Shuji Eguchi

The influence of siloxane modifiers on the thermal expansion coefficient of epoxy resins

Abstract The thermal expansion behaviour of unmodified and siloxane-modified epoxy resins has been investigated to clarify the mechanism by which siloxane modifiers lower the thermal expansion coefficient of epoxy moulding compounds containing inorganic fillers. A mechanism that accounts for all the observed characteristics is proposed. The thermal expansion coefficient of epoxy resins is increased by siloxane modifiers with carboxyl end groups, and the degree of the increase is dependent on the molecular weight of the modifiers. This increase is considered to be due to two effects: an increase in the local free volume in the epoxy matrix caused by the development of thermal stresses, and the building of siloxane molecules into the network structure. For sufficiently low molecular weight siloxane modifiers the latter effect is dominant, whereas with increasing molecular weight the former effect dominates. The increased coefficient of epoxy resins due to siloxane modifiers is likely to result in thermal stress near the filler-polymer interface because of an increased difference in the thermal expansion coefficient between the materials. This is one factor causing siloxane-modified epoxy moulding compounds to have a lower thermal expansion coefficient than unmodified ones.

Advanced IC packaging for the future applications

The performance of electronic equipment is improving rapidly. Portable electronic equipment requires smaller and thinner packaging systems for saving space and miniaturization. In addition, highly integrated, high-speed applications demand improved electrical performance to minimize noise effects. As a result of these considerations, the role of IC packaging has expanded from its traditional role of protecting the integrity and performance of an IC, to being a central factor in the development of electronic system concepts. In developing the optimum system, packaging technology must be a prime design consideration to ensure optimum performance, reliability, and cost. Soldering technology and Printed Wiring Board (PWB) routing density are two of the major technological issues facing miniaturized packaging systems today. Chip Scale Package (CSP), which is a new concept in packaging technology has been introduced. This is an ideal technology to enable the design and manufacture of the next generation of electronic equipment, while overcoming many of the technological issues facing system development.

Gradient Index Polymer Optical Waveguide Patterned by Ultraviolet Irradiation

A new fabricating technique which is capable of easy pattern formation in gradient index polymer optical waveguides is proposed. Waveguides are obtained by diffusion and fixing of monomers with low refractive indices into a gel patterned by ultraviolet irradiation. The gradient index profiles can be selectively formed in the irradiated parts due to the difference in diffusion rate of monomers between regions in the same substrate. Waveguide optical properties are also demonstrated.

Design of Epoxy Encapsulating Compounds for Highly Reliable Surface Mounting Semiconductor Devices

One of the most important subjects for semiconductor packages is preventing cracks which occur when the entire package is exposed to a soldering temperature of 215 to 260°C in the surface mounting technology. Cracking, as seen during temperature cycling tests is also a problem to be addressed. This paper reports the design of epoxy encapsulating compounds for highly reliable semiconductor devices which require the following properties: (1) toughness of matrix resin, (2) low moisture absorption, (3) high adhesion to insertions, and (4) reduction of thermal stress. The moisture absorption was lowered and the toughness was improved by using hydrophobic epoxy resins and high filler loading. The latter reduced the thermal stress, and it was effective for lowering the moisture absorption and increasing the fracture toughness of molding compounds. The reliability tests results were also considered in terms of physical properties of molding compounds.

Selective formation of gradient-index profiles inside a planar polymer substrate by a lithographic technique

A fabricating technique that is capable of easy pattern formation for gradient-index polymer optical devices is proposed. Monomers with low refractive indices are diffused into a gel that contains barium ion patterned by a lithographic technique, and then the diffusion profile is fixed by thermal polymerization. The gradient-index profiles can be selectively formed in the ultraviolet- (UV-) irradiated regions by utilizing the difference in diffusion rate of monomers between regions in the same substrate. The optical properties and shapes of the gradient-index profiles are determined by the diffusion behavior of the monomers into the UV-irradiated regions. A lens array, consisting of two equivalent gradient-index lenses distributed uniformly in the substrate, and a low-loss Y-branched waveguide are fabricated by this technique, and their optical properties are demonstrated.

Modification of Epoxy Resins by Resol Type Phenolic Resin.

エポキシ樹脂の耐熱性を向上させる目的で, 硬化剤としてレゾール型フェノール樹脂 (RE) を用いたエポキシ樹脂系の硬化反応及び硬化物の物性に及ぼす触媒の影響を検討した. その結果, 硬化反応では, エポキシ基とフェノール性水酸基との反応とREの自己縮合反応が競争的に進行することが分かった. 触媒として1,8-ジアサビシクロ (5, 4, 0) -ウンデセン-7 (DBU) を用いた場合にはエポキシ基とフェノール性水酸基との反応が主に進行し, テトラフェニルボスホニウムテトラフェニルポレート (TPP-TPB) を用いた場合にはエポキシ基の反応とREの自己縮合反応が同時に進行する. 硬化物の物性では, ノポラック型フェノール樹脂を硬化剤としたエポキシ樹脂系に比べREを硬化剤として用いた系はガラス転移温度, 高温での強度, 弾性率が上昇し, TPP-TPBはDBUに比べこれら物性値を上昇させる効果が大きいことが分かった.