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1. How Does Photo Etching Work and What Are Some Applications for It?

   March 12, 2025 12:51 pm Leave a Comment

   
   Photo etching has evolved from a niche process to one that serves a wide variety of industries with precision metal fabrication needs.

   Photo etching, also known as chemical etching and photo chemical machining, has evolved from the printed circuit board industry in the 1950s to nearly every industry that has a need for precision metal fabrication. Despite its many uses the process is not well known to engineers and designers who develop OEM products. If you’re unfamiliar with the process, watch this 2-minute video:

   

   As you can see, etching is a unique process. But why should you choose it over other fabrication methods?

   How photo etching compares to the conventional processes
   Stamping and punching utilize hardened steel tools to shape metal parts. Plasma, laser and water jet cutting direct intense energy to shape parts. Wire EDMs use a wire electrode to burn away metal. Each of these processes rely on “brute force” – shearing, cutting or intense directed energy – which may lead to undesirable effects like heat-affected zones (for the high-temperature processes), mechanical distortions and burrs. For designs that require tight tolerances, these effects can be the difference between a working part and scrap.

   By contrast, photo etching uses no hard tooling, and the highest temperature the process reaches is about 135℉ – roughly the same as your dishwasher. It doesn’t affect the composition of the metal in any way, so it’s exempt from Nadcap checklist 7108/5.

   
   PCM had its start in the printed circuit industry, but has since evolved to take a critical place in a diverse collection of verticals.

   Wide Range of Metal Gauges, Alloys and Part Sizes

   • Metal thickness ranges from .001″ to .080″ depending on the type of metal.
   • Part sizes from .020″ diameter to 24″ x 60″.
   • Metals include steel alloys, copper, aluminum, molybdenum and much more.
   • Drawing block tolerances of +/-.005″ are achievable on metals up to .032″ thick.
   • Minimum dimensional tolerances of +/-.001″ are achievable on metals up to .005″ thick.
   • For metal over .005″ thick, minimum dimensional tolerances will be +/- 15% of metal thickness.
   • Location tolerances will be within +/-.001″ of drawing nominal.

   OEMs in many industries including microelectronics, medical and scientific instruments, RF & Microwave and aerospace rely on photo etchers for precision parts that are impractical or impossible for other fabrication methods. Mechanical parts include sensors, shields, retainers, flat springs, strain gauges, filters, screens, grids, shims, and gaskets. Electronics applications include contacts, reeds, leadframes, hermetic lids, antennas, and direct bond copper. New applications are emerging every day that photo etching can fulfill in a timely and cost-effective manner.

   Our Comprehesive Guide to Photo Etching answers many technical questions for engineers.

   The download is free! Get The Guide Now

   For more information on the etching process, or to see how OEMs can benefit from working with a photo etching provider, call us at 800-443-5218 or email us at sales@conardcorp.com and we can get started working on your designs!

2. Essential Things to Know about Photo Etching

   12:40 pm Leave a Comment

   Why Metal thickness Matters so much in Etching

   

   Metal thickness determines the minimum feature size that can be etched, and dimensional tolerances determine the sheet size. The thing to remember is that etching is very much like erosion. Think of the Grand Canyon: it’s 300 yards wide at the bottom and 10 miles wide at the top. And, the same kind of tapering walls a canyon has are also created in the etching process.

   Here are some key design rules to keep in mind:

   •  Minimum holes or slot dimension is 110% of metal thickness
   • Minimum ligature or land area is, generally, not less than metal thickness
   • Minimum dimensional tolerance is +/-15% of thickness, to a practical minimum of +/-.0015″ on metals .010″ and less.
   • Minimum radius dimensions are not less than 70% of metal thickness
   • Etching speed is .001″ -.002″ per minute, depending on the alloy, and thus determines the total etching time.

   Here’s a link to a 3-minute video that shows the process step-by-step

   For commercial photo etching facilities, the most widely used etching solution is ferric chloride. This chemistry has been optimized to be very efficient in etching a broad selection of metal alloys used in a host of industrial applications. Here’s a quick rundown of the mostly widely used materials.

   What Popular Metals Can Be Etched by Ferric Chloride?

   • Carbon, Spring, Stainless and Silicon Steels
   • Nickel, Nickel-Iron (Including Kovar, but not Havar), and Nickel-Copper
   • Copper, Brass, Bronze (phosphor and Muntz)
   • Aluminum (not anodized), Tin, Manganese, Zinc, Chromium, Indium
   • Some “Super Alloys”
     • Inconel 600 and X750
     • Hastelloy X, A214

   Here’s a more extensive list of metals that can be etched in ferric chloride

   What Metals Will Not Etch in Fe3Cl?

   • Gold, Platinum, Palladium, Silver*
   • Titanium, Tungsten, Tantalum
   • Niobium, Zirconium
   • Cobalt, Molybdenum*

   * Conard has an alternative etchant for silver and moly.

   How are Photo Etching Costs Determined?

   Photo etching costs are about the “real estate”: how many parts can fit on a sheet. The size of the sheet is, to a large degree, determined by the dimensional tolerances. Part designs that accommodate standard drawing block tolerances of +/-.005″  on three-place decimals for metals up to .032″ thick allow using the largest sheet size, often up to 18″ x 24″.

   The “sheet” is the primary unit of labor, regardless of its size. Every sheet is handled into and out of each of ten sequential operations. The goal is to maximize the number of parts processed at each step, thereby reducing the labor per part.

   The other significant cost variable is metal thickness. Thicker materials take longer to etch, which is the most expensive part of the process.

   This chart illustrates the relationship between tolerances and costs.

   How much do holes cost?

   The first hole is always included in the price of the part. Any additional holes, no matter how many are FREE. Always.

   

   Is photochemical machining a Nadcap special process?

   No. Etching does not alter the mechanical or chemical properties of metal, therefore it does not qualify as a special process. However, chemical milling can be used to alter metal characteristics and in some cases may be subject to Nadcap checklist 7108/5 criteria.

   What will my parts cost to be photo etched?

   Get a FREE quote today!

   

3. Handy Facts About Photochemical Etching

   12:34 pm Leave a Comment

   Metal Thickness Drives Everything

   Minimum feature sizes, dimensional tolerances and costs are directly affected by metal thickness.

   • Minimum holes or slot dimension is 110% of metal thickness
   • Minimum ligature or land area is, generally, not less than metal thickness
   • Minimum dimensional tolerance is +/-15% of thickness, to a practical minimum of +/-.0015″ on metals .010″ and less.
   • Minimum radius dimensions are not less than 70% of metal thickness
   • Etching speed is .001″ -.002″ per minute, depending on the alloy, and thus determines the total etching time.

   Here’s a link for additional information.

   What Popular Metals Can Be Etched by Ferric Chloride?

   • Carbon, Spring, Stainless and Silicon Steels
   • Nickel, Nickel-Iron (Including Kovar, but not Havar), and Nickel-Copper
   • Copper, Brass, Bronze (phosphor and Muntz)
   • Aluminum (not anodized), Tin, Manganese, Zinc, Chromium, Indium
   • Some “Super Alloys”
     • Inconel 600 and X750
     • Hastelloy X, A214

   You can find more detail here.

   What Metals Will Not Etch in Fe3Cl?

   • Gold, Platinum, Palladium, Silver*
   • Titanium, Tungsten, Tantalum
   • Niobium, Zirconium
   • Cobalt, Molybdenum*

   * Conard has an alternative etchant for silver and moly.

   How are Photo Etching Costs Determined?

   Photo etching costs are about the “real estate”: how many parts can fit on a sheet. The size of the sheet is, to a large degree, determined by the dimensional tolerances. Part designs that accommodate standard drawing block tolerances of +/-.005″  on three-place decimals for metals up to .032″ thick allow using the largest sheet size, often up to 18″ x 24″.

   The “sheet” is the primary unit of labor, regardless of its size. Every sheet is handled into and out of each of ten sequential operations. The goal is to maximize the number of parts processed at each step, thereby reducing the labor per part.

   The other significant cost variable is metal thickness. Thicker materials take longer to etch, which is the most expensive part of the process.

    This chart illustrates the relationship between tolerances and costs.

   How much do holes cost?

   The first hole is always included in the price of the part. Any additional holes, no matter how many are FREE. Always.

   

   Is photochemical machining a Nadcap special process?

   No. Etching does not alter the mechanical or chemical properties of metal, therefore it does not qualify as a special process. However, chemical milling can be used to alter metal characteristics and in some cases may be subject to Nadcap checklist 7108/5 criteria.

   What will my parts cost to be photo etched?

   

4. Half-etching and its applications

   11:07 am Leave a Comment

   
   Half-etched features have several uses in the creation of industrial parts.

   Photo etching is a versatile metal fabrication process, and “half etching” serves as a perfect example. As the term implies, when we create a half etch line or feature, we’re not etching all the way through the metal.

   How do we half-etch parts?
   Photo etching starts with the creation of a photo tool that is taken from a design saved in a Gerber file. We take the design and plot it on a dimensionally stable mylar film in the shape of the part. From there, we measure out the metal sheets, clean them and laminate them with photopolymer film in a safe-light clean room.

   The photo tool and laminated metal are positioned together in a vacuum-frame UV exposure unit, with the identical photo tools on both sides of the metal. The exposed sheets are developed to remove the unexposed photopolymer, which leaves only the bare metal to be etched. Finally, we use an etching solution on both sides of the metal, which dissolves the metal and leaves the part.

   Half-etching essentially works in the same way, but with one slight difference. A line or feature is strategically placed on one side of the photo tool, but is omitted from the other side. This means that during the etching process, the etchant only works on one side, ensuring that the feature is seen only on the desired half of the final part.

   
   Surface features, orientation marking and fold lines are all critical in the design process.

   What is half-etching used for?
   Some of the most common industrial uses are:

   • Heat-dissipating surface features
   • Flow channels for fuel cell plates and sensor membranes
   • Perforated diaphragms
   • Relief for additional tool access
   • Removal of excess metal for weight reduction
   • Part/orientation marking for identification purposes
   • Rupture seams for pressure membranes
   • Fold lines for hand-formed parts

   Fold lines are especially useful for industrial use. A part can be designed flat with fold lines and then hand folded into a three-dimensional shape, saving time and money. RF Shielding is just one popular application of this. Other 3D processes tend to have high-tooling costs and long lead times, so half-etching is a great alternative.

   Half-etching can also be used for what we call a double process. In this case, a design for an etched-through part may also require half-etch graphics on each side that are aligned top to bottom, but not etched completely through. For this, we design two photo tools, where the first tools is printed and processed as a half-etch. The part would then be reprocessed and aligned to a second tool. From there, the part is completed with the desired etch-through design with the added application of half-etch markings aligned from top to bottom.

   To learn more about the photo etching process and its capabilities, call us at 800-443-5218 or email us at sales@conardcorp.com.

   

   ADDITIONAL RESOURCES

   The Comprehensive Guide to Chemical Machining
   DOWNLOAD

   Introduction to Electroforming
   DOWNLOAD

   Design Considerations for Photo Etching
   DOWNLOAD

5. Getting a conceptual grasp of photo etching

   10:36 am Leave a Comment

   
   When it comes to understanding how photo etching works, there seems to be a conceptual gap – many of the engineers I’ve spoken with over the years just don’t have a clear mental picture of how photo etching works.

   One of our biggest business challenges is the overall lack of awareness of the capabilities that photo etching can offer to engineers and designers at the OEMs that contact us for solutions. These are people who can tell you everything there is to know about processes like laser cutting, wire EDM, CNC milling, water jet and all of the other conventional methods.

   Addressing this conceptual gap in the understanding OEMs have about photo etching is important because they should be fully aware of how photo etching can solve some of their most difficult design problems.

   “Some of the steps in the photo etching process share a few similarities with principles of photography.”

   Smile for the camera
   If you may have guessed from the name, some of the steps in the photo etching process share a few similarities with principles of photography.

   The process always starts by printing the shape of the part, supplied by a Gerber file, onto a clear and dimensionally stable photographic film called the “photo tool.” The phototool is made up of two sheets of film that show the negative images of the part. These negatives, or clear spaces will eventually become the parts.

   Once the photo tool is developed, we cut the metal sheets to size, thoroughly scrub and rinse them and then laminated both sides of the sheet with a UV-sensitive photoresist. The metal sheet is then placed between the two photo tools and drawn through a vacuum to ensure that they are perfectly flat and have even contact the whole way through.

   The sheet is then exposed in UV light, much like a photographic exposure, which makes the areas coated in photoresist harden. Once the sheet is exposed, we “develop” it, removing the unexposed photoresist and leaving only the bare metal to be etched.

   Finally, the developed sheet is put through the etching line, where it is sprayed from both sides with a corrosive aqueous solution – usually ferric chloride – which corrodes the bare metal away. The rest of the photoresist is stripped away with a caustic solution and water. Once they’re fully rinsed, we dry the parts and send them off to inspection.

   
   Developing phototools and UV-created exposure of the bare metal underneath are two ways in which the PCM process is similar to photography.

   So, what can you do with it?
   Even though the process itself is intuitive once you get a grasp of the basic concepts behind it, the parts you can make with it range from the simple to the very complex. Here is a very short list of some of the many industrial applications photo etchers can handle with ease:

   • Fine screens and meshes
   • Fuel cell components
   • MEMS components
   • Heat sinks
   • RF and Microwave circuits
   • Semiconductors and leadframes

   The complexity that these parts require lend themselves to the etching process. Photo etching, taking another page from the photo printing process, allows for the creation of part designs that can be intricate without having an impact on the tooling or production process.

   Additionally, photo etching produces no mechanical or thermal stresses in the finished parts, leaving the finished product free of heat-affected zones, inconsistent edges and burrs. And because we don’t alter the composition of the metal, photo etching is exempt from Nadcap checklist 7108/5.

   Through etching, we can produce complex precision parts that would be either impossible or impractical to produce by most other fabrication methods.

   Here are some of the design capabilities of photo etching:

   • Metal thickness ranges from .001″ to .080″ depending on the type of metal.
   • Part sizes from .020″ diameter to 24″ x 60″.
   • Metals include steel alloys, copper, aluminum, molybdenum and much more.
   • Drawing block tolerances of +/-.005″ are achievable on metals up to .032″ thick.
   • Minimum dimensional tolerances of +/-.001″ are achievable on metals up to .005″ thick.
   • For metal over .005″ thick, minimum dimensional tolerances will be +/- 15% of metal thickness.
   • Location tolerances will be within +/-.001″ of drawing nominal.

   For more information on the etching process: Visit the Tech Library

   To see how your OEM can benefit from working with a photo etching provider, call us at 800-443-5218 or email us at sales@conardcorp.com and we can get started working on your designs!

6. Ferric Chloride – Why is it so effective for photo etching?

   9:50 am Leave a Comment

   
   Ferric chloride is a major asset to photo etching because it has such a wide ranging array of benefits to providers in the field.

   While there are a number of possible etchants, none is more commonly used than ferric chloride because it has such a wide ranging array of benefits to providers in the field.

   Ferric chloride’s operational benefits
   This etchant has made a name for itself because it is inexpensive, safe to use, consistent in its etching capabilities and highly suitable for working with a variety of metals.

   In terms of handling, ferric chloride is one of the least harmful etchants we have available. Direct exposure to the skin can often be alleviated with just water. Other etchants, like acid, alkaline and hydrofluoric acid can cause considerable injuries, and in some rare cases, death if they are mishandled.

   While ferric chloride is notable for its versatility, it performs especially well in etching the white metals – Iron- and nickel-based alloys in addition to zinc, tin, indium and manganese. Some of the most common iron-based alloys are stainless, carbon and silicon steels. Examples of alloys whose major fraction is nickel are Alloy 42, Inconel, and Mu-metal. Photo etching these white metals, and others, with ferric chloride produces smooth, consistent edges and sidewalls while keeping a predictable and controlled etch rate.

   
   Ferric chloride’s ability to be recycled and regenerated makes it highly cost effective and efficient.

   Etchant recycling – where ferric chloride shines bright
   One of the greatest benefits that working with ferric chloride has for photo etching shops is its ability to be recycled and regenerated for different purposes. Sensors throughout the etching process constantly monitor the chemistry of the etchant. When it reaches a certain threshold, the solution is infused with injections of muriatic acid, chlorine and water. This allows one batch of ferric chloride to last for weeks at a time.

   Even better is that at certain points, the chemistry can be modified to make the ferric chloride suitable for etching red metals. Here too, the etchant is monitored and refreshed as needed, extending its life by several weeks.

   After that, it can be reconfigured again for etching aluminum. Aluminum can be tricky to photo etch because it is highly reactive and prone to oxidation. The reconfigured ferric chloride, however, has proven itself to be a great choice in aluminum etching.

   The ease with which this popular etchant can be recycled is a powerful cost-cutting tool. Using the same batch of ferric chloride for weeks, even months at a time means that we don’t have to constantly buy new etchant. In fact, research from Professor David M. Allen found that companies that regenerate and recycle their ferric chloride etchant are roughly seven times more efficient in their use of the chemical than companies that do not. By keeping our “machining” costs low, we can pass our savings onto our customers.

   For more information on the etching process, or to see how your OEM can benefit from working with a photo etching provider, call us at 800-443-5218 or email us at sales@conardcorp.com and we can get started working on your designs!

   Design Considerations
   for Photo Etching

7. Etching, Stamping, Water jet or Laser: Which to Choose?

   9:20 am Leave a Comment

   One of the questions we hear a lot is: How do I know whether stamping, laser, water jet or etching would be the best option for my project?

   We decided to find out. We made up a part-we call it the CC star- it’s a little stupid-looking  but it serves the purpose.

   

   We sent it out to several shops and asked them to quote making it in .020 stainless. The part is about 2.75 inches in diameter.

   This is what we learned:

   	Etching	Stamping	Laser	Water jet
   Tooling/Set up	< $500	~ $10,000	N/A	N/A
   Cycle Time	850 pieces/hour	2400 pieces/hour	80 pieces/hour	30 pieces/hour
   1000	$2..33	$4.43	$2.33	$4.03
   5000	$2.26	$2.24	N/A	N/A
   10000	$2.08	$2.07	N/A	N/A

   Not unexpectedly,  stamping is a lot faster, potentially 2400 parts per hour for something like this. So, basically a half a day to produce 10K pieces. Laser and water jet definitely suffer by comparison, but is the (utterly unnecessary) complexity of “CC Star” that drives the issue. A simple washer might be a more fair competition.

   Etching would be about 800 parts per hour regardless of the part complexity- a washer would have the same cycle time. So, a little less than 2 days for 10K parts. And, if you ordered 5000 or more parts, we wouldn’t charge you for the tool.

   Here’s the thing: the etching process is completely agnostic regarding part complexity. Complexity does not affect either the tooling cost or the cycle time at all. We make filters for French press coffee makers. Zillions of holes. All of them free.

   ‘I’m  not sure whether it is possible even to make a stamping die for a coffee filter like that. And, if it is possible, the cost would likely be astounding, with little-if any-impact on cycle time or part cost. (The burrs would be a problem, though.)

   Other considerations:

   • Stamping will raise burrs and may cold-work the metal.
   • Laser will leave heat affected zones in the cut areas that may need to be cleaned up.
   • Water jet will leave somewhat ragged edges as the pressurized cutting slurry contains abrasive material.
   • The part complexity reduces cycle times for laser and water jet, precluding high volume.
   • The cost of the stamping die is a relatively high barrier.

   So, the math works out that you’d have to stamp a million of these widgets to amortize the cost the of the stamping die compared to etching them.

   Each of these processes has a sweet spot:

   • Water jet is the brute force solution for heavy gauges of metal and non-metallic materials.
   • There are a multitude of laser solutions that are optimized for cutting both metal and non-metallic materials. Lasers are particularly good at cutting long runs very fast; they have largely replaced punch presses for most sheet metal fabricating tasks,
   • Stamping is the high volume winner, as long as you can cover the tooling cost.
   • Etching is a very versatile metal cutting process and is suitable for a wide range of alloys. Part sizes can range from .020″ diameter to 24″ x 58″ panels in thicknesses from .001″ to .040″ for steel, .065″ for copper and up to .080″ in aluminum.

   Feel free to contact us with any questions, or if you are ready to price your project:

   Request Quote

8. Thermal Management Challenges Solved by Etching

   9:08 am Leave a Comment

   When the heat is on, many look to photo etching to move it around or make something useful of it–like electricity.

   Heat sinks are devices that help remove heat from vulnerable electronic components, relying on air conduction to radiate heat away. Etching offers the ability to create pin- or vane-like structures that increase the effective radiating surface area without increasing the actual footprint of a device.

   • Etched aluminum circuit board heat sink

   

   • Etched aluminum “pin fin” radiator plate

   

   “Cold plates,” which are designed to attract heat away from electronic devices, get an assist from a transfer medium such as anti-freeze to absorb excess heat and shuttle it away to be chilled and recycled. In a cold plate the tubing is created by etched channels in copper or aluminum plates that are bonded together channel-to-channel to create tubes, of a sort, through which coolant is pumped.

   Power generation and storage are also beneficiaries of the capabilities of photo etching. Fuel cells, batteries and evolving distributed generation technologies require part geometries that are uniquely realized by chemical etching.

   Proton exchange membrane (PEM) fuel cells take advantage of photo etching’s agnosticism with regard to part complexity vs. cost to produce very intricate membrane elements for both generating electricity and electrolyzing water to produce hydrogen.

   Nickel-metal hydride and lithium ion power cells are the batteries of choice for space-based applications. Many medical devices-including implantable devices- rely on battery technologies that also utilize etched components,

   • Etched nickel cell grid for NiMH batteries

   

   Thermal cycles are also useful in power generation. The “waste heat” of combustion is captured and converted to “work” (in the parlance of thermodynamics) as an additional stage of generation, often through steam turbines.

   However, a number of evolving strategies are taking advantage of the ability of photo etching to create complex partial-depth etched structures and patterns that are central features of new distributed power generation technologies that take advantage of thermal cycles without the rotating machinery.

   There are growing applications in power electronic components that are built on direct bond copper circuit materials. These are constructions of aluminum oxide (alumina) or aluminum nitride ceramic that have copper foil diffusion bonded on both sides. The ceramic dissipates the heat generated by the device, enabling both higher power applications and longer service life.

   Etched direct bond copper on ceramic power electronics base

   

   Sometimes it’s not about removing heat. Etching is also use to produce flexible resistive heating elements. Typically an electrically conductive material such as Inconel, stainless steel, nickel or copper is bonded to a non-conductive substrate such as silicon rubber, fiberglass or a polymeric material such as polyimide or polyester. The element pattern is etched into the metal down to the substrate, and the resulting circuit is usually affixed with electrical leads and encapsulated with another layer of non-conductive material. These types of devices find many applications in aircraft, both as de-icing boots for leading edges of the airframe or propellers, as well as preventing freezing in other systems on board.

   Etched Inconel on silicon rubber flexible heater element

   

   So, if you have a “hot” situation, you can keep your cool with photo etching. Contact us for more information.

   For more detailed information on photo chemical machining, download our free comprehensive guide:

   

9. Do You Know Manufacturing’s Best Kept Secret?

   8:52 am Leave a Comment

   You may be aces on the intricacies of stamping, laser, plasma, waterjet and EDM. But what do you know about the other metal fabrication process that is solving problems for engineers in many industries every day? “Which one?” you ask?

   Photochemical machining….or etching ,if you prefer. Yes, we do it with acid.

   Not many people have an instant mental picture of the etching process. Yet, many readily “get” stamping, laser, water, and plasma cutters for creating metal parts.

   Here’s a 3 minute video that will provide a mental framework for you. I’ll wait.

   So, let’s review:

   • Six steps: clean, coat, image, develop, etch, strip.
   • Images are exposed on the metal through the phototool, essentially a stencil.
   • Developed photoresist protects the metal that becomes the parts.
   • Parts are produced in sheets containing as many copies as will fit.
   • The metal is not subject to any mechanical or thermal distortions.

   When to Use Photo Etching?

   • Metal thickness from .0005” to .040” (white metal); .065” (red metal) or .080” (aluminum).
   • Many popular alloys of steel, nickel and copper, as well as aluminum, molybdenum and silver.
     • Here’s a more extensive (but not exhaustive) list.
   • Quantities from dozens to tens of thousands…and sometimes more.
   • Dimensional tolerances within +/-15% of metal thickness.
   • Almost anytime, really.

   Using photo etching, the test part shown below (2.7” diameter on .020” stainless) is no more difficult or costly to make than a simple washer and the phototool is less than $300 and available in one day.

   

   We did a cost study on this part, comparing etching, stamping, laser and water jet. The results are free and you can get the report here. We were surprised, too.

   What are the Design Limitations for Chemical Etching?

   • Holes, or the minor dimensions of slots, must be at least 110% of metal thickness
   • The metal between holes or slots should be at least equal to metal thickness (there are times we can shade this a little.)
   • Minimum dimensional tolerances are +/- 15% of metal thickness.
   • Minimum radius is 70% of metal thickness.

   Easy. You can get the free Comprehensive Guide here.

   Oh, and, we only charge you for the first hole. The rest of them, no matter how many, are FREE. (Completely FREE.)

   Photo etching can produce part geometries that would be extremely difficult, if even possible, with stamping or punching. Laser and plasma cutting are more flexible in this regard, however every feature and every hole must be addressed in a linear way, as if tracing with a pencil.

   Simplifying complexity is perhaps one of photo etching’s greatest advantages. The process is utterly indifferent to odd shapes, multitudes of holes or other less ordinary features.

   Photo chemical machining has been call “manufacturing’s best kept secret.”  Now, you’re in on it, too.

10. DFM: What Matters in Photo Etching

    8:49 am Leave a Comment

    Once Upon a Time….

    Designers and engineers would talk to the tool-and-die guys and the machinists about whether something they wanted to make could be manufactured in a reasonable way. Since the advent and evolution of 3D design environments, it seems that little of that practical knowledge was embedded in the coding rules. Thus, the modern-day mouse jockeys have the power to design almost anything, with little to no regard for the pesky realities of actually making stuff.

    So here’s a true story…

    Going on now three years ago, I got a call from an engineer who was looking to make some copper shims. The shims were pretty small, roughly .125  x .50 inches–which is no problem for photo etching. But then, he wanted them in 10 different thicknesses from .001 to .015″. Again, no problem for photo etching, as far as the range of thickness goes; but 5 of the 10 gauges are not standard.

    So, I tried counsel him to stick with what was available, otherwise it can get expensive rather quickly. But, no, he had to have all 10 gauges. I asked why. It had something to do with some unpredictable range of variability at assembly. And I questioned that, because typically shim sets don’t hit every gauge (1-, 3-, 5-, and 10-mil sets are pretty common). But, he insisted.

    Happily for him, we were able pre-etch to gauge the non-standard thicknesses at a far more reasonable cost than having custom rolled material made to order. And, he got his shims, at a very reasonable price of about .25 each.

    So much for keeping it simple…

    Nearly a year later, they were back for more. Now there’s a whole team of people, and boy, do they have some ideas!  They have narrowed the range of shims that they need to six thicknesses (Yay!), and two of them are standard (Yay!). And, by the way, they absolutely fell in love with the idea that we can pre-etch to whatever magical thickness they want. Except, they didn’t ask us what we could actually do.

    Their new drawing was asking for thicknesses like .0118+/-.0001, and .0142+/-.0001, and so forth. Realistically, +/-.0005″ on re-gauging is most likely. In etching copper, .0001″ inches is about 30 seconds. We managed to talk them off that ledge, and they agreed to +/-.001.

    But, climb back up, they did…

    They added a new packaging spec that required little plastic pocket trays and a specific number of shims in each pocket. Say bye-bye, bag and tag. Each shim, hand-loaded. $$

    Then they asked to have these parts gold plated AND maintain total thickness tolerance of  +/-.0015″. Okay, the math does -just barely- work on this in terms of the plater’s tolerances, but the parts are barrel plated and inspected to an AQL of 2.5. The yield suffered. $$$$

    At this point, we’re two years in. And, we think–finally–real production can start.

    It turns out, they weren’t done…

    The application for this little shim, that now costs–with gold plating (barrel plating) and packaging–about $1.25 each, can’t tolerate a shim that is more than .0003″ out of flat.

    Alrighty. Inspect every shim for flatness. The first obvious choice was a drop gauge. A simple, fast go/no-go answer. Except the variability in plating was just enough to kick out parts that were actually within spec.

    Guess where we are right this minute. Every shim has to be mic’ed for thickness and then measured on a CMM for flatness. We don’t know yet what the yield will be, but let’s say it’s only 50%. Those shims could cost $5 each. Crazy!

    In a sane world (and despite my nattering about DFM)…

    This shouldn’t have happened. If the receiving application wasn’t robust enough to function with a “garden-variety” shim (packaging and plating not withstanding), some one should have said “Whoa, Nelly. Let’s fix the problem here.” Instead they put a team of engineers on it, for nearly a year, to fix the shim!

    CBYD should apply here, too…

    Call Before You Design. We’re happy to answer questions and more than happy to help you avoid the $5 shim “solution.”