Abstract: A printed circuit board includes a first substrate portion including a plurality of first insulating layers, a plurality of first wiring layers respectively disposed on the plurality of first insulating layers, and a plurality of first adhesive layers respectively disposed between the plurality of first insulating layers to respectively cover the plurality of first wiring layers; and a second substrate portion disposed on the first substrate portion, and including a plurality of second insulating layers, a plurality of second wiring layers respectively disposed on the plurality of second insulating layers, and a plurality of second adhesive layers respectively disposed between the plurality of second insulating layers to respectively cover the plurality of second wiring layers.

Abstract: An electrically operated screw-type jack comprising a support base, a housing, a jack body, a lifting ram being contained in the jack body, a servo motor being contained in the housing, reduction gears for transmitting the driving power of the servo motor to the lifting ram, a safety device for preveting the servo motor and the power transmitting mechanism including the reduction gears from an abrupt failure in overloading the jack, and a square head pin for hand operation of the jack when there is an overload on the jack. The reduction gears consist of first sun and planet gears, second sun and planet gears and a sun gear cylinder. The safety device consists of a clutch disk, a clutch spring and a sleeve. The present invention can provide an electrically operated screw-type jack which can promote the driving power of the servo motor, and prevent its power elements from an abrupt failure when there is an overload thereon.