Electricity: electrical systems and devices – Electrostatic capacitors – Fixed capacitor
Reexamination Certificate
2002-06-28
2003-06-10
Dinkins, Anthony (Department: 2831)
Electricity: electrical systems and devices
Electrostatic capacitors
Fixed capacitor
C361S766000, C174S260000
Reexamination Certificate
active
06577490
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wiring board for mounting electronic parts, and in particular to a wiring board mounting chip capacitors on a reverse face side.
BACKGROUND OF THE INVENTION
IC chips has become higher speed in actuation owing to progress of technique of integrated circuit, and being accompanied therewith, noises are accumulated on such as wiring of electric source and bring about erroneous actuation. For removing noises, for example, as seen in
FIG. 22
, a wiring board
2
mounting IC chip
1
thereon is separately mounted with chip capacitors
3
on a principal face
2
b
or a reverse face
2
c,
and capacitor-connecting wiring
4
is provided within the wiring board for respectively connecting two electrodes of the capacitors
3
. Thereby, the chip capacitors
3
are connected to a source terminal or an earth terminal of IC chip
1
via the capacitor-connecting wiring
4
and flip-chip pad
5
.
However, depending on the above technique, the capacitor-connecting wiring
4
connected to the chip capacitors
3
are drawn around within the wiring board
2
. When changing positions of terminals of IC chip
1
, it has been necessary to re-design a whole wiring including the capacitor-connecting wiring
4
. Especially, IC chip of high integration degree is often formed with lots of source terminals and earth terminals, and the drawing-around is easily subject to complication. In addition, in case of mounting many chip capacitors or connecting the chip capacitors having many terminals, the drawing-around also becomes complicated.
SUMMARY OF THE INVENTION
The invention has been accomplished in view of these problems, and it is an object of the invention to provide a wiring board making ready for connecting electronic parts mounted on the principal face side of the wiring board with chip capacitors mounted on the reverse face side thereof.
Means for solving the problems is a wiring board having a principal face and a reverse face, comprising a plurality of principal-face-side connecting terminals formed on the principal face side and connectable to respective terminals of electronic parts to be mounted on the principal face side, chip capacitors mounted on the reverse face side furnished with a first electrode and a second electrode composing capacitors, at least one of the chip capacitors having a first face facing to the reverse face, at least one of first terminals formed on the first face and connected to the first electrode, and at least one of second terminals formed on the first face and connected to the second electrode, first capacitor-connecting terminals formed on the reverse face side and connected to the respective first terminals of the chip capacitors, second capacitor-connecting terminals formed on the reverse face side and connected to the respective second terminals of the chip capacitors, a plurality of insulating layers interposed among the principal-face-side connecting terminals, the first capacitor-connecting terminals, and the second capacitor-connecting terminals, at least one of first converting-conductor layers formed at specific interlayer selected from interlayers of the mutual insulating layers, connected to the plurality of principal-face-side connecting terminals at the principal face side, connected to at least one of first capacitor-connecting terminals at the reverse face side, and changing the connecting positions and the connecting number between the principal face side and the reverse face side, and at least one of second converting-conductor layers formed at the specific interlayer while being insulating the first converting-conductor layers, connected to the plurality of principal-face-side connecting terminals at the principal face side, connected to at least one of second capacitor-connecting terminals at the reverse face side, and changing the connecting positions and the connecting number between the principal face side and the reverse face side.
The wiring board of the invention is formed with the first and the second converting-conductor layers for changing the connecting positions and the connecting number between the principal face side and the reverse face side at the same specific interlayer. The first converting-conductor layers are connected to the principal-face-side connecting terminals at the principal face side, and to the first capacitor-connecting terminals at the reverse face side. Further, the second converting-conductor layers are connected to the principal-face-side connecting terminals at the principal face side, and to the second capacitor-connecting terminals at the reverse face side. Therefore, the connection between the principal-face-side connecting terminals and the first and second capacitor-connecting terminals is easily provided. Accordingly, the connection between terminals of the electronic parts and the first and second terminals is easily made.
As the chip capacitors, any of them are sufficient if being able to be mounted on the wiring board. For example, there are enumerated laminated ceramic types, electrolytic capacitor types, or film capacitor types. In particular, the chip capacitors of the laminated ceramic type have desirable frequency characteristics, and being effected with heat, the characteristics are comparatively stable.
Besides, the first and second terminals formed on the first faces of the chip capacitors are preferably many formed. Because, by forming many, those may be connected in parallel with the first and second converting-conductor layers, and resistance and inductance occurring at wiring between the first, second converting-conductor layers and the chip capacitors may be more reduced. Therefore, the first and second terminals of the chip capacitors are sufficient with those formed on the periphery of the first face, but preferable are such terminals arranged in, e.g., lattice within the first face.
More preferable are that the first terminal and the second terminal are alternately arranged in a manner that, seeing from a certain first terminal, a nearest terminal to this first terminal is a second terminal. The current flowing via the first terminal and the current flowing via the second terminal are opposite to each other with regard to direction when charging and discharging the chip capacitors, and also in this regard, inductance can be decreased.
As the wiring board, there are listed resins such as epoxy resin, polyimide resin, BT resin or PPE resin, composite materials of fibers such as glass fiber or polyester fiber with the resins, or resin composite materials of fluorine resin having three dimensional network structure impregnated with epoxy resin. Further listed are ceramic boards made of alumina, mullite, aluminum nitride or glass ceramic, or combinations of the ceramic board with the resins or composite materials.
Around the principal-face-side connecting terminals and the first and the second capacitor-connecting terminals, solder resist layers may be formed for securing the mutual insulation and preventing solder wetted spread.
In the wiring board as mentioned above, it is preferred that as the specific interlayer, the nearest interlayer to the first capacitor-connecting terminals and the second capacitor-connecting terminals among the interlayers of the mutual insulating layers are selected, and the number of the principal-face-side connecting terminals connected to any of the first converting-conductor layers and the second converting-conductor layers of the principal-face-side connecting terminals is more than the sum of the number of the first capacitor-connecting terminals connected to the first converting-conductor layers+(plus) the number of the second capacitor-connecting terminals connected to the second converting-conductor layers.
The wiring of connecting the principal-face-side connecting terminals and the first, second capacitor-connecting terminals (the first and the second terminals of the chip capacitors) can restrain resistance value and inductance, the more the parallel paths. Accordingly, seeing fr
Ogawa Kouki
Sugimoto Yasuhiro
Dinkins Anthony
NGK Spark Plug Co. Ltd.
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