If you say the phrase “3D printing” to most people, it conjures images of depositing spools of plastic using a machine that looks nothing like a desktop printer. The technology is about 30 years old, but the systems and range of useful materials have gradually expanded over time.
Upon its adoption by industry, 3D printing now forms the cornerstone of the larger field of additive manufacturing, and there is some distinction that must be made between the two. Here’s a closer look at additive manufacturing vs. 3D printing, and how the processes fit together to enable faster prototyping capabilities for PCBs and electronics.
Additive Manufacturing vs. 3D Printing: Is There a Difference?
3D printing and additive manufacturing are often taken as synonymous. Both terms refer to a process in which components are created by means of an additive process, selectively adding material often but not always, one layer at a time. This is in contrast to the traditional subtractive manufacturing process, in which a component is fabricated by removing material from a workpiece, or materials are injected into a mold.
Despite the arguments over semantics, there are some differences between 3D printing and additive manufacturing. 3D printing involves depositing material, either onto a substrate or as a freestanding part. With PCBs, each layer is mapped from an EDA model.
Additive manufacturing includes 3D printing as the core process, but it requires other processes that complement 3D printing that are used to fabricate a broader range of products.
Manufacturing engineers who are considering complementing or replacing traditional manufacturing processes should be aware of current additive manufacturing processes and the range of products they can be used to create. If you are building prototypes for a new product, choosing the right additive manufacturing system and process allows fabrication of components that closely match those produced with traditional processes in less time and at competitive costs.
uses conductive and dielectric inks to form metal traces on or inside of an insulating polymer material.
Additive Manufacturing Processes for Electronics
ASTM International defines seven distinct additive manufacturing processes, all of which expand on 3D printing. Some of these processes are broken out into sub-processes that are specialized for additive manufacturing of electronics.
Using a system that implements the right additive process allows printing of multilayer PCBs that closely resemble a conventionally manufactured board, as well as non-planar PCBs with unique geometries. Functional components, like antennas or conductive sensing elements, can also be printed directly on a PCB without incurring additional fabrication steps.
With this in mind, let’s examine some groups of additive manufacturing processes for 3D printing electronics and PCBs:
Material Jetting Processes
This process is ideal for printing non-planar PCBs and multilayer PCBs with nearly any geometry. This involves controlling a print head that deposits electrically conductive or insulating materials as it moves. A system designed specifically for PCBs actually includes two print heads that print conductive traces and the insulating substrate simultaneously. The ink materials are loaded into the printer and flow to the print heads, either from a cartridge or from external tanks. Excess material may be recaptured and recycled to reduce material waste.
Nanoparticle jetting, a closely related process, uses a liquid ink with suspended metal nanoparticles. The ink is jetted into a thin layer of droplets. This process uses conductive and dielectric inks to form metal traces in or onto an insulating polymer substrate material.
Such nanoparticle inks can also be deposited using an aerosol jet deposition process, this requires a carrier gas for focusing. In this process, the printed materials are solidified with lamps or thermally by heating the deposition stage, leaving behind solid conductors on a pre-shaped polymer substrate.
If you’re familiar with desktop 3D printers that work with plastics and “green” unsinteredmetals, then you’re already familiar with extrusion. In this process, filaments or rods of raw material are heated as they pass through a print head and are extruded layer-by-layer. The material cools and solidifies as it is extruded, leaving behind a solid structure.
Green metal parts 3D printed this way will then require sintering in a furnace. Extrusion is currently gaining in popularity as a direct result of the introduction of engineering-grade polymers, such as Ultem, PEEK, PEK, and carbon fiber ingredients.
This simple, low-cost printing method is only usable with solid materials that have a low melting temperature or that require a further sintering step. Compared to other methods, it is a rather slow process, and the printing resolution is limited by the size of the nozzle. Although material extrusion has been used to print embedded electronic components with odd shapes and larger form factor, it is not ideal for high precision multilayer circuits.
A material extrusion 3D printer in action
Powder Bed Fusion
This class of processes is also solid-state, although this involves depositing powdered materials and fusing them into a solid. Powdered materials can be fused using an electron beam, laser, heated roller, or by simply heating the powder up to high temperature. The most precise powder bed fusion processes use an electron beam for fusion, followed by laser and thermal fusion.
Powder bed fusion is unsuitable for electronics, including PCBs, however, as it does not currently offer high enough resolution, nor is it deployed as a multi-material process. In addition, these methods have slow print speeds, as well as size and shape limitations.
Compared to material jetting, the power consumed by PBF machines is higher. The focusing required with a laser or an electron beam, as well as the use of a heated roller, restricts these methods to a limited set of install sites and highly trained operators.
Additive Manufacturing and 3D Printing for Electronics Prototypes
Although the level of automation in nearly all industries is increasing by leaps and bounds, circuit board fabrication is one critical area that continues to lag behind. The design and fabrication process for building prototype PCBs and electronics is still stuck in the past. Designers still have to work around significant lead times and costs for low-volume prototyping runs.
This is partly a result of the growing complexity of today’s circuits. As recently as the 1990s, when circuits were simpler, many companies had internal prototyping capabilities but today’s multilayer requirements have made using traditional processes for PCB prototyping either too complex, too expensive or oftentimes, both.
Given the continuous innovation in 3D printing technologies, PCB fabrication is poised to enter a new era of automation. The right additive manufacturing system now allows you to print your PCBs in-house, rather than lose control over your development cycles while waiting for a traditional manufacturing house to fabricate and ship a low-volume prototyping run. These devices are ready to assemble and test as soon as they are printed, so you can immediately implement design changes as needed.
Going into the future, we expect these systems and processes to only continue to advance. This could mean integrating conventional pick-and-place and soldering systems into additive manufacturing systems to eliminate manual assembly steps for mounting components to PCBs, further decreasing the time required to create functional prototypes and finished products.