JP2007181771A - Metal foreign matter removing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal foreign matter removing device capable of removing too minute metal foreign matters to be removed by conventional metal foreign matter removing devices. <P>SOLUTION: The metal foreign matter removing device is provided with a passage (inner space of a cylindrical body 2) through which particles pass, a plurality of spherical bodies 1 made of magnetic bodies with a chromizing-treated surface, filling the intermediate part of the passage in a stack, a magnetic field generating means 3 magnetizing the spherical bodies 1 by generating a magnetic field in a spherical bodies filled space, and an exciting means 4 intermittently or continuously vibrating the passage. The metal foreign matters are removed by attracting them to the spherical bodies with magnetic force by passing the particles mixed with the metal foreign matters through the spaces among the spherical bodies. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a metal foreign matter removing device that removes metal foreign matter mixed in a granular material by using magnetic force, in particular, a metal foreign matter in a semiconductor sealing raw material used for manufacturing a semiconductor device. The present invention relates to a metal foreign matter removing apparatus suitable for removal.

  Generally, an element (semiconductor chip) is mounted on a metal lead frame in a semiconductor device, and the element and the inner lead of the lead frame are connected by bonding a metal wire in order to conduct electricity to the outside. Has been. Furthermore, the element and the lead frame are sealed with a semiconductor sealing material such as an epoxy resin composition.

  Recently, the performance of electrical appliances and mobile phones has been improved, and there is a demand for miniaturization, thickness reduction, and performance enhancement of semiconductor devices. As described above, as the miniaturization and performance increase, the pitch of the metal wires inside the semiconductor device becomes narrower, and in some of the latest semiconductor devices, the pitch of the metal wires is less than 100 μm. The pitch of the metal wire is becoming narrower as the performance of the semiconductor device becomes smaller.

  On the other hand, when manufacturing the semiconductor sealing material, first, a plurality of types of raw materials are mixed, and the raw materials (particularly fillers) are mixed with fine metal produced from metal equipment during the manufacturing process. There are many foreign objects. When a semiconductor encapsulant is manufactured using a raw material mixed with such a metal foreign material, and the element or the like is sealed using the semiconductor encapsulant, the above-mentioned metal foreign material is used in a semiconductor device with a narrow pitch as described above. Gets caught between metal wires and causes short circuit.

Therefore, in order to prevent the contamination of the metal foreign matter, it has been proposed to remove the metal foreign matter by a drum-type metal sorting and collecting device using a magnet in the manufacturing process of the semiconductor sealing material. (For example, refer to Patent Document 1). In addition, in the internal space of the cylindrical body, a slit-shaped multilayer filter is formed by laminating a plurality of slit-shaped magnetic filters by changing the slit directions and wound around the outer periphery of the cylindrical body. The magnetic field generating coil is energized to generate a magnetic field to magnetize the slit multilayer filter, and in that state, the semiconductor sealing material raw material is passed through the slit multilayer filter, and the semiconductor sealing material 2. Description of the Related Art A removal device is known that removes fine metallic foreign matter mixed in raw materials by adsorbing each slit-like magnetic filter of the slit-like multilayer filter with a magnetic force.
JP-A-9-173890

  However, in the above-described drum-type metal sorting and collecting apparatus, it is possible to remove large-sized metal foreign matter, but it is not possible to sufficiently remove fine (about 100 μm or less in diameter) metal foreign matter. In addition, the removal device for magnetizing the slit-shaped multilayer filter is superior to the drum-type metal sorting and collecting device in removing fine foreign metal particles, but the passage in the slit-shaped multilayer filter is one-dimensional. More fine metal foreign matter may pass through without contacting each slit magnetic filter, which is a big problem. Thus, until now, it has been inadequate to remove finer metal foreign objects corresponding to the narrowing of the pitch of the metal wires accompanying the downsizing and high performance of the semiconductor device.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a metal foreign matter removing apparatus that can remove finer metal foreign matter that cannot be removed by a conventional metal foreign matter removing apparatus.

  In order to achieve the above object, the metal foreign matter removing apparatus of the present invention is composed of a passage through which powder particles pass and a magnetic material whose surface is chromized and filled in the middle of the passage in a laminated state. A plurality of spherical bodies, a magnetic field generating means for magnetizing the spherical body by generating a magnetic field in the spherical body filling space, and an excitation means for vibrating the passage intermittently or continuously. By passing the powdered granular material through the gaps between the spherical bodies in the passage, the metallic foreign matter is adsorbed to the spherical bodies by magnetic force and removed.

  The inventors of the present invention focused on the element of the magnetic filter in order to remove finer foreign metal particles, and repeated research. In the process, a plurality of spherical bodies (for example, iron balls) made of a magnetic body are used as elements of the magnetic filter, and a passage (for example, a cylindrical body) through which these spherical bodies pass through a granular material to be processed for removing metallic foreign matter. If the spherical body is magnetized by generating a magnetic field in the spherical body filling space, the magnetic force becomes particularly large at the contact point between the spherical bodies. In the same magnetic field generation conditions, the inventors have found that the size is larger than that of the conventional slit-shaped multilayer filter. Further, when the spherical bodies are closely packed (stacked) in the internal space of the passage, the contact portions (parts where the magnetic force is particularly large) between the spherical bodies are arranged three-dimensionally, Since the passage composed of the gaps between the bodies is also formed three-dimensionally, the powder particles passing through the gaps between the spherical bodies in the stacking direction are the surface of the magnetized spherical bodies and the contact portions between the spherical bodies (the magnetic force is Inevitably comes in contact with the particularly large part). As a result, it was found that finer foreign metal particles that could not be removed can be removed.

  In addition, when the granular material is continuously passed through a magnetic filter (a portion where the spherical materials are laminated) using the spherical body as an element, the granular material is easily clogged with a gap between the spherical bodies. For the purpose of solving this problem, if the passage of the cylindrical body is vibrated to facilitate the passage of the granular material, the spherical body is rubbed against each other to generate metal powder, which becomes a new metallic foreign matter. Occurred. Therefore, when the surface of the spherical body is chromized, the present inventors form a hardened layer on the surface of the spherical body, and no metal powder is generated even when the spherical bodies are rubbed with each other, and the action of magnetic force is maintained. We have found out that we can do it and have reached the present invention.

  In the metallic foreign matter removing apparatus of the present invention, a spherical body made of a magnetic material is filled in the middle of the passage in a laminated state, and a magnetic field is generated in the spherical body filling space to magnetize the spherical body. As a result, the magnetic force can be particularly increased at the contact portion between the spherical bodies. Moreover, since the spherical body is filled in a laminated state, the powder passing through the spherical body filling space is on the surface of the magnetized spherical body and the contact part between the spherical bodies (part where the magnetic force is particularly large). Inevitably come in contact. As a result, finer foreign metal particles that could not be removed in the past can be removed by adsorbing to the spherical body with a magnetic force. Further, in the metal foreign matter removing device of the present invention, since the granular material is passed through the gap between the spherical bodies in a state where the passage is continuously and continuously vibrated, the granular material is not clogged with the gap. . In addition, since the surface of the spherical body is hardened by chromizing treatment, even if the spherical bodies are rubbed with each other by the vibration of the passage, metal powder is not generated from the spherical body, and the action of magnetic force can be maintained. it can.

  In particular, when the above-mentioned powder particles mixed with metal foreign matter are raw materials for semiconductor encapsulating materials, the metal foreign matter removing device of the present invention removes finer metal foreign matters that could not be removed conventionally. A raw material for a semiconductor sealing material can be obtained. And the semiconductor sealing material manufactured using the obtained raw material for semiconductor sealing material can sufficiently prevent a short circuit even when the metal wire is used for sealing a semiconductor device having a narrow pitch. it can. Here, the finer metallic foreign matter means a metallic foreign matter having an average diameter of 25 to 75 μm (measured at the longest portion of the metallic foreign matter).

  Next, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to this.

  FIG. 1 is an explanatory view schematically showing an example of the metallic foreign matter removing apparatus of the present invention. This metallic foreign matter removing apparatus includes a cylindrical body 2 erected vertically, and the spherical body (a special spherical body described later) 1 is provided in an internal space (passage) of the cylindrical body 2. Are packed in a densely packed state (laminated state). A number of the spherical bodies 1 that are stacked and filled are supported from below by a support plate 2 a provided in the internal space of the cylindrical body 2. A large number of through holes (not shown) are formed in the support plate 2a, and the size of each through hole is set smaller than the diameter of the spherical body 1 and larger than the particle diameter of the granular material. Has been. A magnetic field generating coil 3 for generating a magnetic field in the space filled with the spherical body 1 is wound around the outer periphery of the cylindrical body 2, and this magnetic field generating coil 3 is a direct current power source (not shown). It is connected to the. Further, on the outer peripheral portion of the cylindrical body 2, a vibration device 4 for vibrating the cylindrical body 2 left and right and up and down is installed. A container 5 is provided below the cylindrical body 2 to store the granular material that has passed through the spherical body 1 filling space (a magnetic filter formed by laminating the spherical bodies 1). In addition, the material of the said cylindrical body 2 is not specifically limited, For example, a nonmagnetic metal, resin, etc. are mention | raise | lifted.

More specifically, the special spherical body 1 is made of a magnetic material, and a hardened layer is formed on the surface thereof by chromizing treatment. And since it is this hardened layer, even if the spherical bodies 1 are rubbed when the cylindrical body 2 is vibrated, metal powder is not generated. Further, the magnetic body is not particularly limited as long as it is a metal usually used as a magnetic body, but from the viewpoint of facilitating chromizing treatment, high carbon chromium steel (SUJ-2), for cold heading Carbon steel (SWRCM10), martensitic stainless steel (SUS440C) and the like are preferable.

The chromizing process is a diffusion penetration process of chromium (Cr) with respect to a processing object such as a magnetic material, and is performed as follows, for example. That is, the spherical body 1 that is the object to be treated is placed in a steel case together with a preparation composed of chromium (Cr) powder, aluminum oxide (Al ₂ O ₃ ) powder, and ammonium chloride (NH ₄ Cl) powder, and sealed. Then, it is performed by heating to 900-1100 ° C. in a furnace while passing hydrogen (H ₂ ) gas or argon (Ar) gas through the steel case.

That is, in the chromizing treatment, as shown in the following chemical reaction formulas (1) to (3-1) and (3-2), Cr reacts with HCl to become CrCl ₂ (vapor), Reduced by H _{2 on} the surface of the spherical body 1 and precipitated Cr diffuses and permeates, or Cr undergoes a diffusion reaction with the component Me (metal element) of the spherical body 1 to diffuse and permeate.
(1) NH ₄ Cl ＮＨ NH ₃ + HCl (2NH ₃ Ｎ N ₂ + 3H ₂ )
(2) Cr + 2HCl → CrCl ₂ + H _{2
(3-1) CrCl 2 + H 2} → Cr + 2HCl ( reduction reaction)
_{(3-2) CrCl 2 + Me +} Cr + MeCl 2 ( substitution reaction)

  For example, when the spherical body 1 made of a magnetic material such as medium to high carbon steel or cast iron is subjected to chromizing treatment, the hardened layer formed on the surface has a thickness of 10 to 40 μm and a hardness of 1400 to 1800 mHv. It is formed in a carbide (FeCr) layer having good slidability within the range, and wear resistance is improved.

  Further, the shape of the spherical body 1 is preferably a true sphere, but if the gap between the spherical bodies 1 can be formed between the spherical bodies 1 while the spherical bodies 1 are stacked, the true sphere is deformed. For example, an elliptical sphere or the like may be used, or a spherical shell with a hollow interior may be used. And although the magnitude | size of the said spherical body 1 is not specifically limited, It is necessary to consider the following for the setting. That is, as the diameter of the spherical body 1 is increased, the gap between the spherical bodies 1 is increased, and the powder body is easy to pass. However, the spherical body 1 is arranged three-dimensionally per unit laminated thickness of the spherical body 1. The number of contact parts (parts where the magnetic force is particularly large) between the bodies 1 is reduced, and the adsorbability of metal foreign objects tends to be reduced. In consideration of this, for example, when processing a raw material for semiconductor encapsulating material (powder particles), the spherical body 1 has a diameter of 10 from the viewpoint of being able to reliably remove finer metal foreign matters and increasing the yield. It is preferable to set within a range of ˜15 mm. This diameter is an average value for any 10 spherical bodies 1 because the shape of the spherical body 1 is not a perfect sphere in most cases, and the measurement is performed for each spherical body 1. Measurement is performed using calipers or the like at three arbitrary locations, and the average value of these values is obtained.

Furthermore, although the lamination | stacking thickness of the spherical body 1 in the internal space of the said cylindrical body 2 is not specifically limited, It is necessary to consider the following for the setting. That is, as the laminated thickness of the spherical body 1 increases, the granular material passing through the laminated portion (magnetic filter) of the spherical body 1 has a surface portion of the spherical body 1 and a contact portion between the spherical bodies 1 (particularly the magnetic force). Although there is an increased chance of coming into contact with a large portion), the certainty that finer metal foreign matter can be removed increases, but the time for the powder to pass through the laminated portion of the spherical body 1 becomes longer, and the processing efficiency tends to decrease. is there. Considering this, for example, when processing the raw material (powder body) for semiconductor encapsulant, when using the spherical body 1 having the above preferred diameter range (10-15 mm range), a finer metal foreign matter From the standpoint that the processing time can be shortened with certainty, the laminated thickness of the spherical body 1 is preferably set within a range of 400 to 600 mm. In addition, the cross-sectional area perpendicular to the axis of the internal space of the cylindrical body 2 (the cross-sectional area perpendicular to the stacking direction of the stacked portion of the spherical body 1) is set to be wider, and the granular material that can be processed per unit time is set wider. The amount can be increased. For example, when processing 50 kg of raw materials for semiconductor sealing material (powder particles) per hour, the cross-sectional area perpendicular to the axis of the internal space of the cylindrical body 2 is usually set within the range of 15000 to 20000 mm ^2. It is preferred that

  Moreover, the vibration to the cylindrical body 2 by the vibration device 4 such as a vibrator is a means for preventing the powder particles from clogging in the laminated portion of the spherical body 1, and is not particularly limited. It may be intermittent or continuous. Further, the frequency and amplitude of the vibration are also appropriately set according to the processing amount and processing time of the granular material.

  According to such a metal foreign matter removing device of the present invention, each spherical body 1 (magnetic filter) is magnetized by applying a magnetic field to the magnetic filter using the spherical body 1 as an element by the magnetic field generating coil 3. (Into an electromagnet), in a state where vibration is intermittently or continuously applied to the magnetic filter by the vibration device 4, the powder is passed through the magnetic filter and mixed into the powder. The foreign metal particles can be adsorbed to the spherical body 1 (magnetic filter) by a magnetic force. In particular, in the contact portion between the spherical bodies 1 arranged in a three-dimensional manner, the magnetic force becomes larger than the other spherical body 1 surfaces, and finer foreign metal particles can be reliably adsorbed.

  And such a metal foreign material removal apparatus of this invention is used effectively for the removal of the metal foreign material from the raw material for semiconductor sealing materials. Then, the raw material for semiconductor sealing materials is demonstrated.

  The raw material for the semiconductor encapsulant is not particularly limited, and examples thereof include an epoxy resin, a phenol resin, a curing accelerator, and an inorganic filler. It has become.

  If it demonstrates in detail, the said epoxy resin will not be specifically limited, The normally used thing may be used. Examples thereof include a cresol novolak type, a phenol novolak type, a bisphenol A type, a biphenyl type, a triphenylmethane type, and a naphthalene type. These can be used alone or in combination of two or more.

  The said phenol resin has an effect | action as a hardening | curing agent of the said epoxy resin, It does not specifically limit and what is normally used may be used. Examples thereof include phenol novolak, cresol novolak, bisphenol A type novolak, naphthol novolak, and phenol aralkyl resin. These can be used alone or in combination of two or more.

  The curing accelerator is not particularly limited, and examples thereof include amine type and phosphorus type. Among them, examples of the amine type include imidazoles such as 2-imidazole, tertiary amines such as triethanolamine and 1,8-diazabicyclo (5,4,0) undecene-7, and the like. Examples of the phosphorus type include triphenylphosphine, tetraphenylphosphonium tetraphenylborate and the like. These can be used alone or in combination of two or more.

  The inorganic filler is not particularly limited and may be a commonly used one. Examples thereof include quartz glass powder, silica powder, alumina, talc and the like. Particularly preferred are spherical fused silica powder and crushed silica powder. These can be used alone or in combination of two or more. Furthermore, it is preferable that the average particle diameter of the said inorganic filler is 1-150 micrometers, More preferably, it is 5-75 micrometers.

  In addition to the above raw materials, if necessary, halogen-based flame retardants such as brominated epoxy resins, flame retardant aids such as antimony trioxide, β- (3,4-epoxysyncyclohexyl) ethyltrimethoxysilane, Other additives such as a silane coupling agent such as γ-glycidoxypropyltrimethoxysilane and a release agent such as carnauba wax are appropriately used.

  And a semiconductor sealing material can be manufactured as follows using the said raw material, for example. That is, after properly blending the above raw materials, it is melted and kneaded in a heated state in a kneading machine such as a mixing roll machine, cooled to room temperature, pulverized by known means, and tableted as necessary. It can be manufactured by a process. Then, when the semiconductor device is sealed with the manufactured semiconductor sealing material, the semiconductor sealing material is heated and fluidized by a known means, and then sealed, and then cured.

  In the above embodiment, the coil 3 wound around the outer periphery of the cylindrical body 2 is used as the magnetic field generating means. However, the present invention is not limited to this, and a magnetic field is generated in the spherical body 1 filling space. If possible, other means may be used.

  Moreover, in the said embodiment, although the interior space of the cylindrical body 2 was utilized as a channel | path of a granular material, it is not limited to this, Others may be used if a granular material can be let through.

  A metal foreign matter removing apparatus similar to that in the above embodiment was prepared. As the spherical body, a true sphere having a diameter of 11 mm was used, and its material (magnetic body) was carbon steel for cold heading (SWRCM10), which was subjected to chromizing treatment. Moreover, the cylindrical body which carries out the lamination | stacking filling of the spherical body used the SUS304 steel pipe with an internal diameter of 150 mm, and made the lamination | stacking thickness of the spherical body 450 mm. Then, a direct current voltage of 180 V was applied to the magnetic field generating coil to pass a current of 33 A, thereby generating a magnetic field [magnetic flux density of 0.3 T (Tesla)]. Further, the vibration to the cylindrical body by the vibration device was continuously applied until the processing was completed, and the frequency of the vibration was 60 Hz and the amplitude was 5 mm.

[Conventional example 1]
A slit-like magnetic filter (each thickness: 22.5 mm) is slit in a cylindrical body similar to that in Example 1 above, in a slit shape (width of each slit rod is 5 mm, gap between adjacent slit rods is 5 mm, thickness of the slit rod is 15 mm). The slit-shaped laminated filter (lamination thickness 450 mm) which laminated | stacked 20 sheets was installed changing the direction of each other. Further, the magnetic field generating coil was also provided in the same manner as in the first embodiment, and the applied voltage, the flowing current, and the generated magnetic field and vibration were the same as in the first embodiment.

〔Processing object〕
Silica powder (manufactured by Denki Kagaku Kogyo Co., Ltd., FB-570) was prepared as a filler. Then, the metal foreign matters having a diameter of 50 μm or more mixed in the filler are selected by magnets, and those remaining on the sieve of 325 mesh (aperture 45 μm) are collected, and the number of the metal foreign matters is counted using a stereomicroscope. . As a result, the number of metal foreign objects was 27 / kg.

[Removal of foreign metal]
The filler was introduced from the upper opening of the cylindrical body in each of the metal foreign matter removing apparatuses of Example 1 and Conventional Example 1, and a treated filler discharged from the lower opening of the cylindrical body was obtained. And the number of the metal foreign material was counted using the stereomicroscope with respect to the processed filler. As a result, 2 particles / kg were processed by the metal foreign matter removing apparatus of Example 1, and 15 pieces / kg were processed by the metallic foreign object removing device of Conventional Example 1.

  From the above results, it can be seen that the metal foreign matter removing apparatus of Example 1 can remove finer metal foreign matters that cannot be removed by the metal foreign matter removing apparatus of Conventional Example 1. In addition, by performing the treatment twice with the metallic foreign matter removing apparatus of Example 1, the number of metallic foreign matters became 0 / kg, and the metallic foreign matter could be completely removed.

[Comparative Example 1]
In the metallic foreign matter removing apparatus of Example 1, the spherical body that was not subjected to chromizing treatment was used. Other than that was the same as Example 1 above. And as a result of processing the said filler with the metal foreign material removal apparatus, the metal foreign material became 8 pieces / kg, and became more than the said Example 1 (2 pieces / kg). This is probably because the surface of the spherical body was not hardened by the chromizing treatment, and the metal powder was newly generated by rubbing the spherical bodies.

  In the metal foreign matter removing apparatus of the present invention, it is possible to remove even finer metal mixed as foreign matter in the granular material. For this reason, for example, in the semiconductor field, a finer metal mixed in a raw material for a semiconductor encapsulant can be removed, and a raw material for a semiconductor encapsulant that can cope with a narrow pitch in recent semiconductor devices. Obtainable.

It is explanatory drawing which shows typically an example of the metal foreign material removal apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Spherical body 2 Cylindrical body 2a Support plate 3 Magnetic field generating coil (magnetic field generating means)
4 Excitation device (excitation means)
5 containers

Claims (2)

A passage through which powder particles pass,
A plurality of spherical bodies made of a magnetic material, the surface of which is chromized and filled in the middle of the passage in a stacked state;
A magnetic field generating means for magnetizing the spherical body by generating a magnetic field in the spherical body filling space;
Vibration means for vibrating the passage intermittently or continuously,
A metal foreign matter removing apparatus, wherein the metal foreign matter is adsorbed to the spherical body by a magnetic force and removed by passing the powder body mixed with the metal foreign body through a gap between the spherical bodies in the passage.   The metallic foreign matter removing apparatus according to claim 1, wherein the passage is formed by an internal space of a cylindrical body, and the magnetic field generating means is constituted by a coil wound around an outer peripheral portion of the cylindrical body.

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