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I'm designing a board with a USB port where the user connects its phone though a USB cable. I want the connection between the USB cable and the board to be strong so the user don't accidentally unplug the cable. So the standard USB port won't work in my case, neither those expensive sealed USB connectors.

I was thinking to use simple SIL connectors with "bornier" type of connectors. see pictures below.

Will that affect the USB communication ? it is a USB2 communication with small data packet transfert.

Let me know guys what you think about this

connector to plug in the board connector to plug in the board

Thank you

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  • \$\begingroup\$ You're going to have a hard time getting a meaningful answer to this. Obviously, this looks like it would probably be an impedance discontinuity in drastic violation of the specs. If it would work or not would require fairly tricky analysis to determine in theory. In practice, if it works when tested say in between two two meter extensions, then you might have some provisional hope of it working near one end of a short cabling run. Things might be better if one of your devices were (ultimately or software) limited to USB full speed. There are probably better connectors. \$\endgroup\$ – Chris Stratton Jan 5 '18 at 17:44
  • \$\begingroup\$ Samtec makes high retention USB connectors. Then you could use a standard USB cable. \$\endgroup\$ – EE_socal Jan 5 '18 at 18:06
  • \$\begingroup\$ When you say "USB 2", what do you mean? USB 2.0 standard supports HS mode (480 Mbps), FS mode (12 Mbps), and LS mode (1.5 Mbps). Which data rate will be used in your application? \$\endgroup\$ – Ale..chenski Jan 5 '18 at 18:23
  • \$\begingroup\$ I meant USB 2.0 FS 12 Mbps, CDC class \$\endgroup\$ – C.Hicham Jan 7 '18 at 20:45
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For the link speed of 12 Mbps (FS) nearly any connector will work just fine, provided that the rest of cabling/PCB tracing maintains 90 Ohms. Although the USB 1.1 specifications do require 90-Ohm differential impedance for FS cables, the FS is not sensitive to transmission line impedance mishaps. In FS mode major reflections are ignored, since all signals are sampled in the middle of bit unit interval, where the reflections already die out more or less. More, as long as the impedance-mismatched area is shorter than 0.5-1", the reflection won't show up at all at typical FS edge rates. And as long as the D+/D- wire lengths don't differ for more than ~2 inches (skew allowance is 400 ps), it should work.

But if you have a screw-type connection (which is basically non user removable), why don't you just solder the USB cable to your board? It will be more reliable, and should even work for HS mode.

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  • \$\begingroup\$ Thank you for your reply, I can't solder the cable so I can swap it easily if needed. \$\endgroup\$ – C.Hicham Jan 8 '18 at 17:05
  • \$\begingroup\$ Just to back up Ali, I once designed a board for a customer with a PCB mount USB socket on it; he ended up using a chassis mount connector and soldered wires from the connector in to the PCB and it worked fine. This was also using CDC class. \$\endgroup\$ – DiBosco Jan 9 '18 at 8:21

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