Study of Die Attach Epoxy Materials and Properties Affecting Substrate Trace Cracks

MAPBGA with large die to package ratio can be sensitive to electrical opens during AEC Grade 1 temperature cycling - 55C to 150C due to substrate metal trace cracks. As higher reliability requirements become more stringent, newer die attach materials need to be evaluated. The study will aim to demonstrate which critical parameters of the die attach are relevant towards increasing package robustness for higher reliability. A MAPBGA test vehicle with large die to package ratio was selected. A series of experiments were carried out with various types of epoxy die attach materials. Samples with electrical open connections after TC test were subjected to X-Ray to confirm substrate trace crack issues. The confirmed trace cracks parts were sent for failure analysis such as cross section, package de-layering and scanning electrode microscope (SEM). Detailed material characterization was performed on all the relevant package materials, with a special focus on the die attach materials. This paper will discuss the experimental results and findings, failure analysis and die attach material properties such as adhesion properties, toughness, modulus and CTE (impacting interfacial stress), to assess and compare the die attach material crack risk that could influence the MAPBGA substrate trace cracks. The study will aim to demonstrate which critical parameters & properties of the die attach materials are relevant towards increasing robustness for the observed failure mechanism.