TW202202587A - Adhesive sheet for semiconductor device production and method for producing semiconductor device using same - Google Patents

Abstract

The present invention provides: an adhesive sheet which sufficiently and stably adheres to the back surface of a lead frame and the back surface of a sealing resin, and is not separated therefrom before a separation step even if subjected to a thermal history associated with QFN assembly, and which is free from leakage of the sealing resin, while being able to be easily separated in the separation step without the occurrence of adhesive residue, namely without leaving some adhesive behind, or without the occurrence of breakage; and a method for producing a semiconductor device, said method using this adhesive sheet. An adhesive sheet for semiconductor device production according to the present invention comprises a base material and a thermosetting adhesive layer that is provided on one surface of the base material; and this adhesive sheet for semiconductor device production is bonded to a lead frame or a wiring board of a semiconductor device in a removable manner. The adhesive layer of this adhesive sheet contains (a) a carboxyl group-containing acrylonitrile-butadiene copolymer, (b) an epoxy resin having a structural formula (1), (c) a compound containing two or more maleimide groups, and (d) a latent curing agent.

Description

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

The present invention relates to a bonding sheet suitable for use as a masking tape when assembling a semiconductor device in a QFN (Quad Flat Non-lead) manner, and a manufacturing method of a semiconductor device using the same.

Background technique In recent years, IT equipments such as mobile phones are becoming smaller, thinner and more functional. In order to meet the needs, the need for higher density mounting technology of semiconductor devices (semiconductor packages) is increasing. In terms of CSP (Chip Size Package) technology that responds to this demand, the QFN method has attracted attention (refer to Patent Document 1 and Patent Document 2), and in particular, fewer pins below 100 pins are widely used. type in the manufacture of semiconductor devices.

Here, the following methods are generally known as an assembling method of a general QFN package using the QFN method. First, in the attaching step, an adhesive sheet is attached to one side of the lead frame, and then in the die attach step, most of the semiconductor element mounting parts (die pad parts) that have been formed on the lead frame are attached. The previous one mounts semiconductor elements such as IC chips. Next, in the wire bonding step, a 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 with bonding wires. Next, in the sealing step, the semiconductor element mounted on the lead frame is sealed with a sealing resin. Then, in the peeling step, the adhesive sheet is peeled off from the lead frame, thereby forming a QFN cell in which a plurality of QFN packages are arranged. Finally, in the dicing step, the QFN unit is diced along the periphery of each QFN package, whereby most of the QFN packages can be fabricated.

The adhesive sheet used for this purpose is required to have the following characteristics: it can be attached sufficiently and stably without peeling from the back side of the lead frame and the back side of the sealing resin before the peeling step, and can be easily peeled off during the peeling step, The backside of the lead frame and the backside of the sealing resin will not have any problems such as residual adhesive residues of the adhesive residue or cracking of the adhesive sheet. In particular, in recent years, in order to reduce the cost of semiconductor devices, lead frames made of copper alloys have been increasingly used. When an adhesive sheet is used for such a lead frame composed of copper alloy, it is due to the catalytic effect of copper, which is a transition metal constituting the lead frame, on the oxidative degradation of the polymer material. Due to the thermal history accompanying the assembly of the QFN package, the adhesive of the polymer material is easy to be oxidized and deteriorated, and the problems of heavy peeling and adhesive residue are prone to occur when the adhesive sheet is peeled off from the lead frame.

Therefore, the adhesive sheets used hitherto have not sufficiently met the practical grades available for use in lead frames composed of copper alloys. For example, the conventional adhesive sheet has the following type: an adhesive layer is laminated on a base material composed of a heat-resistant film, and the adhesive layer contains acrylonitrile-butadiene copolymer and biscis Butenediimide resin (refer to Patent Document 3). When this adhesive sheet is used, the acrylonitrile-butadiene copolymer in the adhesive layer is easily deteriorated due to the heat energy applied in the die-bonding curing process, the wire bonding step and the resin sealing step after the adhesive bonding step. In the peeling step, it becomes difficult to peel off, and then the sheet is broken, and problems such as adhesive residue occur. prior art literature Patent Literature

[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 Invention The problem to be solved by the invention In view of the above-mentioned reasons, the present invention aims to provide an adhesive sheet having the following characteristics: Even if it is subjected to the thermal history accompanying QFN assembly before the peeling step in the assembly method of the QFN package, it will not It can be peeled off from the back side of the lead frame and the back side of the sealing resin, so that it can be fully and stably attached to them, and there is no leakage of the sealing resin, and it can be easily peeled off in the peeling step, and there will be no adhesive residue or cracking. . Furthermore, it is the subject of this invention to provide the manufacturing method of the semiconductor device using this adhesive sheet. means of teaching

The adhesive sheet for manufacturing a semiconductor device of the present invention is characterized in that it will be releasably attached to a lead frame or a wiring board of a semiconductor device, and has a base material and a heat-hardening sheet provided on one surface of the base material. type adhesive layer, the thermosetting adhesive layer contains carboxyl-containing acrylonitrile-butadiene copolymer (a), epoxy resin (b) having the following structural formula (1), containing two or more cis-butadiene The enediimide-based compound (c) and the latent hardener (d).

[Chemical formula 1]

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

With respect to 100 parts by mass of the carboxyl group-containing acrylonitrile-butadiene copolymer (a), the epoxy resin (b), the compound (c) containing two or more maleimide groups, and the latent The type hardener (d) is preferably 30 to 300 parts by mass in total. Furthermore, it is preferable that the said latent hardener (d) is a hardener whose reaction initiation temperature with an epoxy resin is 100 degreeC or more. In addition, the manufacturing method of the semiconductor device of the present invention is characterized by having the following steps: an attaching step of attaching the adhesive sheet for manufacturing a semiconductor device of the present invention on a lead frame or a wiring substrate; a die bonding step, which is to mount a semiconductor element on the aforementioned lead frame or wiring substrate; a wire bonding step, which is to make the aforementioned semiconductor element and external connection terminals conduct; a sealing step of sealing the aforementioned semiconductor element with a sealing resin; and A peeling process peels the adhesive sheet for semiconductor device manufacture from a lead frame or a wiring board after the said sealing process. Invention effect

According to the present invention, it is possible to provide an adhesive sheet which can be sufficiently and stably attached without peeling off from the back surface of the lead frame and the back surface of the sealing resin even if it is subjected to the thermal history accompanying the QFN assembly before the peeling step. The sealing resin leaks and can be easily peeled off in the peeling step without adhesive residue or breakage. According to the present invention, a method for manufacturing a semiconductor device using the adhesive sheet of the present invention can be further provided.

Form for carrying out the invention The present invention is described in detail as follows. [Adhesive Sheet for Semiconductor Device Manufacturing] The adhesive sheet for semiconductor device manufacturing 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. The adhesive sheet of the present invention will be releasably attached to the lead frame or wiring substrate of a semiconductor device, and the adhesive layer contains: a carboxyl group-containing acrylonitrile-butadiene copolymer (a) having the following structural formula The epoxy resin (b) of (1), the compound (c) containing two or more maleimide groups, and the latent hardener (d). The adhesive sheet of the present invention is used as a mask tape when assembling a semiconductor device by a QFN method.

[Chemical formula 2]

The carboxyl group-containing acrylonitrile-butadiene copolymer (a) (hereinafter sometimes referred to as component (a)) constituting the adhesive sheet of the present invention has a function of maintaining an appropriate melt viscosity of the adhesive layer in the initial stage of heating, and the like here At the same time, the hardened adhesive layer is given good flexibility and adhesion. By containing the copolymer, the adhesive sheet of the present invention can form an adhesive layer that has good adhesion to a base material composed of a heat-resistant film or the like and is not cracked. For the carboxyl group-containing acrylonitrile-butadiene copolymer (a), known substances can be used without limitation, but the content of acrylonitrile is preferably 5 to 50 mass %, more preferably 10 to 40 mass % . If the content of acrylonitrile is less than the above range, the solubility to the solvent and the compatibility with other components will decrease, and the uniformity of the obtained adhesive layer tends 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 and the sealing resin becomes excessive, and when it is used for an adhesive sheet, it is difficult to peel off during a peeling step, and the adhesive sheet is broken the possibility.

For the carboxyl group-containing acrylonitrile-butadiene copolymer, the carboxyl group equivalent calculated from the number average molecular weight is preferably in the range of 100 to 20,000, more preferably 200 to 10,000. If the carboxyl group equivalent is less than the above range, the reactivity with other components becomes too high, and the storage stability of the obtained adhesive layer tends to decrease. On the other hand, when the carboxyl group equivalent exceeds the above-mentioned range, the resulting adhesive layer tends to become a low B stage due to insufficient reactivity with other components. As a result, when it is used in the bonding of sheets, at the initial stage of heating, that is, during the attaching step of the bonding sheet and the die-bonding curing process, etc., when the bonding sheet is heated, the viscosity of the adhesive layer is reduced, and it is easy to bond. The agent layer causes foaming or outflow, and the thermal stability tends to decrease. The carboxyl group equivalent calculated from the number-average molecular weight means a value obtained by dividing the number-average molecular weight (Mn) by the average number of carboxyl groups (functional groups) per molecule, as shown in the following formula. Carboxyl equivalent = Mn/number of functional groups

The epoxy resin (b) (hereinafter sometimes referred to as the component (b)) and the compound (c) containing two or more maleimide groups are responsible for the thermosetting properties of the adhesive layer, and by using them together, etc. , it can form an adhesive layer with excellent thermal stability and easy to peel off in the peeling step, without adhesive residue and breakage. In particular, the epoxy resin (b) can impart toughness to the adhesive layer, and by making the adhesive layer contain this component, it is possible to suppress the adhesive residue caused by the rupture of the adhesive layer in the peeling step.

The compound (c) containing two or more maleimide groups (hereinafter also referred to as the component (c)) not only imparts thermal stability to the adhesive layer, but also adjusts the adhesiveness of the adhesive layer. By containing this component, the adhesiveness of the adhesive sheet can be appropriately controlled, and an adhesive layer that can be easily peeled off in the peeling step can be formed on the surface of the substrate. As a specific example of the compound (c) containing two or more maleimide groups, compounds constituting the bismaleimide resin can be suitably used, and examples of the following formula (2-1) ) to (2-3), among which compounds represented by the following formula (2-1) or (2-3) are particularly useful from the viewpoint of solubility in solvents.

[Chemical formula 3]

The latent curing agent (d) (hereinafter sometimes referred to as the component (d)) can adjust the adhesive layer to a lower B-stage state by being contained in the adhesive layer, so that it can be pasted at a low temperature. In addition, in the die-bonding curing step or the like, the adhesive can be rapidly cured by heating at a temperature higher than the reaction start temperature of the latent curing agent (d) contained, thereby exhibiting a state of high elastic modulus. The latent hardener (d) refers to a hardener whose reaction initiation temperature with the epoxy resin is 100°C or higher. Examples of such latent curing agents include 2-phenyl-4,5-dihydroxymethylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd., trade name: CUREZOL 2PHZ-PW, reaction initiation temperature: 150°C), 2-phenyl-4-methyl-5-hydroxymethylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd., trade name: CUREZOL 2P4MHZ-PW, reaction initiation temperature: 130° C.) and the like. Here, the reaction start temperature refers to the temperature at which the heat generation of curing is observed when mixing with the epoxy resin and raising the temperature. Measured using DSC (Differential Scanning Calorimetry). The content of the latent hardener (d) is preferably 0.05 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, relative to 100 parts by mass of the carboxyl group-containing acrylonitrile-butadiene copolymer (a). If the content of the latent hardener (d) is within the above range, the adhesive layer can be adjusted to a lower B-stage state, so the sticking can be performed at a low temperature, and the adhesive layer can be made in steps such as sticking and curing. Fast hardening.

In addition, about each component of said (a)-(d), what consists of 1 type of compound may be used for any one, and the mixture of 2 or more types of compounds may be used.

The ratio of each component is preferably 30 to 300 parts by mass, more preferably 30 to 200 parts by mass, based on 100 parts by mass of (a) component, (b) component, (c) component, and (d) component in total. If the total of the components (b), (c), and (d) is less than the above-mentioned range, the reactivity of the adhesive layer decreases, and the infusibility and infusibility of the adhesive layer are not easily performed even by heating, and the thermal stability decreases and the adhesive force increases. tendency. On the other hand, if it exceeds the above-mentioned range, the melt viscosity of the adhesive layer at the initial stage of heating is insufficient, and the adhesive layer may flow out and develop when the adhesive sheet using the adhesive layer is subjected to the sticking and curing treatment after the adhesive bonding step. Danger of bubbles.

Further, the mass ratio ((c)/(b)) of the (c) component with respect to the (b) component is preferably in the range of 0.1 to 10. If it is less than the above range, the obtained adhesive layer tends to undergo a hardening reaction at room temperature, and the storage stability is deteriorated, and the adhesive force becomes too strong, so that the adhesive sheet using the adhesive cannot be peeled off or broken in the peeling step. Yu. On the other hand, when the above-mentioned range is exceeded, the adhesiveness between the adhesive layer and the base material composed of the heat-resistant film may decrease during the production of the adhesive sheet, and the adhesive layer may foam, resulting in an adhesive sheet. Tendency to glue residue easily.

The adhesive layer in the adhesive sheet for manufacturing a semiconductor device of the present invention may further contain a reactive siloxane compound. The reactive siloxane compound can improve the compatibility of the components constituting the adhesive layer, and at the same time improve the peelability of the adhesive layer from the sealing resin. By including this compound in the adhesive layer, a uniform adhesive layer can be formed in which each component in the adhesive layer is compatible with each other and has no problems such as component separation and precipitation. As a result, the adhesive strength of the adhesive layer can be made more uniform, and defects such as a decrease in peelability and adhesive residue caused by localized high and low adhesive strength can be suppressed.

As the reactive siloxane compound, siloxane compounds imparted with reactivity through reactive groups such as amino group modification, epoxy group modification, carboxyl group modification, and mercapto group modification can be used without limitation. Among them, especially 1,3-bis(3-aminopropyl)tetramethyldisiloxane, aminopropyl-terminated dimethylsiloxane 4- or 8-mer, bis(3 -Aminophenoxymethyl)tetramethyldisiloxane is preferable in that it can react rapidly with (b) component and (c) component. The reactive siloxane compound is as described above, and it is preferable to use a siloxane structure with reactive groups bonded to both ends, but it is also possible to use only one end or one of the ends. Reactive and non-reactive silane coupling agents.

In the adhesive sheet for manufacturing a semiconductor device of the present invention, the number of reactive groups of the reactive siloxane compound in the adhesive layer is relative to the number of epoxy groups in the component (b) and the number of maleimide groups in the component (c). The total ratio is preferably 0.05 to 1.2, more preferably 0.1 to 0.8. If it is less than the above-mentioned range, the reactivity of the entire adhesive layer decreases, and it becomes difficult to carry out a hardening reaction through a die-bonding curing treatment or the like, and as a result, the adhesive force may become too strong. On the other hand, if it exceeds the above-mentioned range, the reaction is excessively advanced, problems such as gelation are likely to occur during preparation of the adhesive layer, and the adhesive force is likely to become weak.

In addition to the necessary components such as components (a) to (d), the adhesive layer may also be added with reaction accelerators such as organic peroxides and triphenylphosphine within a range that does not affect the adhesiveness of the adhesive layer. By adding them, it is also possible to control the state of the adhesive layer at normal temperature to a good B-stage. Furthermore, for the purpose of controlling melt viscosity, improving thermal conductivity, and imparting flame retardancy, a filler having an average particle size of 1 μm or less can also be added to the adhesive layer. Examples of fillers include inorganic fillers such as silica, alumina, magnesia, aluminum nitride, boron nitride, titanium oxide, calcium carbonate, and aluminum hydroxide, and organic fillers such as polysiloxane and fluororesin. When a filler is used, the content of the filler is preferably 1 to 40% by mass in the adhesive layer.

The adhesive sheet of the present invention is one in which the above-mentioned adhesive layer is formed on one side of the heat-resistant film of the base material. When manufacturing such an adhesive sheet, firstly, an adhesive coating composed of at least the following components is prepared: the carboxyl group-containing acrylonitrile-butadiene copolymer (a), the epoxy resin (b) having the above-mentioned structural formula (1) ), a compound (c) containing two or more maleimide groups, a latent hardener (d) and a solvent. Next, on one side of the heat-resistant film, the coating is applied and dried so that the thickness of the adhesive layer after drying is preferably 1-50 μm, more preferably 3-20 μm. In addition, in order to protect the adhesive layer, it is advisable to further provide a peelable protective film on the formed adhesive layer. At this time, a coating can also be applied on the protective film and dried to form an adhesive layer, and a heat-resistant film can be provided on it. The adhesive film is produced by this method. In addition, the protective film is peeled off when the adhesive sheet is used.

The heat-resistant film includes, for example, a heat-resistant film composed of polyimide, polyphenylene sulfide, polyether sulfide, polyether ether ketone, liquid crystal polymer, polyethylene terephthalate, polyethylene naphthalate, and the like. Plastic film and composite heat-resistant film such as epoxy resin-glass cloth, etc., especially polyimide is suitable. The thickness of the polyimide film is preferably 12.5-125 μm, more preferably 25-50 μm. If it is less than the above-mentioned range, the adhesive sheet tends to have insufficient toughness and is difficult to handle, and if it exceeds the above-mentioned range, the operations of the sticking step and the peeling step during QFN assembly tend to be difficult.

As for the solvent used in the adhesive coating, one or more of organic solvents such as hydrocarbons, alcohols, ketones, ethers (tetrahydrofuran, etc.), and water, etc. can be suitably used, and the usage amount only needs to be appropriately adjusted to It can be used as the appropriate viscosity of the coating. In addition, the properties of the coating material can be any of solutions, emulsions and suspensions, and can be appropriately selected according to the coating equipment used and environmental conditions.

The peelable protective film includes plastic films such as polyethylene, polypropylene, vinyl chloride, fluorine-based resin, and polysiloxane, as well as polyethylene terephthalate, polyethylene naphthalate, etc., which have been coated with polysiloxane, etc. Ester, paper, etc., which impart releasability.

[Manufacturing method of semiconductor device] The manufacturing method of a semiconductor device using the adhesive sheet of the present invention includes the following steps: an attaching step in which the adhesive sheet is attached to a lead frame or a wiring substrate; and a die bonding step in which it is mounted on the lead frame or the wiring substrate a semiconductor element; a wire bonding step of conducting the semiconductor element with an external connection terminal; a sealing step of sealing the semiconductor element with a sealing resin; and a peeling step of peeling off the lead frame or the wiring board after the sealing step Sheet.

Hereinafter, with reference to FIGS. 1-2, an example of the manufacturing method of the semiconductor device using the adhesive sheet of this invention is demonstrated. 1 is a top view of the lead frame viewed from the side on which the semiconductor element is mounted; FIGS. 2A to 2F are step diagrams showing a method for manufacturing a QFN package using the lead frame shown in FIG. 1 , which are A- A' section view.

First, a lead frame 20 having a schematic structure shown in FIG. 1 is prepared. In the lead frame 20 , a plurality of semiconductor element mounting portions (seat portions) 21 on which semiconductor elements such as IC chips are mounted are formed in a matrix, and a plurality of leads 22 (external connection terminals) are formed along the outer periphery of each semiconductor element mounting portion 21 . . The lead frame 20 can be made of conventional materials, such as copper plate and copper alloy plate, or those provided with strike plating, and nickel plating layers are sequentially arranged on the surface of the copper alloy plate. , Palladium-plated and gold-plated objects.

As shown in FIG. 2A , the adhesive sheet 10 is attached to one surface (lower surface) of the lead frame 20 so that an adhesive layer (not shown) abuts the lead frame 20 (attachment step). The method of attaching the adhesive sheet 10 to the lead frame 20 includes a lamination method, a pressing method, and the like, and from the viewpoint of productivity, a lamination method that can continuously perform the gluing process is preferable. The temperature of the adhesive sheet 10 in this step can be, for example, from 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 step, the positioning of the die bonding step and the wire bonding step will be difficult, and it will be difficult to transport to the heating furnace, which may reduce the productivity of the QFN package.

As shown in FIG. 2B , a semiconductor element 30 such as an IC chip is mounted on the side of the semiconductor element mounting portion 21 of the lead frame 20 on which the sheet 10 is not attached through a die bonder (not shown). At this time, warpage of the lead frame 20 is suppressed, and positioning can be facilitated. Next, the semiconductor element 30 is accurately placed on a predetermined position. After that, it is heated to about 100 to 200° C. to harden the die bonder, and the semiconductor element 30 is fixed and mounted on the semiconductor element mounting portion 21 (the die bonder hardening process. The above is the die bond step). At this time, the adhesive layer of the adhesive sheet 10 is hardened and attached to the lead frame.

If the outgas components generated from the bonding sheet 10 and the die attach agent adhere to the lead frame 20 and the semiconductor element 30 , the yield due to poor wire bonding is likely to occur in the wire bonding step. Therefore, after the die bonding step and before the wire bonding step, a plasma treatment (plasma cleaning step) is performed on the lead frame 20 and the semiconductor element 30 . Plasma treatment can be exemplified by the following method: in a gas atmosphere such as argon gas or a mixed gas of argon gas and hydrogen gas, the lead frame 20 (hereinafter sometimes referred to as the adhesive sheet 10 on which the semiconductor element 30 is mounted is attached) For semi-finished products) irradiate plasma. The plasma irradiation output power in the plasma treatment can be set to, for example, 150-600W. In addition, the plasma treatment time may be set to, for example, 0.1 to 15 minutes.

As shown in FIG. 2C , the semiconductor element 30 and the leads 22 (external connection terminals) of the lead frame 20 are electrically connected with bonding wires 31 such as gold wires, copper wires, and palladium-clad copper wires (wire bonding step). This step is performed while heating the semi-finished product to about 150-250° C. on a heater block. The heating time in this step can be set to, for example, 5 to 60 minutes. In the wire bonding step, if the semi-finished product is heated and the adhesive layer contains a fluorine additive, the fluorine additive will be transferred to the surface of the adhesive layer, so that the adhesive sheet 10 can be easily removed from the lead frame 20 and the sealant in the peeling step described later. The resin 40 is peeled off.

As shown in FIG. 2D , the semi-finished product shown in FIG. 2C is placed in a mold, and a sealing resin (mold) is used to inject and prefill the inside of the mold. After filling the inside of the mold with an arbitrary amount, the inside of the mold is maintained under an arbitrary pressure, and the semiconductor element 30 is sealed with the sealing resin 40 (sealing step). As a sealing resin, a conventional thing can be used, for example, the mixture of an epoxy resin, an inorganic filler, etc. is mentioned. As shown in FIG. 2E , the adhesive sheet 10 is peeled off from the sealing resin 40 and the lead frame 20 , thereby obtaining a QFN cell 60 in which a plurality of QFN packages 50 are arranged (peeling step).

As shown in FIG. 2F, the QFN cells 60 are cut along the outer periphery of each QFN package 50, thereby obtaining a plurality of QFN packages 50 (cutting step).

In addition, in the above-mentioned embodiments, the method for manufacturing a QFN package using a lead frame is described as an example, but the present invention is not limited to this, and can also be applied to a method for manufacturing a semiconductor device other than a QFN package using a lead frame and its use A method of manufacturing a semiconductor device of a wiring board.

In the adhesive sheet of the present invention, the adhesive layer exhibits a B-stage state (semi-semi hardened state), thereby enabling a low glass transition temperature (10°C to 50°C). The adhesive sheet with an adhesive layer with a low glass transition temperature can be continuously glued under a relatively low temperature heating condition, specifically, at 60~150°C using a roll laminator, etc., with excellent productivity. .

In addition, the adhesive layer with low glass transition temperature (-30°C to 50°C) in the adhesive sheet of the present invention can obtain the characteristics of high elastic modulus when heated. In recent years, for the purpose of reducing the cost of the wire bonding step, products using low-cost copper wire or palladium-clad copper wire for bonding have become popular instead of the conventional gold wire. Copper wire or palladium-clad copper wire is a metal with higher elasticity than gold. In order to make a stable shape, it needs to be processed under a higher load than the conventional gold wire. If such a large load is applied to the lead frame, if the adhesive layer of the adhesive sheet attached to the lower part of the lead frame has a low elastic modulus, the adhesive layer will be deformed, and the resin will be processed in the deformed state of the adhesive layer. seal. As a result, leakage of the sealing resin occurs from the deformed adhesive layer portion. In addition, when the adhesive sheet is peeled off from the lead frame, the adhesive layer is broken from the deformed adhesive layer portion, and there is also a problem that the adhesive remains on the surface of the lead frame. In addition, if the adhesive has a low modulus of elasticity during wire bonding, the adhesive will be deformed, making it difficult to transmit the load on the wire, and wire bonding failure is likely to occur. In the adhesive sheet of the present invention, since the adhesive layer has the characteristics of high elastic modulus as described above, even if a copper wire or a palladium-clad copper wire is used for wire bonding, poor wire bonding and leakage of the sealing resin are unlikely to occur. And problems such as residual adhesive layer.

In addition, in the adhesive sheet of the present invention, the adhesive layer has the compound (c) containing two or more maleimide groups, so during the drying process when the adhesive sheet is produced, the amount of the adhesive layer can be appropriately controlled. By curing the adhesive layer to a high B-stage state, the increase in the bonding strength to the lead frame can be suppressed. As a result, leakage of the sealing resin, remaining of the adhesive on the lead frame, and rupture of the adhesive layer during peeling can be suppressed. Example

Hereinafter, examples are shown to specifically illustrate the present invention. [Examples 1 to 4 and Comparative Examples 1 to 3] (Composition of Adhesive Coating) The components (a) to (d), the other components, and tetrahydrofuran (THF) of the solvent were mixed at the mass ratios shown in Table 1 to prepare an adhesive paint. Next, on one side of a polyimide film with a thickness of 25 μm (manufactured by DU PONT-TORAY CO., LTD., trade name Kapton 100EN), the adhesive layer was applied so that the thickness of the adhesive layer after the coating was dried was 5 μm. After the preparation, it was dried in a hot air circulation type oven set at 80° C. to obtain an adhesive sheet. In addition, the details of each ingredient used are as follows.

・Carboxyl group-containing acrylonitrile-butadiene copolymer: Carboxyl group equivalent calculated from number average molecular weight 1500, acrylonitrile content 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 285g/eq ・2-Phenyl-4,5-dihydroxymethylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd., trade name: CUREZOL 2PHZ-PW, reaction start temperature: 150°C) ・2-Phenyl-4-methyl-5-hydroxymethylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd., trade name: CUREZOL 2P4MHZ-PW, reaction start temperature: 130°C) ・2-Ethyl-4-methylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd., trade name: CUREZOL 2E4MZ, reaction start temperature: 90°C) ・2-Undecylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd., trade name: CUREZOL C11Z, reaction start temperature: 90°C)

[Table 1]

Subsequent measurements and evaluations were performed on the adhesive sheets of the above-obtained Examples and Comparative Examples, and the results are shown in Table 2.

(1) Peel strength to Cu board Attached body: Copper plate (125μm64 type made by Furukawa) Next sheet size: width 10mm x length 50mm Processing: Using a roll laminator, the adhesive sheet obtained in each example was attached to a to-be-attached body as a test body. The lamination conditions at this time were set to a temperature of 80° C., a pressure of 4 N/cm, and a pressing speed of 0.5 m/min. Storage: The adhesive sheet processed as described above was preserved under the following two conditions, and the peel strength was measured and evaluated for each adhesive sheet after storage. <Condition 1> The adhesive sheet processed as described above was stored in a thermostatic bath set at 60° C. for 120 hours. <Condition 2> After the adhesive sheet processed as described above was stored in a thermostat set at 60°C for 120 hours, it was further stored in a thermostat set at 40°C for 1 week. Measurement: Using a universal tensile testing machine, measure the 90° peel strength of the test body at room temperature. The copper plate was fixed, and the adhesive sheet was stretched in the vertical direction to measure. The stretching speed was made 50 mm/min. Evaluation: Considering the mass productivity when the peeling strength is applied by lamination, practically 15 gf/cm or more is a non-problematic adhesive strength. Let A be 15 gf/cm or more, and X be less than 15 gf/cm.

(2) Elastic modulus after heating Processing: On one side of a polyethylene terephthalate film (PET film) with a thickness of 38 μm and having been subjected to mold release treatment, the adhesive coating of each example obtained above was applied in a manner that the thickness of the adhesive layer after drying was 5 μm. Then, the adhesive sheet was obtained by drying. Next, in anticipation of a die-bonding curing process, the adhesive sheet was heated at 175° C. for 60 minutes using a ventilation oven. Measurement: The adhesive layer in the adhesive sheet after heating was peeled off from the PET film, and the tensile storage elastic modulus was measured using a DMA (Dynamic Mechanical Analyzer). DMA was measured using a VIBRON measuring device (manufactured by ORIENTEC CORPORATION, RHEOVIBRONDDV-II-EP) at a frequency of 11 Hz, a temperature increase rate of 10° C./min, and a load of 1.0 gf. Evaluation: The temperature applied during the wire bonding step is expected, and the tensile storage elastic modulus at 200°C is 6 MPa or more as A, and the tensile storage elastic modulus at 200°C is less than 6 MPa as X.

(4) Peel strength to test body after resin sealing step, presence or absence of adhesive residue after tape peeling Processing and measurement methods: (i) Preparation and heat treatment of test body After cutting the adhesive sheet with an adhesive layer on the polyimide film obtained in each example into a width of 50mm × length of 60mm, it is expected that the thermal history of QFN assembly will actually be accompanied by the following (a)~( d). (a) The adhesive sheet obtained in each example was cut into a width of 50 mm × length of 60 mm, and was attached to a test lead frame (surface 50 mm × 100 mm, 57.5 mm × 53.5 mm) made of copper alloy using a roll laminator. Bottom plating, 8 × 8 arrays, package size 5mm × 5mm, 32 pins). At this time, the lamination conditions were set to a temperature of 80° C., a pressure of 4 N/cm, and a pressing speed of 0.5 m/min. (b) The lead frame for a test made of copper alloy to which the adhesive sheet was attached was heated at 175° C./60 minutes in a ventilation oven. This is what the sticky die curing process is supposed to do. (c) Plasma irradiation treatment: 1000P manufactured by Yield Engineering Systems, Inc., Ar gas was used, and treatment was performed at 450W/60 seconds. (d) Heating at 200° C./30 minutes: Heating with a hot plate was performed in anticipation of the wire bonding step. Next, on the adhered body that has completed the heat treatment of (a) to (d), on the exposed surface of the copper material opposite to the adhered surface of the adhesive sheet, use a molding machine under the conditions of 175°C/3 minutes. Laminate a sealing resin (resin sealing step). As the sealing resin, epoxy mold resin (EME-G631BQ) manufactured by Sumitomo Bakelite Co., Ltd. was used.

(ii) Determination of peel strength, presence or absence of adhesive residue after tape peeling The 90° peel strength was measured at room temperature using a universal tensile tester with respect to the test body after the above-mentioned resin sealing step. 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 to 300 mm/min. In addition, the presence or absence of adhesive residue after the tape peeling was confirmed with an optical microscope (Digital Microscope VHX-500 manufactured by KEYENCE CORPORATION) at a magnification of 100 times. evaluate: A: The peel strength is less than 1000 gf/50 mm, the adhesive sheet after peeling is not broken, and no adhesive remains on the surface of the lead frame material and the surface of the sealing resin. B: The peeling strength is 1000 gf/50 mm or more, the adhesive sheet after peeling is not broken, and no adhesive remains on the surface of the lead frame material and the surface of the sealing resin. X: The adhesive sheet was observed to be broken, or the adhesive residue was observed on the surface of the lead frame material and the surface of the sealing resin, and at least one of the above was satisfied.

[Table 2]

As is apparent from Table 2 above, the adhesive sheets of Examples 1 to 4 exhibited peel strength to the Cu board, elastic modulus after heating, peel strength to the test body after the resin sealing step, and whether or not the adhesive tape was peeled off. All evaluations of agent residues were practically non-problematic results. On the other hand, the adhesive sheets of Comparative Example 1 and Comparative Example 2 are adhesive tapes whose adhesive strength to the Cu board is relatively low and leakage of the sealing resin is likely to occur. In addition, the adhesive sheet of Comparative Example 3 is an adhesive tape whose elastic modulus is low after heating and is prone to bond wire bonding failure in copper wire bonding, and the peel strength of the test body after the resin sealing step In the evaluation, it was firmly attached to the copper alloy test lead frame, but there was a problem that the adhesive sheet was broken. industrial availability

The adhesive sheet for manufacturing a semiconductor device of the present invention can be suitably used in a QFN package assembling method using the QFN method. By using it in the semiconductor device manufacturing method, the adhesive sheet can be easily peeled off in the peeling step of the QFN assembly process, and the adhesive residue does not occur on the adhesive sheet, nor does the adhesive sheet occur. fracture.

10: Adhesive sheet for semiconductor device manufacturing 20: Lead frame 21: Crystal seat part 22: Leads 30: Semiconductor components 31: Bonding Wire 40: Sealing resin 50: QFN package 60: QFN unit A-A': section line

FIG. 1 is a plan view showing an example of a lead frame used in a method of manufacturing a semiconductor device of the present invention. FIG. 2A is a step diagram illustrating a manufacturing method of the semiconductor device of the present invention. FIG. 2B is a step diagram illustrating a manufacturing method of the semiconductor device of the present invention. FIG. 2C is a step diagram illustrating a manufacturing method of the semiconductor device of the present invention. FIG. 2D is a step diagram illustrating a manufacturing method of the semiconductor device of the present invention. FIG. 2E is a step diagram illustrating a manufacturing method of the semiconductor device of the present invention. FIG. 2F is a step diagram illustrating a manufacturing method of the semiconductor device of the present invention.

(without)

Claims (5)

An adhesive sheet for manufacturing a semiconductor device, which is to be releasably attached to a lead frame or a wiring board of a semiconductor device, characterized by comprising: a base material; and a thermosetting adhesive layer provided on the base material On one side, it contains a carboxyl-containing acrylonitrile-butadiene copolymer (a), an epoxy resin (b) having the following structural formula (1), and an epoxy resin containing two or more maleimide groups Compound (c) and latent hardener (d); [Chemical formula 1]

. The adhesive sheet for manufacturing a semiconductor device according to claim 1, wherein the carboxyl group-containing acrylonitrile-butadiene copolymer (a) is an acrylonitrile content of 5 to 50% by mass and the carboxyl group equivalent calculated from the number average molecular weight is 100~20000 carboxyl-containing acrylonitrile-butadiene copolymer. The adhesive sheet for manufacturing a semiconductor device according to claim 1, wherein the epoxy resin (b), the epoxy resin (b), the cis-butadiene containing two or more cis-butadiene groups, relative to 100 parts by mass of the carboxyl group-containing acrylonitrile-butadiene copolymer (a) The total amount of the compound (c) of an enediimide group and the aforementioned latent curing agent (d) is 30 to 300 parts by mass. The adhesive sheet for semiconductor device manufacturing according to claim 1, wherein the latent curing agent (d) is a curing agent whose reaction initiation temperature with the epoxy resin is 100° C. or higher. A method of manufacturing a semiconductor device, comprising the following steps: an attaching step of attaching the adhesive sheet for manufacturing a semiconductor device as claimed in claim 1 on a lead frame or a wiring substrate; a die bonding step, which is to mount a semiconductor element on the aforementioned lead frame or wiring substrate; a wire bonding step, which is to make the aforementioned semiconductor element and external connection terminals conduct; a sealing step of sealing the aforementioned semiconductor element with a sealing resin; and A peeling process peels the adhesive sheet for semiconductor device manufacture from a lead frame or a wiring board after the said sealing process.

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