Patent ID: 8697492
Filing Date: 2014-04-15
Classification: H01L

Abstract:
1. A method for making a microelectronic assembly, comprising: providing a microelectronic element having a first surface and first conductive elements projecting above the first surface, and a dielectric element having a second surface and second conductive elements projecting above the second surface, at least some of the first conductive elements or at least some of the second conductive elements being substantially rigid conductive posts, and the other of the first or second conductive elements including a bond metal juxtaposed with the at least some conductive posts, the posts having a height above the respective surface from which the posts project, and an underfill layer overlying at least some of the first conductive elements or at least some of the second conductive elements, the posts including tips having coplanar surfaces; moving at least one of the first conductive elements towards the other of the second conductive elements such that the tips of the substantially rigid posts pierce the underfill layer and at least deform the bond metal; and heating the microelectronic element and the dielectric element to a joining temperature until the bond metal flows along edges of the posts to contact the edges along at least one half the height of the posts and electrically joins the microelectronic element with the dielectric element, wherein the height of the posts above the surface from which they project is at least forty percent of a distance between the first and second surfaces, and wherein prior to the step of deforming the bond metal, trace amounts of the underfill layer are pushed into the bond metal by the conductive posts.