How to Go Postal

How to make your own PCB on free postal labels using conductive ink, epoxy and a few parts. By PCB I mean, Post-Circuit Board: as in enter the age of circuits painted on walls. And also because its on postage. Neither snow nor rain nor heat nor law nor gloom of night stays these couriers from the swift completion of their self-appointed rounds. Lets all Go Postal.

Another old project out of the dust bin of 2006 from the Graffiti Research Lab and The Eyebeam OpenLab.

Confront your fear of the hi-res video by clicking here.



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The essential ways and means to build a PCB:

1. a USPS Priority Mail postal label
2. a multimeter
3. 5-minute epoxy
4. conductive epoxy
5. conductive paint or ink
6. fine tip paint brush
7. copper tape
8. Whatever specific electronic components you need for your circuit.

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This instructable will detail one way to put a blinking LED circuit on postage, fabric, wood and other surfaces. But there's a lot of potential for what could be made using these materials and techniques and a world of simple circuits in textbooks and on the internet to try out. The conductive paint and ink will add resistance so you may need to experiment and tweak component values to get the effect you want. We've included some images and video of other examples including a traffic lite sticker and an homeage to Above created by Fred Zyda in the guerilla studios @ SIGGRAPH that uses timer and decadal counter ICs.



These are the parts we use to create a 555 timer-based flashing LED circuit:

1. 47k resistor (R1)
2. 100k resistor (R2)
3. 400 Ohm resistor (R3)
4. 10uf capacitor (C1)
6. 2 3 Volt DC CR2032 or better lithium batteries
7. 10mm 3 volt, 30mA LED (of any color)
8. 555NE timer IC Chip

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Once you've tested your circuit, you can lay it out on the surface of your choice. You can trace the sticker design attached in this step to create the 555 timer circuit that will blink an LED or two. More complicated circuits will require multiple layers. Leave ~ 0.25 inches for each trace. I make small circular contact pads at locations where electronic components will contact the ink traces.

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Use a paint brush and conductive paint or ink to create the traces. It may require multiple coats. Allow the paint or ink to dry and use a multimeter to test for continuity on each of the traces.

This tutorial is multimeter 101 for those who need it. For PCBs all you need to know is how to use continuity mode.

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Now you can add your components. This happens in three steps:

1. Placement
Position the component so that it lays flat, or upright or on "it's back". Determine the position that is most stable for that given package or form factor. Bend the leads so that they touch your conductive contact pads or traces. Don't worry about cutting the excess lead yet.

2. Epoxy
Epoxy the component body to the postal label. Make sure to not get epoxy on the component leads or the traces as it will act as an insulator.

3. Bend and Clip
Once the epoxy has dried (in about 15 minutes) you can bend the leads so that they follow the traces and make contact exactly where you want them. Just clip off any excess.

4. Hook it Up
Now you can do two things. You can put a thick layer (glob) of conductive paint or ink on the area where the component leads make contact with the traces. This is the quick and dirty way. It is less stable but who are we kidding -- we're making a circuit on postage. You can also use conductive epoxy. The connection will be very strong, but it will require at least 6 hours drying time.

Check the photos for more details on attaching the hardware.

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Depending on your circuit, you may be able to use a single battery. For the LED flasher circuit, I am using a 555 time that operates within a range of 3 - 15 volts DC. One 3 volt battery won't give you much operating life. So I make a six volt battery by using conductive epoxy or conductive tape to create a battery sandwhich that operates in parallel to give me a six volt bus. You can also use conductive velcro. When paper batteries become more common this will be less clunky.

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Now you can attach the battery to the circuit. There are a number of ways to do this as well:

You can epoxy (conductive) the negative terminal to the negative trace on the postal label and run copper tape from the positive terminal of the battery to the positive traces. You can substitute the conductive epoxy with a loop of copper tape for a shorter term solution. You can add a dab of 5-minute epoxy to the battery to secure it in place. Conductive velcro is another method. It requires more fabrication time but allows you to change batteries in situ without destroying the traces by ripping up the conductive epoxy.

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Stick it real good...wall not included.

If you want to see some smart sticker placement check out Thundercut.
Mail this label to a city council member and win a free trip to Gitmo.

-v^vv^-

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