SOLDER ALLOY, SOLDER POWDER, SOLDER PASTE, AND A SOLDER JOINT USING THESE

Abstract

A solder alloy has an alloy composition of As: 25 mass ppm to 300 mass ppm, Bi: 0 mass ppm or more and 25000 mass ppm or less, and Pb: more than 0 mass ppm and 8000 mass ppm or less, with a balance being made up of Sn, the solder alloy satisfying Expression (1) and Expression (2) below,

275≤2As+Bi+Pb   (1)

0<2.3×10.sup.−4×Bi+8.2×10.sup.−4×Pb≤7   (2)

where in Expression (1) and Expression (2), As, Bi and Pb represent respectively contents (mass ppm) thereof in the alloy composition.

Claims

1. A solder alloy comprising an alloy composition of As: 25 mass ppm to 300 mass ppm, Bi: 0 mass ppm or more and 25000 mass ppm or less, and Pb: more than 0 mass ppm and 8000 mass ppm or less, with a balance being made up of Sn, the solder alloy satisfying Expression (1) and Expression (2) below,
275≤2As+Bi+Pb   (1)
0<2.3×10.sup.−4×Bi+8.2×10.sup.−4×Pb≤7   (2) where in Expression (1) and Expression (2), As, Bi and Pb represent respectively contents (mass ppm) thereof in the alloy composition.

2. The solder alloy according to claim 1, wherein the alloy composition further satisfies Expression (1a) below,
275≤2As+Bi+Pb≤25200   (1a) where in Expression (1a), As, Bi and Pb represent respectively contents (mass ppm) thereof in the alloy composition.

3. The solder alloy according to claim 1, wherein the alloy composition further satisfies Expression (1b) below,
275≤2As+Bi+Pb≤5300   (1b) where in Expression (1b), As, Bi and Pb represent respectively contents (mass ppm) thereof in the alloy composition.

4. The solder alloy according to claim 1, wherein the alloy composition further satisfies Expression (2a) below,
0.02≤2.3×10.sup.−4×Bi+8.2×10.sup.−4×Pb≤0.9   (2a) where in Expression (2a), Bi and Pb represent respectively contents (mass ppm) thereof in the alloy composition.

5. The solder alloy according to claim 1, wherein the alloy composition further comprises at least one from among Ag: 0 mass % to 4 mass % and Cu: 0 mass % to 0.9 mass %.

6. A solder powder comprising the solder alloy according to claim 1.

7. A solder paste comprising the solder powder according to claim 6.

8. The solder paste according to claim 7, further comprising a zirconium oxide powder.

9. The solder paste according to claim 8, comprising 0.05 mass % to 20.0 mass % of the zirconium oxide powder relative to a total mass of the solder paste.

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

Description

EXAMPLES

[0092] The present invention will be explained next by way of examples, but is not meant to be limited to the examples below.

[0093] A flux prepared with 42 parts by mass of a rosin, 35 parts by mass of a glycol-based solvent, 8 parts by mass of a thixotropic agent, 10 parts by mass of an organic acid, 2 parts by mass of an amine, 3 parts by mass of a halogen, plus respective solder powders containing the alloy compositions given Table 1 to Table 6 and having a size (particle size distribution) satisfying symbol 4 in the classification (Table 2) of powder size in JIS Z 3284-1:2014, were mixed, to produce respective solder pastes. The mass ratio of the flux and the respective solder powder is herein flux:solder powder=11:89. The change over time of the viscosity of each solder paste was measured. The liquidus temperature and solidus temperature of each solder powder was also measured. Wettability was evaluated using the solder paste immediately after having been produced. Details are as follows.

[0094] Change Over Time

[0095] The viscosity of each solder paste immediately after having been produced was measured at a rotational speed of 10 rpm, at 25° C., in the atmosphere, for 12 hours, using PCU-205 by Malcom Co., Ltd. The viscosity was evaluated as “0” (good), deemed to afford a sufficient thickening suppression effect, if the viscosity after 12 hours was 1.2 times or less the viscosity at a time where 30 minutes had elapsed from production of the solder paste, and was evaluated as “X” (poor) in a case where the viscosity after 12 hours exceeded the above 1.2 times.

[0096] ΔT

[0097] Herein a DSC measurement was carried out on each solder powder prior to mixing with the flux, using EXSTAR DSC 7020 by SII Nano Technology Inc., with a sample amount of about 30 mg, and a rate of temperature rise of 15° C./min, to obtain a solidus temperature and a liquidus temperature. The solidus temperature was subtracted from the obtained liquidus temperature, to yield ΔT. Herein ΔT was evaluated as “O” (good) in a case where ΔT was equal to or smaller than 10° C., and as “X” (poor) in a case where ΔT exceeded 10° C.

[0098] Wettability

[0099] Each solder paste immediately after being produced was printed on a Cu plate, was heated from 25° C. to 260° C. at a rate of temperature rise of 1° C./s in a N2 atmosphere in a reflow oven, and was then cooled down to room temperature. The appearance of the cooled solder bumps was observed using an optical microscope, to evaluate wettability. Instances of no observed unmelted solder powder were evaluated as “O” (good), while instances of observed unmelted solder powder were evaluated as “X” (poor).

[0100] Evaluation results are given in Table 1.

TABLE-US-00001 TABLE 1 Evaluation item Compre- Alloy composition (mass ppm) Expres- Expres- Change hensive Sn As Bi Pb sion (1) sion (2) over time ΔT Wettability evaluation Ref. Ex. 1 Bal 100  75  0  275 0.02 ◯ ◯ ◯ ◯ Ex. 2 Bal 100  0  75  275 0.06 ◯ ◯ ◯ ◯ Ex. 3 Bal 100  50  50  300 0.05 ◯ ◯ ◯ ◯ Ex. 4 Bal 300 300 300 1200 0.32 ◯ ◯ ◯ ◯ Ex. 5 Bal 200 250 250  900 0.26 ◯ ◯ ◯ ◯ Ex. 6 Bal 100 250 250  700 0.26 ◯ ◯ ◯ ◯ Ex. 7 Bal 200 600 850 1850 0.84 ◯ ◯ ◯ ◯ Ex. 8 Bal 200 500 500 1400 0.53 ◯ ◯ ◯ ◯ Ref. Ex. 9 Bal 200 1000   0 1400 0.23 ◯ ◯ ◯ ◯ Ex. 10 Bal 200  0 1000  1400 0.82 ◯ ◯ ◯ ◯ Ex. 11 Bal  25 350 1000  1400 0.90 ◯ ◯ ◯ ◯ Ex. 12 Bal 100  0 5100  5300 4.18 ◯ ◯ ◯ ◯ Ex. 13 Bal 100  0 8000  8200 6.56 ◯ ◯ ◯ ◯ Ref. Ex. 14 Bal 100 10000   0 10200  2.30 ◯ ◯ ◯ ◯ Ex. 15 Bal 100 10000  5000  15200  6.40 ◯ ◯ ◯ ◯ Ref. Ex. 16 Bal 100 25000   0 25200  5.75 ◯ ◯ ◯ ◯ Com. Ex. 1 Bal.  0 100 100  200 0.11 X ◯ ◯ X Com. Ex. 2 Bal  25  25  25  100 0.03 X ◯ ◯ X Com. Ex. 3 Bal 350  25  25  750 0.03 ◯ ◯ X X Com. Ex. 4 Bal 800 100 100 1800 0.11 ◯ ◯ X X Com. Ex. 5 Bal 100  0 10000  10200  8.20 ◯ X ◯ X Com. Ex. 6 Bal 100 20000  5000  25200  8.70 ◯ X ◯ X Com. Ex. 7 Bal 100 25000  25000  50200  26.25  ◯ X ◯ X Com. Ex. 8 Bal 100 50000   0 50200  11.50  ◯ X ◯ X Com. Ex. 9 Bal 100  0 50000  50200  41.00  ◯ X ◯ X Underlining denotes values outside the scope of the invention.

TABLE-US-00002 TABLE 2 Evaluation item Alloy composition (As, Bi, Pb: mass ppm, Compre- Cu: mass%) Expres- Expres- Change hensive Sn Cu As Bi Pb sion (1) sion (2) over time ΔT Wettability evaluation Ref. Ex. 17 Bal 0.7 100  75  0  275 0.02 ◯ ◯ ◯ ◯ Ex. 18 Bal 0.7 100  0  75  275 0.06 ◯ ◯ ◯ ◯ Ex. 19 Bal 0.7 100  50  50  300 0.05 ◯ ◯ ◯ ◯ Ex. 20 Bal 0.7 300 300 300 1200 0.32 ◯ ◯ ◯ ◯ Ex. 21 Bal 0.7 200 250 250  900 0.26 ◯ ◯ ◯ ◯ Ex. 22 Bal 0.7 100 250 250  700 0.26 ◯ ◯ ◯ ◯ Ex. 23 Bal 0.7 200 600 850 1850 0.84 ◯ ◯ ◯ ◯ Ex. 24 Bal 0.7 200 500 500 1400 0.53 ◯ ◯ ◯ ◯ Ref. Ex. 25 Bal 0.7 200 1000   0 1400 0.23 ◯ ◯ ◯ ◯ Ex. 26 Bal 0.7 200  0 1000  1400 0.82 ◯ ◯ ◯ ◯ Ex. 27 Bal 0.7  25 350 1000  1400 0.90 ◯ ◯ ◯ ◯ Ex. 28 Bal 0.7 100  0 5100  5300 4.18 ◯ ◯ ◯ ◯ Ex. 29 Bal 0.7 100  0 8000  8200 6.56 ◯ ◯ ◯ ◯ Ref. Ex. 30 Bal 0.7 100 10000   0 10200  2.30 ◯ ◯ ◯ ◯ Ex. 31 Bal 0.7 100 10000  5000  15200  6.40 ◯ ◯ ◯ ◯ Ref. Ex. 32 Bal 0.7 100 25000   0 25200  5.75 ◯ ◯ ◯ ◯ Com. Ex. 10 Bal. 0.7  0 100 100  200 0.11 X ◯ ◯ X Com. Ex. 11 Bal 0.7  25  25  25  100 0.03 X ◯ ◯ X Com. Ex. 12 Bal 0.7 350  25  25  750 0.03 ◯ ◯ X X Com. Ex. 13 Bal 0.7 800 100 100 1800 0.11 ◯ ◯ X X Com. Ex. 14 Bal 0.7 100  0 10000  10200  8.20 ◯ X ◯ X Com. Ex. 15 Bal 0.7 100 20000  5000  25200  8.70 ◯ X ◯ X Com. Ex. 16 Bal 0.7 100 25000  25000  50200  26.25  ◯ X ◯ X Com. Ex. 17 Bal 0.7 100 50000   0 50200  11.50  ◯ X ◯ X Com. Ex. 18 Bal 0.7 100  0 50000  50200  41.00  ◯ X ◯ X Underlining denotes values outside the scope of the invention.

TABLE-US-00003 TABLE 3 Evaluation item Alloy composition (As, Bi, Pb: mass ppm; Compre- Ag, Cu: mass%) Expres- Expres- Change hensive Sn Ag Cu As Bi Pb sion (1) sion (2) over time ΔT Wettability evaluation Ref. Ex. 33 Bal 1 0.5 100  75  0  275 0.02 ◯ ◯ ◯ ◯ Ex. 34 Bal 1 0.5 100  0  75  275 0.06 ◯ ◯ ◯ ◯ Ex. 35 Bal 1 0.5 100  50  50  300 0.05 ◯ ◯ ◯ ◯ Ex. 36 Bal 1 0.5 300 300 300 1200 0.32 ◯ ◯ ◯ ◯ Ex. 37 Bal 1 0.5 200 250 250  900 0.26 ◯ ◯ ◯ ◯ Ex. 38 Bal 1 0.5 100 250 250  700 0.26 ◯ ◯ ◯ ◯ Ex. 39 Bal 1 0.5 200 600 850 1850 0.84 ◯ ◯ ◯ ◯ Ex. 40 Bal 1 0.5 200 500 500 1400 0.53 ◯ ◯ ◯ ◯ Ref. Ex. 41 Bal 1 0.5 200 1000   0 1400 0.23 ◯ ◯ ◯ ◯ Ex. 42 Bal 1 0.5 200  0 1000  1400 0.82 ◯ ◯ ◯ ◯ Ex. 43 Bal 1 0.5  25 350 1000  1400 0.90 ◯ ◯ ◯ ◯ Ex. 44 Bal 1 0.5 100  0 5100  5300 4.18 ◯ ◯ ◯ ◯ Ex. 45 Bal 1 0.5 100  0 8000  8200 6.56 ◯ ◯ ◯ ◯ Ref. Ex. 46 Bal 1 0.5 100 10000   0 10200  2.30 ◯ ◯ ◯ ◯ Ex. 47 Bal 1 0.5 100 10000  5000  15200  6.40 ◯ ◯ ◯ ◯ Ref. Ex. 48 Bal 1 0.5 100 25000   0 25200  5.75 ◯ ◯ ◯ ◯ Com. Ex. 19 Bal. 1 0.5  0 100 100  200 0.11 X ◯ ◯ X Com. Ex. 20 Bal 1 0.5  25  25  25  100 0.03 X ◯ ◯ X Com. Ex. 21 Bal 1 0.5 350  25  25  750 0.03 ◯ ◯ X X Com. Ex. 22 Bal 1 0.5 800 100 100 1800 0.11 ◯ ◯ X X Com. Ex. 23 Bal 1 0.5 100  0 10000  10200  8.20 ◯ X ◯ X Com. Ex. 24 Bal 1 0.5 100 20000  5000  25200  8.70 ◯ X ◯ X Com. Ex. 25 Bal 1 0.5 100 25000  25000  50200  26.25  ◯ X ◯ X Com. Ex. 26 Bal 1 0.5 100 50000   0 50200  11.50  ◯ X ◯ X Com. Ex. 27 Bal 1 0.5 100  0 50000  50200  41.00  ◯ X ◯ X Underlining denotes values outside the scope of the invention.

TABLE-US-00004 TABLE 4 Evaluation item Alloy composition (As, Bi, Pb: mass ppm; Compre- Ag, Cu: mass%) Expres- Expres- Change hensive Sn Ag Cu As Bi Pb sion (1) sion (2) over time ΔT Wettability evaluation Ref. Ex. 49 Bal 2 0.5 100  75  0  275 0.02 ◯ ◯ ◯ ◯ Ex. 50 Bal 2 0.5 100  0  75  275 0.06 ◯ ◯ ◯ ◯ Ex. 51 Bal 2 0.5 100  50  50  300 0.05 ◯ ◯ ◯ ◯ Ex. 52 Bal 2 0.5 300 300 300 1200 0.32 ◯ ◯ ◯ ◯ Ex. 53 Bal 2 0.5 200 250 250  900 0.26 ◯ ◯ ◯ ◯ Ex. 54 Bal 2 0.5 100 250 250  700 0.26 ◯ ◯ ◯ ◯ Ex. 55 Bal 2 0.5 200 600 850 1850 0.84 ◯ ◯ ◯ ◯ Ex. 56 Bal 2 0.5 200 500 500 1400 0.53 ◯ ◯ ◯ ◯ Ref. Ex. 57 Bal 2 0.5 200 1000   0 1400 0.23 ◯ ◯ ◯ ◯ Ex. 58 Bal 2 0.5 200  0 1000  1400 0.82 ◯ ◯ ◯ ◯ Ex. 59 Bal 2 0.5  25 350 1000  1400 0.90 ◯ ◯ ◯ ◯ Ex. 60 Bal 2 0.5 100  0 5100  5300 4.18 ◯ ◯ ◯ ◯ Ex. 61 Bal 2 0.5 100  0 8000  8200 6.56 ◯ ◯ ◯ ◯ Ref. Ex. 62 Bal 2 0.5 100 10000   0 10200  2.30 ◯ ◯ ◯ ◯ Ex. 63 Bal 2 0.5 100 10000  5000  15200  6.40 ◯ ◯ ◯ ◯ Ref. Ex. 64 Bal 2 0.5 100 25000   0 25200  5.75 ◯ ◯ ◯ ◯ Com. Ex. 28 Bal. 2 0.5  0 100 100  200 0.11 X ◯ ◯ X Com. Ex. 29 Bal 2 0.5  25  25  25  100 0.03 X ◯ ◯ X Com. Ex. 30 Bal 2 0.5 350  25  25  750 0.03 ◯ ◯ X X Com. Ex. 31 Bal 2 0.5 800 100 100 1800 0.11 ◯ ◯ X X Com. Ex. 32 Bal 2 0.5 100  0 10000  10200  8.20 ◯ X ◯ X Com. Ex. 33 Bal 2 0.5 100 20000  5000  25200  8.70 ◯ X ◯ X Com. Ex. 34 Bal 2 0.5 100 25000  25000  50200  26.25  ◯ X ◯ X Com. Ex. 35 Bal 2 0.5 100 50000   0 50200  11.50  ◯ X ◯ X Com. Ex. 36 Bal 2 0.5 100  0 50000  50200  41.00  ◯ X ◯ X Underlining denotes values outside the scope of the invention.

TABLE-US-00005 TABLE 5 Evaluation item Alloy composition (As, Bi, Pb: mass ppm; Compre- Ag, Cu: mass%) Expres- Expres- Change hensive Sn Ag Cu As Bi Pb sion (1) sion (2) over time ΔT Wettability evaluation Ref. Ex. 65 Bal 3 0.5 100  75  0  275 0.02 ◯ ◯ ◯ ◯ Ex. 66 Bal 3 0.5 100  0  75  275 0.06 ◯ ◯ ◯ ◯ Ex. 67 Bal 3 0.5 100  50  50  300 0.05 ◯ ◯ ◯ ◯ Ex. 68 Bal 3 0.5 300 300 300 1200 0.32 ◯ ◯ ◯ ◯ Ex. 69 Bal 3 0.5 200 250 250  900 0.26 ◯ ◯ ◯ ◯ Ex. 70 Bal 3 0.5 100 250 250  700 0.26 ◯ ◯ ◯ ◯ Ex. 71 Bal 3 0.5 200 600 850 1850 0.84 ◯ ◯ ◯ ◯ Ex. 72 Bal 3 0.5 200 500 500 1400 0.53 ◯ ◯ ◯ ◯ Ref. Ex. 73 Bal 3 0.5 200 1000   0 1400 0.23 ◯ ◯ ◯ ◯ Ex. 74 Bal 3 0.5 200  0 1000  1400 0.82 ◯ ◯ ◯ ◯ Ex. 75 Bal 3 0.5  25 350 1000  1400 0.90 ◯ ◯ ◯ ◯ Ex. 76 Bal 3 0.5 100  0 5100  5300 4.18 ◯ ◯ ◯ ◯ Ex. 77 Bal 3 0.5 100  0 8000  8200 6.56 ◯ ◯ ◯ ◯ Ref. Ex. 78 Bal 3 0.5 100 10000   0 10200  2.30 ◯ ◯ ◯ ◯ Ex. 79 Bal 3 0.5 100 10000  5000  15200  6.40 ◯ ◯ ◯ ◯ Ref. Ex. 80 Bal 3 0.5 100 25000   0 25200  5.75 ◯ ◯ ◯ ◯ Com. Ex. 37 Bal. 3 0.5  0 100 100  200 0.11 X ◯ ◯ X Com. Ex. 38 Bal 3 0.5  25  25  25  100 0.03 X ◯ ◯ X Com. Ex. 39 Bal 3 0.5 350  25  25  750 0.03 ◯ ◯ X X Com. Ex. 40 Bal 3 0.5 800 100 100 1800 0.11 ◯ ◯ X X Com. Ex. 41 Bal 3 0.5 100  0 10000  10200  8.20 ◯ X ◯ X Com. Ex. 42 Bal 3 0.5 100 20000  5000  25200  8.70 ◯ X ◯ X Com. Ex. 43 Bal 3 0.5 100 25000  25000  50200  26.25  ◯ X ◯ X Com. Ex. 44 Bal 3 0.5 100 50000   0 50200  11.50  ◯ X ◯ X Com. Ex. 45 Bal 3 0.5 100  0 50000  50200  41.00  ◯ X ◯ X Underlining denotes values outside the scope of the invention.

TABLE-US-00006 TABLE 6 Evaluation item Alloy composition (As, Bi, Pb: mass ppm; Compre- Ag, Cu: mass%) Expres- Expres- Change hensive Sn Ag Cu As Bi Pb sion (1) sion (2) over time ΔT Wettability evaluation Ref. Ex. 81 Bal 3.5 0.5 100  75  0  275 0.02 ◯ ◯ ◯ ◯ Ex. 82 Bal 3.5 0.5 100  0  75  275 0.06 ◯ ◯ ◯ ◯ Ex. 83 Bal 3.5 0.5 100  50  50  300 0.05 ◯ ◯ ◯ ◯ Ex. 84 Bal 3.5 0.5 300 300 300 1200 0.32 ◯ ◯ ◯ ◯ Ex. 85 Bal 3.5 0.5 200 250 250  900 0.26 ◯ ◯ ◯ ◯ Ex. 86 Bal 3.5 0.5 100 250 250  700 0.26 ◯ ◯ ◯ ◯ Ex. 87 Bal 3.5 0.5 200 600 850 1850 0.84 ◯ ◯ ◯ ◯ Ex. 88 Bal 3.5 0.5 200 500 500 1400 0.53 ◯ ◯ ◯ ◯ Ref. Ex. 89 Bal 3.5 0.5 200 1000   0 1400 0.23 ◯ ◯ ◯ ◯ Ex. 90 Bal 3.5 0.5 200  0 1000  1400 0.82 ◯ ◯ ◯ ◯ Ex. 91 Bal 3.5 0.5  25 350 1000  1400 0.90 ◯ ◯ ◯ ◯ Ex. 92 Bal 3.5 0.5 100  0 5100  5300 4.18 ◯ ◯ ◯ ◯ Ex. 93 Bal 3.5 0.5 100  0 8000  8200 6.56 ◯ ◯ ◯ ◯ Ref. Ex. 94 Bal 3.5 0.5 100 10000   0 10200  2.30 ◯ ◯ ◯ ◯ Ex. 95 Bal 3.5 0.5 100 10000  5000  15200  6.40 ◯ ◯ ◯ ◯ Ref. Ex. 96 Bal 3.5 0.5 100 25000   0 25200  5.75 ◯ ◯ ◯ ◯ Com. Ex. 46 Bal. 3.5 0.5  0 100 100  200 0.11 X ◯ ◯ X Com. Ex. 47 Bal 3.5 0.5  25  25  25  100 0.03 X ◯ ◯ X Com. Ex. 48 Bal 3.5 0.5 350  25  25  750 0.03 ◯ ◯ X X Com. Ex. 49 Bal 3.5 0.5 800 100 100 1800 0.11 ◯ ◯ X X Com. Ex. 50 Bal 3.5 0.5 100  0 10000  10200  8.20 ◯ X ◯ X Com. Ex. 51 Bal 3.5 0.5 100 20000  5000  25200  8.70 ◯ X ◯ X Com. Ex. 52 Bal 3.5 0.5 100 25000  25000  50200  26.25  ◯ X ◯ X Com. Ex. 53 Bal 3.5 0.5 100 50000   0 50200  11.50  ◯ X ◯ X Com. Ex. 54 Bal 3.5 0.5 100  0 50000  50200  41.00  ◯ X ◯ X Underlining denotes values outside the scope of the invention.

[0101] Tables 1 to 6 reveal that all the alloy compositions in the examples satisfied all the requirements of the present invention, and therefore exhibited a thickening suppression effect, narrowing of ΔT, and excellent wettability.

[0102] By contrast, Comparative examples 1, 10, 19, 28, 37 and 46 did not contain As, and hence exhibited no thickening suppression effect.

[0103] In Comparative examples 2, 11, 20, 29, 38 and 47, Expression (1) was below the lower limit, and accordingly no thickening suppression effect was elicited.

[0104] In Comparative examples 3, 4, 12, 13, 21, 22, 30, 31, 39, 40, 48 and 49, the As content exceeded the upper limit, and accordingly wettability results were poor.

[0105] In Comparative examples 5, 7, 9, 14, 16, 18, 23, 25, 27, 32, 34, 36, 41, 43, 45, 50, 52 and 54, the Pb content and Expression (2) exceeded respective upper limits, and as a result ΔT exceeded 10° C.

[0106] In Comparative examples 6, 15, 24, 33, 42 and 51, Expression (2) exceeded the upper limit, and as a result ΔT exceeded 10° C.

[0107] In Comparative examples 8, 17, 26, 35, 44 and 53, the Bi content and

[0108] Expression (2) exceeded respective upper limits, and as a result ΔT exceeded 10° C.

[0109] Also, improvement of the thickening suppression effect could be observed in examples where 0.1% of zirconium oxide powder having a particle size of 1 μm was incorporated.