CHIP TRANSFER METHOD AND APPARATUS

In a chip transferring apparatus a wafer (44) and a lead frame (50) are positioned. A first chip (42) is picked up from the wafer (44) by a transfer head (14; 40a-40d) in a chip pick-up position, while bonding a second chip to the lead frame (50) by another transfer head in a chip bonding position. The first chip (42) is then transferred by said one of the transfer heads from the chip pick-up position to the chip bonding position. Next, the first chip (42) is bonded on the lead frame (50) by said one of the transfer heads (14; 40a-40d) in the chip bonding position, while another one of the transfer heads picks up a third chip from the wafer (44) in the chip pick-up position. Each transfer head (14; 40a-40d) comprises a collet (66a-66d) which, through a mechanical coupling, is coupled to another collet for compensating radial forces exerted on the collet relative to said axis of rotation. Vacuum is transferred to the collet from a stationary pressure source by groove sections (106) in a transfer assembly stator (100) communicating through a gap (104) between the rotatable transfer assembly (32) and the transfer assembly stator (100) with gas ducts in the transfer head (14; 40a-40d) and the corresponding collet (66a-66d). A chip (42) is picked up from a wafer (44) by a needle mechanism (224).