Titanium Anodes for PCB Horizontal Copper Plating

Titanium Anode Plates for PCB Horizontal Copper Plating

Acidic electrolytic copper plating is a crucial step in the metallization process of printed circuit board (PCB) holes. With the rapid advancement of microelectronic technology, PCB manufacturing is swiftly moving towards multilayer, stack-up, functional, and integrated designs. This trend encourages the extensive use of small holes, narrow spacing, and fine wires in circuit design, making PCB manufacturing increasingly challenging. Especially in multilayer boards with a hole aspect ratio exceeding 5:1 and stack-up boards with deep blind vias, conventional vertical plating processes cannot meet the high-quality and high-reliability requirements of interconnect holes, leading to the development of horizontal plating technology.

1. PCB Horizontal Reverse Pulse Copper Plating

Due to the design requirements of circuit boards for fine linewidths, high density, fine hole diameters (high aspect ratios, even microvias), and blind hole filling, traditional direct current (DC) plating is becoming increasingly inadequate. Particularly in through-hole plating, the center of the plated layer often shows insufficient copper thickness compared to the ends, leading to uneven copper distribution and affecting the current delivery, thus compromising product quality. To balance the copper thickness on the surface, especially in holes and microvias, the current density must be reduced, which would otherwise lead to unacceptable plating times. With the development of reverse pulse plating technology and suitable chemical additives, it has become possible to shorten plating times and overcome these issues.

Typical Electrolytic Process:

• Electrolyte: CuSO4/5H2O: 100-300g/L, H2SO4: 50-150g/L
• Forward Current Density: 500-1000A/m²
• Reverse Current Density: Three times the forward current density
• Plating Process: Bidirectional Pulse
• Temperature: 20-70°C
• Forward Time: 19ms
• Reverse Time: 1ms
• Lifetime Requirement: 50000kA
• Anode Type: Specialized Iridium-based Mixed Metal Oxide Titanium Anode plate
  

2. PCB Vertical Continuous DC Copper Plating

In the PCB vertical continuous DC copper plating process, special organic additives are added to promote fine-grained metal deposition and uniform board surface distribution. These additives must be maintained at optimal concentrations to achieve the best performance and product quality. This requires the anode to not only meet the lifetime requirements but also minimize the consumption of organic additives to reduce the cost of reagents. Although traditional iridium-based titanium anodes meet the lifetime requirements, they result in high brightener consumption. Qixin Titanium has improved the process and formulation of traditional iridium-based titanium anodes to create specialized titanium anodes for PCB horizontal copper plating that reduce the consumption of organic additives while still meeting the required lifespan.

Typical Electrolytic Process:

• Electrolyte: Cu: 60-120g/L, H2SO4: 50-100g/L, Cl-: 40-55ppm
• Current Density: 100-500A/m²
• Temperature: 0-35°C
• Lifetime Requirement: More than 1 year
• Anode Type: Specialized Iridium-based MMO Titanium Anode

Advantages:

• Good plating uniformity
• Long lifespan
• Energy-saving and electricity-efficient
• High current density