JP6643691B2 - Solder paste - Google Patents

Description

  The present invention relates to a solder paste.

  Bonding and assembling of electronic components to a substrate of an electronic device are often performed by soldering using a solder paste from the viewpoint of cost and reliability.

  As a method of applying a solder paste to a substrate of an electronic device, for example, there is a method of using screen printing using a metal mask. In this case, it is necessary to appropriately adjust the viscosity of the solder paste in order to secure printability of the solder paste. However, the solder paste has poor storage stability, and as a result, the viscosity of the solder paste may increase with time.

Further, in the solder material forming the solder paste, the difference between the liquidus temperature (T _L) and the solidus temperature _{(T S) (ΔT = T} L -T S) increases, for example, the electronic device substrate When a solder paste is applied and solidified, the structure of the solder material is likely to be non-uniform, and as a result, reliability in the future may decrease.

  Further, in general, a solder material is required to have a property of spreading on a metal of an electronic component when melted (wettability). However, when an element such as P, Ge, or Ga is added, the solder material The wettability of the film decreases. Poor wettability of the solder material causes poor soldering.

  Patent Literature 1 discloses a solder paste containing a lead-free solder powder, a rosin resin, an activator, a solvent, and a hindered phenol compound. This document, the combination of hindered phenol compound non-lead-based solder powder, it is disclosed that the deterioration during the reflow of lead-free solder powder and a solder paste layer can be prevented. This document discloses only an example using a lead-free solder powder having a composition of 96.5% by mass of Sn, 3.0% by mass of Ag, and 0.5% by mass of Cu.

JP 2002-283097 A

  However, Patent Literature 1 does not aim at suppressing a rise in viscosity over time or attaining excellent reliability and wettability. For this reason, a solder paste that balances the effect of suppressing viscosity increase, reliability and wettability in a well-balanced manner is desired.

  Accordingly, an object of the present invention is to provide a solder paste capable of achieving a balance between the effect of suppressing thickening, reliability and wettability.

  The present inventors have conducted intensive studies to solve the above-described problems, and as a result, have found that a solder paste composed of a solder material and a flux, wherein the solder material is Sn or a Sn-based alloy and a specific ratio of As, Sb, Bi And Pb, and that the flux contained a hindered phenolic compound could solve the above problems, and completed the present invention.

  That is, the solder paste of the present invention is a solder paste comprising a solder material and a flux, wherein the solder material is Sn or a Sn-based alloy, 20 to 300 mass ppm of As, 0 to 3000 mass ppm of Sb, 0 It contains Bi of 10000 mass ppm and Pb of 0 to 5100 mass ppm (however, the contents of Bi and Pb do not become 0 mass ppm at the same time), and the flux contains a hindered phenol compound. .

  Advantageous Effects of Invention According to the present invention, it is possible to provide a solder paste capable of achieving a balance between a thickening suppression effect, reliability, and wettability.

  Hereinafter, a mode for carrying out the present invention (hereinafter, referred to as “the present embodiment”) will be described. However, the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention.

  In the present specification, the “thickening suppression effect” refers to an effect that, when a solder paste is prepared, a rise in viscosity of the prepared solder paste over time can be suppressed.

  In the present specification, the content of each element can be measured, for example, by analyzing with ICP-AES in accordance with JIS Z3910.

[Solder paste]
The solder paste of the present embodiment is a solder paste composed of a solder material and a flux. The solder material is Sn or a Sn-based alloy, 20 to 300 mass ppm of As, 0 to 3000 mass ppm of Sb, 0 to 10000 mass ppm of Bi, and 0 to 5100 mass ppm of Pb (however, the content of Bi and Pb Are not simultaneously reduced to 0 ppm by mass). However, the content of Bi and Pb does not become 0 mass ppm at the same time, and the fact that two or more types of Sb, Bi and Pb are contained (the content of two or more types exceeds 0 mass ppm) is required. It is also preferable that all of Sb, Bi and Pb are contained (the content of all three is more than 0 mass ppm).

The flux contains a hindered phenol compound. The solder paste of the present embodiment can improve the effect of suppressing thickening by having the above configuration. Further, the solder material constituting the solder paste of the present embodiment has the above-described configuration, so that the difference between the liquidus temperature (T _L ) and the solidus temperature (T _S ) (ΔT = T _L −T _S ) can be reduced. For this reason, for example, even when the solder paste containing the solder material is applied to a substrate of an electronic device and solidified, the solder paste can keep the structure of the solder material uniform. As a result, the solder paste is excellent in reliability such as cycle characteristics. Furthermore, since the solder material constituting the solder paste of the present embodiment has the above-described configuration and is excellent in wettability, it is possible to suppress the occurrence of poor soldering. As described above, the solder paste having the above-described configuration can achieve both a thickening suppressing effect, reliability, and wettability in a well-balanced manner.

(Solder material)
The solder material contains Sn or a Sn-based alloy. Sn or a Sn-based alloy may contain unavoidable impurities.

  Sn, for example, may be a Sn (3N material) having a purity of 99.9% or more, may be a Sn (4N material) having a purity of 99.99% or more, of 99.999% Sn (5N material) having a purity may be used.

  The Sn content may be, for example, 40% by mass or more, 50% by mass or more, 70% by mass or more, or 90% by mass or more based on the entire solder material. There may be.

  Examples of the Sn-based alloy include compositions such as a Sn-Ag alloy, a Sn-Cu alloy, a Sn-Ag-Cu alloy, a Sn-Ag-Cu-Ni-Co alloy, a Sn-In alloy, and a Sn-Sb alloy. Alloys, alloys having the above composition, and alloys to which As, Ag, Cu, In, Ni, Co, Ge, P, Fe, Zn, Al, Ga, and the like are added. The content of Sn in the Sn-based alloy is not particularly limited, and may be, for example, more than 40% by mass.

  The Sn and the Sn-based alloy are preferably Sn, a Sn—Cu alloy, or a Sn—Ag—Cu alloy from the viewpoint of excellent reliability by reducing ΔT. From a similar viewpoint, the Sn-Cu alloy preferably contains more than 0 and 1.0 mass% or less (preferably 0.5 to 1.0 mass%) of Cu, with the balance being Sn. From a similar viewpoint, the Sn-Ag-Cu alloy contains more than 0 to 3.5% by mass (preferably 1.0 to 3.5% by mass) of Ag, and more than 0 to 1.0% by mass. % (Preferably 0.1 to 1.0% by mass) of Cu, and the balance is preferably Sn.

  The content of Ag is preferably 0.05 to 3.5% by mass and 0.1 to 3.0% by mass with respect to the entire solder material from the viewpoint of excellent reliability by reducing ΔT. Is more preferable, and it is still more preferable that it is 0.5 to 3.0 mass%. Further, the content of Cu is preferably 0.01 to 0.9% by mass, and more preferably 0.05 to 0.75% by mass with respect to the entire solder material from the viewpoint of excellent reliability by reducing ΔT. %, More preferably 0.1 to 0.7% by mass. The preferred numerical ranges for the Ag and Cu contents are independent of each other, and the Ag and Cu contents can be determined independently of each other.

  Solder materials contain As of 20 to 300 mass ppm. When the content of As is 20 mass ppm or more, an increase in viscosity is suppressed, and the effect of suppressing thickening is excellent. When the content of As is 300 mass ppm or less, deterioration of wettability can be further suppressed. For this reason, when the content of As is 20 to 300 mass ppm, the solder paste of the present embodiment can achieve both the thickening suppressing effect and the reliability in a well-balanced manner. From the same viewpoint, the content of As is preferably from 30 to 250 ppm by mass, more preferably from 50 to 200 ppm by mass, based on the entire solder material. As may be included with Sn or an Sn-based alloy (for example, an intermetallic compound or a solid solution), or may be present separately from the Sn-based alloy, for example, as As alone or as an oxide.

In the present embodiment, the content of Sb is 0 to 3000 mass ppm, the content of Bi is 0 to 10000 mass ppm, and the content of Pb is 0 to 5100 mass ppm with respect to the mass of the entire solder material. When Sb, Bi, or Pb is sufficiently present, the increase in viscosity tends to be suppressed. Although the reason is not clear, these elements are noble metals with respect to Sn, and therefore, the Sn—Sb / Bi / Pb alloy is less ionizable than Sn, and as an ion state (salt) to the flux. It is considered that elution hardly occurs. However, the mechanism does not depend on this. Bi and Pb also tend to suppress a decrease in wettability that occurs when the solder material contains As. On the other hand, if the contents of Bi and Pb are too large, the solidus temperature decreases, and the difference between the liquidus temperature (T _L ) and the solidus temperature (T _S ) (ΔT = T _L −T _S). ) Increases, and in the solidification process of the molten solder, a high melting point crystal phase having a low Bi or Pb content is deposited first, and then a low melting point crystal phase having a high Bi or Pb concentration is segregated. There is a possibility that the mechanical strength and the like of the solder material are deteriorated and the reliability such as cycle characteristics is reduced. In particular, since the crystal phase having a high Bi concentration is hard and brittle, the segregation in the solder material may significantly reduce the reliability.

From the above viewpoints, preferred ranges of the contents of Sb, Bi and Pb are as follows.
The lower limit of the Sb content is preferably at least 25 ppm by mass, more preferably at least 50 ppm by mass, further preferably at least 100 ppm by mass, particularly preferably at least 300 ppm by mass. The upper limit of the Sb content is preferably 1150 ppm by mass or less, more preferably 500 ppm by mass or less.

The lower limit of the Bi content is preferably 25 mass ppm or more, more preferably 50 mass ppm or more, further preferably 75 mass ppm or more, particularly preferably 100 mass ppm or more, and most preferably 250 mass ppm or more. It is not less than ppm by mass. The upper limit of the Bi content is preferably 1000 ppm by mass or less, more preferably 600 ppm by mass or less, and further preferably 500 ppm by mass or less.
The lower limit of the Pb content is preferably 25 mass ppm or more, more preferably 50 mass ppm or more, further preferably 75 mass ppm or more, particularly preferably 100 mass ppm or more, and most preferably 250 mass ppm or more. It is not less than the mass pp. The upper limit of the Pb content is preferably 5,000 ppm by mass or less, more preferably 1,000 ppm by mass or less, further preferably 850 ppm by mass or less, and particularly preferably 500 ppm by mass or less.

  If the content of Sb, Bi, and Pb with respect to the mass of the entire solder material satisfies the above-mentioned conditions, even if all of them constitute an alloy (intermetallic compound, solid solution, or the like) together with Sn or an Sn-based alloy. Alternatively, a part thereof may be present separately from the Sn-based alloy.

In the present embodiment, the contents of As, Sb, Bi, and Pb preferably satisfy the following expression (1).
275 ≦ 2As + Sb + Bi + Pb (1)

  In the above formula (1), As, Sb, Bi, and Pb represent the contents (mass ppm) in each solder material.

  As, Sb, Bi and Pb are elements each exhibiting the effect of suppressing the rise of clay (thickening suppression effect) when made into a paste, so that from the viewpoint of suppression of thickening, the total of these elements is 275 ppm or more. Preferably, there is. 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.

  2As + Sb + Bi + Pb is preferably 350 or more, more preferably 1200 or more. On the other hand, there is no upper limit for 2As + Sb + Bi + Pb, but from the viewpoint of setting ΔT in a suitable range, it is preferably 25200, more preferably 18600 or less, further preferably 10200 or less, particularly preferably 5300 or less (preferably 3800 or less). Below).

  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 represent the contents (ppm by mass) in each solder material.

In the present embodiment, the contents of As, Sb, Bi, and Pb preferably satisfy the following expression (2).
0.01 ≦ (2As + Sb) / (Bi + Pb) ≦ 10.00 (2)
In the above formula (2), As, Sb, Bi, and Pb represent the contents (mass ppm) in each solder material.

  Generally, when the content of As and Sb is large, the wettability of the solder material tends to deteriorate. 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 control is required. In particular, in an alloy composition containing both Bi and Pb, ΔT easily spreads, and if the content of Bi and Pb is increased to improve the wettability excessively, ΔT will increase. On the other hand, when the content of As or Sb is increased to improve the effect of suppressing thickening, wettability deteriorates. However, if the group is divided into the group of As and Sb and the group of Bi and Pb, and the total content of both groups satisfies the relationship of equation (2), the content of the group of As and Sb and the group of Bi and Pb The balance between the amounts becomes appropriate, and the effect of suppressing thickening, narrowing of ΔT, and wettability can all be satisfied at the same time.

  If (2As + Sb) / (Bi + Pb) is less than 0.01, the total content of Bi and Pb is relatively large as compared to the total content of As and Pb, and thus ΔT is widened. (2As + Sb) / (Bi + Pb) is preferably 0.01 or more, more preferably 0.02 or more, further preferably 0.41 or more, still more preferably 0.90 or more, and particularly preferably. Is 1.00 or more, and most preferably 1.40 or more. On the other hand, when (2As + Sb) / (Bi + Pb) exceeds 10.00, the total content of As and Sb becomes relatively larger than the total content of Bi and Pb, and the wettability deteriorates. (2As + Sb) / (Bi + Pb) is preferably 10.00 or less, more preferably 5.33 or less, still more preferably 4.50 or less, still more preferably 2.67 or less, and particularly preferably. Is 4.18 or less, most preferably 2.30 or less.

  Since the denominator of the expression (2) is “Bi + Pb”, when the expression (2) is satisfied, at least one of Bi and Pb is necessarily contained. As described above, a solder material containing neither Bi nor Pb tends to have poor wettability.

  The following formula (2a) is obtained by appropriately selecting the upper limit and the lower limit from the above preferred embodiments.

0.31 ≦ (2As + Sb) / (Bi + Pb) ≦ 10.00 (2a)
Above (2a) wherein, As, Sb, Bi, and Pb represents the content of each of solder material (mass ppm).

  In the present embodiment, the content of As, Sb, Bi, and Pb preferably satisfies at least one of the above formulas (1) and (2), and more preferably satisfies both.

  In this embodiment, the solder paste may further include a zirconium oxide powder. The content of the zirconium oxide powder based on the total mass of the solder paste is preferably 0.05 to 20.0% by mass, more preferably 0.05 to 10.0% by mass, and most preferably 0.1 to 3% by mass. When the content of the zirconium oxide powder is within the above range, the activator contained in the flux reacts preferentially with the zirconium oxide powder, and the reaction with Sn or Sn oxide on the surface of the solder powder becomes less likely to occur. The effect of further suppressing the increase in viscosity due to the change is exhibited.

  The upper limit of the particle size of the zirconium oxide powder added to the solder paste is not limited, but 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 is not particularly limited, but is preferably 0.5 μm or more. The above-mentioned particle diameter is obtained by taking an SEM photograph of the zirconium oxide powder and obtaining the equivalent diameter of the projected circle by image analysis for each particle present in the visual field. The average value of the equivalent diameter is used. The shape of the zirconium oxide particles is not particularly limited, but a different shape has a large contact area with the flux and has an effect of suppressing thickening. Spherical shape provides good fluidity, and therefore excellent printability as a paste. What is necessary is just to select a shape suitably according to a desired characteristic.

  The method for manufacturing the solder material of the present embodiment is not particularly limited, and includes, for example, a method of manufacturing by melting and mixing raw metal.

  In the present embodiment, the form of the solder material is not particularly limited, and may be, for example, a particulate form such as a powder form (solder powder). The form of the solder material is preferably a particulate form, and more preferably a powder form, from the viewpoint of excellent fluidity.

  Examples of the method for producing the particulate solder material include a dropping method of dropping a molten solder material to obtain particles, a spraying method of centrifugal spraying, and a method of pulverizing a bulk solder material. 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.

Further, when the solder material is particulate, the solder material, JIS Z 3284-1: 20 1 4 Classification of powder size in a size corresponding to the symbol 1-8 in (Table 2) (particle size distribution) It is preferable to have a size (particle size distribution) corresponding to the symbols 4 to 8, and more preferably to have a size (particle size distribution) corresponding to the symbols 5 to 8. This enables soldering to fine components.

[flux]
In the present specification, the term “flux” refers to all components other than the solder material in the solder paste.

  The flux contains a hindered phenol compound as a metal deactivator. When the flux contains the hindered phenol-based compound, the solder material can improve the effect of suppressing thickening.

  The hindered phenol compound refers to a phenol compound having a bulky substituent (for example, a branched or cyclic alkyl group such as a t-butyl group) in at least one of the ortho positions of phenol. The hindered phenol compound is not particularly limited, and for example, bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionic acid] [ethylenebis (oxyethylene)], N, N '-Hexamethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propanamide], 1,6-hexanediol bis [3- (3,5-di-tert-butyl-4) -Hydroxyphenyl) propionate], 2,2′-methylenebis [6- (1-methylcyclohexyl) -p-cresol], 2,2′-methylenebis (6-tert-butyl-p-cresol), 2,2 ′ -Methylenebis (6-tert-butyl-4-ethylphenol), triethylene glycol-bis [3- (3-tert-butyl- -Methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n -Octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4 -Hydroxyphenyl) propionate], 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert- Butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydro) Cannamamide), 3,5-di-tert-butyl-4-hydroxybenzylphosphonate-diethyl ester, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl- 4-hydroxybenzyl) benzene and the like. These hindered phenol compounds are used alone or in combination of two or more.

  The content of the hindered phenol compound is preferably 0.5 to 10% by mass based on the entire flux. When the content is 0.5% by mass or more, the solder paste can further improve the effect of suppressing thickening. When the content is 10% by mass or less, the solder paste can further improve the solder wettability. From the same viewpoint, the content is more preferably 1.0 to 5.0% by mass, and still more preferably 2.0 to 4.0% by mass.

  Preferably, the flux contains a resin. The content of the resin may be, for example, 30 to 60% by mass based on the entire flux.

  The resin is not particularly limited, and examples thereof include a rosin resin, a (meth) acrylic resin, a urethane resin, a polyester resin, a phenoxy resin, a vinyl ether resin, a terpene resin, and a modified terpene resin (for example, an aromatic modified terpene). Resin, hydrogenated terpene resin, hydrogenated aromatic modified terpene resin, etc.), terpene phenol resin, modified terpene phenol resin (eg, hydrogenated terpene phenol resin, etc.), styrene resin, modified styrene resin (eg, styrene acrylic resin, styrene) Maleene resin), xylene resin, modified xylene resin (eg, phenol-modified xylene resin, alkylphenol-modified xylene resin, phenol-modified resol-type xylene resin, polyol-modified xylene resin, polyoxyethylene-added xylene resin, etc.).These resins may be used alone or in combination of two or more. Among these, the resin is preferably at least one selected from the group consisting of a rosin-based resin and a (meth) acrylic resin. Here, the term “(meth) acrylic resin” refers to a concept including methacrylic resin and acrylic resin.

  Examples of the rosin-based resin include raw rosins such as gum rosin, wood rosin, and tall oil rosin, and derivatives obtained from the raw rosins. Derivatives include, for example, purified rosin, hydrogenated rosin, disproportionated rosin, polymerized rosin and α, β unsaturated carboxylic acid modified products (acrylated rosin), maleated rosin, fumarated rosin, and the like. Examples include purified products, hydrides and disproportionates, and purified, hydride and disproportionated products of α, β unsaturated carboxylic acid modified products. These rosin-based resins may be used alone or in combination of two or more.

  The content of the rosin-based resin may be, for example, 30 to 60% by mass based on the entire flux.

  The (meth) acrylic resin, for example, (meth) homopolymers of acrylic monomers, two or more (meth) include copolymers of acrylic monomers. (Meth) acrylic monomers include (meth) acrylic acid, itaconic acid, maleic acid, crotonic acid, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and (meth) acrylic acid. Hexyl, propyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate , Tetradecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate and the like. These (meth) acrylic resins are used alone or in combination of two or more.

  When the resin contains a (meth) acrylic resin, the temperature cycle reliability can be improved. When a thermal stress of high and low temperatures is repeatedly applied to a mounting portion or a bonding portion, a material having high crystallinity such as rosin may be broken and moisture may be absorbed from the crack. In contrast, by including a soft (meth) acrylic resin in the resin, the cracks can be suppressed, and as a result, the temperature cycle reliability can be improved. The content of the (meth) acrylic resin is, for example, 0 to 40% by mass relative to the entire flux, and preferably 20 to 30% by mass from the viewpoint of excellent temperature cycle reliability. The content of the (meth) acrylic resin is, for example, 0 to 80% by mass relative to the entire resin, and is preferably 30 to 80% by mass from the viewpoint of excellent temperature cycle reliability.

  The flux may contain an organic acid-based activator (organic acid) to improve solderability. Organic acids include adipic acid, azelaic acid, eicosane diacid, citric acid, glycolic acid, succinic acid, salicylic acid, diglycolic acid, dipicolinic acid, dibutylaniline diglycolic acid, suberic acid, sebacic acid, thioglycolic acid, terephthalic acid Acid, dodecandioic acid, parahydroxyphenylacetic acid, picolinic acid, phenylsuccinic acid, phthalic acid, fumaric acid, maleic acid, malonic acid, lauric acid, benzoic acid, tartaric acid, tris (2-carboxyethyl) isocyanurate, 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, linolenic acid, dimer acid, hydrogenated dimer acid, trimer acid, hydrogenated trimer acid, and the like.

  The content of the organic acid may be, for example, 0 to 10% by mass based on the entire flux.

  The flux may contain an amine-based activator (amine) to improve solderability. Examples of the amine include an amine aliphatic amine, an aromatic amine, an amino alcohol, imidazole, benzotriazole, an amino acid, guanidine, and hydrazide. Examples of the aliphatic amine include dimethylamine, ethylamine, 1-aminopropane, isopropylamine, trimethylamine, allylamine, n-butylamine, diethylamine, sec-butylamine, tert-butylamine, N, N-dimethylethylamine, isobutylamine, and cyclohexyl. Amines and the like. Examples of the aromatic amine include aniline, N-methylaniline, diphenylamine, N-isopropylaniline, p-isopropylaniline and the like. Examples of the amino alcohol include 2-aminoethanol, 2- (ethylamino) ethanol, diethanolamine, diisopropanolamine, triethanolamine, N-butyldiethanolamine, triisopropanolamine, and N, N-bis (2-hydroxyethyl). -N-cyclohexylamine, N, N, N ', N'-tetrakis (2-hydroxypropyl) ethylenediamine, N, N, N', N ", N" -pentakis (2-hydroxypropyl) diethylenetriamine and the like No. Examples of the imidazole include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, and 2-phenyl-4-imidazole. Methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 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 ′ ―Methylimi Zolyl- (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-di Mino-6-vinyl-s-triazine, 2,4-diamino-6-vinyl-s-triazine isocyanuric acid adduct, 2,4-diamino-6-methacryloyloxyethyl-s-triazine, epoxy-imidazole adduct, -Methylbenzimidazole, 2-octylbenzimidazole, 2-pentylbenzimidazole, 2- (1-ethylpentyl) benzimidazole, 2-nonylbenzimidazole, 2- (4-thiazolyl) benzimidazole, benzimidazole and the like. . Examples of benzotriazole include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole and 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzo Triazole, 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-ethylhexyl) aminomethyl] methylbenzotriazole, 2,2 ′-[[(methyl-1H-benzotriazol-1-yl) methyl] imino] bisethanol, 1,2,3-benzotriazole sodium salt aqueous solution, 1- (1 ′, 2′-dicarboxyethyl) benzotriazole, 1- (2,3-dicarboxypropyl) benzotriazole, 1-[(2-ethylhexylamino) ) Methyl] benzotriazole, 2,6-bis [(1H-benzotriazol-1-yl) methyl] -4-methylphenol, 5-methylbenzotriazole and the like. As amino acids, alanine, arginine, asparagine, aspartic acid, cysteine hydrochloride, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine monohydrochloride, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine, β-alanine, γ-aminobutyric acid, δ-aminovaleric acid, ε-aminohexanoic acid, ε-caprolactam, 7-aminoheptanoic acid and the like. Examples of guanidine include carbodihydrazide, malonic dihydrazide, succinic dihydrazide, adipic dihydrazide, 1,3-bis (hydrazinocarbonoethyl) -5-isopropylhydantoin, sebacic dihydrazide, dodecane diacid dihydrazide, 7, Examples thereof include 11-octadecadien-1,18-dicarbohydrazide and isophthalic dihydrazide. Examples of the hydrazide include dicyandiamide, 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine and the like.

  The content of the amine may be, for example, 0 to 20% by mass based on the entire flux.

  The flux may contain a covalent halogen activator (covalent halogen) to improve solderability. Examples of the covalent halogen include trans-2,3-dibromo-2-butene-1,4-diol, 2,3-dibromo-1,4-butanediol, 2,3-dibromo-1-propanol, 2,3-dichloro-1-propanol, 1,1,2,2-tetrabromoethane, 2,2,2-tribromoethanol, pentabromoethane, carbon tetrabromide, 2,2-bis (bromomethyl)- 1,3-propanediol, meso-2,3-dibromosuccinic acid, chloroalkane, chlorinated fatty acid ester, n-hexadecyltrimethylammonium bromide, triallylisocyanurate hexabromide, 2,2-bis [3,5 -Dibromo-4- (2,3-dibromopropoxy) phenyl] propane, bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] sulfo Benzene, ethylenebispentabromobenzene, 2-chloromethyloxirane, heptonic acid, heptanoic anhydride, brominated bisphenol A type epoxy resin, and the like.

  The content of covalent halogen, relative to the overall flux, for example, may be a 0-5% by weight.

  The flux may contain an amine hydrohalide activator (amine hydrohalide) to improve solderability. Examples of the amine hydrohalide include the amine hydrohalides exemplified as the amine. Examples of amine hydrohalides include, for example, stearylamine hydrochloride, diethylaniline hydrochloride, diethanolamine hydrochloride, 2-ethylhexylamine hydrobromide, pyridine hydrobromide, isopropylamine hydrobromide, Cyclohexylamine hydrobromide, diethylamine hydrobromide, monoethylamine hydrobromide, 1,3-diphenylguanidine hydrobromide, dimethylamine hydrobromide, dimethylamine hydrochloride, rosinamine odor Hydrochloride, 2-ethylhexylamine hydrochloride, isopropylamine hydrochloride, cyclohexylamine hydrochloride, 2-pipecholine hydrobromide, 1,3-diphenylguanidine hydrochloride, dimethylbenzylamine hydrochloride, hydrazine hydrate smell Hydrochloride, dimethylcyclohexylamine hydrochloride Trinonylamine hydrobromide, diethylaniline hydrobromide, 2-diethylaminoethanol hydrobromide, 2-diethylaminoethanol hydrochloride, ammonium chloride, diallylamine hydrochloride, diallylamine hydrobromide, monoethylamine hydrochloride, monoethyl amine hydrobromide, diethylamine hydrochloride, triethylamine hydrobromide, triethylamine hydrochloride, hydrazine monohydrochloride, hydrazine dihydrochloride, hydrazine monohydrobromide, hydrazine dihydrobromide acid Salt, pyridine hydrochloride, aniline hydrobromide, butylamine hydrochloride, hexylamine hydrochloride, n-octylamine hydrochloride, dodecylamine hydrochloride, dimethylcyclohexylamine hydrobromide, ethylenediamine dihydrobromide Rosinamine hydrobromide, 2-Fe Louisimidazole hydrobromide, 4-benzylpyridine hydrobromide, L-glutamate hydrochloride, N-methylmorpholine hydrochloride, betaine hydrochloride, 2-pipecholine hydroiodide, cyclohexylamine hydroiodide 1,3-diphenylguanidine hydrofluoride, diethylamine hydrofluoride, 2-ethylhexylamine hydrofluoride, cyclohexylamine hydrofluoride, ethylamine hydrofluoride, rosinamine hydrofluoride Acid salts, cyclohexylamine tetrafluoroborate, dicyclohexylamine tetrafluoroborate and the like.

  The content of the amine hydrohalide may be, for example, 0 to 2% by mass based on the entire flux.

  The flux may contain a solvent. Examples of the solvent 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, 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] A 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. Examples of glycol ether solvents include diethylene glycol mono-2-ethylhexyl ether, ethylene glycol monophenyl ether, 2-methylpentane-2,4-diol, diethylene glycol monohexyl ether, diethylene glycol dibutyl ether, triethylene glycol monobutyl ether, and hexyl diglycol. And tetraethylene glycol dimethyl ether.

  The content of the solvent may be, for example, 0 to 80% by mass based on the entire flux.

  The flux may contain a thixotropic agent. Examples of the thixo agent include a wax thixo agent and an amide thixo agent. Examples of the wax-based thixotropic agent include castor hardened oil. Amide-based thixotropic agents include, for example, lauric amide, palmitic amide, stearic amide, behenic amide, hydroxystearic amide, saturated fatty amide, oleic amide, erucic amide, unsaturated fatty amide, p-toluene Methane amide, aromatic amide, methylene bis stearic acid amide, ethylene bis lauric acid amide, ethylene bis hydroxy stearic acid amide, saturated fatty acid bis amide, methylene bis oleic acid amide, unsaturated fatty acid bis amide, m-xylylene bis stearic acid amide, Aromatic bisamide, saturated fatty acid polyamide, unsaturated fatty acid polyamide, aromatic polyamide, substituted amide, methylol stearic acid amide, methylol amide, fat Ester amide, and the like.

  The content of the thixotropic agent may be, for example, 0 to 15% by mass based on the entire flux.

  In the present embodiment, the mass ratio between the content of the solder material and the content of the flux (solder material: flux) is 95 mass% of the solder material: 5 mass% of the flux to 5 mass% of the solder material: 95 mass% of the flux. It may be 95% by mass of solder material: 5% by mass of flux to 85% by mass of solder material: 15% by mass of flux.

  In the present embodiment, the solder paste can be manufactured by kneading the solder material (solder powder) of the present embodiment and a flux by a known method.

  The solder paste of the present embodiment is used, for example, for a circuit board having a fine structure in an electronic device, and specifically, by a printing method using a metal mask, an ejection method using a dispenser, a transfer method using a transfer pin, or the like. , Can be applied to a soldered portion and reflowed.

  Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to the contents described in the examples.

(Adjustment of solder powder)
Powders were prepared by melting and mixing the metals shown in Tables 1 to 10 so as to have the compositions shown in Tables 1 to 10 and centrifugally spraying them in an Ar atmosphere. The numerical values in each table represent the content (% by mass) of each metal when the total of the solder powder is 100% by mass, and "Bal" represents the balance. Further, the average particle size of the solder powder JIS Z3284-1: 20 according to the 1 4 measured, JIS Z3284-1 from measurements: were classified according to Table 2 of 20 1 4 powder sizing. Numerical values shown in each table, JIS Z3284-1: shows the symbol of the powder size in Table 2 20 1 4.

(Preparation of flux)
Each material shown in Tables 1 to 10 was heated and stirred to have the composition shown in Tables 1 to 10, and then cooled to prepare a flux. The numerical values in each table represent the content (% by mass) of each material when the total flux is 100% by mass. The reagent name and CAS number of each material shown in the table are shown below.

・ "Metal deactivator A"
Reagent name: bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionic acid] [ethylenebis (oxyethylene)]
CAS No. 36443-68-2
・ "Metal deactivator B"
Reagent name: N, N'-hexamethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propanamide]
CAS No. 23128-74-7
・ "Metal deactivator C"
Reagent name: 1,6-hexanediol bis [3- (3,5-di -tert- butyl-4-hydroxyphenyl) propionate]
CAS No. 35074-77-2
・ "Metal deactivator D"
Reagent name: 2,2'-methylenebis [6- (1-methylcyclohexyl) -p-cresol]
CAS No. 77-62-3
・ "Metal deactivator E"
Reagent name: 2,2'-methylenebis (6-tert-butyl-p-cresol)
CAS No. 119-47-1
・ "Metal deactivator F"
Reagent name: 2,2'-methylenebis (6-tert-butyl-4-ethylphenol)
CAS No. 88-24-4
・ "Metal deactivator G"
Reagent name: N- (2H-1,2,4-triazol-5-yl) salicylamide CAS No. 36411-52-6
-Reagent name: 2-ethyl-4-methylimidazole CAS No. 931-36-2
- reagent name: 2-undecylimidazole CAS No. 16731-68-3
-Reagent name: trans-2,3-dibromo-2-butene-1,4-diol CAS No. 3234-02-4
-Reagent name: triallyl isocyanurate 6 bromide CAS No. 52434-90-9
-Reagent name: Hexyl diglycol CAS No. 112-59-4
-Reagent name: tetraethylene glycol dimethyl ether CAS No. 143-24-8
-Reagent name: Castor hardened oil CAS No. 8001-78-3

(Preparation of solder paste)
A solder paste was prepared by kneading the solder powder and the flux so that the mass ratio (solder powder: flux) was 89:11.

  (1) Evaluation of suppression of thickening was performed on the solder pastes of the respective examples and comparative examples, and (2) reliability evaluation was performed on the solder powders used in the respective examples and comparative examples. Each evaluation method is shown below, and the evaluation results are shown in Tables 1 to 10.

(1) Evaluation of Thickening Inhibition Using a rotational viscometer (PCU-205, manufactured by Malcolm Co., Ltd.) on the obtained solder paste, according to the method described in JIS Z 3284-3 "4.2 Viscosity characteristic test". The viscosity was continuously measured for 12 hours at a rotation speed of 10 rpm and a measurement temperature of 25 ° C. Then, the initial viscosity (viscosity after 30 minutes of stirring) and the viscosity after 13 hours were compared, and the thickening suppressing effect was evaluated based on the following criteria.
Viscosity after 13 hours ≦ initial viscosity × 1.2: little increase in viscosity over time and good (○)
Viscosity after 13 hours> Initial viscosity × 1.2: Viscosity increase with time is large and poor (×)

(2) Evaluation of reliability The obtained solder powder was heated at a rate of 5 ° C./min (180 ° C. to 250 ° C.) using a differential scanning calorimeter (EXSTAR DSC7020, manufactured by SII Nanotechnology Inc.). A DSC measurement is performed under the measurement conditions of a temperature decreasing rate: −3 ° C./min (250 ° C. to 150 ° C.) and a carrier gas: N ₂ to measure a liquidus temperature (T _L ) and a solidus temperature (T _S ). did. Then, calculate the difference between the liquidus temperature (T _L) and the solidus temperature (T _S) and _{(ΔT = T L -T S)} , were evaluated based on the following criteria.
ΔT within 10 ° C: Excellent reliability (○)
ΔT exceeds 10 ° C .: Poor reliability (×)
If the difference between the liquidus temperature (T _L ) and the solidus temperature (T _S ) of the solder powder is large (ΔT = T _L −T _S ), the solder paste containing the solder powder is applied to the substrate of the electronic device. When solidifying, a structure having a high melting point is likely to precipitate on the surface of the solder powder. When a structure with a high melting point precipitates on the surface of the solder powder, then a structure with a low melting point is sequentially deposited toward the inside of the solder powder, and the structure of the solder powder tends to be non-uniform, which lowers reliability such as cycleability. Cause.

(3) Evaluation of wettability In the same manner as in “(1) Evaluation of suppression of thickening”, the solder paste of each of the examples and the comparative examples was coated on a Cu plate with an opening diameter of 6.5 mm, a numerical aperture of 4, and a mask. Printing was performed using a metal mask having a thickness of 0.2 mm, and after heating from 25 ° C. to 260 ° C. at a rate of 1 ° C./sec in a N ₂ atmosphere in a reflow furnace, air-cooled to room temperature (25 ° C.). Solder bumps were formed. The appearance of the obtained solder bumps was observed using an optical microscope (magnification: 100 times), and evaluated based on the following criteria.
No solder particles that could not be melted were observed in all four solder bumps.
: Good solder wettability (O)
Solder particles that could not be completely melted were observed in one or more of the four solder bumps.
: Poor solder wettability (×)

  INDUSTRIAL APPLICABILITY The solder material of the present invention is excellent in reliability such as a thickening suppressing effect and cycle characteristics, and can be used for various applications.

Claims (3)

A solder paste comprising a solder material and a flux,
Said solder material, As: 20 to 300 ppm by weight, Pb: 0 ppm by mass exceeds 5100 mass ppm or less, S b: 0 ppm by mass exceeds 3000 mass ppm or less, B i: 0 mass ppm to 10,000 mass ppm or less, and the balance Has an alloy composition consisting of Sn,
The contents of As, Sb, Bi and Pb satisfy the following formulas (1) and (2),
275 ≦ 2As + Sb + Bi + Pb (1)
0.01 ≦ (2As + Sb) / (Bi + Pb) ≦ 10.00 (2)
(However, in the formulas (1) and (2), As, Sb, Bi, and Pb represent the contents (mass ppm) in each solder material.)
The flux contains a hindered phenol compound,
A solder paste in which the content of the hindered phenol compound is 0.5 to 10% by mass based on the entire flux.   The solder paste according to claim 1, wherein the solder material has a particulate form.   3. The solder paste according to claim 1, wherein the solder material further comprises more than 0 and 3.5 mass% or less of Ag and / or more than 0 and 1.0 mass% or less of Cu. 4.