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In my current design, just for uniformity I wish to keep all the components as SMD. There is one copper line on the PCB which goes up to 1000V (with current in milliamps obviously,) for which I need to attach a resistor and capacitor across it.

Most of the components I found which bear 1kV voltage are through hole. Are there any SMD components that I can use?

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4 Answers 4

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There is the Bourns CHV series of high voltage resistors. The CHV2010 model can stand up to 2 kV and CHV2512 up to 3 kV continuous.

However, clearance and creepage requirements are often larger. For example, IEC 61010 specifies 5.0 mm creepage distance for 1 kV secondary circuits in normal indoor conditions. But that CHV2010 resistor only has 3.7 mm distance between its terminals. Thus it would require potting to actually pass the requirements of that standard.

As other answers have mentioned, putting multiple resistors and capacitors in series is often a better alternative. But when doing that, do also pay attention to the required insulation distances.

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    \$\begingroup\$ As Andy suggested in his answer you can always route out the board below the resistor to the extent that you achieve the 5mm creepage. \$\endgroup\$
    – Ben Watson
    Commented Sep 10, 2021 at 16:37
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    \$\begingroup\$ Also when putting capacitors in series pay attention to balancing the voltage across them. In the OPs case that means rather than having a series string of resistors and a separate series string of capacitors the OP should use a single string of resistor/capacitor pairs. \$\endgroup\$ Commented Sep 10, 2021 at 23:44
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    \$\begingroup\$ @BenWatson That does not usually help with SMD resistors, as the surface of the resistor itself does not become longer. Though it is of a different material, which may or may not require shorter distance. It also carries a risk of mechanical damage due to flexing. \$\endgroup\$
    – jpa
    Commented Sep 11, 2021 at 5:02
  • \$\begingroup\$ @jpa I see, good points! \$\endgroup\$
    – Ben Watson
    Commented Sep 11, 2021 at 21:01
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Is there any SMD component that I can use?

You have to employ tricks when you have 1 kV around like putting a bunch of lower voltage rated resistors in series (as per the light blue block below): -

enter image description here

Notice also the cut-out in the PCB directly below R104-106 - this allows you to get components a little closer. For capacitors (purple box) - these are 2 kV rated devices and have a cut-out on the PCB to to give a little more clearance and voltage withstand. Surface mount capacitors are commonly available over 1 kV rating.

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There are some large case (e.g. 1206, 1210, 1812, 2512) capacitors in pF and nF range having at least 1kV rated voltage.

For resistors, things are a bit different. For example, today's 1206 case resistors do not withstand voltages higher than 200-300V (acc. to datasheets at least). So you need to put multiple resistors connected in series in any case taking the power dissipations and clearances into account as well.

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You do place them in a series string, for example five of them. Also keep in mind that miliamperes on kV range is high power and dangerous.

HI Res photo - Courtesy of EEVblog

enter image description here

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