Jan 23, 2020

Enabling High Layer Count PCBs with Additive Manufacturing

high layer count pcbIf you’ve bought a new electronic product in the last few years, the PCB inside the device is most likely a multilayer PCB. Devices with a microcontroller, WiFi, or other wireless communication capabilities, and displays all require at least four-layer PCBs. This ensures the board includes power/ground planes and at least one signal layer, ensuring a minimal level of power and signal integrity.

As more products are run at lower power levels, and as more capabilities are packed into a single board, high layer count PCBs are becoming increasingly common, especially in the embedded computing, mobile, and IoT worlds. For very advanced applications in industries like aerospace and defense, it is not uncommon to see layer counts reaching dozens of layers. The fabrication process for these boards requires several repetitive steps, bringing higher costs and lead times. In contrast, working with the right additive manufacturing system allows for easier production  of smaller and more compact PCB/package sizes and advanced products with lower lead times and costs.

Additive manufacturing for complex high layer count PCBs

Complex high layer count PCBs like this can be easily produced with the right additive manufacturing system.

Multilayer PCB Production

Multilayer PCBs with high layer counts are widely used in the electronics industry to provide the necessary interconnect density and component density for several devices. Using a larger number of layers in a PCB allows multiple layers to be defined as signal layers, which frees up space on the surface layers for components. 

Multiple power and ground planes can be used in the interior layers, which aids EMC compliance, signal integrity, power integrity, and isolation. These points are particularly important in mixed-signal boards, where digital and analog signals need to be routed in different sections and/or different layers on the same board to prevent interference.

The production process for high layer count PCBs requires multiple plating, etching, pressing, and drilling steps, each of which takes a certain amount of time and materials. As layer counts increase, so do the costs for these fabrication steps. This is one reason why designers try to confine their designs to as few layers as possible, sometimes compromising designing so as not to hinder reliability or risk failure.This has also motivated the development of unique design and routing methodologies, such as laser-drilled microvias, VeCS, and ELIC in multilayer HDI PCBs.

The manufacturing process for high layer count PCBs constrains designers to a particular pad, via, and interconnect architecture to ensure development and manufacturability. Although new manufacturing and quality control methods have broadened multilayer PCB design options, PCB layout engineers are running up against roadblocks to continued innovation. The cost, fabrication time, and innovation obstacles motivate using a new method for electronics prototyping and high-mix, low-volume production of high layer count PCBs. Furthermore, as technology advances, design solutions become increasing complex, which requires more advanced solutions for designing and producing reliable PCBs. 

Why Use 3D Printing to Produce High Layer Count PCBs?

There are several reasons to consider an additive manufacturing system to produce advanced PCBs.

Time and Cost Don’t Depend on Layer Count

An additive manufacturing process like aerosol jetting or inkjet printing is ideal for fabricating fully-functional high layer count PCBs. The layer-by-layer deposition process allows designers to print more complex, higher layer count PCBs without increasing costs. Instead, the fabrication time and costs involved in 3D printing are only a function of the weight of the materials deposited, rather than of the complexity of the device being manufactured.

Thanks to the elimination of repetitive traditional fabrication steps and the complexity-independent nature of 3D printing, electrically complex high layer count PCBs can be 3D printed with fixed lead time and cost. A panel of fully-functional high layer count PCBs can be 3D printed in a matter of hours, while the same PCB panel would take days or weeks to produce with traditional fabrication processes. This allows designers to use higher layer counts without worrying about excess costs.

Any Board Architecture Is Possible

Traditional multilayer fabrication processes constrain designers to using an orthogonal interconnect and via architecture on a planar substrate. In contrast, the layer-by-layer deposition process in 3D printing systems allows designers to create any board architecture, including nonplanar PCBs. The same ideas apply to traces and vias. Nearly any interconnect and via geometry can be easily 3D printed with this type of process, including interconnect architectures that cannot be manufactured with traditional processes.

A less-complex PCB

Your board geometry can be much more complex than this when you use an additive manufacturing system for high layer count PCBs.

Advanced Materials for Functional Electronics Are Available

Inkjet processes already use advanced insulating and conducting nanoparticle suspensions to co-deposit a substrate and conductors simultaneously. However, the list of available polymer materials for use in 3D-printed electronics is growing. New low-k polymer materials are becoming widely available for use as insulating substrates, which are very useful for high-speed devices. 

The electrical properties of polymer materials can also be tuned by doping or adding functional groups, allowing this class of materials to be used in highly specialized applications. In addition, semiconducting organic and inorganic polymers can be 3D printed, allowing fabrication of semiconducting devices on a fully-functional PCB.

Using the right 3D printing system only hastens rapid prototyping, especially when prototyping high layer count PCBs with traditional architecture. Designers can print a single advanced device, test it quickly, and determine required redesigns in less time than is required to manufacture a multilayer PCB with traditional processes. 3D printing is also ideal for R&D or high-mix, low-volume production of advanced electronic devices thanks to its extreme adaptability and the design freedom it provides.

Whether you need to prototype high layer count PCBs or you are looking to produce high mix, low volume multilayer boards, a specialized inkjet 3D printer is ideal for producing these complex electronics. The DragonFly LDM system from Nano Dimension is ideal for rapid prototyping and full-scale in-house production of complex additively manufactured electronics (AMEs) with a planar or nonplanar architecture. You’ll have the capability to produce advanced high layer count PCBs with this advanced fabrication system with lower costs and lead times compared to traditional processes. Read a case study or contact us today to learn more about the DragonFly LDM system.

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