Under the condition of no agitation, the coating is relatively loose, the structure is not close, and there are large holes. This is because the concentration polarization and the thickness of the diffusion layer are reduced by stirring, so that the discharge metal ions on the cathode surface are rapidly supplemented during electrodeposition. Stirring can also improve the upper limit of current density, so that the operating current density increases, reduce pinholes and burrs.

1.3 Process formula and process premise

Type HDV-7C transistor potentiostatic instrument, type CHI660 electrochemical workstation, type FA1004 electronic balance, type 79-1 stirrer, type KQ-50E ultrasonic cleaner, type DKB-8A constant temperature bath.

1.2 Experimental Instruments

CuSO4(> 99.0% by mass),H2SO4(> 95.0% by mass),PEG(> 99.0% by mass),NaCl(> 99.5% by mass), and absolute ethanol (> 99.7% by mass).

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FIG. 1 shows the ac impedance spectra of the coating with or without stirring without any additive. It can be seen from Figure 1 that the corrosion resistance of the coating obtained with agitation is significantly better than that without agitation.

0 foreword

Chinese Library Classification NUMBER :TQ153 Document Code :A Article Number :1000-4742(2011)04-0015-03

Key words: acid copper plating; PEG; The chloride ion; Tafel curve

Abstract: The influence of mass concentration of two additives on copper plating in acid copper plating process was studied. The anode is a phosphorous copper plate.

1.4 Sample preparation

CuSO448g/L, mass fraction of 98% H2SO4100mL/L, nacL30-100mg /L, PEG0.1-0.2g /L,1A/ Dm2,20°C, average stirring 15min. The corrosion resistance of the coating in different bath was measured by Tafel equation, and the influence of PEG and Cl- on the corrosion resistance of the coating was studied.

2.1 Influence of stirring on the coating obtained

2 Results and discussion

Three electrode system is used to test the corrosion resistance of the coating. The reference electrode is saturated calomel electrode, the auxiliary electrode is large-area platinum plate, and the working electrode is electroplated. Concentrated sulfuric acid with a concentration of 0.5mol/L was used as the corrosion solution to test the corrosion resistance of the coating.

1.1 Reagents

Experiment 1

In this paper, the influence of additives in acid copper plating on the coating was mainly studied. The influence law of mass concentration of PEG and Cl- on the corrosion resistance of the coating was determined by Tafel equation [1-3], and the electroplating mechanism was studied, so as to obtain a group of additives combination with good electroplating effect. The synergistic rule and optimal ratio between PEG and Cl- at a certain mass concentration were summarized through experiments. Before the experiment, 600#,800# and 1200# sandpaper were used successively for grinding, and then put into distilled water and anhydrous ethanol respectively for ultrasonic cleaning, and finally activated with 5% dilute H2SO4 for 30min before use.

1.5 Test Method

The experiment used a double electrode system, the cathode was 34# stainless steel sheet, sealed with epoxy resin to make a disk with a diameter of 1.0cm.