Stress evolution in an encapsulated MEMS package due to viscoelasticity of packaging materials

Park, Seungbae; Liu, Dapeng; Kim, Yeonsung; Lee, Hohyung; Zhang, Sam

doi:10.1109/ectc.2012.6248808

Cited by 11 publications

(7 citation statements)

References 8 publications

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“…However, the magnitude and direction of this change (opposite to that observed post-packaging), along with the complete absence of any switch damage or alteration of the membrane shape, leads us to postulate that the change is due to relaxation of the silver epoxy used to attach the die to the package during the 20-day period between packaging and post-flight analysis, rather than to any effects of the flight itself. This relaxation has previously been observed in microelectronics packaging [31][32][33]. It has been further investigated by attaching five blank 3 × 3 mm 2 blank silicon die to ceramic packages using the process described in section 3.1, and by using a stylus profiler (P-10, KLA-Tencor, CA, USA) to measure the warpage at the centre of the die on a similar timescale to the original experiment, i.e.…”

Section: Modelling and Experimental Assessment Of Impact Accelerationmentioning

confidence: 90%

Reliability assessment of MEMS switches for space applications: laboratory and launch testing

O’Mahony¹,

Olszewski²,

Hill³

et al. 2014

J. Micromech. Microeng.

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A novel combination of ground-based and flight tests was employed to examine the reliability of capacitive radio-frequency microelectromechanical switches for use in space applications. Laboratory tests were initially conducted to examine the thermomechanical effects of packaging and space-like thermal stresses on the pull-in voltage of the devices; during this process it was observed that operational stability is highly dependent on the geometrical design of the switch and this must be taken in to account during the design stage. To further expose the switches to acceleration levels experienced during a space mission, they were launched on board a sounding rocket and then subjected to free-fall from a height of over 1.3 km with a resulting impact of over 3500g. Post launch analysis indicates that the switches are remarkably resilient to high levels of acceleration. Some evidence is also present to indicate that time-dependent strain relaxation in die attach epoxy materials may contribute to minor variations in device shape and performance.

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Section: Modelling and Experimental Assessment Of Impact Accelerationmentioning

confidence: 90%

Reliability assessment of MEMS switches for space applications: laboratory and launch testing

O’Mahony¹,

Olszewski²,

Hill³

et al. 2014

J. Micromech. Microeng.

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“…Park et al [12] studied the effect of cooling rate on the stress of MEMS packages. It has been shown that the cooling rate has a great impact on the stress of MEMS packages due to the intrinsic time-dependent features of polymer-based materials such as molding compound (Fig.…”

Section: Optimization Studymentioning

confidence: 99%

“…To predict the viscoelastic behavior accurately, the temperature profile for the cooling process was generated by a transient heat analysis [12]. If the nonuniformity of the package inside is neglected, the temperature change of MEMS package is expressed by…”

Section: Optimization Studymentioning

confidence: 99%

Optimal Material Properties of Molding Compounds for MEMS Package

Kim

Lee

Zhang

et al. 2014

IEEE Trans. Compon., Packag. Manufact. Technol.

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In this paper, an optimization study of molding compounds for a microelectromechanical systems (MEMS) sensor package has been performed. A comprehensive finite element analysis model was established for the MEMS sensor package to assess the stresses and deformations when the package was subjected to temperature loading. A series of stress relaxation tests were performed to characterize the viscoelastic material properties of a molding compound over temperature with dynamic mechanical analysis. A master curve for the molding compound was constructed by a proper shift function and the Prony pairs were obtained by curve fitting to be implemented in the simulation. To validate the simulation result, the thermal behavior of the MEMS package was measured. The digital image correlation technique was employed to observe the real-time deformation of the package exposed to temperature loading. The out-of-plane deformation of the package was compared with the simulation result. With the validated simulation model, the optimization study was conducted. By the process simulation, it has been shown that most of the thermal stress on the MEMS sensor chip was generated during the cooling process. Thus, a detailed cooling profile was developed by the transient heat analysis and applied to the parametric study. The modulus, coefficient of thermal expansion (CTE), and glass transition temperature (T g ) of molding compound were investigated. The result shows that a low modulus, low CTE, and low T g molding compound can minimize the thermal stress on MEMS sensor die.

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“…Especially with the rapid development of integrated circuit (IC) packaging technologies, many new types of high-viscosity adhesives have been applied for realizing high-density assembly [3,4]. This trend requires that the liquid dispensing system can transfer the adhesives more accurately, rapidly, and flexibly.…”

Section: Introductionmentioning

confidence: 99%

Bond-graph model of a piezostack driven jetting dispenser

Liu

Yao

et al. 2014

Simulation Modelling Practice and Theory

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a b s t r a c tMicro liquid jetting technology is widely used in the field of electronic packaging. This paper presents a bond-graph model of a piezostack driven jetting dispenser that can dispense adhesive fluids accurately, rapidly, and flexibly. After describing the structural components and operating principles of the dispenser, the bond-graph model for the system is derived by integrating the electromechanical model with the fluid model. In the bond-graph model, the lumped parameter method is employed to obtain the conceptual bond-graph elements of the adhesive in the channels. Based on the proposed model, the jetting dispenser is designed and manufactured, and its performance is then evaluated through both computer simulations and experiments. Further simulation studies about the working properties based on the bond-graph model is carried out.

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Stress evolution in an encapsulated MEMS package due to viscoelasticity of packaging materials

Cited by 11 publications

References 8 publications

Reliability assessment of MEMS switches for space applications: laboratory and launch testing

Reliability assessment of MEMS switches for space applications: laboratory and launch testing

Optimal Material Properties of Molding Compounds for MEMS Package

Bond-graph model of a piezostack driven jetting dispenser

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