PCB Minimum Annular Ring

Printed Circuit Board (PCB) minimum annular ring refers to the minimum amount of copper between the edge of the land and the edge of the hole, after the finished hole is plated. It is also referred to as a supported hole. Sometimes, the traces on a circuit board are required to be connected to another layer. In such cases, the traces end up on a pad. The via on the pad helps the trace to move from that pad and connect the other layer. The area on the pad, which surrounds the via is referred to as annular ring. It is very crucial to have a proper setting of the annular ring in the PCB layout software. This helps maintain proper spacing of copper. Twisted Traces is a company, which can help you in setting a proper annular ring for your printed circuit board.

Calculating the Annular Ring

The copper ring, which is also referred to as the annular ring, makes a through-hole pad around a drilled hole. For the purpose of creating via, the drilled hole is surrounded by the ring of copper. In case of vias, this is most commonly referred to as outer diameter or via size. According to the IPC-2221A standard, the PCB minimum annular ring size is calculated as follows:

Minimum Annular Ring = (Min Ring Border)*2 + (Hole Size) + (Tolerance)

   Minimum Annular Ring on the Inner Layer     0.1mm
   Minimum Annular Ring on the Outer Layer    0.05mm 

Annular ring width can be calculated as: (diameter of the pad - diameter of the hole) / 2 So, for example, if the diameter of a pad is 20 mil and its hole diameter is 10 mil, then the annular ring width would be: (20 – 10) / 2 = 5 mils. We have a huge experience of more than three decades, which has helped us grow and provide high-quality services and products. To know more about the PCBs that we manufacture, you can contact our professionals on our 24/7 live support line (630) 345-5400, or mail us your queries and requirements at This email address is being protected from spambots. You need JavaScript enabled to view it..

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