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Epoxy based polymers are widely used as thermal or / and electrical interfaces and as encapsulation material in the semiconductor industry. In order to shorten the product development process, simulation plays a more and more important role, especially in a very early design stage. Accurate description of the thermo-mechanical behavior of the individual materials is crucial for quantitative finite...
This paper presents the comparison of the simulation capabilities of material behaviors based on the linear viscoelastic (LVE) model and non-linear viscoelastic (NLVE) model for a commercially available molding compound. Both modeling approaches do consider the effect of time and temperature dependency. However, it is found that the LVE modeling technique is not capable of reproducing the large strain,...
The new age product development demands rolling out effective & efficient designs in short time span and reduced costs in the view of increased competition from market players. This requires the time conventionally needed for conceptualization and validation of new designs has to be significantly reduced without having to compromise on the quality. In order to determine the optimized variant,...
Thermoset-based adhesives are used as thermal and electrical interfaces. In automotive applications, they are required to have excellent adhesion since delamination may precipitate other electrical, thermal or mechanical failure mechanisms. A vast amount of literature is available on the investigation of molding compounds and various material interfaces. However, only very few studies focus on delamination...
This paper presents material characterization utilizing static tensile tests until failure and static tests with relaxation segments until failure for commercially available molding compound. In order to model the material behavior quantitatively a non-linear viscoelastic (NLVE) Bergstrom-Boyce model (BB) is proposed. Material constants of the BB model are optimized utilizing commercially available...
Thermoset-based adhesives are used as thermal and electrical interfaces. These adhesives are filled with different particles in order to meet the requirements of heat transfer and electrical properties. In automotive applications, they are required to have excellent adhesion since bulk cracking and/or delamination may precipitate other electrical, thermal or mechanical failure mechanisms. With the...
Thermoset-based adhesives are used as thermal and electrical interfaces. These adhesives are filled with different particles in order to meet heat transfer and electrical properties. In automotive applications, they are required to have excellent adhesion since delamination may precipitate other electrical, thermal or mechanical failure mechanisms. A vast amount of literature is available on the investigation...
Highly filled epoxy-based adhesives are used as thermal and electrical interfaces in automotive electronics. The successful design for reliability of electronic packages depends on understanding and modeling the fatigue behavior of these materials. Both mechanical and thermal loadings are varying in a cyclic manner in test or field conditions. To establish an adequate constitutive model describing...
Electronic packages in automotive industry are prone to harsh environmental attacks such as extreme temperatures, high temperature variations, shocks, vibrations, humidity and hazarding liquids. Plastic encapsulation is introduced to protect the electronic part by molding a compound material around it. This has been proven as a powerful solution to these challenges. Interfacial delamination is one...
In this paper internal stress state measurements in a large molded electronic control unit are discussed. Measurements were done during transfer molding process in a high volume production environment. In addition, the effect of the post mold cure (PMC) was investigated. Tests were done utilizing piezoresistive stress sensors and thin film strain gages. For some parts post mold cure was done in parallel...
Epoxy-based adhesives are used as thermal and electrical interfaces. These interfaces require excellent adhesion, heat transfer, and electrical properties. Due to the difference in material properties, adhesive failure and delamination remain an integral part of the reliability issue since adhesive rupture or delamination may induce other electrical or mechanical failure mechanisms. Aim of this work...
Numerical simulation plays an important role in product design. Its accuracy relays on a detailed description of geometry, material models, load and boundary conditions. This paper focuses on a new approach of FEM material modeling of three commercially available molding compounds. Curing shrinkage, modulus of elasticity and coefficient of thermal expansion were measured and implemented into commercially...
Curing effects and difference in thermal contraction of components cause residual stresses and warpage during encapsulation of electronic packages. Residual stresses combined with thermal and mechanical loads influence package reliability and performance and may eventually lead to product failure. Comprehensive material characterisation is needed in order to perform numerical simulations which take...
The paper reports the results of a systematic improvement project on the thermal cycle (TC) lifetime prediction of BGA memory modules with SnAg1.0Cu0.5 and SnAg1.0Cu0.5Ni0.05 solder alloys. The pre-existing lifetime modeling scheme allowed predictions with an inaccuracy factor of about 1.6plusmn1 on average while in TC experiments, the characteristic lifetime, N63, showed a standard deviation of about...
The paper reports a comprehensive study on accelerated temperature cycling tests. Based on a DoE test plan, multiple accelerated temperature cycling tests were performed on different SMT soldered 512Mb FBGA daisy chain packages. The thermo-mechanical behavior of two SnAgCu solder alloys was studied. A sensitivity analysis assessed the effects of the TC stress tests factors on the characteristic lifetime...
Modal, harmonic and transient simulations have been performed on typical electronic modules consisting of a printed circuit board to which ball grid array (BGA) components are mounted. The BGA solder joints are modeled as continuous layers applying effective values for stiffness and density. This way, the simulation run time was minimized without reducing the accuracy of the targeted global results:...
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