Challenges with Large Area Ultra-High-Density SIP

ABSTRACT The rapid advancement of artificial intelligence (AI) processors has driven the need for high-performance packaging solutions with ultra-high density, larger die sizes, and heterogeneous integration. Large area array electronic packages have emerged as a key enabler, yet they introduce significant technical challenges across multiple domains. Among the most critical are mechanical reliability related to warpage, coefficient of thermal expansion (CTE) mismatches impact on solder joint lifecycle, manufacturability limitations associated with fine-pitch interconnects and substrate. An often overlooked but increasingly crucial issue in this context is the effective cleaning of flux residues during the die attach and motherboard attach processes. In large packages with fine-pitch interconnects, underfill materials, and complex geometries, flux residue and contaminant removal become particularly challenging. Incomplete cleaning and rinsing can lead to corrosion, electrical leakage, and long-term reliability failures. These issues are exacerbated in AI processor packages due to high thermal cycling, power density, and dense interconnect topologies. This paper explores definition of the boundary conditions where cleaning should be used considering current state and future state package roadmap requirements. Discussion will include the interplay between advanced packaging requirements and cleaning & rinsing challenges for various cleaning machine types, reviewing current cleaning methodologies, limitations of traditional chemistries and equipment, and the need for improved process control and design-for-cleanability. Baseline data will be presented for a small sample set of real test parts. Additional project work will also be discussed to support implementation of future state packages.