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The key to uniform thickness distribution is uniform current distribution. Fundamental laws of electrochemistry (i.e. current distribution) do not always allow for a uniform deposit. Direct current always seeks the path of least resistance from the anode to the cathode (substrate/workpiece). As a result, paths of least resistance, such as sharp edges or protrusions, will receive a heavier deposit, while areas such as internal corners/radii receive a significantly less amount of deposit.

One consideration for deposit uniformity is ensuring an even distribution of plating solution over the area being plated. For best results, the plating solution should be pumped to the work area through the plating tool and uniformly distributed over the work area. An uneven distribution of fresh solution over the work area will result in an uneven deposit thickness.

In order to achieve uniform deposit thickness, a well-designed, properly-used plating tool is critical.

Other factors to consider:

• The thicker the deposit, the more difficult to plate a tight tolerance.
• It is easier to accurately plate on a small area than a large area.
• It is easier to hold tight tolerances on simple shapes with no interruptions than complex shapes or shapes with interruptions or a large percentage of high current density edge areas.
• Mechanical movement of the part or the anode is going to produce more consistent results than hand movement.
• It is easier to accurately plate a low thickness on a small area than to plate high thickness on a large area.

(Source: Uniform Thickness Distribution of Brush Plating)

A good non-destructive test for evaluating the adhesion of electroplated deposits, unfortunately, is not available. All good tests at least partially destroy some of the deposit on the workpiece, even though there is excellent adhesion. This requires a reliance on some indirect and less-than-ideal tests. It has been found, however, that use of some or all of the following five test procedures assures, in a majority of the cases, adhesion sufficient to meet the demands of the application:

1. Chisel, Knife and Scratch Test
2. Grind and Saw Tests
3. Bend Tests
4. Tape Test (nondestructive)
5. Visual Test (nondestructive)

Read Plating Clinic: Adhesion of Brush Plated Deposits for rundowns on each test.

(Source: Plating Clinic: Adhesion of Brush Plated Deposits)

There are a few things that will affect the life of your cleaner baths. The first concerns the condition of parts that you are putting into the bath. If the parts are dripping with oil/grime, your cleaner isn’t going to last very long because it will have a lot to clean up. This is easily fixed by lowering the amount of oil used to ship or manufacture the parts. Additionally, depending on the type of cleaner you are using, adding a weir to your cleaner tank may help lengthen bath life by removing oil from the top of the bath.

The quality of the water being used can also affect the cleaner bath life. Each of the broad categories of water (hard, soft and purified water) have different properties that may affect the bath life. Baths with purified water will last the longest, due to the fact that nearly all of the dissolved minerals have been removed, leaving pure, clean water.

The type of cleaner may also affect the life of a cleaner bath, though this will vary case-by-case. There are many types of oils and compounds used to manufacture parts, and for every oil and buffing compound, there is a surfactant or soap that will clean it. For instance, paraffinic oils can be very difficult to clean.

Talk with the oil supplier and cleaner supplier to find the best solution and check at what temperature the cleaner should run—oftentimes, cleaners will have a range at which that they can run.

(Source: Plating Clinic: Cleaner Bath Life)

The debate over dyed versus non-dyed chemistry is ongoing. The primary difference between the two systems is the characterization of the chosen leveler. Levelers that have color (purple, blue, yellow, green, etc.) tend to be classified as “dyes.” Non-dye levelers tend to produce additives that are colorless or slightly yellow. Whether dyed or non-dyed, virtually all levelers are quaternary amine compounds. Brighteners and carriers are consistent between the two systems and from supplier to supplier. What does change is the chosen leveler and the ratio of brightener components to leveler components.

(Source: Plating Clinic: Non-Dyed Versus Dyed Acid Copper)

1. Use a portable barrel that has button contacts instead of dangler contacts.
2. Completely submerge the barrel so all the air is removed. The floating parts will make contact with the buttons at the top of the barrel.
3. Using a slow rotation speed, copper plate the parts until they sink in the barrel and maintain contact with the buttons in the bottom of the barrel.
4. Rinse thoroughly and then transfer to the nickel plating solution.

(Source: Plating Floating Plastic Parts)