IPA is great for cleaning pcb's but the good stuff can be quite expensive. The other option is to get actual flux remover, such as this stuff: [https://electronics.microcare.com/product-category/flux-removers/|MicroCare Flux Remover]. This stuff is better than IPA for removing flux. There are different brands and these can usually be found in electronic stores or can probably be ordered online too.
From what I [http://www.differencebetween.com/difference-between-isopropyl-alcohol-and-vs-denatured-alcohol/|read], denatured alcohol should work for flux removal but I have never tried it myself.