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Influence of cooling conditions on microstructure and mechanical property of Sn-0.3Ag-0.7Cu lead-free solder
(2021-01-01)
Jattakul, Prajak
;
Madsa, Tavee
;
Sunasuan, Piyawan
;
Mookam, Niwat
This research has investigated the influence of cooling conditions on the microstructure and mechanical properties i.e., tensile strength and microhardness of Sn-0.3Ag-0.7Cu lead-free solder. In the experiments, casting was performed at 300°C with comparison between copper and stainless steel molds under slow and fast cooled conditions. X-ray diffractometer confirmed the presence of Cu6Sn5 and Ag3Sn phases in the solder matrix. Lead-free solder solidified under slow cooled conditions exhibited β-Sn matrix with larger grain growth as compared to the fast cooled solder. The eutectic area of intermetallic compound (IMC) was found to increase with cooling rate. The tensile strength of slow cooled solder was greater than fast cooled solder for both molds. In addition, the microhardness of the solder was also influenced by cooling rate. The dimples size of facture surface was decreased by higher cooling rate. A greater eutectic area of the Cu6Sn5 and Ag3Sn phases of initial β-Sn matrix lead to lower values of the mechanical property from fast cooled conditions.
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Brazing of Porous Copper Foam with Copper Sheet Using CuNiSnP Amorphous Filler Metal
(2021-01-01)
Mookam, Niwat
;
Jattakul, Prajak
;
Rakphet, Tipsuda
;
Kanlayasiri, Kannachai
This research studies effects of the brazing time on interfacial microstructure of brazed joint between the porous copper foam (PCF) and Cu substrate using CuNiSnP amorphous filler metal. To examine the interfacial microstructure and its properties, an assessment of PCF/CuNiSnP/Cu brazed joints was conducted after electric furnace brazing under hydrogen (H2) atmosphere. The results showed that the interfacial microstructure was thick for short brazing time specimens and thin for prolonged brazing time specimens. The interfacial microstructures consisted of Cu-rich solid solution, (Cu, Ni)3P, and Cu3P as a eutectic structure discovered in the brazing region at different brazing times of 5, 10, and 20 min. Only the Cu-rich solid solution and (Cu, Ni)3P were found in the specimen with brazing time of 30 min. indicating that different brazing times affected interfacial microstructures and therefore reliability of the brazed joints.
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Effect of soldering condition on formation of intermetallic phases developed between Sn-0.3Ag-0.7Cu low-silver lead-free solder and Cu substrate
(2011-05-26)
Mookam, Niwat
;
Kanlayasiri, Kannachai
In this paper, effect of soldering time and temperature on formation of intermetallic compounds developed between Sn-0.3Ag-0.7Cu lead-free solder and copper substrate was investigated. Dip soldering was performed at 250, 270, and 290 °C with soldering time of 5, 10, 15, and 20 s. Either ε-Cu <inf>3</inf>Sn or η-Cu<inf>6</inf>Sn<inf>5</inf> intermetallic phase was found at the interface between the solder and the substrate depending on the soldering condition, i.e., soldering time and soldering temperature. ε-Cu<inf>3</inf>Sn was found only when the substrate was soldered at 250 °C for 5 and 10 s. At other soldering conditions, only η-Cu <inf>6</inf>Sn<inf>5</inf> was found at the interfacial zone. Crystal structure of ε-Cu<inf>3</inf>Sn intermetallic phase was orthorhombic, and it was hexagonal structure for η-Cu<inf>6</inf>Sn<inf>5</inf>. Transformation of the intermetallic phases was also discussed. © 2011 Elsevier B.V. All rights reserved.

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