electrical and electronic | Innovation
both ends of a cable are the same. Moreover, with wall thicknesses at only 25% of previous generation connectors, they are much smaller.
With USB Type C connectors being so small, the performance properties of the materials used for their housings are especially critical. Stanyl (polyamide 46) and Stanyl ForTii (polyamide 4T) have CTI (Comparative Tracking Index) ratings well above 400V, a measure of their ability to provide electrical insulation. DSM says that connectors in alternative materials such as LCPs and even some rival high performance polyamides short circuit during CTI testing, resulting in a serious
Figure 1: LED Luminaire polymer conversion roadmap Source: PolyOne
conductive Makrolon grades are set to be launched soon. Numerous polymer producers, as well as com-
pounders, are in fact taking an increasing interest in the market for thermally conductive compounds. In late 2014, for example, Celanese acquired the assets of Cool Polymers, a leading US compounder of conductive polymers with strong technical capabilities in the LED market. Solvay Engineering Plastics is also readying a range of thermally conductive polyamide compounds, set for launch ahead of the next K show. “We see good prospects for these types of materials, and not just in LEDs, they are branching out into other areas,” says James Mitchell, global director for the E&E market.
USB connections DSM is currently putting a strong emphasis on the suitability of its high temperature polyamides for very demanding applications in electronics. It says that its Stanyl PA46 and Stanyl ForTii PA4T have been approved by numerous global producers for use in the next generation of USB Type-C connectors. It says they answer the need for improved levels of safety and reliability. USB (Universal Serial Bus) is the industry bus
Right: Covestro says its thermally
conductive Makrolon TC8030 PC
grade provides good thermal management in LED compo- nents such as heat sinks
76
standard for transferring data and power to and from digital devices. Device charging over USB has become a major consumer feature in recent years. But even though it is a standard, there are numerous types of USB plugs and sockets. The electronics industry has come under considerable pressure to develop a standardised charging interface, so that one charger and its associ- ated cable can be used for multiple devices. As a result, the USB Type-C connector will be obligatory from 2017. Several electronics OEMs have already launched equipment that incorporates Type-C ports. The Type-C connector has a reversible design
allowing it to function perfectly whether it is plugged in right-side up or upside down. In addition, the plugs at
COMPOUNDING WORLD | August 2016
www.compoundingworld.com
performance and safety issue for the complete device. It claims its materials do not.
Stanyl and Stanyl ForTii can be used to produce connectors with wall thicknesses as thin as 0.12 mm and which still have the required high mechanical properties. Their high fl ow in combination with high weld-line strength ensures the required high pin pull-out strength—the force needed to pull metal contacts out of the housing— and parts successfully pass durability tests that involve mating and unmating plugs and sockets more than 10,000 times.
USB Type-C connectors are extremely complicated
assemblies of plastics and metal. Different producers are considering slightly different manufacturing routes, but one favored option, at least for the socket, is to use a process that involves sequential insert moulding. A “preform” is fi rst made, which has a set of contacts embedded in it, and then this is used in a second insert moulding process in which additional metal compo- nents are incorporated into the assembly. With two-stage insert moulding, it is advisable to use a thermoplastic in the fi rst stage that has a melting point higher than that used in the second stage, to ensure that no remelting occurs that could cause the fi rst set of inserts to shift position. But the second material still needs to have a melting point high enough to resist the temperatures involved in any possible subsequent high temperature soldering process. DSM says that an ideal solution is to use PA 4T for
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