JP2007189084A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device having a solder ball with a high arrangement and a relatively high connection strength.
A package substrate having a front surface wiring and a back surface wiring formed on a front surface and a back surface opposite to the front surface, and a semiconductor having electrodes on the surface and fixed to the surface of the package substrate. The chip 21, the bonding wire 32 that electrically connects the electrode of the semiconductor chip 21 and the surface wiring 13 of the package substrate, the sealing resin 27 that seals at least the electrode and the bonding wire 32, and the back surface wiring 15 of the package substrate 11. A ball pad 32 having an elliptical shape oriented in the first and second directions in which the long axis extension intersects each other at substantially 90 degrees and the long axis extension intersects at substantially 45 degrees with respect to the side surface of the package substrate 11; In addition, a solder ball 31 connected to the ball pad 32 is provided.
[Selection] Figure 1

Description

  The present invention relates to a semiconductor device, and more particularly to a semiconductor device having ball-shaped terminals such as a ball grid array (BGA).

  In recent years, along with demands for downsizing and thinning electronic devices, semiconductor devices that are used parts have been downsized and thinned. The downsizing and thinning are in step with the trend toward mobile electronic devices. In order to realize such miniaturization and thinning, in the BGA type semiconductor device, the ball pitch, which is the distance between the solder balls, is reduced to 0.80 mm, 0.65 mm, and further to 0.5 mm. That is, the connection area of the solder balls is reduced.

  When the ball pitch is reduced, the solder ball and the mounting land shape for mounting the solder ball are also reduced. The solder ball arrangement of a semiconductor device having a ball-like terminal such as a BGA type has a one-to-one correspondence with the high-density pattern of the mounting substrate, and the achievement of the high-density solder ball arrangement of the BGA type semiconductor device is achieved by mounting. It is also the achievement of a high density pattern on the substrate.

  Proposals have been made for securing high-density pattern wiring and connection strength of a mounting board on which a semiconductor device having ball-shaped terminals such as solder balls is mounted. For example, in the wiring pattern of the mounting board, in order to pass as many wiring patterns as possible on the same plane, compared to a conventional circular mounting land, a long axis having a circular radius extended in the direction of drawing out the wiring pattern is provided. There has been disclosed a proposal of an elliptical mounting land in which a short axis perpendicular to the vertical axis is reduced from a circle radius (see, for example, Patent Document 1). The elliptical mounting land has the same area as the conventional circular mounting land, and ensures connection reliability. Further, in the case where there is a margin in the mounting land interval, an example is shown in which the short axis is made equal to the circular radius and the long axis is extended from the circular radius to increase the connection area.

However, since the above proposal is an arrangement of mounting lands intended to pass as many wiring patterns as possible on the same plane, even if the solder balls of the semiconductor device are arranged correspondingly, the solder balls The arrangement is not necessarily close to the proximity limit, and the possibility of relative improvement in the closest and connection strength is small. That is, there is a problem that it is difficult to improve the closest arrangement and the connection strength of the solder balls of the semiconductor device requiring miniaturization.
JP 2001-230533 A (Page 6, FIGS. 4, 5)

  SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor device having a solder ball having a high arrangement and a relatively high connection strength.

  A semiconductor device according to one embodiment of the present invention includes a semiconductor chip having an electrode on a surface, a sealing resin that seals at least the electrode, and an extension of a major axis that intersects with each other at substantially 90 degrees, A conductive material exposed portion having an elliptical shape oriented in the first and second directions in which the extension of the major axis intersects at substantially 45 degrees with respect to the extended surface of the side surface of the semiconductor chip, and is connected to the conductive material exposed portion And an external connection terminal.

  According to another aspect of the present invention, there is provided a semiconductor device having a package substrate having wirings formed on a front surface and a back surface opposite to the front surface and connected to each other, an electrode on the surface, and fixed to the surface of the package substrate. The semiconductor chip, the connection means for electrically connecting the electrode and the wiring on the surface of the package substrate, the sealing resin for sealing at least the electrode and the connection means, and the wiring on the back surface of the package substrate A conductive material having an elliptical shape oriented in a first direction and a second direction in which the extension of the major axis intersects with each other at substantially 90 degrees and the extension of the major axis intersects with the side surface of the package substrate at substantially 45 degrees It has an exposed part and an external connection terminal connected to the conductive material exposed part.

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide the semiconductor device which has a solder ball with a high arrangement and a relatively high connection strength.

  Embodiments of the present invention will be described below with reference to the drawings. In each figure, the same components are denoted by the same reference numerals.

  A BGA type semiconductor device according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 shows an outline of a semiconductor device. FIG. 1A is a schematic view seen from the front direction, with a part of the semiconductor device cut away, and FIG. 1B is a plan view seen from the bottom side. . In addition, a part of boundary line which should be shown with a broken line is abbreviate | omitted and only the ball pad (32) of the back surface wiring (15) and its peripheral part are displayed. FIG. 2 is an enlarged view of a part of FIG. 1B, schematically showing the arrangement and shape when the orientation of the solder balls on the bottom surface of the semiconductor device is the same. FIG. 3 is a diagram schematically showing the arrangement and shape when the solder balls on the bottom surface of the semiconductor device have different directions.

  As shown in FIG. 1, the semiconductor device 1 includes a package substrate 11, a semiconductor chip 21, a bonding wire 25 that is a connection means, a sealing resin 27, an elliptical ball pad 32 that is an exposed portion of a conductive material, and an external A solder ball 31 as a connection terminal is provided.

  More specifically, the back surface of the semiconductor chip 21 which is formed in a substantially rectangular parallelepiped shape and is disposed so that the side surfaces thereof are parallel to each other is fixed to the surface of the package substrate 11, also called an interposer, with an adhesive 23. An electrode (not shown) on the surface side of the semiconductor chip 21 and the surface wiring 13 of the package substrate 11 are electrically connected by a bonding wire 25. The semiconductor chip 21 may be connected to the surface of the package substrate 11 face down by forming bumps on the electrode pads on the surface side.

  The surface of the package substrate 11 and the semiconductor chip 21 and the bonding wires 25 on the upper surface are sealed with a sealing resin 27. A plurality of oval ball pads 32 arranged in a grid pattern and facing in different directions are formed in the solder resist 17 formed on the back surface wiring 15 of the package substrate 11, and soldered to the ball pads 32. A ball 31 is connected. Instead of the solder balls 31, a conductive adhesive such as silver paste may be used.

  As shown in FIG. 1B, the package substrate 11 has a rectangular shape and is made of a material mainly composed of an epoxy-based resin, and has a bonding pad or the like on the surface side where the semiconductor chip 21 is mounted. The front surface wiring 13 made of, for example, copper or an alloy containing copper as a main component is disposed, and the back surface wiring 15 is disposed on the back surface facing the front surface. The front surface wiring 13 and the back surface wiring 15 are connected to a through hole formed in the package substrate 11 via a through hole wiring 14 formed by, for example, copper plating. The package substrate 11 may have a multilayer structure.

  Further, as shown in FIG. 1B, the back surface wiring 15 of the package substrate 11 is an ellipse whose major axis on the long axis direction line 37a intersects the rectangular side of the back surface of the package substrate 11 at substantially 45 degrees. It has a shape. One end of the back surface wiring 15 is connected to the through-hole wiring 14, and the other end is an opening of the solder resist 17, and an elliptical ball pad 32 having the same major axis direction is formed. After the solder is disposed, for example, after being melted, it has a shape that is almost part of an ellipsoid. Note that the solder may already be an ellipsoid when initially disposed.

  The package substrate 11 has four regions on the X axis (left and right lines in the drawing) and Y axis (up and down lines in the drawing) parallel to a rectangular side passing through the center of the back surface of the package substrate 11, that is, the upper right portion (first quadrant). ), Upper left (second quadrant), lower left (third quadrant), and lower right (fourth quadrant), and the ball pads 32 in each quadrant face the same direction. The long axis (for example, part of the long axis direction lines 37a and 37b) of the ball pad 32 in the first quadrant to the fourth quadrant is substantially 45 degrees with respect to the X axis. For example, a long axis (a part of the long axis direction line 37a) facing the first direction of the quadrant ball pad 32 and, for example, the second direction of the ball pad 32 of the second and fourth quadrants. The long axis (a part of the long-axis direction line 37b) facing is in a relationship of intersecting at substantially 90 degrees.

  Assuming that the X axis and the Y axis are the same as in a normal XY coordinate system, the intersection is the origin, the right direction and the upward direction are positive, respectively, and the long axis of the ball pad 32 in the first quadrant (long axis) The direction line 37a) intersects with the positive X axis and the positive Y axis. The arrangement of the ball pads 32 including the back surface wiring 15 in the second quadrant and the fourth quadrant is mirror-symmetrical with the arrangement of the ball pads 32 in the first quadrant, and the arrangement of the ball pads 32 in the third quadrant is The arrangement of the ball pads 32 in the first quadrant is mirror-symmetrical and centrally symmetric. The center of the distribution of the ball pads 32 in the first quadrant to the fourth quadrant coincides with the intersection of the X axis and the Y axis. The number of ball pads 32 may not be exactly the same for each quadrant. In this case, an approximate symmetrical relationship is obtained, but there is no problem.

  Next, the proximity arrangement and shape of the ball pad 32 will be described with reference to FIG. Here, for comparison, the solder ball 31 in FIG. 1 is referred to as an elliptical solder ball 31a. As shown in FIG. 2, the elliptical solder ball 31a connected to the ball pad 32 is substantially part of an ellipsoid, and is elliptical in plan view. The square 41 connecting the centers of the ball pads 32 coincides in plan view with the square connecting the centers of the elliptical solder balls 31a. The square 41 is the smallest unit of the grid arrangement of the grids. Each is parallel to the rectangular side of the package substrate 11.

  First, in order to obtain a high-density array, the semiconductor device was examined on the assumption that it has circular solder balls 45 (indicated by dotted lines) made of solder balls that are part of a substantially spherical shape. The arrangement condition of the circular solder balls 45 is to maintain a predetermined radius calculated from the distance between the ball pad 32 and the mounting substrate (not shown) when mounted, and to arrange in a grid pattern, and to set the proximity limit. For example, the closest approach within a range that does not exceed, that is, not closer than the proximity limit circle 43 (shown by a broken line). The proximity limit is the distance (ball pitch) between the solder balls that can be stably mounted on the mounting board, and is defined by the mounting conditions including the type of solder, the amount of solder, and the accuracy of the mounting device. Amount.

  Next, an arrangement of solder balls having a high connection strength is obtained, and the distance between the package substrate 11 and the mounting substrate, that is, the substantial height of the solder balls is not changed, and the conditions of separation by the proximity limit circle 43 are satisfied. The inventors have studied to maximize the solder connection strength and found that the elliptical solder ball 31a is formed. As shown in FIG. 2, the ellipsoidal solder ball 31a, which is a part of an ellipsoid, is suitable for effectively using a usable area vacant in the center of the four nearest grids (square 41). ing. Further, it is considered that the elliptical solder balls 31a are less likely to protrude in an unexpected direction when mounted on the mounting board.

  In other words, the major axis (or minor axis) of the elliptical solder ball 31a is set to the direction of the area vacant in the center of the square 41 (direction of 45 degrees to the side of the square 41). Furthermore, the ratio of the ellipse minor axis to the major axis was about 0.5, and the area of the solder connection part (ball pad 32) of the ellipsoidal solder ball 31a was increased by about 8% compared to the circular solder ball 45. The reason why the ratio of the minor axis to the major axis is about 0.5 is that when the ellipse is longer than about 0.5 and has an elongated ellipse, the ellipse may reduce the mounting stability. This is because an increase in the solder connection area is suppressed when the ellipse is closer to a circle and deviates from .5.

  Next, as shown in FIG. 3, the case where ellipses having different major axis directions are arranged close to each other was examined. Here, the difference in direction corresponds to a case where the major axis directions intersect each other at 90 degrees (first and second directions), and is represented by the positional relationship between the elliptical solder balls 31a and 31b. The positional relationship between the elliptical solder balls 31a and 31c is the same. The proximity limit distance 44 is not represented by the proximity limit circle 43 placed on the side of the square 41 but exists at the top of this side. The distance increase 51 between the elliptical solder balls 31a and 31b is about 8% compared to the distance between the elliptical solder balls 31a in the same quadrant (see FIG. 2, the length of one side of the square 41).

  Therefore, although not shown in FIG. 1, the solder balls 31 that are close to each other at the boundary between the first to fourth quadrants are arranged apart from each other by about 8%. In order to suppress this increase in distance, for example, the solder balls that are close to each other at the boundary may be circular instead of elliptical.

  In the BGA type semiconductor device 1 according to the first embodiment of the present invention as described above, the ball pad 32 of the solder ball 31 is substantially 45 degrees on the side of the rectangle whose long axis extends from the back surface of the package substrate 11. The major axis of the ball pad 32 in the first and third quadrants and the major axis of the ball pad 32 in the second and fourth quadrants are placed so as to intersect at substantially 90 degrees. As a result, the solder balls 31 can increase the solder connection area, that is, the area of the ball pad 32 by about 8% while maintaining the arrangement density of the circular solder balls 45, and the mounting strength of the semiconductor device 1 can be increased. It becomes possible. The mounting strength obtained by forming a ball pad of the same shape corresponding to the ball pad 32 of the semiconductor device 1 on the mounting substrate and connecting the semiconductor device 1 to the mounting substrate is the same as that of the semiconductor device 1 having a conventional circular ball pad. It was confirmed that it was larger than the mounting strength connected to.

  In addition, since the ball pad 32 has an elliptical shape in which the extension of the long axis intersects the rectangular side of the back surface of the package substrate 11 at about 45 degrees, the solder pad is connected in the direction of about 45 degrees to the rectangular side. The area of the parts is increased. Therefore, the solder connection strength in the direction of about 45 degrees with respect to the rectangular side is improved in the distribution of the solder connection strength in the direction in the back surface of the package substrate 11. The two directions parallel to the sides of the rectangle coincide with the arrangement direction of the grids of the ball pad 32 and have a high distribution density and a high solder connection strength, but the BGA type semiconductor according to the first embodiment of the present invention. In the apparatus 1, in addition to this, by increasing the solder connection area, the solder connection strength in the direction of about 45 degrees to the rectangular side is also enhanced. As a result, it is possible to suppress the possibility of poor connection of the semiconductor device 1, particularly in a mobile electronic device or the like where there is a risk of dropping or the like.

  A BGA type semiconductor device according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 4 is a schematic plan view seen from the bottom side of the semiconductor device. A part of the boundary line to be indicated by a broken line is omitted, and only the ball pad 32 of the back surface wiring 15 and its peripheral part are displayed. The present embodiment is different from the first embodiment in the direction of the ball pad 32 and the direction of the solder ball 31 associated therewith. In the following, the same components as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and different components are described.

  As shown in FIG. 4, on the bottom surface of the package substrate 61, when divided into four quadrants along the X axis and the Y axis as in the first embodiment, the individual back surface wirings 15, internal wirings 14, and ball pads 32 in the first quadrant. The configuration of the solder balls 31 is the same as that of the second quadrant of FIG. Similarly, when FIG. 4 is compared with FIG. 1B, the configuration of the second quadrant of FIG. 4 is changed to the configuration of the first quadrant of FIG. 1B except for the vicinity of the boundary between quadrants. The configuration of the third quadrant corresponds to the configuration of the fourth quadrant of FIG. 1B, and the configuration of the fourth quadrant of FIG. 4 corresponds to the configuration of the third quadrant of FIG.

  Assuming the X axis and Y axis of the package substrate 61 as in a normal XY coordinate system, the intersection point is the origin, the right direction and the upward direction are positive, and the extension of the long axis of the ball pad 32 in the first quadrant ( The long-axis extension line 37) intersects at the X-axis positive and Y-axis negative, or the X-axis negative and Y-axis positive, or the origin. The arrangement relationship of the ball pads 32 in the second quadrant to the fourth quadrant with respect to the first quadrant is the same as that in the first embodiment.

  In the BGA type semiconductor device (not shown) according to the second embodiment of the present invention as described above, the ball pad 32 of the solder ball 31 and the long axis extending to the rectangular side on the back surface of the package substrate 61 are about 45 respectively. The major axes of the ball pads 32 in the first and third quadrants and the major axes of the ball pads 32 in the second and fourth quadrants are placed so as to intersect at 90 degrees. As a result, the BGA type semiconductor device of the present embodiment can obtain the same effects as the semiconductor device 1 of the first embodiment.

  Further, the direction of the major axis of the ball pad 32 tends to be concentrated in the center direction of the back surface of the package substrate 61 as compared with the package substrate 11 of the first embodiment. As a result, the solder connected to the ball pad 32 is more resistant to thermal stress due to repeated heating and cooling. That is, it is known that thermal stress generated by repeated heating and cooling in a mounted semiconductor device causes poor connection such as cracking or peeling in the solder connected to the package substrate. Is often present in the back surface of the package substrate, particularly in the center or near the center thereof, and the direction of the major axis of the ball pad 32 is directed to the direction of the deformation center or a direction parallel thereto to increase the solder connection area in this direction. Doing so suppresses the influence of thermal stress.

  As mentioned above, although the Example of this invention was described, this invention is not limited to the said Example, It can implement in various deformation | transformation within the range which does not deviate from the summary of this invention.

  For example, in the embodiment, an example in which the shape of the solder ball of the BGA type semiconductor device on which the semiconductor chip is mounted on the package substrate is an ellipse is shown, but in the wafer level CSP, electrodes are arranged on the surface. A ball pad formed on the upper layer of the electrode of the semiconductor chip has first and second major axes intersecting each other at substantially 90 degrees and the major axes intersecting at substantially 45 degrees with respect to the extended surface of the side surface of the semiconductor chip. It is possible to make the shape of the solder ball connected to this ball pad almost as a part of an ellipsoid as an elliptical shape directed in the direction.

  In the embodiment, an example in which the elliptical solder balls are arranged closest to each other is shown. However, when there is a margin in the vertical or horizontal direction of the grid arrangement of the grid, the short axis and the long axis of the solder ball are arranged. It is not always necessary to limit the ratio to the axis to about 0.5, and it is not always necessary to limit the angle between the major axis and the rectangular side of the back surface of the package substrate 11 to 45 degrees.

  In the embodiment, an example in which the elliptical solder balls are arranged on the entire surface of the semiconductor device or in a region excluding the vicinity of the boundary between the quadrants divided into four is shown. It is possible to arrange the solder balls in a circular shape and to arrange the circular solder balls in other regions.

  In the embodiment, the ball pad is connected to the front surface wiring through the back surface wiring and the internal wiring, but the ball pad is connected to the semiconductor device to the mounting substrate, the connection strength or the connection balance, etc. This is for connecting a dummy solder ball to ensure the resistance, and it does not matter if it is not connected to the surface wiring or the like.

BRIEF DESCRIPTION OF THE DRAWINGS It shows the outline of the semiconductor device which concerns on Example 1 of this invention, FIG. 1 (a) is the schematic diagram seen from the front direction which notches and shows a part of semiconductor device, FIG.1 (b) is from a bottom face side. A plan view. FIG. 5 is an enlarged view of a part of FIG. 1B according to the first embodiment of the present invention, schematically showing an arrangement and a shape when the orientation of solder balls on the bottom surface of the semiconductor device is the same. The figure which shows typically the arrangement | positioning and shape in case the direction of the solder ball of the bottom face of the semiconductor device which concerns on Example 1 of this invention differs mutually. The typical top view seen from the bottom face side of the semiconductor device which concerns on Example 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor device 11, 61 Package board 13 Front surface wiring 14 Internal wiring 15 Back surface wiring 17 Solder resist 21 Semiconductor chip 23 Adhesive material 25 Bonding wire 27 Sealing resin 31 Solder balls 31a, 31b, 31c Elliptical solder balls 32 Ball pads 37, 37a 37b Long axis direction line 41 Square 43 Proximity limit circle 44 Proximity limit 45 Circle solder ball 47 Long axis 48 Short axis 51 Distance increase

Claims (5)

A semiconductor chip having electrodes on the surface;
At least a sealing resin for sealing the electrode;
Connected to the electrode, the long axis extension intersects with each other at substantially 90 degrees, and faces the first and second directions in which the long axis extension intersects with the extension surface of the side surface of the semiconductor chip at substantially 45 degrees. A conductive material exposed portion having an oval shape;
An external connection terminal connected to the exposed portion of the conductive material;
A semiconductor device comprising: A package substrate having wirings formed on the front surface and the back surface facing the front surface and connected to each other;
A semiconductor chip having an electrode on the surface and fixed to the surface of the package substrate;
Connection means for electrically connecting the electrode and the wiring on the surface of the package substrate;
A sealing resin for sealing at least the electrode and the connection means;
The first and second directions are connected to the wiring on the back surface of the package substrate, and the major axis extension intersects each other at substantially 90 degrees, and the major axis extension intersects the side surface of the package substrate at substantially 45 degrees. A conductive material exposed portion having an oval shape facing;
An external connection terminal connected to the exposed portion of the conductive material;
A semiconductor device comprising:   The conductive material exposed part facing the first direction and the conductive material exposed part facing the second direction are mirror-symmetric with each other. Semiconductor device.   4. The semiconductor device according to claim 1, wherein the centers of the exposed portions of the conductive material are arranged in a grid pattern. 5.   5. The semiconductor device according to claim 1, wherein the conductive material exposed portion is arranged with a center of distribution of the conductive material exposed portion as a symmetric center. 6.

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