IPC WP-023 PDF
The proliferation of copper-filled stacked microvias in printed boards has resulted in the emergence of a hidden reliability threat —a weak interface between microvia target pads and electrolytic copper fill. When subjected to thermal stress associated with reflow soldering, weak target pad interfaces are susceptible to fracture. Unfortunately, these weak microvias are often not detectable by electrical tests conducted at ambient temperature and can manifest as intermittent failures in service. Thus, weak microvias pose a significant risk as potential latent defects.
