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Again, I totally agree! Just try to google "hcl h2o2 reaction"! Here is one link for example:Lots of equations can be written for the reactions of copper, HCl, and H2O2.
I just bought the new bottle of HCl (because, allegedly, the shelf life has expired some 11 years ago for my old bottle, although I'm not sure that HCl has shelf-life if stored properly (it was in a plastic bottle with some kind of seal on the cap)). I measured pH (with universal indicator) of my old HCl and it shows pH below +1 !? As I know, 20% (or 6M) HCl have pH of about -0,8 (so, it should be OK). Same result for the new bottle. On that new bottle of "technical HCl" stays 19%, but I saw before that manufacturers mark that "concentration range" as 19-21%. So, it is, in fact, azeotropic solution (about 20±1%). I bought pharmacy grade peroxide of 12% (in my state all the pharmacists MUST have master's degree (one level below doctor's degree), so I can be confident about peroxide concentration. Btw. I simply can't understand why people demand 30 (or even more!)% peroxide??? There is no any need for that concentration, and that is POISON! I can buy (not allways!) in the pharmacy that concentration of peroxide, but only if I give my IDs and put signature in special book (also known as "poison book")! Adults only!John said:It seems you have obtained fresh and/or have decided your HCl concentration is 19%. That is probably pretty close as constant boiling HCl is 20% by weight.
You forgot that I have pretty much laboratory experience (as I said I studied physics) - of course, never add water in any acid (except if it is diluted enough)! But, we allways have to repeat that warning, if nothing, because of "young chemists" that make stupid things over and over again (like mixing acetone and H2O2 or so)! And if you have concentrated acid and peroxide (why?) - peroxide is like water - so I agree, first goes water (or peroxide) and than, carefully, add acid. About hydrogen gas production: frankly, I don't remember when I saw that; I personally think that predominant gas in our case is oxigen (as you pointed before), than Cl, HCl(g)...John said:Also, it is generally recommended to add the acid to the peroxide-water solution.
....When I put PCB in the solution it immediately turns bright-green, but etching took too long, over 45 min.!
NO!, afaik, that really doesn't matter!jofre said:Could it be I need more solution (like a gallon or so)
Do you want to say that with use of FeCl3 everything is OK? If so,what is the problem? Because you can't use your bubble container?jofre said:I completed the PCB recurring to the good old Ferric Chloride and it also had some areas that took longer time to etch but I've got below PCB in about 15 minutes
Why you can't use it with ferric chloride? I want to build one such container, so it is important to me!jofre said:I've made an acrylic container with the air pump but I can not use it with Ferric Chloride.
I agree. But you can try "sponge-etching" or maybe etching in foam!jofre said:With the FCl3 you will need to keep taking the PCB in and out of the etchant.
It is unnecessary high temp. if you ask me - many people work under room-temperature, eventually with bubble agitation. Btw. you can put aquarium heater in your tank and agitate solution with appropriate air-stone and stronger pump (I plan to do this).jofre said:Other thing is that I keep the FCl3 at about 60C...
Again, it is only my opinion: it is not about long etching time (maybe in a smaller degree) but in solution itself - it is simply too aggressive. Some people have success even with toner-transfer, but that is IMHO a big frustrating lottery.jofre said:The problem on waiting a long time is that it will attack the exposed areas as shown in my first picture.
Do you try with fine steel-wool with neutral soap (it looks like a small cushion) for (manual) washing of dishes? It does everything needed: sand, clean and degrease (in one go) and doesn't leave any "remnants". After that let the PCB dry and than clean it with acetone! So far, I didn't find better method.jofre said:If anybody has a better and proven way to clean / sand / degrease the copper just let me know and I will give a try!
Do you try with fine steel-wool with neutral soap (it looks like a small cushion) for (manual) washing of dishes? It does everything needed: sand, clean and degrease (in one go) and doesn't leave any "remnants". After that let the PCB dry and than clean it with acetone! So far, I didn't find better method.
And who said that the board is "bright shiny" after cleaning with steel-wool-soap "sponge"? The PCB is only "normal" shiny and with addition of very small ("microscopic") scratches that help toner or photo-resist to adhere.jpanhalt said:Why do you need a bright shiny board to begin etching?
And who said that the board is "bright shiny" after cleaning with steel-wool-soap "sponge"? The PCB is only "normal" shiny and with addition of very small ("microscopic") scratches that help toner or photo-resist to adhere.
John, I just tried to answer to jofre's question:jpanhalt said:Where did jofre say he had problems making the resist adhere?
I only added my complete experience with that method, including better adherence. Must be I misunderstood something: I thought, and still think, that jofre has problem with etching protected areas of copper - you can clearly see from his pictures: protecting layer (photo-resist in his case) can not withstand HCl+H2O2 and finally "relents", so protected tracks and pads are etched too. With FeCl3 he has no problems.jofre said:I may do another try , now sanding the copper with a 400 grit sand paper , also scrubbing and perhaps using NaOH to rinse and degrease and try again to see if the copper is attacked in a more uniform way and get an overall etching time at or under 15 minutes.
If anybody has a better and proven way to clean / sand / degrease the copper just let me know and I will give a try!