It is always challenging to manufacture RF microwave PCB. During manufacturing certain considerations have to be adhered to. These are like heat management within the board to ensure the considerable thermal stresses of PCB assembly. The spacing features should be taken care of and last but not least choosing the proper material is a key factor.
Based on the diversified application of RF Microwave PCB, So many manufacturers are in the race to offer the said PCB. But it is always advisable to have proper market research to reach a competent manufacturer.