JP5824402B2 - Mask sheet for manufacturing semiconductor device and method for manufacturing semiconductor device using the same - Google Patents

Description

  The present invention relates to a semiconductor device manufacturing mask sheet used for masking a lead frame from a mold resin when a semiconductor device is manufactured by mounting (molding with resin) a semiconductor chip on a lead frame which is a metal plate. (Hereinafter referred to as a mask sheet), and a method of manufacturing a semiconductor device using a mask sheet that is laminated with a metal plate, the metal plate is formed into a predetermined pattern, a semiconductor chip is mounted, and then removed after molding. About.

  With the spread of portable personal computers and mobile phones, electronic devices are required to be further reduced in size, thickness and functionality. In order to realize this requirement, it is indispensable to reduce the size and increase the integration of electronic components, but further requires a high-density mounting technology for electronic components. The use of IC packages capable of high-density mounting of a surface mount type called CSP (Chip Size Package) instead of peripheral mount types such as conventional QFP (Quad Flat Package) and SOP (Small Outline Package) has expanded. ing. Among them, a package called QFN (Quad Flat Non-lead) can be manufactured by a conventional lead frame (hereinafter also referred to as L / F), wire bonding (hereinafter also referred to as W / B), molding technology and apparatus. It is mainly used for manufacturing a small terminal type package having 100 pins or less, and its application to a multi-pin package is expanding. This QFN is manufactured as follows. That is, a mask sheet is attached to one side of the lead frame, a semiconductor chip is mounted on the opposite side, and the lead and the chip are connected by a gold wire. Next, after molding, the mask sheet is peeled off and finally separated into pieces. In recent years, as its use has expanded, and in recent years, the use of gold wires coated with copper wires, palladium (Pd), and the like has begun, and various problems have been observed with conventionally applied mask sheets.

So far, examples of the mask sheet include those obtained by highly crosslinking a silicone adhesive as the resin layer, and those made of rubber and epoxy (see, for example, Patent Document 1). However, even if the pressure-sensitive adhesive is highly crosslinked, sufficient hardness cannot be obtained, it is easy to deform with respect to hot pressure, and it cannot be said that W / B performed at a high temperature is sufficiently performed.
In the case of an adhesive composed of rubber and epoxy, the rubber is relatively soft and the epoxy content needs to be increased in order to obtain hardness at high temperatures. As a result, the adhesiveness with the base material layer decreases, the cured product becomes hard, the ductility also decreases, and the adhesive remains on the mold resin and the frame surface when the mask sheet is peeled off. In particular, since the rubber material is thermally decomposed at a relatively low temperature, it may be decomposed during a process at a high temperature such as W / B to become outgas and contaminate the frame, which is not a preferable adhesive. A mask sheet using bismaleimide and acrylonitrile butadiene resin is disclosed as a mask sheet of a thermosetting adhesive using rubber (see, for example, Patent Document 2). Furthermore, it is said that the balemaleimide and acrylonitrile butadiene resin have improved releasability with silicone oil, but when exposed to high temperatures, the rubber component is hard due to thermal deterioration, the ductility decreases, and the resin tends to remain at the time of peeling (for example, , See Patent Document 3).

  From such a point, a mask sheet using a polyimide resin instead of rubber has been proposed. It is said that a mask sheet with little mold flash and excellent in W / B is realized by using a polyimide resin (see, for example, Patent Document 4). However, the application of a polyimide resin having a glass transition temperature (hereinafter referred to as Tg) of 180 ° C. or higher or a polyimide resin having an elastic modulus of about 100 MPa at 150 ° C. or higher has a very high pressure bonding temperature as described in the document. Since the elastic modulus is high, it is difficult to avoid warping of the mask sheet due to the resin layer being formed only on one side like the mask sheet made of a conventional thermoplastic resin. Furthermore, although it is said that components other than the polyimide resin can be appropriately blended, it is described that the adhesive layer contains 60% by mass or more of the polyimide resin, the pressure bonding temperature is high, and further, the peeling of the mask sheet after molding Is not mentioned at all.

Japanese Patent No. 4357754 JP 2009-158817 A Japanese Patent Laid-Open No. 2005-142401 JP 2003-188334 A

  Therefore, as a mask sheet, taping to L / F can be performed at a lower temperature than a thermoplastic mask sheet, and even when exposed to a high temperature, thermal deterioration that causes adhesive residue at the time of peeling of the mask sheet is difficult to occur, and flatness is improved. It has low warpage, is harder than conventional adhesive mask sheets at high temperatures, has excellent W / B properties, has less mold resin leakage at the time of sealing than adhesive mask sheets, is lightly peelable even after plasma cleaning, and has an adhesive. There is a need for a mask sheet with little remaining.

As a result of intensive studies aimed at solving the above problems, the present inventors have completed the following invention. That is, the mask sheet for manufacturing a semiconductor device of the present invention is a mask sheet for manufacturing a semiconductor device in which a thermosetting adhesive layer is laminated on one surface of a base material layer, and is releasably attached to a metal plate. The thermosetting adhesive layer comprises a polyimide resin containing a siloxane skeleton having a glass transition temperature of 45 to 170 ° C., an epoxy resin, a curing agent, and a fluorine-containing / lipophilic group-containing oligomer that is liquid at 25 ° C. contains fluorine additives, the content of the polyimide resin is at 35 to 75 mass%, at a content of the epoxy resin is 15 to 45 wt%, the content of the fluorine additive 0.5 to 5 phr (fluorine It is characterized in that the adhesive is 100 g excluding additives .
Further, in the melt viscosity curve of the thermosetting adhesive layer, it is preferable that the lower limit value is at a temperature of 70 to 200 ° C. and the viscosity of the lower limit value is 4000 Pa · s or more.
According to another aspect of the present invention, there is provided a method for manufacturing a semiconductor device comprising: laminating a thermosetting adhesive layer of the above-described mask sheet for manufacturing a semiconductor device on a metal plate, forming the metal plate into a predetermined pattern, After mounting and molding, the semiconductor device manufacturing mask sheet is removed.

Since the mask sheet of the present invention has the above-described configuration, the following effects can be obtained. Taping to L / F can be performed at a lower temperature than the thermoplastic mask sheet. Even when exposed to high temperatures, thermal degradation that causes adhesive residue when the mask sheet is peeled off is difficult to occur. Has flatness and small warpage. It is harder than conventional adhesive mask sheets at high temperatures and has excellent W / B properties. It is a mask sheet that has less mold resin leakage at the time of sealing than an adhesive mask sheet, is lightly peelable even after a plasma cleaning process, and has little adhesive residue.
Moreover, it becomes possible to manufacture a semiconductor device efficiently by using the mask sheet of this invention.

It is a figure which shows the melt viscosity curve of an adhesive bond layer. It is a schematic plan view which shows an example of a suitable lead frame used when manufacturing QFN using the mask sheet for semiconductor device manufacture of this invention. FIG. 3 is a cross-sectional view taken along the line A-A ′ of FIG. 2, illustrating an example of a manufacturing process of QFN.

The thermosetting adhesive layer (hereinafter, also simply referred to as an adhesive layer) in the mask sheet of the present invention is melted by heating before being cured, and can be crimped to a metal plate even at a high temperature such as thermoplastic. Moreover, after hardening by heat, even if heated, it does not melt, and a higher elastic modulus is obtained at a higher temperature than the pressure-sensitive adhesive.
The thermosetting adhesive layer is a layer containing a polyimide resin. A polyimide resin has rigidity and heat resistance while having flexibility, as represented by a polyimide film. In the present invention, the polyimide resin is an indispensable material because the thermosetting adhesive requires flexibility in a semi-cured state and a cured state, and adhesiveness with a heat-resistant substrate layer is necessary. is there.

Polyimide resin is a general term for polymers having an acid imide bond in the main chain, and can be synthesized by cyclization polycondensation of tetracarboxylic anhydride and diamine. Moreover, as a polyimide resin, a soluble or meltable thing is suitable.
The polyimide resin in the present invention is a polyimide resin having at least a structural unit represented by the formula (I), in which the structural unit represented by the formula (II) and the structural unit represented by the formula (III) are appropriately arranged. .

［式中、Ｗは、直接結合、炭素数１〜４のアルキレン基、−Ｏ−、−ＳＯ_２−または−ＣＯ−を表し、Ａｒ^１は下記式（１）または（２）で示される２価の芳香族基を表し

[Wherein W represents a direct bond, an alkylene group having 1 to 4 carbon atoms, —O—, —SO ₂ — or —CO—, and Ar ¹ represents ₂ represented by the following formula (1) or (2): Valent aromatic group

（式中、Ｘは、直接結合、炭素数１〜４のアルキレン基、−Ｏ−、−ＳＯ_２−または−ＣＯ−を表し、Ｙは、炭素数１〜４のアルキレン基を表し、Ｚ^１及びＺ^２は、それぞれ水素原子、ハロゲン原子、炭素数１〜４のアルキル基または炭素数１〜４のアルコキシ基を表す。）、Ａｒ^２は、１個または２個の水酸基またはカルボキシル基を有する２価の芳香族基を表し、Ｒ^１及びＲ^６は、炭素数１〜４のアルキレン基または式（３）で示される基を表し

(Wherein X represents a direct bond, an alkylene group having 1 to 4 carbon atoms, —O—, —SO ₂ — or —CO—, Y represents an alkylene group having 1 to 4 carbon atoms, and Z ¹ And Z ² each represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms), Ar ² has one or two hydroxyl groups or carboxyl groups. Represents a divalent aromatic group, R ¹ and R ⁶ represent an alkylene group having 1 to 4 carbon atoms or a group represented by formula (3).

（式中、Ａｌｋはケイ素原子に結合する炭素数１〜４のアルキレン基を表す。）、Ｒ^２〜Ｒ^５は炭素数１〜４のアルキル基を表し、ｎは０〜３１の整数である。］

(Wherein, Alk is an alkylene group having 1 to 4 carbon atoms bonded to a silicon ^atom.), R 2 ~R ⁵ represents an alkyl group having 1 to 4 carbon atoms, n represents is 0 to 31 integer . ]

  In general, polyimide resin is rigid, and in order to achieve the above-mentioned problem, flatness in the mask sheet before curing, taping at low temperature, it is necessary to adjust Tg and hardness, Adjustment is achieved by introducing a siloxane skeleton. If Tg is low, it is basically soft and effective for mask sheet flatness, but it tends to be insufficient in terms of heat resistance, particularly in terms of hardness. However, since it is a thermosetting type and heat resistance can be supplemented by a curing component, Tg may be 45 ° C. or higher. A high Tg is effective in terms of hardness at high temperatures, but is not preferable in terms of flatness of the mask sheet, and the taping temperature is also increased. However, the flatness and taping temperature can be lowered by the curing component, and if the temperature is 170 ° C. or lower, the above problem can be solved. That is, as Tg, a 45-170 degreeC polyimide resin is suitable. Tg is obtained by measuring the temperature at which endotherm occurs by differential thermal analysis and calculating the Tg from its peak or onset or offset temperature.

In order to adjust Tg and hardness, in addition to polysiloxane, a urethane skeleton, a diamine having a methylene chain, and the like are also possible. Compared to polysiloxane, heat resistance tends to be reduced, thermal decomposition is likely to occur, and molecular chains are likely to be broken in an active atmosphere such as plasma treatment. After plasma treatment, polar groups etc. are generated on the surface, and when sealed, there is a possibility of adhesion to the mold resin, the mask sheet peeling force may be increased, etc., and the decomposed gas contaminates the surroundings The possibility increases.
Siloxane is also effective in terms of peelability. However, although it is a siloxane site to be introduced to adjust the hardness, it is necessary to consider W / B, and as a resin, it is also necessary to have adhesion to the base material layer. The degree of polymerization of the siloxane moiety is limited, and the average degree of polymerization of the polysiloxane is 2 to 33 (molecular weight is about 250 to 3000), preferably the average degree of polymerization is 4 to 24 (molecular weight is about 400 to 2000). Is used.

  The molecular weight of the polyimide resin is preferably about 15000 to 70000 in consideration of meltability. The molecular weight can be measured by GPC using tetrahydrofuran (THF) as an eluent, and obtained as an average molecular weight in terms of styrene. When the number average molecular weight is less than 15,000, the toughness and ductility of the film are impaired and the film becomes brittle. On the other hand, when it is larger than 70000, the solvent solubility is lowered, the processability is inferior, the meltability as an adhesive is lowered, the taping temperature is increased, and it is difficult to put it into practical use.

By imparting reactivity with an epoxy group, an adhesive having higher heat resistance can be obtained, so that a reactive polyimide having a functional group is a tetracarboxylic dianhydride represented by the following formula (IV): A siloxane compound represented by the following formula (V), a diamine compound represented by the following formula (VI), and a diamine compound having an epoxy reactive group represented by the following formula (VII) are polycondensed in an organic solvent to obtain The obtained polyamic acid can be obtained by imidization by ring closure.
By having reactivity, W / B property and the like are improved. In particular, when W / B is carried out at a high temperature and with a large force, the pressure-sensitive adhesive may break the pressure-sensitive adhesive, but the adhesive layer in the present invention is hardly broken. Also, the mask sheet peelability is improved. This is because, when the molding is performed at a high temperature, each component of the adhesive is hardened to each other, so that there is an effect that the adhesion with the molding resin is not improved. As the functional group that reacts, a carboxyl group, a hydroxyl group, or the like is generally used.

  The ratio of the polyimide resin adhesive is preferably 35 to 75% by mass. When the amount of the polyimide resin is less than 35% by mass, there is a problem that the adhesiveness to the substrate is lowered and the resin remains when the mask sheet is peeled off, and 35% by mass or more is necessary from the viewpoint of flexibility. On the other hand, when it exceeds 75% by mass, the meltability of the adhesive is lowered, the temperature of application is increased, and the same problem as the thermoplastic resin mask sheet is likely to occur.

  The polyimide resin represented by the formula (I) used in the present invention will be described. Tetracarboxylic dianhydride represented by the following formula (IV), a siloxane compound represented by the following formula (V), a diamine compound represented by the following formula (VI), and an epoxy reaction represented by the following formula (VII) It can be obtained by polycondensing a diamine compound having a functional group in an organic solvent and imidating the resulting polyamic acid by ring closure.

（式中、Ｗ、Ａｒ^１、Ａｒ^２、Ｒ^１〜Ｒ^６、ｎは、前記した定義と同一のものを表す。）

(W, Ar ¹ , Ar ² , R ^{1 to} R ⁶ , and n represent the same definitions as described above.)

  Examples of the tetracarboxylic dianhydride represented by the formula (IV) include 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, 3,4,3 ′, 4′-biphenyltetracarboxylic Acid dianhydride, 2,3,2 ′, 3′-biphenyltetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) ether Anhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 3,4,3 ′, 4′-benzophenonetetracarboxylic Examples thereof include acid dianhydride, 4 ′, 4′-biphthalic acid dianhydride, and the like.

  Examples of the siloxane compound having amino groups at both ends represented by the formula (V) include 1,3-bis (3-aminopropyl) -1,1,3,3-tetramethyldisiloxane, α, ω-bis. (3-aminopropyl) polydimethylsiloxane (for example, tetramer to octamer of dimethylsiloxane having an aminopropyl terminal), 1,3-bis (3-aminophenoxymethyl) -1,1,3,3- Tetramethyldisiloxane, α, ω-bis (3-aminophenoxymethyl) polydimethylsiloxane, 1,3-bis (2- (3-aminophenoxy) ethyl) -1,1,3,3-tetramethyldisiloxane , Α, ω-bis (2- (3-aminophenoxy) ethyl) polydimethylsiloxane, 1,3-bis (3- (3-aminophenoxy) propyl) -1,1,3,3- Tetramethyl disiloxane, alpha, .omega.-bis (3- (3-aminophenoxy) propyl) polydimethyl siloxane, and the like. In the above siloxane compounds, in the case of polysiloxane, those having an average polymerization degree of 2 to 33 (molecular weight of about 250 to 3000), preferably an average polymerization degree of 4 to 24 (molecular weight of about 400 to 2000) are used. Is done.

  Examples of the diamine compound represented by the formula (VI) include 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminodiphenyl ether, and 3,3'-diamino. Diphenyl ether, 4,4′-diaminobenzophenone, 3,3′-dimethyl-4,4′-diaminobenzophenone, 3,3′-diaminodiphenylmethane, 3,3′-dimethoxy-4,4′-diaminodiphenylmethane, 2, 2′-bis (3-aminophenyl) propane, 4,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, benzidine, 3,3′-dimethylbenzidine, 3,3′-dimethoxybenzidine, 3, 3′-diaminobiphenyl, 1,3-bis (3-aminophenoxy) Zen, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [3-methyl-4- (4-aminophenoxy) phenyl] propane, 2,2-bis [3- Chloro-4- (4-aminophenoxy) phenyl] propane, 2,2-bis [3,5-dimethyl-4- (4-aminophenoxy) phenyl] propane, 1,1′-bis [4- (4- Aminophenoxy) phenyl] ethane, 1,1′-bis [3-chloro-4- (4-aminophenoxy) phenyl] ethane, bis [4- (4-aminophenoxy) phenyl] methane, bis [3-methyl- 4- (4-aminophenoxy) phenyl] methane, 4,4 ′-[1,4-phenylenebis (1-methylethylidene)] bisaniline, 4,4 ′-[1,3-phenylenebis (1-methyl) Ruechiriden)] bisaniline, 4,4 '- [1,4-phenylene bis (1-methylethylidene)] bis (2,6-dimethyl-bis aniline) and the like. Two or more of these diamine compounds may be used in combination.

  Examples of the diamine compound having an epoxy reactive group represented by the formula (VII) include 2,5-dihydroxy-p-phenylenediamine, 3,3′-dihydroxy-4,4′-diaminodiphenyl ether, 4,3. '-Dihydroxy-3,4'-diaminodiphenyl ether, 3,3'-dihydroxy-4,4'-diaminobenzophenone, 3,3'-dihydroxy-4,4'-diaminodiphenylmethane, 3,3'-dihydroxy-4 , 4′-diaminodiphenylsulfone, 4,4′-dihydroxy-3,3′-diaminodiphenylsulfone, 2,2′-bis [3-hydroxy-4- (4-aminophenoxy) phenyl] propane, bis [3 -Hydroxy-4- (4-aminophenoxy) phenyl] methane, 3,3′-dicarboxy-4 4'-diaminodiphenyl ether, 4,3'-dicarboxy-3,4'-diaminodiphenyl ether, 3,3'-dicarboxy-4,4'-diaminobenzophenone, 3,3'-dicarboxy-4,4 ' -Diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylsulfone, 4,4'-dicarboxy-3,3'-diaminodiphenylsulfone, 3,3'-dicarboxybenzidine, 2,2 Examples include '-bis [3-carboxy-4- (4-aminophenoxy) phenyl] propane, bis [3-carboxy-4- (4-aminophenoxy) phenyl] methane, and the like. Two or more of these diamine compounds may be used in combination.

  In order to obtain the polyimide resin in the present invention, the above tetracarboxylic dianhydride, a siloxane compound having an amino group at both ends, and a diamine compound are -20 to 150 ° C. in the presence of a solvent, preferably 0 to It can be produced by reacting at a temperature of 60 ° C. for several tens of minutes to several days to produce a polyamic acid and further imidization. Examples of the solvent include amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, and N-methyl-2-pyrrolidone, and sulfur such as dimethylsulfoxide and dimethylsulfone. Examples of the solvent include phenol solvents such as phenol, cresol, and xylenol, acetone, tetrahydrofuran, pyridine, and tetramethylurea.

  As the imidization method, there are a method of dehydrating and ring-closing by heating and a method of chemically ring-closing using a dehydrating and ring-closing catalyst. When dehydrating and ring-closing by heating, the reaction temperature is 150 to 400 ° C., preferably 180 to 350 ° C., and the reaction time is several tens of minutes to several days, preferably 2 to 12 hours. Examples of the dehydration ring closure catalyst in the case of chemical ring closure include acid anhydrides such as acetic acid, propionic acid, butyric acid, and benzoic acid, and it is preferable to use pyridine or the like that promotes the ring closure reaction. The amount of the catalyst used is 200 mol% or more, preferably 300 to 1000 mol% of the total amount of diamine.

  In the polyimide resin used in the present invention, the structural unit represented by the above formula (I) and the structural unit represented by the above formula (II) and formula (III) are arranged in a molar ratio of 5/95 to 50/50. It is preferable. The ratio of the structural unit represented by the formula (II) to the structural unit represented by the formula (III) is 0: 100 to 99: 1, preferably 80:20 to 95: 5, more preferably in molar ratio. It is in the range of 50:50 to 95: 5.

In order to impart flatness, as described above, it is necessary to modify with silicone. However, with only a polyimide resin, it becomes soft upon heating, and W / B properties and the like are reduced. Further, in the case of a relatively rigid polyimide resin that suppresses the amount of modification by silicone, flatness cannot be obtained, and there is a problem that the temperature during pressure bonding becomes too high. In order to complement these, the former problem can be prevented from being softened at high temperature by using an epoxy resin together, and the latter problem is softened and melted at a lower temperature than polyimide resin. By using an epoxy resin in combination, the temperature for pressure bonding can be lowered as an adhesive, which can be put to practical use.
Epoxy resin has two or more epoxy groups in one molecule, cresol novolac type epoxy resin, phenol novolac type epoxy resin, epoxy resin containing biphenyl type skeleton, naphthalene skeleton epoxy resin, triphenylmethane type Epoxy, bisphenol A type, F type epoxy resin, dicyclopentadiene type epoxy resin, linear aliphatic epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin, and halogenated epoxy resin.

Among the epoxy resins, the polyfunctional epoxy resin is suitable for improving the Tg of the adhesive layer and the hardness at high temperature. On the other hand, since the polyfunctional epoxy resin tends to have a high softening point, a double-ended epoxy resin is more suitable for improving the meltability of the adhesive layer.
Both-end epoxy resins are less than the polyfunctional type in terms of the Tg of the adhesive layer and the hardness at high temperature, but are relatively low in rigidity, so that they are preferable materials for the warp of the mask sheet. It is more preferable to contain a type epoxy resin and a both-end epoxy resin.
In addition, the linear epoxy resin is not a polyfunctional type in terms of the Tg of the adhesive layer and the hardness at high temperature, but is a preferable material for the warpage of the mask sheet as a result of its relatively low rigidity. Further, it may be further contained in the polyfunctional epoxy resin and the both-end epoxy resin.

Specific examples of the polyfunctional epoxy resin, triphenylmethane type epoxy resin (e.g., manufactured by Nippon Kayaku Co., Ltd. trade name: EPPN502H), Na Futaren type epoxy resin (e.g., DIC Corp. trade name: HP4700 ), Cresol novolac type epoxy resin (trade name: EOCN1022 manufactured by Nippon Kayaku Co., Ltd.), multifunctional type epoxy resin manufactured by Printec Co., Ltd., product name: VG3101, and the like.
Further, as both-end epoxy resins, bisphenol A type epoxy resins (for example, Epicoat 828 manufactured by JER), biphenyl type epoxy resins (for example, product name: YX-4000 manufactured by JER), naphthalene type epoxy (HP4032D manufactured by DIC) Dicyclopentadiene type epoxy resin (for example, product name: HP7200, manufactured by DIC), and epoxy resin having a siloxane skeleton in terms of imparting flexibility (for example, product names: KF105, X-22-163, manufactured by Shin-Etsu Chemical Co., Ltd.) ), Manufactured by DIC, Inc. Trade names: EXA4816, EXA4822, both end epoxy of butanediol skeleton, and the like .

  The above epoxy resin having a siloxane skeleton is more preferable for the warpage of the mask sheet. As for the siloxane skeleton, there may be a siloxane moiety also in the skeleton of the polyimide resin, but it has a stress relaxation effect on curing shrinkage and the like when a relatively low molecular weight epoxy resin is thermally cured. Since the multifunctional type and the both-end epoxy resin have contradictory characteristics, a more preferable resin composition can be obtained by using a siloxane-modified polyimide resin that is an elastomer, a multifunctional epoxy resin, and a both-end epoxy resin in combination. When the content is small, it is difficult to lower the softening temperature of the adhesive. When the content is large, the flexibility of the adhesive is lowered, the adhesiveness with the heat-resistant substrate is lowered, and it becomes brittle. The remaining adhesive when the mask sheet is peeled off is likely to be a problem. The optimum content varies depending on the molecular weight, functional group, etc. of the curing agent, and the content of the epoxy resin is preferably 15 to 45 mass%, more preferably 20 to 40 mass%.

  The adhesive layer contains a curing agent that crosslinks with an epoxy group. By containing a curing agent that undergoes a curing reaction with an epoxy resin, the hardness and heat resistance after curing are improved, and it is also suitable for W / B properties. Further, by curing, contact with the mold resin without melting at the time of mold sealing does not significantly increase the adhesiveness of the interface, and it is possible to suppress the mask sheet peeling force and prevent the adhesive from remaining. Examples of curing agents include 3,3 ′, 5,5′-tetramethyl-4,4′-diaminodiphenylmethane, 3,3 ′, 5,5′-tetraethyl-4,4′-diaminodiphenylmethane, 3 , 3'-dimethyl-5,5'-diethyl-4,4'-diaminodiphenylmethane, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 2,2 ', 3,3'-tetrachloro-4 , 4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfide, 3,3'-diaminobenzophenone, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone Aromatic polyamines such as 4,4′-diaminobenzophenone and 3,4,4′-triaminodiphenylsulfone, boron trifluoride Amine complexes of boron trifluoride such as ethylamine complex, dicyandiamide, p-t-butylphenol, bisphenol A skeleton, paraphenylene skeleton, novolak phenolic resins such as biphenyl skeleton, bisphenol compounds such as bisphenol A can be used. Self-crosslinking type resole resins having the skeleton can also be used. Of these, phenolic curing agents are preferred because of their excellent heat resistance. In addition, these are preferably used alone or in combination of two or more in terms of control of meltability. Further, imidazoles, diamines, triphenylphosphine accelerators and catalysts may be used for the purpose of controlling the curing rate.

The adhesive layer contains a fluorine additive for imparting peelability. The fluorine additive is a copolymer or graft containing at least one of a perfluoro group-containing olefin, vinyl ether or vinyl ester as a constituent material. As the fluorine-containing graft polymer, trade name: Chemitry LF-700 manufactured by Soken Chemical Co., Ltd., which is a fluorine-containing acrylic graft polymer, can be exemplified. The fluorine-containing acrylic graft polymer is composed of a trunk polymer and a plurality of branch polymers extending from the trunk polymer, the trunk polymer is composed of an acrylic polymer, and the branch polymer is composed of a polymer containing fluorine.
As the fluorine-containing block copolymer, a block copolymer comprising a fluorinated alkyl group-containing polymer segment and an acrylic polymer segment is a product name manufactured by NOF Corporation: Modiper F series, for example, Modiper F200, Modiper F220, Modiper F2020, Modiper. F3035 and Modiper F600 are commercially available. Moreover, as a fluorine-containing aliphatic polymer ester, what has the characteristic as a nonionic surfactant is preferable, and the brand name: Novec FC-4430 etc. by 3M Corporation can be mentioned. Examples of fluorine additives include anionic surfactants such as sulfonates containing perfluoroalkyl groups and carboxylates containing perfluoroalkyl groups, perfluoroalkylalkylene oxide adducts, fluorine-containing groups and lipophilic groups. Fluorine-containing surfactants such as nonionic surfactants such as group-containing oligomers, fluorine-containing groups / hydrophilic group-containing oligomers, fluorine-containing groups / hydrophilic groups / lipophilic group-containing oligomers, and the like. These fluorine additives may be used singly or in combination of two or more. The fluorine additive to be blended may be a liquid or a solid, but is a liquid at 25 ° C. from the viewpoint of increasing the surface fluorine restoration rate of the adhesive layer and further improving the peelability. Is preferred. Suitable fluorine additives include, for example, Megafac F-552, F-554, F-558, and F-477 (manufactured by DIC Corporation), which are liquid fluorine-containing / lipophilic group-containing oligomers at 25 ° C. It is done.

The presence of the fluorine additive can suppress the adhesiveness with the mold resin or the metal plate, and particularly the problem of the resin residue is improved. On the other hand, the fluorine additive is effective in providing releasability, but it may also reduce the adhesion to the substrate. If the addition amount is too large, the adhesion will be too low, and a metal plate such as a frame will be used. As a result, problems such as resin leakage occur and it is not practically used. As a result of intensive studies, 0.5 to 5 phr (excluding fluorine additive, based on 100 g of adhesive) is desirable.
The effect on releasability by the fluorine additive is considered as follows. First, in the QFN process, a mask sheet is attached to one side of a lead frame, and a semiconductor chip is mounted on the opposite side by a die attach adhesive. However, outgas is generated from the die attach agent when the adhesive is cured, Since outgas is also generated from the mask sheet, cleaning is performed with plasma in order to improve the reliability of bonding by wire bonding in which the lead and the chip are connected by the gold wire.
Plasma cleaning breaks the molecular chains on the surface of the adhesive, creating polar groups and roughening the surface, resulting in improved adhesion to the mold resin in mold sealing after wire bonding. The peeling force at the time of peeling off the mask sheet of the mask sheet increases, and the problem that the adhesive remains in the part of the mold resin is likely to occur. However, as in the present invention, by containing a fluorine additive, after being plasmatized, fluorine and fluorine-containing molecules are aligned or appear on the surface layer on the adhesive surface of the mask sheet due to the thermal history during wire bonding. Therefore, the above-described problem after sealing is solved. Considering the orientation of fluorine on the surface, etc., the Tg of the adhesive layer in the mask sheet is preferably 90 to 200 ° C. If the Tg after curing is lower than 90 ° C., there is a problem in wire bonding properties. If the Tg after curing exceeds 200 ° C., the fluorine additive is applied to the surface by heat treatment in the temperature history of wire bonding after plasma. Since it becomes difficult to come out, the peelability deteriorates, and as a result, problems such as resin residue are likely to occur.

Tg in the present invention is determined from the temperature dependence of the dynamic viscoelasticity of the adhesive layer, and is determined by the peak temperature of the loss coefficient or the displacement point.
Sample size is 1 cm or more in length, 1 to 4 mm in width, 5 to 40 μm in thickness, using a dynamic viscoelasticity automatic measuring instrument DDV-01FP manufactured by Orientec Co., Ltd. with a frequency of 11 Hz, a heating rate of 10 ° C./min, and a load of 3 g. And measure in air. The adhesive layer is peeled off from the base material layer, and only the adhesive layer is subjected to a curing treatment at 175 ° C. for 1 hour, and the above measurement is performed. In the case where only the adhesive layer cannot be collected, the measurement may be performed by the configuration of the base material layer and the adhesive layer. When measured with the configuration of the base material layer and the adhesive layer, the temperature characteristic of the loss coefficient may not be detected as a peak, but in that case, determine the loss behavior of the adhesive layer from the characteristics of the base material layer, Tg is determined.

Filler should be included in the adhesive layer for the purpose of changing the meltability in the B stage (semi-cured state), the hardness of the cured product, or adjusting the thermal expansion coefficient, thermal conductivity, surface tack, adhesiveness, etc. I can do it. As the filler, an insulating filler is more preferable. In general, it is preferable to add an inorganic or organic filler.
Here, as the inorganic filler, pulverized silica, fused silica, alumina, titanium oxide, beryllium oxide, magnesium oxide, calcium carbonate, titanium nitride, silicon nitride, boron nitride, titanium boride, tungsten boride, silicon carbide, carbonized carbon Filler made of titanium, zirconium carbide, molybdenum carbide, mica, zinc oxide, carbon black, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, antimony trioxide, etc., or those having a trimethylsiloxyl group introduced on their surface Etc. can be illustrated. Examples of the organic filler include fillers made of polyimide, polyamideimide, polyetheretherketone, polyetherimide, polyesterimide, nylon, silicone, and the like. In the case of a mask sheet, since the adhesive layer is as thin as about 5 μm, the size of the filler that can be used is limited, and the average particle size is preferably 1 μm or less as D (50). Furthermore, 0.2 μm or less is suitable.

  The meltability of the adhesive layer is important in the following points. After the mask sheet is applied, heat treatment for curing the die attach agent is performed when the chip is mounted. Generally, the temperature is raised from room temperature to about 175 ° C. in about 1 hour, and heat treatment is performed at around 175 ° C. for about 1 hour. Further, the die attach agent may be cured by passing through a heating furnace at 200 ° C. in about several minutes. The thermosetting adhesive layer generally has a tendency to decrease in viscosity once, and may foam due to volatilization of moisture absorption, entrainment of bubbles when a mask sheet is attached, or the like. Further, when the curing rate is low, the mask sheet adhesive is not sufficiently cured when the die attach agent is cured. From such a viewpoint, as the melt viscosity of the B stage, the temperature at which the lower limit of the viscosity appears is 70 to 200 ° C., preferably 90 to 180 ° C., and the viscosity of the lower limit is 4000 Pa · s or more. It is preferably 80000 Pa · s or more. That is, as shown in FIG. 1, in the melt viscosity curve of the adhesive layer, it is preferable that the lower limit A has a temperature of 70 to 200 ° C. and the viscosity is 4000 Pa · s or more. In order to obtain such a melt viscosity, the polyimide resin, epoxy resin, and curing agent composition described above is preferably used, and the curing rate is adjusted with an accelerator and a catalyst, and the adhesive is used for a long time at a predetermined temperature. An appropriate melt viscosity can be obtained by controlling the reaction state by heat treatment (aging). The melt viscosity is measured by using a rheometer RS manufactured by Eiko Seiki Co., Ltd., at a frequency of 1 Hz and a heating rate of 10 ° C./min.

  The thickness of the adhesive layer is 1 to 30 μm, preferably 3 to 7 μm. If the thickness of the adhesive layer is less than 1 μm, it is easy for mold resin to leak when foreign matter or the like is mixed in. If the thickness of the adhesive layer is too thick, the wire bonding property is deteriorated, and sealing is performed. There is a possibility that the lead frame is buried in the adhesive. Furthermore, since the adhesive layer affects the thermal expansion as a mask sheet, the thickness is preferably about 3 to 7 μm.

Examples of the base material layer include polyester film, polyethylene naphthalate film, polyether sulfone, polyetherimide film, polyphenylene sulfide film, PAR film, aramid film, polyimide film, and liquid crystal polymer film. Moreover, it is not limited to a film, A paper, the metal foil of copper foil, etc. can be used. Non-woven fabrics such as polyparaphenylene benzobisoxazole (PBO) and aramid are also applicable.
Although 10-125 micrometers can be used for the thickness of a base material layer, it is 15-25 micrometers generally. Further, if there is a difference in thermal expansion from the metal plate, problems such as warpage occur in a state where the mask sheet is stretched on the metal plate, so that the thermal expansion of the base material layer is preferably about 13 to 25 ppm.

In the mask sheet of the present invention, if there is a foreign substance on the surface or inside of the adhesive layer, a problem such as mold resin leakage occurs. Therefore, a protective film is attached as necessary.
As the protective film, a synthetic resin film such as paper, polyethylene, polypropylene, or polyethylene terephthalate that has been subjected to a release treatment is used. In the case where the base material layer is a peelable film or paper having a release treatment applied to the surface, the base material layer may be peeled off before use and only the adhesive layer may be used as a mask sheet.

  Next, an example of a method for manufacturing a semiconductor device using the above-described mask sheet of the present invention will be briefly described with reference to FIGS. Hereinafter, a case where QFN is manufactured as a semiconductor device will be described as an example. 2 is a schematic plan view when the lead frame is viewed from the side on which the semiconductor element is mounted. FIGS. 3A to 3F show a method of manufacturing QFN from the lead frame shown in FIG. FIG. 3 is a process diagram, and is an enlarged schematic cross-sectional view when the lead frame is cut along the line AA ′ in FIG. 2.

  First, a lead frame 20 having a schematic configuration shown in FIG. 2 in plan view is prepared. The lead frame 20 includes a plurality of island-shaped semiconductor element mounting portions (die pad portions) 21 on which semiconductor elements such as IC chips are mounted, and a large number of leads 22 are arranged along the outer periphery of each semiconductor element mounting portion 21. It has been done. Next, as shown in FIG. 3A, in the mask sheet attaching step, the mask sheet 10 of the present invention is placed on one surface of the lead frame 20 with the adhesive layer (not shown) side on the lead frame 20 side. Adhere to be. As a method for attaching the mask sheet 10 to the lead frame 20, a laminating method or the like is suitable. Next, as shown in FIG. 3B, in the die attach step, the semiconductor element 30 such as an IC chip is attached to the semiconductor element mounting portion 21 of the lead frame 20 from the side where the mask sheet 10 is not adhered. It is mounted using a touch agent (not shown).

  Next, as shown in FIG. 3C, in the wire bonding step, the semiconductor element 30 and the leads 22 of the lead frame 20 are electrically connected via bonding wires 31 such as gold wires. Next, as shown in FIG. 3 (d), in the resin sealing step, the semiconductor device being manufactured shown in FIG. 3 (c) is placed in a mold and transferred using a mold resin (molding agent). The semiconductor element 30 is sealed with the mold resin 40 by molding (molding). Next, as shown in FIG. 3E, in the mask sheet peeling step, the QFN unit 60 in which a plurality of QFNs 50 are arranged is formed by peeling the mask sheet 10 from the mold resin 40 and the lead frame 20. Can do. Finally, as shown in FIG. 3F, a plurality of QFNs 50 can be manufactured by dicing the QFN unit 60 along the outer periphery of each QFN 50 in the dicing step.

The mask sheet of the present invention can also be applied as a mask sheet for a semiconductor device by the following process.
The adhesive layer surface of the mask sheet of the present invention is laminated on a metal plate. An example of the metal plate is a thin film metal foil such as copper. Thereafter, the adhesive layer is cured by heat. Next, a thin film metal foil is formed into a predetermined pattern by etching or the like. After the thin metal foil is formed in a pattern, the semiconductor device is manufactured by removing the mask sheet through die attach, wire bonding, and molding processes as described above.
In the case of a mask sheet using an adhesive containing a conventional rubber and an epoxy resin, the adhesive can be swelled with acid or alkali caused by an etching solution used in the etching process. Adsorption of impurity ions by the chemical solution in the inside, impurities contained in the adhesive come into contact with the mold resin, and problems such as migration to the mold resin portion, and adhesive and metal foil at the edge of the pattern due to the chemical solution The chemical liquid permeates into the surface of the film, resulting in problems such as mold flash. Moreover, if it is a mask sheet | seat by an adhesive, it cannot endure etching liquid.
In this respect, the mask sheet of the present invention has almost no adsorption of impurity ions, no penetration of chemicals into the interface between the adhesive and the metal foil at the edge of the metal foil pattern, and mold flash is also generated. Hard to do. Further, the semiconductor device by such a process is applied to thinning and the like, and the metal foil can be thinned.

Examples and comparative examples according to the present invention will be described below.
Specifically, a polyimide resin was first prepared as follows.

(Synthesis Example 1) (No epoxy reactivity)
In a flask equipped with a stirrer, 10.3 g (52 mmol) of 3,4'-diaminodiphenyl ether, 1,3-bis (3-aminophenoxymethyl) -1,1,3,3-tetramethyldisiloxane; 2 g (48 mmol), 3,4,3 ′, 4′-benzophenonetetracarboxylic dianhydride 32.2 g (100 mmol) and N-methyl-2-pyrrolidone (NMP) 300 ml were introduced under ice temperature. Stirring was continued for hours. Next, the resulting solution was reacted at room temperature for 3 hours under a nitrogen atmosphere to synthesize polyamic acid. To the obtained polyamic acid solution, 50 ml of toluene and 1.0 g of p-toluenesulfonic acid were added and heated to 160 ° C. An imidization reaction was performed for 3 hours while separating water azeotroped with toluene. Toluene was distilled off, and the resulting polyimide varnish was poured into methanol, and the resulting precipitate was separated, pulverized, washed, and dried to obtain 54.3 g of polyimide resin (yield 95%). It was. When an infrared absorption spectrum of this polyimide resin was measured, typical imide absorption was observed at 1718 and 1783 cm. Moreover, about this polyimide resin, the number average molecular weight and the glass transition temperature were measured. The results are shown in Table 1.

(Synthesis Example 2) (with epoxy reactivity)
1,2-bis [4- (4-aminophenoxy) phenyl] propane 17.8 g (43 mmol), 3,3′-dicarboxy-4,4′-diaminodiphenylmethane 2.3 g (9 mmol), 1, 18.3 g (48 mmol) of 3-bis (3-aminophenoxymethyl) -1,1,3,3-tetramethyldisiloxane, 3,4,3 ′, 4′-benzophenonetetracarboxylic dianhydride32. Reactive polyimide resin 62.5 g (yield 93%) was obtained in the same manner as in Synthesis Example 1 using 22 g (100 mmol) and N-methyl-2-pyrrolidone (NMP) 300 ml. The number average molecular weight and glass transition temperature of this polyimide resin were measured. The results are shown in Table 1.

(Synthesis Example 3) (No epoxy reactivity)
2,2-bis [4- (4-aminophenoxy) phenyl] propane 33.7 g (82 mmol), aminopropyl-terminated dimethylsiloxane octamer 13.8 g (18 mmol), 2,3,3 ′, 4 ′ Using 69.4 g (100 mmol) of biphenyltetracarboxylic dianhydride and 300 ml of N-methyl-2-pyrrolidone, 67.4 g of polyimide resin (92% yield) was obtained in the same manner as in Synthesis Example 1. . The number average molecular weight and glass transition temperature of this polyimide resin were measured. The results are shown in Table 1.

(Synthesis Example 4) (with epoxy reactivity)
2,4-bis [4- (4-aminophenoxy) phenyl] propane 30.4 g (74 mmol), 3,3′-dicarboxy-4,4′-diaminodiphenylmethane 2.35 g (8 mmol), aminopropyl Using 13.6 g (18 mmol) of terminal dimethylsiloxane octamer, 29.4 g (100 mmol) of 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride and 300 ml of N-methyl-2-pyrrolidone In the same manner as in Synthesis Example 1, 67.8 g of reactive polyimide resin (yield 94%) was obtained. The number average molecular weight and glass transition temperature of this polyimide resin were measured. The results are shown in Table 1.

(Synthesis Example 5) (No epoxy reactivity)
2,2-bis [4- (4-aminophenoxy) phenyl] propane 32.0 g (78 mmol), aminopropyl-terminated dimethylsiloxane octamer 17.0 g (22 mmol), bis (3,4-dicarboxyphenyl) ) 78.7 g (97% yield) of polyimide resin was obtained in the same manner as in Synthesis Example 1 using 35.8 g (100 mmol) of sulfone dianhydride and 300 ml of N-methyl-2-pyrrolidone. The number average molecular weight and glass transition temperature of this polyimide resin were measured. The results are shown in Table 1.

(Synthesis Example 6) (with epoxy reactivity)
3,0.4 g (74 mmol) of 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 1.1 g (4 mmol) of 3,3′-dicarboxy-4,4′-diaminodiphenylmethane, aminopropyl Synthesis example using 16.9 g (22 mmol) of terminal dimethylsiloxane octamer, 35.83 g (100 mmol) of bis (3,4-dicarboxyphenyl) sulfone dianhydride and 300 ml of N-methyl-2-pyrrolidone In the same manner as in Example 1, 75.0 g (93% yield) of a reactive polyimide resin was obtained. The number average molecular weight and glass transition temperature of this polyimide resin were measured. The results are shown in Table 1.

(Synthesis Example 7) (No epoxy reactivity)
1,3-bis (3-aminophenoxy) benzene 26.1 g (89 mmol), aminopropyl-terminated dimethylsiloxane octamer 8.1 g (11 mmol), bis (3,4-dicarboxyphenyl) ether dianhydride Using 20.0 g (100 mmol) and 300 ml of N-methyl-2-pyrrolidone, 47.1 g of polyimide resin (yield 93%) was obtained in the same manner as in Synthesis Example 1. The number average molecular weight and glass transition temperature of this polyimide resin were measured. The results are shown in Table 1.

(Synthesis Example 8) (with epoxy reactivity)
1,3-bis (3-aminophenoxy) benzene 23.6 g (81 mmol), 3,3′-dihydroxy-4,4′-diaminodiphenylmethane 2.1 g (9 mmol), aminopropyl-terminated dimethylsiloxane octamer In the same manner as in Synthesis Example 1, 8.1 g (10 mmol), 20.0 g (100 mmol) of bis (3,4-dicarboxyphenyl) ether dianhydride and 300 ml of N-methyl-2-pyrrolidone were used. 45.6 g (yield 91%) of polyimide resin was obtained. The number average molecular weight and glass transition temperature of this polyimide resin were measured. The results are shown in Table 1.

(Synthesis Example 9) (No epoxy reactivity)
28.7 g (70 mmol) of 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 23.1 g (30 mmol) of aminopropyl-terminated dimethylsiloxane octamer, bis (3,4-dicarboxyphenyl) ) 78.7 g (97% yield) of polyimide resin was obtained in the same manner as in Synthesis Example 1 using 35.8 g (100 mmol) of sulfone dianhydride and 300 ml of N-methyl-2-pyrrolidone. The number average molecular weight and glass transition temperature of this polyimide resin were measured. The results are shown in Table 1.

(Synthesis Example 10) (No epoxy reactivity, no siloxane skeleton)
4,4′-methylenebis (2,6-diethylaniline 3.2 g (10 mmol), 1,3-bis (3-aminophenoxy) benzene 11.7 g (40 mmol), 4,4′-oxydiphthalic anhydride Using 15.5 g (50 mmol) and N-methyl-2-pyrrolidone 300 ml, polyimide resin 78.7 g (yield 97%) was obtained in the same manner as in Synthesis Example 1. About this polyimide resin, its number The average molecular weight and glass transition temperature were measured and the results are shown in Table 1.

[Examples 1 and 12, Comparative Examples 13 to 16 and Comparative Examples 1 to 4]
Next, polyimide resins, epoxy resins, curing agents, fluorine additives, and accelerators were mixed in methyl ethyl ketone based on the formulations shown in Tables 2 and 3 below, and Examples 1 to 12 and Comparative Examples 13 to 16 were mixed. And the adhesive agent of Comparative Examples 1-4 was prepared. They are dried on a base material layer made of polyimide resin film (trade name: Kapton 100EN, thickness 25 μm, glass transition temperature 300 ° C., thermal expansion coefficient 16 ppm / ° C., manufactured by Toray DuPont), and the thickness after drying becomes 5 μm. Thus, it applied and dried at 100 degreeC for 5 minute (s), and produced the mask sheet | seat which comprises the adhesive bond layer of this invention, and the mask sheet for a comparison.
In addition, the numerical value in Table 2 and Table 3 shows the compounding ratio of the mass in a polyimide resin, an epoxy resin, a hardening | curing agent, a fluorine additive, and an accelerator.

[Comparative Examples 5 to 8]
For Comparative Examples 5, 6, 7 and 8, after producing an adhesive or pressure-sensitive adhesive as follows, a comparative mask sheet was produced in the same manner as in Example 1.
[Comparative Example 5]
The following compounds were mixed and stirred until dissolved to prepare an adhesive.
・ Acrylic nitrile butadiene rubber 100 parts by mass (Zeon Corporation, trade name: Nipol 1072)
・ 50 parts by mass of orthocresol novolac epoxy resin (manufactured by Nippon Kayaku Co., Ltd., trade name: EOCN1020)
-50 parts by weight of novolac phenolic resin (made by Showa Polymer Co., Ltd., trade name: CKM 2432)
・ 0.5 parts by mass of 2-ethyl-4-methylimidazole ・ 800 parts by mass of methyl ethyl ketone

[Comparative Example 6]
A solution containing a polyalkylalkenylsiloxane having an average molecular weight of 500,000 and a platinum catalyst (TSR-1512, solid concentration 60 mass%, manufactured by GE Toshiba Silicone) and a polyalkylhydrogensiloxane (CR-51, average molecular weight 1300) GE Toshiba Silicone Co., Ltd.) was mixed at a mass ratio of 100: 1 to prepare an addition reaction type silicone pressure-sensitive adhesive.

[Comparative Example 7]
An adhesive was prepared by dissolving only the polyimide resin shown in Synthesis Example 1 in a tetrahydrofuran solution so that the solid content was 25% by mass.

[Comparative Example 8]
The following compounds were mixed and stirred until dissolved to prepare an adhesive.
-Silicone main chain epoxy resin 50 parts by mass (trade name: X-22-163, molecular weight of about 400, manufactured by Shin-Etsu Chemical Co., Ltd.)
・ 25 parts by mass of novolac phenolic resin (made by Showa Polymer Co., Ltd., trade name: CKM 2432)
・ 2 parts by mass of fluorine-based leveling agent (trade name: Mega-Fac F-482, manufactured by DIC)
-0.1 part by mass of 2-ethyl-4-methylimidazole-800 parts by mass of methyl ethyl ketone

<Physical properties>
For the mask sheets of Examples 1 to 12, Comparative Examples 13 to 16, and Comparative Examples 1 to 8, the glass transition temperature (Tg), melt viscosity, and viscosity lower limit temperature of the adhesive layer were measured, and the results are shown in Table 4. And in Table 5.

<Evaluation results>
Further, the following characteristics were measured for the mask sheets of Examples 1 to 12, Comparative Examples 13 to 16 and Comparative Examples 1 to 8, and the results are shown in Tables 4 and 5.
In addition, "-" in the evaluation result of Table 5 shows that the measurement was stopped because the evaluation result of any of the following flatness warpage, sticking property, or foam test was bad.
1. Flatness warp In the absence of a protective film, cut to 20 cm in length and 5 cm in the width direction, with the adhesive layer as the top surface, in an environment of 20-25 ° C./45-55% RH for 20 hours on a flat place The amount of float at both ends was measured for the warp in the width direction, and the average was taken as the amount of warp. The warp having no problem in practical use is 2 mm or less.

2. Adhesiveness After laminating a 10 mm wide mask sheet on a copper plate (125 μm 7025 type, manufactured by Furukawa) at a rate of 0.5 m / min with a metal roll at 150 ° C., the adhesive force is peeled at 90 ° at a tensile speed of 50 mm / min. Measured. A practical adhesive strength of 5 g / cm or more is a problem.

3. Foam test generated between the mask sheet and the pasted frame in the Die-Attach curing process (D / A) A 1 cm wide mask sheet was applied to the copper plate with a metal roll at 150 ° C. at a rate of 0.5 m / min. After laminating at a speed and treating to 175 ° C. for 30 minutes, foaming was further confirmed when treated at 175 ° C. for 1 hour.

4). Wire bonding (W / B)
The mask sheets obtained in each of the examples and comparative examples were subjected to a QFN lead frame (Au—Pd—Ni plated Cu lead frame of 4 × 16 pieces (total of 64 pieces) in a matrix size of 200 mm × 60 mm, package size). 10 mm × 10 mm, 84 pins) by a heat laminating method. Next, a dummy chip (6 mm × 6 mm, thickness 0.4 mm) on which aluminum was vapor-deposited using an epoxy die attach agent was mounted on the semiconductor element mounting portion of the lead frame. After that, without performing plasma cleaning, a wire bonder (manufactured by Shinkawa Co., UTC-470BI) was used, heating temperature was 210 ° C., US power was 30, load was 0.59 N, processing time was 10 msec / pin, dummy chip And the lead were electrically connected by a gold wire. The obtained 64 semiconductor devices were inspected, and the number of semiconductor devices in which a lead-side connection failure occurred was examined as the number of wire bonding failures.

5. Adhesive residue, mold flash QFN lead frame with external dimensions of 200 mm x 60 mm (Au-Pd-Ni plated Cu lead frame, 4 x 16 (64 total) matrix arrangement, package size 10 mm x 10 mm, 84 pins) After laminating the mask sheet with a rubber roll at 140 ° C. at 0.3 m / min, heat treatment at 175 ° C./1 h is performed as a condition for chip mounting, 450 W / 60 sec Ar plasma treatment is performed, and the mold is sealed. Thereafter, the mask sheet was peeled off at 90 ° and peeled at 50 mm / min, and the presence or absence of adhesive residue (residue of the mask sheet adhesive on the mold resin) and the presence or absence of mold flash (mold resin leakage) were confirmed.
Regarding the adhesive residue, the adhesive residue on the mold resin on the frame and in contact with the adhesive portion of the mask sheet was observed with a 4 × magnification microscope to determine the presence or absence of the adhesive residue.
With regard to the mold flash, the presence or absence of the mold resin oozing (flash) on the frame was observed with a 4 × stereomicroscope to determine the presence or absence.

As the evaluation result described in the said Table 4, the mask sheet | seat of this invention of Examples 1-12 had planarity with 2 mm or less of flatness curvature. Further, the sticking property is 5 g / cm or more, and taping to L / F can be performed at a low temperature. Also, in the foam test, it does not foam, and hardly deteriorates even when exposed to high temperatures. It was also confirmed that the wire bonding property, the adhesive residue, and the mold flash test were excellent. Moreover, it was a result inferior compared with Examples 1-12 about Comparative Examples 13-16.
On the other hand, in the mask sheets of the comparative examples in Table 5, the mask sheets of the comparative examples 1 and 7 had a problem of practicality with a flatness warpage exceeding 2 mm.
Further, the mask sheets of Comparative Example 1, Comparative Example 3, Comparative Example 4, and Comparative Example 7 had a problem of practical use because their sticking properties were smaller than 5 g / cm. Further, the mask sheet of Comparative Example 8 is foamed by a foam test, and the mask sheets of Comparative Example 2 and Comparative Examples 3 to 6 have practical problems in any of the tests for wire bonding, adhesive residue, and mold flash. It was a thing.

[Example 17]
The mask sheet obtained in Example 1 was thermocompression bonded at 140 ° C. to a copper foil (trade name: FQ-VLP 18 μm) manufactured by Mitsui Kinzoku Co., Ltd., and then the adhesive layer was cured by heat treatment at 175 ° C. for 1 hour. Next, the copper foil layer was etched using a 40 Baume etching solution using ferric oxide so as to form a QFN lead frame pattern as shown in FIG. Thereafter, the wire bonding property (W / B), the remaining adhesive and the mold flash were evaluated in the same manner as in Example 1 on the copper foil QFN lead frame pattern to which the mask sheet was adhered. As a result, it was confirmed that no defect occurred in wire bonding, and there was no adhesive residue and mold flash.
Thereby, the mask sheet of the present invention can be laminated on a thin film metal foil such as copper, and thereafter the adhesive is cured by heat, and then the thin film metal foil is formed by etching into a predetermined pattern, It was confirmed that it is suitable for the process of forming a semiconductor device through die attach, wire bonding, and molding processes.

[Comparative Example 9]
The mask sheet obtained in Comparative Example 5 was thermocompression bonded at 140 ° C. to a copper foil (trade name: FQ-VLP 18 μm) manufactured by Mitsui Kinzoku Co., and the adhesive layer was cured by heat treatment at 175 ° C. for 1 hour. Next, the copper foil layer was etched using a 40 Baume etching solution using ferric oxide so as to form a QFN lead frame pattern as shown in FIG. Thereafter, the wire bonding property (W / B), the remaining adhesive and the mold flash were evaluated in the same manner as in Example 1 on the copper foil QFN lead frame pattern to which the mask sheet was adhered. As a result, the number of wire bonding defects was 15, and adhesive residue and mold flash were also generated. This is probably because the adhesive swells due to the etching solution.

DESCRIPTION OF SYMBOLS 10 Mask sheet | seat for semiconductor device manufacture 20 Lead frame 30 Semiconductor element 31 Bonding wire 40 Mold resin

Claims (3)

A mask sheet for manufacturing a semiconductor device in which a thermosetting adhesive layer is laminated on one surface of a base material layer and is detachably attached to a metal plate, wherein the thermosetting adhesive layer has a glass transition temperature. Containing a polyimide resin containing a siloxane skeleton having a siloxane skeleton of 45 to 170 ° C., an epoxy resin, a curing agent, and a fluorine additive comprising a fluorine- containing / lipophilic group-containing oligomer that is liquid at 25 ° C., and the content of the polyimide resin 35 to 75% by mass, the epoxy resin content is 15 to 45% by mass, and the fluorine additive content is 0.5 to 5 phr (excluding the fluorine additive, based on 100 g of the adhesive). A mask sheet for manufacturing a semiconductor device.   2. The melt viscosity curve of the thermosetting adhesive layer has a minimum lower limit value of 70 to 200 ° C. and a lower limit viscosity of 4000 Pa · s or more. Mask sheet for semiconductor device manufacturing.   The thermosetting adhesive layer of the mask sheet for manufacturing a semiconductor device according to claim 1 is laminated on a metal plate, the metal plate is formed into a predetermined pattern, a semiconductor chip is mounted, molded, and then the semiconductor A method of manufacturing a semiconductor device, comprising removing a mask sheet for manufacturing the device.

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