Things move quickly at Rogers!  Just yesterday, an announcement was made that Rogers signed a definitive agreement to acquire 100% of the stock of Curamik Electronics GmbH, a manufacturer of power electronic substrate products headquartered in Eschenbach, Germany, for €116 million (subject to closing adjustments).  Today, the deal has been closed and the acquisition complete.

Curamik, founded in 1983, is the worldwide leader for development and production of direct copper bonded (DCB) ceramic substrate products used in the design of intelligent power management devices, such as Insulated Gate Bipolar Transistor (IGBT) modules. These devices enable a wide range of products including highly efficient industrial motor drives, wind and solar energy converters and hybrid electric vehicle drive systems. Most of Curamik’s products are manufactured using state-of-the-art automated processes in its facility located in Eschenbach, Germany.

Robert C. Daigle, Rogers’ Senior Vice President and Chief Technology Officer commented:

“This is an exciting acquisition for Rogers. Curamik is a recognized market-leader in power electronic substrate products for the sustainable energy market. This acquisition is a significant complement to our existing power electronic product portfolio, which includes our Power Distribution Systems and Thermal Management Solutions businesses”.

Robert D. Wachob, Rogers’ President and CEO commented;

“I am pleased to complete this acquisition as it provides the Company with significant opportunities to grow platforms in its targeted strategic markets.”

Read the full press releases about the signed agreement and completed transaction.

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Cool Running Autos: HEVs and EVs

On December 22, 2010, in HEV, TMS, by juliann

This is an excerpt from an article that ran in Power Systems Design in August 2010. This article was authored by Thomas Sleasman and Birol Sonuparlak from Thermal Management Solutions, Rogers Corporation, Chandler, Arizona, U.S.

Cooling of IGBT based power modules for Hybrid Electric and Electric Vehicles

It has been forecast that by 2020 there will be upwards of 10 million passenger and light truck vehicles sold annually that are powered entirely or in part by electric motors. Starting with the leadership of Toyota’s first Hybrid car launched in 1997, significant progress in various power train electrification designs have been made by every major OEM, especially during the last five years.

Today’s Hybrid Electric Vehicle Power Module Market

Hybrid drive systems use a combination of an internal combustion engine (ICE) and one or more electrical motors (EM). Variations in hybrid drive systems depend on how the EM and ICE of a power train connect, and also when and at which power level each propulsion system contributes to powering the vehicle.

There are two types of HEV drive systems, series or parallel. The parallel system is currently used by almost all the major OEMs. Parallel hybrid systems can be further categorized as assist, mild and full hybrid. The Toyota Prius and the Ford Escape are examples of full hybrids, as they can run on just the ICE, the EM or a combination of both. Mild hybrids on the other hand do not run on EM only. The EM provides additional power as required while the ICE still provides the primary power for the power train. Honda’s Integrated Motor Assist (IMA) is such a mild hybrid. A third hybrid drive system is the plug-in hybrid (PHEV). These should be increasingly popular in the future. PHEV allows the driver to choose the mode of operation. The driver can choose the EM mode of operation for short distance commuting or the independent ICE mode of operation for long distance driving. The PHEV’s larger battery can be charged using standard voltages from a typical power grid system.

HEV/EV Power Module Solutions – Cooling, Heat Dissipation

The efficient dissipation of heat generated by Insulated Gate Bipolar Transistor (IGBT) based power modules used to control these electric drive designs is critical to system quality and reliability. Design concepts such as integrating inverter, DC-DC converter and electronic control unit, along with reducing the number of IGBT power chips, are helping design engineers to lower the size and weight of the power train and significantly reduce the power train cost. Reducing the size and populating more components in a confined space increases the challenges of thermal management. Well engineered thermal management is required to cool electronics and maintain electrical performance within a given envelope of HEV/EV operation, and efficient thermal management provides long term reliability by minimizing thermally induced stresses.

Today, most HEV/EV inverter systems use liquid cooled IGBT power modules for thermal management. Although there are still power module designs utilizing air cooled power modules in design and production, we believe that future IGBT power modules for HEV/EV applications will continue to use more direct liquid cooled IGBT modules and move heat away from these modules more efficiently. A schematic representation of IGBT power module with pin fin heat sink is illustrated in Figure 1.

Integrated Pin Fin, direct liquid cooling base plates eliminate thermal grease interfaces between the IGBT module and the heat sink. This is a performance advantage that is realized in HEV/EV IGBT power modules beyond the standard base plate technology currently used in power modules for Rail/Traction power IGBT modules. Today, 70 to 80% of standard power modules for HEV/EV use base plates. There are also power modules on the market that do not use base plate solutions. These solutions also eliminate the solder joint between the DBC and base plate, and are present in such products as the SKAI IGBT System and Danfoss Shower Power® cooler system.

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This post authored by John Coonrod originally appeared on the RogBlog hosted by Microwave Journal.

Outgassing is a concern for any electronic equipment intended for use in high-vacuum environments. It refers to the release of gas trapped within a solid, such as a high-frequency circuit-board material. The effects of outgassing can impact a wide range of application areas in electronics, from satellites and space-based equipment to medical systems and equipment. In space-based equipment, released gas can condense on such materials as camera lenses, rendering them inoperative. Hospitals and medical facilities must eliminate materials that can suffer outgassing to maintain a sterile environment.

In the vacuum of deep space, outgassing (also known as “offgassing”) has contributed to the degraded performance of charge-coupled-device (CCD) sensors in space probes, prompting NASA to develop exacting procedures for evaluating materials prior to their use in space. NASA test procedure SP-R-0022A, for example, is used to test composite materials such as circuit-board laminates. ASTM International, a well-respected materials standards organization, has developed procedures, such as ASTM E595-07, to gauge key material parameters such as total mass loss (TML) and collected volatile condensable materials (CVCM) for the purpose of evaluating the changes in mass of different materials in a vacuum environment as would occur due to outgassing. GSFC and other NASA centers have long endorsed a policy of selecting the lowest outgassing materials available for spacecraft and space applications, testing in accordance with ASTM E595-07 which outlines a test method for evaluating the changes of mass in a test specimen under vacuum at a temperature of +125°C for 24 hours. NASA’s target number for acceptable TML is less than 1% and for CVCM is less than 0.1%.

The term “vacuum” as used in these tests is somewhat subjective. Per the standards, testing does not have to proceed at the vacuum levels of deep space, which are typically 10-12 Pa (10-14 Torr). In fact, the ASTM standard specifies only that the vacuum for performing TML and CVCM testing should be less than 7 x 10-3 Pa (5 x 10-5 Torr) for 24 hours at +125°C. The high temperature was selected to be at least +30°C above any typical operating temperature, in order to create accelerated-lifetime conditions.

After the 24-hour vacuum/high-temperature period, the standard notes that a specimen should be weighed at +23°C and 50% relative humidity to minimize the effects of water vapor on the measurement accuracy. Specimens are placed in a glass vial during the 24-hour heating period and must be weighed within 2 minutes after opening the vial to minimize the loss of absorption of water vapor when exposed to an uncontrolled humidity environment. An additional test, for water vapor recovered (WVR), can be performed after measurements of TML and CVCM. Tests can be performed on materials in their “as received” condition or after they have undergone curing.

Low levels of outgassing are usually associated with high-quality materials as well as well-controlled manufacturing processes. Various circuit-board materials from Rogers Corporation, for example, have been tested according to NASA test procedure SP-R-0022A for TML, CVCM, and WVR and found well suited for spacecraft applications. The materials include RT/duroid® composites based on polytetrafluoroethylene (PTFE) with inorganic filler materials, such as glass and ceramic fillers, and TMM® series temperature-stable hydrocarbon composites. The specimens were etched free of copper foil prior to testing, and heated at +125°C for 24 hours in a vacuum. Sample sizes were 100 to 300 mg placed in copper enclosures. The exit port of each enclosure was heated to +125°C with a chrome-plated collector maintained at +25°C spaced 12.7 mm from the exit port.

For these measurements, in all cases, the RT/duroid and TMM circuit-board materials posted impressive numbers for TML and CVCM compared to NASA’s maximum recommended values of 1.0% and 0.1%, respectively. For RT/duroid 5880 laminate materials, with PTFE dielectric, glass-microfiber filler, and low relative dielectric constant of 2.20, the TML and CVCM values were 0.03% and 0.00%, respectively. RT/duroid 6010 laminates, with a considerably higher dielectric constant of 10.2 as a result of adding glass microfiber and ceramic fillers to the PTFE dielectric, posted the same TML and CVCM values of 0.03% and 0.00%, respectively. RT/duroid 6002 laminate, with PTFE dielectric but a lower concentration of glass microfiber and ceramic filler resulting in a relative dielectric constant of 2.94, had TML and CVCM values of 0.02% and 0.01%, respectively.

For all of the RT/duroid and TMM materials tested, the TML values were well below 0.1% and the CVCM values at or near zero. The TMM laminates, which are highly crosslinked thermoset hydrocarbon dielectric materials, feature characteristically low TML and CVCM values. The TMM 3 laminates, with low relative dielectric constant of 3.27, achieved 0.04% TML and 0.00% CVCM. The TMM 10 laminates, with higher 9.20 dielectric constant, had slightly higher 0.06% TML while maintaining a 0.00% CVCM. Of the materials tested, the highest value of TML was for 3001 bonding film, a thermoplastic chlorofluorocopolymer with relative dielectric constant of 2.28 designed for bonding layers of PTFE-based circuit boards to form multilayer circuits. Still, its TML tested at only 0.13%, or well below NASA’s high limit of 1.0%, while its CVCM was only 0.01% or one-tenth that of the NASA recommended maximum value. (A complete rundown of the TML and CVCM values, along with WVR results, for the full lines of RT/duroid, TMM, ULTRALAM® laminates, and RO4003C™ circuit materials can be found in application note 2.9.1 from Rogers Corporation.)

Outgassing is not a material characteristic of concern to all circuit designers. But for those involved in electronics for satellites and other spacecraft, it is not something to be taken lightly. For circuit-board materials, the most prudent choice is the material with the lowest TML, CVCM, and WVR values available.

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Ken Kozicki from BISCO® Silicones recently authored an article for Railway Technology International about the design considerations that go into creating comfortable railcar seat cushions.  How important are first impressions for seating when a passenger steps into the railcar? Obviously, if it’s the Orient Express or another high end rail system, the feeling of luxury must be present.  But even for standard commuter railcars, seat cushions do make an impression.  Ken notes:

“…the most prevalent and obvious fixture within any interior, rendering, brochure, or maze of booth exhibits is the seat or array of seats. The type of seat will vary from the most outrageously luxurious – slated for a VIP very high speed Oriental Express pod – to the simplest and ergonomic that allows for rows and rows of passengers in a configuration that would be suitable for the rush hour of London, Shanghai or San Paulo….What has taken teams of engineers and designers months, if not years, to conceptualise, design, prototype, test (and re-test), will be given a judgment in less than ten seconds. So from that, one could wonder just how important is the first impression of a railcar seat?”

In this article, Ken look at the design considerations that need to be factored in when choosing the right seat cushion for a railcar:  Ken highlights the following:

  • the number of seating positions per coach (as required by the transit authority)
  • materials’ standards for flame, smoke, and toxicity (FST)
  • type of train service (urban metro system versus suburban commuter), and
  • severity of usage.

Ken also discusses the new concerns of sustainability and end-of-life:

“This is being driven by questions related to the disposal of the seat: “What will become of a worn, damaged, or obsolete seat?” Will it be thrown into a land-fill? What are the decomposition ramifications of that seat in a land-fill?”

All good questions.  But what about the seat itself and the cushioning material? Are some better than others?  Ken suggests yes, there are differences between one cushioning material from another:

“…cushions have differences in profile, appearance and texture, it is not obvious that there are different types of materials used to fabricate the cushions. These materials are usually in the form of foam, such as a filled-polyurethane, silicone, and melamine. The foam which is specified for the fabrication of the cushion will have been tested to the various FST standards, ensuring the safety of the passengers. In addition, some of the foam materials may have been cycletested to simulate wear and usage, which brings us back to our earlier statement of first impressions. Often, seat cushion foam materials are tested and certified to a characteristic known as indention force deflection (IFD).”

2-D & 3-D view of thin profile seat with loaded urethane

“A typical IFD test method will be comprised of a disk of a determined diameter that compresses the foam material a certain percentage of its thickness, and then measures the amount of “pushback” force the foam has. This is its indention force deflection, and is directly related to the comfort of the seat. In production, the foam will be certified according to this test. If it is within the IFD tolerance range, the foam will be qualified for seat cushion fabrication.”

Of course, Ken highlights that the bigger test happens after many months of wear on the cushion, after the “pushback” force has been worn down.  Different materials, like silicone foam, do a better job over the life of a cushion than other materials.

To read Ken’s final recommendations, either view the article here (in a magazine viewer) or download a full PDF of the printed article.

Related Links

BISCO Material Selection Guide

Floating Floor Design Tool

Silicone Material Selection Guide

On December 2, 2010, in BISCO Silicones, by sharilee

Selecting materials for gasketing and sealing means taking a close look at critical specs, such as temperature, flammability, toxicity, vibration isolation, and sound damping. To make the process easier, the Silicone Material Selection Guide walks you through the options, helping you pick the right materials for your application.

Fire, heat, tearing, elasticity, EMI/RFI shielding – there are a lot of issues to consider. Hybrid Electric Vehicles (HEV), for example, need materials for environmental seals, vibration pads, antenna seals, battery cell cushions, and more. The goal is a design that performs at its peak over an extended period of time. This requires materials that keep harsh environmental elements out and provide low compression set and long term stress relaxation.

For mass transit applications, foam cushioning is one of the largest single combustible components. As a result, strict regulations are in place to ensure cushions meet flame spread, smoke density, and hazardous emissions standards.

Whether your design calls for resistance to temperature extremes, low flammability, or high tear strength, start your search with the Silicon Material Selection Guide. The Guide features BISCO Silicones — cellular, solid, and specialty materials that can be fabricated into gaskets, heat shields, fire stops, seals, cushions, and insulation for a wide variety of applications.

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Rogers Corporation’s New PORON® ShockSeal™ Foam takes the Pain out of Dropped Handheld Devices

PORON® World’s Greatest Foam

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