I would like to know why thermal jumpers are used. If lets say that we use thermal jumpers in the circuit and they get either short or open during operation. How does it effect my heat performance of the circuit. I am adding the schematic for better understanding. enter image description here

Marketing Material: https://www.mouser.ca/new/vishay/vishay-thjp-thermawick-chips/

Datasheets: https://www.vishay.com/docs/60157/thjp.pdf

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    \$\begingroup\$ Show links to part and photo of circuit \$\endgroup\$ Mar 14, 2021 at 14:37
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    \$\begingroup\$ I for one, would like to know the answer to this question. I've seen electrically-insulating, thermally conductive chip components and have always wondered how effects they are at their job. It seems to me like not very so power applications seem out. But then begets the question what application would be so sensitive that would need such an improvement? Instrumentation? I gather they are superior to vias but much bulkier. I've added links to OP's post. \$\endgroup\$
    – DKNguyen
    Mar 14, 2021 at 19:27
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    \$\begingroup\$ There is a video on SMD thermal jumpers on eevblog that could be interesting. \$\endgroup\$ Mar 14, 2021 at 20:00
  • \$\begingroup\$ @LarsHankeln That video is real helpful. Though, I think I'd have to test it on a real board to believe it's effectiveness. Those parts are really expensive but Dave is correct when he mentions that heatsinks are also really expensive. But them being a generic SMD part makes me want to have a reel of 100 or 1000 of them just on hand. \$\endgroup\$
    – DKNguyen
    Mar 15, 2021 at 8:13

2 Answers 2


If the surface mount component could be electrically connected to GND it would be connected using an array of thermal vias. The ground plane then provides heat dissipation across a bigger area so that the temperature stays within reasonable limits. If the power dissipation of the component is quite high, an additional heat-sink is attached on the bottom side of the PCB.

It becomes more difficult when isolation is required between the component and ground. Connecting the component to a heat-sink is still possible using isolating thermal interface materials e.g. SIL-PAD 900S. But thermally connecting the component to the ground plane is not as easy. This is where thermal jumpers come into play. You can use them to connect the power dissipating component to an array of ground vias while maintaining electrical isolation:

Illustration of thermal jumper application Source: pk-components

The thermal resistance for a 0612 thermal jumper is about 4°C/W. To gage this performance, we could have a look at the thermal resistance of an array of vias:

thermal via resistance

Source: High efficient heat dissipation on printed circuit boards

The 5mm x 5mm via array has a thermal resistance that is similar to one 0612 thermal jumper. But at least three 0612 thermal jumpers can be connected to the 5mm width of the via array. This makes the thermal resistance of the vias more significant then the thermal resistance of the jumpers.

Coming back to the original question:

If lets say that we use thermal jumpers in the circuit and they get either short or open during operation. How does it effect my heat performance of the circuit.

Shorting the jumper also means electrically shorting the two nets. This is very likely not a good idea. The concern of an open circuit is the temperature increase of the component. It depends on the component and its power dissipation if this is harmful or not.


The thermal jumpers are electrically isolating, and have a very low thermal resistance. Not sure what you mean with "Ether open or closed"

Say you have a typical MOSFET where the back tab is connected to drain, and as such has a voltage there.

During operation the mosfet will get hot, so you need to cool it.

You could add a convensional heatsink, or connect the tab copperpad to your huge nearby GND plane(s) with thermal jumper. The entire GND plane is now your heatsink.

  • \$\begingroup\$ How effects would this really be though? Because heat already doesn't travel far on a PCB copper plane so how effective would it actually be to connect to a tiny point at the very edge of the plane? \$\endgroup\$
    – DKNguyen
    Mar 14, 2021 at 19:33
  • \$\begingroup\$ I meant in future operation, if the thermal jumper is either short circuited or open circuited then how does it change the heat sink capability of the circuit \$\endgroup\$ Mar 14, 2021 at 20:07
  • \$\begingroup\$ You would stich together planes with lots of these. Typically you would not have a plane at heat source at all, these would connect as close to the pad as possible. You cannot electrically change these. If they are shortcircuted they have no use - it would be better to use a copper plane. Perhaps you are mixing up the terms thermal resitance and electrical resitance? \$\endgroup\$
    – Arcatus
    Mar 14, 2021 at 22:24
  • \$\begingroup\$ Are you sure they are electrically isolating? Some I've seen aren't. \$\endgroup\$
    – Damien
    Mar 15, 2021 at 8:12
  • \$\begingroup\$ @Damien: You have? I've seen small SMD heatsinks, but that is something else entirely. I have only seen thermal jumpers made out of ceramics that were electrically isolating. I might be mistaken, off course, lots of strange parts out there. (But how would you use them if they were conductive?) \$\endgroup\$
    – Arcatus
    Mar 15, 2021 at 9:12

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