Dear All,

We have been doing multilayer metal core heat sink PCBs for the last many years. Recently we received a requirement to fabricate a multilayer metal core PCB with Alumnium 6061 core with 10 rigid layers. The customer drawing calls for hard anodizing of the Aluminum core after drilling of the Aluminium sheet. We were earlier doing normal 6061 Alumnium sheet without hard anodizing. We have been using Arlon 44N prepreg with about 85% resin content for filling the holes and cavities of the core. We use about 4-5 plies on either side of the core.

But with this hard anodized Aluminium core, we have some increased internal rejections due to delamination. Delamination is found between anodized surface and the prepreg. Can you pls share your views on this or the alternate method of fab other than using Arlon 44N. We are also thinking of epoxy filling.  Would be grateful if you could share your comments on this.

Rgds

Pradeep