JPH09134978A - Semiconductor device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the warp of a wiring board due to the curing shrinkage of a resin. SOLUTION: This device has a semiconductor pellet 2 on the main surface side of a wiring board 1 and bump electrodes 6 on the rear side of the wiring board 1. The resin 4A of a resin-sealed body 4 is provided on the main surface side and on the rear surface side, respectively, and further, lead pins 5 for electrically interconnecting the electrode pads 1B of the rear surface of the wiring board 1 and the bump electrodes 6 are provided therebetween. The thickness T2 of the resin 4A provided on the rear surface side of the wiring board 1 is set nearly equal to the thickness T1 of the resin 4A provided on the main surface side of the wiring board 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and is particularly effective when applied to a semiconductor device in which a semiconductor pellet is provided on the main surface side of a base substrate and a bump electrode is provided on the back surface side of the base substrate. Technology.

[0002]

2. Description of the Related Art As a semiconductor device employing the BGA (B all G rid A rray ) structure, for example, Nikkei Nikkei Electronics [1994 BP, published, February 28 (No.6
02), pages 111 to 118], semiconductor pellets are mounted on the main surface side of a wiring substrate formed of a resin substrate, and the semiconductor pellets are sealed with a resin sealing body. The so-called plastic type BGA is being developed. This plastic type BGA structure semiconductor device is generally formed by the following manufacturing process.

First, a wiring board made of a resin substrate is prepared. A plurality of electrode pads are arranged on each of the main surface of the wiring board and the back surface thereof that faces the main surface.

Next, the semiconductor pellets are mounted on the main surface of the wiring board, and then the external terminals of the semiconductor pellets and the electrode pads on the main surface of the wiring board are electrically connected by bonding wires.

Next, a resin encapsulant for encapsulating the semiconductor pellets is formed on the main surface side of the wiring board. The resin sealing body is formed based on a transfer molding method using, for example, an epoxy thermosetting resin.

Next, bump electrodes are connected to the electrode pads on the back surface of the wiring board. This allows the plastic mold B
A semiconductor device of A structure is formed.

After that, the semiconductor device is shipped as a product after being subjected to a sorting process. The semiconductor device shipped as a product is mounted on a mounting board such as a CPU board and a memory board.

[0008]

The semiconductor device has a structure in which a resin sealing body is formed on one surface side (main surface side) of a wiring board. The resin encapsulant is formed of, for example, an epoxy thermosetting resin to which a phenolic curing agent, silicone rubber and a filler are added. This thermosetting resin is 3
Since it has a curing shrinkage ratio of about 5%, the wiring substrate is warped due to the curing shrinkage of the resin when the resin encapsulant is formed. When the semiconductor device is mounted on the mounting board, the warp of the wiring board causes a connection failure in which the electrode pads of the mounting board and the bump electrodes of the semiconductor device are not connected, and significantly reduces the mounting accuracy of the semiconductor device on the mounting board. This decrease in the mounting accuracy of the semiconductor device becomes more remarkable as the planar size of the wiring board increases due to the increase in the number of pins.

An object of the present invention is to provide a technique capable of preventing the wiring board from warping due to curing shrinkage of the resin.

Another object of the present invention is to provide a semiconductor device having high mounting accuracy on a mounting board.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0012]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

A semiconductor device in which a semiconductor pellet is provided on a main surface side of a wiring board and bump electrodes are provided on a back surface side of the wiring board, wherein a resin is provided on each of the main surface side and the back surface side of the wiring board. A resin for the sealing body is provided, and lead pins are provided between the electrode pads on the back surface of the wiring board and the bump electrodes to electrically connect the two. The thickness of the resin on the back surface side of the wiring board is set to be substantially the same as the thickness of the resin on the main surface side of the wiring board.

According to the above-mentioned means, when the resin encapsulant is formed, shrinkage stress due to curing shrinkage of the resin occurs on the main surface side and the back surface side of the wiring board, and the main surface side and the wiring board side Since the same pulling force acts on each of the back side,
It is possible to prevent warpage of the wiring board due to curing shrinkage of the resin.

Further, since it is possible to prevent the connection failure between the electrode pad of the mounting substrate and the bump electrode of the semiconductor device due to the warp of the wiring substrate, it is possible to provide the semiconductor device having a high mounting accuracy on the mounting substrate.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The structure of the present invention will be described below with reference to B
An embodiment in which the present invention is applied to a semiconductor device having a GA structure will be described. In all the drawings for describing the embodiments, components having the same function are denoted by the same reference numerals, and a repeated description thereof will be omitted.

FIG. 1 is a plan view showing a state in which an upper portion of a resin sealing body of a semiconductor device according to an embodiment of the present invention is removed, and FIG. 2 is a view taken along the line AA shown in FIG. It is the sectional drawing cut.

As shown in FIGS. 1 and 2, the semiconductor device has a semiconductor pellet 2 mounted in a recess 1C provided on the main surface side of the wiring board 1.

Although not shown in detail, the wiring board 1 has, for example, a multilayer wiring structure. The wiring board 1 is used for the purpose of reducing the manufacturing cost of the semiconductor device.
For example, it is formed of a resin substrate in which glass fiber is impregnated with epoxy resin or polyimide resin. This resin substrate is
It has a thermal expansion coefficient of about 10 to 30 × 10 ⁶ [1 / ° C.].

A plurality of electrode pads 1A are arranged on the main surface of the wiring board 1, and a plurality of electrode pads 1B are arranged on the back surface thereof facing the main surface of the base substrate 1. Each of the plurality of electrode pads 1A is arranged along each side of the semiconductor pellet 2, and each of the plurality of electrode pads 1B is arranged in a matrix. The electrode pad 1A and the electrode pad 1B are electrically connected to each other via the wiring of the above-mentioned multilayer wiring structure.

Each electrode pad 1B on the back surface of the wiring board 1
One end of the lead pin 5 is electrically and mechanically connected to the surface of the via a bonding layer. The lead pin 5 is
For example, it is formed of a Kovar material whose surface is plated with gold. The adhesive layer is formed of, for example, a silver brazing material.

Support leads 7B are fixed to the outer peripheral region of the main surface of the wiring board 1 with an adhesive layer interposed. The support lead 7B is formed in, for example, a ring shape extending along the outer periphery of the wiring board 1. This support lead 7B
The suspension leads 7C are integrated on each side of the wiring board 1.

The semiconductor pellet 2 is mainly formed of a semiconductor substrate made of, for example, single crystal silicon. A logic circuit system, a memory circuit system, or a mixed circuit system thereof is formed on the main surface (element formation surface) of the semiconductor substrate. Further, on the main surface of the semiconductor substrate 1, a plurality of external terminals (bonding pads) 2A arranged along each side of the outer periphery thereof are arranged. The semiconductor substrate made of single crystal silicon has a coefficient of thermal expansion of about 3.0 to 3.5 × 10 ⁶ [1 / ° C.].

The external terminals 2A of the semiconductor pellet 2 and the electrode pads 1A of the wiring board 1 are electrically connected to each other via bonding wires 3. As the bonding wire 3, for example, a gold (Au) wire, a copper (Cu) wire, an aluminum (Al) wire, or a coated wire in which the surface of a metal wire is coated with an insulating resin film is used. The bonding wires 3 are connected by, for example, a bonding method using thermocompression and ultrasonic vibration.

The wiring board 1, the semiconductor pellets 2, the bonding wires 3, the lead pins 5, the support leads 7B, the suspension leads 7C and the like are sealed with a resin sealing body 4. The resin sealing body 4 is formed based on, for example, a transfer molding method. The resin sealing body 4 is formed of, for example, an epoxy thermosetting resin 4A to which a phenolic curing agent, silicone rubber, and a filler are added. The thermosetting resin 4 has a thermal expansion coefficient of about 5 to 30 × 10 ⁶ [1 / ° C.] and a curing shrinkage ratio of about 3 to 5 [%].

A plurality of bump electrodes 6 are arranged in a matrix on the back surface of the resin sealing body 4. That is, the semiconductor device of the present embodiment has a BGA structure in which a plurality of bump electrodes 5 are arranged in a matrix on the back surface side of the wiring board 1.
Each of the plurality of bump electrodes 6 is electrically and mechanically connected to the other end side of each of the plurality of lead pins 5. That is, the bump electrode 6 includes the lead pin 5, the electrode pad 1B,
The external terminal 2A of the semiconductor pellet 2 is connected via the wiring of the multilayer wiring structure, the electrode pad 1A, and the bonding wire 3 respectively.
Is electrically connected to The bump electrode 6 is, for example,
It is made of a spherical Pb-Sn alloy material.

A resin 4A of a resin encapsulant 4 is provided on each of the main surface side and the back surface side of the wiring board 1, and between the electrode pads 1B on the back surface of the wiring board 1 and the bump electrodes 6. Is provided with a lead pin 5 for electrically connecting the two. In this way, by providing the resin 4A of the resin sealing body 4 on the main surface side and the back surface side of the wiring board 1, respectively, when forming the resin sealing body 4, the main surface side of the wiring board 1 and its side. A contraction stress is generated on the back surface side due to curing shrinkage of the resin 4A, and a tensile force acts on each of the main surface side and the back surface side of the wiring board 1, so that the wiring board 1 is prevented from warping due to the curing contraction of the resin 4A. can do. Further, by providing a lead pin 5 between the electrode pad 1B on the back surface of the wiring board 1 and the bump electrode 6, the bump electrode 5 is separated from the electrode pad 1B on the back surface of the wiring board 1. Since the two can be electrically connected in this state, the resin 4A of the resin sealing body 4 can be provided on the back surface side of the wiring board 1.

As shown in FIG. 3, the thickness T2 of the resin 4A provided on the back surface side of the wiring board 1 is substantially the same as the thickness of the resin 4A provided on the main surface side of the wiring board 1. By setting the height to approximately the same, the pulling forces acting on the main surface side and the back surface side of the wiring board 1 can be made substantially the same, so that the prevention effect of preventing the warpage of the wiring board due to the curing shrinkage of the resin is enhanced. be able to.

The semiconductor device having such a structure is shown in FIG.
(Principal plan view) and the manufacturing process using the lead frame 7 shown in FIG. 5 (cross-sectional view taken along the line BB in FIG. 4). The lead frame 7 has a structure in which the wiring board 1 is arranged in a region defined by the frame 7A. The wiring board 1 is adhesively fixed to the support leads 7B with an adhesive layer interposed, and the support leads 7B are integrated with the frame body 7A via the suspension leads 7C. That is, the wiring board 1
It is supported by the body 7A of the lead frame 7 via the support leads 7B and the suspension leads 7C, respectively. A recess 1C is provided on the main surface side of the wiring board 1, and lead pins 5 are provided on the back surface side thereof. One end side of the lead pin 5 is adhesively fixed to the electrode pad 1B on the back surface of the wiring board 1 with an adhesive layer interposed.

Next, a method of manufacturing the semiconductor device will be described.

First, the lead frame 7 having the wiring board 1 supported by the frame body 7A via the support leads 7B and the suspension leads 7C is prepared.

Next, the concave portion 1C on the main surface side of the wiring board 1 is formed.
The semiconductor pellets 2 are mounted inside. Semiconductor pellet 2
Are fixed in the concave portion 1C of the wiring board 1 with an adhesive layer interposed.

Next, the external terminals 2 of the semiconductor pellet 2
A and an electrode pad 1A on the main surface of the wiring board 1 are electrically connected by a bonding wire 3.

Next, as shown in FIG. 6 (a cross-sectional view of an essential part), the lead frame 7 is arranged between the upper die 10A and the lower die 10B of the molding die 10 and the upper die of this molding die 10 is arranged. A wiring board 1 having a semiconductor pellet 2 provided on the main surface and a lead pin 5 having one end connected to an electrode pad 1B on the back surface is arranged in a cavity 11 formed by 10A and a lower die 10B. In this step, since the wiring board 1 is supported by the frame body 7A of the lead frame 7 via the suspension leads 7C, the other end side of the lead pin 5 is the suspension leads 7C.
The elastic force of C makes pressure contact with the inner wall surface of the cavity 11. Further, since the wiring board 1 is supported by the lead frame 7, the cavity 11 and the wiring board 1 are positioned by the molding die 10 and the lead frame 7. In addition, since the molding die 10 enhances the fluidity of the resin (4A) supplied into the cavity 11,
It has been previously heated to a temperature of about 170 to 180 [° C.].

Next, a resin tablet (thermosetting resin) is put into the pot of the molding die 10. The resin tablet is heated in advance by a heater to reduce its viscosity and then put into a pot. The resin tablet placed in the pot is given heat from the molding die 10 to further reduce the viscosity.

Next, the resin tablet is pressed by the plunger of the transfer molding apparatus, and the resin 4A is introduced into the cavity 11 from the pot through the runner and the inflow gate.
Is supplied to form the resin sealing body 4 in which the resin 4A is provided on each of the main surface side and the back surface side of the wiring board 1. Thereafter, the resin sealing body 4 is heat-treated for a while in order to cure the resin 4A. In this process, the wiring board 1
A shrinkage stress is generated on the main surface side and the back surface side of the resin 4A due to curing shrinkage of the resin 4A, and a pulling force acts on the main surface side and the back surface side of the wiring substrate 1, respectively. The warp of the substrate 1 can be prevented.

Next, the REIT frame 7 is taken out from the molding die 10.

Next, the bump electrode 6 is electrically and mechanically connected to the other end of the lead pin 5. After that, the suspension leads 7C are cut from the frame body 7A of the lead frame 7, whereby the semiconductor device of this embodiment is almost completed.

Thereafter, the semiconductor device is shipped as a product after being subjected to a sorting process. The semiconductor device shipped as a product is mounted on the mounting substrate, and the bump electrodes 6 of the semiconductor device are electrically and mechanically connected to the electrode pads of the mounting substrate.

As described above, according to this embodiment, the following effects can be obtained.

(1) A semiconductor device having a BGA structure in which a semiconductor pellet 2 is provided on the main surface side of the wiring board 1 and bump electrodes 5 are provided on the back surface side of the wiring board 1, The resin 4A of the resin encapsulant 4 is provided on each of the main surface side and the back surface side thereof, and furthermore, between the electrode pad 1B on the back surface of the wiring board 1 and the bump electrode 6, the both are electrically connected. By providing the lead pins 5, shrinkage stress due to curing shrinkage of the resin occurs on the main surface side and the back surface side of the wiring board when the resin sealing body is formed, and the main surface side and the back surface side of the wiring board are generated. Since a pulling force acts on each of them, it is possible to prevent the warp of the wiring board due to the curing shrinkage of the resin. In addition, the electrode pad 1B on the back surface of the wiring board 1
By providing the lead pin 5 for electrically connecting the bump electrode 6 and the bump electrode 6 to each other, the bump electrode 5 and the bump electrode 6 are electrically connected to each other in a state where the bump electrode 5 is separated from the electrode pad 1B on the back surface of the wiring board 1. Wiring board 1 so that
The resin 4A of the resin sealing body 4 can be provided on the back surface side of the. Also, by changing the length of the lead pin 5,
The thickness of the resin 4A provided on the back surface side of the wiring board 1 can be freely set.

Further, since it is possible to prevent the connection failure between the electrode pad of the mounting substrate and the bump electrode 6 of the semiconductor device due to the warp of the wiring substrate 1, it is possible to provide a semiconductor device having high mounting accuracy on the mounting substrate. .

(2) Resin 4A on the back side of the wiring board 1
Of the resin 4A on the principal surface side of the wiring board 1 is set to be substantially the same as the thickness T2 of the resin 4A on the principal surface side and the rear surface side of the wiring board 1. Since they can be made substantially the same, it is possible to enhance the prevention effect of preventing the warpage of the wiring substrate 1 due to the curing shrinkage of the resin. Further, the wiring board 1 can be arranged at the center of the resin sealing body 4 in the plane direction.

(3) The semiconductor pellet 2 is placed in a recess 1C provided on the main surface of the wiring board 1. With this configuration, the protrusion amount (height) of the semiconductor pellet 2 protruding from the main surface of the wiring board 1 can be reduced by an amount corresponding to the depth of the recess 1C, and the semiconductor pellet 2 is provided on the main surface side of the wiring board 1. Since the thickness T1 of the resin 4A can be reduced, the thickness T2 of the resin 4A provided on the back surface side of the wiring board 1 can be reduced. As a result, an increase in the thickness of the semiconductor device due to the resin 4A provided on the back surface side of the wiring board 1 can be suppressed.

(4) By manufacturing a semiconductor device using the lead frame 7 having the wiring board 1, the other end of the lead pin 5 is attached to the inner wall surface of the cavity 11 of the molding die 10 by the elastic force of the suspension lead 7C. Since they are pressed into contact with each other, it is possible to prevent the resin 4A from flowing between the other end of the lead pin 5 and the inner wall surface of the cavity 11.
Further, since the wiring board 1 is supported by the lead frame 7, the cavity 11 and the wiring board 1 can be positioned by positioning the molding die 10 and the lead frame 7.

As shown in FIG. 8 (main part cross-sectional view), the wiring board 1 is pressed by the pressing member 12 provided on the upper die 10A of the molding die 10, and one end side of the lead pin 5 is inserted into the cavity 11. You may make it press-contact with an inner wall surface. The pressing member 12 is composed of a mechanism that moves up and down with respect to the wiring board 1.

As shown in FIG. 8, the cavity 11 and the wiring board 1 may be positioned by the positioning member 13 provided on the lower mold 10B of the molding die 10.

Further, as shown in FIG. 9 (a cross-sectional view of the main part), the wiring board 1 is pressed by the projections 14 provided on the upper die 10A of the molding die 10, and the one end side of the lead pin 5 is moved to the cavity 11
It may be pressed into contact with the inner wall surface of the.

Although not shown, a recess may be provided in the inner wall surface of the cavity facing the one end side of the lead pin 5, and the one end side of the lead pin 5 may be inserted into this recess.

As described above, the invention made by the present inventor is:
Although specifically described based on the embodiment, the present invention
It is needless to say that the present invention is not limited to the above embodiment, and various changes can be made without departing from the scope of the invention.

For example, the present invention can be applied to a semiconductor device in which a semiconductor pellet is provided on the main surface side of a wiring board with a bump electrode interposed and a bump electrode is provided on the back surface side of the wiring board.

[0052]

The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.

It is possible to prevent the warp of the wiring board due to the curing shrinkage of the resin.

Further, it is possible to provide a semiconductor device having high mounting accuracy on the mounting substrate.

[Brief description of the drawings]

FIG. 1 is a plan view showing a state in which an upper portion of a resin sealing body of a semiconductor device according to an embodiment of the present invention is removed.

FIG. 2 is a sectional view taken along a line AA shown in FIG.

FIG. 3 is an enlarged sectional view of a main part of FIG. 2;

FIG. 4 is a plan view of a main portion of a lead frame used in the manufacturing process of the semiconductor device.

5 is a cross-sectional view taken along the line BB shown in FIG.

FIG. 6 is a main-portion cross-sectional view for illustrating the manufacturing process for the semiconductor device.

FIG. 7 is a main-portion cross-sectional view for illustrating the manufacturing process for the semiconductor device.

FIG. 8 is a main-portion cross-sectional view for illustrating the manufacturing process for the semiconductor device according to the other embodiment of the present invention.

FIG. 9 is a main-portion cross-sectional view for illustrating the manufacturing process for the semiconductor device which is another embodiment of the present invention.

[Explanation of symbols]

1 ... Wiring board, 1A, 1B ... Electrode pad, 1C ... Recess,
2 ... Semiconductor pellet, 2A ... External terminal (bonding pad), 3 ... Bonding wire, 4 ... Resin encapsulant, 4
A ... Resin, 5 ... Lead pin, 6 ... Bump electrode, 7 ... Lead frame, 7A ... Frame body, 7B ... Support lead, 7C ... Suspension lead, 10 ... Mold, 11 ... Cavity, 12 ...
Pressing member, 13 ... Positioning member, 14 ... Protrusion.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Tachi 5-20-1 Kamimizuhonmachi, Kodaira-shi, Tokyo Inside Hiritsu Cho-LS Engineering Co., Ltd. (72) Inventor Shoji Matsugami Tokyo 5-20-1 Kamimizuhoncho, Kodaira-shi Hitsuryu SLS Engineering Co., Ltd. (72) Inventor Toshihiro Tsuboi 5-20-1 Kamimizuhoncho, Kodaira-shi, Tokyo Hiritsu Cho-LS・ I Engineering Co., Ltd. (72) Inventor Takashi Miwa 2326 Imai, Ome City, Tokyo Hitachi Device Manufacturing Center

Claims (4)

[Claims] 1. A semiconductor device in which a semiconductor pellet is provided on a main surface side of a wiring board, and bump electrodes are provided on a back surface side of the wiring board, wherein the main surface side and the back surface side of the wiring board are respectively provided. The semiconductor device is characterized in that a resin of a resin encapsulant is provided on the wiring board, and lead pins are provided between the electrode pads on the back surface of the wiring board and the bump electrodes to electrically connect the two. 2. The thickness of the resin provided on the back surface side of the wiring board is set to be substantially the same as the thickness of the resin provided on the main surface side of the wiring board. The semiconductor device according to claim 1. 3. The semiconductor device according to claim 1, wherein the semiconductor pellet is arranged in a recess provided in the main surface of the wiring board. 4. A method of manufacturing a semiconductor device, wherein a semiconductor pellet is provided on the main surface side of a wiring board, and bump electrodes are provided on the back surface side of the wiring board, the semiconductor pellet being provided on the main surface. A step of disposing a wiring board having a lead pin whose one end side is connected to an electrode pad on the back surface in a cavity of a molding die, and supplying resin into the cavity of the molding die so that the main surface side of the wiring board And a step of forming a resin resin body in which a resin is provided on each of the back surfaces thereof, and a step of connecting a bump electrode to the other end side of the lead pin, the method for manufacturing a semiconductor device.