Noriyuki Kinjo

Re-examination of the relationship between packing coefficient and thermal expansion coefficient for aromatic polyimides

Abstract The existence of a possible relationship between molecular packing coefficient and thermal expansion coefficient for various aromatic polyimides was investigated. Rod-like low-thermal-expansion polyimides without side groups were seen to have very high packing coefficients, pointing to free volume as a factor in lowering their thermal expansion coefficients. But the small packing coefficients for low-thermal-expansion polyimides with side groups indicated that this was not so. Also, even if the large packing coefficients tended to increase the Youngs moduli for these polyimides without side groups, the rod-like polyimides with side groups have small packing coefficients and large Youngs moduli. The polyimides with low packing coefficients were found to have very small diffusion coefficients for water vapour.

A humidity sensor using ionic copolymer and its application to a humidity-temperature sensor module

Abstract A humidity-temperature sensor module with a frequency output signal was fabricated by integrating a humidity sensor, temperature sensor and measuring circuit on a ceramic substrate. The humidity sensor had a copolymer of ionic and non-ionic monomers as its humidity-sensitive material, and a chip thermistor served as the temperature sensor. The measuring circuit was an astable multivibrator, and the humidity and temperature sensors were used as circuit elements to determine the oscillation frequency. Operation of the humidity-sensing circuit was evaluated on the basis of an analysis of the frequency dependence of the humidity sensor impedance. In the derivation of the humidity-oscillation frequency characteristics from the impedance data, a model that expresses the humidity sensor impedance by the bulk resistance of the humidity-sensitive material gave relatively good agreement with expe The fabricated module offers superior long-term stability. Changes in humidity-oscillation frequency and temperature-oscillation frequency characteristics were less than ±3% r.h. and ±0.1 °C, respectively, after more than two years in an open laboratory atmosphere.

Low Thermal Expansion Polyimides and their Applications

Thermal expansion coefficients (TECs) for polyimides differ very much depending on their chemical structures. Polyimdes with a rod-like structure as their backbone chains have lower TEC values. This is attributed to restraining of thermal expansion by rod-like molecules within intermolecular spaces, analogous to glass fibers in FRPs. The development of new polyimides which can closely match TECs of inorganic materials, such as metal or Si, can eliminate problems produced by thermal stress including warping, cracking or delamination. A new multilevel interconnection system using multilayered dielectrics consisting of low thermal expansion polyimide and inorganic materials has been proposed as one future technology for submicron VLSIs. Consequently, adhesiveless, high quality flexible printed circuit boards have been developed using a polyimide with the same TEC as copper foil. Their most significant property is a high dimensional stability after heat treatments, such as in a soldering process. Furthermore, they have very high adhesion strength at elevated temperatures.

Studies on Thermal Cyclization of Polyamic Acids

The imidization reaction of various polyamic acids having different chemical structures has been followed by measuring the weight losses that occurred during dehydro-cyclization. From these studies it was found that when polyamic acids were heated rapidly to a given temperature, the imidization reaction proceeded during the temperature rise but slowed down very markedly after the given temperature was reached. The temperature at which the imidization reaction ended was closely related to the glass transition temperature of the resulting polyimide. Based on these observations, it is concluded that the imidization reaction slows down markedly because the glass transition temperature of the polymer rises as the reaction proceeds, and molecular motion is frozen. In other words, the free rotation of amide bonds in the main chain is frozen. As a result, suitable conformation for imidization cannot take place any more.

Membrane potential studies on reverse osmosis membranes of cellulose acetate

Abstract The mobilities of various univalent ions in cellulose acetate membranes were investigated by means of membrane potential, diffusion coefficient, and electrical resistance measurements. The mobilities of Na + and Cl − ions in dense membranes are about three orders of magnitude less than those in aqueous solution. The size dependence of ionic mobility in dense membranes is significantly different from that in aqueous solution. The relationship between ionic mobilities and ionic radii in asymmetric membranes having salt rejections lower than 80% is almost the same as that in aqueous solution. As for asymmetric membranes having salt rejections higher than 86%, however, this relationship is clearly different from that in aqueous solution and seems to be similar to that in dense membranes. The fact that the mechanism of ionic movement in asymmetric membranes changes at salt rejection values of 80–86% has been attributed to the fact that the bulk water filling the ion channels in membranes which have lower salt rejections is initially eliminated by shrinkage at annealing. The ions are then limited to movement in the bound water filling the ion channels.

Movements of univalent ions in cellulose acetate membranes

Abstract Membrane potentials across the asymmetric membranes of cellulose acetate with various salt rejection properties have been measured for univalent ions. The behavior of ions in the membranes is discussed from the viewpoint of relative ionic mobilities calculated from the membrane potentials. The relationship between ionic mobilities and ionic radii in the membranes having salt rejections lower than 80% is almost the same as that in aqueous solutions. This implies that the ions in these membranes behave as if they exist in bulk water. However, the ionic mobilities in the membranes having salt rejections higher than 86% differ significantly depending on the ionic radii. It seems probable that the bound water influences the ionic mobilities in these membranes.

Thermally stimulated current in aluminium phthalocyanine chloride film

Analyse des courbes de courant thermostimule, induit par irradiation par laser a 600 nm: les sites des pieges peuvent etre exprimes par le modele de Poole-Frenkel. Evaluation des parametres de piegeage dans les limites de repiegeage rapide ou lent

Silicone Elastomer Vulcanized by the Hydrosilation Reaction and its Influence on Properties of a Modified Mos Device

A p-MOS device in which the gate position is incompletely covered by the gate electrode has been used as a test device to estimate influence of silicone elastomer on residual current after gate operation. The elastomer was vulcanized by the hydrosilation reaction. It was found that the residual current could be represented as a function of the hardness and electrical conductivity of the silicone elastomer; that is, the current increased with decreasing hardness and increasing conductivity over the temperature range from 100 to 150°C. Comparison of activation energies measured by the residual current and by electrical conductivity indicated that different mechanisms of charge transport may be in operation, The differences may be due to the presence of dipole moments such as from unreacted hydrosilyl groups and of certain species such as water and chloride ions.

Bending strength of thermosetting resins containing isocyanurate and oxazolidone rings and analysis of their chemical structures.

ジフェニルメタンジイソシアナートを含む化合物とビスフェノールAのジグリシジルエーテルとをN-メチルモルホリンの存在下, 加熱して得られる樹脂硬化物の曲げ特性を25℃で測定した, 曲げ強さはイソシアナート化合物とエポキシ化合物のモル比 (0.63～51) 及び加熱処理温度 (180, 200, 及び225℃) などに強く依存することを見いだした. 硬化物の赤外線吸収スペクトルを測定し, イソシアヌラート環とオキサゾリドン環の形成割合を解析し, 曲げ強さとの関係について考察を加えた. 硬化物中の未反応のイソシアナート基量をスベクトルの吸光度比から定量化し, 硬化反応がほぼ終了するまで, 更に加熱し, 曲げ強さを追跡して樹脂組成物の硬化性を検討した.

Water vapor solubility and permeability of coating polymers and their effects on residual current of modified semiconductor devices.

シリコーン系, 熱可塑系, 及びイミド系などの各種ポリマーが, 恒湿度雰囲気下 (25℃, 0～75%RH) で半導体素子に及ぼす影響を調べるために, 各ポリマーの吸湿率, 及び透過係数などを測定し, 水分の拡散係数を算出した. 次に, ポリマー, 及び水分などの影響を評価できるように工夫した電界効果型トランジスタの残留電流を測定した。残留電流は, ポリマーの種類によって異なり, 印加時間の延長, 及び湿度の増加などによって増大する傾向を示した. この残留電流は, 拡散係数D, 時間t, 及び相対湿度 Px (%) などを含む関数として表せることを導き出した. log Ir=m・Px+n・log (D・t) +log C, ここで, m, n及びCなどは, ポリマーの種類及び, 素子の構造によって決定される係数である. 拡散係数を比較することにより, 恒湿度雰囲気下で残留電流が増大する機構について考察した.