JP2019137785A - Adhesive sheet for manufacturing semiconductor device, and manufacturing method of semiconductor device using the same - Google Patents

Abstract

To provide an adhesive sheet which sufficiently and stably adheres to back surface of a lead frame and a back surface of an encapsulating resin without detachment from them even when received heat history owing to the QFN assemblage, having no leakage of the encapsulating agent, capable of easily being detached in a detachment process, and having neither generation of paste residue with remaining an adhesive nor breaking, and a manufacturing method of a semiconductor device using the same.SOLUTION: There is provided an adhesive sheet for manufacturing a semiconductor device having a substrate, a thermosetting adhesive layer arranged on one surface of the substrate, which is detachably adhered to a lead frame or a wiring board of a semiconductor device, in which the adhesive layer contains a carboxyl group-containing acrylonitrile-butadiene copolymer (a), a tri-functional epoxy resin having a structure by composing bisphenol A (b) and a compound containing 2 or more maleimide groups (c), and unreacted maleimide residue amount is 0.02 to 0.13.SELECTED DRAWING: None

Description

  The present invention relates to an adhesive sheet suitably used as a mask tape when a semiconductor device is assembled by a QFN (Quad Flat Non-lead) method, and a method of manufacturing a semiconductor device using the adhesive sheet.

In recent years, the demand for further high-density mounting technology in semiconductor devices (semiconductor packages) has been increasing in response to demands for downsizing, thinning, and multi-functioning of IT equipment including mobile phones.
As a CSP (Chip Size Package) technology that meets this requirement, the QFN method has attracted attention (see Patent Document 1 and Patent Document 2), and is widely used particularly in a small pin type of 100 pins or less.

  Here, the following method is generally known as a general method of assembling a QFN package by the QFN method. First, in the attaching step, an adhesive sheet is attached to one surface of the lead frame, and then in the die attaching step, a plurality of semiconductor element mounting portions (die pad portions) formed on the lead frame are attached to a semiconductor such as an IC chip. Each element is mounted. Next, in the wire bonding step, the plurality of leads arranged along the outer periphery of each semiconductor element mounting portion of the lead frame and the semiconductor elements are electrically connected by bonding wires. Next, in the sealing step, the semiconductor element mounted on the lead frame is sealed with a sealing resin. Thereafter, in the peeling step, the QFN unit in which a plurality of QFN packages are arranged can be formed by peeling the adhesive sheet from the lead frame. Finally, in the dicing step, a plurality of QFN packages can be manufactured by dicing the QFN unit along the outer periphery of each QFN package.

Adhesive sheets used in such applications can be sufficiently and stably attached to the adhesive sheet without peeling from the back surface of the lead frame and the back surface of the sealing resin before the peeling process, and can be easily peeled off in the peeling process. It is required that there is no inconvenience such as adhesive residue remaining on the back surface of the lead frame and the back surface of the sealing resin, and breakage of the adhesive sheet.
Particularly in recent years, lead frames made of copper alloys have been used to reduce the cost of semiconductor devices. The lead frame made of such a copper alloy also has a catalytic action of oxidative degradation to the copper polymer material which is a transition metal, and the adhesive is likely to be oxidatively degraded due to the thermal history accompanying the QFN package assembly after the taping process, Heavy peeling and adhesive residue are likely to occur when the sheet is peeled off.

However, the conventionally used adhesive sheet does not sufficiently satisfy a practical level that can be used for a lead frame made of a copper alloy.
For example, a conventional adhesive sheet has a form in which an adhesive layer containing an acrylonitrile-butadiene copolymer and a bismaleimide resin is laminated on a base material made of a heat resistant film (see Patent Document 3). When this is used, the acrylonitrile-butadiene copolymer is likely to deteriorate due to the heat applied in the die attach curing process, the wire bonding process, and the resin sealing process after the taping process, making it difficult to remove in the peeling process. Or the adhesive sheet breaks or adhesive residue occurs.

Japanese Patent Laid-Open No. 2003-165961 Japanese Patent Laid-Open No. 2005-142401 JP 2008-095014 A

  The present invention has been made in view of the above circumstances, and until the peeling step, even if it receives a thermal history associated with the QFN assembly, it is sufficiently and stable without being peeled off from the back surface of the lead frame and the back surface of the sealing resin. Adhesive sheet that adheres to the substrate, has no leakage of sealing resin, and can be easily peeled off in the peeling step, and no adhesive residue remains or breaks, and a semiconductor device manufacturing method using the same It is an issue to provide.

  The adhesive sheet for manufacturing a semiconductor device of the present invention includes a base material and a thermosetting adhesive layer provided on one surface of the base material, and is detachably attached to a lead frame or a wiring board of the semiconductor device. In the adhesive sheet for manufacturing a semiconductor device to be attached, the adhesive layer comprises a carboxyl group-containing acrylonitrile-butadiene copolymer (a), an epoxy resin (b) having the following structural formula (1), and a maleimide group. Containing at least one compound (c), and the unreacted maleimide residue is 0.02 to 0.13.

  The component (a) is a carboxyl group-containing acrylonitrile-butadiene copolymer having an acrylonitrile content of 5 to 50% by mass and a carboxyl group equivalent calculated from the number average molecular weight of 100 to 20000. preferable.

The total of the component (b) and the component (c) is preferably 20 to 300 parts by mass with respect to 100 parts by mass of the component (a).
Moreover, the manufacturing method of the semiconductor device of this invention is a manufacturing method of the semiconductor device using the adhesive sheet for semiconductor device manufacture described above,
An adhering step of adhering an adhesive sheet for manufacturing a semiconductor device to a lead frame or a wiring board;
A die attach step of mounting a semiconductor element on the lead frame or the wiring substrate;
A wire bonding step for conducting the semiconductor element and the external connection terminal;
A sealing step of sealing the semiconductor element with a sealing resin;
After the sealing step, a peeling step of peeling the semiconductor device manufacturing adhesive sheet from the lead frame or the wiring board is provided.

  According to the present invention, before the peeling process, even if it receives a thermal history associated with QFN assembly, it is sufficiently and stably attached to the back surface of the lead frame and the back surface of the sealing resin, and sealed. It is possible to provide an adhesive sheet that does not leak resin, can be easily peeled off in the peeling step, and does not cause adhesive residue in which adhesive remains or breaks, and a method of manufacturing a semiconductor device used therefor.

It is a top view which shows an example of the lead frame used for the manufacturing method of the semiconductor device of this invention. It is process drawing explaining the manufacturing method of the semiconductor device of this invention.

Hereinafter, the present invention will be described in detail.
[Adhesive sheet for manufacturing semiconductor devices]
An adhesive sheet for manufacturing a semiconductor device of the present invention (hereinafter referred to as an adhesive sheet) includes a base material and a thermosetting adhesive layer provided on one surface of the base material. In the adhesive sheet that is detachably attached to the wiring board, the adhesive layer includes a carboxyl group-containing acrylonitrile-butadiene copolymer (a), an epoxy resin (b) having the following structural formula (1), and maleimide Containing compound (c) containing two or more groups and having an unreacted maleimide residue of 0.02 to 0.13, used as a mask tape when assembling a semiconductor device by the QFN method Is done.

  The carboxyl group-containing acrylonitrile-butadiene copolymer (a) plays a role of appropriately maintaining the melt viscosity of the adhesive layer in the initial stage of heating and has good flexibility and adhesion to the cured adhesive layer. By providing and containing this, it is possible to form an adhesive layer that has good adhesion to a substrate made of a heat-resistant film or the like and that does not crack. As the carboxyl group-containing acrylonitrile-butadiene copolymer (a), known ones can be used without limitation, but those having an acrylonitrile content of 5 to 50% by mass are preferred, and those having 10 to 40% by mass are more preferred. When the acrylonitrile content is less than the above range, the solubility in a solvent and the compatibility with other components are lowered, and the uniformity of the resulting adhesive layer tends to be lowered. On the other hand, when the acrylonitrile content exceeds the above range, the resulting adhesive layer becomes excessively adherent to the lead frame and the sealing resin, and when this is used for an adhesive sheet, it becomes difficult to peel in the peeling step. Or the adhesive sheet may break.

The carboxyl group equivalent calculated from the number average molecular weight in the carboxyl group-containing acrylonitrile-butadiene copolymer is preferably in the range of 100 to 20000, more preferably 200 to 10,000. When the carboxyl group equivalent is less than the above range, the reactivity with other components becomes too high, and the storage stability of the resulting adhesive layer tends to be lowered. On the other hand, when the carboxyl group equivalent exceeds the above range, the reactivity with other components is insufficient, so that the resulting adhesive layer tends to be a low B stage. As a result, when this is used for an adhesive sheet, the adhesive layer is reduced in viscosity when the adhesive sheet is heated in the initial stage of heating, that is, in the adhesive sheet sticking process or die attach curing process. The layer tends to foam or flow out, and the thermal stability tends to decrease.
The carboxyl group equivalent calculated from the number average molecular weight is obtained by dividing the number average molecular weight (Mn) by the number of carboxyl groups (number of functional groups) per molecule, and is represented by the following formula.
Carboxyl group equivalent = Mn / number of functional groups

  The epoxy resin (b) and the compound (c) containing two or more maleimide groups are responsible for the thermosetting property of the adhesive layer, and by using these in combination, they are excellent in thermal stability and are peelable. In the process, an adhesive layer that can be easily peeled off and does not cause adhesive residue or breakage can be formed. In particular, the epoxy resin (b) imparts toughness to the adhesive layer. By containing this, the adhesive residue due to the cracking of the adhesive layer in the peeling step can be suppressed.

The compound (c) containing two or more maleimide groups imparts heat stability to the adhesive layer and also has an effect of adjusting the adhesiveness of the adhesive layer. Is appropriately controlled, and an adhesive layer that can be easily peeled in the peeling step can be formed.
As a specific example of the compound (c) containing two or more maleimide groups, a compound constituting a bismaleimide resin is preferably used, and examples thereof include those of the following formulas (2-1) to (2-3). Of these, the compound represented by the following formula (2-1) or (2-3) is particularly useful in terms of solubility in a solvent.

  In addition, as each component of the above-mentioned (a)-(c), you may use what was comprised from 1 type of compounds, and may use the mixture of 2 or more types of compounds. .

The adhesive layer in the adhesive sheet for manufacturing a semiconductor device of the present invention must have an unreacted maleimide residual amount of 0.02 to 0.13. In particular, the residual amount of unreacted maleimide is preferably 0.02 to 0.10. When the unreacted maleimide residual amount is lower than 0.02, the initial adhesive strength to the lead frame is low, and problems such as occurrence of an unattached portion at the time of laminating occur. On the other hand, when it is higher than 0.13, the initial adhesive strength to the lead frame is increased, and as a result, the detaping property after the assembly of the package is deteriorated (high peel strength, adhesive residue / tape breakage is likely to occur). In order to make the unreacted maleimide residual amount 0.02 to 0.13, it can be obtained by appropriately controlling the curing during the drying process during the production of the adhesive layer.
The residual amount of unreacted maleimide can be obtained by analyzing the result of measuring the adhesive layer by FT-IR spectroscopy (Fourier transform infrared spectroscopy). The unreacted maleimide residual amount is calculated from the ratio (S1148 / S1500) of the integrated value of the maleimide peak (1148 cm ⁻¹ ) and the integrated value of the aromatic ring peak (1500 cm ⁻¹ ) in FT-IR. The The analysis method for the unreacted maleimide residue is described in detail in the evaluation results of the examples.

  The ratio of each component is preferably 20 to 300 parts by mass, and more preferably 20 to 200 parts by mass with respect to 100 parts by mass of component (a). When the sum of the component (b) and the component (c) is less than the above range, the reactivity of the adhesive layer is reduced, and insolubility and infusibilization are difficult to proceed even by heating, and the thermal stability is reduced. There is a tendency for the adhesive strength to increase. On the other hand, when the above range is exceeded, the melt viscosity of the adhesive layer at the initial stage of heating is insufficient, and in the adhesive sheet using this adhesive layer, the adhesive layer flows out or foams due to die attach curing treatment after the taping process. There is a risk of doing so.

  Furthermore, the mass ratio ((c) / (b)) of the component (c) to the component (b) is preferably in the range of 0.1 to 10. If it is less than the above range, the resulting adhesive layer is likely to undergo a curing reaction at room temperature, resulting in poor storage stability, or the adhesive strength becomes too strong, and an adhesive sheet using this cannot be peeled off in the peeling step. Or may break. On the other hand, if the above range is exceeded, when the adhesive sheet is produced, when the adhesiveness between the adhesive layer and the substrate made of the heat-resistant film is reduced, the adhesive layer is foamed, or the obtained adhesive sheet There is a tendency that glue tends to remain.

The adhesive layer in the adhesive sheet for manufacturing a semiconductor device of the present invention may contain a reactive siloxane compound. The reactive siloxane compound is for improving the compatibility of each component constituting the adhesive layer and for improving the peelability of the adhesive layer from the sealing resin. The components are compatible with each other, and a uniform adhesive layer free from inconveniences such as separation and precipitation of components can be formed. As a result, the adhesive layer has a uniform adhesive strength, and it is possible to suppress inconveniences such as a decrease in peelability and adhesive residue due to a partially high adhesive strength.
As the reactive siloxane compound, a siloxane compound imparted with reactivity by a reactive group such as amino modification, epoxy modification, carboxyl modification, mercapto modification, etc. can be used without any limitation. Among these, 1,3-bis (3-aminopropyl) tetramethyldisiloxane, aminopropyl-terminated dimethylsiloxane tetramer or octamer, and bis (3-aminophenoxymethyl) tetramethyldisiloxane are (b ) Component and (c) component are preferred in that the reaction proceeds rapidly. As the reactive siloxane compound, it is preferable from the viewpoint of reactivity that the reactive group is bonded to both ends of the siloxane structure as described above. Non-reactive silane coupling agents can also be used.

  In the adhesive layer of the adhesive sheet for manufacturing a semiconductor device of the present invention, the ratio of the number of reactive groups of the reactive siloxane compound to the total of the number of epoxy groups of the component (b) and the number of maleimide groups of the component (c) is 0.05 to 1. It is preferable that it is 2, More preferably, it is 0.1-0.8. If it is less than the said range, the reactivity as the whole adhesive bond layer will fall, and it will become difficult for hardening reaction to advance by the die attach cure process etc., As a result, adhesive force may become strong too much. On the other hand, when the above range is exceeded, the reaction proceeds excessively, and problems such as gelation tend to occur during the preparation of the adhesive layer, and the adhesive strength tends to be weakened.

In addition to the essential components (a) to (c), a reaction accelerator such as an organic peroxide, imidazoles, or triphenylphosphine may be added to the adhesive layer. By adding these, it is also possible to control the state of the adhesive layer at room temperature to a good B stage.
Furthermore, a filler having an average particle size of 1 μm or less may be added for the purpose of controlling the melt viscosity, improving thermal conductivity, imparting flame retardancy, and the like. Examples of the filler include inorganic fillers such as silica, alumina, magnesia, aluminum nitride, boron nitride, titanium oxide, calcium carbonate, and aluminum hydroxide, and organic fillers such as silicone resin and fluorine resin. When using a filler, it is preferable that the content shall be 1-40 mass% in an adhesive bond layer.

In the adhesive sheet of the present invention, the above-mentioned adhesive layer is formed on one side of a heat-resistant film as a base material.
When producing such an adhesive sheet, first, at least the carboxyl group-containing acrylonitrile-butadiene copolymer (a), the epoxy resin (b) having the above structural formula (1), and two or more maleimide groups are used. An adhesive paint comprising a compound (c) to be contained and, if necessary, a reactive siloxane compound and a solvent is prepared. Next, this coating material may be applied to one side of the heat-resistant film so that the thickness of the adhesive layer after drying is preferably 1 to 50 μm, more preferably 3 to 20 μm, and dried. In order to protect the adhesive layer, it is preferable to further provide a peelable protective film on the formed adhesive layer. In that case, a paint is applied on the protective film, and then dried and adhered. You may manufacture an adhesive sheet by the method of forming an agent layer and providing a heat resistant film on it. The protective film is peeled off when the adhesive sheet is used.

Examples of heat resistant films include heat resistant plastic films made of polyimide, polyphenylene sulfide, polyether sulfone, polyether ether ketone, liquid crystal polymer, polyethylene terephthalate, polyethylene naphthalate, and composite heat resistant films such as epoxy resin-glass cloth. However, a polyimide film is particularly preferable.
The thickness of the polyimide film is preferably 12.5 to 125 μm, more preferably 25 to 50 μm. If it is less than the above range, the adhesive sheet will have insufficient stiffness and tend to be difficult to handle, and if it exceeds the above range, work in the taping process or peeling process during QFN assembly tends to be difficult.

  As the solvent used in the adhesive coating, one or more of organic solvents such as hydrocarbons, alcohols, ketones, ethers (such as tetrahydrofuran), water, etc. can be preferably used. And may be adjusted as appropriate so as to obtain an appropriate viscosity. The properties of the paint may be any of a solution, an emulsion, and a suspension, and may be appropriately selected according to the coating apparatus to be used and environmental conditions.

  Examples of the peelable protective film include plastic films such as polyethylene, polypropylene, vinyl chloride, fluororesin, and silicone, and polyethylene terephthalate, polyethylene naphthalate, paper, and the like that have been made peelable by silicone coating or the like.

[Method for Manufacturing Semiconductor Device]
A manufacturing method of a semiconductor device using an adhesive sheet of the present invention includes an attaching step of attaching an adhesive sheet to a lead frame or a wiring substrate, a die attaching step of mounting a semiconductor element on the lead frame or the wiring substrate, and a semiconductor element A wire bonding step for conducting electrical connection with the external connection terminal, a sealing step for sealing the semiconductor element with a sealing resin, and a peeling step for peeling the adhesive sheet from the lead frame or the wiring substrate after the sealing step. Is.

  Hereinafter, an example of the manufacturing method of the semiconductor device using the adhesive sheet of this invention is demonstrated with reference to FIGS. FIG. 1 is a plan view of a lead frame as viewed from the side on which a semiconductor element is mounted, and FIGS. 2A to 2F are steps showing a method of manufacturing a QFN package using the lead frame shown in FIG. FIG. 2 is a cross-sectional view of the lead frame of FIG. 1 along AA ′.

First, a lead frame 20 having a schematic configuration shown in FIG. 1 is prepared. In the lead frame 20, a plurality of semiconductor element mounting portions (die pad portions) 21 for mounting semiconductor elements such as IC chips are formed in a matrix, and a large number of leads 22 (external connection) are provided along the outer periphery of each semiconductor element mounting portion 21. Terminal) is formed.
Examples of the material of the lead frame 20 include conventionally known materials, for example, a copper plate and a copper alloy plate, or those having strike plating provided thereon, a nickel plating layer and a palladium plating layer on the surface of the copper alloy plate. The thing provided with the gold plating layer in this order is mentioned.

As shown in FIG. 2A, the adhesive sheet 10 is adhered to one surface (lower surface) of the lead frame 20 so that the adhesive layer (not shown) contacts the lead frame 20 (adhesion step). . As a method for adhering the adhesive sheet 10 to the lead frame 20, there are a laminating method, a pressing method, and the like. From the viewpoint of productivity, a laminating method capable of continuously performing a taping process is preferable. The temperature of the adhesive sheet 10 in this step is, for example, normal temperature (5-35 ° C.) to 150 ° C., and more preferably 60-120 ° C. If it is attached at a temperature higher than 150 ° C., the lead frame is likely to warp.
If the lead frame 20 is warped in this process, positioning in the die attach process or wire bonding process becomes difficult, and transport to the heating furnace becomes difficult, which may reduce the productivity of the QFN package. .

  As shown in FIG. 2B, a semiconductor element 30 such as an IC chip is attached to the side of the semiconductor element mounting portion 21 of the lead frame 20 where the adhesive sheet 10 is not attached via a die attach agent (not shown). Place. At this time, the lead frame 20 is easily positioned because warpage is suppressed. Then, the semiconductor element 30 is accurately placed at a predetermined position. Then, it heats to about 100-200 degreeC, a die attach agent is hardened, and the semiconductor element 30 is fixed and mounted in the semiconductor element mounting part 21 (die attach agent hardening process. As mentioned above, a die attach process). At this time, the adhesive sheet 10 is bonded to the lead frame after the adhesive layer is cured.

  If an outgas component generated from the adhesive sheet 10 or the die attach agent or the like is attached to the lead frame 20 or the semiconductor element 30, the yield is likely to decrease due to poor bonding of the wires in the wire bonding process. Therefore, plasma processing is performed on the lead frame 20 and the semiconductor element 30 after the die attach process and before the wire bonding process (plasma cleaning process). As the plasma treatment, for example, a lead frame 20 (hereinafter sometimes referred to as work-in-process) on which the adhesive sheet 10 is attached and the semiconductor element 30 is mounted is made of argon gas or a mixed gas of argon gas and hydrogen gas. A method of plasma irradiation in an atmosphere can be mentioned. The plasma irradiation output in the plasma processing is, for example, 150 to 600 W. Moreover, the time of plasma processing shall be 0.1 to 15 minutes, for example.

As shown in FIG. 2C, the semiconductor element 30 and the lead 22 (external connection terminal) of the lead frame 20 are electrically connected by a bonding wire 31 such as a gold wire, a copper wire, or a copper wire covered with palladium. (Wire bonding process). This step is performed while heating the work-in-process to about 150 to 250 ° C. on the heater block. The heating time in this step is, for example, 5 to 60 minutes.
When the work-in-process is heated in the wire bonding process, when the fluorine additive is contained in the adhesive layer, the fluorine additive moves to the surface of the adhesive layer. Is easily peeled off from the lead frame 20 and the sealing resin 40.

As shown in FIG. 2 (d), the work-in-process shown in FIG. 2 (c) is placed in the mold, and is injected and filled into the mold using a sealing resin (mold material). After filling an arbitrary amount into the mold, the semiconductor element 30 is sealed with the sealing resin 40 by maintaining the inside of the mold at an arbitrary pressure (sealing process). A conventionally well-known thing is used as sealing resin, For example, mixtures, such as an epoxy resin and an inorganic filler, are mentioned.
As shown in FIG. 2E, the adhesive sheet 10 is peeled from the sealing resin 40 and the lead frame 20 to obtain a QFN unit 60 in which a plurality of QFN packages 50 are arranged (peeling step).

  As shown in FIG. 2F, a plurality of QFN packages 50 are obtained by dicing the QFN unit 60 along the outer periphery of each QFN package 50 (dicing step).

  In the above-described embodiment, the QFN package manufacturing method using the lead frame has been described as an example. However, the present invention is not limited thereto, and the semiconductor device manufacturing method other than the QFN package using the lead frame, The present invention can also be applied to a method for manufacturing a semiconductor device using a wiring board.

  The adhesive layer in the adhesive sheet of the present invention takes a B-stage state (semi-cured state) by crosslinking the carboxyl group of the carboxyl group-containing acrylonitrile-butadiene copolymer (a) and the glycidyl group of the epoxy resin (b). Thereby, it can be set as a low glass transition temperature (-30 degreeC-50 degreeC). An adhesive sheet having an adhesive layer having a low glass transition temperature can be continuously subjected to a taping process using a roll laminator or the like under relatively low-temperature heating conditions, specifically from room temperature (5 ° C. to 35 ° C.) to 150 ° C. And excellent productivity.

Moreover, the adhesive layer of the low glass transition temperature (-30 degreeC-50 degreeC) in the adhesive sheet of this invention will obtain the characteristic of a high elastic modulus, when heated. In recent years, for the purpose of reducing the cost in the wire bonding process, products that are bonded with low-cost copper wires or palladium-coated copper wires in place of conventional gold wires have started to spread. The copper wire or the copper wire coated with palladium is a metal having higher elasticity than gold, so that a process with a higher load than that of a conventional gold wire is required to form a stable shape.
When such a large load is applied to the lead frame, if the adhesive layer in the adhesive sheet attached to the lower part of the lead frame has a low elastic modulus, the adhesive layer is deformed and the deformed adhesive layer Resin-sealed in a state. Then, leakage of the sealing resin occurs from the deformed adhesive layer portion. Further, when the adhesive sheet is peeled from the lead frame, there is a problem that the adhesive layer breaks from the deformed adhesive layer portion and the adhesive remains on the lead frame surface. In addition, if the adhesive has a low elastic modulus at the time of wire bonding, the adhesive is deformed, so that the wire load is difficult to be transmitted and wire bonding defects are likely to occur. Since the adhesive layer in the adhesive sheet of the present invention has a high elastic modulus characteristic as described above, even if wire bonding is performed using a copper wire or a copper wire coated with palladium, wire bonding failure or sealing is prevented. It is difficult to cause problems such as leakage of the stop resin and residual adhesive layer.

  Moreover, since the adhesive layer in the adhesive sheet of the present invention contains a compound (c) containing two or more maleimide groups and the unreacted maleimide resin residual amount is in a specific range, the adhesive layer is It is possible to achieve a high B stage state, and therefore, it is possible to suppress an increase in adhesive strength to the lead frame. As a result, leakage of the sealing resin, residual adhesive on the lead frame, and the adhesive layer at the time of peeling Breakage can be suppressed.

Hereinafter, the present invention will be specifically described with reference to examples.
[Examples 1-4 and Comparative Examples 1-3]
(Composition of adhesive paint)
Adhesive paints were prepared by mixing components (a) to (c) and other components and tetrahydrofuran (THF) as a solvent at a mass ratio shown in Table 1.
Next, this adhesive paint was applied to one side of a 25 μm-thick polyimide film (trade name Kapton 100EN, manufactured by Toray DuPont) so that the adhesive layer thickness after drying would be 5 μm, and then dried as shown in Table 1. Based on conditions, it dried in the hot air circulation type oven, and obtained the adhesive sheet.
In addition, the detail of each used component is as follows.

Carboxyl group-containing acrylonitrile-butadiene copolymer: carboxyl group equivalent 1500 calculated from number average molecular weight, acrylonitrile content 27% by mass
Epoxy resin having the structural formula (1): molecular weight 630, functional group equivalent 210 g / eq
Bisphenol A diphenyl ether bismaleimide: molecular weight 570, functional group equivalent 285 g / eq
1,3-bis (3-aminopropyl) tetramethyldisiloxane: molecular weight 248, functional group equivalent 62 g / eq

The adhesive sheet of each example obtained as described above was subjected to the following measurements and evaluations, and the results are shown in Table 2.
(1) Unreacted residual amount of maleimide The residual amount of maleimide in the adhesive sheet was measured by an ATR (Attenuated Total Reflection) method using FT-IR (Spectraum 100 manufactured by Perkin Elmer). The calculation method of the maleimide residual amount of an adhesive sheet is shown below.
(i) Measurement: After ATR correction and absorbance conversion, the peak areas at wave numbers S1 and S2 below are calculated.
S1 = Integral value of maleimide peak (1148 cm ⁻¹ ) S2 = Integral value of maleimide aromatic ring peak (1500 cm ⁻¹ )
(ii) The ratio of S1 / S2 was the unreacted maleimide residue.

(2) Peel strength against Cu plate Substrate: Copper plate (Furukawa 125μm7025 type)
Adhesive sheet size: 10mm width x 50mm length
Processing: Using a roll laminator, the adhesive sheet obtained in each example was attached to an adherend to make a test body. The lamination conditions at that time were a temperature of 80 ° C., a pressure of 4 N / cm, and a pressure bonding speed of 1 m / min.
Measurement: Using a universal tensile testing machine, the 90 ° peel strength of the specimen was measured at room temperature. The measurement was performed by fixing the copper plate and pulling the adhesive sheet in the vertical direction. The tensile speed was 50 mm / min.
Evaluation: Peel strength is an adhesive strength that has a practical problem of 5 gf / cm or more. 5 gf / cm or more was rated as ◯, and less than 5 gf / cm was rated as x.

(3) Thermal characteristics after the die attach step Processing: In the adhesive sheet obtained in each example, a polyimide film having a thickness of 25 μm was converted into a polyethylene terephthalate film (PET film) having a release treatment having a thickness of 38 μm. Assuming a die attach cure process, it was heated at 175 ° C. for 1 hour using a ventilated oven.
Measurement: The adhesive layer in the adhesive sheet after heating was taken out from the PET film, and the tensile storage modulus was measured using DMA (Dynamic Mechanical Analyzer).
Measurement was performed at a frequency of 11 Hz, a temperature increase rate of 10 ° C./min, and a load of 1.0 gf using a Vibron measuring device (RHEOVIBRON DDV-II-EP, manufactured by Orientec Corp.) as DMA.
Evaluation: The temperature at the time of assuming the time of the wire bonding process, and the one having a tensile storage elastic modulus at 200 ° C. of 10 MPa or more was evaluated as ◯.

(4) Peel strength against specimen after resin sealing step, presence or absence of adhesive residue after tape peeling Processing / measurement method:
(I) Preparation of test body and heat treatment After cutting the adhesive sheet obtained in each example into a width of 50 mm and a length of 60 mm, assuming the heat history associated with the actual assembly of QFN, first, the following (a ) To (d) were sequentially performed.
(A) The adhesive sheet obtained in each example was cut into a width of 50 mm × a length of 60 mm, and this was a test lead frame made of a 50 mm × 100 mm outer dimension 57.5 mm × 53.5 mm copper alloy (surface strike plating, (8 × 8 matrix arrangement, package size 5 mm × 5 mm, 32 pins) was attached using a roll laminator. The lamination conditions at that time were a temperature of 80 ° C., a pressure of 4 N / cm, and a pressure bonding speed of 1 m / min.
(B) A copper alloy test lead frame to which the adhesive sheet was attached was heated in a ventilation oven at 175 ° C./1 hour. This is a process assuming a die attach cure process.
(C) Plasma irradiation treatment: Treated for 450 W / 60 seconds using 1000P manufactured by Yield Engineering, using Ar as the gas species.
(D) Heating at 200 ° C./30 minutes: A process assuming a wire bonding process, which was heated using a hot plate.
Next, on the copper material exposed surface opposite to the surface on which the adhesive sheet of the adherend subjected to the heat treatment of (a) to (d) is bonded, using a mold press machine, the condition is 175 ° C./3 minutes. A sealing resin was laminated (resin sealing step). As the sealing resin, an epoxy mold resin (EME-G631BQ) manufactured by Sumitomo Bakelite Co., Ltd. was used.

(Ii) Peel strength measurement, presence or absence of adhesive residue after tape peeling About the test body after the resin sealing process described above, a 90 ° peel strength was measured at room temperature using a universal tensile tester. In addition, it measured by fixing the test body and pulling the corner part of an adhesive sheet to the orthogonal | vertical direction. The tensile speed was 300 mm / min. Moreover, the presence or absence of the adhesive residue after tape peeling was confirmed at 100-times multiplication factor using the optical microscope (Keyence Corporation digital microscope VHX-500).
Rating:
A: The peel strength is less than 1000 gf / 50 mm, the peeled adhesive sheet is not broken, and no adhesive remains on the lead frame material surface and the sealing resin surface.
Δ: Peel strength is 1000 gf / 50 mm or more, the peeled adhesive sheet is not broken, and no adhesive remains on the lead frame material surface and the sealing resin surface.
X: Corresponds to at least one of rupture of the adhesive sheet or the presence of residual adhesive on the lead frame material surface and the sealing resin surface.

(5) Presence or absence of resin leakage About the test body after the above-mentioned resin sealing process, the presence or absence of sealing resin leakage was confirmed using an optical microscope (Keyence Corporation digital microscope VHX-500) at a magnification of 100 times. .
○: The sealing resin does not leak onto the surface of the test lead frame material that has been sealed with the resin after the adhesive sheet is peeled off.

As is apparent from Table 2 above, the adhesive sheets of Examples 1 to 4 were peel strengths with respect to the Cu plate, thermal characteristics after the die attach process, peel strengths with respect to the test specimen after the resin sealing process, and after tape peeling. In all the evaluations regarding the presence or absence of adhesive residue and the presence or absence of resin leakage, there were no practical problems.
On the other hand, the adhesive sheets of Comparative Example 1 and Comparative Example 2 have a problem that they cannot be attached to a test lead frame made of copper alloy in the evaluation of peel strength for the specimen after the resin sealing step. It was. In addition, the adhesive sheet of Comparative Example 3 has a problem in that the adhesive sheet is torn apart in the evaluation of the peel strength with respect to the specimen after the resin sealing step, and is firmly bonded to the test lead frame made of copper alloy. It was.

DESCRIPTION OF SYMBOLS 10 Adhesive sheet for semiconductor device manufacture 20 Lead frame 30 Semiconductor element 31 Bonding wire 40 Sealing resin 50 QFN package

Claims (4)

In an adhesive sheet for manufacturing a semiconductor device, comprising a base material and a thermosetting adhesive layer provided on one surface of the base material, and releasably attached to a lead frame or a wiring board of a semiconductor device, The adhesive layer contains a carboxyl group-containing acrylonitrile-butadiene copolymer (a), an epoxy resin (b) having the following structural formula (1), and a compound (c) containing two or more maleimide groups. And the unreacted maleimide residual amount is 0.02-0.13, The adhesive sheet for semiconductor device manufacture characterized by the above-mentioned.

  The component (a) is a carboxyl group-containing acrylonitrile-butadiene copolymer having an acrylonitrile content of 5 to 50% by mass and a carboxyl group equivalent calculated from the number average molecular weight of 100 to 20000. The adhesive sheet for manufacturing a semiconductor device according to claim 1.   2. The adhesive sheet for manufacturing a semiconductor device according to claim 1, wherein the total of the component (b) and the component (c) is 30 to 300 parts by mass with respect to 100 parts by mass of the component (a). . A method for manufacturing a semiconductor device using the adhesive sheet for manufacturing a semiconductor device according to claim 1,
An adhering step of adhering an adhesive sheet for manufacturing a semiconductor device to a lead frame or a wiring board;
A die attach step of mounting a semiconductor element on the lead frame or the wiring substrate;
A wire bonding step for conducting the semiconductor element and the external connection terminal;
A sealing step of sealing the semiconductor element with a sealing resin;
A semiconductor device manufacturing method comprising: a peeling step of peeling the semiconductor device manufacturing adhesive sheet from the lead frame or the wiring board after the sealing step.

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