Selective Laser Sintering (SLS) and How It Works in Electronics Manufacturing

March 26, 2020 Cadence PCB Solutions

Start button on an electronic with innovation spelled next to it

 

“This isn’t the way that we’ve always done it.” Many times, the phrase “this isn’t the way that we’ve always done it” becomes the death knell for good projects and inventions. Think about this: if past, present, and future thinkers had not risked moving their ideas forward, we might still be carrying our work as brickmakers on horseback, view the thought of powered flight as mere folly, and might never have the desire to explore the universe. And…certainly, we wouldn’t concern ourselves with something called PCB design or what’s new with the Internet.

Breakthrough Thinking Wins

Although additive manufacturing has become an accepted and viable process….and has the potential to powerfully impact the processes involved with PCB design, the concept continues to define breakthrough thinking and continues to foster innovation. Additive manufacturing develops products—such as PCBs—by adding materials until the final product has formed.

Originally considered as a fast prototyping method, additive manufacturing now yields the flexibility, durability, and environmental friendliness that responds to consumer need and cost-consciousness. For just a moment, let’s consider several methods for achieving additive manufacturing. Material extrusion relies on a heated nozzle moving horizontally across a bed. Extruded materials add to the product while the bed lowers and provides more space for new layers. A subset of material extrusion called directed energy deposition (DED) uses similar methods for adding layers of ceramics, polymers, and metals.

Lasers or thermal beams make an additive process called power bed fusion possible by dissolving different types of materials. Power bed fusion covers processes such as direct metal laser sintering (DMLS), stereolithography (SLA), electron beam melting (EBM), selective heat sintering (SHS), and selective laser sintering (SLS). The following table describes the different power fusion processes.

 

Power Bed Fusion Processes

Process

Description

Materials

Direct Metal Laser Sintering

3D printing technology that uses a laser to create a metal part from a 3D CAD model

Finely powdered metal alloys or pure metals including steels, aluminum, titanium, nickel alloys

Stereolithography

Uses an ultraviolet laser to convert liquid thermoset resin into layers that form 3D-printed objects

Resin

Electron Beam Melting

Uses a precise high power electron beam controlled by electromagnetic coils. Works in a vacuum and melts material according to geometry defined by CAD model

Powdered titanium and cobalt-chrome

Selective Heat Sintering

Uses a thermal print head to harden layers of powder

Thermoplastic

Selective Laser Sintering

3D printing technology that uses a laser to create a nylon part from a 3D CAD model

Nylon or Polyamide

 

Along with using extrusion, fusion, and polymerization techniques, additive manufacturing may also consist of jetting processes. While binder jetting combines distributing a powder material layer via a print head with the application of a binding liquid to build products, material jetting again uses a print head to distribute materials. In contrast to binding jetting, material jetting uses natural cooling or UV lighting to stabilize the layers of material.

About That Brickmaking Job…

An age-old manufacturing process called sintering has become a foundational piece of additive manufacturing. During the very, very early days of civilization, brickmakers used heat and pressure to sinter materials into a solid brick. Modern manufacturing uses different types of sintering—such as direct metal laser sintering and selective laser sintering to produce a wide range of components and assemblies. In addition, 3D printers rely on sintering to build objects.

Rather than produce metal parts with direct metal laser sintering, selective laser sintering uses computer-controlled processes to fuse thermoplastic particles into single layers. The sintering process begins with computer-aided design (CAD). From there, the process continues by mathematically slicing a 3D CAD model into a 2D cross-sectional format that the machine can use as it builds limited run, durable, operating parts from high-grade polymers. The “selectivity” of SLS occurs through the capability of the laser to automatically and precisely target points in space defined by the 3D model. 

Within the manufacturing portion of the SLS process, a roller assembly pushes powdered material to create a uniform layer across the build piston. Then, a high-power carbon-dioxide laser scanner draws and sinters the 2D cross section onto the uniform layer of powdered material. Mechanisms within the SLS repeatedly lower the build piston and raise the powder delivery piston for the purpose of adding a new layer of material. This constant movement of the build and powder delivery pistons continues until the process has fabricated a complete part.

SLS machine within a manufacturing facility

Finding a manufacturer that can adapt and keep ahead of manufacturing evolutions is necessary.

 

Selective Laser Sintering Impacts Sustainable Design

Shifting to PCB design for a moment, selective laser sintering fits into the electronic computer-aided design and mechanical computer aided design (ECAD/MCAD) processes used for rigid-flex designs. As an example, the ECAD/MCAD processes grow from design rules that ensure that the selection of components matches with the physical clearance provided by enclosures. 

Selective laser sintering provides the physical properties, precise dimensional tolerances, complexity, and appearance needed for enclosures and assemblies that meet design requirements. From a long-term perspective, the development of additive processes such as selective laser sintering promises to deliver another aspect of sustainable designs that minimize waste and utilize processes that do not harm the environment

With the conscious efforts of the design and analysis tools available through Cadence, you and your design team are sure to be able to make any electronic hardware into a reality with the most reliable of manufacturing processes. Allegro PCB designer can be the layout and schematic option you can trust to base any design around. 

If you’re looking to learn more about how Cadence has the solution for you, talk to us and our team of experts.

About the Author

Cadence PCB solutions is a complete front to back design tool to enable fast and efficient product creation. Cadence enables users accurately shorten design cycles to hand off to manufacturing through modern, IPC-2581 industry standard.

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