An electronic subassembly comprises a printed circuit board and an electronic module, particularly a ceramic module, electrically connected to one another through a planar interposer. The interposer comprises an insulator sheet and electrical spring elements joining contact sites on the module with contact pads on the PCB. The invention includes modifications that improve the integrity of electrical connections between the printed circuit board and the electronic module. This is achieved by compensating for non-planarity between the surfaces of the interposer and the module, particularly resulting from a convex curvature of the module, by minimizing relative movement, such as rocking in the x-z and y-z planes. It also includes modifications to the suspension of the module within the interposer housing to reduce the effects caused by any sliding that may occur between the interposer and the module in the x-y plane.