Patent Application
20050230850
1). Field of the Invention
This invention relates to a microelectronic assembly and the manner according to which contacts and terminals can be connected for purposes of redistributing current.
2). Discussion of Related Art
Integrated circuits are often manufactured in and on semiconductor wafers. A wafer is subsequently “singulated” or “diced” into individual dies. Each die is then mounted to a package substrate for purposes of structural integrity and providing signals, power, and ground to and from an integrated circuit in the die. Wirebonding wires may connect contacts on the die to terminals on the substrate. The terminals on the substrate are, in turn, connected through vias and other conductors to solder balls on an opposing side of the substrate.
It is often also required to connect one of the terminals to a solder ball on an opposing side of the die. In order to accomplish such redistribution of signals, conductors are formed out of metal layers in the substrate. More metal layers allow for more flexibility in design and more connections that can be made between components located on opposing sides of the die. A large number of metal layers in the substrate, however, increases the overall cost of the substrate. There is thus a trade-off between flexibility in the redistribution and the cost of the microelectronic assembly.
The invention is described by way of examples with reference to the accompanying drawings, wherein:
A microelectronic assembly is provided, having redistribution conductors that are formed over a microelectronic die of the assembly instead of through a substrate to which the microelectronic die is mounted. A redistribution conductor is formed by a pair of contacts on the die and a conductive portion connecting the contacts to one another. A wirebonding wire is attached to each contact. One of the wirebonding wires may be used to connect to a terminal on the substrate, a terminal on another die, or to another contact on the same die.
Referring specifically to
Each one of the solder ball contacts 24 is also connected through a respective conductor 20 to one or more of the terminals 22A. The number of connections that can be made between the solder ball contacts 24 and the terminals 22A depends on the number of metal layers in the substrate 18; a larger number of metal layers allows for a larger number of connections. The number of metal layers in the substrate 18 should, however, be maintained as low as possible to reduce the cost of the substrate 18.
The die subassembly 14 includes a microelectronic die 25 and contacts 26 formed at an upper surface of the die 25. The die 25 includes a die substrate 28 and an integrated circuit 30 formed on the die substrate 28. The contacts 26 include functional contacts 26A that are connected to the integrated circuit 30. The integrated circuit 30 includes a multitude of transistors and other electronic components that are interconnected with one another. Signals, power, and ground can be provided through the functional contacts 26A to or from the electronic components of the integrated circuit 30.
The wirebonding wires 16 include functional wirebonding wires 16A. Each functional wirebonding wire 16A has one end portion attached to one of the functional terminals 22A, and an opposing end portion attached to one of the functional contacts 26A. The functional contacts 26A are connected through the respective functional wirebonding wires 16A and the respective functional contacts 26A to the integrated circuit 30.
Referring to
As illustrated in
Referring again to
Although only a single pair of re-routing terminals 22Bi and 22Bii is shown, it should be understood that there may be additional re-routing conductors that are similar to the re-routing conductor illustrated in
The package substrate subassembly 112 and the first die subassembly 114 are similar to the package substrate subassembly 12 and die subassembly 14 of
The first redistribution wirebonding wire 116Bi has opposing ends that are attached respectively to the first redistribution terminal 122Bi and to the first redistribution contact 126Bi. The redistribution conductor trace 134 has opposing ends connected to the redistribution contacts 126Bi and 126Bii. The redistribution conductor trace 134 runs over the integrated circuit of the first die subassembly 114, without communicating therewith. The second die subassembly 150 is placed over the redistribution conductor trace 134, with the redistribution contacts 126Bi and 126Bii on opposing sides and outside an area of the second die subassembly 150.
The second die subassembly 150 is located on the first die subassembly 114. The second die subassembly 150 includes a microelectronic die 152 and a plurality of terminals 154 formed on the die 152. The die 152 includes a die substrate 156 and an integrated circuit 158 formed on the die substrate 156. The terminals 154 and the first redistribution terminal 122Bi are formed along edges of the second die subassembly 150, and are in direct communication with the integrated circuit 158.
The second redistribution wirebonding wire 116Bii has opposing ends connected respectively to the second redistribution contact 126Bii, and the second redistribution terminal 122Bii.
It can thus be seen that the first redistribution terminal 122Bi on the left of the second die subassembly 150 is connected to the second redistribution terminal 122Bii without the need for re-routing any signals through a substrate of the package substrate subassembly 112. Further functional wirebonding wires 160 can be used to connect terminals 162 of the package substrate subassembly 112 directly to terminals 154 of the second die subassembly 150.
The package substrate subassembly 212 includes a substrate 218, solder ball contacts 224 on a lower side of the substrate 218, and terminals 222 on an upper surface of the substrate 218.
The die subassembly 214 includes a die 225 and plurality of contacts 226 on the die 224. The die 225 includes a die substrate and an integrated circuit formed on the die substrate.
The terminal 222A is connected through the redistribution wirebonding wire 272A to the contact 226A. The contact 226A is connected through the redistribution wirebonding wire 272B to the redistribution pad 270A. The redistribution pad 270A is connected through the wirebonding wire 272C to the contact 226B. The contact 226B is connected to the integrated circuit of the die subassembly 214. Similarly, a redistribution conductor is formed by the redistribution terminal 222B, redistribution wirebonding wire 272D, redistribution contact 226C, redistribution wirebonding wire 272E, redistribution pad 270B, redistribution wirebonding wire 272F, and contact 226D.
It can thus be seen that two redistribution conductors are formed, each with a respective redistribution pad 272. The redistribution pads 272 allow for more flexibility in design of redistribution conductors.
While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative and not restrictive of the current invention, and that this invention is not restricted to the specific constructions and arrangements shown and described since modifications may occur to those ordinarily skilled in the art.
