolenic acid Trimer acid that, hydrogenated dimer acid which is a hydrogenation product of the dimer acid as described above, hydrogenated trimer acid, and the like are hydrogenated products of the trimer acid described above.

One type of organic acid may be used alone, or two or more types may be used in combination.
As the organic acid, it is preferable to use at least one selected from the group consisting of succinic acid, glutaric acid, adipic acid and hydrogenated dimer acid.
The flux of the present embodiment preferably contains the organic acid in an amount of 0.1% by mass or more and 15% by mass or less, more preferably 0.2% by mass or more and 10% by mass or less based on the total amount of the entire flux.

  The flux of the present embodiment preferably contains the organic acid and the aromatic guanidine compound in a total amount of 2% by mass or more and 18% by mass or less, more preferably 3% by mass or more and 18% by mass or less.

Examples of the solvent used in the present embodiment include water, alcohol solvents, glycol ether solvents, terpineols, and the like.
Examples of alcohol solvents include isopropyl alcohol, 1,2-butanediol, isobornylcyclohexanol, 2,4-diethyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 2,5 -Dimethyl-2,5-hexanediol, 2,5-dimethyl-3-hexyne-2,5-diol, 2,3-dimethyl-2,3-butanediol, 1,1,1-tris (hydroxymethyl) Ethane, 2-ethyl-2-hydroxymethyl-1,3-propanediol, 2,2′-oxybis (methylene) bis (2-ethyl-1,3-propanediol), 2,2-bis (hydroxymethyl) -1,3-propanediol, 1,2,6-trihydroxyhexane, bis [2,2,2-tris (hydroxymethyl) ethyl] ether 1,1-ethynyl-1-cyclohexanol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, erythritol, threitol, guaiacol glycerol ether, 3,6-dimethyl-4-octyne-3,6-diol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol and the like.
As glycol ether solvents, hexyl glycol, hexyl diglycol, 2-ethylhexyl glycol, 2-ethylhexyl diglycol, dimethyl triglycol, dibutyl diglycol, diethylene glycol mono-2-ethylhexyl ether, 2-methylpentane-2,4- Aliphatic glycol ether solvents such as diols, diethylene glycol monohexyl ether, diethylene glycol dibutyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol dimethyl ether; phenyl glycol, phenyl diglycol, benzyl glycol, benzyl diglycol, Aromatic glycol ethers such as ethylene glycol monophenyl ether System solvent and the like.
One or more solvents can be used.

  The flux of the present embodiment may contain components other than a thixotropic agent, an aromatic guanidine compound, rosin, an organic acid and a solvent, such as an amine, a halogen-based activator, an antioxidant, and a resin component other than rosin. Is mentioned.

  Examples of the amine include monoethanolamine, diphenylguanidine, ditolylguanidine, ethylamine, triethylamine, cyclohexylamine, ethylenediamine, triethylenetetramine, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, and 1,2-dimethyl. Imidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methyl Imidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl -2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6- [2'-methylimidazolyl- (1 ')]-ethyl-s-triazine 2,4-diamino-6- [2′-undecylimidazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6- [2′-ethyl-4′-methylimidazolyl- ( 1 ′)]-Ethyl-s-triazine, 2,4-diamino-6- [2′-methylimidazolyl- (1 ′)]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro 1H-pyrrolo [1,2-a] benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline, 2,4-diamino-6-vinyl-s- Triazine, 2,4-diamino-6-vinyl-s-triazine isocyanuric acid adduct, 2,4-diamino-6-methacryloyloxyethyl-s-triazine, epoxy-imidazole adduct, 2-methylbenzimidazole, 2-octyl Benzimidazole, 2-pentylbenzimidazole, 2- (1-ethylpentyl) benzimidazole, 2-nonylbenzimidazole, 2- (4-thiazolyl) benzimidazole, benzimidazole, 2- (2′-hydroxy-5′-) Methylphenyl) benzotriazole 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-amylphenyl) Benzotriazole, 2- (2′-hydroxy-5′-tert-octylphenyl) benzotriazole, 2,2′-methylenebis [6- (2H-benzotriazol-2-yl) -4-tert-octylphenol], 6 -(2-benzotriazolyl) -4-tert-octyl-6'-tert-butyl-4'-methyl-2,2'-methylenebisphenol, 1,2,3-benzotriazole, 1- [N, N-bis (2-ethylhexyl) aminomethyl] benzotriazole, carboxybenzotriazole, 1- [N, N-bis (2-ethyl Xyl) aminomethyl] methylbenzotriazole, 2,2 ′-[[(methyl-1H-benzotriazol-1-yl) methyl] imino] bisethanol, 1- (1 ′, 2′-dicarboxyethyl) benzotriazole , 1- (2,3-dicarboxypropyl) benzotriazole, 1-[(2-ethylhexylamino) methyl] benzotriazole, 2,6-bis [(1H-benzotriazol-1-yl) methyl] -4- Examples thereof include methylphenol, 5-methylbenzotriazole, 5-phenyltetrazole, and triazole.

The amines may be used alone or as a mixture of two or more.
The flux of the present embodiment preferably contains 0% by mass or more and 8% by mass or less, more preferably 1% by mass or more and 6% by mass or less.

The flux of the present embodiment may contain a halogen-based activator.
Examples of the halogen-based activator include amine hydrohalides, organic halogen compounds, and the like.

Amine hydrohalide is a compound obtained by reacting an amine with hydrogen halide.
As the amine of the amine hydrohalide, the above-mentioned amines can be used, and examples thereof include ethylamine, cyclohexylamine, ethylenediamine, triethylamine, diphenylguanidine, ditolylguanidine, methylimidazole, and 2-ethyl-4-methylimidazole. Can be Examples of the hydrogen halide include hydrides of chlorine, bromine, iodine, and fluorine (hydrogen chloride, hydrogen bromide, hydrogen iodide, hydrogen fluoride). Further, a borofluoride may be contained in place of the amine hydrohalide or in combination with the amine hydrohalide, and examples of the borofluoride include borofluoric acid.
Examples of the amine hydrohalide include aniline hydrogen chloride, cyclohexylamine hydrogen chloride, aniline hydrogen bromide, diphenylguanidine hydrogen bromide, ditolylguanidine hydrogen bromide, and ethylamine hydrogen bromide.

  Examples of the organic halogen compound include trans-2,3-dibromo-2-butene-1,4-diol, triallyl isocyanurate hexabromide, 1-bromo-2-butanol, 1-bromo-2-propanol, 3-bromo -1-propanol, 3-bromo-1,2-propanediol, 1,4-dibromo-2-butanol, 1,3-dibromo-2-propanol, 2,3-dibromo-1-propanol, 2,3- Dibromo-1,4-butanediol, 2,3-dibromo-1,4-butanediol, 2,3-dibromo-2-butene-1,4-diol, tris (2,3-dibromopropyl) isocyanurate, Chlorendic anhydride and the like can be mentioned.

  The flux of the present embodiment preferably contains 0% by mass or more and 8% by mass or less, more preferably 1% by mass or more and 6% by mass or less of an organic halogen compound; and 0% by mass or more of an amine hydrohalide. It is preferably contained in an amount of 8% by mass or less, more preferably 0.5% by mass or more and 5% by mass or less.

Examples of the antioxidant include 2,2′-methylenebis [6- (1-methylcyclohexyl) -p-cresol], a hindered phenol-based antioxidant, and the like.
The flux of the present embodiment preferably contains 0% by mass to 8% by mass of antioxidant, more preferably 1% by mass to 6% by mass.

The flux of the present embodiment may contain a resin component other than rosin.
Examples of the resin component other than rosin include acrylic resin, terpene resin, modified terpene resin, terpene phenol resin, modified terpene phenol resin, styrene resin, modified styrene resin, xylene resin, modified xylene resin, and the like.
As the modified terpene resin, an aromatic modified terpene resin, a hydrogenated terpene resin, a hydrogenated aromatic modified terpene resin, or the like can be used. As the modified terpene phenol resin, a hydrogenated terpene phenol resin or the like can be used. As the modified styrene resin, a styrene acrylic resin, a styrene maleic resin, or the like can be used. Examples of the modified xylene resin include a phenol-modified xylene resin, an alkylphenol-modified xylene resin, a phenol-modified resol-type xylene resin, a polyol-modified xylene resin, and a polyoxyethylene-added xylene resin.

The flux of the present embodiment may further contain a surfactant.
Examples of the surfactant include polyoxyalkylene acetylene glycols, polyoxyalkylene glyceryl ether, polyoxyalkylene alkyl ether, polyoxyalkylene ester, polyoxyalkylene alkylamine, and polyoxyalkylene alkylamide.

Flux content:
The content of the flux is preferably 5 to 95% by mass, more preferably 5 to 15% by mass, based on the total mass of the solder paste.
When the content of the flux in the solder paste is within this range, the effect of suppressing viscosity increase caused by the solder powder is sufficiently exhibited. In addition, the wetting speed of the solder on the metal surface of the joining object can be more easily increased.

  It is preferable that the solder paste of the present embodiment further contains zirconium oxide powder. By containing zirconium oxide, it is possible to suppress an increase in the viscosity of the paste due to aging. This is presumed to be due to the inclusion of zirconium oxide to maintain the oxide film thickness on the surface of the solder powder before it was introduced into the flux. Details are unknown, but are presumed as follows. Normally, since the active component of the flux has a slight activity even at room temperature, the surface oxide film of the solder powder is thinned by reduction, which causes the powder to agglomerate. Therefore, it is presumed that by adding zirconium oxide powder to the solder paste, the active component of the flux reacts preferentially with the zirconium oxide powder, and is maintained to such an extent that the oxide film on the surface of the solder powder does not aggregate.

  In order to sufficiently exhibit such effects, the content of the zirconium oxide powder in the solder paste is preferably 0.05 to 20.0% by mass based on the total mass of the solder paste. When the content is 0.05% by mass or more, the above function and effect can be exhibited, and when the content is 20.0% by mass or less, the content of the metal powder can be secured, and the effect of preventing thickening is exhibited. Can be. The content of the zirconium oxide powder is more preferably 0.05 to 10.0% by mass, and still more preferably 0.1 to 3% by mass.

The particle diameter of the zirconium oxide powder in the solder paste is preferably 5 μm or less. When the particle size is 5 μm or less, the printability of the paste can be maintained. The lower limit of the particle size is not particularly limited, but may be 0.5 μm or more.
The particle diameter of the zirconium oxide powder is determined by taking an SEM photograph of the zirconium oxide powder, obtaining an equivalent diameter of a projected circle by image analysis for each powder having a diameter of 0.1 μm or more, and setting the average value thereof.

  The shape of the zirconium oxide is not particularly limited, but a different shape has a large contact area with the flux and has an effect of suppressing thickening. When the shape is spherical, good printability as a paste is obtained because good fluidity is obtained. What is necessary is just to select a shape suitably according to a desired characteristic.

Manufacturing method of solder paste:
The solder paste of the present embodiment is manufactured by a method generally used in the art.
First, in the production of the solder powder, a known method such as a dropping method of dropping a molten solder material to obtain particles, a spraying method of centrifugal spraying, and a method of pulverizing bulk solder material can be adopted. In the dropping method or the spraying method, the dropping or spraying is preferably performed in an inert atmosphere or a solvent in order to form particles. Then, the above components can be heated and mixed to prepare a flux, and the above-mentioned solder powder is introduced into the flux, followed by stirring and mixing to produce the flux.

<Solder paste flux>
The solder paste flux of the present embodiment is used for a solder paste.
Such a flux contains a thixotropic agent, an aromatic guanidine compound, rosin, an organic acid, and a solvent.
The solder paste in which such a flux is used includes: As: 25 to 300 mass ppm, Pb: more than 0 mass ppm to 5100 mass ppm, and Sb: more than 0 mass ppm to 3000 mass ppm, and Bi: more than 0 mass ppm to 10,000 mass ppm. At least one of the following, and the remainder has an alloy composition composed of Sn, and contains a solder powder containing a solder alloy satisfying the following formulas (1) and (2).
275 ≦ 2As + Sb + Bi + Pb (1)
0.01 ≦ (2As + Sb) / (Bi + Pb) ≦ 10.00 (2)
In the above formulas (1) and (2), As, Sb, Bi and Pb each represent the content (ppm by mass) in the alloy composition.

<Example of operation and effect of flux and solder paste of the present embodiment>
In the present embodiment, a flux having an aromatic guanidine compound together with a thixotropic agent, a rosin, an organic acid and a solvent is employed. In addition, a solder powder containing a solder alloy having an alloy composition in which specific elements (at least one of As, Pb and Sb and Bi) are used together with Sn at a specific ratio is employed. The solder paste in which the flux and the solder powder are combined hardly causes a change with time such as an increase in viscosity, has excellent wettability of molten solder, and exhibits high mechanical properties. Further, according to this solder paste, the wetting speed of the solder on the metal surface of the joining object can be increased.

  The joining method using the solder paste according to the present invention may be performed according to an ordinary method using, for example, a reflow method. The melting temperature of the solder alloy in the case of performing the flow soldering may be approximately 20 ° C. higher than the liquidus temperature. In the case of joining using the solder alloy in the present embodiment, it is preferable to consider the cooling rate at the time of solidification from the viewpoint of making the structure finer. For example, the solder joint is cooled at a cooling rate of 2 to 3 ° C./s or more. Other joining conditions can be appropriately adjusted according to the alloy composition of the solder alloy.

  For the solder alloy in the present embodiment, a low α-dose alloy can be manufactured by using a low α-dose material as a raw material. When such a low α-dose alloy is used for forming solder bumps around a memory, it is possible to suppress soft errors.

  Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

First, a solder powder having the alloy composition shown in Tables 1 to 6 and having a size (particle size distribution) satisfying the symbol 4 in the powder size classification (Table 2) in JIS Z 3284-1: 2014 (Test Examples 1 to 108; Examples 201 to 278) were produced.
However, Test Examples 1, 5 to 11, 13 to 15, 18, 19, 23 to 29, 31 to 33, 36, 37, 41 to 47, 49 to 51, 54, 55, 59 to 65, 67 to 69, The solder powders 72, 73, 77 to 83, 85 to 87, 90, 91, 95 to 101, 103 to 105, and 108 correspond to the solder powders specified in the present invention.

  6 parts by mass of a polyamide as a thixotropic agent, 3 parts by mass of diphenylguanidine as an aromatic guanidine compound, 50 parts by mass of polymerized rosin as a rosin, 0.5 part by mass of adipic acid as an organic acid, and tetraethylene glycol monomethyl ether 40 as a solvent And 0.5 parts by mass to prepare a flux (a flux having the composition shown in Example 1).

  As the polyamide, an aliphatic polyamide was used.

  The above-described flux having the composition shown in Example 1 and the solder powder having the alloy compositions of the respective examples shown in Tables 1 to 6 were mixed to prepare a solder paste. The mass ratio of the flux to the solder powder was set to flux: solder powder = 11: 89.

  With respect to the case where the solder powder of each example was used, the change with time of the viscosity of the solder paste was measured. In addition, the liquidus temperature and the solidus temperature of the solder powder were measured. Furthermore, the wettability was evaluated using the solder paste immediately after the preparation. Details are as follows.

<Evaluation of change over time in viscosity of solder paste>
(1) Verification method The viscosity of each solder paste immediately after preparation was measured using PCU-205 manufactured by Malcom Corporation at a rotation speed of 10 rpm at 25 ° C. for 12 hours in the air.

(2) Criteria 基準: The viscosity after 12 hours is 1.2 times or less compared to the viscosity when 30 minutes have passed since the preparation of the solder paste.
×: The viscosity after 12 hours exceeds 1.2 times the viscosity when 30 minutes have passed since the preparation of the solder paste.

<Evaluation of ΔT>
(1) Verification method Regarding the solder powder before mixing with the flux, DSC measurement was performed using SII Nano Technology Co., Ltd., model number: EXSTAR DSC7020 at a sample amount of about 30 mg and a heating rate of 15 ° C./min. Then, a solidus temperature and a liquidus temperature were obtained. ΔT was determined by subtracting the solidus temperature from the obtained liquidus temperature.

(2) Criteria 〇: ΔT is 10 ° C. or less.
×: ΔT exceeds 10 ° C.

<Evaluation of wettability>
Each solder paste immediately after the preparation was printed on a Cu plate, heated from 25 ° C. to 260 ° C. in a N ₂ atmosphere at a rate of 1 ° C./s in a reflow furnace, and then cooled to room temperature. The wettability was evaluated by observing the appearance of the cooled solder bumps with an optical microscope.

〇: When no unmelted solder powder is observed.
×: When solder powder not completely melted was observed.

<Comprehensive evaluation>
〇: In Tables 1 to 6, each of the changes over time, ΔT, and wettability were evaluated as 〇.
X: In Tables 1 to 6, at least one of the evaluations of the change over time, ΔT, and wettability was x.

  The evaluation results are shown in Tables 1 to 6.

  As shown in Tables 1 to 6, when the solder powders of Test Examples 1 to 108 were used, it was confirmed that any of the alloy compositions exhibited a thickening suppressing effect, a narrowing of ΔT, and excellent wettability. Was.

  On the other hand, when the solder powders of Test Examples 201, 214, 227, 240, 253, and 266 were used, As did not contain As, and the result that the effect of suppressing thickening was not exhibited was shown.

  When the solder powders of Test Examples 202, 215, 228, 241, 254, and 267 were used, the results showed that the effect of suppressing thickening was not exhibited because the formula (1) was less than the lower limit.

  When the solder powders of Test Examples 203, 216, 229, 242, 255 and 268 were used, the result was inferior in wettability because the expression (2) exceeded the upper limit.

  When the solder powders of Test Examples 204, 205, 217, 218, 230, 231, 243, 244, 256, 257, 269, and 270 were used, the As content and the formula (2) exceeded the upper limits, so that wetting occurred. Inferior results were obtained.

  When the solder powders of Test Examples 206 to 208, 219 to 221, 232 to 234, 245 to 247, 258 to 260, and 271 to 273 are used, since the Sb content exceeds the upper limit, poor wettability results. Indicated.

  When the solder powders of Test Examples 209, 210, 222, 223, 235, 236, 248, 249, 261, 262, 274, and 275 were used, ΔT exceeded 10 ° C. because the Bi content exceeded the upper limit. The results are shown.

  When the solder powders of Test Examples 211, 213, 224, 226, 237, 239, 250, 252, 263, 265, 276, and 278 were used, ΔT exceeded 10 ° C. because the Pb content exceeded the upper limit. The results are shown.

  When the solder powders of Test Examples 212, 225, 238, 251, 264, and 277 were used, Bi and Pb were not contained, and the expression (2) was not satisfied. As a result, poor wettability was obtained.

  Next, the solder wetting rate (solder wettability) of the solder powder having the alloy composition shown in Test Example 77 was evaluated for the cases where the fluxes shown in Tables 7 to 15 were used. The results are shown in Tables 7 to 15.

<Evaluation of solder wetting rate (solder wettability)>
(1) Verification Method An evaluation test of the solder wetting speed (solder wettability) was performed as follows.
According to the method of the meniscograph test, a copper plate having a width of 5 mm, a length of 25 mm and a thickness of 0.5 mm was oxidized at 150 ° C. for 1 hour to obtain a copper oxide plate as a test plate, and a Solder Checker SAT-5200 was used as a test device. (Manufactured by RHESCA) and the following evaluation was performed using a solder powder having the alloy composition shown in Test Example 77 as the solder.
First, the test plate was immersed in 5 mm of the flux of each example measured in a beaker, and the flux was applied to the test plate. Subsequently, after applying the flux, the test plate to which the flux was applied was immediately immersed in a solder bath having the alloy composition shown in Test Example 77, and a zero cross time (sec) was obtained.
Subsequently, the measurement was performed five times for the flux of each example, and the average value of the obtained five zero cross times (sec) was calculated. The test conditions were set as follows.
Immersion speed in solder bath: 5 mm / sec (JIS Z 3198-4: 2014)
Immersion depth in solder bath: 2 mm (JIS Z 3198-4: 2014)
Immersion time in solder bath: 10 sec (JIS Z 3198-4: 2014)
Solder bath temperature: 245 ° C (JIS C 60068-2-69: 2019 Annex B)
The shorter the average value of the zero cross time (sec), the higher the wetting speed, which means that the solder wettability is better.

(2) Criteria 基準: The average value of the zero cross time (sec) is 6 seconds or less.
X: The average value of the zero cross time (sec) exceeds 6 seconds.

  The evaluation results are shown in Tables 7 to 15.

  In the table, aliphatic polyamide was used as the polyamide. Hexamethylenebishydroxystearic acid amide was used as the bisamide. P-Toluamide was used as the monoamide.

  As shown in Example 1, when the flux having the composition shown in Example 1 was used for the solder powder having the alloy composition shown in Test Example 77, the solder wettability increased, and the solder wettability was reduced. A sufficient effect was obtained (see Table 7).

  As shown in Examples 1 and 2, even when the type of the solvent was changed, the solder wetting speed was increased, and a sufficient effect on the solder wettability was obtained.

  As shown in Examples 1, 3 to 5, and 7, changing the type of the aromatic guanidine compound, combining a plurality of types of aromatic guanidine compounds, and changing the amount of the aromatic guanidine compound also increase the solder wetting rate. Thus, a sufficient effect on the solder wettability was obtained.

  As shown in Examples 6 and 8, by combining a plurality of types of organic acids and changing the amount of the organic acids, the wetting speed of the solder was increased, and a sufficient effect on the solder wettability was obtained.

  As shown in Examples 9 to 12, changing the type of amide compound as a thixotropic agent, or combining a plurality of types of amide compounds also increases the wetting speed of the solder and provides a sufficient effect on the solder wettability. Was done.

  As shown in Example 13, the use of an ester compound in addition to the amide compound as the thixotropic agent also increased the solder wetting rate, and a sufficient effect on solder wettability was obtained.

  As shown in Examples 14 to 18, changing the type of the organic acid, combining a plurality of types of organic acids, and changing the amount of the organic acid also increase the wetting speed of the solder, which is sufficient for the solder wettability. The effect was obtained.

  As shown in Examples 19 to 22, changing the type of rosin and combining a plurality of types of rosins also increased the solder wetting speed, and a sufficient effect on the solder wettability was obtained.

As shown in Examples 23 and 24, changing the type of amine also increased the solder wetting speed, and a sufficient effect on solder wettability was obtained.
As shown in Examples 25 to 27, the inclusion of an amine hydrohalide, an organic halogen compound or an antioxidant also increased the wetting rate of the solder, and a sufficient effect on the solder wettability was obtained. .
As shown in Example 28, even when the amount of the organic acid was reduced, the inclusion of the amine, the halogen-based activator and the antioxidant increased the solder wetting speed and had a sufficient effect on the solder wettability. was gotten.

  As shown in Examples 29 to 30, changing the amount of rosin also increased the solder wetting speed, and a sufficient effect on solder wettability was obtained.

  As shown in Examples 31 to 35, when an amide compound and an ester compound are used in combination as a thixotropic agent, by changing the type of organic acid, combining a plurality of types of organic acids, or changing the amount of the organic acid, The wetting speed of the solder was increased, and a sufficient effect on the solder wettability was obtained.

  As shown in Examples 36 to 37, when an amide compound and an ester compound are used in combination as a thixotropic agent, changing the amount of rosin also increases the solder wetting speed, which is sufficient for solder wettability. The effect was obtained.

  As shown in Examples 38 to 41, when an amide compound and an ester compound are used in combination as a thixotropic agent, the type of rosin is changed, and even if a plurality of types of rosins are combined, the wetting speed of the solder increases, A sufficient effect on wettability was obtained.

As shown in Examples 42 to 43, when an amide compound and an ester compound are used in combination as a thixotropic agent, changing the type of amine also increases the wetting speed of the solder, which is sufficient for solder wettability. The effect was obtained.
As shown in Examples 44 to 46, when an amide compound and an ester compound are used in combination as a thixotropic agent, even when an amine hydrohalide, an organic halogen compound or an antioxidant is contained, the solder wetting rate is reduced. As a result, a sufficient effect on solder wettability was obtained.
As shown in Example 47, when an amide compound and an ester compound are used in combination as a thixotropic agent, even when the amount of an organic acid is reduced, the presence of an amine, a halogen-based activator, and an antioxidant enables the soldering. Has a high wettability, and has a sufficient effect on solder wettability.

  As shown in Examples 48 to 52, when an amide compound and an ester compound are used in combination as a thixotropic agent, changing the mass ratio between the amide compound and the ester compound also increases the wetting rate of the solder and increases the solder wetting. A sufficient effect was obtained on the properties.

As shown in Examples 53 to 55, even when the amount of the amide compound as the thixotropic agent was reduced, the solder wetting speed was increased, and a sufficient effect on the solder wettability was obtained.
As shown in Example 56, even when the ester compound was used alone as the thixotropic agent, the solder wetting rate was increased, and a sufficient effect on the solder wettability was obtained.

  As shown in Examples 57 and 58, even when the amount of the aromatic guanidine compound was reduced, the wetting speed of the solder was increased, and a sufficient effect on the solder wettability was obtained.

  As shown in Example 59, changing the kind of organic acid, combining a plurality of kinds of organic acids, changing the amount of organic acid, changing the kind of aromatic guanidine compound, changing the kind of amide compound, changing the amount of amide compound Also, by changing the amount, changing the amount of the ester compound, and changing the type of the solvent, the wettability of the solder was increased, and a sufficient effect on the solder wettability was obtained.

  On the other hand, as shown in Comparative Example 1, when the aromatic guanidine compound was not contained, the wetting speed of the solder was slower than when the aromatic guanidine compound was contained, and a sufficient effect on the solder wettability was obtained. I couldn't.

Next, when the solder powder having the alloy composition shown in Test Example 77 was changed to the solder powder having each alloy composition shown in Test Examples 1 to 76 and Test Examples 78 to 108, respectively, Evaluation of solder wettability).
As a result, when the flux having the composition shown in Example 1 was used for each of the solder powders of Test Examples 1 to 76 and Test Examples 78 to 108, in each case, the solder powder of Test Example 1 was used. Similarly to the above, the wetting speed of the solder was increased, and a sufficient effect on the solder wettability was obtained.
For the solder powders of Test Examples 1 to 76 and Test Examples 78 to 108, the zero cross times when the flux having the composition shown in Example 1 was used were all the solder powders of Test Examples 201 to 278. Was significantly shorter than the zero cross time when the flux having the composition shown in Example 1 was used.

Next, each of the solder powders having the respective alloy compositions shown in Test Examples 1 to 76, Test Examples 78 to 108 and Test Examples 201 to 278, and the flux having the respective compositions shown in Examples 2 to 58 and Comparative Example 1 Each was mixed with (solder powder: flux = 89: 11 (mass ratio)) to produce a solder paste.
As a result, in the case of a solder paste obtained by combining the solder powders of Test Examples 1 to 76 and Test Examples 78 to 108 with the fluxes of Examples 2 to 58, the solder paste using the flux having the composition shown in Example 1 As in the case, it was confirmed that the composition exhibited an effect of suppressing thickening, narrowing of ΔT, and excellent wettability.

  Further, the zero-cross times when each of the solder powders of Test Examples 1 to 76 and Test Examples 78 to 108 and each of the fluxes having the compositions shown in Examples 2 to 58 were mixed, It was significantly shorter than the zero cross time when the flux of Example 1 was used.

According to the present invention, it is possible to provide a solder paste in which a change with time, such as an increase in viscosity, does not easily occur, and the rate of wetting of the solder to the metal surface of the joining object is increased.
Further, according to the present invention, it is possible to provide a solder paste flux having a high solder wettability with respect to a metal surface of an object to be joined and having good solder wettability.

Claims (17)

Ru solder powder and the flux Tona, a solder paste,
The solder powder contains at least one of As: 25 to 300 mass ppm, Pb: more than 0 mass ppm to 5,100 mass ppm, and Sb: more than 0 mass ppm to 3000 mass ppm, and Bi: more than 0 mass ppm to 10,000 mass ppm. , and the balance has an alloy composition consisting of Sn, made of solder alloy which satisfies the following formula (1) and (2),
The flux seen containing a thixotropic agent, and an aromatic guanidine compound, a rosin, an organic acid, and a solvent,
A solder paste containing the aromatic guanidine compound in an amount of 0.5% by mass or more and 15% by mass or less based on the total amount of the flux .
275 ≦ 2As + Sb + Bi + Pb (1)
0.01 ≦ (2As + Sb) / (Bi + Pb) ≦ 10.00 (2)
In the above formulas (1) and (2), As, Sb, Bi and Pb each represent the content (ppm by mass) in the alloy composition. The solder paste according to claim 1, wherein the alloy composition satisfies the following expression (1a).
275 ≦ 2As + Sb + Bi + Pb ≦ 25200 (1a)
In the above formula (1a), As, Sb, Bi and Pb each represent the content (mass ppm) in the alloy composition. The solder paste according to claim 1, wherein the alloy composition satisfies the following expression (1b).
275 ≦ 2As + Sb + Bi + Pb ≦ 5300 (1b)
In the above formula (1b), As, Sb, Bi and Pb each represent the content (mass ppm) in the alloy composition. The solder paste according to any one of claims 1 to 3, wherein the alloy composition satisfies the following expression (2a).
0.31 ≦ (2As + Sb) / (Bi + Pb) ≦ 10.00 (2a)
In the above formula (2a), As, Sb, Bi and Pb each represent the content (mass ppm) in the alloy composition.   The solder paste according to any one of claims 1 to 4, wherein the alloy composition contains at least one of Ag: 0 to 4% by mass and Cu: 0 to 0.9% by mass.   The solder paste according to any one of claims 1 to 5, wherein the aromatic guanidine compound is at least one selected from the group consisting of diphenylguanidine and ditolylguanidine. The solder paste according to any one of claims 1 to 6 , wherein the total amount of the organic acid and the aromatic guanidine compound is 3% by mass or more and 18% by mass or less based on the total amount of the flux . The solder paste according to any one of claims 1 to 7, wherein the content of the thixotropic agent is 0.1% by mass or more and 15.0% by mass or less based on the total amount of the entire flux.   The solder paste according to claim 1, wherein the thixotropic agent contains at least one selected from the group consisting of an amide compound and an ester compound.   The solder paste according to claim 9, wherein the amide compound includes at least one selected from the group consisting of polyamide, bisamide and monoamide. The solder paste according to claim 9, wherein the thixotropic agent contains at least the amide compound, and contains the amide compound in an amount of 0.1% by mass or more and 15% by mass or less based on the total amount of the flux .   The solder paste according to any one of claims 9 to 11, wherein the ester compound includes a hardened castor oil. The solder according to any one of claims 9 to 12, wherein the thixotropic agent contains at least the ester compound, and contains the ester compound in an amount of 0.2% by mass or more and 10% by mass or less based on the total amount of the entire flux. paste. The solder paste according to any one of claims 1 to 13, wherein the rosin is contained in an amount of 15% by mass or more and 70% by mass or less based on the total amount of the entire flux .   The solder paste according to any one of claims 1 to 14, wherein the organic acid includes at least one selected from the group consisting of succinic acid, glutaric acid, adipic acid and hydrogenated dimer acid. The solder paste according to claim 15, wherein the organic acid is contained in an amount of 0.1% by mass or more and 15% by mass or less based on the total amount of the entire flux . Further, based on the total amount of the entire flux, the amine is 0% to 8% by mass, the organic halogen compound is 0% to 8% by mass, the amine hydrohalide is 0% to 8% by mass, The solder paste according to any one of claims 1 to 16, comprising 0 mass% to 8 mass% of an antioxidant.