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Research on Bending Performance and Brazing Perform Ance of Copper Alloy Material Used for Lead Frame

Author: ZhangGuoJun
Tutor: SuJuanHua
School: Henan University of Science and Technology
Course: Materials Processing Engineering
Keywords: Lead frame materials Bending forming Performance Lead-free solder Aging Interface intermetallic Shear strength
CLC: TG146.11
Type: Master's thesis
Year: 2011
Downloads: 22
Quote: 0
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Abstract


Cu0.1Fe0.03P alloy, Cu3.2Ni0.75Si alloy, Cu0.36Cr0.03Zr alloy and Cu0.38 Cr0.17Sn0.16Zn are used as research materials in this paper. The numerical analysis method is used to study the bending forming performance of copper alloy for lead frame materials. The intermetallic organization morphology and growth dynamics of copper alloy substrate/lead-free solder interface intermetallic are discussesed.The shear performance and fracture morphology of Cu0.38Cr0.17Sn0.16Zn/SnAg3.0Cu0.5 brazing joints are researched.Tensile tests for the three kinds(Cu0.38Cr0.17Sn0.16Zn, Cu3.2Ni0.75Si, Cu0.1Fe 0.03P)of materials were performed to obtain the yield limit, ultimate strength and other parameters. The bending forming process and bending springback of copper alloys for lead frame materials were analyzed by Eta/Dynaform numerical analysis. The results show that the bending property of Cu0.38Cr0.17Sn0.16Zn alloy is the best, Cu0.1Fe0.03P alloy followed, Cu3.2Ni0.75Si alloy the worst. According to the simulation result, it is feasible to use the numerical analysis method to evaluate bending forming performance of copper alloy, so an effective method to evaluate bending forming performance of copper alloy is provided.Three kind of copper alloy for lead frame materials (Cu0.38Cr0.17Sn0.16Zn, Cu0.36Cr 0.03Z, Cu0.1Fe0.03P) with different composition and lead-free solder were used to do brazing experiment respectively. The microstructure of the interfaces between three different copper alloys for lead frame and SnAg3.0Cu0.5 solder were investigated by means of scanning electron microscope(SEM) equipped with energy dispersive X-ray spectroscopy. The growth dynamics model of interface intermetallic of copper alloy substrate/lead-free solder was briefly discussed. The results show that the interface microstructures between three different copper alloys for lead frame and SnAg3.0Cu0.5 solder are similar without aging. After aging at 160℃for 300h, the interface intermetallic compound between the copper alloys(Cu0.1Fe0.03P, Cu0.36Cr0.03Zr, Cu0.38Cr0.17Sn0.16Zn)and SnAg3.0Cu0.5 solder are Cu6Sn5 with 8.7μm, 7.4μm, 6.2μm in thickness, respectively. There is a small amount of Cu3Sn close to the copper alloys side. Cu0.38Cr0.17Sn0.16Zn alloy has better solder reliability than Cu0.1Fe0.03P alloy and Cu0.36Cr0.03Zr alloy. Finally, the influence of Zn elements in Cu0.38Cr0.17Sn0.16Zn alloy to growth speed of IMC on the interface is emphatically discussed, the addition of Zn elements could slow the growth speed of IMC in service condition in some extent, the solder welding reliability will reduce slowly. A certain amount of Zn element can be added to ensure the brazing performance improvement of copper alloy when a new kind of frame materials is developed.The microstructure and shear property of Cu0.38Cr0.17Sn0.16Zn/SnAgCu brazed joint under 160℃for different times of thermal exposure conditions were investigated by means of scanning electron microscope and universal material machine. The results show that with the increase of aging time, the brittle intermetallic and interface stress of the interface will increase continuously, the shear strength of soldered joint increases to a certain degree gradually and then decrease. The fracture place is inside the solder matrix at the initial stage of aging, the position of fracture gradually moves to interface after aging for 300h. The fracture type changes from ductile fracture to brittle fracture gradually.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > Metallic materials > Non - ferrous metals and their alloys > Heavy non - ferrous metals and their alloys > Copper
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