Typical Process Flow for Multilayer Flip-Chip Substrate Fabrication with the Use of AIT Build-Up Film Adhesives Coated on Copper:

Typical Process Flow for Multilayer Flip-Chip Substrate Fabrication with the Use of AIT Build-Up Film Adhesives Coated on Copper

• The need for thin Copper on BUF film is to facilitate the de-smearing of the vias without damaging the build-up film, depending on the properties of the BUF polymer’s molecular chemistry. It may not be required depending on the processing conditions and the specific BUF.
• For AIT BUF7880 and BUF7860 that are not loaded with CTE fillers, surface roughness induced by the less rigorous de-smearing process may be minimal.
• The BUF lamination pressure, temperature, and curing time are different from ABF and other build-up films. They typically require less pressure and time.

Note: Only one side of the build-up substrate processing is shown for ease of visualization.

Vacuum-Assisted Build-up Film Adhesive with Thin Copper to Core Substrate Lamination (Same for Multi-Layer Build-up Lamination)

The following is a pictorial representation of the basic processing of build-up substrate fabrication on core substrates when the build-up film adhesive has a thin copper for de-smearing assistance: