JP2003031614A - Semiconductor device, semiconductor module and method of mounting the device and the module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the occurrence of erroneous mounting of a semiconductor device and semiconductor module. SOLUTION: A first solder ball 13 and a second solder ball 14 of different fusing points are joined to each connecting electrode 12 provided at the rear surface of a semiconductor package 11 of the semiconductor device 10. The first solder ball 13 of lower fusing point is provided in the external circumferential side of the semiconductor device 10, while the second solder ball 14 of higher fusing point in the internal circumferential side. A contact point 22 is provided on a base substrate 21, the semiconductor device 10 is allocated on a mounting substrate 20 in which solder paste 23 is printed on the contact point 22, and a reflow soldering process is conducted in which the semiconductor device 10 is heated up to a first temperature at which the first solder ball 13 is fused and is then heated up to a second temperature at which the second solder ball 14 and solder paste 23 are fused.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device in which a solder ball is provided on a connecting electrode on the mounting surface side, a semiconductor device is mounted on one surface side, and a solder ball is provided on a connecting electrode on the other surface side. And a mounting method for these.

[0002]

2. Description of the Related Art In recent years, the trend toward smaller and lighter electronic devices has become more and more remarkable, and the electronic components used, especially semiconductor devices, are highly integrated, the signal processing speed is increased, and the memory capacity is increased. While higher performance has been achieved, efforts have been made to reduce the size of components and the component mounting area on the mounting substrate to be small with the miniaturization of electronic devices.

Conventionally, as a package shape of a semiconductor device, a lead wire serving as a connecting electrode is often drawn out in a gull wing shape from the side surface of the package like a QFP (Quad Flat Package).
GA (Ball Grid Array), LGA (Land Grid Arra)
y), LCC (Landless Chip Carrier), QFN (Quad
Semiconductor devices in which a connection electrode is provided on the lower surface or the side surface of a package such as a Flat No Lead Package) have been widely used.

In the semiconductor device as described above, since the mounting area on the mounting board can be reduced, the electric wiring of the mounting board can be shortened and the electrical characteristics of the circuit can be improved.

Now, the above-mentioned BGA type semiconductor device and a method of mounting the semiconductor device on a mounting board will be described with reference to the drawings. The semiconductor device 50 is shown in FIG.
As shown in FIGS. 3 and 14, a plurality of connection electrodes 52 are provided on the back surface of a semiconductor package 51 having a semiconductor chip made of a semiconductor element, and solder balls 53 are provided on each connection electrode 52. As shown in FIGS. 15 and 16, the mounting substrate 60 is provided with a plurality of contacts 62 on the mounting surface of the base substrate 61.

First, as shown in FIG. 17, the base substrate 6
The solder paste 63 is printed on the first contact 62. next,
As shown in FIG. 18, the solder paste 63 and the solder balls 5
The semiconductor device 50 is bonded onto the mounting substrate 60 such that the semiconductor device 50 and the semiconductor device 3 face each other.

Next, as shown in FIG. 19, the mounting board 60 to which the semiconductor device 50 is bonded is overheated to a predetermined temperature in a reflow furnace, so that the solder balls 53 and the solder paste 63 are collectively melted, After that, so-called reflow soldering for re-solidifying is performed.

[0008]

However, with the miniaturization of the package of the semiconductor device and the external dimensions approaching the size of the semiconductor chip, the pitch of the BGA type connection electrodes is narrowed to 0.8 mm and 0.5 mm. If the pitch of the connection electrodes becomes narrower, it is necessary to increase the positional accuracy of printing the solder paste on the connection electrodes of the mounting board.
In addition, it is necessary to increase the mounting accuracy of the semiconductor device by the mounting machine.

In the reflow soldering process, as described above, when the solder ball and the solder paste are heated, the solder paste and the solder ball are melted and integrated. However, as shown in FIGS. 20 to 22, when the printing position of the solder paste 63 or the mounting position of the semiconductor device 50 is not appropriate, the solder balls 53 do not attract the molten solder paste 63 to which they are originally connected, An erroneous mounting occurs in which the mounting position of the semiconductor device 50 deviates due to attracting the molten solder paste 63 in an erroneous position such as in an adjacent row.

With the need to reduce the environmental load, lead-free solder balls, solder paste, other electronic components, and connection electrodes are being promoted. Due to the lead-free solder balls and solder paste, their melting points are raised, and the temperature in the reflow soldering process is also raised in order to melt them. In a difficult situation where it is necessary to suppress heat damage to a semiconductor device or each component or oxidation of solder paste due to a temperature rise in the reflow soldering process, a simple erroneous mounting prevention method has been demanded.

The present invention has been made in view of the above-mentioned problems, and it is possible to prevent erroneous mounting between a semiconductor device and a semiconductor module and a mounting board and to mount them properly. It is an object to provide modules and a method of mounting these.

[0012]

A semiconductor device according to the present invention comprises a semiconductor package having a plurality of connection electrodes on a mounting surface side, the connection electrodes being electrically connected to contacts provided on a substrate. Each connection electrode is provided with a plurality of types of solder balls having different melting points.

Further, the semiconductor device mounting method according to the present invention is a semiconductor device provided with a semiconductor package having a plurality of connection electrodes electrically connected to contacts provided on a substrate on the mounting surface side. A mounting method, which comprises a step of providing a plurality of types of solder balls having different melting points on the connection electrodes, a step of heating and melting the solder balls to connect the connection electrodes and the contacts, and a step of heating and melting the solder balls. Are characterized in that they are heated and melted in order from a solder ball having a low melting point.

Further, in the semiconductor module according to the present invention, a plurality of connection electrodes electrically connected to the contacts provided on the second substrate are provided on the mounting surface side of the first substrate. The semiconductor device is provided on the other surface side of the substrate, and a plurality of types of solder balls having different melting points are provided on the plurality of connection electrodes.

Further, in the semiconductor module mounting method according to the present invention, a plurality of connection electrodes electrically connected to the contacts provided on the second substrate are provided on the mounting surface side of the first substrate. A method of mounting a semiconductor module including a semiconductor device on the other surface side of the first substrate, the step of providing a plurality of types of solder balls having different melting points on connection electrodes,
A step of heating and melting the solder ball to connect the connection electrode and the contact, and the step of heating and melting the solder ball is characterized in that the solder balls having a lower melting point are sequentially heated and melted.

As described above, according to the present invention, when mounting a semiconductor device on a substrate or mounting a semiconductor module on a substrate, a plurality of types of solder balls having different melting points are used and the melting point is low. Melt the solder balls first,
By melting the high melting point solder balls later,
Correct the mounting position deviation.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is applied to the case where a semiconductor device is mounted on a mounting board and will be described in detail with reference to the drawings.

As shown in FIGS. 1 and 2, the semiconductor device 10 includes a semiconductor package 11 containing a semiconductor chip made of a semiconductor element and a plurality of connection electrodes serving as electrodes for electrically connecting to the semiconductor chip. 12 and a first solder ball 13 and a second solder ball 14 attached to each connection electrode 12 and having different melting points.

The semiconductor package 11 is made of, for example, an insulating material such as ceramics or resin,
Various semiconductor chips such as CPU, RAM and ROM are packaged.

Each connection electrode 12 is a semiconductor package 11.
Are arranged in a grid on the back surface, that is, the mounting surface, and each connection electrode 12 functions as a terminal of the semiconductor chip.

The first solder balls 13 and the second solder balls 14 are joined to the respective connection electrodes 12 arranged on the back surface of the semiconductor package 11. The first solder ball 13 and the second solder ball 14 have different melting points, and the second solder ball 14 has a higher melting point than the first solder ball 13. There is.

Three first solder balls 13 are bonded to each of the connection electrodes 12 at the four corners of the semiconductor device 10. The first solder balls 13 are made of, for example, Su-Zn-.
A Bi-based alloy is used, and the melting point is set to 200 ° C. or lower. In this example, solidus line 187 ° C., liquidus line 197
Sn-8Zn-3Bi which is the temperature is used.

The second solder balls 14 are connected to the respective connection electrodes 12 other than the first solder balls 13 described above.
Are joined to each. The second solder ball 14 is
For example, a Sn-Ag-Cu based alloy is used, and the melting point is 220 ° C or lower. In this example, the solidus line 2
Sn-3Ag-0.5C that has a liquidus of 220 ° C at 17 ° C
u is used.

FIG. 2 is a side view of the semiconductor device 10 shown in FIG. 1, in which the connection electrodes 12 are provided on the back surface of the semiconductor package 11, and the first solder balls 13 and the second solder balls 14 are provided on the connection electrodes 12. The state of being joined is shown.

As shown in FIGS. 3 and 4, the mounting substrate 20 is an electrode for electrically connecting a base substrate 21 serving as a base and other devices (not shown) disposed on the base substrate 21. And a plurality of contact points 22 that

The base substrate 21 is, for example, a printed wiring board, and electric wiring is formed on a substrate made of an insulating material such as resin. The base substrate 21 may be a multi-layer substrate.

The contacts 22 are arranged in a grid on the surface of the base substrate 21, that is, the mounting surface.
2 are each connected to the electric wiring. Further, each contact 22 is provided at a position corresponding to the connection electrode 12 of the semiconductor device 10 described above.

When the semiconductor device 10 is mounted on the mounting board 20 using the semiconductor device 10 and the mounting board 20 as described above, the solder paste 23 is printed on the contacts 22 as shown in FIG. As shown in FIG. 6, the semiconductor device 10 is placed on the mounting substrate 20 with the first solder balls 13 and the second solder balls 14 of the semiconductor device 10 facing the solder paste 23 of the mounting substrate 20, The first solder balls 13, the second solder balls 14, and the solder paste 23 are melted and re-solidified. As a result, each connection electrode 12 and each contact 22 are electrically connected, and the semiconductor device 10 and the mounting substrate 20 are mechanically connected.

Here, it is preferable that the solder paste 23 has a melting point higher than that of the above-mentioned first solder ball 13 and substantially the same as that of the second solder ball 14. Therefore,
In the present example, the above-mentioned Sn-3Ag-0.5Cu and Sn-2.5Ag- having a solidus line of 214 ° C and a liquidus line of 221 ° C are used.
1Bi-0.5Cu or the like is used.

Hereinafter, the semiconductor device 10 is mounted on the mounting substrate 20.
A method of implementing will be described based on the flowchart shown in FIG.

First, in step S1, as shown in FIG. 5, a mask (not shown) having openings corresponding to the connection terminals 22 on a plurality of connection terminals 22 provided in a grid pattern on the base substrate 21. The base substrate 21 is covered with and the solder paste 23 is printed by squeegee or the like to form a layer of the solder paste 23 corresponding to each connection terminal 22.

Next, in step S2, as shown in FIG. 8, the first solder ball 13 and the second solder ball 1
4 and the solder paste 23 are opposed to each other, the semiconductor device 10 is installed at a corresponding position on the mounting substrate 20.

Next, in step S3, so-called preheating is performed in which the mounting substrate 20 on which the semiconductor device 10 is installed is inserted into a reflow furnace and heated to about 140 ° C. to 160 ° C.

Next, in step S4, the first
To 200 ° C. which is the temperature of This makes the first
As shown in FIG. 9, the solder ball 13 of FIG. 9 is melted and liquefied, so that the connection electrode 12 and the contact point 22 face each other exactly, that is, the arrow T ₁ direction in FIG. Apply tension.

Next, in step S5, the second
It is heated to the temperature of 250 ° C. As a result,
As shown in 0, the second solder ball 14 and the solder paste 23 are melted and connect the corresponding connection electrode 12 and the contact 22. At this time, since tension is applied to the semiconductor device 10 by the first solder balls 13, the second solder balls 14 and the solder pace 23 are melted, and at the same time, the tension causes an appropriate position, that is, FIG. Shift in the direction of the inner arrow T ₂ .

Next, in step S6, the mounting board 20 on which the semiconductor device 10 is installed is cooled to room temperature, and as shown in FIG. 11, the integrated first solder balls 13 and second solder balls 13 are formed. 14 and the solder paste 23 are solidified again. Thereby, the semiconductor device 10
Are electrically and mechanically connected to the mounting board 20 and are mounted on the mounting board 20.

As described above, the first solder balls 13 having a low melting point are first melted, and the surface tension of the liquefied first solder balls 13 applies tension to the semiconductor device 10 on the mounting substrate 20. Then, by melting the second solder balls 14 and the solder paste 23, the second solder balls 14 and the solder paste 23 are melted, and at the same time, the semiconductor device 10 is shifted by the tension, so that the connection electrodes 12 and the contact points 22 corresponding to each other are formed. Join together. Then, by cooling the mixed solder of the first solder ball 13, the second solder ball 14 and the solder paste 23, the mixed solder is re-solidified and the semiconductor device 10 can be properly mounted.

As described above, in this example, when the semiconductor device 10 is mounted on the mounting substrate 20, the semiconductor device 1
The first solder balls 1 at the four corners of the BGA provided at 0
3 and the second solder ball 14 on the inner peripheral side have different melting points,
Since the melting points of the first solder balls 13 are lower than that of the second solder balls 14, the first solder balls 13 at the four corners are first melted and a tension is generated in a direction to move the semiconductor device 10 to an appropriate position. Let Therefore, the second solder balls 14 and the solder paste 23 on the inner peripheral side are melted, and at the same time, the semiconductor device 10 is shifted in a direction of correcting the deviation, and the corresponding connection terminals 12 and 22 can be connected to each other. it can.

Further, in this example, the connection electrode 12 and the contact 22 are
It is possible to reduce erroneous mounting in which the BGA type semiconductor device 10 having a narrow width, that is, an electrode pitch is soldered to an erroneous position on the mounting substrate 20.

Further, in the present example, since the erroneous mounting of the semiconductor device 10 is reduced, the re-mounting work can be omitted, and each part is prevented from being damaged by heat in the reflow soldering process. be able to.

Further, in this example, as described above, the first solder balls 13, the second solder balls 14, and the solder paste 23 are lead-free, and the environment is concerned, and the reflow soldering process accompanying the lead-free process is performed. It is possible to suppress the temperature rise, and to suppress the oxidation of the solder paste 23 and the like by suppressing the temperature rise.

Furthermore, in this example, the metal composition of the first solder ball 13 bonded to a part of the connection electrodes 12 is different from that of the second solder ball 14 without largely changing the configuration of each part as compared with the prior art. Since the above-mentioned improvement can be made by an easy method such as differentiating, the manufacturing cost can be reduced and the reliability of the manufactured parts can be improved.

Further, in this example, the above-described improvement can be made without changing the mounting substrate 20, the material used for mounting such as the solder paste 23, and the equipment such as the reflow furnace. It is advantageous because the change in sex is small.

Further, in this example, three first solder balls 13 having a lower melting point than the second solder balls 14 are provided at four corners of the semiconductor package 11, but the first solder balls 13 are provided. The location and number are not limited, and for example, the first solder balls 13 may be provided on the entire outer circumference, or the first solder balls 13 may be provided on the inner circumference.

Although two types of solder balls are used in the above description, the same effect can be obtained by using three or more types of solder balls.

In the above description, the present invention is applied to the case where the semiconductor device 10 is mounted on the mounting board 20, but, for example, the semiconductor device and various electronic parts are mounted on one surface of the mounting board and the other surface thereof is mounted. The same can be applied to the case where the semiconductor module in which the connection electrode is provided on the side and the solder ball is provided on this connection electrode is further mounted on another mounting substrate.

[0047]

As described above, according to the present invention, a plurality of types of solder balls having different melting points are used to mount a semiconductor device or a semiconductor module on a substrate, so that the melting point of the melting point is changed in the reflow soldering process. By heating to a temperature at which a low solder ball melts, the tension of the melted solder ball generates a tension that tends to move the semiconductor device or semiconductor module to an appropriate position. Further, by heating to a temperature at which the solder ball having the highest melting point is melted, all the solder balls and the solder paste are melted, and the tension of the solder ball can return the semiconductor device to an appropriate position.

As a result, it is possible to reduce erroneous mounting of semiconductor devices and semiconductor modules by the mounting method described above and improve productivity.

Further, by reducing the erroneous mounting, it is possible to avoid the thermal damage to the semiconductor device or the semiconductor module when the semiconductor device or the semiconductor module is remounted, so that the reliability of the semiconductor device or the semiconductor module is improved. To do.

Further, the above-mentioned improvement is made possible by an easy method such as changing the metal composition of the solder balls joined to some of the connecting electrodes from the solder balls provided in the other parts without largely changing the structure of the parts. Therefore, the cost of manufacturing the parts is reduced and the reliability of the manufactured parts is improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a back surface side of a semiconductor device to which the present invention is applied.

FIG. 2 is a side view showing a schematic configuration of the same semiconductor device.

FIG. 3 is a plan view showing a schematic configuration of a mounting board.

FIG. 4 is a side view showing a schematic configuration of a mounting board.

FIG. 5 is a diagram showing a mounting procedure of the semiconductor device, and is a side view showing a state in which a solder paste is printed on the connection electrodes on the mounting substrate.

FIG. 6 is a view showing a mounting procedure of the semiconductor device, and is a side view showing a state in which the semiconductor device is arranged on the mounting substrate.

FIG. 7 is a flowchart showing a flow of mounting a semiconductor device on a mounting board.

FIG. 8 is a view showing a mounting procedure of the semiconductor device, and is a side view showing a state where the semiconductor device is arranged on the contact on the mounting substrate.

FIG. 9 is a view showing a mounting procedure of the semiconductor device, and is a side view showing a state where the mounting substrate and the semiconductor device are heated to a first temperature by a reflow furnace.

FIG. 10 is a diagram showing a mounting procedure of a semiconductor device,
It is a side view showing the state where the mounting board and the semiconductor device were heated to the second temperature by the reflow furnace.

FIG. 11 is a diagram showing a mounting procedure of a semiconductor device,
FIG. 6 is a side view showing a state where the mounting board and the semiconductor device are cooled to room temperature and each solder ball and solder paste are re-solidified.

FIG. 12 is a graph showing a temperature change with time when performing reflow soldering.

FIG. 13 is a diagram showing a schematic configuration of a back surface side of a conventional semiconductor device.

FIG. 14 is a side view showing a schematic configuration of a conventional semiconductor device.

FIG. 15 is a plan view showing a schematic configuration of a conventional mounting board.

FIG. 16 is a side view showing a schematic configuration of a conventional mounting board.

FIG. 17 is a view showing a mounting procedure of a conventional semiconductor device, and is a side view showing a state in which a solder paste is printed on a connection electrode provided on a mounting substrate.

FIG. 18 is a view showing a mounting procedure of a conventional semiconductor device, which is a side view showing a state where the semiconductor device is arranged on a mounting substrate.

FIG. 19 is a diagram showing a conventional semiconductor device mounting procedure, and is a side view showing a state in which the semiconductor device is mounted on a mounting substrate.

FIG. 20 is a view showing a mounting procedure of a conventional semiconductor device, and is a side view showing a state where a mounting position is displaced when the semiconductor device is arranged on a contact provided on a mounting substrate.

FIG. 21 is a diagram showing a mounting procedure of a conventional semiconductor device, and is a side view showing a state where a mounting substrate and a semiconductor device are heated to a predetermined temperature by a reflow furnace.

FIG. 22 is a diagram showing a conventional semiconductor device mounting procedure, in which the mounting substrate and the semiconductor device are cooled to room temperature,
It is a side view which shows the state which each solder ball and solder paste re-solidified.

[Explanation of symbols]

10 semiconductor devices, 11 semiconductor packages, 12
Connection electrode, 13 first solder ball, 14 second solder ball, 20 mounting substrate, 21 base substrate, 22
Contacts, 23 solder paste

Claims (8)

[Claims] 1. A semiconductor package having, on the mounting surface side, a plurality of connection electrodes electrically connected to contacts provided on a substrate, wherein the plurality of connection electrodes have a plurality of melting points. A semiconductor device having a kind of solder ball. 2. The semiconductor device according to claim 1, wherein the plurality of connection electrodes are provided with solder balls having a lower melting point toward the outer circumference. 3. A method for mounting a semiconductor device, comprising a semiconductor package, on a mounting surface side of which is provided a plurality of connection electrodes electrically connected to contacts provided on a substrate, wherein: The step of providing a plurality of types of solder balls having different melting points, the step of heating and melting the solder balls to connect the connection electrodes and the contacts, and the step of heating and melting the solder balls has a low melting point. A method for mounting a semiconductor device, which comprises sequentially heating and melting solder balls. 4. The method of mounting a semiconductor device according to claim 3, wherein the plurality of connection electrodes are provided with solder balls having a lower melting point toward the outer circumference. 5. A plurality of connection electrodes electrically connected to contacts provided on the second substrate are provided on the mounting surface side of the first substrate, and the semiconductor is provided on the other surface side of the first substrate. A semiconductor module comprising a device, wherein a plurality of types of solder balls having different melting points are provided on the plurality of connection electrodes. 6. The semiconductor module according to claim 5, wherein the plurality of connection electrodes are provided with solder balls having a lower melting point toward the outer circumference. 7. A mounting surface of the first substrate is provided with a plurality of connection electrodes electrically connected to contacts provided on the second substrate, and a semiconductor is provided on the other surface of the first substrate. In a method of mounting a semiconductor module including a device, the method includes the steps of providing a plurality of kinds of solder balls having different melting points on the connection electrode, and heating and melting the solder ball to connect the connection electrode and the contact. The method of mounting a semiconductor module, wherein the step of heating and melting the solder balls is performed by sequentially heating and melting the solder balls having a low melting point. 8. The method of mounting a semiconductor module according to claim 7, wherein solder balls having a lower melting point are provided on the plurality of connection electrodes toward the outer circumference.