Design007 Magazine


Issue link:

Contents of this Issue


Page 68 of 81

MAY 2023 I DESIGN007 MAGAZINE 69 › Plating: We are seeing more require- ments for wire bonding on flex. Electro- plated so gold or ENEPIG are the best choices. ENIG is the most common for standard assembly. Ultimately, aer working with your manu- facturer and going through this list, you should end up with a material stack that meets all your requirements. Flex circuits and rigid-flex are a more com- plex solution than a standard printed cir- cuit board. ere are far more processes and components to consider vs. a rigid PCB. You must partner with a vendor that has industry knowledge and relationships, experience with the materials, and a full understanding of your environment and requirements. DESIGN007 Michael Morando is director of sales and marketing for PFC Flexible Circuits. the circuit may be in a particular section of the circuit only. Share the location of the bend and the number of times the circuit will bend. Your vendor should propose to reduce thicknesses in the required areas by adjusting the material thicknesses. › Temperature: What temperature is the flex going to encounter? High tempera- tures affect the adhesives used. Make sure to discuss the environment with your ven- dor. We have used aluminum for heat dis- sipation. › Stiffeners: FR-4 is the most popular stiffener material. It is used for stiffening SMT areas, through-hole connectors, and for ZIF connector interfaces, but we have used additional polyimide as a stiffener, and ceramic and stainless steel, depending on the requirements. › Coverlay and soldermask: Coverlay (polyimide layer and adhesive over traces) is used in most flex areas, but now with the shrinking of components, the use of sol- der mask in dense areas has become more common. Remember: Solder mask can crack when bent. It sounds like something from science fiction: Don a specialized, electronic headband and control a robot using your mind. But now, recent research published in ACS Applied Nano Materials has taken a step toward making this a reality. By designing a special, 3D-patterned structure that doesn't rely on sticky conductive gels, the team has created "dry" sensors that can measure the brain's electrical activity, even amidst hair and the bumps and curves of the head. Most non-invasive versions involve the use of "wet" sensors, which are stuck onto the head with a gloopy gel that can irritate the scalp and sometimes trigger allergic reactions. As an alter- native, researchers have been developing "dry" sensors that don't require gels, but thus far none have worked as well as the gold-standard wet variety. When combined with an augmented reality head- set displaying visual cues, the electrodes could detect which cue was being viewed, then work with a computer to interpret the signals into com- mands that controlled the motion of a four-legged robot—completely hands-free. Though the new electrodes didn't yet work quite as well as the wet sensors, the researchers say that this work repre- sents a first step toward developing robust, easily implemented dry sensors to help expand the appli- cations of brain-machine interfaces. (Source: ACS) A Sensor That Might Someday Enable 'Mind-Controlled' Robots

Articles in this issue

Archives of this issue

view archives of Design007 Magazine - Design007-May2023