CN115916453A

CN115916453A - Solder alloy, solder powder, solder paste, solder ball, preform solder, and solder joint

Info

Publication number: CN115916453A
Application number: CN202180041140.1A
Authority: CN
Inventors: 川崎浩由; 白鸟正人; 川又勇司
Original assignee: Senju Metal Industry Co Ltd
Current assignee: Senju Metal Industry Co Ltd
Priority date: 2020-04-10
Filing date: 2021-02-19
Publication date: 2023-04-04
Anticipated expiration: 2041-02-19
Also published as: JP6836091B1; TWI762200B; KR20220141914A; CN115916453B; KR102557835B1; TW202138577A; WO2021205759A1; JP2021167006A

Abstract

The invention adopts a soft solder alloy which comprises the following alloy compositions: u: less than 5 mass ppb, th: less than 5ppb by mass, pb: less than 5 mass ppm, as: less than 5 mass ppm, ni: 0-600 mass ppm inclusive, and Fe:0 to 100 mass ppm and the balance of Sn, satisfies the formula (1), and has an alpha ray content of 0.02cph/cm ² The following. In the formula (1) 20. Ltoreq. Ni + Fe. Ltoreq.700 (1), ni and Fe represent the contents (mass ppm) in the alloy composition. According to the solder alloy of the present invention, the solder paste can be inhibited from passing throughThe viscosity increases, short circuit of the circuit is not easily generated, the mechanical strength of the soldered joint can be improved, and the occurrence of soft error can be suppressed.

Description

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

Technical Field

The invention relates to solder alloys, solder powders, solder pastes, solder balls, pre-formed solder and soldered joints.

This application is based on the priority claim of Japanese application No. 2020-070927, filed on 10.4.2020, and the contents of which are incorporated herein.

Background

Electronic components mounted on printed circuit boards are increasingly required to be smaller and have higher performance. Examples of the electronic component include a semiconductor package. In the semiconductor package, a semiconductor element having an electrode is sealed with a resin composition. A solder bump made of a solder material is formed on the electrode. In addition, a solder material connects the semiconductor element and the printed circuit board.

In the solder material, the influence of the alpha ray on the soft error becomes a problem. In order to reduce such adverse effects on the operation of semiconductor elements, development of low α -ray materials including solder materials has been carried out.

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

In contrast, it is technically not difficult to remove U, th, and Po in refining Sn base metals (see, for example, patent document 1).

In general, sn contains lead (Pb) and bismuth (Bi) as impurities. Radioactive isotopes of Pb and Bi ²¹⁰ Pb and ²¹⁰ bi undergoes beta decay to ²¹⁰ Po， ²¹⁰ Alpha decay of Po to generate ²⁰⁶ Pb generates α rays. This series of decays (uranium series) is believed to be the main cause of alpha ray generation from the solder material.

In the evaluation of the amount of alpha rays generated from a material, "cph/cm" is often used as a unit ² ”。“cph/cm ² "is" counts per hours/cm ² "abbreviation of" means every 1cm ² Middle, count of alpha rays every 1 hour.

Regarding the half-life of Pb and Bi, the following is described.

With respect to the Bi component, the compound, ²¹⁰ the half-life of Bi is about 5 days. With respect to Pb, ²¹⁰ the half-life of Pb is about 22.3 years. Further, it is said that the influence (presence ratio) of these compounds can be expressed by the following formula (see non-patent document 1). That is, the influence of Bi on α -ray generation is very low compared to Pb.

[ ²¹⁰ Bi]≒[ ²¹⁰ Pb]/1.6×10 ³

In the formula (2) ²¹⁰ Bi]Represent ²¹⁰ Molar concentration of Bi. [ ²¹⁰ Pb]Represent ²¹⁰ Molar concentration of Pb.

As described above, in the design of a low α -dose material, conventionally, U and Th are usually removed to completely remove Pb.

In addition, it is known that the amount of α rays generated from the solder material substantially increases due to a change with time. This is said to be caused by beta decay of radioactive Pb and radioactive Bi in the solder alloy, increase of Po amount, and then alpha decay of Po to generate alpha rays.

These radioactive elements are hardly contained in a material having an extremely low alpha ray content, but because of the very low alpha ray content ²¹⁰ The segregation of Po may increase the amount of α rays with time. ²¹⁰ Po originally radiates α rays, but segregates in the central portion of the solder alloy when the solder alloy solidifies, and thus the radiated α rays are shielded by the solder alloy. Furthermore, as time passes, the temperature of the molten steel, ²¹⁰ po is uniformly dispersed in the alloy and is also present when alpha rays are detectedAccordingly, the α ray amount increases with time (see non-patent document 2).

As described above, the amount of α rays generated is increased by the influence of the extremely small amount of impurities contained in the solder alloy. Therefore, in designing a material with a low α -ray dose, it is difficult to add only various elements as in the conventional method for producing a solder alloy.

For example, a method of adding arsenic (As) to a solder alloy is known for suppressing thickening of a solder paste to suppress an increase in viscosity with time (see, for example, patent document 2).

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

In flow welding, a solder bath is required. In the solder bath, the high-temperature molten solder flows for a long time. Therefore, stainless steel or the like whose main component is iron (Fe) is used as a material of the solder bath from the viewpoint of corrosion resistance. However, the inner surface of the solder bath may be eroded by Fe erosion due to long-term use.

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

Documents of the prior art

Patent literature

Patent document 1: japanese patent application laid-open No. 2010-156052

Patent document 2: japanese patent laid-open publication No. 2015-98052

Patent document 3: japanese patent laid-open No. 2008-168322

Non-patent literature

Non-patent document 1: radio active nucleic Induced Soft Errors at group Level; IEEE TRANSACTIONS ON NUCLEAR SCIENCE, DECEMBER 2009, VOL.56, NO.6, p.3437-3441

Non-patent document 2: energy Dependent Efficiency in Low Back ground Alpha Measurements and Impacts on Accurate Alpha Characterization; IEEE TRANSACTIONS NUCLEAR SCIENCE, DECEMBER 2015, VOL.62, NO.6, p.3034-3039

Disclosure of Invention

Problems to be solved by the invention

In order to suppress the thickening of the solder paste with time, for example, in a method of adding As to a solder alloy As described in patent document 2, the alloy also contains impurities by adding As. In this case, the amount of α rays generated from the solder material increases due to the presence of the radioactive element in the impurity.

Further, as in the solder alloy described in patent document 3, when a large amount of Fe is contained in a solder alloy containing Sn as a main component, needle-like crystals derived from the SnFe compound are precipitated, and there is a possibility that a short circuit occurs in a circuit.

In addition, a solder alloy mainly composed of Sn may contain a large amount of nickel (Ni) in order to improve wettability. If the Ni content is large, the SnCuNi compound precipitates in the vicinity of the joining interface of the solder alloy, and the mechanical strength of the soldered joint may decrease.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a solder alloy that can suppress an increase in viscosity of a solder paste with time, is less likely to cause a short circuit in an electric circuit, improves mechanical strength of a soldered joint, and can suppress occurrence of a soft error, a solder powder composed of the solder alloy, a solder paste containing the solder powder and a flux, and a solder ball, a solder preform, and a soldered joint composed of the solder alloy.

Means for solving the problems

The present inventors have studied for the purpose of designing a solder alloy with a low α -ray dose, which can suppress the thickening of a solder paste with time without adding As accompanied by impurities including radioactive elements. According to the research, the following findings are found: the above object can be achieved by forming an alloy composition containing Sn as a main component, and predetermined amounts of Ni having a melting point of 1455 ℃ and Fe having a melting point of 1538 ℃ which are high-melting-point metals heated at high temperatures during refining or processing of a base metal.

That is, the present invention adopts the following means to solve the above problems.

[1] A solder alloy having the following alloy composition: u: less than 5 mass ppb, th: less than 5ppb by mass, 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 to 100 mass ppm inclusive and the balance of Sn,

satisfies the following formula (1), and

alpha ray dose is 0.02cph/cm ² The following.

20≤Ni+Fe≤700 (1)

(1) In the formula, ni and Fe represent the respective contents thereof (mass ppm) in the foregoing alloy composition.

[2] A solder alloy having the following alloy composition: u: less than 5 mass ppb, th: less than 5ppb by mass, 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 0ppm by mass and not more than 100ppm by mass, and the balance being Sn,

satisfies the following formula (1), and

alpha ray dose is 0.02cph/cm ² The following.

20≤Ni+Fe≤700 (1)

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

40≤Ni+Fe≤200 (1’)

(1') in the formula, ni and Fe represent the respective contents thereof (mass ppm) in the foregoing 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] The solder alloy according to any one of [1] to [5], wherein the alloy composition further contains Ag: 0% by mass or more and 4% by mass or less and Cu: at least one of 0 mass% or more and 0.9 mass% or less.

[7] A solder alloy having the following alloy composition:

u: less than 5 mass ppb, th: less than 5ppb by mass, 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 0ppm by mass and 100ppm by mass or less;

ag: more than 0 mass% and 4 mass% or less and Cu: at least one of more than 0 mass% and 0.9 mass% or less; and is

The balance of Sn, and the balance of Sn,

satisfies the following formula (1), and

alpha ray dose is 0.02cph/cm ² The following.

20≤Ni+Fe≤700 (1)

[8] A solder alloy having the following alloy composition:

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: more than 0 mass ppm and 600 mass ppm or less, and Fe:0 to 100 mass ppm;

cu: more than 0 mass% and 0.9 mass% or less; and is

The balance of Sn, and the balance of Sn,

satisfies the following formula (1),

the ratio of Cu to Ni is 8 or more and 175 or less in terms of a mass ratio of Cu/Ni, and

the alpha ray dose is 0.02cph/cm ² The following.

20≤Ni+Fe≤700 (1)

(1) In the formula, ni and Fe represent the content (mass ppm) of each in the foregoing alloy composition.

[9] A solder alloy having the following alloy composition:

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: 0-600 mass ppm inclusive, and Fe:0 to 100 mass ppm;

cu: more than 0 mass% and 0.9 mass% or less; and is provided with

The balance of Sn, and the balance of Sn,

satisfies the following formula (1),

the ratio of Cu to Ni to Fe is 7 to 350 in terms of a mass ratio of Cu/(Ni + Fe), and

the alpha ray dose is 0.02cph/cm ² The following.

20≤Ni+Fe≤700 (1)

[10] A solder alloy having the following alloy composition:

u: less than 5 mass ppb, th: less than 5ppb by mass, pb: less than 5 mass ppm, as: less than 5 mass ppm, ni: 0-600 mass ppm inclusive, and Fe: more than 0ppm by mass and 100ppm by mass or less;

cu: more than 0 mass% and 0.9 mass% or less; and is

The balance of Sn, and the balance of Sn,

satisfies the following formula (1),

the ratio of Cu to Fe is 50 or more and 350 or less in terms of a mass ratio of Cu/Fe, and

the alpha ray dose is 0.02cph/cm ² The following.

20≤Ni+Fe≤700 (1)

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

[12] The solder alloy according to any one of [8] to [11], wherein the alloy composition further contains Ag: more than 0 mass% and not more than 4 mass%.

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

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

0.03≤Bi+Sb≤1.2 (2)

(2) In the formula, bi and Sb represent the content (mass%) of each in the foregoing alloy composition.

[15]According to [1]]～[14]The solder alloy according to any one of the above claims, wherein an area of one surface formed by molding is 900cm ² The sheet-like solder alloy sheet of (1), wherein the amount of alpha rays after the heat treatment at 100 ℃ for 1 hour is 0.02cph/cm ² The following.

[16]According to [1]]～[15]The solder alloy according to any one of the above claims, wherein the amount of alpha rays is 0.002cph/cm ² The following.

[17]According to [16 ]]The soft solder alloy has alpha ray amount of 0.001cph/cm ² The following.

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

[19] The solder powder according to item [18], which simultaneously has 2 or more solder alloy particle groups having different particle size distributions.

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

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

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, there can be provided a solder alloy which can suppress an increase in viscosity of a solder paste with time, is less likely to cause a short circuit in an electric circuit, can improve mechanical strength of a soldered joint, and can suppress occurrence of a soft error, a solder powder composed of the solder alloy, a solder paste containing the solder powder and a flux, a solder ball composed of the solder alloy, a solder preform, and a soldered joint.

Detailed Description

The present invention will be described in more detail below.

In the present specification, "ppb" relating to the composition of the solder alloy is "mass ppb" unless otherwise specified. The "ppm" is "mass ppm" unless otherwise specified. "%" is "% by mass" unless otherwise specified.

(solder alloy)

A solder alloy according to one embodiment of the present invention has the following alloy composition: 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 to 100 mass ppm and the balance of Sn, satisfies the following formula (1), and has an alpha ray content of 0.02cph/cm ² The following.

20≤Ni+Fe≤700 (1)

< composition of alloy >

The solder alloy of the present embodiment has the following alloy composition: u: less than 5 mass ppb, th: less than 5ppb by mass, 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 to 100 mass ppm and the balance of Sn, and satisfies the formula (1).

U: less than 5 mass ppb, th: less than 5ppb by mass

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

In the present embodiment, the amounts of U and Th in the solder alloy are adjusted so that the amount of alpha rays generated from the solder alloy is 0.02cph/cm ² From the following viewpoints, the content of each is less than 5ppb based on the total mass (100 mass%) of the solder alloy. From the viewpoint of suppressing the occurrence of soft errors in high-density mounting, the contents of U and Th are preferably 2ppb or less, respectively, with lower contents being better.

Pb: less than 5 mass ppm

Generally, pb is contained in Sn as an impurity. The radioactive isotope in Pb undergoes beta decay to become ²¹⁰ Po， ²¹⁰ Alpha decay of Po to generate ²⁰⁶ Pb generates α rays. Therefore, it is preferable that the content of Pb as an impurity in the solder alloy is as small as possible.

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

As: less than 5 mass ppm

When As is added to the solder alloy, it is effective to suppress the thickening of the solder paste with time, but As is added, the alloy also contains radioactive elements, and the amount of α rays generated from the solder material increases.

The present embodiment aims to suppress thickening of a solder paste with time without adding As accompanied by impurities including radioactive elements.

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

Ni: 0-600 ppm by mass, fe:0 to 100 mass ppm inclusive, (1) formula

By soldering, the formation of an Sn-containing intermetallic compound (an intermetallic compound containing Sn) advances in the vicinity of a joining interface in a solder alloy, and if the Sn-containing intermetallic compound precipitates, the mechanical strength of a soldered joint deteriorates.

Ni:0 to 600 mass ppm inclusive

Ni is an element that suppresses formation of an intermetallic compound containing Sn at the bonding interface.

By containing Ni in the solder alloy, the formation of the Sn-containing intermetallic compound is suppressed, and the mechanical strength of the soldered joint can be maintained. On the other hand, if the Ni content in the solder alloy exceeds 600ppm, snNi compounds are precipitated in the vicinity of the joining interface in the solder alloy, and there is a concern that the mechanical strength of the soldered joint is deteriorated.

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

Fe:0 to 100 mass ppm inclusive

Like Ni, fe is an element that suppresses the formation of Sn-containing intermetallic compounds at the bonding interface. In addition, within the predetermined content range, the precipitation of needle-like crystals due to the SnFe compound can be suppressed, and short-circuiting of the circuit can be prevented.

Here, "needle-like crystals" mean crystals having an aspect ratio of 2 or more, which is the ratio of the major axis to the minor axis, among crystals derived from 1 kind of SnFe compound.

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

The alloy composition in the solder alloy of the present embodiment satisfies the following expression (1).

20≤Ni+Fe≤700 (1)

(1) In the formula, ni and Fe are both elements for suppressing the formation of Sn-containing intermetallic compounds at the bonding interface. In addition, in the present embodiment, both Ni and Fe are also advantageous in the effect of suppressing the thickening of the solder paste with time.

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 with time, the total content of Ni and Fe in the solder alloy must be 20ppm to 700ppm, based on the total mass (100 mass%) of the solder alloy. The total content of Ni and Fe is preferably 40ppm to 700ppm, more preferably 40ppm to 600ppm, and most preferably 40ppm to 200 ppm.

The "total content of Ni and Fe" is the content of Fe when the content of Ni in the solder alloy is 0ppm, the content of Ni when the content of Fe in the solder alloy is 0ppm, and the total content of Ni and Fe when both Ni and Fe are present.

In the case where Ni and Fe are both contained in the present embodiment, the ratio of Ni and Fe in the solder alloy is preferably 0.4 or more and 30 or less, more preferably 0.4 or more and 10 or less, further preferably 0.4 or more and 5 or less, and particularly preferably 0.4 or more and 2 or less in terms of the mass ratio Ni/Fe.

If the mass ratio of Ni/Fe is in the above-described preferable range, the effects of the present invention can be more easily obtained.

(optional elements)

The alloy composition in the solder alloy of the present embodiment may contain elements other than the above-described elements as necessary.

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

Ag:0 to 4 mass% inclusive

Ag can be formed in grain boundary ₃ Sn is an arbitrary element that improves the reliability of the solder alloy. In addition, ag is more expensive than Sn in ionization tendencyThe element coexists with Ni and Fe, thereby improving the effect of suppressing thickening of the solder paste over time. Further, if the content of Ag in the solder alloy is within the above range, the rise of 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, more preferably more than 0% and 4% or less, further preferably 0.5% or more and 3.5% or less, particularly preferably 1.0% or more and 3.0% or less, and most preferably 2.0% or more and 3.0% or less, with respect to the total mass (100% by mass) of the solder alloy.

Cu:0 to 0.9 mass%

Cu is used in a general solder alloy, and is an arbitrary element that can improve the bonding strength of a solder joint. Cu is an element whose ionization tendency is more expensive than Sn, and coexists with Ni and Fe, thereby improving the effect of suppressing the thickening of the solder paste with time.

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

In the case where Cu and Ni are present together in the present embodiment, the ratio of Cu to Ni in the solder alloy is preferably 8 or more and 175 or less, more preferably 10 or more and 150 or less, in terms of the mass ratio represented by Cu/Ni.

If the mass ratio of Cu/Ni is in the above-described preferred range, the effects of the present invention can be more easily obtained.

In the case where Cu and Fe are present together in the present embodiment, the ratio of Cu to Fe in the solder alloy is preferably 50 or more and 350 or less, more preferably 70 or more and 250 or less, in terms of a mass ratio represented by Cu/Fe.

If the mass ratio of Cu/Fe is in the above-described preferred range, the effects of the present invention can be more easily obtained.

In the case where Cu, ni, and Fe are contained together in the present embodiment, the ratio of Cu to Ni to Fe in the solder alloy is preferably 7 or more and 350 or less, more preferably 10 or more and 250 or less, in terms of a mass ratio represented by Cu/(Ni + Fe).

If the mass ratio of Cu/(Ni + Fe) is in the above-described preferred range, the effects of the present invention can be more easily obtained.

As an embodiment of the solder alloy, the following alloy composition may be used: u: less than 5 mass ppb, th: less than 5ppb by mass, pb: less than 5 mass ppm, as: less than 5 mass ppm, ni: 0-600 mass ppm inclusive, and Fe: more than 0ppm by mass and not more than 100ppm by mass, and the balance of Sn, satisfies the above formula (1), and has an alpha ray amount of 0.02cph/cm ² The following.

The alloy composition in the solder alloy may further contain Ag: 0% by mass or more and 4% by mass or less, and Cu: at least one of 0 mass% or more and 0.9 mass% or less.

In addition, as an embodiment of the solder alloy, the following alloy composition may be given: the method is characterized in that the reaction solution is prepared from U: less than 5 mass ppb, th: less than 5ppb by mass, pb: less than 5 mass ppm, as: less than 5 mass ppm, ni: more than 0ppm by mass and 600ppm by mass or less, and Fe: more than 0ppm by mass and 100ppm by mass or less; ag: more than 0 mass% and 4 mass% or less, and Cu: at least one of more than 0 mass% and 0.9 mass% or less; and Sn as the balance, satisfies the above formula (1), and has an alpha ray dose of 0.02cph/cm ² The following. In the alloy composition of the solder alloy, the ratio of Ni to Fe may be 0.4 or more and 30 or less in terms of the mass ratio represented by Ni/Fe.

In addition, as an embodiment of the solder alloy, the following alloy composition may be given: the method is characterized in that the reaction solution is prepared from U: less than 5 mass ppb, th: less than 5ppb by mass, 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 to 100 mass ppm; cu: more than 0 mass% and 0.9 mass% or less; and Sn as the balance, satisfying the above formula (1), the ratio of Cu to Ni being 8 or more and 175 or less in terms of the mass ratio Cu/Ni, and the amount of alpha rays being 0.02cph/cm ² The following. In the solder alloyIn the alloy composition of (3), the ratio of Ni to Fe may be 0.4 or more and 30 or less in terms of a mass ratio represented by Ni/Fe. Further, the foregoing alloy composition may further contain Ag: more than 0 mass% and not more than 4 mass%.

In addition, as an embodiment of the solder alloy, the following alloy composition may be given: the method is characterized in that the reaction solution is prepared from U: less than 5 mass ppb, th: less than 5ppb by mass, pb: less than 5 mass ppm, as: less than 5 mass ppm, ni: 0-600 mass ppm inclusive, and Fe:0 to 100 mass ppm; cu: more than 0 mass% and 0.9 mass% or less; and Sn as a balance, the balance satisfying the formula (1), the ratio of Cu to Ni to Fe being 7 or more and 350 or less in terms of a mass ratio represented by Cu/(Ni + Fe), and the amount of alpha rays being 0.02cph/cm ² The following. In the alloy composition of the solder alloy, the ratio of Ni to Fe may be 0.4 or more and 30 or less in terms of the mass ratio of Ni/Fe. Further, the foregoing alloy composition may further contain Ag: more than 0 mass% and not more than 4 mass%.

In addition, as an embodiment of the solder alloy, the following alloy composition may be given: the method is characterized in that the reaction solution is prepared from U: less than 5 mass ppb, th: less than 5ppb by mass, 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 Sn as a remainder, the balance satisfying the above formula (1), the ratio of Cu to Fe being 50 or more and 350 or less in terms of a mass ratio of Cu/Fe, and the amount of alpha rays being 0.02cph/cm ² The following. In the alloy composition of the solder alloy, the ratio of Ni to Fe may be 0.4 or more and 30 or less in terms of the mass ratio of Ni/Fe. Further, the foregoing alloy composition may further contain Ag: more than 0 mass% and not more than 4 mass%.

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

Bi:0 to 0.3 mass% inclusive

Bi is an element that has low reactivity with the flux and exhibits an effect of suppressing the thickening of the solder paste with time. Further, bi is an element that suppresses the deterioration of wettability because Bi can lower the liquidus temperature of the solder alloy and reduce 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 further preferably 0.010% or more and 0.3% or less, with respect to the total mass (100% by mass) of the solder alloy.

Sb:0 to 0.9 mass%

Sb is an element having low reactivity with the flux and exhibiting an effect of suppressing thickening of the solder paste with time, similarly to Bi. Since the wettability deteriorates if the Sb content in the solder alloy is too large, it is necessary to have an appropriate content when Sb is added.

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, and further preferably 0.010% or more and 0.9% or less, with respect to the total mass (100% by mass) of the solder alloy.

The alloy composition in the solder alloy of the present embodiment further contains Bi: 0% by mass or more and 0.3% by mass or less, and Sb: in the case of at least one of 0 mass% to 0.9 mass%, the alloy composition preferably satisfies the following formula (2).

0.03≤Bi+Sb≤1.2 (2)

(2) In the formula, bi and Sb represent the contents (mass%) thereof in the foregoing alloy composition.

(2) In the formula, bi and Sb are elements that exhibit an effect of suppressing thickening of the solder paste with time. In addition, in the present embodiment, both Bi and Sb contribute to the wettability of the solder alloy.

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

The "total content of Bi and Sb" is the content of Sb when the content of Bi in the solder alloy is 0%, the content of Bi when the content of Sb in the solder alloy is 0%, and the total content of Bi and Sb when Bi and Sb are present at the same time.

In the case where Bi and Sb are simultaneously contained in the present embodiment, the ratio of Bi to Sb in the solder alloy is preferably 0.01 to 10, more preferably 0.1 to 5, in terms of the mass ratio Sb/Bi.

When the Sb/Bi ratio is in the above-described preferable range, the effect of the present invention can be more easily obtained.

The balance: sn

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

< alpha ray dose >

The amount of alpha rays of the solder alloy of the present embodiment was 0.02cph/cm ² The following.

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

From the viewpoint of suppressing soft errors in further high-density mounting, the α -ray amount in the solder alloy of the present embodiment is preferably 0.01cph/cm ² Less, more preferably 0.002cph/cm ² The lower, more preferably 0.001cph/cm ² The following.

The amount of alpha rays generated from the solder alloy can be measured as follows. The above-mentioned method for measuring the amount of alpha rays is based on JEDEC STANDARD which is an international STANDARD.

Step (i):

a gas flow type α -ray amount measuring device was used.

As a sample for measurement, a solder alloy was melted and molded so that the area of one surface was 900cm ² The sheet-like solder alloy sheet of (1).

The α -ray measuring apparatus was provided with the solder alloy sheet as a measurement sample, and the PR gas was purged therefrom.

Note that, as the PR gas, a gas according to JEDEC STANDARD, which is an international STANDARD, is used. That is, the PR gas used for the measurement is a gas obtained by decay of radon (Rn) over 3 weeks from filling a gas bomb with a mixed gas of 90% argon gas and 10% methane gas.

Step (ii):

after the PR gas was flowed for 12 hours and left to stand in the α -ray dosimetry apparatus provided with the solder alloy sheet, α -ray dosimetry was performed for 72 hours.

Step (iii):

the average alpha ray dose was taken as "cph/cm ² "calculate. Outliers (counting based on device vibration, etc.) have their count removed for 1 hour.

[ method for producing solder alloy ]

The solder alloy of the present embodiment can be produced, for example, by a production method including a step of melt-mixing a raw material metal containing Sn and at least one of Ni and Fe.

For the purpose of designing a solder alloy with a low α ray content, it is preferable to use a low α ray content material as the raw material metal, and for example, it is preferable to use a high-purity material and a material from which U, th, and Pb are removed, among Sn, ni, and Fe, which are the raw material metals.

Sn as a raw material metal can be produced by a production method described in, for example, jp 2010-156052 a (patent document 1).

For example, ni and Fe, which are raw material metals, can be produced according to japanese patent No. 5692467.

The raw material metals may be melt-mixed by a conventionally known method.

In general, in a solder alloy, when each constituent element constituting the solder alloy does not function alone, and the content of each constituent element is within a predetermined range, various effects can be exhibited for the first time. According to the solder alloy of the above-described embodiment, the content of each constituent element is in the above-described range, so that the viscosity of the solder paste is suppressed from increasing with time, short circuit of the circuit is less likely to occur, the mechanical strength of the soldered joint is improved, and the occurrence of soft error can be suppressed. That is, the solder alloy of the present embodiment is useful as a target low α -ray amount material, and can suppress the occurrence of soft errors by being applied to the formation of solder bumps around a memory.

In the present embodiment, the content of each constituent element is within the above range, and Fe and Ni that contribute to suppression of Fe corrosion, suppression of thickening of the solder paste with time, improvement of mechanical strength of the soldered joint, and suppression of circuit short circuit satisfy a predetermined relationship, whereby the effects of the present invention can be more sufficiently exhibited.

In the present embodiment, the purpose is to design a low α -ray amount solder alloy that can suppress the thickening of a solder paste with time without adding As actively. In contrast, the object is achieved by using a solder alloy containing Ni and Fe as high-melting-point metals heated at high temperatures during refining or processing of a base metal at specific ratios.

The reason why the above-described effect is obtained is not clear, but is presumed as follows.

The purity of Sn for a solder alloy with a low α -ray dose is very high, and when the alloy after melting is solidified, the crystal size of Sn increases. In addition, the oxide film in Sn also forms a sparse oxide film corresponding thereto. Therefore, by adding Ni and Fe as high-melting point metals, the crystal size can be reduced, and a dense oxide film can be formed, whereby the reactivity of the alloy and the flux can be suppressed, and therefore, thickening of the solder paste with time becomes possible.

In addition, the solder alloy of the present embodiment has an area of 900cm on one surface formed by molding ² The amount of alpha rays after the heat treatment at 100 ℃ for 1 hour is preferably 0.02cph/cm ² The concentration is preferably 0.01cph/cm or less ² It is more preferably 0.002cph/cm ² The following are particularly preferredIs selected to be 0.001cph/cm ² The following.

The solder alloy exhibiting such an alpha ray amount is less likely to be caused in the alloy ²¹⁰ The segregation of Po is useful because the influence of the temporal change in the α ray amount is small. By applying a solder alloy exhibiting such an α -ray amount, the occurrence of soft errors is further suppressed, and it becomes easier to ensure stable operation of the semiconductor element.

(solder powder)

A solder powder according to an embodiment of the present invention includes the solder alloy according to an embodiment of the present invention.

The solder powder of the present embodiment is suitably used as a solder paste described later.

The solder powder can be produced by a known method such as a dropping method in which a molten solder alloy is dropped to obtain particles, a spraying method in which centrifugal spraying is performed, an atomizing method, a granulating method in a liquid state, or a method in which a bulk solder alloy is pulverized. In the dropping method or the spraying method, the dropping or spraying is preferably carried out in an inert atmosphere or a solvent for forming the granular form.

The solder powder of the present embodiment is preferably a spherical powder. The spherical powder improves the fluidity of the solder alloy.

When the solder powder of the present embodiment is a spherical powder, the solder powder is prepared in accordance with JIS Z3284-1: 2014 (table 2), the reference symbols 1 to 8 are preferably satisfied, and the reference symbols 4 to 8 are more preferably satisfied. If the particle size of the solder powder satisfies this condition, the surface area of the powder is not excessively large, and the increase in viscosity of the solder paste with time is suppressed, and the aggregation of fine powder is suppressed, and the increase in viscosity of the solder paste is sometimes suppressed. Therefore, soldering to a finer component is possible.

The solder powder of the present embodiment preferably contains at least 2 kinds of solder alloy particle groups having different particle size distributions at the same time. This improves the workability, such as improving the sliding property of the solder paste and facilitating printing.

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

The "sphericity of spherical powder" can be measured by using a CNC image measuring system (ULTRA QUICK VISION ULT RA QV350-PRO measuring apparatus manufactured by Mitutoyo Corporation) using the minimum region center method (MZC method).

The sphericity is a deviation from the sphere, and is an arithmetic average value calculated by dividing the diameter of each solder alloy particle by the major axis, for example, 500 pieces, and indicates that the value is closer to the sphere as the upper limit is 1.00.

(solder paste)

A solder paste according to an embodiment of the present invention contains the solder powder according to the above-described embodiment of the present invention and a flux.

< soldering flux >

The flux used in the solder paste of the present embodiment is composed of, for example, any of a resin component, an active component, a solvent, and other components, or a combination of 2 or more kinds of blending components thereof.

Examples of the resin component include rosin resins.

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

Examples of the derivative include purified rosin, hydrogenated rosin, disproportionated rosin, polymerized rosin, and modified products of α, β unsaturated carboxylic acid (acrylated rosin, maleylated rosin, fumarylated rosin, etc.), purified products, hydrogenated products, disproportionated products of the polymerized rosin, purified products, hydrogenated products, disproportionated products of the modified products of the α, β unsaturated carboxylic acid, etc., and 2 or more kinds thereof can be used.

In addition, examples of the resin component include, in addition to the rosin-based resin, terpene resins, modified terpene resins, terpene-phenolic resins, modified terpene-phenolic resins, styrene resins, modified styrene resins, xylene resins, modified xylene resins, acrylic resins, polyethylene resins, acrylic-polyethylene copolymer resins, epoxy resins, and the like.

Examples of the modified terpene resin include an aromatic modified terpene resin, a hydrogenated terpene resin, and a hydrogenated aromatic modified terpene resin. Examples of the modified terpene phenol resin include hydrogenated terpene phenol resins and the like. Examples of the modified styrene resin include styrene acrylic resins and styrene maleic acid resins. Examples of the modified xylene resin include a phenol-modified xylene resin, an alkylphenol-modified xylene resin, a phenol-modified methyl-xylene resin, a polyol-modified xylene resin, and a polyoxyethylene-adduct xylene resin.

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

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-bishydroxymethylpropionic acid, tartaric acid, malic acid, glycolic acid, diglycolic acid, thioglycolic acid, dimercaptoacetic acid, stearic acid, 12-hydroxystearic acid, palmitic acid, and oleic acid.

Examples of the amine include ethylamine, triethylamine, ethylenediamine, triethylenetetramine, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1, 2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-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' -methylimidazolyl- (1 ') ] -ethyl-s-triazine, 2, 4-diamino-6- [2' -undecylimidazolyl- (1 ') ] -ethyl-s-triazine, 2, 4-diamino-6- [2' -ethyl-4 ' -methylimidazolyl- (1 ') ] -methyl-s-triazine, 2' -ethylimidazolyl-4-isocyanuric acid adduct, 2-diamino-6- [2' -methylimidazolyl- (1 ') ] -methyl-1 ') ] -triazine, 2' -ethylimidazolyl- (1 ') -2 ' -isocyanato-2 ' -isocyanurate, 2-phenyl-4, 5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2, 3-dihydro-1H-pyrrolo [1,2-a ] benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline, 2, 4-diamino-6-vinyl-s-triazine 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, 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' -methylenebis [6- (2H-benzotriazol-2-yl) -4-tert-octylphenol ], (I) a salt thereof, and (II) a salt thereof, 6- (2-benzotriazolyl) -4-tert-octyl-6 '-tert-butyl-4' -methyl-2, 2 '-methylenebisphenol, 1,2, 3-benzotriazole, 1- [ N, N-bis (2-ethylhexyl) aminomethyl ] benzotriazole, carboxybenzotriazole, 1- [ N, N-bis (2-ethylhexyl) aminomethyl ] methylbenzotriazole, 2' - [ [ (methyl-1H-benzotriazol-1-yl) methyl ] imino ] diethanol, 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-phenyltetrazole, and the like.

Examples of the halogen-based active agent include amine hydrohalide salts and organic halogen compounds.

The amine hydrohalide salt is a compound obtained by reacting an amine with a hydrogen halide. Examples of the amine include ethylamine, ethylenediamine, triethylamine, diphenylguanidine, ditolylbutylguanidine, methylimidazole, and 2-ethyl-4-methylimidazole, and examples of the hydrogen halide include hydrides of chlorine, bromine, and iodine.

Examples of the organic halogen compound include trans-2, 3-dibromo-2-butene-1, 4-diol, triallyl isocyanurate hexabromide, 1-bromo-2-butanol, 1-bromo-2-propanol, 3-bromo-1, 2-propanediol, 1, 4-dibromo-2-butanol, 1, 3-dibromo-2-propanol, 2, 3-dibromo-1, 4-butanediol, 2, 3-dibromo-2-butene-1, 4-diol and the like.

Examples of the thixotropic agent include wax-based thixotropic agents, amide-based thixotropic agents, and sorbitol-based thixotropic agents.

Examples of the wax thixotropic agent include hydrogenated castor oil and the like.

Examples of the amide-based thixotropic agent include monoamide-based thixotropic agents, bisamide-based thixotropic agents, and polyamide-based thixotropic agents, and specific examples thereof 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-toluamide, aromatic amide, methylene bisstearic acid amide, ethylene bislauric acid amide, ethylene bishydroxystearic acid amide, saturated fatty acid bisamide, methylene bisoleic acid amide, unsaturated fatty acid bisamide, m-xylylene bisstearic acid amide, aromatic bisamide, saturated fatty acid polyamide, unsaturated fatty acid polyamide, aromatic polyamide, substituted amide, methylol stearic acid amide, methylolamide, and fatty acid ester amide.

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

Examples of the solvent include water, alcohol solvents, glycol ether solvents, terpineol, and the like.

As the alcohol-based solvent, there may be mentioned, examples thereof include isopropanol, 1, 2-butanediol, isobornyl cyclohexanol, 2, 4-diethyl-1, 5-pentanediol, 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-tris (hydroxymethyl) ethane, 2-ethyl-2-hydroxymethyl-1, 3-propanediol, 2' -oxybis (methylene) bis (2-ethyl-1, 3-propanediol) 2, 2-bis (hydroxymethyl) -1, 3-propanediol, 1,2, 6-trihydroxyhexane, bis [2, 2-tris (hydroxymethyl) ethyl ] ether, 1-ethynyl-1-cyclohexanol, 1, 4-cyclohexanediol, 1, 4-cyclohexanedimethanol, erythritol, threitol, guaifenesin, 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, diethylene glycol dibutyl ether, and triethylene glycol monobutyl ether.

Examples of the metal deactivator include hindered phenol compounds and nitrogen compounds. The flux contains either a hindered phenol compound or a nitrogen compound, and thus the thickening suppression effect of the solder paste is easily improved.

The "metal deactivator" as used herein refers to a compound having the property of preventing the metal from being deteriorated by contact with a certain compound.

The hindered phenol compound is a phenol compound having a bulky substituent (for example, a branched or cyclic alkyl group such as a t-butyl group) at least in the ortho position to the phenol.

The hindered phenol compound is not particularly limited, and examples thereof include triethylene glycol ether-bis (3-t-butyl-4-hydroxy-5-methylphenyl) propionate, N, N '-hexamethylenebis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionamide ], 1, 6-hexanediol bis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], 2' -methylenebis [6- (1-methylcyclohexyl) -p-cresol ], 2 '-methylenebis (6-tert-butyl-p-cresol), 2' -methylenebis (6-tert-butyl-4-ethylphenol), triethylene glycol-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-tert-butylamino) -1,3, 5-triazine, pentaerythritol-tetrakis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], 2-thio-bis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], 2, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], and diethylene, octadecyl-3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate, N '-hexamethylenebis (3, 5-di-tert-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' -bis [2- [2- (3, 5-di-tert-butyl-4-hydroxyphenyl) ethylcarbonyloxy ] ethyl ] oxamide, a compound represented by the following chemical formula, and the like.

(wherein Z is an optionally substituted alkylene group. R ¹ And R ² Each independently is an optionally substituted alkyl, aralkyl, aryl, heteroaryl, cycloalkyl or heterocycloalkyl group. R is ³ And R ⁴ Each independently is an optionally substituted alkyl group. )

Examples of the nitrogen compound in the metal deactivator include a hydrazide nitrogen compound, an amide nitrogen compound, a triazole nitrogen compound, and a melamine nitrogen compound.

The hydrazide-based nitrogen compound may be any nitrogen compound having a hydrazide skeleton, and examples thereof include dodecanedioic acid bis [ N2- (2-hydroxybenzoyl) hydrazide ], N '-bis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl ] hydrazine, sebacic acid bis-salicyloyl hydrazide, N-salicylidene-N' -salicyloyl hydrazide, m-nitrobenzoyl hydrazide, 3-aminophenyl hydrazide, phthalic acid dihydrazide, adipic acid hydrazide, oxabis (2-hydroxy-5-octylbenzylidene hydrazide), N '-benzoylpyrrolidone carboxylic acid hydrazide, N' -bis (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hydrazine, and the like.

The amide-based nitrogen compound may be a nitrogen compound having an amide skeleton, and examples thereof include N, N' -bis {2- [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyloxy ] ethyl } oxamide and the like.

The triazole-based nitrogen compound may be a nitrogen compound having a triazole skeleton, and examples thereof include N- (2H-1, 2, 4-triazol-5-yl) salicylamide, 3-amino-1, 2, 4-triazole, and 3- (N-salicyloyl) amino-1, 2, 4-triazole.

The melamine nitrogen compound may be any nitrogen compound having a melamine skeleton, and examples thereof include melamine and melamine derivatives. More specifically, for example, triaminotriazine, alkylated triaminotriazine, alkoxyalkylated triaminotriazine, melamine, alkylated melamine, alkoxyalkylated melamine, N2-butylmelamine, N2-diethylmelamine, N', N ", N ″ -hexa (methoxymethyl) melamine, and the like can be given.

Examples of the other components include a surfactant, a silane coupling agent, an antioxidant, and a colorant.

Examples of the surfactant include nonionic surfactants and weakly cationic surfactants.

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 weakly cationic surfactant include a terminal diamine polyethylene glycol, a terminal diamine polyethylene glycol-polypropylene glycol copolymer, an aliphatic amine polyoxyethylene adduct, an aromatic amine polyoxyethylene adduct, and a polyamine polyoxyethylene adduct.

Examples of the surfactant other than those described above include polyoxyalkylene acetylene glycols, polyoxyalkylene glycerol ethers, polyoxyalkylene alkyl ethers, polyoxyalkylene esters, polyoxyalkylene alkylamines, and polyoxyalkylene alkylamides.

The content of the flux in the solder paste of the present embodiment is preferably 5 to 95% by mass, more preferably 5 to 50% by mass, and still more preferably 5 to 15% by mass, based on the total mass (100% by mass) of the solder paste.

When the content of the flux is within this range, the effect of suppressing the thickening by the solder powder can be sufficiently exhibited.

The solder paste of the present embodiment can be manufactured by a manufacturing method that is common in the art.

The solder paste can be obtained by heating and mixing the components constituting the flux to prepare the flux, and stirring and mixing the solder powder in the flux. Further, the effect of suppressing the thickening with time is expected, and a zirconia powder may be further added in addition to the solder powder.

(solder ball)

The solder ball according to one embodiment of the present invention is composed of the solder alloy according to one embodiment of the present invention.

The solder alloy of the above embodiment may be used in the form of a solder ball.

The solder ball of the present embodiment can be manufactured by using a method common in the art, i.e., a dropping method.

The particle diameter of the solder ball is preferably 1 μm or more, more preferably 10 μm or more, further preferably 20 μm or more, and particularly preferably 30 μm or more. On the other hand, the particle diameter of the solder ball is preferably 3000 μm or less, more preferably 1000 μm or less, further preferably 600 μm or less, and particularly preferably 300 μm or less.

The particle diameter 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, further preferably 20 μm or more and 600 μm or less, and particularly preferably 30 μm or more and 300 μm or less.

(Pre-formed solder)

The solder preform according to one embodiment of the present invention is composed of the solder alloy according to one embodiment of the present invention.

The solder alloy according to the above embodiment can be used as a preform.

Examples of the shape of the preform according to the present embodiment include a gasket, a ring, a pellet, a disk, a tape, and a string.

(solder joint)

A solder joint according to an embodiment of the present invention is composed of the solder alloy according to the above-described embodiment of the present invention.

The solder joint of the present embodiment is composed of an electrode and a solder joint. The solder joint refers to a portion mainly formed of a solder alloy.

The solder joints of the present embodiment can be formed by bonding electrodes of PKGs (packages) such as IC chips and electrodes of substrates such as PCBs (printed circuit boards) with the solder alloys of the above embodiments, for example.

The solder joint of the present embodiment can be manufactured by a method that is common in the art, such as mounting 1 solder ball of the above-described embodiment on 1 electrode coated with flux and bonding the solder ball.

Examples

The present invention will be described in further detail with reference to examples below, but the present invention is not limited to these examples.

In the present example, "ppb" and "ppm" and "%" in the solder alloy composition are "mass ppb", "mass ppm" and "% by mass", respectively, unless otherwise specified.

< solder alloy >

(examples 1 to 370 and comparative examples 1 to 8)

The raw material metals were melted and stirred to prepare solder alloys of respective examples having alloy compositions shown in tables 1A to 16B.

< solder powder >

The solder alloys of the examples were melted, and solder alloy compositions of the examples, each having an alloy composition shown in tables 1A to 16B, were prepared by an atomization method, and the alloy compositions were measured in JIS Z3284-1: 2014 (table 2) is a solder powder satisfying the size (particle size distribution) indicated by symbol 4.

< preparation of flux (F0) >

A rosin resin is used as the resin component.

Thixotropic agents, organic acids, amines and halogen-based active agents are used as active ingredients.

A glycol ether solvent is used as the solvent.

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 were mixed to prepare a flux (F0).

< manufacture of solder paste >

Solder pastes were produced by mixing the flux (F0) with solder powders composed of solder alloys of examples having the alloy compositions shown in tables 1A to 16B, respectively.

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

< evaluation >

Using the above-described solder paste, evaluation of thickening suppression was performed.

Further, using the solder alloy, the deposition inhibition of the needle-like crystal, the formation inhibition of the Sn-containing intermetallic compound, and the α -ray amount were evaluated. Further, comprehensive evaluation was performed.

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

[ thickening inhibition ]

(1) Verification method

For the solder paste just after the preparation, malcolm co., ltd. System: PCU-205, at rotational speed: the viscosity was measured at 10rpm at 25 ℃ for 12 hours in the air.

(2) Criterion for determination

Good: the viscosity after 12 hours is 1.2 times or less as compared with the viscosity immediately after the solder paste is prepared and after 30 minutes has elapsed.

X: the viscosity after 12 hours is more than 1.2 times as high as the viscosity at the time of 30 minutes from immediately after the preparation of the solder paste.

If the judgment is "good", it can be said that a sufficient thickening suppressing effect is obtained. That is, the viscosity of the solder paste can be suppressed from increasing with time.

[ precipitation inhibition of needle-like crystals ]

(1) Verification method

The solder alloys of the respective examples were melted at 250 ℃ and cooled to 100 ℃ or lower, which is the solidus temperature of the entire alloy composition, for 10 minutes. The solder alloy after cooling was observed at 5 arbitrary positions in the range of 300 μm × 300 μm in cross section using a Scanning Electron Microscope (SEM), and the presence or absence of needle-like crystals derived from the SnFe compound was confirmed in the cross-sectional SEM photograph.

The needle-like crystal in the present example is a crystal having an aspect ratio of 2 or more, which is a ratio of a long diameter to a short diameter, among crystals derived from 1 SnFe compound.

(2) Criterion for determination

O: in the SEM observation image at all 5, needle-shaped crystals were not observed.

X: in at least 1 SEM observation image, needle-shaped crystals were observed.

If the evaluation is "good", the precipitation inhibiting effect of the needle-like crystals is exhibited. That is, short-circuiting of the circuit may not easily occur.

[ suppression of formation of Sn-containing intermetallic Compound ]

(1) Verification method

The solder alloys of the respective examples were melted at 250 ℃ and cooled to 100 ℃ or lower, which is the solidus temperature of the entire alloy composition, in 10 minutes. The solder alloy after cooling was observed at any 5 points in the range of 300. Mu. M.times.300. Mu.m in cross section by SEM to confirm the presence or absence of Sn (Cu) Ni compounds.

(2) Criterion for determination

O: in the SEM observation images at all 5, no Sn (Cu) Ni compound was observed.

X: in the SEM observation image of at least 1 place, a Sn (Cu) Ni compound was observed.

If the evaluation is "good", it can be said that the effect of suppressing the formation of the Sn-containing intermetallic compound is exhibited. That is, the mechanical strength of the soldered joint can be improved.

[ alpha ray dose ]

(1) One of the verification methods

The measurement of the α -ray amount was performed according to the above steps (i), (ii), and (iii) using an α -ray amount measuring device of a gas flow rate ratio counter.

The solder alloy sheet immediately after production was used as a measurement sample.

The solder alloy sheet was molded by melting the solder alloy just after the production into a sheet having a surface area of 900cm ² The sheet-like product of (1).

The measurement sample was placed in an α -ray measuring apparatus, and after flowing and standing a PR-10 gas for 12 hours, the α -ray amount was measured for 72 hours.

(2) One of the criteria for determination

Good for good: the amount of alpha rays generated from the measurement sample was 0.002cph/cm ² The following.

Good: the alpha ray generated by the self-determination sample exceeds 0.002cph/cm ² And is 0.02cph/cm ² The following.

X: the alpha ray generated by the self-determination sample exceeds 0.02cph/cm ² 。

The good quality judgment may be a solder material with a low α -ray amount if the good quality judgment is the good quality judgment.

(3) Second verification method

The measurement of the α -ray amount was performed in the same manner as in the verification method (1) except that the measurement sample was changed.

As a sample for measurement, a solder alloy immediately after production was melted and formed to have an area of 900cm on one surface ² The sheet-like solder alloy sheet of (2) was subjected to heat treatment at 100 ℃ for 1 hour and then naturally cooled for use.

(4) Second judgment standard

The judgment is good on "good quality" or good quality ", it can be said to be a solder material with a low alpha ray amount.

(5) Third verification method

After a solder alloy sheet of a measurement sample in which the α -ray amount was measured by one of the above (1) verification methods was stored for 1 year, the α -ray amount was measured again according to the above steps (i), (ii), and (iii), and the change in the α -ray amount with time was evaluated.

(6) Third judgment reference

Good component: the alpha ray generated by the self-determination sample exceeds 0.002cph/cm ² And is 0.02cph/cm ² The following.

×：The alpha ray generated by the self-determination sample exceeds 0.02cph/cm ² 。

If the evaluation is "good quality" or "good quality", it can be said that the generated α -ray amount is not changed with time and is stable. That is, occurrence of soft errors in the electronic device class can be suppressed.

[ comprehensive evaluation ]

Good component: in tables 1A to 16B, each evaluation of the thickening suppression, the precipitation suppression of needle-like crystals, the formation suppression of Sn-containing intermetallic compounds, the amount of α -ray immediately after production, the amount of α -ray after heat treatment, and the temporal change in the amount of α -ray is "good" or "good".

X: in tables 1A to 16B, at least 1 of the respective evaluations of the inhibition of thickening, the inhibition of the precipitation of needle-like crystals, the inhibition of the formation of Sn-containing intermetallic compounds, the amount of α rays immediately after production, the amount of α rays after heat treatment, and the change with time in the amount of α rays was x.

[ 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, it was confirmed that, in the case of using the solder alloys to which examples 1 to 370 of the present invention were applied, the solder paste could be inhibited from increasing in viscosity with time, short-circuiting of the circuit was less likely to occur, the mechanical strength of the soldered joint was improved, and the occurrence of soft errors was also inhibited.

On the other hand, the solder alloys of comparative examples 1 to 8, which were outside the scope of the present invention, all showed at least 1 difference in the results of suppression of thickening, suppression of precipitation of needle-like crystals, suppression of formation of Sn-containing intermetallic compounds, and evaluation of α -ray amount.

Claims

1. A solder alloy having the following alloy composition: u: less than 5 mass ppb, th: less than 5ppb by mass, pb: less than 5 mass ppm, as: less than 5 mass ppm, ni: 0-600 mass ppm inclusive, and Fe:0 to 100 mass ppm inclusive and the balance of Sn,

satisfies the following formula (1), and

alpha ray dose is 0.02cph/cm ² In the following, the following description is given,

20≤Ni+Fe≤700 (1)

(1) In the formula, ni and Fe represent their respective contents (mass ppm) in the alloy composition.

2. A solder alloy having the following alloy composition: 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: more than 0ppm by mass and not more than 100ppm by mass, and the balance being Sn,

satisfies the following formula (1), and

the alpha ray dose is 0.02cph/cm ² In the following, the following description is given,

20≤Ni+Fe≤700 (1)

(1) In the formula, ni and Fe represent the content (mass ppm) of each in the alloy composition.

3. Solder alloy according to claim 1 or 2, wherein the alloy composition further satisfies the following formula (1'),

40≤Ni+Fe≤200(1’)

(1') in the formula, ni and Fe represent the respective contents thereof (mass ppm) in the alloy composition.

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

5. Solder alloy according to any of claims 1 to 4, wherein As is below 2 mass ppm.

6. Solder alloy according to any of claims 1 to 5, wherein the alloy composition further contains Ag: 0% by mass or more and 4% by mass or less and Cu: at least one of 0 mass% or more and 0.9 mass% or less.

7. A solder alloy having the following alloy composition:

u: less than 5 mass ppb, th: less than 5ppb by mass, pb: less than 5 mass ppm, as: less than 5 mass ppm, ni: more than 0ppm by mass and 600ppm by mass or less, and Fe: more than 0 mass ppm and 100 mass ppm or less;

The balance of Sn, and the balance of Sn,

satisfies the following formula (1), and

20≤Ni+Fe≤700 (1)

8. A solder alloy having the following alloy composition:

cu: more than 0 mass% and 0.9 mass% or less; and is provided with

The balance of Sn,

satisfies the following formula (1),

the ratio of Cu to Ni is 8 or more and 175 or less in terms of a mass ratio represented by Cu/Ni, and

20≤Ni+Fe≤700 (1)

9. A solder alloy having the following alloy composition:

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 to 100 mass ppm inclusive;

cu: more than 0 mass% and 0.9 mass% or less; and is provided with

The balance of Sn,

satisfies the following formula (1),

the ratio of Cu to Ni to Fe is 7 or more and 350 or less in terms of a mass ratio represented by Cu/(Ni + Fe), and

20≤Ni+Fe≤700 (1)

10. A solder alloy having the following alloy composition:

u: less than 5 mass ppb, th: less than 5ppb by mass, 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 is

The balance of Sn, and the balance of Sn,

satisfies the following formula (1),

the ratio of Cu to Fe is 50 or more and 350 or less in terms of a mass ratio represented by Cu/Fe, and

20≤Ni+Fe≤700 (1)

11. The solder alloy according to any one of claims 7 to 10, wherein a ratio of Ni to Fe is 0.4 or more and 30 or less in terms of a mass ratio of Ni/Fe.

12. Solder alloy according to any of claims 8 to 11, wherein the alloy composition further contains Ag: more than 0 mass% and not more than 4 mass%.

13. Solder alloy according to any of claims 1 to 12, wherein the alloy composition also contains Bi:0 mass% or more and 0.3 mass% or less and Sb: at least one of 0 mass% or more and 0.9 mass% or less.

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

0.03≤Bi+Sb≤1.2 (2)

(2) Wherein Bi and Sb represent the content (mass%) of each in the alloy composition.

15. Solder alloy according to any of claims 1 to 14, wherein the area for molding into one side is 900cm ² The sheet-like solder alloy sheet of (2) is a sheet obtained by melting at 100 ℃ of 1 hrThe amount of alpha rays after the heat treatment was 0.02cph/cm ² The following.

16. Solder alloy according to any one of claims 1 to 15, having an alpha dose of 0.002cph/cm ² The following.

17. Solder alloy according to claim 16, having an alpha dose of 0.001cph/cm ² The following.

18. Solder powder consisting of the solder alloy according to any of claims 1 to 17.

19. Solder powder according to claim 18 simultaneously having groups of more than 2 solder alloy particles with different particle size distributions.

20. A solder paste comprising the solder powder of claim 18 or 19 and a flux.

21. A solder ball consisting of the solder alloy of any one of claims 1 to 17.

22. A preformed solder consisting of the solder alloy of any one of claims 1 to 17.

23. A solder joint made of the solder alloy according to any one of claims 1 to 17.