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Cheap and good PCB etching solution.....

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#81
gogo ferric chloride isn't added to help it break down, it's added to aid in flocculation, it provides a nucleation site to remove other metals from the waste stream as the iron adds a large amount of weight to the precipitate helping gravity separators to get more of the sludge out and allowing increased flow rates. It does have the downside of producing a thicker sludge and the iron itself is effectively thrown out with the waste so it's sometimes not used.
 
#84
My concern is not the production of you final product however. It's the proper disposal of the elements you use in it.

Hobbyists think they can just flush this stuff down the drain at will without consequence.
You've shown you know how one chemical in waste disposal works and drew the conclusion that because you used it in etching that it was safe and beneficial to waste treatment facilities down the line, implying that dumping it down the drain might actually be safe.

What you don't think of is if you just dump this stuff down the drain it will precipitate and floc in the sewer itself, mind you not as well as it would in the waste treatment plant, but it will, and you'll end up with a heavy metal sludge in the sewer which will go into ground water etc.. etc.. Much like sewer waste if it's not treated. Most hazardous waste from a sewer treatment plant is immobilized in concrete and landfilled. Only slightly better than dumping it down the drain.
 

Oznog

Active Member
#85
I've stopped etching entirely, in favor of CNC engraving.

Stuff's awesome. I can do really fine traces with extremely good reliability, then switch to carbide drills and do all the holes with perfect accuracy. Then flip over, align the coordinate system zero and angle to match the holes previously drilled, and engrave the bottom.

This is just WAY simpler than setting up transparencies, sensitizing/developing, or toner transfer. Actually my toner transfer efforts have been foiled when I found hairlines in the traces- invisible to the naked eye, but a microscope showed it. I just can't deal with any possibility of problems like this mucking up my development efforts. And it's so clean.
 

3v0

Coop Build Coordinator
Forum Supporter
#86
I have been CNC drilling and then etching using Eagle and PCB-GCODE.

My question is about trace width. About the smallest line width I use is .01 in. Does this work with milling or does the copper lift from the PCB ?

3v0
 
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#87
wow CNC machine nice. did you buy one or make your own? The reason I ask is because I might try to make one myself. I think I have the software to run it. Is a Linux package call Braindead.
gogo
 
#88
I have been CNC drilling and then etching using Eagle and PCB-GCODE.

My question is about trace width. About the smallest line width I use is .01 in. Does this work with milling or does the copper lift from the PCB ?

3v0
Hi 3V0,have you actually built a CNC machine for drilling PCB's?If so i found this video

How to Build a Cnc Machine out of 2 Cd Drives - Video


It shows how to make a CNC machine but have doubts(no clue) about how one is supposed to control it.Couldnt find its controller.I mean it would save a lot of work trying to get the TTP substitute thing work correctly and then etch it.Do you have a better way.As far as disposal is concerned it is not a big problem(not caring about environment) here but i am a man of conscience!:eek:
 
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unclejed613

Well-Known Member
#90
interesting, i used to live in a semi-rural town, and had to have cottonwood roots removed from my sewer pipe a couple of times, once by the town. the guy from the water department that replaced the section of sewer pipe on the town's side of my fence gave me a can of "root-be-gone" and told me to flush some of it down the toilet once a month. it was mostly copper chloride.
 

unclejed613

Well-Known Member
#91
Hi 3V0,have you actually built a CNC machine for drilling PCB's?If so i found this video

How to Build a Cnc Machine out of 2 Cd Drives - Video


It shows how to make a CNC machine but have doubts(no clue) about how one is supposed to control it.Couldnt find its controller.I mean it would save a lot of work trying to get the TTP substitute thing work correctly and then etch it.Do you have a better way.As far as disposal is concerned it is not a big problem(not caring about environment) here but i am a man of conscience!:eek:
not only would those DC motors be a bear to control accurately (fine pitch stepper motors are what commercial CNC machines use), but those little DC motors have very low torque, and the plastic drawers used in the video flex too much. a machine tool needs RIGIDITY, otherwise it will be neither precise OR accurate. in the video, i saw the "work" (the piece of wood) move vertically when the pen made contact with it. think of what the result would be if your Z axis was set to the depth of a copper layer on a PC board, and you tried to etch a board on a table that had that much "give". the milling bit wouldn't remove enough copper over most of the board. and the bit would "chatter" leaving a rough surface.

i replace enough of those traverse mechs daily to know that those little motors have very serious loading limitations. the traverse motor only has to move a few grams of mass, and it's controlled by an analog servo, with the servo signal derived from the laser pickup.

a better way to make an XY table would be to gut an old dot matrix printer for it's stepper motors, and get the timing strips and opto sensors out of a couple of inkjet printers. that way you have the high torque and fine pitch motors for the table, and a dimensional reference with the timing strips.
 
#93
You can still buy root be gone (copper chloride) at most hardware stores. Its used to kill tree trunks too.
gogo
 
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unclejed613

Well-Known Member
#95
About the PCB etchant, especially Ferric Chloride, is it safe after I mixed these used stuff with a baking powder/soda?
ferric chloride is a salt. it's action on copper is a replacement reaction, the iron for the copper. the iron precipitates out and the copper bonds to the chloride ions. chlorine "likes" copper a little bit more than iron. i don't think there's actually anything here that would happen with ferric chloride and baking soda. since ferric chloride isn't an acid, there's no oxidizer to reduce. sodium usually stays bonded very closely to whatever it's compounded with. i would think there may be some possibility of a bicarbonate ions being replaced by chlorine ions. the only way to find out would be to try it in a small quantity. if you get iron and copper precipitate, and carbon dioxide (gas bubbles), and a resulting sodium chloride solution, then you have a viable method for making these salts safer for the sewer system. if you end up with a foggy mixture of sodium bicarbonate and ferric and copper ( since it's waste solution) chlorides, then it wouldn't really do much good.

maybe somebody with more chemistry experience could weigh in on this.
 
#96
Press n Peel

Hi new here, but I use Ink Jet Photo paper sold by Epson. Print on the white side (the other side is off-white) clean the board with a good rub down, and with alchohol. Iron it down well with an ordinarary iron, and then soak the board in the sink in warm water. Thanks for the tip on the solution , will give it a bash:)
 

Oznog

Active Member
#97
I have been CNC drilling and then etching using Eagle and PCB-GCODE.

My question is about trace width. About the smallest line width I use is .01 in. Does this work with milling or does the copper lift from the PCB ?

3v0
10 mil? No prob- and BTW, WAY easier to do reliably than 10 mil with chemical etching. There is a limit on separation. I have a carbide bit with a 6 mil tip for fine work, but it has to run very slowly or the tip may break. But that's ok, if it takes an hour to make a board, well, I'll just set it and come back when it's done, it's no big deal. I also have a 10mil tip when the work does not need very fine-pitch separation. That runs much faster and has fewer steps because it's a wider swath per step.

There are problems with board flatness, esp if the traces are thin and the area large. You zero it on the surface and try to descend X many mils down, but the engraver's V-shaped so if the board is warped and flexes upwards, it's too deep, the swath is wider, and the trace may disappear. If it's too shallow, the tip may not cut all the way through the copper. But, still, that's like the one and only persistent problem to deal with and it doesn't show up often with small boards because the height won't vary much over the lateral distances involved.

A Taig or Sherline or Sieg or Grizzly (recommend Taig, personally, Sherline's kinda crappy) mill with a proper CNC kit works great. Gecko is the only driver to consider right now, it's literally the only one on the market that really "works" and it works really well.

The great thing is you would never understand what a CNC mill will do for you until you try one out. It's amazing. Beyond your wildest dreams. There are PCB engraver machines, which I wouldn't bother with- the full milling machine is far more capable.
 
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