Analytical Test Study of PCB Plating Solution (5)

E. Analysis of Modified Watts Nickel Plating Solution

â–  a. Determination of nickel content using the following reagents:

1) 0.2 normal EDTA: disodium salt (37.2 g/l).

2) Ammonium red finger indicator (see section Analysis of pyrophosphate copper plating solution).

Analytical method:

1) Pipette 2 ml of the sample into a 250 ml erlenmeyer flask.

2) Add 50 ml of distilled water and 10 ml of 29% ammonium hydroxide.

3) Add 0.5 grams of ammonium oleate indicator.

4) Titrate with 0.2 EDTA until the blue end point.

Calculation:

1 ml of 0.2 normal EDTA = 0.00587 g Ni

Milliliters of 0.2 normal EDTA x 2.94 = g/l Ni

Milliliters of 0.2 EDTA x 0.392 = oz/gallon Ni

â–  b. Determination of chloride or bromide content requires the following reagents:

1) 0.1 equivalent concentration of silver nitrate (16.99 g/l).

2) Potassium dichromate indicator. A saturated solution of potassium chromate in distilled water.

Analytical method:

1) Pipette 5 ml of the solution into a 250 ml Erlenmeyer flask and add 100 ml of distilled water.

2) Add 2 grams of sodium bicarbonate, plus a few drops of potassium chromate indicator.

3) Titrate slowly with 0.1 normal silver nitrate until the resulting precipitate is light reddish brown.

Calculation:

1 ml of 1 equivalent amount of AgNO3=0.001189 g of NiC12·6H2O

1 ml 1 equivalent concentration of AgNO3 = 0.01363 g NiBr2 · 3H2O

Milliliter 0.1 equivalent concentration of AgNO3 x 2.378 = g/l NiC12·6H2O

Milliliters of 0.1 normal AgNO3 x 0.317 = oz/gal NiC12·6H2O

Milliliter 0.1 equivalent of AgNO3×2.726=g/L NiBr2·3H2O

Milliliters 0.1 normal concentration of AgNO3 x 0.364 = ounces/gallon NiBr2 · 3H2O

â– c. Determination of boric acid content requires the following reagents:

1) 1 normal NaON (40.0 g/l).

2) Bromocresol red indicator. One gram of the indicator was thoroughly mixed with 118 ml of 0.1 normal NaOH and diluted to 1 liter in a volumetric flask.

3) Chemically pure glycerin.

Analytical method:

1) Pipette 5 ml of the sample into a 250 ml flask.

2) Add 25 ml of chemically pure glycerine and 0.5 ml of bromocresol red indicator.

3) Titrate with 1 N NaOH until the color turns green and violet ends.

Calculation:

1 ml of 1 equivalent NaOH = 0.0619 = g/l H3BO4

Milliliter 1 NaOH x 12.38 = g/l H3BO4

Milliliters of 1 NaOH x 1.65 = oz/gal H3BO4
F. Analysis of sulfamate nickel plating solution

a. Determination of nickel content. See Plating Modified Watts Nickel Solution Analysis section.

b. Determination of bromide content. See Plating Modified Watts Nickel Solution Analysis section.

c. Determination of boric acid content. See Plating Modified Watts Nickel Solution Analysis section.

(to be continued)