Palm Technology - The Electroless Nickel Troubleshooting Guide Page Number 3

1: Filter the solution through 1 micron bag filters at a rate equal to 10 tank volumes per hour

2: Totally filter the solution while it is being transferred through a 1/2 or 1 micron filter

1: Increase agitation (air) to ensure that the bath and replenishments are well mixed and that particles are suspended until they are filtered

2: Ensure that the agitation pattern moves particles away from the parts and into the filters (bath should show a uniform, rolling motion)

1: Locate and eliminate any external sources of particles, like blasting or grinding media

2: Keep the tank covered when it is not in use

1: Place parts on the rack so that critical surfaces are not facing upwards

2: Change the angle of the parts occasionally during plating so that the shelf is spread over the entire surface

3: Provide auxiliary agitation across the shelf area

4: Provide auxiliary mechanical part agitation(cathode rod agitator)

1: Check the tank and its components for evidence of plate out

2: Transfer the bath to another clean tank through a 1 micron filter bag

3: Strip and passivate the tank and equipment with room temperature, 30% nitric acid

1: Ensure that there is no nickel remaining on the tank or its components after passivation

2: Leave the nitric acid in the tank for a longer period to complete stripping

1: Check that the bath's temperature, pH and concentration are within the proper range

2: If necessary, adjust the temperature, pH or concentration to their proper range

3: Reduce the solution's plating rate to the value recommended by its supplier

1: Use only deionized water to make up and maintain the bath (tap water contains calcium and magnesium which can precipitate)

2: Improve filtration and carbon treatment in the deionized water system

1: Observe solution for rapid gassing and the presence of particles around the heater

2: Increase agitation around immersion heaters either with increased solution flow or air

3: Move immersion heaters away from the tank wall to improve solution circulation

4: Change to external pump through heat exchangers

5: If electric, change to derated immersion heaters

1: Check bath records or analyze the bath for orthophosphate to determine the bath's age

2: If older than normal range for bath (often equals 1 or 2 mol/L of ortho), dispose of the bath and make up a new one

3: If cloudy, add 1% by volume glycolic or lactic acid to clear the solution and then increase the bath's pH to its proper range with 50% ammonia or potassium carbonate

1: Ensure that the proper ratio of hypo to nickel replenishers has been used(generally either 1:1 or 2:1)

2: Where possible, analyze the solution for stabilizers like lead and cadmium

3: If necessary, add additional stabilizers to bring the bath into balance

1: Check the parts (iron or nickel base with a gauss meter (magnetic field indicator) to detect residual magnetism

2: Values as low as 5 or 10 gauss will often times cause roughness

3: Demagnetize the parts prior to pretreatment and plating

1: Find and eliminate any sources of stray current

2: Properly ground all equipment

3: Check that the anodic passivation system is properly connected and set up

1: Add replenishment solutions to the bath slowly and in a well agitated location

2: Add the nickel and hypophosphite solutions separately

3: Add replenishment solutions into the bag filter or the circulation pump overflow opening

1: Make additions in a well agitated location away from the parts and heater

1: Check that bath loading is below 0.75ft2/gal or 1.9 dm2/L (for some heavy metal stabilized baths)

2: Reduce the number of parts in the bath to obtain a bath loading less than 0.75 ft2/gal or 1.9 dm2/L

3: Ensure that the tank is not plating out on the plating or its components

1: Confirm that the appropriate pretreatment procedure has been used

2: After acid activation, examine parts for water breaks, and if present, reprocess and improve pretreatment cycle

3: Ensure that the pretreatment procedure is not etching the parts

1: Observe that the rinses are clear and free flowing

2: If rinses are not, increase the water flow rate

1: Rinsing alkali and acid coated parts in the same rinse water can result in difficult to remove salt particles on the surface

2: Rinse alkali and acid coated parts indifferent tanks

1: Improve pretreatment cycle to remove particles

2: Inspect at the last rinse for water break swhich may result from particles

3: Use soak cleaner that is designed to remove polishing compounds

4: Avoid the use of glass beads for abrasive blasting; aluminum oxide is preferred

1: Eliminate any sources of alkaline drag in, such as blind holes and poor rinsing

2: Improve rinsing

1: Check castings or powder metal parts for porosity that can spit out soils

2: Use alternating hot and cold rinses to pumps oils out of the pores

1: Check the quality of the agitation air by blowing it through a white cloth or bag filter

2: Install a filter on the inlet to the air blower

3: Install a filter/separator on the compressed air supply

4: Install a regenerative blower with filter to supply the plating tank

1: Pigmented polypropylene or CPVC tank liners should not be used (replace with natural polypropylene)

1: Filters and liners should be leached or rinsed completely prior to use

1: Check steam coils or heaters for leaks and repair or replace if necessary; steam can cause particles due to localized overheating and by introducing calcium and magnesium into the bath

1: Maintain the bath's temperature in its proper range (generally 185-195 DegF or 85-90 DegC)

2: Calibrate, repair or replace the temperature controller if necessary

3: If electrically heated, check that the voltage, current, and resistance are correct

4: If steam heated, check the steam supply, including solenoid, strainer and trap for proper operation

5: Ensure that the temperature sensor is in the solution and not damaged or leaking

6: If large loads of parts are causing the bath's temperature to drop abnormally, reduce the load or preheat it

1: Maintain the bath's pH in its proper range(generally between 4.8 and 5.2 pH)

2: Recalibrate the pH meter or check the accuracy of pH papers used

3: Eliminate any sources of acid or alkali dragin, such as blind holes and poor rinsing

4: Install an automatic controller to make more frequent neutralizer additions to keep the pH in proper range

1: Maintain the bath's nickel and reducer content in their proper range

2: Check the EDTA solution used for nickel titrations against a standard to ensure its accuracy

3: Ensure that only deionized water is used for nickel titrations

4: Ensure that the plating tank's volume, used to determine replenishment amounts, is correct

5: Install an automatic bath controller to make more frequent additions to keep the bath in balance

1: Make additions in a well agitated location away from the parts

1: Parts must always remain in the solution during plating

2: Use test panels or razor blades to inspect the coating while plating

1: Analyze the solution for heavy metals like lead, cadmium, bismuth and tin

2: Dummy the solution electrolessly or electrolytically at low current density and large cathode area to remove contaminants

3: Dispose of the bath if is not successful and make up a new one

4: Identify and eliminate the source of contamination. Look for: Racks or barrels that have been used in incompatible processes like cadmium; contaminated rinses; drag in blind holes or pores; parts plated with poisonous metals; drippage from adjacent equipment; impurities in process water

1: Check that organic maskants are properly cured and compatible with electroless nickel solutions

2: Identify and eliminate other sources of contamination, such as from the air supply, drippage from overhead equipment, ethylene glycol, plastic components, and drag in of inhibitors or wetting agents

3: Check steam coils or heaters for leaks and repair or replace if necessary

4: Carbon treat the solution by circulating it through carbon cartridges or a packed filter

5: Dispose of the bath if is not successful and make up a new one

1: Confirm that the appropriate pretreatment procedure has been used, especially for leaded and sulfurized alloys

2: After acid activation, examine parts for water breaks, and if present, reprocess and improve pretreatment cycle

3: Check that cleaners will remove (dissolve)the machining or cutting oils

4: If cleaner cannot remove them, change to a different type of oils or a different cleaner

5: Do not use inhibitors or wetting agents inactivating acids

1: Contaminated rinse water

2: Observe that the rinses are clear and free flowing

3: If rinses are not, increase the water flowrate

4: Observe the rinse water for the presence of an oil film on its surface or tank walls

5: If oil is visible, drain and carefully clean the tank and refill it with clean water

1: Reduce air to the minimum required for solution movement (for some heavy metal stabilized baths)

1: Check that bath loading is above 0.15ft2/gal or 0.4 dm2/L (for some heavy metal stabilized baths)

2: Put dummy panels into the bath to raise the loading to about 0.25 ft2/gal or 0.6 dm2/L

3: Increase the number of parts in the bath to obtain about 0.25 ft2/gal or 0.6 dm2/L

1: Inspect parts in barrels and baskets for freedom of movement

2: Reduce the number of parts in the basket or barrel

3: Add parts to the barrel or basket that will allow them to mix together better

4: Increase or decrease the barrel's rotation speed

5: Agitate basket mechanically

1: Find and eliminate any sources of stray current

2: Properly ground all equipment

3: Check that the anodic passivation system is properly connected and set up

1: Example parts for areas of passive metals(like stainless steel) such as inserts or repairs

2: Consult with manufacturer for manufacturing or repair history

3: If present, pretreat the parts as if it all were passive metal (such as with a strike)

1: Increase agitation (air) to ensure that the bath is well mixed and that fresh solution is continuously supplied to the part's surface

1: Reposition the parts so that gas streaks do not occur

2: Increase agitation, either with air or solution sparging or with a mechanical agitator

3: Periodically, move the parts to a new location

4: Periodically, strike or jar the work bar to vibrate bubbles loose from the substrate

1: Confirm that the appropriate pretreatment procedure has been used

2: After cleaning, examine parts for patterns, and if present, reprocess and improve pretreatment cycle

3: Ensure that the pretreatment procedure is not etching the parts and producing a localized pattern

1: Observe that the rinses are clear and free flowing

2: If rinses are not, increase the water flow rate

3: Do not rinse parts after alkali cleaning and acid activation in the same rinse water

1: Observe that the rinse is clear and free flowing

2: If rinse is not, increase the water flow rate

3: Install a hot deionized rinse after plating

1: Improve rinsing

2: Use non-silicated cleaners

1: Solution from filters or solution sparger should not impinge on the parts

2: Relocate the parts so that solution does not directly strike them

3: Check the filters and spargers for plugging

1: Copious quantities of air should not impinge on the parts

2: Relocate the parts so that the air does not directly strike them

3: Reduce air to the minimum required for solution movement

1: Analyze the solution for heavy metals like lead, bismuth, antimony and tin