Category:PCB PCB Design Rules

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Initially PCBs were designed manually by creating a photomask on a clear mylar sheet, usually at two or four times the true size. Starting from the schematic diagram the component pin pads were laid out on the mylar and then traces were routed to connect the pads. If you have many questions of PCB Design, please come here!

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PCB Design:Six Valuable Tips and Practices Reply 2017-02-14 17:20:35
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Giampaolo Braga

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PCB design is the balance between longevity, functionality, aesthetics, PCB costs, time for designs and capabilities. With some simple but valuable tips and practices, you can ensure a more robust printed circuit board design, which can save money for you.

The following are eleven of the most common useful practices in PCB design:

Trace Angles

45 degree trace angles are recommended for the smaller impact on the trace width, while trace angles greater than 90 degrees will cause acid traps that is harmful to PCB boards. The narrow angles are more likely to cause copper migration and electromagnetic radiation, and should be avoided.

PCB Thickness to Drill Diameter Ratio

PCB Thickness to Drill Diameter Ratio should be less than 3.9:1, which will keep the PCB manufacturing cost much lower. For example, a 0.080” thick PCB with a minimum drill size of 0.020” results in a ratio of 4:1 will cause extra costs in manufacture.

Annular Rings

For small holes, you’d better make sure that annular ring widths are at a minimum of 0.005”. And the annular ring size of 0.006” and greater is recommended in your PCB design. As for the shape of annual ring, the shape of a droplet is recommended, especially the design with min. width of 0.005”.
Space and Trace

If space and current is not an issue, the recommended spaces and traces that are dependent on copper thickness, are at or greater than:

  •  1/2 oz Cu boards: 0.007”/0.007”
  •  1 oz Cu boards: 0.008”/0.008”
  •  2 oz Cu boards: 0.010”/0.010”
  •  3 oz Cu boards: 0.012”/0.012”

Space and trace less than 0.007”/0.007” will result in higher costs in manufacturing. Besides, remember to keep the space between a trace and the ground plane at a minimum of 0.008” but a space of 0.010” is preferred.

Solder Mask

Solder mask is necessary for all PCB boards. To omit solder mask is able to save slight cost but the risk of short circuits in the soldering is much stronger. It is acceptable to cover through-hole vias with solder mask. It is recommended to offer zero mask expansion and allow your PCB manufacturer to adjust if necessary.

Ground Plane

When taking v-scoring in manufacture, make sure the ground plane is at a minimum of 0.020” from the edge. And as for routed boards, you should guarantee 0.010” between the ground plane and the edge.

The best time to carry out these techniques is at the stage of design, depending on the volume and expected lifespan of your PCBs. But a DFM redesign is also necessary for PCB manufacturing. Usually, the easiest way to determine the feasibility of a redesign is to work with PCB manufacturers directly, with the consideration of their manufacturing capabilities.

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Statement: This post is only the personal view of the author and does not represent the opinions of ALLPCB.com.

Jerry

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Nice content you’ve posted in here
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