Effect of small Sn-Ag-Cu additions on structure and properties of Sn-Zn-Bi solder/BGA during as-soldered and as-aged conditions

Author

Gain, A.K. ; Chan, Y.C. ; Sharif, Ahmed ; Yung, Winco K. C.

Author_Institution

Dept. of Electron. Eng., City Univ. of Hong Kong, Kowloon

fYear

2009

fDate

26-29 May 2009

Firstpage

1021

Lastpage

1026

Abstract

Sn-8Zn-3Bi solder balls with different weight percentages of Sn-Ag-Cu addition were bonded to Au/Ni metallized Cu pads, and the effect of multiple reflow and aging on impact reliability was investigated. In the Sn-Ag-Cu content Sn-Zn-Bi solder joints, the AgZn₃ intermetallic compound layer was clearly observed at the interfaces and its thickness increased with an increase the number of reflow cycles and aging time. In the solder ball region, fine acicular-shaped Zn-rich phase and spherical-shaped AgZn₃ compound particles were found in szlig-Sn matrix. The shear strength of monolithic Sn-Zn-Bi and 7 wt% Sn-Ag-Cu content Sn-Zn-Bi solder joints after one reflow cycle were about 44.5 MPa and 53.1 MPa, respectively while their shear strengths after eight reflow cycles were about 43.4 MPa and 51.6 MPa, respectively. The fracture surface of monolithic Sn-Zn-Bi solder exhibited a semi ductile fracture mode with a smooth surface while Sn-Zn-Bi solder joints containing Sn-Ag-Cu particles showed a typical ductile failure with very rough dimpled surfaces.

Keywords

ageing; ball grid arrays; bismuth alloys; copper alloys; ductile fracture; fracture toughness; gold alloys; metallisation; nickel alloys; reflow soldering; reliability; shear strength; silver alloys; solders; tin alloys; zinc alloys; Au-Cu; BGA; Ni-Cu; SnAgCuSnZnBi; aging; gold metallized copper pad; intermetallic compound layer; monolithic solder fracture surface; multiple reflow effect; nickel metallized copper pad; pressure 43.4 MPa; pressure 44.5 MPa; pressure 51.6 MPa; pressure 53.1 MPa; rough dimpled surface; semi ductile fracture mode; shear strength; solder ball; solder joint reliability; Electronics industry; Electronics packaging; Environmentally friendly manufacturing techniques; Lead; Microelectronics; Oxidation; Rough surfaces; Soldering; Surface cracks; Surface roughness;

fLanguage

English

Publisher

ieee

Conference_Titel

Electronic Components and Technology Conference, 2009. ECTC 2009. 59th

Conference_Location

San Diego, CA

ISSN

0569-5503

Print_ISBN

978-1-4244-4475-5

Electronic_ISBN

0569-5503

Type

conf

DOI

10.1109/ECTC.2009.5074137

Filename

5074137