Shigeru Matake

Improvement of the light extraction efficiency of top-emitting organic light-emitting diodes by a two-dimensional diffraction layer fabricated using self-assembled nanoparticles

The light extraction efficiency of top-emitting organic light-emitting diodes (OLEDs) was improved by insertion of a two-dimensional (2D) diffraction layer. The 2D diffraction layer was fabricated by our original nanofabrication technique, the embedded particle monolayer method, which could form a self-assembled particle monolayer. As a result, the electroluminescence intensity of the device with the 2D diffraction layer was improved by 1.67 times (in total luminous flux) and 2.07 times (in peak wavelength). High luminance top-emitting OLEDs were fabricated using the potentially low-cost self-assembling technique.

Novel method for simultaneous formation of wires and vias of a printed circuit board using nanoporous body

A new type of a flexible printed circuit board with landless vias is developed using a novel method called interconnection via nanoporous structure (INPS). This method can make wires and vias of the printed circuit board simultaneously by a single photo-exposure process. A new photo-induced selective plating method was used to impregnate a nanoporous substrate with copper, and a new photomask was designed, which constitutes of a completely vacant large hole for via and aggregation patterns of very fine holes for wire. Because of the simple process, the INPS board is characterized by landless vias and very fine circuit. Owing to the structure, it is also characterized by flexibility and detachable wires.

Preparations and properties of novel positive photosensitive polyimides

Polyamic acid esters with phenol moieties (Ph-ES) were synthesized from diamines and dicarboxylic acids bonding to phenol moieties through ester linkage. To synthesize the dicarboxylic acids, 1 mol of BTDA was reacted with 2 mol of m-hydroxybenzyl alcohol in NMP. The resultant dicarboxylic acid are predominantly benzyl esters, not phenyl esters, was condensed with ODA, using DCC as condensing agent. The polyimide precursors Ph-ES was actually soluble in basic aqueous solutions. However, its dissolution rate was too low for binder resins used for resists. To increase the resist dissolution rate, polyamic acid PA, which is assumed to be more soluble in the base developer, was added to Ph-ES. The PA was synthesized from BTDA and ODA. Resists containing Ph-ES (60 wt%), PA (20 wt%) and naphthoquinone diazide (20 wt%) gave 4 micron line and space pattern with 5 micron thickness. There was no pattern deformation, even after the polyamic acid ester was heated at 320 degree(s)C to form the polyimides. The PA content was critical to the high resolution achievement. As the content of the PA to Ph-ES increases, the pattern shape of the resist deteriorated rapidly. At more than 40 wt% PA rate, patterns could not be obtained, because fine patterns peeled off form the silicon wafer substrate during the development. This proved that adjusting dissolution rates in basic aqueous solutions is one of the significant points for realizing fine resist patterns.