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Archive for December 2013

  • PCB mounting 0.05" above the plate


    I have a design for a thermal cold plate which has several PCBs mounted 0.05" above the plate. In the previous production the mounting was achieved by having 4-40 threaded blind holes concentric with 4.6 mm circular cavities of 0.73 mm depth. A 2 mm spacer in each cavity defined 1.27 mm mounting height.

    I'd like to change mounting points to 4-40 studs with 5.08 mm depth offsets. That leaves 0.05" protruding part. My question is, what kind of variation can I expect on that height?

    Posted By: Dmitry Teytelman on Oct 24, 2017 03:24AM Category: Front Panel Designer

    Hi Dmitry,

    Our machining tolerance is +/- .1mm / .004"

    If you have any other questions let us know.

    Posted By: Adrian on Oct 25, 2017 01:19AM


    Hi Adrian,

    Thanks for your response! I do have a few more questions. If I machine a 0.73 mm deep cavity and set a 2 mm spacer in it, with +/-0.1 mm tolerance I get height above the plate of 1.27+/-0.1 mm.

    With the standoffs, is there additional spread due to differences in standoff installation depth? If I take 4-40 standoff with 5/16" length and specify 6.67 mm depth offset, do I still get 1.27+/0.1 mm expected spread?

    Finally, a slightly different question - is there a obvious better way of doing this that I am missing?

    Posted By: Dmitry Teytelman on Oct 25, 2017 01:35AM


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