Semiconductor package having a grid array of pin-attached balls

Abstract

Semiconductor chip ( 1101 ) of a ball grid array device ( 1100 ) is mounted onto tape substrate ( 1102 ) using attach adhesive ( 1103 ). The metal layer on the top surface of substrate ( 1102 ) uses between about 30% to 90% of its area for connecting lines ( 1104 ), and only the remainder for members/rings ( 1105 ) and terminals ( 1106 ). Routing of differential pair signals and large numbers of signals on a single layer tape package are feasible. This embodiment creates an inexpensive high performance tape ball grid array package for chip-scale devices. Terminals ( 1106 ) serve the connection (by bonding wires or reflow bumps) to the chip contact pads. Inserted in members/rings ( 1105 ) are the conductive pins ( 1107 ), which serve as anchors for the solder bodies/balls ( 1108 ). Pins ( 1107 ) are substantially insensitive to the thermomechanical stresses, which occur in device ( 1100 ) during assembly, testing and operation.

1 . A method for fabricating a substrate for the assembly of semiconductor devices, comprising the steps of:
 providing a sheet-like base of insulating material, said base having first and second surfaces;   forming a plurality of connecting lines, conductive members, and terminals on said first surface so that selected lines interconnect conductive members and terminals; and   inserting a conductive pin, having a head on one end, in each of said members so that said pin penetrates through said base until it protrudes from said second surface and said pin head rests on said member.   
   
   
       2 . The method according to  claim 1  further comprising, before said step of inserting said pin, the step of heating said sheet-like base approximately to the temperature of the elastic limit of said material. 
   
   
       3 . The method according to  claim 1  wherein said insulating material is compliant. 
   
   
       4 . The method according to  claim 1  wherein said pins have a surface composition metallurgically suitable for solder attachment. 
   
   
       5 . A method for fabricating a semiconductor assembly, comprising the steps of:
 providing a sheet-like substrate of insulating material, said substrate having first and second surfaces and a plurality of connecting lines, conductive members, and terminals on said first surface, selected lines interconnecting conductive members and terminals;   inserting a conductive pin, having a head on one end and a surface composition metallurgically suitable for solder attachment, in each of said members so that said pin extends through said substrate and protrudes from said second surface and said head rests on one of said members;   providing an integrated circuit chip having contact pads;   connecting said pads to said terminals, respectively; and   attaching a separate body of solder material to each of said protruding pins.   
   
   
       6 . The method according to  claim 5  wherein wire bonding is employed for the step of connecting said contact pads to said terminals after said chip has been attached to said first substrate surface. 
   
   
       7 . The method according to  claim 5  wherein metallic bump bonding is employed for the step of connecting said contact pads to said terminals after said chip has been flipped. 
   
   
       8 . The method according to  claim 5  further comprising the step of encapsulating said chip and said first substrate surface. 
   
   
       9 . The method according to  claim 8  wherein said step of encapsulating comprises transfer molding. 
   
   
       10 . The method according to  claim 5  wherein said step of attaching solder material comprises the steps of:
 providing a plurality of bodies of solder material spaced to correspond one by one to said pins protruding from said second substrate surface;   applying thermal energy to reach the reflow temperature of said solder material so that each body forms an approximate sphere;   aligning said substrate and said spheres so that each pin is aligned with its corresponding solder sphere;   bringing said assembly and said plurality of solder spheres in a position to insert each protruded pin into its corresponding solder sphere, and to wet said solder on said pin surface; and   cooling said assembly and attached solder spheres to create reliable solder-to-substrate attachment.   
   
   
       11 . The method according to  claim 10  wherein said solder bodies are placed on a non-wettable carrier to be spaced and heated.