Nannie is right.
It gets complicated, so you should get an atty.
If the father hasn't had contact in over a year, it is called abandonment. It takes a little longer, you will have to publish the adoption, to see if he comes forward, to dispute the adoption. If he doesn't it will go through with no problem.
If he does try to stop the adoption, take him to court for back child support. Tell him you will drop it if he signs the papers.
My Mom did this to adopt my nephew, and I am getting ready to start the same thing. Both in PA. You will also be issued a new birth certificate.
Good Luck