JPH06127518A - Resin encapsulation method for semiconductor device - Google Patents

Abstract

(57) [Abstract] [Purpose] It is an object of the present invention to provide a resin sealing method for a semiconductor device, which can be applied to a semiconductor device having a large chip size, and to manufacture a thin semiconductor device. A TAB tape having a perforated portion in a central portion, a semiconductor chip disposed in the perforated portion, and an inner lead fixedly formed on the TAB tape and electrically connected to the semiconductor chip are provided. A method for encapsulating a semiconductor device, comprising a TAB tape 14 having a semiconductor chip mounted thereon, and an encapsulating sheet 15 composed of a thin film of a semi-curable curable resin or a thermoplastic resin on at least the side where the inner leads are provided. It is characterized in that they are superposed in a reduced pressure atmosphere and pressed by utilizing the expansion of the elastic film-like material 11 on the heat block 13 due to the air pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for sealing a semiconductor device.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor device, a semiconductor chip mounted on a lead frame is bonded to an inner lead portion by wire bonding, and the whole is resin-sealed with a resin molding material by transfer molding. There is. FIG. 4 shows the state, and the whole is sealed with the resin molding material 30. Recently, there has been a demand for a semiconductor device that is thin and has a high packing density. Therefore, a TAB (tape automated bond)
Ding) method is used to deal with the increase in the number of pins of the inner lead. That is, in this type of thin semiconductor device, a copper foil is adhered and fixed to a TAB tape formed by punching a space for mounting a semiconductor chip, and a circuit made of the copper foil is formed by forming a photoresist and etching. It is formed by forming a solder resist on the circuit portion, electrically connecting the inner lead of the circuit and the semiconductor chip, and sealing the resin with a liquid molding material. At this time, the epoxy resin / curing agent type liquid molding material is dropped by a dispenser and then heat-cured to perform resin sealing. FIG. 7 is a cross-sectional view of a conventional thin semiconductor device using a TAB tape, showing a state of being sealed with a liquid molding material. That is, adhered to the TAB tape 31,
A solder resist 34 is provided on the lead 33 formed of a fixed copper foil, the inner lead portion and the semiconductor chip 32 are electrically joined, and a resin sealing portion using a liquid molding material 35 thereon. Are formed.

[0003]

However, the conventional resin-encapsulated semiconductor device has a large thickness and does not sufficiently satisfy the demand for thinning. In the case of the semiconductor device using the TAB tape shown in FIG. 7, the thickness can be made smaller than in the case of FIG. 6, but there is a problem that the resin cannot be quantitatively determined and the film thickness is difficult to control. There is a problem that a step of providing a solder resist is required. Recent resin-encapsulated semiconductors tend to have a larger chip size due to demands for higher power, larger capacity, and the like. However, with the increase in chip size, conventional encapsulation methods for encapsulating semiconductor devices with resin are affected by surface tension and have insufficient flatness in the shape after curing. There is also a problem in that the semiconductor device after encapsulation is distorted due to the difference in thermal expansion coefficient between the material and the semiconductor chip, and the flatness is lost. Due to these factors, the accuracy of outer lead bonding deteriorates in the mounting process using the semiconductor device.

The present invention is intended to solve the above problems in the prior art, and the object is also applied to a large chip size semiconductor device which was difficult in the prior art. A possible object is to provide a resin sealing method for a semiconductor device.

[0005]

According to the present invention, there is provided a TAB tape having a perforated portion at a central portion, a semiconductor chip disposed in the perforated portion, a semiconductor chip fixedly formed on the TAB tape, and a semiconductor chip. In a method for sealing a semiconductor device including an electrically connected inner lead, a TAB tape having a semiconductor chip is formed of a thin film of a semi-curable curable resin or a thermoplastic resin on at least the side where the inner lead is provided. It is characterized in that the encapsulating sheets thus obtained are overlapped with each other, and the elastic film-like material is pressed on the heat block under a reduced pressure atmosphere by utilizing the expansion by air pressure. In the present invention, the thin film used for sealing is composed of a semi-curable curable resin or a thermoplastic resin, but this thin film may be laminated with a metal foil or a non-metal thin film.

As the semi-curable curable resin, a thermosetting or ultraviolet curable resin cured in a B stage is used, and specifically, a thermosetting or ultraviolet curable epoxy resin or phenol resin. , Acrylic resin, polyimide resin, etc. can be used. An elastomer may be contained in these curable resins for the purpose of imparting toughness. Specifically, NBR-based, polyamide-based, acrylic-based, polyurethane-based, polyester-based, and polyolefin-based elastomers can be contained. As the thermoplastic resin, specifically, a polyimide resin, a polyester resin, a polyurethane resin or the like can be used.

Furthermore, the thin film may contain an inorganic or organic filler to control the coefficient of thermal expansion or workability. Examples of the inorganic filler include silica, alumina, zinc oxide, silicon nitride and the like, and examples of the organic filler include nylon, polyimide, silicone and the like. The amount of these fillers to be blended is 5 to 95 parts by weight, preferably 2 to 100 parts by weight of the resin.
It is in the range of 0 to 50 parts by weight. Further, a colorant such as carbon may be mixed in for the purpose of preventing the semiconductor device from being irradiated with light.

The encapsulating sheet composed of a thin film of a semi-curable curable resin or a thermoplastic resin in the present invention is a carrier substrate which is peelable after the resin composition of the above components is prepared by using an appropriate solvent. It is obtained by coating on another suitable substrate and drying, or is obtained as a thin film single film by a melt extruder and has a film thickness of 10
The range from ˜500 μm, preferably the range from 20 to 100 μm is used.

When a metal foil is laminated on a thin film of a semi-curable curable resin or a thermoplastic resin, the thickness of the metal foil is 1
.About.1000 .mu.m, preferably 10 to 260 .mu.m, for example, copper foil, aluminum foil, molybdenum alloy foil or the like can be used. This metal foil provides the semiconductor device with the effects of preventing moisture absorption and improving heat dissipation, and imparts the function of a ground plane.

When a nonmetal thin film is laminated on a thin film of a semi-curable curable resin or a thermoplastic resin, the thickness of the nonmetal thin film is 1 to 1000 μm, preferably 10 to 26.
A film of 0 μm, for example, polyethylene terephthalate, polypropylene, fluororesin, polyimide, polyetherimide, polyphenylene sulfide, polyether ether ketone, or the like is used. These non-metal thin films act as a protective film that imparts a function of preventing moisture absorption. On the other hand, in the thin semiconductor device of the present invention, as the TAB tape, any tape can be used as long as it is conventionally used, and for example, a tape having a heat-resistant polyimide resin as a base material can be preferably used.

FIG. 1 is a sectional view of an example of a thin semiconductor device manufactured by the method of the present invention. In the figure, reference numeral 1 denotes a TAB tape base material having a square perforated portion formed in the center thereof, on which a copper foil is adhered and fixed, and an inner lead 3 formed in a pattern by etching or the like. Are provided via the adhesive layer 5. The semiconductor chip 2 is placed in the space of the TAB tape base material, and the inner lead 3
And the bumps 4 are electrically connected to each other. On the inner lead fixed to the TAB tape base material, TAB
A thin film of a semi-curable curable resin or a thermoplastic resin having substantially the same size as the tape base material is bonded to form a layer made of the sealing resin 6, and the sealing resin bonds the semiconductor chip to the inner lead. The part is sealed. FIG. 2 is a sectional view of another embodiment of the thin semiconductor device manufactured by the method of the present invention. This embodiment shows a state in which a thin film of a semi-curable curable resin or a thermoplastic resin in which metal foils are laminated is used for resin encapsulation, and the surface of the sealing resin 6 is the metal foil 7. Is covered by. Further, FIG. 3 is a cross-sectional view of still another embodiment of the thin semiconductor device manufactured by the method of the present invention. In this embodiment, both sides of the TAB tape are resin-sealed by a sealing sheet composed of a thin film of a semi-curable curable resin or a thermoplastic resin, and both sides of the TAB tape are sealed. A layer made of the stop resin 6 is formed.

The resin sealing of the thin semiconductor device according to the present invention can be performed as follows. First, the above T
A perforation for mounting a semiconductor chip is formed on the AB tape, a conductive film such as copper foil is adhered and fixed, a conductor circuit is formed by photoresist formation and etching, and a solder resist is formed on the conductor circuit. Is provided to electrically connect the inner lead of the conductor circuit and the semiconductor chip. Then, the above-mentioned thin films of the semi-curable curable resin or the thermoplastic resin are superposed on each other, and the elastic film-like material is expanded by air pressure on a heat block under a reduced pressure atmosphere of 500 mmHg or less, preferably 50 mmHg or less. By pressing, they are attached and integrated.

Referring to the drawings, the present invention will be described with reference to FIG.
Is an example of an apparatus for implementing the present invention. Reference numeral 10 denotes a vacuum box, in which an elastic layered material 11 made of rubber or the like is provided.
The inside of the vacuum box is divided into an upper chamber 12a and a lower chamber 12b. A vent hole 10a for introducing or exhausting air is attached to the upper chamber, and a vent hole 10b for exhausting air is also attached to the lower chamber. A heat block 13 is provided inside the lower chamber, and a TAB tape 14 having a semiconductor mounted thereon and a sealing sheet 15 having a thin film of a sealing resin provided on a base material are formed by an elastic layered material. It is designed to be pressed. Further, the feeding reel 16a and the take-up reel 16b for the TAB sheet and the feeding reel 17a and the take-up reel 17b for the sealing sheet are provided outside the vacuum box. Note that 18a and 18b
Is a guide roll. When the sealing resin layers are provided on both sides of the thin semiconductor device, for example, a device as shown in FIG. 5 may be used. In FIG. 5, the TAB tape 14
The take-up reel 16a and the take-up reel 16b are provided above and below, respectively, and the take-up reel 17a and the take-up reel 17b for the sealing sheet 15 are provided, whereby the sealing sheet 15 is pressed to both sides of the TAB tape 14. To be done. Although a means for maintaining the airtightness of the vacuum box when the TAB tape and the sealing sheet are carried in and out of the vacuum box is not shown, it is well known in the art. The above means may be adopted.

In this device, the pay-out reel 16a
The TAB tape 14 having the semiconductor chip mounted thereon and the sealing sheet 15 supplied from the supply reel 17a are superposed by the guide roll 18a, and the heat block 13 in the lower chamber is evacuated to the vacuum of the vacuum box. Transported on. Then the vent 1 of the upper chamber
The air is introduced from 0a to increase the pressure in the upper chamber and change the atmospheric pressure between the lower chamber and the lower chamber. As a result, the elastic layered product 1
1 expands to the side of the lower chamber as shown by the phantom line, and presses the TAB tape conveyed onto the heat block 13 and the thin film of the sealing resin of the sealing sheet. Since the heat block is kept at a predetermined temperature by an appropriate means, the sealing resin thin film is transferred onto the TAB tape by thermocompression and integrated. Next, the air in the upper chamber is discharged to shrink the elastic layered material, and the TAB tape is moved from above the heat block. At that time, the base material forming the sealing sheet is peeled off and wound around the winding reel 17b. While repeating this operation, the TAB tape on which the resin-sealed semiconductor is formed is taken out from the vacuum box and wound on the take-up reel 16b. According to the invention, TA
Since the B tape and the sealing sheet are thermocompression-bonded under a reduced pressure atmosphere, bubbles and the like are prevented from being involved.

[0015]

EXAMPLES The present invention will be described below with reference to examples. Example 1 Using a TAB tape composed of a polyimide film having a thickness of 75 μm, an adhesive layer having a thickness of 20 μm, and a wiring layer formed of a copper foil having a thickness of 36 μm, a semiconductor element having a thickness of 250 μm was subjected to inner lead bonding, A thermosetting thin film having the following composition was attached to the assembled unsealed semiconductor device to assemble a thin film semiconductor device. Thickness 38μ
m of a polyethylene terephthalate film is coated with a thermosetting resin coating having the following composition and heated and dried at 160 ° C. for 10 minutes to form a semi-cured thermosetting resin layer having a film thickness of 20 μm and sealed. A stop sheet was prepared. 25% isopropyl alcohol / toluene mixed solution of polyamide resin (Macromelt 6238, amide group equivalent 220, weight average molecular weight 40,000, manufactured by Henkel Hakusui Co., Ltd.) 400 parts Epoxy resin (Epicoat 828, manufactured by Yuka Shell Co., Ltd.) 50 parts Novolac 50% methyl ethyl ketone solution of phenol resin (CKM2400, Showa High Polymer Co., Ltd.) 50 parts 1% methyl ethyl ketone solution of 2-methylimidazole 30 parts

Next, four thin films of the sealing resin constituting this sealing sheet are superposed and heated and pressed under the conditions of 80 ° C. and 1 kg / cm ² to give a semi-cured thermosetting sealing resin of 80 μm. A thin film was prepared. Using this semi-curable thermosetting encapsulating resin thin film, resin encapsulation was performed by the apparatus shown in FIG.
That is, the semi-curable thermosetting encapsulating resin thin film is superposed on the TAB tape on which the thin film semiconductor device is formed, and introduced into the lower chamber in the evacuated vacuum box.
Induction on a heat block heated to 0 ° C. The pressure in the evacuated vacuum box was <1 mmHg.
Next, the elastic layered material is expanded by introducing air into the upper chamber and bonded by pressing with a pressure of 1 kg / cm ² , and the total thickness of the structure shown in FIG.
A thin semiconductor device of 0 μm was manufactured.

Example 2 An electrolytic copper foil having a thickness of 35 to 40 μm is applied to one surface of the semi-curable thermosetting encapsulating resin thin film described in Example 1 at 80 ° C. and 1 kg / kg.
² has the same structure as in Example 1 except that the ones bonded together under a pressure of cm ² are used, and the total thickness is 400 μm.
m thin semiconductor device was manufactured.

Example 3 A coating liquid made of a thermoplastic polyimide resin (LARC, manufactured by Mitsui Toatsu Kagaku Co., Ltd.) was applied to a substrate made of a polyethylene terephthalate film having a thickness of 38 μm, and 180 ° C.
Was dried by heating for 10 minutes to form a thermoplastic resin layer having a film thickness of 20 μm, and further dried by heating at 200 ° C. for 1 hour to produce a sealing sheet. Next, four sheets of this encapsulating sheet were overlapped and heated and pressed under the conditions of 300 ° C. and 4 kg / cm ² to produce a thermoplastic encapsulating resin thin film of 80 μm. This thermoplastic encapsulating resin thin film was placed on an unsealed thin film semiconductor device similar to that of Example 1, and was placed under reduced pressure (<1 mm
Hg), 300 ° C., and a pressure of 4 kg / cm ² , and the thin semiconductor device having the structure shown in FIG. 1 and a total thickness of 400 μm was manufactured.

Example 4 An encapsulating resin thin film was prepared in the same manner as in Example 1 using a UV-heat combined curing type epoxy resin (Adeka Optomer KS-800, manufactured by Asahi Denka Co., Ltd.). This encapsulating resin thin film was placed on an unencapsulated thin film semiconductor device similar to that of Example 1, and under reduced pressure conditions (<1 mmHg), 150 ° C., 1 k.
UV lamp 80W by laminating with pressure of g / cm ^2.
/ Cm × 2 for 1 minute, and heated at 150 ° C. for 5 minutes to cure the thin film semiconductor device having a structure shown in FIG. 1 and a total thickness of 400 μm.

Example 5 Using the semi-cured thermo-photochemical encapsulation resin thin film described in Example 1, resin encapsulation was performed from both sides of a thin semiconductor device by the apparatus shown in FIG. That is, the above-mentioned semi-curable thermosetting encapsulating resin thin films are superposed from both sides on both sides of a TAB tape on which a thin semiconductor device is formed, and the device shown in FIG.
Bonding was performed in the same manner as in Example 1 to fabricate a thin semiconductor device having a structure shown in FIG. 3 and a total thickness of 480 μm.

Comparative Example 1 A semiconductor device was manufactured by mounting a semiconductor device on a lead frame with a die attach material and wire-bonding the semiconductor device with a mold material as shown in FIG. In this case, it was difficult to keep the total thickness below 1 mm. Moreover, the production process is complicated, such as punching and aligning the dam burring, resulting in poor production efficiency.

Comparative Example 2 In the unsealed semiconductor device described in Example 1,
10μm of protective solder resist layer on the wiring surface of TAB
Then, the inner lead portion and the semiconductor blocking surface were sealed by a potting method with a liquid molding material to prepare a thin semiconductor device having the structure shown in FIG. The total thickness was 500 μm. Further, the flatness was not good as compared with the cases of Examples 1 to 5 above.

The thin semiconductor devices manufactured by the method of the present invention in Examples 1 to 5 were evaluated for reliability, and were compared in all the temperature cycle, pressure cooker test, high temperature and high humidity bias test. Results equivalent to those of the semiconductor device manufactured by the method in Examples 1 and 2 were obtained. On the other hand, the semiconductor devices of Comparative Examples 1 and 2 were difficult to be thinned as compared with the semiconductor devices of Examples 1 to 5, and the total thickness was larger than that of the semiconductor devices of Examples 1 to 5. In addition, the semiconductor device in Comparative Example 2 had poor planarity as compared with the semiconductor devices manufactured by the method of the present invention in Examples 1 to 5. From the above results, it was confirmed that the thin semiconductor device manufactured by the method of the present invention is extremely thin and has excellent reliability.

[0024]

As described above, according to the sealing method of the present invention, a thin film of a semi-curable curable resin or a thermoplastic resin is bonded by utilizing the expansion of an elastic film material by air pressure in a reduced pressure atmosphere as described above. It is possible to fabricate a thin semiconductor device which does not involve bubbles or the like during thermocompression bonding, has good flatness, and has an extremely thin thickness and high reliability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an example of a thin semiconductor device resin-sealed according to the present invention.

FIG. 2 is a cross-sectional view of another example of a thin semiconductor device resin-sealed according to the present invention.

FIG. 3 is a cross-sectional view of still another example of a thin semiconductor device resin-sealed according to the present invention.

FIG. 4 is a cross-sectional view of an example of an apparatus for practicing the present invention.

FIG. 5 is a cross-sectional view of another example of a device for carrying out the present invention.

FIG. 6 is a side view of a resin-sealed conventional semiconductor device.

FIG. 7 is a cross-sectional view of a conventional resin-sealed thin semiconductor device.

[Explanation of symbols]

1 ... TAB tape base material, 2 ... Semiconductor chip, 3 ... Inner lead, 4 ... Bump, 5 ... Adhesive layer, 6 ... Sealing resin,
7 ... Metal foil, 10 ... Vacuum box, 10a, 10b ... Vent, 11 ... Elastic layered material, 12a ... Upper chamber, 12b ... Lower chamber, 13 ... Heat block, 14 ... TAB tape, 1
5 ... Sealing sheet, 16a ... Delivery reel, 16b take-up reel, 17a ... Delivery reel, 17b ... Take-up reel, 18a, 18b ... Guide roll.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takao Fujitsu 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Stock company Toshiba Tamagawa factory

Claims (3)

[Claims] 1. A TAB tape having a perforated portion in a central portion, a semiconductor chip disposed in the perforated portion, an inner lead fixedly formed on the TAB tape, and electrically joined to the semiconductor chip. In a method of encapsulating a semiconductor device, the TAB tape on which a semiconductor chip is mounted is overlaid with a encapsulating sheet composed of a thin film of a semi-curable curable resin or a thermoplastic resin, at least on a side where an inner lead is provided. A method for encapsulating a semiconductor device, comprising: pressing on a heat block in a reduced-pressure atmosphere by utilizing expansion of an elastic film material by air pressure. 2. The method for encapsulating a semiconductor device according to claim 1, wherein a thin film of a semi-curable curable resin or a thermoplastic resin is laminated with a metal foil. 3. The method for encapsulating a semiconductor device according to claim 1, wherein a thin film of a semi-curable curable resin or a thermoplastic resin is laminated with a non-metal thin film.