Have questions about specifications? We've included the most common answers here.

    Frequently Asked Questions - Specifications

    Our ISO 9002 standards specify our boards must conform to IPC-A-600 Class 2.

    What are the most common PCB board parameters?

    The most common PCB board parameters are:

    • Material: 0.062" FR4
    • Finish: Immersion White Tin
    • Copper Weight: 1 oz/sqft
    • Smallest Hole: 0.016 "
    • Trace / Space: 0.007 " / 0.007 "
    • Silkscreen: White, component side
    • Soldermask: LPI Green

    For a complete list of specifications please visit our Capabilities Page

    What is the minimum annular ring?

    We require minimum 0.005" copper pad ring around drill holes. Under ISO 9002 standards, Omni does not recommend a board with a smaller copper ring than this.

    What is the finest silkscreen resolution possible?

    Our best resolution for the silkcreen layer is 5mil. More information about silkscreening can be found here.

    What are the minimum Traces & Spaces?

    Extra base copper on a board will limit the size of the features on it. The following is a list of the minimum traces and spaces:

    Base Cu / Oz Traces / mil Spaces / mil
    0.5 4 4
    1 8 8
    2 10 10

    We may be able to go below these guidelines under some circumstances depending on the layout of the board.

    What is silkscreen clipping? Does Omni clip silkscreens?

    This is when the CAM operator removes all silkscreen elements that would be printed on the pads. Omni only clips the silkscreen on request or when the boards are to be electrically tested.

    What does copper thickness: 0.5 + 0.7 Oz Cu mean?

    The first number refers to the base copper we start with. The second refers to how much we plate up the board by. So 0.5 + 0.7 Oz would be a little over 1 Oz of Copper. For a more detailed explanation on how copper weights impact board design, please go here.

    What is the recommended copper thickness?

    The thickness of the copper on a board is a design requirement, so Omni cannot make a recommendation on this issue. We can say that most boards we make have 1 Oz finished Cu.

    What is the Dieletric Constant of FR4?

    The Dieletric Constant of our FR4 is about 4.7 at 1 MHz. However, we cannot give a fixed value for this since it tends to drift from batch to batch. If a fixed dieletric is required, it is possible to build on specialty PCB materials. Omni has experience with Rogers, Isola and Arlon materials, duroid and polyimides.

    What is the Df (Dissipation Factor) of FR4?

    The Df (Dissipation Factor) or Lf (Loss Factor) of our FR4 laminates can be found in the attached table.

    What final finishes can Omni provide?

    For prototyping and small volume runs, we offer Immersion White Tin and Hard Gold finishes. We also offer HASL, ENIG and Immersion Silver finishes which are provided by suppliers we have long standing relationships with. For large volume runs, we provide all finish options through offshore sourcing.

    Are aluminum trace PCBs really solderable?

    Yes, we have solder and flux options for both standard and fine pitch (0.020") aluminum trace PCB applications. Contact us for details.

    Are aluminum circuit boards the same as aluminum trace circuit boards?

    No, Aluminum circuit boards typically use an aluminum plate to help conduct heat away from critical components while Aluminum trace circuit boards utilize fine line aluminum circuitry to electrically connect electronic components.

    How many PCBs can I nest on one standard panel?

    As many as you need considering the maximum outside dimensions of a standard panel is 12.5" x 16.5". For routed PCBs which are rectangular and greater than 1.0" in length, allow for a 100 mil (0.100") gap between boards for all others allow for a 300 mil (0.300") gap. For V-score PCBs, we recommend a 20 mil (0.020") border between copper and silk screen features.


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    Need help? We're only a call away at 1-855-798-9717 (Toll Free) during regular business hours. Pacific Standard Time (PST). You can also use our contact form.

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