Note: The figures in this chapter
assume that signals are routed from the BGA ball to a via in a dog-bone configuration where the signal from the BGA
routes diagonally from the pad to a via on the same routing layer. Via-In-Pad (VIP)
technology (see the Via-In-Pad Structure figure in Fabrication Technologies) can be used to place a via directly on top of a BGA
pad so it can travel straight down to an inner signal layer.
Recommended BGA Ball Pad and Via Dimensions for 1.0 mm, 0.92 mm, 0.8 mm, and 0.5 mm Devices
The definition of dimensions of FPGA/ACAP ball pads and vias for
Xilinx®
BGA devices are show in the
following figure. The table that follows shows the actual dimensions based on BGA
ball pitch.
Figure 1. BGA Ball and Via Definition of Dimensions
| Solder Ball Land Pitch (e) | 1.0 mm | 0.92 mm | 0.8 mm | 0.5 mm |
|---|---|---|---|---|
| Solder Mask Opening Diameter (M) | 20.9 mil | 20.9 mil | 15.7 mil | 11.0 mil |
| 0.53 mm | 0.53 mm | 0.40 mm | 0.28 mm | |
| PCB Solder Land Diameter (L) | 19.7 mil | 20.0 mil |
15.7 mil |
10.2 mil |
| 0.50 mm | 0.51 mm | 0.40 mm | 0.26 mm | |
| Via Plating Diameter (VD) |
19 mil |
19 mil |
19 mil |
10 mil |
| 0.48 mm | 0.48 mm | 0.48 mm | 0.254 mm | |
| Via Finished Hole Diameter (VH) |
10 mil |
10 mil |
10 mil |
4 mil |
| 0.25 mm | 0.25 mm | 0.25 mm | 0.10 mm | |
| Distance between BGA Pad and Via) |
27.83 mil |
25.61 mil |
22.27 mil |
13.92 mil |
| 0.70 mm | 0.65 mm | 0.56 mm | 0.35 mm |
Recommended Trace Routing between Pads and Vias for 1.0 mm, 0.92 mm, 0.8 mm, and 0.5 mm Devices
The ball pitch and BGA pad/via diameters determine how much space is available to
route traces between pads or vias. Standard PCB processes can allow for as low as
3.5 mil trace widths with 3.5 mil spacing. Advanced processes can allow for as low
as 2 mil trace widths with 2 mil spacing. Recommended trace routing is shown in the
following figure. The table that follows shows the actual BGA/trace routing
dimensions.
Figure 2. BGA/Trace Routing Dimensions
| Solder Ball Land Pitch (e) | 39.39 mil | 36.22 mil | 31.40 mil | 19.7 mil |
|---|---|---|---|---|
| 1.0 mm | 0.92 mm | 0.8 mm | 0.5 mm | |
| PCB Solder Land Diameter (L) |
19.7 mil |
20.0 mil |
15.7 mil |
10.63 mil |
| 0.50 mm | 0.51 mm | 0.40 mm | 0.27 mm | |
| Available Routing Distance (R) | 19 mil | 16 mil | 15 mil | 9 mil |
| 0.33 mm | 0.40 mm | 0.38 mm | 0.23 mm | |
| Pad-to-Trace/Trace-to-Trace Spacing for one route between pads (S1) | 7.5 mil | 6 mil | 5 mil | 3 1 |
| 0.19 mm | 0.15 mm | 0.13 mm | 0.08 mm | |
| Trace thickness for one route between pads (W1) | 4 | 4 | 4 | 3 |
| 0.10 mm | 0.10 mm | 0.10 mm | 0.08 mm | |
| Pad-to-Trace/Trace-to-Trace Spacing for two route between pads (S2) |
4 mil |
3 mil |
3 mil | N/A |
| 0.10 mm | 0.08 mm | 0.08 mm | ||
| Trace thickness for two route between pads (W2) | 3 mil | 3 mil | 3 mil | N/A |
| 0.08 mm | 0.08 mm | 0.08 mm | ||
|
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Recommended Trace Routing between Vias
One or two traces can be routed in-between vias for 1.0 mm, 0.92 mm, and 0.80 mm
pitch devices. It is not practical to route traces in-between vias spaced 0.5 mm
apart due to the tight spacing and trace widths required. For those situations, it
is recommended to use Via-in-Pad technology for added pitch between vias.
Recommended via/trace routing is shown in the following figure. The table that
follows shows the actual BGA/trace routing dimensions.
Figure 3. Via/Trace Routing
| Solder Ball Land Pitch (e) | 39.39 mil | 36.22 mil | 31.40 mil | 19.7 mil |
|---|---|---|---|---|
| 1.0 mm | 0.92 mm | 0.8 mm | 0.5 mm | |
| Via Drill Diameter (VD) | 10 mil | 10 mil | 10 mil | 4 mil |
| 0.25 mm | 0.25 mm | 0.25 mm | 0.10 mm | |
| Available Routing Distance (R) | 29 mil | 26 mil | 21 mil | 15 mil |
| 0.74 mm | 0.66 mm | 0.53 mm | 0.38 mm | |
| Via-to-Trace/Trace-to-Trace Spacing for one route between pads (S1) | 12 mil | 11 mil | 8 mil | 5 mil |
| 0.30 mm | 0.28 mm | 0.20 mm | 0.13 mm | |
| Trace thickness for one route between pads (W1) |
4 mil |
4 mil |
4 mil |
4 mil |
| 0.10 mm | 0.10 mm | 0.10 mm | 0.10 mm | |
| Pad-to-Trace/Trace-to-Trace Spacing for two route between pads (S2) | 10 mil | 6 mil | 5 mil | 3 mil 1 |
| 0.25 mm | 0.15 mm | 0.13 mm | 0.08 mm | |
| Trace thickness for two route between pads (W2) |
4 mil |
4 mil |
3 mil |
3 mil |
| 0.10 mm | 0.10 mm | 0.08 mm | 0.08 mm | |
|
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