Post Interview Thank You Note
 

I would like to send the thank you notes but forgot to ask for the emails of the interviewers.

Is it very bad form to request them from my contact point (HR Dept) with the company?

You can probably ask hr to forward to the email to them. Hr wouldn't be too keen to release their email to you. Also I think most interviewers don't really like to receive such email as they usually reject my request for email and ask me to liaise with hr. It's more common as a technique used in US due to their culture. In Singapore you might seem like you're trying too hard to impress.

I actually dropped hr an email to ask for the interviewers' email addresses so I can drop them a thank you email, then hr replied me that they will be glad to help me convey my thanks to the interviewers. no harm saying thank you(: although it seems a bit forced? but it's part of the whole job application process I guess..