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Annular Ring Formula:
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The annular ring in PCB design refers to the copper pad area that surrounds a drilled via or hole. It ensures proper electrical connection between the via and the copper trace on the PCB layer.
The calculator uses the annular ring formula:
Where:
Explanation: The formula calculates the radial distance from the edge of the drilled hole to the edge of the copper pad, divided by 2 to get the width on each side.
Details: Proper annular ring width is crucial for PCB reliability. Insufficient ring width can lead to connection failures during drilling or thermal stress, while excessive width wastes space and may cause manufacturing issues.
Tips: Enter pad diameter and via diameter in millimeters. Both values must be positive, and pad diameter must be larger than via diameter for valid calculation.
Q1: What is the minimum recommended annular ring width?
A: Typical minimum annular ring width is 0.15mm for standard PCBs, but this varies based on PCB manufacturer capabilities and design requirements.
Q2: Why is annular ring important in PCB manufacturing?
A: It ensures reliable electrical connections, provides tolerance for drilling misalignment, and prevents breakout where the drill hole breaks through the copper pad edge.
Q3: What happens if annular ring is too small?
A: Small annular rings can cause connection failures, drill breakout, reduced reliability, and increased risk of open circuits during thermal cycling.
Q4: Does annular ring requirement differ for different PCB types?
A: Yes, high-density interconnect (HDI) PCBs may have smaller annular rings, while high-reliability applications often require larger rings for better mechanical strength.
Q5: How does annular ring affect PCB cost?
A: Smaller annular rings may require more precise manufacturing processes, potentially increasing cost. Larger rings use more copper but are generally easier to manufacture reliably.