The
calculated pad size from the following table means the
minimal requirement.
Use bigger pads to increase reliability.
Feel free to add teardrops.
For pad size calculation we use the drill diameter, that is the diameter of the drilling tool.
Note the difference between drill and hole diameter, the hole diameter is the diameter of the finished hole.
Learn more about this difference on the hole diameter page.
Pad size calculation
min. P = (2 x R) + FA + D
P R FA D
= = = =
Pad size Annular ring Fabrication allowance Drill or tool diameter
Rigid PCB's
Rigid-flexible PCB's
and thin laminates < 100 µm
Board size up to...
600
450
300
600
450
300
Fabrication allowance (FA)
0.35
0.25
0.20
0.40
0.30
0.25
Drill diameter (D) (example)
0.30
0.30
0.30
0.30
0.30
0.30
Annular ring (R) (example)
0.050
0.050
0.050
0.050
0.050
0.050
Minimal pad size (P)
(2 x R) + FA + D
(2 x R) + FA + D
Minimal pad size (P) (example)
0.75
0.65
0.60
0.80
0.70
0.65
Clearance area GND/VCC
(2 x R) + FA + D + 0.1
(2 x R) + FA + D + 0.1
Clearance area GND/VCC (example)
0.85
0.75
0.70
0.90
0.80
0.75
(all dimensions in mm)
Notes
For multilayers with more than 12 layers add 0.050 mm to fabrication allowance.
For each sequential laminating (SBU) add 0.025 mm to fabrication allowance.
For clearance areas of metal cores made of copper, aluminium or CIC add 0.1 mm to fabrication allowance.
For a copper thickness of 70 µm on inner layers add 0.025 mm to fabrication allowance.
For a copper thickness of 105 µm on inner layers add 0.050 mm to fabrication allowance.
For a copper thickness of 140 µm on inner layers add 0.075 mm to fabrication allowance.
For a copper thickness of 210 µm on inner layers add 0.125 mm to fabrication allowance.
Note that the required annular ring from this table is just an example.
The
calculated pad size from the following table means the