This micro-shape formation technology is a method of forming a honeycomb (a hollow hexagonal pillar structure similar to a beehive). A template having regularly arrayed holes is coated with material, which becomes the base of the honeycomb, covering the holes, as shown in Figure 1 (1). Then, air bubbles formed in the holes are inflated by air pressure, as shown in Figure 1 (2), to change the shape and harden the honeycomb material. The air bubbles in the holes are simultaneously inflated by lowering the air pressure around them from atmospheric pressure to a vacuum state.
This process resembles the method of producing soap bubbles using a drinking straw. Although soap bubbles are usually spherical, when they attach to each other they form hexagons or squares. This technology makes use of that principle.
Figure 1: Microhoneycomb formation process
Figure 2: Microhoneycomb formed using this process
Although the honeycomb formation method developed by Ricoh involves simple equipment and methods, it has honeycomb formation capabilities equivalent to or superior to those of X-ray lithography requiring extremely expensive equipment or dry etching involving many processes. The principal capabilities of this method are described below.
|1||Variable aspect ratio (cell height/wall thickness: 50 to 750)|
|2||Variable pitch (from 5 to 150µm or greater)|
|3||Wide processing area (ø100mm or greater)|
|4||High processing speed (from a few seconds to a few minutes)|
Figure 3: Ricoh technology enabling versatile processing
Figure 4: Shape comparison of the Ricoh method and dry etching
Ricoh believes the ability to manufacture minute microhoneycombs with high aspect ratios at low cost will greatly expand microhoneycomb applications. Examples include adsorption materials with large surface areas, anisotropic materials inducing heat or light in only one direction, and multifunctional materials combining hydrophilic and hydrophobic properties on a single surface. Facial masks that do no constrict breathing are another potential application.
Figure 5: Expansion of microhoneycomb applications