CREAM SOLDER AND METHOD OF SOLDERING ELECTRONIC PART

Title:

CREAM SOLDER AND METHOD OF SOLDERING ELECTRONIC PART

Document Type and Number:

WIPO Patent Application WO/2008/004531

Kind Code:

A2

Abstract:

A cream solder obtained by kneading an Sn-Ag-Cu alloy together with a flux, wherein the Sn-Ag-Cu alloy comprises a mixture of a first powdery alloy and a second powdery alloy, the first powdery alloy is represented by an Sn-Ag phase diagram having a solid-liquid coexistence region and has a given silver amount which is larger than that in the eutectic composition (3.5 wt.% silver), and the second powdery alloy has a silver amount which is that in the eutectic composition (3.5 wt.% silver) or which is close to that in the eutectic composition and is smaller than that in the first powdery alloy. This cream solder is excellent in strength and thermal stability and has satisfactory bonding properties. It is based on an inexpensive Sn-Ag-Cu solder alloy. It is suitable for use as a high-temperature-side lead-free solder material conformable to temperature gradation bonding. Also provided is a method of soldering an electronic part.

Inventors:

YAMASHITA MITSUO (JP)
GOTO TOMOAKI (JP)
ASAGI TAKESHI (JP)

Application Number:

PCT/JP2007/063267

Publication Date:

January 10, 2008

Filing Date:

July 03, 2007

Export Citation:

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Assignee:

FUJI ELECTRIC HOLDINGS (JP)
NIHON HANDA CO LTD (JP)
YAMASHITA MITSUO (JP)
GOTO TOMOAKI (JP)
ASAGI TAKESHI (JP)

International Classes:

B23K35/26; B23K1/00; C22C13/00; H05K3/34; B23K101/42

Domestic Patent References:

WO2005084877A1

2005-09-15

Foreign References:

JP2002126893A	2002-05-08
JPH1177366A	1999-03-23
JP2001504760A	2001-04-10
JP2002314241A	2002-10-25

Other References: