ELECTRONIC SPACE PRODUCTS INTERNATIONAL
1050 Benson Way, Ashland, OR 97520
Toll Free (800) 638-2581 * Fax (541) 488-8313
E-Mail: sales@espimetals.com
GOLD SALTS, PLATING INSTRUCTIONS
24k neutral gold produces an ultra pure 24k satin bright deposit that is stress free; is extremely ductile and tight grained with exceptional heat and corrosion resistance. It also contains no brighteners, either organic or inorganic; no free cyanide; no harsh alkalis or acids; is economical to operate and simple to maintain.
For Normal and High Temperature Applications:
RACK PLATING:
Equipment:
Tanks: Polypropylene Koroseal lined steel or glass.
Anodes: Platinum plated titanium, tantalum or niobium. Area equal to cathode.
Agitation: Filter pump or sparger system with separate high speed pump.
Heating: Immersion heaters with permanent agitation (sparger system).
Formula:
1 Gallon 100 Gallons
Gold Solution Additive: 1-1/2 lbs 150 lbs
Gold Salts: 1 troy oz. 100 troy ozs.
Preparation:
1. Fill tank two-thirds full with distilled or deionized water. Heat to 140 oF.
2. Add the Additive and stir until completely dissolved.
3. Add the 24k Gold salts. Stir until completely dissolved.
4. Add distilled or deionized water to bring up to operating level.
Operating Conditions:
pH (Electrometric): 5.0 - 7.0
pH (Paper): 5.3 - 7.3
Specific Gravity: 1.08 - 1.15; 11 o - 16 o Baumé
Anode/Cathode Area: 1/1
Agitation: Preferred
Temperature: 130 - 160 oF
Current Density: 1-10 ASF
Current Efficiency: 100 % at 1-4 ASF with agitation
Time to plate 0.0001"
at pH of 6.2: 8 min. at 5 ASF
Replenishment:
Every 4 amp. hours, add 1 troy oz. Gold Salts
BARREL PLATING:
Equipment: See ‘Rack Plating’
Formula:
1 Gallon 100 Gallons
Gold Solution Additive: 2 lbs 200 lbs
Gold 24k Salts: 1/2 troy oz. 50 troy ozs.
Operating Conditions:
Current Density: 1-3 ASF
Temperature: 130-170 oF (140-160 oF preferred)
Anode/Cathode Area: 1/1
pH: 5-6 electrometric
Specific Gravity: 1.1 - 1.2; 14 o - 24 o Baumé
Time to plate 0.0001"
at pH of 6.0, 150 oF: 30 min. at 2 ASF
Preparation: See ‘Rack Plating’
Replenishment:
After every 5 amp. hours add 1 troy oz. Gold salts
BARREL PLATING - TRANSISTOR HEADERS:
Formula:
Additive #1: 1 Gallon 2-1/2 lbs
Gold Salts: 1 troy oz.
Preparation: See ‘Rack Plating’
Operating Conditions:
Current Density: 1/2 - 1 ASF
Temperature: 130 - 170 oF (140-160 oF preferred)
Anodes/Cathode Area: 1/1
pH: 5 - 6 electrometric
Specific Gravity: 1.1 - 1.2; 14 o - 24 o Baumé
Time to plate 0.0001"
at pH of 5.5, 140 oF: 60 min. at 1 ASF (TO-18)
Replenishment:
After every 6 amp. hours add 1 troy oz. Gold Salts
SUGGESTED PLATING PROCEDURE:
1. Descale and bright dip.
2. Pickle in warm hydrochloric acid, 30% by volume, at 120 oF for 1 to 3 minutes.
3. Rinse in running water.
4. Strike, 3-4 ASF, pH 3.5-4.5, 2-5 minutes at 80-100 oF.
5. Drag-out or quick rinse.
6. 24k Gold-1 ASF, 140 oF, Approximately 60 minutes for 0.0001 in.
7. Drag-out.
8. Running rinse.
9. Hot water and dry.
STRIKING SOLUTION:
In plating high nickel alloys and other passive prone metal surfaces it is strongly recommended that a weak gold strike be used before entering the 24k Neutral Gold Solution. Such a strike may be made up as follows:
Gold Solution Additive: 1-1½ lbs per gallon
Gold Salts: 0.25 - 0.5 troy oz. per gallon
Procedure for make up will be the same as for ‘Rack Plating’. If pH is too high add diluted phosphoric acid. (See Note 1)
Operating Data:
pH: 3.5 - 4.5
Temperature: 80 - 120 oF
Current Density, Rack: 10 - 20 ASF 30 - 10 seconds
Barrel: 3 - 10 ASF 3 - 1 minute
This strikeout solution may be used as a drag-out for the heavy 24k Neutral Gold bath.
NOTES:
Note 1 - pH: The pH of 24k Neutral Gold Solution slowly rises during operation. The pH should be checked periodically with a glass electrode pH meter, such as the Beckman Portable or equivalent. If the pH drops below 5.0 the current efficiency will drop rapidly, reaching a value of 50 % at a pH of 4.5. This effect is more noticeable at current densities above 6 ASF.
To reduce the pH of a 100 gallon bath 0.1 unit, dissolve 1 lb of phosphoric acid in 1 gallon of water and add slowly to bath with agitation. To raise the pH of a 100 gallon bath 0.1 unit, dissolve 20 oz. of of reagent grade potassium hydroxide in ½ gallon of water and then add slowly with stirring to the gold bath.
Note 2 - Current Density: High current density will produce dark red plates. As the gold content is increased and as agitation is increased, the allowable current density can be increased.
Note 3 - Temperature: As the temperature is increased the current density may be raised and still maintain clean yellow plates.
Note 4 - Specific Gravity: Specific gravity below 11 o Baumé causes loss of throwing power. To raise the specific gravity 1 o Baumé, add 10 lbs of monopotassium phosphate per 100 gallons of plating solution. (Add slowly with good mixing.)
Note 5 - Filtration and Carbon Treatment: The bath should be filtered periodically. Stainless steel filters are adequate for batch filtration, but plastic filters should be used for continuous filtration.
Note 6 - Heavy Plates: For plates heavier than .001", it is preferred that the gold concentration be increased to 40 - 50 dwt. per gallon.
Note 7 - Barrel Plating: The current density range increases with increase in temperature and increase in pH approaching a maximum at pH 6 - 7 and a temperature of 160 oF. At the lower temperatures and lower pH values the current efficiency at 1 ASF drops off rapidly.
TROUBLESHOOTING:
Dark Color in High Current Density Areas:
1. Reduce the current density.
2. Increase temperature to 140 - 150 oF.
3. Increase gold content.
Rough Plate:
1. Carbon treat and filter the bath. Use 3 lbs of Darco S-51 or G-60 activated carbon per 100 gallons of solution.
Loss of Throwing Power:
1. Raise the specific gravity of the bath to above 12 o Baumé with monopotassium phosphate. (See Note 4)