JP2000200852A - Semiconductor device, manufacturing method and mounting method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce defective connection of solder bump due to warp of a semiconductor device by differentiating the height of columnar solder bumps from the mounting surface depending on the warp of the semiconductor device. SOLUTION: When a semiconductor device BGA is brought close to a mounting board 12 while heating the mounting board 12, a columnar solder bump 9A at a part of lowest height from the mounting surface touches a solder paste 13 because of warp of the BGA and begins to melt. When the BCG is pressed to approach the mounting board 12 furthermore, columnar solder bumps 9B at parts of lower height from the mounting surface touches the solder paste 13 sequentially and begin to melt. The BCG is pressed to approach the mounting board 12A up to a point where a columnar solder bump 9C at a part of highest height from the mounting surface eventually touches the solder paste 13 and begins to melt and then the temperature is lowered to room temperature. The columnar solder bump 9A touching the solder paste 13 is deformed into a substantially spherical shape and the columnar solder bump 9C touching the solder paste 13 last retains substantially columnar shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, a method of manufacturing the same, and a method of mounting the same, and more particularly to a technique effective when applied to a ball grid array type semiconductor device in which solder bumps are arranged in an array. .

[0002]

2. Description of the Related Art Conventionally, electrode pads and leads on a circuit element forming surface of a semiconductor chip are electrically connected to each other, and only the semiconductor chip and the connecting portion or the connecting portion are sealed with a resin or the like and arranged in an array. In a ball grid array type semiconductor device in which solder bumps are connected to the other ends of the leads (hereinafter referred to as BGA), the shape of the solder bumps is usually a spherical solder ball (Electronic Technology, 19).
September 1998, p. 2). In the BGA, the diameter of a terminal electrode for connecting a solder ball is often 600 microns, and the distance between the terminal electrodes is often 1.27 mm. The solder ball connected to the terminal electrode has a diameter of 760 microns.
After the connection, the height from the terminal electrode surface becomes about 600 microns. Also, in the BGA, the connection portion between the electrode pad of the semiconductor chip and the lead is sealed with a resin or the like, so that the sealing temperature is lowered from the sealing temperature to room temperature due to the difference in the thermal expansion coefficient of the sealing material and the package material. Warpage occurs when In addition, the heating causes the package body of the BGA to be warped. In particular, when solder balls are mounted and reflowed, they are heated to about 240 ° C., and thus are most likely to warp.

[0003]

As a result of studying the above-mentioned prior art, the present inventor has found the following problems. As shown in FIG. 5 (schematic diagram for explanation), the package body P is warped by heating, depending on the sealing material and the package material used. Due to the warpage of the package, when mounted on the mounting substrate 12,
Variations in height H from the mounting surface occur between 200 and 300 microns. A solder ball having a height H of about 600 microns before mounting becomes about 400 microns on a solder ball 14A connected to the mounting substrate 12 after mounting. Therefore, if the variation in the height H from the mounting surface becomes large, the solder balls 14 </ b> B in a portion higher than the mounting surface do not reach the mounting substrate 12,
There is a problem that connection is poor. Further, when a solder ball having a large diameter is used to increase the height of the solder ball, there is a problem that adjacent solder balls come into contact with each other and cause a short circuit. An object of the present invention is to provide a technique capable of reducing a connection failure of a solder bump due to warpage of the semiconductor device when the semiconductor device is mounted on a mounting board by solder bumps. Another object of the present invention is to provide a technique capable of reducing a connection failure due to a variation in height from a mounting surface without contact between adjacent solder bumps in a semiconductor device having solder bumps. It is in. 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.

[0004]

The following is a brief description of an outline of a typical invention among the inventions disclosed in the present application.

(1) A ball grid array type semiconductor device in which solder bumps connected to leads electrically connected to electrode pads formed on a circuit element forming surface of a semiconductor chip are arranged in an array. When the bumps are columnar and the columnar solder bumps are mounted on a mounting board, the heights of the columnar solder bumps from the mounting surface are different depending on the warpage of the semiconductor device.

(2) A ball grid array type semiconductor device in which solder bumps connected to leads electrically connected to electrode pads formed on a circuit element forming surface of a semiconductor chip are arranged in an array. When the bumps are columnar, a solder material having a lower melting point than the melting point of the columnar solder bumps is interposed between the columnar solder bumps and the leads. The height of the bump from the mounting surface is different depending on the warpage of the semiconductor device.

(3) In the semiconductor device of (1) or (2), when mounted on a mounting board, the volume of all the columnar solder bumps is equal.

(4) A method of manufacturing a ball grid array type semiconductor device in which solder bumps connected to leads electrically connected to electrode pads formed on a circuit element forming surface of a semiconductor chip are arranged in an array. Then, a solder material is applied to terminal electrodes connecting the solder bumps of the semiconductor device, and a columnar solder bump having a melting point higher than the melting point of the solder material is mounted on the solder material. A manufacturing method in which the columnar solder bump is fixed on the semiconductor device by heating at a temperature higher than the melting point of the solder material and lower than the melting point of the columnar solder bump.

(5) A method of manufacturing a ball grid array type semiconductor device in which solder bumps connected to leads electrically connected to electrode pads formed on a circuit element forming surface of a semiconductor chip are arranged in an array. Then, on the terminal electrode surface connecting the solder bumps of the semiconductor device, a mask having a corresponding cylindrical hole formed in an array is placed,
A manufacturing method in which a solder material is printed from above the mask to fill the inside of the cylindrical hole, and the mask is removed to form a columnar solder bump.

(6) The method for mounting a ball grid array type semiconductor device according to (1) or (2), wherein a solder material having a melting point lower than a melting point of the columnar solder bump is connected to the columnar solder bump on a mounting board. Coating on the portion, the columnar solder bump connection portion, the positioning of the columnar solder bumps is performed, the mounting substrate is heated at a temperature higher than the melting point of the columnar solder bumps, and the columnar solder bumps are mounted on the mounting substrate. The semiconductor device is brought into contact with and melted in the order of the contacted columnar solder bumps, and in response to the warpage of the semiconductor device, the semiconductor device is pressed closer to the mounting substrate until the unconnected columnar solder bumps contact the solder material. The implementation method.

Hereinafter, the present invention will be described in detail along with embodiments (examples) with reference to the drawings. In all the drawings for describing the embodiments, components having the same function are denoted by the same reference numerals, and their repeated description will be omitted.

[0012]

FIG. 1 shows a BGA according to an embodiment of the present invention.
FIG. 1 is a diagram showing a schematic configuration of a (semiconductor device), and FIG.
FIG. 1B is a plan view of the BGA as viewed from the surface on which the solder bumps are mounted, and FIG. 1B is a cross-sectional view of the BGA taken along the line AA ′ in FIG. In the BGA of this embodiment, as shown in FIG. 1B, a semiconductor chip 1 is fixed to a heat diffusion plate 3 provided on a wiring board 2 on a surface opposite to a surface on which circuit elements are formed. I have. The electrode pads (not shown) on the circuit element forming surface of the semiconductor chip 1 are electrically connected to the leads 4 on the wiring board 2 by bonding wires 5. A connection portion between the semiconductor chip 1 and the lead 4 is sealed with a mold resin (sealing material) 6. Wiring board 2
The terminal electrode 7 of the lead 4 is provided on a surface opposite to the surface on which the heat diffusion plate 3 is provided. The columnar solder bump 9 is connected to the terminal electrode 7 via a solder material (solder paste) 8 having a lower melting point than the melting point of the columnar solder bump 9. Here, the BGA is warped due to a difference in thermal expansion coefficient between the wiring board 2 mainly composed of resin and glass fiber, the heat diffusion plate 3 made of copper or aluminum, and the sealing material 6. And The columnar solder bumps 9 have the same volume as the conventional solder bumps.

Hereinafter, the first embodiment will be described with reference to FIGS. 2 and 3.
The method of mounting the columnar solder bumps 9 on the BGA terminal electrodes 7 will be described. First, as shown in FIG. 2A, a lead is formed on a heat diffusion plate 3 made of copper or aluminum, on a surface of the semiconductor chip 1 opposite to the surface on which circuit elements are formed, and on a package base made of resin and glass fiber. The wiring board 2 on which the wiring (including the multilayer wiring) is formed is adhered with an adhesive (not shown), and the leads 4 on the wiring board 2 and the electrode pads (not shown) on the semiconductor chip 1 are connected. After being electrically connected with the wires 5, the semiconductor chip 1, the leads 4, and the wires 5 are sealed with a sealing material 6. Next, as shown in FIG. 2B, a solder paste 8 having a low melting point is applied on the terminal electrodes 7 provided on the wiring board 2. Next, as shown in FIG. 2C, columnar solder bumps 9 having a melting point higher than the melting point of the solder paste 8 are mounted on the solder paste 8. This columnar solder bump 9 is created in advance. next,
As shown in FIG. 2D, the BGA is heated at a temperature higher than the melting point of the solder paste 8 and lower than the melting point of the columnar solder bumps 9 to melt the solder paste 8, and then the temperature is lowered to room temperature. 7 and the columnar solder bumps 9 are connected and fixed. According to the above method, the BGA in which the electrode pads 7 and the columnar solder bumps 9 are fixed via the low melting point solder paste 8 has the appearance as shown in FIGS. 1A and 1B.

Next, a method using a screen mask will be described as a modification of the method of mounting the columnar solder bumps. In the method using this screen mask, FIG.
As shown in (a), a semiconductor chip 1, leads 4, wires 5
Is sealed with a sealing material 6, as shown in FIG. 3A, on the surface of the wiring substrate 2 on which the terminal electrodes 7 are formed, on the terminal electrodes 7 arranged in an array, A mask 11 having a cylindrical hole corresponding to the terminal electrode 7 is placed thereon, and the mask 1
1, a solder paste is filled from above into a cylindrical hole by a printing technique, a columnar solder paste 10 is formed inside the hole formed in the mask 11, and heated at a temperature equal to or lower than the melting point of the columnar solder paste 10 to form a terminal electrode. After fixing on the mask 7, the mask 11 is removed to form the columnar solder bumps 9 as shown in FIG.

FIG. 4 is a schematic diagram for explaining a process of mounting the BGA having the columnar solder bumps 9 manufactured by the above method on a mounting board. First, as shown in FIG. 4A, the columnar solder bump 9 connected to the BGA is formed on a terminal electrode (not shown) on which a solder paste 13 having a melting point lower than the melting point of the columnar solder bump 9 on the mounting board 12 is applied. ). Next, as shown in FIG. 4B, the BGA is brought close to the mounting substrate 12 while heating the mounting substrate 12 at a temperature higher than the melting point of the solder paste 13 and lower than the melting point of the columnar solder bumps 9. Due to the warpage, the columnar solder bump 9A at the lowest height from the mounting surface comes into contact with the solder paste 13 and melts. Next, as shown in FIG. 4C, when the BGA is further pressed and approached to the mounting board 12, the BGA comes into contact with the solder paste 13 in the order of the columnar solder bumps 9B having a lower height from the mounting surface and melts. Next, FIG.
As shown in (d), finally, the columnar solder bump 9C at the highest position from the mounting surface is connected to the solder paste 1.
3 and BGA is mounted on the mounting substrate 12 until it melts.
, And the temperature is lowered to room temperature. At this time, the columnar solder bump 9A that has first contacted the solder paste 13 has been deformed into a shape close to a sphere, and the columnar solder bump 9C that has last contacted the solder paste 13 remains substantially columnar. The columnar solder bump 9B and the columnar solder bump 9C correspond to the height from the mounting surface.
Take the shape between.

As described above, according to the present embodiment, a BGA (semiconductor device) having the columnar solder bumps 9 is formed by using the columnar solder bumps 9 as the BGA solder bumps.
Is mounted on the mounting board, even if the BGA is warped,
The mounting surface of the columnar solder bump 9 can be a horizontal surface. Further, by using the columnar solder bumps 9 as the solder bumps of the BGA, the gap between the adjacent solder bumps is increased, so that the wiring board 2 and the mounting board can be brought close to each other.
The connection failure of the solder bumps due to the warpage of A can be reduced. In addition, since the columnar solder bumps 9 are not heated at a high temperature when mounted on the BGA, the warpage of the BGA can be suppressed, and the variation in height from the mounting surface can be reduced.

For example, in the case of a BGA in which the distance between the nearest terminal electrodes is 1.27 mm, the columnar solder bump 9 or the solder bump 9 having the same volume as the conventionally used solder ball having a diameter of 760 μm and having a smaller bottom area. When the columnar solder paste 10 is formed, the height can be higher than about 600 microns when solder balls are used. Therefore, even when the package body of the BGA has a large warp and the height variation from the mounting surface is large, the connection failure is reduced. It decreases and the mountability improves.

In this embodiment, the case where the BGA warps toward the mounting substrate 12 has been described. However, the BGA may warp to the opposite side to the mounting substrate 12 due to a difference in material of the package body or a method of sealing the semiconductor chip. However, in this case as well, it is possible to reduce the connection failure with the mounting board by the same mounting method as in the present embodiment. Also, besides the warpage of the package,
Even when the mounting board is warped, mounting by the method of the present embodiment can reduce poor connection between the mounting board and the BGA.

As described above, the present invention has been specifically described based on the embodiments. However, it is needless to say that the present invention is not limited to the above-described embodiments and can be variously modified without departing from the gist thereof. .

[0020]

The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows. (1) By making the solder bumps of the semiconductor device columnar, when the semiconductor device having the columnar solder bumps is mounted on a mounting substrate, the mounting surface of the columnar solder bumps is made horizontal even if the semiconductor device is warped. Can be. Further, it is possible to reduce the connection failure of the solder bump due to the warpage of the semiconductor device or the mounting substrate. (2) By making the solder bumps of the semiconductor device column-shaped, the gap between the adjacent solder bumps is widened so that the wiring board and the mounting board can be made closer to each other, and the connection failure of the solder bumps due to the warpage of the semiconductor device is reduced. can do. (3) Since heating is not performed at a high temperature when mounting the columnar solder bumps on the semiconductor device, warpage of the semiconductor device can be suppressed, and variations in height from the mounting surface can be reduced. (4) By making the solder bumps of the semiconductor device column-shaped, the height from the terminal electrode can be increased without changing the volume thereof. Therefore, even when the semiconductor device is greatly warped, poor connection with the mounting board can be prevented. Can be reduced.

[Brief description of the drawings]

FIG. 1 is a plan view and a cross-sectional view illustrating a schematic configuration of a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view for explaining a method of forming a solder bump of the semiconductor device of the present embodiment.

FIG. 3 is a cross-sectional view for explaining a modification of the method of forming solder bumps of the semiconductor device according to the embodiment.

FIG. 4 is a schematic cross-sectional view for explaining a mounting process of the semiconductor device of the present embodiment.

FIG. 5 is a schematic cross-sectional view for explaining a problem of the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor chip, 2 ... Wiring board, 3 ... Heat diffusion plate, 4 ...
Lead, 5: Wire, 6: Resin (sealing material), 7: Terminal electrode, 8: Solder paste, 9, 9A, 9B, 9C: Columnar solder bump, 10: Columnar solder paste, 11: Screen mask, 12 ... Mounting board, 13 ... solder paste, 14
A, 14B: solder ball, P: package body, H: variation in height due to warpage

Claims (6)

[Claims] 1. A ball grid array type semiconductor device in which solder bumps connected to leads electrically connected to electrode pads formed on a circuit element forming surface of a semiconductor chip are arranged in an array. When the pillar-shaped solder bumps are mounted on a mounting board,
A semiconductor device, wherein heights of the columnar solder bumps from a mounting surface are different depending on the warpage of the semiconductor device. 2. A ball grid array type semiconductor device in which solder bumps connected to leads electrically connected to electrode pads formed on a circuit element forming surface of a semiconductor chip are arranged in an array. A column, and a solder material having a lower melting point than the melting point of the columnar solder bump is interposed between the columnar solder bump and the lead. When the columnar solder bump is mounted on a mounting board, the columnar solder bump Wherein the height of the semiconductor device from the mounting surface is different depending on the warpage of the semiconductor device. 3. The semiconductor device according to claim 1, wherein all of the columnar solder bumps have the same volume when mounted on a mounting board. 4. A method of manufacturing a ball grid array type semiconductor device in which solder bumps connected to leads electrically connected to electrode pads formed on a circuit element forming surface of a semiconductor chip are arranged in an array. A solder material is applied to terminal electrodes connecting the solder bumps of the semiconductor device, and a columnar solder bump having a higher melting point than the melting point of the solder material is mounted on the solder material. A method of manufacturing a semiconductor device, comprising heating the semiconductor device at a temperature higher than the melting point of the solder material and lower than the melting point of the columnar solder bump to fix the columnar solder bump on the semiconductor device. 5. A method of manufacturing a ball grid array type semiconductor device in which solder bumps connected to leads electrically connected to electrode pads formed on a circuit element forming surface of a semiconductor chip are arranged in an array. On a terminal electrode surface for connecting the solder bumps of the semiconductor device, a mask having a cylindrical hole corresponding to the terminal electrode formed in an array is placed, and a solder material is printed from the mask. A method for manufacturing a semiconductor device, comprising filling a cylindrical hole and removing the mask to form a columnar solder bump. 6. The method for mounting a ball grid array type semiconductor device according to claim 1, wherein a solder material having a melting point lower than a melting point of the columnar solder bump is applied to the columnar solder bump connection portion of a mounting substrate. Then, the connection between the columnar solder bump connection portion and the columnar solder bump is performed, the mounting substrate is heated at a temperature higher than the melting point of the columnar solder bump, and the columnar solder bump is brought into contact with the mounting substrate. Melting the columnar solder bumps in order, and pressing the semiconductor device toward the mounting board until the unconnected columnar solder bumps contact the solder material in response to the warpage of the semiconductor device. Semiconductor device mounting method.