JP2920750B2 - Area array semiconductor device and printed circuit board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an area array semiconductor device in which a plurality of ball electrodes are arranged on the lower surface of a package and a printed circuit board on which the device is mounted. The present invention relates to an area array semiconductor device and a printed circuit board which are efficiently performed without increasing the number of layers and the size of the printed circuit board.

[0002]

2. Description of the Related Art The number of output terminals of a semiconductor tends to increase as the function of a semiconductor device increases. In addition, the pitch between electrodes of a semiconductor device is becoming narrower in order to cope with lighter and thinner printed circuit boards. For example, a typical QFP (Quad
In Flat Package), some parts are used up to extremely narrow ones such as 0.3 mm pitch. However, as the inter-electrode pitch becomes narrower, it has become extremely difficult to ensure quality in manufacturing. In recent years, attention has been paid to area array packages in which electrodes are arranged in a grid on the back surface of a component package. Representative examples thereof include a BGA (Ball Grid Array) and a CSP (Chip Scale Pac).
kage).

For example, in a BGA package, as shown in FIG. 5, a semiconductor chip 50 and a BGA package daughter substrate 53 having circuit wiring are electrically connected by a gold wire or the like. It is configured by sealing and electrically connecting signal lines output from the semiconductor chip 50 to respective ball electrodes 54 arranged in a lattice on the back surface of the substrate via a BGA package daughter substrate 53.

[0004] In the BGA package, the ball electrodes 54 are arranged in a lattice pattern in a plane. Therefore, even if the pitch between the electrodes is wider than that of the QFP, the number of electrodes per component area can be secured more. It has an advantageous structure.

The connection of the BGA to the printed circuit board is Q
As in the case of the FP, a flux or a solder paste is applied to soldering pads arranged in a grid on a printed circuit board in advance as shown in FIG. 6, and a BGA package is positioned and mounted thereon. Next, the BGA package and the printed circuit board are connected by heating them in a reflow furnace.

[0006]

However, when the above-mentioned conventional BGA package is used, the following problems occur.

That is, as shown in FIG. 6, since the soldering pads are arranged in a lattice pattern, the pads arranged outside and the wirings (solid lines or thick lines) connected to the pads become more inward toward the inside of the BGA package. (Indicated by a solid line) makes the wiring space small and makes it difficult to draw out each wiring. In the example of the pad arrangement shown in FIG. 6, it is possible to draw out one to three wires between adjacent pads.
It can be seen that when the number is four or more, the gap between the pads is so small that the fourth line cannot be wired.

For this reason, in order to efficiently perform wiring from all the electrodes to each pad, the number of layers of the printed circuit board is increased and wiring is performed via inner layers, or the size of the printed circuit board is increased. There is a problem that wiring must be performed by increasing the gap between the pads, and the cost and size of the printed circuit board cannot be avoided.

[0009] On the other hand, a via ball which does not penetrate a printed board, which is formed by stacking layers above and below a core layer and conducts only between specific layers, instead of a via ball (through hole) penetrating the printed board. A printed circuit board made by a build-up method, in which wiring in the inner layer can be made more efficient by providing a (non-through hole), is also used in part, but even with this method, a cost increase is inevitable.

Therefore, in order to avoid the above cost increase, the electrodes can be actually arranged only in about 3 to 4 rows around the package, or 3 to 4 rows around the package.
There is a problem that only the electrodes in the rows can be used.

Such a problem is described in, for example, an article of “Surface Mount Technology, November 1996, pages 2 to 7”.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an area array semiconductor device and a printed circuit board in which wiring efficiency is improved without increasing the number of layers and the size of the printed circuit board. With the goal.

[0013]

According to a first aspect of the present invention, there is provided an area array semiconductor device having a plurality of ball electrodes disposed on a lower surface of a package.
Among the ball electrodes, a ball electrode that does not exchange signals with other components on a printed circuit board on which the area array semiconductor device is mounted is arranged at a central portion on the lower surface of the package.

According to the first aspect of the present invention, since the ball electrode that does not transfer signals to and from other components on the printed circuit board is arranged at the center of the lower surface of the package of the area array semiconductor device, the ball electrode that does not transfer signals is provided. And the wiring to the pad for transferring signals on the printed circuit board can be wired so as not to interfere with each other in any layer of the printed circuit board. As a result, wiring can be efficiently performed without increasing the number of layers or the size of the substrate.

According to a second aspect of the present invention, in the first aspect of the present invention, the ball electrode which does not exchange signals with other components on the printed circuit board is a test signal ball electrode, a power supply or ground connection ball electrode. It is at least one of an electrode and a ball electrode having no specific function.

According to a second aspect of the present invention, at least one of a test signal ball electrode, a power supply or ground connection ball electrode, and a ball electrode having no specific function is disposed at the center of the lower surface of the package of the area array semiconductor device. Therefore, the wiring to the pad corresponding to such a ball electrode that does not transfer signals and the wiring to the pad that transfers signals on the printed board are wired so as not to interfere with each other in any layer of the printed board. It becomes possible. As a result, wiring can be efficiently performed without increasing the number of layers or the size of the substrate.

According to a third aspect of the present invention, there is provided a printed circuit board on which an area array semiconductor device having a plurality of ball electrodes disposed on a lower surface of a package is mounted, wherein a pad for connecting to each ball electrode of the area array semiconductor device is provided. ,
A pad which does not exchange signals with other components on the printed circuit board is arranged at a position corresponding to the center of the lower surface of the package of the area array semiconductor device.

According to the third aspect of the present invention, of the pads for connecting to the respective ball electrodes of the area array semiconductor device, pads that do not transfer signals to and from other components on the printed circuit board are located at the center of the lower surface of the package. The wiring to the pads that do not pass signals and the wiring to the pads that pass signals on the printed circuit board can be wired so as not to interfere with each other on any layer of the printed circuit board. It becomes possible. As a result, wiring can be efficiently performed without increasing the number of layers or the size of the substrate.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the pad which does not exchange signals with other components on the printed circuit board is a test signal pad, a power supply or ground connection pad, and It is characterized by being at least one of pads having no specific function.

According to the fourth aspect of the present invention, at least one of the test signal pad, the power supply or ground connection pad, and the pad having no specific function is arranged at a position corresponding to the center of the lower surface of the package. Wiring to a pad that does not transfer a signal and wiring to a pad that transfers a signal on a printed board can be wired so as not to interfere with each other in any layer of the printed board. As a result, wiring can be efficiently performed without increasing the number of layers or the size of the substrate.

According to a fifth aspect of the present invention, in the area array semiconductor device in which a plurality of ball electrodes are arranged on the lower surface of the package, other parts of the ball electrodes on a printed circuit board on which the area array semiconductor device is mounted are removed. A ball electrode connected to a power supply or a ground through the package is arranged on an outer peripheral portion of the package.

According to the fifth aspect of the present invention, the ball electrode connected to the power supply or the ground via another component on the printed circuit board is arranged on the outer periphery of the package. Eliminates the need for wiring for ground connection inside the package, thereby eliminating wiring congestion between pads and efficiently wiring without increasing the number and size of boards. Can be.

According to a sixth aspect of the present invention, there is provided a printed circuit board on which an area array semiconductor device having a plurality of ball electrodes disposed on a lower surface of a package is mounted, wherein a pad for connecting to each ball electrode of the area array semiconductor device is provided. ,
A pad connected to a power supply or a ground via another component on the printed board is arranged at a position corresponding to an outer peripheral portion of the package.

According to the sixth aspect of the present invention, since the pads connected to the power supply or the ground via other components on the printed circuit board are arranged at positions corresponding to the outer peripheral portion of the package, the printed circuit board is generally a wide wiring. It is not necessary to wire the wiring for connection to the upper power supply or the ground inside the package, which eliminates the crowding of the wiring between the pads and efficiently increases the number of layers and the size of the board without increasing the number of layers Wiring can be performed.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
1 is a cross-sectional view of an area array semiconductor device (BGA package) according to an embodiment and a printed circuit board on which the device is mounted.

As shown in FIG. 1, the BGA package according to the first embodiment includes a semiconductor chip 1, a mold resin 2 for protecting the semiconductor chip 1, and ball electrodes arranged on the back surface of the package in a grid pattern. And a daughter substrate 3 provided below the semiconductor chip 1 and having circuit wiring therein for electrically connecting the semiconductor chip 1 and the ball electrode 4. It is mounted on a printed circuit board 6 having a four-layer structure of first to fourth layers.

In the first embodiment, of the ball electrodes 4 of the BGA package, the ball electrodes 5 that are not electrically connected to other components in the same printed circuit board 6, that is, the ball electrodes 4 connected to other components. Ball electrode 5 that does not deliver signals
(Black ball electrodes in FIG. 1) are collected at the center of the package.

The printed circuit board 6 has a through hole 7 that electrically penetrates the front surface (the surface on the mounting side of the BGA package) and the back surface of the printed circuit board 6, and a surface layer (first layer in FIG. 1) or a back layer (FIG. 1). The fourth layer in FIG. 1 and the inner layer (second layer in FIG. 1)
And a non-penetrating hole 8 that conducts the third layer without passing through the front and back. Further, test pads 9 are provided on the front and back surfaces of the printed circuit board 6 as signal input / output terminals for performing a connection state inspection of a soldered portion, a component abnormality inspection, a function inspection, and the like.

A test pad 10 is provided on the upper surface of the daughter board 3 as a signal input / output terminal when the mounted printed board 6 is inspected including the BGA package. At least one ball electrode 5 is connected via a wiring in an inner layer of the daughter substrate 3. The wiring may be run from the back surface of the daughter substrate 3 and connected to the upper surface of the daughter substrate via the side surface of the daughter substrate.

Next, the electrodes 4 of the BGA package shown in FIG.
FIG. 2 shows a soldering pad arranged on a printed circuit board 6 connected to the soldering pad 5 by soldering, and how wiring is routed from the pad.

As shown in FIG. 2, the printed circuit board 6 includes
A soldering pad 12 for transferring signals to and from other components of the printed circuit board 6 and a soldering pad 13 for not transferring signals to and from other components of the printed circuit board 6 are arranged. Here, since the ball electrodes 5 are gathered in the center of the package, the soldering pads 13 connected to the ball electrodes 5 are more centrally located in the package (inside the package) than the soldering pads 12 connected to the ball electrodes 4. ).

The soldering pad 12 shown in FIG. 2 includes a pad to which a wiring 14 on the surface of the board drawn from another component of the printed board 6 is connected, and a pad via the inner layer from the non-through hole 8. There are pads connected to components.
The soldering pads 13 include a pad connected to the through hole 7 or the non-through hole 8 and a pad connected to the test pad 10 via the daughter board 3.

The ball electrode 5 or the soldering pad 13 which does not exchange signals with other components on the printed circuit board 6 may be, for example, a device for inputting / outputting a test signal or another signal on the printed circuit board 6. Some components are directly connected to a power supply or a ground without using any components, and others have no particular function.

Next, the operation of the first embodiment will be described. Since the ball electrodes 5 that do not exchange signals with other components on the printed circuit board 6 are collected at the center of the package,
As shown in FIGS. 1 and 2, the wiring to the soldering pad 13 corresponding to the ball electrode 5 and the wiring 14 to the soldering pad 12 for transferring signals on the printed board 6 are connected to the printed board 6. Wiring can be performed so as not to interfere with each other. Thus, wiring can be efficiently performed without increasing the number and size of the layers of the substrate, and the cost can be reduced.

By the way, conventionally, when inspecting the mounted printed circuit board including the BGA parts, in order to inspect one electrical signal without fail, an input signal and an output signal are converted to a BGA signal. It is necessary to input / output data from / to a test pad 9 on a printed circuit board via the ball electrode 4. In this conventional method, two ball electrodes 4 and a wiring for transferring signals between them are required.

On the other hand, in the first embodiment, a test signal input / output test pad 10 electrically connected from a ball electrode for transferring a test signal through a BGA daughter board 3 is connected to the daughter board 3. Is provided on the upper surface of the substrate, one or two ball electrodes 4 and wiring on the printed circuit board 6 for transferring signals to and from them are not required for one signal test. As a result, the wiring from the ball electrode 4 necessary for performing the normal device operation is not hindered by the wiring for the test signal, and the wiring efficiency can be improved. Further, since test pads and wiring areas for the test pads can be reduced on the printed board 6, the number of layers and the size of the board can be reduced, and the cost can be reduced.

(Second Embodiment) In the second embodiment, among the ball electrodes 4 of the BGA package, the ball electrodes connected to the power supply or the ground via other components on the printed circuit board 6 are connected to the package. It is arranged on the outer periphery. When the ball electrodes are arranged in this manner, the wiring method of the soldering pads on the printed circuit board 6 is as shown in FIG. In addition, about the structure similar to 1st Embodiment, detailed description is abbreviate | omitted using the same code | symbol and the same design.

In FIG. 3, each pad except for the pad connected through the through hole 7 and the non-through hole 8
It is connected to either a wiring 14 for inputting / outputting a normal electric signal to / from a pad and a wiring 15 for connecting to a power supply or a ground. Usually, the wiring 15 for connecting to a power supply or a ground is a wiring 14 for inputting / outputting a normal electric signal due to the necessity of flowing relatively large-capacity electricity and the necessity of flowing stable waveform electricity.
The wiring is wider than the wiring (the same applies to FIG. 4 described later). In the second embodiment, since the ball electrodes connected to the power supply or the ground are arranged on the outer periphery of the package, the soldering pads 16 connected to the power supply or the ground via the wiring 15 are printed as shown in FIG. Outer periphery of package (outside of package) on substrate 6
It can be seen that the thick wiring 15 is not wired inside the package.

Next, FIG. 4 shows a conventional wiring method for soldering pads, which is compared with the wiring method shown in FIG.

As shown in FIG. 4, in the conventional wiring method,
Wide wiring 1 to connect to power or ground
Since the ball electrodes connected to 5 are also inside the package, the wiring between the pads outside the package on the printed circuit board 6 is very crowded, and it is found that it is difficult to draw out the wiring.

On the other hand, in FIG. 3 according to the second embodiment,
In the wiring method described above, since the wide wiring 15 is not wired inside the package on the printed circuit board 6 as described above, the crowding of the wiring between the pads is eliminated, and as a result, more electrodes are formed. The substrate can be used efficiently without increasing the cost.

However, of the ball electrodes connected to the power supply or the ground, those connected directly to the power supply or the ground without passing through other components on the printed circuit board 6 are packaged as in the first embodiment. May be arranged at the center of the power supply, and the center may be connected to a power supply or a ground via a via ball.

Although the embodiment of the present invention has been described above, it is needless to say that the present invention is not limited to the above example, and various changes can be made without departing from the gist of the present invention.

[0045]

As described above, according to the first and second aspects of the present invention, the ball electrode which does not exchange signals with other components on the printed circuit board is provided on the lower surface of the package of the area array semiconductor device. The wiring to the pad corresponding to the ball electrode that does not transfer signals and the wiring to the pad that transfers signals on the printed circuit board are not obstructed by any layers of the printed circuit board. Wiring can be performed, thereby providing an effect that wiring can be efficiently performed without increasing the number and size of layers of the substrate.

According to the third and fourth aspects of the present invention, of the pads for connecting to the respective ball electrodes of the area array semiconductor device, the pads that do not exchange signals with other components on the printed circuit board are provided. Is arranged at the position corresponding to the center of the lower surface of the package, so that the wiring to the pads that do not pass signals and the wiring to the pads that pass signals on the printed board can be It is possible to wire so that they do not interfere with each other,
As a result, an effect is obtained that wiring can be efficiently performed without increasing the number of layers or the size of the substrate.

According to the fifth aspect of the present invention, since the ball electrodes connected to the power supply or the ground via other components on the printed circuit board are arranged on the outer periphery of the package, the wiring is generally thick. Eliminates the need to route wiring for power or ground on the printed circuit board inside the package, which eliminates wiring congestion between pads and increases efficiency without increasing the number of layers and size of the board An effect is obtained that the wiring can be performed efficiently.

According to the sixth aspect of the present invention, the pads connected to the power supply or the ground via other components on the printed circuit board are arranged at positions corresponding to the outer peripheral portion of the package. There is no need to route the wiring for power or ground on the printed circuit board, which is a thick wiring, inside the package.This eliminates the crowding of the wiring between the pads and increases the number of layers and the size of the board. An effect is obtained that wiring can be efficiently performed without performing.

[Brief description of the drawings]

FIG. 1 is a sectional configuration diagram of an area array semiconductor device (BGA package) according to a first embodiment of the present invention and a printed circuit board on which the device is mounted.

FIG. 2 is a diagram illustrating a wiring state of soldering pads arranged on a printed circuit board according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a wiring state of soldering pads arranged on a printed circuit board according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a wiring state of soldering pads arranged on a conventional printed circuit board.

FIG. 5 is a cross-sectional configuration diagram of a conventional area array semiconductor device (BGA package).

FIG. 6 is a diagram showing a wiring state of a soldering pad arranged on a conventional printed circuit board.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Semiconductor chip 2 Mold resin 3 Daughter board 4 Ball electrode 5 Ball electrode which does not exchange signals with other parts on a printed board 6 Printed board

Claims (6)

(57) [Claims] 1. An area array semiconductor device in which a plurality of ball electrodes are arranged on a lower surface of a package, wherein a signal is transmitted between another one of the ball electrodes and another component on a printed circuit board on which the area array semiconductor device is mounted. An area array semiconductor device, wherein a ball electrode which is not transferred is arranged at a central portion of a lower surface of the package. 2. A ball electrode which does not exchange signals with other components on the printed circuit board is a test signal ball electrode, a power supply or ground connection ball electrode, and a ball electrode having no specific function. 2. The area array semiconductor device according to claim 1, wherein the area array semiconductor device is at least one of them. 3. A printed circuit board on which an area array semiconductor device having a plurality of ball electrodes disposed on a lower surface of a package is mounted, wherein a pad for connecting to each ball electrode of the area array semiconductor device is provided on the printed circuit board. A printed circuit board, wherein pads that do not exchange signals with other components are arranged at positions corresponding to the center of the lower surface of the package of the area array semiconductor device. 4. A pad that does not exchange signals with other components on the printed circuit board is a test signal pad,
4. The printed circuit board according to claim 3, wherein the printed circuit board is at least one of a power supply or ground connection pad and a pad having no specific function. 5. An area array semiconductor device having a plurality of ball electrodes disposed on a lower surface of a package, wherein a power supply or a ground is provided via another component on a printed circuit board on which the area array semiconductor device is mounted. An area array semiconductor device, wherein a ball electrode connected to the package is arranged on an outer peripheral portion of the package. 6. A printed circuit board on which an area array semiconductor device having a plurality of ball electrodes arranged on a lower surface of a package is mounted, wherein a pad for connecting to each ball electrode of the area array semiconductor device is provided on the printed circuit board. A printed circuit board, wherein pads connected to a power supply or a ground via other components are arranged at positions corresponding to an outer peripheral portion of the package.