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Topic: Li-poly powered 2.6W LED road flares :) -homemade PCB and pictures (Read 1 time) previous topic - next topic


Nov 25, 2013, 05:19 am Last Edit: Nov 25, 2013, 06:25 am by megaBlocks Reason: 1
I have been acquiring the parts and tools required to make my own PCBs and i though i would share a little success ive had recently. this weekend I threw together this PCB with eight by 0.33Watt Amber LEDs:

Li-poly Powered 2.64Watt LED Road Flare!!
Aka: Arduflare V1.0

this is the first pattern I've programmed on it so its very simple and none of the PWM registers are even set, but yes it really is that bright! I know because I was blinding my neighbors with it earlier this evening showing it off  ]:D
Also there is a button for mode selections in future updates.


as you see here i have some laser printed artwork of the PCB printed onto a piece of Press-and-Peel Blue transfer paper, which the toner is face down and contacting the copper clad.
for initial alignment i use a little Kapton tape to hold the corners and keeps things straight. but this must be removed after the first press or the corners of your transfer will suffer!

Heat Press:

Here i do about three presses at roughly 260°F for 45 seconds making sure to rotate the board 90° each time i open the clam.

this is then followed by i heavy inspection and sometimes (more often than not) i will need to hit areas with an iron's tip and then re-press to get everything to stick.

Transfer Paper Removal:

at this stage i do a full visual inspection under a microscope of both the transfer and the negative for flaws and missing transfer (in these images there was no missing transfer however i suspect dust particles to be the culprit of all the blemishes I touched up with a sharpie marker and you can see as black spots.. a HEPA airflow system over the printer and the heat press should help significantly!


once all blemishes are fixed its time to dissolve all that copper in some Iron(III) chloride solution.
i use a small soft acid brush to both remove micro bubbles that cling to the surface of the copper clad when it is submerged and to directly wipe off accumulation of dissolved copper between traces and small gaps so as to expose fresh layers. also i use a Pyrex dish with a sealed top so as not to spill any acid and also i can swish it around quickly. I like to tape off any areas that don't require etching so i can save on some of the chemistry in the Iron(III) chloride solution.


all unwanted copper has dissolved and the board looks ready for drilling, some people get the urge to wipe off the resist mask at this point but i insist that leaving it on will not only save you time, protect the copper surface and make drilling easier. but it also feels a bit more gratifying to save the reveal for last!!


I know the board in the image is not the same as above, but i forgot to take pictures at this stage, and im sure you get the point.. though that is a dremel drill press and some solid carbide mirco drills.
when i did these boards i put some siliconized parchment paper under the board to allow it to smoothly slide around, this assists in allowing the board to self adjust as the drill bit centers its self within the copper "ring" that its drilling through (and once you get the feel down, it almost feels like the board self aligns to the drill bit once you've hit the hole)


after letting an acetone soaked paper towel cover the resist mask for about 15-30 seconds it should just wipe right off. and after a brushing with some 0000 steel wool and a wipe down with some IPA alcohol a nice polished surface of copper will emerge in the shape of the design that was just rendered to the laser printer a few minutes ago!!


And finally after dispensing solder paste on each pad and going through the reflow oven this is what the finished board looks like :D

I have also made an Arduino controlled hybrid convection/radiation reflow oven and an Arduino controlled piston driven solder paste dispenser that i will hopefully post on here soon.

Hope you've enjoyed!!


Reserved for beam shot pictures and updates to the design or program :P


looks good, very well done :) I have used press and peel before - nightmare to get it to stick without it getting too hot sometimes

Thanks for sharing

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