1. Introduction
For 20 years, the 94*34mm packaged IGBT module has become the industry standard. Since then, major companies have continued to develop their own packaging forms while being compatible with this standard. Now, Nanjing Yinmao Microelectronics has launched a 34mm thin low-inductance module (hereinafter referred to as T1 package) that is compatible with the standard packaged substrate. It incorporates new design, new materials, processes, and new chip technology, which makes the traditional standard power module more reliable and has optimized electrical performance.
Figure 1 Comparison of the form factor of T1 package and traditional package
2. Materials
The T1 packaged module's casing is made of high-strength materials, and the terminals undergo a rigorous electroplating process to ensure the casing's robustness during long-term use at high temperatures. It also features a unique cover design to ensure safety during use.
3. RoHS process
The new module is manufactured using lead-free processes, and the terminals and DBCs are produced using solderless processes, making it a green product that meets RoHS requirements.
4. Terminal solderless process
5. Power cycling capability
Figure 4. Module power cycling capability under different TC variations
6. Novel low-inductance power terminal design
Figure 5 Comparison of T1 terminal and conventional terminal
The T1's new terminals do not require soldering to connect to the DBC and do not need to consider stress, so the traditional S-shaped design is eliminated, reducing the terminal length by 1/3, thereby reducing the module's parasitic inductance and terminal resistance. Compared to traditional 34mm package terminals, the inductance is reduced by 30%, greatly optimizing turn-off characteristics and reducing power consumption at the terminals during use. The nickel plating on the copper terminals ensures that oxidation is not easily formed during long-term use.
Figure 6 Installation of the new type of terminal
The novel terminal design reduces internal installation space. Eliminating the need for soldering effectively saves chip placement space on the DBC, resulting in a more optimized chip layout, higher module current density, and a balanced circuit design. The signal terminals utilize DBC routing and bonding technology, optimizing signal symmetry and reducing gate parasitic inductance and resistance compared to traditional flying wire soldering.
7. Switching characteristics
Nanjing Yinmao Microelectronics has launched low-loss, fast, and standard IGBT modules using a new T1 package design. These modules are suitable for systems with different requirements, such as frequency converters, motor control, welding machines, and UPS. By testing the dynamic characteristics of the modules at high temperatures, it was found that the new thin-terminal, welder-free package design greatly improves the switching losses, RBSOA, and voltage change rate during turn-off of the devices.
GL90HF120T1-turn off BSM75GB120DLC-turn off
Figure 7 Comparison of shutdown characteristic waveforms of T1 package and standard package (Tj=125℃)
The figure above shows the turn-off waveforms of the two devices measured under the same test setup and conditions. The voltage change rate of T1 can be derived from the figure.
△Vc1=180V; the voltage change rate of the DLC △Vc2=220V. Therefore, the calculation shows:
T1 packaged module;
di/dt = 72A/0.386us = 187A/us
△Vc1=L1*di/dt
L1=△Vc1/di/dt=180V/187A/us=960nH
DLC standard package:
di/dt = 72/0.320us = 225A/us
△Vc2=L2*di/dt
L2=△Vc2/di/dt=220V/225A/us=978nH
Since identical devices have the same inductance, the two types of modules produce different inductances, with the difference being:
△L=978-960=18nH
Overcurrent shutdown feature (RBSOA)
GL90HF120T1-RBSOA BSM75GB120DLC-RBSOA
Figure 8 Comparison of RBSOA characteristics (Tj=125℃, Ic=2*Ic*nom; Vcc=600V)
Frequency characteristics
The thin, low-inductance package design reduces the switching losses of the module, and the optimized chip space layout reduces thermal resistance, ensuring that the module has excellent frequency characteristics.
Figure 9 Comparison of output current at different frequencies
8. The new packaging is more suitable for high-frequency, high-speed IGBT modules.
In applications where switching frequencies exceed 20kHz, power devices are typically required to have excellent switching performance. However, due to the different systems used by these power devices, the main circuits and control methods also vary. Often, not only are high-speed chips on the module required, but also optimal packaging and design at high frequencies. Therefore, the advantages of T1 packaging are particularly prominent in high-frequency devices, providing greater scope for the use of medical equipment and inverter welding machines.
GF75HF120T1-turn on GF75HF120T1-turn off
Figure 10. Turn-on and turn-off characteristics of a 1200V/75A fast IGBT (Tj=125℃)
Testing the switching losses of the GF75HF120T1 at high temperatures reveals that, at Vcc=600V and I <sub>C</sub> =75A, E<sub>on</sub>=6.8mJ and E<sub>off</sub>=3.2mJ, with a total switching loss of only 10mJ. This significantly reduced loss results in better dynamic characteristics of the device at high frequencies.
9. Optimize installation space
To ensure optimal heat dissipation for the module, good contact is crucial between the substrate and the heatsink. The substrate is mechanically curved, and the pressure generated when mounting the module substrate onto the heatsink guarantees this contact. The standard 80mm hole spacing allows users to install the module directly without altering the heatsink's mounting holes. The slim housing, only 21.5mm high, reduces the module's mounting height for customer system designs, shortening the wiring and copper busbars used for power terminals. While not significantly different from traditional installation methods, the new solderless terminals require less and more even force during installation, necessitating careful and meticulous handling.
in conclusion:
With the development of the power market, there is an increasing demand for miniaturization and high power density in various systems such as frequency converters, inverter welding machines, and UPS. This inevitably requires new power devices to develop towards miniaturization. Nanjing Yinmao Microelectronics' T1 thin-package module significantly reduces internal inductance and thermal stress, saving space for system designers. Equipped with new chip technology, it will unleash greater potential in the power market and represents a significant improvement over traditional packaged modules.
