Surface-mount technology (SMT) is a manner of constructing circuits with components that mount to the surface of a printed circuit board (PCB). Die packages are an example of a component used in SMT. A conventional die package includes a die connected to leads. The leads extend out from or are exposed within a die package body to provide for connecting the die package to the PCB. The die package body protects the die and is typically a plastic encapsulant material. Conventionally, a die package uses one type of lead. The leads may be lead-frame pins or a grid array leads. The number of pins in a die package is uniquely constrained when using only one type of lead arrangement.
Conventional lead-frame pins include leads extending from the perimeter of the die package. Dual in-line packages (DIP), ceramic DIPs (CDIP), plastic DIPs (PDIP), and thin small-outline packages (TSOP) are examples of packages with leads on only two edges of the perimeter. Quad flat packages (QFP), thin QFP (TQFP), low-profile QFP (LQFP), and plastic QFP (PQFP) are examples of packages with leads on all four edges of the perimeter. Using lead-frame pins in these configurations creates difficulties in achieving high pin counts. These difficulties arise from a fixed amount of space for pins and constraints on the size and spacing of the pins.
Grid array leads include pin grid array (PGA), a land grid array (LGA), or a ball grid array (BGA). Conventional grid array arrangements extend from or are exposed within a bottom surface of the die package. One challenge in grid array arrangements is the length of bond wires that connect leads to the die. Long bond wires induce difficulties with routing the bond wires back to the die. These routing difficulties result in manufacturing challenges.
Lead-frame arrangements may also include a metal exposed die pad on a bottom surface of the die package. Manufacturing leads into both the perimeter and the bottom surface of the die package is challenging. Conventional methods typically cut leads into the metal exposed die pad using a sawing isolation process. However, the sawing isolation process suffers from several manufacturing difficulties. The sawing isolation process uses a blade to isolate leads. Blade alignment difficulties arise with this method resulting in manufacturing waste. Other difficulties with the sawing isolation process include mold flash covering under body leads and residual copper dust remaining on the package after sawing. All of these difficulties increase the cost of manufacturing and are therefore undesirable.
The foregoing statements are not intended to constitute an admission that any patent, publication or other information referred to herein is prior art with respect to this disclosure. Rather, these statements serve to present a general discussion of technology and associated issues in the technology.
USPTO Backgrounds
USPTO Backgrounds