Quest for the perfect printed circuit board...

Discussion in 'Homebrew and Kit Projects' started by W4INF, Oct 17, 2008.

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  1. W4INF

    W4INF Ham Member QRZ Page

    A quest for the perfect home brew/DIY printed circuit board. A week ago, I knew nothing and was getting horrid results. I knew some tinkering and figuring was going to be in order. Just about the time I was ready to give up, I start having some brain storms and give it one last shot, with good results I might add.


    Image below shows various stages of experimenting early on.
    Bottom left is glossy magazine paper with clothes iron for 5 min.
    Not too good. Top image is laserjet clear transparency. 5 min
    yielded a bled toner, but it looks promising so Ill give it another
    shot with a different method later. Bottom right is inkjet glossy
    photo paper, I dont think I had enough pressure on the iron long
    enough, and the board was not prepped well enough.
    [​IMG]




    Image below shows the modified clothes iron and a pressure
    rack I was building to make it all work better. One "secret"
    to a good transfer, is pressure and heat. Putting hard pressure
    on the transfer for 5 min is hard work, this jig will do the work
    for me.
    [​IMG]




    I create the PCB layout using Pad2Pad, then with PDFCreator,
    I output to 600 DPI a BMP. I did use JPEG, but there was some
    compression artifact. Saving to BMP yields a 4.5 meg image now,
    but.. crisp and clean with no artifact. Paper is HP inkjet glossy
    photo paper in 4X6 inch sheets, 50 for $7 at WalMart.
    [​IMG]




    A proud result of the W4INF Ghetto Workshop! A modified iron
    transformed into a dedicated PCB transfer station. Two 10 lb
    weights plus 4 clamps apply a guessed 200 lbs of pressure on
    the board for about 5 min. (I previously stated 50 lbs but that
    was discovered to be incorrect)
    [​IMG]




    After the board has been pressed and heated, I take a stainless
    bowl filled half way and convert the press into a hot plate, the
    board is "cooked" in HOT water (but, its not boiling hot...) for
    about 20 minutes. The paper peels off very easy after that. No
    residue on the board at all.
    [​IMG]




    Here is the result, a super crisp and clear transfer and shiny
    copper! I tried a few different things, finally tried the method
    that sounded as if it made the least sense... I used an SOS/
    Brillo pad that already had cleaner in it, wet scrubbed the board
    for the first stage of prep. The board was super clean and very
    nice after that. I then wiped it off with denatured alcohol and
    let it air dry before pressing.
    [​IMG]




    Here is the board after etching with 2 parts hydrogen peroxide
    and 1 part Muriatic acid. Etching time was about 5 min.
    [​IMG]




    Here is the board after toner is removed with acetone. Notice
    the super crisp lines and full transfer of 99% of the layout, only
    the thin outside lines that boxed in the circuits had some
    difficulty.
    [​IMG]




    The above R1.7 board can be had at:
    http://rogertango.com/pcb/


    This post was intended to be a basic intro... a full writeup will
    be available soon, including a video. However, there really is
    enough information and detail in this post to get up and running.

    Hope this helps,
    Andrew
     
    Last edited: Oct 18, 2008
  2. KC4UMO

    KC4UMO Ham Member QRZ Page

    Very nice job Andrew!
    Well done.
    That sure beats what my boards look like.
    I have several projects I like to try this on myself.
     
  3. K9FV

    K9FV Ham Member QRZ Page

    That is a NICE result - I will have to try that iron with pressure myself. I've turned out some ok boards, but nothing like that. Andrew, you have done GREAT!!!! too bad you don't live close by - we'd etch some boards together. I had got to use clear transparency because the photo paper was too hard to remove, maybe "cooking" for a while in water is the answer?

    Thank you agian - and be sure to let us know how the tin plate works.

    Edit: Is the board same size as before?

    73 de Ken H>
     
    Last edited: Oct 17, 2008
  4. W4INF

    W4INF Ham Member QRZ Page

    Ken,
    Yes, the "cook in water" is the real deal trick... otherwise, you will toil with getting it off for hours! Once I hot water treated it, the paper peeled off without any residue at all on the board!

    The final board in the photos is R1.7 and is smaller than the others. Reason being, UPS man dropped off my 130pc of 1.5"X3" scrap blanks, DS, though I only needed SS, for $20 I couldnt let the auction pass me up! So I reckon I got about $100 worth of blanks... and perfect size for smaller projects too. Anyway, I took out some stuff (you can short pins 7 to 8 on the DB9) and made it smaller to fit on the boards that just came.

    I forgot to mention, a piece of CARDBOARD was under the PCB, just just a bit bigger than then PCB. I think it allowed for more even pressure. I think Ill use the same method from now on, it appears to be "tried and true" at this stage.

    HTH,
    Andrew
     
    Last edited: Oct 17, 2008
  5. W4INF

    W4INF Ham Member QRZ Page

    The clamps are cumbersome, Ive brain stormed a fix that I hope to have rigged today or tomorrow. Will post when I have it. Last night, I had 140 pounds of weight on the press. The new rig setup Ill be doing, I estimate about 200 pounds of force. Maybe it sounds like a lot... but, you see the results I get-

    Andrew
     
    Last edited: Oct 17, 2008
  6. WA7KKP

    WA7KKP Ham Member QRZ Page

    Excellent dissertation

    Congratulations, you show some of that American resourcefullness that many now lack.

    If you don't know how, keep trying until you find something that works. That's how Edison came up with the light bulb.

    Sadly, these days, if you can't BUY it already made for you, it can't be done.

    Gary WA7KKP
     
  7. W4INF

    W4INF Ham Member QRZ Page

    Thx Gary (blush).

    Andrew
     
  8. KC4UMO

    KC4UMO Ham Member QRZ Page

    Again good job.
    I was going to give this a try this week end. But noticed I was out of boards, Ran to rat shack. They had some a few months ago right?
    Nope!
    So I have to order now.
     
  9. W4INF

    W4INF Ham Member QRZ Page

    Thx Buddy. Yup, I got some about a year ago from the Rat, but all they stock now is the perf boards with copper pads.

    Also, the press I am building is using the KISS method. It is designed to be shown that anyone with some patience and a few tools can build it with minimal cost.

    The frame is 3/4" square tube. Hardware is 1/4" 20 bolts. All connections are tapped so no bolts are needed. I used a drill press, but a hand drill will work. The platform is 3/4" pine. The iron was WalMart for about $12. A few washers are used for spacers. The revised press will use some square "u-bolts" for pressure. This one is gonna be good! I hope to finish this up this evening and be pressing another board before bed time. If I do, Ill post some updated pictures.

    Aluminum is not used because under the high pressure that is applied it may offer too much flex.


    The white part of the iron is bakalite type material, and has fractured under high pressure. So, I will be removing that and trying to figure how to mount the hot plate to the upper part of the press frame. Theres only 1 good hole to use. Mounting it to the top is not too critical- it only makes it one unit. You need something to hold the plate, you sure as heck cant handle it bare handed without something!

    Also, I hijacked/liberated some overhead transparency from work, last time I tried it with the iron, the heat was too much and the toner bled. Ill try one tonight in the small laminator I have that will take PCBs.


    Andrew
     
    Last edited: Oct 18, 2008
  10. W4INF

    W4INF Ham Member QRZ Page

    Also, R2.0 of the CI-V board is in the works, a rework of the traces and it will be smaller, also eliminate the JP1 wire jumper. :cool:

    Andrew

    UPDATE:
    R2.1 just uploaded. JP1 wire jumper removed and board made more compact.
     
    Last edited: Oct 20, 2008
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