PCB Final Finishes: EPIG

Electroless Palladium / Immersion Gold (EPIG)

The EPIG nickel-free PCB final finish is ideal for high frequency applications; it has opened a wide, new design avenue for designs with reduced spacing.

The EPIG process deposits palladium directly onto copper. Eliminating the nickel means reduced build-up on circuits, and circuits can be controlled with smaller geometries. It’s a perfect fit for applications involving smaller features and clearances.

    EPIG offers unique and significant advantages for microwave applications, flex circuits, and end users requiring high purity levels. These advantages include:
  • Nickel-free process prevents fracture on bending for flex circuits
  • Maintains solderability and wire bondability to copper circuits
  • Short process time
  • No EN to pose corrosion issues
  • No skin effect on low current, HF applications
  • Non-magnetic
  • Suitable for tight lines and spaces
  • Easy to visually inspect
  • Reworkable in most circumstances

Read “Characteristics of EPIG Deposits for Fine Line Application” by Don Gudeczauskas, George Milad, et al. in the Uyemura Library.

Electroless Palladium

Talon 3 is the electroless/autocatalytic palladium bath for HF applications. It deposits directly on copper, zincated aluminum or electroless nickel. The palladium surface is gold or aluminum wire bondable when topcoated with immersion gold, and solderable as-plated. The EPIG finish enabled by Talon 3 solders perfectly after 8 hours of steam aging. Talon has a low operating temperature, and is highly stable and tolerant to impurities (nitrate, copper, nickel). It is the most cost-effective palladium for EPIG.

Also available: Talon 1, Talon 2.2.

“RAIG” Immersion Gold

TWX-40 Reduction Assisted Immersion Gold plates, in one step, up to 4-8 μin gold. Using both immersion and autocatalytic deposition, deposits are exceptionally uniform and low in porosity, minimizing palladium’s exposure to the environment. TWX-40 is the chemistry of choice for applications requiring heavier gold. It is also valued for its ability to withstand corrosive atmospheres and light pollutant environments, and for its fast deposition rate.

Also available: TAW-66, TAM-55.

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