A method of forming thin, uniform braze joints is effected through the use of curtain coating. Braze powder is admixed with a liquid polymeric binder to form a slurry. The slurry is forced through the slots in a curtain coating head and deposited on at least one of the metal surfaces to be bonded together. The method has particular utility for bonding fin/plate sections of a heat exchanger where the fins have a U-shaped cross section. The slurry is deposited on the top portion of the fin and the side portion of the fin and wiped from the top portion leaving braze material primarily on the side wall portion. When the plates are contacted to the fins and heating performed, a bond is effected with maximum plate-to-fin contact for high heat transfer and a strong braze joint.