For $29/mo, we provide access to advanced level technicians who will answer your questions on any Macbook board related matter to the best of their knowledge promptly & walk you through how to solve your problem so you can deliver a working board to your customer.
I use the RT 1 when going small. It is 0.2 mm. But you can get a 0.1 mm. It is called RT 1NW which means it is non-wettable and thereby will not take solder.
This brochure lists all available tips along with the order number that you can easily use for searching at Mouser or Farnell or other suppliers.