# US 12,109,653 B2 · Solder alloy, solder ball, solder paste, and solder joint

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- Number: US 12,109,653 B2
- Document ID: US12109653B2
- Status: Granted
- Kind: B2
- Application number: 18/224,833
- Filed: 2023-07-21
- Published: 2024-01-25
- Granted: 2024-10-08
- Earliest claimed: 2022-07-22
- Assignees: Senju Metal Industry Co., Ltd.
- Applicants: Senju Metal Industry Co., Ltd.
- Inventors: Takahiro Matsufuji; Shunsaku Yoshikawa; Hiroki Sudo
- Web page: https://patentgrep.com/patent/US12109653B2

## CPC

- B23K 35/262: {Sn as the principal constituent}
- B23K 35/0222: {for use in soldering or brazing (B23K35/0205 takes precedence)}
- B23K 35/0244: {Powders, particles or spheres; Preforms made therefrom}
- B23K 35/025: {Pastes, creams or slurries}
- B23K 35/264: {Bi as the principal constituent}
- C22C 12/00: Alloys based on antimony or bismuth
- C22C 13/02: with antimony or bismuth as the next major constituent
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- C22C: ALLOYS (treatment of alloys C21D, C22F)

## Abstract

Provided are a solder, a solder alloy, a solder ball, a solder paste, and a solder joint, which have a low melting point, high hardness in a high-temperature environment, heat cycle resistance, and electromigration resistance. The solder alloy has an alloy composition that includes by mass %, Bi: 30 to 60%, Ag: 0.7 to 2.0%, Cu: more than 0% and 1.00% or less, Ni: 0.01 to 1.00%, Sb: 0.2 to 1.5%, with the balance being Sn.

## Claims

### Claim 1

A solder alloy having an alloy composition consisting of, by mass %,
Bi: 30 to 60%,
Ag: 0.7 to 2.0%,
Cu: more than 0% and 1.00% or less,
Ni: 0.01 to 1.00%,
Sb: 0.2 to 1.5%, with the balance being Sn,
wherein the solder alloy exhibits the following properties:
a melting rate in which 99.9% has melted before reaching 200° C., wherein the melting rate is judged based on an area ratio of a DSC curve and is a value obtained by dividing reaction calories necessary for complete melting by reaction calories completed before reaching 200° C., and multiplying the result of dividing by 100;
an average surface hardness of 7.0 Hv or more, wherein the average surface hardness is determined by measuring surface hardness of 5 bumps that are subjected to a load of 1.96N for 60 seconds at 110° C.;
an average number of heat cycles until rupture of at least 3,000, wherein the heat cycles include a low temperature of −40° C., a high temperature of +100° C., and a holding time of 10 minutes, wherein determining the average number of cycles until rupture includes subjecting test substrates to the heat cycles, monitoring resistance values using a daisy chain circuit, and judging that rupture has occurred when a resistance value increase of over 200% is reached from the start of the test, wherein the test substrates are prepared by placing solder balls with a diameter of 0.24 mm on electrodes of a substrate on which a soldering flux comprising a solvent, an activator, a thixotropic agent, and an organic acid was applied, mounting BGA components, and performing reflow soldering under conditions of a maximum temperature of 190° C. and a holding time of 90 seconds; and
an electromigration resistance in which at least 300 hours elapses until the electrical resistance increases by 150% compared with an initial electrical resistance value, wherein the electrical resistance is determined by connecting a test substrate to a variable switching power supply and applying a current in a silicon oil bath held at 110° C. and continuously measuring the electrical resistance, wherein the test substrate is prepared by fabricating a package using solder balls with a diameter of 0.24 mm made of the solder alloy by performing reflow soldering on a package substrate with a size of 12 mm×12 mm including Cu electrodes with a diameter of 0.24 mm by using a water-soluble flux, printing solder paste on a glass epoxy substrate with a size of 29 mm×19 mm and a thickness of 0.8 mm, and mounting the fabricated package to the glass epoxy substrate using reflow soldering under conditions of a maximum temperature of 190° C. and a holding time of 90 seconds to fabricate the test substrate.

### Claim 2

A solder alloy having an alloy composition consisting of, by mass %,
Bi: 30 to 60%,
Ag: 0.7 to 2.0%,
Cu: more than 0% and 1.00% or less,
Ni: 0.01 to 1.00%,
Sb: 0.2 to 1.5%, and
at least one selected from the group consisting of,
at least one of P, Ge, Ga, and As: 0.1% or less in total,
at least one of Fe and Co: 0.1% or less in total,
Pd: 0.1% or less,
Zr: 0.1% or less,
Zn: 0.1% or less, and
Pb: 0.02% or less,
with the balance being Sn,
wherein the solder alloy exhibits the following properties:
a melting rate in which 99.9% has melted before reaching 200° C., wherein the melting rate is judged based on an area ratio of a DSC curve and is a value obtained by dividing reaction calories necessary for complete melting by reaction calories completed before reaching 200° C., and multiplying the result of dividing by 100;
an average surface hardness of 7.0 Hv or more, wherein the average surface hardness is determined by measuring surface hardness of 5 bumps that are subjected to a load of 1.96N for 60 seconds at 110° C.;
an average number of heat cycles until rupture of at least 3,000, wherein the heat cycles include a low temperature of −40° C., a high temperature of +100° C., and a holding time of 10 minutes, wherein determining the average number of cycles until rupture includes subjecting test substrates to the heat cycles, monitoring resistance values using a daisy chain circuit, and judging that rupture has occurred when a resistance value increase of over 200% is reached from the start of the test, wherein the test substrates are prepared by placing solder balls with a diameter of 0.24 mm on electrodes of a substrate on which a soldering flux comprising a solvent, an activator, a thixotropic agent, and an organic acid was applied, mounting BGA components, and performing reflow soldering under conditions of a maximum temperature of 190° C. and a holding time of 90 seconds; and
an electromigration resistance in which at least 300 hours elapses until the electrical resistance increases by 150% compared with an initial electrical resistance value, wherein the electrical resistance is determined by connecting a test substrate to a variable switching power supply and applying a current in a silicon oil bath held at 110° C. and continuously measuring the electrical resistance, wherein the test substrate is prepared by fabricating a package using solder balls with a diameter of 0.24 mm made of the solder alloy by performing reflow soldering on a package substrate with a size of 12 mm×12 mm including Cu electrodes with a diameter of 0.24 mm by using a water-soluble flux, printing solder paste on a glass epoxy substrate with a size of 29 mm×19 mm and a thickness of 0.8 mm, and mounting the fabricated package to the glass epoxy substrate using reflow soldering under conditions of a maximum temperature of 190° C. and a holding time of 90 seconds to fabricate the test substrate.

### Claim 3

A solder alloy having an alloy composition consisting of, by mass %,
Bi: 30 to 60%,
Ag: 0.7 to 2.0%,
Cu: more than 0% and 1.00% or less,
Ni: 0.01 to 1.00%,
Sb: 0.2 to 1.5%, and
at least one selected from the group consisting of,
P: less than 0.01%,
Ge: 0.01% or less,
Ga: less than 0.01%,
As: more than 0.001% and 0.01% or less,
Co: less than 0.01%,
Pd: 0.01% or less, and
Pb: less than 0.004%,
with the balance being Sn,
wherein the solder alloy exhibits the following properties:
a melting rate in which 99.9% has melted before reaching 200° C., wherein the melting rate is judged based on an area ratio of a DSC curve and is a value obtained by dividing reaction calories necessary for complete melting by reaction calories completed before reaching 200° C., and multiplying the result of dividing by 100;
an average surface hardness of 7.0 Hv or more, wherein the average surface hardness is determined by measuring surface hardness of 5 bumps that are subjected to a load of 1.96N for 60 seconds at 110° C.;
an average number of heat cycles until rupture of at least 3,000, wherein the heat cycles include a low temperature of −40° C., a high temperature of +100° C., and a holding time of 10 minutes, wherein determining the average number of cycles until rupture includes subjecting test substrates to the heat cycles, monitoring resistance values using a daisy chain circuit, and judging that rupture has occurred when a resistance value increase of over 200% is reached from the start of the test, wherein the test substrates are prepared by placing solder balls with a diameter of 0.24 mm on electrodes of a substrate on which a soldering flux comprising a solvent, an activator, a thixotropic agent, and an organic acid was applied, mounting BGA components, and performing reflow soldering under conditions of a maximum temperature of 190° C. and a holding time of 90 seconds; and
an electromigration resistance in which at least 300 hours elapses until the electrical resistance increases by 150% compared with an initial electrical resistance value, wherein the electrical resistance is determined by connecting a test substrate to a variable switching power supply and applying a current in a silicon oil bath held at 110° C. and continuously measuring the electrical resistance, wherein the test substrate is prepared by fabricating a package using solder balls with a diameter of 0.24 mm made of the solder alloy by performing reflow soldering on a package substrate with a size of 12 mm×12 mm including Cu electrodes with a diameter of 0.24 mm by using a water-soluble flux, printing solder paste on a glass epoxy substrate with a size of 29 mm×19 mm and a thickness of 0.8 mm, and mounting the fabricated package to the glass epoxy substrate using reflow soldering under conditions of a maximum temperature of 190° C. and a holding time of 90 seconds to fabricate the test substrate.

### Claim 4 (depends on 1)

The solder alloy according to claim 1,
wherein the alloy composition satisfies at least one of the following relations (1) to (3):
13.00≤Bi/(Ag+Cu+Ni+Sb)≤23.27 Relation (1)
0.017≤(Ag+Cu+Ni)/Sn≤0.039 Relation(2)
70.9≤(Bi+Ag+Sb)/(Cu+Ni)≤6349 Relation (3)
wherein Sn, Bi, Ag, Cu, Ni, and Sb in the relations (1) to (3) each represent the contents mass % thereof in the solder alloy.

### Claim 5 (depends on 1)

A solder ball consisting of the solder alloy according to claim 1.

### Claim 6 (depends on 1)

A solder paste comprising a solder powder comprising the solder alloy according to claim 1.

### Claim 7 (depends on 1)

A solder joint comprising the solder alloy according to claim 1.

### Claim 8 (depends on 2)

The solder alloy according to claim 2,
wherein the alloy composition satisfies at least one of the following relations (1) to (3):
13.00≤Bi/(Ag+Cu+Ni+Sb)≤23.27 (1)
0.017≤(Ag+Cu+Ni)/Sn≤0.039 (2)
70.9≤(Bi+Ag+Sb)/(Cu+Ni)≤6349 (3)
wherein Sn, Bi, Ag, Cu, Ni, and Sb in the relations (1) to (3) each represent the contents mass % thereof in the solder alloy.

### Claim 9 (depends on 2)

A solder ball consisting of the solder alloy according to claim 2.

### Claim 10 (depends on 2)

A solder paste comprising a solder powder consisting of the solder alloy according to claim 2.

### Claim 11 (depends on 2)

A solder joint comprising the solder alloy according to claim 2.