I need to use some sort of jumper to allow heavy current from terminal block to the relay pins:


Dimensions shown in mm. I want to replace this trace with a jumper, preferably SMD. Going through datasheets, I found these:


High resistance makes this almost useless. I want the current handling capacity around 25 A. This components gives 10 A for 30 degree C rise. There are other packages available at different price but they don't make much sense for my project.

I checked current sensing shunt resistors which are available in 1 mohm resistance and 5 W power handling capacity for almost the same price. Should I go for these instead of jumpers?


2 Answers 2


As you discovered, jumper resistors are not good for carrying a lot current because of their relatively high resistance. A 1 milli-ohm resistor is a good choice. Also Keystone makes a low cost jumper that works well:



I think you must go to a Thruhole current shunt for this 25A requirement of 625mW to reduce the local temp rise. It might be 1cm on each leg. . I've seen them as stamped 1mm copper with EMI wall shields around them for SMPS. THere's no way an SMD jumper can fit here. Even the 50 mil tracks are far too thin even if it were 4 oz. copper.

Pd = (25A)² R for 1mΩ = 625 mΩ which for a 50 mil x 200 mil track is 0.6mΩ with 1oz Cu. and conductor temp rise is 40'C above max ambient which is excessive, not for the wire but for other parts nearby.

Your tracks could be supplemented with a busbar to support this current in a small space and minimize temp rise.

Even this Keystone jumper is 5 mOhm minimum and you need <=1 mΩ enter image description here

So look for a heavier duty version of the above and do not rely on even 100mil copper tracks for 25A current then the sense traces must not be near any joints for consistency with solder.


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