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Study on Diode-laser Soldering Technology of QFP Devices

Author: ZhangZuo
Tutor: XueSongBai
School: Nanjing University of Aeronautics and Astronautics
Course: Materials Science
Keywords: Laser soldering Process parameters Mechanical properties Microstructure Thermal cycle test
CLC: TG454
Type: Master's thesis
Year: 2008
Downloads: 87
Quote: 0
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Abstract


As more and more small QFP lead width , as well as lead-free solder applications become more popular , the use of traditional infrared reflow soldering technology to connect more and more powerless . As an emerging brazing technology, semiconductor laser brazing can effectively avoid bridging defects , and to improve joint strength , thus expanding application areas . This paper studies the laser brazing process on the mechanical properties of solder QFP components were investigated . Select the Sn-Ag-Cu solder, soldering a semiconductor laser device system QFP100 brazing tests. The results showed that : selection Sn-Ag-Cu solder paste test laser output power of 38.3W, scanning speed of 2mm / s , the solder joints of good appearance , the most excellent mechanical properties , and a bridged without Weld even defects. Comparative Sn-Pb solder joints , Sn-Ag-Cu solder joints average tensile strength greater data stability, higher reliability. By changing the laser output power, with the microstructure of the variation of the laser output power . The results show that: with the laser output power increases , microstructure gradually optimized. When the laser output power of 38.3W , the solder joints homogeneous, fine grain size , while avoiding Cu6Sn5 intermetallic compounds within the solder joint overgrowth , the solder / substrate interface to form a thick enough layer of intermetallic compounds . At this point , the fracture has significant dimple fracture mode is ductile fracture . When the power is further increased , further growth of intermetallic compounds , resulting in uneven dimples size , even a kind of ray florets , contrast, solder joint fracture mode from ductile fracture to brittle fracture. QFP devices for laser brazing heat cycle test research, and the use of STR-1000 micro solder joint strength tester QFP micro- joints strength testing, research QFP100 device under different cycles variation of mechanical properties of solder joints . The results show that: with the increase of thermal cycles , QFP micro- joints tensile strength showed a clear downward trend , the solder joint fracture mode changes from ductile to brittle fracture . In this paper, a semiconductor laser device QFP lead-free soldering process conducted by the system , in-depth study of lead-free solder for the semiconductor laser application provides a theoretical basis and data support .

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Welding, metal cutting and metal bonding > Welding process > Brazing
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