KR20220141914A - Solder alloy, solder powder, solder paste, solder ball, solder preform and solder joint - Google Patents

Abstract

U: less than 5 mass ppb, Th: less than 5 mass ppb, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Ni: 0 mass ppm or more and 600 mass ppm or less, and Fe: 0 mass ppm or more and 100 mass ppm or more. A solder alloy having an alloy composition of mass ppm or less and the balance consisting of Sn, satisfying Equation (1), and having an α dose of 0.02 cph/cm 2 or less is employed.
20≤Ni+Fe≤700 (1)
(1) In formula, Ni and Fe represent content (mass ppm) in an alloy composition. According to the solder alloy of the present invention, it is possible to suppress the increase in the viscosity of the solder paste over time, to make it difficult to cause a short circuit in the circuit, to increase the mechanical strength of the solder joint, and to suppress the occurrence of soft errors.

Description

Solder alloy, solder powder, solder paste, solder ball, solder preform and solder joint

FIELD OF THE INVENTION The present invention relates to solder alloys, solder powders, solder pastes, solder balls, solder preforms and solder joints.

This application claims priority based on Japanese Patent Application No. 2020-070927 for which it applied to Japan on April 10, 2020, The content is used here.

DESCRIPTION OF RELATED ART In the electronic component mounted on a printed circuit board, size reduction and performance improvement are calculated|required more and more. As such an electronic component, a semiconductor package is mentioned, for example. In a semiconductor package, the semiconductor element which has an electrode is sealed with the resin component. A solder bump made of a solder material is formed on this electrode. Further, the solder material connects the semiconductor element and the printed circuit board.

In solder materials, the influence of α-rays on soft errors becomes a problem. In order to reduce such a bad influence on the operation|movement of a semiconductor element, the development of the low alpha-dose material containing a solder material is carried out.

The factor serving as the α-ray source is, for example, a trace amount of radioactive element contained in the solder alloy in the solder material, particularly the tin (Sn) metal used as the base. A solder alloy can be manufactured by melt-mixing a raw material metal. In such a solder alloy, in order to design a low α-dose material, it is important to remove radioactive elements that become upstream, such as uranium (U), thorium (Th), and polonium (Po), from the alloy composition.

On the other hand, it is not technically difficult to remove U, Th, and Po in the refining of Sn metal (for example, refer patent document 1).

In general, Sn contains lead (Pb) and bismuth (Bi) as impurities. ²¹⁰ Pb and ²¹⁰ Bi, which are radioactive isotopes in Pb and Bi, undergo β decay to ²¹⁰ Po, and ²¹⁰ Po decays to α to produce ²⁰⁶ Pb, generating α rays. It is said that this series of abnormal changes (uranium-based) is the main cause of the generation of α-rays from the solder material.

In addition, in the evaluation of the amount of α radiation generated from a material, “cph/cm 2 ” is often used as a unit. "cph/cm2" is an abbreviation of "counts per hours/cm2", and means the number of counts of α-rays per 1cm2 and per hour.

About the half-life of Pb and Bi, it is as follows.

For Bi, the half-life of ²¹⁰ Bi is about 5 days. For Pb, the half-life of ²¹⁰ Pb is about 22.3 years. In addition, it is said that these influence degrees (abundance ratio) can be expressed by the following formula (refer nonpatent literature 1). That is, the influence of Bi on the generation of α-rays is very low compared to that of Pb.

[ ²¹⁰ Bi]≒[ ²¹⁰ Pb]/1.6×10 ³

In the formula, [ ²¹⁰ Bi] represents the molar concentration of ²¹⁰ Bi. [ ²¹⁰ Pb] represents the molar concentration of ²¹⁰ Pb.

As described above, conventionally, in the design of a low α-dose material, it is common to remove U and Th and thoroughly remove Pb.

In addition, it is known that the α-ray dose generated from the solder material basically increases with the lapse of time. It is said that this is caused by β decay of radioactive Pb and radioactive Bi in the solder alloy to increase the amount of Po, and α aberration of Po to generate α rays.

In materials with extremely low α dose, these radioactive elements are rarely contained, but segregation of ²¹⁰ Po is the cause, and the α dose increases with time in some cases. ²¹⁰ Po originally radiated α-rays, but during solidification of the solder alloy, it segregates in the central portion of the solder alloy, so that the radiating α-rays are shielded by the solder alloy. And ²¹⁰ Po is uniformly dispersed in the alloy with the lapse of time, and since it also exists on the surface where the α-ray is detected, the amount of α-ray increases with the passage of time (refer to Non-Patent Document 2).

As described above, the amount of α radiation generated increases under the influence of trace amounts of impurities contained in the solder alloy. For this reason, in the design of a low α-dose material, it becomes difficult to simply add various elements as in the conventional manufacturing method of a solder alloy.

For example, the method of adding arsenic (As) to a solder alloy is known for the thickening suppression which suppresses the viscosity increase with time of a soldering paste (for example, refer patent document 2).

By the way, among the mounting on a printed circuit board as described above, a method of inserting a terminal into a through hole of the board and mounting the electronic component having a certain size is adopted from the viewpoint of connection strength and the like. As an operation of mounting such an electronic component, flow soldering is usually used. Flow soldering is a method of soldering by bringing the solder jetting surface of a solder bath into contact with the connection surface of a printed circuit board.

In flow soldering, a solder bath is required. In the solder bath, hot molten solder flows for a long time. For this reason, from a viewpoint of corrosion resistance, stainless steel etc. whose main component is iron (Fe) are used as a material of a solder bath. However, with prolonged use, the inner surface of the solder bath may be eroded by Fe corrosion.

Patent Document 3 discloses a solder alloy containing a predetermined amount of Fe and Ge in order to suppress Fe corrosion of a solder bath in flow soldering.

Japanese Patent Laid-Open No. 2010-156052 Japanese Patent Laid-Open No. 2015-98052 Japanese Patent Laid-Open No. 2008-168322

Radioactive Nuclei Induced Soft Errors at Ground Level; IEEE TRANSACTIONS ON NUCLEAR SCIENCE, DECEMBER 2009, VOL.56, NO.6, p.3437-3441 Energy Dependent Efficiency in Low Background Alpha Measurements and Impacts on Accurate Alpha Characterization; IEEE TRANSACTIONS ON NUCLEAR SCIENCE, DECEMBER 2015, VOL.62, NO.6, p.3034-3039

In the method of adding As to a solder alloy like the method of patent document 2 for suppressing the thickening in time-lapse|temporality of a solder paste, for example, when As is added, an impurity will also be contained in an alloy. In this case, the presence of a radioactive element in the impurity increases the amount of α radiation generated from the solder material.

Further, like the solder alloy described in Patent Literature 3, in a solder alloy containing Sn as a main component, when a large amount of Fe is contained, needle crystals derived from the SnFe compound are precipitated, and there is a fear that the circuit may be short-circuited.

In addition, in the solder alloy containing Sn as a main component, a large amount of nickel (Ni) may be contained in order to improve wettability. When there is much Ni content, a SnCuNi compound may precipitate in the vicinity of the bonding interface of a solder alloy, and there exists a possibility that the mechanical strength of a solder joint may fall.

The present invention has been made in view of the above circumstances, and it is possible to suppress the increase in the viscosity of the solder paste over time, it is difficult to cause a short circuit in the circuit, it is possible to increase the mechanical strength of the solder joint, and it is also possible to suppress the occurrence of a soft error. An object of the present invention is to provide a possible solder alloy, a solder powder made of this solder alloy, a solder paste containing the solder powder and flux, a solder ball made of this solder alloy, a solder preform, and a solder joint.

The present inventors studied for the purpose of designing a low α-dose solder alloy capable of suppressing the thickening of the solder paste over time without adding As accompanied by impurities containing radioactive elements. According to these studies, Sn as a main component and an alloy composition containing predetermined amounts of Ni having a melting point of 1455° C. and Fe having a melting point of 1538° C., which are high-melting-point metals heated at high temperatures during refining or processing, as an alloy composition, It discovered that the objective could be achieved, and came to complete this invention.

That is, in order to solve the said subject, this invention employ|adopts the following means.

[1] U: less than 5 mass ppb, Th: less than 5 mass ppm, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Ni: 0 mass ppm or more and 600 mass ppm or less, and Fe: 0 mass ppm or more 100 A solder alloy having an alloy composition of mass ppm or less and the remainder being Sn, satisfying the following formula (1), and having an α dose of 0.02 cph/cm 2 or less.

20≤Ni+Fe≤700 (One)

(1) In formula, Ni and Fe respectively represent content (mass ppm) in the said alloy composition.

[2] U: less than 5 mass ppb, Th: less than 5 mass ppm, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Ni: 0 mass ppm or more and 600 mass ppm or less, and Fe: 0 mass ppm or more, 100 mass ppm A solder alloy having an alloy composition of mass ppm or less and the remainder being Sn, satisfying the following formula (1), and having an α dose of 0.02 cph/cm 2 or less.

20≤Ni+Fe≤700 (One)

(1) In formula, Ni and Fe respectively represent content (mass ppm) in the said alloy composition.

[3] The solder alloy according to [1] or [2], wherein the alloy composition satisfies the following formula (1').

40≤Ni+Fe≤200 (One')

In formula (1'), Ni and Fe each represent content (mass ppm) in the said alloy composition.

[4] The solder alloy according to any one of [1] to [3], wherein Pb is less than 2 mass ppm.

[5] The solder alloy according to any one of [1] to [4], wherein As is less than 2 mass ppm.

[6] In addition, the alloy composition according to any one of [1] to [5], wherein the alloy composition contains at least one of Ag: 0 mass% or more and 4 mass% or less and Cu: 0 mass% or more and 0.9 mass% or less. The solder alloys described.

[7] U: less than 5 mass ppb, Th: less than 5 mass ppm, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Ni: greater than 0 mass ppm and 600 mass ppm or less, and Fe: greater than 0 mass ppm 100 It has an alloy composition consisting of at least one of mass ppm or less, Ag: more than 0 mass% and 4 mass% or less, and Cu: more than 0 mass% and 0.9 mass% or less, and the balance is Sn, and satisfies the following formula (1), Further, the solder alloy having an α dose of 0.02 cph/cm 2 or less.

20≤Ni+Fe≤700 (One)

(1) In formula, Ni and Fe respectively represent content (mass ppm) in the said alloy composition.

[8] U: less than 5 mass ppb, Th: less than 5 mass ppm, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Ni: more than 0 mass ppm and 600 mass ppm or less, and Fe: 0 mass ppm or more 100 mass ppm or less, Cu: more than 0 mass % and 0.9 mass % or less, and the balance has an alloy composition consisting of Sn, the following formula (1) is satisfied, and the ratio of Cu and Ni is a mass ratio expressed by Cu/Ni. , 8 or more and 175 or less, and an α dose of 0.02 cph/cm 2 or less.

20≤Ni+Fe≤700 (One)

(1) In formula, Ni and Fe respectively represent content (mass ppm) in the said alloy composition.

[9] U: less than 5 mass ppb, Th: less than 5 mass ppm, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Ni: 0 mass ppm or more and 600 mass ppm or less, and Fe: 0 mass ppm or more 100 mass ppm or less, Cu: more than 0 mass % and 0.9 mass % or less, and the balance has an alloy composition consisting of Sn, the following formula (1) is satisfied, and the ratio of Cu, Ni, and Fe is Cu/(Ni+Fe) ), which is 7 or more and 350 or less, and has an α dose of 0.02 cph/cm 2 or less.

20≤Ni+Fe≤700 (One)

(1) In formula, Ni and Fe respectively represent content (mass ppm) in the said alloy composition.

[10] U: less than 5 mass ppb, Th: less than 5 mass ppm, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Ni: 0 mass ppm or more and 600 mass ppm or less, and Fe: more than 0 mass ppm 100 mass ppm or less, Cu: more than 0 mass % and 0.9 mass % or less, and the balance has an alloy composition consisting of Sn, the following formula (1) is satisfied, and the ratio of Cu and Fe is a mass ratio expressed by Cu/Fe , 50 or more and 350 or less, and the α dose is 0.02 cph/cm 2 or less.

20≤Ni+Fe≤700 (One)

(1) In formula, Ni and Fe respectively represent content (mass ppm) in the said alloy composition.

[11] The solder alloy according to any one of [7] to [10], wherein the ratio of Ni and Fe is a mass ratio expressed by Ni/Fe, and is 0.4 or more and 30 or less.

[12] The solder alloy according to any one of [8] to [11], wherein the alloy composition contains Ag: more than 0 mass% and 4 mass% or less.

[13] The alloy composition according to any one of [1] to [12], wherein the alloy composition contains at least one of Bi: 0 mass% or more and 0.3 mass% or less and Sb: 0 mass% or more and 0.9 mass% or less. The solder alloy described in.

[14] The solder alloy according to [13], wherein the alloy composition satisfies the following formula (2).

0.03≤Bi+Sb≤1.2 (2)

(2) In formula, Bi and Sb respectively represent content (mass %) in the said alloy composition.

[15] to a solder alloy sheet molded into a sheet shape having an area of 900 cm on one side, after heat treatment at 100 ° C. for 1 hour, the α dose becomes 0.02 cph/cm 2 or less, [1] to The solder alloy according to any one of [14].

[16] The solder alloy according to any one of [1] to [15], wherein the α dose is 0.002 cph/cm 2 or less.

[17] The solder alloy according to [16], wherein the α dose is 0.001 cph/cm 2 or less.

[18] A solder powder comprising the solder alloy according to any one of [1] to [17].

[19] The solder powder according to [18], wherein two or more types of solder alloy particle groups having different particle size distributions are shared.

[20] A solder paste comprising the solder powder according to [18] or [19] and a flux.

[21] A solder ball comprising the solder alloy according to any one of [1] to [17].

[22] A solder preform comprising the solder alloy according to any one of [1] to [17].

[23] A solder joint comprising the solder alloy according to any one of [1] to [17].

Advantageous Effects of Invention According to the present invention, a solder alloy capable of suppressing an increase in the viscosity of a solder paste over time, making it difficult to cause a short circuit, increasing the mechanical strength of a solder joint, and suppressing the occurrence of a soft error, this solder A solder powder made of an alloy, a solder paste containing the solder powder and a flux, a solder ball made of the solder alloy, a solder preform, and a solder joint can be provided.

The present invention will be described in detail below.

In this specification, "ppb" regarding a solder alloy composition is "mass ppb" unless otherwise specified. "ppm" is "mass ppm" unless otherwise specified. "%" is "mass %" unless otherwise specified.

(solder alloy)

The solder alloy according to one aspect of the present invention includes: U: less than 5 mass ppb, Th: less than 5 mass ppb, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Ni: 0 mass ppm or more and 600 mass ppm or less; and Fe: 0 mass ppm or more and 100 mass ppm or less, and the balance has an alloy composition comprising Sn, satisfies the following formula (1), and the α dose is 0.02 cph/cm 2 or less.

20≤Ni+Fe≤700 (One)

(1) In formula, Ni and Fe respectively represent content (mass ppm) in the said alloy composition.

<alloy composition>

The solder alloy of this embodiment has U: less than 5 mass ppb, Th: less than 5 mass ppm, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Ni: 0 mass ppm or more and 600 mass ppm or less, and Fe: It has an alloy composition in which 0 mass ppm or more and 100 mass ppm or less, and remainder consists of Sn, and satisfy|fills said (1) Formula.

≪U: less than 5 mass ppb, Th: less than 5 mass ppb≫

U and Th are radioactive elements. In order to suppress the occurrence of soft errors, it is necessary to suppress the content of these in the solder alloy.

In the present embodiment, the contents of U and Th in the solder alloy are each less than 5 ppb with respect to the total mass (100 mass%) of the solder alloy from the viewpoint of making the α dose generated from the solder alloy 0.02 cph/cm 2 or less. to be. From the viewpoint of suppressing the occurrence of soft errors in high-density packaging, the contents of U and Th are preferably 2 ppb or less, respectively, and the lower it is, the better.

≪Pb: less than 5 mass ppm≫

In general, Sn contains Pb as an impurity. The radioisotope in this Pb decays β to ²¹⁰ Po, and ²¹⁰ Po decays to α to generate α ray when ²⁰⁶ Pb is produced. From this point of view, it is preferable that the content of Pb as an impurity in the solder alloy is also as small as possible.

In the present embodiment, the content of Pb in the solder alloy is less than 5 ppm, preferably less than 2 ppm, more preferably less than 1 ppm with respect to the total mass (100 mass%) of the solder alloy. Further, the lower limit of the content of Pb in the solder alloy may be 0 ppm or more.

«As: less than 5 mass ppm»

Addition of As to the solder alloy is effective for suppressing the thickening of the solder paste over time, but with the addition of As, a radioactive element is also included in the alloy, and the amount of α radiation generated from the solder material increases.

In this embodiment, it aims at aiming at the thickening suppression over time of a solder paste, without adding As accompanying the impurity containing a radioactive element.

In the present embodiment, the content of As in the solder alloy is less than 5 ppm, preferably less than 2 ppm, and more preferably less than 1 ppm with respect to the total mass (100 mass%) of the solder alloy. Further, the lower limit of the content of As in the solder alloy may be 0 ppm or more.

≪Ni: 0 mass ppm or more and 600 mass ppm or less, Fe: 0 mass ppm or more and 100 mass ppm or less, formula (1)≫

By soldering, in the vicinity of the bonding interface in the solder alloy, formation of a Sn-containing intermetallic compound (an intermetallic compound containing Sn) proceeds, and when this Sn-containing intermetallic compound is precipitated, the mechanical strength of the solder joint deteriorates. do.

Ni: 0 mass ppm or more and 600 mass ppm or less

Ni is an element which suppresses formation of a Sn-containing intermetallic compound at a bonding interface.

When the solder alloy contains Ni, the formation of the Sn-containing intermetallic compound is suppressed, and the mechanical strength of the solder joint is maintained. On the other hand, when the content of Ni in the solder alloy exceeds 600 ppm, SnNi compounds are precipitated in the vicinity of the bonding interface in the solder alloy, and there is a fear that the mechanical strength of the solder joint is deteriorated.

In the present embodiment, the content of Ni in the solder alloy is 0 ppm or more and 600 ppm or less, preferably more than 0 ppm and 600 ppm or less, more preferably 20 ppm or more and 600 ppm or less, with respect to the total mass (100 mass%) of the solder alloy. , More preferably 40 ppm or more and 600 ppm or less.

Fe: 0 mass ppm or more and 100 mass ppm or less

Fe is an element which suppresses formation of a Sn-containing intermetallic compound at a bonding interface similarly to Ni. Moreover, within the range of the predetermined content, precipitation of needle crystals by the SnFe compound is suppressed, and short circuit of the circuit can be prevented.

The "acicular crystal" as used herein refers to a crystal having an aspect ratio of 2 or more, which is a ratio of a major axis to a minor axis, in a crystal derived from one SnFe compound.

In the present embodiment, the content of Fe in the solder alloy is 0 ppm or more and 100 ppm or less, preferably more than 0 ppm and 100 ppm or less, more preferably 20 ppm or more and 100 ppm or less, with respect to the total mass (100 mass%) of the solder alloy. , more preferably 40 ppm or more and 80 ppm or less.

In the alloy composition in the solder alloy of this embodiment, the following formula (1) is satisfied.

20≤Ni+Fe≤700 (One)

(1) In formula, Ni and Fe respectively represent content (mass ppm) in the said alloy composition.

Both Ni and Fe in the formula (1) are elements that suppress the formation of Sn-containing intermetallic compounds at the bonding interface. In addition, in this embodiment, both Ni and Fe contribute also to the effect of the thickening suppression in time-lapse|temporality of a solder paste.

In order to obtain the effect of suppressing the formation of the Sn-containing intermetallic compound and the effect of suppressing the thickening of the solder paste over time, the total content of Ni and Fe in the solder alloy is adjusted to the total mass (100% by mass) of the solder alloy. It needs to be 20 ppm or more and 700 ppm or less. The total content of Ni and Fe is preferably 40 ppm or more and 700 ppm or less, more preferably 40 ppm or more and 600 ppm or less, and most preferably 40 ppm or more and 200 ppm or less.

However, the "total content of Ni and Fe" is the content of Fe when the content of Ni in the solder alloy is 0 ppm, and becomes the content of Ni when the content of Fe in the solder alloy is 0 ppm, and Ni and Fe It becomes the total content of these in the case of co-occurring.

In addition, when Ni and Fe are used together in this embodiment, the ratio of Ni and Fe in the solder alloy is a mass ratio expressed by Ni/Fe, preferably 0.4 or more and 30 or less, more preferably 0.4 or more and 10 or less, more preferably 0.4 or more and 5 or less, and particularly preferably 0.4 or more and 2 or less.

If Ni/Fe of such a mass ratio is the said preferable range, it will become easy to acquire the effect of this invention.

≪Random Elements≫

The alloy composition in the solder alloy of this embodiment may contain elements other than the above-mentioned elements as needed.

For example, the alloy composition in the solder alloy of the present embodiment includes, in addition to the elements described above, at least one of Ag: 0 mass% or more and 4 mass% or less and Cu: 0 mass% or more and 0.9 mass% or less. You may contain more.

Ag: 0 mass % or more and 4 mass % or less

Ag is an optional element capable of improving the reliability of the solder alloy by forming Ag ₃ Sn at the crystal interface. Moreover, Ag is an element rare with respect to Sn in an ionization tendency, and by coexisting with Ni and Fe, the thickening inhibitory effect in time-lapse|temporality of a solder paste is improved. In addition, when the content of Ag in the solder alloy is within the above range, the increase in the melting point of the alloy can be suppressed, so that it is not necessary to excessively increase the reflow temperature.

In the present embodiment, the content of Ag in the solder alloy is preferably 0% or more and 4% or less with respect to the total mass (100% by mass) of the solder alloy, more preferably more than 0% and 4% or less, still more preferably Preferably it is 0.5 % or more and 3.5 % or less, Especially preferably, it is 1.0 % or more and 3.0 % or less, Most preferably, it is 2.0 % or more and 3.0 % or less.

Cu: 0 mass % or more and 0.9 mass % or less

Cu is used in general solder alloys and is an optional element capable of improving the joint strength of solder joints. Moreover, Cu is an element whose ionization tendency is noble with respect to Sn, and by coexisting with Ni and Fe, the thickening inhibitory effect in time-lapse|temporality of a solder paste is improved.

In the present embodiment, the content of Cu in the solder alloy is preferably 0% or more and 0.9% or less with respect to the total mass (100% by mass) of the solder alloy, more preferably more than 0% and 0.9% or less, still more preferably Preferably, it is 0.1 % or more and 0.8 % or less, Especially preferably, it is 0.2 % or more and 0.7 % or less.

In the case of using Cu and Ni together in the present embodiment, the ratio of Cu and Ni in the solder alloy is a mass ratio expressed by Cu/Ni, preferably 8 or more and 175 or less, and more preferably 10 or more and 150 or less. .

If Cu/Ni of such mass ratio is the said preferable range, it will become easy to acquire the effect of this invention.

When Cu and Fe are used together in the present embodiment, the ratio of Cu and Fe in the solder alloy is a mass ratio expressed by Cu/Fe, preferably 50 or more and 350 or less, and more preferably 70 or more and 250 or less. .

If Cu/Fe of such a mass ratio is the said preferable range, it will become easy to acquire the effect of this invention.

When Cu, Ni, and Fe are used together in the present embodiment, the ratio of Cu, Ni, and Fe in the solder alloy is a mass ratio expressed by Cu/(Ni+Fe), preferably 7 or more and 350 or less, and more Preferably it is 10 or more and 250 or less.

If Cu/(Ni+Fe) of this mass ratio is the said preferable range, the effect of this invention will become easier to acquire.

As one embodiment of the solder alloy, U: less than 5 mass ppb, Th: less than 5 mass ppb, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Ni: 0 mass ppm or more and 600 mass ppm or less, and Fe: It has an alloy composition which exceeds 0 mass ppm and 100 mass ppm or less, and the remainder consists of Sn, the said formula (1) is satisfy|filled, and the alpha radiation amount may be 0.02 cph/cm<2> or less.

The alloy composition in this solder alloy may further contain at least 1 sort(s) of Ag: 0 mass % or more and 4 mass % or less, and Cu: 0 mass % or more and 0.9 mass % or less.

Further, as one embodiment of the solder alloy, U: less than 5 mass ppm, Th: less than 5 mass ppb, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Ni: more than 0 mass ppm and 600 mass ppm or less, and Fe: more than 0 mass ppm and 100 mass ppm or less, Ag: more than 0 mass % 4 mass % or less, Cu: at least one of more than 0 mass % and 0.9 mass % or less, and the balance having an alloy composition consisting of Sn, 1) Expression may be satisfied, and the α dose may be 0.02 cph/cm 2 or less. As for the alloy composition in this solder alloy, the ratio of Ni and Fe may be a mass ratio represented by Ni/Fe, and 0.4 or more and 30 or less may be sufficient.

Further, as one embodiment of the solder alloy, U: less than 5 mass ppm, Th: less than 5 mass ppb, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Ni: more than 0 mass ppm and 600 mass ppm or less, and Fe: 0 mass ppm or more and 100 mass ppm or less, Cu: more than 0 mass % and 0.9 mass % or less, and the balance has an alloy composition composed of Sn, the above formula (1) is satisfied, and the ratio of Cu and Ni is Cu As a mass ratio expressed by /Ni, it may be 8 or more and 175 or less, and the α-ray dose may be 0.02 cph/cm 2 or less. As for the alloy composition in this solder alloy, the ratio of Ni and Fe may be a mass ratio represented by Ni/Fe, and 0.4 or more and 30 or less may be sufficient. In addition, the said alloy composition may contain Ag: more than 0 mass % and 4 mass % or less.

Further, as one embodiment of the solder alloy, U: less than 5 mass ppb, Th: less than 5 mass ppm, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Ni: 0 mass ppm or more and 600 mass ppm or less, and Fe: 0 mass ppm or more and 100 mass ppm or less, Cu: has an alloy composition consisting of more than 0 mass % and 0.9 mass % or less, and the balance is Sn, the above formula (1) is satisfied, and the ratio of Cu, Ni and Fe is , Cu/(Ni+Fe) as a mass ratio expressed by 7 or more and 350 or less, and the α dose may be 0.02 cph/cm 2 or less. As for the alloy composition in this solder alloy, the ratio of Ni and Fe may be a mass ratio represented by Ni/Fe, and 0.4 or more and 30 or less may be sufficient. In addition, the said alloy composition may contain Ag: more than 0 mass % and 4 mass % or less.

Further, as one embodiment of the solder alloy, U: less than 5 mass ppb, Th: less than 5 mass ppm, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Ni: 0 mass ppm or more and 600 mass ppm or less, and Fe: more than 0 mass ppm and 100 mass ppm or less, Cu: more than 0 mass % and 0.9 mass % or less, and an alloy composition in which the balance consists of Sn, the above formula (1) is satisfied, and the ratio of Cu and Fe is Cu The mass ratio expressed by /Fe may be 50 or more and 350 or less, and the α dose may be 0.02 cph/cm 2 or less. As for the alloy composition in this solder alloy, the ratio of Ni and Fe may be a mass ratio represented by Ni/Fe, and 0.4 or more and 30 or less may be sufficient. In addition, the said alloy composition may contain Ag: more than 0 mass % and 4 mass % or less.

For example, the alloy composition in the solder alloy of the present embodiment includes, in addition to the elements described above, at least one of Bi: 0 mass% or more and 0.3 mass% or less and Sb: 0 mass% or more and 0.9 mass% or less. You may contain more.

Bi: 0 mass% or more and 0.3 mass% or less

Bi has a low reactivity with the flux and is an element showing the effect of suppressing the thickening of the solder paste over time. In addition, Bi is an element capable of suppressing deterioration of wettability because it lowers the liquidus temperature of the solder alloy and reduces the viscosity of the molten solder.

In the present embodiment, the content of Bi in the solder alloy is preferably 0% or more and 0.3% or less, more preferably 0.0020% or more and 0.3% or less, and still more preferably, with respect to the total mass (100% by mass) of the solder alloy. Preferably, it is 0.010% or more and 0.3% or less.

Sb: 0 mass% or more and 0.9 mass% or less

Like Bi, Sb has low reactivity with a flux, and is an element showing the effect of suppressing the thickening of the solder paste over time. When there is too much content of Sb in a solder alloy, since wettability deteriorates, when adding Sb, it is necessary to set it as an appropriate content.

In the present embodiment, the content of Sb in the solder alloy is preferably 0% or more and 0.9% or less, more preferably 0.0020% or more and 0.9% or less, still more preferably with respect to the total mass (100 mass%) of the solder alloy. It is preferably 0.010% or more and 0.9% or less.

When the alloy composition in the solder alloy of the present embodiment further contains at least one of Bi: 0 mass% or more and 0.3 mass% or less and Sb: 0 mass% or more and 0.9 mass% or less, the alloy composition is It is desirable to satisfy the expression (2).

0.03≤Bi+Sb≤1.2 (2)

(2) In formula, Bi and Sb respectively represent content (mass %) in the said alloy composition.

Both Bi and Sb in the formula (2) are elements showing the thickening inhibitory effect over time of the solder paste. In addition, in the present embodiment, both Bi and Sb also contribute to the wettability of the solder alloy.

The total content of Bi and Sb in the solder alloy is preferably 0.03% or more and 1.2% or less, more preferably 0.03% or more and 0.9% or less, still more preferably 0.3 with respect to the total mass (100% by mass) of the solder alloy. % or more and 0.9% or less.

However, the above "total content of Bi and Sb" becomes the content of Sb when the content of Bi in the solder alloy is 0%, and becomes the content of Bi when the content of Sb in the solder alloy is 0%, and Bi In the case of co-occurring with Sb, it becomes the total content of these.

When Bi and Sb are used together in the present embodiment, the ratio of Bi and Sb in the solder alloy is a mass ratio expressed by Sb/Bi, preferably 0.01 or more and 10 or less, and more preferably 0.1 or more and 5 or less. .

If Sb/Bi of such a mass ratio is the said preferable range, the effect of this invention will become easier to acquire.

≪Balance: Sn≫

The balance of the alloy composition in the solder alloy of this embodiment consists of Sn. In addition to the above elements, unavoidable impurities may be contained. Even when unavoidable impurities are contained, the above-described effects are not affected.

<α dose>

The solder alloy of the present embodiment has an α dose of 0.02 cph/cm 2 or less.

This is an α dose to the extent that soft errors do not become a problem in high-density packaging of electronic components.

The α dose in the solder alloy of the present embodiment is preferably 0.01 cph/cm 2 or less, more preferably 0.002 cph/cm 2 or less, and still more preferably from the viewpoint of suppressing soft errors in further high-density packaging. 0.001 cph/cm 2 or less.

The α dose generated from the solder alloy can be measured as follows. This α-dose measurement method is based on the international standard JEDEC STANDARD.

Procedure (i):

A gas flow type α dose measuring device is used.

As a measurement sample, a solder alloy sheet formed by melting a solder alloy and forming a sheet having an area of 900 cm 2 on one side is used.

In the α dose measuring apparatus, the solder alloy sheet is provided as a measurement sample, and PR gas is purged thereto.

In addition, for PR gas, what complies with the international standard JEDEC STANDARD is used. That is, the PR gas used for the measurement assumes that radon (Rn) has decayed for 3 weeks or more after filling the gas cylinder with a mixed gas of 90% argon and 10% methane.

Procedure (ii):

After allowing the PR gas to flow for 12 hours in the α-dose measuring apparatus provided with the solder alloy sheet, the α-dose measurement is performed for 72 hours.

Step (iii):

The average α dose is calculated as “cph/cm 2 ”. An outlier (such as a count due to device vibration) removes the one-hour count.

[Method for producing solder alloy]

The solder alloy of this embodiment can be manufactured by using the manufacturing method which has a process of melt-mixing, for example, at least 1 sort(s) of Ni and Fe, and the raw material metal containing Sn.

In view of the purpose of designing a low-α-dose solder alloy, it is preferable to use a low-α-dose material as the raw material metal. For example, Sn, Ni, and Fe as the raw material metal are each of high purity; and It is preferable to use what has removed U, Th and Pb.

As Sn as a raw material metal, what was manufactured according to the manufacturing method of Unexamined-Japanese-Patent No. 2010-156052 (patent document 1) can be used, for example.

As Ni and Fe as raw material metals, the thing manufactured according to Unexamined-Japanese-Patent No. 5692467, respectively can be used, respectively.

A conventionally well-known method can be used for operation of melt-mixing a raw material metal.

In general, in a solder alloy, each constituent element constituting the solder alloy does not function independently, and various effects can be exhibited only when the content of each constituent element is within a predetermined range. According to the solder alloy of the embodiment described above, when the content of each constituent element is within the above-mentioned range, it is possible to suppress an increase in the viscosity of the solder paste over time, it is difficult to cause a short circuit in the circuit, and it is possible to increase the mechanical strength of the solder joint. Also, it is possible to suppress the occurrence of soft errors. That is, the solder alloy of the present embodiment is useful as a target low α-dose material, and by applying it to the formation of solder bumps around the memory, it is possible to suppress the occurrence of soft errors.

In this embodiment, in addition to the content of each constituent element being within the above-mentioned range, it is also involved in suppression of Fe corrosion, suppression of thickening over time of the solder paste, improvement of the mechanical strength of the solder joint, and suppression of short circuit of the circuit. When Fe and Ni satisfy a predetermined relationship, the effect of the present invention can be more fully exhibited.

Further, in the present embodiment, an object of the present embodiment is to design a low α-dose solder alloy capable of suppressing the thickening of the solder paste over time without actively adding As. In contrast, the present object is achieved by employing a solder alloy containing Ni and Fe, which are high-melting-point metals heated at high temperatures during refining or processing, in specific proportions.

Although the reason such an effect is acquired is not clear, it is estimated as follows.

Sn for a low α-dose solder alloy is very high in purity, and when the molten alloy is solidified, the crystal size of Sn increases. In addition, the oxide film in Sn also forms a reduced oxide film in connection therewith. Therefore, by adding Ni and Fe, which are refractory metals, the crystal size is reduced, and by forming a dense oxide film, the reactivity between the alloy and the flux is suppressed, so that it is possible to suppress the thickening of the solder paste over time. do.

Incidentally, in the solder alloy of this embodiment, the α dose after heat treatment at 100° C. for 1 hour with respect to the solder alloy sheet formed into a sheet having an area of 900 cm 2 on one side is 0.02 cph/ It is preferably set to cm 2 or less, more preferably 0.01 cph/cm 2 or less, still more preferably 0.002 cph/cm 2 or less, and particularly preferably 0.001 cph/cm 2 or less.

A solder alloy exhibiting such an α dose is useful because segregation of ²¹⁰ Po is unlikely to occur in the alloy, and the influence of the α dose with time change is small. By applying a solder alloy exhibiting such an α dose, the occurrence of soft errors is further suppressed, and stable operation of the semiconductor element is further easily ensured.

(solder powder)

The solder powder according to one aspect of the present invention is made of the solder alloy according to one aspect of the present invention.

The solder powder of this embodiment is suitable for use with the solder paste mentioned later.

For the production of solder powder, known methods such as a dropping method in which particles are obtained by dropping a molten solder alloy dropwise, a centrifugal spraying method, atomization method, submerged granulation method, and a method of pulverizing a bulk solder alloy can be employed. have. It is preferable to perform dripping or spraying in the dripping method or the spraying method in an inert atmosphere or a solvent in order to set it as a particulate form.

It is preferable that the solder powder of this embodiment is a spherical powder. By being a spherical powder, the fluidity|liquidity of a solder alloy improves.

When the solder powder of this embodiment is a spherical powder, it is preferable that symbols 1 to 8 are satisfied, and symbols 4 to 8 are specified in the classification (Table 2) of the powder size according to JIS Z 3284-1:2014. It is more preferable to be satisfied. When the particle size of the solder powder satisfies this condition, the surface area of the powder is not too large, the increase in the viscosity of the solder paste over time is suppressed, and the aggregation of the fine powder is suppressed, and the increase in the viscosity of the solder paste is suppressed. There are cases. For this reason, it becomes possible to solder to a finer component.

In addition, it is preferable that the solder powder of this embodiment shares two or more types of solder alloy particle groups from which particle size distribution differs. Thereby, the slidability of a solder paste becomes high and workability|operativity, such as becoming easy to print, improves.

In the solder powder of the present embodiment, the sphericity of the spherical powder is preferably 0.8 or more, more preferably 0.9 or more, still more preferably 0.95 or more, and particularly preferably 0.99 or more.

The "sphericity of the spherical powder" referred to herein can be measured using a CNC image measurement system (ULT RA QV350-PRO measuring device manufactured by Mitsutoyo Co., Ltd.) using the minimum area center method (MZC method).

Sphericity indicates deviation from a true sphere, and is, for example, an arithmetic average value calculated when the diameter of each of 500 solder alloy particles is divided by the major axis.

(solder paste)

A solder paste according to an aspect of the present invention contains the solder powder according to an aspect of the present invention and a flux.

<Flux>

The flux used in the solder paste of the present embodiment is composed of, for example, any one of a resin component, an active component, a solvent, and other components, or a combination of two or more of these components.

As a resin component, rosin-type resin is mentioned, for example.

Examples of the rosin-based resin include raw material rosin such as gum rosin, wood rosin and tall oil rosin, and derivatives obtained from the raw material rosin.

Examples of the derivative include purified rosin, hydrogenated rosin, disproportionated rosin, polymerized rosin and α, β unsaturated carboxylic acid-modified products (acrylated rosin, maleinized rosin, fumarated rosin, etc.), and purification of the polymerized rosin water, a hydride and a disproportionated product, and a purified product, a hydride and a disproportionated product of the α, β unsaturated carboxylic acid modified product, and the like, and two or more types can be used.

As the resin component, in addition to the rosin resin, terpene resin, modified terpene resin, terpene phenol resin, modified terpene phenol resin, styrene resin, modified styrene resin, xylene resin, modified xylene resin, acrylic resin, polyethylene resin, acrylic-polyethylene A copolymer resin, an epoxy resin, etc. are mentioned.

As modified terpene resin, aromatic modified terpene resin, hydrogenated terpene resin, hydrogenated aromatic modified terpene resin, etc. are mentioned. Hydrogenated terpene phenol resin etc. are mentioned as modified terpene phenol resin. As modified styrene resin, a styrene acrylic resin, styrene maleic acid resin, etc. are mentioned. Examples of the modified xylene resin include phenol-modified xylene resin, alkylphenol-modified xylene resin, phenol-modified resol-type xylene resin, polyol-modified xylene resin, and polyoxyethylene-added xylene resin.

Examples of the active ingredient include organic acids, amines, halogen-based activators, thixotropic agents, solvents, and metal deactivators.

Examples of the organic acid include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dimer acid, propionic acid, 2,2-bishydroxymethylpropionic acid, tartaric acid, malic acid, glycolic acid , diglycolic acid, thioglycolic acid, dithioglycolic acid, stearic acid, 12-hydroxystearic acid, palmitic acid, oleic acid, and the like.

Examples of the amine include ethylamine, triethylamine, ethylenediamine, triethylenetetramine, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, and 1,2-dimethyl. Midazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenyl Imidazole, 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'-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-triazineisocyanuric acid adduct, 2-phenylimidazoleisocyanuric acid adduct, 2-phenyl-4,5- Dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dode Syl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline, 2,4-diamino-6-vinyl-s-triazine, 2,4-diamino -6-vinyl-s-triazineisocyanuric 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, 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-benzo Triazolyl)-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-(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, 5-phenyltetra sol etc. are mentioned.

As a halogen-type activator, an amine hydrohalide, an organic halogen compound, etc. are mentioned, for example.

An amine hydrohalide is a compound in which an amine and a hydrogen halide are reacted. Examples of the amine here include ethylamine, ethylenediamine, triethylamine, diphenylguanidine, ditolylguanidine, methylimidazole, 2-ethyl-4-methylimidazole, and the like, and examples of the hydrogen halide include , for example, a hydride of chlorine, bromine, or iodine.

Examples of the organic halogen compound include trans-2,3-dibromo-2-butene-1,4-diol, triallyl isocyanurate 6 bromide, 1-bromo-2-butanol, and 1-bromide. Mo-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-2-butene-1,4-diol, and the like.

As a thixo agent, a wax-type thixo agent, an amide-type thixo agent, a sorbitol-type thixo agent etc. are mentioned, for example.

As a wax-type thixo agent, castor hardened oil etc. are mentioned, for example.

Examples of the amide-based thixotropic agent include monoamide-based thixotropic agents, bisamide-based thixologic agents, and polyamide-based thixologic agents, and specifically, lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydride. Roxy stearic acid amide, saturated fatty acid amide, oleic acid amide, erucic acid amide, unsaturated fatty acid amide, p-toluene methanamide, aromatic amide, methylene bis stearic acid amide, ethylene bis lauric acid amide, ethylene bis hydroxy stearic acid amide , saturated fatty acid bisamide, methylenebisoleic acid amide, unsaturated fatty acid bisamide, m-xylylenebisstearic acid amide, aromatic bisamide, saturated fatty acid polyamide, unsaturated fatty acid polyamide, aromatic polyamide, substituted amide, methylolstear Acid amide, methylol amide, fatty acid ester amide, etc. are mentioned.

Examples of the sorbitol-based thixotropic agent include dibenzylidene-D-sorbitol, bis(4-methylbenzylidene)-D-sorbitol, and the like.

Examples of the solvent include water, an alcohol solvent, a glycol ether solvent, and terpineols.

Examples of the alcohol-based solvent include isopropyl alcohol, 1,2-butanediol, isobornylcyclohexanol, 2,4-diethyl-1,5-pentanediol, and 2,2-dimethyl-1,3-propane. Diol, 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-ethynyl- 1-Cyclohexanol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, erythritol, threitol, guaiachol 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 the glycol ether solvent include diethylene glycol mono-2-ethylhexyl ether, ethylene glycol monophenyl ether, 2-methylpentane-2,4-diol, diethylene glycol monohexyl ether, and diethylene glycol dibutyl ether. and triethylene glycol monobutyl ether.

As a metal deactivator, a hindered phenol type compound, a nitrogen compound, etc. are mentioned, for example. When the flux contains either a hindered phenolic compound or a nitrogen compound, the thickening inhibitory effect of the solder paste is easily enhanced.

The term "metal deactivator" as used herein refers to a compound having the ability to prevent deterioration of a metal by contact with a certain type of compound.

The hindered phenol-based compound refers to a phenol-based compound having a bulky substituent (eg, a branched or cyclic alkyl group such as a t-butyl group) at at least one of the ortho positions of the phenol.

It does not specifically limit as a hindered phenol type compound, 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), triethyleneglycol-bis[3-(3-tert-butyl-5-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-hydrocinnamamide), 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, N,N'-bis[2-[2-(3,5-di-tert-butyl-4-hydroxyphenyl)ethylcarbonyloxy]ethyl]oxamide, represented by the formula compounds used as such can be mentioned.

(Wherein, Z is an optionally substituted alkylene group. R ¹ and R ² are each independently an optionally substituted alkyl group, aralkyl group, aryl group, heteroaryl group, cycloalkyl group or heterocycloalkyl group. R ³ and R ⁴ is each independently an optionally substituted alkyl group.)

As a nitrogen compound in a metal deactivator, a hydrazide type nitrogen compound, an amide type nitrogen compound, a triazole type nitrogen compound, a melamine type nitrogen compound, etc. are mentioned, for example.

As the hydrazide-based nitrogen compound, any nitrogen compound having a hydrazide skeleton may be used, and dodecanedioic acid bis[N2-(2-hydroxybenzoyl)hydrazide], 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-ami Nophthalhydrazide, phthalic acid dihydrazide, adipic acid hydrazide, oxalobis(2-hydroxy-5-octylbenzylidenehydrazide), N'-benzoylpyrrolidonecarboxylic acid hydrazide, N, N'-bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hydrazine etc. are mentioned.

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

The triazole-based nitrogen compound may be a nitrogen compound having a triazole skeleton, such as N-(2H-1,2,4-triazol-5-yl)salicylamide, 3-amino-1,2,4-triazole , 3-(N-salicilyl)amino-1,2,4-triazole and the like.

As a melamine-type nitrogen compound, what is necessary is just a nitrogen compound which has a melamine skeleton, melamine, a melamine derivative, etc. are mentioned. More specifically, for example, trisaminotriazine, alkylated trisaminotriazine, alkoxyalkylated trisaminotriazine, melamine, alkylated melamine, alkoxyalkylated melamine, N2-butylmelamine, N2,N2-diethylmelamine, N, N,N',N',N",N"-hexakis(methoxymethyl)melamine etc. are mentioned.

As other components, surfactant, a silane coupling agent, antioxidant, a coloring agent, etc. are mentioned, for example.

Nonionic surfactants, weak cationic surfactants, etc. are mentioned as surfactant.

Examples of the nonionic surfactant include polyethylene glycol, polyethylene glycol-polypropylene glycol copolymer, aliphatic alcohol polyoxyethylene adduct, aromatic alcohol polyoxyethylene adduct, and polyhydric alcohol polyoxyethylene adduct.

Examples of the weak cationic surfactant include terminal diamine polyethylene glycol, terminal diamine polyethylene glycol-polypropylene glycol copolymer, aliphatic amine polyoxyethylene adduct, aromatic amine polyoxyethylene adduct, and polyvalent amine polyoxyethylene adduct. can be heard

As the surfactant other than the above, for example, polyoxyalkylene acetylene glycols, polyoxyalkylene glyceryl ether, polyoxyalkylene alkyl ether, polyoxyalkylene ester, polyoxyalkylene alkylamine, polyoxyalkylene Alkylamide etc. are mentioned.

It is preferable that content of the flux in the solder paste of this embodiment is 5-95 mass % with respect to the total mass (100 mass %) of a solder paste, It is more preferable that it is 5-50 mass %, It is 5-15 mass % It is more preferable that

When the content of the flux is within this range, the thickening inhibitory effect due to the solder powder is sufficiently exhibited.

The solder paste of this embodiment can be manufactured by the manufacturing method common in the art.

A solder paste can be obtained by heating and mixing the components constituting the flux to prepare a flux, and stirring and mixing the solder powder in the flux. Moreover, in anticipation of the thickening suppression effect over time, you may mix|blend further zirconium oxide powder separately from the said solder powder.

(solder ball)

The solder ball according to one aspect of the present invention is made of the solder alloy according to the first aspect of the present invention.

The solder alloy of the above-described embodiment can be used as a solder ball.

The solder ball of this embodiment can be manufactured by using the dripping method which is a general method in the art.

1 micrometer or more is preferable, as for the particle diameter of a solder ball, 10 micrometers or more are more preferable, 20 micrometers or more are still more preferable, and 30 micrometers or more are especially preferable. On the other hand, as for the particle diameter of a solder ball, 3000 micrometers or less are preferable, 1000 micrometers or less are more preferable, 600 micrometers or less are still more preferable, and 300 micrometers or less are especially preferable.

The particle size of the solder ball is, for example, preferably 1 µm or more and 3000 µm or less, more preferably 10 µm or more and 1000 µm or less, still more preferably 20 µm or more and 600 µm or less, and 30 µm or more and 300 µm or less. Especially preferred.

(Solder Preform)

A solder preform according to an aspect of the present invention is made of the solder alloy according to an aspect of the present invention.

The solder alloy of the above-described embodiment can be used as a preform.

As a shape of the preform of this embodiment, a washer, a ring, a pellet, a disk, a ribbon, a wire, etc. are mentioned.

(solder joint)

The solder joint according to one aspect of the present invention is made of the solder alloy according to one aspect of the present invention.

The solder joint of this embodiment is comprised by an electrode and a solder joint part. The solder joint portion refers to a portion mainly formed of a solder alloy.

The solder joint of the present embodiment can be formed by, for example, joining an electrode of a PKG (package) such as an IC chip and an electrode of a substrate such as a printed circuit board (PCB) with the solder alloy of the above-described embodiment. have.

In addition, the solder joint of this embodiment can be manufactured by processing by a general method in the art, such as mounting and bonding one solder ball of the above-mentioned embodiment on one electrode to which the flux was applied.

Example

Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited by these examples.

In the present Example, unless otherwise specified, "ppb" for the solder alloy composition is "mass ppb", "ppm" is "mass ppm", and "%" is "mass %".

<Solder alloy>

(Examples 1 to 370, Comparative Examples 1 to 8)

The raw metal was melted and stirred to prepare solder alloys of each example each having the alloy compositions shown in Tables 1A to 16B.

<Solder Powder>

The solder alloys of each example are melted, and the solder alloys of each example each having the alloy compositions shown in Tables 1A to 16B are made by the atomization method, and the powder size is classified according to JIS Z 3284-1:2014 (Table 2). ), solder powder having a size (particle size distribution) satisfying symbol 4 was produced.

<Preparation of flux (F0)>

A rosin-based resin was used as the resin component.

As active ingredients, thixotropic agents, organic acids, amines and halogen-based activators were used.

A glycol ether-based solvent was used as the solvent.

A flux (F0) was prepared by mixing 42 parts by mass of rosin, 35 parts by mass of a glycol ether solvent, 8 parts by mass of a thixotropic agent, 10 parts by mass of an organic acid, 2 parts by mass of an amine, and 3 parts by mass of a halogen-based active agent.

<Production of Solder Paste>

A solder paste was prepared by mixing the flux F0 with the solder powder of each of the solder alloys having the alloy compositions shown in Tables 1A to 16B, respectively.

The mass ratio of the flux (F0) to the solder powder was set to flux (F0):solder powder = 11:89.

<Evaluation>

Evaluation of thickening suppression was performed using the said solder paste.

Moreover, evaluation of the precipitation suppression of needle-shaped crystal|crystallization, evaluation of formation suppression of Sn containing intermetallic compound, and evaluation of alpha radiation were respectively performed using the said solder alloy. Moreover, comprehensive evaluation was performed.

The details are as follows. The evaluation results are shown in Tables 1A to 16B.

[Thickening suppression]

(1) Verification method

About the solder paste immediately after preparation, using the Malcom Corporation make: PCU-205, rotation speed: 10rpm, 25 degreeC, the viscosity was measured in air for 12 hours.

(2) Judgment criteria

(circle): The viscosity after 12 hours is 1.2 times or less compared with the viscosity when 30 minutes pass from immediately after solder paste preparation.

x: The viscosity after 12 hours exceeds 1.2 times compared with the viscosity when 30 minutes pass from immediately after solder paste preparation.

If this determination is "(circle)", it can be said that sufficient thickening inhibitory effect was acquired. That is, an increase in the viscosity of the solder paste over time can be suppressed.

[Precipitation suppression of needle crystals]

(1) Verification method

The solder alloy of each example was melted at 250°C and cooled to 100°C, which is the solidus temperature of the entire alloy composition or less, for 10 minutes. With respect to the cooled solder alloy, cross-section observations were made at arbitrary five locations within the range of 300 µm × 300 µm using a scanning electron microscope (SEM), and the needle-shaped crystals derived from the SnFe compound in the cross-sectional SEM photograph. The presence or absence of was confirmed.

The needle-like crystal in this example means a crystal having an aspect ratio of 2 or more, which is a ratio of a major axis to a minor axis, in a crystal derived from one SnFe compound.

(2) Judgment criteria

(circle): Acicular crystal|crystallization was not observed in all the SEM observation images of 5 places.

x: Acicular crystals were observed on at least one SEM observation image.

If this determination is "circle", it can be said that it has the precipitation inhibitory effect of needle-shaped crystal|crystallization. That is, it can be made difficult to generate|occur|produce a short circuit of a circuit.

[Inhibition of formation of Sn-containing intermetallic compounds]

(1) Verification method

The solder alloy of each example was melted at 250°C and cooled to 100°C, which is the solidus temperature of the entire alloy composition or less, for 10 minutes. The solder alloy after cooling was cross-sectionally observed at five arbitrary locations in the range of 300 µm × 300 µm using SEM, and the presence or absence of a Sn(Cu)Ni compound was confirmed.

(2) Judgment criteria

(circle): Sn(Cu)Ni compound was not observed in all the SEM observation images of 5 places.

x: A Sn(Cu)Ni compound was observed on at least one SEM observation image.

If this determination is "circle", it can be said that it has the effect of suppressing the formation of Sn containing intermetallic compound. That is, the mechanical strength of the solder joint can be increased.

[α dose]

(1) Verification method part 1

The α dose was measured by following the procedures (i), (ii) and (iii) described above using an α dose measuring device of a gas flow proportional counter.

As a measurement sample, the solder alloy sheet immediately after manufacture was used.

This solder alloy sheet was obtained by melting the solder alloy immediately after production and forming it into a sheet having an area of 900 cm 2 on one side.

This measurement sample was placed in an α-dose measuring device, and after allowing PR-10 gas to flow for 12 hours, it was left still, and then the α-dose was measured for 72 hours.

(2) Judgment Criteria Part 1

○○: The amount of α radiation generated from the measurement sample was 0.002 cph/cm 2 or less.

○: The amount of α radiation generated from the measurement sample was greater than 0.002 cph/cm 2 and less than or equal to 0.02 cph/cm 2 .

x: The amount of α radiation generated from the measurement sample was more than 0.02 cph/cm 2 .

If this determination is "○○" or "○", it can be said that it is a solder material with a low α dose.

(3) Verification method part 2

Except having changed the measurement sample, it carried out similarly to said (1) verification method part 1, and measured the alpha radiation dose.

As a measurement sample, a solder alloy sheet formed by melting a solder alloy immediately after production and forming a sheet having an area of 900 cm 2 on one side was subjected to heat treatment at 100° C. for 1 hour and allowed to cool.

(4) Judgment standard part 2

○○: The amount of α radiation generated from the measurement sample was 0.002 cph/cm 2 or less.

○: The amount of α radiation generated from the measurement sample was greater than 0.002 cph/cm 2 and less than or equal to 0.02 cph/cm 2 .

x: The amount of α radiation generated from the measurement sample was more than 0.02 cph/cm 2 .

If this determination is "○○" or "○", it can be said that it is a solder material with a low α dose.

(5) Verification method part 3

After storing the solder alloy sheet of the measurement sample for which the α dose was measured in (1) Verification Method 1 above, for one year, the α dose was measured by following the above-mentioned procedures (i), (ii) and (iii) again. , the change over time of α-dose was evaluated.

(6) Judgment Criteria Part 3

○○: The amount of α radiation generated from the measurement sample was 0.002 cph/cm 2 or less.

○: The amount of α radiation generated from the measurement sample was greater than 0.002 cph/cm 2 and less than or equal to 0.02 cph/cm 2 .

x: The amount of α radiation generated from the measurement sample was more than 0.02 cph/cm 2 .

If this determination is "○○" or "○", it can be said that the amount of α radiation generated does not change with time and is stable. That is, generation|occurrence|production of the soft error in electronic devices can be suppressed.

[Comprehensive evaluation]

○: In Tables 1A to 16B, each evaluation of thickening suppression, needle-like crystal precipitation suppression, Sn-containing intermetallic compound formation suppression, α dose immediately after production, α dose after heat treatment, and change over time of α dose, All were "○○" or "○".

×: In Tables 1A to 16B, during each evaluation of thickening suppression, needle-like crystal precipitation suppression, Sn-containing intermetallic compound formation suppression, α dose immediately after production, α dose after heat treatment, and change over time of α dose, At least one was ×.

[Table 1A]

[Table 1B]

[Table 2A]

[Table 2B]

[Table 3A]

[Table 3B]

[Table 4A]

[Table 4B]

[Table 5A]

[Table 5B]

[Table 6A]

[Table 6B]

[Table 7A]

[Table 7B]

[Table 8A]

[Table 8B]

[Table 9A]

[Table 9B]

[Table 10A]

[Table 10B]

[Table 11A]

[Table 11B]

[Table 12A]

[Table 12B]

[Table 13A]

[Table 13B]

[Table 14A]

[Table 14B]

[Table 15A]

[Table 15B]

[Table 16A]

[Table 16B]

As shown in Tables 1A to 16B, when the solder alloys of Examples 1 to 370 to which the present invention is applied are used, in any case, the increase in the viscosity of the solder paste over time is suppressed, and it is difficult to cause a short circuit in the circuit. , it was confirmed that it is possible to increase the mechanical strength of the solder joint and to suppress the occurrence of soft errors.

On the other hand, when the solder alloys of Comparative Examples 1 to 8 outside the scope of the present invention were used, in any case, at least one of thickening suppression, needle crystal precipitation suppression, Sn-containing intermetallic compound formation suppression, and α dose evaluation. showed a falling result.

Claims (23)

U: less than 5 mass ppb, Th: less than 5 mass ppm, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Ni: 0 mass ppm or more and 600 mass ppm or less, and Fe: 0 mass ppm or more and 100 mass ppm or less , and the balance has an alloy composition consisting of Sn,
It satisfies the following formula (1), and
A solder alloy having an α dose of 0.02 cph/cm 2 or less.
20≤Ni+Fe≤700 (1)
(1) In formula, Ni and Fe respectively represent content (mass ppm) in the said alloy composition. U: less than 5 mass ppb, Th: less than 5 mass ppm, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Ni: 0 mass ppm or more and 600 mass ppm or less, and Fe: more than 0 mass ppm and 100 mass ppm or less , and the balance has an alloy composition consisting of Sn,
It satisfies the following formula (1), and
A solder alloy having an α dose of 0.02 cph/cm 2 or less.
20≤Ni+Fe≤700 (1)
(1) In formula, Ni and Fe respectively represent content (mass ppm) in the said alloy composition. The solder alloy according to claim 1 or 2, wherein the alloy composition also satisfies the following formula (1').
40≤Ni+Fe≤200 (1')
In formula (1'), Ni and Fe each represent content (mass ppm) in the said alloy composition. The solder alloy according to any one of claims 1 to 3, wherein Pb is less than 2 mass ppm. The solder alloy according to any one of claims 1 to 4, wherein As is less than 2 mass ppm by mass. The solder according to any one of claims 1 to 5, wherein the alloy composition further contains at least one of Ag: 0 mass% or more and 4 mass% or less and Cu: 0 mass% or more and 0.9 mass% or less. alloy. U: less than 5 mass ppm, Th: less than 5 mass ppm, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Ni: more than 0 mass ppm and 600 mass ppm or less, and Fe: more than 0 mass ppm and 100 mass ppm or less Wow,
Ag: more than 0 mass % 4 mass % or less and Cu: at least 1 sort(s) of more than 0 mass % and 0.9 mass % or less;
The balance is Sn
It has an alloy composition consisting of
It satisfies the following formula (1), and
A solder alloy having an α dose of 0.02 cph/cm 2 or less.
20≤Ni+Fe≤700 (1)
(1) In formula, Ni and Fe respectively represent content (mass ppm) in the said alloy composition. U: less than 5 mass ppb, Th: less than 5 mass ppm, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Ni: more than 0 mass ppm and 600 mass ppm or less, and Fe: 0 mass ppm or more and 100 mass ppm or less Wow,
Cu: more than 0 mass % and 0.9 mass % or less;
The balance is Sn
It has an alloy composition consisting of
It satisfies the following formula (1),
The ratio of Cu and Ni is a mass ratio expressed by Cu/Ni, and is 8 or more and 175 or less, and
A solder alloy having an α dose of 0.02 cph/cm 2 or less.
20≤Ni+Fe≤700 (1)
(1) In formula, Ni and Fe respectively represent content (mass ppm) in the said alloy composition. U: less than 5 mass ppb, Th: less than 5 mass ppm, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Ni: 0 mass ppm or more and 600 mass ppm or less, and Fe: 0 mass ppm or more and 100 mass ppm or less Wow,
Cu: more than 0 mass % and 0.9 mass % or less;
The balance is Sn
It has an alloy composition consisting of
It satisfies the following formula (1),
The ratio of Cu, Ni, and Fe is a mass ratio expressed by Cu/(Ni+Fe), and is 7 or more and 350 or less, and
A solder alloy having an α dose of 0.02 cph/cm 2 or less.
20≤Ni+Fe≤700 (1)
(1) In formula, Ni and Fe respectively represent content (mass ppm) in the said alloy composition. U: less than 5 mass ppb, Th: less than 5 mass ppm, Pb: less than 5 mass ppm, As: less than 5 mass ppm, Ni: 0 mass ppm or more and 600 mass ppm or less, and Fe: more than 0 mass ppm and 100 mass ppm or less Wow,
Cu: more than 0 mass % and 0.9 mass % or less;
The balance is Sn
It has an alloy composition consisting of
It satisfies the following formula (1),
The ratio of Cu and Fe is a mass ratio expressed by Cu/Fe, and is 50 or more and 350 or less, and
A solder alloy having an α dose of 0.02 cph/cm 2 or less.
20≤Ni+Fe≤700 (1)
(1) In formula, Ni and Fe respectively represent content (mass ppm) in the said alloy composition. The solder alloy according to any one of claims 7 to 10, wherein the ratio of Ni and Fe is a mass ratio expressed by Ni/Fe, and is 0.4 or more and 30 or less. The solder alloy according to any one of claims 8 to 11, wherein the alloy composition further contains more than 0 mass % Ag: 4 mass % or less. The alloy composition according to any one of claims 1 to 12, further comprising at least one of Bi: 0 mass% or more and 0.3 mass% or less and Sb: 0 mass% or more and 0.9 mass% or less, solder alloy. The solder alloy according to claim 13, wherein the alloy composition also satisfies the following formula (2).
0.03≤Bi+Sb≤1.2 (2)
(2) In formula, Bi and Sb respectively represent content (mass %) in the said alloy composition. 15. The α-ray dose according to any one of claims 1 to 14, after heat treatment at 100°C for 1 hour with respect to a solder alloy sheet molded into a sheet having an area of 900 cm 2 on one side. Solder alloy, which becomes cph/cm 2 or less. The solder alloy according to any one of claims 1 to 15, wherein the α dose is 0.002 cph/cm 2 or less. The solder alloy according to claim 16, wherein the α dose is 0.001 cph/cm 2 or less. A solder powder comprising the solder alloy according to any one of claims 1 to 17. The solder powder according to claim 18, wherein two or more types of solder alloy particle groups having different particle size distributions are shared. A solder paste comprising the solder powder according to claim 18 or 19 and a flux. A solder ball made of the solder alloy according to any one of claims 1 to 17. A solder preform comprising the solder alloy according to any one of claims 1 to 17. A solder joint comprising the solder alloy according to any one of claims 1 to 17.