Four common forms of pulse power supply
Square wave pulse is the most basic form of pulse electroplating current, commonly referred to as single pulse. Other commonly used forms evolved from single pulses include DC superimposed pulses, periodic commutation pulses, intermittent pulses, etc. Among them, unidirectional pulses include single pulse, DC superimposed pulse, intermittent pulse, etc. Unidirectional pulse refers to a pulse waveform in which the direction of current does not change over time; The periodic commutation pulse is a bidirectional pulse form with reverse anode pulse.
1. Single pulse
Single pulse, commonly referred to as pC, is not only used in functional electroplating, but also in anodizing of aluminum. It can comprehensively improve the quality of the oxide film and oxidation rate, avoiding phenomena such as "powdering" and "burning"; And due to the periodic voltage reduction, it can prevent the accumulation of local surface heat of the workpiece, thereby reducing the resulting burning phenomenon.
2. DC superimposed pulse
DC superimposed pulse refers to the addition of a square wave pulse on the DC fundamental wave. This method is commonly used for anodizing aluminum, and its main advantage is that when a uniform oxide film cannot be formed by DC plating, it can be used for all aluminum alloys to generate a uniform oxide film. In addition, this method can form a 25-300ttm thick oxide film on cast, forged, or machined aluminum parts after a short period of anodizing, and the film layer has good wear and corrosion resistance. In addition, DC superimposed pulses are sometimes used to increase the output power of pulse power supplies, and their effective current is equal to the sum of the fundamental DC current and the average pulse current. The electroplating effect of this method is basically equivalent to that of a single pulse.
3. Periodic commutation pulse
Periodic commutation pulse electroplating is commonly referred to as double pulse electroplating, abbreviated as pR electroplating. It should be pointed out that the double pulse referred to here is a bidirectional pulse, which refers to the current form of introducing a reverse anode pulse after the forward cathode pulse, rather than the traditional double pulse form of alternating two different parameter pulses. The electrochemical principle based on which pR plating is based is that the highly uneven anode current distribution caused by a large amplitude and short duration of reverse pulse will cause the convex parts of the coating to be strongly dissolved and leveled.
4. Intermittent pulse
Intermittent pulse, also known as intermittent pulse or pulsating pulse, is a periodic interruption of the pulse, which can also be seen as the reverse pulse current of pR plating being zero. This situation, due to the presence of intermittent time, is conducive to the full recovery of discharge ions and can increase the pulse limit current density. In addition, this method can reduce the corrosion of the substrate metal by reverse pulse during the plating stage of pR plating. Intermittent pulses require adjustable intervals.
