JPH11274356A - Surface mounting type electronic component and its mounting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability of connection practically adequately by providing a plurality of dummy bumps at the same height as a bump in at least a plurality of places, which are not on the same straight line of one surface. SOLUTION: A dummy bump 11 is formed of solder whose practical melting point is higher than a melting point of each bump 2B, and heat resistance guaranteed temperature is equal to that of a ball grid array(BGA) 10 and is formed by screen print through method, etc., respectively in four or more places on one surface of a printed wiring board 2 at the same height and configuration as each bump 2B. As a result, in the BGA 10, each dummy bump 11 and each land 6C of a motherboard 6 corresponding thereto come into direct contact with each other and can be mounted on the motherboard 6, since each bump 2B is conductivity connected through a creamy solder 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Table of Contents] The present invention will be described in the following order.

BACKGROUND OF THE INVENTION Prior Art (FIGS. 5 to 7) Problems to be Solved by the Invention (FIGS. 5 to 7) Means for Solving the Problems Embodiments of the Invention (1) This embodiment Configuration of BGA According to Embodiment (FIG. 1) (2) Method of Mounting BGA According to Embodiment (FIG. 2) (3) Operation and Effect of Embodiment (FIGS. 1 to 3) (4) Other Embodiments Form (FIG. 4) Effect of the Invention

[0003]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount type electronic component and a mounting method thereof, for example, a BGA (Ball Grid Arrangement).
ray).

[0004]

2. Description of the Related Art Conventionally, for example, a BGA 1 as shown in FIG. 5 has been widely known as this kind of surface mount type electronic component.

In this BGA 1, a plurality of bumps 2B are formed on one surface 2A of a printed wiring board 2, while a plurality of pads 2D are formed on another surface 2C, and a semiconductor chip 3 is provided. Each electrode 3A and each pad 2D are electrically connected by a wire 4. Then, a sealing resin 5 made of, for example, an epoxy-based insulating resin is supplied onto the other surface 2C of the printed wiring board 2 so as to cover the pads 2D, the wires 4, and the semiconductor chips 3.

As a result, the BGA 1 is connected to the bumps 2 B of the printed wiring board 2 and the lands 6 B on the mounting surface 6 A of the mother board 6 via the cream solder 7 so that the BGA 1 is electrically connected to the mother board 6. It has been made so that it can be implemented.

Here, such a BGA 1 is shown in FIGS.
The mother substrate 6 is formed by the following procedure shown in FIG.
Implemented above. That is, first, as shown in FIG. 6A, the cream solder 7 is placed on each land 6B of the mother substrate 6.
Is supplied by a method such as screen transfer.

In this state, as shown in FIG.
1 and the lands 6B on the mother substrate 6 are opposed to each other. Then, as shown in FIG. 6C, the BGA 1 is positioned so that the bumps 2B of the BGA 1 contact the lands 6B. Press and mount with a predetermined pressure.

The mother substrate 6 on which the BGA 1 is mounted is reflow-heated at a predetermined temperature, thereby
A1 can be mounted on the motherboard 6.

[0010]

However, such a B
In GA1, in the BGA mounting step shown in FIG. 6C, the pressure for pressing BGA1 onto mother substrate 6 is not constant. Thus, for example, as shown in FIG. 7A, when the pressing pressure of the BGA 1 is large, the cream solder 7 supplied on each land 6B of the mother board 6 is crushed more than necessary, so that the There is a problem that the cream solders 7 come into contact with each other and cause short-circuit failure between the lands 6B.

A mother board 6 on which the BGA 1 is mounted
In the heating step of reflow heating, after the cream solder 7 supplied on each land 6B of the mother board 6 is melted, the BGA 1 is pressed onto each land 6B by its own weight, and There is also a problem that the cream solder 7 on each land 6B comes into contact with each other to crush the cream solder 7 supplied to the lands more than necessary, causing short shot between the lands 6B.

On the other hand, when the pressing pressure of the BGA 1 is small, on the other hand, as shown in FIG. 7B, for example, the shapes of the bumps 2B of the BGA 1 are not uniform and the height of the bumps 2B varies (coplanarity). ) Is large, the bumps 2B that do not come into contact with the cream solder 7 supplied on the lands 6B of the mother board 6 are generated in the bumps 2B of the BGA1, and there is a problem that an open defect is caused by the floating of the bumps.

Conventionally, the control of the pressing pressure of the BGA 1 depends only on the setting of the conditions of the mounting device of the BGA 1. For example, when the BGA 1 or the mother board 6 itself has a defect such as warpage, the above-described control is performed. It was difficult to avoid short shots.

Further, the heating temperature applied to the BGA 1 during the heating processing step is confirmed by measuring the temperature of the heating furnace before heating the BGA 1, which is caused by the temperature variation of the heating furnace and the temperature measuring device. In some cases, there is a difference between the temperature of the pre-measurement and the temperature of the actual heating due to the variation in accuracy of the BGA1. Therefore, the heating temperature applied to the BGA1 at the time of the heating processing for actually heating the BGA1 is the BGA1.
When the temperature is higher than the heat-resistant guaranteed temperature, the sealing resin 5 of the BGA 1 is dissolved, so that there is a problem that the BGA 1 cannot be used.

The present invention has been made in view of the above points, and has as its object to realize a surface mount electronic component capable of sufficiently improving the reliability of connection in practical use.

[0016]

According to the present invention, there is provided a surface mounting type electronic component having a plurality of first protruding electrodes made of a first conductive material provided on one surface thereof. Using a second conductive material having a melting point higher than that of the first conductive material, at least at three or more positions that are not on the same straight line, a plurality of second conductive materials having the same height as the first protruding electrodes. Protrusion electrodes were provided.

Thus, in this surface mount type electronic component,
When mounting on a motherboard, the second projection electrode can stably mount the motherboard in a predetermined state.

According to the present invention, there is provided a method for mounting a surface-mounted electronic component having a plurality of first projecting electrodes made of a first conductive material on one surface, wherein at least one surface is not on the same straight line. A first step of forming a plurality of second projecting electrodes at the same height as each first projecting electrode by using a second conductive material having a higher melting point than the first conductive material at three or more positions; And electrically connecting the respective electrodes of the motherboard provided with a plurality of electrodes corresponding to the first and second projecting electrodes on one surface with the first and second projecting electrodes of the surface mount type electronic component, respectively. A second step for connection is provided.

According to this method of mounting a surface mount type electronic component, it is possible to stably mount the electronic component on a mother board in a predetermined state by the second protruding electrode.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

(1) Configuration of BGA According to the Present Embodiment In FIG.
Indicates a BGA according to the present embodiment as a whole, and has substantially the same configuration as that of the BGA 1 except that a dummy bump 11 is formed on the surface 2A in addition to the bumps 2B on the surface 2A of the printed wiring board 2. Become.

In this case, the dummy bump 11 has a melting point higher than the melting point of each of the bumps 2B, and is, for example, about 220 [° C.] to 250 [° C.], such as Sn-Ag based solder, which is equivalent to the heat-resistant guaranteed temperature of the BGA 10. The bumps 2B are formed, for example, at four corners on the one surface 2A of the printed wiring board 2 by the screen transfer method or the like with the same height and the same size as the height of each bump 2B.

As a result, the BGA 10 is provided with the dummy bumps 11 and the corresponding lands 6C of the mother substrate 6 corresponding to the dummy bumps 11.
Are directly in contact with each other, and the bumps 2B and the corresponding lands 6B of the mother board 6 are electrically connected via the cream solder 7 so that the bumps 2B can be mounted on the mother board 6. ing.

(2) Method of Mounting BGA According to the Present Embodiment Here, this BGA 10 is actually shown in FIGS. 2 (A) to 2 (C).
Can be mounted on the motherboard 6 by the following procedure shown in FIG. That is, first, as shown in FIG. 2A, each dummy bump 11 of the BGA 10 is mounted on the mounting surface 6A of the mother substrate 6.
Each land 6B except the land 6C formed corresponding to
The cream solder 7 is supplied onto each of them by a method such as screen transfer.

Next, in this state, as shown in FIG.
Each bump 2B of GA10 and each land 6 on mother substrate 6
B and each dummy bump 11 and each corresponding land 6
6C, the BGA 10 is pressed and mounted at a predetermined pressure so that each dummy bump 11 of the BGA 10 comes into contact with each land 6C as shown in FIG. 6C. At this time, the pressing pressure of the BGA 10 is always equal since each dummy bump 11 and each land 6C are in contact with each other.

Thereafter, the mother substrate 6 on which the BGA 10 is mounted is reflow-heated at a predetermined temperature,
The cream solder 7 is melted and each bump 2B and each land 6
Since B is electrically connected, the BGA 10 can be mounted on the motherboard 6.

(3) Operation and Effect of the Present Embodiment In the above configuration, the BGA 10 forms the dummy bumps 11 at at least four places other than on a straight line on the one surface 2A of the printed wiring board 2, and The respective lands 6C of the substrate 6 are brought into direct contact with each other, and at the same time, each bump 2B and each
The BGA 10 can be always mounted on the mother substrate 6 by pressing with uniform pressing pressure.

In this way, the BGA 10 is attached to the mother board 6
Each land is pressed more than necessary or the BGA 10 is pressed more than necessary on each land 6B by its own weight, and the cream solder 7 supplied on each land 6B is crushed more than necessary. 6
In order to prevent short-circuit failure between B beforehand and to reliably connect each bump 2B and each land 6B via the cream solder 7, even when the height of each bump 2B varies, Open failure due to bump floating can be prevented beforehand.

On the other hand, at this time, since the dummy bumps 11 are higher than the respective bumps 2B and have a melting point equivalent to the heat resistance assurance temperature of the BGA 10, the case where the reflow heating temperature is lower than the heat resistance assurance temperature of the BGA 10 is shown in FIG. As shown in FIG.
While the solidification is performed so as to float in the height direction of A10, the cream solder 7 is not supplied between each dummy bump 11 and each corresponding land 6C. I have.

On the other hand, when the reflow heating temperature is higher than the guaranteed heat resistance temperature of the BGA 10, as shown in FIG.
Since each of the dummy bumps 11 melts and joins with each of the lands 6C, there is no gap between each of the dummy bumps 11 and each of the corresponding lands 6C, and these dummy bumps 11 and each of the lands 6C contact each other. State.

Thus, in this BGA 10, it is known whether or not the heating processing temperature during the reflow heating is lower than the heat resistance assurance temperature of the BGA 10 based on whether or not the dummy bump 11 of the BGA 10 is in contact with the land 6C of the mother substrate 6 after the reflow heating. It has been made possible.

According to the above configuration, the BGA 10 forms the dummy bumps 11 in at least four places other than on a straight line on the one surface 2A of the printed wiring board 2, and the dummy bumps 11 and the lands 6C of the mother board 6 correspond to each other. By mounting the BGA 10 on the mother board 6 so as to be in contact with the mother board 6, the BGA 10 can always be pressed on the mother board 6 with an even pressing pressure, and the weight of the BGA 10 or the pressing of the BGA 10 on the mother board 6 more than necessary can be achieved. Short failure between the lands 6B can be prevented beforehand, and even when the height of each bump 2B varies, the bump 2B and each land 6B are securely connected. Can be prevented beforehand, and thus the connection reliability can be sufficiently improved in practical use. It is possible to realize a 10.

(4) Other Embodiments In the above-described embodiment, the case where the material of the dummy bumps 11 as the support means is formed using Sn-Ag based solder has been described. The invention is not limited to this, but the point is that the melting point is higher than that of bump 2B and BG
As long as the material is equivalent to the heat-resistant guaranteed temperature of A10, the material of the dummy bump 11 can be widely applied to the case where various materials such as Sn—Sb are used.

In the above-described embodiment, the case where the dummy bumps 11 are formed at the four corners on the one surface 2A of the printed wiring board 2 has been described. However, the present invention is not limited to this, and As long as the dummy bumps 11 are formed at at least four places other than on a straight line on the one surface 2A of the plate 2, the present invention can be widely applied to the case where the dummy bumps 11 are formed at various other positions.

Further, in the above-described embodiment, the case has been described where the dummy bumps 11 are formed in the same shape as the bumps 2B. However, the present invention is not limited to this, and the point is that the dummy bumps 11 have the same dimensions as the height of the bumps 2B. If there is, the shape of the dummy bump 11 is, for example, a cube having the same dimensions as the height of the bump 2B, such as the dummy bump 21 of the BGA 20 shown in FIG. The present invention can be widely applied to the case of forming using various shapes.

Further, in the above-described embodiment, the case where the dummy bumps 11 are formed by using the screen transfer method has been described. However, the present invention is not limited to this.
The method for forming the dummy bumps 11 can be widely applied to the case where the dummy bumps 11 are formed by using various forming methods such as the plating method.

Further, in the above-described embodiment, a case has been described in which the BGA 10 is used as the surface-mounted electronic component. However, the present invention is not limited to this, and in other words, a plurality of electrodes are formed on one surface. In addition, various surface-mounted electronic components such as an LGA (land grid array) 30 as shown in FIG. 4B can be used as the surface-mounted electronic component.

Further, in the above-described embodiment, after the reflow heating, a slight gap is formed between each dummy bump 11 and the corresponding land 6C of the mother substrate 6, so that the reflow heating temperature is lower than that of the BGA 10. Although the case in which it is possible to confirm whether the temperature is lower than the heat-resistance guaranteed temperature has been described, the present invention is not limited to this, and the point is that each dummy bump 1
1 and the corresponding lands 6C of the motherboard 6 contact with each other, so that it can be confirmed that the reflow heating temperature is higher than the heat resistance assurance temperature of the BGA 10; A current flows when each of the inspection bumps comes into contact with each of the inspection lands corresponding thereto as an inspection bump, and this current allows the reflow heating temperature to be confirmed to be higher than the heat resistance guaranteed temperature of the BGA 10. Various configurations such as cases can be widely applied.

[0039]

As described above, according to the present invention, a plurality of first projecting electrodes made of a first conductive material are provided on one surface of a surface-mounted electronic component. At least at three or more positions, a plurality of second projection electrodes are provided at the same height as each first projection electrode using a second conductive material having a higher melting point than the first conductive material. By doing so, it is possible to stably mount the semiconductor device in a predetermined state by the second protruding electrode when mounting it on the mother board, and thus a surface mount electronic component capable of sufficiently improving the reliability of connection practically. Can be realized.

According to the present invention, as described above, a method of mounting a surface mount electronic component having a plurality of first protruding electrodes made of a first conductive material on one surface is provided on a surface of the same straight line. A plurality of second protruding electrodes are formed at at least three or more positions where the second protruding electrodes are at the same height as each first protruding electrode using a second conductive material having a higher melting point than the first conductive material. A first step to be performed, the respective electrodes of a mother board provided with a plurality of electrodes on one surface corresponding to the first and second projection electrodes, respectively, and the first and second projections of a surface mount type electronic component. By providing the second step for electrically connecting the electrodes to each other, it is possible to stably mount in a predetermined state by the second protruding electrodes when mounting on the mother board, and thus the connection can be established. Table that can sufficiently improve reliability in practical use Mounting method of mounting electronic components can be achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a BGA according to the present embodiment.

FIG. 2 is a cross-sectional view showing a procedure for mounting a BGA according to the present embodiment.

FIG. 3 is a partial cross-sectional view showing a configuration of mounting a BGA and a mother board according to the present embodiment.

FIG. 4 is a partial cross-sectional view showing a configuration of a surface-mounted electronic component according to another embodiment.

FIG. 5 is a cross-sectional view showing a configuration of a conventional BGA.

FIG. 6 is a cross-sectional view showing a conventional BGA mounting procedure.

FIG. 7 is a partial cross-sectional view showing a configuration of mounting a conventional BGA and a mother board.

[Explanation of symbols]

1, 10, 20 ... BGA, 2 ... printed wiring board, 2
A: One side, 2B: Bump, 2C: Other side, 2D:
Pad 3, semiconductor chip 4, wire 5, sealing resin 6, mother board 6A mounting surface 6B, 6
C: land, 7: cream solder, 11, 21, 3
1 ... Dummy bump, 30 ... LGA.

Claims (6)

[Claims] 1. A surface-mounted electronic component provided with a plurality of first protruding electrodes made of a first conductive material on one surface, wherein at least three or more positions are not on the same straight line on the one surface. A plurality of second projecting electrodes each provided at the same height as each of the first projecting electrodes using a second conductive material having a higher melting point than the first conductive material. Mountable electronic components. 2. A semiconductor chip having a plurality of first electrodes provided on one surface thereof, and a plurality of second electrodes provided on one surface thereof respectively corresponding to the first electrodes of the semiconductor chip. A conversion substrate provided on the other surface so as to correspond to each of the second electrodes so that each of the first projection electrodes is electrically connected to the corresponding one of the second electrodes; A conductive connection means for conductively connecting the first electrode and the corresponding second electrode of the conversion substrate; and a sealing resin for integrally sealing the semiconductor chip and the conductive connection means. The surface-mounted electronic component according to claim 1, wherein the conductive material has a melting point equivalent to the melting point of the sealing resin. 3. The surface-mounted electronic component according to claim 1, wherein the second protruding electrodes are formed at four corners of the other surface. 4. A method for mounting a surface-mounted electronic component having a plurality of first projecting electrodes made of a first conductive material on one surface, wherein at least three or more locations not on the same straight line on the one surface are provided. A first step of forming a plurality of second projection electrodes at the same height as each of the first projection electrodes using a second conductive material having a higher melting point than the first conductive material. And a plurality of electrodes on a mother substrate provided with a plurality of electrodes on one surface respectively corresponding to the first and second protruding electrodes;
A second step of electrically connecting the first and second protruding electrodes of the surface-mounted electronic component to each other. 5. The surface-mounted electronic component according to claim 1, wherein a plurality of first electrodes are provided on one surface of the semiconductor chip, and a plurality of first electrodes of the semiconductor chip are provided on one surface corresponding to the first electrodes. A conversion substrate provided with a second electrode and provided on the other surface so that each of the first protruding electrodes is electrically connected to the corresponding second electrode in correspondence with each of the second electrodes. Conductive connecting means for conductively connecting each of the first electrodes of the semiconductor chip and the corresponding second electrode of the conversion substrate; and sealing for integrally sealing the semiconductor chip and the conductive connecting means. 5. The surface-mounted electronic component according to claim 4, wherein the first step uses a conductive material having a melting point equivalent to that of the sealing resin in the first step. How to implement. 6. The method according to claim 4, wherein in the first step, the second protruding electrodes are formed at four corners of the other surface.