Analysis and experimental study of the hottest PCB

2022-10-24
  • Detail

Analysis and experimental study of PCB plating solution (3)

b. analysis of pyrophosphate plating solution

■ 1 Determination of copper content

1.1 reagent:

1) 0.2 equivalent concentration of EDTA: disodium salt (37.23 g/L)

2) 29% safety hydroxide (NH4OH)

3) ammonium papyrate indicator. Mix 0.2 g with 100 g of sodium chloride. Store the mixture until dry. Use a mixture of 0.2 g and 0.4 g for each titration

1.2 analysis:

1) pipette 5 ml of sample into a 500 ml flask

2) add 10 ml of concentrated ammonium hydroxide

3) add 300 ml distilled water

4) add 0.2 to 0.4 g of ammonium rhodiolate indicator to make it yellow brown

5) titrate with 0.2 equivalent EDTA until the end point (the solution changes from yellow brown to blue purple)

1.3 calculation:

1 ml 0.2 equivalent concentration edta=0.006357 g cu

1 ml 0.2 equivalent concentration edta*1.271= g/l cu

1 ml 0.2 equivalent concentration edta*0.17= ounce/gallon cu

■ 2 Determination of pyrophosphate content:

2.1 reagent:

1) 30% sodium hydroxide solution

2) 0.5 equivalent of sodium hydroxide (20.0 g/L)

3) bromophenol blue indicator. To prepare this indicator, weigh 1 g and mix it with 15 ml of 0.1 equivalent concentration of NaOH to form a slurry. Dilute the mixture to one liter with distilled water in a volumetric flask

4) 24.5g/l sulfuric acid with a concentration of 0.5 equivalent

5) 10% zinc sulfate solution

6) 1 equivalent of sodium hydroxide (40 g/L)

2.2 analysis:

1) use a straw to suck 5 ml of the sample into a 500 ml beaker, and add 200 ml of distilled water

2) heat the solution until it boils, and slowly add 30% sodium hydroxide to make copper precipitate as copper oxide until adding sodium hydroxide no longer produces precipitation

3) after the sediment is precipitated, filter the solution with no, 40 Whatman filter paper or other similar filter paper, thoroughly wash the collected sediment with hot water, collect the filtrate into 500 ml and beaker, and discard the sediment

4) add a few drops of bromophenol blue indicator and titrate with a burette with 0.5 equivalent concentration until the indicator turns yellow

5) add 30 ml of 10% zinc sulfate solution under strong stirring

6) let the solution stand for 5 minutes, and titrate with 1 equivalent of sodium hydroxide solution until the initial yellow color reappears

2.3 calculation:

1 ml 1 equivalent concentration naoh=0.08698 g p2o7

1 ml 1 equivalent concentration naoh*17.3= g/l p2o7

1 ml 1 equivalent concentration naoh*2.32= oz/gallon p2o7

■ 3 Determination of ammonia content:

3.1 reagent:

1) methyl red indicator. Dissolve 1 g of methyl red indicator powder in 50 ml of isopropanol and add 50 ml of distilled water to meet the new era in the field of materials

2) hydrochloric acid standard solution with 0.1 equivalent concentration

3) 25% sodium hydroxide

4) 0.1 equivalent of sodium hydroxide

3.2 analysis method:

1) suck 5 ml of the sample with a pipette and put it into a 125 ml long neck flask

2) add 50 ml of 25% sodium hydroxide and connect the flask to a condenser

3) distill to half (1/2) of the original volume, and collect the effluent in 400ml and beaker; The beaker contains 50 ml of 0.1 equivalent concentration of hydrochloric acid, 200 ml of distilled water and 5 drops of methyl red indicator. The outlet of the condenser should be lower than the liquid level

4) when the solution in the beaker has cooled, titrate it with 0.1 equivalent concentration of NaOH until it turns yellow

3.3 calculation:

50 ml 0.1 equivalent concentration naoh*1.17 g/L 29 ammonia

50 ml 0.1 equivalent concentration naoh*0.16= ounce/gallon 29% ammonia

■ 4 Titration of orthophosphate content:

4.1 reagent:

1) 1% phenolphthalein solution. Dissolve 1 gram of phenolphthalein in 50 ml of DuPont Hongji and the settled isopropanol of a batch of new material projects such as Dow glaze and Guangdong Tian'an new materials, and add 50 ml of distilled water

2) hydrogen sulfide source

3) magnesium oxide mixture. Dissolve 55 grams of magnesium chloride in 800 ml of distilled water, add 2 ml of hydrochloric acid, and dilute to 1 liter with distilled water

4.2 analysis:

1) determine the content of pyrophosphate (described in the previous section)

2) suck a circuit that is traditionally considered correct with a pipette, take 3ml of copper bath sample and put it into a 400ml beaker. Dilute with distilled water to 200 ml, and then 5 ml of sulfuric acid

3) the solution is bubbled with hydrogen sulfide for 5 minutes (under ventilation)

4) filter the solution into a 400ml beaker with no, 40 waltmann filter paper

5) boil the melt to a volume of 25 ml

6) dilute to 100 ml and add a few drops of 1% phenolphthalein

7) add 29% ammonium hydroxide until the solution turns pink

8) slowly add concentrated hydrochloric acid until the pink disappears. Then add 10 ml of excess concentrated sulfuric acid

9) the price index has increased, adding 5g ammonium acetate

10) add 50 ml of magnesium oxide mixture

11) add the solution to boiling

12) heat the solution to boiling

13) slowly add 29% ammonium hydroxide until the solution turns pink

14) stir the solution and cool it to room temperature

15) add 50 ml of 29% ammonium hydroxide

16) let the solution stand for at least 4 hours

17) use a pre weighed sintered glass crucible to hold the filtered residue

18) use ammonium hydroxide to clean the sediment

19) wet the sediment with saturated solution of ammonium nitrate

20) dry the residue in an oven

21) heat the crucible to red state for 30 minutes on Meker or (tirrill) lamp

22) cool the crucible and weigh it again to get the weight of the sediment

4.3 calculation:

weight of sediment (g) *37.9- (ounce/gallon P2O7) *1.9= ounce/gallon po4

(to be continued)

Copyright © 2011 JIN SHI