BondFilm

BondFilm is Atotech's simple, cost effective process for improved inner layer bonding. From the standpoint of the chemical process, the inner layer undergoes a combination of micro-roughening and treatments in order to form an organo-metallic layer on the copper surface. Typically, the BondFilm process will microetch the copper to a depth of 1.2 to 1.5 µm, while simultaneously converting the copper at the surface (200 - 300 Angstroms) to the desired organo-metallic structure. The visible result is a homogenous layer that is an medium-brown color. Although etching of the copper will continue with immersion time, growth of the actual BondFilm adhesion layer is self-limiting, reaching a maximum thickness as equilibrium is reached between the formation and dissolution of the layer itself.

During high temperature pressing operation, the BondFilm surface provides both mechanical and chemical bonding with the prepreg material.
 

BondFilm - The Process

The BondFilm process consists of only three steps, which can be accomplished in either an immersion or conveyorised mode:

Alkaline Clean - Correct cleaning of the copper surface is a necessary prerequisite for the formation of the surface. BondFilm Cleaner ALK is an effective and simple alkaline cleaner for removal of soils and contaminants from the inner layer surface, this step is more than capable of removing fingerprints and small photo resist residues.
Activation - Following the cleaning step, BondFilm Activator pretreats the Copper to create the proper surface conditions necessary for the formation of the adhesion layer itself. In addition to uniformly activating the Copper surface, this stage also protects the BondFilm process solution from contamination caused by "drag-in".

BondFilm - The activated copper surface is then treated in the BondFilm Solution to form the organo-metallic coating. This component system offers a high degree of operating flexibility with simplified process maintenance.

Typically, the entire BondFilm process, including rinsing and drying, requires only approximately three minutes for treatment in the conveyorized (horizontal) mode.

Features and Benefits

• Consistent bonding enhancement
• High copper loading (typically 28 g/l and 40 – 45 g/l for BondFilm HC)
• Simple, dependable, low temperature process
• Wider operating window
• Ideally suited for conveyorized application
• Greatly reducing the formation of "pink ring" and "wedge voids"
• Optimized for Laser Direct Drilling applications
• Lower cost of inner layer processing by improving yields
• Ideally matched chemistry and equipment for Atotech's Horizon system