Monday, December 27, 2010
【 Weak current College 】 perforation of copper printed circuit board plating principle outlined 】
The broad definition of pulse plating
Pulse plating widely defined as continuous current of electroplating. Continuous current is corrected to the current at some time to appear in another time reverse current occurs. Since the 1950s, has been engaged in research on pulse plating, pulse current can cause the coating crystalline refinement, high adhesion, non-porous, so the coating has a bad and good chemical resistance.
Pulse plating parameters
According to numerous experiments, for a set of electrolyte systems, its metal plating rate depends on: (1) pulse frequency, (2) cycle (duty cycle), (3) waveform, and (4) the current density of the fourth argument. In addition, additives, chemical medicine and metal itself features also has the effect of pulse plating. When you apply the pulse galvanization, no preset of standard parameters. Each specific experimental metal required to find their way and special parameter combination, reached its improved physical properties of the coating, which is the largest of the pulse galvanization. We are not able to other metal plating parameter combinations in another metal plating. Since the circuit board design requirements tend to be thin wire, high density, small aperture (and even micro-through-hole), today's direct galvanised does not meet the above requirements. As the aperture and thickness increases perforated copper greatly technical difficulties, particularly in the aperture Centre of coating, usually a Aperture at both ends of the copper layer too thick but Centre of copper layer. The coating is not uniform conditions can affect the current transmission. This problem can be overcome periodic steering pulse plating. The high-speed cycle steering principle of pulse plating is applied forward current plating for a period of time (approximately 95 per cent), and then to a high-energy short speed reverse current galvanised around 5 per cent). The high-speed cycle go
The pulse and electroplating and additive effect, high current density areas, reassign the electroplating polarisation current redistribution to the low current density areas, its effect is in high current density areas of copper coating decreases, but this is not going in low current density areas, hence, circuit board of aperture of copper plating layer surface copper layer also thick. Its current and time of the pulse galvanization principles outlined
In the electroplating process, plating tank three resistance, anode resistor cathode resistor and plating resistance. In cathodic deposition, cathode resistor can be divided into two majority; geometry resistance and polarization resistance. Geometric electric Group (primary current distribution) plating, due to the different shapes, circuit board surface resistance and aperture in resistance. Surface resistivity (Rs) resistance than aperture (RH). Therefore, the flow of surface currents (Is) is far better than aperture (IH) in-current. Hence resulting aperture and surface uneven copper layer assignment