JPH10189626A - Manufacturing method of electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to manufacture a package consisting of a ball grid array efficiently at low cost and, also to provide a method of manufacturing an electronic component which is superior in characteristics to a temperature chamber and moisture. SOLUTION: A semiconductor chip 20 is mounted on the upper surface of a lead frame 10. Pad parts 12, 12,... for solder balls are provided in the bottom of the lead frame 10, and adhesive tapes are respectively bonded to these pad parts 12, 12,.... Here, a hole 24 is provided in a printing hole plate 32, and a liquid sealing resin 36 is poured in the hole 34 by a squeegee 38 to seal the chip 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an electronic component, and more particularly to a method of manufacturing an electronic component by encapsulating a semiconductor chip or the like and performing packaging such as a ball grid array. About.

[0002]

2. Description of the Related Art Conventionally, in packaging a semiconductor chip, the semiconductor chip is mounted on a lead frame.
It is formed by sealing the mounted semiconductor chip by a resin molding method using a mold and cutting the lead frame at a predetermined position. In recent years, BGA (Ball Grid Arra
y) A new package of electronic components is being developed. Since the BGA-packaged electronic component has electrodes provided on the bottom surface of the package, the electronic component does not require a large mounting area when mounting the electronic component on a substrate. Since BGA is extremely excellent in mounting form, from the viewpoint of mounting electronic components,
It is expected that more and more opportunities will be used.

[0003] Portable electronic devices, such as notebook personal computers and mobile phones, are required to be portable. However, mounting parts for electronic components are extremely limited in order to emphasize portability. In addition, it is not difficult to expect that electronic devices with an emphasis on portability will appear in various future electronic devices. For these reasons, BGA-packaged electronic components that do not require a large mounting area are often used in electronic devices that require portability, and the future is promising.

[0004]

The above-mentioned B
Substrates used for GA include, for example, glass-epoxy,
An organic substrate of a glass cloth such as a glass-BT resin or a glass-polyimide substrate is used. Normally, a circuit is formed on the upper surface of this substrate, and bumps for solder balls are formed on the bottom surface. Therefore, the wiring portion formed on the upper surface of the substrate and the bump for the solder ball formed on the lower surface of the substrate are electrically connected via the through-hole plating.

The production of the above-mentioned substrate requires many steps such as a step of making holes for through holes in the copper-clad laminate, a copper plating step, a circuit forming step by etching, a solder resist forming step, and a gold plating step. However, there is a problem that the substrate itself is expensive.

[0006] The above resin is sealed by a resin molding machine such as a transfer molding machine using a mold.
Since the resin molding machine itself is expensive, and it takes a long time to create the mold to be used, and the production cost is high,
There has been a problem that the cost of the manufactured electronic components is inevitably increased.

[0007] Further, the conventional electronic parts using the BGA package are formed of a substrate, copper foil, plating, solder resist, adhesive, semiconductor chip, sealant, etc., each of which has a different expansion with respect to temperature. Because it has a coefficient,
There is a problem in that the properties against temperature change are not excellent, and furthermore, when used under high humidity conditions, problems such as peeling and cracking of the sealant occur due to moisture absorption of the sealant and moisture from the through-holes.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method of manufacturing an electronic component capable of efficiently and inexpensively manufacturing a package using a ball grid array. Also, the present invention
It is an object of the present invention to provide a method for manufacturing an electronic component that not only reduces the cost of the electronic component but also excels in characteristics against temperature change and characteristics against humidity.

[0009]

According to a first aspect of the present invention, there is provided a method for sealing a semiconductor chip mounted on a lead frame using a liquid sealing resin. A step of curing a sealing resin; and a step of welding a solder ball used as an electrode of the semiconductor chip to the lead frame.
According to a second aspect of the present invention, in the method of manufacturing an electronic component according to the first aspect, the sealing step includes printing the liquid sealing resin on the lead frame using a printing stencil provided with holes. It is characterized by sealing. According to a third aspect of the present invention, in the method for manufacturing an electronic component according to the first aspect,
A projection for welding the solder ball is provided on the bottom surface, and the sealing is performed using the lead frame to which an adhesive tape is attached so as to cover the entire bottom surface of the projection. Features. According to a fourth aspect of the present invention, in the method for manufacturing an electronic component according to the first aspect,
After the liquid sealing resin is sealed, a step of defoaming by reducing the pressure is provided. The invention according to claim 5 is
4. The method for manufacturing an electronic component according to claim 3, wherein the adhesive tape is peelable, and is peeled after the liquid sealing resin is cured. According to a sixth aspect of the present invention, in the method for manufacturing an electronic component according to the fifth aspect, the solder balls are welded to the protrusions that appear when the adhesive tape is peeled off.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. The embodiments described below are for making the present invention easy to understand. Such an embodiment shows one embodiment of the present invention and does not limit the present invention. It can be arbitrarily changed within the scope of the present invention.

First, a lead frame on which a semiconductor chip is mounted will be described. 2A and 2B are views showing a lead frame, wherein FIG. 2A is a top view, and FIG.
It is sectional drawing of the middle AA line. The lead frame 10 shown in FIGS. 2A and 2B serves as an electrode of a semiconductor chip, and is formed into a wiring shape by applying a resist on the upper surface of a metal plate such as copper or brass. After exposing the resist using a mask (not shown), the resist is developed and the metal plate is etched. This lead frame 10
, Pad portions (projections) 12, 12,... Are formed at positions where solder balls serving as electrodes of a semiconductor chip are arranged.

At the center of the lead frame 10, a substantially square semiconductor chip mounting portion 16 is provided. The semiconductor chip mounting portion 16 is a portion on which a semiconductor chip is mounted. Are supported by the frame 14. The frame 14 is a frame provided to support the wirings 15, 15,... And the semiconductor chip mounting portion 16. As will be described later, each frame 15,
, And the support rods 13, 13, so that after the frame 14 is cut off, the electrical continuity of each of the wirings 15, 15,.

The pad portion 1 of the lead frame 10 described above.
, The frame 14, and the portion other than the semiconductor chip mounting portion 16, that is, the wirings 15, 15,..., Have their lower portions so that the pad portions 12, 12,. Is further etched. In other words, since the pad portions 12, 12,... Are not etched, this portion has a shape protruding relatively downward.

FIG. 3 is a sectional view showing a sealing member before the semiconductor chip is sealed. As shown in FIG. 3, a semiconductor chip 20 is mounted on the upper surface of the semiconductor chip mounting portion 16 of the lead frame 10 described above. In addition, the semiconductor chip 20
A fixing tape 22 made of polyimide or the like is affixed to the bottom surfaces of the wirings 15, 15,... Where the lead wires 24, 24 are connected. As the fixing tape 22, an adhesive tape having a thickness substantially equal to the etching depth of the wirings 15, 15,... Is used.
It is attached so as to surround the periphery of the semiconductor chip mounting portion 16. Since the ends of the wirings 15, 15,... Formed on the lead frame 10 near the semiconductor chip mounting portion 16 are free ends and are not fixed, the fixing tape 22 .. Are provided so that the wires 15, 15,... Are fixed during bonding.

Further, an adhesive tape is provided on the entire bottom surface of the lead frame 10 so as to prevent the above-mentioned pad portions 12, 12,... From being sealed, and is peelable to maintain the flatness of the lead frame 10. The adhesive tape 26 is stuck. The adhesive tape 26 has heat resistance enough to withstand the curing temperature of the liquid sealing resin, and the material is not limited as long as no adhesive or the like remains on the pad portions 12, 12,. For example, as the adhesive tape 26, a polyimide adhesive tape, a polyester adhesive tape, or the like is used.

When the adhesive tape 26 is applied, the semiconductor chip 20 to be sealed is mounted on the semiconductor chip mounting portion 16 and the wiring 1 between the semiconductor chip 20 and the lead frame 10 is formed.
, 15 and ... are lead wires 24 and 2 such as gold wires and aluminum wires.
4 are electrically connected by wire bonding. When the above steps are completed, the member to be sealed 30 is formed.

Next, a step of sealing a semiconductor chip using a liquid sealing resin will be described. 1 (a) to 1 (c)
FIG. 3 is a cross-sectional view for explaining a step of sealing a semiconductor chip. 1A to 1C, the above-described sealed member 30 is arranged at a predetermined position. Reference numeral 32 denotes a printing stencil formed of stainless steel or the like and disposed above the member 30 to be sealed. The printing stencil 32 is formed with a hole 34 having an inner diameter substantially equal to the size of the frame 14 of the lead frame 10 and having a square shape.
The thickness of the printing stencil 32 is set according to the height of the manufactured electronic part.

Reference numeral 36 denotes a liquid sealing resin, which is a compound obtained by adding a curing agent, a filler, and the like to a liquid epoxy resin. The liquid sealing resin 36 is excellent in printing workability, has little shrinkage after curing, has an expansion coefficient of 10 ppm or less, has excellent moisture reflow resistance, and has good shape retention. For example, NPR-785N, NPR-783,
NPR-580 (all manufactured by Nippon Rec Co., Ltd.) and the like are used.

Reference numeral 38 denotes a squeegee formed in a substantially flat plate shape, the surface of which is substantially perpendicular to the printing stencil 32, and whose lower end 3
8a is arranged near the upper surface 32a of the printing stencil 32. The squeegee 38 moves in a direction perpendicular to the surface of the squeegee 38 along the upper surface 32 a of the printing stencil 32.

The step of sealing the semiconductor chip 20 in the above configuration will be described. First, as shown in FIG. 1A, the formed sealed member 30 is arranged below the printing stencil 32 at a predetermined interval. Next, the member to be sealed 3
Hole 3 formed in the printing stencil 32
The member 30 to be sealed is moved along the printing stencil 32 and adjusted so as to be located directly below the center of the printing plate 4.

Next, the member 30 to be sealed is moved upward in parallel, and the lead frame 10 of the member 30 to be sealed is
2 is brought into contact with the bottom surface 32b. Then, the liquid sealing resin 3
6 is dropped on the upper surface 32 a of the printing stencil 32, and the squeegee 3
8 is moved along the upper surface 32a of the printing stencil 32, and the liquid sealing resin 36 is poured into the holes 34 formed in the printing stencil 32 and filled therein, thereby performing printing on the member 30 to be sealed (FIG. 1). (B)). After the printing is completed, the member 30 to be sealed is moved downward, and the holes 3 of the printing stencil 32 are moved.
The liquid sealing resin filled in 4 is transferred to a member to be sealed (see FIG. 1C). When the above steps end, the printing step ends.

When the printing process is completed, the process shifts to a defoaming process under reduced pressure. In this step, when the semiconductor chip is sealed with the liquid sealing resin, the space between the lead frame 10 and the adhesive tape 26, the corner of the semiconductor chip 20, or the lead wire 2
This is a step performed to eliminate inconveniences such as air remaining at the positions 4 and 24, and a change in temperature that causes the remaining air to expand and crack.

FIGS. 4A and 4B are explanatory views showing a vacuum degassing step. As shown in FIG. 4A, first, the member to be sealed 30 to which the liquid sealing resin has been transferred is placed in the decompression tank 40. Thereafter, the inside of the decompression tank 40 is evacuated by a vacuum pump or the like, and the pressure in the decompression tank 40 is reduced to 10 Torr or less. By performing this process, air remaining in the liquid sealing resin is discharged to the outside from the surface of the liquid sealing resin. This vacuum degassing step is performed for 2 to 5 minutes.

When the decompression process is completed, a step of leaking air into the decompression tank 40 and returning the pressure in the decompression tank 40 to the atmospheric pressure is performed as shown in FIG. When the above steps are completed, no air remains in the liquid sealing resin, and only the liquid sealing resin is filled. When the vacuum degassing step is completed, a step of curing the liquid sealing resin transferred to the member to be sealed 30 is performed. In this step, the member 30 to be sealed is placed in a drying oven (not shown), and the temperature is reduced to about 1 °.
A process of setting the temperature to 00 to 150 ° C. and drying for 1 to 3 hours is performed.

After the step of curing the liquid sealing resin is completed, a step of peeling off the adhesive tape 26 adhered to the bottom surface of the lead frame 10 is performed. FIG. 5 shows the adhesive tape 26.
FIG. 4 is an explanatory view showing a step of peeling off the substrate. When the adhesive tape 26 is peeled off, the bottom surface of the member to be sealed 30 is almost entirely covered with the liquid sealing resin, and only the pads 12, 12,... And the fixing tape 22 appear.

When the above steps are completed, a step of cutting the frame 14 of the lead frame 10 is performed. FIG. 6 is an explanatory view showing a step of cutting the frame 14. The frame 14 is necessary to support the respective wirings 15, 15,... And the semiconductor chip mounting portion 16, but becomes unnecessary after sealing because the wirings 15, 15,. . Further, the frame 14 is provided with each wiring 1
Are electrically connected, wiring 1
This step is performed to insulate 5, 15,...

FIG. 7 is a diagram showing the bottom surface of the electronic component manufactured through the above steps. As shown in FIG. 7, only the semiconductor mounting portion 16, the pad portions 12, 12,... And the fixing tape 22 are exposed on the bottom surface of the manufactured electronic component.
The semiconductor chip, the lead wires 24, 24, and the wiring are sealed in the sealing resin.

In the final step, a step of welding the solder balls 45, 45,... Shown in FIG. 8 is performed. FIG. 8 is a sectional view showing an electronic component manufactured by welding solder balls. In this step, the pad portions 12, 12 shown in FIG.
The solder balls 45 having a uniform diameter are welded to each other using a ball mounter (not shown). With the above steps, all the steps are completed, and an electronic component in which the ball grid array is packaged as shown in FIG. 8 is manufactured.

In the embodiment of the present invention described above, since a mold is not required for sealing, a release agent for releasing the resin from the mold is not required. Therefore, an electronic component having good adhesion between the resin and the lead frame and having excellent moisture resistance can be manufactured. In addition, since a mold is not used, a process such as deburring is not required, and the process can be simplified.

The method for manufacturing an electronic component according to one embodiment of the present invention has been described above.
May be used, a film which is released by a solution, a solvent, or the like, or a photosensitive film, for example, a development type photoresist, a dry film, or the like. When the heat resistance of the adhesive tape 26 to be attached to the bottom surface of the lead frame 10 is low, the set temperature of the drying oven is set to about 100 ° C. to gel the liquid sealing resin, and then the adhesive tape 26 is peeled off. Thereafter, the composition may be further cured at a high temperature. Although only one hole 34 is provided in the printing stencil 32 in the attached drawings, it goes without saying that many holes may be provided to seal many semiconductor chips at once. Absent.

[0031]

As described above, in the method for manufacturing an electronic component according to the present invention, since the electronic component is manufactured using an inexpensive lead frame, the cost can be reduced. In addition, since the liquid sealing resin is printed when the liquid sealing resin is sealed, there is an effect that the electronic component can be manufactured efficiently and economically. Further, in the present invention, the periphery of the lead frame and the semiconductor chip are sealed with the same resin, and a member having a hygroscopic property is not used. Has an effect of being excellent in solder reflow properties.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining a step of sealing a semiconductor chip.

FIGS. 2A and 2B are views showing a lead frame, wherein FIG. 2A is a top view and FIG. 2B is a cross-sectional view taken along line AA in FIG.

FIG. 3 is a sectional view showing a sealing member before semiconductor chip sealing.

FIG. 4 is an explanatory view showing a vacuum degassing step.

FIG. 5 is an explanatory view showing a step of peeling the adhesive tape 26.

FIG. 6 is an explanatory view showing a step of cutting the frame 14;

FIG. 7 is a diagram illustrating a bottom surface of the manufactured electronic component.

FIG. 8 is a cross-sectional view showing an electronic component manufactured by welding solder balls.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Lead frame 12 Pad part (projection) 20 Semiconductor chip 26 Adhesive tape 32 Printing stencil 34 Hole 36 Liquid sealing resin 45 Solder ball

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koichi Nagai 12-16 Koyanagicho, Ibaraki-shi, Osaka Precious Mansion 302 (72) Inventor Noritaka Oyama 21-1 Ohatacho, Takatsuki-shi, Osaka Charman Corp. Settsu Tomita No. 301 (72) Inventor Tsuneichi Hashimoto No. 2339-7 Koshinohara, Yasu-cho, Yasu-gun, Shiga Prefecture

Claims (6)

[Claims] A step of sealing a semiconductor chip mounted on a lead frame with a liquid sealing resin, a step of curing the liquid sealing resin, and a step of forming a solder ball used as an electrode of the semiconductor chip. Welding the electronic component to the lead frame. 2. The electronic component according to claim 1, wherein, in the step of sealing, the liquid sealing resin is printed on the lead frame using a printing stencil provided with a hole and sealed. Manufacturing method. 3. A projection for welding the solder ball is provided on a bottom surface, and the sealing is performed by using the lead frame to which an adhesive tape is attached so as to cover the entire bottom surface. 2. The method for manufacturing an electronic component according to claim 1, wherein: 4. The method for manufacturing an electronic component according to claim 1, further comprising a step of depressurizing and defoaming after sealing the liquid sealing resin. 5. The method for manufacturing an electronic component according to claim 3, wherein the adhesive tape is peelable, and is peeled after curing the liquid sealing resin. 6. The method according to claim 5, wherein the solder balls are welded to the protrusions that appear when the adhesive tape is peeled off.