Mechanical Properties of Rolled Copper Foils in Cryogenic and Room‐Temperature Environments

Yu, Hailiang; Zhao, Xinling; Kong, Charlie

doi:10.1002/adem.202100830

Cited by 4 publications

(5 citation statements)

References 28 publications

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“…The copper foil thickness in a typical SCB-build-up is 17 µm or 35 µm, like it is used in the conventional PCB manufacturing. Straight copper interconnection on this basis would typically allow elastic deformations in the order of 1% before plastic deformation sets in and the structure eventually ruptures [9]. Larger deformations without tearing up can be reached by meandering designs of the interconnects, which elongate like two-dimensional springs [1,2,8].…”

Section: Stretchable Electronics Based On Structured Copper Foilmentioning

confidence: 99%

Mechanical properties of structured copper and printed silver hybrid stretchable electronic systems

Salo

Werft

Adams

et al. 2023

Flex. Print. Electron.

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Stretchable electronics can be realized using different manufacturing methods and hybrids thereof. An example of the latter is the combination of stretchable circuit boards with screen-printing, which will be discussed in this work. The hybrid stretchable electronics structures are based on photolithographically structured and rigid copper islands and screen-printed silver ink interconnections. This enables the assembly of components with a high number of contacts onto the copper islands and deformable silver ink lines between islands. The transition area between islands and lines is critical due to local stress concentration. The effect and potential mitigations were studied by measuring the electrical resistance of test interconnections under mechanical loading. The first set of samples was elongated up to 30 % in tensile tests. The second set of samples was elongated 10 %, 20 %, and 30 % in cyclic tests up to 10.000 cycles. After the tests, extensive failure analysis, e.g., scanning electron microscope, and finite element analysis were conducted.In tensile tests at maximum load, the interconnections either snap apart or their resistance increases by 640 % in the transition area. Adding protective structures around the transition area, the resistance increase can be reduced to 12 %. Stress concentration in the transition area can be controlled with the layout of the structures, as shown in the cyclic tests. Depending on a layout, the structures protect interconnections in the transition area (resistance < 4 Ω at 10 % and 20 % throughout 10.000 cycles, and up to 5000 cycles at 30 % elongation), or with particular designs, cause fatal damage of the circuitry and fail early. The identified failure mechanism is typically fatigue damage caused by the repeated bending of the protective structure. The observed resistance increase at the interface was closely related to the crack propagation phase in the protective structures.

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Section: Stretchable Electronics Based On Structured Copper Foilmentioning

confidence: 99%

Mechanical properties of structured copper and printed silver hybrid stretchable electronic systems

Salo

Werft

Adams

et al. 2023

Flex. Print. Electron.

View full text Add to dashboard Cite

show abstract

“…High-purity copper is generally used as a substrate to manufacture superconducting strands such as NbTi/Cu composite wires and Nb 3 Sn/Cu composite wires [11,12]. At cryogenic temperature, changes in the intrinsic microstructural parameters including the dislocation density and grain boundary spacing of the copper sample affect its tensile strength and the properties of superconducting wires [13]. There are many studies on the tensile properties of high-purity copper at cryogenic temperature, such as copper foils and copper wires.…”

Section: Samplesmentioning

confidence: 99%

A tensile property measuring system for miniaturized samples from 300 K to 70 K based on pulse tube cryocooler

Shen

Zhang

et al. 2023

J. Inst.

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With the rapid development and wide application of cryogenic, superconducting and space technologies in engineering fields, measurements of the mechanical properties especially the tensile properties of small-sized samples at cryogenic temperatures are more and more important. In this study, a tensile property measuring system for miniaturized samples was designed and built, where the samples can be measured from 300 K to 70 K with a resolution of 0.1 K. The cryogenic environment was provided by a pulse tube cryocooler. The force load applied to the sample was up to 10 N with a resolution of 0.001 N. The structure of the cryogenic system and sample holders were specially designed for miniaturized samples. A control and automatic data acquisition system was used to control and acquire data from all devices of the instrument. The simulations of the stretching part under load at cryogenic temperature were performed to ensure the measurement accuracy and reliability. To verify the performance and accuracy of the system, the tensile properties of two kinds of fine high-purity copper wires were measured at both 77 K and 300 K. The tensile measurement results were discussed and the measurement uncertainty of the system was analyzed. With different clamps more kinds of mechanical measurements of miniaturized samples can be carried out on this system.

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“…In addition, the HEAp/AMCs could accumulate a large amount of stored energy with a high density of dislocations in cryogenic environment, enabling grain refinement during ACR [22,23]. The phenomenon of dynamic recovery of AMCs because heat generation during AR will not occur [24,25]. Therefore, ACR can form high-density dislocations and substructures in the HEAp/AMCs, which improves the comprehensive mechanical properties of the HEAp/AMCs [26].…”

Section: Microstructure Analysismentioning

confidence: 99%

Effect of asymmetric rolling on microstructure and mechanical properties of aluminum matrix composites

Luo

2022

IOP Conf. Ser.: Mater. Sci. Eng.

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The lightweight of structural materials was an important research focus for reduced energy consumption and transport efficiency. Aluminium matrix composites (AMCs) had the advantages of high specific strength and good wear resistance, so they were widely used in automobile, aerospace and other fields. At present, the deformation mechanism of AMCs reinforced by high-entropy alloy particles (HEAp) in asymmetric rolling was not clear. In this work, AMCs ingot reinforced with 6 wt% HEAp was prepared by stir casting process. Then the mechanical properties of HEAp/AMCs under different rolling processes were studied by asymmetric rolling (AR) and asymmetric cryorolling (ACR) processes. High-entropy alloy (HEA) had excellent strength and toughness, which imparted good deformation ability when added to AMCs as reinforcement. The microstructure of AMCs reinforced by HEAp was refined by ACR. At the same time, the HEAp/AMCs obtained by ACR displayed a higher ultimate tensile strength (UTS) than that obtained by AR. The study of ACR shows that AMCs reinforced with HEAp have good toughness. ACR can reduce the thickness of HEAp/AMCs to a greater extent so as to produce AMCs strip with excellent mechanical properties.

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Mechanical Properties of Rolled Copper Foils in Cryogenic and Room‐Temperature Environments

Cited by 4 publications

References 28 publications

Mechanical properties of structured copper and printed silver hybrid stretchable electronic systems

Mechanical properties of structured copper and printed silver hybrid stretchable electronic systems

A tensile property measuring system for miniaturized samples from 300 K to 70 K based on pulse tube cryocooler

Effect of asymmetric rolling on microstructure and mechanical properties of aluminum matrix composites

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