A study of joint properties of Sn-Cu-(X)Al(Si) middle-temperature solder for automotive electronics modules |
Dong-Yurl Yu*, Yong-Ho Ko*, Junghwan Bang*, Chang-Woo Lee* |
Correspondence:
Chang-Woo Lee, Email: cwlee@kitech.re.kr |
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Abstract |
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℃, 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℃ 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 Cu6Sn5 IMC were measured and then compared with Sn-0.7Cu. With increasing the amounts of Al(Si), the Cu6Sn5 thickness was decreased. These results show the addition of Al(Si) could suppress IMC growth and improve the reliability of solder joint. |
Key Words:
Electric control unit (ECU), Lead-free solder, Al(Si), Intermetallic compound (IMC), Organic solderability perseveration (OSP) |
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