The laser provides a controllable means of supplying localized energy for solder joint formation and is a valuable tool in electronics manufacture.Diode laser soldering for fine pitch QFP devices were carried out with...The laser provides a controllable means of supplying localized energy for solder joint formation and is a valuable tool in electronics manufacture.Diode laser soldering for fine pitch QFP devices were carried out with Sn-Ag-Cu lead-free solder and Sn-Pb solder respectively,and the mechanical properties of micro-joints of the QFP devices were tested and studied by STR-1000 micro-joints tester.The results indicate that sound QFP micro-joints without bridging or solder ball are gained by means of diode laser soldering method with appropriate laser processing parameters,and the pitch of the QFP devices is as fine as to 0.4mm.Tensile strength of QFP micro-joints increases gradually with the increase of laser output power,the maximum tensile strength presents when the laser output power increase to a certain value.The results also indicate that the mechanical properties of QFP micro-joints soldered by diode laser soldering system are better than those of QFP micro-joints soldered by IR reflow soldering method.The experimental results may provide a theory guide for investigation of diode laser soldering.展开更多
Formation of AuSnx intermetallic compounds （IMCs） in laser reflowed solder joints was investigated. The results showed that few IMCs formed at the solder/0. 1μm Au interface. Needlelike AuSn4 IMCs were observed at ...Formation of AuSnx intermetallic compounds （IMCs） in laser reflowed solder joints was investigated. The results showed that few IMCs formed at the solder/0. 1μm Au interface. Needlelike AuSn4 IMCs were observed at the solder/0.5μm Au interface. In Sn-2.0Ag-O,75Cu-3,0Bi and Sn-3.5Ag-O.75Cu solder joints, when the laser input energy was increased, AuSn4 IMCs changed .from a layer to needlelike or dendritic distribution at the solder/0.9μm Au interface. As for the solder joints with 4.0 μm thickness of Au surface finish on pads, AuSn4 , AuSnx, AuSn IMCs, and Au2Sn phases formed at the interface. Moreover, the content of AuSnx IMCs, such as, AuSn4 and AuSn2, which contained high Sn concentration, would become larger as the laser input energy increased. In the Sn-37Pb solder joints with 0.9 μm or 4.0 μm thickness of the Au surface finish on pads, AuSn4 IMCs were in netlike distribution. The interspaces between them were filled with Pb-rich phases.展开更多
基金supported by Nanjing University of Aeronautics and Astronautics Doctoral Dissertation Innovation and Excellence Producing Foundation of China (Grant No. BCXJ09-07)Jiangsu Provincial General Colleges and Universities Postgraduate Scientific Research Innovative Plan of China (Grant No. CX09B_074Z)the Six Kind Skilled Personnel Project of Jiangsu Province of China(Grant No. 06-E-020)
文摘The laser provides a controllable means of supplying localized energy for solder joint formation and is a valuable tool in electronics manufacture.Diode laser soldering for fine pitch QFP devices were carried out with Sn-Ag-Cu lead-free solder and Sn-Pb solder respectively,and the mechanical properties of micro-joints of the QFP devices were tested and studied by STR-1000 micro-joints tester.The results indicate that sound QFP micro-joints without bridging or solder ball are gained by means of diode laser soldering method with appropriate laser processing parameters,and the pitch of the QFP devices is as fine as to 0.4mm.Tensile strength of QFP micro-joints increases gradually with the increase of laser output power,the maximum tensile strength presents when the laser output power increase to a certain value.The results also indicate that the mechanical properties of QFP micro-joints soldered by diode laser soldering system are better than those of QFP micro-joints soldered by IR reflow soldering method.The experimental results may provide a theory guide for investigation of diode laser soldering.
基金This study was financially supported by National Natural Science Foundation of China （No.50675047）.
文摘Formation of AuSnx intermetallic compounds （IMCs） in laser reflowed solder joints was investigated. The results showed that few IMCs formed at the solder/0. 1μm Au interface. Needlelike AuSn4 IMCs were observed at the solder/0.5μm Au interface. In Sn-2.0Ag-O,75Cu-3,0Bi and Sn-3.5Ag-O.75Cu solder joints, when the laser input energy was increased, AuSn4 IMCs changed .from a layer to needlelike or dendritic distribution at the solder/0.9μm Au interface. As for the solder joints with 4.0 μm thickness of Au surface finish on pads, AuSn4 , AuSnx, AuSn IMCs, and Au2Sn phases formed at the interface. Moreover, the content of AuSnx IMCs, such as, AuSn4 and AuSn2, which contained high Sn concentration, would become larger as the laser input energy increased. In the Sn-37Pb solder joints with 0.9 μm or 4.0 μm thickness of the Au surface finish on pads, AuSn4 IMCs were in netlike distribution. The interspaces between them were filled with Pb-rich phases.
