Flip chip interconnection with double post

Abstract

A method of assembling a packaged microelectronic element is disclosed that includes the steps of providing a microelectronic element having a plurality of conductive posts extending away from a first surface of a microelectronic element, the posts having top surfaces and edge surfaces extending abruptly away from the top surfaces, and a fusible metal cap attached to an end of each of the plurality of posts; at least substantially aligning the posts of the microelectronic element with a plurality of conductive posts extending from a first surface of a substrate, the posts of the substrate having top surfaces and edge surfaces extending abruptly away from the top surfaces; and joining the posts of the microelectronic element with the posts of the substrate.

1 - 15 . (canceled) 
     
     
         16 . A method of assembling a packaged microelectronic element comprising:
 providing a microelectronic element having a plurality of conductive posts extending away from a first surface of a microelectronic element, the posts having top surfaces and edge surfaces extending abruptly away from the top surfaces, and a fusible metal cap attached to an end of each of the posts;   at least substantially aligning the posts of the microelectronic element with a plurality of conductive posts extending from a first surface of a substrate, the posts of the substrate having top surfaces and edge surfaces extending abruptly away from the top surfaces; and   joining the posts of the microelectronic element with the posts of the substrate.   
     
     
         17 . The method of  claim 16 , wherein the step of joining the posts includes heating the fusible metal cap to a melting temperature, wherein fusible metal in the fusible metal cap flows onto exposed portions of the edge surfaces of the posts. 
     
     
         18 . The method of assembling of  claim 16 , wherein a passivation layer and an underbump metallization layer are deposited over the microelectronic element. 
     
     
         19 . The method of  claim 17 , wherein the posts extending from the first surface of the substrate include a base, and wherein when the fusible metal flows onto the exposed portions of the edge surfaces of the posts, and at least second portions of the solid metal posts remain exposed. 
     
     
         20 . The method of  claim 19 , wherein the step of joining includes heating the fusible metal caps attached to the posts extending from the substrate and the posts extending from the microelectronic element to a melting temperature, wherein the fusible metal flows onto exposed portions of the edge surfaces of the posts of the substrate and microelectronic element, such that the fusible metal does not contact one or both of the first surface of the microelectronic element or the first surface of the substrate. 
     
     
         21 . The method of  claim 17 , further comprising providing a predetermined amount of the fusible metal in the fusible metal cap that is sufficient to flow only onto exposed portions of the edge surfaces of the posts of the substrate and microelectronic element. 
     
     
         22 . The packaged microelectronic element of  claim 16 , wherein at least portions of the posts of the microelectronic element remain exposed when the posts of the substrate are joined to the posts of the microelectronic element. 
     
     
         23 . The method of  claim 16 , wherein the step of joining further includes maintaining a minimum distance between the front surface of the microelectronic element and the top surface of the substrate. 
     
     
         24 . The packaged microelectronic element of  claim 23 , further comprising structure adapted to maintain a minimum distance between the front surface of the microelectronic element and the top surface of the substrate. 
     
     
         25 . The method of  claim 16 , wherein the fusible metal cap is a first fusible metal cap and a second fusible metal cap is attached to an end of each of the posts extending from the first surface of the substrate. 
     
     
         26 . The method of  claim 17 , wherein the fusible metal does not contact both the first surface of the microelectronic element and the first surface of the substrate. 
     
     
         27 . The method of  claim 26 , wherein the step of joining the posts of the microelectronic element with the posts of the substrate electrically connects terminals exposed at an opposed second surface of the substrate with the posts of the microelectronic element. 
     
     
         28 . The method of  claim 27 , wherein the step of providing posts extending away from the first surface of the microelectronic element and posts extending away from a first surface of the substrate comprises providing etched solid metal posts extending away from the first surface of the microelectronic element and etched solid metal posts extending away from a first surface of the substrate. 
     
     
         29 . A method of assembling a packaged microelectronic element comprising:
 providing a microelectronic element having a plurality of solid metal conductive posts extending away from a first surface of a microelectronic element, the posts having top surfaces and edge surfaces extending away from the top surfaces;   at least substantially aligning the posts of the microelectronic element with a plurality of solid metal conductive posts extending from a first surface of a substrate, the posts extending from the first surface of the substrate having top surfaces and edge surfaces extending away from the top surfaces, and   joining the posts of the microelectronic element with the posts of the substrate using a fusible metal therebetween.   
     
     
         30 . The method of  claim 29 , wherein the step of joining the posts of the microelectronic element with the posts of the substrate electrically connects terminals exposed at an opposed second surface of the substrate with the posts of the microelectronic element. 
     
     
         31 . The method of  claim 29 , wherein the conductive posts are etched posts. 
     
     
         32 . The method of  claim 29 , wherein the posts extending from the first surface of the substrate include a base, and wherein when the fusible metal flows onto the exposed portions of the edge surfaces of the plurality of the posts extending from the first surface of the substrate, and at least second portions of the posts extending from the first surface of the substrate remain exposed. 
     
     
         33 . The method of  claim 29 , wherein the step of joining includes heating the fusible metal to a melting temperature, wherein the fusible metal flows onto exposed portions of the edge surfaces of the posts of the substrate and the posts of the microelectronic element, such that the fusible metal does not contact both the first surface of the microelectronic element and the first surface of the substrate. 
     
     
         34 . The method of  claim 33 , wherein the fusible metal does not contact both the first surface of the microelectronic element and the first surface of the substrate. 
     
     
         35 . The method of  claim 29 , wherein the posts of the substrate and the microelectronic element are wettable by solder.