Monthly Archives: April 2013
That is a question I’ve been contemplating about for the last few days. Having produced a first functioning prototype is quite encouraging! The question is now what to do with that success.
While there have been some people that have shown interest in buying one, currently the number possible orders does not exceed 20. That on the other hand would not justify having 50+ boards manufactured as that would include having to lay out about $2000 in advance. We have been in contact with a manufacturer in Germany (where the co-host of this blog is located) , specialized in manufacturing small series. This by the way is not a garage shop but a company that has been doing this for 20+ years and they’d be providing us with a complete turnkey solution. We send them the layout and money and they send us back completed boards. However, that only makes sense if the number of boards is larger than 50 for the first batch and would also really only make sense if there would be several batches of 50+ boards after that.
We could investigate to find a less costly alternative, however, the reduction in cost would have to be rather significant 30%-50% to really make a difference. We have a costed BOM and the price of all the components assuming Newark as the source of supply is about $27 for a qty of 50 boards. That does not leave much room for the labor to actually build the board.
My current thinking is to set up a fund raiser at Tindie and then post on a few forums to determine if there is enough interest to justify having 50+ boards manufactured. Another option would be InMojo. They are also offering assembly and serve as a sales platform for open source hardware.
Meanwhile, as I’ve mentioned above, my early success is really encouraging. Should there not be enough interest I can imagine making these myself depending on what QTY is involved. Making the first prototype was my first venture into SMD and Solder Paste and Reflow Soldering in a Toaster Oven. I started around 6:00PM in the evening getting all the materials ready, building a makeshift stenciling fixture etc. I was done with testing the prototype and had written the blog post by 11:00 PM. I believe it took me a good 120 minutes to populate the board. I had not made an assembly plan and I was doing it on my computer desk going back and forth between the layout and schematic in Eagle to see where the component went and and then I had to use the BOM with the Newark part number and find the bag/reel/tape with the component, and get them out of the packaging to be finally be able to place the thing on the board.
With some better preparation and a little hardware I believe I should be able to get it to well under 30 minutes per board. I have ordered several of these and several of these and with some intelligent, labeling and an assembly plan things should progress much faster.
I have sets for 4 more prototype boards and will see how quickly these can be assembled with better planning within the next week or so.
Once that is completed I intend to send one or more to my partner-in-crime in Germany to do some testing under load. I don’t have enough LEDs to test the thermal side of things and he has managed to burn out one shield already. This should tell us how many LEDs the shield really can sustain! I only use one RGB LED @700mA per shield in my own lighting projects (trippylighting.com) and none of the thermal considerations are of any concern 😉
You can read about it and look at a finished board, however, until you try to pick up these dust-like 0402 capacitors or 0603 resistors with a tweezer and try to place these precisely on a pair of solder pads you really don’t know what you are dealing with.
I started with the smallest components first and about halfway through populating the board I had serious doubts this board would ever work! Nevertheless I decided to continue to at least see if how reflow soldering in the toaster oven would work. While this is certainly not my first electronics project this is my first attempt at a more advanced SMD board and reflowing with a toaster oven was also a first for me.
And again, I’ve read in many places before that the components don’t have to be placed absolutely perfect and the reflow solder process is somewhat forgiving and surface tension will correct some mistakes. There are a number of videos available online that show this, but it’s still thrilling to see it actually happen and have the board come out looking very nicely reflowed.
It is even more thrilling to stack the thing on top of an Arduino connect it to an RGB LED and have it going through a color changing routine immediately. Well…almost. I had placed the diode in the on-board power supply in reverse, but that was quickly fixed with a trusty soldering iron. Anyway here is an image of the first functioning prototype still stacked on top of the Arduino and hot, right out of the oven, so to speak 😉