PCB Libraries, Inc. | https://www.pcblibraries.com/Forum/topic2497&OB=DESC.html
. Then after the drill oversize and the layer to layer tolerance you still need to have 1 mil annular ring. IPC Class 3 Hole = 8 mil (0.20 mm) Pad = 20 mil (0.50 mm) IPC Class 2 Hole = 8 mil (0.20 mm) Pad = 18 mil (0.45 mm) The via hole tolerance would be
PCB Libraries, Inc. | https://www.pcblibraries.com/forum/topic2497&OB=ASC.html
. Then after the drill oversize and the layer to layer tolerance you still need to have 1 mil annular ring. IPC Class 3 Hole = 8 mil (0.20 mm) Pad = 20 mil (0.50 mm) IPC Class 2 Hole = 8 mil (0.20 mm) Pad = 18 mil (0.45 mm) The via hole tolerance would be
PCB Libraries, Inc. | https://www.pcblibraries.com/Forum/ipc7251-3tier-pth-pad-stack-obsolete_topic1463_post5897.html
. An example of this would be: The Nominal Environment annular ring (AR) was set to 8 mils. That means that a 10 mil hole had a 8 mil AR and a 20 mil hole had a 8 mil AR and the 40 mil hole had a 8 mil AR and a 80 mil hole had a 8 mil AR
PCB Libraries, Inc. | https://www.pcblibraries.com/forum/topic1463&OB=ASC.html
. An example of this would be: The Nominal Environment annular ring (AR) was set to 8 mils. That means that a 10 mil hole had a 8 mil AR and a 20 mil hole had a 8 mil AR and the 40 mil hole had a 8 mil AR and a 80 mil hole had a 8 mil AR
PCB Libraries, Inc. | https://www.pcblibraries.com/forum/ipc7251-3tier-pth-pad-stack-obsolete_topic1463.html
. An example of this would be: The Nominal Environment annular ring (AR) was set to 8 mils. That means that a 10 mil hole had a 8 mil AR and a 20 mil hole had a 8 mil AR and the 40 mil hole had a 8 mil AR and a 80 mil hole had a 8 mil AR
PCB Libraries, Inc. | https://www.pcblibraries.com/Forum/proportional-throughhole-padstacks_topic90_post41.html
) or the Pad is 20 mil (0.5 mm) larger than the hole size. Then, as the hole size gradually gets larger, the pad annular ring grows "Proportionally" larger in increments of 1 mil (0.025 mm
PCB Libraries, Inc. | https://www.pcblibraries.com/Forum/proportional-throughhole-padstacks_topic90&OB=DESC_page3.html
) or the Pad is 20 mil (0.5 mm) larger than the hole size. Then, as the hole size gradually gets larger, the pad annular ring grows "Proportionally" larger in increments of 1 mil (0.025 mm
PCB Libraries, Inc. | https://www.pcblibraries.com/forum/proportional-throughhole-padstacks_topic90&OB=DESC_page3.html
) or the Pad is 20 mil (0.5 mm) larger than the hole size. Then, as the hole size gradually gets larger, the pad annular ring grows "Proportionally" larger in increments of 1 mil (0.025 mm
PCB Libraries, Inc. | https://www.pcblibraries.com/forum/proportional-throughhole-padstacks_topic90_post27.html
) or the Pad is 20 mil (0.5 mm) larger than the hole size. Then, as the hole size gradually gets larger, the pad annular ring grows "Proportionally" larger in increments of 1 mil (0.025 mm
PCB Libraries, Inc. | https://www.pcblibraries.com/Forum/proportional-throughhole-padstacks_topic90.html
) or the Pad is 20 mil (0.5 mm) larger than the hole size. Then, as the hole size gradually gets larger, the pad annular ring grows "Proportionally" larger in increments of 1 mil (0.025 mm
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