Thanks for the replies dudes, for the moment select this product:

https://www.ebay.es/itm/BARNIZ-AISLANTE-TRANSPARENTE-50ml-PROTECTOR-PCB-contra-corrosion-oxidacion-Q033-/201558280020?utm_medium=cpc&utm_source=twenga&utm_campaign=twenga&utm_param=eyJlcyI6MCwicyI6NTMzODU0NywiY2kiOiIwNWQ0OTJkYzNkYjQ2MTFhZmMxZmZhZGU0MjljYTFjOSIsImkiOiI1ODU2ODMyMDAzNzYxMTEyMDIyIiwidHMiOjE1Mjc0MjU3MzYsInYiOjMsInNvIjoxNTAwLCJjIjo2MzN9&rmvSB=true

of course not apply to heatsink only the pcb, at the future post here the pics.