Engineering Change Method Not Requiring Pads
Original Publication Date: 1986-Sep-01
Included in the Prior Art Database: 2005-Mar-09
A method is described to use spare chip inputs/outputs and wiring on a chip interposer to perform the engineering change (EC) function in modules. The method does not require pads, does not require space around the chip for EC pads, and does not require changes to the multi- level ceramic (MLC) substrate. In the procedure developed to make an EC, the chip and its associated interposer are removed and a replacement interposer 1 (Fig. 1) is used which eliminates the C-4 connection 2 to the substrate 8. This makes it possible to delete the net 3 in the substrate. A printed line 4 on the top surface of the interposer is added to pick up the unused C-4 connection 5 on the chip 6. Its output is connected to a C-4 on the interposer which is connected to one of the EC channels 7 buried in the substrate.