Tuning the Ignition Performance of a Microchip Initiator by Integrating Various Al/MoO₃ Reactive Multilayer Films on a Semiconductor Bridge

Abstract

Reactive multilayer films (RMFs) can be integrated into semiconducting electronic structures with the use of microelectromechanical systems (MEMS) technology and represent potential applications in the advancement of microscale energy-demanding systems. In this study, aluminum/molybdenum trioxide (Al/MoO)-based RMFs with different modulation periods were integrated on a semiconductor bridge (SCB) using a combination of an image reversal lift-off process and magnetron sputtering technology. This produced an energetic semiconductor bridge (ESCB)-chip initiator with controlled ignition performance. The effects of the Al/MoO RMFs with different modulation periods on ignition properties of the ESCB initiator were then systematically investigated in terms of flame duration, maximum flame area, and the reaction ratio of the RMFs. These microchip initiators achieved flame durations of 60-600 μs, maximum flame areas of 2.85-17.61 mm, and reaction ratios of ∼14-100% (discharged with 47 μF/30 V) by simply changing the modulation periods of the Al/MoO RMFs. This behavior was also consistent with a one-dimensional diffusion reaction model. The microchip initiator exhibited a high level of integration and proved to have tuned ignition performance, which can potentially be used in civilian and military applications.

SHS in Ni/Al Nanofoils: A Review of Experiments and Molecular Dynamics Simulations

“…The excess Cu layers act as diffusion barriers, limiting the transport of oxygen from the oxide to the Al fuel, and decrease temperature of the self‐propagating thermite reactions below the boiling point of Cu, eliminating metal vapor production. Another example of a new composition is an aluminum/molybdenum trioxide (Al/MoO 3 )‐based RMNFs with different modulation periods that were produced using an image reversal lift‐off process and magnetron sputtering technology . These RMNFs were integrated into microchip initiators that proved to have tunable ignition performance, which can potentially be used in civilian and military applications.…”

Towards Safer Primers: A Review

“…The ratio of fuel to oxidiser in a reactive mix plays an important part in the overall energy output during ignition. For CuO and Al nanoparticles, maximum combustion speed was found to be at a fuel:oxide stoichiometry of 1.6:1, which was also observed and preferred for other metal rich reactions, including nanoparticles and thin film multilayers [54,56]. When combustion speeds increase, peak pressure maxima are greater, which makes finer reactive powders or higher surface area mixes ideal for optimising performance [63].…”

“…Materials are chosen with consideration for their availability and cost, as well as their reaction performance in terms of heat, gas, initiation energy, process rate and device integrability. Fabrication of micrometer-sized devices is a particular focus as they can be manufactured using well-established lithography and deposition techniques commonly used in the semiconductor industry [55,56]. Regardless of the material used, the performance needs to meet the standard required for the application.…”

“…This depends on multiple factors such as the composition, stoichiometry, particle or layer size for solid-state mixes and distribution (layers, particles, vertical 1D or 2D periodic structures) [19,73]. The reaction speed is tuned by changing the surface area, particle size or thickness of thin film layers and reaction temperatures are also dependent on rate, with higher temperatures reached from faster reactions [54,56,63]. Combustion speeds of thermite mixes are highly varied depending on particle size and surface area.…”

“…For example, reactive powders containing metals and oxides of various particle sizes can be added to EEDs for increased energy output [19,74,120]. Laminated coatings of Al/MoO 3 or other thermites have also been used to enhance the output energy [56].…”