5SHY6545L0001 AC10272001R0101 5SXE10-0181 IGBT power module

The provided text discusses thermal resistance in water-cooled systems, emphasizing the importance of managing thermal resistance within high-power modules. The discussion includes considerations for the three main resistances in series within the system and the impact on thermal performance.

Thermal Resistance in Water-Cooled Systems:

1. Three Comparable Resistances:
   • First Resistance (Internal to Module): Located inside the module between the chip junction and the casing (baseplate bottom).
   • Second Resistance (Contact to Cooler): Contact resistance to the cooler surface.
   • Third Resistance (Cooler Surface to Ambient Air): Resistance between the cooler surface and the ambient air.
2. Concerns about the First Resistance:
   • The first resistance (within the module) is of primary concern, especially in traction applications.
   • To reduce thermal resistance, materials must be thin and thermally conductive.
3. Material Selection:
   • ABB modules use aluminum silicon carbide (AISiC) for the baseplate and aluminum nitride (AlN) insulating substrates.
   • AISiC and AlN are chosen for their excellent thermal cycling capability and low thermal resistance.
4. Impact of Coefficient of Thermal Expansion (CTE) Mismatch:
   • Significant CTE mismatch in materials may lead to delamination, impacting soldering areas below the substrate.
   • Delamination observed in scanning acoustic microscopy (SAM) image after thermal cycling.
5. Solder Thickness and Cycling Capabilities:
   • A solder thickness of 0.2 mm is considered necessary for high cycling capabilities.
   • Thinner solder layers induce stress, while thicker layers impact overall stress levels due to higher CTE.
6. Potential Improvements:
   • Implementation of distance holders to address substrate tilting during the process.
   • Consideration of solder with a higher melting point for better resistance against creep.
7. Thermal Mass Considerations:
   • Reducing material thickness reduces thermal resistance but also decreases thermal mass close to the junction.
   • Impact on factors such as reliability and surge current capability due to changes in power flow.
8. Active and Passive Cycling Tests:
   • Active tests involve passing a current through the modules to induce thermal cycles and stress bondwire connections and chip metallization.
   • Longer cycles serve to stress solder joints and assess the module’s ability to withstand thermal cycling.

Conclusion:

The text provides insights into the challenges and considerations related to thermal resistance in water-cooled systems, highlighting material choices, CTE mismatch issues, solder thickness impact, and the importance of active and passive cycling tests for reliability assessment. If you have further questions or need additional information, feel free to ask.