CN1320619C - Method for producing semiconductor and heat-resisting pressure-sensitive adhesive tape - Google Patents

Abstract

The method of manufacturing a semiconductor device of the present invention includes the steps of: placing and bonding a plurality of semiconductor chips on each die pad of a metal lead frame having an outer pad on which a heat-resistant pressure-sensitive adhesive tape is attached side edges; connecting leads are wired between each terminal of the lead frame and each electrode pad on the semiconductor chip, and each semiconductor chip is sealed in sealing resin from one side; the main body of the sealing body is cut into a plurality of separate semiconductor devices. The heat-resistant pressure-sensitive adhesive tape in the present invention comprises a base layer made of polyimide resin and a pressure-sensitive adhesive layer with a thickness of 1-20 μm, the adhesive layer is made of acrylic resin, and the It has a memory elastic modulus of 1.0×10 ⁵ Pa.

Description

Method for making semiconductor device and heat-resistant pressure-sensitive adhesive tape used therein

technical field

The present invention relates to a method of manufacturing a semiconductor device using a metal lead frame attached with a heat-resistant pressure-sensitive adhesive tape, and to a heat-resistant pressure-sensitive adhesive tape used in the method.

Background technique

In recent years, LSI packaging technology has focused on the CSP-Chip Size/Scale Package process. This process usually includes a quad flat non-lead level package (QFN-Quad Flat Non-Lead Package), whose lead terminals are placed inside the package. It is a special form that attracts attention in terms of miniaturization and high integration density. In recent years, a particularly attractive method of manufacturing QFNs involves systematically arranging a plurality of QFN chips on each die pad within the package pattern area of a lead frame; Each chip is sealed with a sealing resin, and the main body of the sealing body is cut into a plurality of separate QFN structures. This approach can significantly increase the productivity of each area of the lead frame.

In this QFN process including the step of simultaneously sealing a plurality of semiconductor chips, the injection molding die clamps only the outer portion of the resin sealing area beyond the package pattern area. Therefore, in the package pattern area, especially in its central area, the pressure from the injection die holding the outer lead surface may not be sufficient. Therefore, it may be very difficult to prevent sealing resin from leaking into the side surfaces of the outer leads, and QFN terminals and the like may be undesirably covered with resin.

To face this problem, during the QFN process, a pressure sensitive adhesive tape can be attached to the outer lead side of the lead frame. According to the self-adhesive (hiding) characteristic of the pressure-sensitive adhesive tape, such a process can be effective in obtaining a sealing effect, especially in preventing resin from leaking to the outer lead side in the resin sealing step.

In such a process, the fundamental difficulty is that the heat-resistant pressure-sensitive adhesive tape is attached after the step of mounting the semiconductor chip on the lead frame, or after the wiring connection step, during the handling process. Therefore, in a preferred manner, the heat-resistant pressure-sensitive adhesive tape is attached to the outer pad surface of the lead frame at an early stage, and then in the step of mounting the semiconductor chip, and the wiring mounted before resin sealing. They are maintained during the connection step. Thus, the heat-resistant pressure-sensitive adhesive tape should not only prevent leakage of sealing resin, but also satisfy all required characteristics such as high heat resistance in the face of mounting a semiconductor chip, and should not be used in the bonding step. Delicate and complex operations will be hindered.

If higher tack is emphasized in order to prevent resin leakage, ordinary heat-resistant pressure-sensitive adhesive layers can be selected. However, such a conventional heat-resistant pressure-sensitive adhesive tape may hinder wiring connection due to the high elasticity of such a pressure-sensitive adhesive layer. In this case, the functions required in a series of processes may be conflicted and difficult to be satisfied at the same time.

In order to solve these problems, the process of a semiconductor device proposed by the inventors uses a heat-resistant pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer having a thickness of 10 μm or less (undisclosed on the priority date of this application) Japanese Patent Application No. 2001-020395). According to this process, a series of steps including wiring connection can be performed without resin sealing.

Currently, the number of packages arranged per lead frame has increased in terms of productivity. Therefore, not only the package itself has been made smaller, but also the number of arrangements has been increased so that more packages can be sealed in one sealing portion. Therefore, the above-mentioned heat-resistant pressure-sensitive adhesive tape having a relatively thin adhesive layer for the purpose of reducing the liner may have difficulty in balancing sufficient sealing properties and other properties, and thus the prevention of resin leakage cannot be properly achieved. 1. Basic purpose.

Contents of the invention

Accordingly, it is an object of the present invention to provide a method of manufacturing a semiconductor device in which a heat-resistant pressure-sensitive adhesive tape is used in the sealing step for forming the latest fine type QFN, especially in the process of simultaneously sealing many packages in a large matrix pattern , resin leakage can be properly prevented, and the attached adhesive tape is difficult to cause trouble during a series of manufacturing steps. Also provided is a heat-resistant pressure-sensitive adhesive tape used in such a method.

The inventors have made active research on the physical properties, materials, thickness and other properties of heat-resistant pressure-sensitive adhesive tapes, and found that the above object can be achieved by using a heat-resistant pressure-sensitive adhesive tape comprising a pressure-sensitive adhesive layer, so The adhesive layer has a specific thickness, is made of acrylic resin, and has a suitable high-temperature memory elastic modulus. Based on this finding, the present invention has been accomplished.

Specifically, the present invention is directed to a method of manufacturing a semiconductor device, which at least includes the following steps: placing and bonding a plurality of semiconductor chips on each die pad of a metal lead frame, the lead frame having a an outer pad side edge of a heat-resistant pressure-sensitive adhesive tape; wiring connection leads between each terminal of the lead frame and each electrode pad on the semiconductor chip; and cutting the main body of the sealing body into a plurality of separate A semiconductor device, wherein the heat-resistant pressure-sensitive adhesive tape includes a base layer made of polyimide resin and a pressure-sensitive adhesive layer having a thickness of 1-20 μm, the adhesive layer is made of polyacrylate plastic resin, And it has a memory elastic modulus of 1.0×10 ⁵ Pa at 200°C. In the present invention, the physical properties including the memory modulus of elasticity are specifically determined by the method described below.

According to the present invention, the heat-resistant pressure-sensitive adhesive tape having a polyimide resin base layer has high heat resistance, and in addition, its linear thermal expansion coefficient is close to that of the metal lead frame. Therefore, such an adhesive tape is less likely to warp or peel off upon thermal expansion. This adhesive tape maintains a high sealing effect, so resin leakage is properly prevented during the sealing step. In addition, the polyimide resin-based layer can provide good processability as well as good handleability. The pressure-sensitive adhesive layer has a suitable high-temperature memory modulus of elasticity, so that it can always maintain a suitable cushioning effect even at its relatively large thickness of about 20 μm. In the bonding step with the attached heat-resistant pressure-sensitive adhesive tape, the loss of bonding energy can be made small, and the wiring connection can be performed well in a more reliable manner. In the latest fine QFN processes, especially large matrix pattern types with a large number of packages that are simultaneously sealed, the encapsulant must produce sufficient encapsulation to properly prevent resin leakage during the injection molding step. In this regard, the pressure-sensitive adhesive layer must have an appropriate thickness of 1 µm or more. Therefore, in the present invention, the acrylic pressure-sensitive adhesive layer with a thickness of 1-20 μm can not only provide a suitable memory elastic modulus, but also provide a suitable thickness. Therefore, in the process of manufacturing a semiconductor device of the present invention, in the sealing step using the heat-resistant pressure-sensitive adhesive tape, resin leakage can be appropriately prevented, and the attached adhesive tape is not easily attached in a series of steps. cause trouble.

The present invention is also directed to a heat-resistant pressure-sensitive adhesive tape used in such a method of manufacturing a semiconductor device, comprising: a base layer made of polyimide resin, and a pressure-sensitive adhesive layer having a thickness of 1 to 20 μm, said The adhesive layer was made of acrylic resin, and had a memory modulus of elasticity of 1.0×10 ⁵ Pa at 200°C.

The present invention is also directed to a method of using the heat-resistant pressure-sensitive adhesive tape of the present invention, comprising the steps of: attaching the heat-resistant pressure-sensitive adhesive tape to the outer pad side edge of a metal lead frame; to form a semiconductor device including a semiconductor chip and a sealing resin; wherein the semiconductor chip is sealed from one side. Wherein, the heat-resistant pressure-sensitive adhesive tape includes: a base layer made of polyimide resin, and a pressure-sensitive adhesive layer with a thickness of 1-20 μm, the adhesive layer is made of acrylic resin, and It has a memory elastic modulus of 1.0×10 ⁵ Pa at 200°C.

According to the present invention, if said heat-resistant pressure-sensitive adhesive tape is heated at 200° C. for one hour while attached to a stainless steel plate, the bond strength of the heat-resistant pressure-sensitive tape, preferably having a width of 19 mm, will preferably be 5.0 Newtons or smaller. In this case, the adhesive strength required to prevent resin leakage during the sealing step can be ensured, and after the sealing step, the adhesive tape can be easily peeled without causing damage to the sealing resin.

Description of drawings

Fig. 1 (a)-1 (e) is the schematic diagram that represents the process example of manufacturing semiconductor device of the present invention;

Fig. 2 (a)-2 (c) shows the example of the used lead frame of the present invention, wherein, Fig. 2 (a) is a front view, and Fig. 2 (b) is the enlarged schematic view of main part, and Fig. 2 (c) is to represent resin A cross-sectional view of the structure after the sealing step;

Fig. 3 is a longitudinal sectional view showing an example of the resin sealing step of the present invention.

Detailed ways

Specific embodiments of the present invention will be described below with reference to the accompanying drawings. Referring to FIGS. 1(a)-1(e), an example of the process of manufacturing a semiconductor device of the present invention is described as follows.

As shown in Fig. 1 (a)-1 (e), the method for manufacturing semiconductor device of the present invention comprises the following steps: install semiconductor chip 15; Wiring with connecting wire 16; With sealing 17 sealing and cutting the main body 21 of sealing body.

1(a) and 1(b), the mounting step includes bonding each semiconductor chip 15 on each die pad 11c of the lead frame 10, wherein a heat-resistant pressure-sensitive adhesive tape 20 is attached to the lead Outer gasket side edge of frame 10 (lower side in each figure).

For example, the lead frame 10 is made of a metal, such as copper, and has a formed QFN terminal pattern. The electrical contact portions of the lead frame 10 may be coated or plated with a metal such as silver, nickel, palladium or gold. The thickness of the lead frame 10 is usually 100-300 μm. But a thin portion formed by partial etching or the like does not have such a thickness.

The lead frame 10 preferably has a plurality of QFN patterns arranged systematically so as to be easily separated in a later cutting step. For example, referring to FIGS. 2( a ) and 2 ( b ), the structure of the lead frame 10 has multiple two-dimensional matrix patterns, called matrix QFN or MAP-QFN, which is an optimal lead frame structure. In terms of productivity, in recent years, the number of packages arranged per lead frame has increased. Thus, not only has the packaging representation been made more refined, but the number of arrangements has also been significantly increased, allowing more packages to be sealed in one sealing portion.

Referring to FIGS. 2( a ) and ( b ), the lead frame 10 has a plurality of packaging pattern areas 11 . In each region 11, a plurality of QFN package patterns are systematically arranged in which a plurality of terminal portions 11b are arranged around each adjacent opening 11a. For a general QFN, each package pattern (corresponding to each lattice area in FIG. 2(a)) includes a plurality of terminal portions 11b arranged around the opening 11a, and each terminal has an outer A lead surface, a die pad 11c disposed at the center of the opening 11a, and a die bar 11d supporting the die pad 11c from the four corners of the opening 11a.

Preferably a heat resistant pressure sensitive adhesive tape is attached at least on the outside of said encapsulation pattern area 11, and the attached area preferably includes the outer perimeter of the area to be sealed in resin. Near the side edges, the lead frame 10 typically has a plurality of lead pin holes 13 for positioning during the resin sealing step. Therefore, it is preferable to attach the adhesive tape 20 to an area not including the holes 13 . A plurality of resin sealing areas are arranged along the lengthwise direction of the lead frame 10 . Then, it is preferable to attach the pressure-sensitive adhesive tape 20 so as to extend continuously over the plurality of resin-sealed regions.

On the above lead frame 10 are mounted a plurality of semiconductor chips 15, which are silicon wafers, each of which is formed with a semiconductor integrated circuit. A plurality of mounting areas are provided on the lead frame 10 for fixing semiconductor chips 15, each of which is called a die pad 11c. The step of bonding (fixing) each semiconductor chip 15 on each die pad 11c can be realized by using any method, such as using conductive paste 19, adhesive tape, adhesive, etc. When bonding using a conductive paste, a thermosetting adhesive, etc., heat treatment is generally performed at a temperature of 150 to 200° C. for 30 to 90 minutes.

1 (c), the wiring step includes electrical connection between the end of each terminal portion 11b (each inner lead) of the lead frame 10 and each electrode pad 15a of each semiconductor chip 15. Connection line 16. For example, the connecting wire 16 is a gold wire or an aluminum wire. The bonding of the wiring is usually achieved by using a combination of ultrasonic vibration energy and contact bonding energy under heating at a temperature of 120 to 250°C. In this step, the surface of the heat-resistant pressure-sensitive adhesive tape 20 attached to the lead frame 10 may be vacuum-adsorbed so as to be held on a hot block in an adsorbed manner.

Referring to FIG. 1( d ), the sealing step includes encapsulating the semiconductor chip 15 in a sealing resin 17 from one side. A sealing step is performed to protect the semiconductor chip and the connection wires 16 mounted on the lead frame 10 . In the sealing step, a sealing resin 17, such as epoxy resin, is usually molded into the die. In this case, referring to FIG. 3, a sealing step in which a plurality of parts are simultaneously sealed in the sealing resin 17 is generally performed using a die unit 18 consisting of an upper die 18a and a lower die 18b each having a plurality of cavities. For example, resin sealing is carried out at a heating temperature of 170-180°C, which requires a few minutes of processing, and then several hours of demoulding processing. According to a preferred manner, the heat-resistant pressure-sensitive adhesive tape 20 is peeled off before the mold release process.

Referring to FIG. 1(e), the cutting step includes cutting the main body 21 of the sealing body into individual semiconductor devices 21a. In the cutting step, a rotary cutting blade such as a diamond wheel scribe is generally used to cut each cut point 17a of the sealing resin 17 .

According to the present invention, the heat-resistant pressure-sensitive adhesive tape 20 used in the above-mentioned processes includes: a base layer made of polyimide resin; and a pressure-sensitive adhesive layer having a thickness of 1-20 μm, which is made of acrylic resin , and has a memory elastic modulus of 1.0×10 ⁵ Pa at 200°C. The heat-resistant pressure-sensitive adhesive tape 20 is attached to the lead frame 10 in advance, and then subjected to heat during the above-mentioned processes. For example, in the step of die-bonding the semiconductor chip 15, heat treatment is usually performed at a temperature of about 150° C. to about 200° C. for about 30 to 90 minutes. In the wiring connection step, if a lead frame is used to form a large number of semiconductor devices, for example, at a temperature of about 120° C. to about 250° C., it may take 1 hour or more per lead frame to complete the bonding of all semiconductor devices. The resin sealing step must also adopt a temperature that sufficiently melts the resin. Such a temperature may be about 175°C. Therefore, in this case, the heat-resistant pressure-sensitive adhesive tape must satisfy a required heat resistance class.

As mentioned above, the lead frame 10 to which the heat-resistant pressure-sensitive adhesive tape is to be attached is made of a metal such as copper, so its coefficient of linear expansion is generally about 1.8×10 ^-5 -1.9×10 ^-5 / K. If the coefficient of linear expansion of the lead frame is significantly different from that of the heat-resistant pressure-sensitive adhesive tape 20 to be attached to it, the deformation caused by the difference in thermal expansion between the two when they are heated in the bonded state Warpage or peeling of the adhesive tape may result. Therefore, it is preferable to make the coefficient of linear expansion of the base layer of the heat-resistant pressure-sensitive adhesive tape close to that of the material of the lead frame.

For example, the material of this base layer is polyimide resin having a coefficient of linear expansion of about 1.5×10 ^-5 -2.8×10 ^-5 /K, which can have high processability and high operability. This material is preferably used in the present invention. The coefficient of linear expansion here is a value determined by thermo-mechanical analysis (TMA) according to ASTM D696.

Examples of films made of such polyimide resins include Kapton ^(R) (Du Pont-Toray Co., Ltd.), Upilex (trade name) (Ube Industries, Ltd.), Apical ^(R ) (Kaneka Corporation) and the like.

The thickness of the base layer of the heat-resistant pressure-sensitive adhesive tape 20 is preferably 10-100 [mu]m in terms of preventing breakage or cracking and having good handleability.

In terms of pressure-sensitive adhesive function, the adhesive layer of the heat-resistant pressure-sensitive adhesive tape 20 should have a certain degree of elasticity. But if the adhesive layer as a whole is too soft, the lead frame attached with the pressure-sensitive adhesive tape cannot be sufficiently fixed in the connection step of the connecting wire due to the elasticity of the pressure-sensitive adhesive layer. As a result, the pressurized contact bonding energy can be reduced, and failure may occur in the bonding step.

According to the present invention, in order to avoid such joint failure, ensure sufficient adhesive strength to prevent resin leakage in the sealing step, or to ensure performance different from others, the memory of the pressure-sensitive adhesive layer The modulus of elasticity should be 1.0×10 ⁵ Pa or more, preferably 5.0×10 ⁵ Pa or more, and the thickness should be 1-20 µm, preferably 5-15 µm. Such a pressure-sensitive adhesive layer as a whole can maintain light cushioning properties, making it possible to suitably realize wiring connection in a more reliable manner. Such a pressure-sensitive adhesive layer having an appropriate thickness can give sufficient sealing performance in the sealing step. The memory elastic modulus here is a shear memory elastic modulus determined by a viscoelastic spectrometer under the conditions of 1 Hz and a temperature increase rate of 5° C./min.

At any stage after the sealing step, the heat resistant pressure sensitive adhesive tape is peeled off. If the adhesive strength of the pressure-sensitive adhesive tape is too strong, it is difficult to achieve such peeling, and in some cases, the molded resin may be peeled or cracked due to the peeling stress of the adhesive tape. Therefore, a pressure-sensitive adhesive layer having an adhesive strength stronger than necessary in order to prevent overflow of the sealing resin is rather not preferred. In this regard, the adhesive strength of the pressure-sensitive adhesive tape having a width of 19 mm is preferably 5.0 Newton or less by a test according to JIS Z0237 after heating at 200° C. for 1 hour while attaching to a stainless steel sheet , and 2.0 Newtons or less is especially preferable.

A preferable example of the pressure-sensitive adhesive layer having the above-mentioned physical properties is an acrylic pressure-sensitive adhesive layer, which can easily provide a suitable memory modulus of elasticity and suitable adhesive strength. For example, such an adhesive includes an acrylic copolymer formed by copolymerizing a monomer containing at least an alkyl (meth)acrylate. Examples of the alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isopentyl (meth)acrylate, (meth) n-hexyl acrylate, (2-ethylhexyl) (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate and deca (meth)acrylate dialkyl esters.

The acrylic pressure-sensitive adhesive layer having heat resistance may include an acrylic polymer formed by copolymerizing a mixture of imide group-containing alkyl (meth)acrylate and a monomer of alkyl (meth)acrylate.

Each of these acrylic pressure sensitive adhesives contains a suitable crosslinking agent. Examples of the crosslinking agent include isocyanate crosslinking agents, epoxy crosslinking agents, ethyleneimine crosslinking agents and chelate crosslinking agents. The amount of the cross-linking agent is not particularly limited, but it is preferred that the amount of the cross-linking agent be added to produce sufficient cross-linking for the purpose of achieving the desired modulus of elasticity. For example, the amount is preferably 0.1 to 15 parts by weight; particularly preferably 1.0 to 10 parts by weight, per 100 parts by weight of the acrylic polymer.

In the present invention, by adding a relatively large amount of cross-linking agent, the memory modulus of elasticity at 200° C. can be adjusted within a desired range. In addition, for the purpose of adjusting the memory elastic modulus, the type of the crosslinking agent, the type of the monomer, the crosslinking ratio, or the molecular weight of the material can be changed; or fillers can be added.

The acrylic adhesive may contain any other components. Examples of any other components include various, such as plasticizers, fillers, pigments, dyes, antioxidants, and antistatic agents. The above-mentioned acrylic pressure-sensitive adhesive has relatively high heat resistance and can easily provide a suitable memory modulus of elasticity and suitable bond strength, so it is preferably used in the present invention. In addition, recoating including primer pretreatment of the pressure-sensitive adhesive layer or backside treatment of the base material may be performed, if desired.

As described above, the heat-resistant pressure-sensitive adhesive tape used in the method of the present invention includes a base layer and an acrylic pressure-sensitive adhesive layer. This heat-resistant pressure-sensitive adhesive tape can be attached to the lead frame in any case. Various devices and methods for heat laminator, heat roll, press roll can be used in the step of attaching the heat-resistant pressure-sensitive adhesive tape. In general, a method using a pressure roller is widely used to attach the adhesive tape in a lead frame.

example

The following examples particularly demonstrate the features and effects of the present invention.

example 1

A polyimide film (Kapton ^(R) 100H, Du Pont-Toray Co., Ltd.) having a thickness of 25 µm was used as a base material. The linear expansion coefficient of polyimide film is about 2.6×10 ^-5 -2.8×10 ^-5 /K, which is obtained by testing at a temperature increase rate of 10°C/min between 100°C and 200°C . An acrylic copolymer comprising 100 parts by weight of butyl methacrylate monomer and 5 parts by weight of methacrylic acid monomer was used. An acrylic pressure-sensitive adhesive layer was formed by adding 2 parts by weight of an epoxy crosslinking agent (Tetrad-C, Mitsubishi Gas Chemical Company, Inc.) to 100 parts by weight of this copolymer. Pressure-sensitive bonding in which an acrylic pressure-sensitive adhesive layer having a thickness of 10 µm is formed on a base material for forming a heat-resistant pressure-sensitive adhesive tape. This pressure-sensitive adhesive tape has a memory elastic modulus of 9.0×10 ⁵ Pa at 200°C, which is obtained by passing a parallel plate with a sample size of 7.9 mmφ in the shear memory elastic mode at 1 Hz and 5°C/min. It was detected by ARES (Rheometric Scientific FEL Ltd.) under the condition of temperature increase rate. The heat-resistant pressure-sensitive adhesive tape was heated at 200° C. for 1 hour while being attached to a stainless steel sheet. The adhesive tape was then tested for adhesive strength according to JIS Z0237. The bond strength measured on the adhesive tape having a width of 19 mm was 0.3 Newtons.

Heat resistant pressure sensitive adhesive tape was attached to the outer pad side of a copper lead frame with each terminal portion plated with silver and having a 4 x 4 matrix of 16 pin side QFNs. Each semiconductor chip was bonded to each die pad portion of the lead frame using epoxy phenolic silver paste and fixed by treating at 180° C. for about 1 hour.

The lead frame was then vacuum-adsorbed to one side of the heat-resistant pressure-sensitive adhesive tape so as to be fixed on a hot part heated at 200°C. The peripheral edge portion of the lead frame is also held by the crimped insert. Then, each semiconductor chip was wire-bonded with a 25 μmφ gold wire (GMG-25, Tanaka Precious Metals) in a 115 kHz connector (UTC-300 Bisuper, Shinkawa Ltd.) under the following conditions. It took about 1 hour to complete the binding.

The first bonding pressure: 80g

Ultrasonic intensity in the first bond: 550mW

The first bonding time: 10ms

Second bonding pressure: 80g

Ultrasonic intensity in the second bond: 550mW

The first bonding time: 8ms

After this, the semiconductor chip was sealed in epoxy sealing resin (HC-300, Nitto Denko Corporation) using an injection molding machine (Model-Y-series, TOWA Corporation). Molding was carried out under the following conditions: preheating at 175°C for 3 seconds, injection time for 12 seconds, and processing time for 90 seconds. The pressure sensitive adhesive tape is then peeled off. After the mold is released, for the purpose of sufficient processing, the processing is carried out at 175° C. for about 3 hours, and the main body of the sealing body is cut into each QFN type semiconductor device with a diamond wheel dicing machine.

Each of the resulting QFNs has no resin overflow, and various steps including connecting lead wires can be carried out smoothly without trouble.

Example 2

Each QFN type semiconductor device was formed using the procedure of Example 1 except that the thickness of the pressure-sensitive adhesive layer of the heat-resistant pressure-sensitive adhesive tape was 15 µm. The resulting QFN has no resin overflow, and various steps including connecting leads can be carried out smoothly without trouble.

Example 3

A heat-resistant pressure-sensitive adhesive tape was formed using the procedure of Example 1 except that the epoxy crosslinking agent was added in an amount of 0.5 parts by weight. The obtained pressure-sensitive adhesive tape had a memory modulus of elasticity at 200°C of 2.0×10 ⁵ Pa, and after heat treatment at 200°C, the adhesive strength for the pressure-sensitive adhesive tape having a width of 19 mm was about 2.5 Newton. The thickness of the pressure-sensitive adhesive layer of the adhesive tape is about 5 μm. The heat-resistant pressure-sensitive adhesive tape was then attached to the outer pad side of the copper lead frame as used in Example 1, and each semiconductor chip was bonded under the conditions described below. It was then vacuum-adsorbed from the side of the heat-resistant pressure-sensitive adhesive tape so as to be fixed on the hot part at 200°C. In addition, the peripheral portion of the lead frame is held by the crooked fitting piece. Then, each semiconductor chip was subjected to wire bonding with a 25 μmφ gold wire (GLD-25, Tanaka Precious Metals) in a 60 kHz bonder (MB-2000, Nippon Avionics Co., Ltd.) under the following conditions. It took about 1 hour to complete the binding.

The first bonding pressure: 30g

Ultrasonic intensity in the first bond: 25mW

The first bonding time: 100ms

Second bonding pressure: 200g

Ultrasonic intensity in the second bonding: 50mW

The second bonding time: 50ms

After this, the semiconductor chip was sealed in epoxy sealing resin (HC-300, Nitto Denko Corporation) using an injection molding machine (Model-Y-series, TOWA Corporation). The injection molding was carried out under the following conditions: preheating at 175°C for 40 seconds, injection time 11.5 seconds, and processing time 120 seconds. The pressure sensitive adhesive tape is then peeled off. After the mold is released, for the purpose of sufficient processing, the processing is carried out at 175° C. for about 3 hours, and the main body of the sealing body is cut into each QFN type semiconductor device with a diamond wheel dicing machine.

Each of the resulting QFNs has no resin overflow, and various steps including connecting lead wires can be carried out smoothly without trouble.

Comparative example 1

Except that the base layer of the adhesive tape is a high-density polyethylene film (with a thickness of 25 μm and a linear expansion coefficient of 15×10 ^-5 K), the process of Example 1 is adopted for the study. At the time of thermal curing in the step of mounting a semiconductor chip, significant wrinkles and partial peeling are generated in the adhesive tape. In the injection molding step, the adhesive tape cannot fundamentally suppress the overflow of the resin.

Comparative example 2

Except that the pressure-sensitive adhesive tape contains a pressure-sensitive adhesive layer of a polyester base material and a 50 μm thick silicon-based pressure-sensitive adhesive, so that the adhesive strength of the pressure-sensitive adhesive tape with a width of 19 mm after heating at 200 ° C For other than 7 Newtons, the process of Example 1 is used for research. As a result, at the time of the second bonding, most of the wirings cannot be bonded sufficiently due to the pad cushioning of the bonding tape, and bond failure frequently occurs in the bonding step. When the adhesive tape is peeled off after the sealing step, the lead frame is deformed by the stress, and part of the sealing resin is also peeled off.

Comparative example 3

Except for using a silicon-based pressure-sensitive adhesive with a memory elastic modulus of 1.1×10 ⁴ Pa at 200°C to form a pressure-sensitive adhesive layer with a thickness of 30 μm, the process of Example 1 was used for research. In the bonding step, most of the wires cannot be sufficiently bonded due to cushioning of the adhesive tape, and damage to the bond frequently occurs.

Claims (6)

1. a methods of making semiconductor devices comprises the steps:

A plurality of semiconductor chips are placed and are bonded on each die pad of die-attach area, and described lead frame has the outer pad lateral margin that is attached with heat-resisting pressure sensitive adhesive tape on it;

Wiring is connected lead-in wire between each electrode pads on each terminal of described lead frame and semiconductor chip;

The main body of seal is cut into a plurality of semiconductor device that separate;

The main body of seal is cut into each semiconductor device separately, wherein,

Described heat-resisting pressure sensitive adhesive tape comprises that basic unit and thickness that polyimide resin is made are the pressure-sensitive adhesive layer of 1-20 μ m, and this tack coat is made by acrylic resin, and has 1.0 * 10 under 200 ℃ ⁵The memory modulus of elasticity of Pa.

2. the method for claim 1, wherein if under 200 ℃ described heat-resisting pressure sensitive adhesive tape was heated 1 hour, be attached to simultaneously on the corrosion resistant plate, width is that the adhesion strength of the described heat-resisting pressure sensitive adhesive tape of 19mm will be at most 5.0 newton.

3. used heat-resisting pressure sensitive adhesive tape in claim 1 method, described heat-resisting pressure sensitive adhesive tape comprises:

The basic unit that polyimide resin is made; With

Thickness is the pressure-sensitive adhesive layer of 1-20 μ m, and this tack coat is made by acrylic resin, and has 1.0 * 10 under 200 ℃ ⁵The memory modulus of elasticity of Pa.

4. adhesive tape as claimed in claim 3 wherein, if under 200 ℃ described heat-resisting pressure sensitive adhesive tape was heated 1 hour, is attached on the corrosion resistant plate simultaneously, and width is that the adhesion strength of the described heat-resisting pressure sensitive adhesive tape of 19mm will be at most 5.0 newton.

5. a method of using heat-resisting pressure sensitive adhesive tape comprises the steps:

Described heat-resisting pressure sensitive adhesive tape is attached on the outer pad lateral margin of die-attach area;

Form semiconductor device with described lead frame, described device comprises semiconductor chip and sealing resin, and described each semiconductor chip is sealed in the described sealing resin, wherein from a side

Described heat-resisting pressure sensitive adhesive tape comprises the basic unit that polyimide resin is made; With thickness be the pressure-sensitive adhesive layer of 1-20 μ m, this tack coat is made by acrylic resin, and has 1.0 * 10 under 200 ℃ ⁵The memory modulus of elasticity of Pa.

6. method as claimed in claim 5 wherein, if under 200 ℃ described heat-resisting pressure sensitive adhesive tape was heated 1 hour, is attached on the corrosion resistant plate simultaneously, and width is that the adhesion strength of the described heat-resisting pressure sensitive adhesive tape of 19mm will be at most 5.0 newton.

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