Below are the questions asked during the presentation, along with their respective answers.
Q: I am using a cold plate. Can I consider its temperature as ambient in my analysis?
A: Yes, as long as the cold plate’s temperatures does not change regardless of the thermal load.
Q: Is there a specific type of heatsink that is used with thermal gap fillers?
A: Thermal gap fillers do not require any specific heat sink or surface.
Q: Is there a rule of thumb to calculate the XY thermal resistance of gap fillers?
A: Unfortunately, since we design thermal gap fillers for one-dimensional heat transfer we do not know the x and Y. We assume it is homogeneous conductivity.
Q: When you reference these are going to be in service a long time, how long is that to you?
A: We have extrapolated data that estimates the life of our gap fillers at 17 years at 125C.
Q: What is the thinnest material you can make? What limits the minimum bondline thickness?
A: .2mm is our thinnest thermal material.
Q: How does pressure affect the thermal resistance of the thermal gap filler?
A: Increasing pressure on the thermal interface will always recue thermal resistance.
Q: Do you complete application testing on your samples? What type of testing do you do? Do you see resistance change over time?
A: All our thermal interface materials are tested up to 1,000 hours at 150C, -40C, heat shock, 60C/90%RH
Q: What are the most critical questions you ask customers when helping with material selection?
A: Heat flux and compression range.
Q: What electronic thermal simulation software is recommended for both pcb and enclosure? Does Fujipoly have material models for this software?
A: ANSYS and Flotherm both make very popular thermal analysis software.
Q: Which test method are you using to measure the conductivity of homogeneous Fujipoly materials? ghp, tps etc. or thermal imaging cameras?
A: We use Hotwire, Hot disk as well as ASTM5470D.
Q: What are the typical materials that could be used for next generation TIMs for high heat flux applications?
A: Graphene is of interest.
Q: What minimum thickness can we get with gap fillers?
A: A gap filler if less than .5mm will be difficult to use due to control of the gap. Gap has to be .45mm but no less than ~.3mm.
Q: What is the mechanism for reducing the thermal resistance as pressure increases?
A: Reduction in contact resistance at lower pressures. At higher pressures the gap filler will deform and reduce the gap between the heat source and sink.
Q: How can you measure the thermal interface of a gap filler?
A: Typically you will apply a thermal load over a given area and measure the T gradient between the two surfaces. This will give you a thermal resistance of Cin2/W.
Q: How to calculate thermal resistence when we are using heat spreader with thermal interface material.
A: You can treat the heat spreader as one bulk resistance and apply it to the resistive network. Heat spreader vendor may have this data.
Q: Can there be any issue with corrosion using Silicone filler material?
A: No issue with corrosion with thermal fillers used in thermal interface materials sold by Fujipoly.
Q: But there is a limit for pressure upon the component, so can we go beyond that limit?
A: Managing the pressure that component sees is critical and at times more ff a challenge than the thermals. Addressing the compression should be addressed early.
Q: Can only a TIM be used to heat source without heat sink? If so, is TIM efficient?
A: No, A TIM is designed to transfer heat form one surface to the other. A heat sink is designed for convection. The geometry of the heat sink is critical. A gap filler alone would not make a good heat sink.
Q: Are there any TIMs that are re-usable that have full recovery (shape memory) of compression from Fujipoly?
A: Yes, but they tend to be less compliant and lower conductivity. We do offer Rubber type TIMs. https://www.fujipoly.com/usa/products/sarcon-thermal-management-components/thin-film-profiles/
Q: How does the material “extrude” under pressure – is that a consideration during design?
A: Typically gap fillers will bulge, and flow in the case of putty types. The material should be allowed to flow and bulge. Anything that interferes with that will increase the stress.