The invention relates to the field of integrated circuit chip carriers. Chip carriers provide an alternative method of packaging integrated circuit chips to the well-known dual in-line package (DIP).
Known forms of chip carrier consist of a usually rectangular base of ceramic material. A central area on the base is provided, on to which an integrated circuit chip or die is mounted and secured, for example using an epoxy resin adhesive. Leads are then connected between the appropriate points on the die to metal bonding pads provided on the carrier base. A preformed metallization pattern on the carrier base connects the bonding pads to terminal contacts formed around the periphery of the base. A metal or ceramic lid is then secured over the base so as to enclose and protect the die. The ceramic chip carrier is therafter mounted on a printed circuit board together with a series of other chip carriers and electronic components that go to form the complete circuit.
The use of ceramic material for the chip carrier is expensive and problems can also arise when the ceramic base is later bonded to a conventional epoxy/glass printed circuit board, due to the differential expansion between the two materials. In extreme environmental conditions the ceramic chip carrier can break away from the printed circuit board.