Rainer Tilgner

A simple model for the mode I popcorn effect for IC packages

Abstract A simple model for the Mode I popcorn effect is presented here for packages with rectangular die pad (P-DSO). A package “stability parameter”, relating to its moisture sensitivity, is derived from the popcorn model. It describes the critical factors for a robust package - molding compound properties and package, leadframe design for a given preconditioning and soldering process. Furthermore, nomograms generated from the model enable an easy estimation of moisture sensitivity levels (between 1 and 5) of packages with different die pad sizes and molding compound underpad thicknesses and for different soldering temperatures ranging from 220°C to 260°C (Pb-free soldering).

Advanced thermal failure analysis and reliability investigations Industrial demands and related limitations.

The thermal interaction between actively operated integrated circuits and applied characterization tools is one of the most important ones within failure analysis (FA) and reliability/methodology (RM) investigations. Hereby different kind of thermal interaction mechanisms can be utilized, whereas these mechanisms have to be separated for instance into classes with respect to thermal excitation and/or detection, spatial limitations, and underlying physical principle. Although they all have in common the capability to link the thermo-electric device characteristic to a representing output signal, they have to be interpreted in completely different ways. Therefore, within this paper we discuss from a practical engineering point of view established FA/RM characterization techniques by means of infrared-lock in thermography (IR-LIT) and thermal induced voltage alteration (TIVA) case studies as well as the capability of non established ones like scanning thermal microscopy (SThM), thermal reflectance microscopy (TRM), and time domain thermal reflectance (TDTR). Hereby we focus on the complementarities of the methods for localization and characterization as well as on the according industrial demands and related limitations.

Numerical evaluation of miniaturized resistive probe for quantitative thermal near-field microscopy of thermal conductivity

Modern applications of source characteristic based quantitative thermal microscopy in the nanometer regime require optimized probe characteristics with respect to both, geometry and electrical / thermal dynamic source behaviour. Within this field of dynamic techniques completely different approaches are available. Exemplarily for these different approaches the capability of a special resistive thermal probe will be investigated by means of transient 3D thermal electrical coupled Finite Element Analysis (FEA) within this work.

Scanning Acoustic Microscopy Covering a Wide Temperature Range: SAM(T)

The reliability of plastic encapsulated microchips is strongly influenced by temperature. Scanning Acoustic Microscopy (SAM) is established as an indispensable non-destructive analytical tool to evaluate mechanical failures such as cracks or delaminations imposed by reliability tests within electronic components. They are investigated by SAM at room temperature after a treatment by thermal stress. Thus, the very failure mechanisms due to the thermal effects remain in dark. In this work we present for the first time the growth and change of delaminations in integrated circuit devices under thermal stress from -60°C to 150°C in a real temperature manner. For this SAM(T) was established, a SAM with the particular feature to change the temperature of the object and to record its changes online. This kind of results may be used as valuable input for future work on virtual reliability testing for microelectronics.