Conformal Coating for Traction and High Reliability Applications

Introduction
Electronics used in traction inverters are subject to a great variety of environmental conditions including dirt, corrosion, moisture, and chemicals. Additionally, high-voltage applications, above 3000V, require larger creepage-clearance distances to meet UL specifications. To avoid premature failure and ensure safe operation, the printed circuit board assemblies (PCBA) inside the inverter must be well protected.

Conformal Coating
Conformal coating adds a thin lacquer to all surfaces of the PCBA covering all exposed metal contacts. This service, that AgileSwitch provides for all of our products, can dramatically reduce the volume of an expensive enclosure and increase the dielectric withstand voltage of the product.

AgileSwitch recommends HumiSeal UV40 UV curable coating for a good balance of protection and cost. This material is MIL-I-46058C qualified, and IPC-CC-830 and RoHS compliant and recognized under UL File Number E105698. This material has excellent dielectric withstand voltage properties, humidity resistance, and chemical resistance. AgileSwitch also has experience with Humiseal 1A33 polyurethane and IB33 acrylic materials. Customers may also specify a material of their choice.

Approach
There are two approaches to conformal coating PCBAs: automated and manual.

Automated Process:
AgileSwitch issues a list of coating specifications, including material, thickness, and keep-out areas, to our subcontractor. The subcontractor programs a PVA Delta 6 Selective Coating/ Dispensing System with our specifications. The boards are washed in a batch cleaner and placed on a conveyor belt in the PVA machine. Each board is carried under an computer-controlled nozzle and the conformal coating is dispensed. The final coating is precise, repeatable, and very little material is wasted. This process does not require any manual masking.

You can see this process in action below on an AgileSwitch Gate Driver:

Top Side


Bottom Side


Manual Process:
The manual process follows a more conventional approach. Each board is cleaned in a batch cleaner and then a technician masks the keep-out areas using tape. Then, the boards are sprayed in a well ventilated area and cured. After curing, the masking tape is manually removed from all the boards to reveal the keep-out areas. This process is sufficient for many applications, but it requires hours of pre- and post-processing, it is not repeatable, and there may be inconsistencies in the coating thickness and coverage.

Summary
AgileSwitch offers conformal coating as a service for any of our products and highly encourages customers to use conformal coating for all high reliability applications.

Please contact AgileSwitch for more information.

AgileSwitch featured on PSDtv at PCIM 2017

In this episode of Power System Design TV from PCIM Europe 2017, Rob Weber, CEO of AgileSwitch discusses their portfolio of IGBTs and SiC MOSFET Drivers. And now introduces their full range of Stack Electronics.

IPM Reference Designs

We teamed up with Mersen and FT Cap, experts in bus bars, cooling, and capacitors, to develop SiC MOSFET and Si IGBT reference designs. AgileSwitch Intelligent Gate Drivers and Stack Electronics are featured in each stack.

The SiC design uses 62mm power modules from Wolfspeed or Semikron in a very compact 16kW/L, 150kW rated package, beating the DoE's 2020 target. The target application is heavy-duty vehicles.














The IGBT design is targeted for Energy Storage applications. It is built around Infineon's PrimePACK IGBT5 with .XT technology. The demonstrator achieved 25kW/L at 500kW.

For more information, please contact Mersen.

http://ep-us.mersen.com/news/news/news-article/mersen-and-partners-beat-next-generation-doe-power-density-targets-through-stack-reference-designs-8/

New AgileSwitch SiC Gate Driver Optimized for 62mm Modules

Patented Augmented Turn-Off™ switching technique, robust high-noise-immunity design, advanced monitoring and fault reporting facilitate conversion from IGBTs to 62mm SiC MOSFET power modules

Philadelphia, PA—February 16, 2017—AgileSwitch, LLC, innovator of intelligent IGBT and SiC MOSFET gate drivers, introduces the 62EM (62mm Electrical Master) SiC MOSFET gate driver series. The easy-to-use, plug and play driver is compatible with most 62mm SiC MOSFET modules. Applications including heavy-duty traction vehicles, auxiliary power units in trains, buses and trolleys, induction heating systems and other high-power industrial systems are rapidly moving from IGBTs to SiC power devices. The 62EM Series is designed specifically to facilitate this conversion. 

The 62EM driver incorporates AgileSwitch’s patented, software configurable Augmented Turn-Off (ATOff™) technology. ATOff addresses two significant impediments to the successful implementation of Silicon Carbide modules in high-power applications. By reducing turn-off spikes and ringing, both under normal operation as well as short-circuit (DSAT) conditions, SiC MOSFET modules can be safely operated in the higher frequencies that enable dramatic increases in power conversion density. This allows SiC MOSFET modules to be operated closer to their rated specifications, resulting in size, cost and performance improvements. The 62EM gate driver is designed for harsh, high-noise environments, with optional conformal coating. It is equipped with powerful diagnostic and troubleshooting tools and it continuously monitors critical parameters, such as temperature and DC link voltage.

“Designers want the benefits of switching at higher speeds using smaller, lighter, less expensive system components. But, today, this can only be achieved by reducing the switching efficiency, which effectively negates much of the benefits,” said Rob Weber, AgileSwitch CEO. “The 62EM Series enables them to have both higher switching frequencies and high efficiency by dramatically reducing the typical secondary effects of high switching frequency: voltage overshoots, ringing and false short circuit reporting.”

A whitepaper describing the performance improvements attained using ATOff is available for download.

Price: $128.94 (OEM quantities)
Delivery: 2 Weeks, ARO

AgileSwitch Receives Patent for SiC MOSFET Switching Technology

The patented Augmented Turn-Off (ATOff™) switching technique addresses two significant impediments to the successful implementation of Silicon Carbide modules in high-power applications. By reducing both turn-off spikes and ringing both under normal operation as well as short-circuit conditions (DSAT), SiC MOSFET modules can be operated in the higher frequencies that enable dramatic increases in power conversion density.

 A whitepaper describing this technology and test results can be found here.

 Patent No. 9,490,798

AgileSwitch to get patent for SiC module switching Tech

Power Systems Design reports today that "AgileSwitch, innovator of intelligent IGBT and SiC MOSFET gate drivers, announced that it has “allowed patent claims” related to its proprietary ATOFF (Augmented Turn-Off)) switching technique. The firm expects the formal patent to be awarded within the next 60 to 90 days."

Read the full article here: Power Systems Design article

Advanced Protection for Silicon Carbide (SiC) Power Semiconductors

Protecting the power semiconductor is a continuous process and AgileSwitch Gate Drivers have a unique capability in this regard. The driver boards from AgileSwitch are able to reduce the stress on the Power Semiconductor while reducing switching losses, through the use of Augmented Turn-Off

Under normal operating conditions, the gate voltage in a turn-off cycle steps through an intermediate level before reaching the off voltage level. Under short circuit conditions, the gate voltage steps through multiple intermediate levels before reaching the off voltage level.

A detailed explanation of the benefits of Augmented Turn-Off can be found here.

In addition to this continuous process, what else do we protect against?

• Power Supply Under Voltage or Over Voltage
• Over Current (Short Circuit)
• Overtemperature 
• DC Link Overvoltage