JPH05145364A - High frequency filter and non-adjustment method for the high frequerncy filter - Google Patents

Abstract

PURPOSE:To reduce the manufacture cost by mounting a coil and a capacitor onto a board to manufacture the high frequency filter with respect to the high frequency filter and the non-adjustment method for the high frequency filter so as to obtain a desired characteristic with no adjustment. CONSTITUTION:A capacitor C being a component of a high frequency filter is mounted on a 1st layer 1-1 being a front side layer of a multi-layer board as a discrete component, and a coil L is formed on a layer (e.g. 2nd layers 1-2-4th layer 1-4) beneath the layer 1-1 with a thick film coil pattern 2. The capacitance of the capacitor C is set to a prescribed capacitance at the time of mounting, and the coil pattern is designed to obtain a desired filter characteristic with respect to the capacitor C to apply patterning to the coil L.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency filter in which a capacitor and a coil forming an LC resonance circuit are mounted on a multi-layer substrate, and a method for adjusting the high frequency filter.

[0002]

5 and 6 are explanatory views of a conventional example. FIG. 5A is a circuit example of a high frequency filter, FIG. 5B is a characteristic example of a high frequency filter, FIG. 6A is an exploded perspective view of the high frequency filter, and FIG. It is a perspective view of a high frequency filter (SMD).

In the figure, C _{1 to} C ₈ are capacitors, and L _{1 to} L
₃ is a coil, IN is an input terminal, OUT is an output terminal, 1-
Reference numerals 1 to 1-3 are first to third layers of the multilayer substrate, 2 is a coil pattern, 3 is a capacitor electrode pattern, 4 is a GND electrode (side electrode), 5 is an input terminal (IN) electrode (side electrode). ), 6 are electrodes (side electrodes) for the output terminal (OUT).

As a conventional high-frequency filter having an LC resonance circuit composed of a coil and a capacitor, for example, FIG.
A circuit like was known. This high frequency filter
It is an example of a bandpass filter, and capacitors C _{1 to} C ₈
And coils L _{1 to} L ₃ .

The high frequency filter (bandpass filter) has the bandpass characteristic (frequency characteristic) shown in FIG. 5B. Of these characteristics, the center frequency f ₀ , the band width, and the side-band limiting characteristics are particularly important.

By the way, the capacitors C _{1 to} C ₈ and the coils L _{1 to} L ₃ are used by mounting them on a substrate. At this time, in order to create the bandpass characteristics, the capacitors and the coils must be accurate. It is necessary to make it well.

Therefore, conventionally, it has been considered to mount a capacitor and a coil on a substrate as follows. FIG. 6 is an implementation example thereof, FIG. 6A is an exploded perspective view of a high-frequency filter (bandpass filter), and FIG. 6B is a perspective view of a high-frequency filter (SMD-equipped bandpass filter).

In FIG. 6, a coil and a capacitor are formed on the multilayer substrate by a thick film pattern. In this case, at least some electrodes of the capacitor are formed on the surface of the multilayer substrate. Then, by trimming the capacitor electrodes on the surface, the characteristics as shown in FIG. 5B are created.

That is, a multilayer substrate 1 is used as a substrate, and its first layer (surface layer) 1-1, second layer 1-2, third layer 1-3 are used.
The coil pattern 2 and the capacitor electrode pattern 3 are respectively patterned on the upper side by printing. Then, the dotted line portions in the drawing are connected by blind through holes (through holes whose insides are filled with conductors) to form the circuit configuration of FIG. 5A.

After stacking the first layer 1-1 to the third layer 1-3, the GND electrode 4, the input terminal (IN) electrode 5, and the output terminal (OUT) are formed on the side surface of the multilayer substrate 1. Electrode 6
Is formed by printing and is connected to the internal pattern. As a result, the high-frequency filter is realized as an SMD (surface mount component).

The high frequency filter (bandpass filter) is a filter used particularly in a frequency band of 100 MHz or more, and the substrate material may be ceramic or resin as long as it has a low dielectric constant.

The coils L _{1 to} L ₃ are air core coils whose inductance is determined by the pattern and the number of turns, without using a magnetic material. Therefore, the inductance of the coil can be obtained very stably during manufacturing.

However, the capacitors C _{1 to} C ₈ depend on the thickness of the dielectric layer (insulating layer) between the respective layers, and these thicknesses cannot be made completely constant during mass production. For this reason,
The variation in the thickness of the dielectric layer is the same as that of each capacitor C ₁
It becomes capacity variation of -C _8, as a characteristic variation of the filter.

Therefore, some electrodes of each capacitor are patterned on the surface layer 1-1 of the multi-layer substrate, and are also patterned to a size capable of covering the variation in capacitance by trimming. Then, by trimming the capacitor electrode pattern on this surface, the bandpass characteristic as shown in FIG. 5B was obtained.

[0015]

SUMMARY OF THE INVENTION The above-mentioned conventional device has the following problems. (1) When a high-frequency filter is manufactured by patterning a capacitor electrode pattern or a coil pattern on each layer of a multilayer substrate, a stable inductance can be obtained for the coil, but the capacitance of the capacitor will vary greatly.

For this reason, some electrodes of the capacitor are patterned on the surface of the multi-layer substrate, and the capacitor electrode pattern on the surface is trimmed to obtain predetermined characteristics.

As described above, when the high frequency filter is manufactured, it is premised on the trimming of the capacitor electrode pattern, so that the step of obtaining characteristics by trimming is required. Therefore, the manufacturing process becomes complicated and the manufacturing cost becomes high.

(2) In the process of obtaining the characteristic by the trimming, for example, in the case of the examples of FIGS. 5 and 6, it is necessary to adjust all eight capacitors by the trimming, and it is necessary to adjust the time while observing the characteristic. It takes a lot of time to put a limit on the quantity that can be mass-produced. Moreover, since the trimming position changes depending on the type of filter, it is difficult to design a machine for trimming, and it is currently done manually. As a result, there are variations in adjustment among workers.

Particularly in recent years, miniaturization of modules has progressed, and trimming electrodes have also become extremely small, so that the trimming work (for example, the work of scraping the electrodes with a router) is troublesome, and this process requires a filter manufacturing cost. Was pushing up a lot.

(3) Further, when the high-frequency filter is made into the SMD, it is necessary to design it so as not to be influenced by the mother board to be mounted. Therefore, if a GND pattern is added to the bottom layer of FIG. 6, capacitors C ₅ and C ₇
Unnecessary capacitance between GND is generated in each capacitor except (capacitor whose one electrode is connected to GND).

For this reason, frequency deviation and insertion loss due to impedance mismatching occur, and it becomes impossible to match, for example, the characteristics shown in FIG. 5B. Therefore, such a design becomes extremely difficult.

The present invention solves such a conventional problem, and when a coil and a capacitor are mounted on a substrate to manufacture a high frequency filter, desired characteristics can be obtained without adjustment and the manufacturing cost is reduced. The purpose is to do.

[0023]

FIG. 1 is a principle view of the present invention, FIG. 1A is an exploded perspective view of a high frequency filter, and FIG. 1B is a sectional view taken along line XY of FIG. 1A. In the figure, 1-1 to 1
-4 is the first to fourth layers of the multilayer substrate, and 2 is a coil pattern.

In order to solve the above problems, the present invention has the following configuration. (1) In a high-frequency filter in which a capacitor C and a coil L that form an LC filter circuit are mounted on a multilayer substrate 1,
A capacitor C composed of discrete components is mounted on the surface layer 1-1 of the multilayer substrate 1, and a thick film coil pattern 2 is provided on the layers 1-2 to 1-4 below the capacitor C. The coil L was built in the multilayer substrate 1.

(2) A method of making the high-frequency filter non-adjustable, wherein when the capacitor C and the coil L forming the high-frequency filter are mounted on the multilayer substrate 1, the capacitor C is used as a discrete component and has a constant capacitance value. By fixing and designing the coil pattern 2 so that the desired filter characteristic value can be obtained for the capacitor C and patterning the coil L, the desired filter characteristic can be obtained without adjustment. I was allowed to.

[0026]

The operation of the present invention based on the above construction will be described with reference to FIG. The capacitor C, which is a discrete component, is supplied with components of various capacities so that the capacitance can be arbitrarily selected. Further, the coil L is the multilayer substrate 1
Even if the coil pattern 2 is formed of a thick film that is patterned as described above, the inductance is determined by the number of turns and the size (shape) of the pattern, so that the coil pattern can be formed with high accuracy.

Therefore, the capacitor C is fixed as a discrete component to a fixed capacitance value, and the capacitor C is fixed.
By designing the coil pattern so that a characteristic value can be obtained, a high-frequency filter having desired characteristics can be manufactured without adjustment during mass production.

Further, in order to make SMD, GND is formed in the lowermost layer.
Even if a pattern is formed, the capacitor is not affected by the GND pattern.

[0029]

Embodiments of the present invention will be described below with reference to the drawings. (Explanation of First Embodiment) FIG. 2 is a view showing a first embodiment of the present invention, in which C _{1 to} C ₈ are capacitors and L ₁ to
L ₃ is a coil, 2 is a coil pattern, and 1-1 to 1-4 are first to fourth layers of the multilayer substrate.

The first embodiment is an example of a high frequency filter having the same circuit configuration as the circuit shown in FIG. 5A. As shown in FIG. 2, when mounting the capacitors C _{1 to} C ₈ and the coils L _{1 to} L ₃ of the high frequency filter on the multilayer substrate, the capacitors C ₁ to C ₈
C ₈ is implemented as discrete components, coils L ₁ ~
L ₃ is built in the multilayer substrate as a thick film pattern (printed pattern).

As shown, the first layers 1-1 to 1-1 of the multilayer substrate
Capacitor C _{1 of the} high frequency filter using the fourth layer 1-4
~ C ₈ and coils L _{1 to} L ₃ are mounted, but in this example, the first layer 1-1 is the uppermost layer (surface layer).

Then, the capacitors C _{1 to} C ₈ are mounted as discrete components on the uppermost first layer 1-1, and the second layer 1-2, the third layer 1-3, and the lower layers below the capacitors C _{1 to} C ₈ are mounted. Fourth
The coil pattern 2 is formed as a thick film pattern on the layers 1-4.

The coil patterns 2 of the second layer 1-2 to the fourth layer 1-4 are connected by blind through holes (through holes filled with conductors) in the respective layers.
The coils L ₁ , L ₂ and L ₃ are formed.

Further, the capacitors C ₁ to C ₁ on the first layer 1-1.
And C _8, and the coil L ₁ ~L ₃ formed on the second layer 1-2 to the fourth layer 1-4, are connected by the blind through holes, and the circuit arrangement of Figure 5A.

As described above, the capacitors C _{1 to} C ₈ and the coils L _{1 to} L ₃ constituting the high frequency filter are mounted on the multilayer substrate. In this case, the capacitors C _{1 to} C ₈ which are discrete parts are The coil pattern 2 is fixed and fixed to a constant capacitance value, and the coil pattern 2 is designed and patterned so that a characteristic value as shown in FIG. 5B can be obtained.

At present, the accuracy of a capacitor as a discrete component has a deviation of ± 0.5 PF and 5P at 10 PF or more.
Deviation of ± 0.25 PF below F and ± 10 PF or below
Supply at 5% is possible. Moreover, such a capacitor is inexpensive and easily available.

Therefore, by forming the capacitor with discrete parts, a capacitor having a desired capacitance value can be selected and fixed. Further, since the inductance value of the coil is determined by the number of turns and the size (shape) of the pattern (this point has been described in the conventional example), the coil can be formed with high accuracy.

With the above configuration, the capacitor C ₁
-C ₈ are discrete components, and because it selects a part of the desired capacitance value, adjustment after mounting is not required.
Further, the coils L _{1 to} L ₃ are built in the multilayer substrate as a thick film pattern, but since the inductance value can be set with extremely high accuracy, adjustment after patterning is unnecessary.

Therefore, even when the high frequency filter is mass-produced, desired filter characteristics can be obtained without adjustment. Further, since there is a capacitor as a discrete component on the upper side of the coil, this capacitor can prevent the coupling between the coils.

Therefore, good characteristics can be obtained even if the coil interval is narrowed. (Explanation of Second Embodiment) FIGS. 3 and 4 are views showing a second embodiment, FIG. 3 is an exploded perspective view of a high frequency filter, and FIG. 4 is an exploded perspective view of an SMD-type high frequency filter.

In the figure, the same reference numerals as those in FIGS. 1 and 2 indicate the same elements. Further, 1-5 indicates a fifth layer of the multilayer substrate, and 7 indicates a GND pattern. The second embodiment uses an SMD as a high frequency filter.
This is an example of (surface mount component). As shown in FIG. 3, capacitors C _{1 to} C ₈ are mounted as discrete components on the first layer (surface layer) 1-1 of the multilayer substrate, and the second
The coil pattern 2 is formed of a thick film pattern on each of the layers 1-2 to the fourth layer 1-4.

Then, the coil pattern 2 of each layer or the coil pattern 2 and the capacitor are connected by a blind through hole to form a circuit configuration as shown in FIG. 5A. In this case, the configuration of the first layer 1-1 to the fourth layer is the first
Same as the embodiment.

In this example, the fifth layer 1-5 of the multilayer substrate is further added.
The GND pattern 7 is formed as a solid pattern on the top.
When this GND pattern is added, the constant of the coil changes (the inductance value decreases) as compared with that of the first embodiment.

However, such a change in the coil constant is
If the size (shape) of the coil pattern is changed at the time of design so that the filter characteristics can be obtained, an appropriate value can be created without adjustment during mass production.

On the other hand, the capacitors C _{1 to} C ₈ are composed of discrete parts, and can be sufficiently separated from the GND pattern 7, so that the GND pattern 7
Is almost unaffected by.

After laminating the first layer 1-1 to the fifth layer 1-5, a side surface electrode is formed on the side surface of the multi-layer substrate 1 so that the capacitors C _{1 to} C ₈ and the coils L _{1 to} L ₃ are predetermined. By connecting to the portion of (1), a high frequency filter in SMD form as shown in FIG. 4 can be obtained.

In FIG. 4, an electrode 5 for an input terminal (IN), a GND electrode 4, and an electrode 6 for an output terminal (OUT) are provided as the side surface electrodes on the side surface. Such SMD
The converted high-frequency filter (module) can obtain the filter characteristics as shown in FIG. 5B without adjustment even during mass production.

(Other Embodiments) The embodiments have been described above, but the present invention can be implemented as follows. (1) Not limited to the circuit configuration shown in FIG. 5A, any high-frequency filter using a capacitor and a coil can be applied to a filter having any circuit configuration.

(2) Not limited to the SMD type high frequency filter, it may be an insert part.

[0050]

As described above, the present invention has the following effects. (1) Even when the high frequency filter is mass-produced, the coil and the capacitor are kept constant with desired constants, so that the characteristics can be adjusted.

Therefore, the conventional process for producing the characteristic is not required, and the manufacturing cost is reduced. (2) Since the same circuit pattern is formed at the same time by screen printing (multiple cutting), the capacitor electrodes are not patterned unlike the conventional method, so the size of one module is reduced and The number of pieces that can be formed can be increased, and the manufacturing cost can be reduced.

(3) Even if the GND pattern is provided on the lowermost layer of the multilayer substrate, the capacitor is hardly affected by the GND pattern, so that the SMD high frequency filter can be manufactured without adjustment.

(4) Since the coupling between the coils can be prevented by the discrete capacitor mounted on the surface, the characteristics are not affected even if the coil interval is narrowed. Therefore, the module can be downsized.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is an exploded perspective view of the high frequency filter according to the first embodiment of the present invention.

FIG. 3 is an exploded perspective view of a high frequency filter according to a second embodiment.

FIG. 4 is an exploded perspective view of an SMD-type high frequency filter.

FIG. 5 is an explanatory diagram of a conventional example, FIG. A is a circuit example of a high frequency filter, and FIG. 5 is a characteristic example of a high frequency filter.

6A and 6B are explanatory views of a conventional example, FIG. A is an exploded perspective view of a high frequency filter, and FIG. B is a perspective view of a high frequency filter (SMD).

[Explanation of symbols]

1-1 to 1-5 First layer to fifth layer of multi-layer substrate 2 Coil pattern C _{1 to} C ₈ , C capacitor L _{1 to} L ₃ , L coil 7 GND pattern

Claims (2)

[Claims] 1. A high frequency filter in which a capacitor (C) and a coil (L) forming an LC resonance circuit are mounted on a multilayer substrate (1), wherein a surface layer (1-1) of the multilayer substrate (1) is provided. Mounts a capacitor (C) composed of discrete components, and a thick film coil pattern (2) is provided on the lower layer (1-2 to 1-4) of the coil (L). A high-frequency filter characterized by being built in a multilayer substrate. 2. When mounting a capacitor (C) and a coil (L) constituting a high frequency filter on a multilayer substrate (1), the capacitor (C) is fixed as a discrete component to a fixed capacitance value, By designing the coil pattern (2) so as to obtain a desired filter characteristic value for (C) and patterning the coil (L), the desired filter characteristic value can be adjusted without adjustment. A method for adjusting a high-frequency filter, which is characterized in that