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[on:]

I have a project that will require two 3" square circuit boards.  I've made my own about 20 years ago and I'd like to make my own again to cut down on cost and the time it would take a professional shop to do it.  I'm looking for a kit, if anyone has used one.  Any suggestions or advice?

[Reply #1 on:]

Yes, but it requires that you consider investing in a laser printer.  The Laser Printer toner transfer method is one of the easiest ways to create your own PCB's. I actually have never sent a board design out to a service, having always done my own.

I would recommend using the gootee method.

http://fullnet.com/~tomg/gooteepc.htm

[Reply #2 on:]

Is $24.90 for 10 boards too much cost?
http://iteadstudio.com/store/index.php?main_page=product_info&cPath=19_20&products_id=175


Or maybe this as a kit.
http://www.pcbfx.com/

[Reply #3 on:]

The Laser Printer toner transfer method is one of the easiest ways to create your own PCB's

its the easiest cheapest way to produce your own boards, but boards with uv sensitive chemicals, a uv box and a transparency is sooooooo much easier but more costly

course you need the boards or chemicals to treat the pcb, developer, and a UV box but it beats trying not to mush laser toner with a iron, and having a extra printer around if you dont own a laser.

[Reply #4 on:]

The Laser Printer toner transfer method is one of the easiest ways to create your own PCB's

its the easiest cheapest way to produce your own boards, but boards with uv sensitive chemicals, a uv box and a transparency is sooooooo much easier but more costly

course you need the boards or chemicals to treat the pcb, developer, and a UV box but it beats trying not to mush laser toner with a iron, and having a extra printer around if you dont own a laser.

Or you could use a slightly modified (to increase the heat) hot laminator instead of an iron...

Another method (if cost isn't an issue) would be to use a CNC machine to mill away the excess copper...

[Reply #5 on:]

Or you could use a slightly modified (to increase the heat) hot laminator instead of an iron...

depends on your sources, at our goodwill they had some germicidal UV pool filter bulbs for a couple bucks that would work in a standard compact fluorescent socket so like 16 bucks I had the uv box made, vs 20 for a cheap laminator + big bulky laser printer I would have no other real use for ...

choices choices 

[Reply #6 on:]

i have tried but failed not because the method doesn't works it works but it call for a lot of hardwork and precise tools and timing like you should be using a glossy paper to print your pcb design onto and then the iron must be very well hot then also sometimes getting the whole design onto the pcb is not possible it happens that some of the design is not printed and remains on the glossy magazine page and i have also used laminator and according to me one time getting through the laminator will not do the thing instead you have to keep it in for sometime and even run multiple times through the laminator to get it done.

Printed PCB at home has always been a hard accomplishment.

i think you should DEVELOP a SCREEN PRINTING base instead going down the line using the hot iron method.

[Reply #7 on:]

Another method (if cost isn't an issue) would be to use a CNC machine to mill away the excess copper...

Then he has to invest in a DIY CNC first , that most probably he would not have done already or would not be having a CNC.

[Reply #8 on:]

CNC to remove copper is non-trivial
it can be done, but the copper tends to tear rather than cut cleanly
and the fibreglass underneath just eats the bits!

I've used the laser transfer method several times
works quite nicely
never trie double sided, but people do report success

[Reply #9 on:]

I was intimidated at first, but have since become quite proficient at successfully producing double-sided boards at home.  Here is a snapshot of one of my early/basic boards,


My current project uses a double sided board with 67 components, 213 pad and 29 vias.  I built the whole thing from scratch (i.e. printed, exposed, etched, drilled, soldered and assembled) starting yesterday morning (admittedly pretty early ) and was playing with the working prototype before dinner.

Board houses are the way to go if you have the resources (time & money).  But the turn-around time is key to me.  I often spin multiple new prototype boards in a weekend now.

There are a few tricks to learn, but the process is trivial for me now, even with somewhat complex boards.  Here is an overview of my process.

• PCB Design

I use Eagle PC.  I bought the hobbyist license and the phone support is awesome.  There is a free version for small boards.  There is a great video tutorial that got me off and running from scratch (no prior experience here)

• Transfer Method

I use the laser printer -> transparency -> photo resist approach.  This works really well... if you use heat stabilized transparencies.  Off the shelf transparency paper warps in the printer and you will never get the two sides to align 100%.  Heat stabilized transparency is a bit expensive (~$2 USD/sheet) but if you plan things out you can put both sides on one sheet.  I buy mine from Digikey (http://search.digikey.com/us/en/products/416-T/473-1038-ND/949480).

• Making an exposure 'master'

This was where I added a few tricks of my own, but am having flawless results now (really...zero throw aways).  First off, go buy 2 10x12" panes of glass at your local hardware store and book-end them on the narrow side with duct tape (sand the edges with regular sandpaper so you don't cut yourself).  You will sandwich your top transparency, photo-resist PCB board and bottom transparency in this for exposure to UV.  The 'sandwich' approach is key to flipping it over to expose the other side without moving anything.

• Exposure

I use a florescent tube, 6-8" away, 10 minutes per side.  There are 'kits' for this if you want...I bought one.

• Developing

I use positive photoresist boards that are pre-treated (~$7 USD per 100x150mm board http://www.circuitspecialists.com/gd114.html).  Once exposed, simply drop in the developer solution (http://www.circuitspecialists.com/418-500ml.html) and gently brush them for two minutes (turning occasionally).

• Etching

  I use Ammonium Persulfate (http://www.circuitspecialists.com/410-1kg.html) solution in an etching kit I bought from Circuit Specialists for ~$60 USD (http://www.circuitspecialists.com/et20.html).  8 minutes in the tank and you're done.

• Cleaning

Rub off the remaining photoresist using basic acetone (hardware store).

• Drilling

The trick here is a Dremel, Dremel Drill Press, a magnifying lamp and *quality* bits.  Don't use standard Dremel bits.  You will need tiny bits (for your vias) and these are ~$5-10 USD/each but are rated for ~3,000 PCB holes (http://www.soigeneris.com/PreciseBits_Carbide_Micro_Drills__Number-details.aspx).  I've drilled a dozen or so boards and am still on my first bit.
[/list]

Actually, now that I have a process, making the board is the fun part for me.  I no longer worry whether I will be wasting my time on a throw away.

-Mitch

PS If you decide to go the home PCB route, let me know.  There are more tricks I've learned, but this posting is getting a bit long-winded.

[Reply #10 on:]

no no keep going I want more!

[Reply #11 on:]

Ok...you asked for it!

This exceeds the maximum length of a posting so I split it into two parts.  This is part one.

• PCB Design

  The default setup in Eagle PC is designed for SMD and board houses.  For home builds you will need to make everything bigger (holes, pads, vias & traces).  This is easy to do in Eagle PC.  Just modify your design constraints for these parameters and the Eagle PC auto router will make everything bigger for you.  Now you have something you can work with.

At the design phase you can make your etchant last longer (i.e. etch more boards with a batch of etchant) by making sure you do a GND 'pour' with Orphans on.  This will fill all the blank spaces on your board with copper (either GND attached or unattached copper...orphans).  This means less copper to dissolve away, and your etchant lasts longer.

• Transfer Method - Printing

You need to make sure that the toner side on the top and bottom transparencies face each other.  This improves the quality of the traces, etc.  To do this, I print the the 'top' transparency in mirror mode (Eagle PC supports this).  Which side (top/bottom) you 'mirror' depends on what your printer thinks is 'up'.

Also, I discovered that some UV does pass through the toner during the exposure process.  This means that during etching you will remove the copper from the exposed portion of your board and thin the copper from the unexposed (printed) areas.  This thinning can be a problem.  Sometimes you can tear the thinned copper trace right off if you're not careful.  My solution is to use two 'top' sheets and two 'bottom' sheets of transparency, carefully aligned.  This doubles the amount of toner the UV has to pass through and produces a much nicer board (at the expense of extra sheets of heat sensitized transparency).

• Making the exposure 'Master' - Supplies

  Get yourself a set of those nerdy headband magnifying goggles.  This will make everything easier.  Pick up some white foam core board at your local craft store to use as a work surface (~$3 USD)  Pick up some double-sided 'carpet tape' at the local hardware store.  This is sticky on both sides with a waxy paper covering the sticky back side.  Get some masking tape.  Make sure your (foam core) workspace is well lit.

• Making the exposure 'Master'

Begin with your two 'top' sheets. Lay the first toner side down an secure the corners to the foam core with masking tape.  Add a strip of carpet tape to the top edge (don't cover your artwork) and leave the wax paper attached to the back of the carpet tape.  Now lay the second 'top' sheet over that and with your magnifying goggles in place, carefully align the artwork.  With one hand pressing down to maintain the alignment, remove the protective wax paper from the carpet tape with your free hand and carefully affix the top sheet to it, permanently attaching the two top sheets together, perfectly aligned.

Now repeat the above process with the two bottom sheets, toner side up this time, and with the carpet tape on the opposite edge.  You now have perfectly aligned double-layer top and bottom sheets.

Now tape the corners of the bottom sheets, toner side up, to the work surface and apply carpet tape to the opposite edge of the carpet tape holding the two bottom sheets in alignment.  Then lay the two aligned top sheets, toner side down, and carefully align the artwork.  Once you are aligned, press down with one hand to maintain the alignment and remove the wax paper backing from the carpet tape with your free hand and affix the top sheets to the bottom sheets.

You now have a perfectly aligned...and stable...master sheet to work with.  You will place your PC board between them later for exposure.

The final step is to attach the bottom sheets, with masking tape, to the bottom pane of the glass sandwich board you made earlier (see previous posting).  Don't attach the top sheets to the top pane.  That won't be necessary.

• Exposing the board

Peel off the UV protective film from the top and bottom faces of the photoresist PC board blank.  With the glass sandwich board laying open, place the PC board blank on the bottom sheet(s) of transparency, which have been taped to the bottom glass pane and align it so your artwork is centered on the board (this doesn't need to be precise).  Now close the top transparency over your board, make any final adjustments to align your artwork and close the top pane of glass.

You now have a very stable exposure 'sandwich' which you can lay in the sun, under a florescent tube, etc. for UV exposure and not worry about alignment issues (I promise).

The instructions that come with the photoresist boards I use say expose for 8-10 minutes, 6-8 inches from a florescent tube.  Since I double the top and bottom layer I roughly double that and expose for 15 minutes per side.  This works perfectly in my setup.

• Developing the board

NOTE: I do use rubber/latex gloves for developing and etching.  Once both sides of the board have been exposed to the UV, drop the board in a bath of developer (I use about 500ml in a small, resealable throw-away container).  Use a small foam paintbrush to delicately brush the board as you watch the board design slowly appear before your eyes.  I turn the board over every 30 seconds.  After 2 minutes, I remove the board from the developer bath and rinse under cold water.  You can now save your board for later if you want, but I etch immediately afterward.

When you are done, reseal the container and save the developer for your next spin of the board.

End of part one...[/list]

[Reply #12 on:]

Part 2

• Etching the board

  I bought a relatively cheap (~$60 USD) PCB etching tank online.  This comes with a tank, tank thermometer, tank heater, clips for dipping your board and a little aquarium pump that pumps air into the bottom of the tank, agitating the solution during etching.  Well worth the investment.

With the etchant powder mixed with water, in the tank an warmed to 50 degrees C, drop your board into the tank and turn on the bubbles.  At 50 degrees C, my boards are completely etched after 8 minutes.  After the exposed copper traces are completely gone (I use the magnifying goggles to verify), remove the board and rinse.

NOTE: If you use the tank I used, mix a full 2 liters of etchant at a time.  Otherwise you will pop (break) the glass around the tank heater due to the temperature gradient caused by the fact that the liquid only partially covers the heating element (like I did).

NOTE: 2 liters of etchant can handle multiple boards (depending on the amount of copper you dissolve off of each board).  I pour the etchant into a plastic container and save for next weekend.

• Cleanup

Once you've etched the board, the remaining photoresist needs to be removed.  I put the board in a small throw away container and pour some acetone over it (just a couple of tablespoons).  Then I rock the container back and forth to remove all the photoresist.  I finish by wiping with an acetone soaked paper towel.

• Drilling the board

This requires some investment.  I use a Dremel 4000 (~$75 USD) and a Dremel Drill Press (~$50 USD) and high quality carbide drill bits (~$5 USD/ea) and a magnifying florescent lamp (~$75 USD...Optional, the goggles just don't work as well for me here).  I also bought a 2x2' plywood plank to use as a build/work surface.

All of my holes are at least 0.8mm (nothing smaller).  Some parts require larger drill holes, so check your data sheets.

First, apply some strips of masking tape to the back of your board to prevent it from getting scratched up as you move your board around on the drill press.

Drilling takes a little practice.  The key is to start slowly. You will get faster after about 500-1000 holes drilled (...really).  Looking through the magnifying lamp, continue to adjust the board location as necessary as the bit approaches the pad/via hole.  Start slow.  I can drill my latest board, which requires 246 holes in ~40 minutes (I time everything).

I also ran a length of 3/4" clear plastic tubing from my shop-vac up over the accessory holder on the drill press and taped it to the head of the Dremel with duct tape so that the end of the tube is right next to the bit.  This will suck away debris as you go, alleviating you from having to stop to wipe away drillings every few holes.  With the vacum attachement I can dill my entire board in one pass.

• Building the board

I learned the hard way to do this incrementally and test as you go.  I start with my power supply components (including the obligatory power indicator LED).  Then I test that.  Then I add the Atmega board, crystal oscillator, etc. and power that up with a chip programmed with the BLINK sketch.  To support testing via the BLINK sketch I always wire digital pin 13 to a green LED/resistor.  This is a great way to ensure your Arduino sketch will work.  Then I continue, one system component at a time, testing as I go.

One thing that makes this phase easier is to avoid soldering to large copper areas, which dissipate the heat so quickly you often get cold solder joints.  You need to do this way back in the Design phase.  Eagle PC has features to help you with this (i.e. add 'thermal' spacing to vias that attach to GND pours, etc.)

Also, be aware that some of your components will cover the pads and prevent you from soldering on the top (component placement) side of the board.  For those components, you will need to prevent Eagle from attaching traces to the pads on the top side of the board.  You can you use rectangles and polygons in the 'trestrict' layer to automatically prevent Eagle from attaching traces to 'obscured' pads.

[/list]

Thats about it.  I know it sounds like a lot, but following these instructions has made my projects absolutely enjoyable (and affordable).

Remember, board houses are the way to go if you can.  But when you are developing your design, and haven't proven your board design yet, spinning boards at home is fast and cheaper.

-Mitch

[Reply #13 on:]

grinsalot
ta v much
I've copied this for offline study!

[Reply #14 on:]

Transfer Method
I use the laser printer -> transparency -> photo resist approach.  This works really well... if you use heat stabilized transparencies.  Off the shelf transparency paper warps in the printer and you will never get the two sides to align 100%.  Heat stabilized transparency is a bit expensive (~$2 USD/sheet) but if you plan things out you can put both sides on one sheet.  I buy mine from Digikey (http://search.digikey.com/us/en/products/416-T/473-1038-ND/949480).

I've had good results using an inkjet printer and coated transparencies. No warping because there's no heat. The transparencies cost a bit more than line ones used for laser printing. E.g from Amazon.