Ammonium persulfate pcb etching

The method described here assumes you want to make a PCB from an electronics magazine PCB layout - so you can copy it with a copier - or you are able to print your own PCB layouts from a PCB design package or have them available in electronic format and you can print them with a laser printer. I am using the described method below successfully since I was forced to find an etching method to be used at home after the company I worked for dumped their prototype PCB production tools.

The PCB layout is a mirrored positive one - black on white. Mirrored as viewed from the silkscreen top component side. The PCB layout is printed on paper by means of a laser printer or copier machine. The laser printer or copier toner will not run out when it gets wet or oily. The ink of an inkjet paper print does run out and inkjet printers are therefore useless with the described method. These printers work fine. It might be possible that the toner texture on the layout prints from your used laser printer is not dense enough and passes too much light.

PCB Etching - Toner Transfer Method

However, results might be improved by setting the toner density to maximum. Generally printer driver properties allow to set the toner density. The PCB layout paper is drenched with sunflower-seed oil.

Sunflower-seed oil is common available from your local grocery or wall market. Superfluous oil should be removed carefully with tissue paper. The sunflower-seed oil is used to make the white part of the layout paper transparent for light. The layout paper should be carefully dried on forehand as much as possible with tissue paper. Exposed to the air over a number of hours, the layout paper becomes rigid again.

A kind of polymerization takes place. You will get a lot less or no greasy fingers anymore afterwards. Other mineral or vegetable oils might work as well to obtain light transparency. When I started experimenting, sunflower-seed oil was the first oil I used and it worked fine. So I didn't try any other oils. Using water does not work. The layout paper crumples up a bit.

The protective plastic layer is removed - peeled back - from the photosensitive PCB. The toner side of the greased layout is placed on the copper of the PCB. Captured air-bubbles are gently pressed away from underneath the layout. The PCB with the layout is now covered with an appropriate sized windowpane and placed on a piece of plain polished tile or marble. The tile or marble absorbs the heat coming from the UV bulb, which is significant.

Three to four minutes W bulb UV exposure from a distance of cm will do the photo process. Take care when finished and removing the PCB, it gets hot! You can make this solvent by adding 10 gram of sodium hydroxide pellets to 1 liter of water and mix it until everything is dissolved.Super Administrator.

The art of wondering makes life worth living Want to wonder? Not logged in [ Login ]. Back to:. Printable Version. Once consumed, it is "waste". Once mixed, it will lose its etching ability in a short time frame days or a week or so. It works better hot, and barely at room temperature. There's scant information on how to dispose of it, so it tends to Nurdrage has a video on making Copper Chloride etchant in three different ways, and one of the ways used Copper Sulfate as the starting ingredient.

I believe that Copper Sulfate is a component of the waste. Taking spent etchant waste, and transforming it into a renewable etchant is very appealing! Additionally, Nurdrage indicates that the Sulfate ions are not a part of the etching process and don't interfere, so I jump to the conclusion that it's very tolerant of any type of contamination.

The slurry turned a pale green, as expected. I added more HCl until there were no more blue crystals left It amounts to about a third to a half of the beaker contents. White-ish precipitate on the bottom, bright green liquid on top. I tried a small strip of copper-clad PCB in the beaker, and while it did etch the copper, it wasn't as fast as I would have liked.

It got through the copper overnight. I believe that my "other stuff" is ammonium sulfate in the original waste. After the HCL addition, perhaps I have some ammonium chloride, too?

I've looked at solubility ratings, and both Copper Sulfate and ammonium sulfate appear to have similar solubilities. If I've managed to convert either, both, partially? I don't know how to determine the balance between Cu conversion and NH4 conversion to Chloride - is there a way to tip the scales in one direction or the other? Does anyone have any suggestions on how to proceed? To reiterate, I wish to convert my ammonium persulfate copper etching waste into CuCl2 etchant.

If I reuse my CuCl2 etchant again and again, year after year, will I encounter any problems? Am I overlooking something, i. What's the decomposition results in that case? Thank you in advance for any guidance. Just filter it and keep the green liquid.It is a colourless white salt that is highly soluble in water, much more so than the related potassium salt. It is a strong oxidizing agent that is used in polymer chemistryas an etchantand as a cleaning and bleaching agent.

The dissolution of the salt in water is an endothermic process. Ammonium persulfate is prepared by electrolysis of a cold concentrated solution of either ammonium sulfate or ammonium bisulfate in sulfuric acid at a high current density. As an oxidizing agent and a source of radicalsAPS finds many commercial applications. Salts of sulfate are mainly used as radical initiators in the polymerization of certain alkenes.

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Commercially important polymers prepared using persulfates include styrene-butadiene rubber and polytetrafluoroethylene. In solution, the dianion dissociates to give radicals: [4].

The sulfate radical adds to the alkene to give a sulfate ester radical. It is also used along with tetramethylethylenediamine to catalyze the polymerization of acrylamide in making a polyacrylamide gel, hence being important for SDS-PAGE and western blot.

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Illustrative of its powerful oxidizing properties, it is used to etch copper on printed circuit boards as an alternative to ferric chloride solution. InJohn William Turrentine used a dilute ammonium persulfate solution to etch copper.

Ratio of ammonia persulfate to water?

Turrentine weighed copper spirals before placing the copper spirals into the ammonium persulfate solution for an hour. After an hour, the spirals were weighed again and the amount of copper dissolved by ammonium persulfate was recorded. This experiment was extended to other metals such as nickel, cadmium, and iron, all of which yielded similar results.

Ammonium persulfate is a standard ingredient in hair bleach. Persulfates are used as oxidants in organic chemistry. Airborne dust containing ammonium persulfate may be irritating to eyenosethroatlung and skin upon contact. Exposure to high levels of dust may cause difficulty in breathing. It has been noted that persulfate salts are a major cause of asthmatic effects in women. These asthmatic effects are proposed to be caused by the oxidation of cysteine residues, as well as methionine residues.Caropreso, Hamilton Square, Kenneth J.

Radimer, Little Falls, and Bernard J. Hogya, Sayreville, N. Continuation-impart of application Ser. This application Sept. Cross reference to related applications This application is a continuation-in-part of application Ser. Caropreso, Kenneth J. Radimer and Bernard J. Background of the invention A Field of the invention. This invention relates to aqueous ammonium persulfate etching solutions, and more specifically, to the reactivation of spent ammonium persulfate etching solutions containing residual ammonium persulfate values.

B Description of the prior art. This is desirable, for example, in place of ordinary machining in order to remove specified amounts of these metals from surfaces of fragile or peculiarly shaped objects. A more widespread application of this technique is the production of printed electrical circuits. In this application a resist or mask in the form of the desired circuit is placed over the surface of a metal film, e. The copper area not covered by the resist is dissolved, while the copper covered by the resist remains to form the desired circuit.

Ammonium persulfate solutions are desirable in such applications because they do not generate obnoxious fumes, are easy to work with, and are relatively noncorrosive to certain common materials of construction, such as stainless steels.

In use, the metal, e. The resulting spent etchant is then treated to remove the dissolved copper and is disposed of. One serious problem that has arisen in using this process is that substantial amounts of persulfate are discarded in the spent etchant.

It has not been possible to recover or make use of the remaining persulfate values in the spent etchant on a commercial scale; the mere addition of fresh ammonium persulfate to a spent etching solution to restore the original persulfate concentration does not yield an acice ceptable etching solution because such solutions give inferior and erratic etching.

A second problem is that the treatment of spent persulfate solutions to remove the dissolved metal entails an additional process step which adds to the expense of disposing of these solutions. The dissolved metal, e. Objects of the invention It is an object of the present invention to treat spent persulfate etching solutions on a commercially acceptable basis to recover residual persulfate values and to eliminate the expense of removing dissolved metal in the solution and of disposing of the spent solutions.

It is a further object of the present invention to treat spent persulfate etching solutions to remove the products of the etching reaction selectively and to obtain reactivated solutions which yield consistent, commercially acceptable etching rates.

Summary of the invention We have found that spent, aqueous ammonium persulfate etching solutions which have been used to dissolve certain metals, namely copper, cobalt, iron, nickel, Zinc and magnesium, and which contain residual ammonium persulfate values can be reactivated by cooling these solutions to a temperature preferably about 0 C.

Surprisingly, the reactivated ammonium persulfate solutions with or without fresh ammonium persulfate addition can be used to give high quality etching down to much lower residual persulfate values than can fresh, untreated ammonium persulfate solutions.

Description of the invention and the preferred embodiments In carrying out the present invention a fresh, aqueous 0. This etching solution is then heated to temperatures of from about 35 to 46 C. The etching can take place either by conventional immersion etching or spray etching.

In the immersion etching process the masked metal coated workpiece is immersed in the solution for the amount of time required to etch the exposed metal surface. In the spray etching technique the persulfate solution is discharged from a spray nozzle under pressure and the spray impinges on the masked workpiece. In practice, the spray etching technique is preferred because it permits shorter etching times and results in a better quality etch.

This is due in large measure to the constant replacement of etchant in contact with the workpiece and to the removal of the dissolved metal-rich layer of etchant in immediate contact with the workpiece.

ammonium persulfate pcb etching

Etching is continued until the solution has been depleted of persulfate values and reaches a concentration of about 0.Forums New posts Search forums.

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ammonium persulfate pcb etching

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Ratio of ammonia persulfate to water? Thread starter aperri Start date Aug 12, Waht is the proper ratio of ammonia persulfate to water for etching a copper PCB? I bought one of those etching tanks from Circuit Specialist ET20 and it recommends I use no less than 2 Liters of etchant. I would even say that this tank is over-kill but I have it and want to try to use it. One site recommended a water to acid ratio I was wondering if that sounds right.

Boncuk New Member. Etching tank Hi asperri, the etching tank you purchased contains an aquarium heater, which will get too hot and break if if the liquid level is under the heating element. Therefore this releatively high amount of etching solution is recommended. The heater will become red hot heating the glass cylinder too.

Causing movement of the etching solution by any means will break the cylinder at the point between "cool" and "hot". Not using the heater the etching process takes a long time at room temperature. At 10degC it won't etch at all. The tank should be equipped with an air distribution frame at the bottom. This is very important for the mechanical work during etching.Opening the bottle reveals large clumps and it seems the whole bottle has undergone this change After like 30 minutes with agitation the copper was only marginally thinner pink color I decided to pour some Ferric Chloride in there and it was finished within like minutes after that I think because I etched and agitated for so long that some of my etch-resist began to chip off along the edges.

My main question is Does anybody know what kind of shelf-life to expect or a better alternative to storage it's been sitting in the MG Chemicals bottle this whole time, opened before but untouched for a long long tmie Also toner-transfer What do you guys think of that method seems kinda iffy to me. I chose photo-etch because I think it should be more predictable Any tips, etc I use the blue toner paper with much success.

ammonium persulfate pcb etching

Cleanliness is key. The printer makes a difference too. I use the Sodium Persulfate from MG a little less expensive. The key is heat. Put the etchant in the microwave for 22 seconds.

It will etch much faster if it's hot as a cup of freshly brewed coffee - but don't drink it. I saw on a website some guy was using baking soda to develop his boards. Has anyone tried this. I believe I could neutralize the hydroxide with vinegar and then dump down the drain, sound good? You need a cool and dry place to store it. And yes: heat is an important factor. I don't go as high as the temperature of a good coffee For coffee, that temp would be too low :. Quote: Any tips, etc I would give a try with the higher temperature.

I use gr per liter. And use it more than once: 4 eurocards per liter. Dragon broken?

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I currently use the Pulsar paper and a laser printer to put the pattern on the paper. The Pulsar paper is like a decal paper. It has a special coating on one side. The pattern is applied to the side of the paper with the special coating.Ammonium persulfate is one of many compounds available for copper etching, and is often used for etching circuit boards in particular. It is available in a dry or powder form and must be mixed with water to create the etching solution.

In addition, the solution must be hot to etch copper efficiently, and heat causes ammonium persulfate to decompose. Therefore, you must mix a fresh solution every time you want to etch copper.

Mixing an ammonium persulfate solution is not difficult, but it is important to take proper precautions to ensure safety when handling this chemical. Put on the gloves, goggles and mask. Ammonium persulfate can cause serious skin irritation and unpleasant or irritating fumes. It can also cause allergic reactions in some people.

Pour milliliters of distilled water into a clean glass container. If you want to use the solution immediately, heat the water.

The metric system is standard for the sciences, including chemistry, and working with grams and milliliters enables you to calculate ratios more easily. Put a clean glass container or disposable container for weighing chemicals onto a scale and tare it, or reduce the weight to zero so the scale does not take the weight of the container into account.

Add ammonium persulfate powder to the empty glass container using a clean plastic spoon or a chemistry spoon until you have 10 grams of powder. Carefully add the powder to the container of distilled water and stir thoroughly with a glass stirring rod.

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The powder makes a clear solution, so stir until you do not see any powder. Make more of the solution, if necessary, until you have enough to cover the item you are etching. Adding 10 grams to milliliters of water makes a standard percent solution. This is typical for etching, although you can make a stronger solution if desired, up to about 20 percent. In addition, some companies sell this chemical in tablets that create a percent solution when added to the proper amount of water and do not need weighing.

Always work with clean materials and use glass containers, which have low chemical reactivity. While less dangerous than many other etching chemicals, ammonium persulfate is a strong oxidizer and can have very negative reactions with other chemicals.

Work outdoors or in areas with good ventilation to disperse irritating fumes. By: Rochelle Leggett Updated April 12, Share It. Things You'll Need. Photo Credits.

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