Abstract: Introduced here are rotors that can be placed inside of microplate wells that include liquid samples. Each rotor can be comprised of a ferromagnetic material. Accordingly, when a rotor is subjected to an external rotational magnetic field, the rotor spins and agitates the liquid sample inside the corresponding well. The spin speed may be adjusted by changing the rotation speed, direction, and/or orientation of the external rotational magnetic field. The rotor typically includes a central cavity within which a probe can be suspended during the biochemical test.

Abstract: The invention discloses a printed circuit board compensation processing method for fabricating a BGA despite a small distance between a line and a pad of the BGA. The method includes compensating a pad and/or a line under a predetermined condition, and removing a portion of the pad facing the line by a second predetermined width when the shortest distance between the compensated line and pad is smaller than a first predetermined distance. The invention further discloses a device for performing the method and a PCB fabricated using the method.