The Great Big Guide to Paper Circuits a learn.sparkfun.com tutorial

Available online at: http://sfe.io/t348

Contents

Introduction

Paper circuits are becoming more and more popular in the hobby electronics world. The easy availability of craft-like materials and increasing abundance of new products has created a really unique ecosystem for crafters looking to make the leap to electronics projects. This guide is an overview of materials and techniques available to paper circuit crafters.

Pam Paper Circuit

What is a Paper Circuit?

A paper circuit is a functioning electronic circuit built on a paper surface instead of a PCB. Projects can range from greeting cards, to origami, to traditional art such as paintings or drawings. What makes them unique is the use of traditional fine art techniques to create a circuit that is combines aesthetics and functionality.

Suggested Reading

Before we begin crafting, here few concepts you should be familiar with:

Creating Traces: Overview

A trace is a path that takes the place of wiring, most commonly seen on a printed circuit board. In paper circuits we'll use conductive materials as a substitute for wires on the paper's surface to connect components. In this tutorial we'll discuss three types of traces: paint, tape, and ink.

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The green lines on this PCB are the traces connecting parts of the board.

Conductive Tape Traces

Conductive tape is one of the easiest ways to get started crafting a paper circuit. Just peel off the paper backing and press down where you want your circuit to go! Copper tape is also solderable, allowing strong connections between components and traces that you won't get with paint and inking methods.

Applying Copper Tape to a Paper Circuit

Prototyping with copper tape and a SparkFun template

Difficulty: Beginner
Cost: Varies - copper tape ~$.06/ft, fabric tape ~$.79/ft
Mess Level: Minimal

Pros:

Cons:

Copper Tape

Copper Tape - 5mm (50ft)

Copper Tape - 5mm (50ft)

PRT-10561
$3.95
4
Copper Tape - 2" (50ft)

Copper Tape - 2" (50ft)

PRT-11081
$18.50
8
The most common conductive tape for paper circuits is made of a thin sheet of copper with an adhesive on the bottom that comes on a roll. Manufacturers create the tape in a few different sizes, we like 5mm width tape because it is easy to work with on a smaller crafting scale.

Ni/Cu/Co 1" Wide Fabric Tape

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Image from LessEMF.com

Less common than copper tape is a conductive fabric tape made of nickel, copper and cobalt. This tape will stand up to bending and flexing and is a great option for projects that have folds (such as cards that require traces to cross the center crease).

Instructions:

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Note how the copper tape is cut to leave room for the LED.

Examples:

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This blushing robot card from Chibitronics uses thin copper tape to spell the message inside and create the circuit for the LED on the front of the card.

Jie Qi's Circuit Sketchbook uses conductive fabric tape in the book's binding and copper tape on the inside cover.

Additional Resources:

Conductive Paint Traces

Conductive paints are a great way to create artistic pieces with electronics. Use a brush or a squeeze bottle to create traces that curve and swirl to connect components. Conductive paints can also be used to 'glue' components to a trace. This method can be the most frustrating to use because of the mess factor and dry time. We recommend patience and practice when beginning to work with these materials.

Difficulty: Beginner - Intermediate (depending on complexity). Can be frustrating to get smooth lines.
Cost: Varies. Most conductive paints start at ~$10.
Mess Level: Moderate

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Painting with Bare Conductive Paint and a paintbrush. Image via Instructables.com.

Pros:

Cons:

Bare Conductive Electric Paint

Bare Conductive - Electric Paint (50ml)

Bare Conductive - Electric Paint (50ml)

COM-10994
$32.50
1

Bare Conductive - Electric Paint Pen (10ml)

COM-11521
3

Bare Conductive Printed Sensors (3 pack)

SEN-14696
Retired

Bare Conductive's Electric Paint is a nontoxic, solvent free and water soluble carbon-based paint. Available in a squeeze tube for finer lines or pot for brush and stencil use.

CuPro-Cote Paintâ„¢ from LessEMF

Conductive Paint

CuPro-Coate Paint is water based paint containing copper, similar to latex paint. Comes in 4oz through gallon containers. Due to short shelf life/working time once opened, we recommend the 4oz size.

Instructions:

Painting Copper paint

Artist carefully following her lines with conductive paint during a paintable electronics workshop held at MIT.

Examples:

Electronic Popables is an interactive pop up book created using conductive paints and electronics

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Paper Piano created by Hannah Perner-Wilson

Additional Resources:

Conductive Ink Traces

Conductive inks are now available in pre-filled pens, making it easier than ever to create traces by simply drawing them. Most conductive ink pens also dry faster than conductive paints. This method may be the easiest to apply, but attaching components can be more frustrating.

Difficulty: Beginner to Intermediate (depending on components you are attaching to the ink).
Cost: Higher - most pens start ~$20
Mess Level: Minimal

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Drawing with a Circuit Scribe pen. Image via Circuit Scribe's Kickstarter.

Pros:

Cons:

Circuit Scribe

Circuit Scribe Conductive Ink Pen

Circuit Scribe Conductive Ink Pen

COM-13254
$6.50

Circuit Scribe Maker Kit

COM-13255
Retired
Circuit Scribe is a non-toxic, silver conductive ink pen that writes similarly to a gel pen. It is great for creating precise lines and drawings to showcase (and light up) your circuit.

AgIC Circuit Marker

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AgIC is another silver-based ink that comes in marker form. It only works on EPSON Glossy Photo Paper, so you will need to plan your projects accordingly.

Instructions:

Examples:

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Paperduino 2.0 - an entire Arduino made with Circuit Scribe ink and components. Image via Instructables.

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Interactive art using Circuit Scribe modules and ink, crafted by SparkFun's Education Team.

Additional Resources:

Choosing Components

Now that we've explored options for creating traces, let's talk about the components we can use with our circuits. Not all components play nice with paper circuit trace materials. For example, if you'd like to solder connections, copper tape would be a better choice than a conductive ink. Here are a few of our suggestions of components to use in your projects.

Through-Hole Components

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Through-hole components with long leads (such as LEDs) can be bent with pliers into a shape that will sit flat on paper and provide more surface area to connect with the traces. Components with shorter legs (like the ATtiny85) can can be carefully bent flat with fingers or pliers.

Use With:

SMD Components

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While a little trickier to work with, surface-mount device (SMD) components are low profile and great small or flat projects such as greeting cards. You will need tweezers to place these components and a good eye to see the labels on the part itself. SMD components can be soldered to copper tape, connected by painting the pads with conductive paint, or taped onto copper tape. This tutorial from The Exploratorium's Tinkering Studio shows two methods for attaching SMD LEDs - soldering and clear tape.

Use With:

LilyPad Components

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Originally made for e-textile applications, LilyPad components can work well with paper circuits because of their low profile and large conductive pads. LilyPad components work best when soldered to copper tape, but can also be attached using z-axis tape or by placing clear tape over the pads to hold them to traces. Note - if using the clear tape method, only the Button and Switch boards have large enough pads to make good contact.

Use With:

Chibitronics Circuit Stickers

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Chibitronics stickers have a conductive adhesive on them which make them ideal for paper circuit projects. They are compatible with almost all paper circuit traces, but can be more expensive than using off the shelf components.

Use With:

Circuit Scribe Modules

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Circuit Scribe modules work differently than all the other components we've shown so far - they are magnetic. To attach to your traces, you will need a metal sheet or surface behind your paper. This is a temporary connection instead of the more permanent connections shown in this tutorial. While their size isn't ideal for small projects like greeting cards, it can be fun to create wall hangings or reconfigurable artwork with the modules.

Use With:

Making Connections

Now that we know how to create traces and have chosen components for our project, it's time to connect them together. Here are a variety techniques for creating an electrical connection between the components and traces.

Tape Method

Clear tape is an easy way to start attaching components to paper circuits, though it is not as reliable as other methods. Use tape to carefully press over component leads or pads and press down onto copper tape. For SMD components, you can tape over the entire part.

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Taping over SMD LED. Image via Jie Qi's flickr feed.

Use With:

Z Axis Tape

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Z-Axis tape is an easy-to-use, pressure sensitive double-sided tape designed for connecting, bonding and grounding flex circuits and PCBs. We can use small sections of tape to attach components to conductive traces.

Use With:

Conductive Paint

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Image from Bare Conductive's How to Cold Solder Tutorial.

Conductive paints can be used as a glue/cold solder joint to attach components to traces. Push components into wet paint to connect and let dry completely before powering.

Use With:

Conductive Glue/Epoxy

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An example of conductive epoxy from Atom Adhesives.

Conductive glue or epoxy is another option for connecting components. These products are one of the more expensive ways of attaching components to your paper circuit projects and can be difficult to work with. Often they need a long dry time or to be heat set. Try to find a syringe of epoxy to cut down on mess and help with precision placement. Make sure to read through the MSDS and follow all package directions when using these types of glues.

Use With:

Soldering

Soldering is one of the stronger connections you can make with paper circuits, the only drawback is that it will only work on copper tape - you cannot solder to conductive paints, inks, or most fabrics. If you need help learning how to solder, check out our tutorial.

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Examples of soldering components to copper tape from left to right:
SMD LED from the Tinkering Studio, LilyPad LED from SparkFun, and 3mm LED from High Low Tech.

Use With:

Powering Your Project

Paper circuit projects can be easily powered with a 3V coin cell battery. We recommend a 20mm or 12mm diameter battery for small projects such as greeting cards.

Coin Cell Battery - 20mm (CR2032)

Coin Cell Battery - 20mm (CR2032)

PRT-00338
$2.10
Coin Cell Battery - 12mm (CR1225)

Coin Cell Battery - 12mm (CR1225)

PRT-00337
$2.10
2

Most common coin cell batteries look like the ones above - the top and sides of the battery are positive and a textured bottom is negative. This can prove tricky for attaching to our traces, so we'll go over a few techniques to try.

Safety Note: Never solder directly to a coin cell battery! To attach a battery, choose a battery holder or battery with tabs specifically for soldering.

You can also find some good examples of battery use and power in this tutorial:

LilyPad Basics: Powering Your Project

September 24, 2018

Learn the options for powering your LilyPad projects, LiPo battery safety and care, and how to calculate and consider power constraints on your projects.

Create Your Own Battery Holder

Making a battery holder with the materials you have on hand is quick and easy! Here are a few different methods for crafting your own battery holder.

Copper Tape Holder:

Copper Tape Battery Holder Open

Copper Tape Battery Holder Closed

Copper Tape Battery Holder Example

We at SparkFun use this copper tape technique in all of our pop up card tutorials.

Paper and Copper Tape Holder:

Copper Tape Battery Holder Example

Image via Chibitronics.

Chibitronics has a tutorial on using copper tape and a piece of paper to make a battery pouch.

Paper and Conductive Paint Holder:

Conductive Paint Battery Holder Example

Image via Bare Conductive

Bare Conductive has a few different paper battery holder tutorials:

Battery Holder Modules

Battery holder modules can be soldered onto copper tape or glued with conductive glue or paint. Always remember to remove the battery from the holder before soldering.

LilyPad Coin Cell Battery Holder - Switched - 20mm

LilyPad Coin Cell Battery Holder - Switched - 20mm

DEV-13883
$2.10
12
Coin Cell Battery Holder - 20mm (Sewable)

Coin Cell Battery Holder - 20mm (Sewable)

DEV-08822
$1.50
4

Tabbed Batteries

You can also purchase batteries with solder tabs - these can then be soldered, glued with conductive glue, or sometimes even pressed in place with clear tape to attach to a circuit. When shopping for a tabbed battery, try to find one with insulation around the sides to avoid accidental shorts.

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Some examples of tabbed batteries.

Many paper circuit-specific components such as LED stickers, boards, or modules have built-in resistors. If creating your own paper circuit components with off the shelf LEDs, you may need to add resistors to your circuit to account for different voltage requirements.

Resources and Going Further

Wow, we covered a lot of concepts in this tutorial! If you are unsure where to start, try experimenting with small swatches of scrap paper and exploring which technique works best for your project ideas. If you are looking for some more guided projects, check out some of our tutorials:

Light-Up Father's Day Card

Light up your dad's day with this electronic pop-up card!

Let It Glow Holiday Cards

Craft a glowing card for friends and family this holiday season with paper circuits - no soldering required!

Light-Up Valentine Cards

Light up your love with paper circuits - no soldering required!

Bare Conductive Musical Painting

Learn how to make a musical painting using the Bare Conductive Touch Board and Conductive Paint.

Looking for some paper circuit designs? Check out some of these resources:

Paper Circuits Pin

March 31, 2014

This quick craft project shows you how to create a circuit using copper tape instead of wire to light up an LED and make a wearable piece of e-craft art.

Paper Circuits: Lotus Flower Pop Up Card

May 6, 2014

Templates used in the Have Fun with Paper Circuitry workshop at GESTEM on 5/9/14.

You also do not have to be limited by using just paper. Try exploring circuits with cardboard!

Enginursday: Cardboard Circuits

November 30, 2017

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