FAQs on Plating and Final Finishes

How can we consistently meet IPC’s 4552 Rev A specification?

Uyemura’s TWX-40 bath uses immersion and autocatalytic modes of gold deposition to produce a thicker, lower porosity gold deposit that minimizes palladium’s exposure to the environment. The result is zero corrosion, and compliance with the specification. ENIG and ENEPIG platers now have the option of depositing the heavier gold many designs call for – up to 8μin – in one step, while not risking the corrosion that has historically been associated with heavier gold. The very nature of the displacement reaction inherent in all competitor products is a primary cause of the corrosion that TWX-40 avoids with its unique mixed reaction process.

What are ENIG’s main advantages for printed circuit manufacturers, and what component assembly methods are compatible with it?

Wave soldering, solder fusing and wire bonding are all compatible with electroless nickel immersion gold finishes. ENIG creates a highly solderable surface that won’t discolor, or tarnish, and it provides exceptional electrical continuity. The nickel component provides a barrier against copper diffusion and guards against contamination of the solder during soldering and re-work. ENIG also contributes EMI shielding.

What is meant by “direct gold” and where is direct gold used?

Direct gold is application directly on copper – without nickel. Direct gold is used primarily wherever RF interference is a factor.

How can Uyemura’s ENIG be gentler on solder masks?

Because we run at low temperature, and our ENIG formula is chloride free.

What are the most compelling advantages of Uyemura GT platinized anodes?

No micro-pores, and no micro-cracks—thus longer life. Also, these rigid frameless platinum anodes can be double or single-sided, and are manufactured in several mesh sizes. The newest MMO anode technology, and Platinode anode options are described here.

What is “white bronze?”

White bronze is a white version of Miralloy, the electroplating alloy of tin, copper and zinc that’s become the preferred alternative to nickel for many applications. Among these applications are jewelry, zippers, buttons and other products that contact the skin. About 20% of the population has a dermatological reaction to nickel, and no-nickel Miralloy eliminates this problem. White bronze Miralloy is inert, long-lived and tarnish-free. There’s also a lead-free formula.

What alternatives are there to silver and nickel for the connector and electronic component industries, where there’s an issue over intermodulation or tarnishing?

Miralloy, the copper-tin-zinc alloy, produces a bright, white finish and provides excellent corrosion performance, high solderability and conductivity. It is also diamagnetic, and won’t tarnish.

Does “white bronze” also have other uses?

Yes. In addition to being an excellent finish for products such as jewelry and zippers and other consumer products that contact the skin, white bronze is an excellent finish for countertops in medical offices and hospitals, on knife racks and shelving in restaurants, on door knobs – and on bathroom fixtures, changing tables, toys, etc.

Is there a solution to “black pad” or “black nickel” defects in electroless nickel immersion gold used in the PCB industry?

The black pad seen with ENIG processing causes solder joint failure and low shear forces after assembly. It indicates a problem with the nickel bath that causes nickel corrosion during immersion gold deposition. Uyemura’s ENIG process was engineered specifically to eliminate it, while maximizing yields.

Are there alternatives to watts, sulfamate or sulfate-based baths that deliver higher throwing power for electrolytic nickel?

Uyemura’s Thru-Nic process provides substantially higher throwing power for your nickel plating process – users typically experience a 5-fold increase in throwing power over standard nickel systems. Thru-Nic CL is formulated for ceramic IC packages and general metal finishing.

How can we eliminate the need for dummy plating?

Yes. Uyemura’s Nimuden NPR4, NPR6, NPR8, and HDX+D electroless nickel baths eliminate dummy plating and wasted chemistry. When operated with Uyemura’s StarLine Dash NP Chemical controller, the most consistent, most reliable plating results can be achieved.

From an operations standpoint, what's the main advantage of Nickstar decorative black nickel plating, compared to conventional black nickel?

Nickstar can be operated at higher current density to get better plating coverage, specifically 5-8 asf vs. 1-3 asf.

How does Nickstar's cycle time compare to older black nickel?

Nickstar achieves a deep black deposit in 5-10 minutes, compared with 15-20 minutes required by traditional black nickel products.