What Is Photo Etching?


Photo etching is the process of using ultra-violet light to fix an image onto a sheet of metal, and then using chemicals (etching solution) to etch the shape into the metal, removing more and more of the material until only the shape is left – a metal component that is far more precise than anything that can be cut or machined.
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Why Is Photo Etching Different?

Photo etching is a very precise method of metal cutting and etching that uses specially formulated acids such as Ferric Chloride (FeCI3) to produce designs on flat sheets of metal with thicknesses up to 2.5mm. Due to the nature of this process, it is possible to etch designs with an unrivalled level of complexity, incorporating special features, in most metals, with thicknesses ranging from 5 μm to 2.5mm.

The Photo Etching Process Made Easy


The ACE Etching Process

Our process starts with digital tooling, where we receive data from the customer in the form of a DXF/DWG file or dimensioned drawing. This method allows customers the flexibility to include several variations of a design on one sheet of metal. Once a sample has been approved and the best design chosen, ACE uses the same data to produce a photo tool for higher volumes. The photo tooling can be modified in a matter of minutes, and samples produced in hours, not days or weeks.

Once the design is printed onto the chosen grade of metal sheet and chemically developed, the sheet is passed through the etching machine on a conveyor, where the acid solution is sprayed and attacks the unprotected surfaces of the metal, until the chemical etching process is completed, and the resulting components can be rinsed and inspected.

 

A Quick Overview of the Etching Process

Chemical Etching / Photo Etching is normally performed in a series of eight steps:


  1. Choosing The Metal


  2. Metal Cleaning


  3. Lamination


  4. Printing


  5. Developing


  6. Etching


  7. Stripping


  8. Inspecting & Finishing

Is There A Difference Between Photo Etching and Chemical Etching?

Photo etching is simply the name given to the process of using light and photo-tools to fix the image of the component to be etched. Photo etching can be used interchangeably with terms including chemical etching and chemical milling, although those terms may refer only to the chemical process of etching.

The Photo Etching Process In 8 Steps


Step 1


Choosing The Metal

Sheet metal or coil is selected from a comprehensive metal store (over 2000 different types of metal on the database from 0.07mm to 1.5mm thickness) and is cut to the required size. We only use high photo etching quality metal for all of our chemical etching processes. Material is allocated with a unique batch number traceable to incoming material certificates. Cosmetic inspection is carried out to ensure material quality is good.

Step 2


Metal Cleaning

The metal to be used is chemically cleaned to remove any rolling oils or contaminants from the surface, this is important as contamination will inhibit the application of the photo-resist and could negatively impact the quality of the finished etched part.

Step 3


Lamination

The cut sheets are laminate coated with UV light sensitive photo resist (laminar) which is applied to both sides of the sheets using heat and pressure. The excess laminar is trimmed from the sheets.

Step 4


Printing

The Dry Film laminated sheet has the photo tool image applied to it by exposing the image onto the metal using a UV (Ultra Violet) light source. The component image is transferred to the metal sheet.

Step 5


Developing

The exposed sheets are passed through a developer and chemically developed, chemistry washes away un-exposed soft areas and leaving the component shape protected.

Step 6


Photo Etching

Sheets are placed on the etch machine conveyor, the etch speed is calculated based on the metal thickness and etch rate which is based on metal chemical composition. A pilot sheet is etched and measured, once the target size is correct the speed is set for the rest of the sheets and samples are periodically measured to ensure machine settings are constant.

Step 7


Stripping

Rinse and strip the photographically resistant dry film from the metal sheet, the etched sheet is now ready for the final inspection. Components can now have secondary operations applied such as forming, plating, heat treatment, etc..

Step 8


Inspecting & Finishing

QA inspection on critical dimensions as agreed with the customer are undertaken using a CMM (Coordinate Measuring Machine). Finished etched components are visually inspected and final inspection of the parts is carried out to ensure they are cosmetically perfect for the customer. Inspection is carried out to different inspection procedures to suit particular customer requirements.

Why Choose Photo Etching?

Traditionally, processes employed in metal profiling to produce metal parts and components have included stamping, punching, laser and water jet cutting. These methods impart inevitable stress on the material, and can result in distortion, burrs and surface imperfections, leading to a loss of integrity and quality in the finished component. Hard tooling methods can involve long lead times, especially when alterations are required, and costs that scale quickly as design complexity increases.

ACE’s process allows for the highest possible level of flexibility and complexity at the best price– and produces a product of the same consistency and quality from the first etching to the last, without the characteristic drawbacks of other cutting methods.

 


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Benefits Of The Photo Etching Process

  • Go-To Process

    Low set-up costs and fast lead times make photo etching a go-to process in batch sizes of one to multiple millions  

  • Low-Cost Tooling

    The tooling for photo etching is digital, low-cost and can be modified quickly

  • Right First Time

    No heat or force is used when photo etching, so the mechanical properties of the metal remain unaltered and parts are free from stresses and burrs

  • Any complexity

    Component features are etched at the same time so part/feature complexity is not an issue

METALS PHOTO ETCHED BY ACE

photo-etching-3
               
And many more metals & alloys...
             

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