Think & Tinker Instrument Prototyping

Think & Tinker, Ltd.
P.O. Box 1606, Palmer Lake, CO 80133
Tel: (719) 488-9640, Fax: (866) 453-8473
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Acid-Copper Electroplating Module Model 1000 Manual
Chemical Analysis - Hull Cell III

Examine the test panel.
A properly adjusted bath will yield a test plate that looks something like:
If the test plate shows burning that extends to current densities lower than 45 amps per square foot (ASF) or if the region below 40 ASF is anything but mirror bright, the plating bath needs attention. To save time (and brass plates), check the copper and sulfuric acid levels with the a titration analysis kit and adjust if necessary.
Once you have ascertained that the copper content, sulfuric acid, and chloride ion (black anode deposit) are at acceptable levels and that the copper to acid ratio is to within 10% of optimum, run another test plate. If the board shows dullness or rough plating in the low current density area, the bath is low on brightener.
Using the syringe filled with brightener, add PCM+ to the sample bath. If the test plate run above was slightly dull in the low current area, add 0.4 milliliters (cc) of brightener to the sample bath and run another test plate.
If the first plate was very dull or rough add 0.7 milliliters (cc).
Continue adding brightener 0.4 cc at a time until you achieve an acceptable test plate. Record the total amount of brightener you added to achieve acceptable results.
Multiply this number by the scaling factor A calculated at the beginning of this section to determine the amount that should be added to the plate through module (A_{11 gal} = 156, A_{22 gal} = 312)
Repeat steps 1 through 8 until acceptable results are achieved.

Do not use a drawn sample for more than 3 Hull cell tests. If more than 3 are needed, pour the used sample back into the plating tank (REMOVE CORRUGATED ANODE FIRST!!!) and draw a new sample.
Once the plating bath is properly adjusted you may proceed with your board plating.
If the plate refuses to brighten with the addition of more brightener, the bath has either become polluted with excessive organic plating by-products or the individual components of the additive system are out of balance. Performing a dilution Hull Cell test is about the only way, short of cyclic voltametric stripping (CVS, think $12,000 or more), to accurately determine the root cause of the problem. If the bath is found to be contaminated, it should be carbon treated to remove the bulk of the dissolved organics.

Proactive Brightener (HTL) Maintenace
The brightener is constantly being consumed by the plating operation at the rate of approximately 0.50 milliliter (cc) per Amp hour. Before plating each board, determine the amount of brightener to add. This will help insure that the bath is always operating at an optimum level and should reduce the need for large periodic brightener adjustments.

To determine the amount of brightener to add:

Calculate the total area to be plated. Be sure to include both sides of the board as well as robber bars and any other areas of exposed copper. AREA
Calculate the total plating time. An acid copper plating bath based on the Lea Ronal PCM+ additive system deposits 0.0011" (1.10 mils, 28 microns, 0.81 oz) of high ductility copper in 1 hour at 20 ASF(Amps per Square Foot). TIME
In a well maintained bath, Lea Ronal Copper Gleam PCM and PCM+ are consumed at a rate of 0.25 to 0.5 ml of brightener per Amp-hour of plating. To calculate the total probable consumption use:

PCM+ to add (ml) = AREA x TIME x 20 ASF x 0.35

Established 1990

On the web since 1994