Button fall apart.. Whipped up a quick little batch of 2 part epoxy to set this switch on a piece of acrylic. Checking to see if it was set, it basically totally fell apart. I was planning on taking a peek inside the housing anyway, so it wasn’t a total waste of time.
Every Maker Faire we have been to has had a ‘Learn to Solder For A Dollar’ tent. This, Montreal’s first Mini Maker Faire, we teaching people how to solder for a dollar.
Here is a sneak preview of the ‘learn to solder’ kit we have put together. It is a badge that you can clip to your clothing or backpack.
Two 10mm red LEDs flash in an alternating pattern, using a simple resistor – capacitor circuit with 2 transistors.
The PCB attaches to a piece of laser cut & etched acrylic. The red light from the LEDs shines up and makes the acrylic glow. Making the badge pretty cool to look at, and a lot of fun to build.
If you are interested in learning a new skill, for not much money, come see us. If you already know how to solder, well you are welcome to come and check it out too. The most fun that can be had for $1.
Interested in having a custom pack of 25+ made for your Hackerspace, educational institution, or group? We will laser cut & etch your name & logo, and send them along with the electronics in kit form.
Through-Hole soldering is fast, fun and easy. The parts you populate your PCB’s with are the very same ones you can pull from your breadboard once your project is finished, and you are ready to make a permanent version.
What if the components end up taking up too much space for the size of your product? What if the components you need to use are only available as SMD parts, and you were using break-out-boards for them while prototyping?
In this quick tutorial, I will show you how easy it is to make a ‘Mylar’ stencil, that you can use for short runs. It will cleanly and easily apply solder paste to a PCB with surface mount parts (SMT). Mylar isn’t the best material for making a solder paste stencil, but it is really cheap and you can find it almost everywhere, and heck, it does an OK job.
Here is a quick demo video that shows what it looks like when you are reflowing solder paste. As soon as we received our first few boards for our Solder : Time II watch, we wanted to figure out a quick way to paste up a PCB. Our steel stencil took a few days to arrive, we wanted to try out these new PCBs right away.
We used a ‘Mylar’ stencil to put solder paste on this board. Notice how the components ‘self-center’ themselves. The surface tension of the liquified solder paste automatically centers each component, provided they are more or less properly aligned.
We will be using EagleCAD and Illustrator with a 45 Watt Epilog Laser Cutter. The techniques should be the similar if you are using other software. If you have access to a different laser cutter at your local hacker space, tech-shop etc, you may have to fiddle with the power setting we suggest to get them right for your machine.
Step One: Creating an .eps from EagleCAD
Click On Cam (Film Strips Highlighted in Photo)
Click on CAM (Highlighted in photo)
This will bring you to the next screen (below) and Step Two.
Step Two: Outputting from EagleCAD
With this window up in EagleCAD, you need to do the following.
A. Device [Set to PS]
B. Scale [Make sure that it is 1]
C. File [Type the name of your file, and end it with ".eps"]
Be sure that only the layer 31 tCream is selected. (Deselect all of the other layers)
Click the button [Process Job].
In your project file directory of your Eagle schematic and board files you will find the .eps file that EagleCAD created, and this is the file you will be opening in Illustrator.
Step Three: Adjustments in your Illustration Software
Open the saved “.eps” file in Illustrator. We have found that stencils for components that have really fine pitched pads, need a little bit of tweaking before sending the file to the laser cutter. It’s not that there is a problem with the file but rather the way the laser cutter burns through the mylar. Leaving the edges “microscopically” burnt so some resolution is lost. This can be a problem with fine pitch parts.
Our experience has been that decreasing the width of each pad by 20% makes the spacing between the laser created holes larger, leaving a slightly thicker piece of Mylar between pads, increasing the durability of the stencil, as well as limiting the amount of solder paste that gets applied. Solder paste can be used very sparingly, while still having more than enough to make a solid solder joint. Keep in mind that too much solder paste can turn into a ‘jumper’ situation after the board has been reflowed.
Ungroup the pads, select one of them, and make a copy at 80% width. Repeat. The new pads will be 20% less wide than the original. In experiments that we have done, these thinner pads make the super thin strip of mylar between pads thicker and still allows plenty of solder paste through to make a great solder joint.
Here, in our example the thinner pads are shown in grey, over the original sized black pads. We then erase the original black pads, leaving only the grey ones.
Components on your PCB like resistors, caps, SOIC parts and other ICs that have thicker, and less fine pitch legs don’t necessarily need this same treatment. There is a sweet-spot for the thickness of laser beam kerf, and really fine pitched components. You can get away with a great deal more, when dealing with larger & wider spaced pads.
Step Four : Preparing for Laser Etching
When you’re using a Laser Cutter, there are two ways to make holes in things. You can vector cut, and etch. If the medium you want to cut holes in is thin enough, you can get a much more detailed & precise hole by etching right through, rather than cutting holes in a ‘band saw’ type of way.
Select all of the pads in your illustration, open the Rasterize menu, and convert your vector art into a rasterized image at 1200 ppi.
Draw a box around your PCB. The larger the better, you are going to want a large surface area around your components to accomodate the edges of your squeegee. The larger surface area also gives a larger area for contact with the tape that is holding your stencil solid in place.
The settings that we have uncovered as perfect for our 45 Watt Epilog Helix is as above.
1200 DPI, 40% Speed, 25% Power.
Tape your mylar sheet to a backing sheet of regular paper. And hold everything in place inside the Laser machine with masking tape. If you have a strong enough air exhaust, it can flutter paper sheets, if they aren’t secured.
Step Five : Pressing GO
Here the rastering mode of the laser, is actually printing all the way through the the Mylar sheet, making really precise holes that will act as a stencil to allow just enough solder paste through onto the PCB.
For the purpose of this tutorial, I went with a small cutout. If I was using this stencil for an acutal PCB, it would be about 5x larger.
Notice the amount of remaining Mylar between the pad holes. Any less, and the squeegee would wear it out prematurely.
Step Six : Test Stenciling Solder Paste
Macro closeup of the stencil aligned onto the PCB. We use Kapton tape to hold the stencil into a jig made up of same thickness scrap PCBs. The more time you spend precisely aligning your stencil, and taping it down firmly, the fewer boards you will need to re-do.
We hope you’ve found this tutorial informative. Surely if you’ve done this on your own, you may have other tips and techniques that we have not included. We would love to hear about successes and failures of your own experimentation. Please add them in the comments!
For small jobs, mylar sheets are good, but the Mylar wears out, gets solder paste around to the backside, and needs to be replaced frequently.
After you have tested your PCBs, with this method, and have a few functional units work to your liking, you may want to think about getting a stainless steel stencil made. There is a big difference between the mylar and stainless steel. The $0.50 worth of Mylar sheet helps you find out ahead of time that the $100 + you’re going to spend on the steel stencil is not a waste of money.
After the incredible success of the Solder : Time, we compiled the majority of what was on people’s wish lists for the next version of our Solder : Time Watch.
After a great deal of brainstorming, component sourcing, code-wrangling, and laser cut prototyping, we unveiled the Solder : Time II at MakerFaire Bay Area 2012.
• Solder : Time II’s microcontroller is the ATmega328. Use the Arduino IDE to hack / reprogram
•Display is 4 x (5 by 7) matrix LED modules
•Two button interface
•Displays text / time / numbers / graphics etc…
•Create graphics animations & Scrolling text
•Standard .1″ spaced FTDI header for easy reprogramming
•ATmega serial port open & available – attach accessories
•Low power sleep mode
We had a lot of fun building this new watch, and made it as hack-able as possible. Available as a KIT, solder the through hole parts and assemble the watch body on your own. (SMD parts come pre-mounted / tested and programed). Don’t feel like soldering? The Solder : Time II is also available fully assembled — ready to wear & hack –
We just got them in store, and they are the the most slick proto-boards we have ever seen. I can’t decide to build a project on one, or hang it on the wall as art. We have them as the ‘Superpack’ (3 of each size) as well as single size 3 packs.
While building prototypes the need to cut an existing PCBs or generic prototyping PCBs to fit your project will come up once in a while.
What I normally do is score the PCB with a box cutting knife or hack saw the board into the shape I need. Both of these techniques end up making a bunch of PCB dust, and everyone says that it’s bad for you.
Today I needed to make a programming header but all of the prototyping PCBs on hand were too large and I didn’t have my hack saw or box cutter. But, I did have a paper guillotine. So I thought why not give that a try?
The results were amazing! The guillotine cut the PCB quite easily, and there was almost no PCB dust at all. This could dull the blade, but with no dust, it’s worth possibly needing to change the blade every so often.
In the tests that I did, I cut along a set of holes. Thats why you hear the “thud” “thud” “thud” … in the video.
Oftentimes we get approached to help with a project, and sometimes we are given the mandate to ‘Make Something Awesome’. Here is one of those times.
For CBC’s game show “Canada’s Smartest Person” we were contracted to create an on-set prop that is actually a functioning music guessing device. The purpose of this, is to test ones musical memory, and seeing how well they can play back a set of notes, adding each note to the set for a given number of total notes.
We used the Arduino, and our Shield Dock to prototype the 2 boxes for the production. Using our laser cutter, we crafted the housings, and arcade style buttons to take the abuse that an excited game show contestant will be throwing at it.
The notes coming out are triggered by a MIDI signal. We set the baud rate of the the serial on the arduino to 31200. Soldered on a MIDI jack, and with that, you can hook it to an iPad, Mac running Garageband, any computer running a software synth, or a real hardware synth.
The two semi-translucent panels are back-lit with a set of bright 10mm LEDS. (The same ones used in our Dice Kit). Each panel has an array of six LEDs, controlled by a MOSFET, pushing the brightness to the safest maximum.
I was working on an Arduino style project the other day and needed just a couple of more pins. I really didn’t want to add any extra circuitry to the project so I looked at the Atmega328 and wondered how I could get more pins out of it. Then it dawned on me, simply remove the crystal and associated capacitors and use the internal RC clock rather than the external crystal. To try this out, I built one of our new Minuino Kits and omitted the crystal and 22pf capacitors.
In order to do this, I had to change some fuse bits on the ATmega, telling it which clock source to use.
Here is a screen shot of the only setting I changed using the AVR studio software; I chose Int RC Osc. 8 mhz.
Then to finish up, using my MKII programmer, I loaded a new bootloader onto the ATmega. Here I chose the Arduino Pro 8mhz 3.3volts (BTW, I have been running the board at 5+ volts) for both the bootloader and the IO board style when uploading sketches.
Here is the example sketch the blinks two LEDs connected in place of the crystal: