Diy pcb. Drill or Etch first?

Discussion in 'The Projects Forum' started by jerseyguy1996, Apr 17, 2011.

  1. jerseyguy1996

    Thread Starter Active Member

    Feb 2, 2008
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    I made my first pcb yesterday. When I tried to drill the holes, the drill bit was pulling the pads right off the board. Does it make sense to drill the holes before etching to avoid the pads coming off?
     
  2. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Stretching back yo 1973, believe we etched, plated,& re-flowed before Lucy drilled, no spoiled boards that I remember
     
  3. GetDeviceInfo

    Senior Member

    Jun 7, 2009
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    probably a combination of drill sharpness/speed/feed. Etching first should provide a pilot 'hole' in the pad for your drill.
     
  4. Wendy

    Moderator

    Mar 24, 2008
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    Etch first, but don't clean the resist off until you drill the holes. The resist will help keep the dril bit centered, a good thing.

    How I make PCBs
     
  5. CDRIVE

    Senior Member

    Jul 1, 2008
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    Because PC boards are made of Fiberglass they are hard on (high speed steel) bits, which is what most people have in there arsenal. Solid Carbide bits will hold an edge much better. They are made for PCB drilling and have a heavy shank. That's only one factor. The second factor is PCB holes are typically much smaller than the smallest (typically 1/16th inch) bit you'll find in most bit caddies. Very small bits require very high speeds that are more in line with Dremel RPM (15 to 35000 RPM) than your typical hand drill. Because the bit is so small and fragile a miniature (high speed) drill press is a must for accuracy and to minimize bit breakage.
     
  6. Wendy

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    Mar 24, 2008
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    If you can get a Dremel type drill press it is much better still. In the link I showed my version, and the specialty drill bits I use. If you have the right tools they don't wear out or break, but getting them can be a challenge. That same thread covers several vendors to use.
     
  7. jerseyguy1996

    Thread Starter Active Member

    Feb 2, 2008
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    Thanks everyone for the responses. I am using a dremel 4000 with a 1/32 inch dremel bit and the dremel drill press. I think the problem is that the image of the pads and traces didn't include drill holes. I exported the image to MS paint and I am busy putting a drill hole into the middle of each pad. I'm sure I will need to find the specialised pcb bits soon but I am hoping that the drill holes in the pad will work for now.
     
  8. Wendy

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    Mar 24, 2008
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    I've used Paint for PCBs. It worked, but it wasn't pretty. A better software package is Gimp. It will go to the resolution of the printer, 600DPI, while Paint goes to 96DPI. The 96DPI bugs me deeply, as it is a total pain in the assets. Why 96, instead of 100? bleh.

    Nowdays I'm using Express PCB, which is not great but it works. Then I use Gimp to clean up the resultant output to my personal standards.

    Gimp is not easy to use, like Paint. The people who wrote Paint had their act together, except for that one major print scale detail. Gimp, in theory, will do everything Paint will, but I'm not even close to the proficiency with Gimp I am with Paint.

    BTW, print out a paper copy, and see how the parts fit by laying them on it. I've solved this problem, but I'm curious if you have (or are aware of it)?
     
  9. jerseyguy1996

    Thread Starter Active Member

    Feb 2, 2008
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    I'm not sure about the process that I am using. TI sent me Gerber files for a double sided circuit. I downloaded a free copy of Viewmate from here:

    http://www.pentalogix.com/ and imported the files so that I could view the circuit. Viewmate gives me the option to print to .bmp which I then open in paint. I am not sure if I can open a gerber file in a format that allows me to manipulate the pads as pads rather than manipulate them as a collection of pixels on the screen.

    Is there an easier way to manipulate a pcb circuit if I am just given the gerber files?
     
  10. Wendy

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    Mar 24, 2008
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    I suspect you will find Paint simply will not work. Scaling is very important, 1" must be 1", exactly. Paint can be accurate, but it is simply not scaled for this job.

    How were you planning on making the PCB?

    I think Eagle will handle gerber files, but I'm not sure. If you have never done this you have a steep learning curve ahead.
     
  11. jerseyguy1996

    Thread Starter Active Member

    Feb 2, 2008
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    I actually decided to try to design the PCB myself using ExpressPCB. It will be my first time trying to design one and it is a fairly ambitious schematic for a first one. I am planning to post it on here along with the schematic when I am done to see if anyone spots anything glaringly wrong. The TI PCB is double sided and I am hoping to fit everything on to one side. This way I can design it with the pads and clearances that I need to use the iron on toner transfer method along with appropriately sized drill wholes in the center of each pad.
     
  12. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    One tip that I use is to take a very sharp pointed scratch awl/ice pick and use it to make a 'center punch mark' for each hole before drilling. Don't use the awl/pick like a center punch, don't hit it with a hammer. Just apply some pressure and kind of twist it back and forth to make a little divot in the board. Makes a big difference in the ease of drilling in the correct spot.
     
  13. Wendy

    Moderator

    Mar 24, 2008
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    It the program, such as Express or any other PCB CAD program, leaves holes in the pattern. You don't need to do anything, after the PCB is etched their will be holes in the copper that work just fine. This was explained in my PCB etching tutorial in post #4.
     
  14. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    @ Bill, I know thats what the 'hole' in the trace is for, but not having a Dremel drill press the divot helps big time when using a lower speed bench drill press :) Haven't broke a drill or messed up a pad since starting to do this. The hole in th pad is the mark used for the divot.
     
  15. CDRIVE

    Senior Member

    Jul 1, 2008
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    As a guy who's spent as much time in the wood and machine shop as I have on a test bench, I concur. It certainly won't hurt to do so, especially if it's a hand drill or hand held dremel.

    Shop Tip: In a pinch you can cut the heads off small brads and use them as a drill bit in wood, plastic and fiberglass. Brads are made of a relatively soft alloy, but like I said... In a pinch.
     
  16. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    If you break PCB drill bits you can also just grind the end at a 45 degree diagonal angle and they drill pretty good.

    And of course once they are shorter they don't break again. ;)
     
  17. RogerTango

    New Member

    Apr 22, 2011
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    I have always:

    -etched
    -drilled
    -coated with Tinnit

    HTH,
    Andrew
     
  18. marshallf3

    Well-Known Member

    Jul 26, 2010
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    There is quite an advantage to using the tiny carbide bits that are mounted to a larger "holder" that will fit even a standard drill press. I think even Harbor Freight sells them.
     
  19. nerdegutta

    Moderator

    Dec 15, 2009
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    I'm using Eagle. When the board is etched the copper in the center of the pads are also etced, leaving a nice "line-up" when I'm drilling. I have a Dremel and a Dremel drill press.

    Etch
    Drill
    Solder
     
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