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CU-800 系列
The CU-800 series is a thin-film super-fill via solution developed by Wechsler specifically to meet the high-frequency signal transmission requirements of smartphones, AI, and 5G. This series aims to solve the filling challenge of micro-blind vias in high-density interconnect (HDI) boards. Through a unique "bottom-up" filling mechanism, it achieves a void-free, low-dimple plating effect, making it particularly suitable for micro-line (SAP/M-SAP) processes.
Product Composition and Functions
The CU-800 series consists of three components, each performing a different electrochemical function:
Component Name | Corresponding model | Core Functions | Mechanism of action |
carrier | CU-800C | Inhibitors/Wetting Agents | Contains polymeric components that bind with chloride ions, preventing abnormal precipitation; reducing surface tension, facilitating the entry of the drug solution into the pores. |
Inhibitors | CU-800A | Leveler | The diffusion rate is slow, and adsorption is high on surfaces with high current and strong stirring, inhibiting the growth of copper on the surface and forcing copper to deposit into the pores. |
Accelerator | CU-800B | Brightener | Rapid diffusion and uniform adsorption; Works synergistically with inhibitors, breaking down the inhibitory layer and promoting rapid filling of the pore bottom. |
Standard Process Parameters
To achieve optimal pore-filling (Dimple ≤ 5μm), it is recommended to refer to the following standard bath formulation:
project | Standard concentration | Management Scope | Remark |
Copper sulfate pentahydrate (CuSO₄·5H₂O) | 240 g/L | 230 ~ 250 g/L | Copper source, high concentration, good hole-filling performance |
Sulfuric acid (H₂SO₄) | 40 g/L | 30 ~ 50 g/L | Conductivity; excessively high concentrations will reduce pore-filling performance. |
Chloride ions (Cl⁻) | 50 mg/L | 30 ~ 70 mg/L | It needs to work in synergy with the carrier. |
CU-800A (Leveler) | 15 ml/L | 10 ~ 30 ml/L | The core inhibitor requires regular activated carbon treatment and maintenance. |
CU-800B (Brightener) | 1.0 ml/L | 0.5 ~ 1.5 ml/L | Excessive accelerator can lead to decreased pore-filling performance. |
CU-800C (Carrier) | 15 ml/L | 10 ~ 20 ml/L | Basic carrier |
• Temperature: 24℃
• Agitation: Air agitation (1~2 L/min)
• Anode: Insoluble anode (soluble anode can also be used)
• Current Density: 1.5 ~ 2.0 A/dm²
Core Advantages
• Thin-film via filling: Compared to traditional processes, significantly reduces surface copper thickness (15~20μm plating thickness is sufficient for filling), shortens plating time, and reduces copper consumption costs.
• Excellent via morphology: Less prone to protrusion, minimal dimple (≤5μm), perfectly compatible with Anylayer processes.
• High adaptability: Supports advanced processes such as HDI, M-SAP, and SAP; compatible with both soluble and insoluble anodes.
• Convenient management: All components can be precisely analyzed and managed using CVS (Cyclic Voltammetric Stripping), offering a wide range of solution management and high stability.
Stability and Maintenance
• Lifespan: Maintains stable hole-filling performance over long-term use.
• Maintenance Recommendations: To maintain resistance to burr precipitation, it is recommended to perform activated carbon treatment when the cumulative charge reaches 300~400 AHr/L to remove organic impurities and restore the activity of the solution.
• Reliability:
• Elongation: > 20%
• Tensile Strength: > 248 MPa
• Thermal Stress Test: 288℃/10s, no delamination or board bursting.
Process Capability
The CU-800 series is primarily optimized for blind holes (BVH) drilled by laser drilling. Typical applicable specifications are as follows:
Aperture (μm) | Hole depth (μm) | Aspect Ratio (A/R) | Recommended coating thickness (μm) | Remark |
100 | 70 | 0.70 | ≥15 | Standard Specifications |
100 | 80 | 0.80 | ≥16 | Standard Specifications |
125 | 60~100 | 0.48~0.80 | ≥16~22 | Parameters need to be adjusted according to depth. |
150 | 60~100 | 0.40~0.67 | ≥20~28 | For aperture depths >120μm, X-via design is recommended. |
(Note: Specific parameters need to be fine-tuned according to the customer's equipment and actual conditions)
