Preparing a Copper Surface prior to a Resist or Plating Application

Preparation of the copper surface in PCB fabrication is key to adhesion of resists and any subsequent plating operation. The topography that is created provides a mechanical bond which improves as micro roughness increases. Scratches from scrubbing, cause inconsistent resist adhesion, resulting in increased opens and shorts as the line width and space goes down. To fabricators, this means a lower first pass yield and higher costs of operation due to increased scrap rates. Microetchants, such as sodium persulfate, have been replacing scrubbing operations for the past several years so that finer features can be developed with resists.






Brush Scrub

Pumice Scrub


TechniEtch 1118

TechniEtch 1688

TechniEtch 1118 - Better Typography at a Lower Cost

TechniEtch 1118 is a proprietary replacement for persulfate and peroxide based microetches. It can be utilized prior to application of plating and etch resists or prior to copper and electrolytic or electroless nickel. TechniEtch 1118 is designed to produce better topography with lower etch depth and with higher copper loading levels. This translates into more panels per volume of etch solution.

The calculation below shows how much more:

When compared to generic sodium persulfate, TechniEtch 1118 doubles the number of panels that can be processed per liter and cuts in half the amount of solution sent for treatment.

Copper Holding Capacity: Listed below is the dump point for different generic microetches vs. TechniEtch 1118.

Chemistry..................................gm/L Cu

TechniEtch 1118.................................45

Sodium Persulfate.........................15-25

Mono Potassium Persulfate................30

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TechniEtch 1688 - High performance Copper Micro Etch for Fine Features

TechniEtch 1688 is an organic acid based copper micro etch engineered to produce optimum adhesion of polymer coatings. TechniEtch 1688 improves yields of fine features with plating resists, etch resists or solder mask, especially where adhesion is critical under harsh conditions like HASL, ENIG, and Immersion Tin. TechniEtch 1688 provides an optimum uniform copper surface appearance desired for AOI detection.

Formulated to be used in horizontal spray applications for a wide variety of products, the TechniEtch 1688 processing sequence is as follows:

Solder Mask and Dry Film Adhesion: Adhesion is critical as solder mask dams and dry film structures go below 75 microns. The mechanical bond sites created by the TechniEtch 1688 dramatically improve adhesion and the ability for these fine features to survive developing and plating, even with harsh chemical operations like immersion tin and ENIG.

High AOI Yields: TechniEtch 1688 not only provides a consistent surface for AOI, but the resultant color is optimum to eliminate false rejects typical with competitive micro etch chemistry.

High Copper Capacity: For feed and bleed operations, the recommended copper level is 35 gm/l. For batch mode operations, copper can be operated as high as 50 g/l/.

Controllable Low Etch Depth: Typical etch depths are 0.8 to 1.0 microns (~30-40 micro inches). Several studies have been done demonstrating that the surface topography is consistent even with changes in temperature, Cu concentration and equipment set up.

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Roll-to-Roll Wet Process Technology

Electroplating for flex circuits

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