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Multiple reflows에 따른 Sn-Cu-xCr/Cu 접합계면의 금속간화합물 거동 및 기계적 특성 연구
유동열(Dong-Yurl Yu),손준혁(Junhyuk Son),고용호(Yong-Ho Ko),이창우(Chang-Woo Lee),방정환(Junghwan Bang) 대한용접·접합학회 2018 대한용접·접합학회지 Vol.36 No.2
In this study, a new lead-free solder, Sn-0.7Cu-0.2Cr (wt.%) alloy, was developed. The mother alloy of Sn-0.7Cu-0.2Cr solder, which has melting temperature of about 231℃, was fabricated and then made by 300 um solder balls. To evaluate the thermo-mechanical reliability of the new solder alloy for automobile electronics, multiple reflows test was performed. As a result of the microstructure analysis, grain size increased with increasing reflow test. And microstructure of Sn-3.0Ag-0.5Cu solder was finest. It was also confirmed that the microstructure of Sn-0.7Cu-0.2Cr solder was finer than Sn-0.7Cu solder by Cr addition. The IMC thickness results show that the presence of Cr in solder inhibits the growth of interfacial Cu6Sn5 layer and Cu3Sn layer. Specifically, the shear strength of the Sn-0.7Cu-0.2Cr/Cu solder joints increases by 9% and 22% than that of Sn-3.0Ag-0.5Cu and Sn-0.7Cu solder joints after 10 reflows test at 1m/s shear speed. And brittle fracture rate (%) of Sn-0.7Cu-0.2Cr was lower than Sn-3.0Ag-0.5Cu and Sn-0.7Cu solder after 10 reflows test at 1m/s shear speed.
다중 리플로우에 따른 Sn-Cu-(X)Al-(Y)Si/Cu 접합부 특성 연구
유동열(Dong-Yurl Yu),손준혁(Jun-Hyuk Son),고용호(Yong-Ho Ko),이창우(Chang-Woo Lee),변동진(Dongjin Byun),방정환(Junghwan Bang) 대한용접·접합학회 2020 대한용접·접합학회지 Vol.38 No.2
Joint properties of Sn-Cu-(X)Al-(Y)Si lead-free solder alloy were investigated for automotive electronics module. In this study, Sn-0.5Cu-(0.01, 0.03)Al-0.005Si(wt.%) alloys were then fabricated in the form of solder balls for reflow samples. To evaluation of solder joint properties, solder ball was attached to PCB finished with OSP Cu pad. The reflow process was performed for 40 s above 260.5 ℃. And solder joint was evaluated by repeating the reflow process up to 10 times. The melting temperatures of Sn-0.7Cu, 0.01 Al-0.005Si and 0.03Al-0.0.005Si were 227.5, 230.2 and 231.4 ℃, respectively. Initial microstructures are composed of β-Sn regions surrounded by eutectic networks with spherical Cu6Sn5 IMC particles. However, with the increasing Al content, refined eutectic β-Sn + Cu-Sn IMC networks were observed. The shear strength of Sn-0.5Cu-0.03Al-0.005Si solder joints was higher than Sn-0.5Cu-0.01Al-0.005Si and Sn-0.7Cu solder after 10 reflow test.
Jieun Yu,Myeonghwan Choi,Dong-Yurl Yu,Won Sik Hong,Cheolho Park,강남현 대한금속·재료학회 2023 ELECTRONIC MATERIALS LETTERS Vol.19 No.3
The predicted growth behavior of intermetallic compound (IMC) induced by electromigration of a Cu/organic solderabilitypreservative (OSP)/Sn-2.5Ag solder/electroless nickel electroless palladium immersion gold (ENEPIG)/Cu joint was calculatedfor a current density of 14 kA/cm 2 and current application time of 600 h and validated experimentally. Under as-refl owconditions, thin Cu 3 Sn and scallop-shaped Cu 6 Sn 5 layers were produced near the OSP interface, and a (Cu, Ni) 6 Sn 5 layer wasformed near the ENEPIG interface. Cu 6 Sn 5 islands and Ag 3 Sn with a β-Sn matrix were formed in the solder. The mobilitiesof Cu, Ni, and Sn atoms at the OSP and ENEPIG interfaces were calculated, and a relationship was found between IMCthickness and current application time. Under electron fl ow from the OSP to ENEPIG interface, the predicted total thickness(26.6 μm) of the IMCs (Cu 3 Sn, Cu 6 Sn 5 , and (Cu, Ni) 6 Sn 5 ), was in agreement with the experimental value (24.7 μm). With electron fl ow reversed, the predicted IMC thickness (14.2 μm) was similar to the experimental value (13.2 μm). Theapplication of current during electromigration only coarsened Cu 6 Sn 5 , regardless of the direction of electron fl ow. Finally,the Ni plating layer on the ENEPIG surface fi nish prevented the diff usion of Cu and suppressed electromigratory IMC growthby approximately 50%.
Baek Seungju,Yu Dong-Yurl,Son Jun-Hyuk,Bang Junghwan,Kim Jungsoo,Kim Min-Su,Lee Han-Bo-Ram,고용호 대한용접접합학회 2020 대한용접·접합학회지 Vol.38 No.4
In this study, we investigated the effect of plasma treatment for the surface of an insert bonding metal on the prop�erties of a transient liquid phase (TLP) bonding joint for a power module. Sn preforms, as the insert bonding metal for the TLP bonding, were used with and without Ar plasma treatment. To investigate the effect of Ar plasma treat�ment, the TLP bonding for two structures of Cu-finished Si chip/Sn preform/organic solderability preservative (OSP)-finished direct bond copper (DBC) substrate (Cu/Sn/Cu), and Ni-finished Si chip/Sn preform/Ni(P)-finished DBC substrate (Ni/Sn/Ni) was performed with 1 MPa at 300 ℃ and the bonding times were 10, 30, and 60 min, respectively. After the TLP bonding, we observed interfacial reactions and formations of intermetallic compounds (IMCs) under various bonding conditions. To evaluate mechanical properties, a shear test was also performed. Compared to the TLP bonding joint that used bare Sn preforms without Ar plasma treatment, growth of IMCs at the bonding joint that used Sn preforms with Ar plasma treatment occurred faster, and the IMCs could be formed through the entire joint despite the bonding time of 10 min. Meanwhile, by increasing the bonding time, Cu6Sn5 and Cu3Sn were formed at the Cu/Sn/Cu TLP bonding joint, whereas Ni3Sn4, Ni-Sn-P, and Ni3P were observed at the Ni/Sn/Ni joint. In the case of the Cu/Sn/Cu joint, we observed that increasing Cu3Sn formation while increasing the bonding time could be beneficial to the shear strength of the joint. Further, shear strengths of the joint were not sig�nificantly changed under the bonding conditions after Ni3Sn4, Ni-Sn-P, and Ni3P IMCs were formed at the entire joint of the Ni/Sn/Ni.
자동차 전장부품을 위한 Sn-0.5Cu-(X)Al(Si) 중온 솔더의 접합특성 연구
유동열,고용호,방정환,이창우,Yu, Dong-Yurl,Ko, Yong-Ho,Bang, Junghwan,Lee, Chang-Woo 대한용접접합학회 2015 대한용접·접합학회지 Vol.33 No.3
Joint properties of electric control unit (ECU) module using Sn-Cu-(X)Al(Si) lead-free solder alloy were investigated for automotive electronics module. In this study, Sn-0.5Cu-0.01Al(Si) and Sn-0.5Cu-0.03Al(Si) (wt.%) lead-free alloys were fabricated as bar type by doped various weight percentages (0.01 and 0.03 wt.%) of Al(Si) alloy to Sn-0.5Cu. After fabrications of lead-free alloys, the ball-type solder alloys with a diameter of 450 um were made by rolling and punching. The melting temperatures of 0.01Al(Si) and 0.03Al(Si) were 230.2 and $230.8^{\circ}C$, respectively. To evaluation of properties of solder joint, test printed circuit board (PCB) finished with organic solderability perseveration (OSP) on Cu pad. The ball-type solders were attached to test PCB with flux and reflowed for formation of solder joint. The maximum temperature of reflow was $260^{\circ}C$ for 50s above melting temperature. And then, we measured spreadability and shear strength of two Al(Si) solder materials compared to Sn-0.7Cu solder material used in industry. And also, microstructures in solder and intermetallic compounds (IMCs) were observed. Moreover, thickness and grain size of $Cu_6Sn_5$ IMC were measured and then compared with Sn-0.7Cu. With increasing the amounts of Al(Si), the $Cu_6Sn_5$ thickness was decreased. These results show the addition of Al(Si) could suppress IMC growth and improve the reliability of solder joint.