MYX Digital

MYX PCB makin' process

Dec 272011

Several people have asked about how I get my PCB boards burned with the results. For a long time I have promised that I would put up a tutorial about how to do it. So, I have an 8 hour drive ahead of me, so here you have it.

Having built a brazillion PCBs on perf board, I wanted something a little more custom. A few years ago, out of ‘necessity’, I decided to learn how to burn my own boards. I routed around online for several days, reading and watching many different methods of how to get the job done. I settled on Eagle Cad for the PCB design and layout. I will not go into how to use Eagle as there are already a number of good tutorials out there. Some of the best I found were this one and this one from Sparkfun. The first couple of boards I designed were slow going. As with all things, it got easier, and I got faster. What I found interesting is how designing on the screen has made clear things would not work on the physical breadboard. When you see the physical connectivity of everything, it just makes more sense.

For the actual boards, I tried a few different methods, but kept getting so-so results. I had seen the Pulsar FX website and read it front to back. For a product web site, there is an amazing amount of “How to” information on their site. I called and spoke with Frank (the owner) about his product. It turns out that he is a fellow tweaker and really cool guy. While I called to talk about his product, I had a great time talking to him about all sorts of geeky things. That is actually what sealed the deal. I bought the laminator a package of the transfer paper and some of the green ‘foil’.

Having done the magazine thing with an iron, you don’t always walk away with good results. The special paper you buy from Pulsar is not a gimmick. If you follow the directions and use the right toner it works very well. I would not have thought that toner would have made that big of difference, but it did. I had some cheap generic toner in my printer and it fell apart. The second I used true, namebrand toner, the whole game changed. My lines were solid and crisp. It was at that point that I started bringing my trace sizes down. While the product says I can get down to 6 mil (.006 inch), I stayed at a minimum of 10 mil.

Before I start to prepare the toner paper, I get the laminator plugged in and turned on. You want it fully hot when you transfer the toner to the board. You will also want to prep your board here as well. I cut my boards using an old paper cutter. After cutting the boards, I sand the edges using a fine grain sand paper as they tend to be a little sharp. I like the look of rounded edges on PCBs so I sand the edges round as well. This also helps prevent holes when etching (more on this later).

Ok, time to get down to business. While the following is more on how to produce a 2 sided PCB, the same concepts can be used for making single sided boards. I export the PCBs out of Eagle at 300 dpi. There should be 3 or 4 files (Top, Bottom, Front Silk, Bottom Silk). In this case I have 3. I use Photoshop to process my boards. I lay out all 3 files on one page. Eagle sends out a positive image of the board, so I invert the black and white. Any boards using the top must be horizontally flipped so it appears properly when it is etched onto the board. Once everything is set, I make a print to serve as a template for the toner transfer paper.

I cut out 3 pieces of the toner transfer paper (TTP). I cut about a 1/4 inch extra on all sides to leave room for a little play in where the printer prints as well as the possibility of not placing the paper exactly centered. I use a light stick painters tape and tape the TTP over the print on the pre-printed page. I position the page on the manual feed on the printer and print again. When it comes out, the toner is now printed on the TTP (sorry… duh right?). I carefully pull off the painters tape. It is important that you pull carefully so the paper does not rip, and if it does (which sometimes happens), it does not rip into the print.

The next step is the moment that I dread the most. This is one of the steps that will either make or break the PCB. It probably does not need to be said, but alignment of the top and the bottom holes of a PCB is critical. I align the top and bottom by facing the prints towards each other. I use a wicked bright 3 watt LED headlamp and shine it through both layers of the TTP. I gently move the top around until I see a good portion of the PCB line up. I then zero in on the right hand side of the paper. Once it is about as close as one can get I squeeze with my right hand and then I move in the left side. Once everything seems to be all lined up, I use a piece of the painters tape and lock the 2 sides together to make a clam shell kind of shape (see the picture below).

Before I commit the design to the copper, I clean the copper completely with a green scrubby pad. As you scrub it, you can see the copper get shiny. I do not (and recommend that you do not) use soap that uses oil in it’s ingredients for grease break up (like Dawn). You want the board completely free of oils so the toner will stick. At this point I fill a plate with warm water in preparation for the toner’d board.

I place the board between the 2 sheets of TTP and make sure that the dimensions of the board are inside the area of the copper. I run it through the laminator 3 or 4 times flipping it over each time. I also move the board to a different position on the rollers so I get the maximum heat transfer per pass. I set the board and paper in the water.This is where the PulsarFX stuff rocks. I usually run my finger over the whole board to make sure it takes the water. I leave it for about 2 minutes, then I check it. The board will freely move when it has released from the paper so there is no question about when it is done. If the board moves it really moves too. It becomes slick on the paper. There is no scrubbing necessary, it just comes off clean.

If you are using the green foil, you would add it at this time. The foil fills in any pits or holes that the toner missed (within a certain amount). I do not have a picture of the green foil in this set as I was out of it. This is added to the board by placing it over the toner and running it through the laminator again. Anywhere the toner is, it sticks.

I really like one of the methods of etching the board found on the Pulsar site. The idea is to etch the board in about an ounce of Ferric Chloride inside a plastic ziplock bag. You then repeatedly run your finger over it to agitate the surface. This direct contact results in a really fast burn, which does a couple of things. It insures that no thin traces are over burned, resulting in broken traces. Also, this uses far less FC fluid (i.e. less waste). When I am done etching and cleaning the board, I throw the paper towels into the remaining solution, seal the bag, and toss it in the trash.

While swiping the surfaces of the board you will see the edges of the copper surface start to fade. Occasionally you will want to look through the board to check the condition of both sides. You want it as clear of any unwanted copper as possible. Again, being that this is such a quick process (3-5 minutes) you have plenty of time to make sure the board is clean. If you still see little remnants of copper, take the time to rework that area of the board in the etchant solution. Once the board is free of excess copper, I pull it out and clean it thoroughly. You do not want any of that fluid on you, or your clothes.

Using the green scrubby pad, scrub the board to get the toner and green foil off the board. You can use acetone to speed the process up a bit and make the job a little easier on your arms. The only drawback to using the acetone is that it melts the toner and the foil which colors the board a bit greenish black. This is not a really a problem, it’s more of a cosmetic thing.

Next up is the drilling of the board. PCBs have little tiny holes and as you may expect, need little tiny drill bits to drill them. I get my bits from Harbor freight as you can occasionally get them on sale. Again, there are many methods to drilling. What I have found to be the easiest is to use my drill press. The problem is your eyes crossing when you are trying to line up the drill bit to the holes. I designed a little magnetic board with 4 white LEDs on it to shine through the hole, and through the board which makes lining up the bit a heck of a lot easier. I keep a 12 v battery on my workbench strictly for this purpose. If the alignment of the top and bottom is the most dreaded part, drilling is probably the second. There are many opportunities to screw up your board during drilling. This is one area where you really want to keep your head straight and stay focused. It is a somewhat long and monotonous process and the holes are small which is a bad combination. I usually keep about a 10 mil of space between the drill tip and the board so the travel to board is at a minimum. While you will want to go fast to get the job done, I have found this to be the key to unsavory holes and broken bits.

Convention Massivity

Photography, Video No Responses »

Jul 142011

Yeah, I know massivity is not a real word… just be ok with it.

Every 2 years the company I work for holds a rather large convention. I am not talking about a hotel ballroom, nice dinner, and a DJ. I talking about a full on, gigantical, colossical, massivity of a convention. We quite literally took over the Georgia Dome for a little over a week. A massive spectacle with concert sound, lighting, 50,000+ crazy attendees.

My job… shoot it. I shot brazillion pictures and hours of footage which was initially supposed to be edited into a doc. But at the eleventh hour as with most projects, things changed. They now wanted a upbeat rockin’ music video. I had shot everything smooth and slow. Oh well… But it was still a fun piece though. As far as pictures go, there were too many things to shoot. Everywhere you look there was another something interesting. As I have said in the past, I am a sucker for blinky things and this was the granddaddy of blinky things.

“Big Decisions” Convention Promo

Video No Responses »

Apr 202011

Here is a piece I did a few weeks back for the upcoming convention.

Freedom Promo

Video No Responses »

Mar 142011

I had a pile of footage that had many great bites that were not getting used in several other projects I was working on. I took some time and pulled this one together.

Pinewood 2011 – The Corona Wire

Electronics, Pinewood Derby No Responses »

Feb 222011

As I have said more than once, I was an 80′s kid. As you know, Tron Legacy came out. While I was a little disappointed in the story, I was totally in love with the art. It was beautifully done with so much attention to the little details. If they paid as much attention to the story, it would have totally rocked… but I digress… I wanted to make this years pinewood derby car in the styling of the new movie.

I decided to take a different approach to the building of my car. Instead of starting from a block and working down, I started by sawing the block down to a thin slab and adding to it. Using thin pieces of wood, I carved each piece of the car with the coping saw and / or razor knife. The caliper helped a lot. The wood is soft enough that I could mark the wood easily. I used super glue to keep the weight down. Then I used wood filler to fill in the the cracks between the pieces.

The overall design is something between an F-16 with no wings and a Comaro. The jet intake, rear, hood grill, and the front grill were from an old set of computer speakers. They were of course rear lit as well. The hood was to have plexiglass inbedded in it, but I could not get the fit to not look chunky so the idea was scrapped for the metal.

In the past I have used screws to hold little things like this together. This year I wanted to make it easier to access the guts. I used a little neodymium magnets to hold the top onto the bottom of the car. The only thing I do not like is the bump in the middle of the top piece. There was supposed to be a rear spoiler, but I did not have time to built up the back end to add it.

I thought through many different ways to achieve the glowing linage. I bought and experimented with everything from science grade glow in the dark paint, back lit plexi, UV reactive paint with UV LEDs, and eventually settled on EL wire. It is what was used in the movie for the costumes. It was the best look for the size. I had to come up with a way to fit the inverter in the car, be able to turn it on and off, and most importantly, how to power it. I opened the case that the inverter came in and hacked the board so I could move the batteries and switch to the middle of the car. For weight and size reasons I chose to use a small LiPo battery. The last thing I added was 0805 SMD UV LEDs for ground effects and head lights. The effect was very slick. Another nifty (and unintended) effect was that the inverter has a high pitched whine to it. In addition to looking very electric, it also sounded very electric.

Triumph and agony…
Sometimes when you work on things for too long, you loose you mind. This can be a dangerous thing if not to yourself, then to the object being worked on. I spent a lot of time priming and painting the car so it had a near ‘real car’ paint job. I mean, I spent a stupid amount of time painting, sanding, painting, sanding… So then it comes time to put the wheels on. If you have ever built a pinewood derby car, you know that this is the last step and the time that most cars get damaged. Well, this was no different. It was like 3 am and I had to finish the thing. I put the front wheels on first and they went on without issue. The third wheel went on without issue. On the 4th wheel, as I was tapping the nail in, I heard ‘CRACK’. Knowing what had just happened, I put my head down on the workbench and let out a big sigh. After about 30 seconds or so, I decided to look at what the damage was. The top of the car had caved in on itself. This was not something that could be repaired easily, or quickly. I had to get up for work in a few hours and it needed to be turned in right after work. There was no time. I chose to get it at least track worthy. I glued the heck out of the broken area. To add insult to injury, when I picked up the car to look the damage closer and the car fell out of my hands and landed beak down. While it did not break, it added another nice little ding to the killer paint job. There is a lesson in here somewhere… I am not sure what it is… but it’s there.

Weather: Part 1

Arduino, Weather, Wind No Responses »

Dec 122010

I have been a fan of weather and storm watching since I was a little kid. It really all started one night when I was in bed in the midst of a wild thunderstorm. I was awake and frightened and thought everyone else was asleep. I heard a noise, and as kids do when they can’t sleep, I went in search of what I was hearing. It was my grandmother. She was standing by the sliding glass window watching out across the lake. I went and stood next to her. I told her that the storm was scaring me. I asked if it was scaring her. She said no. She explained how she loved to watch the storms. We sat there together not really saying a whole lot, just watching the storm. Occasionally we would comment about the lightning or thunder hits. I forgot to be scared. It turned out that I wasn’t. I was amazed.

I have been in many storms since. I have been closer to tornadoes that I would have liked. But all in all, I am still fascinated by the storms. Since I started learning about the mircocontrollers, one of the earliest ideas I had was that I could somehow use one to measure the weather. Early on I did not know how to go about it. But as I have been exploring new areas of technology, as well as learning to build, building, and crafting new things I am starting to understand more and more what can go together. It is somewhat freeing actually.

So, weather. Where to begin. Starting with my most basic needs, I need to know how fast the wind is going and from what direction. I decided that I wanted to build an anemometer. There are several folks on the web who have built them, but true to form, I did not see one that sort of suited me. (What can I say, I like making my own stuff). So, I started to play with different ideas. I still had several skateboard wheel bearings from the windmill, but I have found that those will rust when exposed directly to the elements. I could use them, but they would need to be shielded. I wanted to integrate electronics so I could measure the speed. I wanted it to be cheap. I wanted it to be repeatable in case I wanted to do it again.

PVC is a great, low cost, experimental building material. It can be cut, shaped, sanded, and painted and put together in countless ways. It’s like Legos for Adults. The way I decided to approach it was to have a cap suspended on top of a smaller cap. The outer cap would need to freely rotate, yet stay connected to the inner cap. An issue I ran into was how to drill a hole in the exact middle of the pvc cap. I have no good scientific answer. I used a ruler and marked lines across the dome. I kept doing this from many angles till one spot showed it’s self as the center. I used a 1/4 2 inch brass bolt. I used brass as this is what they use in toilets and figured it would be outside.

The bolt was put through the end of the cap and nut tightened in place. Before I get too much farther, I should mention that I fit everything together to make sure it all worked then went back and epoxied all the non moving bits. I drilled a hole in the middle of the smaller cap and widened the hole until the ball bearings fit snugly inside. I put the outer cap over the inner cap and added another nut to the inside of the smaller cap to hold the two caps together. The 2 nuts sit directly on the inner rim and not the sleeve of the bearing. Being that the outer rim is firmly attached to the smaller cap, the inner rim spins freely. BTW, something that I did not take into consideration was how to hold the nut as I was tightening it. There is no room for fingers in that small of a space. Needle nose pliers helped out here, but it still was not easy. If you are asking why, remember that the tighter that the nut gets, the further down the large cap gets, which means you have nothing to grip onto after a while because the outer rim spins.

The next issue I needed to figure out was the scoops. I have seen all sorts of ideas ranging from as simple as easter egg cups to folks who have custom machined their own. I wanted something bigger than easter egg shells and far less complex than machining. I could use a makerbot and make whatever shape I wanted, if I had one (Man oh man, I want a makerbot). One day when trolling the dollar store (a good source for budget makers) I saw a huge display of big plastic spoons. After being an ass and asking how much they cost, I bought 4 of em’. I bought 3 for the build and one to goof up. Not long later, I had the handles removed and ready to attach.

I used super glue at first, but it really did not work well. Epoxy eventually was the right solution. But how does one hold a salad spoon to a round spinable object until it hardens in place? You get comfortable because you are not going any place for a while. With all the goofy angles, there was not a good way to clamp it. Fortunately is was 5 min. epoxy.

For the electrical part of this, I took apart a relay I had in my kit o goodies. If you gently pull on one of the ends of this variety, the glass reeded vial will come out fairly easily. I soldered wires to the leads and covered them in heat shrink to keep the water out. I epoxied the reed to a groove I made on the outside of the inside cap. (clear as mud?) I drilled a hole in the side of the bigger cap just big enough to push a little magnet into. The magnet trips the reed which gives you your pulse for your uC (microcontroller).

The wind vane was dome somewhat similar. But, to make the assembly a little easier (which occurred to me after putting together the anemometer, I bolted in reverse this time. I had the bolt come out of the top of the big cap. Something I did not realize when I started on the arrowish part of the vane was that the 2 sides had to be of equal weight. Who knew. I cut it all out and epoxied it to the cap. It was locked in and when I went to test it, it sort of lazily flopped around, but did not really head into the wind as I had expected. I am writing this some time afterwards and seriously have no idea how I solved this one, but I found that balance was the key. I some metal bits, but it was not enough. I started looking for small, really heavy stuff so I could balance the thing. I remembered the fishing weights we had used for the pinewood derby cars. I cut a slit down the middle of a large weight and epoxied it in place. The vane came to live. While it is ugly as hell, it effortlessly moves about when even the slightest wind is present.