JP2001127111A - Mounting substrate for semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability for mounting BGA or flip-chip connecting structure. SOLUTION: A plurality of metal electrodes 3 is provided on the lower side of a BGA package sealing a semiconductor therein, and a solder ball with a 500 μm diameter D is connected to each of the metal electrodes 3. A metal wiring 13 of 700 μm height H1 and 250 μm width W1 is formed protruded to the side of the BGA package 1 on a mounting surface 11a of a mounting substrate 11 in its position corresponding to each of the solder ball 5 in the BGA package 1. The solder balls in relation to metal wirings 9 are connected to each of the metal wiring 9. Even though stress is generated due to difference in coefficient of thermal expansion between the BGA package 1 and the mounting substrate 11 on mounting or after mounting, deformation of the metal wiring 13 can absorb the stress.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting board for a semiconductor device in which a plurality of ball-shaped connecting terminals are connected to a lower surface of a semiconductor device and metal wiring is connected to the semiconductor device and the semiconductor device is surface-mounted. It is. More specifically, B
The present invention relates to a mounting substrate used for connection of a semiconductor device mounted with a GA (Ball Grid Array, US Pat. No. 5,148,265) and flip-chip connection.

[0002]

2. Description of the Related Art At present, as a semiconductor device having connection terminals such as solder balls on the lower surface of a package in which a semiconductor chip is sealed, a BGA or a μBGA (a BGA having a terminal pitch of 0.8 mm or less, a CSP (Chip Scale Package)). )). A mounting structure using a BGA or μBGA (hereinafter referred to as a BGA mounting structure) is a QFP (Quad Flat Pa) in which a plurality of leads are taken out from the periphery of a package.
In this case, the mounting area can be reduced as compared with the case where the ckage is mounted.

FIG. 1A is a sectional view showing a conventional mounting board, and FIG. 1B is a sectional view showing a BGA mounting structure using the mounting board. In a BGA package 1 in which a semiconductor chip is sealed, a plurality of metal electrodes 3 are provided on a lower surface 1a, and each metal electrode 3 has a solder ball 5 as a connection terminal.
Are connected respectively. A metal wiring 9 is provided on a mounting surface 7 a of the mounting board 7 facing the BGA package 1 at a position corresponding to each solder ball 5 of the BGA package 1. The thickness of the metal wiring 9 is, for example, 18 μm or 50 μm, which is used as the material thickness of the JIS standard,
Each of the thicknesses is smaller than the ball diameter of the solder ball 5. The corresponding solder balls 5 are connected to the respective metal wires 9.

As a mounting structure for realizing high-density mounting, there is a flip-chip connection structure in which an active element surface of a semiconductor chip is directly connected to a mounting substrate via connection terminals such as solder balls. The flip-chip connection structure is also suitable for high-density mounting, since the mounting area can be reduced similarly to the BGA mounting structure.

[0005]

However, in the BGA mounting structure, when the package is mounted on a mounting substrate such as glass epoxy, a stress is generated due to a difference in thermal expansion coefficient between the package and the mounting substrate, and the stress is generated by the metal wiring. It is generally known that cracks are generated in the connection terminals in the vicinity of the connection portions of the connection terminals, resulting in poor connection. It is generally known that even in the flip-chip connection structure, a stress is generated due to a difference in thermal expansion coefficient between the semiconductor chip and the mounting substrate, and a crack occurs in the connection terminal to cause a bonding failure.

In order to avoid such problems, Japanese Patent Application Laid-Open No. 09-129789 and Japanese Patent Application Laid-Open No. 09-199540
And Japanese Patent Application Laid-Open No. H10-173006 disclose inventions for improving reliability after connection. However, the structure, size, and shape of connection terminals (such as solder balls) are characterized by The connection portion of the connection terminal (solder ball or the like) is formed in a concave shape, and the problem is solved by giving a characteristic to the package, and the effect is obtained by giving the characteristic only to the mounting board. Not something.

Accordingly, the present invention provides a BGA mounting structure or a flip-chip connection structure in which a wiring structure of a mounting substrate is characterized by a stress caused by a difference in thermal expansion coefficient after mounting a package or a semiconductor chip on the mounting substrate. And to improve the reliability after mounting.

[0008]

According to the present invention, there is provided a mounting board for a semiconductor device in which a plurality of ball-shaped connecting terminals are connected to a lower surface of the semiconductor device and the metal wiring is connected to the semiconductor device and the semiconductor device is surface-mounted. The thickness of the metal wiring is greater than the height of the connection terminal before connection at least at a position where the connection terminal is connected.

At least at the position where the connection terminal is connected, the thickness of the metal wiring is equal to or greater than the height of the connection terminal before connection. Absorbs the stress caused by the difference in the coefficient of thermal expansion. As a result, it is possible to prevent stress from being concentrated near the joint between the connection terminal and the metal wiring, and it is possible to suppress fatigue damage of the connection terminal.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS It is preferable that the semiconductor device further includes a support member that projects toward the semiconductor device with a dimension not less than the height of the connection terminal before connection and supports the lower surface of the package of the semiconductor device. As a result, even if the metal wiring does not reach the electrode of the semiconductor device in the connected state, the gap can be filled with the connection terminal itself, so that the stress can be absorbed even if the thickness of the metal wiring is reduced. become able to.

[0011] At least a part of the metal wiring is projected toward the semiconductor device with a dimension larger than the thickness of the metal wiring,
It is preferable that the distal end portion further includes a guide member having a guide surface inclined so that the height decreases toward the connection terminal. As a result, the alignment accuracy at the time of mounting can be relaxed and the mountability can be improved.
It is preferable that a guide surface that is inclined so that the height decreases toward the connection terminal side is formed at a tip portion of the support member. As a result, the support member can also serve as the guide member.

[0012]

FIG. 2 is a sectional view showing an example in which one embodiment is applied to a BGA mounting structure. FIG. 2A shows a mounting substrate, and FIG. 2B shows a BGA mounting structure. BGA sealed semiconductor chip
A plurality of metal electrodes 3 are provided on the lower surface 1a of the package 1, and each metal electrode 3 has a solder ball 5 as a connection terminal.
Are connected respectively. Diameter D of solder ball 5
Is, for example, 500 μm. The solder balls 5 are connected to the metal electrodes 3 by, for example, being supplied to the metal electrodes 3 in advance and passing through a reflow furnace so that the solder balls 5 are melted.

The mounting board 11 includes the BGA package 1
A metal wiring 13 is provided at a position corresponding to each solder ball 5 of the BGA package 1 on the mounting surface 11a opposed to the BGA package 1 so as to protrude toward the BGA package 1 side. Metal wiring 13
Is made of Cu, Au, Ni, Al, or the like, and has a rectangular shape, for example, and a height (thickness) H1 of 700 μm.
m, and the width W1 is 250 μm. On the mounting surface 11a of the mounting substrate 11, a wiring pattern (not shown) connected to the metal wiring 13 is formed.

As shown in FIG. 2B, corresponding solder balls 5 are connected to the respective metal wirings 13. The solder balls 5 are melted and connected to the metal wires 13 by passing through a reflow furnace, for example, in a state where the solder balls 5 are positioned on the corresponding metal wires 13 of the mounting board 11 in advance.

With such a structure, even if stress is generated due to a difference in the coefficient of thermal expansion between the BGA package 1 and the mounting substrate 11 during or after mounting, the metal wiring 13 is deformed to absorb the stress, and It is possible to prevent stress from being concentrated only at the joint between the ball 5 and the metal electrode 3 or the metal wiring 13, thereby preventing cracks in the solder ball 5 caused by the stress and improving mounting reliability. Can be.

FIG. 3 is a sectional view showing an example in which another embodiment is applied to a BGA mounting structure.
(B) shows a BGA mounting structure. The mounting board 15 is provided on the mounting surface 15a of the mounting surface 15a facing the BGA package 1.
At the position corresponding to each solder ball 5 of the package 1, a metal wiring 17 similar to that of FIG. 2 is provided so as to protrude toward the BGA package 1. The height H2 of the metal wiring 17 is 300 μm
And the width W2 is 300 μm.

The BGA package 1 is supported on the mounting surface 15a of the mounting board 15 with a space between the mounting board 15 and the mounting board 15 during mounting, and the degree of freedom of approach of the BGA package 1 to the mounting board 15 is suppressed. A plurality of support members 19 are provided to protrude toward the BGA package 1. Support member 19
Is made of the same material as the mounting substrate 15 or an insulating material such as a resist material.
Is 600 μm, and the width W3 is 200 μm.

The corresponding solder balls 5 are connected to the respective metal wirings 17 as shown in FIG. The solder balls 5 are passed through a reflow furnace in a state where the lower surface 1a of the BGA package 1 is supported on the upper end surface of the support member 19 and positioned on the corresponding metal wiring 17 of the mounting board 11, so that the solder balls 5 Molten metal wiring 1
7 is connected. Although the height H2 of the metal wiring 17 is lower than the height H1 of the metal wiring 13 in FIG. 2, the BGA package 1 is held at a predetermined distance from the mounting board 15 by the supporting member 19 having a height H3. By supporting the lower surface 1a, the solder ball 5 having a constant thickness can be interposed between the metal wiring 17 and the metal electrode 3.

By adopting such a structure, even when a stress is generated due to a difference in thermal expansion coefficient between the BGA package 1 and the mounting board 15 during mounting, the metal wiring 17 and the solder ball 5 are deformed to absorb the stress, and It is possible to prevent stress from being concentrated only at the joint between the solder ball 5 and the metal electrode 3 or the metal wiring 17, thereby preventing cracking of the solder ball 5 due to the stress and improving mounting reliability. be able to. In this embodiment, the support members 19 as the support members are provided between the metal wirings 17, respectively. However, the shape, arrangement and number of the support members are not limited to these, and the support members 19 may be disposed between the metal wirings 17 and 17. Any shape, arrangement, and number may be used as long as the structure can support the lower surface of the package while maintaining a predetermined interval.

FIGS. 4A and 4B are cross-sectional views showing an example in which still another embodiment is applied to a BGA mounting structure. FIG. 4A is a mounting board, and FIG. 4B is a mounting board before mounting a BGA package.
4 shows a GA package. The mounting substrate 21 has a metal wiring 23 similar to that of FIG. 2 protruding toward the BGA package 1 at a position corresponding to each solder ball 5 of the BGA package 1 on a mounting surface 21 a facing the BGA package 1. . The height H4 of the metal wiring 23 is 700 μm,
The width W4 is 250 μm.

On the mounting surface 21a of the mounting board 21, a plurality of guide members 25 which approach the metal wiring 23 and guide the solder balls 5 to the front ends of the corresponding metal wiring 23 during mounting are provided with BGs.
It protrudes from the A package 1 side. The guide member 25 is made of the same material as that of the mounting substrate 21 or an insulating material such as a resist material. The shape of the guide member 25 is chamfered from the front end surface to the side surface facing the metal wiring 23 and the guide surface 25 is formed.
a is formed, the height H5 is 600 μm, and the width W5 is 500 μm.

At the time of mounting the BGA package 1, the solder balls 5 are melted by passing through a reflow furnace while being positioned on the corresponding metal wirings 23 of the mounting board 21, and are connected to the metal wirings 23. Is done. At the time of the positioning, even if the position of the solder ball 5 is shifted with respect to the metal wiring 23, the solder ball 5 is positioned on the corresponding metal wiring 23 by the guide surface 25a of the guide member 25, so that the alignment accuracy is eased. As a result, the mountability can be improved. At this time, it is preferable to provide a space of about 100 μm between the metal wiring 23 and the guide member 25 in advance so that the metal wiring 23 and the guide member 25 do not contact each other. Thereby, the absorption of stress due to the difference in the coefficient of thermal expansion after mounting is performed smoothly. In this embodiment, the guide members 25 are provided between the metal wirings 23, 23. However, the shape, arrangement and number of the guide members 25 are not limited to these, and the connection terminals correspond to those of the mounting board. Any shape, arrangement, and number may be used as long as it can be guided to the metal wiring.

FIGS. 5A and 5B are cross-sectional views showing an example in which still another embodiment is applied to a BGA mounting structure. FIG. 5A shows a mounting substrate, and FIG. 5B shows a BGA mounting structure. The mounting board 27
B of the mounting surface 27a facing the BGA package 1
At the position corresponding to each solder ball 5 of the GA package 1, the same metal wiring 29 as that of FIG. 2 is provided so as to protrude toward the BGA package 1. The height H6 of the metal wiring 29 is 300
μm, and the width W6 is 300 μm. Mounting board 27
A wiring pattern (not shown) connected to the metal wiring 29 is formed on the mounting surface 27a.

The BGA package 1 is supported on the mounting surface 27a of the mounting board 27 with a space between the mounting board 27 and the mounting board 27 during mounting, and the degree of freedom of approach of the BGA package 1 to the mounting board 27 is suppressed. In addition, a plurality of support / guide members 31 for guiding the solder balls 5 to the tips of the corresponding metal wirings 29 are provided so as to protrude toward the BGA package 1. The supporting / guiding member 31 is made of the same material as the mounting substrate 27 or an insulating material such as a resist material. For example, the shape of the supporting / guiding member 31 is chamfered from an end surface toward a side surface facing the metal wiring 29 to form a guide surface 31a. Is rectangular,
The height H7 is 600 μm and the width W7 is 500 μm.

Each metal wiring 29 is connected to a corresponding solder ball 5. The solder balls 5 are passed through a reflow furnace with the lower surface 1a of the BGA package 1 supported on the upper end surface of the support / guide member 31 and positioned on the corresponding metal wiring 29 of the mounting board 27. 5 is melted and connected to the metal wiring 29.
At the time of the positioning, the position of the solder ball 5 is
9, the solder balls 5 are positioned on the corresponding metal wirings 29 by the guide surfaces 31a of the support / guide members 31, so that the alignment accuracy can be relaxed and the mountability can be improved.

The shape, arrangement and number of the supporting / guiding members 31 are not limited to those in this embodiment, and the connection terminals can be guided to the corresponding metal wiring on the mounting board and have a predetermined distance from the mounting board. Any shape, arrangement, and number may be used as long as it can hold the lower surface of the package while holding the.

In these embodiments, only the portion of the metal wiring of the mounting board corresponding to the solder ball protrudes toward the package. However, all of the metal wiring may protrude.
Other portions may protrude as long as the portion corresponding to the solder ball protrudes. Also, these embodiments are based on BG
Although it is applied to the A mounting structure, it can be applied to a flip chip mounting structure.

[0028]

According to the present invention, there is provided a mounting board for a semiconductor device in which a plurality of ball-shaped connecting terminals are connected to a lower surface of the semiconductor device and the metal wiring is connected to the semiconductor device. A mounting board, the metal wiring of which is
At least at the position where the connection terminal is connected, the thickness is equal to or greater than the height of the connection terminal before connection, and the metal wiring is deformed, which is caused by a difference in thermal expansion coefficient between the package or the semiconductor chip and the mounting substrate. Since the stress is absorbed and the stress due to the difference in thermal expansion coefficient after mounting the package or semiconductor chip on the mounting board is dispersed, the stress is prevented from being concentrated near the joint between the connection terminal and the metal wiring. In addition, fatigue damage of the connection terminal can be suppressed, and reliability after mounting can be improved.

Furthermore, if a supporting member is provided which protrudes toward the semiconductor device with a dimension not less than the height of the connection terminal before connection and supports the lower surface of the package of the semiconductor device, the metal wiring in the connected state is provided. Even if the electrode does not reach the electrode of the semiconductor device, the space therebetween can be filled with the connection terminal itself, so that stress can be absorbed even if the thickness of the metal wiring is reduced. Further, a guide surface that protrudes toward the semiconductor device with a dimension larger than the thickness of the metal wiring around at least a part of the metal wiring, and has a guide surface that is inclined at the tip portion so that the height decreases toward the connection terminal side. If the formed guide member is further provided, the alignment accuracy at the time of mounting can be relaxed and the mountability can be improved. Furthermore, if a guide surface that is inclined so as to decrease in height toward the connection terminal side is formed at the distal end portion of the support member, the support member can also serve as the guide member.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view showing a conventional mounting board,
(B) is a sectional view showing a BGA mounting structure using the mounting substrate.

FIGS. 2A and 2B are cross-sectional views showing an example in which one embodiment is applied to a BGA mounting structure, wherein FIG. 2A shows a mounting substrate and FIG. 2B shows a BGA mounting structure.

3A and 3B are cross-sectional views illustrating an example in which another embodiment is applied to a BGA mounting structure, wherein FIG. 3A is a mounting board, and FIG.
The mounting structure is shown.

4A and 4B are cross-sectional views illustrating an example in which still another embodiment is applied to a BGA mounting structure, wherein FIG. 4A illustrates a mounting substrate, and FIG. 4B illustrates a mounting substrate and a BGA package before mounting a BGA package.

5A and 5B are cross-sectional views showing an example in which still another embodiment is applied to a BGA mounting structure, wherein FIG. 5A shows a mounting substrate, and FIG. 5B shows a BGA mounting structure.

[Explanation of symbols]

 Reference Signs List 1 BGA package 1a Lower surface of BGA package 3 Metal electrode 5 Solder ball 7, 11, 15, 21, 27 Mounting substrate 7a, 11a, 15a, 21a, 27a Mounting surface 9, 13, 17, 23, 29 Metal wiring 19 Support member 25 guide member 31 support / guide member

Claims (4)

[Claims] 1. A mounting board for a semiconductor device in which a plurality of ball-shaped connection terminals are connected to a connection terminal of a semiconductor device and a metal wiring is connected to a lower surface of the semiconductor device, and wherein the semiconductor device is surface-mounted. A mounting board for a semiconductor device, wherein a thickness of the connection terminal is higher than a height of the connection terminal before connection at a position where the connection terminal is connected. 2. The semiconductor device according to claim 1, further comprising a support member projecting toward the semiconductor device with a dimension not less than the height of the connection terminal before connection, and supporting a lower surface of a package of the semiconductor device.
The mounting board according to 1. 3. The semiconductor device protrudes around at least a part of the metal wiring with a dimension larger than the thickness of the metal wiring toward the semiconductor device, and has a tip portion having a height decreasing toward the connection terminal. 3. The mounting board for a semiconductor device according to claim 1, further comprising a guide member having a guide surface inclined as described above. 4. The mounting board for a semiconductor device according to claim 2, wherein a guide surface inclined so as to decrease in height toward the connection terminal is formed at a tip portion of the support member.