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PCBD-June2015

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20 The PCB Design Magazine • June 2015 nents to plastic components where solder is al- lowed to climb the lead and touch the body of the component. This criteria has been in 610 for at least four revisions, so to make it a little less ambiguous due to the number of new compo- nents being introduced it was decided to make a difference between plastic and other body ma- terials being used for the fabrication of compo- nents. Additionally, since this is the chapter on surface mount components, there are changes in the Class 3 requirement for chip components to have minimum end overlap expanding on the definition of billboarding and its acceptabil- ity for certain size chip components. There is also the new requirement for the solder charge terminations, which are a butt joint component that is being introduced for use in Class 3 products. Although the debate is still ongoing, this is a new component which may end up being used on Class 3 products. The voiding criteria in BGA balls was changed from 25, to 30%, and it also discusses cham- pagne voids at the board to BGA solder ball in- terface which will impact product reliability if not watched carefully. The criterion for bottom thermal plane termination was also expanded to clarify the requirement. Finally the addi- tion of criteria for "P" style terminations, a new component being introduced which is applied by sliding it over the edge of the circuit board and soldering the terminations on both sides of the board. Section 10 was modified to bring it into line with IPC-A-600, Acceptability of Printed Boards. If you'd like to get involved with IPC stan- dards such as IPC-A-610, the standards commit- tees always welcome new volunteers. Check the EPTAC website for more information about IPC- A-610 and related training. PCBDESIGN IPC-A-610: WHAT'S NEW WITH REV F? continues feature Leo Lambert is vice president and technical director of the training company EPTAC Corporation. Researchers at Missouri university of science and Technology are giving new meaning to the term "read the fine print" with their demonstra- tion of a color printing process using nanoma- terials. The researchers describe their "no-ink" printing method in the latest issue of the journal Scientific Reports and illustrate their technique by reproduc- ing the Missouri s&T athletic logo on a nanome- ter-scale surface. The researchers' printing surface consists of a sandwich-like structure made up of two thin films of silver separated by a "spacer" film of sili- ca. The top layer of silver film is 25 nanometers thick and is punctured with tiny holes created by a micro- fabrication process known as focused ion beam milling. The researchers created a scaled-down tem- plate of the athletic logo and drilled out tiny perfo- rations on the top layer of the metamaterial struc- ture. under a scanning electron microscope, the template looks like a needlepoint pattern of the logo. The researchers then beamed light through the holes to create the logo using no ink – only the interaction of the materials and light. This allowed researchers to create different colors in the reflect- ed light and thereby accurately reproduce the s&T athletic logo with nanoscale color palettes. "unlike the printing process of an inkjet or laserjet printer, where mixed color pigments are used, there is no color ink used in our structural printing process – only different hole sizes on a thin metallic layer," says Dr. Jie gao, an assistant professor of mechanical and aero- space engineering at Missouri s&T and a co-author of the paper. "No-ink" Color Printing with Nanomaterials

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