The Package Impact
Ohmic and thermal Resistance of MOSFETs
In the past semiconductor manufacturers have spent a lot of effort to minimize the RDSon of MOSFET chips. However, the effective RDSon of a packaged device is the sum of chip-RDSon and ohmic package resistance. Because bond-wiring of the chips contributes significantly to the total resistance, manufacturers have recently introduced bond-wireless i. e. laminar contacting technologies e. g. with copper clips.
Low ohmic resistance is the prerequisite for low loss operation. But for a real device switching and conduction losses still generate heat in a MOSFET. This heat has to be dissipated to the ambient. One important mechanism to lead heat away from a MOSFET is heat conduction. For good heat conduction the thermal resistance Rthjc between heat source and package should also be as low as possible.
Vishay’s TrenchFET® GenIV MOSFETs feature excellent values for RDSon and thermal resistance:
| Type | Polarity | Voltage Class | Rdson mΩ | Rthjc K/W | Package | Datasheet |
| SQJQ140E | N | 40 | 0,53 | 0,25 | PowerPAK® 8x8L | |
| SQJQ144AE | N | 40 | 0,9 | 0,25 | PowerPAK® 8x8L | |
| SQJ138EP | N | 40 | 1,8 | 0,48 | PowerPAK® 5×6 | |
| SQJQ184E | N | 80 | 1,4 | 0,25 | PowerPAK® 8x8L | |
| SQJ180EP | N | 80 | 3,3 | 0,3 | PowerPAK® 5×6 | |
| IAUT300N08S5N012 | N | 80 | 1,2 | 0,4 | TOLL 10×12 |
For comparison reasons the table includes a part in TO leadless package from another supplier.
Conclusion
Vishay’s TrenchFET® GenIV MOSFETs deliver previously unseen values of conductivity in packages smaller than TOLL.
Last update: 08.01.2021
