Among various materials, polymers are widely used in microelectronics as different product constituents, such as encapsulants, conductive or non-conductive adhesives, underfills, molding compounds, insulators, dielectrics, and coatings. The behavior of these polymer constituents determines the performance, such as functionality and reliability, of the final products. Therefore, the successful development of microelectronics depends on, to some extent, the optimal design and processing of polymer materials. Due to the development trends of microelectronics, characterized mainly by ongoing miniaturization down to the nano scale, technology and functionality integration, eco-designing, shorter-time-to-market, development and application of polymers become one of the bottlenecks for microelectronic industry. Aiming at optimizing the product/process development, we have been spending a lot of effort to understand and design polymer behavior in microelectronics, such as material pre-selection, processing, characterization and modeling. Although these efforts are necessary, the ultimate benefits can only be realized if the relationship between chemistry and the behavior can be understood and predicted. This paper presents some results of our effort to establish the links between chemical details of the polymers and microelectronics reliability.@en

In the electronics industry epoxy molding compounds, underfills and adhesives are used for the packaging of electronic components. These materials are applied in liquid form, cured at elevated temperatures and then cooled down to room temperature. During these processing steps residual stresses are built up resulting from both cure and thermal shrinkage. In order to minimize these stresses inorganic fillers are added. These fillers have several opposing effects on the residual stresses because they decrease the cure shrinkage and thermal contraction but increase the modulus below and above the glass transition temperature. In this paper an extensive study on the cure-dependent rubbery moduli of a series of silica spheres filled epoxy resins is carried out both experimentally and theoretically. Low frequency dynamic mechanical analysis (DMA) was used to measure the rubbery modulus build-up during cure. A model based on scaling analysis was applied to describe the evolution of the rubbery shear modulus. The effect of the filler percentage on the rubbery shear and bulk moduli as well as the coefficients of thermal expansion were measured and compared with models from the theory of particulate-filled composites.@en

In order to calculate cure induced stresses, reliable material data is needed over a large modulus range. This paper concerns the derivation of correction equations needed for the interpretation of dynamic mechanical experiments on two different shear tools. For the first shear tool, consisting of an excitator plate sliding between two fixed parallel plates, the effect of the finite clamp stiffness on both the elastic and the viscoelastic modulus components are discussed. It turns out that this shear tool produces reliable results for modulus values in the range from 200 MPa and lower. The second shear tool consists of two parallel leaf springs between which the initially fluid sample is introduced. Clamping of the leaf spring ends and vertical displacement of the center then causes the sample to shear. Exact as well as approximate analytical solutions for the force¿displacement relation are derived and are shown to compare well with finite element results. This second shear tool has a typical measuring range for modulus values of 20 MPa and higher.@en

Warpage is a critical issue for QFN array molding process. In this paper, a cure-dependent viscoelastic constitutive model is established to model the cure-induced warpage in array molding process. For the relaxation modulus functions of the packaging polymer , the equilibrium moduli are modeled with a model based on scaling analysis and the relaxation behavior of the transient part is described by the cure-dependent relaxation amplitude and reduced relaxation times which are based on the time-conversion superposition principle. The cure-dependent parameters are characterized by using an integrated approach of dynamical mechanical analysis (DMA) and differential scanning calorimetry (DSC) measurements. Finite element modeling is carried out for three configurations of a carrier package during the curing process has significant contribution on the toal warpage of the map.@en

In order to establish the possible influence of residual stress and strain fields after cure on the failure prediction of electronic packages, cure-dependent viscoelastic constitutive relations for the applied polymers are required. This paper gives an overview of progress in the field of viscoelastic modeling and characterization of applied polymers over the past few years. It also discusses limitations and needs for future development.@en

Package warpage, interface delamination and thermal fatigue are the major reliability concerns for micro-electronic packages, caused by mismatch in thermal expansion together with residual stress originating from the curing process of the packaging polymers. To investigate the influence of the residual stress- and strain fields on the failure predictions and to optimise the product for reliability, cure-dependent viscoelastic constitutive relations for the applied polymers are required. The present paper gives an overview of recent progress in establishing such relations. A model moulding compound is used for cure dependent characterization and is subsequently used for QFN package moulding. The modelled and the experimentally obtained warpage have been compared.@en

In microelectronic industry, thin polymer layers are one of the more commonly used product constituents. Examples are glue layers, coatings, and dielectric layers. The thicknesses of these films vary from a few tens of nanometers to over a hundred micrometers. Since at film thicknesses below 100 nm the thermal and mechanical properties start to deviate from those in the bulk, adequate characterization techniques are required. In the present paper we will report the results of an extensive literature search on the state-of-the-art of thermo-mechanical thin film characterization methods, such as the substrate curvature test, nanoindentation technique, bulge test, and impulsive simulated thermal scattering.@en