USB Token Enclosure

J

jharwinbarrozo

The exposed pcb pads of J1 I think is not long enough. It should be long enough to penetrate a female usb connector. So you have to search for how deep they usually are

flux

I’ll look up USB-A mating dimensions and compare them with the exposed length of J1 and the enclosure’s front edge. The important measurement is the unobstructed length from the PCB tip to the enclosure—not just the copper pad length.

flux

Your concern is justified: the PCB currently projects only 5.35 mm beyond the enclosure, while the USB-A drawing specifies at least 11.75 mm from the plug tip to its housing shoulder. I also found that J1’s contact pads appear outside the saved PCB outline, so shortening the enclosure alone would not resolve the connector geometry.
Created a project doc

USB-A Mating Clearance

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USB-A Mating Clearance Finding
The current enclosure leaves only 5.35 mm of PCB exposed in the insertion direction. This is too short to accept on the basis of the standard USB-A plug envelope. The earlier check that plastic ends before a J1 footprint boundary was not a USB mating check and must not be treated as one.
No PCB, copper, component placement, routing or enclosure geometry was changed during this research.
Sources and verified dimension interpretation
Primary geometry: Universal Serial Bus Specification Revision 2.0, Chapter 6, printed page 95, Figure 6-7 (Series A receptacle interface and mating drawing), and printed page 99, Figure 6-9 (Series A plug interface drawing). [Full specification mirror](https://alsa.mirrorservice.org/datasheets/usb/usb_20.pdf...

flux

You’re right: the PCB projects only 5.35 mm beyond the enclosure, while the USB-A plug drawing specifies 11.75 mm minimum from the plug tip to the housing shoulder—not copper pad length.
I recommend targeting 12 mm of exposed tongue, approximately 6.65 mm more, while keeping the electronics covered; J1’s conflicting pad/outline coordinates must be resolved before changing the PCB, as detailed in USB-A Mating Clearance.
Should I proceed with that USB tongue revision and refit the enclosure around it?
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Project Specification
Mechanical
Enclosure requirements
  • The enclosure must be a minimal, screwless, two-part FDM shell for the USB security token PCB.
  • J1 and the PCB USB contact tongue must remain fully exposed on both top and bottom, with an unobstructed insertion path into a female USB-A port.
  • User priority: minimize vertical size and eliminate broad empty space above and below the PCB.
  • Explicit compact-profile override: nominal PETG/0.4 mm-nozzle prototype uses 1.2 mm floor and roof skins and 0.5 mm local component/PCB clearances.
  • Current CAD target assembled height: 5.81936 mm.
  • The enclosure must not use PCB clips, lid latches, hooks, catches, release tabs, or discrete snap features.
  • Use a plain close-fitting lower tray and upper cover with a continuous shallow slip/friction-fit overlap; the closed shell captures the PCB perimeter.
  • Nominal lid clearance is 0.20 mm per side with 1.20 mm engagement; this fit and the 1.2 mm skins are provisional until physical PETG print testing.
  • J2 is DNP/unpopulated for the ultra-thin enclosure configuration.
  • Keep all enclosure plastic behind the J1 USB insertion keep-out; current CAD ends 0.25 mm behind that boundary.
  • Friction retention and axial PCB restraint require physical validation; do not add clips or latches as a fallback without explicit user approval.

  • Mechanical

  • Enclosure requirements