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The Photo Etching Process




Photo Etching Process Steps


The photo etching process consists of 8 steps.


The “front end” process consists of material selection, material cleaning, application of photo-resist or “lamination”, image printing and transfer and image developing.


The “back end” process consists of etching, stripping and visual and dimensional inspection.


Finishing, forming and plating are also available as an in-house added value service.


Each stage of the process is interdependent of the next, so the preparation of the material at the front end of the process is crucial to achieving a high quality and accurate etched component.


Material Selection


A wide range of metals can be photo etched, and as such Precision Micro holds some 1,500 metal types in stock. Typically, sheet sizes range from A3 up to a maximum of 600mm x 1500mm.


Material Cleaning


The material is cleaned and degreased to ensure a clean surface prior to lamination.


Lamination


A photo-sensitive resist is laminated onto the top and bottom of the sheet. Good adhesion of this resist is again crucial to ensure etchant does not compromise the metal sheet it is protecting. A common issue that can occur is pitting of the surface should the resist lift away from the sheet during etching.


By recently investing in automated cut sheet lamination of our photo-resist, Precision Micro can ensure consistent and sound adhesion of resist for every metal sheet.


Image Printing


Using Laser Direct Imaging (LDI) technology, UV light selectively hardens the photo-resist upon exposure. The conventional method of imaging is by using “photo-tools” as a mask. A move by Precision Micro to digitise this process means greater accuracy and smaller component features can be imaged than ever before.


Developing


The unexposed resist is removed or developed away to reveal the raw metal. The exposed resist remains and will protect the metal underneath during etching.


Etching


The experience of the “etcher” is crucial in achieving highly precise components to micron accuracy. It takes a minimum of 5 years for our “etchers” to build up sufficient skill to work with the wide range of metals, grades and thicknesses we handle each day.


Specially selected etch chemistry at the appropriate concentration is sprayed onto the developed metal sheets for a pre-determined period of time. The time the sheets need in the etchant is subject to a number of variables, including sheet size, thickness, type and grade.


Metal is removed atom-by-atom until the resultant profiles and component features are etched from the sheet.


Stripping


The etched sheets move to the stripping department where the remaining photo-resist, which had up to now been selectively protecting the sheets, is removed.


Visual and Dimensional Inspection


The finished components move to visual and/or dimensional inspection. 100% automatic optical inspection is also available, where every individual component can be inspected to identify both cosmetic and dimensional defects.


Precision Micro 100% inspects millions of components each year for one specific high volume automotive application, which provides some insight into the scale of our operation.


Finishing


We offer a wide range of added value services including forming, plating and Wire EDM.


Should you wish to find out more about the available finishing options, or indeed the specifics of the photo etching process, please talk to one of our engineers by following the link below.


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