Integrated circuits have been manufactured for many years. Manufacturing integrated circuits involves integrating various active and passive circuit elements into a piece of semiconductor material, referred to as a die. The die is attached to a package substrate to form a package. Currently, the size of packages is trending to smaller sizes due to application and cost. In some instances, a number of dies are attached to a single package substrate. When a number of dies are attached to a single substrate, the dies are stacked.
There are many categories of dies. Two of the many categories include flip chip ball grid array dies (FCBGA) and plastic ball grid array dies (PBGA). FCBGA dies include a series of solder balls that attach directly to corresponding pads on a substrate. PBGA dies include wires that are wire bonded to pads on a substrate. The solder balls form a reliable connection to a first type of pad, while the wires attach to form a reliable connection to a second and very different type of pad. Therefore, when a stack of dies are formed, typically one category of dies is typically used in the stack. Using two types of dies stacked in a single package would compromise the reliability of the finished package since one of either the solder balls or the wires would have a less than reliable bond with a package substrate. Typically, two substrates would be used rather than compromise reliability. This requires additional packages on a printed circuit board in an electronic device.
The description set out herein illustrates various embodiments of the invention, and such description is not intended to be construed as limiting in any manner.
USPTO Backgrounds
USPTO Backgrounds