Chemical etching: A step by step guide

Below is a quick breakdown of Precision Micro’s chemical etching process, step by step.

Step 1. Material Selection

Virtually any metal can be chemically etched. Precision Micro holds more than 2,000 metals in stock in thicknesses from 0.010 mm – 1.5 mm, and sheet sizes to 600 mm x 1500 mm.

The company routinely processes stainless steel, copper and its alloys, nickel and its alloys, and with demand from industry often focusing on metals that have attractive strength to weight attributes, has developed proprietary processes for aluminium and titanium.

Step 2. Material Cleaning

Once a metal has been selected, it is chemically cleaned and degreased to remove debris, waxes and rolling oils, all of which could negatively affect the lamination of photoresist.

Step 3. Lamination

Light-sensitive photoresist is applied to the sheet in class 10,000 clean conditions. Good adhesion is essential for highly repeatable, blemish-free components. Any issue with the bonding of the laminate could allow the etchant to come into contact with the protected areas of the metal during etching, compromising the finished parts.

Step 4. Image printing

Precision Micro uses laser direct imaging (LDI) to transfer the CAD image of the component to the laminated sheet. LDI works by exposing both sides of the sheet to ultraviolet (UV) light which selectively cures the photoresist with an image of the component.

Step 5. Developing

The unexposed photoresist is removed during the developing stage to reveal the raw material. The hardened resist will protect the part during etching.

Step 6. Etching

Etchant chemistry (typically ferric chloride as standard) is sprayed onto the developed sheet. The etch-time is determined by skilled technicians taking account of variables such as metal type, grade, thickness, and size which all affect the end result.

Step 7. Stripping

The remaining photoresist is removed from the sheet revealing the etched components.

Step 8. Visual and dimensional inspection

The final components are visually and dimensionally inspected using state-of-the-art optical inspection equipment. This guarantees quality and repeatability levels approaching Six Sigma standards.

Step 9. Finishing

Precision Micro offers manual and semi-automatic precision forming, electropolishing and passivation post-etching corrosion protection, heat treatment for components that require increased surface hardness, surface finishing providing either non-reflective, dull, satin, mirrored or grit finish to enhance aesthetics or improve functionality, and brazing and diffusion bonding for heat exchanger, cooling, and fuel cell applications.