In recent years, the growing number of safety and comfort systems in vehicles has resulted in the space for these systems becoming increasingly limited and the demand for smaller components increasing. To meet these requirements, there is growing interest in MOSFETs with floor electrodes whose dimensions can be further reduced with the same high current.
In order to guarantee the quality of automotive applications, an optical inspection is carried out during assembly. In the case of components with bottom electrodes, however, the solder height cannot be inspected after assembly. This makes it difficult to guarantee the quality of the solder joints. Rohm is now the first company to use its proprietary Wettable Flank technology to ensure the 130 µm electrode height required for automotive applications. The result is consistent solder quality, even for products with bottom electrodes, so that automatic inspection machines can easily check the soldering conditions after assembly.
With Wettable Flank technology, a cut is made in the lead frame on the underside of the housing before coating. However, burrs can occur which occur more frequently with increasing height of the cut. In order to minimize this burr formation, Rohm developed a process that introduces a barrier layer on the entire surface of the lead frame. This process not only prevents the erection of components and soldering errors during assembly, but also guarantees an electrode height of 130 µm on the underside of the DFN161616 package (1.6 mm x 1.6 mm) for the first time.