JP2549829B2 - Cleaning mold for semiconductor mold - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning sheet for cleaning a mold for semiconductor encapsulation.

[0002]

2. Description of the Related Art Semiconductor elements such as transistors, ICs, and LSIs are sealed in ceramic packages or plastic packages to form semiconductor devices. The ceramic package itself has heat resistance,
It has excellent moisture resistance, so it is strong against temperature and humidity.
Moreover, since it is a hollow package, high mechanical strength and highly reliable sealing are possible. However, since the constituent materials are relatively expensive and there is a drawback that mass productivity is insufficient, recently, resin sealing using a plastic package instead of the ceramic package has become mainstream.
An epoxy resin composition is used for this type of resin encapsulation, and resin encapsulation is performed by casting, compression molding, injection molding, transfer molding, or the like. And resin encapsulation by transfer molding, which excels in workability, is a prize.

[0003]

However, when the semiconductor element is resin-sealed with the epoxy resin composition by the transfer molding as described above, if the molding is continuously performed, the separation in the epoxy resin composition is prevented. The transfer agent is contaminated by the mold agent, which causes a problem that good molding cannot be achieved. That is, at the time of the above-mentioned molding, the release agent contained in the epoxy resin composition exudes to the surface of the mold to exert a release action,
When the molding is repeated, the release agent exuded on the mold surface is
The layers are sequentially laminated on the surface of the mold, and gradually deteriorated by oxidation to form a hard release agent oxidation deterioration layer (the surface is not smooth like the mold). Then, the molding material comes to be molded on the surface of the oxidation-deteriorated layer, and the surface of the oxidation-deteriorated layer is transferred to the molded product, so that the surface of the molded product is not roughened and gloss is not generated. Cause Further, once such an oxidation-deteriorated layer of the release agent is formed on the surface of the mold, the release agent exuding from the composition when molding the epoxy resin composition is It acts not on the mold surface but on the oxidation-deteriorated layer of the above-mentioned mold release agent, so that a sufficient mold release effect cannot be exhibited. In order to solve such problems,
Conventionally, as shown in the drawings, a semiconductor element having a lead frame 5 is positioned in a cavity 4 formed by an upper die 2 and a lower die 3 of a molding die 1, and the lead frame 5 is placed in the cavity 4 described above. Is positioned between the upper mold 2 and the lower mold 3 which are adjacent to each other, and in that state, a melamine resin molding material is cast and molded and cured, and the mold release agent oxidation deterioration layer on the surface of the mold is used as the molded product. It is performed that the surface of the mold is cleaned by taking out a molded product which is integrated and the oxidation deterioration layer is integrated from the mold 1. In this case, the lead frame 5 is positioned in the cavity 4 and the melamine resin molding material is cast by the upper mold 2 adjacent to the cavity 4 with the upper mold 2 and the lower mold 3 closed. Since there is a gap 6 for the lead frame 5 between the lower mold 3 and the lower mold 3, do not position the lead frame 5 there,
This is because if only the melamine resin molding material is cast into the cavity 4, the melamine resin molding material will escape from the gap 6 between the upper mold 2 and the lower mold 3 and molding cannot be performed sufficiently. However, in the case of cleaning the die surface in this way, as described above, the lead frame must be properly positioned in each cavity 4 to be cleaned, and the work is complicated and at the same time, Formalin is by-produced as a condensate of the above melamine resin molding material to generate odor and the like, which deteriorates the work environment and causes a decrease in workability of the cleaning work. Further, when the semiconductor element is resin-sealed by the transfer molding as described above, a burr is generated in the peripheral portion of the cavity 4, and the burr is automatically removed by the air blown from the air nozzle. However, at times, burrs may occur on the portion of the mold 1 that cannot be completely processed by the air nozzle, and in that case, a person must remove the burrs with a finger or the like. It will not be possible. Generally, the transfer mold molding is performed by automatic molding, and in the above cases,
It has become standard work to release the automatic molding, stop the device and deburr. However, if the work is delayed, rarely while automatic molding continues, insert a finger or the like between the molds 2 and 3 within a short time when the mold 1 is open, Burrs that cannot be completely removed by the nozzle are removed, which is extremely dangerous.

The present invention has been made in view of the above circumstances, and provides a cleaning die cleaning sheet for molding a semiconductor, which is capable of easily and efficiently cleaning the die surface, deburring, and the like. To aim.

[0005]

In order to achieve the above object, the present invention provides a cleaning sheet for cleaning the die surface of the transfer molding die by sandwiching it between a pair of transfer molding dies and applying heat and pressure. Therefore, the gist is a semiconductor mold sealing die cleaning cleaning sheet made of unvulcanized rubber material.

[0006]

In other words, the above-mentioned cleaning sheet is sandwiched between a pair of transfer molding dies and heated and pressed to perform the complicated work of positioning and arranging the lead frame one by one in the cavity of the molding dies. The mold surface can be cleaned without needing to do so. At this time, formalin odor is not generated unlike the conventional case. As a result, the efficiency of mold cleaning can be increased. At that time, burrs adhering to the part of the mold surface adjacent to the cavity are also adhered to and removed from the cleaning sheet at the same time. The dangerous work of plugging in and removing the burr is completely unnecessary,
Deburring can be performed safely.

The present invention relates to a cleaning sheet for cleaning the die surface of a transfer molding die. The cleaning sheet is made of, for example, unvulcanized rubber cloth made of unvulcanized rubber and a removal aid.

As the unvulcanized rubber, natural rubber (N
R), chloroprene rubber (CR), butadiene rubber (B
R), nitrile rubber (NBR), ethylene propylene terpolymer rubber (EPT), ethylene propylene rubber (EPM), styrene butadiene rubber (SBR), polyisoprene rubber (IR), butyl rubber (IIR), silicone rubber (Q), A fluororubber (FKM) or the like as a main component, a vulcanizing agent, and optionally a vulcanization accelerator and a reinforcing agent are used. This unvulcanized rubber is vulcanized into a vulcanized rubber in the mold. The above-mentioned unvulcanized rubber is preferably EPT, SBR, NBR or a mixture thereof. The EPT is a cyclic or acyclic copolymer having ethylene, α-olefin and a non-conjugated double bond. More specifically, EPT is a terpolymer composed of ethylene, α-olefin (particularly propylene) and the polyene monomers listed below, and the polyene monomers include dicyclopentadiene, 1,5-cyclooctadiene, and 1-cyclooctadiene. , 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 30 to 80 mol% of ethylene,
The ratio is such that the polyene is 0.1 to 20 mol% and the rest is α-olefin. More preferably, ethylene is 30 to 60 mol%. The Mooney viscosity ML _{1 + 4} (100 ° C.) is preferably 20 to 70. Specific examples of the EPT include Mitsui EPTs 4021, 4045, and 4070 manufactured by Mitsui Petrochemical Co., Ltd. Also, SBR has a styrene content of 15
Mooney viscosity ML _{1 + 4} (100 ° C) is 2 at ~ 30 mol%
Those of 0 to 80, preferably 35 to 60 are suitable.
Specific examples thereof include JSR-1502, JSR-1507, and JSR-1778, manufactured by Japan Synthetic Rubber Co., Ltd. The NBR has an acrylonitrile content of 20 to 60 mol%, preferably 25 to 45 mol%, and a Mooney viscosity ML _{1 + 4} (1
It is suitable to use one having a temperature of 00 ° C.) of 20 to 85, preferably 30 to 70. As a specific example, N-234L, 230S, and 230SH manufactured by Japan Synthetic Rubber Co., Ltd. can be mentioned.

The removal aids used with the unvulcanized rubber are glycol ethers, imidazoles and imidazolines, which may be used alone or in combination.

As the glycol ethers, those represented by the following general formula (1) are preferable.

[0011]

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Specific examples thereof 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,
Examples thereof include 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 and ethylene glycol monobutyl ether.

Among the glycol ethers represented by the above general formula (1), when n = 1 to ₂ and either R ₁ or R ₂ is hydrogen, the other is an alkyl group having 1 to 4 carbon atoms. And when R ₁ and R ₂ are both alkyl groups,
An alkyl group having 1 to 4 carbon atoms is preferable.
When n has a value of 3 or more, the compatibility with rubber is lowered, and when the number of carbon atoms of the alkyl group is 5 or more, the permeability of the release agent to the oxidative deterioration layer is increased. The tendency is to become worse.

As the imidazoles, it is possible to obtain good results by using the imidazoles represented by the following general formula (2). Typical examples of such imidazoles include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 1-benzyl-2-methylimidazole, and 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.

[0015]

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As the above-mentioned imidazolines, it is possible to obtain good results by using the imidazolines represented by the following general formula (3). Typical examples of such imidazolines include 2-methylimidazoline and 2-methyl-4.
-Ethylimidazoline, 2-phenylimidazoline, 1
-Benzyl-2-methylimidazoline, 2-phenyl-
4-methyl-5-hydroxymethyl imidazoline, 2,
4-diamino-6 [2'methylimidazolyl-
(1) ′] Ethyl-s-triazine, 2,4-diamino-6 [2′-methyl-4′-ethylimidazolyl-
(1) ′] Ethyl-s-triazine, 1-cyanoethyl-2-methylimidazoline, 1-cyanoethyl-2-methyl-4-ethylimidazoline and the like.

[0017]

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The above glycol ethers, imidazoles and imidazolines may be used as they are, or in a mixture with water or an alcohol such as methanol, ethanol or n-propanol, or an organic solvent such as toluene or xylene. Good. When mixed with an organic solvent, the amount of the organic solvent is usually glycol ethers,
The total amount of imidazoles and imidazolines is 100 parts by weight (hereinafter abbreviated as "part"), and is 50 parts or less, and most commonly 20 parts or less. Further, a conventionally used release agent such as stearic acid, carnauba wax, or stearylethylenediamide may be used in an appropriate amount, if necessary. When a release agent is used in combination, the amount used is unvulcanized rubber,
The total amount of 100 parts with at least one of the glycol ethers, imidazoles and imidazolines is 10 parts or less, and most commonly 2 to
There will be 5 copies.

The above glycol ethers, imidazoles and imidazolines, alone or in combination, are mixed with the above unvulcanized rubber to form unvulcanized rubber material and a cleaning sheet. In this case, the glycol ethers, imidazoles, and imidazolines alone or in combination are usually 5 to 60 parts with respect to 100 parts of the unvulcanized rubber.
Partly compounded. Preferred is 15 to 25 parts. The glycol ethers have a boiling point of 130 to 2
It is preferably about 50 ° C. That is, the mold molding is usually performed at 150 to 185 ° C., and if the boiling point of the glycol ether is less than 130 ° C., the evaporation during cleaning is remarkable, and therefore the cleaning work environment may deteriorate. On the contrary, when the temperature 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 is weakened and the metal is deformed. This is because it becomes difficult to sufficiently peel off the oxidation-deteriorated layer of the release agent from the mold surface, and the workability for cleaning tends to decrease.

Further, the cleaning sheet made of the unvulcanized rubber material may be blended with an inorganic reinforcing agent (filler) such as silica, alumina, calcium carbonate, aluminum hydroxide, titanium oxide as a reinforcing agent. is there. In this case, the amount of the reinforcing agent used is preferably set to 10 to 50 parts per 100 parts of unvulcanized rubber.

The cleaning sheet made of unvulcanized rubber material preferably has a total content of chlorine ions and sodium ions of 2000 ppm or less. That is, when cleaning the die surface of the transfer mold with the above cleaning sheet, chlorine ions and sodium ions contained in the cleaning sheet remain on the die surface, and these ionic impurities are contained in the semiconductor device. This is because there is a risk that they will enter, and if the above-mentioned ionic impurities enter these semiconductor devices, a serious problem will occur in terms of reliability such as moisture resistance reliability. Therefore, when manufacturing the cleaning sheet made of the unvulcanized rubber fabric, it is desirable to thoroughly examine the raw materials used and to use the one that does not contain the above ionic impurities.

According to the present invention, when the semiconductor element is continuously resin-sealed by transfer molding to continuously manufacture the semiconductor device, the cleaning sheet as described above is used to clean the mold surface of the mold. After cleaning, transfer molding can be continuously performed to manufacture a semiconductor device. At this time, the molding material used for sealing is not particularly limited, and a conventionally known molding material such as an epoxy resin molding material is used, and molding conditions and the like are set according to the conventional method.

The semiconductor device manufactured in this manner is
Since the molding die is molded in a good cleaning state, the surface condition of the sealing resin is extremely good.

[0024]

According to the present invention, prior to transfer molding, a cleaning sheet is used to remove the oxidation-deteriorated layer of the release agent formed on the surface of the mold, and deburring is performed. Therefore, cleaning of the mold is extremely easy. You can do that,
No odor is generated. Also, deburring can be performed safely.

Next, examples will be described in detail together with comparative examples.

[0026]

Example 1 Ethylene propylene terpolymer rubber (E
PT, Mitsui Petrochemical Industry Co., Ltd., Mitsui EPT4045) 1
After kneading 00 parts, 20 parts of silica powder, 5 parts of titanium oxide, 4 parts of organic peroxide, 1 part of stearic acid and 20 parts of diethylene glycol dibutyl ether with a kneading roll, a rolling roll is used to form a sheet having a thickness of 7 mm. A mold cleaning cleaning sheet was obtained.

[0027]

Example 2 In place of diethylene glycol dibutyl ether, ethylene glycol monoethyl ether was used. A mold cleaning cleaning sheet was obtained in the same manner as in Example 1 except for the above.

[0028]

Example 3 100 parts of styrene-butadiene rubber (SBR, JSR-1502 manufactured by Japan Synthetic Rubber Co., Ltd.), 20 parts of silica powder, 5 parts of aluminum hydroxide, 4 organic peroxides
Parts, 1 part of zinc stearate, and 15 parts of diethylene glycol monomethyl ether to obtain a mold cleaning cleaning sheet in the same manner as in Example 1.

[0029]

Example 4 100 parts of nitrile rubber (NBR, N-230SH manufactured by Japan Synthetic Rubber Co., Ltd.), silica powder 20
Part, titanium oxide 5 parts, organic peroxide 4 parts, stearic acid 1 part, and ethylene glycol monoethyl ether 15 parts to obtain a mold cleaning cleaning sheet in the same manner as in Example 1.

[0030]

Example 5 The usage rate of ethylene glycol monoethyl ether was reduced to 12 parts. A mold cleaning cleaning sheet was obtained in the same manner as in Example 4 except for the above.

[0031]

Example 6 The amount of ethylene glycol monoethyl ether used was increased to 55 parts. A mold cleaning cleaning sheet was obtained in the same manner as in Example 4 except for the above.

[0032]

Example 7 EPT was not used alone, but was used in combination with the SBR used in Example 3 (50:50). A mold cleaning cleaning sheet was obtained in the same manner as in Example 1 except for the above.

[0033]

Example 8 Ethylene propylene terpolymer rubber (E
PT, Mitsui Petrochemical Industry Co., Ltd., Mitsui EPT4045) 1
After kneading 00 parts, silica powder 20 parts, titanium oxide 5 parts, organic peroxide 4 parts, stearic acid 1 part, and 2-ethyl-4-methylimidazole 3 parts with a kneading roll, a rolling roll is used to obtain a thickness of 7 mm. To obtain a desired mold cleaning cleaning sheet.

[0034]

Examples 9, 10 The amount of 2-ethyl-4-methylimidazole was changed to 20 parts and 50 parts, respectively. Otherwise, in the same manner as in Example 1, a target mold cleaning cleaning sheet was obtained.

[0035]

Examples 11, 12 Instead of 2-ethyl-4-methylimidazole, 2,4-diamino-6 [2'-methylimidazolyl- (1) '] ethyl-s-triazine (hereinafter "2MZ-AZINE") was used. Abbreviated) was used in 3 parts and 20 parts, respectively. A mold cleaning cleaning sheet was obtained in the same manner as in Example 1 except for the above.

[0036]

Example 13 In place of 2-ethyl-4-methylimidazole, 10 parts of 2MZ-AZINE and 10 parts of 1-cyanoethyl-2-methylimidazole were used in combination. A mold cleaning cleaning sheet was obtained in the same manner as in Example 1 except for the above.

[0037]

Examples 14 and 15 100 parts of styrene-butadiene rubber (SBR, JSR-1502 manufactured by Japan Synthetic Rubber Co., Ltd.) was used instead of the ethylene propylene terpolymer rubber, and
5 parts and 20 parts of 2-methylimidazoline were used instead of ethyl-4-methylimidazole, respectively. A mold cleaning cleaning sheet was obtained in the same manner as in Example 1 except for the above.

[0038]

[Examples 16 and 17] Half of the ethylene propylene terpolymer rubber was replaced with the styrene-butadiene rubber, and 2-phenyl-4-methylimidazole was replaced with 2-phenylimidazoline in an amount of 5 parts and 20 parts, respectively.
A mold cleaning cleaning sheet was obtained in the same manner as in Example 1 except for the above.

[0039]

Example 18 In place of the ethylene propylene terpolymer, 50 parts of the above styrene-butadiene rubber and 50 parts of nitrile rubber (NBR, N-230SH manufactured by Nippon Synthetic Rubber Co., Ltd.) were used and 2-ethyl-4-methylimidazole was prepared. Instead 1-cyanoethyl-2-methylimidazole 10
Parts and 10 parts of 1-cyanoethyl-2-methyl-4-ethylimidazoline. A mold cleaning cleaning sheet was obtained in the same manner as in Example 1 except for the above.

[0040]

Comparative Example 1 2-Amino-2-methyl-1-propanol was used in place of diethylene glycol dibutyl ether. A mold cleaning cleaning sheet was obtained in the same manner as in Example 1 except for the above.

[0041]

Comparative Example 2 Toluene was used instead of ethylene glycol monoethyl ether. A mold cleaning cleaning sheet was obtained in the same manner as in Example 2 except for the above.

[0042]

Comparative Example 3 Diisopropyl ketone was used in place of diethylene glycol monomethyl ether. A mold cleaning cleaning sheet was obtained in the same manner as in Example 3 except for the above.

[0043]

Comparative Example 4 Ethanol was used in place of ethylene glycol monoethyl ether. A mold cleaning cleaning sheet was obtained in the same manner as in Example 4 except for the above.

The mold cleaning / cleaning sheets obtained in the above Examples and Comparative Examples were sandwiched between thermosetting resin molding molds on which an oxidation-deteriorated layer of a release agent was formed, and vulcanized at 175 ° C. for 4 minutes. Then, immediately after the vulcanization, the mold was opened and the vulcanized rubber molded was taken out. In this case, the mold surface cleanability and the deterioration of the work environment due to the odor were investigated. In addition, using a mold after cleaning, a semiconductor element is transfer-molded under normal conditions into a semiconductor device, and the surface state of the sealing resin of the obtained device is visually observed, and the result is the above test results. In addition, the results are collectively shown in Tables 1 to 5 below.

[0045]

[Table 1]

[0046]

[Table 2]

[0047]

[Table 3]

[0048]

[Table 4]

[0049]

[Table 5]

As is clear from Tables 1 to 5 above, according to the examples, the vulcanized rubber taken out from the thermosetting resin molding die has the surface of the vulcanized rubber on which the release agent oxidative deterioration layer is formed. Transferred and adhered, whereby the cavity surface of the mold was sufficiently cleaned. In addition, no odor was generated during the cleaning work, and therefore the cleaning workability was not a problem at all. On the other hand, in the comparative example, there were problems in mold cleaning property or odor, and good results were not obtained. As a result, regarding the sealing resin of the semiconductor device obtained by using the above-mentioned mold, the surface of the resin had smoothness and gloss, while the comparative example, especially the comparative example 2
Nos. 4 to 4 were slightly uneven and were not glossy.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a conventional example.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koichi Takashima, 2307 Yoshida, Kanazaki-gun, Mitagawa-machi, Saga 2 2 Kyushu Nitto Denko Corporation (56) Reference JP-A-55-137914 (JP, A) 55-36960 (JP, A)

Claims (7)

(57) [Claims] 1. A sandwiching device between a pair of transfer molding dies.
Transfer molding die by heating and pressurizing
It is a cleaning sheet for cleaning the mold surface of
Semiconductor encapsulation characterized by being made of rubber material
Mold cleaning die cleaning sheet. 2. A claim in which a reinforcing agent is mixed with unvulcanized rubber fabric.
Item 1. A semiconductor sealing molding die cleaning cleaning sheet according to item 1.
G. 3. An unvulcanized rubber containing 100 parts of a reinforcing agent.
The semiconductor package according to claim 2, wherein the amount is 10 to 50 parts per part.
Mold cleaning mold cleaning sheet for stop. 4. The semiconductor encapsulation according to claim 1, wherein the unvulcanized rubber material comprises unvulcanized rubber and a removal aid.
Mold cleaning die cleaning sheet. 5. The removal aid, glycol ethers, imidazoles, and at least one compound selected from the group consisting of imidazolines claim 4 half according
Mold cleaning die cleaning sheet for conductor sealing. 6. An unvulcanized rubber 10 containing the removal aid in an amount of 10 parts.
It is 5 to 60 parts with respect to 0 parts.
Mold cleaning die cleaning sheet for semiconductor encapsulation. 7. The semiconductor according to any one of claims 1 to 6 , wherein the unvulcanized rubber material has a total content of chlorine ions and sodium ions suppressed to 2000 ppm or less.
Mold cleaning mold cleaning sheet for body sealing.