TWI784129B - Adhesive sheet for use in semiconductor device and method for producing semiconductor device using the same - Google Patents

Abstract

The present invention provides an adhesive sheet, which sufficiently and stably adheres to a back face of a lead frame and to a back face of a sealing resin without peeling off, even in the case of receiving a heat hysteresis accompanying the QFN assembly, and is free from leakage of the sealing resin, even before a peeling step, and in addition, which can be easily peeled off in the peeling step, without causing adhesive residue in which the adhesive remains, or without breakage. In addition, the present invention also provides a method for producing a semiconductor device using the adhesive sheet. The adhesive sheet for use in producing a semiconductor device, contains a substrate and a thermosetting type of adhesive layer provided on one surface of the substrate, and is peelably adhered to a lead frame or a wiring board of the semiconductor device. In the adhesive sheet, the adhesive layer contains (a) a carboxyl group-containing acrylonitrile – butadiene copolymer, (b) an epoxy resin having the structural formula (1) described below, and (c) a compound containing two or more maleimide groups, and in the adhesive layer, the residual amount of unreacted maleimide ranges from 0.02 to 0.13.

Description

Adhesive sheet for manufacturing semiconductor device and method for manufacturing semiconductor device using same

field of invention The present invention relates to an adhesive sheet suitable for use as a mask tape when assembling semiconductor devices using a QFN (Quad Flat Non-lead) method, and a method of manufacturing a semiconductor device using the same . This application claims priority on the basis of Japanese Patent Application No. 2018-022641 filed in Japan on February 12, 2018, and its contents are incorporated herein.

Background of the invention In recent years, demands for miniaturization, thinning, and multifunctionalization of IT equipment such as mobile phones have increased the need for higher-density mounting technologies for semiconductor devices (semiconductor packages). As a CSP (Chip Size Package (chip size package)) technology to meet this demand, the QFN method has attracted attention (see Patent Document 1 and Patent Document 2), and it is widely used in low-pin-count types below 100 pins. .

Here, as a method of assembling a general QFN package based on the QFN method, roughly the following methods are known. First, in the attaching step, an adhesive sheet is attached to one surface of the lead frame. Next, in the die bonding step, IC chips etc. are mounted on the plurality of semiconductor element mounting portions (die seat portions) formed on the lead frame. semiconductor components. Then, in the wire bonding step, a plurality of leads arranged along the outer periphery of each semiconductor element mounting portion of the lead frame are electrically connected to the semiconductor element by using a bonding wire. Next, in the sealing step, the semiconductor element mounted on the lead frame is sealed with a sealing resin. Then, in the peeling step, by peeling the adhesive sheet from the lead frame, a QFN unit in which a plurality of QFN packages are arrayed can be formed. Finally, in the dicing step, multiple QFN packages can be manufactured by cutting the QFN unit along the periphery of each QFN package.

Adhesive sheets used in such applications are required to be attached sufficiently and stably without peeling off from the inner surface of the lead frame and the inner surface of the sealing resin until the peeling step, and to be easily peeled off in the peeling step , without problems such as adhesive residue remaining on the inner surface of the lead frame or the inner surface of the sealing resin, or cracking of the adhesive sheet. In particular, lead frames made of copper alloys have been used in recent years in order to reduce the cost of semiconductor devices. A lead frame made of copper alloy like this will have a catalytic effect of copper, which is a migration metal, on the oxidation and degradation of polymer materials, and will be affected by the heat history accompanying the assembly of the QFN package after the taping process , so that the adhesive is susceptible to oxidation and deterioration, and it is easy to cause heavy peeling and residual glue when peeling off the sheet.

However, conventionally used adhesive sheets do not sufficiently meet the practical grades that can be used in lead frames made of copper alloys. For example, in the known adhesive sheet, although there is a form in which an adhesive layer containing acrylonitrile-butadiene copolymer and bismaleimide resin is laminated on a base material composed of a heat-resistant film (see Patent Document 3), but when using this one, the heat applied by the die attach cure (die attach cure) treatment, wire bonding step, and resin sealing step after the adhesive step will make the acrylonitrile-butadiene copolymer Deterioration is easy, and there are problems such as becoming difficult to peel off, followed by cracking of the sheet, or generation of adhesive residue in the peeling step. prior art literature patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2003-165961 Patent Document 2: Japanese Patent Laid-Open No. 2005-142401 Patent Document 3: Japanese Patent Laid-Open No. 2008-095014

Summary of the invention The problem to be solved by the invention The present invention was made in view of the above circumstances, and its object is to provide an adhesive sheet and a method of manufacturing a semiconductor device using the adhesive sheet, even if the adhesive sheet undergoes QFN assembly until the peeling step. The thermal history will not peel off from the inner surface of the lead frame and the inner surface of the sealing resin, but it will be fully and stably attached to them, and there will be no leakage of the sealing resin, and it can be easily peeled off in the peeling step without occurrence of such problems as adhesion. Residual glue or cracks left by the agent. means to solve problems

The adhesive sheet for manufacturing semiconductor devices of the present invention has a base material and a thermosetting adhesive layer provided on one side of the base material, so as to be peelably attached to a lead frame or a wiring board of a semiconductor device; wherein the aforementioned adhesive The agent layer contains carboxyl-containing acrylonitrile-butadiene copolymer (a), epoxy resin (b) with following structural formula (1) and compound (c) containing more than 2 maleimide groups, and The residual amount of unreacted maleimide is 0.02~0.13.

[chemical formula 1]

Also, the carboxyl group-containing acrylonitrile-butadiene copolymer of the aforementioned component (a) preferably has an acrylonitrile content of 5 to 50% by mass and a carboxyl equivalent calculated from the number average molecular weight of 100 to 20,000.

The total of the aforementioned (b) component and the aforementioned (c) component is preferably 20 to 300 mass parts relative to 100 mass parts of the aforementioned (a) component. In addition, the method of manufacturing a semiconductor device of the present invention is a method of manufacturing a semiconductor device using the adhesive sheet for manufacturing a semiconductor device described above, which has the following steps: Attaching step, attaching the adhesive sheet for semiconductor device manufacturing to the lead frame or the wiring substrate; Die bonding step, mounting semiconductor elements on the aforementioned lead frame or wiring substrate; a wire bonding step, conducting the aforementioned semiconductor element and the external connection terminal; a sealing step of sealing the aforementioned semiconductor element with a sealing resin; and In the peeling step, after the aforementioned sealing step, the adhesive sheet for manufacturing a semiconductor device is peeled from the lead frame or the wiring board. Invention effect

According to the present invention, it is possible to provide an adhesive sheet and a method of manufacturing a semiconductor device using the adhesive sheet. The adhesive sheet does not escape from the lead frame even if it undergoes the heat history accompanying QFN assembly until the peeling step. The surface and the inner surface of the sealing resin are peeled off, but they are fully and stably attached to them without leakage of the sealing resin, and can be easily peeled off in the peeling step without residual glue or cracks such as adhesive residues.

form for carrying out the invention The present invention will be described in detail below. [Adhesive sheets for semiconductor device manufacturing] The adhesive sheet for manufacturing semiconductor devices of the present invention (hereinafter referred to as the adhesive sheet) has a base material and a thermosetting adhesive layer provided on one side of the base material for detachable attachment to a lead frame or a semiconductor device. Wiring substrate; wherein the aforementioned adhesive layer contains carboxyl group-containing acrylonitrile-butadiene copolymer (a), epoxy resin (b) with the following structural formula (1) and a resin containing two or more maleimide groups compound (c), and the residual amount of unreacted maleimide is 0.02~0.13, the adhesive sheet is used as a mask tape when semiconductor devices are assembled by QFN method.

[chemical formula 2]

The carboxyl group-containing acrylonitrile-butadiene copolymer (a) not only plays the role of maintaining the melt viscosity of the adhesive layer appropriately at the initial stage of heating, but also imparts good flexibility and adhesiveness to the hardened adhesive layer , By containing this component, 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 is not damaged. 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, more preferably 10 to 40% by mass. If the content of acrylonitrile is less than the above range, the solubility to the solvent or compatibility with other components will decrease, so the uniformity of the obtained adhesive layer will tend to decrease. On the other hand, if the content of acrylonitrile exceeds the above-mentioned range, the adhesiveness of the obtained adhesive layer to the lead frame or sealing resin will become excessive, and when the adhesive layer is used for an adhesive sheet, there will be problems such as becoming weak in the peeling step. It is difficult to peel off, or there is a possibility that the sheet may be broken.

The carboxyl equivalent of the carboxyl group-containing acrylonitrile-butadiene copolymer calculated from the number average molecular weight is preferably in the range of 100 to 20,000, more preferably 200 to 10,000. When the carboxyl group equivalent is less than the above-mentioned range, the reactivity with other components will become too high, and the storage stability of the obtained adhesive agent layer will tend to fall. On the other hand, if the carboxyl equivalent exceeds the above-mentioned range, the reactivity with other components will be insufficient, so the obtained adhesive layer will easily become a low B-stage (B-stage (semi-cured stage)). As a result, when it is used to bond the sheet, at the initial stage of heating, that is, when the bonding step of the bonding sheet or the die-bonding solidification treatment, etc., when the bonding sheet has been heated, the adhesive layer will have a low viscosity, and it is easy to If the adhesive layer foams or overflows, etc., thermal stability tends to decrease. In addition, the carboxyl equivalent calculated from the number average molecular weight is obtained by dividing the number average molecular weight (Mn) by the number of carboxyl groups (functional group number) per molecule, and is represented by the following formula. Carboxyl equivalent = Mn/functional group number

The epoxy resin (b) and the compound (c) containing two or more maleimide groups are responsible for the thermosetting properties of the adhesive layer. By using them in combination, it is possible to form a The peeling step enables easy peeling without residue or cracked adhesive layers. In particular, the epoxy resin (b) imparts toughness to the adhesive layer, and by containing this component, it is possible to suppress adhesive residue due to damage of the adhesive layer in the peeling step.

The compound (c) containing two or more maleimide groups not only imparts thermal stability to the adhesive layer but also plays a role in adjusting the adhesiveness of the adhesive layer. By containing this compound, an adhesive layer can be formed. Adhesive layer that is moderately controlled in properties and can be easily peeled off in the peeling step. Specific examples of the compound (c) containing two or more maleimide groups are preferably compounds that constitute bismaleimide resins, such as compounds of the following formulas (2-1) to (2-3), etc. , but the compound represented by the following formula (2-1) or (2-3) is useful in terms of solubility in solvents.

[chemical formula 3]

In addition, for each of the aforementioned components (a) to (c), a single compound may be used, or a mixture of two or more compounds may be used.

In the adhesive layer of the adhesive sheet for manufacturing semiconductor devices of the present invention, the residual amount of unreacted maleimide must be 0.02-0.13. In particular, the residual amount of unreacted maleimide should be 0.02~0.10. When the residual amount of unreacted maleimide is less than 0.02, the initial bonding strength to the lead frame is low, and unbonded parts may be generated during lamination. On the other hand, if it is higher than 0.13, the initial bonding strength to the lead frame will become high, and as a result, the de-taping property after package assembly will be deteriorated (high peel strength; adhesive residue/glue will easily occur) membrane rupture). In order to change the residual amount of unreacted maleimide to 0.02~0.13, it can be obtained by properly controlling the hardening during the drying process during the manufacture of the adhesive layer. The residual amount of unreacted maleimide can be obtained by analyzing the results of the adhesive layer measured by FT-IR spectroscopy (Fourier Transform Infrared Spectroscopy). The residual amount of unreacted maleimide can be determined by using the ratio of the integral value of the maleimide peak (1148cm ^-1 ) of FT-IR to the integral value of the aromatic ring peak (1500cm ^-1 ) of maleimide (S1148/S1500) to calculate. About the analysis method of the residual amount of unreacted maleimide, the details are described in the evaluation results of the examples.

The ratio of each of the aforementioned components is preferably 20 to 300 parts by mass, more preferably 20 to 200 parts by mass, of the total of components (b) and (c) relative to 100 parts by mass of component (a). If the total of the components (b) and (c) is less than the above range, the reactivity of the adhesive layer will decrease, and it will be difficult to perform insolubility or melting even by heating, and the adhesive force will be reduced due to the decrease in thermal stability. tendency to become stronger. On the other hand, once the above-mentioned range is exceeded, the melt viscosity of the adhesive layer at the initial stage of heating will be insufficient, and as far as the adhesive sheet using the adhesive layer is concerned, there may be problems in the die-bonding solidification treatment after the gluing step, etc. There is a risk of the adhesive layer flowing out or foaming.

Moreover, it is preferable that the mass ratio ((c)/(b)) of (c) component with respect to (b) component exists in the range of 0.1-10. If it is less than the above-mentioned range, the obtained adhesive layer may easily undergo a hardening reaction at room temperature and the storage stability may become insufficient; or the adhesive force may become too strong, and the adhesive sheet using the adhesive layer may In the peeling step, there is a possibility that it becomes impossible to peel or breaks. On the other hand, if it exceeds the above range, when the adhesive sheet is manufactured, the adhesiveness with the base material composed of the adhesive layer and the heat-resistant film may decrease; or the adhesive layer may foam or The resulting adhesive sheet tends to be prone to adhesive residue.

The adhesive layer of the adhesive sheet for manufacturing semiconductor devices of the present invention can contain a reactive siloxane compound. The reactive siloxane compound is used to improve the compatibility of the components constituting the adhesive layer and to improve the peelability of the adhesive layer from the sealing resin. By containing this compound, a good compatibility between the components can be formed. A uniform adhesive layer that dissolves and has no adverse conditions such as component separation and precipitation. As a result, the adhesive layer will have a uniform adhesive strength, and can suppress adverse conditions such as reduced peelability and residual adhesive caused by local high adhesive strength. As the reactive siloxane compound, siloxane compounds that have been given reactivity by reactive groups such as amino group modification, epoxy modification, carboxyl modification, and mercapto group modification can be used without limitation. Among these, 1,3-bis(3-aminopropyl)tetramethyldisilazine is ideal in terms of the rapid reaction with components (b) and (c). Oxane, aminopropyl-terminated dimethylsiloxane 4-mer or 8-mer, bis(3-aminophenoxymethyl)tetramethyldisiloxane. From the viewpoint of reactivity, it is preferable to use a compound having reactive groups bonded to both ends of the siloxane structure as the reactive siloxane compound, but one having a reactive group bonded to one end, or one of the ends may also be used. A silane coupling agent in which one is reactive and the other is non-reactive.

In the adhesive layer of the adhesive sheet for manufacturing semiconductor devices of the present invention, the number of reactive groups of the reactive siloxane compound is the sum of the number of epoxy groups of component (b) and the number of maleimide groups of component (c) The ratio of should be 0.05~1.2, more preferably 0.1~0.8. If it is less than the above-mentioned range, the reactivity of the adhesive layer as a whole may decrease, and the hardening reaction may become difficult to proceed during die-bonding curing treatment, etc., resulting in an excessively strong adhesive force. On the other hand, once the above range is exceeded, the reaction will proceed excessively, and problems such as gelation will easily occur when preparing the adhesive layer, and the adhesive force will easily become weak.

In the adhesive layer, in addition to the necessary components (a) to (c), reaction accelerators such as organic peroxides, imidazoles, and triphenylphosphine can also be added. By these additions, the state of the adhesive layer at room temperature can be controlled to a good B-stage. Furthermore, fillers having an average particle diameter of 1 μm or less may be added for the purpose of controlling melt viscosity, improving thermal conductivity, imparting flame retardancy, and the like. Examples of the filler include inorganic fillers such as silicon oxide, aluminum oxide, magnesium oxide, aluminum nitride, boron nitride, titanium oxide, calcium carbonate, and aluminum hydroxide, and organic fillers such as silicone resin and fluororesin. When fillers are used, their content in the adhesive layer should be set at 1-40% by mass.

The adhesive sheet of the present invention is one in which the aforementioned adhesive layer is formed on one side of a heat-resistant film as a base material. When making this kind of adhesive sheet, at first to prepare the adhesive coating, the adhesive coating is at least composed of the aforementioned carboxyl-containing acrylonitrile-butadiene copolymer (a), the epoxy resin with the aforementioned structural formula (1) ( b) A compound (c) containing two or more maleimide groups, a reactive siloxane compound and a solvent as required. Next, apply the paint on one side of the heat-resistant film so that the thickness of the adhesive layer after drying is preferably 1-50 μm, more preferably 3-20 μm, and then dry. Also, in order to protect the adhesive layer, it is advisable to further set a peelable protective film on the formed adhesive layer. In this case, the following method can also be used to manufacture the adhesive sheet: apply paint on the protective film and dry it. An adhesive layer is formed, and a heat-resistant film is placed thereon. In addition, the protective film is to be peeled off when the sheet is used.

Examples of heat-resistant films include heat-resistant films made of polyimide, polyphenylene sulfide, polyethersulfone, polyether ether ketone, liquid crystal polymer, polyethylene terephthalate, polyethylene naphthalate, etc. Plastic films, composite heat-resistant films such as epoxy resin-glass fiber cloth, etc., but polyimide films are especially preferred. The thickness of the polyimide film is preferably 12.5-125 μm, more preferably 25-50 μm. If it is less than the above range, the toughness of the adhesive sheet will tend to be insufficient and handling will tend to become difficult; if it exceeds the above range, it will tend to be difficult to perform the gluing step or the peeling step during QFN assembly.

The solvent used in the adhesive paint can be suitably used at least one of organic solvents such as hydrocarbons, alcohols, ketones, ethers (tetrahydrofuran, etc.), and water, and the amount used should be properly adjusted to make it into a paint Appropriate viscosity is enough. In addition, the properties of the coating material may be any of solution, emulsion, and suspension, and only need to be appropriately selected according to the coating equipment used, environmental conditions, and the like.

Examples of peelable protective films include plastic films such as polyethylene, polypropylene, vinyl chloride, fluorine-based resins, and silicone, or polyethylene terephthalate, polyethylene naphthalate, paper etc. are coated with polysiloxane, etc. to give peelability.

[Manufacturing method of semiconductor device] The method of manufacturing a semiconductor device using the adhesive sheet of the present invention is a method comprising the following steps: an attaching step, attaching an adhesive sheet to a lead frame or a wiring substrate; a die bonding step, mounting a semiconductor on a lead frame or a wiring substrate element; a wire bonding step of conducting conduction between the semiconductor element and an external connection terminal; a sealing step of sealing the semiconductor element with a sealing resin; and a peeling step of peeling the adhesive sheet from the lead frame or the wiring substrate after the sealing step.

Hereinafter, an example of a method of manufacturing a semiconductor device using the adhesive sheet of the present invention will be described with reference to FIGS. 1 to 2 . Figure 1 is a top view of the lead frame seen from the side where the semiconductor element is mounted; Figure 2(a)~(f) is a flow chart showing the method of manufacturing a QFN package using the lead frame shown in Figure 1, and is the lead frame of Figure 1 The A-A' profile.

First, a lead frame 20 having a schematic configuration shown in FIG. 1 is prepared. The lead frame 20 is formed in an array with a plurality of semiconductor element mounting parts (die pads) 21 on which semiconductor elements such as IC chips are mounted, and a plurality of leads 22 (external connection parts) are formed along the outer circumference of each semiconductor element mounting part 21. terminal). The material of the lead frame 20 can be a well-known thing in the past, such as a copper plate and a copper alloy plate, or a strike plating is provided on them, or a nickel plating layer, a palladium plating layer, and a copper alloy plate are sequentially provided on the surface of the copper alloy plate. Gold plated ones.

As shown in FIG. 2( a ), on one side (lower side) of the lead frame 20 , the adhesive sheet 10 is attached so that the adhesive layer (not shown) is closely attached to the lead frame 20 (attaching step). The method of attaching the adhesive sheet 10 to the lead frame 20 includes a lamination method, a pressing method, etc., but from the viewpoint of productivity, the lamination method that can continuously carry out the adhesive bonding step is preferable. The temperature of the adhesive sheet 10 in this step is, for example, from normal temperature (5-35°C) to 150°C, preferably 60-120°C. If it is attached at a temperature higher than 150°C, it is easy to warp the lead frame. In this step, if the lead frame 20 is warped, the positioning in the die bonding step or the wire bonding step may become difficult, or the transportation to the heating furnace may become difficult, and the production of the QFN package may be affected. Risk of sexual decline.

As shown in FIG. 2( b ), on the side of the semiconductor element mounting portion 21 of the lead frame 20 to which the adhesive sheet 10 is not attached, semiconductor elements 30 such as IC chips are placed through a die-bonding agent (not shown). At this time, the lead frame 20 is easily positioned because warping is suppressed. And the semiconductor element 30 will be correctly placed on the predetermined position. Thereafter, it is heated to about 100-200° C. to harden the die-bonding agent, and the semiconductor element 30 is fixed and mounted on the semiconductor element mounting portion 21 (die-bonding agent hardening treatment. The above is the die-bonding step). At this time, the adhesive layer attached to the sheet 10 will harden and be attached to the lead frame.

Once the outgassing components generated from the adhesive sheet 10 or the die-bonding agent adhere to the lead frame 20 or the semiconductor device 30 , it is easy to cause yield reduction due to defective wire bonding in the wire bonding step. Therefore, plasma treatment (plasma cleaning step) is performed on the lead frame 20 or the semiconductor element 30 after the die bonding step and before the wire bonding step. The plasma treatment can be, for example, irradiating the lead frame 20 (hereinafter sometimes referred to as a semi-finished product) with the adhesive sheet 10 attached thereon and the semiconductor element 30 mounted thereon in a gas atmosphere such as argon gas or a mixed gas of argon gas and hydrogen gas. Methods. The plasma irradiation output power during plasma treatment is set to 150~600W, for example. In addition, the time of the plasma treatment is, for example, 0.1 to 15 minutes.

As shown in FIG. 2( c ), use bonding wires 31 such as gold wires, copper wires, and palladium-clad copper wires to electrically connect the semiconductor element 30 and the lead wires 22 (external connection terminals) of the lead frame 20 (wire bonding step). This step is carried out while heating the semi-finished product to about 150~250°C on the heater assembly. The heating time in this step is, for example, 5 to 60 minutes. If the semi-finished product is heated in the wire bonding step, in the case where the adhesive layer contains a fluorine additive, the fluorine additive will move to the surface of the adhesive layer, so the adhesive sheet 10 will be easily removed from the adhesive sheet 10 in the peeling step described later. The lead frame 20 and the sealing resin 40 are peeled off.

As shown in Figure 2(d), the semi-finished product shown in Figure 2(c) is placed in the mold, and the sealing resin (molding material) is injected into the mold for filling. After filling an arbitrary amount in 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 step). A well-known thing can be used as a sealing resin, For example, the mixture of an epoxy resin and an inorganic filler etc. is mentioned. As shown in FIG. 2( e ), by peeling the adhesive sheet 10 from the sealing resin 40 and the lead frame 20 , a QFN cell 60 in which a plurality of QFN packages 50 are arrayed is obtained (peeling step).

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

In addition, in the foregoing embodiment, the method of manufacturing a QFN package using a lead frame was described as an example, but the present invention is not limited thereto, and can be applied to semiconductor devices other than the QFN package using a lead frame. and a method of manufacturing a semiconductor device using a wiring board.

The adhesive layer in the adhesive sheet of the present invention can be obtained by cross-linking the carboxyl group of the carboxyl-containing acrylonitrile-butadiene copolymer (a) with the glycidyl group of the epoxy resin (b) to obtain the B-stage state (semi-hardened state), and make it a low glass transition temperature (-30 ° C ~ 50 ° C). The adhesive sheet with the adhesive layer of low glass transition temperature can be heated continuously at a relatively low temperature, specifically at room temperature (5°C~35°C)~150°C using a roll laminator or the like. Excellent productivity due to glue application step.

In addition, the adhesive layer with a low glass transition temperature (-30°C~50°C) in the adhesive sheet of the present invention can obtain the characteristic of high elastic modulus when heated. In recent years, for the purpose of reducing the cost of the wire bonding process, products using low-cost copper wires or palladium-clad copper wires instead of conventional gold wires for bonding have become popular. Since copper wire or palladium-clad copper wire is a metal with higher elasticity than gold, in order to produce a stable shape, it must be processed under a higher load than conventional gold wire. If such a large load is applied to the lead frame, once the adhesive layer in the adhesive sheet attached to the lower part of the lead frame has a low modulus of elasticity, the adhesive layer will be deformed and the deformed adhesive layer will The state is sealed with resin. As a result, the sealing resin partially leaks from the deformed adhesive layer. In addition, when the adhesive sheet is peeled off from the lead frame, the adhesive layer is cracked from the deformed adhesive layer portion and the adhesive remains on the surface of the lead frame. Furthermore, once the adhesive has a low modulus of elasticity during wire bonding, it will be difficult to transmit the wire load due to the deformation of the adhesive, and it will also become prone to poor wire bonding. The adhesive layer in the adhesive sheet of the present invention has the characteristics of high elastic modulus as mentioned above, so even if copper wire or palladium-clad copper wire is used for wire bonding, it is difficult to cause poor wire bonding and sealing resin leakage. Leakage or residual adhesive layer problems.

Also, in the adhesive layer of the adhesive sheet of the present invention, since the compound (c) containing two or more maleimide groups is contained, the residual amount of unreacted maleimide resin is kept within a specific range , so that the adhesive layer can be made into a high B-stage state, therefore, it is possible to suppress its bonding strength to the lead frame from becoming high, and as a result, it is possible to suppress the leakage of the sealing resin, the adhesive remaining on the lead frame, and the adhesive layer when peeling off of rupture. Example

The embodiments disclosed in the present invention will be described in detail below. [Examples 1-4 and Comparative Examples 1-3] (composition of adhesive coating) Adhesive paint was prepared by mixing components (a) to (c) and other components with tetrahydrofuran (THF) as a solvent in the mass ratio shown in Table 1. Next, this adhesive coating was applied to one side of a polyimide film (manufactured by DU PONT-TORAY CO., LTD., trade name Kapton 100EN) with a thickness of 25 μm so that the thickness of the adhesive layer after drying was 5 μm. Then, according to the drying conditions shown in Table 1, it was dried in a hot air circulation oven to obtain an adhesive sheet. In addition, the breakdown of each component used is as follows.

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

[Table 1]

The following measurements and evaluations were performed on the adhesive sheets obtained in each example as described above, and the results are shown in Table 2. (1) Residual amount of unreacted maleimide The residual amount of maleimide in the adhesive sheet is measured using FT-IR (Spectrum 100 manufactured by PerkinElmer) and the ATR (Attenuated Total Reflection (attenuated total reflection)) method Determination. The calculation method of the remaining amount of maleimide in the adhesive sheet is shown below. (i) Measurement: After ATR correction and absorbance conversion, calculate the peak areas of the following wavenumbers S1 and S2. S1=Integral value of maleimide peak (1148cm ^-1 ) S2=Integral value of maleimide aromatic ring peak (1500cm ^-1 ) (ii) The ratio of S1/S2 is unreacted maleimide residues.

(2) Peel strength to Cu plate Adherent: copper plate (Furukawa 125μm 7025 type) Next sheet size: width 10mm x length 50mm Processing: Use a roll laminating machine to stick the adhesive sheet obtained in each case to the adherend as a test body. The lamination conditions at this time were a temperature of 80° C., a pressure of 4 N/cm, and a pressing speed of 1 m/min. Measurement: Use a universal tensile testing machine to measure the 90° peel strength of the test body at room temperature. And fix the copper plate, and then stretch the sheet in the vertical direction for measurement. The stretching speed was set at 50 mm/min. Evaluation: The peel strength is practically 5gf/cm or more and there is no problem with the adhesive strength. On the other hand, 5 gf/cm or more was rated as ◯, and less than 5 gf/cm was rated as x.

(3) Thermal characteristics after die bonding step Processing: For the adhesive sheets obtained in each example, a polyimide film with a thickness of 25 μm was made into a release-treated polyethylene terephthalate film (PET film) with a thickness of 38 μm, and To simulate the die-bonding curing process, heat at 175°C for 1 hour in a ventilated oven. Measurement: The adhesive layer of the adhesive sheet after heating was taken out from the PET film, and the tensile storage elastic modulus was measured using DMA (Dynamic Mechanical Analyzer). DMA was measured at a frequency of 11 Hz, a heating rate of 10° C./min, and a load of 1.0 gf using a Vibron measuring device (manufactured by Orientec, RHEOVIBRON DDV-II-EP). Evaluation: The temperature used in the wire bonding step was simulated, and those whose tensile storage elastic modulus at 200° C. was 10 MPa or more were rated as ◯.

(4) The peel strength of the test body after the resin sealing step, and the presence or absence of adhesive residue after the film is peeled off Processing • Measuring method: (i) Fabrication and heat treatment of test body After cutting the adhesive sheet obtained in each example into a width of 50 mm x a length of 60 mm, the thermal history accompanying the actual QFN assembly was simulated, and the following (a) to (d) were first implemented in sequence. (a) Cut the adhesive sheet obtained in each example into a width of 50mm x length of 60mm, and use a roll laminating machine to paste it on a test lead frame made of copper alloy with a size of 57.5mm x 53.5mm (surface Shock plating, 8×8 array configuration, package size 5mm×5mm, 32 pins). The lamination conditions at this time were a temperature of 80° C., a pressure of 4 N/cm, and a pressing speed of 1 m/min. (b) Heat the test lead frame made of copper alloy to which the adhesive sheet has been attached in a ventilated oven at 175° C. for 1 hour. This is a treatment for simulating die-bonding solidification. (c) Plasma irradiation treatment: 1000P manufactured by Yield Engineering Co., Ltd. was used, and the gas type was Ar, and the treatment was performed at 450W/60 seconds. (d) Heating at 200°C/30 minutes: for simulating the process of wire bonding, and using a heating plate to heat. Next, use a molding machine to laminate sealing resin at 175°C/3 minutes on the exposed surface of the copper material opposite to the surface on which the adhesive sheet has been pasted in the adherend that has completed the heat treatment of (a)~(d) (resin sealing step). As the sealing resin, epoxy molding resin (EME-G631BQ) manufactured by Sumitomo Bakelite Co., Ltd. was used.

(ii) Determination of peel strength, whether there is adhesive residue after peeling off the film The 90° peel strength was measured at room temperature for the test body after the aforementioned resin sealing step using a universal tensile testing machine. In addition, the test body was fixed, and the corner portion of the adhesive sheet was stretched in the vertical direction for measurement. The stretching speed was set at 300 mm/min. Also, using an optical microscope (digital microscope VHX-500 manufactured by KEYENCE CORPORATION), at a magnification of 100 times, it was checked whether there was any adhesive residue after the adhesive film was peeled off. ○: The peel strength is less than 1000gf/50mm, the peeled adhesive sheet is not broken, and there is no adhesive residue on the surface of the lead frame material and the surface of the sealing resin. △: The peeling strength is more than 1000gf/50mm, the peeled adhesive sheet is not broken, and there is no adhesive residue on the surface of the lead frame material and the surface of the sealing resin. ×: Cracks in the adhesive sheet can be seen, or adhesive residues can be seen on the surface of the lead frame material and the surface of the sealing resin, at least any of the above.

(5) Whether there is resin leakage Using an optical microscope (digital microscope VHX-500 manufactured by KEYENCE CORPORATION), at a magnification of 100 times, the presence or absence of sealing resin leakage was confirmed for the test body after the aforementioned resin sealing step. ○: No sealing resin leaked from the surface of the lead frame material for the resin sealing test after the adhesive sheet was peeled off.

[Table 2]

It can be seen from the aforementioned Table 2 that the peeling strength of the adhesive sheets of Examples 1 to 4 to the Cu plate, the thermal characteristics after the die bonding step, the peeling strength of the test body after the resin sealing step, and the presence or absence of adhesion after the adhesive film is peeled off. In all the evaluations of agent residue and resin leakage, the evaluation results showed that there was no practical problem. On the other hand, the adhesive sheets of Comparative Example 1 and Comparative Example 2 had a problem that they could not be attached to the test lead frame made of copper alloy in the evaluation of the peel strength of the test body after the resin sealing step. Also, the adhesive sheet of Comparative Example 3 was firmly attached to the test lead frame made of copper alloy in the evaluation of the peel strength of the test body after the resin sealing step, but there was a problem that the adhesive sheet was broken.

10‧‧‧Adhesive sheet for semiconductor device manufacturing 20‧‧‧lead frame 21‧‧‧Semiconductor element mounting part (die seat part) 22‧‧‧lead 30‧‧‧Semiconductor components 31‧‧‧Joint wire 40‧‧‧Sealing resin 50‧‧‧QFN package 60‧‧‧QFN unit A-A’‧‧‧hatching

FIG. 1 is a plan view showing an example of a lead frame used in the method of manufacturing a semiconductor device of the present invention. FIG. 2 is a flowchart illustrating a method of manufacturing a semiconductor device of the present invention.

(none)

Claims (4)

An adhesive sheet for manufacturing semiconductor devices, comprising a base material and a thermosetting adhesive layer disposed on one side of the base material, for detachable attachment to a lead frame or a wiring substrate of a semiconductor device; wherein the adhesive layer Contains carboxyl-containing acrylonitrile-butadiene copolymer (a), epoxy resin (b) with the following structural formula (1) and compound (c) containing two or more maleimide groups, and is unreacted The residual amount of maleimide is 0.02~0.13; [chemical formula 1]

. The adhesive sheet for manufacturing semiconductor devices as claimed in claim 1, wherein the carboxyl group-containing acrylonitrile-butadiene copolymer of the aforementioned component (a) has an acrylonitrile content of 5 to 50% by mass and a carboxyl equivalent calculated from the number average molecular weight 100~20000. The adhesive sheet for semiconductor device manufacture according to claim 1, wherein the total of the aforementioned component (b) and the aforementioned component (c) is 20 to 300 parts by mass relative to 100 parts by mass of the aforementioned component (a). A method of manufacturing a semiconductor device, which is a method of manufacturing a semiconductor device using the adhesive sheet for semiconductor device manufacturing according to claim 1, which has the following steps: Attaching step, attaching the adhesive sheet for semiconductor device manufacturing to the lead frame or the wiring substrate; Die bonding step, mounting semiconductor elements on the aforementioned lead frame or wiring substrate; a wire bonding step, conducting the aforementioned semiconductor element and the external connection terminal; a sealing step of sealing the aforementioned semiconductor element with a sealing resin; and In the peeling step, after the aforementioned sealing step, the adhesive sheet for semiconductor device manufacture is peeled off from the lead frame or the wiring board.

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