Patent ID: 8723538

Claim:
An assembly comprising: a lower guide plate comprising: a first plurality of through-holes therein; and a plurality of lifting holes penetrating through the lower guide plate; an upper guide plate over the lower guide plate, wherein the upper guide plate comprises a second plurality of through-holes therein; two spacers between the lower guide plate and the upper guide plate, wherein the two spacers are rotational spacers having a same thickness, and wherein the two spacers are configured to be rotated to be stacked, and rotated to be at a same level when rotated relative to each other to different positions; a plurality of probe pins, wherein each of the probe pins is inserted through one of the first plurality of through-holes and one of the second plurality of through-holes; and a plurality of probe pin stoppers, each attached to one of the probe pins, wherein the plurality of probe pin stoppers has lateral sizes greater than lateral sizes of the second plurality of through-holes, and wherein the plurality of probe pin stoppers is located over the upper guide plate.