I am a mechanical engineer, designing a small aerospace device with a simple electronic circuit. I was working with an EE but he left with work uncomplete, and now I have to finish in a hurry. The device is meant to function in a chain: think of christmas tree lights. I need to select a component to act as a switch: in the event that a key component in the device fails, causing an open circuit, I need to bypass that component and keep the circuit intact.

I looked, and Christmas tree lights do this with a resistor in parallel to the component (in their case an LED). That causes power burn, which I want to minimize if not avoid.

I have a tight form factor: no more than 0.130" in thickness for the component as well as the board. Laterally, there is more space.

Electronic requirements are up to 3 A current, and < 1.5 volt drop across a single component. However, in the moment of failure, voltage could be higher, i.e. the stacked voltage drop of all units in the chain. Maximum in that case would be 28 V.

I understand my options are 1) a relay, which draws no power; and 2) a diode, which would draw power. We ruled out a switching transistor based on complexity required to drive it. I want a very dumb passive component. This is an analog circuit.

My question specifically relates to relays - I am hoping someone can tell me if there is a component in the size range required. My searches show large components that look like they were cutting-edge in the 50's. I feel like there must be something smaller I am just not finding.

Your help is much appreciated.