I have noticed that in almost every board, RJ-45 Ethernet sockets are always soldered upside-down. Why are these sockets made this way? Wouldn't it be easier to make and solder them with the pins laying on the bottom?


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    \$\begingroup\$ How have you come to the decision that one way is right-side-up and the other way is upside-down? \$\endgroup\$ – brhans Mar 16 '15 at 18:06
  • \$\begingroup\$ @brhans I was about to ask a similiar question. That RJ45 you posted, can be soldered top down or bottom up. The pins still go through the board, and soldering is the same whether top or bototm. \$\endgroup\$ – efox29 Mar 16 '15 at 18:07
  • \$\begingroup\$ Yes, I mean... Why the pins are not in the same side of the internal contacts? \$\endgroup\$ – Alex Mar 16 '15 at 18:09
  • \$\begingroup\$ Thats a through hole part. There are surface mount connectors that have them on the same side. But hand soldering them is much more difficult than through hole. \$\endgroup\$ – efox29 Mar 16 '15 at 18:11
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    \$\begingroup\$ I have through hole RJ45 components with the pins on both top and bottom... So idk where you're getting this idea that they're always like the one in the picture, because they're not. Probably has more to do with where you want the release tab for the RJ45 to be more than anything \$\endgroup\$ – I. Wolfe Mar 16 '15 at 18:13

Connector profile is often a huge concern. I think you'll find that by putting the contacts on the top and the tab close to the board, the socket can be made 1mm or 1.5mm less tall.


I think it's just as easy to manufacture one style or the other. The reason for preferring to have the tab on the bottom is that it is less likely you'll accidentally unplug the cable by something hitting the tab.


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