PWB Processes: ENIG

KAT Electroless Nickel/ Immersion Gold (ENIG)

KAT ENIG is the industry standard for producing uniform mid-phos EN deposits with a thin topcoat of immersion gold, over copper substrates. This PCB finish is highly resistant to corrosion, and is both solderable and aluminum wire bondable. It is an ideal contacting surface.

KAT users never have to contend with “dummy plating.” They also benefit from:

  • A low-concentration, room temperature, chloride-free catalyst
  • A bath that runs at least 10°F below the competition
  • Compatibility with the newest soldermask technology

Use with the STARLINE DASH Controller. This advanced electroless nickel controller is self-cleaning and self-calibrating. The controller modifies the calibration curve to compensate for the accumulation of bath by-products. It maintains a complete analytical record for SPC charting. MORE

KAT has long been the world's highest-performing mid-phos electroless nickel. That, however, hasn't stopped Uyemura chemists from making it better...

MFD-5 palladium catalyst is an activator for the electroless nickel plating of fine pattern PCBs. While traditional activators often have bridging issues when fine patterns are plated, MFD-5 deposits more palladium on the copper, reducing the chance of skip plating and eliminating the potential for bridging between pads. Stable, chloride-free bath operates between 77-95°F; immersion time is 1-3 minutes. Needs charging less often!

Nimuden NPR-4 is an acid electroless nickel plating bath that has been specially formulated for electronic and PCB applications involving fine line circuitry. The special bath formulation allows the deposition of electroless nickel without bridging. This process operates at lower temperatures, which allows for improved resist tolerance. The bath is very stable, easy to use and is optimized for automatic solution control using the Uyemura STARLINE-Ni controller.

Nimuden NPR-8 is a mildly acidic electroless nickel-phosphorus process engineered for electroless nickel / gold plating to selective PWBs with dry film masking. The catalyst, electroless nickel, and immersion gold components have all been improved for greater productivity, and bath life. The NPR-8 bath is highly stable in continuous use, and the phosphorous content in the deposited film remains constant regardless of metal turn-overs.

NPR-8 is chemical corrosion-resistant, especially against OSP treatment chemicals, including pre-treatment, and is ideal with lead-free solders. It is used with TAM 55 gold to produce the highest quality ENIG, with the highest yields, possible today.

TAM-55 advanced immersion gold bath minimizes nickel corrosion, optimizes gold distribution. A special additive minimizes nickel dissolution and thus leaves a robust nickel surface following the immersion gold reaction. TAM-55 protects and maintains the solderability of the electroless nickel in an ENIG deposit. It is ideally suited for use as a solderable finish for small SMT and BGA pads. For maximum compatibility, use Nimuden NPR Series electroless nickel as the underlying deposit for PWB and IC packaging. TAM-55 may be used for both ENIG and ENEPIG applications, allowing a single source immersion gold for plating lines where both finishes are employed.

Gobright® TAW-66 Immersion Gold provides superior performance, with low porosity and low nickel dissolution. It operates at 1 g/l gold metal, and offers high solder joint reliability, with minimal effect on the nickel layer.

GoBright® TWX-40 gold electrolyte plates directly on electroless palladium depositions for ENEPIG processes, as well as optimized ENIG processes. The electrolyte deposits uniform gold films up to 0.3 µm independent of pad sizes and PCB surface potential.

Thanks to its semi-autocatalytic reaction, the Ni/Pd/Au film provides excellent wire bondability, and solderability using lead-free solder. Corrosive attack on the intermediate nickel layer is prevented. For optimum performance, use Uyemura electroless palladium baths as the underlayer for PWBs and IC packages.

KAT SP ENIG for Selective Plating

This modified KAT ENIG process accommodates the processing needed for the selective plating of ENIG and OSP (organic solderability preservative). The nickel bath is sulfur-free and more corrosion resistant. The gold is a much tighter, lower porosity gold coating.

KAT GW Electroless Nickel with Electroless Gold for Gold Wire Bonding

In this process, the standard ENIG deposit is followed by an electroless gold step. Here the gold thickness is built up to meet the requirements of gold wire bonding.

ENAG Electroless Nickel / Autocatalytic Gold

ENAG is a high-performing final finish for wire bondable deposits, and an excellent alternative to immersion chemistry, or ENEPIG. Deposits 120-240 μins of nickel, 8-40 uins of electroless gold. Read "Neutral Auto-Catalytic Electroless Gold Plating Process" in the Uyemura library.

DIG Direct Immersion Gold on Copper

Uyemura's  Direct Immersion Gold process deposits a thin coating of immersion gold directly on the copper substrate. It is the best choice for a solderable surface, eliminating the shortcomings of other finishes.

It is ideally suited for "lead free" higher temperature assembly conditions. The gold coating is 1-2 micro inches (0.02– 0.05 microns). DIG is in direct competition with OSP finishes.

TCU-36 and TCU-41 are two versions of this process that can be custom tailored to meet specific manufacturing needs. Read the article, "Solder Joint Reliability of Gold Surface Finishes for PWB Assembled with Lead Free SAC Alloy" in the Uyemura library.

Electrolytic Nickel Gold

Uyemura offers a broad range of electrolytic nickel processes; sulfate, sulfamate and "high throw" electrolytic nickel. "Thru-Nic" electrolytic gold processes are available for hard or soft gold, depending on customer requirements.

Anodes for Gold Plating

Uyemura offers top of the line platinized titanium anodes for gold plating. The platinum is deposited from a molten bath that avoids micro-pores and micro-cracks found in traditionally produced anodes.


Uyemura PCB finishes lead the world in plating performance. Products include final finishes, acid copper DC electroplate, ENIG, gold wire bonding, electrolytic nickel gold, immersion silver and immersion tin. Also, Electrolytic Palladium.