Monden K.,Japan Central Research Institute of Electric Power Industry |
Okajima Y.,Shibukawa Plant |
Yashima K.,Shibukawa Plant
Journal of Japan Institute of Electronics Packaging | Year: 2011
An insulated metal substrate (IMS) is a circuit board comprising an insulating layer on a metal base plate. The insulating layer is made from epoxy resin incorporating dense ceramic fillers. The thermal conductivity of the insulating layer is calculated from measurements of the thermal resistance of the substrate. The influence of percolation on the thermal conductivity of an insulating layer is considered. The thermal conductivity as a function of the volume fraction of filler is estimated. Based on these experimental and numerical results, the equivalent thermal conductivity of the filler is evaluated. It is thought that the control of filler size and shape is important for the achievement of high thermal conductivity of an insulating layer. In addition, an improved equation for assessing the thermal conductivity of an IMS is proposed. The predictive values agree with experimental results.
Tanimoto M.,Tokyo Institute of Technology |
Yamagata T.,Shibukawa Plant |
Miyata K.,Shibukawa Plant |
Ando S.,Tokyo Institute of Technology
ACS Applied Materials and Interfaces | Year: 2013
A series of inorganic/organic composite films exhibiting high thermal stability and high thermal diffusivity was prepared from five different grades of flake-shaped hexagonal boron nitride (hBN) and aromatic polyimides (PIs). Thermal diffusivities along the out-of-plane (D//) and in-plane (D//) directions of hBN/PI films were separately measured and analyzed in terms of particle size, shape, concentration, and orientation, as well as molecular structures of rigid and flexible PI matrices. hBN/PI films filled with large flake-shaped particles exhibited a large anisotropy in D // and D// due to the strong in-plane orientation of heat-conducting basal plane of hBN, while smaller anisotropy was observed in composites with small flakes and aggregates which tend to orient less in the in-plane direction during film processing. The anisotropic thermal diffusion property observed in hBN/PI films exhibited strong correlation with the orientation of hBN particles estimated using scanning electron micrographs (SEM) and wide-angle X-ray diffraction. Moreover, composites of hBN with a rigid-rod PI matrix exhibited much larger anisotropy in D// and D// than flexible PI-composites, reflecting the effect of the rigid and densely packed PI chains preferentially orienting parallel to the film plane. The thermal conductivities of the hBN/rigid-rod PI films were estimated as 5.4 and 17.5 W/m·K along the out-of-plane and in-plane directions, respectively, which is one of the largest values ever reported. © 2013 American Chemical Society.
Kurimura H.,Shibukawa Plant |
Watanabe J.,Shibukawa Plant |
Oshima K.,Shibukawa Plant |
Yoda K.,Shibukawa Plant |
Shimizu N.,Shibukawa Plant
Polymer Journal | Year: 2016
We have developed a next-generation temporary fixing agent for electronic materials. This fixing agent allows for film peel-off via immersion in hot water while retaining strong adhesiveness, which can resist various forms of processing. Although thermoplastic adhesives (known as waxes) have been previously used as temporary fixing agents, problems related to their safety and workability were observed because they melt at high temperatures during the adhesion process. In addition, environmental issues were encountered due to the use of organic solvents in the cleaning process that was performed after peel-off. Conversely, our temporary fixing agent is expected to compensate for such limitations because it possesses advantageous characteristics, such as curing capabilities over short durations at room temperature using redox polymerization or photopolymerization, peel-off via immersion in hot water, and a film-type peel-off. Such fixing agents are becoming the de facto standard for use in the processing of capacitive touch sensors in glass covers, for example, in smartphones and tablet PCs. © 2016 The Society of Polymer Science, Japan (SPSJ).