Do a project manager sound in project integration and coordination need to be sound in the technical aspects?

A project manager is preferred to have some basic technical skills and knowledge for the project (s)he is managing, and that is in order to be able to understand the tasks, and communicate with project team and impacted stakeholders.
But, this does not mean that a project manager needs to be a guru in the field (s)he is managing, as the main skill needed for a project manager is people skills (negogiation, communication, motivation, empathy, team work, etc...)

No, he/she doesn't need to be a technical expert in the subject matter. He/She needs to be an expert in project management to succeed in achieving project goals within budget and within planned time frame.

This is an additional benefit...however if we go through any PM training...there is no where written (i dint read at least) that it is mandatory ....

A project is an entity and it's success is translated into a working and fit to purpose device/machine/plant/software.  I shall just ask a question: How do you know whether the solution you propose is fit? Just asking the stakeholders? How do you support/explain to project sponsor your technical proposal. if do not know something more than basics?

yes-----this is one of important aspects to have a Successful project

It's good for a project manager to have a techinical background.

Yes i agree with you totally.
But i mainly believe, a PM's main role is in Project Integration and Communication.
Even though if he is Technically sound, if he can integrate and communicate thoroughly, he can successfully lead the Project.

Sure its like Palm and back of the hand