| 摘要 |
<p>A surface mounted electric part not requiring any additional facility investment on soldering and free from coming off a substrate even when the substrate is turned over and subjected to reflow. In a state that an electrical part is placed under a circuit board (100), the sum B of the periphery length of a second soldering portion (P2) is so set that the relationship between a downward rotation moment (M1) around a first soldering portion (P1) produced by the gravity and an upward rotation movement (M2) acting on a second soldering portion (P2) produced by the surface tension of solder melted during soldering using the overall heating method is M1 ‰ M2, and the sum A of the periphery length of the first soldering portion (P1) is so set that the relationship between a downward rotation movement (M3) around the second soldering portion (P2) produced by the gravity and an upward rotation movement (M4) acting on the first soldering portion (P1) produced by the surface tension is M3 ‰ M4.</p> |
