Typically you would just dip the board in a pool of the etchant, but this is not so good as it will reduce the effectiveness of the etchant as it fills with cupric chloride remnant from etching. Cheap fast and easy to regenerate, either chemically or by electrolytic recovery. Its something every electronics tinkerer ends up trying sooner o later. According to adam seychells etching with air regenerated acid cupric chloride, more copperii ions enhance etching speed.
It has been reported that a micro etching solution containing cupric chloride or ferric chloride, peroxysulfuric acid and quaternary ammonium cationic surfactant provided a smooth. Caig labs cl etch 16 ferric chloride pcb etchant solution 16oz bottle. When we hear about etching pcbs at home we assume that either ferric chloride or cupric chloride were used to eat away unmasked copper from. Feb 20, 2017 here is a bit of footage of an attempt at pcb etching with cupric chloride. Here is a bit of footage of an attempt at pcb etching with cupric chloride. Ferric chloride etching for pcbs pcb manufacture uk. A tiny flaw in a prototype is very expensive to find in terms of time. Cuppric chloride cucl2 cuppric chloride, cucl2h2o2, is another pcb etchant that is actually made by etching copper in a mixture of hcl and h2o2. The acidic method is used to etch off the inner layers in a pcb. Feric chloride, as it bites away at the copper, leaves a residue of iron, which stops or slows the process. Instead, she combines vinegar, hydrogen peroxide, and. How to etch copper with ferric chloride by lilytree.
Pcb etching is another big topic in the electronics diy world. This method involves adding lime calcium hydroxide directly to the cupric chloride etching solution. Using an iron, the resist traces, pads, vias, and patterns are copied onto a singlesided clean copper board. Build a complete pcb etching station and produce boards in. However, once youve etched a board with it, youre left with a solution with a bunch of cop. Any etching procedure you read about can be described in 5 different steps. Printed circuit board etchant pcb dry powder 8 oz in a spacesaver bottle usa. Etchant concentration, additives and etching temperature were examined as an input parameter. The typical cupric etchant contains about 180 grams per liter of copper as cupric chloride, which is equivalent to about 3 molar, or in this case 3 normal also. Almost half the etch systems sold by chemcut in the last five years have been cupric chloride systems. Alkaline etching ammoniacal the acidic method is used to etch off the inner layers in a pcb. However, the cuprous chloride solution can then be converted back into cupric chloride by introducing oxygen and a little more hydrochloric acid as required, thus making the solution rechargeable, but only for etching copper, not steel. Of the several types of etchant chemistries the hobbyist can choose, acid cupric chloride also called acid copperii chloride or just cupric chloride is one of the more interesting types, since it has the ability to be regenerated, or replenished, without having to throw away the solution.
It is further important to realize that speed of etching and etch undercut go hand in hand, the faster the etch rate, the greater the undercut. A new additive to help this etchant be more effective. The pcm industry typically etches foils that are 510 mils thick, and occasionally much thicker than that, consequently etch factor is even more critical than in the pcb industry. Copper etching with cupric chloride and regeneration of waste. Better yet, our new etchant will turn an eerie green color rather than the dull.
It is important that this be gotten rid of as soon as possible, to maintain etch speed. Etching of copper from standard singlesided copper boards used usually for. The normal ferric chloride solution works well, but can be expensive and leaves permanent stains. Various acids such as acid cupric chloride and hydrochloric acid may also be used as etchants. Today cupric chloride is used to etch a majority of the inner layers produced in the world. Copper can exist in three oxidation states, the elemental form, the blue colored cupric form, and the less common cuprous form. Copper etching with cupric chloride and regeneration of. Ready to use solution designed for etching printed circuit boards and other metals. When we hear about etching pcbs at home we assume that either ferric chloride or cupric chloride were used to eat away unmasked copper from the boards. Printed circuit board fabrication chemistry of the. The chemistry of the cupric chloride etching process copper can exist in three oxidation states, the elemental form, the blue colored cupric form, and the less common cuprous form.
The etching process can be carried out in a number of ways. I know it wouldnt look as good as using software and inkjet printer but for some simple circuits it would seem to make things a little faster by just hand drawing your. Here, i need to assume few things before you start comparing the information with your pcb. While you wouldnt want to drink it, i wouldnt call it highly toxic. On the other side of the coin, the dry etching method is a far more complex operation requiring a dedicated machine for its operation. Acidic etching ferric chloride and cupric chloride. The great thing about cucl2 is that you can regenerate the solution by adding a little oxygen fish tank pump, shake bottle, or add a. During its first phase, it gives off chlorine gas in quantities that coulld be dangerous in small spaces ventilate well. When you submerge your pcb in the etchant, depending on the result you want, you should either plunge it in the ferric chloride or dip it slowly. By adam seychell last modified 5 november 2005 this page describes some practical information on how to use air regenerated acid cupric chloride to etch printed circuit boards at home.
This process still requires etching in either ferric chloride or some other mess of acid, but the results are good. The etch resist is a material you put on the pcb where you want the copper to stay intact. However, ferric chloride is very toxic and environmentally unsafe, which is why it was not chosen for this application note. In the toner transfer method, the toner of the laser printer acts as the resist.
Chemistry of the cupric chloride and ammoniacal etchants. Most pcb companies use the pattern plate strip etch tin strip process so ammoniacal etchant must be used due to the fact that cupric chloride will remove the tin or tin nickel pattern plate applied as a resist along with all of the copper. Not suitable for pth work as it readily attacks tin lead. According to adam seychells etching with air regenerated acid cupric chloride, more copper ii ions enhance etching speed. Cupric chloride etching for pcbs pcb manufacture uk. So good, in fact, that marco is experimenting with copper foil and kapton to create flexible circuit boards. However, last two decades, new etchants have been introduced for copper etching. How to create a pcb etchant that automatically improves after. Ferric chloride is a traditional homeuse circuit board etchant. Thirdly, slowly dip your pcb into the etching solution for close to three minutes.
This process, when combined with a peroxide cupric chloride etching process forms an environmentally responsible, green pcb development process. Even thou its a fairly simple procedure it requires some self confidence or bravery since it involves strong, smelly and hazardous chemicals. Jul 11, 2009 i have done a search and have been looking on the web to find out if it is possible to make traces on a pcb board with a sharpie. Process guidelines for cupric chloride etching is presented in this paper along with the advantages and disadvantages of using cupric chloride as an etchant, the chemical reactions and processing parameters of cupric chloride, equipment parameters, and system design considerations. I have done etching, have owned a pcb milling machine. Luckily, we can whip up our own etchant at home with everyday chemicals. Cakir 3, 4, copper etching with cupric chloride and regeneration of waste etchant was studied.
One of the most important steps in the world of printed circuit board manufacturing pcb is the copper etching process. Pcb etching experiment with cupric chloride youtube. Fabrication cupric chloridehcl acid microetch roughening process. However, ammonium can be very expensive, and hard to control. Mg chemicals ferric chloride copper etchant solution, 4l liquid bottle. As it etches away uncured photomask and copper from the pcb, it will become less effective and etching time will increase. The best etch rate occurs between copper concentrations of 125 gpl cu and 175 gpl cu. Nowadays, it has been major etchant in copper etching industry 4. An old favorite, also very good at staining fingers, clothing, etc brown. The operative reactions in a ferric chloridebased etchant are as follows. After reading this howto and watching the step by step video, you will be able to make your own. Historically, the first etchant in pcb fabrication was ferric chloride fecl 3 and it is still used as an etchant for small scale production lines. This page is an attempt to document the process in a concise way. There are many webpages explaining how to create printed circuit boards pcbs without having to use uv light and photoresist.
This bulletin will cover the advantages and disadvantages of using cupric chloride as an etchant, the chemical reactions and processing parameters of cupric. Pcb fine lines and spaces hitech hdi circuit board. Various etchants can be used for this purpose, but nowadays cupric chloride is more accepted etchant, because of its high etch rate and easy regeneration properties. Check out the edinburgh etch which iscitric acid added to ferric chloride. Make sure the ferric chloride you are using is reasonably fresh. Exposed copper is etched with ferric chloride etchant, heat, aeration, and agitation. Whether it is a simple prototype or a fullblown manufacturing batch, your boards connection paths will need to be precisely defined and laid out so that your components will be able to successfully communicate with one another. My sharpie traces were not thick enough, so much of the traces were burned away by the acid. Making a printed circuit board using pcb cad software and laser printing the artwork to pressnpeel toner transfer film.
The toner is a kind of a polymer mixed with carbon that sticks to the paper when heated. At 70c using spray etching 1oz copper is removed in a little under a minute, normal etching temperature is more likely to be 45c. In the case of the cupric etch, the etch speed is a sensitive function of the free acid. I plan on etching some pcbs with hydrochloric acid and hydrogen peroxide, which will therefore produce some kind of copper chloride green color which is highly toxic if released into the environnement it may be useful as an herbicide, but i dont have any garden right now. How i do my projects part 2 producing the pcb by cnlohr. Etching with air regenerated acid cupric chloride an excellent indepth page on acid cupric chloride etching by adam seychell. Mg chemicals ferric chloride copper etchant solution, 4l.
Chemistry of the cupric chloride etch chemical milling. The pcb manufacturers usually employ a wet etching process. Nice little kit for drawing and building pc boards. Ive been using my new container store spaghettiholder etching tank with cupric chloride etchant for several months now, and im pretty pleased with it. This method involves chemical solvents like ferric chloride fecl3 or cupric chloride cucl2.
For drilling i use hss drills as they are much more flexible than the carbide drills and seem to last well drilling fibreglass boards at low speeds. To make a pcb you need two things, an etchant and an etch resist. At 2 weeks, itll take twice as long to etch as it did when mixed fresh. The chemistry of homeetched pcbs adafruit industries. I can walk away and let the bubbles do the etching, needing only a visit halfway continue reading. The dissolved copper creates cupric chloride which can itself be used to etch metal. Pcb etching process is carried out to get rid of the excessive copper, and only the required copper traces are left behind after the etching process.
When exhausted it can be revived by adding hydrogen peroxide or by bubbling air through it. Cuppric chloride, cucl2h2o2, is another pcb etchant that is actually made by etching copper in a mixture of hcl and h2o2. To etch, i make cupric chloride from hydrochloric acid as its hard to get ferric chloride locally, as it gets tired you just bubble air through it and add a bit more acid to recharge it again. Stripping and etching process of pcb sierra assembly. Its easy enough to come by, and the ferric by itself is no big environmental problem.
Etching your pcb is a mandatory step for any sort of pcb production. The copper is converted to hydroxide, just as it would be if sodium hydroxide was added, however the reaction with calcium is much less violent, and the sludge formed is a lot less liquid. You can also prolong the etchant by the way you use it. Both solutions contain water and the etching reaction itself produces water. Call it hightechlowtech circuit making, if you will youll need. Cupric chloride will react with copper to form cuprous chloride. Learn about pcb manufacturing processes sierra circuits. However, the roughness from cupric chloride micro etching depends on the organic components in the system. The cupric chloride etchant is controlled and replenished in a number of different ways.
Simple chemical regeneration is possible by adding hcl and enough h 2 o 2 to re oxidize the cuprous chloride to cupric. Build a complete pcb etching station and produce boards in just one hour. The problem with ferric chloride is that it is not easily reusable. The fact that you can etch copper using a solution of the copper itself depends on the fact that you can easily transform from one oxidation state to the other. In wet etching, the unwanted material gets dissolved when immersed in a chemical solution. First, the ferric will oxidize the copper metal to cupric, while being reduced to ferrous. Printed circuit board fabrication chemistry of the cupric. Having an etchant that wont last long stretches between boards is kind of dumb and can get pretty expensive with the store bought variety of this etchant. Photo by vkoudymov keeping the ratio of hydrogen peroxide to hydrochloric acid is rather difficult over the course of multiple etchings. Our goal is to have some fun while exploring and learning. Plasma dry etching acts like a plasma lamp when etching away the unwanted copper on your pcb.
Proper storage of ferric cloride pcb etchant stack exchange. However, most of them are bloated, unsurveyable or incomplete. Which acid is used in etching process for making pcb. Circuits software are hard enough to debug in a new design without the additional ifs about the pcb. This page documents a successful version of this method done with a 3dprintmi and a scriber holder, and earlier on a mcwirestyle cnc by matt gilbert the scratch n etch method is one of the more successful methods of automated circuitry making. Instead, she combines vinegar, hydrogen peroxide, and salt. Pcb etching how to achieve the perfect pcb etching. I do handetching of pcbs and i dont use ferric chloride. No volatile compounds are usedonly simple bases which can be rendered environmentally safe by filtering solids and neutralizing with hcl see manufacturer instructions for proper disposal procedures. And while the etchant used was cupric chloride, not ammoniacal copper etch, what was discovered should apply to the use of ammoniacal etch in the pcb industry as well. The etchants are typically also about 12 normal with respect to hcl.
Etch rate can be very high but is dependant on solution movement over the surface of the board and temperature. Pcb etchant solutions engineering technical pcbway. Copper etching is the main process in the printed circuit board pcb manufacturing for electronics application. The typical byproduct of a ferric chloride etch of a copper pcb would be a solution of ferric chloride, cuprous and cupric chloride, water, and dissolved photoresist. Because of its low cost, environment aspects, and simple regeneration techniques, cupric chloride was chosen to be the most attractive etchant. Pcb is etched with a 220 gl solution of ammonium peroxydisulfate a. Pcb etching technique and analysis of etching solution. Copper etching is considerably important process in electronics industry, particularly in the fabrication of printed circuit board. Then i remembered id been thinking of switching to reusable etchant, created on the bench using muriatic acid the store name for hydrochloric acid, hcl, used for cleaning swimming pools. The scratch n etch method for producing pcbs uses an etch resist that is scratched away with a cnc and a carbide scriber. This is the reason why cupric chloride is one of two main etchants widely used by pcb fabricators.
Etching your own circuit boards is tons of fun, but etching requires strong chemicals to dissolve the copper plating on blank circuit boards. Technical information bulletin 8 chemcut page 2 of 14 chemical reactions cupric chloride is an acidic solution with a ph of etching. Super simple copper etching sylvias mini maker show by make. If not, dont worry, ill mention the changes you need to make at a. The ferric etching machine can be configured to do ferric chloride etching, as well as cupric chloride etching,used for photochemical milling filter meshes, seives, screens and grilles. Ammonium persulfate is also used as a chemical solution for etching. Mg chemicals 415 ferric chloride copper etchant solution, 945ml liquid bottle. The chemistry of the cupric chloride etching process. The cupric chloride etchant generates large quantities of cuprous ion as the copper is being etched. I assume the pcb copper plate is of size 4x4 inches and you have a ground plane on pcb. Mar 31, 2017 here, i need to assume few things before you start comparing the information with your pcb. A process of chemically etching circuit boards application note.
236 491 1579 1465 1241 424 1487 1325 1429 491 393 315 280 904 863 1269 798 1463 1556 1183 1565 392 733 1281 1439 805 212 244 1077 1230 1350 202