DESIGN and LAYOUT
Physical design is based on your performance, size and cost requirements
The construction of leadframe packages such as QFP, LQFP, and TQFP consists of a single metal layer for die attach and wirebond lead tips, with epoxy encapsulation. Therefore the design process is straight-forward and the layout flow is from the diepad coordinates to the leadtips to package leads. Using standard JEDEC outlines is highly recommended to assure low cost in manufacturing, assembly and test fixturing.
LAMINATE AND BUILDUP SUBSTRATE
The construction of laminate/buildup substrate packages such as BGA, LGA, MCM, SIP, POP, etc. consists of multiple layers of metal and dielectric material with interconnect holes (vias) passing between each metal layer. The die can be attached using wirebond or flip chip technologies, and multiple die can be placed in a single package. Also, packages can be stacked (PoP) or embedded (PiP). Therefore the design process can be complex and varied to suit the need of the product. To optimize the interface between the package and top metal layer of the die, a co-design process flow is used. Experience and design analysis is needed to make the optimum trade-offs between cost and performance. Periodic design reviews with the customer may be needed during the design process.
Depending on the application, a package other than leadframe or laminate might be needed. Wafer level packaging (WLP), Chip on Board (COB), Chip on Flex (COF), ceramic small outline package (CSOP), and power quad flat pack with no leads (PWFN) are examples. Design flow depends upon the specific package and application requirements.
PSS can design a custom package for your device. We have experience in modifying standard package design and process flows for ultra-thin, multi-chip SiP, stacked and POP packaging.