Open a link in new tab, not working target='_blank'

This is a PHP code, in need to open a link in new tab.

But i tried target='_blank' in all the areas not working.

return "<a href='".get_home_url()."/out/".$post->ID.
 "/".$GLOBALS['CORE_THEME']['code_link']."/' title='"
.$post->ID."' rel='nofollow' class='btn btn-primary cbtn'>"
.$CORE->_e(array('button'))."</a>";

I think its calling the link from code_link not sure exactly.