Lead-free and antimony-free solder alloy, solder ball, ball grid array, and solder joint

Patent metadata

Field	Value
Publication number	US-12447565-B2
Application number	US-202117922218-A
Country	US
Kind code	B2
Filing date	Apr 29, 2021
Priority date	Apr 30, 2020
Publication date	Oct 21, 2025
Grant date	Oct 21, 2025

Abstract

Provided are a lead-free and antimony-free solder alloy which has a medium-low melting point and ensures solderability even after being held at a high temperature for a long time, a solder ball, a ball grid array, and a solder joint. The lead-free and antimony-free solder alloy has an alloy composition consisting of 12 to 23% by mass of In, and 0.001 to 0.08% by mass of Ge, with the balance being Sn and unavoidable impurities. Preferably, the alloy composition has 16 to 21% by mass of In; the alloy composition has 0.005 to 0.01% by mass of Ge; the alloy composition has 0.005 to 0.009% by mass of Ge; U and Th as the unavoidable impurities are each included in an amount of 5 mass ppb or less; and As and Pb as the unavoidable impurities are each included in an amount of 5 mass ppm or less.

First claim

The invention claimed is:

1. A lead-free and antimony-free solder alloy consisting of, by mass %:
16 to 23% of In,
0.001 to 0.08% of Ge, and
optionally, at least one of 3.5% or less of Ag, 0.7% or less of Cu, 0.05% or less of Ni, and 0.02% or less of Co,
with the balance being Sn and unavoidable impurities, and
wherein the solder alloy comprises an oxide film on its surface,
wherein a thickness of the oxide film is 7 nm or less as measured according to: in an XPS analysis chart, a depth in terms of SiO 2 at which a maximum detected intensity of O atom is defined as Do·max (nm), and a first depth in terms of SiO 2 at which a detected intensity of O atom is half of the maximum detected intensity in a portion deeper than Do·max is the thickness of the oxide film.

2. The lead-free and antimony-free solder alloy according to claim 1 , wherein, by mass %,
the alloy composition has an In content of 16 to 20%.

3. The lead-free and antimony-free solder alloy according to claim 1 , wherein, by mass %,
the alloy composition has a Ge content of 0.005 to 0.01%.

4. The lead-free and antimony-free solder alloy according to claim 1 , wherein, by mass %,
the alloy composition has a Ge content of 0.005 to 0.009%.

5. The lead-free and antimony-free solder alloy according to claim 1 , comprising U and Th as the unavoidable impurities each in an amount of 5 mass ppb or less, and As and Pb as the unavoidable impurities each in an amount of 5 mass ppm or less.

6. The lead-free and antimony-free solder alloy according to claim 1 , by mass %, further comprising at least one of 3.5% or less of Ag, 0.7% or less of Cu, 0.05% or less of Ni, and 0.02% or less of Co.

7. A solder ball comprising the lead-free and antimony-free solder alloy according to claim 1 .

8. The solder ball according to claim 7 , having an average diameter of 1 to 1,000 μm.

9. The solder ball according to claim 7 , having an average diameter of 1 to 100 μm.

10. The solder ball according to claim 7 , having a sphericity of 0.95 or more.

11. The solder ball according to claim 7 , having a sphericity of 0.99 or more.

12. A ball grid array formed by using the solder ball according to claim 7 .

13. A solder joint formed of the lead-free and antimony-free solder alloy according to claim 1 .

14. The lead-free and antimony-free solder alloy according to claim 2 , wherein, by mass,
the alloy composition has a Ge content of 0.005 to 0.01%.

15. The lead-free and antimony-free solder alloy according to claim 2 , wherein, by mass,
the alloy composition has a Ge content of 0.005 to 0.009%.

16. The lead-free and antimony-free solder alloy according to claim 2 , comprising U and Th as the unavoidable impurities each in an amount of 5 mass ppb or less, and As and Pb as the unavoidable impurities each in an amount of 5 mass ppm or less.

17. The lead-free and antimony-free solder alloy according to claim 3 , comprising U and Th as the unavoidable impurities each in an amount of 5 mass ppb or less, and As and Pb as the unavoidable impurities each in an amount of 5 mass ppm or less.

18. The lead-free and antimony-free solder alloy according to claim 4 , comprising U and Th as the unavoidable impurities each in an amount of 5 mass ppb or less, and As and Pb as the unavoidable impurities each in an amount of 5 mass ppm or less.

Assignees

• Senju Metal Industry Co

Inventors

• Saito Takashi
• Sudo Hiroki
• SUSA Mai

Classifications

• B23K35/0244

  Powders, particles or spheres; Preforms made therefrom · CPC title

• C22C13/00 Primary

  Alloys based on tin · CPC title

• B23K35/262 Primary

  Sn as the principal constituent · CPC title

• H05K3/34

  by soldering · CPC title

• H10W95/00

  Packaging processes not covered by the other groups of this subclass · CPC title