With modern electronics becoming faster, smarter, and smaller, more and more PCB designers are working on progressively smaller boards. Finding a balance between efficient use of board space and form factor is like walking a tightrope, and PCB designers are always looking for creative ways to reduce the footprint of a circuit to miniaturize products.
Developments in PCB design, like high-density interconnect routing, creative via architectures, and higher layer counts, are great ways for designers to save board space and reduce costs. One technique that will play an important role when addressing how to reduce PCB size is embedding components in the interior layers of the board. This saves space on the surface layers for bulky components that are not suitable for embedding.
3D printing edge connectors is one way to reduce PCB size
Solving the Problem of How to Reduce PCB Size
With a significant amount of board space on PCBs being occupied by passive components, designers can save board space for active components by embedding passive components in the interior layers. Active components can also be embedded so long as designers can reach the relevant pins on these devices with traces and vias.
3D printing of multilayer PCBs makes this possible with fewer fabrication and assembly steps compared to traditional methods. Some components can already be 3D printed with commercially available materials. This ultimately allows a designer to decrease the overall board size. Many of these applications involving embedded components are still in the proof-of-concept phase, but the range of viable applications will continue to expand as 3D printing technology advances.
The Role of 3D Printing in Embedding Components
3D printing can play an important role in expanding the range of components that can be embedded in the interior layers of a PCB. The inherent layer-by-layer fabrication process in 3D printing makes it quite easy to leave cavities with conductive pads in an interior layer. The print-job can be quickly paused, the required components placed and soldered in the cavity, and the print-job can then be continued.
This mimics the procedure used to embed components during the traditional PCB fabrication process, albeit with far fewer fabrication steps. The industry has actually recognized a standard fabrication process in IPC-7092, Design and Assembly Process Implementation for Embedded Components standards. This standard specifies design and assembly processes for embedding active and passive components in multilayer PCBs.
The typical process involves depositing a molded prepreg layer on an interior rigid layer. This requires depositing a layer of photosensitive resin on a rigid board layer and exposing the resin to UV light through a photoresist. The exposed resin hardens, while the unexposed resin can be washed away with a chemical solution. Components can then be placed in the remaining cavities, and successive layers are pressed on top of the molded layer using standard processes.
With traditionally fabricated multilayer PCBs already requiring dozens of fabrication steps, 3D printing provides the same results with fewer required fabrication steps thanks to the continuous layer-by-layer deposition process. With 3D printing, the copper etching, prepreg deposition and exposure, and washing processes are eliminated because cavities for embedded components can be printed directly. This reduces material waste and eliminates the photoresist recycling processes typically used by traditional PCB manufacturers.
3D Printing Passive Embedded Components Directly
Going into the future, 3D printing offers designers the possibility of directly fabricating embedded components during fabrication, rather than embedding commercial off-the-shelf components. Passive components are prime candidates for 3D printing as additive manufacturing systems for PCBs still lack the capability to fabricate semiconductor devices directly on a PCB.
As inductors are essentially just coiled conductors, they can be easily embedded in multilayer PCBs using 3D inkjet printing with nanoparticle conductive inks. Electromagnets have similar structures as inductors in that they consist of a coiled conductor, making them ideal for additive manufacturing, either on the surface of a 3D printed PCB or embedded in an inner layer. Placing these elements in the interior layers can free up surface layers for active components or other bulky components, with potential to make the component smaller, lighter and less expensive to produce.
If you’re working with a device that requires an antenna or RF amplifier, 3D printing these components can provide another advantage in addition to embedding. Unique antenna architectures like phased array antennas or non-planar antennas can be directly fabricated on the surface layer of a PCB or embedded in the substrate. Such antenna arrays and amplifiers need to be impedance matched to their transceiver using an LC network, and the inductor in the network can be embedded in the substrate, freeing up space on the surface layer for the capacitor.
Process for designing and 3D printing embedded capacitors
3D printing of capacitors is still in the proof-of-concept stage. Without the capability to 3D print an electrolytic or ceramic material as the dielectric core of the capacitor, these devices must use the actual substrate as the dielectric. Currently, the available range of capacitance is limited by the geometry of the capacitor. However, as the range of materials available for 3D printing expands, so will the capabilities of 3D-printed embedded capacitors and resistors.
If you’re developing a proof of concept for an embedded sensor system and you need rapid prototyping capabilities, look no further than the DragonFly Pro additive manufacturing system. Sensors engineers can quickly produce novel 3D-printed sensors alongside other functionality on a single PCB. Read a case study about our 3D-printed embedded capacitors or contact us today to learn more about the DragonFly Pro system.
IMPORTANT: PLEASE READ CAREFULLY.
This ability of the DragonFly 2020 3D Printer and the feature presented in this article is shown here for demonstration purposes only.
Caution! This feature is still in development and is not released with the product. Any attempt to reproduce or imitate the feature is made at your own risk and may result in injury to the operator and/or damage to the printer You are strongly encouraged not to reproduce the feature or perform similar actions.
For further information regarding the DragonFly 2020 3D Printer and the feature presented here, please contact www.nano-di.com/contact-us