Interface for electric interconnection and absorption of thermo-mechanical constraints, and method for its implementation, by use of an insulator substrate with feedthroughs and solder balls

摘要

The interface (A) between an electronic component or chip (1) whose inputs/outputs (8) are on its surface and can be soldered to another component (2) or element of type printed circuit board comprising reception pads (8) for soldering, is in the form of an electrically insulating substrate (3) which is flexible or rigid and whose coefficient of expansion is between that of the component (1) and the printed circuit board (2). The substrate (3) comprises unitary interconnection elements in the form of metallized feedthroughs (4) whose extremities (5, 6) can be soldered and are set up by interconnection balls (7). At least one of the extremities (5, 6) of the metallized feedthroughs (4) is extended to a reception pad (9) on which an interconnection ball (7) can be soldered. The method (claimed) for implementing the interface (claimed) consists of implementing metallized holes whose extremities are blocked up and solderable, and of soldering the interconnection balls to the extremities. The first interconnection balls are soldered by a refusion of solder paste to the first face of the substrate so to bring about a capillary rising of the solder alloy to the opposite face of the substrate, and the second interconnection balls are implemented of an alloy whose temperature of fusion is below that of the alloy for the balls on the first face of the substrate. For example, the alloy for the first balls is tin/silver or tin/indium whose temperature of fusion is about 220 deg C, and the alloy for the second balls is tin/lead whose temperature of fusion is 183 deg C.