LDC Solutions -The Four Different Groups:
- Preparatory Solutions
- Stripping Solutions
- Plating Solutions
- Special Purpose Solutions
All LDC solutions are aqueous, which means they are manufactured with water being the primary solvent.
The Preparatory and Stripping Solutions, along with water, contain acids or alkaline materials and sometimes wetting agents or other additives. The Plating Solutions are the most complex solutions. These water based solutions contain dissolved metal salts, wetting agents, chelating agents, stress reducing agents, grain refilling agents, along with many other additives which help make them suitable for the LDC Process.
LDC Solution Shelf Life and Storage Conditions
The Shelf Life of LDC Plating Solutions, when properly stored is indefinite. Tests have been performed on solutions 5 years old with no deterioration in quality noticed. The following are some exceptions:
- Babbitt – 5029 – 6 Months
- CadmiumS – 4803 – 1 Year
- Tin-ZincS- 5030 – 1 Year
- Zinc-NickelS- 3028 – 1 Year
According to U.S. Government Quality Control Standards the following guidelines should be used;
- Preparatory & Plating Solutions – 12 Months
- Alloy Solutions – 3 Months.
All Shelf Life recommendations are based on date of manufacturing which is stamped on the front label of all LDC Solutions, refer to this number any time you have questions or problems with a solution.
As a general rule, all LDC Solutions should be stored in approximately a 60F to 80F (16C to 27C) environment, in a tightly sealed bottle, and out of direct light. Excessive heat & light will, in time, break down some of the more complex solutions. Precious Metal Solutions should all be stored in a cool, dark area. Silver is extremely sensitive to light, extra precautions should be taken. Alloy solutions, no matter what composition, have a tendency to decompose earlier than standard solutions.
During the winter months, it is sometimes impossible to predict the conditions of shipment or storage. You may occasionally receive a partially frozen bottle, which may cause “Salting Out”, the precipitation of dissolved salts. If this occurs, you can usually restore the solutions to full effectiveness by redissolving the salts. To accomplish this the solution should be heated to approximately 140 F (60 C) and stir until all the material has redissolved. If the salts are not dissolved the solution cannot be expected to perform to the normal specifications. If questions arise please contact your local LDC representative.
“The Brush Plating Solution Doesn’t Work”
How often have you had users of Brushplating insist that the solution is at fault. I hope not too many times but it does happen. The solution always gets the blame yet in many years of experience in New Zealand the solution has only been found to be at fault once.
What are the faults that have been discovered and what fixes have been used?
My brushplating manufactures and friends in UK have given me this advice:
LDC 01, Electrocleaning LDC-#1 Activator, LDC-02 Activator No.2, LDC-03 Activator No.3. Anodes that are too small for activation are frequently used and under activation results. If the anode does not cover at least 10% of the total area to be plated activation quality can be compromised.
If you see users using a 2-inch diameter anode to activate a 24″ internal diameter tell them to expect disaster. It may be that small activation anode coverage could work on simple Carbon Steels but as soon as the base metal is Stainless Steel or some other alloy the coverage becomes more critical. It is not worth the risk to save money in the short term and use small anodes.
We would always recommend the use of Ampere-Hour Factors for all Activation except LDC-03. To activate for so many minutes or seconds is, in our opinion risky. It very much depends upon the percentage coverage of the anodes and with 50% 33% and 25% coverage commonly used by different users it can be readily understood that different amounts of activation can easily be arrived at if the over-simplified time parameter for Activating is used.
Anode wrap material can also be a source of trouble. The scrubbing action does seem to aid activation and the use of Red Scotchbrite does improve the overall quality. We would therefore recommend that it is the preferred wrap for LDC-#1 Activator and LDC-03.
Rinsing between nickel bonding layers and nickel build-up has been identified as a source of trouble. At TEI New Zealand in our Contract Services shop we would never rinse between nickels no matter what nickles – Alkaline, Acidic or Sulfamate. The potential minor contamination has not proved to affect the quality of either solution but the rinsing has been shown to cause de-lamination so rinsing is not carried out
The wrap choice for the Nickel Bonding layer can also be critical. If we are depositing a nickel bonding layer onto chromium we always use Red Scotchbrite. For this reason we always use Red Scotchbrite for any Nickel Bonding layer deposition. This applies to Nickel LDC-2801, Nickel Acid LDC-2807.
It is surprising how often you find experienced operators taking their time between stages of selective plating, particularly between the activation stage and the deposition of the bonding layer. Encouragement to hurry up is sometimes all that is required to improve bonding quality. anode/cathode movement is often ignored.
When manually plating flat surfaces it is difficult to achieve even the minimum recommended feet/minute, metres/minute but the advised figures for anode/cathode movement should be respected.
Anode coverage is as important as in the previous paragraph.
Solution flow is another neglected area. Pumped solutions are always preferable to dipping the anode for solution replenishment and the solution should be well distributed on the anode face.
Electrical contact has been identified as a cause for problems in the past. Although the new designs of handles reduces this problem the cleanliness of all contacts should be checked, and cleaned frequently.
All the above points can be in the control of the operator. It is in his hands if the process works or fails so that encouragement to follow some or all of the above points will improve the quality of the work being carried out and the overall acceptance of the process.
I remember someone in Selective Plating telling me many years ago that Selective Plating training’s aim was to create heroes out of the operators. When operators return to their work place they must be confident, successful and efficient. If they can be all these three things then we have made them heroes in their particular company work place.
I hope that next time you are told “It’s the solution that’s at fault” some of the above points may help