Efficiently packaged: SMT DC/DC converters in 3D Power Packaging from RECOM

Packaging refers to the housing of sensitive electronic components to make them easier to physically handle, for example by inserting a "naked" chip into a moulded housing with pin connections to produce an IC. Conventional circuit assembly technologies are based on discrete components being placed – manually or automatically, depending on requirements – onto a PCB using through-hole or surface mounting technologies, with the same components often being available in a variety of packaging options.

As the demand for ever-increasing performance in ever-smaller package sizes grows, the right component package has become critical to the overall performance specification. Smaller components, however, are more difficult to handle. The higher switching and operating frequencies used in designs with high power density have led to the introduction of new IC packaging technologies and assembly methods specifically designed to meet the more exacting requirements. One of these is the space-saving 3D Packaging technology.

3D Power Packaging – which makes use of stacked, embedded and planar components – enables significant size reduction without compromising performance or features. But the reduced size does more than just increase the power density: disruption factors and current loops have also been diminished, allowing electromagnetic interference (EMI) to be controlled even at switching frequencies in the megahertz range. As a result, however, thermal management becomes more critical. The performance and temperature characteristics of a DC/DC converter, for example, are strongly dependent on the form in which the converter is used in the final application.

Despite increasing requirements in terms of performance and power density, low-power-consumption DC/DC converters have to be affordable. Over time, many form factors have been experimented with, often involving SMT circuit boards. SIP versions are frequently used, but these make assembly more difficult, as the THT components used have to be wave-soldered or even hand-soldered.

As an alternative to THT DC/DC converters, RECOM has developed models that, like other modern SMT components, can be assembled and soldered with a low profile. To realise the advantages of a converter module over a discrete design, the footprint had to be kept as small as possible. This can be achieved with the aid of 3D Power Packaging: by utilising the Z-axis for construction in vertical layers, the manufacturer creates the highest power density in its class.

The RPM, RPMB and RPMH series stand as examples of higher output currents for a 30W device in a thermally optimised 25-pad LGA package (size: 12.19 x 12.19 x 3.75mm). A multilayer internal circuit board ensures the power density, while vias provide good thermal conductivity and efficient use of available space.

The 3D construction of the RPM series consists of a four-layer circuit board with a baseplate shielded and enclosed on six sides by a metallic housing to achieve a very low EMI. This construction, although very elaborate, offers significant advantages: it needs only about 1.4cm² of space for proper heat dissipation and delivers full performance at ambient temperatures above +85°C. Moreover, the complex design is completely contained in a single module. End users can thus utilise a low-cost, two-layer PCB without expensive plugged vias and still integrate a powerful, compact SMT on-board power supply that does not require forced-air cooling.

At Schukat electronic, a wide selection of RECOM series that use the new packaging technology is available. In addition to the non-isolated LGA power modules, the distributor now offers the following DC/DC converters, and others, direct from stock:
• Non-isolated QFN power modules (RPX series)
• Isolated 12W converters in a SIP8 package (RS12-Z series)
• Surface-mount isolated converters (R1SX, R2SX, R1DX, R1ZX series)
• Isolated converters in a SOIC-16 package (R05CT05S series)

For advice and support on the products and applications, please contact our technical power supply sales team.