Acid Salts

Acid Salts OPS

ACID SALTS OPS is a highly stable etch process formulated to ensure reliable clean base copper surfaces. The ACID SALTS OPS provides a smut-free, uniformly etched copper prior to electroless and electrolytic plating.

ACID SALTS OPS is supplied as a dry acid salt which can be dissolved in dilute sulphuric acid at ambient temperature. The system provide a fume-free copper activator.

The stability of the ACID SALTS OPS process provides up to four times the life of conventional persulphate solution, reducing rejects due to poor adhesion caused by copper recrystalization.

ACID SALTS OPS may be used in spray as well as immersion modes. No de-foamer is necessary.


  • 100 % active for long life.
  • No hazard in handling when used as described.
  • No fumes or odors, easy on equipment.
  • Readily soluble.
  • Contains no ammonium compounds, chromates, chlorides, nitrates or fluorides.
  • Ambient temperature operation.


Depending on application, ACID SALTS OPS is usually worked to exhaustion rather than run in a replenishable mode. Reliable copper activation is achieved from a 100 g/litre solution until copper concentration reaches 20 g/litre.

Application & Operating Conditions

For base-copper etch in Electroless & Electrolytic Nickel lines.

ACID SALTS OPS 20 oz./gallon (150 g/litre)
Sulphuric acid 66° Baumé 2% by volume
Temperature 70°F to 80°F (21°C to 26°C)
Time 2-3 minutes
Etch rate 35-45 µ inches/min. (0.9-1.1microns/min.)

Air agitation of ACID SALTS OPS solutions will produce a more even etch, while extending its life.

Tanks: PVC, rubber lined, polyethylene, polypropylene
Heaters: Quartz, Titanium, PTPE required to raise temperature to 50 F.
Air lines: PVC
Ventilation: Recommended
Heaters: Quartz, Titanium, PTPE

Half fill tank with water. Add required amount of ACID SALTS OPS, depending on specific application. Stir thoroughly. When fully dissolved, add 2% sulphuric acid and adjust volume. Protective face masks, boots and aprons are recommended.

CAUTION: Use ONLY sulphuric acid with ACID SALTS OPS.

ACID SALTS OPS contains an oxidizing agent and, therefore, should not be allowed to contact any reducing or organic matter. Use of hydrochloric acid will liberate chlorine gas. Use of nitric acid will generate oxides of nitrogen.


  1. Pipette 1 ml of ACID SALTS OPS solution into a 250 ml Erlenmeyer flask. Add 50 mls of water.
  2. Pipette 20 mls of 0.1N ferrous ammonium sulphate into the flask. Mix. Allow to stand for 30 seconds.
  3. Add 5 mls of 25% sulphuric acid and titrate to a violet end-point with 0.1N potassium permanganate. This is Titration X. Record the result.
  4. Repeat the procedure using a 5 ml sample of water. (This is a blank.)
    This is Titration Y.


    (Y - X) x 18.60 = g/litre ACID SALTS OPS

    (Y - X) x 2.41 = oz./gallon ACID SALTS OPS

Purpose: To describe the steps to be taken to determine the concentration of active oxygen in ACID SALTS OPS solutions.
  • 0.1N Sodium Thiosulphate Standard Solution
  • Potassium Iodide / EDTA solution Dissolve 100 grams of potassium iodide and 20 grams of EDTA (disodium salt) in 800 ml of distilled water. Add 1 drop of ammonium hydroxide, and dilute to one litre.
  • Starch Indicator
  • Degassed water; use boiled-out deionized or freshly distilled water.


  1. Pipette a 2 ml sample to a 250 Erlenmeyer flask.
  2. Add 100 ml of degassed water and 10 ml of Potassium Iodide / EDTA solution and mix.
  3. Titrate with 0.1N Sodium Thiosulphate to a pale yellow / green colour.
  4. Add Starch Indicator and continue titration to the almost colourless endpoint.


Active Oxygen Content (A.O.C.) (g/litre) = ( ml 0.1N sodium thiosulphate x 0.4 )

To increase 0.1 g/litre A.O.C. , add 3.0 g/litre of ACID SALTS OPS Copper Activator.


ACID SALTS OPS solutions are controlled by visual observation of the work. When etching or activation is incomplete or when the immersion time is excessive, a 10% addition of the original make-up should be added to the bath.

Depending on the quantity and type of alloys, soils and scale being processed, ACID SALTS OPS solutions eventually become saturated with metallic contamination. It is better to discard the bath than make continual maintenance additions.


Consult the individual Material Safety Data Sheets (MSDS) covering ACID SALTS OPS for complete information.

For the ACID SALTS OPS and the working solution, handling is recommended using chemical goggles or a full face shield, as well as protective clothing like neoprene gloves and boots, acid resistant apron or suit and hat. Use only with adequate ventilation or a NIOSH/MSHA approved respirator, as necessary. Always wash hands thoroughly after handling.

Accidental swallowing of this material should be avoided since it is toxic orally. This material, as well as its dust, is irritating to the eyes and skin. Contact with eyes, skin, and clothing should be avoided. ACID SALTS OPS dust is irritating to all parts of the respiratory system. Therefore, it is advisable to avoid inhalation of this product. This product is slightly acidic and may cause burns to eyes and skin. Employees handling this material should be equipped with gloves, safety goggles, and a respirator. When making the solution, add slowly to surface of the solution to avoid violent spattering.

In case of eye contact, immediately wash out eyes thoroughly by means of a continuously flowing stream of water directed into the eyes for at least 15 minutes, and consult a physician.

In the event of skin contact, remove contaminated clothing and drench skin thoroughly with water. Remove and launder contaminated clothing before reuse.

If an irritating amount of dust is inhaled, remove individual to a non-contaminated area. Call a physician.

If swallowed, DO NOT INDUCT VOMITING. Give large quantities of water. Call a physician immediately. Never give anything by mouth to an unconscious person.


Consult the individual Material Safety Data Sheets (MSDS) covering ACID SALTS OPS for complete information.


Neutralize spent ACID SALTS OPS solutions with alkali to a pH range of 7 to 9. Allow metals to settle. Care should be taken when adding alkali to avoid splashing. Wear protective equipment and clothing.

Provincial and local regulations concerning the discharge limits of hazardous substances must be observed.

It is recommended that each user establish a spill prevention control and countermeasure plan (SPCC). Such a plan should include procedures applicable to proper storage, control and clean-up of spills, including reuse or disposal, as appropriate.

Provincial and local disposal laws and regulations will determine the proper waste disposal procedure. All waste materials should be reviewed to determine the applicable hazards (testing may be necessary). Disposal requirements are dependent on the hazard classification and will vary by location and the type of disposal selected. Some waste materials are amenable to recycle/reuse.

Please note that the information above for this chemical is partial. Click the button below to request full technical information sheet.
Request Technical Information Sheet

Quick Contact