JPH10242328A - Circuit board, circuit module having the circuit board and electronic equipment having the circuit module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit module which reduces unsoldered zones when semiconductor devices are mounted on a circuit board. SOLUTION: The module comprises semiconductor devices 1 having connection terminals 2, 3 and a circuit board 11 having a surface for mounting the elements 1 and pads 12 to be soldered to the terminals 2, 3. The mounting surface of the board 11 has recesses 12 into which the terminals 2, 3 are entered when the elements are mounted. The recesses 12 have pads 13 coated with solder 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board, a circuit module having the circuit board, and an electronic device having the circuit module.

[0002]

2. Description of the Related Art In an electronic device such as a portable computer, there is a solder joining method as a method of joining a connection terminal provided on a semiconductor bare chip to a pad provided on a circuit board in order to mount the semiconductor bare chip on a circuit board.

In this solder bonding method, a bump is formed on a pad provided on a semiconductor bare chip (connection terminals are formed by the pad and the bump), and a terminal forming surface of the semiconductor bare chip is formed on a semiconductor element having a pad formed on a circuit board. By facing the mounting surface, the tip of the bump of the semiconductor bare chip is brought into contact with the pad of the circuit board, the solder applied to the pad surface is melted and fixed to the pad and the bump, and the semiconductor bare chip is electrically connected to the circuit board. It is connected and mechanically fixed.

[0004]

However, the method of joining the connection terminals of the semiconductor bare chip to the pads of the circuit board by soldering for the following reasons is as follows.
A so-called unsoldering defect, in which the connection terminal of the semiconductor bare chip and the pad of the circuit board are not joined by solder, may occur.

That is, when the solder is joined by heating and melting the solder, the circuit board is sometimes heated together with the solder and deformed so as to warp in a direction away from the semiconductor bare chip. This phenomenon often occurs particularly at the edge of the circuit board. For this reason, the pad located at the warped portion of the circuit board moves in a direction away from the semiconductor bare chip, and the solder melted on the pad separates from the semiconductor bare chip, and unsolder failure may occur.

Further, Au formed on a semiconductor bare chip
If the bump height varies, or if the thickness of the solder applied to the circuit board pads varies,
When the solder is melted to join the Au bump and the pad, the Au bump may not reach the melted solder on the pad and unsolder failure may occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a circuit board capable of performing reliable mounting while suppressing occurrence of unsoldering defects when mounting a semiconductor element by soldering. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a circuit module in which unsoldering defects can be suppressed when a semiconductor element is mounted on a circuit board by soldering, thereby enabling reliable mounting.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electronic device having a circuit module capable of performing reliable mounting while suppressing the occurrence of unsoldering defects when mounting a semiconductor element on a circuit board by soldering.

[0010]

According to a first aspect of the present invention, there is provided a circuit board having a mounting surface on which a semiconductor element is mounted, and a pad which is soldered to a connection terminal of the semiconductor element. A circuit board, wherein the mounting surface is provided with a concave portion into which the connection terminal enters when the semiconductor element is mounted, and the concave portion is provided with the pad coated with solder. .

According to the structure of the present invention, since the connection terminal of the semiconductor element enters the recess of the circuit board, the connection when the height of the connection terminal is small by the displacement of the connection terminal when the circuit board is warped. The recess absorbs the shortage of the terminal height and the shortage of the solder when the thickness of the solder applied to the pads of the circuit board is small, so that the connection terminal and the pad cannot be soldered inside the recess. The occurrence of solder failure can be suppressed.

According to a second aspect of the present invention, in the circuit board according to the first aspect, the concave portion has a curved surface. According to the configuration of the present invention, the concave portion can be easily formed on the circuit board, and the pad can be easily formed inside the concave portion.

According to a third aspect of the present invention, there is provided a circuit module having a semiconductor element having a connection terminal, and a mounting surface for mounting the semiconductor element, and a pad which is soldered to the connection terminal of the semiconductor element on the mounting surface. Provided on the mounting surface of the circuit board, a recess in which the connection terminal enters when the semiconductor element is mounted is formed, and the pad coated with solder is provided in the recess. It is characterized by having.

According to the structure of the present invention, since the connection terminal of the semiconductor element enters the recess of the circuit board, the connection when the height of the connection terminal is small by the displacement of the connection terminal when the circuit board is warped. The recess absorbs the insufficient terminal height and the insufficient solder thickness when the thickness of the solder applied to the circuit board pads is small. The occurrence of defects can be suppressed.

According to a fourth aspect of the present invention, in the circuit module according to the third aspect, the connection terminal of the semiconductor element has a bump. ADVANTAGE OF THE INVENTION According to the structure of this invention, the semiconductor element using the bump for the connection terminal can be reliably solder-joined to a circuit board.

According to a fifth aspect of the present invention, in the circuit module according to the third aspect, the connection terminal of the semiconductor element has a solder ball. According to the configuration of the present invention, the semiconductor element using the solder ball for the connection terminal can be securely soldered to the circuit board.

According to a sixth aspect of the present invention, in the circuit module according to the third aspect, the semiconductor element is a bare chip. According to the configuration of the present invention, the semiconductor bare chip can be securely mounted on the circuit board by soldering.

An electronic device according to a seventh aspect of the present invention has a housing, a semiconductor element having a connection terminal, and a mounting surface for mounting the semiconductor element, and the mounting surface is soldered to the connection terminal of the semiconductor element. A circuit board provided with a pad; and a circuit module provided inside the housing.The mounting surface of the circuit board has a recess in which the connection terminal enters when the semiconductor element is mounted. The recess is provided with the pad coated with solder.

According to the structure of the present invention, it is possible to obtain an electronic apparatus having a circuit module capable of performing reliable mounting while suppressing the occurrence of unsoldering defects when mounting a semiconductor element on a circuit board by soldering. .

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. This embodiment is applied to a circuit module provided in an electronic device such as a portable computer or a word processor.
A semiconductor bare chip is used as an example of a semiconductor element. 1 to 3 show a circuit module provided inside a housing of an electronic device, FIG. 1 shows a semiconductor bare chip and a circuit board before soldering, FIG. 2 shows a semiconductor bare chip and a circuit board soldered, FIG. 3 shows a solder bare semiconductor bare chip and a warped circuit board.

In FIG. 1 to FIG. 3, reference numeral 31 denotes a housing of an electronic apparatus, and a circuit module to be described later is provided inside the housing 1. Next, the circuit module will be described.

1 to 3, reference numeral 1 denotes a semiconductor bare chip. As shown in FIG. 5, the semiconductor bare chip 1 has a rectangular shape, for example, and has a terminal forming surface 1a facing the mounting surface 11a of the circuit board 11 when soldered and mounted on the circuit board 11. For example, a plurality of pads 2 are formed at intervals along the entire periphery thereof, and a bump (hereinafter, referred to as an Au bump) 3 made of gold is formed on the surface of each pad 2. ing. The pad 2 and the Au bump 3 constitute a connection terminal.

Reference numeral 11 denotes a flat circuit board made of an insulating material, on which the semiconductor bare chip 1 is mounted. On the mounting surface 11a on which the semiconductor bare chip 1 is mounted on the circuit board 11, a plurality of recesses 12 are formed in a rectangular frame corresponding to the plurality of Au bumps 3 (pads 2) provided on the semiconductor bare chip 1. . Each of the plurality of recesses 12 has a hemispherical shape, that is, a shape having a curved surface, and a pad 13 made of a conductive metal is formed on the inner surface of each recess 12. When the semiconductor bare chip 1 is mounted on the circuit board 11 by soldering, the Au bumps 3 of the semiconductor bare chip 1
It is large enough to get inside. Solder 14 is applied to the surface of each pad 13 at a predetermined thickness.

Next, a structure for mounting the semiconductor bare chip 1 on the circuit board 11 will be described. As shown in FIG. 2, the semiconductor bare chip 1 is arranged with the terminal forming surface 1a facing the mounting surface 11a of the circuit board 11, and a plurality of Au bumps 3 provided on the terminal forming surface 1a are opposed to each other provided on the mounting surface 11a. It enters the inside of the plurality of recesses 12. Then, the solder 14 applied to the pads 13 respectively formed in the plurality of recesses 12 is melted and fixed to the pads 13 of the recesses 12 and the Au bumps 3 entering the recesses 12 for each of the recesses 12. I have. That is, the molten solder 14
Is fixed to the Au bump 3 that is stored inside the concave portion 12 and enters the concave portion 12. As a result, each Au bump 3 of the semiconductor bare chip 1 is mechanically joined and electrically connected to each pad 13 of the circuit board 11.

An insulating resin 15 is molded between the terminal forming surface 1a of the semiconductor bare chip 1 and the mounting surface 11a of the circuit board 11, and each of the joints between the Au bumps 3 and the pads 13 is sealed and mechanically. As well as electrical insulation from the outside.

When mounting the semiconductor bare chip 1 on the circuit board 11, pads 13 are formed in each recess 12 formed in the circuit board 11, and solder 14 is
Is applied, and wax is applied to each solder 14.
In the semiconductor bare chip 1, an Au bump 3 is formed on each pad 2 by a ball bonder. Then, the semiconductor bare chip 1 is arranged on the circuit board 11, and then the solder 14 is melted and the Au bumps 3 and the pads 13 are soldered.

In this structure, the recess 12 formed in the circuit board 11 serves as a solder pool for storing the molten solder 14, and the A of the semiconductor bare chip 1 that has entered the recess 12 is formed.
The u bump 3 is securely bonded to the pad 13 by the solder 14. When the Au bumps 3 of the semiconductor bare chip 1 enter the recesses 12 formed in the circuit board 11, the depth of the recesses 12 is reduced due to the warpage of the circuit board 11, the insufficient height of the Au bumps 3, and the thickness of the solder 14. A due to lack of
By absorbing the change in the positional relationship between the u bump 3 and the solder 14, the solder 14 can be fixed to the Au bump 3 while the tip of the Au bump 3 is located inside the recess 12.

For example, as shown in FIG. 3, when the circuit board 11 is warped in the direction away from the semiconductor bare chip 1 due to heat at the time of soldering and the pad 13 moves in the direction away from the Au bump 3, 11 recesses 1
2 absorbs the movement of the pad 13 and the Au bump 3 does not come off from the inside of the recess 12. For this reason, the Au bump 3 is fixed to the molten solder 14 stored inside the concave portion 12 while entering the inside of the concave portion 12, so that occurrence of unsoldering defects can be suppressed.

The recess 12 absorbs a shortage of the height of the Au bump 3 when the height of the Au bump 3 is small.
The Au bump 3 and the pad 11 are solder-bonded inside the concave portion 12, so that occurrence of unsoldering defects can be suppressed. Further, when the thickness of the solder 14 applied to the pads 13 of the circuit board 11 is small, the insufficient thickness of the solder
2 is absorbed, and the Au bump 3 and the pad 13 are solder-bonded inside the concave portion 12, so that occurrence of unsoldering defects can be suppressed.

Further, since the concave portion 12 of the circuit board 11 has a hemispherical shape, that is, a shape having a curved surface, the concave portion 12 can be easily formed, and the pad 13 can be easily formed inside the concave portion 12.

In this embodiment, the semiconductor bare chip 1 using bumps as connection terminals can be securely mounted on the circuit board 11 by soldering. Also,
In this embodiment, it is possible to obtain a circuit module securely mounted on the circuit board 11 by soldering using the semiconductor bare chip 1 as a semiconductor element.

FIG. 4 shows a second embodiment. In this embodiment, solder balls are used as connection terminals provided on a semiconductor bare chip 1. In FIG. 4, the same parts as those in FIG. 2 are denoted by the same reference numerals.
In the figure, reference numeral 21 denotes a solder ball. The solder ball 21 is attached to each pad 2 formed on the semiconductor bare chip 1 by a solder 2.
2 are joined. The surface of the solder ball 21 is also covered with the solder 22. When the semiconductor bare chip 1 is mounted on the circuit board 11, the solder balls 21 enter the recesses 12 of the circuit board 11, and the solder balls 21 and the pads 13 are joined by melting the solders 14 and 22. For this reason, in the case of this embodiment as well, the occurrence of unsoldering failure of the solder balls 21 can be suppressed.

By mounting the circuit module of each of the above-described embodiments inside the housing 31 of an electronic device such as a portable computer or a word processor, the unsoldered soldering when the semiconductor element is mounted on the circuit board by soldering. It is possible to obtain an electronic device including a circuit module capable of performing reliable mounting while suppressing occurrence of defects.

The present invention is not limited to the above-described embodiment, but can be implemented with various modifications. For example,
The semiconductor element is not limited to a semiconductor bare chip.
Other types, such as GA (ball grid array), can be used. Also, the connection terminals provided on the semiconductor element are not limited to the above-described embodiment,
Other types can be used.

[0035]

As described above, according to the present invention, the connection terminals of the semiconductor element enter the recesses of the circuit board.
The displacement of the connection terminal when the circuit board is warped, the shortage of the connection terminal when the height of the connection terminal is small, and the thickness of the solder when the thickness of the solder applied to the pads of the circuit board is small The shortage is absorbed by the concave portion, and the connection terminal and the pad are solder-bonded inside the concave portion, so that occurrence of unsoldering defects can be suppressed. For this reason,
The semiconductor element can be securely joined to the circuit board by soldering.

Therefore, according to the present invention, a circuit board capable of suppressing the occurrence of unsoldering when mounting a semiconductor element by soldering, and performing reliable mounting, a circuit module having this circuit board, and this circuit module An electronic device provided with:

[Brief description of the drawings]

FIG. 1 is a sectional view showing a circuit module according to a first embodiment of the present invention.

FIG. 2 is an exemplary sectional view showing a circuit module according to the embodiment;

FIG. 3 is an exemplary sectional view showing a circuit module according to the embodiment;

FIG. 4 is a sectional view showing a circuit module according to a second embodiment of the present invention.

FIG. 5 is a perspective view showing a semiconductor bare chip.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Semiconductor bare chip (semiconductor element), 2 ... Pad (connection terminal), 3 ... Au bump (connection terminal), 11 ... Circuit board, 12 ... recessed part, 13 ... Pad, 14 ... Solder, 31 ... Housing of electronic equipment.

Claims (7)

[Claims] 1. A circuit board having a mounting surface on which a semiconductor element is mounted, and a pad to be solder-bonded to a connection terminal of the semiconductor element on the mounting surface. A circuit board, characterized in that a concave portion into which the connection terminal enters when a semiconductor element is mounted is formed, and the pad coated with solder is provided in the concave portion. 2. The circuit board according to claim 1, wherein the concave portion has a curved surface. 3. A semiconductor device having a connection terminal, and a circuit board having a mounting surface on which the semiconductor device is mounted, and a pad provided on the mounting surface with a solder terminal to the connection terminal of the semiconductor device. A circuit, wherein the mounting surface of the circuit board has a concave portion into which the connection terminal enters when the semiconductor element is mounted, and the concave portion is provided with the pad coated with solder. module. 4. The circuit module according to claim 3, wherein the connection terminals of the semiconductor element have bumps. 5. The circuit module according to claim 3, wherein the connection terminal of the semiconductor element has a solder ball. 6. The circuit module according to claim 3, wherein the semiconductor element is a bare chip. 7. A circuit board having a housing, a semiconductor element having connection terminals, and a mounting surface on which the semiconductor element is mounted, and a pad provided on the mounting surface to be soldered to the connection terminals of the semiconductor element. A circuit module provided inside the housing, and a concave portion in which the connection terminal enters when the semiconductor element is mounted is formed on a mounting surface of the circuit board, and solder is applied to the concave portion. An electronic device comprising the pad.