Evaluation of PMDE Compact and Highly Heat Dissipating Package for Si DiodesSummary

Key Points of This Article

・The new “PMDE” package is a successor to the previous “PMDU” package.

・The PMDE package reduces footprint by roughly 40% from that required by the PMDU package, yet back electrodes about 1.5 times larger to secure comparable allowable dissipation of the package, while mounting strength is improved by a factor of 1.4.

Key Points of This Article

・The PMDE package has an allowable dissipation comparable to that of the PMDU package, while reducing the footprint by roughly 40%, and increase the mounting strength by 1.4 times.

・Due to the wireless structure, there is no risk of wire fusion caused by a surge current, so that a high surge current rating (I_FSM) is achieved.

・Through greater exposure of the back electrodes, the PMDE package directly and efficiently dissipates heat to the PCB.

Key Points of This Article

・In the PCB mounted state, as the copper foil area increases, heat is spread more readily, so that heat dissipation improves.

・If the copper foil area is too small, the PMDE R_th(j-a) value becomes larger than that for PMDU, and adequate heat dissipation is not exhibited.

・As the copper foil area increases, the PMDE heat dissipation performance improves, exceeding that of the PMDU package.

・The thicker the copper foil, the smaller the copper foil area at which the PMDE heat dissipation performance exceeds that of the PMDU package.

・If the copper foil area is made larger than necessary, the heat dissipation performance reaches saturation, and an effect equivalent to the area is no longer obtained. Hence an appropriate size should be chosen for the copper foil area.

Key Points of This Article

・In these comparative evaluations, the PMDE package had a package temperature Tc and an efficiency comparable to those of the PMDU package, despite its compact size.

・It can be inferred that if efficiencies are similar, Tj values will also be similar, indicating that the PMDE package, while compact, exhibits heat dissipation performance similar to that of the PMDU package.

Key Points of This Article

・The PMDE package is being adopted in numerous product types, particularly SBDs.

・Hereafter there are plans to use the package with FRDs, ZDs, TVS diodes, etc. as well.