Research On Heat Dissipation Of Silicon-based Gallium Nitride HEMT Package

AlGaN/GaN high electron mobility transistor has the advantages of wide energy gap(about 3.4ev),high breakdown voltage,high critical breakdown electric field,high electron saturation drift rate,high peak electron speed,high electron saturation rate,etc.,so it is widely used in power electronics and high frequency communication.Because Gan power devices are normally open,they can only be turned off under negative pressure,and short circuit through becomes a big hidden danger.So the normally closed cascaded Gan power devices come into being.As a high-power device,the heat output of general devices is very large,while that of long closed Gan power devices is much higher.If the package can not dissipate heat in time,the junction temperature of the device will rise dramatically,and Schottky will be deteriorated.In addition,Gan also has excellent electronic properties.It can form a modulated and doped AlGaN / GaN heterostructure with AlGaN.And propose a cascode GaN power device that can realize normally closed cascode(cascode)type in TO-220 F package First,this thesis focuses on the application of AlGaN / GaN HEMT(high electron mobility transistor)power devices,which requires high power and heating density,so it is important to study the thermal analysis of AlGaN / GaN HEMT package.In different packaging conditions,the thermal resistance calculation and ANSYS Icepak simulation are used to obtain a better packaging mode.Power components must have power loss under electrical operation,and most of the lost power will be converted into heat form through heat conduction from components to packages and then heat convection to the external environment.Second,cermet packaging is a very common packaging form of broadband GaN HEMT RF power devices on the market at present.However,compared with plastic packaging,this packaging form has high processing temperature and low cost performance,and the process automation and thin packaging ability is not as good as plastic packaging.Therefore,this thesis uses DFN(bilateral flat lead-free package)packaging form to package the chip.In conclusion,this thesis compares the advantages and disadvantages of single GaN HEMT device and cascaded GaN HEMT device packaging,verifies the actual situation through ANSYS software simulation,tests and analyzes the infrared thermal imager,and makes the finished GaN HEMT RF device in DFN(4 * 4)packaging form,and conducts electrical test.The main contents are as follows:1)Model the bare core with ANSYS finite element simulation software to obtain the heat source distribution of the device,and then model the single GaN HEMT device and the cascaded GaN HEMT device,and simulate the heat source distribution of the device.The main position of the heat source of the whole device is at the gate and the bias drain end of the gate,which provides a theoretical basis for the simulation.The problems in the fabrication of cascaded GaN power devices are analyzed,and the cascode structure is proposed,which solves the hidden danger that GaN power devices can only be turned off under negative pressure conditions,and provides a good reference for manufacturing normally closed GaN power devices.2)This thesis analyzes the impact of ceramic packaging and plastic packaging on the packaging of GaN HEMT radio frequency devices,and proposes a feasible packaging method to produce finished GaN HEMT radio frequency devices in DFN(4*4)packaging.The test results show that 6mm gate The breakdown voltage of a wide radio frequency device can reach up to 309 V,and the device will reach a stable state after a certain number of switches,and the drain current will not change significantly.