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SEPTEMBER 2019 I DESIGN007 MAGAZINE 53 to design the board correctly in the first place. Well, there is. Standards, such as IPC-A-610, lay out many of the PCB acceptability requirements that you need to know to design a board that can be manufactured correctly. One portion of this standard covers everything you've ever want- ed to know in order to design your board for good solder joints. IPC-A-610 is a vast docu- ment, but like a detailed map, it will give you the direction you need. Protection Of all the benefits that a colorful standard offered on the battlefield, the one that seems the most attractive to me is in its protection. A soldier who was separated from their battalion could look up and find where they needed to go to come under the protection of the group. Interestingly enough, today's standards offer that same sort of protection. If you want elec- tronics that you know are certified for use, you may look for a UL standard. And if you want to know if a board can be sold or distributed in the European Union, you would look to see if it was RoHS-compliant. Certification to different standards will tell you if the circuit board that you are using can be used in the manner that you want it to be used. For the PCB designer, however, there's more to the protective nature of standards than just that. When you lay out a PCB, you are responsible for how that board will eventually be manufac- tured. As I pointed out earlier, a standard can give you excellent direction when you don't know how something should be designed. At the same time, though, a standard can also give you a threshold that shouldn't be crossed. If you are being asked to design something and you aren't sure if you should push the level of tolerances that far, don't be afraid to say that what you are being asked to do will violate the standard. And if you are pushed over that threshold, then document that you were re- quired to violate the standard so that there will be no question in the future about why you did what you did. Conclusion I hope that this insight will be helpful to you the next time you are tempted to grumble or groan about having to adhere to a particular standard. Today's design standards provide a necessary level of identification to our work, give us direction on how best to accomplish our work, and protect us and our work as long as we take the time to follow them. I would even say that working with standards should become part of our regular standard operating procedure (SOP). And now I believe that there is a new stan- dard that I need to explore—one that involves some dessert and a quiet evening. Until next time then, keep on designing. DESIGN007 Tim Haag is a PCB design consultant based in Portland, Oregon. To read past columns or contact Haag, click here. Researchers at the University of Göttingen have devel- oped a new method that takes advantage of the unusu- al properties of graphene to electromagnetically interact with fluorescing (light-emitting) molecules. Led by Professor Enderlein, re- searchers used a single sheet of graphene, just one atom thick (0.34 nm), to modulate the emis- sion of light-emitting (fluorescent) molecules when they came close to the graphene sheet. The excellent optical transparency of graphene and its capability to modulate through space the molecules' emission made it an ex- tremely sensitive tool for measuring the distance of sin- gle molecules from the graphene sheet. The accuracy of this method is so good that even the slightest distance changes of around 1 ångström. (Source: University of Göttingen) Graphene Layer Enables Advance in Super-Resolution Microscopy

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