A phototool (i.e., stencil) is printed with the desired design or part shape. Two matching copies of the tooling are often printed so they can be applied to both sides of the metal raw material for etching from both sides at once.
Since 1965, the Conard Corporation has been providing precision photochemical etching for OEMs and other companies in the aerospace and avionics, defense, electronics, medical, scientific, and other industries. We use a proprietary aluminum etching process to create precision components, and also provide engineering support and rapid prototyping services.
Learn more about how photochemical etching works, some of its benefits in manufacturing, common alloys and technical considerations, and application examples.
What Is Photochemical Etching?
Photochemical etching, also known as photochemical machining, is a precision manufacturing technique that uses chemicals and light to selectively remove material from a metal substrate and create patterns, cutouts, or individual components. It is often used with very thin-gauge metal and is capable of making complex and intricate shapes and part features without burrs and mechanical or thermal distortion.
There are multiple steps in the process:
01
02
The metal raw material is cleaned to remove grease, oil, dirt, and other contaminants.
03
Both sides of the metal are coated with a light-sensitive photoresist layer.
04
The coated metal is secured between the two phototool layers and exposed to UV radiation for a predetermined time.
05
Developer solution is applied to the metal, and the un-hardened portions of the resist are dissolved.
06
An etching solution, such as ferric chloride, is applied to dissolve the metal only in the areas where the resist was removed.
07
The metal is stripped with an alkaline solution to remove the remaining resist from the part.
Benefits of
Photochemical Etching
Photochemical etching is an excellent choice for high-precision metal parts and components made of thin or delicate metals. It is a relatively non-contact technique, which protects the material from impact, hard tooling, excessive handling, or heat generated from machining. This process also prevents damage to intricate part features during manufacturing. The resulting near-net-shape parts have smooth edges and usually need little additional finishing.
There are several advantages to this method:
High precision.
Highly repeatable.
Cost-effective set up and production.
Suitable for many types of designs and features.
Efficient production of tooling and parts.
Quick turnaround.
Burr-free parts with no distortion.
No change to metallurgical properties of raw materials.
Suitable for rapid prototyping and tight tolerances.
Does not put physical stress on materials.
Metal Alloy Options
Photochemical etching is compatible with many metals and alloys in sheet or foil form, in different thicknesses and sheet sizes. Common options include, but are not limited to:
| Aluminum | Brass | Stainless Steel | Copper, Oxygen Free |
|---|---|---|---|
| Copper, Rolled | Copper, Electrolytic | Beryllium Copper | OFHC Copper |
| Inconel® 600, X750 and 800H | Monel® | Nickel | Nickel Silver |
| Nichrome® | Ni Span C | Permanickel® | Phosphor Bronze |
| Carbon Steel | Electrical Steel | Stainless Steel, 300 & 400 Series | PH15-7 Stainless Steel |
| PH17-7 Stainless Steel | Custom 455® | Spring Steel | 90-10 Copper Nickel |
| Kovar® | Rodar® | Nicoseal® | Therlo® |
| Sealmet 29-17® | Glass Sealing 42® | 142 Alloy® | Glass Sealing 46® |
| 146 Alloy® | Glass Sealing 49® | Alloy 4750® | Glass Sealing 52® |
| 152 Alloy® | Glass Sealing 42-6® | Sylvania No. 4® | 44-50 Nickel Iron |
| High Permeability 49® | Hipernik® | High Permeability 45® | Hymu 80® |
| 4-79 Permalloy® | Hymu800® | Hipernon® | Supermalloy® |
| 5-79 Permalloy | Invar 36® | TC-30® | Molybdenum |
| Conetic AA® | Metal on Polyamide | Metal on Kapton® | Metal on Rubber |
| Metal on Ceramic | Titanium |
Brazing Alloys for Photo Etched Preforms
Photo etching brazing alloy preforms saves time, cost and reduces scrap. Photo etching avoids many problems associated with stamping, die-cutting, laser, or digital knife plotter-cutting of these expensive alloys.
Find the Right Alloy for Your Application
Popular Brazing Alloys that can be Photo Etched
- Aluminum: AMS 4047, 4184, 4185
- Nickel: AMS 4776, 4777, 4778, 4779, 4782
- AWS: BNi5A, BNi5b, BNi6, BNi9
- Copper: AWS BCu-1, BCu-1a, BCu-2, BCu-3, BCu-1b
- Silver: AMS 4767, BVAg-0
Specifications and Tolerances
Material thickness is a major factor in the shapes, part features, and tolerances that can be achieved with photochemical etching. As tolerances become tighter, it is necessary to use smaller sheets of material due to the level of monitoring, adjustment, and process control required to maintain even etching throughout and across the surface of the material. This close control is necessary to create high-precision features and shapes reliably. In general then, thicker and/or larger sheets are more challenging to use with tight tolerance applications because it is more difficult to control etching with the larger volume and surface area of material.
As a result, part success involves some design considerations, such as:
- Drawing block tolerances of +/-.005 in. are achievable on metals up to .032 in. thick.
- Minimum dimensional tolerances of +/-.001 in. are achievable on metals up to .005 in. thick.
- For metal over .005 in. thick, minimum dimensional tolerances will be +/- 15% of metal thickness.
- Minimum hole/slot dimensions must be at least 110% of metal thickness.
- Minimum radius must be not less than 70% of metal thickness.
- Partial etch depth tolerance is +/-.001 in.
- Location tolerances will be within +/-.001 in. of drawing nominal dimensions.
| Sheet Size | 12″ x 12″ | 12″ x 18″ | 12″ x 24″ | 18″ x 24″ |
|---|---|---|---|---|
| Min Tolerance | +/-.002″ | +/-.0025″ | +/-.003″ | +/-.004″ |
| Quantity | ||||
| 500 | $.59 | $.43 | $.41 | $.38 |
| 1000 | $.56 | $.39 | $.36 | $.31 |
| 2500 | $.52 | $.38 | $.29 | $.25 |
| 5000 | $.45 | $.33 | $.29 | $.23 |
| 10000 | $.42 | $.31 | $.27 | $.22 |
| 25000 | $.40 | $.30 | $.26 | $.21 |
| 50000 | $.39 | $.29 | $.26 | $.20 |
| Sheets/ 1k Parts | 15 | 9 | 7 | 5 |
Photo Etching Costs
The specified features, allowable tolerances, inspection requirements, order volume, as well as material type, thickness, and sheet size all affect costs.
While thicker materials are easier to work with and are generally more sturdy and resilient, they may require more monitoring and closer process control to create certain features or shapes. Thinner materials, in contrast, require more care to avoid kinks or bends.
Download our Comprehensive Guide
for detailed information regarding photo etching costs.
| Sheet Size | 12″ x 12″ | 12″ x 18″ | 12″ x 24″ | 18″ x 24″ |
|---|---|---|---|---|
| Min Tolerance | +/-.002″ | +/-.0025″ | +/-.003″ | +/-.004″ |
| Quantity | ||||
| 500 | $.59 | $.43 | $.41 | $.38 |
| 1000 | $.56 | $.39 | $.36 | $.31 |
| 2500 | $.52 | $.38 | $.29 | $.25 |
| 5000 | $.45 | $.33 | $.29 | $.23 |
| 10000 | $.42 | $.31 | $.27 | $.22 |
| 25000 | $.40 | $.30 | $.26 | $.21 |
| 50000 | $.39 | $.29 | $.26 | $.20 |
| Sheets/ 1k Parts | 15 | 9 | 7 | 5 |
Industries that Use Photochemical Etching
Conard Corporation offers cost-effective manufacturing for customers in many industries, including:
- Aerospace
- Automotive
- Electronics
- Industrial
- Instrumentation & Controls
- Medical / Scientific
- Metal Filtration
- Power Generation & Storage
- RF / Microwave
- Telecommunications
- Semiconductors
Examples of Etched Components and Products
Because photochemical etching is compatible with so many materials, it is widely used for precision parts and components including:
Aerospace
Avionics heatsinks, fuel control plates, screens, shims, jet engine braze foils, satellite battery components.
Medical Device
Clips, brackets, dial components, spacers, flat springs, brazing metal preform components.
Filtration
Grids, screens, meshes, filters, separators, microfilters, flow orifice plates, diffuser plates.
Semiconductors
Lead frames, heat spreaders, EMI/RFI shields, micro-springs, contacts, interconnects, test handling components.
Power Generation
Bipolar plates, flow field plates, current collectors, diffusion screens, combustor liners, shims, seals, heat exchanger plates.
Contact Conard Corporation To Get Started
Since 1965, Conard Corporation has provided precision photochemical etching services, specializing in aluminum etching as well as many other metals and performance alloys. All of our work is backed by metallurgical expertise, and our team provides engineering and design support from prototyping through production.