Electroless Nickel Troubleshooting Guide Page 4

1: Measure the phosphorus content of the deposit

2: Deposits containing more 11% or less than4% phosphorus are compressively stressed; med phos deposits can be highly tensile

3: Use a high phos or low phos type plating baths

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

2: The internal stress of most coatings increases rapidly after 4 or 5 cycles of operation

3: 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

1: Analyze the bath's reducer content and adjust it to its proper range

2: Low reducer concentration will cause the phosphorus content of high phos type coatings to decline and their stress to increase

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

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

1: Measure the bath's pH with a calibrated pH meter and adjust it to its proper range(generally between 4.8 and 5.2 pH) with50% sulfuric acid

2: High pH will cause the phosphorus content of high phos type coatings to decline and their stress to increase

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

4: Eliminate any sources of alkali drag in, such as blind holes and poor rinsing

1: Analyze the bath's reducer content and adjust it to its proper range

2: High reducer concentration will cause the phosphorus content and stress of low phos type coatings to increase

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

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

1: Measure the bath's pH with a calibrated pH meter and adjust it to its proper range(generally between 4.8 and 5.2 pH) with 50 precent ammonia or potassium carbonate

2: Low pH will cause the phosphorus content and stress of low phos type coatings to increase

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

4: Eliminate any sources of acid drag in, such as blind holes and poor rinsing

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: 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

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

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

1: Measure nickel concentration of rinse after the plating tank and calculate the amount of bath being lost

2: Loss of complexers will cause the phosphorus content of high phos deposits to decline and stress to increase

3: Reduce drag out by draining or spray rinsing the parts over the plating tank before placing them in the rinse tank

4: Add small amounts of make up concentrate(typically 1-2 percent per bath cycle) to replace the complexer being lost

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

2: Install an automatic bath controller to make more frequent additions to keep the bath inbalance

1: Check heat treatment records or measure the deposit's hardness to determine its heat treatment

2: Heat treating electroless nickel deposits causes their ductility to decline

3: For maximum ductility do not heat treat coatings at temperatures over 550 DegF (290 DegC) or to hardness over 700HV100

1: Measure the phosphorus content of the deposit

2: Normally, deposits containing more than 10.5 or 11 precent phosphorus have the highest ductility

3: The ductility of deposits with lower phosphorus contents is significantly reduced

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

2: The ductility of most coatings declines rapidly after 5 or 6 cycles of operation

3: 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

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; contaminatedrinses; drag in blind holes or pores; parts plated with poisonous metals; drippage from adjacent equipment; impurities in process water

1: Analyze the bath's reducer content and increase it to its proper range

2: Low reducer concentration will cause the deposit's phosphorus content and ductility to decline

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

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

1: Measure the bath's pH with a calibrated pH meter and reduce it to its proper range (generally between 4.8 and 5.2 pH) with50% sulfuric acid

2: High pH will cause the deposit's phosphorus content and ductility to decline

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

4: Eliminate any sources of alkali drag in, such as blind holes and poor rinsing

5: Confirm that the proper ratio of hypophosphite to nickel replenisher is being used (for self pH regulating baths)

1: Measure nickel concentration of rinse after the plating tank and calculate the amount of bath being lost

2: Loss of complexers will cause the deposit's phosphorus content and ductility to decline

3: Reduce drag out by draining or spray rinsing the parts over the plating tank before placing them in the rinse tank

4: Add small amounts of make up concentrate(typically 1-2 percent per bath cycle) to replace the complexer being lost

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 possible, discard part of the bath and adjust with replenisher to bring the solution into balance

4: If not, dispose of the bath and make up a new one

1: Check heat treatment records or measure the deposit's hardness to determine its heat treatment

2: Increase the temperature or time of treatment to obtain the desired hardness and wear resistance

3: Consider the use of SiC or diamond composite coatings for really severe applications

1: Measure the phosphorus content of the deposit

2: After heat treatment, deposits containing more than 10.5 or 11 percent phosphorus have the highest hardness and generally provide the best wear resistance

3: Use a high phos type plating bath for applications that are heat treated

1: Measure the phosphorus content of the deposit

2: In the as deposited condition, deposits containing about 4 percent phosphorus have the highest hardness and generally provide the best wear resistance

3: Use a low phos type plating bath for applications that will not be heat treated

1: Test the adhesion of the coating to the substrate according to ASTM B-733 orAMS 2404

2: See the preceding sections on poor adhesion

1: Observe the deposit after wear or wear test to see if it is shattering or crumbling

2: See the preceding sections on brittle deposits