Abstract: An electrical connection structure is provided. The electrical connection structure includes a through hole, a first pad, a second pad and a conductive bridge. The through hole has a first end and a second end. The first pad at least partially surrounds the first end of the through hole and is electrically connected to a first circuit. The second pad is located at the second end of the through hole and is electrically connected to a second circuit. The conductive bridge is connected to the first pad and second pad through the through hole, thereby making the first and second circuits electrically connected to each other.

Abstract: A multispindle machining center includes a machine body, a knife rack, and a plurality of identical spindles. The knife rack has a knife rack body, a plurality of knife claws and a plurality of knife holders. The knife rack body has a plurality of accommodating troughs and accommodating trough openings connecting the accommodating troughs to the outside. The knife claw has a knife claw trough penetrating the top and bottom of the knife claw, and the knife claw opening connects the knife claw trough to the outside. The knife holder has a spindle connecting end and knife connecting end. The size and shape of the spindle connecting end is the same, while the size and shape of the knife connecting end vary. The outer periphery of the knife holder has a clipping portion which can be forced into the knife claw trough from the knife claw opening in a detachable way.

Abstract: A multispindle machining center includes a machine body, a knife rack, and a plurality of spindles. The knife rack has a knife rack body, a plurality of knife claws and a plurality of knife holders. The knife rack body has a plurality of accommodating troughs and accommodating trough openings connecting the accommodating troughs to the outside. The knife claw has a knife claw trough penetrating the top and bottom of the knife claw, and the knife claw opening connects the knife claw trough to the outside. The knife holder has a spindle connecting end and knife connecting end. The size and shape of the spindle connecting end is the same, while the size and shape of the knife connecting end vary. The outer periphery of the knife holder has a clipping portion which can be forced into the knife claw trough from the knife claw opening in a detachable way.