Voltera's printing solutions enable the creation of flexible membrane switches by depositing conductive inks onto substrates like PET and polycarbonate, allowing for the development of customizable, durable human-machine interfaces.

Flexible Membrane Switches

Flexible Membrane Switch Printing - Customized Human-Machine Interface Applications

<h2 id="">Video</h2><figure id="" class="w-richtext-figure-type-video w-richtext-align-center" style="padding-bottom:33.723653395784545%" data-rt-type="video" data-rt-align="center" data-rt-max-width="" data-rt-max-height="33.723653395784545%" data-rt-dimensions="854:480" data-page-url="https://youtu.be/n3ZVfqWDtJU?si=z4j9WOXPW6Pz-pzW"><div id=""><iframe allowfullscreen="true" frameborder="0" scrolling="no" src="https://www.youtube.com/embed/n3ZVfqWDtJU" title="Printing a Flexible Multilayer Membrane Keyboard with Voltera NOVA"></iframe></div></figure><h2 id="">Project overview</h2><h3 id="">Purpose</h3><p id="">The purpose of this project is to demonstrate how NOVA prints multilayer electrical circuits on a highly flexible substrate (PET), and dispenses ink with high precision on sections that are as small as 250 µm W × 40 µm H.</p><figure id="" class="w-richtext-figure-type-image w-richtext-align-center" data-rt-type="image" data-rt-align="center"><div id=""><img src="https://cdn.prod.website-files.com/6334888a34bfac03b46aa715/6709244e9b0c2b80f33a3fe8_670922e2efba3a9da3b8f456_Printing-flexible-membrane-keyboard-purpose.webp" loading="lazy" alt="A three layered print on PET with crossovers" width="auto" height="auto" id=""></div><figcaption id="">Figure 1:&nbsp;Three layered print with crossovers</figcaption></figure><h3 id="">Design layout</h3><p id="">We divided the layout into three layers:</p><ol id=""><li id="">Base conductive layer (ACI SS1109 Stretchable Silver Ink)</li><li id="">Dielectric layer (ACI SI3104 Stretchable Printed Insulator)</li><li id="">Top conductive layer (ACI SS1109 Stretchable Silver Ink)</li></ol><h3 id="">Desired outcome</h3><p id="">Based on a matrix style keyboard design, we limited the number of pins used to only seven on the controller (Arduino Micro, A000053). Once connected to a power source, pressing any key on the keyboard will trigger the controller to register the key.&nbsp;</p><h3 id="">Functionality</h3><p id="">We determined a 10-numbered keypad design would be suitable for this project. However, other flexible membrane keyboard designs have the potential for further customization, such as specific graphics, colors, or lighting, which could be beneficial for specialized equipment, including customized control panels, wearable devices, and foldable electronics.</p><h2 id="">Printing and curing the flexible substrate</h2><h3 id="">Base conductive layer</h3><p id="">This layer consists of a 4’’ × 3’’ matrix grid for 10 numbered keys, excluding the 10 dielectric pads (see dielectric layer).</p><figure id="" class="w-richtext-figure-type-image w-richtext-align-center" data-rt-type="image" data-rt-align="center"><div id=""><img src="https://cdn.prod.website-files.com/6334888a34bfac03b46aa715/6709244d9b0c2b80f33a3fb9_670923005ab20b4c6a573338_Printing-flexible-membrane-keyboard-base-conductive-layer-schematic.webp" loading="lazy" alt="Base conductive layer schematic" width="auto" height="auto" id=""></div><figcaption id="">Figure 2:&nbsp;Base conductive layer schematic</figcaption></figure><figure id="" class="w-richtext-figure-type-image w-richtext-align-center" data-rt-type="image" data-rt-align="center"><div id=""><img src="https://cdn.prod.website-files.com/6334888a34bfac03b46aa715/6709244e9b0c2b80f33a4047_6709231c5bb93f90a2cdcfcf_Printing-flexible-membrane-keyboard-base-conductive-layer-printing.webp" loading="lazy" alt="NOVA Dispenser printing layer 1 on PET" width="auto" height="auto" id=""></div><figcaption id="">Figure 3:&nbsp;Base conductive layer being printed with NOVA</figcaption></figure><p id="">[script]https://uploads-ssl.webflow.com/6334888a34bfac591c6aa6e9/661988c7b384dd7ea5d77f7a_Flexible%20membrane%20keyboard%20whitepaper%20table%201.txt[/script]</p><figure id="" class="w-richtext-figure-type-image w-richtext-align-center" data-rt-type="image" data-rt-align="center"><div id=""><img src="https://cdn.prod.website-files.com/6334888a34bfac03b46aa715/6709244c9b0c2b80f33a3fac_67092339362ae204a8569f3b_Printing-flexible-membrane-keyboard-base-conductive-layer-print-settings.webp" loading="lazy" alt="NOVA settings for base conductive layer" width="auto" height="auto" id=""></div><figcaption id="">Figure 4:&nbsp;NOVA&nbsp;print settings, base conductive layer</figcaption></figure><h3 id="">Dielectric layer&nbsp;</h3><p id="">This layer consists of 10 dielectric pads. To ensure full coverage of the dielectric ink, we did two passes for this layer, each cured after dispensing.</p><figure id="" class="w-richtext-figure-type-image w-richtext-align-center" data-rt-type="image" data-rt-align="center"><div id=""><img src="https://cdn.prod.website-files.com/6334888a34bfac03b46aa715/6709244c9b0c2b80f33a3fa9_67092356708e26b2cc8d222e_Printing-flexible-membrane-keyboard-dielectric-layer-schematic.webp" loading="lazy" alt="Dielectric layer schematic" width="auto" height="auto" id=""></div><figcaption id="">Figure 5:&nbsp;Dielectric layer schematic</figcaption></figure><figure id="" class="w-richtext-figure-type-image w-richtext-align-center" data-rt-type="image" data-rt-align="center"><div id=""><img src="https://cdn.prod.website-files.com/6334888a34bfac03b46aa715/6709244e9b0c2b80f33a3ffd_6709236e994543d8a36f6105_Printing-flexible-membrane-keyboard-dielectric-layer-print-result.webp" loading="lazy" alt="Dielectric layer print result" width="auto" height="auto" id=""></div><figcaption id="">Figure 6:&nbsp;Dielectric layer print result</figcaption></figure><p id="">[script]https://uploads-ssl.webflow.com/6334888a34bfac591c6aa6e9/66198a8a04b1f825dac46907_Flexible%20membrane%20keyboard%20whitepaper%20table%202.txt[/script]</p><figure id="" class="w-richtext-figure-type-image w-richtext-align-center" data-rt-type="image" data-rt-align="center"><div id=""><img src="https://cdn.prod.website-files.com/6334888a34bfac03b46aa715/6709244d9b0c2b80f33a3fbe_67092388bd5f734676f835a5_Printing-flexible-membrane-keyboard-dielectric-layer-print-settings.webp" loading="lazy" alt="NOVA print settings for the dielectric layer" width="auto" height="auto" id=""></div><figcaption id="">Figure 7:&nbsp;NOVA&nbsp;print settings, dielectric layer</figcaption></figure><h3 id="">Top conductive layer</h3><p id="">This layer consists of 10 fine crossover lines that connect the red signal paths and complete the circuitry. </p><figure id="" class="w-richtext-figure-type-image w-richtext-align-center" data-rt-type="image" data-rt-align="center"><div id=""><img src="https://cdn.prod.website-files.com/6334888a34bfac03b46aa715/6709244d9b0c2b80f33a3fb6_670923ababdea1f85b1530df_Printing-flexible-membrane-keyboard-top-conductive-layer-schematic.webp" loading="lazy" alt="Top conductive layer schematic" width="auto" height="auto" id=""></div><figcaption id="">Figure 8:&nbsp;Top conductive layer schematic</figcaption></figure><figure id="" class="w-richtext-figure-type-image w-richtext-align-center" data-rt-type="image" data-rt-align="center"><div id=""><img src="https://cdn.prod.website-files.com/6334888a34bfac03b46aa715/6709244e9b0c2b80f33a3fd8_670923cfabdea1f85b154f1d_Printing-flexible-membrane-keyboard-top-conductive-layer-print-result.webp" loading="lazy" alt="Top conductive layer with crossovers" width="auto" height="auto" id=""></div><figcaption id="">Figure 9:&nbsp;Top conductive layer print result with crossovers</figcaption></figure><p id="">[script]https://uploads-ssl.webflow.com/6334888a34bfac591c6aa6e9/66198b6c59c79a384d6119df_Flexible%20membrane%20keyboard%20whitepaper%20table%203.txt[/script]</p><figure id="" class="w-richtext-figure-type-image w-richtext-align-center" data-rt-type="image" data-rt-align="center"><div id=""><img src="https://cdn.prod.website-files.com/6334888a34bfac03b46aa715/6709244e9b0c2b80f33a3fe4_670923ef79f68cb3137c9c83_Printing-flexible-membrane-keyboard-top-conductive-layer-print-settings.webp" loading="lazy" alt="NOVA settings for the top conductive layer" width="auto" height="auto" id=""></div><figcaption id="">Figure 10:&nbsp;NOVA print settings, top conductive layer</figcaption></figure><h2 id="">Challenges and advice for printing multilayer</h2><h3 id="">Broken layers</h3><p id="">Because inks from different manufacturers have different properties – they may contain solvents that dissolve existing traces for example – printing and curing each new layer risks breaking the layer previously completed. It is, therefore, crucial that you choose compatible materials based on the degree of flexibility required.</p><p id="">For this project, we selected compatible inks from ACI Materials, but for projects that involve using multiple inks from different manufacturers, it is recommended that you <strong id="">check the materials’ technical data sheets</strong>.</p><h3 id="">Electrical shorts</h3><p id="">Due to the matrix design of the keyboard, the signal lines have a number of crossovers, which could cause electrical shorts if not insulated properly.</p><p id="">Printing a second pass of the dielectric layer achieves an appropriately thick insulating layer and supports further printing on top.&nbsp;</p><h3 id="">Connection issues</h3><p id="">Because the crossover sections are intricate (250 µm W × 40 µm H), if the nozzle scratches the ink while printing, the electrical paths may not function as planned.</p><p id="">Separating the crossover sections into their own layer (the top conductive layer) allows each crossover pad to be probed accurately and have specialized settings, yielding a higher success rate.</p><p id="">In addition, because changes in height can happen drastically when printing over existing traces, setting a low probe pitch will make the height map more accurate. An accurate height map means the height transition at the edges of features is accurate and the risk of traces being printed off-course is low.</p><h2 id="">Post-printing: A fully flexible electronic device</h2><figure id="" class="w-richtext-figure-type-image w-richtext-align-center" data-rt-type="image" data-rt-align="center"><div id=""><img src="https://cdn.prod.website-files.com/6334888a34bfac03b46aa715/6709244e9b0c2b80f33a400f_6709241ab070d58e6f035de8_Printing-flexible-membrane-keyboard-post-printing-fully-flexible-electronic-device.webp" loading="lazy" alt="Flexible keyboard assembled and plugged in" width="auto" height="auto" id=""></div><figcaption id="">Figure 10:&nbsp;Flexible keyboard assembly</figcaption></figure><p id="">To ensure the Arduino Micro was securely in place, we used a FR1 board, cut it to 30 mm × 60 mm, and placed it beneath the flexible substrate (PET sheet). Next we drilled through holes on the board and the flexible substrate with the <a href="https://www.voltera.io/v-one" id="">Voltera V-One PCB printer</a>.</p><p id="">We then dispensed solder paste, placed the diodes on the flexible substrate, and riveted it together with the FR1 board, before placing the metal switches on the rectangle-shaped contacts. To secure the metal switches, we covered them with Kapton tape.</p><p id="">Next, we secured the controller to the flexible substrate and connected it to a power source. We also gave the keyboard a finishing touch by placing it inside a 3D-printed enclosure with graphical silicone keys.</p><figure id="" class="w-richtext-figure-type-image w-richtext-align-center" data-rt-type="image" data-rt-align="center"><div id=""><img src="https://cdn.prod.website-files.com/6334888a34bfac03b46aa715/6709244d9b0c2b80f33a3fd3_67092437df6f44a8a78c9bfb_Printing-flexible-membrane-keyboard-post-printing-final-hard-case.webp" loading="lazy" alt="final assembly in 3D-printed case" width="auto" height="auto" id=""></div><figcaption id="">Figure 11:&nbsp;Final assembly in 3D-printed case</figcaption></figure><h2 id="">Conclusion&nbsp;</h2><p id="">This project highlights the innovative potential of printing on flexible substrates. It also points to the critical role of fine-tuning print settings to achieve success in multilayer projects.&nbsp;</p><p id="">As achieved by this project, using compatible materials helps ensure optimal performance, and is key to unlocking the full potential of flexible electronics. As we continue to explore the boundaries of what’s possible with flexible substrates, we invite you to view the <a href="https://www.voltera.io/applications" id="">other projects</a> we’ve completed.</p>

Printing a Flexible Membrane Keyboard with Conductive Silver Ink and Dielectric Ink on PET

Discover the design, printing, and assembly of a multilayer flexible membrane keyboard printed with conductive silver ink and dielectric ink on PET.

Printing a Flexible Membrane Keyboard with Conductive Silver Ink and Dielectric Ink on PET | Voltera

Flexible Membrane Keyboard

For this project, we used NOVA to print multilayer electrical circuits to make a compact, adaptable, flexible membrane keyboard.

Flexible Membrane Switches

Our white papers

Printing a Flexible Membrane Keyboard with Conductive Silver Ink and Dielectric Ink on PET

Additional resources

Learn how we can help with your application