Mini/Maxi IPM isolation, clearance and creepage
This article explains the FAQs related to the isolation, clearance and creepage of IPM mini/maxi.
1. What is the isolation rating in the Datasheet of IPM mini and IPM maxi?
Ans: The Isolation rating indicates the degree of isolation between each IPM pin and the connected heat sink.
2. Does the isolation rating in the module section of the IPM datasheet explains insulation of the control and power sections?
Ans: No, it does not describe the isolation level between the control and power sections.
3. How is the isolation test performed on a IPM module?
Ans: To perform an isolation test on the IPM module, the heat sink is connected to the IPM module and all IPM pins are shorted with a conductor and then the voltage is applied between the heat sink and all shorted pins for 1 min which is shown in Figure 1.
4. Can the IPM isolation rating increase?
Ans: Yes, it is possible to improve the isolation rating of the IPM by increasing the distance between the pins of the IPM and the heatsink. This is achieved by using a recommended heat sink shape, as shown in Figure 2. The creepage distance is the distance from the IPM pins to the heatsink measured along with the surface of the IPM. For IPM maxi, the creepage distance is 1.62 mm with the conventional heat sink shape, while the creepage distance is increased by 4.1 mm with a recommended heat sink. Similarly, the clearance is the distance between the heat sink and the IPM pins measured through the air. With a conventional heat sink, the clearance is 1.6 mm, but with the recommended heat sink the clearance is improved as shown in Figure 2.
5. How to comply with the IEC60335-1, IEC60664-1, IEC67800-5-1, UL840 standards for pin to heat sink(earthed) using IPM module?
Ans: These standards are provided in the AN2019-16 Application notes. Infineon Technologies AG suggests using the recommended heat sink shape as shown in Figure 2 to comply with the suggested standards. Figure 2 is an example with the IPM maxi IM828 package (DIP 36X23D).
Figure 1. Isolation test
Figure 2. IPM with recommended heatsink shape