Etching my own boards


  • Mod

    This is a fresh start of a previous discussion I added to another topic pre-forum-crash...

    My first 'production' of boards was an experiment and not too unsuccessful but I really did not like the etching part. It was dirty, took too much time and up to now it withheld me from creating another board without taking proper time. The way I did it: 'rocking a tray with etchant'.

    Then I saw the BreadBox Kickstarter project. To me this was a kick-ass-solution...

    However when I posted this on this forum it was my ass that was kicked.
    According to a few here on the forum it is too expensive and too fancy and they showed me some alternatives like a sort of an aquarium tank Either DIY (I like this one but there are many more) or to buy as a kit (like this one).

    Looking further I found this one but that one was also commented on as 'nice but not necessary'.

    That made me think, think, think and think again and browsing a bit brought me to a website that I found before and talks about (and sells) the toner technique. This time I found a page that explains how to etch cheap (very cheap), fast and efficient. It is pcbfx.com and this is the page.
    If this is really true, please bring it on, than I just saved a lot of money...

    So this is what I learned from this discussion:

    • Nice looking is not always the best :)
    • Buying cheap is not necessarily bad :)

    What is your take on this?

    Marcel


  • Mod

    @marceltrapman Welcome back to the interesting discussion )

    The most important step in etching is a drawing PCB design on the copper.
    The most common is to use thermo transfer or photo transfer.

    1. thermo transfer in my experience is best choice because it is faster and cheaper. The minimum track archived can be 0.3-0.2mm which is sufficient for most DIY PCBs. You will need:
    • appropriate laser printer. Printer is used to print design on paper which will be later transferred to copper. Not any toner can be successfully transferred this why not any printer can succeed
    • paper. very critical thing. There are number of recommendation on forums which paper to use. It is also some special paper you can purchase especially for thermo transfer. Regular office paper cannot be used because it absorbs toner. You need paper with smooth surface. In my experience the paper from some news-papers can be sufficient. Choose the news-paper with smooth and gloss but not thick. I use paper which is thinner that regular office paper.
    • iron or laminator. Regular iron can be used, but it will be hard to get a stable result with iron because both the stability of temperature & pressure are important for the result, It is better to have laminator . I will recommend to choose a laminator with 1. 4 rolls (2 heating and 2 cooling) 2. ability to work with a thick material up to 2mm 3. with regulated temperature up to 180 C
    • sand paper. I use paper with index 280 to sharp edges while I use index 1200-1500 to sharp the surface. This need to be done after cutting the edges but before thermo-transfer. After sharping is better to remove any fat from the surface and touch the surface by fingers.
    1. photo transfer. You can reach better result up to 0.1-0.2mm track but it is more expensive and requires more steps. For this you can choose from 1. PCB with photoresistive coverage 2. a special photoresistive film to cover copper by yourself. You will need laminator for best result. 3. special photoresistive spray to cover copper by yourself
      2 is less expensive but requires to have laminator and to do an additional step
      1 is most expensive but save time and guarantee stability in result
      3 is in the middle

    You will need:

    • prepared PCB material with photoresistive coverage (as described above)
    • UV lamp. It can be glass lamp, energy saving lamp or LED. All need to have to give UV light. before purchasing you will need to check that a light source wave length is compatible with a wave length recommended by selected photoresist
    • a film designed for printing. It can be laser print or inkjet. Not any inkjet is applicable while any laser can
    • a printer
    • chemicals for developing photoresist
    • chemicals to clean photoresist
    • the box for the liquid chemicals while developing/cleaning
    • sand paper as above

    For etching most commonly Feric chloride or ammonium persulhate. My choice is ammonium persulhate. It is transparent while feric chloride is dark yellow. Also feric can leave things stained

    While you learned how to draw the design on the copper you can use any transparent or semi-transparent plastic box for etching. Even at home temperature a fresh spread can work well but if you can heat it before use to 40-50 C you will run faster and beter even with not fresh spread. The visual control of the process is only needed this stage. All other tools is to make process simpler or nicer but not required


  • Mod

    @axillent I think you stated before (thank you for picking this up again) that the design will take more time and is more important even.

    I agree with that and I can only say: yes it can be very time consuming.
    The thing is that I am very much experienced in everything that has to do with using my 10 fingers and a track pad (or using a Wacom board). I am not afraid of my Mac to put it mildly :)

    However, all the other stuff has always had my interest but I did not touch it in a long time because I seemed to break everything when I was young(er). So this is a fresh experience for me and so I concentrate on this etching stuff which I don't fully understand.

    Apart from that I am a gadget freak. Show me something that looks nice and I get greedy...


  • Mod

    @marceltrapman if only etching stops you that means that you just in a few steps before the finish to get your first prize)

    what you do not understand in the etching? It is very simple chemical process. Just put you PCB with design drawing into your etching chemical and spend 15-20 minutes watching how cooper is disappearing


  • Mod

    @axillent Nothing I don't understand just that imho it is a bit of a primitive process where so many things are automated nicely :)
    I can do everything with clean hands and, more important, having it all standing by except for Etching.


  • Mod

    @marceltrapman are all of your kitchen cooking is automated with clean hands? :)
    I'm using long tweezers to keep hands off chemicals but the rest is put for the fan I do DIY for

    if all you do for DIY will be automated what will be the reason to keep it doing?)


  • Mod

    @axillent I give in :)



  • @axillent @marceltrapman Welcome back:)

    My (cheap ~15$ with shipping) driller stand arrived yesterday. Soon i will try how good/bad it is for drilling PCB holes. This is my equiplent for drilling: http://ppl.ug/Gz9FbbglsWE/ . You probably have seen my photos https://www.dropbox.com/sh/ec4ap8dgci1oe0p/AAD3YIqS_JqKMiUFu9TAfF5Ca .

    1, and 2 - right after transfering toner with proper paper, and laminator, and after about 5 minutes in water to get rid of paper
    3 - during the etching process with sodium persuflate, and container like this http://img14.allegroimg.pl/photos/oryginal/44/06/46/49/4406464944
    4, and 5 look after etching process
    6, and 7 look after cleaning from toner


  • Mod

    @jendrush Good looking boards (doubt that I am the one to judge it though).

    The stand looks nice.

    I have the Dremel stand, bought it a couple of years ago together with my Dremel.

    Although I am happy with it the disadvantage is not necessarily the position of the board but, imho, more the moving of the board by hand to each position. For that reason alone I look forward to my FABtotum :)

    Looking forward to hear about your experience...



  • I think quality is not that bad, but etching lasted too long(due to a little bit to low temperature), so traces are little overetched.


  • Mod

    @marceltrapman said:

    Although I am happy with it the disadvantage is not necessarily the position of the board but, imho, more the moving of the board by hand to each position. For that reason alone I look forward to my FABtotum :)

    the manual drilling is better to do when etching was finished. It is also a good idea to have a small hole in a center of each pad while designing PCB. This will give you a centering holes after etching for each pad.

    I spend a year to make my CNC very easy to use for PCB drilling & milling
    at the beginning the use of CNC was much worse comparing to manual drilling
    I'm not sure how well FABtotum is prepared


  • Mod

    @axillent said:

    It is also a good idea to have a small hole in a center of each pad while designing PCB. This will give you a centering holes after etching for each pad.

    Are you talking about a drill hole here? Like created by default by Eagle?

    I'm not sure how well FABtotum is prepared

    Neither am I, will have to do some experimenting I guess...


  • Mod

    @marceltrapman said:

    Are you talking about a drill hole here? Like created by default by Eagle?

    Yes, it is most easiest way to add free from toner holes while transferring design drawing to the copper
    This holes will get copper dissolved during etching and your drill will became centered while drilling


  • Mod

    @axillent Nice, that is what I already do...



  • @marceltrapman said:

    Looking forward to hear about your experience...

    I've tested this stand before moment. Generally not bad, but stability isn't "spectacular". If we have holes in pins, like @axillent mentioned there is no problem with drilling. Most important is that drilling with this stand is really more convinient than without:) I can't complaint to much, becouse more proffesional drilling stand with driller costs about 20 times more than this:)


  • Mod

    @jendrush Nice, I guess it is like you said, a more professional stand cost serious money but this one will be much better than doing this by hand ;)



  • @marceltrapman, using a smart and nice etching process is never something people have an issue with. The point people are trying to make on this thread is that if you can achieve the same results by using a small tank and an inexpensive chemical, why go for an expensive process. There are so many different etching processes available that you can choose from which are cheap enough to be used by anyone. Etching does impact the quality of a PCB but as long as you’re not making expensive antenna PCBs, usual process work fine.

    electronics assembly


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