3M Electronics: Connectivity, Shielding and Insulation

Electronics Prototyping: more than just the board

James Fordham, Industry Sector Marketing Manager at RS Components takes a look at some of the unsung technologies that are essential for delivering a working prototype

The democratisation of the design process and increased availability of new technologies is enabling engineers from companies of all sizes to achieve the concept-to-creation of a prototype product in a substantially faster time. RS is putting all the key tools in place to help that process with free PCB-design and 3D-modelling software tools, a host of design resources, and fast access to all the necessary products and technologies to aid the process including some rather overlooked and unsung heroes. When considering a new project, naturally the overall board design takes primary place along with the processing power needed, usually subject to trade-offs to meet energy consumption requirements. Then there are other factors including memory demands, interface options, power supply and form factor. But there are also key technologies that could be crucial to delivering a fully working product: physical connectivity, EMI shielding and electrical insulation. Innovation in these fields is just as competitive as in other areas of electronics design with many world-leading companies vying for market share. 3M is one of them, and for some decades now, the company has been a pioneer in developing cable-to-board interconnect technologies, EMI shielding and advanced insulation solutions.

Connectivity

3M has developed numerous platforms and customer solutions based on a foundation of ribbon cable, IDC sockets and mating headers, which work to simplify the cable termination process and reduce total cost of ownership. A key feature of IDC devices is the ability to terminate large numbers of conductors quickly, accurately and repeatedly. IDC sockets have also proven to be robust, reliable and effective, generally providing a quick, lower cost and more accurate wire termination compared to crimping or soldering. The connectors are ideally suited to wire-to-board and internal wiring applications across a wide range of markets including factory automation, medical, test and instrumentation, network communications and computers and peripherals.

Two example IDC solutions are 3M’s 158 series of ribbon-cable sockets and the 159 series of shrouded headers, which provide manufacturers and cable-harness builders numerous options in designing a variety of electronic systems. The 158 series offers a wide selection including: 30-micro-inch gold-plated devices with an adhesive backed cover for robust termination, improved strain relief and discrete wire capability; and 30/15-micro-inch gold-plated connectors with a pre-assembled cover and packaged using 3M's ‘sword pack’ technology to enable higher speed termination operations than traditional separated cover termination methods. The 159 series of shrouded board-mount headers maximise design flexibility, minimise PCB footprint and mate to the 158 ribbon cable sockets, which are available in vertical-mount, through-hole, surface mount and extended shroud versions.

Other popular connectivity solutions with engineers are the 451 and 452 ribbon-cable connector systems, which are incredibly small-size systems that deliver high-density connectivity and increased design freedom for applications where space is at a premium. Pin-for-pin, they are 75% smaller than comparable 0.100-inch solutions with latch/eject header nearly the same size as box header, and terminate to a broad range of existing 0.025-inch pitch cables.

Just to complete the list of connectivity solutions, the ribbon-cable connector systems described above are compatible with a broad range of 3M ribbon cables. For example, 3M HF625 Series LSZH Round Conductor Cable features 28 AWG stranded conductors on 1mm pitch permitting mass terminations and long-term connection to a broad line of metric IDC connectors.

Shielding

In the development of electronics products, it is clear that standards need to be met for both electromagnetic radiation emissions and noise interference. Shielding reduces the EMI field around electronic components by using barriers made of conductive or magnetic materials. This shielding needs to be applied to enclosures and cables to isolate electrical devices from their environment.

Widely used in the industry are shielding tapes, which are suited for applications that require reliable point-to-point electrical contact, particularly EMI shielding, grounding and static charge draining. Typical applications include shielding around electronic cabinet doors and panels, individual electronic components, and cables.

For more than four decades 3M has been delivering adhesive-backed foil tapes for EMI shielding and grounding applications with proven long life, stability and effectiveness for backings and adhesives. Particularly popular are 3M’s 1170 (aluminium) and 1181 (copper) series of smooth-backed foil tapes. These establish secure electrical contact with the application surface by means of a unique adhesive. This adhesive uses broadly distributed conductive particles to provide a multitude of low-resistance paths between the backing and the substrate. In addition, the 1245 (copper) series offers a backing that is impressed with an embossed pattern that protrudes through the acrylic adhesive to make direct electrical contact with the application surface. This provides a reliable ‘through-the-adhesive’ conductivity system with stable contact resistance and a high level of shielding effectiveness.

Insulation

The final item is insulation: clearly, it is important to insulate wires and other materials that conduct electricity to prevent short circuits, risk of electrocution or fire. Electrical insulation tape is widely used in the industry and can be made from a range of different plastics including vinyl, which is the most popular as it stretches well and provides effective and long-lasting insulation.

Popular in the industry are 3M’s polyester film and vinyl insulation tapes, including a variety of polyester tapes for applications requiring a thin and durable tape with high dielectric strength, which can withstand higher temperatures than tapes with acetate cloth backings. They are also conformable, exhibit excellent chemical, solvent and moisture resistance and resist cut-through and abrasion. This means they perform well in environments with high levels of moisture or humidity, for example in the food production and pharmaceutical industries. In addition, 3M’s Temflex vinyl electrical tapes perform well over a range of temperatures and combine the flexibility of PVC backing with excellent electrical insulating properties and high dielectric strength. These tapes also provide high resistance to moisture, UV, abrasion, corrosion and both alkaline and acidic substances.

  CLICK HERE TO SEE 3M CONDUCTIVE AND INSULATION TAPES ON OUR  ELECTRONICS WORKBENCH PAGE