The difference between electroplated filled vias and copper paste filled vias

1. Electroplated Filled Vias：Suitable for board thickness ≤0.6mm and hole diameter ≤0.2mm.

•Process & Material: Vias are completely filled with 100% pure copper through electrolytic deposition.

•Performance: Provides maximum electrical conductivity and superior thermal performance, making it the ideal choice for High-Density Interconnect (HDI), Via-in-Pad (VIPPO), and high-frequency or high-current applications.

2. Copper Paste Filled Vias: Suitable for hole diameters ranging from 0.1mm to 1.0mm and board thickness ranging from 0.2mm to 4.0mm.

•Process & Material: Vias are mechanically filled using conductive/thermal copper paste (a composite mixture of copper powder and resin matrix), followed by curing, planarization, and surface copper capping.

•Formulation & Reliability: The ratio of copper powder to resin varies based on substrate CTE (Coefficient of Thermal Expansion) matching, required thermal conductivity, and specific production lines. For designs strictly requiring pure electrical interconnects, electroplated filling is recommended.

3. Key Comparison: While both process options yield a flat surface suitable for via-in-pad design, electroplated filling forms a continuous solid copper pillar for optimal conductivity, whereas copper paste filling provides robust thermal dissipation and structural support for larger or thicker board vias.

Advantages of electroplated filled vias

1. Facilitates the design of stacked vias and vias on pad, increasing substrate density and allowing for the application of packages with more I/O pins.

2. Improves electrical performance, aids in high-frequency design, enhances connection reliability, increases operating frequency, and avoids electromagnetic interference.

3. After electroplating, the vias are filled with copper columns, providing better conductivity than conductive resin/glue, aiding in heat dissipation and improving the thermal performance of the board.

4. Via filling and electrical interconnection are completed in one step, avoiding defects caused by filling with resin or conductive glue, and preventing inconsistencies in CTE (Coefficient of Thermal Expansion) that can occur with other filling materials.

5. Blind vias filled with electroplated copper avoid surface depressions, which is beneficial for the design and fabrication of finer circuits.

Before via filling with copper

After via filling with copper