The adhesion of the overmolding plastic with the substrate is of course usually a relevant specifications in many applications. The issue is that the adhesion of a molten plastic with metal is intrinsically close to 0, broadly speaking. Depending on the nature of the polymer and those of the metal substrate, a specific treatment might be applied to trigger the adhesion.

Some internal studies have shown that a good adhesion between our Tecnoflon FKM and metal can be obtained during molding and curing provided a specific metal surface treatment and the use of a primer. This is well documented in this presentation.

For some E&E applications, a specific chemical etching process is applied on the metal with the objective to get a "nano-mechanical locking". This Nano Molding Technology (NMT-one slide, NMT-thesis) developed and patented by Taisei Plas was successfully used these last years by some of our customer(s). 

There are alternatives like the AMALPHA process from MEC (https://www.mec-co.com/product/amalpha/en/about/feature/) or the TRI SYSTEM from Toadenka in which a nanofilm formed by a surface treatment of the metal enables a very good adhesion when overmolding.