As the size of portable electronic devices continues to decrease, the associated semiconductor packages that operate them must be smaller to accommodate the ever-shrinking p. c. board real estate. Continued innovation to develop smaller, thinner surface-mount devices has been necessary. While performance requirements are often dependent on the package type and specific application, designers are looking for higher performance in smaller packages. At the same time, these new solutions must remain cost efficient to meet the high-volume production requirements of consumer electronics devices.
An extensive line of new package solutions minimizes board space while meeting a wide range of performance, cost, and size specifications. A broad array of small packages for power SMDs is now available, ranging from industry-standard solutions to proprietary packaging advances that enable designers to use less space for power components. Depending on the package and application, the designer must consider thermal characteristics and mounting stability.
SMT Power Devices
Packaging innovations for Power MOSFETs enable smaller footprints with a greatly improved performance. For example:
- VS-6 is a 6-pin surface-mount package that is the thinnest available among those in this class with the same footprint. With a thickness of only 0.85 mm (max.), it is 23% and 34% thinner, respectively, than the industry-standard SM-6 (1.1-mm) and TSOP-6 (1.3-mm) packages. MOSFETs offered in the VS-6 are targeted for dc-dc conversion and power management switching in portable electronics devices.
- VS-8 is an 8-pin surface-mount package with a 33% smaller footprint than the 6-pin VS-6 package. It improves power dissipation by 14% and reduces on-resistance by 20% using third-generation trench MOSFET technology (U-MOS III). Fig. 1 compares the VS-8, VS-6, and TSOP-6 packages. The VS-8 is ideal for power management switching and dc-dc conversion in portable computers, portable phones, PDAs, and other applications where space is at a premium.
- Thin Flat Package (TFP) MOSFETs provide a high power solution for dc-dc converters and automotive equipment. Housed in a 9-mm × 10-mm × 2.8-mm package, it requires only 42% of the footprint of the industry-standard D2PAK package. MOSFETs packaged in TFPs support high power dissipation (PD =125W), high speed, and low on-resistance, along with improved heat dissipation and stable switching operation in a 4-pin package.
- SOP-8 and TSSOP-8 packages house U-MOS III series MOSFETs targeted for high-frequency dc-dc converters using synchronous rectification. U-MOS III technology features ultrahigh density of 100,000 cells per sq in., with low on-resistance and gate charge. Devices with U-MOS III technology also include a built-in zener diode for ESD protection.
- SOP-8 Al-strap packages provide low on-resistance with high reliability. The modified SOP-8 features an aluminum strap connection between the chip and terminal, rather than a standard wire bond. This device is intended for high-frequency dc-dc converters using synchronous rectifiers that require low power losses.
A new series of small diode packages intended for use in notebook PCs, hard disk drives, cellular phones, and PDAs continues to reduce space requirements while maintaining high power output.
- S-Flat is a package series for diode and rectifiers that requires only 50% of the thickness and mount area of the industry-standard SMA package. It provides a low profile and small size while maintaining high power output — up to a maximum of 1A.
- US-Flat is a smaller variation of the S-Flat package that requires only 20% of the thickness and area of the SMA package, with maximum power output of 1A.
- M-Flat packages have the same footprint as an SMA and can be a direct replacement for those that support a maximum 5A output.
- TFP packages are for applications such as dc-dc converters that require higher power output. A TFP can support up to 30A while requiring only 42% of the area needed for the comparable industry-standard D2PAK.
The forecasts are for continued growth for power ICs, especially in ac-dc and dc-dc converters and power management solutions used in power supplies for telecom base stations, servers, hard disk drives, notebook computers, and set-top boxes, as well as in battery packs and chargers for wireless hand-held devices and PDAs. Fig. 2 is a roadmap for power IC SMD development.
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