JPH04245409A - Inductor device - Google Patents

Abstract

PURPOSE:To lower the cost of the title device and to increase its reliability by a method wherein a spiral interconnection which acts electromagnetically as effective as an inductor by utilizing a multilayer interconnection and a through hole in an electronic-component mounting board is formed around a ferromagnetic-material chip which is mounted on and fixed to the board. CONSTITUTION:A ferromagnetic-material chip 2 is fixed to an electronic- component mounting board 1 by a mounting operation using a solder. An electric current flowing in a wiring print 3 is passed sequentially through a through hole 7, a wiring print 4, a through hole 8, a wiring print 5 and a through hole 9 and reaches a wiring print 6. The electric current flows graphically in a spiral shape; it is influenced by a magnetic field from the ferromagnetic-material chip 6 and yields the same effect as an inductor. Thereby, the inductor can be surface-mounted, the electrical connection of a lead-wire part to a wiring part at the board is eliminated, the cost of the title device is lowered and the reliability of the title device can be enhanced.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induct device comprising electronic elements that realize inductance electromagnetically.

0002

[Prior Art] A conventional inductor device is constructed in such a way that a lead wire is wound spirally around a ferromagnetic material, and both ends of the lead wire are fixed to holes on an electrical component mounting board with solder. There is.

0003

[Problem to be Solved by the Invention] However, in the above conventional example, a lead wire is wound spirally around the ferromagnetic material, and both ends of the lead wire are fixed to holes on the electrical component mounting board with solder. Due to this structure, there were the following problems.

First, recently, electrical components other than inductors, such as LSIs, resistors, and capacitors, have been increasingly surface-mounted. Implementation is expensive.

[0005]Secondly, since the components of the lead wire section cannot be shared with the wiring on the electrical component mounting board, the cost for the components of the lead wire section increases.

Third, since the lead wire section and the wiring section on the electrical component mounting board must be electrically connected, the structure becomes complicated and reliability decreases.

The present invention aims to solve the above problems. That is, an object of the present invention is to provide an inductor device that can reduce costs and has high electrical reliability.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention has a ferromagnetic chip mounted and fixed on an electrical component mounting board, and has a ferromagnetic chip mounted around the ferromagnetic chip. The spiral wiring is formed using the multilayer wiring and through holes of the electrical component mounting board and has the same electromagnetic effect as an inductor.

[0009]

[Operation] According to the present invention, a spiral wiring is formed around a ferromagnetic chip mounted and fixed on an electrical component mounting board using the multilayer wiring and through holes of the electrical component mounting board. Therefore, electromagnetically, the spiral wiring has the same effect as a spiral lead wire.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a plan view showing an embodiment of the present invention, and FIG. 2 is an enlarged sectional view thereof.

In the figure, reference numeral 1 denotes an electrical component mounting board. A ferromagnetic chip 2 is fixed to the electrical component mounting board 1 by soldering. 3 is a wiring print on the top surface, 4 and 5 are wiring prints on the intermediate layer, 6 is a wiring print on the bottom surface, and 7, 8, and 9 are through holes that are electrically connected.

[0012] Then, the wiring prints 3, 4, 5, 6
is formed in a truncated arc shape around the ferromagnetic chip 2 when viewed from the ferromagnetic chip 2.

Therefore, the current flowing through the wiring print 3 passes through the through hole 7, the wiring print 4, the through hole 8, the wiring print 5, and the through hole 9, and reaches the wiring print 6 in this order. This current flows in a spiral pattern. Therefore, it is influenced by the magnetic field from the ferromagnetic chip 2 and produces an effect similar to that of an inductor. The same effect is produced even if the direction of current flow is reversed.

FIG. 3 shows the wiring pattern of the intermediate layer, in which 10 and 11 are through holes, and 12 is a wiring print.

[0015] As another embodiment of the present invention, a hole is made in the electrical component mounting board and a ferromagnetic chip is embedded in the hole to increase the effect of the magnetic field. It will be done. In other words, the ferromagnetic chip is fixed to the center of the printed wiring and through-holes, where current flows in a spiral manner. Further, in FIG. 2, a four-layer printed board is used as an example, but the same method can be applied to any printed board with any number of layers. Furthermore, the position of the through hole and the shape of the printed wiring are also
There is no need to limit it to a specific one, and the same effect can be obtained if the current flows spirally.

[0016]

[Effects of the Invention] As explained above, according to the present invention,
A ferromagnetic chip is mounted and fixed on an electrical component mounting board, and around it, using the multilayer wiring and through holes of the electrical component mounting board, a spiral wiring is realized to achieve the same effect as an inductor. Since it is possible to use the recent surface mount L
Similar to electronic components such as Si, resistors, and capacitors, surface mounting is also possible with inductors. Therefore, all electronic components can be surface mounted, and costs can be reduced.

Furthermore, since the parts of the lead wire section and the wiring on the electrical component mounting board can be shared, the cost for the parts of the lead wire section is reduced.

Furthermore, electrical reliability is improved because there is no electrical connection between the lead wire section and the wiring section on the electrical component mounting board, and it can be realized only by printed wiring.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of FIG. 1;

FIG. 3 is a plan view showing a wiring pattern of an intermediate layer.

[Explanation of symbols]

1...Electrical component mounting board 2...Ferromagnetic chip 3, 4, 5, 6...Wiring print 7
, 8, 9...Through hole

Claims (1)

[Claims] Claim 1: A ferromagnetic chip mounted and fixed on an electrical component mounting board, and formed around the ferromagnetic chip using multilayer wiring and through holes of the electrical component mounting board. An inductor device characterized in that it has a spiral wiring that electromagnetically has the same effect as an inductor.