Ultra-compact automotive MOSFETs bring mounting reliability

In recent years, the growing number of vehicle safety and convenience systems such as ADAS cameras has emphasised the challenge of limited space to accommodate these systems and spurring the demand for smaller components. To meet this need, bottom electrode type MOSFETs that can be miniaturised while maintaining high current are increasingly attracting attention.

However, for automotive applications optical inspection is performed during the assembly process to ensure quality, but in the case of bottom electrode components solder height cannot be verified after mounting, making it difficult to confirm mounting conditions.

ROHM has a proven track record of developing and introducing new products ahead of market trends, and such is the case with the new ultra-compact MOSFETs. This time, ROHM has become the first in the industry to ensure the electrode height on the side of the package (130µm) required for vehicle applications by utilising original Wettable Flank formation technology.

The result is a consistent solder quality, even for bottom electrode type products, enabling automatic inspection machines to easily verify solder conditions after mounting.

ROHM is committed to developing compact products that leverage this technology, including bipolar transistors and diodes, allowing us to expand our extensive product portfolio and achieve greater miniaturisation while providing higher reliability.

Key features fo the ultra-compact MOSFETs

1. Proprietary Wettable Flank technology guarantees an electrode height on the side of the package of 130µm: ROHM’s Wettable Flank formation technology involves making a cut into the lead frame on the side of the package before plating. However, burrs resulting from cutting into the lead frame can occur more frequently as the height of the cut increases.

In response, ROHM developed a unique method that introduces a barrier layer on the entire surface of the lead frame to minimise the occurrence of burrs. This not only prevents component rise and solder defects during mounting, but is the first on the market to ensure a 130µm electrode height on the side of DFN1616 (1.6x1.6mm) packages.

2. Compact bottom electrode MOSFETs reduce mounting area: Until recently, Schottky barrier diodes (SBDs) were commonly used in the reverse connection protection circuits of ADAS camera modules. But due to the larger currents required by high resolution cameras in advanced vehicle systems, SBDs are increasingly being replaced by compact MOSFETs that provide low ON resistance and less heat generation.

For example, at a current and power consumption of 2.0A and 0.6W, respectively, conventional automotive MOSFETs can reduce mounting area by 30% over SBDs. However, adopting bottom electrode MOSFETs capable of providing excellent heat dissipation while still supporting large currents in an even smaller form factor makes it possible to decrease mounting area by as much as 78% compared with conventional SBDs and by as much as 68% compared with conventional MOSFETs.