Some embodiments provide a magnet gripper system, comprising: a gripper base comprising a magnetically attractive face; at least two slide plate retaining systems; and two or more slide plates wherein at least one of the slide plates is movably cooperated with each of the at least two slide plate retaining systems such that the slide plates are configured to move between a retracted position with the slide plates retracted relative to the face of the gripper base and an extended position with the slide plates extended relative to the face of the gripper base with an end of each of the slide plates being positioned further from the face of the gripper base when in the extended position than when the slide plates are in the retracted position.

Provided is a substrate holding unit that holds a pair of substrates that are aligned and layered, comprising a first holding member that holds one of the substrates; a plurality of members to be joined that are connected to the first holding member; a second holding member that holds the other of the substrates to face the one of the substrates; a plurality of joining members that exert an adhesion force on the members to be joined and are connected to the second holding member at positions corresponding to positions of the members to be joined; and an adhesion restricting section that restricts the adhesion force until the substrates are aligned.

Some embodiments provide a magnet gripper system, comprising: a gripper base comprising a magnetically attractive face; at least two slide plate retaining systems; and two or more slide plates wherein at least one of the slide plates is movably cooperated with each of the at least two slide plate retaining systems such that the slide plates are configured to move between a retracted position with the slide plates retracted relative to the face of the gripper base and an extended position with the slide plates extended relative to the face of the gripper base with an end of each of the slide plates being positioned further from the face of the gripper base when in the extended position than when the slide plates are in the retracted position.

Discussed is an assembly board including: a base portion; a plurality of assembly electrodes extending in one direction and disposed on the base portion at predetermined intervals; a dielectric layer stacked on the base portion to cover the plurality of assembly electrodes; and barrier ribs stacked on the dielectric layer and defining cells in which semiconductor light emitting diodes are seated at the predetermined intervals along an extending direction of the plurality of assembly electrodes so as to overlap a portion of the plurality of assembly electrodes, wherein the plurality of assembly electrodes include first electrodes and second electrodes disposed on different planes on the base portion, and wherein the first electrodes are disposed on one surface of the base portion, and the second electrodes are disposed on one surface of the dielectric layer.