Local control of underfill flow on high density packages, packages and systems made therewith, and methods of making same

Abstract

An article includes a mounting substrate, a passive component site on the mounting substrate, and an active component site on the mounting substrate. The article also includes a fluid flow barrier disposed local to the passive component site and spaced apart from the active component site. The fluid flow barrier can be a recess that resists fluid flow thereinto because of surface tension of the fluid when it meets-the recess edge. The fluid flow barrier can include a boundary that diverts fluid flow due to the angle of the recess edge as the fluid approaches it. An embodiment also includes a packaging system that includes the article and at least one passive component. An embodiment also includes a method of assembling the article or the packaging system.

1 - 20 . (canceled) 
   
   
       21 . A method comprising:
 forming an active component site and a passive component site in a substrate, wherein the active component site and the passive component site are spaced apart; and   forming a fluid flow barrier local to the passive component site and spaced apart from the active component site, the fluid flow barrier forming an obtuse angle directed against the active component site.   
   
   
       22 . The method of  claim 21 , further including:
 installing an active component at the active component site;   installing a passive component at the passive component site; and   forming an encapsulation structure contiguous the active component and extending away therefrom.   
   
   
       23 . The method of  claim 21 , wherein forming an encapsulation structure includes flowing encapsulation material under conditions that cause the encapsulation material to terminate at the fluid flow barrier. 
   
   
       24 . The method of  claim 21 , wherein forming an encapsulation structure includes flowing encapsulation material under conditions that cause the encapsulation material to terminate in a convex meniscus profile at the fluid flow barrier. 
   
   
       25 . The method of  claim 21 , wherein forming a fluid flow barrier local to the passive component site includes forming the fluid flow barrier perimeter to divert flow of the encapsulation material. 
   
   
       26 . The method of  claim 21 , wherein forming an encapsulation structure includes flowing encapsulation material under conditions that cause the encapsulation material to terminate in a convex meniscus profile at the fluid flow barrier, and wherein forming a fluid flow barrier local to the passive component site includes forming the fluid flow barrier perimeter to divert flow of the encapsulation material. 
   
   
       27 . The method of  claim 21 , wherein the passive component site and the active component site are disposed in a solder mask on the first side, wherein the fluid flow barrier is a trench in the solder mask, wherein the trench describes a perimeter around the passive component site, wherein the perimeter includes a trench side that is adjacent and spaced apart from the active component site, wherein the trench side that is adjacent and spaced apart from the active component site includes a boundary and wherein forming an encapsulation structure includes flowing encapsulation material under conditions that cause the encapsulation material to terminate at the fluid flow barrier. 
   
   
       28 . The method of  claim 21 , wherein the passive component site and the active component site are disposed in a solder mask on the first side, wherein the fluid flow barrier is a trench in the solder mask, wherein the trench describes a perimeter around the passive component site, wherein the perimeter includes a trench side that is adjacent and spaced apart from the active component site, wherein the trench side that is adjacent and spaced apart from the active component site includes a non-linear boundary, and wherein the non-linear boundary is selected from curvilinear, rectilinear, and combinations thereof, and wherein forming an encapsulation structure includes flowing encapsulation material under conditions that cause the encapsulation material to terminate at the fluid flow barrier, and wherein forming a fluid flow barrier local to the passive component site includes forming the fluid flow barrier perimeter to divert flow of the encapsulation material.