Experimental validation of external load effects on micro-contact performance and reliability

Laurvick, Tod V.; Coutu, Ronald A.

doi:10.1109/holm.2015.7355120

Cited by 3 publications

(4 citation statements)

References 6 publications

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“…12. 9 The two curves in this plot show data from two different devices, one that lasted for 10 M cycles without incident ("stable contact" in Fig. 12) and one that failed before that point ("failing contact" in Fig.…”

Section: B External Circuit Loading Testsmentioning

confidence: 99%

“…13. 9 In Fig. 13 (bottom and top), an expanded view of the larger image is provided of a beam folded back with a probe, and close-up views of both sides of the microcontact are provided, respectively.…”

Section: B External Circuit Loading Testsmentioning

confidence: 99%

“…Looking to prior efforts in mitigating these device failures, it has been demonstrated that external circuitry can have a significant effect under dc conditions. 9 While the motivation for this protective circuitry has been to address hot-switching damage, testing the effectiveness of this sort of protection with low-frequency ac loads is the next task. Thus, the goal is to investigate not only how microcontacts behave during closure with an ac load, but also the effects of this polarity reversal during cold-switching in a closed microcontact, how performance and reliability are altered under these conditions, and whether these effects be can mitigated.…”

Section: Introductionmentioning

confidence: 99%

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Improving Gold/Gold Microcontact Performance and Reliability Under Low-Frequency AC Through Circuit Loading

Laurvick

Coutu

2017

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

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This paper investigates the performance and reliability of microcontacts under low-frequency and lowamplitude ac test conditions. Current microcontact theory is based on dc tests adapted to RF applications. To help better apply dc theory to RF applications, frequencies between 100 Hz to 100 kHz were experimentally investigated. Microcontacts designed to conduct performance and reliability measurements were used, which in prior dc testing typically lasted for 100 million cycles or more. Under ac loads, at similar power levels, eight devices were tested under cold-switching conditions, and only one was still operational at 10 million cycles. The effect of external circuitry on dc loaded devices was also considered. The experimental data were presented for dc conditions, which demonstrated that both a parallel capacitance with a microcontact and a series inductance were highly detrimental. For all six tested devices, failure occurred typically in 100 thousand cycles or less. However, utilizing series resistive/capacitive circuits as well as parallel resistor/inductive resulted in improved performance, with only one device of the four tested failing prematurely, but those that lasted showed less variation in measure contact resistance throughout the lifetime of the device. Two devices were tested with passive contact protection using parallel and series resistances, and both devices lasted for the full test duration. Finally, the effects of applying circuit protection to microcontacts and repeating ac test conditions were investigated. Reliability and device lifetime were extended significantly (9.1% success rate without protection was increased to 87% success rate). It was also observed in several instances that devices that failed showed subtle signs of variance during contact closure measurements in the range of 5-30 μ N, indicating a possible means for accurately predicting device failure. For these failed devices, notable physical damage was observed using a scanning electron microscope.

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Section: B External Circuit Loading Testsmentioning

confidence: 99%

Section: B External Circuit Loading Testsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Improving Gold/Gold Microcontact Performance and Reliability Under Low-Frequency AC Through Circuit Loading

Laurvick

Coutu

2017

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

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“…An important consideration for the reliability of a microswitch is the external load circuit. In [135], Laurvick et al experimented with several different load configurations in conjunction with a microswitch, including combinations of resistive, reactive, and capacitive loads in parallel and series. A reactive load in series with the microswitch caused the maximum damage to the switch, yielding a reported contact lifetime as little as 1000 cycles.…”

Section: Reliability Of Ohmic Mems Contactsmentioning

confidence: 99%

A review of micro-contact physics, materials, and failure mechanisms in direct-contact RF MEMS switches

Basu

Adams

McGruer

2016

J. Micromech. Microeng.

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Direct contact, ohmic MEMS switches for RF applications have several advantages over other conventional switching devices. Advantages include lower insertion loss, higher isolation, and better switching figure-of-merit (cut-off frequency). The most important aspect of a direct-contact RF MEMS switch is the metal microcontact which can dictate the lifetime and reliability of the switch. Therefore, an understanding of contact reliability is essential for developing robust MEMS switches. This paper discusses and reviews the most important work done over the past couple of decades toward understanding ohmic micro-contacts. We initially discuss the contact mechanics and multi-physics models for studying Hertzian and multi-asperity contacts. We follow this with a discussion on models and experiments for studying adhesion. We then discuss experimental setups and the development of contact test stations by various groups for accelerated testing of microcontacts, as well as for analysis of contact reliability issues. Subsequently, we analyze a number of material transfer mechanisms in microcontacts under hot and cold switching conditions. We finally review the material properties that can help determine the selection of contact materials. A trade-off between contact resistance and high reliability is almost always necessary during selection of contact material; this paper discusses how the choice of materials can help address such trade-offs.

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Experimental Validation of External Load Effects for Micro-Contacts under Low Frequency, Low Amplitude Alternating Current (AC) Test Conditions

2018

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Abstract:The use of micro-contacts has been demonstrated in various radio frequency (RF) applications. However, the premature failure of such devices under alternating current (AC) operations is still a hurdle to further development. In this work, modified gray scale lithography is performed to fabricate two types of gold-gold (Au-Au) micro-contacts: hemispherical-planar and hemispherical-2D pyramid. The performance of these devices was investigated under low frequency, low amplitude AC conditions with external circuit loads. A custom-made experimental setup which uses various load configurations, controls the frequency of the applied voltage and modifies the cycle rate of switch operation to obtain the contact resistance as a function of number of cycles (up to 10 7 cycles). Nearly 87% of the tested devices (13 out of 15 hemispherical-planar micro-contacts) were found to be in good operational condition and passed the 10 million cycle mark successfully. A steady gain and large swing in the value of contact resistance was also observed near the end of all, but one, tests. Such changes in contact resistance were found to be permanent as none of the devices recovered completely. On the other hand, the hemispherical-2D pyramid micro-contact performed better than the planar one as it also passed 10 7 cycle mark with low and remarkably stable contact resistance throughout the testing span. This study suggests that micro-contacts with 'engineered' surface structures with external loads applied are a viable solution to premature failure and high contact resistance in micro-contacts under low frequency AC operations.

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Experimental validation of external load effects on micro-contact performance and reliability

Cited by 3 publications

References 6 publications

Improving Gold/Gold Microcontact Performance and Reliability Under Low-Frequency AC Through Circuit Loading

Improving Gold/Gold Microcontact Performance and Reliability Under Low-Frequency AC Through Circuit Loading

A review of micro-contact physics, materials, and failure mechanisms in direct-contact RF MEMS switches

Experimental Validation of External Load Effects for Micro-Contacts under Low Frequency, Low Amplitude Alternating Current (AC) Test Conditions

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