Will 1206, 1R resistor fail open or short?

[grizedale]

Hello,

If a 1206, 1R resistor conducts 20Amps of current, wil it fail open or short?

 

[Gagan23]

Grizedale,

saw the datasheet. for continous operation, 0.03W is allowed. going by it current comes 173mA.

The resistor will burn owing to ohmic heat loss of I2R. And, it will fail open......

 

[Sloth]

Hi,

If the resistor is the first thing to fail, I would guess it leaves an open. But that's just a guess. If you want it to leave an open, you should buy a special type of resistor, that is promised to leave an open in case of burn. Capacitors are also sold in the same manner.

Edit:

Here's an example:

https://fi.farnell.com/vishay-bc-components/nfr2500001008ja500/resistor-fusible-1r/dp/9473939

 

[godfreyl]

If a 1206, 1R resistor conducts 20Amps of current, wil it fail open or short?

I suspect the result would be a burned mess with some resistance - i.e. neither open nor short. I would worry about the fire hazard. Are you using a flame-proof PCB for this circuit?

 

[Sloth]

You should also consider using some current limiting. Without knowing anything about you circuit, you could consider adding a series PTC thermistor for current limiting. The thermistor has a very low initial resistance, but when current increases, the thermistor heats up, building up more resistance, thus limiting the current. This method won't have a fast protection, nor does it cut current spikes, but it's pretty harmless and easy.