Low-Temperature Soldering Technology for Environmental Burden Reduction あらまし Sn - Bi Sb.5 mass Sn-Sb Sn-Bi Sn-Bi4 4 PC Sn - Ag - Cu 4518 3 Sn-Bi-Sb Abstract Fujitsu has successfully developed a new lead-free solder alloy for low-temperature semiconductor packaging by introducing.5 mass% antimony to eutectic tin-bismuth solder. In this way, it has dramatically improved the solder s high strain rate ductility and drop impact resistance. It was found that in this solder, a fine-grain tin-antimony inter-metallic compound dispersed in the tin-bismuth major phase, thus giving the alloy a fine-grain structure. This would improve the mechanical properties of the eutectic tin-bismuth solder. In particular, the ductility and drop impact resistance were found to be four times those of tin-bismuth solder. This solder alloy s high tolerance to the drop impact made it possible to apply the alloy in mobile electronics such as cellular phones, notebook PCs and so on. Moreover, the low melting point of the alloy paved the way to realize low-temperature device packaging below 18. Using this solder, the energy consumption of a solder reflow furnace can be reduced by 3% compared with the conventional tin-silver-copper solder. This paper introduces the basic properties of the newly developed solder alloy, and its potential applications in electronic packaging. FUJITSU. 62, 6, p. 715-722 11, 211 715
まえがき 26 7RoHS Restriction of Hazardous Substances Sn - Pb 217 Sn-3 mass Ag -.5 masscu 12 Sn-Ag-Cu Sn-Pb 34 3 3 6 図 -1 5 Sn-Ag-Cu 2 3 4 139 Sn- Bi Sb Sn-Bi-Sb 低温接合へのアプローチ Sn-Ag-Cu SimPRESSO/RFL 46 - Sn-Pb 139 Sn-Bi AgSn-57 mass Bi-1 mass Ag MCM Multi-Chip Module 図 -2 7 W 2 1 2 Sn-37Pb Sn-3Ag-.5Cu 3 4 15 2 25-1 Fig.1-Relationship between soldering temperature and energy consumption of reflow furnace. 716 FUJITSU. 62, 6 11, 211
Multi-Chip Module LSI Sn-57Bi-1Ag Fujitsu GS89 System board -2 Sn-Bi Fig.2-Mainframe adopting Sn-Bi solder. Sn-Bi Bi Pb Sn-Bi 系はんだの課題 Sn-Bi Bi Sn-Bi Sn-Bi Ag 89 CSP Chip Size Package Bi Sn-Bi Sn-Bi 共晶はんだへの第三元素 (Sb) 添加 Sn-Bi Ag Sb Sb Ag Sn Sn Sn Sb Bi 1 Sn-Bi Ag Bi Sb Sb 添加による Sn-Bi 共晶はんだの延性改善 Sb Sn-Bi Sb 図 -3 Ag 図 -4.5 mass Sb.5 mass Sn-Bi 4 FUJITSU. 62, 6 11, 211 717
5 4 3 2 1 7 2. 1-3 /sec n 3 3.3 1-4 /sec 1 2 3 Sb mass 4 5-3Sb Sn-Bi Fig.3-Ductility of Sn-Bi solder under high and low strain rate improved by adding antimony. 5 4 3 2 1 25 2. 1-3 /sec n 3 3.3 1-4 /sec 1 2 3 4 5 Ag mass -4Ag Sn-Bi Fig.4-Ductility of Sn-Bi solder under high and low strain rate improved by adding silver. 3. mass Sb Sn-Bi -4 Ag Sb Sn-Bi 7 Ag 25 Sn-Bi-Sb 図 -5 SnBi Sb Sn-Bi-.5Sb Sb Sb 1. masssn-bi-1.sb EPMA Electron Probe Micro Analyzer 図 -6 Sb Sn Bi Sn Sn-Sb SbSnSb 11 SnSb Sn Bi 図 -7 Bi 57 masssb Sb.5 mass 141.6 Sn Sb 1 Sb SnSbSn 718 FUJITSU. 62, 6 11, 211
Sn Sn-Bi Sn-Bi-1.Sb Bi Sn-Bi-.1Sb Sn-Bi-3.Sb Sn-Bi-.5Sb Sn-Bi-5.Sb 1 µm -5 Sb Sn-Bi Fig.5-Eutectic microstructure of Sn-Bi-xSb solder. Bi Sn SnSb a 1 µm b Sb 1 µm -6 Sn-Bi-1.Sb Sb Fig.6-Microstructure and distribution of Sb observed for Sn-Bi-1.Sb by SEM and EPMA. SnSb Sb 1. mass Bi 5 massbi SnSb Sb SnSb Sb.5 mass -3.5 mass Sb Sn-Bi-Sb はんだの落下衝撃に対する信頼性 BGA Ball Grid Allay 18 図 -8 Sn-Ag-Cu45 図 -9 3 15 Sn-Bi Sn-Bi-Ag 5 Sn-Bi-Sb FUJITSU. 62, 6 11, 211 719
25 2 15 1 5 a b L L Bi Sn Bi 1 Sn Bi 2 Sn Bi 1 Bi 2 c Sn Bi 1 SnSb L SnSb L Bi SnSb Sn Bi 2 SnSb a b Sn Sb Bi 1 2 3 4 5 Sn-57Bi Sb mass a c b - SnSb -7 Sn-57Bi Sb Fig.7-Calculated (Sn-57Bi) 1-y -Sb y ternary phase diagram. a Sn-Bi 1 µm b Sn-Bi-Sb 1 µm -8 18Sn-BiSn-Bi-Sb Fig.8-Cross-sectional view of Sn-Bi and Sn-Bi-Sb solder at 18ºC. 15 Sb 5 Sn-Bi Sn-Bi-Ag Sn-Bi-Sb 4 Sn- Bi-Sb Sn-Bi-Sb むすび Sn-Bi.5 mass Sb Sn-Bi TV LCD PDP PC 72 FUJITSU. 62, 6 11, 211
5 a Sn-Bi b Sn-Bi-Ag c Sn-Bi-Sb 5 µm 1 8 6 4 2 Sn-Bi Sn-Bi-Ag Sn-Bi-Sb 2 µ 1 2 3 4-9 Fig.9-Changes in joint resistance as function of package drop test. 参考文献 1 -IC Vol.23 No.1 p.57-6 27 2 p.16-21 21 3 FUJITSU Vol.56 No.6 p.545-551 25 4 Vol.2 No.7 p.561-565 1999 5 T. Sakai et al. A new flip-chip bonding method using ultra-precision cutting of metal/adhesive layers Journal of Japan Institute of Electronics Packaging Vol.11 No.3 p.217-222 28 6 3 Matelial stage Vol.1 No.7 p.47-5 21 7 FUJITSU Vol.54 No.4 p.337-342 23 8 Sn-Bi Ag Vol.6 No.5 p.414-419 23 9 M. McCormack et al. Significantly Improved Mechanical Properties of Bi-Sn Solder Alloys by Ag- Doping Journal of Electronic Materials Vol.26 No.8 p.954-958 1997 1 M. Hansen et al. Constitution of Binary Alloys. Second edition McGraw-Hill Book Company New York p.332-334 1958 11 M. Hansen et al. Constitution of Binary Alloys. Second edition McGraw-Hill Book Company New York p.1175-1177 1958 FUJITSU. 62, 6 11, 211 721
著者紹介 作山誠樹 ( さくやませいき ) 岡本圭史郎 ( おかもとけいしろう ) 赤松俊也 ( あかまつとしや ) 722 FUJITSU. 62, 6 11, 211