PCB Finishes: Acid Copper DC Electroplate

Related Pages:

• ENIG, ENEPIG, Electroless Gold, Immersion Silver, Electrolytic Palladium
• MEC Surface Treatments

Acid Copper for "Via filling" Via Filling connects the different layers in buildup technology (stacked vias and vias in pad) manufacturing, enhancing the long-term reliability of the PCB and the package.

Thru-Cup EVF-R

EVF-R is a unique DC (direct current, no pulse) acid copper plating system that is capable of filling blind vias, connecting layer 1 to layer 2 and occasionally to layer 3. It is designed to plate aspect ratios of 1:1 or less. With diligence and current time manipulation, the EVF-R system could be effective in plating aspect ratios higher that 1:1, (vias whose depth exceeds the diameter of the ablated hole).

It is made up of a combination of a set of organic additives that work with a specific acid to copper ratio in the bath. The organic components include a brightener (accelerator/grain refiner), a carrier (a wide range suppressor) and a leveler (a unique surface suppressor). All components are readily analyzable using CVS. EVF-R does not require any additives in the pre-dip.

For best performance, the chemistry must be augmented with solution dynamics that can preferentially maintain the leveling component at the surface in contrast with the bottom of the via. The leveling component would suppress plating on the surface and allow plating to be accelerated in the bottom of the via.

The EVF-R plating sequence must be preceded by a low surface tension, high wetting capability acid cleaner. The function of the cleaner is to evenly wet the hole and facilitate the removal of any entrapped air that may interfere with plating. In addition, the cleaner will also remove any oxidation from the surface to be plated.

When setting up the EVF-R bath, cell design, solution dynamics and appropriate rectification must be optimized for best results.

The choice of current density (ASF) and dwell time are to be determined based on the degree of difficulty (hole diameter vs depth). Occasionally it may be necessary to increase the current density at the back end of the plating cycle.

Thru-Cup EVF-N

EVF-N plates copper in through-holes and blind vias simultaneously, reducing process time by 50%. It delivers exceptional performance for blind via diameters smaller than 150 micrometers.

Designed for soluble anodes, it is suitable for both pattern and through-hole plating. The process uses DC current, which minimizes both equipment cost and chemical use. Thru-Cup EVF-N is a unique organic additive system, which fills blind vias with electroplated copper using vertical plating equipment.

Additive components are readily analyzed using CVS and Hull cell techniques. The organic additives are very stable and do not require regeneration. Carbon treatment is recommended at a frequency of 2000AH/L of bath (approximately annually). The ratios of the inorganic components are different from traditional acid copper plating.

Thru-Cup EPL
A "High Throwing Power" acid copper additive for printed wiring board plating applications. It was engineered for high aspect ratios with fine line circuitry. It has the simplicity of DC plating with results that can easily compete with the more complex waveforms of pulse plating. The chemistry is very stable and does not require continuous regeneration.

The process produces a fine-grained equiaxed copper deposit. The leveling capability of Thru-Cup EPL overcomes irregularities on the substrate and does prevents nodule growth. The deposit is bright and ductile with excellent elongation, tensile strength and metallurgical properties. Thru-Cup EPL can maintain these metallurgical properties plating as low as 5 ASF (0.5 ASD) and as high as 25 ASF (2.5ASD).

Thru-Cup EPL is a two-component system: the carrier controls deposit thickness uniformity, and the brightener is the grain-refining additive. The solution components and additives have a wide operating window and are easily controlled by standard analytical methods.

Thru-Cup EPL is compatible with both air agitation and airless agitation (Eductor). It is also compatible with "EZ-PLATE." EZ-PLATE is a plating system that uses insoluble anodes with copper regeneration in a vertical plating mode. The anodes are titanium coated with iridium oxide and a patented synergy coating. The copper regeneration is a patented process that uses the bath chemistry with air sparging to dissolve copper external to the plating cell.

Uyemura Thru-Cup EPL Acid Copper and ENIG Pass More Than 2000 Cycles of IST Testing

Thru-Cup ETN
An acid copper additive for printed wiring board plating. It is ideally suited for vertical conveyorized lines where plating speed is Critical, and plates with current densities as high as 40 ASF or 4.0 ASD.

The process produces a fine-grained equiaxed copper deposit. The leveling capability of Thru-Cup ETN overcomes substrate irregularities and does not allow nodule growth. The deposit is bright and ductile, with excellent elongation, tensile strength and metallurgical properties. The chemistry is exceptionally stable and does not require continuous

Thru-Cup AC-90
A single-component acid copper additive system designed for simplicity. It is a mixture of carrier and brightener that has a wide operating window for general-purpose plating. The additives are mixed in the proper ratio for use as a single component system.

Thiourea-Free High-Performance Cleaners

Thru-Cup MSC-PS
MSC-PS acid soak cleaner removes organic residues, including light oils and oxides, and activates copper substrates prior to plating. Low surface tension makes it particularly suitable for high aspect ratio holes and small diameter blind vias. It wets blind vias thoroughly, facilitating highly uniform blind via filing using Thru-Cup EVF-R or Thru-Cup EVF-N. MSC-PS is highly recommended for acid copper pattern plating, as well as ENIG and ENEPIG. It is an excellent cleaner for PTH acid copper. MSC-PS acid cleaner rinses well and will not damage dry film or soldermask.

ACL-634 is a through-hole cleaner for electroless nickel / immersion gold. This acid-type soaking cleaner is well suited for the pretreatment of electroless Ni/Au processes with NPT (Non-Plating Through Holes). ACL-634 removes palladium from NPTH, will not damage permanent resist, and rinses well with water.

Palla-Clean MPC-200
MPC-200 is a mild alkaline palladium cleaner / stripper for electroless copper processing. It removes palladium residues from epoxy and copper surfaces, and will not etch copper. The cleaner is an excellent pretreatment for ENIG where palladium would otherwise allow nickel to deposit in the NPTH – it is a more efficient, and superior alternative to masking the palladium. The MPC-200 is environmentally friendly and odor-free; baths are easy to control, and require only simple waste treatment.

Thru-Cup ACL-007
ACL-007 multi-use acid soak cleaner cleans and activates copper substrates prior to plating. It removes organic residues, including light oils and oxides, and is highly recommended for use with the KAT and MNK processes. ACL-007 is a superior, time-proven surface preparation for microetching; it rinses well, and will not compromise soldermask.

Thru-Cup ACL-067
ACL-067 acid soak cleaner for final finish and acid copper cleans and activates copper substrates prior to plating. It removes organic residues, including light oils and fingerprints, as well as traces of oxidation. It also acts as a wetting agent. ACL-067 is chloride-free and is used in combination with peroxide etches. It is highly regarded as a pretreatment for ENIG, ENEPIG, immersion silver, immersion tin and acid copper, and is an excellent surface preparation for microetch. ACL-067 is compatible with dry film resist and rinses easily.

Thru-Cup ACL-839
ACL-839 is a high performance acid soak cleaner for cleaning and activating copper substrates prior to plating. It has excellent wetting properties and rinses easily with water. ACL-839 was developed specifically for flexible boards, and is ideally suited for fine pattern and through-hole cleaning. It will not damage soldermask, and is an ideal ENIG pretreatment.

Palla-Clean MPC-300
MPC-300 is Uyemura’s newest cleaner. A mild acid formula developed for NPTH cleaning, it strips palladium from through holes and is compatible with dry film resist. It will not etch copper.


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