02

2025

-

07

The content of hydrochloric acid in electroplating solution was determined by potentiometric titration


I. Preface

A liquid that carves by eroding the properties of materials. At present, there are mainly six types of etching solutions in use: acidic copper chloride, basic copper chloride, ferric chloride, ammonium persulfate, sulfuric acid/chromic acid, and sulfuric acid/hydrogen peroxide etching solutions. The etching speed of the ferric chloride etching solution is mainly affected by the etching temperature, the content of hydrochloric acid and the content of iron ions. The influence of the addition amount of hydrochloric acid in the etching solution: Adding hydrochloric acid to the etching solution can inhibit the hydrolysis of FeCl3 and increase the etching rate, especially when the copper dissolution amount reaches 37.4g/L, the effect of hydrochloric acid is more obvious. However, the amount of salt acid added should be appropriate. If the acidity is too high, it will cause damage to the liquid photoresist coating. In this experiment, the JH-T6 fully automatic potentiometric titrator was used to determine the endpoint based on its potential jump point and measure the content of hydrochloric acid to verify the feasibility of the experimental plan.

Ii. Instruments and Reagents

2.1 Instruments

JH-T6 fully automatic potentiometric titrator, composite PH electrode, analytical balance, etc

2.2. Reagents

3mol/L KF solution, 0.1mol/L sodium hydroxide standard titrant

Iii. Experimental Methods

3.1 Experimental Process:

Accurately weigh 1g of the sample to be tested (accurate to 0.0001g), add 50mL of deionized water and 25mL of 3mol/L KF solution in sequence, mix well, and titrate with the calibrated sodium hydroxide titrant until the potential suddenly exceeds the endpoint. At the same time, conduct a blank test and calculate the content of hydrochloric acid.

3.2 Instrument Parameters

The instrument parameters are shown in Table 1

Table 1 Parameter Settings of Titrator

Titration type:  Dynamic titration  method name:  Determination of hydrochloric acid in etching solution
Burette volume: 

10mL

Sample measurement unit:

g

Working electrode:  Composite PH electrode  Reference electrode

no

Stirring speed:

7

 Pre-stirring time:

5s

 


 

 

 

 

Electrode equilibrium time: 

4s

electrode equilibrium potential:

1mv

Titration speed:   standard titration  Equilibrium potential 

6mv

Display unit:

mv

 End volume:

20mL

Pre-titration addition volume:  0 (can also be set appropriately) Minimum addition volume:

0.02mL

Potential spike:

500mV

pre-controlled mv value:

0

Correlation coefficient:

3.655

Result unit::

%

Titrant name:

NaOH

 Theoretical concentration:

0.1580

 

Iv. Results and Discussion

4.1 Experimental Results

The samples were tested and the experimental results are shown in Table 2

Table 2 Content Test Results

Sample name Sample weighing capacity /g

Sampling volume

/mL

c( 1/6K2 Cr2

O7)/mol/L

Blank volume

V1/mL

Titration volume

V2 /mL

Iron content /%

Average value

(%

RSD(%)

 

Etching solution

 

0.1580

0.9600

0.530

 

0.09

0.2574

 

0.2576

 

 

0.4325

0.9115

0.549

0.2588

1.0244

0.558

0.2566

 4.2 Titration chromatogram

4.3. Conclusion

This test determined the content of hydrochloric acid in the etching solution through potentiometric titration. The instrument's judgment reduced human errors and significantly improved the accuracy of the experiment. Therefore, potentiometric titration is a good choice for detecting such samples.

Keyword:

potentiometric titratio