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19-1
tn1074_01.7
March 2010
Technical Note TN1074
Introduction
As Ball Grid Array (BGA) packages become increasingly popular and become more populated across the array
with higher pin count and smaller pitch, it is important to understand how they are affected by various board layout
techniques. This document provides a brief overview of PCB layout considerations when working with BGA pack-
ages. It outlines some of the most common problems and provides tips for avoiding them at the design stage. A key
challenge of adopting fine-pitch (0.8 mm or less) BGA packages is the design of a route fanout pattern that maxi-
mizes I/O utilization while minimizing fabrication cost. This technical note provides an overview of PCB design
examples provided by Lattice Semiconductor.
For more information and design examples see the PCB Design Support page at the Lattice Semiconductor web
BGA Board Layout Recommendations
All Lattice BGA packages have Solder Mask Defined (SMD) pads. In order to evenly balance the stress in the sol-
der joints, Lattice recommends PCB solder pads be SMD with dimensions as similar to the applicable BGA as pos-
sible. If Non Solder Mask Defined Pads (NSMD) are used, the optimum pad dimensions will result in an equivalent
surface contact area on the PCB as on the BGA component.
Table 19-1. Lattice Semiconductor SMD/NSMD Pad Recommendations
Pitch 0.4 mm
ucBGA
Pitch 0.5 mm
csBGA
Pitch 0.8 mm
caBGA
Pitch 1.00 mm (fpBGA, ftBGA, fpSBGA, fcBGA)
Pitch
1.27 mm
PBGA,
SBGA
100 fpBGA,
256 ftBGA
All Other fpBGA,
ftBGA,fpSBGA
1020 Organic
fcBGA
All Other
fcBGA
Solder Mask Defined (SMD) Pad Recommendations
Optimum Solder Land
Diameter1
0.25
0.40
0.50
0.55
0.65
0.60
0.73
Solder Land Diameter
Range
0.20 - 0.25
0.25 - 0.40
0.40 - 0.60
0.45 - 0.70
0.45 - 0.70 0.55 - 0.85
Optimum Solder Mask
Opening (M)
0.20
0.25
0.40
0.45
0.55
0.50
0.63
Solder Mask Opening
Range
0.18 - 0.22
0.20 - 0.30
0.35 - 0.50
0.40 - 0.60
0.40 - 0.60 0.50 - 0.75
Non Solder Mask Defined (NSMD) Pad Recommendations
Optimum Solder Land
Diameter (L)
0.16
0.23
0.35
0.40
0.52
0.45
0.58
Solder Land Diameter
Range
0.14 - 0.18
0.20 - 0.30
0.35 - 0.50
0.40 - 0.60
0.40 - 0.60 0.50 - 0.78
Optimum Solder Mask
Opening1
0.22
0.35
0.45
0.50
0.55
0.70
0.60
0.73
Solder Mask Opening
Range
0.20 - 0.25
0.30 - 0.40
0.45 - 0.55
0.45 - 0.60
0.50 - 0.70
0.50 - 0.85
0.50 - 0.75 0.60 - 0.88
1. Assuming 0.050 mm solder mask tolerance.
PCB Layout Recommendations
for BGA Packages