Records were pulled using a search string combining material terms — capillary underfill, no-flow underfill, non-conductive paste — with process and reliability terms like flow front, voiding defect, fillet height, thermal cycling reliability and reworkability. This means the dataset captures both device-level assembly claims and materials-level formulation claims, provided the record also touches on the flow, voiding, or reliability behaviour of the underfill. It excludes broader adhesive or encapsulant patents that do not reference these specific underfill mechanics.

Filing is concentrated: the top five assignees together hold 46.2% of all 1,516 records in scope, and the top ten hold 62.1%. The single leading assignee’s 418 records are far ahead of the fifth-place total of 55, so the gap at the very top is much larger than the gap between fifth and tenth place. Several of the largest historical filers, however, show sharp year-on-year declines in the most recent tracked year.

Complete-year data shows filings falling from 126 in 2021 to 100 in 2024, a 21% decline over that span, after peaking at 139 in 2023. The 2025 and 2026 figures look lower still, but publication typically lags filing by around 18 months, so those most recent years are undercounted rather than necessarily reflecting less activity. The honest read is a cooling trend after a 2023 peak, not a confirmed collapse.