{"id":31848,"date":"2019-06-13T17:00:27","date_gmt":"2019-06-13T17:00:27","guid":{"rendered":"https:\/\/www.padtinc.com\/2019\/06\/13\/3d-printing-polymer-parts-with-electrostatic-dissipative-esd-properties\/"},"modified":"2019-06-13T17:00:27","modified_gmt":"2019-06-13T17:00:27","slug":"3d-printing-polymer-parts-with-electrostatic-dissipative-esd-properties","status":"publish","type":"post","link":"https:\/\/www.padtinc.com\/2019\/06\/13\/3d-printing-polymer-parts-with-electrostatic-dissipative-esd-properties\/","title":{"rendered":"3D Printing Polymer Parts with Electrostatic Dissipative (ESD) Properties"},"content":{"rendered":"\n

Getting zapped by static electricity at the personal level\nis merely annoying; having your sensitive electronic equipment buzzed is\nanother, highly destructive story. <\/p>\n\n\n\n

Much as you\u2019d like to send these components out into the\nworld wearing their own little anti-static wristbands, that\u2019s just not\npractical (and actually, not good enough*). During build and use, advanced\nelectronics applications need true charge-dissipative protection that is\ninherent to their design and easy to achieve. However, the typical steps of\npainting or coating, covering with conductive tape, or wrapping with\ncarbon-filled\/aluminum-coated films incur both time and cost.<\/p>\n\n\n\n

Electrostatic dissipative (ESD) polymer materials instead provide this kind of protection on a built-in basis, offering a moderately conductive \u201cexit path\u201d that naturally dissipates the charge build-up that can occur during normal operations. It also prevents powders, dust or fine particles from sticking to the surface. Whether the task is protecting circuit boards during transport and testing, or ensuring that the final product works as designed throughout its lifetime, ESD materials present low electrical resistance while offering the required mechanical, and often thermal and\/or chemically-resistant properties.<\/p>\n\n\n\n

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ESD-safe fixture for testing a printed-circuit board, produced by 3D printing with Stratasys ABS-ESD7 material. (Image courtesy of Stratasys)<\/figcaption><\/figure><\/div>\n\n\n\n

Combining ESD Behavior with 3D Printing<\/strong><\/p>\n\n\n\n

All the features that are appealing with 3D printing carry\nover when printing with ESD-enabled thermoplastics. You can print trays custom-configured\nto hold circuit-boards for in-process testing, print conformal fixtures that\nspeed up sorting, and produce end-use structures for projects where static\nbuild-up is simply not allowed (think mission-critical aerospace applications).\n<\/p>\n\n\n\n

Acrylonitrile butadiene styrene (ABS), that work-horse of\nthe plastics industry, has been available as 3D printing filament for decades.\nAlong the way, Stratasys<\/a>\nand other vendors started offering this filament in a version filled with\ncarbon particles that decrease the plastic\u2019s inherent electrical resistance.\nStratasys ABS-ESD7 runs on the Fortus 380, 400, 450 and 900 industrial systems,\nand soon will be available on the office-friendly F370 printer.<\/p>\n\n\n\n

What kind of performance does ABS-ESD7 offer? When\nevaluating materials for ESD performance, the most important property is\nusually the surface resistance, measured in ohms. (This is not the same as surface\nresistivity, plus there\u2019s also volume resistivity \u2013 see Note at end). Conductive\nmaterials – typically metals – have a surface resistance generally less than 103<\/sup>\nohms, insulators such as most plastics are rated at greater than 1012<\/sup>\nohms, and ESD materials fall in the mid-range, at 106<\/sup> to 109<\/sup>\nohms.<\/p>\n\n\n\n

Compared to standard ABS filament, ABS-ESD7 offers more than five orders of magnitude lower resistance, converting it from an insulator to a material that provides an effective static-discharge path to the outside world. Due to the inherent layered structure of FDM parts, the differences in properties between flat (XY) and vertical (ZX) build orientations produces a range of resistance values, with a target of 107<\/sup> ohms, reflected in the product name of ABS-ESD7. Stratasys offers an excellent, easy-to-read FAQ paper about ABS-ESD7.<\/p>\n\n\n\n

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Printed-circuit board production tool, custom 3D-printed in Stratasys ABS-ESD7 material for built-in protection from electrostatic discharge during test and handling. (Image courtesy of Stratasys)<\/figcaption><\/figure><\/div>\n\n\n\n

When ABS isn\u2019t strong enough or won\u2019t hold up to temperature extremes, engineers can turn to Stratasys\u2019 ESD-enhanced polyetherketoneketone (PEKK), termed Antero 840CN03. Developed in 2016 and slated for full release in October 2019, this new filament expands the company\u2019s Antero line of \u00a0high-temperature, chemically resistant formulations. The PEKK base material offers a high glass transition temperature (Tg 149C, compared to 108C for ABS-ESD7) while meeting stringent outgassing and cleanroom requirements. As with ABS-ESD7, the carbon-nanotube loading lowers electrical resistance values of Antero 840CN03 parts to the desirable \u201cESD safe\u201d range of 106<\/sup> to 109<\/sup> ohm. <\/p>\n\n\n\n

Setting up Parts for Printing with ESD-Enhanced Filament\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/strong><\/p>\n\n\n\n

Support structures in contact with part walls\/surfaces can disturb the surface resistance behavior. To counter-act this condition for filament printing with any type of ESD material, users should perform a special calibration that makes the printer lay down slightly thinner-than-usual layers of support material. In Stratasys Insight software, this is currently accomplished by setting the Support Offset Thickness to -0.003; this decreases the support layers from 0.010 inches to 0.007 inches. In addition, supports should be removed (in Insight software) from holes that are smaller in diameter than 0.25 inches (6.35mm). <\/p>\n\n\n\n

As more of these materials are developed, the software will be updated to automatically create supports with this process in mind.<\/p>\n\n\n\n

ESD Applications for 3D Printing<\/strong><\/p>\n\n\n\n

Avionics boxes, fixtures for holding and transporting\ncircuit boards, storage containers for fuel, and production-line conveyor\nsystems are just a few examples of end-use applications of ESD-enabled\nmaterials. Coupled with the geometric freedom offered by 3D printing, three\ncategories of manufacturing and operations are improved:<\/p>\n\n\n\n