Title:
LEAD-FREE SOLDER MATERIAL
Document Type and Number:
WIPO Patent Application WO/2003/061897
Kind Code:
A1
Abstract:
A lead-free solder material, which is a Sn-Ag binary alloy comprising Al incorporated therein and thereby having a fine structure induced, through simultaneous and many engined crystal formation, by a coagulation accompanied with heterogeneous nucleation. A first embodiment, wherein 0.1 to 5 wt % of Ag is incorporated into an alloy containing 0.1 to 5 wt % of Al and the balanced amount of Sn; a second embodiment, which further contains 0.1 to 3 wt % of Cu, and 40 to 60 wt % of Bi or 40 to 50 wt % of In, in addition to the first embodiment; and a third embodiment which further contains, in addition to the first embodiment, 0.1 to 5 wt % of Cu and 0.1 to 5 wt % of one or more elements selected from among In, Bi, Ni, Au, Sb, Zn, Mg, La and Ce. In the structure of Fig 1 (a) according to the invention, it is observed that fine primary β-Sn crystals are formed and gaps between them are filled by a fine eutectic crystalline structure, whereas, in the structure of Fig 1 (b) or (c) of an comparative example containing no Al, rough primary β-Sn crystals account for the major part of the visual field. The lead-free solder material allows the formation of a fine primary β-Sn crystals, which results in the formation of a fine coagulated structure being independent of the cooling rate during implementation and the reduction in the amount of Ag used.
Inventors:
NARITA TOSHIO (JP)
TANAKA JUNICHI (JP)
KOBAYASHI TAIKI (JP)
TANAKA JUNICHI (JP)
KOBAYASHI TAIKI (JP)
Application Number:
PCT/JP2003/000470
Publication Date:
July 31, 2003
Filing Date:
January 21, 2003
Export Citation:
Assignee:
JAPAN SCIENCE & TECH CORP (JP)
NARITA TOSHIO (JP)
TANAKA JUNICHI (JP)
KOBAYASHI TAIKI (JP)
NARITA TOSHIO (JP)
TANAKA JUNICHI (JP)
KOBAYASHI TAIKI (JP)
International Classes:
B23K35/26; C22C12/00; C22C13/00; C22C13/02; H05K3/34; (IPC1-7): B23K35/26
Foreign References:
| JP2000141078A | 2000-05-23 | |||
| JPH11129091A | 1999-05-18 | |||
| JP2001347394A | 2001-12-18 | |||
| JP2001058287A | 2001-03-06 |
Other References:
TAIKAI KOBAYASHI ET AL.: "Biryo genso o tenka shita Sn-Ag gokin no gyoko soshiki", DAI 8 KAI ELECTRONICS NI OKERU MICRO SETSUGO JISSO GIJUTSU SYMPOSIUM RONBUNSHU, vol. 8, 31 January 2002 (2002-01-31), pages 209 - 214, XP002966325
Attorney, Agent or Firm:
Irimajiri, Takao (24 Shinjuku 1-chom, Shinjuku-ku Tokyo, JP)
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