Today’s designers are often focused on high density, high reliability, high speed, rugged environmental equipment. We are faced with significant growth in the demand for portable access to GPIS, Bluetooth and cellular systems. We are employing more remote equipment such as drones, robots, instant communication systems. We want rapid delivery of high quality images from surveillance systems installed in airports and city streets and even at our own doorbells.
Our military is racing ahead with expectations to retain constant contact with each and every warrior on their mission. Robotics of all sizes and functions are showing up the world over. Data being sent to and from unmounted soldiers includes everything from personal medical monitors to helmet mounted camera systems and global positions. Environmental monitors are reporting situational analysis from aircraft and shipping to satellites. Satellite circuitry is condensing to signal board computers and data processing centres.
All of these data collection and processing systems must be small, lightweight and rugged, while simultaneously routing high signal integrity from data acquisition source to information analysis and response control equipment. Electronic modules are no longer connected by a cable and connector back to the big box. Our new technologies are alive and active at the source of the information we need and it is expected to be compact and rugged.
Many of our older electronic and signal cable and connector routing systems are just too large, too heavy and cumbersome to serve these new purposes. We must recognise that circuits are now operating from 30 to 5.0 volts and less while current flow is often running below 200 millivolts to microvolts. Insulation voltages can be significantly lower than earlier cable systems. This is because older silicon diffusion chip technology has given away to newer charge coupled devices (CCD), and CMOS (Complementary metal-oxide-semiconductors)-type circuits. In addition, eGAN, (enhanced mode Gallium Nitride) circuits are offering significantly higher signal and switching speeds at the new lower voltages simultaneously with enhanced signal integrity for today’s new systems.
What are Nano-d connectors?
Nano-d connectors fit well into this new era and are designed to perform at high reliability levels in extreme environments including military applications. QPL, (qualified product specifications), and assure performance during extensive use from battlefield to satellite instruments. These smaller connectors often use a 17,200 ksi beryllium copper ‘spring pin-to-solid-socket’ design to insure signal integrity during high shock as well as continuous vibration experienced in drone to remote ground robots. As signal speeds go up, the wavelength of each signal is shorter and at lower voltages, vibration and circuit noise could confuse the signal.
Nano-d connector resistance is kept as low as 12 to 15 milliohms with a capacitance of 2.0 pf to 2.4 pf. Since most circuits have low current flow and low voltage this fits ideally. With increasing speeds capacitive coupling is also controlled by adjusting the Nano-connector insulator spacing to match the specific needs of the application. Metal connector body insures against cross-talk and reduces EMI issues at the connector.
Small diameter, low skew cable technology is also evolving to match the cable performance to the needs of higher switching and signal speed interconnects. Wire and cable have changed from higher diameters down to 30 and 32 AWG,(American Wire Gauge) of 0.01 to 0.008 inches in diameter and offer 103 to 164 ohms per foot of resistance per 1000ft and are insulated for long term reliability in Teflon.
The wiring will have a rugged limpness and perform small bend radius when used in constant motion robotic devices, as well as be light weight to reduce drag on the electrical system. High speed differential signal cable will be needed to have a matched skew between the two signal lines. (That is, with differential digital signalling, one half of the signal runs on Line A, and the other half of the signal runs on Line B.)
Signal integrity is managed by matching the electron transmission time of the two lines and is measured as a capacitance in peek-o-farads. Low skew cable is specialty ordered for these applications and carefully assembled to meet the performance needed. The Nano-d connector is designed into many light weight compact instruments used in multiple spectral frequency devices for ‘Search and Rescue’ or LiDAR, (Light Detection and Ranging) surveillance cameras.
As a result, surveillance signal processing speeds are doubling with larger image frames and the use of increased frame rates from 30 and 60 frames per second to over 100 frames per second. Digital signal data rates from 5 Gigabits/second to above 10 gigabits/second. To handle higher resolution simultaneously with higher speeds, new cable and connector designs are required to deliver quality signals to the image processor and storage systems. Soon we will see more use of hyperspectral imaging being applied in applications from food analysis to security scanning at airports.
These multispectral imaging systems actually capture a cube-like structure of many wavelength frequency bands of data that must be processed after collection. These systems will push the limits of high speed Ethernet processing as well as the interconnections serving them.
Nano-d connectors are seeing growth in the design of cube and small satellites for space. Multiples of small satellites are being launched into controlled orbits. They are kept in a constant attitude position as they travel in orbit to keep focused on the earth and also communicate with one another. Satellite construction format uses standardised printed circuit cards stacked and electrically interconnected. Nano-d connectors are very often chosen because of their format and size and low profile. They are designed with low outgassing materials, specifically tested by NASA. Retention screws are included to maintain long term mating.
Nano-d connectors match and support the evolution of upgraded medical instruments and prosthetics devices with improved portability and size reduction that helps miniaturise circuit interconnection systems and providing faster circuit speed for operating motor controls, addressing data-acquisition, and even therapy delivery through simple, comfortable cable systems. They also assist inside the instrument design by allowing circuits and interconnect systems to be attachable during the modular assembly processes.
Smaller connectors and smaller diameter wires also place a demand on the cable design to avoid EMI, (electro-magnetic interference), cyber intrusion, or electronic noise from adjoining wiring or systems. Cable designs require good shielding for each area of signal within the cable and may have two or three sections isolated from one another as well as an over-all shield system when multiple applications are squeezed into tightly packed electronics.
COTs, standard Nano-D connectors often meet many standard miniature design needs from PC board and panel mounting, to edge cards and cable to cable interfaces. Some new systems require unique modifications to the current standards. They are formatted for current standard designs and materials but can be formed into different shapes to fit unique system requirements. System designers can work directly with a connector and cable specialist and discuss on-line and jointly develop solid models that carefully adjust shapes and formats of previously proven designs. By using proven materials the newly tailored miniature connectors can continue to insure full reliability and performance but fit the new form and function of the next generation circuit designs.
What lies ahead in electronic interconnection systems?
Higher speed, massive data volume, interactive signal to data comparators, fibre to copper interface systems, micro-sensors and detectors. We are faced with gathering data from micro-bio systems that can report and even automatically adjust equipment employed to help us. The neuromodulation industry is sensing minute brainwaves and moving our prosthetic devices to help us walk. New exoskeletons are extending the strength of athletics and soldiers. Robotic platoons are being tested for capability and performance improvements while overhead we see drone constellations protecting our airspace. Other devices watch for UAVs and automatically detect and detour when not wanted. Hand held phased-array radar provide personal data not previously available while smaller munitions will include automatic ‘detect and follow’ targets.
In short, we are seeing aggressive changes towards high density, low energy, intelligent electronics that will demand miniaturisation of connector and interconnect systems.
The author is Bob Stanton, Director of Technology at Omnetics.