ROHM Unveils Tiny Automotive Grade MOSFETSNovember 12, 2020 by Gary Elinoff
Wettable flanks assure easy optical inspection, improved heat dissipation and better mounting reliability
Three new MOSFETS from ROHM come in DFN1010 packages measuring only a scant 1.0 by 1.0 millimeters.
Image courtesy of ROHM
ROHM’s three new MOSFETS, the RV8C010UN, RV8L002SN and BSS84X, are AEC-Q101 qualified and are aimed at high-density automotive applications that demand the utmost in miniaturization. Bottom electrodes fit the bill, and they also provide excellent heat dissipation.
Side Wettable Flanks
But, there’s one problem. The image below compares a classical terminal leaded package to a Bottom electrode DFN package.
Modified image courtesy of a ROHM video
The reader will note the solder connections to the terminal leaded package is clearly visible to Automatic Optical Inspection (AOI), but those of the bottom electrode DFN package is not. This would require manufacturers to rely instead on more expensive inspection methods, greatly increasing manufacturing costs.
But, the problem can be solved with side wettable flanks, as illustrated below:
Image courtesy of ROHM
On the left side, it can be seen that the soldered connection is hidden under the package and not visible, and cannot be verified optically. On the top right side, it can be seen that the electrode extends up the side of the device's electrode. Then, as illustrated on the bottom right, the solder fillet that forms on the side, electrically and mechanically marrying the device to the PCB, is clearly observable. It is perhaps too small for the naked eye, but clearly visible to AOI.
Compared to SOT-23 package
ROHM claims that the tree new MOSFETs perform as well as devices available in 2.9 × 2.4 mm SOT-23 packages but that they reduce the mounting area by approximately 85%. In addition, the high heat dissipation of the bottom electrode structure improves heat dissipation by up to 65% over SOT-23.
Electrical characteristics of the new MOSFETs
The BSS84X is a positive polarity device, with drain-source voltage (VDSS) of -60 volts, drain current (ID) of -0.25 amps, and drive voltage is -0.25 volts.
RV8C010UN and the RV8L002SN are negative polarity units. The RV8C010UN’s VDSS, ID and drive voltage are specced at 20, 1.0, and 1.2 volts, respectively. For the RV8L002SN, the corresponding numbers are 60, 0.25, and 2.5 volts.
Inner circuit for the RV8C010UN and the RV8L002SN. The BSS84X exhibits opposite polarity. Modified image courtesy of RV8C01UN datasheet
Power dissipation is specified at 1.0 watts for all three devices.
For all three units, the important drain-source ON Resistances vary with VGS. Typical values range from:
- RV8C010UN from 340 to 700 mΩ
- RV8L002SN from 170 to 300 mΩ
- BSS84X from 280 f to 350 mΩ
ESD protection is specified at up to 2 kV human body model (HBM) for the RV8C010UN and for the RV8L002SN.
- Automotive electronic control units (ECU)
- ADAS applications
- Drive recorders
- Car infotainment
As described, the length and width of all three devices are 1.0 mm. Height is 0.4 mm, with tin-plated solderable side pads of a minimum height of 0.125 mm.
Operating junction storage and temperature range is from -55 to +150 ℃