JP2013168767A - Electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact electronic apparatus.SOLUTION: The electronic apparatus has a signal terminal T1 (signal electrode E1) placed adjacently to one side of an undersurface of a BGA package 9, a signal terminal T2 (signal electrode E2) placed adjacently to the signal terminal T1 in an X direction, a power terminal T3 (power electrode E3) placed adjacently to the signal terminal T1 in a Y direction, and power wires L4, L5 routed so as to surround a crystal oscillator 4 and others. This can implement an oscillation circuit by a routing rule of passing a single wire L between two adjacent terminals T (electrodes E).

Description

  The present invention relates to an electronic device, and can be suitably used for an electronic device including a printed wiring board on which an oscillation circuit is mounted, for example.

  2. Description of the Related Art Conventionally, there are electronic devices including a printed wiring board on which an oscillation circuit including a crystal oscillator, a resistance element, two capacitors, and a semiconductor device (inverter) is mounted (for example, see Patent Documents 1 and 2).

  In some cases, a crystal oscillator is mounted on an IC chip and accommodated in a package (see, for example, Patent Document 3).

Japanese Patent Laid-Open No. 9-162643 Japanese Patent Laid-Open No. 61-216523 JP 2010-34094 A

  In the electronic devices disclosed in Patent Documents 1 and 2, when a semiconductor device including a BGA (Ball Grid Arreay) package is used, it is necessary to pass wiring on the printed wiring board surface between electrodes (solder balls) on the back surface of the BGA package. There is. Conventionally, two wires are passed between two adjacent electrodes. However, in recent years, the size of the BGA package has been reduced, and the gap between the electrodes has been reduced. Therefore, it has become difficult to pass two wires between two adjacent electrodes.

  Other problems and novel features will become apparent from the description of the specification and the accompanying drawings.

  In one embodiment, the first signal electrode is disposed adjacent to one side of the back surface of the package, the first and second signal electrodes are disposed adjacent to each other in a direction orthogonal to the one side, One signal electrode and the first power supply electrode are arranged adjacent to each other in a direction parallel to one side thereof.

  According to the embodiment, the first signal electrode and the first power supply electrode are arranged along the outer periphery of the package, and the second signal electrode is arranged inside the first signal electrode. This makes it possible to adopt a wiring rule that allows one wiring to pass between two adjacent electrodes.

It is a circuit block diagram which shows the principal part of the electronic device by Embodiment 1 of this application. FIG. 2 is a diagram illustrating a configuration of the semiconductor device illustrated in FIG. 1. It is a figure which shows the layout of the surface of the printed wiring board shown in FIG. 3 is a circuit block diagram illustrating a comparative example of the first embodiment. FIG. It is a figure which shows the layout of the surface of the printed wiring board shown in FIG. It is a circuit block diagram which shows the principal part of the electronic device by Embodiment 2 of this application. It is a figure which shows the layout of the surface of the printed wiring board shown in FIG.

  Digital consumer devices are multifunctional, but prices continue to drop. For this reason, it is necessary to reduce the cost of components of digital consumer devices while maintaining multiple functions. As an LSI (Large Scale Integration) which is a key device of a constituent member, an LSI having a BGA package structure is generally used in order to realize multiple functions. In addition, in order to reduce the cost of LSIs, the pitch of the electrodes of the BGA package is narrowed and the outer shape of the BGA package is being reduced. On the other hand, for printed wiring boards on which LSIs are mounted, the number of wiring layers is being reduced without reducing the design rules in order to reduce costs.

  Accordingly, the design rule of the printed wiring board is not changed, and the pitch of the electrodes of the BGA package is reduced. Therefore, the two wirings of the printed wiring board cannot be passed between two adjacent electrodes of the BGA package. Will occur.

  In addition, since a large number of wirings are concentrated in the vicinity of a small-area BGA package, there is a problem that crosstalk is likely to occur and it is difficult to ensure the waveform quality of the signal.

  A crystal oscillator is generally used as a clock source for an LSI for a digital consumer device having a high-speed interface such as DDR (Double Date Rate), LVDS (Low Voltage differential signaling), or HDMI (High Definition Multimedia Interface). Since the waveform quality of the clock signal affects the clock jitter characteristics of the high-speed interface, a layout design that can ensure the waveform quality of the clock signal is necessary.

  In view of this, a method has been devised for efficiently laying out a crystal oscillator or the like on a printed wiring board while maintaining a high waveform quality of the clock signal with a wiring rule that allows one wiring to pass between the electrodes of the BGA package.

[Embodiment 1]
FIG. 1 is a circuit block diagram showing a main part of an electronic device according to Embodiment 1 of the present application. In FIG. 1, the electronic device includes a printed wiring board 1. Capacitors 2 and 3, a crystal oscillator 4, a resistance element 5, and a semiconductor device (LSI) 6 are mounted on the surface of the printed wiring board 1.

  As shown in FIG. 2, the semiconductor device 6 includes a semiconductor chip 8 on which an inverter 7 and the like are mounted, and a BGA package 9 on which the semiconductor chip 8 is mounted. On the back surface of the BGA package 9, a plurality of electrodes (solder balls) E are arranged in a lattice pattern. Each electrode E is connected to a predetermined pad of the semiconductor chip 8 via the wiring of the BGA package 9 or the like.

  Returning to FIG. 1, some of the plurality of electrodes E of the BGA package 9 are used as signal electrodes E1, E2 and power supply electrodes E3, E4 for the inverter 7. The signal electrode E1 is connected to the output node of the inverter 7, and the signal electrode E2 is connected to the input node of the inverter 7. Power supply electrode E4 is connected to power supply node 7a of inverter 7, and power supply electrode E3 is connected to power supply node 7b of inverter 7. Inverter 7 is driven by a power supply voltage applied between power supply nodes 7a and 7b, and outputs an inverted signal of a signal applied to an input node.

  Further, signal terminals T1 and T2 and power supply terminals T3 to T6 are formed on the surface of the printed wiring board 1. Electrodes E1 to E4 are soldered to the surfaces of the terminals T1 to T4, respectively. The power supply terminal T5 receives a power supply voltage VCC from the outside, and the power supply terminal T6 receives a ground voltage VSS from the outside.

  In addition, signal wirings L1 to L3 and power supply wirings L4 to L6 are formed on the surface of the printed wiring board 1. The signal line L1 is connected between the signal terminal T1 and the first electrode of the resistance element 5. The signal line L <b> 2 connects the second electrode of the resistance element 5, the first electrode of the capacitor 3, and the first electrode of the crystal oscillator 4. The signal line L3 connects the signal terminal T2, the second electrode of the crystal oscillator 4, and the first electrode of the capacitor 2.

  The power supply line L4 connects the power supply terminal T3 and the second electrodes of the capacitors 2 and 3. A part of the power supply line L4 is disposed adjacent to the signal line L3. The power supply line L5 connects the power supply terminals T3 and T6 and the second electrode of the capacitor 3. The power supply line L6 is connected between the power supply terminals T4 and T5. The power supply lines L4 and L5 are arranged so as to surround the capacitors 2 and 3, the crystal oscillator 4, the resistance element 5, the signal lines L1 to L3, and the signal terminals T1 and T2.

  The power supply lines L4 and L5 constitute a return current path (coplanar ground) of the oscillation circuit. The power supply lines L4 and L5 form a guard ground that prevents crosstalk between the clock signal CLK generated by the oscillation circuit and signals of other circuits on the printed wiring board 1.

  The capacitors 2 and 3, the crystal oscillator 4, the resistance element 5, and the inverter 7 constitute an oscillation circuit, and the inverter 7 outputs a clock signal CLK having a predetermined frequency. The clock signal CLK is supplied to other circuits in the semiconductor device 6. The semiconductor device 6 operates in synchronization with the clock signal CLK.

  FIG. 3 is a diagram showing a layout of the surface of the printed wiring board 1. In FIG. 3, a plurality of terminals T are arranged in a matrix in a region on the surface of the printed wiring board 1 where the semiconductor device 6, that is, the BGA package 9 is mounted. The plurality of terminals T are arranged at a predetermined pitch Px in the X direction (long-side direction of the substrate 1) in the figure corresponding to the plurality of electrodes E on the back surface of the BGA package 9, respectively, and Y in the figure They are arranged at a predetermined pitch Py in the direction (the short side direction of the substrate 1). A through via V is also arranged at the center of the four terminals T.

  In other words, a plurality of electrodes E are arranged in a matrix on the back surface of the BGA package 9. The plurality of electrodes E are arranged at a predetermined pitch Px in the X direction (direction perpendicular to one side of the BGA package 9) in the drawing corresponding to the plurality of terminals T on the surface of the printed wiring board 1, respectively. These are arranged at a predetermined pitch Py in the Y direction in the drawing (a direction parallel to one side of the BGA package 9).

  The signal terminal T1 is arranged so as to be adjacent to one side of the BGA package 9. The signal terminals T1 and T2 are arranged adjacent to each other in the X direction. The signal terminal T1 and the power supply terminal T3 are disposed adjacent to each other in the Y direction.

  In other words, the signal electrode E1 is disposed adjacent to one side of the BGA package 9 corresponding to the signal terminal T1. The signal electrodes E1 and E2 are disposed adjacent to each other in the X direction corresponding to the signal terminals T1 and T2, respectively. The signal electrode E1 and the power supply electrode E3 are disposed adjacent to each other in the Y direction corresponding to the signal terminal T1 and the power supply terminal T3, respectively.

  A plurality of wirings L are formed on the surface of the printed wiring board 1. Each terminal T is connected to one end of the corresponding wiring L. The other end of each wiring L is connected to an external component on the front surface of the substrate 1 or connected to a wiring (not shown) on the back surface of the substrate 1 through a through via V.

  The first and second electrodes of the resistive element 5, the first electrode of the capacitor 3, the first and second electrodes 4a and 4b of the crystal oscillator 4, and the first electrode of the capacitor 2 They are arranged in the X direction when viewed from the terminal T1 (that is, the signal electrode E1).

  The signal line L1 extends in the X direction and is connected between the signal terminal T1 and the first electrode of the resistance element 5. The signal line L2 extends in the X direction, and connects the second electrode of the resistor element 5, the first electrode of the capacitor 3, and the first electrode 4a of the crystal oscillator 4. The signal wiring L3 passes between the signal terminal T1 and the power supply terminal T3, and connects the signal terminal T2, the second electrode 4b of the crystal oscillator 4, and the first electrode of the capacitor 2. The signal line L3 is adjacent to the signal lines L1 and L2.

  The power supply line L4 is connected between the power supply terminal T3 and the second electrodes of the capacitors 2 and 3. A part of the power supply line L4 is disposed adjacent to the signal line L3. The power supply line L5 passes between the signal terminals T1 and T2 and the other terminal T group adjacent to them, and is connected between the power supply terminal T3 and the second electrode of the capacitor 3. The power supply lines L4 and L5 are arranged so as to surround the capacitors 2 and 3, the crystal oscillator 4, the resistance element 5, the signal lines L1 to L3, and the signal terminals T1 and T2.

  In the first embodiment, the signal terminals T1, T2 (signal electrodes E1, E2) are arranged adjacent to each other in the X direction, and the signal terminal T1 (signal electrode E1) and the power supply terminal T3 (power supply electrode E3) are in the Y direction. Are arranged adjacent to each other, and an annular shield member is constituted by the power supply terminal T3 (power supply electrode E3) and the power supply wirings L4 and L5. This makes it possible to adopt a wiring rule that allows only one wiring L to pass between two adjacent terminals T (electrodes E).

  Since such a wiring rule is adopted, the wiring width and wiring interval of the printed wiring board 1 can be increased, and the cost of the printed wiring board 1 can be reduced. Further, the pitch of the electrodes E of the BGA package 9 can be reduced, and the BGA package 9 can be reduced in size and cost.

  Of the wires L passing through one side of the BGA package 9 on the crystal oscillator 4 side, the number of wires L related to the oscillation circuit is four wires L1, L3 to L5 shown in FIG. Although not shown in FIG. 1, the total number of wirings is five with the wiring L6 shown in FIG. The number of wires is one less than the comparative example described later. When the BGA package 9 is downsized, the outer periphery of the BGA package 9 is shortened, so that the number of wirings L that can be drawn from the BGA package 9 is reduced. However, in the first embodiment, since the number of wirings L related to the oscillation circuit is reduced, the BGA package 9 can be downsized.

  In the first embodiment, the power supply voltage VCC and the ground voltage VSS are applied to the power supply terminals T5 and T6, respectively, but conversely, even if the ground voltage VSS and the power supply voltage VCC are applied to the power supply terminals T5 and T6, respectively. The oscillation circuit operates in the same manner, and the same effect can be obtained.

  Further, the positions of the signal terminals T1 and T2 (signal electrodes E1 and E2) may be interchanged. That is, the signal terminal T2 (signal electrode E2) is arranged adjacent to one side of the BGA package 9, the signal terminals T2, T1 (signal electrodes E2, E1) are arranged adjacent to each other in the X direction, and the signal wiring L1 , L2 and the resistance element 5 may be interchanged with the position of the signal line L3. Also in this case, the oscillation circuit operates in the same manner, and the same effect can be obtained.

[Comparative example]
FIG. 4 is a circuit block diagram showing a main part of an electronic device as a comparative example of the first embodiment, and is a diagram contrasted with FIG. 5 is a diagram showing the layout of the surface of the printed wiring board 11 shown in FIG. 4, and is a diagram contrasted with FIG.

  4 and 5, this comparative example is different from the first embodiment in that printed wiring board 1, semiconductor device 6, and BGA package 9 are printed wiring board 11, semiconductor device 12, and BGA package, respectively. This is a point replaced by 13.

  In this electronic apparatus, the signal terminals T1, T2 (signal electrodes E1, E2) are arranged adjacent to each other in the X direction, but the power terminal T3 (power electrode E3) is the signal terminals T1, T2 (signal electrodes E1, E1). It is arranged at a position away from E2). As a result, the power supply lines L4 and L5 are directly connected without passing through the power supply terminal T3 (power supply electrode E3) to form an annular shield member. A power supply line L7 is connected between the power supply terminals T3 and T6.

  Further, a wiring rule is adopted in which two wirings L are passed between two adjacent terminals T (electrodes E). For this reason, the signal wiring L3 and the power supply wiring L4 pass between the signal terminal T1 (signal electrode E1) and the adjacent terminal T (electrode E).

  In this comparative example, a wiring rule for passing two wirings L between the electrodes E is adopted. Therefore, in order to adopt a BGA package in which the pitch of the electrodes E is narrow in order to reduce the cost of the semiconductor device 12, a print is required. It is necessary to narrow the wiring width and wiring interval of the wiring board 11. In order to manufacture such a printed wiring board 11, a highly accurate and expensive manufacturing apparatus is required, and as a result, the printed wiring board 11 is expensive.

  In addition, among the wirings L passing through one side of the BGA package 13 on the crystal oscillator 4 side, the number of wirings L related to the oscillation circuit is four wirings L1, L3 to L5 shown in FIG. Although not shown in FIG. 5, there are a total of six wires L6 and L7 shown in FIG. The number of wires is one more than in the first embodiment. When the BGA package 13 is downsized, the outer periphery of the BGA package 13 is shortened, so that the number of wirings L that can be drawn from the BGA package 13 is reduced. Therefore, when the number of wirings L related to the oscillation circuit increases, it becomes difficult to reduce the size of the BGA package 13.

[Embodiment 2]
FIG. 6 is a circuit block diagram showing the main part of the electronic device according to the second embodiment of the present application, and is a diagram contrasted with FIG. 7 is a diagram showing the layout of the surface of the printed wiring board 21 shown in FIG. 6, and is a diagram contrasted with FIG.

  Referring to FIGS. 6 and 7, the second embodiment is different from the first embodiment in that printed wiring board 1, semiconductor device 6, and BGA package 9 are printed wiring board 21, semiconductor device 22, and It is replaced with the BGA package 23 and a capacitor 24 is added.

  In this electronic apparatus, power supply terminals T3 and T4 (power supply electrodes E3 and E4) are arranged adjacent to each other in the X direction in the drawing. The first and second electrodes of the capacitor 24 are arranged in the X direction when viewed from the power supply terminal T3 (power supply electrode E3).

  Power supply terminals T5 and T6 receive ground voltage VSS and power supply voltage VCC from the outside, respectively. The power terminals T3 and T6 and the first electrode of the capacitor 24 are connected by a power line L11. The power supply line L11 is disposed adjacent to the signal line L3. The second electrodes of the capacitors 2, 3 and 24 are connected by a wiring L12. The second electrode of the capacitor 3 and the power supply terminal T4 are connected by a wiring L13. The power supply line L13 passes between the signal terminals T1 and T2 (signal electrodes E1 and E2) and the terminal T (electrode E) group adjacent thereto. The power supply lines L11 to L13 are arranged so as to surround the capacitors 2 and 3, the crystal oscillator 4, the resistance element 5, the signal lines L1 to L3, and the signal terminals T1 and T2.

  In the second embodiment, the signal terminals T1 and T2 (signal electrodes E1 and E2) are arranged adjacent to each other in the X direction, and the signal terminal T1 (signal electrode E1) and the power supply terminal T3 (power supply electrode E3) are in the Y direction. And power supply terminals T3 and T4 (power supply electrodes E3 and E4) are arranged adjacent to each other in the X direction. The power supply terminals T3 and T4 (power supply electrodes E3 and E4) and the power supply wirings L11 to L13 constitute an annular shield member. As a result, an oscillation circuit can be realized with a wiring rule that allows only one wiring L to pass between two adjacent terminals T (electrodes E).

  Since the oscillation circuit is realized by such a wiring rule, the wiring width and wiring interval of the printed wiring board 21 can be increased, and the cost of the printed wiring board 21 can be reduced. Further, the pitch of the electrodes E of the BGA package 23 can be reduced, and the BGA package 23 can be reduced in size and cost.

  Of the wirings L passing through one side of the BGA package 23 on the crystal oscillator 4 side, the number of wirings L related to the oscillation circuit is a total of four wirings L1, L3, L11, and L13 shown in FIG. Become. The number of wires is two less than the comparative example. When the BGA package 23 is downsized, the outer periphery of the BGA package 23 is shortened, so that the number of wirings L that can be drawn from the BGA package 23 is reduced. However, in the second embodiment, since the number of wirings L related to the oscillation circuit is reduced, the BGA package 23 can be reduced in size.

  In the second embodiment, the ground voltage VSS and the power supply voltage VCC are applied to the power supply terminals T5 and T6, respectively. Conversely, even if the power supply voltage VCC and the ground voltage VSS are applied to the power supply terminals T5 and T6, respectively. The oscillation circuit operates in the same way, and the same effect can be obtained.

  Further, the positions of the signal terminals T1 and T2 (signal electrodes E1 and E2) may be interchanged. That is, the signal terminal T2 (signal electrode E2) is arranged adjacent to one side of the BGA package 9, the signal terminals T2, T1 (signal electrodes E2, E1) are arranged adjacent to each other in the X direction, and the signal wiring L1 , L2 and the resistance element 5 may be interchanged with the position of the signal line L3. Also in this case, the oscillation circuit operates in the same manner, and the same effect can be obtained.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  1, 11, 21 Printed circuit board, 2, 3, 24 capacitor, 4 crystal oscillator, 5 resistance element, 6, 12, 22 semiconductor device, 7 inverter, 7a, 7b power supply node, 8 semiconductor chip, 9, 13, 23 BGA package, E electrode, E1, E2 signal electrode, E3, E4 power supply electrode, L wiring, L1 to L3 signal wiring, L4 to L7, L11 to L13 power supply wiring, T terminal, T1, T2 signal terminal, T3 to T6 Power supply terminal, V through via.

Claims (7)

A printed wiring board having an oscillation circuit including a crystal oscillator, a resistance element, a first capacitor, a second capacitor, and a semiconductor device;
The semiconductor device includes a semiconductor chip on which an inverter is mounted, and a package on which the semiconductor chip is mounted.
The back surface of the package is arranged at a first pitch in a first direction parallel to one side of the back surface, and at a second pitch in a second direction orthogonal to the first direction. Provided with a plurality of electrodes,
The plurality of electrodes are:
First and second signal electrodes respectively connected to an output node and an input node of the inverter;
First and second power electrodes respectively connected to the first and second power nodes of the inverter;
The first signal electrode is disposed adjacent to the one side of the back surface of the package,
The first and second signal electrodes are disposed adjacent to each other in the second direction;
The electronic device, wherein the first signal electrode and the first power supply electrode are disposed adjacent to each other in the first direction. In addition, a third capacitor is provided,
The first and second power supply electrodes are disposed adjacent to each other in the second direction;
First and second electrodes of the resistive element, first electrodes of the first capacitor, first and second electrodes of the crystal oscillator, and a first electrode of the second capacitor; Are arranged in the second direction as viewed from the first signal electrode,
The first and second electrodes of the third capacitor are arranged in the second direction when viewed from the first power supply electrode,
The printed wiring board is
A first signal wiring connecting the first signal electrode and the first electrode of the resistive element;
A second signal line connecting the second electrode of the resistive element, the first electrode of the first capacitor, and the first electrode of the crystal oscillator;
Passing between the first signal electrode and the first power supply electrode, and connecting the second signal electrode, the second electrode of the crystal oscillator, and the first electrode of the second capacitor A third signal wiring to
A first power supply wiring connecting the first power supply electrode and the first electrode of the third capacitor;
The first signal electrode passes between the first and second signal electrodes and another electrode group adjacent thereto, and connects the second power supply electrode and the second electrodes of the first to third capacitors. 2 power wirings,
The first and second power supply lines include the crystal oscillator, the resistance element, the first and second capacitors, the first to third signal lines, and the first and second lines. The electronic device according to claim 1, wherein the electronic device is disposed so as to surround the signal electrode. The first power supply wiring receives a power supply voltage from the outside,
The electronic device according to claim 2, wherein the second power supply wiring receives a ground voltage from outside. The first power supply wiring receives a ground voltage from the outside,
The electronic device according to claim 2, wherein the second power supply wiring receives a power supply voltage from outside. First and second electrodes of the resistive element, first electrodes of the first capacitor, first and second electrodes of the crystal oscillator, and a first electrode of the second capacitor; Are arranged in the second direction as viewed from the first signal electrode,
The printed wiring board is
A first signal wiring connecting the first signal electrode and the first electrode of the resistive element;
A second signal line connecting the second electrode of the resistive element, the first electrode of the first capacitor, and the first electrode of the crystal oscillator;
Passing between the first signal electrode and the first power supply electrode, and connecting the second signal electrode, the second electrode of the crystal oscillator, and the first electrode of the second capacitor A third signal wiring to
A first power supply wiring connecting the first power supply electrode and the second electrode of the first and second capacitors;
A second power supply wiring that passes between the first and second signal electrodes and another electrode group adjacent thereto and connects the first power supply electrode and the second electrode of the second capacitor. And
The first and second power supply lines include the crystal oscillator, the resistance element, the first and second capacitors, the first to third signal lines, and the first and second lines. The electronic device according to claim 1, wherein the electronic device is disposed so as to surround the signal electrode.   The electronic apparatus according to claim 5, wherein the first and second power supply wirings receive a ground voltage from the outside.   The electronic device according to claim 5, wherein the first and second power supply wirings receive a power supply voltage from the outside.

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