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I am currently in process of my eagle library cleanup, and came up with the idea to create a footprint similar to the one from nucleo boards. Those pads are meant to be easily bridged by just solder when modifying the board:

Nucleo 0603 solder bridges

However I couldn't really find much useful information about specific layouts, especially things like pastemask layout and minimum safe gap on such pad shapes.

Goals of the footprint:
1) will take a surface mount resistor by pick-and-place
2) won't bridge if the resistor is not placed
3) can be easily (un)bridged by hand soldering
4) provide visual distinction between normal resistors and bridges on both schematic and PCB

Please note, that the goal of these footprints is not to replace original footprints specified in manufacturing standards, but rather make prototyping the product easier, when the ammount of devices is in hundreds rather than millions.

If anyone has any useful materials, or even clues where to find such info, it would be really nice to share them here.

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  • \$\begingroup\$ Can you make it a bit clearer what you want from these pads? Is it 1) will take a surface mount resistor by pick-and-place and 2) won't bridge if the resistor is not placed and 3) can be easily bridged by hand soldering? \$\endgroup\$ – Jack B Oct 21 '18 at 11:21
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    \$\begingroup\$ I have no reflow experience but I know that the components are pulled into line by surface tension during reflow. I would be afraid that your cool-looking solder pads would cause a component to shift enough to cause a short-circuit across the pads. Nobody's going to see them once the components are in place. What's the benefit? \$\endgroup\$ – Transistor Oct 21 '18 at 11:22
  • \$\begingroup\$ @JackB yes, exacly, and also providing visual distinction between normal resistors and on-off connections on both schematic and PCB. \$\endgroup\$ – CritBit95 Oct 21 '18 at 11:31
  • \$\begingroup\$ @Transistor that's a photo of ST Nucleo. Those pads are meant to be easily bridged by just solder when modifying the board. \$\endgroup\$ – Jan Dorniak Oct 21 '18 at 11:32
  • \$\begingroup\$ @Transistor This is why I'm asking for some guidelines. Atleast ST has done that on their products, so it might be viable (while i'm not saying it certainly is) \$\endgroup\$ – CritBit95 Oct 21 '18 at 11:33
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There is no mention of solder bridges in the main standards - except on design equations on how to avoid them:

  • IPC-7351 - Generic Requirements for Surface Mount Design and Land Pattern Standard;
  • EN 61188−5−1 Printed boards and printed board assemblies - Design and use;
  • EC 61191-2:2017 Printed board assemblies.

We use just a zero ohm jumper - it's reliable and not very expensive.

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    \$\begingroup\$ Do these standards contain solder bridge pads? I thought they only had standard 0603 pads etc. not special ones which are designed to double as hand-solderable bridges, which is what I think this question is about. \$\endgroup\$ – Jack B Oct 21 '18 at 11:20
  • \$\begingroup\$ You can see that on the photo, "0" resistor has been mounted, probably by a machine, even though the footprint underneath is not the standard "0603". I would like to know, what should I remember about, when designing such non-standard footprints. \$\endgroup\$ – CritBit95 Oct 21 '18 at 12:29
  • \$\begingroup\$ I don't see much of a problem in terms of the PCB, the stencil pattern could (should) be kept as a rectangular pad, or a dome top, as a chevron it may get caught eventually on the squeegee by the point and getting damaged. \$\endgroup\$ – isdi Oct 22 '18 at 10:52
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Usually, you want to avoid solder bridges. If you want a removable short, you can use either a thin copper trace instead, with component pads in case you want to remake the short, or as mentioned in Duck's answer, a 0 Ohm resistor.

All the production equipment (Stencils, AOI programming, ICT tests) is geared to detect and warn against such bridges.

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