D.M. Allen

Quantitative Examination of Photofabricated Profiles. Part 5: Effect of Stencil Integrity on Etch Factor and the Deep Etching of Stainless Steel

AbstractFor satisfactory deep etching of metals through a photoresist stencil, the stencil must remain intact and adherent, i.e. maintain its integrity. Meeting this requirement depends on the extent to which resist physical properties and thickness enable the stencil to withstand buffetting by etehant spray. Mechanical breakdown of the stencil set a limit to the width of the undercut stencil flap that could survive, and hence restricted the depth of etch achievable. Conversion coaling (passivation) of stainless steel, considered to improve adhesion, increased the etch factor but also caused formation of deep pits and rough edges.

Production of spring steel camera shutter blades by photoetching

Abstract The feasibility of producing spring steel shutter blades to exacting specifications by photofabrication has been studied. In comparison with the current production method, stamping, some advantages of using photofabrication are apparent and it is possible that economic advantages might accrue with an ‘in-house’ photofabrication facility capable of producing a range of components

Properties of Liquid Photoresists used in the Photoetching of Stainless Steel

In the use of liquid photoresists for photoetching, measurement of coating thickness is important for process control. Relative average thickness can be determined from weight/unit areas, but value...

Surface textures and process characteristics of the electrolytic photoetching of annealed AISI 304 stainless steel in hydrochloric acid

Abstract Electrolytic photoetching of AISI 304 stainless steel surfaces in 10% (w/w) hydrochloric acid has been studied. A surface texture value of 1.35 μm ( R a ) has been measured for a commercially acceptable rate of etch (10 μm/min). Comparisons of this etching system with FeCl 3 -HCl-H 2 O spray systems used in conventional photochemical machining have also been made

Quantitative Examination of Photofabricated Profiles Part 4. Photoetched Profiles in Mild Steel

Part 1 of this series described an experimental procedure for following the development of edge profile of photoetched parts at all stages of the etching process. The procedure has now been used to study the etching of stainless steel: a metal with valuable properties but reputed to be difficult to handle. The depth of downward etching increased linearly with time, but with gaps in the resist narrower than 0.2 mm the rate decreased markedly with decreasing width. Sideways etching (undercut) also progressed linearly with time, but was less dependent on the line width. The results confirmed that the experimental procedure (described in Part 1) produced the desired data. Results obtained were consistent with current published statements about the state of the art. They provided data for adjustment of conditions needed to produce specified performance for a production run. In addition, comparison of results given by two different photoresists and two different etching baths demonstrated the ability to...

Quantitative Examination of Photofabricated Profiles. Part 3. Measurement of Etch Factor

AbstractAlthough “etch factor” is a basic concept in photomechanical systems, no detailed examination of the problems of its determination is known to the authors in the open (unrestricted) literature. This paper aims to fill that void and also defines a new parameter named Bar Etch Factor.

Photoetching of narrow deep slots for stylus wear standards

Abstract The performance of surface texture instruments needs to be assessed periodically. Although a step height standard checks vertical magnification and an R a standard checks mathematical integration, no stylus wear standard was available for checking resolution. Such a standard has now been produced with vertical-walled slots of widths 2.5, 5, 10 and 20μm, and a minimum depth of 42.4μm, made by anisotropic photoetching of polished silicon slices. During exposure of photoresist the slots were aligned with a crystal cleavage plane to control line width and this was achieved using a circular table to orientate the slice with a chrome-on-glass mask. These stylus wear standards are now commercially available

Preparation of specimens for microscopic examination of edge profiles

A method of mounting small fragile components in an optically clear medium has been developed which results in good edge retention on an undistorted specimen.

Radial grating master making

Abstract Automatic measuring systems, based on the formation of moire interference fringers between two gratings, are used for the incremental control of linear and rotary movements in machine tools and instruments. Photoetched chrome-on-glass radial grating masters and photocopies of high quality can be made on a cnc rotaty table using positive photoresists, a continuous ultra-violet light source, and proximity printing in yellow safe-light illumination

Production of High Resolution Photoetched Stainless Steel Plaques

AbstractDecorative plaques on stainless steel were made by photoetching. using as a mask a 30 : 1 reduced microphotographic copy of a text. Methods for ensuring minimum loss of typographical quality and for combining information from reduced copy of separate parts of the inscription by a superimposition procedure are described.