Singapore Savings Bond as passive income

Passive yes, but using it solely is probably not a very good one.

1. U said 24 months, so technically u need to buy SSB like 24 times. To have "enough" passive income, u probably need a huge sum considering the yield is below 4% at most
2. There are better ways to earn passive income monthly that can potentially be higher than from SSB
3. SSB is a good addition, but being the core probably might not be enough

It could be a good source of passive income as it is virtually risk-free. However, if you are looking at building a passive income you can live off, Singapore Savings Bond would not be the best option as it provides relatively low returns. Perhaps reading about its advantages and disadvantages could help you consider other options.

Passive is indeed true, safe tool to use as well.

Sure, it is a good idea. However, it seems the interest rate trend is down from this point of time. There might be some other slightly riskier but better options, but depends on your risk appetite.