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Thread: Need immediate help: Jedec Drawing Surface Profile question

  1. #1
    Associate Engineer
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    Need immediate help: Jedec Drawing Surface Profile question

    Hi, I was looking at the attached image of a Jedec POD (Package Oultine Drawing) and have to ask 3 questions:
    1) Are 'D' and 'E' correct not to be BASIC dimensions?
    2) The surface profile tolerance datum is 'C' which is the seating plane for this POD. Should it be 'A' and 'B' instead?
    3) If the drawing is correct on its Surface profile call-out, how should it be interpreted?
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  2. #2
    Technical Fellow Kelly_Bramble's Avatar
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    Quote Originally Posted by Nomer View Post
    Hi, I was looking at the attached image of a Jedec POD (Package Oultine Drawing) and have to ask 3 questions:
    1) Are 'D' and 'E' correct not to be BASIC dimensions?
    2) The surface profile tolerance datum is 'C' which is the seating plane for this POD. Should it be 'A' and 'B' instead?
    3) If the drawing is correct on its Surface profile call-out, how should it be interpreted?
    Engineering drawing is incomplete as well as application is not fully understood so a full evaluation is not possible. Additionally you did not specify the industry standard. I'll answer accordingly..

    Q1 -> If the Profile of Surface tolerance is meant to control all of the outer perpendicular to view surface then the dimension E and D should likely be Basic (TED).

    Q2 -> The Profile of Surface relative to Datum C specification also seems OK. Based on your description I think Datum C is the near most planar surface. Relative to datums A and B should be used in the FCF. I would remove datums A and B if not used.

    Q3 -> The profile of Surface intent appears to control the top surface and the other three surfaces perpendicular to the view. If this is intent I would have used the "All Around" symbology with the FCF specification. The datum appears to be the front planar surface. Therefore the Profile of Surf. tolerance is two sets tolerance boundaries (inside and outside of the true drawing profile) projecting parallel to the surfaces and perpendicular to front face datum C. The tolerance boundaries are bilateral equal and displaced equal to the Profile of Surface Specification.
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