Posted on 27 November 2019

Strong Competence in Materials Enables more Efficiency

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Small, smaller, smallest - that's the main message TDK Technologies has. The company is convinced that it has achieved another milestone regarding the on-going miniaturisation. In addition to the ultra-flattest multilayer varistors for ESD protection, TDK claims to have the world's smallest common-mode choke for automotive Ethernet and the smallest automotive-grade MLCCs in the mega cap class. Addionally, there are more NTC sensor solutions available.

By Marisa Robles Consée, Corresponding Editor; Bodo's Power Systems

ESD protection devices are needed wherever there is electronics. The demand on high safety and reliability is not only a topic of telecommunication and industrial electronics. More and more smartphones and tablets require ESD/EMI protection in order to achieve high data rates. Automotive ECUs are demanding high system integration in applications sensitive to ESD. "Miniaturized ESD guards at interfaces and connectors offer greater safety for more complex designs", Dr. Oliver Dernovsek, Director Multilayer Product Development of the Piezo and Protection Devices Business Group of TDK Technologies, is convinced. That's the reason why the company has started a R&D project with the Austrian printed circuit board manufacturer AT&S in order to develop technologies for embedding active and passive electronic components. The aims of the partnership include driving forward standardisation of these technologies, which play a decisive role in the fabrication of extremely miniaturised modules.

The new CeraDiodes are about 80 percent smaller than their predecessors and simultaneously offer reliable ESD protection

Ultra-flat multilayer varistors for ESD protection

Facing the technical challenge of higher functional density together with higher data rates in mobile communications, the company has developed a series of ultra-flat and compact multilayer varistors for ESD protection. The smallest CeraDiode device has a footprint of 0.47 mm x 0.47 mm at a height of 0.1 mm in LGA packaging. These new SMD protection components are available in EIA case sizes of 0402, 0201 and even smaller. This enables the production of varistors about 80 percent smaller than their predecessors for reliable ESD protection. The CeraDiodes have an ESD immunity of 15 kV or 25 kV which more than satisfies the higher requirements on the ESD protection of sensitive ICs. Their clamping voltage is 70 V or 90 V at a pulse voltage of 8 kV (IEC- 62019-4-2). Thanks to their low capacitance, the signal integrity of high-speed interfaces such as HDMI is not impaired.

TDK has achieved this breakthrough in the miniaturization of its protection components by combining an efficient semiconductor material with its micro core technology. The new ZnO material also possesses significantly more grain boundaries per volume which increases the ability of the components to absorb ESD pulses by a factor of 50. These micro core components can also be incorporated directly into 3D circuits and modules. Size, performance and cost can make the CeraDiodes an attractive alternative to TVS diodes.

Common-mode choke for automotive Ethernet

The new series of common-mode chokes for automotive Ethernet ACT45L features fairly high common-mode noise suppression.

With the ACT45L series, TDK presents a common-mode choke that features satisfactory common-mode noise suppression

Measuring in with a footprint of 4.5 mm x 3.2 mm and an insertion height of just 2.8 mm, the "miniaturized series is the world's smallest common-mode choke for automotive Ethernet and fulfils the standard´s stiffest requirements", states Norbert Peters, Director Product Marketing Europe of the Magnetics Business Group of TDK. Mass production has started in November 2013. "Ethernet, which supports data rates of up to 100 Mbit/s, is quickly becoming the networking protocol of choice for high-speed multimedia infotainment applications in cars", he adds. Because it employs lightweight unshielded twisted-pair (UTP) wires, automotive Ethernet can save space and weight. The specifications of the new automotive Ethernet standard with regard to common-mode noise suppression are significantly more demanding than the requirements of CAN and FlexRay. "The higher the noise attenuation, the better the performance of the commonmode choke." According to TDK, the ACT45L's noise suppression of the is 15 dB to 25 dB better than that of existing products over a frequency range of up to 100 MHz.

The ACT45L series is designed to be manufactured using fully-automated processes that include a high-precision autowinding process and the bonding of ferrite cores with a highly temperature- and moisture-resistant adhesive. The result is a series of automotive components qualified to AEC-Q200 with suitable reliability and consistent quality.

Automotive-grade MLCCs

"As more and more electronic control units are deployed in and near the engine compartment, the capacitors used in such harsh environments must be extremely heat-resistant, reliable and compact", says Marc Frankenberg, Manager Product Marketing Europe of the Ceramic Capacitors Business Group of TDK. Therefore, TDK has expanded its CKG series of Megacap-type MLCCs to include miniature 1608 to 3216 packages (EIA 0603 to 1206). Until now these MLCCs were available only in 3225 to 5750 packpackages (EIA 1210 to 2220). With dimensions of 1.9 mm x 1.3 mm x 1.5 mm, to be "the world's smallest automotive-grade MLCCs in the mega cap class".

TDK has expanded its CKG series of Megacap-type MLCCs to encompass miniature 1608 to 3216 packages (EIA 0603 to 1206)

The expanded series offers even higher reliability thanks to their high-precision metal cap fitting structure that enables mounting without adhesives or solder. The novel lead frame design is supposed to offer resistance to thermal and mechanical stress. Moreover, the new MLCC series has a wider and higher capacitance range from 0.1 μF to 22 μF and rated voltages from 16 V to 630 V. The structural design of the CKG series of Megacap-type MLCCs allows for an operating temperature range of -55 °C to +150 °C and high reliability for use in ECUs.

"Until now it was extremely difficult to create Megacaptype MLCCs with lead frames in such miniature case sizes", the expert says focussing on the fully-automated high-precision assembly process of TDK.

Material know-how enables new NTC temperature sensors

The new manufacturing technologies can also be applied to larger sizes. The devices are available as single or stacked types. Customer-specific multiple stacked types are available on request. The mass production is scheduled to start in April 2014.

NTC sensor technology

Finally, the generation of NTC temperature sensors fulfils the requirements of the RoHS directive without exception and "are simultaneously characterized by their high precision and durability", claims Holger Hegner. The Executive Vice President NTC Sensors of the Sensors Business Group of TDK adds: "The development of ever more exact temperature sensors is driven especially by the increasing demands on temperature measurement in automotive and industrial electronics applications. The overriding goal is to further boost the energy efficiency of motor vehicles as well as equipment and installations." To ensure that temperature sensors continue to operate reliably even under harsh conditions, the requirements on their ruggedness and durability are continuously increasing.

The devices are halogen and lead-free, and their measurement accuracy has supposedly been increased by a factor of ten. The devices' high resistances are due to ion migration at the terminals.


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