LFXP20E-3FN256C Lattice, LFXP20E-3FN256C Datasheet - Page 389

• Manufacturer Part Number: LFXP20E-3FN256C
• Description: IC FPGA 19.7KLUTS 188I/O 256-BGA
• Manufacturer: Lattice

Specifications of LFXP20E-3FN256C

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

PCB Layout Recommendations
Lattice Semiconductor
for BGA Packages
Stack-up types, ordered by cost, high-to-low include:
• High-Density Interconnect (HDI) build up with micro vias
• Laminated with blind and buried vias
• Laminated with through vias
Figure 14-12. Stack-up Example
HDI is a “sandwich” with older-style larger geometry in the middle with fully drilled through holes and then a stack
of fine geometry of blind, buried or mixed via, laminated both on the top and bottom of the middle stack-up. The
laminated layers are thinner than traditional layers and allow finer drilling technology. Staggered micro vias allow
vias within close tolerance or connected to a BGA pad to go down to the next layer or more to route away for
escape routing or underneath the BGA device for further interconnect. HDI type interconnect is used on complex
boards and takes extra steps in the processing flow due to special drilling, plating an laminations. It is a mix of older
technology mixed with newer technology that results in a board that is highly routable.
Figure 14-13. HDI Stack-up with Staggered Micro Vias
Advantages and Disadvantages of BGA Packaging
As pin counts increase and board space becomes more valuable, it is important to place as many circuits per
square inch as possible. BGA offer the best I/O density for a given PCB area. Lattice offers a range of packages
from a 4x4 mm 64-ball csBGA to a 33x33 mm 1704-ball fcBGA.
One of the greatest advantages of BGA packaging is that it can be supported with existing placement and assem-
bly equipment. BGAs also offer significantly more misalignment tolerance and less susceptibility to co-planarity
issues. Even if the solder paste is misaligned or the device is slightly offset, the BGA will self-center during the
14-14