AND9295/D ATPAK Idea for Improving Heat Radiation 1. Overview This application note is to discuss that ON www.onsemi.com Semiconductor’s original ATPAK package is superior to DPAK (TO-252) in heat dissipation APPLICATION NOTE by using heat sink and measuring actual thermal resistance. However, this paper is not any guarantee for 3. Channel Temperature operation. Installation of heat sink is on your Power MOS Max. Power Dissipation (PD max) own responsibility. is calculated as follows: 2. Thermal Resistance Thermal resistance is the coefficient that indicates to what extent the temperature increases to an object when applying 1W heat to it. Its unit is C/W. it is common that, the lower the thermal resistance is, the better the heat dissipation performance is. Thermal design model that uses a heat sink can be shown by an equivalent circuit of series resistors (see Figure 1). In case of Surface Mount type packages like ATPAK and DPAK, because the heat dissipates almost to the underneath substrate, measurement of Case Temperature (RJC) is difficult. So, in this test, we evaluated the superiority of heat dissipation from surface by relatively comparing in the substrates with the same copper foil area. PD max = Tch max - Ta (1) RJA Tch = RJA x PD + Ta (2) Channel Temperature (Tch) can be calculated from the ambient temperature and power consumption. It is recommended that Tch is designed to be about 80% of the allowable maximum temperature (Tch max). Ta RHS Heat Sink Ts Grease Thermal resistance of heat sink RGR Case Tc Channel Thermal resistance of grease RJC Substrate Thermal resistance of the case RJA = RJC + RGR + RHS Tch Figure 1. Thermal Resistance Model © Semiconductor Components Industries, LLC, 2016 February 2016- Rev. 1 1 Publication Order Number: AND9295/D AND9295/D 5. Initial comparison of thermal resistance 4. Spec. Comparison Table 1 shows the performance comparison between ON Semiconductor’s ATPAK (ATP113) and other company’s DPAK. You can see from the table that devices with identical performance were selected as much as possible in order that the heat dissipation of the package can be compared relatively. As previously stated, we selected ATPAK and DPAK devices with almost identical spec., and measured their actual thermal resistance and made comparison. For the measurement, we used glass-epoxy substrates with the same copper foil area of 1.0x1.0inch (Figure 2). ATPAK and DPAK have almost the same footpattern, so completely the same substrate can be used. Table 1. Spec comparison between ATPAK and DPAK Parameter Symbol Condition Value Unit ATPAK DPAK Drain-Source Voltage VDSS -60 -60 V Gate-Source Voltage VGSS ±20 ±20 V Drain Current ID -35 -36 A Drain Current(PW) IDP PW ≤ 10us,Duty ≤ 1% -105 -108 A Allowable Power Dissipation PD Tc = 25C 50 56 W Channel Temperature Tch 150 175 C Zero Gate Voltage Drain Current IDSS Vds=-60V,Vgs=0V -1 -10 uA Gate Leakage Current IGSS Vgs=16V,Vds=0V ±10 ±10 uA Gate-Source Cut-off Voltage VGS(off) Vds=-10V,Id=-1mA -2.6 -2.5 V Drain-Source On-state Resistance RDS(on) Vgs=-10V,Id=-18A 29.5 30 m Chip Size same-size Package 6.5x9.5x2.3 ATPAK DPAK Figure 2. Actual Evaluation Board www.onsemi.com 2 6.5x9.8x1.5 mm mm AND9295/D Figure 3 shows the transient thermal resistance measurements. You can see from the graph that thermal resistance (RJA) of either ATPAK or DPAK is 80.3C/W, the same results are obtained, so there is no difference in the heat dissipation. 6. Comparison of heat resistance using the heat sink For ATPAK and DPAK selected and measured previously, we applied silicon grease on the surfaces of both packages and measured thermal resistances with heat sink mounted (Figure 4). Detail of the heat sink is shown in Figure 5. Figure 3. Transient Thermal Resistance ATPAK DPAK Figure 4. Actual Evaluation Board with Heat Sink www.onsemi.com 3 AND9295/D Figure 6 shows the measurements of transient thermal resistance. For DPAK, thermal resistance (RJA) is 62.5C/W; for ATPAK, it is 56.4C/W. The result shows that, even though the two packages have the same thermal resistance under the condition of no heatsink, by using heatsink, the thermal resistance of ATPAK becomes 6C/W lower than that of DPAK. 7. Summary This test suggests that ON Semi’s original ATPAK package shows more possibility of lowering the inside semiconductor chip (die) even than DPAK package in case of using heatsink due to its good heat dissipation from the surface. Therefore, ATPAK can support applications with high heat dissipation by using heatsink. 12.5 Maker : Fischer Elektronik Part No. : ICKS 10x10x12.5 Thermal Resistance : 26.3KW 10 10 2 [mm] Figure 5 Specification of Heat Sink Figure 6 Transient Thermal Resistance with Heat Sink www.onsemi.com 4 AND9295/D ON Semiconductor and the ON logo are registered trademarks of Semiconductor Components Industries, LLC (SCILLC) or its subsidiaries in the United States and/or other countries. SCILLC owns the rights to a number of patents, trademarks, copyrights, trade secrets, and other intellectual property. A listing of SCILLC’s product/patent coverage may be accessed at www.onsemi.com/site/pdf/Patent-Marking.pdf . SCILLC reserves the right to make changes without further notice to any products herein. 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