Dowa Electronics Materials Co., Ltd.

Daisuke Itoh

Hidefumi Fujita

Yu Murano

Shuji Yamashita

Shinichi Konno

Shuji Kaneda

Daiki Yoshihara

In a fine silver particle dispersing solution wherein 30 to 75% by weight of fine silver particles, which are coated with an organic acid having a carbon number of 5 to 8 or a derivative thereof and which have an average particle diameter of 1 to 100 nm, are dispersed in a water-based dispersion medium which is a solvent containing water as a main component, the fine silver particle dispersing solution containing ammonia and nitric acid, there is added 0.15 to 0.6% by weight of a surface regulating agent, which preferably contains a polyether-modified polydimethylsiloxane and a polyoxyethylene alkyl ether or a polyether, or 0.005 to 0.6% by weight of an antifoaming agent which is preferably a silicone antifoaming agent.

Fine silver particle dispersing solution

After there is prepared a conductive paste which contains fine copper particles having an average particle diameter of 1 to 100 nm, each of the fine copper particles being coated with an azole compound, coarse copper particles having an average particle diameter of 0.3 to 20 &#x3bc;m, a glycol solvent, such as ethylene glycol, and at least one of a polyvinylpyrrolidone (PVP) resin and a polyvinyl butyral (PVB) resin and wherein the total amount of the fine copper particles and the coarse copper particles is 50 to 90% by weight, the weight ratio of the fine copper particles to the coarse copper particles being in the range of from 1:9 to 5:5, the conductive paste thus prepared is applied on a substrate by screen printing to be preliminary-fired by vacuum drying, and then, fired with light irradiation by irradiating with light having a wavelength of 200 to 800 nm at a pulse period of 500 to 2000 &#x3bc;s and a pulse voltage of 1600 to 3800 V to form a conductive film on the substrate.

Conductive paste and method for producing conductive film using same

A silver particle dispersing solution, which contains 50-70% by weight of silver particles having an average particle diameter of 20 nm or less, is applied on a substrate by the flexographic printing, and then, calcined to produce a booster antenna wherein a silver conductive film, which contains 10-50% by volume of a sintered body of the silver particles and which has a volume resistivity of 3-100 &#x3bc;&#x3a9;&#xb7;cm, a surface resistivity of 0.5&#x3a9;/&#x25a1; or less and a thickness of 1-6 &#x3bc;m, is formed on the substrate. Thus, there is provided a booster antenna which has excellent electrical characteristics and flexibility and which can be inexpensively mass-produced.

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Okayama, Japan

Daisuke Itoh