Abstract:
A built-in capacitor type power feed device for an electrical component which solves the problems of the reduction in the noise margin of the power supply system accompanying the lower drive voltages of electrical components and the noise between the power supply and ground accompanying simultaneous switching waveforms, provided with a power supply for supplying power, a printed circuit board including a signal line pattern, a power bar having conductive projections provided in shapes and at positions corresponding to the shapes and positions of electrodes of the electrical component and provided outside of the printed circuit board, a ground bar provided outside of the printed circuit board, and a high dielectric layer provided at a part corresponding to the electrical component between the power bar and the ground bar, power from the power supply being fed to electrodes of the electrical component through the power bar and the ground bar.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is based upon and claims a priority of Japanese Patent Application No. 2005-286867 filed on Sep. 30,  2005 , the contents of which being incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a power feed device to power pins of an electrical component, more particularly relates to a built-in capacitor type power feed device designed to feed power to various types of power pins of a ball gate array (BGA) or other electrical component from an on board power (OBP) or other power supply without going through patterns included in the printed circuit board by arranging a power bar and ground bar outside of the printed circuit board, providing a high dielectric layer between them, and going through the power bar and ground bar.  
         [0004]     2. Description of the Related Art  
         [0005]     In recent years, the reduction in the noise margin of the power supply system accompanying the lower drive voltages of electrical components such as BGAs and the noise between the power and ground accompanying simultaneous switching waveforms are becoming major problems.  
         [0006]      FIG. 1A  is a plan view, seen from below, of a BGA fed with power by a conventional power feed device. In the figure,  10  indicates a BGA at the back side of which power pins  1  to  6  are arranged at predetermined positions in the row direction and column direction by solder balls. Each power pin  1  is an electrode supplied with for example a 3.3V power voltage V 1 . Each power pin  2  is an electrode supplied with for example a 3.3V reference voltage V 2 . Each power pin  3  is an electrode supplied with for example a 3.3V auxiliary power voltage V 3 . Each power pin  4  is an electrode supplied with for example a 5V power voltage V 4 . Each power pin  5  is an electrode supplied with for example a 5V reference voltage V 5 . Each power pin  6  is an electrode supplied with for example a 5V auxiliary power voltage V 6 .  
         [0007]      FIG. 1B  is a cross-sectional view showing one example of a conventional power feed device. In the figure,  12  indicates a printed circuit board arranged below the BGA  10 ,  13  indicates an OBP arranged on the printed circuit board  12  and generating a 3.3V voltage,  14  indicates an OBP arranged on the printed circuit board  12  and generating a 5V voltage,  15  indicates a copper foil power layer included in the printed circuit board  12  and forming a 3.3V power layer,  16  indicates a copper foil power layer included in the printed circuit board  12  and forming a 5V power layer,  17  indicates a via passing through the printed circuit board  12  for supplying the OBP  13  output voltage 3.3V to the power layer  15 ,  18  indicates a via passing through the printed circuit board  12  for supplying the OBP  14  output voltage 5V to the power layer  16 , and  19  to  24  are vias passing through the printed circuit board  12  corresponding to the power pins  1  to  6 . The bottom of the BGA  10  is shown by a cross-section along the dot-chain line of  FIG. 1A . The 3.3V power layer  15  is connected through the vias  19  to  21  to the power pins  1  to  3 , while the 5V power layer  16  is connected through the vias  22  to  24  to the power pins  4  to  6 .  
         [0008]     Instead of preparing the reference voltage V 2  inside the OBP  13 , a voltage output from the other OBP  14  generating the 5V voltage is divided by a voltage division circuit (formed on the printed circuit board  12 , but not shown) to prepare a 3.3V reference voltage V 2 .  
         [0009]     The BGA  10  is actually supplied with a plurality of types of power voltage and signals. For this reason, the printed circuit board  12  includes, though not shown, a plurality of other power layers and signal patterns.  
         [0010]      FIG. 2  shows one example of a circuit included in the BGA. In the figure,  22  indicates a driver and  24  a receiver. The BGA has inside it a driver circuit and a receiver circuit. The driver and the receiver are connected by connecting different BGAs. A single BGA never has the driver and receiver connected inside it. If considering this by  FIG. 2, 22  and  24  show the case of a different BGA driver circuit and receiver circuit connected by patterns on a printed circuit board. The driver  22  is supplied with the 3.3V power voltage V 1  and auxiliary power voltage V 3 , while the receiver  24  is supplied with the 3.3V power voltage V 1 . These power voltages are output from the OBP  13  and are supplied through the power layer  15  to the power pins  1  to  3 .  
         [0011]      FIG. 3  shows another example of a circuit included in the BGA. In the figure,  32  indicates a driver and  34  a receiver. The driver  32  is supplied with the 5V power voltage V 4  and the auxiliary power voltage V 6 , while the receiver  34  is supplied with the 5V power voltage V 5 . These power voltages are output from the OBP  14  and supplied through the power layer  16  to the power pins  4  to  6 .  
         [0012]     The reference voltage V 2  shown in  FIG. 2  is used as the criteria for judgment as to if the output voltage of the driver  32  of the circuit shown in for example  FIG. 3  is the high level or low level. For example, when the output voltage of the driver  32  is higher than 3.3V, it is judged that the voltage is the high level, while when it is 3.3V or less, it is judged as the low level.  
         [0013]     For reference to this related art, see Japanese Patent Publication (A) No. 2-003957, Japanese Patent Publication (B) No. 7-120227, and Japanese Patent Publication (A) No. 6-223632.  
         [0014]     In the case of a component like a BGA where a plurality of voltage power supplies are required, as shown in  FIGS. 1A and 1B , the situation where the V 1 , V 2 , and V 3  are the same voltages, but the applications differ frequently occurs in practice. In this example, the driver-receiver power voltage V 1  of  FIG. 2  is a voltage the same as the receiver reference voltage V 2  of  FIG. 3 . Further, physically, for example when using a 1 mm pitch BGA, since the distances between pins is in the narrow region of 1 mm, the pins are easily affected by each other in structure.  
         [0015]     In the circuit of  FIG. 2 , when a current I flows through the driver  22 , a noise in accordance with that current, that is, V n =LdI/dt, occurs at the power bar  15  and as a result the power layer  15  fluctuates in voltage and the reference voltage V 2  fluctuates. This being the case, the reference voltage for judging if the output voltage of the driver  32  of the circuit shown in  FIG. 3  is the high level or low level will fluctuate. For example, if the reference voltage V 2  changes to 3.5V and the output voltage of the driver  32  is 3.4V, while originally speaking the output of the driver  32  should be the high level, the change of this reference voltage causes it to be misjudged as the low level. Further, depending on the component, the component may also contain pins requiring an analog system power supply (PLL: phase-locked loop). In general, an analog system power supply is sensitive to noise, so for example even if the same voltage as the digital system power supply, physical separation is necessary. This is also one example where the voltages are the same, but the applications differ, so separation would be better.  
         [0016]     Further, there were the problem that a printed circuit board included a large number of power layers and signal layers and therefore the number of conductor layers provided in the printed circuit board was large and the dimensions became larger and the problem that if trying to make the printed circuit board smaller in thickness, the conductor layers became greater in mounting density and production became difficult. For example, when the BGA  10  is a 1152-pin field programmable gate array (FPGA), there are 3.3V Vccaux pins (eight pins), but specification-wise, these Vccaux pins have to be activated before all of the other power supplies (Vcc and Vref). For this reason, in the past, two separate layers, that is, a Vccaux power layer and a Vcco and Vref power layer, were necessary.  
       SUMMARY OF THE INVENTION  
       [0017]     An object of the present invention is to solve the problem of the reduction in the noise margin of the power supply system accompanying the lower drive voltages of electrical components such as BGAs and the noise between the power supply and the ground accompanying simultaneous switching waveforms.  
         [0018]     Another object of the present invention is to reduce the mounting density of the conductor layers included in the printed circuit board in a power feed device or reduce the thickness of the printed circuit board and thereby realize a smaller size.  
         [0019]     To achieve the above objects, the first aspect of the present invention provides a built-in capacitor type power feed device for an electrical component, comprising a power supply for supplying power, a printed circuit board including a signal line pattern, a power bar having conductive projections provided in shapes and at positions corresponding to the shapes and positions of electrodes of the electrical component and provided outside of the printed circuit board, a ground bar provided outside of the printed circuit board, and a high dielectric layer provided at a part corresponding to the electrical component between the power bar and the ground bar, power from the power supply being fed to electrodes of the electrical component through the power bar and the ground bar.  
         [0020]     According to the first aspect of the present invention, since the power bar and the ground bar are provided outside of the printed circuit board and a high dielectric layer is provided between the power bar and the ground bar, it is possible to reduce the mounting density of the printed circuit board or simplify the production of the printed circuit board. Further, since the power bar, high dielectric layer, and ground bar form a capacitor, a built-in capacitor type power feed device can be realized.  
         [0021]     According to a second aspect of the present invention, the electrical component is provided with ground use ground pins and power pins, the power bar is provided with holes provided at positions corresponding to the ground pins and insulated at their surroundings from the power bar and first conductive projections provided at positions corresponding to the power pins, the ground bar is provided with second conductive projections fitting into the holes, the first conductive projections are connected to the power pins of the electrical component through vias in the printed circuit board, and the second conductive projections are connected to the ground pins of the electrical component through other vias in the printed circuit board.  
         [0022]     According to the second aspect of the present invention, since the power bar, high dielectric layer, and ground bar are provided below the printed circuit board in that order, in the built-in capacitor type power feed device, the power bar and ground bar are free from the effects of voltage fluctuations in a power layer in the printed circuit board, therefore the quality of transmission of signals in the electrical component can be improved.  
         [0023]     According to a third aspect of the present invention, the electrical component is provided with ground use ground pins and power pins, the ground bar is provided with first conductive projections provided at positions corresponding to the ground pins and holes provided at positions corresponding to the power pins and insulated at their surroundings from the ground bar, the power bar provided with second conductive projections fitting into the holes, the first conductive projections are connected to the ground pins of the electrical component through vias in the printed circuit board, and the second conductive projections are connected to the power pins of the electrical component through other vias in the printed circuit board.  
         [0024]     According to the third aspect of the present invention, since the ground bar, high dielectric layer, and power bar are provided below the printed circuit board in that order, in the built-in capacitor type power feed device, the power bar and ground bar are free from the effects of voltage fluctuations in a power layer in the printed circuit board, therefore the quality of transmission of signals in the electrical component can be improved.  
         [0025]     According to a fourth aspect of the present invention, the power bar and the ground bar are provided between the printed circuit board and the electrical component, and the power bar and the ground bar are directly connected to the electrical component without going through vias of the printed circuit board.  
         [0026]     According to the fourth aspect of the present invention, since the power bar and ground bar are directly connected to the electrical component without going through vias of the printed circuit board, compared with the case of connection through vias, the effect of high frequency noise can be reduced.  
         [0027]     According to a fifth aspect of the present invention, there are a plurality of power bars and there are a plurality of ground bars provided between the plurality of power bars sandwiching high dielectric layers.  
         [0028]     According to the fifth aspect of the present invention, even when there are a plurality of power supplies, since high dielectric layers are provided between the power bars and ground bars corresponding to these plurality of power supplies, it is possible to further reduce the mounting density of the printed circuit board, realize further simplification of the production of the printed circuit board, and realize a built-in capacitor type power feed device for a plurality of power supplies.  
         [0029]     According to the sixth aspect of the present invention, the power bar and the ground bar are provided between the printed circuit board and the electrical component, the power pins and ground pins of the electrical component are directly connected to the power bar and the ground bar without going through vias of the printed circuit board, and the power bar and the ground bar are also connected to vias of the printed circuit board. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0030]     These and other objects and features of the present invention will become clearer from the following description of the preferred embodiments given with reference to the attached drawings, wherein:  
         [0031]      FIG. 1A  is a plan view, as seen from below, of a BGA fed with power by a conventional power feed device, while  FIG. 1B  is a cross-sectional view showing an example of a conventional power feed device;  
         [0032]      FIG. 2  shows an example of a circuit included in the BGA;  
         [0033]      FIG. 3  shows another example of a circuit included in the BGA;  
         [0034]      FIGS. 4A  to  4 D are views for explaining the basic configuration of a built-in capacitor-type power feed device according to Example 1 of the present invention;  
         [0035]      FIG. 5  is a cross-sectional view of a built-in capacitor-type power feed device according to Example 3 of the present invention.  
         [0036]      FIG. 6  is a cross-sectional view of a built-in capacitor-type power feed device according to Example 4 of the present invention;  
         [0037]      FIG. 7  is a cross-sectional view of a built-in capacitor-type power feed device according to Example 5 of the present invention;  
         [0038]      FIG. 8  is an enlarged view showing part of  FIG. 7 ;  
         [0039]      FIG. 9  is a graph of the frequency characteristics of a conventional COH configuration power feed device, a built-in capacitor type power feed device according to Example 1 of the present invention shown in  FIGS. 4A  to  4 D, and a power feed device of the built-in capacitor type shown in  FIG. 5  and given measures against high frequency;  
         [0040]      FIG. 10A  to  10 D are plan views of a built-in capacitor-type power feed device according to Example 6 of the present invention, wherein  FIG. 10A  is a plan view of a BGA  10 ,  FIG. 10B  is a plan view of a power supply A side power bar,  FIG. 10C  is a plan view of a ground side power bar, and  FIG. 10D  is a power supply B side power bar; and  
         [0041]      FIG. 11A  is a plan view of a multi-power supply power bar shown in  FIGS. 10A  to  10 D, while  FIG. 11B  is a cross-sectional view of a multi-power supply power bar. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0042]     Below, preferred embodiments of the invention will be explained in detail with reference to the attached drawings.  
       EXAMPLE 1  
       [0043]      FIGS. 4A  to  4 D are views explaining the basic configuration of a built-in capacitor type power feed device according to Example 1 of the present invention.  FIG. 4A  is the same as the conventional view shown in  FIG. 1A  viewing the BGA  10  from the back. In the figure, the circles  41  shown by the black dots are ground use ground pins, the circles  42  half filled in with black indicate the power pins  42 , and the circles indicated by  43  indicate the signal pins. These pin are formed by solder balls at the back surface of the BGA  10 . Reference numeral  44  shown at the right of the BGA  10  in the figure is an OBP, while reference numerals  45  and  46  shown by dotted lines indicate conductive patterns formed at the back surface of the printed circuit board  50  (see  FIG. 4D ) for electrical contact with the power bar  48  or ground bar  49 .  
         [0044]      FIG. 4B  is a plan view of a power bar  48 . As illustrated, the power bar  48  is comprised of a main body part  481  of substantially the same shape as the BGA  10  and a bar part  482 . The width of the bar part  482  is shown as being narrower than the width of the main body part  481 , but does not necessarily have to be narrower. It may also be made wider when there is a reason such as keeping the voltage drop low, increasing the capacity of the capacitor, etc. The main body part  481  is provided with holes  411  provided at positions corresponding to the ground pins  41  of the BGA  10  and cylindrical conductive projections  421  provided at positions corresponding to the power pins  42  of the BGA  10 . The conductive projections  421  are not limited in shape to cylinders. The holes  411  are coated around them with an insulating material, preferably a high dielectric, so as to be electrically insulated from the power bar  48 .  
         [0045]      FIG. 4C  is a plan view of the ground bar  49 . As illustrated, the ground bar  49  is also comprised of a main body part  491  of substantially the same shape as the BGA  10  and a bar part  492 . The width of the bar part  492  is shown as being narrower than the width of the main body part  491 , but does not necessarily have to be narrower. It may also be made wider when there is a reason such as keeping the voltage drop low, increasing the capacity of the capacitor, etc. The main body part  491  is provided with conductive projections  412  provided at positions corresponding to the ground pins  41  of the BGA  10 . The conductive projections  412  are not limited in shape to cylinders. The holes  411  of the power bar  48  are made somewhat larger than the conductive projections  412  of the ground bar  49 . They are designed so that when the power bar  48  and the ground bar  49  are overlaid, the conductive projections  412  fit tightly into the holes  411 .  
         [0046]      FIG. 4D  is a cross-sectional view of a built-in capacitor type power feed device according to Example 1. As illustrated, the output power pin  51  of the OBP  44  arranged at the right side of the printed circuit board  50  in the illustration is electrically connected to the conductive projections  54  of the power bar  48  through the conductive pattern  52  formed on the printed circuit board  50 , the via  53  passing through the printed circuit board  50 , and the conductive pattern  45 .  
         [0047]     The BGA  10  is mounted at on the printed circuit board  50  at the left side in the illustration. The ground pins  41  of the BGA  10  are connected to the ground bar  49  through vias  413  passing through the printed circuit board  50  and conductive projections  412  fit in holes  411  of the power bar  48 . The holes  411  are formed at their surroundings with electrical insulating materials or spaces are provided from the power bar  48  to insulate them from the power bar  48 . The main body part  491  of the ground bar  49  is connected through the bar part  492  to the ground pins of the OBP  44  through conductive projections, vias, and conductive patterns formed at the bottom side of the printed circuit board  50  (in the figure, hidden since at back of power bar  49 ).  
         [0048]     The power pins  42  of the BGA  10  are electrically connected to the power bar  48  through other vias  422  passing through the printed circuit board  50  and conductive projections  421  of the power bar  48 .  
         [0049]     The main body part  481  of the power bar  48  and the main body part  491  of the ground bar  49  are provided between them, according to the present invention, with a high dielectric layer  55 . The main body part  481 , high dielectric layer  55 , and main body part  491  form a capacitor  56 . Due to this, a built-in capacitor type power feed device is formed. This built-in capacitor type power feed device realizes substantially the same noise performance as the case of mounting  125  0.1 μF capacitors by chip on hole (COH) configuration. By realizing such a built-in capacitor type power feed device, it is no longer necessary to separately provide any capacitor for removal of high frequency noise in the power feed device.  
         [0050]     The BGA  10  and the OBP  44  are mounted by an ordinary reflow process on the printed circuit board  50 . The power bar  48  and ground bar  49  can also be similarly mounted, but if the power bar or ground bar is thick or when large in volume, it will become larger in heat capacity and may conceivably be hard to raise in temperature by the reflow heat. In this case, the power bar  48  and ground bar  49  may be fastened to the printed circuit board  50  by screws etc. The parts of the printed circuit board  50  other than the not shown signal layers and power layers are insulators.  
         [0051]     According to the basic configuration of the built-in capacitor type power feed device shown in  FIGS. 4A  to  4 D, since the power bar and ground bar are provided outside of the printed circuit board  50 , it becomes possible to reduce the number of the power layers inside the printed circuit board  50 . Further, by sandwiching a high dielectric layer  55  between the power bar  48  and the ground bar  49 , it is possible to realize a large capacity capacitor in the power feed device and it is no longer necessary to mount a large number of capacitors such as with a COH configuration.  
       EXAMPLE 2  
       [0052]     In Example 1, the power bar  48  was arranged under the printed circuit board  50 , the high dielectric layer  55  was provided under that, and the ground bar  49  was arranged under that, but it is also possible to reverse the positional relationship between the power bar and ground bar. That is, it is also possible to arrange the ground bar  49  under the printed circuit board  50 , provide the high dielectric layer  55  under that, and arrange the power bar  48  under that. In this case, first conductive projections are provided at positions corresponding to the ground pins  41  of the ground bar  49  and holes are provided at positions corresponding to the power pins  42 . Further, the power bar  48  is provided with second conductive projections fitting into holes provided at the ground bar  49 . Further, the first conductive projections may be connected to the ground pins of the electrical component through vias in the printed circuit board, while the second conductive projections may be connected to power pins of the electrical component through other vias in the printed circuit board.  
       EXAMPLE 3  
       [0053]      FIG. 5  is a cross-sectional view of a built-in capacitor type power feed device according to Example 3 of the present invention. In Example 3, a power bar  71  and ground bar  72  are provided between the BGA  10  and the printed circuit board  70 . The power bar  71  and the ground bar  72  are electrically separated by a high dielectric layer  73 . The BGA  10  is provided with not only power pins  2 , but also ground use power pins  74  and signal transmission use signal pins  75 . Reference numeral  76  shows connection pins for connecting the signal pins  75  to a signal layer (not shown) included in the printed circuit board  70 , while  77  shows insulators for electrically insulating the signal pins  75  from the power bar  71  and ground bar  72 . The connection pins  76  are cylindrically shaped, while the insulators  77  are shaped as hollow tubes able to surround them. The signal pins  75  of the BGA  10  are connected through connection pins  76  passing through the power bar  71  and insulation layer  73  and ground bar  72  to the vias  78 . The power bar  71 , ground bar  72 , and high dielectric layer  73  are formed with holes for passage of the signal pins  76 . The vias  78  are connected with a signal layer (not shown) in the printed circuit board  70 . The connection pins  76  are connected to the vias  78  by reflow soldering, or the power bar  71  and ground bar  72  themselves are fastened by screws (not shown) to the printed circuit board  70  for connection to the signal layer included in the printed circuit board  70 .  
         [0054]     Due to this configuration, a high dielectric layer is sandwiched between the power bar and ground bar enabling realization of a built-in capacitor type power feed device, while the power bar and ground bar are directly connected to the BGA  10  without going through vias of the printed circuit board, so there is an effect of reduction of the high frequency noise.  
         [0055]     In general, vias in a printed circuit board have large inductances in the high frequency region and pose major problems even when the printed circuit board is at most 2 mm or so in thickness. As a measure against high frequency noise, in general a capacitor is mounted in the circuit in the printed circuit board. According to the present embodiment, however, since the state is the same as if mounting a capacitor directly under the BGA  10  and the power bar is directed connected to the BGA  10  without going through the printed circuit board, this is extremely effective as a measure against high frequency noise.  
       EXAMPLE 4  
       [0056]      FIG. 6  is a cross-sectional view of a built-in capacitor type power feed device according to Example 4 of the present invention. In the figure, parts the same as in  FIG. 5  are assigned the same reference numerals and explanations are omitted. The differences from  FIG. 5  are that in  FIG. 6 , the power bar  71  is not only connected to the power pins  2 , but is also connected to a via  781  passing through the printed circuit board  70  and that the ground bar  72  is not only connected to the ground use power pins  74 , but is also connected to a via  782  passing through the printed circuit board  70 . Reference numeral  771  is an insulator. While not shown in  FIG. 6 , the printed circuit board  70  includes a power layer and ground layer. The via  781  is electrically connected to this power layer, while the via  782  is electrically connected to this ground layer. Due to this, the power bar  71  and the power layer in the printed circuit board  70  are connected in parallel and the ground bar  73  and the ground layer in the printed circuit board  70  are connected in parallel, so the effect due to the voltage drop can be reduced.  
       EXAMPLE 5  
       [0057]      FIG. 7  is a cross-sectional view of a built-in capacitor type power feed device according to Example 4 of the present invention. In the figure, parts the same as in  FIG. 5  are assigned the same reference numerals, and explanations are omitted. A power bar  71  is made from copper or another metal originally having a high electric conductivity, so by providing part of the power bar  71  with at least one of plate type heat radiating fins  81  and disk type heat radiating fins  82 , it is possible to obtain a heat radiating structure. Further, if providing part of the plate type heat radiating fins  81  with slits  83  to enable part of the disk type heat radiating fins  82  to slide, a further larger heat radiating effect is obtained.  
         [0058]      FIG. 8  is an enlarged view showing an example of providing part of the plate type heat radiating fins  81  explained in  FIG. 7  with slits  83  to enable part of the disk type heat radiating fins  82  to slide.  
         [0059]      FIG. 9  is a graph of the frequency characteristics of a conventional COH configuration power feed device, a built-in capacitor type power feed device according to Example 1 of the present invention shown in  FIGS. 4A  to  4 D, and a power feed device of the built-in capacitor type shown in  FIG. 5  and given measures against high frequency. In the figure, the solid line curve shows the frequency characteristic of the COH configuration, the dotted line curve the frequency characteristic of a built-in capacitor type power bar, and the dot-chain line curve the frequency characteristic of a power bar of the built-in capacitor type given measures against high frequency. As illustrated, near 10 MHz, compared with the frequency characteristic of the COH configuration, the frequency characteristic of the built-in capacitor type power bar shown in  FIGS. 4A  to  4 D and the frequency characteristic of the power bar of the built-in capacitor type shown in  FIG. 5  given measures against high frequency can be suppressed in noise to the single digit level. Further, at 10 MHz to 1 GHz high frequency, the frequency characteristic of the power bar of the built-in capacitor type shown in  FIG. 5  given measures against high frequency, compared with the frequency characteristic of the COH configuration and the frequency characteristic of the built-in capacitor type power bar, can be suppressed in noise to the single digit level.  
       EXAMPLE 6  
       [0060]      FIGS. 10A  to  10 D are plan views of a built-in capacitor type power feed device according to Example 6 of the present invention. In the figures,  FIG. 10A  is a plan view of a BGA  10 ,  FIG. 10B  is a plan view of a power supply A side power bar,  FIG. 10C  is a plan view of a ground side power bar, and  FIG. 10D  is a plan view of a power supply B side power bar. In this way, in the present example, a single BGA has two power supplies  122  (A) and  123  (B) connected to it.  
         [0061]     The BGA  10  shown in  FIG. 10A  is the same as that shown in  FIGS. 1A and 1B  and is provided with ground pins  1 , power pins  2 , and power pins  3 .  
         [0062]     In  FIG. 10B, 124  indicates a power bar connected to a power supply A side  122  and provided at its main body part with cylindrical conductive projections  125  corresponding to the power pins  3 , holes  126  corresponding to the ground pins  1 , and holes  127  corresponding to the power pins  2 .  
         [0063]     In  FIG. 10C, 128  indicates a ground side power bar connected to the power supply A side  122  and provided at its main body part with cylindrical conductive projections  129  corresponding to the ground pins  1  and holes  130  corresponding to the power pins  2 .  
         [0064]     In  FIG. 10D, 131  indicates a power bar connected to the power supply B side  123  and provided at its main body part with cylindrical conductive projections  132  corresponding to the power pins  2 . By superposing these three power bars  124 ,  128 , and  131 , a multi-power supply power bar can be realized.  
         [0065]      FIG. 11A  is a plan view of the multi-power supply power bar shown in  FIG. 10A  to  10 D, while  FIG. 11B  is a cross-sectional view of a multi-power supply power bar as seen from the arrow A direction in  FIG. 11A . As will be understood from  FIG. 11A , the bar parts of the power bars are arranged offset in the lateral direction. In  FIG. 11B, 133  indicates a high dielectric layer between the power bar  124  and the main body part of the power bar  128 , and  134  indicates a high dielectric layer between the power bar  128  and the main body part of the power bar  131 . In the example shown in  FIGS. 10A  to  10 D and  FIGS. 11A and 11B , the case of two power supplies is shown, but even if the number of power supplies is three or more, this can be similarly dealt with by adding power bars under the printed circuit board  132  and holes in the power bars superposed with the same.  
         [0066]     As clear from the above explanation, according to the present invention, by arranging the power bar and ground bar outside of the printed circuit board and providing a high dielectric layer sandwiched between the power bar and ground bar, it is possible to reduce the number of power layers included in the printed circuit board and reduce the mounting density of the printed circuit board or simplify the production of the printed circuit board and realize a built-in capacitor type power feed device. Further, the power bar is free from the effects of voltage fluctuations of a power layer in the printed circuit board, therefore it is possible to improve the quality of transmission of the signals in the electrical component. Further, by having the power bar directly connected to the electrical component without going through vias of the printed circuit board, it is possible to reduce the effects of high frequency noise compared with the case of connection through vias. Further, since the power bar is insulated from the power layer in the printed circuit board, the power bar is free from the effects of voltage fluctuations in the power layer in the printed circuit board, therefore it is possible to improve the quality of transmission of the signals in the electrical component. Further, even when there are a plurality of power supplies, since a plurality of power bars corresponding to the plurality of power supplies are provided outside of the printed circuit board, it is possible to further reduce the mounting density of the printed circuit board and further simplify the production of the printed circuit board.  
         [0067]     While the invention has been described with reference to specific embodiments chosen for purpose of illustration, it should be apparent that numerous modifications could be made thereto by those skilled in the art without departing from the basic concept and scope of the invention.