The trend in the electronics industry over the last 50 years has been one of continuous minimization, where more computing power is packed into ever-smaller footprints. Keeping up with Moore’s Law has driven miniaturization at the integrated circuit level, where transistors are successively miniaturized and densities are increased over time. However, this level of miniaturization has also happened at the PCB level.
Part of this miniaturization is driven by the convenience of Moore’s Law: As transistor densities increase, chip sizes have decreased, and the board size required for a given device is also allowed to decrease. However, there is still a demand for even smaller boards that is driven by an expectation of greater functionality in a single device.
This motivates totally changing the PCB manufacturing process for developers to see the benefits of miniaturization of electronic components. Here’s how 3D printing can help satisfy the demand for smaller boards with greater device density.
Moore’s Law has helped designers see the benefits of miniaturization of electronic components and PCBs.
Benefits of Miniaturization of Electronic Components with 3D Printing
As electronic components have been miniaturized, so have the PCBs used to connect them. Developments in specialized system-on-chip (SoC) components, smaller passives, and higher transistor density in powerful processors have allowed more components to be placed in a smaller area. In addition, this has allowed newer devices to have greater functionality that would formerly have required multiple boards in a single package, or multiple devices connected together. There is no sign of this trend ending, which is constantly forcing designers to come up with new ways to pack more components into a smaller space.
The structure of planar PCBs on rigid substrates is such that components are confined on one or two layers, ultimately limiting available board space. In addition, the manufacturing process for planar PCBs constrains the interconnect architecture that can be implemented to being purely orthogonal, making use of perpendicular vias and traces for layer transitions in multilayer PCBs. Other DFM guidelines for planar PCBs limit the allowed spacing between traces, pads, and vias, which inhibits components from being placed closer than would be allowed electrically.
With a 3D printing system, designers can break these traditional DFM rules and take full advantage of miniaturization of electronic components. There are some novel design choices layout engineers can easily implement when fabricating boards with an additive manufacturing system.
Component Stacking and Embedding
This solution for increasing component density normally relies on cutting and routing cavities from a planar prepreg layer to make room for an IC or large passives. This significantly increases fabrication costs and time as multiple drilling, plating, etching, and pressing steps are required to build a stackup with cavities for components. Most manufacturers do not offer this type of service, even though it is an ideal way to see the benefits of miniaturization of electronic components.
With an additive manufacturing system, cavities for embedded or stacked components can be easily formed in a standard layer-by-layer deposition process. This can be done with any drilling steps as the process leaves behind open cavities for components with exposed pads. Large ICs or small passives can be placed in these cavities and coated with a subsequent layer, leaving a fully encased component in the board interior. Another option is to embed thin connectors in the interior layers.
Furthermore, because these cavities are not placed through mechanical drilling and routing, the only limit in the size of the cavity that can be placed is the printing resolution, rather than the size of the bit. This allows very small passives to be placed in an interior layer as needed, rather than on a surface layer.
Four integrated circuits can be vertically stacked in this 3D-printed structure.
Direct Printing of Passives
3D printing processes that allow simultaneous deposition of an insulating and conductive structure can be used to easily fabricate passive components on a board. Such processes include aerosol jetting and inkjet printing, which can be used to deposit capacitors, inductors, passive filters, RF amplifiers, and unique antennas directly in a 3-printed substrate. When these components are placed in an interior layer, this frees up space on a surface layer for other components that may be more bulky, such as large capacitors, transformers, or connectors.
As a broader range of advanced materials become available for use in commercial 3D printers, such as semiconducting polymers, a wider range of passive and active devices can be printed directly on a surface layer or an interior layer. This allows a range of unique devices to be 3D printed alongside the board and conductors in a single process. Because these structures can be directly printed a layer at a time, they can be easily embedded inside the board with no required finishing or assembly steps.
This ultra-wideband antenna is easily 3D printed with an inkjet process.
Unique Interconnects Save Board Space
Taking advantage of the aforementioned benefits of miniaturization of electronic components may require implementing a unique interconnect architecture, which may not consist of orthogonal vias and traces. Examples include the use of curved, coaxial, and flat vias and traces.
The layer-by-layer deposition process in a 3D printing system is only limited by the resolution of the printer, and your design limitations are only based on electrical rules rather than traditional DFM requirements. Because the spacing between traces and via holes is not limited by mask or drill sizes, components can be placed closer together than would be allowed in a traditional manufacturing process. When implemented alongside embedded components and printed passives, a unique interconnect architecture provides a customizable routing solution and gives layout engineers more control over signal integrity.
Beyond Board Miniaturization
These benefits of 3D printing for electronics fabrication also affect fabrication costs and time. The time and costs involved in 3D printing processes are independent of the device complexity, and instead, they only depend on the weight of raw materials being deposited. Furthermore, a single fully-functional prototype PCB can be fabricated in a matter of hours with the right 3D printing system. This dramatically hastens R&D cycles, allows electronics designers to be more agile and creative, and decreases time to market.
You can see the benefits of miniaturization of electronic components and board sizes when you use an additive manufacturing system that allows embedding and fabrication of unique interconnect architecture. The DragonFly LDM system from Nano Dimension is ideal for high-volume, low-mix production of complex additively manufactured electronics (AMEs) in-house with planar or nonplanar geometry that is not possible with traditional processes. Read a case study or contact us today to learn more about the DragonFly LDM system.