Definition

Via filling completely fills the via hole with either conductive (copper or silver-filled) or non-conductive (epoxy) material. Conductive fill is required for stacked micro-vias in HDI designs, providing electrical continuity and thermal dissipation. Non-conductive fill is used for via-in-pad where electrical connection through the via isn't needed. Filled vias are typically planarized (ground flat) and may be capped (plated over). Via filling is more thorough than plugging, leaving no void in the hole.