Currently, CO2 emissions from the peat is a global problem. Particularly, it is caused by biodegradation of dry peat or peat fire. In the northern coast of Bengkalis island, peat is flowing out due to coastal erosion, and mangrove tidal flat is formed the west coast by peat. The core samples of the mangrove have been confirmed that the clay layer and the peat layer are in mutual layers, and decomposition was inhabited because these sandwiched peat soils was an anoxic state. In the northern part of the Bengkalis island, peat is sandwiched in the clay layer. Biodegradation can be suppressed by being sandwiched, there is a possibility of suppressing the amount of peat decomposed by providing a place to store peat in tidal flats. In this research, we examined the degree of decomposition of peat accumulated in the mangrove tidal flats and confirmed that decomposition was suppressed for the peat soils in the tidal flat under mangrove trees, we call it “sandwich effect”. The peat materials in deeper layer came from originally peat swamp forest, however, the surface organic materials were thought to be come from mangrove materials. Considering the change from 1988 to 2015, the carbon fixation rate by mangrove is 1.7 × 103 tC km-2 yr-1, the carbon accumulation rate by accumulation of secondary deposition of peat was 7.4×103 tC km-2 yr-1.
Polyimide (PI) film is widely used in several applications especially in the electronics industry, e.g., as a base material for flexible printed wiring assembly, because of its excellent mechanical and thermal stability and a low dielectric constant. Our group proposed an all-wet process to fabricate the diffusion barrier layer and Cu wiring by using an organosilane layer as an adhesive/catalyst layer as shown in fig. 1 [1, 2]. Additionally, wet processes offer relatively simple procedures and tools, and usually are cost effective. In previous study, an immobilized aminosilane film on polyimide works as an adhesion layer and a catalyst supporting layer for electroless deposition (ELD) of NiB. Adhesion of NiB-ELD film on ultra-smooth polyimide is a particular need for realizing a high-density printed circuit board [3]. We have reported that an induction time of NiB-ELD was changed by the number of amino groups in aminosilane, and a shorter induction time was found in the aminosilane having two or three amino groups as compared with that having single. Our recent critical problem is in the step of Cu deposition onto NiB-ELD: a low reduction rate of cupric ion in sulfuric acid, or if the reduction proceeded, the film peeling was observed. We therefore used the alkaline electrolytes developed by Japanese company or it’s improved to fabricate Cu wiring, and examined thermal annealing effect on the electronic conductivity, crystallinity. References [1] T. Osaka, M. Yoshino, “New Formation Process of Plating Thin Films on Several Substrates by Means of SAM (Self-Assembled Monolayer) Process”, Electrochim. Acta, 53, 271 (2007). [2] M. Yoshino, T. Masuda, T. Yokoshima, J. Sasano, Y. Shacham-Dimand, I.Matsuda, T. Osaka, A. Hashimoto, Y. Hagiwara, I. Sato, “Electroless Diffusion Barrier Process Using SAM on Low-k Dielectrics”, J. Electrochem. Soc, 154, D122 (2007) [2] T. Osaka, S. Wakatsuki, T. Masuda, M. Yoshino, N. Yamachika, J. Sasano, I. Matsuda, Y. Okinaka, “A Wet Process for Forming an Adhesive Copper Layer on Polyimide Film”, Electrochemistry, 76, 191 (2008). Figure 1
Polyimide materials are widely used for printed circuit board as substrate/insulation layer because of its high mechanical stability, high electrical insulation properties, high heat resistance, etc. Low dielectric constant and superior flat surface are requested for applying to high speed signal circuit. Applying the polyimide film to high-speed circuit board, high adhesion length and superior flat interface between metal wiring and polyimide is needed. Our group proposed an all-wet process to fabricate the diffusion barrier layer and Cu wiring by using an organosilane layer as an adhesive/catalyst layer [1, 2]. Additionally, wet processes offer relatively simple procedures and tools, and usually are cost effective. In previous study, an immobilized aminosilane film on polyimide works as an adhesion layer and a catalyst supporting layer for electroless deposition of NiB. This process showed superior smooth surface of catalyzed polyimide because of without etching processes. Adhesion of electroless-deposited NiB film on superior smooth polyimide is a particular need for realizing a high-density printed circuit board [3,4]. In this investigation, this technique was applied for preparation of the silicone chip substrate called interposer. The high-speed signal transmission line for interposer was developed by our proposed method. Soluble block copolymerization polyimide (Q-VR-X1014, PI R&D CO.,LTD) was used for polyimide film source, and thin polyimide layer with and superior flat surface was prepared on glass substrate by spin-coating. After drying, hydrophilic surface of polyimide was developed by UV-irradiation in 10 min. Aminosilane layer in the polyimide was formed in toluene solution containing aminocilane molecule at 60 oC, 10 min. Then, modified surface was catalyzed by palladium, and thin metal layer as seedlayer/adhesion layer and conductive layer were formed by electroless NiB deposition and Cu electrodeposition, respectively. Cu electrodeposition was carried out using alkaline electrolytes bath (Meltex Inc). First, Cu electrodeposition on polyimide was investigated. Figure 1 shows schematic illustration of electrodeposited Cu film on aminocilane-modified polyimide film. To form Cu conductive layer using electrodeposition with conventional acidic bath, film peeling between Pd/aminosilane interfaces was observed. Acid condition was affected for Pd catalyst layer, and Pd was dissolved from the aminocilane supporting layer. We therefore used the alkaline electrolytes bath for Cu electrodeposiotion. We optimized operating condition of electrodeposition and thermal annealing to decrease electronic conductivity, adhesion strength. Using this optimized condition, Cu film with 2 μΩcm could be obtained. Second, roughness of the surface and its interface was measured. Figure 2 shows cross sectional TEM image of electrodeposited Cu film on aminosilane-modified polyimide film after annealing. Roughness of interface between polyimide and NiB was not observed and superior smooth interface was obtained using this technique. Moreover, surface roughness of deposited Cu film was very smooth of Rq = 14 nm. Final, a coplanar waveguide as high-speed signal transmission line was fabricated by this technique. Cu wiring was prepared by semi-additive method. Line width was 100 μm, and film thickness and space between grand and signal line was varied. The characteristic impedance of the fabricated coplanar waveguide showed almost the same value of the theoretical designed one that was 50 Ω. References [1] T. Osaka, M. Yoshino, Electrochim. Acta, 53, 271 (2007). [2] M. Yoshino, T. Masuda, T. Yokoshima, J. Sasano, Y. Shacham-Dimand, I.Matsuda, T. Osaka, A. Hashimoto, Y. Hagiwara, I. Sato, J. Electrochem. Soc, 154, D122 (2007) [3] T. Osaka, S. Wakatsuki, T. Masuda, M. Yoshino, N. Yamachika, J. Sasano, I. Matsuda, Y. Okinaka, Electrochemistry, 76, 191 (2008). [4] T. Osaka, T. Yokoshima, H. Kagawa, T. Hachisu, A. Sugiyama, Meeting abstract of 227th ECS Meeting, No. 1133 (2015). Figure 1
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