An experimental investigation of a heat pipe integrated power module
A novel flat plat heat pipe (FPHP) integrated in high power module instead of metal substrate is developed. Compared with the metal subtrate, the FPHP uses two-phase boiling heat transfer to diffuse heat flux in power module.Thus the FPHP diffuses significantly the collect heat source to the more larger condensation area. Analyze the use of a FPHP as a heat spreader to spread out the heat from the die to the heat sink.The transient and steady heat transfer performance of the FPHP was experimentally measured.The experiment indicates that the FPHP of isothermal and high convection coefficient can improve the heat transfer capacity for the integrated power electronic module (IPEM), which make thermal resistance decrease 30 percent. The maximum thermal flux density of IGBT die is obtained to 186 W/cm2. IPEM based on FPHP can avoid the power uprush and raise the ability of resisting thermal impact.
Fabrication of vapor-deposited micro heat pipe arrays as an integral part of semiconductor devices
Vapor-deposited micro heat pipe arrays (VDMHP) were fabricated as an integral part of semiconductor devices to act as efficient heat spreaders by reducing the thermal path between the heat sources and heat sink. Fabrication of the VDMHP was accomplished by first establishing a series of grooves in a silicon wafer. Orientation dependent etching (ODE) using a KOH-1-propanol-H/sub 2/O solution on a (100) wafer with a (111) flat covered with an oxide mask, resulted in grooves 25 /spl mu/m wide and 25 /spl mu/m deep with sharp, perpendicular edges. The wafers were predeposited with a layer of chromium followed by a layer of gold to improve the adhesion characteristics. Dual electron beam vapor deposition, followed by planetary process using molybdenum crucibles, were used to deposit copper 31.5-33.0 /spl mu/m thick, and provide complete closure of the grooves. A glass cover slip was bonded on the top of the deposited layer. The grooves were finally charged and sealed. A computer model Simulation and Modeling of Evaporated Deposition Profiles (SAMPLE) was used to optimize the metal step coverage and successfully predict the cross-sectional profile of the VDMHP. >
Numerical analysis and experimental observation of guidewire motion in a blood vessel model.
We have developed a computer-based system to simulate a guidewire in blood vessels for surgical planning, intra-operative assistance, and to facilitate the design of new guidewires. In this study, we compared simulation results with experimental results for validation of the simulation system. First, we inserted a commercial guidewire into a poly (vinyl alcohol) hydrogel blood vessel model using a two-axis automatic stage and measured the position of the guidewire tip and the contact force between the guidewire and the vessel. The experimental apparatus can be used not only for the validation of numerical analyses, but also as a simulation system. Second, similarly to the experiment, the motion of the guidewire in the blood vessel model was calculated when the proximal part of the guidewire model was pushed and twisted. The model of the guidewire is constructed with viscoelastic springs and segments, and the proximal part of the guidewire model is constrained by the fixed catheter model. Collisions between the guidewire and the vessel are calculated, and the contact forces are determined according to the stiffness of the vessel wall. The same tendency was seen in the trajectories and the contact force of both the experimental and simulated guidewire tips.