Manufacture of some SIMS components from tantalum foils by electrolytic photoetching

Allen, D.M.; Gillbanks, P.J.

doi:10.1016/0141-6359(85)90100-x

Cited by 6 publications

(5 citation statements)

References 7 publications

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“…EMM has been used in the past for machining chemically resistant metals like Ti, Ta, Zr, and Nb. 9 Allen and Gillbanks 10 performed EMM of Ta in a solution of 5% by volume sulfuric acid in methanol. A uniform etch rate over the anode surface was obtained for an applied cell voltage of 10 V. These studies, however, give very little information on the role of prevailing electrochemical conditions.…”

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confidence: 99%

Through‐Mask Electrochemical Micromachining of Titanium

Madore

Piotrowski

Landolt

1999

J. Electrochem. Soc.

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Through-mask electrochemical micromachining (EMM) involves high speed selective metal dissolution from unprotected areas of a photoresist-patterned workpiece that is made an anode in an electrolytic cell. Compared to chemical etching, electrochemical dissolution offers higher rates and better control on a micro-and macro-scale of shape and surface texture of anodically dissolved materials. 1,2 EMM is receiving considerable attention in the electronics industry for thin film patterning. 3 In recent years, there has been an increasing demand for the micromachining of titanium. Due to their good mechanical properties and chemical inertness, titanium and titanium alloys have attracted considerable interest in the chemical process, aerospace, and biomedical industries. Fabrication of well-defined microstructures with controlled surface finish on titanium has become key in the biomedical industry for producing implants with improved biocompatibility 4-7 as well as miniaturized implantable devices. 8 For such applications, electrochemical micromachining (EMM) is promising in view of its flexibility and cost effectiveness.EMM has been used in the past for machining chemically resistant metals like Ti, Ta, Zr, and Nb. 9 Allen and Gillbanks 10 performed EMM of Ta in a solution of 5% by volume sulfuric acid in methanol. A uniform etch rate over the anode surface was obtained for an applied cell voltage of 10 V. These studies, however, give very little information on the role of prevailing electrochemical conditions. Rosset et al. 11,12 studied shape change during the dissolution of a type 304 stainless steel through an unevenly spaced pattern of lines into a 6 M NaNO 3 electrolyte. Using a flow-channel cell, they investigated the influence of current density and hydrodynamic conditions on the profile shapes and surface finish. The current distribution between anodes and hence the etch rate was found to be more uniform when dissolution is mass-transport controlled. The maximum current that could be applied was limited by Joule heating of the electrolyte in the developing etch grooves. Datta 13 employed EMM to fabricate an array of precision nozzles in copper and stainless steel foils for application in ink-jet printer heads. Nozzles of desired shape with microsmooth surfaces were obtained by dissolving at the limiting current plateau or at high voltages. The use of pulsating voltage provided a better control over the nozzle fabrication process because of the possibility of applying high instantaneous current density while maintaining a low average current. Shape evolution during the electrochemical etching of lines and holes into thin metal films sandwiched between a photoresist mask and an insulating support has been simulated by West et al. 14 assuming the primary current distribution approximation. Both small and large aspect ratio of photoresist thickness to cavity width were considered. The calculated shapes were compared with the experimental results of Rosset et al. 12 The fair agreement obtained between theory and ex...

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confidence: 99%

Through‐Mask Electrochemical Micromachining of Titanium

Madore

Piotrowski

Landolt

1999

J. Electrochem. Soc.

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“…The most common electrolyte constituents are H 2 SO 4 or LiCl, which are dissolved in methanol or ethanol. These solutions are primarily applied to the machining of difficultto-etch metals and alloys, including nickel, 91,119,126 tantalum, 177,178 titanium, 35,[50][51][52]57,107,122,130,179,180 tungsten, 91 and nickel-titanium alloys. 54,56,91,[181][182][183][184] During immersion etching, typical etch rates are on the order of 5-15 μm min −1 .…”

Section: Metals and Electrolytesmentioning

confidence: 99%

“…This is because specific safety concerns arise due to the toxicity, flammability and limited long-term stability of such mixtures. 177,178 For this reason, less-toxic and non-flammable solvents, such as ethylene glycol, 193 should be given priority for future work on TMEMM of difficult-to-etch metals. In this regard, novel EP electrolytes based on ionic liquids also represent a promising avenue for further research.…”

Section: Metals and Electrolytesmentioning

confidence: 99%

“…68 In the PCM industry, tantalum and titanium are among the difficultto-etch metals, which necessitate the use of aggressive etchants, such as hydrofluoric/nitric acid and aqua regia. 28,124,229 By comparison, safer alternatives can be used in TMEMM, like methanol/sulfuric acid 124,177 or saline solutions. 91 In the case of stainless steel, acidified ferric-chloride etchants 28 can be substituted with concentrated NaCl electrolytes.…”

Section: Technical and Financial Considerationsmentioning

confidence: 99%

“…Note that switching to TMEMM is accompanied by time savings due to increased etch rates. 111,177 Despite the capability to mass-produce parts at low cost, the continued use of PCM for microreactor fabrication is limited by technical constraints. 66 The isotropic nature of the process leads to combined perpendicular and lateral etching, which result in large undercuts of the mask.…”

Section: Technical and Financial Considerationsmentioning

confidence: 99%

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Review—Through-Mask Electrochemical Micromachining

Baldhoff

Nock

Marshall

2018

J. Electrochem. Soc.

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Through-mask electrochemical micromachining (TMEMM) is a versatile microfabrication technique, which combines anodic metalshaping and -finishing steps in a single operation for the purpose of microstructuring a wide range of electrically conductive materials. It has been extensively utilized for the manufacture of precision-engineered components in microsystems, such as microlenses, microprobes, microactuators, microchannels and microvalves. This is because TMEMM is able to mass-produce parts; it is applicable to difficult-to-etch materials and operable under polishing conditions. This review provides an in-depth summary of the current state of TMEMM and presents key concepts relevant to its application. To this end, the interplay between the current distribution, mass-transfer effects and surface-film formation is discussed, and its effect on the machining rate, shape profile and surface finish is highlighted. Also, past incarnations of TMEMM are reviewed in terms of their masking method, substrate material, electrolyte composition and technical application. Techno-economic aspects of TMEMM are debated in relation to potential rival techniques, taking microreactor fabrication as an example for a novel area of application. This is followed by an overview of process variations and recent developments.

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