Can floor tiles be laid direct onto chipboard flooring without a plywood overlay first?

Never tile straight on to chipboard flooring or plywood overlay as these are problematic substrates that move and warp, always use hardi backer boards as they are water resistant and heat resistant and an excellent substrate to enhance adhesion. Always use a minimum 6mm backer board on floors stuck down with a highly flexible adhesive and screwed at 150mm centres then tape the joints and spread over tape with adhesive.....once set you will be good to go and will never have a problem with your floor and this method will provide a lifelong tiling installation.

MW Smith has given good advice so cannot say much more, other than if using backer board please leave a 2 to 3 mm gap between boards for expansion.