JP6555402B1 - Solder paste - Google Patents

Abstract

An object of the present invention is to provide a solder paste capable of achieving both a thickening suppression effect, reliability and wettability in a balanced manner. The solder paste of the present invention is a solder paste composed of a solder material and a flux, and the solder material is Sn or Sn-based alloy, 20-300 mass ppm As, 0-3000 mass ppm. Sb, 0 to 10000 mass ppm Bi and 0 to 5100 mass ppm Pb (however, the contents of Bi and Pb are not 0 mass ppm at the same time), and the flux is a metal deactivator And the metal deactivator contains a nitrogen compound. [Selection figure] None

Description

  The present invention relates to a solder paste.

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

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

Further, in the solder material constituting the solder paste, when the difference (ΔT = T _L −T _S ) between the liquidus temperature (T _L ) and the solidus temperature (T _S ) becomes large, for example, a substrate of an electronic device When the solder paste is applied and solidified, the structure of the solder material is likely to be non-uniform, and as a result, future reliability may be reduced.

  Furthermore, in general, the solder material is required to have a property (wetting property) that spreads on the metal of the electronic component when melted. When an element such as P, Ge, or Ga is added, the solder material The wettability will be reduced. If the wettability of the solder material is poor, soldering failure may occur.

  Patent Document 1 includes a rosin resin, an acrylic resin, an activator, a thixotropic agent, an antioxidant, and a solvent. As the antioxidant, a phenol-based antioxidant, a triazole-based antioxidant, and phosphorus A solder paste composition containing a flux composition containing at least one of a system antioxidant and a solder alloy powder is disclosed. In this document, the solder paste composition is used for an electronic circuit board placed in an environment where the temperature difference is great and the thermal shock is large. It has been disclosed that it has the effect of suppressing the occurrence of cracks and their development, and can exhibit better performance such as meltability and wettability. This document only discloses an example using a solder alloy powder having a composition of Sn-3Ag-0.5Cu.

  Patent Document 2 discloses a solder paste obtained by mixing Sn-based lead-free solder powder with a rosin flux, and the rosin flux contains at least one salicylamide compound selected from salicylamide and derivatives thereof. A solder paste containing 0.01 to 10% by mass is disclosed. In this document, the salicylamide compound is preferentially adsorbed on the surface of the solder powder, thereby preventing a reaction between the solder powder and a flux component, particularly an activator such as an organic amine hydrohalide or an organic acid, It is disclosed that a change in the viscosity of the solder paste due to such a reaction is prevented. This document only discloses an example using a solder alloy powder having a composition of 8% Zn-3% Bi-Ba Sn and 3% Ag-0.5% Cu-Ba Sn.

JP 2017-1000018 A WO2002 / 043916

  However, neither of Patent Documents 1 and 2 is intended to balance the increase in viscosity over time with the balance between reliability and wettability. For this reason, a solder paste that balances the thickening suppression effect, reliability, and wettability is desired.

  Therefore, an object of the present invention is to provide a solder paste capable of achieving both a thickening suppressing effect, reliability and wettability in a balanced manner.

  As a result of diligent research to solve the above-mentioned problems, the inventors of the present invention are solder pastes composed of a solder material and a flux, and the solder material is Sn or an Sn-based alloy, and As, Sb, Bi at a specific ratio. And Pb, and the flux includes a metal deactivator containing a nitrogen compound, and the present inventors have found that the above problems can be solved, and have completed the present invention.

  That is, the solder paste of the present invention is a solder paste composed of a solder material and a flux, and the solder material is Sn or Sn-based alloy, 20 to 300 mass ppm As, 0 to 3000 mass ppm Sb, 0 to 10000 mass ppm Bi and 0 to 5100 mass ppm Pb (however, the contents of Bi and Pb are not 0 mass ppm at the same time), and the flux contains a metal deactivator The metal deactivator contains a nitrogen compound.

  ADVANTAGE OF THE INVENTION According to this invention, the solder paste which can balance a thickening inhibitory effect, reliability, and wettability with sufficient balance can be provided.

  Hereinafter, modes 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 scope of the invention.

  In the present specification, the “thickening suppressing effect” refers to an effect capable of suppressing an increase in viscosity over time of the prepared solder paste when the solder paste is prepared.

  In addition, in this specification, content of each element can be measured by analyzing by ICP-AES based on JISZ3910, for example.

[Solder paste]
The solder paste of this embodiment is a solder paste made of a solder material and a flux. The solder material is Sn or Sn-based alloy, 20 to 300 mass ppm As, 0 to 3000 mass ppm Sb, 0 to 10000 mass ppm Bi and 0 to 5100 mass ppm Pb (however, the contents of Bi and Pb) Are not simultaneously 0 ppm by mass). However, the contents of Bi and Pb are not simultaneously 0 ppm by mass, and two or more of Sb, Bi, and Pb are included (the content of two or more is more than 0 ppm by mass). It is also preferable that all of Sb, Bi, and Pb are contained (the content of all three types exceeds 0 mass ppm). The flux contains a metal deactivator, and the metal deactivator contains a nitrogen compound. The solder paste of this embodiment can improve the thickening suppression effect by having the above configuration. Further, the solder material forming the solder paste of the present embodiment is provided with the configuration described above, 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, even if the solder paste containing the said solder material is apply | coated to the board | substrate of an electronic device and it is made to solidify, for example, the solder paste can maintain the uniformity of the structure | tissue of a solder material. As a result, the solder paste is excellent in reliability such as cycle characteristics. Furthermore, since the solder material which comprises the solder paste of this embodiment is excellent in wettability by providing said structure, generation | occurrence | production of the soldering defect can be suppressed. As described above, the solder paste having the above-described configuration can achieve a balance between the thickening suppressing effect, reliability, and wettability.

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

  Sn may be, for example, Sn (3N material) having a purity of 99.9% or more, Sn (4N material) having a purity of 99.99% or more, and 99.999%. Sn (5N material) having 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, and 90% by mass or more with respect to the entire solder material. There may be.

  Examples of the Sn-based alloy include a composition 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. Examples of the alloy include alloys obtained by adding As, Ag, Cu, In, Ni, Co, Ge, P, Fe, Zn, Al, Ga, or the like to the alloy having the above composition. The Sn content in the Sn-based alloy is not particularly limited, and can be, for example, more than 40% by mass.

  The Sn and Sn-based alloy is preferably Sn, Sn—Cu alloy, or Sn—Ag—Cu alloy from the viewpoint of excellent reliability by reducing ΔT. From the same viewpoint, the Sn—Cu alloy contains more than 0 and 1.0% by mass or less (preferably 0.5 to 1.0% by mass) of Cu, with the balance being Sn. From the same viewpoint, the Sn—Ag—Cu alloy contains more than 0 and not more than 3.5% by mass (preferably 1.0 to 3.5% by mass) of Ag, more than 0 and more than 1.0%. % Or less (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 with respect to the entire solder material from the viewpoint of excellent reliability by reducing ΔT, and 0.1 to 3.0% by mass. It is more preferable that it is 0.5-3.0 mass%. Moreover, it is preferable that content of Cu is 0.01-0.9 mass% with respect to the whole solder material from a viewpoint which is excellent in reliability by making (DELTA) T small, 0.05-0.75 It is more preferable that it is mass%, and it is still more preferable that it is 0.1-0.7 mass%. In addition, the preferable numerical range of said Ag and Cu content is respectively independent, Comprising: Content of Ag and Cu can each be determined independently.

  The solder material contains 20 to 300 ppm by mass of As. When the As content is 20 mass ppm or more, an increase in viscosity is suppressed, and the effect of suppressing increase in viscosity is excellent. It can suppress further that wettability deteriorates because content of As is 300 mass ppm or less. For this reason, when the content of As is 20 to 300 ppm by mass, the solder paste of the present embodiment can achieve both a thickening suppression effect and reliability in a balanced manner. From the same viewpoint, the content of As is preferably 30 to 250 ppm by mass and more preferably 50 to 200 ppm by mass with respect to the entire solder material. As may constitute Sn (for example, an intermetallic compound or a solid solution) together with Sn or an Sn-based alloy, and may exist as, for example, an As simple substance or an oxide separately from the Sn-based alloy.

In this embodiment, the Sb content is 0 to 3000 mass ppm, the Bi content is 0 to 10000 mass ppm, and the Pb content 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 viscosity increase tends to be suppressed. The reason is not clear, but these elements are precious metals with respect to Sn. Therefore, the Sn—Sb / Bi / Pb alloy is less ionized than Sn, and as an ionic state (salt) to the flux. This is probably because elution is less likely to occur. 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). ), And in the solidification process of the molten solder, a high melting point crystal phase with a low content of Bi or Pb is first precipitated, and then a low melting point crystal phase with a high concentration of Bi or Pb is segregated. The mechanical strength and the like of the solder material may be deteriorated and reliability such as cycle characteristics may be reduced. In particular, since the crystal phase having a high Bi concentration is hard and brittle, segregation in the solder material may significantly reduce the reliability.

From the above viewpoint, the preferable ranges of the contents of Sb, Bi and Pb are as follows.
The lower limit of the Sb content is preferably 25 ppm by mass or more, more preferably 50 ppm by mass or more, still more preferably 100 ppm by mass or more, and particularly preferably 300 ppm by mass or more. Moreover, the upper limit of the Sb content is preferably 1150 mass ppm or less, and more preferably 500 mass ppm or less.

The lower limit of the Bi content is preferably 25 ppm by mass or more, more preferably 50 ppm by mass or more, still more preferably 75 ppm by mass or more, particularly preferably 100 ppm by mass or more, and most preferably 250 ppm. It is mass ppm or more. Moreover, the upper limit of Bi content becomes like this. Preferably it is 1000 mass ppm or less, More preferably, it is 600 mass ppm or less, More preferably, it is 500 mass ppm or less.
The lower limit of the Pb content is preferably 25 ppm by mass or more, more preferably 50 ppm by mass or more, further preferably 75 ppm by mass or more, particularly preferably 100 ppm by mass or more, and most preferably 250 ppm. The mass is pp or more. Further, the upper limit of the Pb content is preferably 5000 ppm by mass or less, more preferably 1000 ppm by mass or less, still more preferably 850 ppm by mass or less, and particularly preferably 500 ppm by mass or less.

  Even if Sb, Bi, and Pb all constitute an alloy (intermetallic compound, solid solution, etc.) together with Sn or an Sn-based alloy, if the content with respect to the mass of the entire solder material satisfies the above-described conditions. Alternatively, a part thereof may exist separately from the Sn-based alloy.

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

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

  As, Sb, Bi, and Pb are all elements that have an effect of suppressing the increase in clay when used as a paste (thickening suppressing effect). From the viewpoint of suppressing thickening, the total of these is 275 ppm or more. Preferably there is. The reason why the As content is doubled in the formula (1) is that As has a higher viscosity-inhibiting effect than Sb, Bi, or Pb.

  2As + Sb + Bi + Pb is preferably 350 or more, more preferably 1200 or more. On the other hand, 2As + Sb + Bi + Pb has no upper limit, but from the viewpoint of making ΔT a suitable range, it is preferably 25200 or less, more preferably 18600 or less, still more preferably 10200 or less, and particularly preferably 5300 or less (preferably 3800 or less).

  The following formulas (1a) and (1b) are obtained by appropriately selecting the upper limit and the lower limit 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 content (mass ppm) in each solder material.

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

  Generally, when the contents of As and Sb are large, the wettability of the solder material tends to deteriorate. On the other hand, Bi and Pb suppress deterioration of wettability due to containing As, but if the content is too large, ΔT spreads, and thus strict management is required. In particular, in an alloy composition containing Bi and Pb at the same time, ΔT tends to spread, and ΔT spreads when the content of Bi and Pb is increased to improve wettability excessively. On the other hand, when the content of As or Sb is increased to improve the thickening suppressing effect, the wettability deteriorates. However, if it is divided into the group of As and Sb and the group of Bi and Pb so that the total content of both groups satisfies the relationship of formula (2), the content of the group of As and Sb and the content of Bi and Pb group The balance between the amounts becomes appropriate, and the thickening suppressing effect, the narrowing of ΔT, and the wettability can all be satisfied simultaneously.

  When (2As + Sb) / (Bi + Pb) is less than 0.01, the sum of the contents of Bi and Pb becomes relatively larger than the sum of the contents of As and Pb, so that ΔT spreads. (2As + Sb) / (Bi + Pb) is preferably 0.01 or more, more preferably 0.02 or more, still more 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 sum of the contents of As and Sb becomes relatively larger than the sum of the contents of Bi and Pb, so that the wettability deteriorates. (2As + Sb) / (Bi + Pb) is preferably 10.00 or less, more preferably 5.33 or less, further preferably 4.50 or less, still more preferably 2.67 or less, and particularly preferably Is 4.18 or less, and most preferably 2.30 or less.

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

  What selected the upper limit and the lower limit suitably from the said preferable aspect is following (2a) Formula.

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

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

  In the present embodiment, the solder paste may further include zirconium oxide powder. 0.05-20.0 mass% is preferable, as for content of the zirconium oxide powder with respect to the mass of the whole solder paste, 0.05-10.0 mass% is more preferable, and 0.1-3 mass% is the most preferable. If 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 is 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 a projected circle of which the projected circle equivalent diameter is 0.1 μm or more when a SEM photograph of the zirconium oxide powder is taken and the projected circle equivalent diameter is obtained by image analysis for each particle present in the field of view. The average value of equivalent diameters is used. The shape of the zirconium oxide particles is not particularly limited. However, if the shape is different, the contact area with the flux is large, and a thickening suppressing effect is obtained. In the case of a spherical shape, good fluidity can be obtained, so that excellent printability as a paste can be obtained. What is necessary is just to select a shape suitably according to a desired characteristic.

  The method for producing the solder material of the present embodiment is not particularly limited, and examples thereof include a method for producing by melting and mixing raw material metals.

  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 from the viewpoint of excellent fluidity, and more preferably a powder form.

  Examples of the method for producing the particulate solder material include a dropping method in which a molten solder material is dropped to obtain particles, a spraying method in which centrifugal spraying is performed, and a method in which a bulk solder material is pulverized. 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 obtain particles.

Further, when the solder material is in the form of particles, the solder material has a size (particle size distribution) corresponding to symbols 1 to 8 in the powder size classification (Table 2) in JIS Z 3284-1: 20 14. Preferably, it has a size (particle size distribution) corresponding to symbols 4 to 8, and more preferably has a size (particle size distribution) corresponding to symbols 5 to 8. Thereby, soldering to a fine part is attained.

[flux]
In this specification, “flux” refers to the entire component other than the solder material in the solder paste.

(Metal deactivator)
The flux contains a metal deactivator. The metal deactivator refers to a compound having the performance of preventing the metal from being deteriorated by contact with a certain compound.

  The metal deactivator contains a nitrogen compound. When the flux contains a nitrogen compound, the solder paste can improve the thickening suppressing effect.

  The nitrogen compound is not particularly limited as long as it is a compound containing a nitrogen atom and used as a metal deactivator. The nitrogen compound is preferably at least one selected from the group consisting of a hydrazide nitrogen compound, an amide nitrogen compound, a triazole nitrogen compound, and a melamine nitrogen compound, from the viewpoint of excellent thickening suppression effect. More preferably, it is at least one selected from the group consisting of nitrogen compounds and triazole nitrogen compounds.

  The hydrazide nitrogen compound may be any nitrogen compound having a hydrazide skeleton, such as bis [N2- (2hydroxybenzoyl) hydrazide] dodecanedioate, N, N′-bis [3- (3,5-di-tert). -Butyl-4-hydroxyphenyl) propionyl] hydrazine, decanedicarboxylic acid disalicyloyl hydrazide, N-salicylidene-N'-salicyl hydrazide, m-nitrobenzhydrazide, 3-aminophthalhydrazide, phthalic acid dihydrazide, adipic acid hydrazide Oxalobis (2-hydroxy-5-octylbenzylidene hydrazide), N'-benzoylpyrrolidone carboxylic acid hydrazide, N, N'-bis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) And hydrazine.

  The amide-based nitrogen compound may be any nitrogen compound having an amide skeleton, and N, N′-bis {2- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxyl] ethyl } Oxamide etc. are mentioned.

  As the triazole-based nitrogen compound, any nitrogen compound having a triazole skeleton may be used, and N- (2H-1,2,4-triazol-5-yl) salicylamide, 3-amino-1,2,4-triazole, 3- (N-salicyloyl) amino-1,2,4-triazole and the like can be mentioned.

  The melamine nitrogen compound may be any nitrogen compound having a melamine skeleton, and examples thereof include melamine and melamine derivatives.

  The content of the nitrogen compound is more than 0 and preferably 10% by mass or less, more preferably 0.05 to 5.0% by mass, and 0.10 to 2.0% with respect to the entire flux. More preferably, it is mass%. When the content exceeds 0% by mass, the solder paste is excellent in the thickening suppressing effect.

  The metal deactivator may further contain a hindered phenol compound. When the metal deactivator contains a hindered phenol-based compound, the solder paste is excellent in the thickening suppressing effect. The hindered phenol-based compound is not particularly limited, and examples thereof include 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-t-butyl-4-hydroxy-hydro Nnamamide), 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 singly or in combination of two or more.

  0-10 mass% may be sufficient as content of a hindered phenol type compound with respect to the whole flux, for example.

  The flux preferably contains a resin. 30-60 mass% may be sufficient as content of resin with respect to the whole flux, for example.

  The resin is not particularly limited. For example, rosin resin, (meth) acrylic resin, urethane resin, polyester resin, phenoxy resin, vinyl ether resin, terpene resin, modified terpene resin (for example, 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) Maleic resin), xylene resin, modified xylene resin (for example, phenol modified xylene resin, alkylphenol modified xylene resin, phenol modified resole type xylene resin, polyol modified xylene resin, polyoxyethylene-added xylene resin, etc.).These resins are used alone or in combination of two or more. Among these, the resin is preferably at least one selected from the group consisting of rosin resins and (meth) acrylic resins. The “(meth) acrylic resin” here refers to a concept including a methacrylic resin and an acrylic resin.

  Examples of the rosin resin include raw material rosins such as gum rosin, wood rosin, tall oil rosin, and derivatives obtained from raw rosin. Examples of the derivatives include 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, and polymerized rosin. Examples include purified products, hydrides and disproportionates, and purified products, hydrides and disproportions of α, β-unsaturated carboxylic acid modified products. These rosin resins are used singly or in combination of two or more.

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

  Examples of the (meth) acrylic resin include a homopolymer of a (meth) acrylic monomer and a copolymer of two or more (meth) acrylic monomers. (Meth) acrylic monomers include (meth) acrylic acid, itaconic acid, maleic acid, crotonic acid, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (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 singly or in combination of two or more.

  The resin can improve the temperature cycle reliability by containing a (meth) acrylic resin. When repeated thermal stresses of high temperature and low temperature are applied to the mounting portion or the joint portion, a material with high crystallinity such as rosin may break and absorb moisture from the crack. On the other hand, the crack is suppressed by including a soft (meth) acrylic resin in the resin, and as a result, temperature cycle reliability can be improved. The content of the (meth) acrylic resin is, for example, 0 to 40% by mass with respect to the entire flux, and is 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 with respect 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 activator (organic acid) in order 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, 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- Quinoline carboxylic 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.

  0-10 mass% may be sufficient as content of an organic acid with respect to the whole flux, for example.

  The flux may contain an amine activator (amine) in order to improve solderability. Examples of amines include amine aliphatic amines, aromatic amines, amino alcohols, imidazoles, benzotriazoles, amino acids, guanidines, hydrazides and the like. Examples of the aliphatic amine include dimethylamine, ethylamine, 1-aminopropane, isopropylamine, trimethylamine, allylamine, n-butylamine, diethylamine, sec-butylamine, tert-butylamine, N, N-dimethylethylamine, isobutylamine, cyclohexyl An amine etc. are mentioned. Examples of the aromatic amine include aniline, N-methylaniline, diphenylamine, N-isopropylaniline, p-isopropylaniline and the like. Examples of amino alcohols include 2-aminoethanol, 2- (ethylamino) ethanol, diethanolamine, diisopropanolamine, triethanolamine, N-butyldiethanolamine, triisopropanolamine, N, N-bis (2-hydroxyethyl). -N-cyclohexylamine, N, N, N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine, N, N, N ′, N ″, N ″ -pentakis (2-hydroxypropyl) diethylenetriamine, etc. Can be mentioned. Examples of imidazole include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4- 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, 2 -Methylbenzimidazole, 2-octylbenzimidazole, 2-pentylbenzimidazole, 2- (1-ethylpentyl) benzimidazole, 2-nonylbenzimidazole, 2- (4-thiazolyl) benzimidazole, benzimidazole, etc. . Amino acids include alanine, arginine, asparagine, aspartic acid, cysteine hydrochloride, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine monohydrochloride, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine, Examples include β-alanine, γ-aminobutyric acid, δ-aminovaleric acid, ε-aminohexanoic acid, ε-caprolactam, and 7-aminoheptanoic acid.

  0-20 mass% may be sufficient as content of an amine with respect to the whole flux, for example.

  The flux may contain a covalent halogen activator (covalent halogen) in order to improve solderability. Examples of the covalently bonded 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, triallyl isocyanurate hexabromide, 2,2-bis [3,5 -Dibromo-4- (2,3-dibromopropoxy) phenyl] propane, bis [3,5-dibromo-4- (2,3-dibromopropoxy) phenyl] sulfo , Ethylene bispentabromobenzene, 2-chloromethyloxirane, het acid, het acid anhydride, brominated bisphenol A type epoxy resin, and the like.

  The content of the covalent bond halogen may be, for example, 0 to 5% by mass with respect to the entire flux.

  The flux may contain an amine hydrohalide activator (amine hydrohalide) to improve solderability. Examples of the amine hydrohalides include the amine hydrohalides exemplified as the amine. Examples of the amine hydrohalide include 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-pipecoline hydrobromide, 1,3-diphenylguanidine hydrochloride, dimethylbenzylamine hydrochloride, hydrazine hydrate odor Hydrohalide, dimethylcyclohexylamine hydrochloride Trinonylamine hydrobromide, diethylaniline hydrobromide, 2-diethylaminoethanol hydrobromide, 2-diethylaminoethanol hydrochloride, ammonium chloride, diallylamine hydrochloride, diallylamine hydrobromide, monoethylamine Hydrochloride, monoethylamine hydrobromide, diethylamine hydrochloride, triethylamine hydrobromide, triethylamine hydrochloride, hydrazine monohydrochloride, hydrazine dihydrochloride, hydrazine monohydrobromide, hydrazine dihydrobromide Salt, pyridine hydrochloride, aniline hydrobromide, butylamine hydrochloride, hexylamine hydrochloride, n-octylamine hydrochloride, dodecylamine hydrochloride, dimethylcyclohexylamine hydrobromide, ethylenediamine dihydrobromide Rosinamine hydrobromide, 2-Fe Ruimidazole hydrobromide, 4-benzylpyridine hydrobromide, L-glutamate hydrochloride, N-methylmorpholine hydrochloride, betaine hydrochloride, 2-pipecoline hydroiodide, cyclohexylamine hydroiodide 1,3-diphenylguanidine hydrofluoride, diethylamine hydrofluoride, 2-ethylhexylamine hydrofluorate, cyclohexylamine hydrofluorate, ethylamine hydrofluoride, rosinamine hydrogen fluoride Examples thereof include acid salts, cyclohexylamine tetrafluoroborate, and dicyclohexylamine tetrafluoroborate.

  The content of the amine hydrohalide may be, for example, 0 to 2% by mass with respect to 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, 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] A 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, hexyl diglycol. And tetraethylene glycol dimethyl ether.

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

  The flux may contain a thixotropic agent. Examples of thixotropic agents include wax-based thixotropic agents and amide-based thixotropic agents. Examples of wax-based thixotropic agents include castor oil. Examples of the amide thixotropic agent include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, saturated fatty acid amide, oleic acid amide, erucic acid amide, unsaturated fatty acid amide, p-toluene. Methane amide, aromatic amide, methylene bis stearic acid amide, ethylene bis lauric acid amide, ethylene bis hydroxystearic 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.

  0-15 mass% may be sufficient as content of a thixotropic agent with respect to the whole flux, for example.

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

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

  The solder paste of the present embodiment is used for, for example, a circuit board having a fine structure in an electronic device, and specifically, by a printing method using a metal mask, a discharge method using a dispenser, or a transfer method using a transfer pin. It can be applied to the soldering part and reflowed.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to the content as described in an Example.

(Adjustment of solder powder)
Powders were prepared by melting and mixing the metals shown in Tables 1 and 2 so as to have the compositions shown in Tables 1 to 5 and centrifugally spraying them in an Ar atmosphere. The numerical value in each table | surface represents content (mass%) of each metal when the sum total of a solder powder shall be 100 mass%, and "Bal" represents the remainder. 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.

(Flux preparation)
Each material shown in Table 1 and Table 2 was heated and stirred so as to have the composition shown in Tables 1 to 5, and then cooled to prepare a flux. The numerical value in each table | surface represents content (mass%) of each material when the sum total of a flux shall be 100 mass%. The reagent name and CAS number of each material shown in the table are shown below.

・ "Metal deactivator A"
Reagent name: N- (2H-1,2,4-triazol-5-yl) salicylamide CAS No. 36411-52-6
・ "Metal deactivator B"
Reagent name: Bis dodecanedioic acid [N2- (2-hydroxybenzoyl) hydrazide]
CAS No. 63245-38-5
・ "Metal deactivator C"
Reagent name: bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionic acid] [ethylene bis (oxyethylene)]
CAS No. 36443-68-2
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 hexabromide 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 hydrogenated oil CAS No. 8001-78-3

(Preparation of solder paste)
The solder powder and the flux were kneaded so that the mass ratio (solder powder: flux) was 89:11 to prepare a solder paste.

  (1) Thickening suppression evaluation was performed about the solder paste of each Example and the comparative example, and (2) Reliability evaluation was performed about the solder powder used by each Example and the comparative example. Each evaluation method is shown below, and the evaluation results are shown in Tables 1 to 3.

(1) Viscosity suppression evaluation For the obtained solder paste, a rotational viscometer (PCU-205, manufactured by Malcolm Co., Ltd.) was used according to the method described in “4.2 Viscosity characteristics test” of JIS Z 3284-3. The viscosity was continuously measured for 12 hours at a rotational speed of 10 rpm and a measurement temperature of 25 ° C. Then, the initial viscosity (viscosity after 30 minutes of stirring) was compared with the viscosity after 12 hours, and the thickening suppression effect was evaluated based on the following criteria.
Viscosity after 13 hours ≦ Initial viscosity × 1.2: Good increase in viscosity over time
Viscosity after 13 hours> Initial viscosity × 1.2: Large increase in viscosity over time and poor (×)

(2) Reliability evaluation About the obtained solder powder, using a differential scanning calorimeter (EXSTAR DSC7020, manufactured by SII Nano Technology Co., Ltd.), the rate of temperature increase is 5 ° C./min (180 ° C. to 250 ° C.). The temperature drop rate: -3 ° C./min (250 ° C. to 150 ° C.), DSC measurement was performed under the measurement conditions of carrier gas: N ₂ , and the liquidus temperature (T _L ) and the solidus temperature (T _S ) were measured. 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 (×)
When the difference (ΔT = T _L −T _S ) between the liquidus temperature (T _L ) and the solidus temperature (T _S ) of the solder powder is large, 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 tends to be deposited on the surface of the solder powder. If a structure with a high melting point is deposited on the surface of the solder powder, then a structure with a low melting point is successively deposited toward the inside of the solder powder, and the structure of the solder powder tends to be non-uniform, reducing the reliability such as cycleability. Cause.

(3) Evaluation of wettability In the same manner as in “(1) Evaluation of suppression of thickening”, the solder pastes of the examples and comparative examples were formed on a Cu plate with an aperture diameter of 6.5 mm, an aperture of 4 pieces, and a mask. Printing was performed using a metal mask having a thickness of 0.2 mm, heated in a reflow oven from 25 ° C. to 260 ° C. in a N ₂ atmosphere at a heating rate of 1 ° C./sec, and then air-cooled to room temperature (25 ° C.). Individual solder bumps were formed. Using an optical microscope (magnification: 100 times), the appearance of the obtained solder bumps was observed and evaluated based on the following criteria.
Solder particles that could not be melted were observed in all four solder bumps.
: Good solder wettability (○)
Solder particles that could not be melted in one or more of the four solder bumps were observed.
: Poor solder wettability (×)

  Since the solder paste of this invention is excellent also in reliability, such as a thickening inhibitory effect and cycling characteristics, it can be utilized for various uses.

Claims (5)

Solder paste consisting of solder material and flux,
The solder material is at least one of As: 20-300 mass ppm, Pb: more than 0 mass ppm and less than 5100 mass ppm, and Sb: more than 0 mass ppm and less than 3000 mass ppm, and Bi: more than 0 mass ppm and less than 10,000 mass ppm. A seed, as well as an alloy composition with the balance being 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 Formula (1) and Formula (2), As, Sb, Bi, and Pb represent content (mass ppm) in each solder material.)
The solder paste in which the flux contains a metal deactivator, and the metal deactivator contains a nitrogen compound.   The solder paste according to claim 1, wherein the nitrogen compound is at least one selected from the group consisting of hydrazide nitrogen compounds, amide nitrogen compounds, triazole nitrogen compounds, and melamine nitrogen compounds.   The solder paste according to claim 1, wherein the nitrogen compound is at least one selected from the group consisting of a hydrazide nitrogen compound and a triazole nitrogen compound.   The solder paste according to any one of claims 1 to 3, wherein a content of the nitrogen compound is more than 0 and 10% by mass or less with respect to the entire flux. The solder paste according to claim 1, wherein the solder material has a particulate form.