Cleaner – Epithas® MCL-10 acid soak cleaner removes surface oils and contamination and wets the surface to enhance solution transfer. (Also available: MCL-067 CMOS-compatible, low-foaming acid soak cleaner.)
Micro-etch – removes copper surface oxide and roughens the copper, enhancing nickel adhesion.
Acid rinse – ensures that the copper surface is oxide-free and residual copper has been removed.
Pre-dip – minimizes acid dilution of the subsequent activator bath.
Activator – Epithas MCT-14 is an extremely stable activator for copper and copper alloys. It is well-suited for activating isolated copper pads for subsequent nickel deposition. The MCT-14 immersion reaction bath displaces copper and seeds it with palladium. The palladium initiates the subsequent autocatalytic nickel plating step, electroless nickel. The electroless nickel is an autocatalytic process. The nickel layer acts as a diffusion barrier that is solderable or aluminum wire bondable.
Epithas Acid Activator activates difficult to plate metal surfaces prior to the subsequent metal deposition. Advantages include no fumes, extended bath life and easy operation & maintenance.
Electroless nickel – NPR-18 electroless nickel is a mildly acidic plating bath for fine line circuitry in silicon wafer plating. Bath formulation allows deposition of electroless nickel without bridging. Highly stable, easy to use; 6-8% phosphorus content as-plated.
Epithas NPR-24, is a mildly acidic electroless nickel formulated for fine line circuitry in silicon wafer plating. This bath allows the deposition of EN without bridging; easy to use and optimized for automatic solution control using the Uyemura STARLiNE DASH controller.
Immersion gold – TDS-20 cyanide-free immersion gold bath was engineered for surface mount applications and wafer plating. Neutral pH; will not corrode the underlying nickel. Provides excellent solder joint reliability, including small solder balls. The thin gold coating maintains long-term solderability and prevents nickel oxidization and passivation.
Autocatalytic gold – Epithas TMX-16 electroless gold for silicon wafers is cyanide-free, with a neutral pH. Ideal for surface mount and wafer plating. Will not corrode the underlying nickel, thus it provides excellent solder joint reliability.
CMOS-Compatible Process for Copper Metallization
Cleaner – Epithas CACL-067 acid soak pretreatment for silicon wafer plating, including SOI wafers.
Micro-etch – Epithas LEC-19 removes naturally-occurring oxidation from aluminum and aluminum alloy surfaces. Pretreatment for electroless nickel on aluminum for silicon wafers, including SOI wafers.
Activator – Epithas MCT-14 is a highly stable activator for copper and copper alloys. Immersion reaction bath deposits palladium only on the copper surface. The palladium initiates the subsequent autocatalytic nickel plating step, electroless nickel.
Electroless Nickel – Epithas NPR-18CM – for wafer plating, including SOI wafers, involving fine line circuitry.
Read about our UBM process for aluminum
Read Under Bump Metallization: Some Economical Alternatives published in US Tech.