Method development for the cyclic characterization of thin copper layers for PCB applications

Fellner, Klaus; Fuchs, Peter; Pinter, Gerald; Antretter, Thomas; Krivec, Thomas

doi:10.1108/cw-09-2013-0032

Cited by 9 publications

(7 citation statements)

References 11 publications

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“…Specimens consisting of alternating layers of copper and FR4-prepreg were used; a suitable fixture was developed in earlier work. 24 It was installed in a MTS 810-22 (MTS, Eden Prairie, MN, USA) testing machine for the measurements at 23 °C and in a MTS 831 testing machine for the measurements at 85 °C and 145 °C. The gage length was 5 mm to avoid buckling.…”

Section: Experimental Characterizationmentioning

confidence: 99%

“…They were calculated by micromechanic simulations. The measurements and the complementary simulations are described in detail in Fellner et al, 24 Fuchs et al 30 and Fellner. 31 The elastic properties of the copper foil were measured using a micro-dynamic mechanical analyzer.…”

Section: Experimental Characterizationmentioning

confidence: 99%

“…In previous work, thin copper layers for PCB applications were tested in cyclic tension–compression tests at different temperatures. 24 In these tests, composite specimens consisting of layers of copper and of glass fiber-reinforced epoxy resin were used. The kinematic and isotropic hardening behaviors were determined from the resulting hysteretic force–strain curves.…”

Section: Introductionmentioning

confidence: 99%

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Cyclic mechanical behavior of thin layers of copper: A theoretical and numerical study

Fellner

Antretter

Fuchs

et al. 2015

The Journal of Strain Analysis for Engineering Design

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In printed circuit boards, thin copper layers are used as current paths. During the thermal loading of printed circuit boards, stresses arise due to the different coefficients of thermal expansion of the used materials. To be able to model the mechanical behavior of printed circuit boards under cyclic thermal loads, cyclic mechanical tests of thin copper foils under changing tensile and compression loads at different temperatures were conducted. From these experiments, the isotropic and kinematic hardening parameters were determined serving as material input data for a nonlinear isotropic/ kinematic hardening model in the finite element analysis-software Abaqus. The kinematic hardening parameters were fitted in an optimization process. The isotropic hardening variables were determined based on the stress versus plastic strain relationship that was constructed incrementally from the available individual cycles. The so-obtained curve was found to be not unique, but to depend on the loading situation. Hence, different approaches for strain range memorization were evaluated. Since these approaches were developed for modeling strain-controlled tests, whereas the experimental data were obtained in a force-controlled way, a phenomenological formulation was developed and applied. The results of curvature measurements during thermal cycling were used for model validation. The experimental results and the numerical predictions are in good agreement.

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Section: Experimental Characterizationmentioning

confidence: 99%

Section: Experimental Characterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cyclic mechanical behavior of thin layers of copper: A theoretical and numerical study

Fellner

Antretter

Fuchs

et al. 2015

The Journal of Strain Analysis for Engineering Design

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“…Thus from the overall and substrate responses, the authors were able to define the stress-strain response of the copper alone, nevertheless neglecting the transversal stress induced in the film due to the mismatch in Poisson's ratio between the substrate and the copper film. One can also refer to Mönig et al (2004), Kraft et al (2001) or Fellner et al (2014) for similar experiments and copper characterization. It has been also observed that microstructural features influence the mechanical response of copper film.…”

Section: Introductionmentioning

confidence: 99%

Cyclic response of electrodeposited copper films. Experiments and elastic–viscoplastic mean-field modeling

Girard

Frydrych

Kowalczyk-Gajewska

et al. 2021

Mechanics of Materials

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The goal of the present work is to identify and model the elastic-viscoplastic behavior of electrodeposited copper films under tension-compression loadings. From the experimental point of view, as proposed in the literature, a film of copper is electrodeposited on both sides of an elastic compliant substrate. The overall specimen is next subjected to tensile loading-unloadings. As the substrate remains elastic, the elastic-plastic response of copper under cyclic loading is experimentally determined. A clear kinematic hardening behavior is captured. To model the mechanical response, a new elastic-viscoplastic self-consistent scheme for polycrystalline materials is proposed. The core of the model is the tangent additive interaction law proposed in (Molinari, 2002). The behavior of the single grain is rate dependent where kinematic hardening is accounted for in the model at the level of the slip system. The model parameters are optimized via an evolutionary algorithm by comparing the predictions to the experimental cyclic response. As a result, the overall response is predicted. In addition, the heterogeneity in plastic strain activity is estimated by the model during cyclic loading.

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“…At the same time, the low processing temperature makes Cu as an ideal internal electrodes for MLCs . It is well‐known that Cu electrodes have been widely used in the PCBs and IC chips . The low processing temperature avoids the oxidation of Cu layers during the thermal processing of the MLCs.…”

Section: Introductionmentioning

confidence: 99%

Bismuth Zinc Niobate Thin Film Multilayer Capacitors with Cu Electrodes Fabricated at Low Temperature by RF Magnetron Sputtering

Ren

Khan

et al. 2016

J. Am. Ceram. Soc.

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Thin film multilayer capacitors (MLCs) composed of amorphous Bi1.5Zn1.0Nb1.5O7 (BZN) dielectric layers with Cu internal electrodes were fabricated by radio‐frequency magnetron sputtering at a temperature below 150°C. Both BZN thin films and Cu internal electrodes were deposited in situ through a set of steel shadow masks at room temperature and postannealed at 150°C. The BZN dielectric layers used in the MLCs are amorphous and the thickness for each BZN layer is approximately 220 nm. Metallic Cu layer used as the internal electrode is about 50 nm thick. Auger electron spectroscopy analysis indicates that there are no diffusion between BZN films and Cu electrodes, as well as no oxidation of Cu electrodes during the fabrication process owing to room‐temperature deposition and low‐temperature postannealing (150°C). The thin film MLCs with different number of BZN layers were fabricated. The thin film MLCs with five BZN layers exhibit promising properties with dielectric constant of 72, capacitance density of 1600 nF/cm2, and loss tangent of 5.4% at 10 kHz. These results suggest that the BZN thin film MLCs have potential applications for the embedded PCBs.

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Method development for the cyclic characterization of thin copper layers for PCB applications

Cited by 9 publications

References 11 publications

Cyclic mechanical behavior of thin layers of copper: A theoretical and numerical study

Cyclic mechanical behavior of thin layers of copper: A theoretical and numerical study

Cyclic response of electrodeposited copper films. Experiments and elastic–viscoplastic mean-field modeling

Bismuth Zinc Niobate Thin Film Multilayer Capacitors with Cu Electrodes Fabricated at Low Temperature by RF Magnetron Sputtering

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