Thank you for the details. But I think signing a bond and submitting your original certificates is a little risky business. If possible, try to talk to any employee of that company and find out about its work pressure, appraisals and promotions, and clients. Go through the website of the company to determine how old the company is, etc.
Questions to Consider
There are other questions that come to my mind which you can ask yourself or get information from a person who is working there:
1. Why do they want you to sign a bond? What are the reasons?
2. Since you will be submitting your original documents, what is the guarantee that they will be safe?
3. Since you are signing a bond for one and a half years, that means you will not be able to leave the company. However, in case of unavoidable circumstances (such as shifting to another state) where you have to leave your job, will they return your documents, provide your full payment, and issue relieving documents?
4. If you are not happy with the kind of profile given to you, or if your boss is not good, or if during the interview they described a different job profile and you are actually doing a different job, in these cases, will you be able to leave the job?
5. If you leave the company within this one and a half year span, is there some kind of money that you need to pay the company?
I think you should consider the points above and make your own decision.