There is known a semiconductor package in which a semiconductor chip (semiconductor element) is covered (encapsulated) with a resin-made encapsulating (sealing) material. The encapsulating material for the semiconductor chip is produced by molding a resin composition through, e.g., a transfer molding method.
A process for producing the resin composition from a powder material thereof includes a surface treatment process in which a processing liquid such as a coupling agent is allowed to adhere to surfaces of inorganic particles such as silica particles (filler material) contained in the powder material of the resin composition.
In this surface treatment process, the silica particles are injected into a chamber from an inlet port thereof, and the coupling agent is also sprayed into the chamber from an opposite side with respect to the inlet port while the silica particles are spirally swirled in the chamber (for example, see patent document 1). In this configuration, a part of the coupling agent is contacted with the silica particles upon spraying the coupling agent and the remaining coupling agent is swirled and contacted with the other silica particles in the chamber during swirling of the silica particles so that the coupling agent adheres to the surfaces of the silica particles. As a result, a mixing property of resin particles constituting the resin composition and the silica particles is enhanced, thereby easily mixing the silica particles and the resin particles since the silica particles are coated with the coupling agent.
However, according to the above method, in the surface treatment process, there is a problem in that the silica particles are aggregated. In this case, it is difficult to uniformly mix the silica particles (inorganic particles) with the resin particles (resin composition).
Patent Document 1: JP-A 2003-275555.
It is an object of the present invention to provide a particle production apparatus, a particle production method and a method for producing a semiconductor encapsulating resin composition, by which a processing liquid is allowed to adhere to inorganic particles contained in a powder material reliably while aggregation of the inorganic particles is suppressed.
In order to achieve the object, one aspect of the present invention is directed to a particle production apparatus which is configured so that a processing liquid adheres to a surface of each of inorganic particles contained in a powder material, the particle production apparatus comprising:
a processing section in which the processing liquid is allowed to adhere to the surface of each of the inorganic particles;
a chamber connected to the processing section at a downstream side thereof in which the powder material is separated from gas carrying the powder material;
a powder material supply device which supplies the powder material into the processing section; and
a processing liquid spraying device which sprays the processing liquid as droplets to the powder material just after the powder material being supplied into the processing section,
wherein after the processing liquid sprayed to the powder material adheres to the surface of each of the inorganic particles contained in the powder material in the processing section, the powder material is transferred into the chamber so that the powder material is separated from the gas.
In the particle production apparatus of the present invention, it is preferred that the processing liquid spraying device comprises: a nozzle; a gas supply device for supplying the gas having a pressure being equal to or higher than 0.3 MPa to the nozzle; and a processing liquid supply device for supplying the processing liquid into the nozzle, and
wherein the processing liquid is sprayed from the nozzle into the processing section due to the pressure of the gas.
In the particle production apparatus of the present invention, it is preferred that the processing liquid supply device is a pump.
In the particle production apparatus of the present invention, it is preferred that the droplets of the processing liquid sprayed from the processing liquid spraying device include small-sized droplets having a particle size being equal to or less than 20 and the processing liquid spraying device is configured so that a ratio of the small-sized droplets to the total of the sprayed droplets becomes equal to or more than 80 wt %.
In the particle production apparatus of the present invention, it is preferred that the particle production apparatus is configured so that a swirl stream of the gas is generated in the chamber by spraying the processing liquid using the processing liquid spraying device.
In the particle production apparatus of the present invention, it is preferred that the chamber has a cylindrical shape and the processing section has a central axis and an outlet port connected to the chamber,
wherein the processing section is connected to a side portion of the chamber such that the central axis of the processing section is inclined with respect to a direction of a radius of the chamber which passes through the outlet port of the processing section, and
wherein the particle production apparatus is configured so that a swirl stream of the gas is generated in the chamber by spraying the processing liquid using the processing liquid spraying device.
In the particle production apparatus of the present invention, it is preferred that the inorganic particles are constituted of silica and the processing liquid is a coupling agent.
In order to achieve the object, another aspect of the present invention is directed to a particle production method by which a processing liquid is allowed to adhere to a surface of each of inorganic particles contained in a powder material, wherein the powder material is supplied into a processing section, and the processing liquid is sprayed as droplets to the powder material just after the powder material being supplied into the processing section, thereby allowing the processing liquid to adhere to the surface of each of the inorganic particles contained in the powder material, and then the powder material is transferred into a chamber so that the powder material is separated from gas carrying the powder material.
In the particle production method of the present invention, it is preferred that the processing liquid and the gas having a pressure being equal to or higher than 0.3 MPa are supplied into a nozzle so that the processing liquid is sprayed from the nozzle into the processing section.
In the particle production method of the present invention, it is preferred that an average particle size of the inorganic particles is in the range of 0.5 to 100 μm.
In the particle production method of the present invention, it is preferred that when the processing liquid is sprayed to the powder material so that the processing liquid adheres to the surface of each of the inorganic particles contained in the powder material, there is a case that the powder material includes aggregated particles each comprised of the inorganic particle and the adhering processing liquid wherein each aggregated particle having a particle size of 150 μm or more, but a ratio of such aggregated particles to the whole of the powder material is equal to or less than 1 wt % of the powder material.
In order to achieve the object, the other aspect of the present invention is directed to a method for producing a semiconductor encapsulating resin composition comprising:
allowing the processing liquid to adhere to the surface of each of the inorganic particles contained in the powder material by the particle production method of the present invention; and
mixing a composition containing a powder material constituted of a resin and the powder material containing the inorganic particles to which the processing liquid adheres.