Analytical Test Study of PCB Plating Solution (4)

C. Acid sulphate copper plating solution analysis:

â– 1. Determination of copper content:

1.1 Reagents:
1) Ammonium puritanate indicator. 0.2 g is mixed with 100 g of sodium chloride. Store this mixture until dry. Use 0.2 g and 0.4 g of this mixture for each titration.

2) 0.2 normal EDTA: disodium salt (37.23 g/l).

3) Ammonium buffer. Nearly 68 grams of ammonium chloride was dissolved in 300 milliliters of distilled water. 570 ml of 29% ammonium hydroxide was added and the mixture was diluted to 1 liter.

1.2. Analysis method:

1) Pipette 2 ml of the solution into a 600 ml flask.

2) Add 5 ml of ammonium buffer and dilute to 450 ml with water. At this point the solution should be brewed. If it is still not clear, ammonium buffer should be added until it is complete.

3) Add 0.2 to 0.4 grams of ammonium muranate indicator.

4) Titrate with 0.2 equivalents of EDTA to the purple endpoint.

1.3 Calculation:

1 ml 0.2 equivalent EDTA=0.006357 g copper

1 mL of 0.2 equivalent of EDTA* 3.18 = g/L copper

1 ml 0.2 equivalent EDTA* 0.424 = oz/gallon copper

â–  2.0 Titration of sulfuric acid content:

2.1 Reagents;

1) 0.1% methyl orange. 0.1 g of this salt was dissolved in 100 ml of water.

2) 1 N NaOH (40 g/L)

2.2 Analysis;

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

2) Add 250 ml of distilled water and add 10 drops of methyl orange indicator.

3) Titrate with a 1 N NaOH solution until the end of pale green.

2.3 Calculation:

1 ml equivalent of sodium hydroxide = 0.049 g/sulfuric acid

1 ml equivalent of sodium hydroxide * 9.8 = g/l sulfuric acid

1 ml equivalent of sodium hydroxide * 1.31 = oz/gallon of sulfuric acid

　

D. Analysis of Acid Fluoroborate Copper Plating Solution

â–  1.0 Determination of Copper Content - See section Analysis of Acid Sulfate Copper Plating Solution.

â– 2.0 Determination of free fluoroboric acid content:

2.1 Reagents

1) 1 N NaOH (40 g/l).

2) cresol red indicator. One gram of this salt was weighed, ground with 26.2 ml of 0.1 equivalent sodium hydroxide and slurried to 1 liter in a roasting flask.

2.2 Analysis:

1) Pipette 10 ml of the sample into a 250 ml beaker.

2) Add 150 ml distilled water and a few drops of cresol red indicator.

3) Titrate with 1N NaOH until the blue green end point.

2.3 Calculation:

1 ml NaOH = 0.0878 g HBF4

1 ml normalized sodium hydroxide * 8.78 = g/l HBF4

1 milliliter normalized sodium hydroxide * 1.18 = ounces/gallon HBF4

(to be continued)