JP5245040B2 - Mold regeneration sheet - Google Patents

Description

  The present invention relates to a mold regeneration sheet used for cleaning a mold surface of a molding mold.

  For example, in the step of resin-sealing a semiconductor element by transfer molding, resin molding using a mold is repeatedly performed. As the number of repetitions (the number of shots) increases, dirt such as components, flashes, and dust that have exuded from the resin accumulate on the mold surface, particularly the cavity surface. Such dirt deteriorates the releasability when the molded product is taken out from the mold, and causes rough skin on the surface of the molded product. Therefore, the mold surface (cavity surface) of the mold is cleaned every fixed number of molding repetitions (number of shots).

As this cleaning method, a method using a cleaning sheet has been proposed (see, for example, Patent Document 1). In this method, the cleaning sheet is clamped in a state where the cleaning sheet is sandwiched between the upper mold and the lower mold, the cleaning sheet is filled into the cavity, and the cleaning sheet is heated and molded in this state. In this method, dirt is attached, and then the cleaning sheet is removed from the mold surface (cavity surface) together with the cleaning sheet.
Japanese Patent Laid-Open No. 2004-130819

  However, when the cleaning sheet is used, depending on the shape of the cavity, the air in the cavity may be difficult to escape. In such a case, there is a problem in that the air collecting portion is not filled with the cleaning sheet and the dirt is not removed.

Therefore, the present inventor has conducted research on the cause of the above air accumulation. As a result, the inventors have found that the cause is that the surface of the cleaning sheet has a uniform planar shape. That is, if the surface of the cleaning sheet is a uniform flat surface, when the cleaning sheet is sandwiched between the upper mold and the lower mold, the cleaning sheet covers the entire opening of the cavity, Even if the mold is clamped in this state, the air in the cavity is difficult to escape.

  This invention is made | formed in view of such a situation, The objective is to provide the sheet | seat for metal mold | die reproduction | regeneration which makes it easy to remove | eliminate the air in a cavity and has the outstanding filling property.

In order to achieve the above object, the mold regenerating sheet of the present invention uses a pressure at the time of mold clamping to fill the cavity with a mold cleaning material from the cavity opening of the mold. a mold reproducing sheet to be used for cleaning the interior surface of the cavity, on one or both surfaces of the plastic sheet, the mold cleaning material mainly composed of unvulcanized rubber composition, the cavity opening A plurality of strip-like patterns, grid-like patterns, or spot-like patterns protruding in a state not corresponding to the arrangement of the portions, and a predetermined upper portion of the strip-like pattern, grid-like pattern, or spot-like pattern is the cavity opening so as to close the part partially cross-sectional shape of the components of the band-shaped pattern or grid pattern is non-rectangular polygonal or semicircular Is formed, the shape of the components of the punctate pattern is formed in a conical or pyramidal, not blocked by the upper portion of the pattern, the portion of the cavity opening, into the cavity of the mold cleaning material In order to improve the filling property, it is an air bleed opening for evacuating the air in the cavity, and a space between adjacent components of the pattern is formed in the air bleed space. The configuration is as follows.

The present inventors, based on the cause investigation results of the air reservoir, and further investigations. As a result, as a mold regenerating sheet, a mold cleaning material is provided on one or both sides of a plastic sheet so as to protrude into a plurality of band-like patterns, grid-like patterns or spotted patterns having air venting gaps. When the mold surface (cavity surface) of the mold was used and cleaned, it was found that the air in the cavity was easily removed and excellent filling properties were achieved, and the present invention was achieved.

In other words, when a mold regeneration sheet in which a mold cleaning material projects on the one or both sides of a plastic sheet and protrudes in the above pattern having an air venting gap is sandwiched between an upper mold and a lower mold The protruding pattern portion of the mold cleaning material closes a part of the opening of the cavity, and the other portion of the opening is not closed by the protruding pattern portion and remains open. Then, when the mold is clamped in that state, the mold cleaning material is filled into the cavity from a part of the opening of the cavity, and accordingly, the opening of the opening is not blocked by the protruding pattern portion. The air in the cavity is pushed out from the other part. As a result, air cannot be accumulated in the cavity, and the mold cleaning material is filled to every corner of the cavity. In this state, when heat molding is performed, a mold cleaning material mainly composed of an unvulcanized rubber composition is vulcanized, and the mold surface (cavity surface) of the mold adheres to the vulcanized rubber. To do. As a result, every corner of the cavity can be cleaned.

Mold reproducing sheet of the present invention, on one or both surfaces of the plastic sheet, the mold cleaning material mainly composed of unvulcanized rubber composition, a plurality of band-shaped pattern having an air vent gap, grid-like Projected into a pattern or spotted pattern. Therefore, when the mold is cleaned using the mold regeneration sheet of the present invention, the cavity opening can be partially blocked by the protruding pattern portion of the mold cleaning material, and the mold The air in the cavity can be evacuated while filling the mold cleaning material. Thereby, the filling property of the mold cleaning material is improved, and it becomes possible to clean every corner in the cavity. In addition, since the pattern is a plurality of strips, lattices, or spots, the shape and dimensions of the pattern and the air bleed air gap are easy to set, and the mold cleaning material is suitable for filling the cavity. You can easily set the pattern.

In addition, the cross-sectional shape of the constituent elements of the band-like pattern or the lattice-like pattern is a polygon or semicircle other than a quadrangle, and the shape of the constituent elements of the spotted pattern is a cone or a pyramid. And, as a polygon other than the above-mentioned square, triangle Ru and the like.

  In particular, when the width and thickness of each component of the pattern are set in the range of 1 to 5 mm, and the gap between the adjacent components of the pattern is set in the range of 1 to 5 mm. The size is appropriate for cleaning a transfer molding die used for resin-sealing a semiconductor element, and the transfer molding die can be properly cleaned.

  Further, when the plastic sheet is a perforated sheet or a porous sheet, the surface of the plastic sheet becomes rough, so that the anchor effect of the mold cleaning material is improved. The adhesion between the sheet made and the mold cleaning material can be strengthened.

  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 shows a first embodiment of a mold regeneration sheet of the present invention. In the mold regeneration sheet of this embodiment, a mold cleaning material 2 mainly composed of an unvulcanized rubber composition is provided on both surfaces of a base sheet 1 so as to protrude in a plurality of strip patterns. The strips that are the constituent elements of the strip pattern are arranged in parallel with a gap therebetween.

  More specifically, the base sheet 1 serves as a base for projecting the mold cleaning material (band-like body) 2. And as a characteristic requested | required of the said base material sheet 1, it endures the flow pressure at the time of the said metal mold | die cleaning material (band-like body) 2 flowing in in a cavity, and it is the molding temperature (usually 100-160 degreeC). It is preferable to endure. From the viewpoint of withstanding the fluid pressure, the tear strength of the base sheet 1 is preferably 8N or more. It is because it will become easy to fracture | rupture as it is less than 8N. However, if the base sheet 1 is too hard, there is a risk of damaging the guide pins and the like provided on the mold, and therefore it is necessary to select an appropriate hardness. In addition, when the mold regeneration sheet is taken out from the mold after molding, the mold cleaning material (band-like shape) can be taken out in a state where the base sheet 1 and the vulcanized mold cleaning material (band-like body) 2 are integrated. It is preferable to select the base sheet 1 that has a strong adhesion with the body 2 and has a grip property. This is because when the mold cleaning material (band-shaped body) 2 is peeled from the base sheet 1, the mold cleaning material (band-shaped body) 2 remains in the mold (cavity) and is difficult to remove.

  An example of such a base sheet 1 is a plastic sheet. When this plastic sheet is used, when cleaning the mold surface of the mold, it is sandwiched between the molds, and when pressed, a mold cleaning material (on the surface of the base sheet 1) ( The pressurizing force sufficient to fill the band 2) to every corner in the cavity increases. Furthermore, the base material sheet 1 becomes difficult to break at the time of thermoforming or peeling (demolding) from the mold.

  Examples of the material for forming the plastic sheet include polyethylene terephthalate, polyimide, polyethylene naphthalate, polyamide (nylon), and polypropylene. Further, a material having a thickness of 0.02 to 1 mm, preferably 0.05 to 0.5 mm is used.

  Among them, from the viewpoint of improving the anchor effect of the mold cleaning material (band-shaped body) 2 and strengthening the adhesion with the mold cleaning material (band-shaped body) 2 (having grip properties), The plastic sheet is preferably a surface-roughened, perforated or porous sheet. Examples of the porous sheet include polypropylene sheets.

The size of the belt-shaped pattern made of the mold cleaning material 2 is appropriately set depending on the size and arrangement of the mold cavity, and is not particularly limited. In particular, the semiconductor element is resin-sealed (transfer molding). ) The width and thickness of each strip (each component of the pattern) are set within a range of 1 to 5 mm, and the gap between adjacent strips (facing each other) is 1 to 5 mm. It is preferable to set within the range. In addition, although the cross-sectional shape of each said strip | belt-shaped body has shown the trapezoid thing as reference form in FIG. 1, a rectangle is mention | raise | lifted as another reference form . Further, triangles, other polygons, semicircular be mentioned as an embodiment.

  The color of the mold cleaning material (strip-shaped body) 2 is not particularly limited, but is preferably white or gray. The reason is that the dirt to be removed from the mold cavity is a dark color such as black, so after cleaning, it can be easily confirmed with the naked eye that the dirt has adhered to the mold regeneration sheet, This is because the cleaning status can be easily confirmed. In order to make the light color, a white pigment or the like is added to the unvulcanized rubber composition.

  As described above, the mold cleaning material 2 is mainly composed of an unvulcanized rubber-based composition, and depending on the cleaning contents shown in the following (A) and (B), The composition mixed in the vulcanized rubber composition is different. That is, in the above cleaning, (A) removing dirt on the mold surface (cavity surface) of the mold, and (B) removing dirt from the mold surface (cavity surface) of the mold, Imparting releasability to the mold surface (cavity surface).

  First, (A), that is, a first example of the mold cleaning material 2 for the purpose of removing dirt will be described. In this first example, an unvulcanized rubber fabric made of a mixture of unvulcanized rubber and glycol ethers represented by the following general formula (1) is used as a base material.

  The glycol ethers represented by the general formula (1) include ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether. , Diethylene glycol monobutyl ether, diethylene glycol diethyl ether, diethylene glycol propyl ether, diethylene glycol dibutyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol mono Or the like can be mentioned Chirueteru.

Among the glycol ethers represented by the general formula (1), when n = 1 to ₂ , any one of R ₁ and R ₂ is hydrogen, the other is an alkyl group having 1 to 4 carbon atoms, , R ₁ and R ₂ are both alkyl groups, they are preferably alkyl groups having 1 to 4 carbon atoms. In addition, when n takes a value of 3 or more, compatibility with rubber is reduced, and when the carbon number of the alkyl group is 5 or more, the mold surface (cavity surface) of the mold There is a tendency that the permeability to dirt becomes worse.

  The above glycol ethers may be used as they are or mixed with water or alcohols such as methanol, ethanol and n-propanol, and organic solvents such as toluene and xylene. When mixing with an organic solvent, the amount of the organic solvent is usually 50 parts or less with respect to 100 parts by weight of glycol ethers (hereinafter abbreviated as “parts”), and most commonly 20 parts or less. To be done. Moreover, there is no problem even if a conventional release agent is used in an appropriate amount if necessary. When a release agent is used in combination, the amount used is 10 parts or less with respect to 100 parts of the total amount of unvulcanized rubber fabric and glycol ethers, most commonly 2 to 5 parts. To be done.

  Unvulcanized rubber includes natural rubber (NR), chloroprene rubber (CR), butadiene rubber (BR), nitrile rubber (NBR), ethylene propylene diene rubber (EPDM), ethylene propylene rubber (EPM), styrene butadiene rubber ( SBR), polyisoprene rubber (IR), butyl rubber (IIR), silicone rubber (Q), fluorine rubber (FKM), etc., alone or as a main component, and a vulcanizing agent is added and vulcanized as necessary. Those containing accelerators, reinforcing agents and the like are used. This unvulcanized rubber is vulcanized in the mold to become vulcanized rubber. EPDM, EPM, SBR, NBR, BR or a mixture thereof is preferable as the above-mentioned unvulcanized rubber.

The above EPDM is a copolymer comprising ethylene, α-olefin and a cyclic or non-cyclic structure having a non-conjugated double bond. More specifically, EPDM is a terpolymer composed of ethylene, α-olefin (particularly propylene) and polyene monomers listed below. Examples of the polyene monomer include dicyclopentadiene, 1,5-cyclooctadiene, 1 , 1-cyclooctadiene, 1,6-cyclododecadiene, 1,7-cyclododecadiene, 1,5,9-cyclododecatriene, 1,4-cycloheptadiene, 1,4-cyclohexadiene, norbornadiene, Methylene norbornene, 2-methylpentadiene-1,4,1,5-hexadiene, 1,6-heptadiene, methyl-tetrahydroindene, 1,4-hexadiene and the like. The copolymerization ratio of each monomer is preferably a terpolymer in which ethylene is 30 to 80 mol%, polyene is 0.1 to 20 mol%, and the remainder is α-olefin. More preferably, ethylene is 30 to 60 mol%. And the thing with Mooney viscosity ML1 _{+ 4} (100 degreeC) of 20-70 is good.

As the SBR, those having a styrene content of 15 to 30 mol% and a Mooney viscosity ML _{1 + 4} (100 ° C.) of 20 to 80, preferably 35 to 60 are suitable.

As the NBR, it is preferable to use an NBR having an acrylonitrile content of 20 to 60 mol%, preferably 25 to 45 mol%, and a Mooney viscosity ML _{1 + 4} (100 ° C.) of 20 to 85, preferably 30 to 70. is there.

As the BR, 1,2 polybutadiene or 1,4 polybutadiene is used alone or in combination, and Mooney viscosity ML _{1 + 4} (100 ° C.) is 20 to 85, preferably 30 to 60.

  And the said glycol ether becomes unvulcanized rubber cloth by mixing with the said unvulcanized rubber. In this case, the glycol ether is usually blended in an amount of 10 to 60 parts with respect to 100 parts of the unvulcanized rubber. Preferred is about 15 to 25 parts. And it is preferable that the boiling point of the said glycol ethers is about 130-250 degreeC. That is, mold molding is usually performed at 150 to 185 ° C., and if the boiling point of the glycol ethers is less than 130 ° C., the evaporation during cleaning is significant, and therefore, the cleaning work environment may be deteriorated. On the contrary, if it exceeds 250 ° C., it becomes difficult to evaporate and remains in the vulcanized rubber, and the strength of the vulcanized rubber when it is taken out from the mold becomes weak and deformed. This is because it becomes difficult to sufficiently remove the dirt from the mold surface of the mold, and the cleaning workability tends to be reduced.

  The mold cleaning material 2 using the unvulcanized rubber fabric as a base material includes an inorganic reinforcing agent (such as silica, alumina, calcium carbonate, aluminum hydroxide, titanium oxide) as a reinforcing agent in the unvulcanized rubber. It is also possible to add a filler. In this case, the use amount of the reinforcing agent is preferably set to 10 to 50 parts with respect to 100 parts of the unvulcanized rubber. Further, as described above, a release agent can be blended. Examples of the release agent include stearic acid, zinc stearate, carnauba wax, montan wax, stearylethylenediamide and the like. It is possible to add 1 to 10 parts of these to 100 parts of unvulcanized rubber.

  Next, (A), that is, a second example of the mold cleaning material 2 for the purpose of removing dirt will be described. This second example is based on an unvulcanized rubber fabric made of a mixture of an unvulcanized rubber and at least one of imidazoles and imidazolines (imidazoles and / or imidazolines). In the second example, the difference from the first example will be mainly described.

  As the imidazoles, use of imidazoles represented by the following general formula (2) brings about good results. Representative examples of such imidazoles include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 1-benzyl-2-methylimidazole, and the like, 2,4-diamino-6 [2 '-Methylimidazolyl (1)'] ethyl-s-triazine, 2,4-diamino-6 [2'-ethyl-4'-methylimidazolyl- (1) '] ethyl-s-triazine, and the like.

  As the imidazolines, use of imidazolines represented by the following general formula (3) brings about good results. Representative examples of such imidazolines include 2-methylimidazoline, 2-methyl-4-ethylimidazoline, 2-phenylimidazoline, 1-benzyl-2-methylimidazoline, 2-phenyl-4-methyl-5-hydroxy. Methylimidazoline, 2,4-diamino-6 [2′methylimidazolyl- (1) ′] ethyl-s-triazine, 2,4-diamino-6 [2′-methyl-4′-ethylimidazolylyl- (1 ) ′] Ethyl-s-triazine, 1-cyanoethyl-2-methylimidazoline, 1-cyanoethyl-2-methyl-4-ethylimidazoline and the like.

  Next, (A), that is, a third example of the mold cleaning material 2 for the purpose of removing dirt will be described. In this third example, an unvulcanized rubber fabric made of a mixture of unvulcanized rubber and amino alcohols is used as a base material. In the third example, portions different from the first example will be mainly described.

  Use of the following amino alcohols as the amino alcohols brings about good results. That is, monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, N, N-dimethylethanolamine, N, N-dibutylethanolamine, N, N-diethylethanolamine, N-methyl-N, N- Examples include diethanolamine, 2-amino-2-methylpropanol, 3-aminopropanol, and 2-aminopropanol.

  Next, the above-mentioned (B), that is, the mold cleaning material 2 for the purpose of imparting releasability will be described. In this case, an unvulcanized rubber cloth made of a mixture of unvulcanized rubber and a release agent is used as a base material. Here, a different part from the said 1st example is mainly demonstrated.

  Examples of the release agent include long chain fatty acids such as stearic acid and behenic acid, metal salts of long chain fatty acids represented by zinc stearate and calcium stearate, carnauba wax, montan wax, and partially saponified esters of montanic acid. Specific examples include ester waxes, long-chain fatty acid amides represented by stearylethylenediamide, and paraffins represented by polyethylene wax.

  The mold cleaning material 2 can be obtained by mixing the unvulcanized rubber and the release agent by a known method, for example, using a calender roll or the like. It can also be obtained by a method such as kneading a release agent. In these cases, the release agent is usually blended in an amount of 1 to 50 parts per 100 parts of the unvulcanized rubber fabric. Preferred is 3 to 20 parts. And as said mold release agent, that whose melting | fusing point is 200 degrees C or less and whose boiling point is 200 degrees C or more is preferable. Furthermore, a thing with melting | fusing point of 50-150 degreeC is preferable. That is, mold molding is usually performed at 150 to 200 ° C. If the melting point of the mold release agent is greater than 200 ° C., the mold release agent does not exude to the mold surface of the mold, and the boiling point is low. This is because if the temperature is lower than 200 ° C., the mold release agent evaporates even if it exudes to the mold surface, and the function tends to be lost.

  And the manufacturing method of the said sheet | seat for metal mold | die reproduction | regeneration is performed as follows using the said base material sheet 1 and the metal mold | die cleaning material 2, for example. That is, first, the mold cleaning material 2 is kneaded with a continuous kneader or a batch kneader, and then disposed on both surfaces of the substrate sheet 1. Next, it is sandwiched and pressed between two molds in which concave portions corresponding to the protruding pattern (band pattern) of the mold cleaning material 2 are formed. And it winds up or cut | disconnects to an appropriate dimension. In this way, the mold regeneration sheet can be produced.

  In addition, the space | gap part between adjacent metal mold | die cleaning materials (strip | belt-shaped body) 2 may expose the base material sheet 1, and may be covered with the metal mold | die cleaning material 2. FIG. When it is covered, the thickness is preferably 20% or less of the thickness of the mold cleaning material (band-like body) 2.

  A method of cleaning the mold surface (cavity surface) using such a mold regeneration sheet can be performed, for example, as follows. That is, first, as shown in FIG. 2, the mold regeneration sheet is sandwiched between the upper mold 11 and the lower mold 12. Thereby, a part of the opening of the cavity 13 is blocked by the mold cleaning material (band-shaped body) 2, and the other part of the opening is not blocked by the mold cleaning material (band-shaped body) 2. Will remain. Then, the mold is clamped in this state. As a result, the mold cleaning material 2 of the mold regeneration sheet is pressed against the mold surfaces of the upper mold 11 and the lower mold 12 and filled into the cavity 13. At this time, from the other part of the opening of the cavity 13 that is not blocked by the mold cleaning material (band-like body) 2, the inside of the cavity 13 is filled with the filling of the mold cleaning material 2 into the cavity 13. Air is pushed out and the mold cleaning material 2 is filled to every corner in the cavity 13. That is, the air gap between the mold cleaning materials (band-like bodies) 2 adjacent to each other (facing each other) is an air vent gap. Next, it heat-molds in this state. As a result, the mold cleaning material 2 mainly composed of the unvulcanized rubber-based composition is heated and vulcanized to form a vulcanized rubber, and is molded into the shape of the cavity 13. At this time, the dirt in the cavity 13 is integrated with the vulcanized rubber 2a (see FIG. 3). Thereafter, as shown in FIG. 3, the upper mold 11 and the lower mold 12 are separated, and the mold regeneration sheet is removed. At this time, dirt on the mold surfaces of the upper mold 11 and the lower mold 12 (the surface of the cavity 13) integrated with the vulcanized rubber 2a is removed. In this way, cleaning is performed.

  Further, when the mold surfaces of the upper mold 11 and the lower mold 12 (surfaces of the cavities 13) are given release properties, the process is performed in the same manner. The contained release agent exudes, and release properties can be imparted to all corners of the cavity 13 (attachment of the release agent).

  FIG. 4 shows a second embodiment of the mold regeneration sheet of the present invention. In the mold regeneration sheet of this embodiment, the belt-shaped mold cleaning material (band-shaped body) 2 is formed on one side of a base sheet 1. Other than that, it is the same as the mold reproducing sheet of the first embodiment shown in FIG. 1, and the same reference numerals are given to the same parts.

  When using the sheet | seat for metal mold | die reproduction | regeneration of this 2nd Embodiment, as shown in FIG. 5, it folds so that the base material sheet 1 may become inside, and it uses it in the state which faced the base material sheets 1 mutually. . Thereby, there exists an effect | action and effect similar to the sheet | seat for metal mold | die reproduction | regeneration of the said 1st Embodiment.

  FIG. 6 shows a third embodiment of the mold regeneration sheet of the present invention. In the mold regeneration sheet of this embodiment, the mold cleaning material 2 is formed in a lattice shape. This lattice shape is obtained by vertically and horizontally forming strips in the mold regeneration sheet of the first embodiment shown in FIG. Other than that, it is the same as the mold reproducing sheet of the first embodiment shown in FIG. 1, and the same reference numerals are given to the same parts. And the same operation and effect as the metallic mold reproduction sheet of the 1st embodiment of the above are produced.

  FIG. 7 shows a fourth embodiment of the mold regeneration sheet of the present invention. In the mold regeneration sheet of this embodiment, the mold cleaning material 2 is formed in a spot shape. Other than that, it is the same as the mold reproducing sheet of the first embodiment shown in FIG. 1, and the same reference numerals are given to the same parts. And the same operation and effect as the metallic mold reproduction sheet of the 1st embodiment of the above are produced.

The shape of each spot-like mold cleaning material 2 in the fourth embodiment is a truncated cone as a reference form in FIG. 7, but a cone and a pyramid are given as an embodiment . Incidentally, cylindrical, prismatic, cylindrical, square tube, etc. as another reference embodiment.

  Next, examples will be described together with comparative examples.

[Plastic sheet]
As the base material sheet, a punched sheet, a punched sheet, and a porous sheet were prepared. Among them, a polyethylene terephthalate film, a polyimide film, a polyethylene naphthalate film, a nylon 6 film, and a polypropylene film were prepared, and a polyethylene terephthalate film, nylon 12 A made film was prepared, and a polypropylene porous sheet (manufactured by Nitto Denko Corporation) was prepared as a porous sheet. In addition, the said perforation process was set as the process which forms a circular hole with a diameter of 1 mm at a 2 mm pitch vertically and horizontally. Moreover, all the base material sheets were 50 micrometers in thickness.

[Mold cleaning material]
100 parts of ethylene propylene rubber, 50 parts of silica powder, 5 parts of titanium oxide, 2 parts of organic peroxide [n-butyl-4,4-bis (t-butylperoxy) valerate], imidazole {2,4-diamino- A mold cleaning material was prepared by kneading 10 parts of 6- [2'-methylimidazolyl- (1 ')] ethyl-s-triazine} and 5 parts of montan wax with a kneader.

[Examples 1-8]
The mold cleaning material was projected on both surfaces of the substrate sheet in the pattern (band shape, lattice shape, spot shape) and dimensions (width, thickness, gap) shown in Table 1 below.

[Comparative Examples 1-3]
The mold cleaning material was formed on both surfaces of the base sheet in a uniform planar shape (a sheet with a uniform thickness).

[Filling rate / fillability]
The molds were cleaned using the mold regeneration sheets of Examples 1 to 8 and Comparative Examples 1 to 3 thus obtained. This mold is a transfer molding mold used for resin-sealing a semiconductor element. The mold includes an upper mold and a lower mold. Each mold surface (opposing surface) of these upper mold and lower mold. Is a rectangle of 24 mm × 91 mm. Moreover, the shape of each cavity in the state of mold clamping is a rectangular parallelepiped shape, and the dimension is 4 mm × 5 mm × 2 mm (height). Further, 16 cavities are formed, and 8 cavities are arranged in parallel in two rows. The interval between the two rows is 10 mm, and the interval between adjacent cavities in each row is 1 mm. The filling rate was evaluated for the filling rate of the cavity having the worst filling property among the 16 cavities. The filling rate was determined by the ratio between the bottom area of the cavity and the bottom area of the vulcanized rubber that was thermoformed into a cavity shape by cleaning. The cleaning conditions were as follows: the mold regeneration sheet had the same dimensions as the mold surface, the mold clamping gap was 0.5 mm, the molding temperature was 175 ° C., and the molding time was 5 minutes.

[Cleanability]
When the filling rate is 100%, it was evaluated as “good” because it was cleaned to every corner of the cavity, and when the filling rate was less than 100%, the cavity was insufficiently cleaned and evaluated as “x”. These are also shown in Tables 1 and 2 below.

  From the results of Tables 1 and 2, it can be seen that the mold regeneration sheets of Examples 1 to 8 are more excellent in filling and cleaning than the mold regeneration sheets of Comparative Examples 1 to 3.

It is a perspective view which shows 1st Embodiment of the sheet | seat for metal mold | die reproduction | regeneration of this invention. It is explanatory drawing which shows the cleaning method using the said sheet | seat for metal mold | die reproduction | regeneration. It is explanatory drawing which shows the said cleaning method. It is a perspective view which shows 2nd Embodiment of the sheet | seat for metal mold | die reproduction | regeneration of this invention. It is explanatory drawing which shows the usage method of the said sheet | seat for metal mold | die reproduction | regeneration. It is a perspective view which shows 3rd Embodiment of the sheet | seat for metal mold | die reproduction | regeneration of this invention. It is a perspective view which shows 4th Embodiment of the sheet | seat for metal mold | die reproduction | regeneration of this invention.

Explanation of symbols

1 Base sheet 2 Mold cleaning material

Claims (4)

A mold regeneration sheet that is used when a mold cleaning material is filled into a cavity from the cavity opening of the mold and the inner surface of the cavity is cleaned by using pressure at the time of mold clamping. In addition, on one or both sides of the plastic sheet, a mold cleaning material mainly composed of an unvulcanized rubber-based composition does not correspond to the arrangement of the cavity openings, and a plurality of belt-like patterns and lattice shapes A component of the band-like pattern or grid- like pattern that protrudes from the pattern or spot-like pattern and that the predetermined upper part of the band-like pattern, grid-like pattern or spot-like pattern partially closes the cavity opening The cross-sectional shape is a polygon other than a rectangle or a semicircle, and the shape of the constituent elements of the spotted pattern is a cone. Others are formed in a pyramid, not blocked by the upper portion of the pattern, the portion of the cavity opening, in order to improve the filling property into the cavity of the mold cleaning material, removing the air in the cavity An air vent opening for the above, and a gap between adjacent components of the above pattern is formed in the air vent gap.   2. The mold regeneration sheet according to claim 1, wherein the polygon other than the square is a triangle.   The width and thickness of each component of the pattern are set within a range of 1 to 5 mm, and the gap between adjacent components of the pattern is set within a range of 1 to 5 mm. 2. A mold regeneration sheet according to 2.   The mold regeneration sheet according to any one of claims 1 to 3, wherein the plastic sheet is a perforated sheet or a porous sheet.

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