Remove 0 Ohm resistor (solder bridge jumper)

Question

I have an STM Nucleo-64 board that I want to power from my own 3v3 rail. To do so you must remove two solder bridges (SB2 and SB12 in the photos), both made with what appear to be size 805, \$0\Omega\$ resistors that are placed close to other nearby components. Does anyone have a technique for removing these safely?

I considered trying to somehow snip them, but I don't see how to get flush cut snips in there safely. Maybe I could cut perpendicularly through the bridges from above, but even that looks like it would be difficult. I could try to wick them, but it would be a bear.

I think my best idea might be to use a hot air gun and hope the nearby stuff stays in decent shape. Otherwise it might actually be easier to snap the ST-Link from the rest of the board...

Answer 1

Skill with a soldering iron goes a long way, at my place of work we have a professional rework technician that can do this with a standard soldering iron, it requires finesse and care, and sometimes reflowing or resoldering adjacent components

For mere mortals there are other tools, personally for small SMT resistors I prefer to use a tweezer soldering iron, which is an available attachment for many common soldering stations (HAKKO,Metcal, Weller) as well as standalone "irons". There are also special soldering tips that have a "gap" or fork that fit around the SMT part

For Guides on this type of rework I like Circuit Rework.com which has two guides available for this type of work

1. Forked Tip Method
2. Hot Tweezer Method

Answer 2

It seems like your question really is how to desolder a 0805 resistor. This is easily done various ways:

1. Use a single soldering iron. Turn up the temp a little higher than usual, like 700 °F. Melt the solder on one end. Then melt the solder on the other end. Go back and forth until everything gets hot enough so that the solder on one end takes longer to cool than it takes to melt at the other end when the iron is moved. Once that happens, simply push the part away. It will usually stick to the soldering iron due to surface tension. It can help to add some solder to each pad before doing this. Each end then takes longer to cool once molten.

2. Use two soldering irons. The rest should be obvious.

3. Use a hot air soldering station and tweezers to lift off the part.

Trying to cut the part off the board is a bad idea. Bit can go flying around, and there is also a good chance of damaging the pads.

Answer 3

In addition to the other fine answers, (assuming you have the wrong tools) a 65W flat (properly maintained) cheap flat edge tip and solder iron applied to both sides by alternating on either side to increase the solder temp to liquid in 5 seconds is all it should take.

A hot plate makes it easier. (<100'C)

A solder technician can do this with a Weller 0603 part 1/16 diam tip @ 315'C/ 600'F in about 3 seconds. This appears to be 0805 and won't take much longer. (4s)

Answer 4

I had to do this today on a STM8SVL DISCOVERY board. I used desoldering braid and the braid lifted the jumper off the board with the solder. It went much easier than I had expected.