Copper plating on aluminum

I am using Zincate to plate on aluminum (Cu/Ni). The electroless copper (seed layer) coming this way just fine. But when I am trying to plate an electrolytic copper (phosphate bath)on the top - it is growing but shows very low adhesion and all blistered. May be somebody can help.

Irina,

From the very little info you give I see two possibilities
1- Your pyrophos copper is attacking the zinc underneath the E-less copper flash. Increase time and thickness of flash.
2- Your orthophosphate has reached a point where causes excesive internal stress, so plate blisters and cracks. There is no practical way to reduce the ortho but to discard part and add new formulation.