Microelectronics Packaging Application using post-LTCC technology

Abstract

The rapid evolution in electronic equipment has created a demand for advanced devices that are flexible, thin, and light in weight. This demand is driving the development of flexible and stretchable electronic devices as a core technology. To produce wearable computers, we need to fabricate functional membranes that contain passive devices such as capacitors and resistors on resin sheets at low temperatures. These sheets can then serve as mounting boards for various electronic devices. By improving the technique for room-temperature aerosol deposition (ASD) of a ceramic material (post-LTCC technology), we have established a technology for forming a dielectric inorganic film with an excellent degree of crystallinity and favorable electric properties for use in the production of flexible and stretchable electronic devices on a polyimide sheet. In the barium titanate film produced by the deposition on a polyimide sheet, a closely packed film with a high degree of sealing was formed by means of structure control to establish large-particle anchors, measuring about 100 nm in diameter, at the interface between the ceramic film and the polyimide sheet. The maximum dielectric constant of a film of barium titanate formed on the polyimide sheet by using the improved aerosol-deposition was 350 .By using this method to form a three-dimensional capillary structure inside a film, we produced a capacitor film with an apparent dielectric constant of 40,000 at room temperature. We also demonstrate cathode films for quick-charging lithium ion batteries. To achieve rapid charging, it is necessary to improve the speed of the chemical reaction between the cathode material and the electrolyte. Our process, however, does not require any unnecessary additive, such as a binder, unlike conventional tape casting method, and forms a film consisting of nano-particles of a high crystallinity, and is therefore effective for rapid charging.