Metal Organic Decomposition Inks for Electromagnetic Interference Shielding

Michael Vinson, Sima Hannani, Melbs LeMieux, Brett Walker
Electroninks
TX, 78744

The goal of utilizing conductive inks to compliment traditional metallization approaches in semiconductor packaging applications is to enable ultimate design, functionality, and capital expenditures (CAPEX) flexibility through additive manufacturing without sacrificing performance or reliability.

Traditional metallization processes include the sputtering method, a Physical Vapor Deposition (PVD) technique, and plating among others. PVD and electroless plating are currently the most used method to deposit a metal film in semiconductor packaging industry and it requires a complex, multi-step process. The metal films and patterns are required for electromagnetic interference (EMI) shielding and SAP among others. These processes have certain limitations related to technology factors including limits on panel area, uniform thickness on complex 3D shapes, temperature, patterning, health, and environmental factors as well as economic factors (throughput, CAPEX, footprint, maintenance, material waste and energy usage).

Alternatively, technology is seeing a shift to jettable (aerosol jet and inkjet) or sprayable conductive inks for conformal shielding and additive, 3D metallization. This approach brings about substantial total cost of ownership and throughput advantages that will be reviewed in this paper as the ink-based processes (spray/jet) does not require vacuum and has relatively low process temperatures (at or below 180C in most cases).

Metal complex conductive inks can be printed via various digital printing techniques such as aerosol jet printing, inkjet printing, and spray coating. The inks can be jetted or sprayed on various substrates e.g., 3D packages, wafers, chips, boards, and housings to provide a high-performance shielding layer that is reasonably priced and has outstanding reliability qualities for the semiconductor packaging industry.

In this paper, we will review different printing techniques, and spray coating. We will review 5-sided metallization to provide shielding via spray coating, film performance parameters including coating thickness uniformity, EMI shielding effectiveness, adhesion to different substrates, and reliability. Another area of focus in this paper is using the silver metal complex inks in semi additive manufacturing as the silver MOD inks make an excellent seed layer for plating processes. We will discuss the spray coating process and performance of the silver film as the seed layer.

MOD inks have shown versatility, production readiness and enhanced performance in IC packaging. With the introduction of a new global benchmark copper MOD ink, we can expect to see the adoption of these particle free inks accelerate soon.