JPH11330884A - Band-pass filter and manufacture of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a band-pass filter in a compact and light thin film structure for surface mounting, whose occupancy area is small with superior characteristics using a thin film inductor. SOLUTION: In this discrete thin film band-pass filter, solder balls 4 are used for the junction of one side part of electrodes, on which the magnetic cores of the both end parts of thin inductors in a thin-film inductor array 1 in which 6 thin inductors having magnetic cores are gathered, are exposed with one side part (left sides in the figures in both cases) of electrode patterns connected with thin film capacitors in a thin-capacitor array 2, in which 12 thin film capacitors are gathered. Moreover, a gold bump 5 is used for the junction of the remaining one side part of the electrodes with the remaining one side part (right sides in the figures in both cases) of the electrode patterns. Then, ultrasonic thermo compression bonding is performed so that the thin-film inductor array 1 and the thin-film capacitor array 2 can be pressurized and jointed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mainly used as a filter for input / output signals of portable telephones and the like, and a band-pass filter (BP) as an LC magnetic device having a thin film structure including a thin film inductor and a thin film capacitor.
F) and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, this type of bandpass filter has
The mainstream is a SAW (surface acoustic wave) type having a relatively high Q value of several hundreds and a dielectric type having a Q value of several tens to several hundreds. These two filters are effective in an applied frequency band of several hundred MHz to several GHz, and obtain a transmission frequency band having a narrow frequency band and a sharp rise to show a high Q value. On the other hand, the low frequency band is a weak area, and it is difficult to obtain a wide transmission frequency bandwidth.

[0003] The shape of these filters depends on the frequency band to be used, but for a SAW type filter, for example, the dimensions are 3.8 mm long x 3.8 mm wide x 2 mm thick.
While it is possible to make a small and thin surface mount component (SMD) package of about 3 mm, the dielectric type is manufactured by sintering, and its thickness is 3 to 4 mm due to its essential characteristics. A degree is needed.

When manufacturing these filters, SAW
In the case of the type, an aluminum comb electrode is arranged by the same technology as when a semiconductor element is formed on a dielectric ceramic, and a metal or ceramic made of metal or ceramic is used so that the protection of the surface state and the propagation of surface vibration waves are not hindered. Although it is necessary to cover with a cover, in the case of a dielectric type, a ceramic resonator and L, C chip elements are arranged on a substrate.

[0005] Incidentally, in the case of a dielectric type band-pass filter, an LC lumped constant type is designed due to the configuration of the electric circuit, and the inductor used here is several m.
The main types are a bulk type in which a ferrite of m is wound, a chip element type in which a coil is embedded in a ferrite, and an air-core coil that does not use a magnetic material. These inductors have L in the high frequency band of several tens MHz to several hundred MHz.
When the value is large, the Q value is small because the resonance frequency is low. Conversely, when the L value is small, the resonance frequency is high, but because the L value is small, the Q value is small. In addition, a chip capacitor element, which is a surface mount component, is mainly used for a capacitor which is a component for a chip inductor.
0.8mm for 8 type, 0.5m for 1005 type
m. These chip capacitor elements have an efficiency of several
00, which is a standard, with the capacitance characteristics being determined by 100% screening.

On the other hand, when a thin film LC filter is manufactured, a copper coil is formed on a substrate made of glass, ceramics, Si or the like by a sputtering method or a plating method, and then a sputtering method using a metal target and an insulator target is performed. A semiconductor element is formed by forming a magnetic thin film, forming a resist pattern with a thickness of several μm by exposure using a photomask, forming a magnetic layer or conductor, and then processing using a lift-off method. The same process is applied as in the case where

Incidentally, a thin-film inductor made of a thin-film soft magnetic material has a low Q value, and is not applied to a thin-film bandpass filter.

[0008]

In the case of the above-mentioned dielectric type bandpass filter, the driving frequency is several tens of MHz.
In the ~ 100 MHz band, effective Q value cannot be obtained, the characteristics such as insertion loss and bandwidth are inferior to SAW filters, and the size of inductor is large despite the miniaturization due to higher frequency. Because the thickness of itself does not become thin,
Not only is there a problem that there is a limit to miniaturization of the device shape, but if the number of L and C chip elements increases, the area also increases, the price cannot be expected to be low, and there is no competitiveness with other elements. Due to various problems such as the above, the chances of adopting L and C lumped constant types in recent surface mount components tend to decrease. In the case of 1608 type and 1005 type chip capacitor elements, although the components themselves are small, an electrode portion for mounting the chip components is required, and furthermore, the chips cannot be extremely close to each other from the handling of the chip components, so that the size is reduced. And it is not suitable for area saving.

On the other hand, a thin-film inductor is not used in a bandpass filter. This is because the Q value of a thin-film soft magnetic material is low. The Q value of the soft magnetic material is represented by μ ′ (real part of magnetic permeability) / μ ″ (imaginary part of magnetic permeability), and the Q value of the inductor is ωL / R (where ω = 2πf: R is a resistance), and the Q value as a bandpass filter is proportional to ω, L and μ ′, and R and μ ″
Is inversely proportional to The loss of the soft magnetic material is determined by the precession motion of the magnetic spin, and the spin motion is essentially lost. Therefore, it is indispensable to reduce the resistance R in order to improve the Q value.

However, since the inductance is obtained by inserting a magnetic material into the coil due to the structure of the inductor, the loss of the magnetic material (iron loss) and the copper loss of the coil (DC loss and AC loss) are reduced. We have to reduce both,
The Q value of the prototype obtained so far is around 20 at the maximum.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its technical object a thin, light-weight, surface-mounting thin-film structure having a small occupying area, and using a thin-film inductor. An object of the present invention is to provide a bandpass filter having excellent characteristics and a method for manufacturing the same.

[0012]

According to the present invention, a thin film structure in which a thin film inductor array in which several thin film inductors each having a magnetic core are assembled and a thin film capacitor array in which several thin film capacitors are assembled are joined. Is obtained.

According to the present invention, in the band pass filter, the operating frequency band is 10 MHz to 500 M.
A bandpass filter in the range of Hz is obtained.

On the other hand, according to the present invention, a thin-film inductor array manufacturing process for manufacturing a thin-film inductor array by assembling several thin-film inductors having a magnetic core, and manufacturing a thin-film capacitor array by assembling some thin-film capacitors. A method of manufacturing a bandpass filter including a thin film capacitor array manufacturing step and a pressure bonding step of pressure bonding the thin film inductor array and the thin film capacitor array using any of a solder ball and a gold bump is obtained.

Further, according to the present invention, in the above-described method for manufacturing a bandpass filter, in the pressure bonding step, a method for manufacturing a bandpass filter in which pressure bonding is performed by thermocompression bonding or ultrasonic thermocompression bonding is obtained.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows an equivalent circuit of a discrete thin-film bandpass filter according to one embodiment of the present invention. This equivalent circuit includes six spiral type thin film inductors L1 to L6, 12 overlay type thin film capacitors C1 to C12, and two resistors R1 and R2 having resistance values such as 50Ω and 210Ω. , L-
The C circuit has a six-stage configuration. In this equivalent circuit, the inductor chip element comprises a thin film inductor array 1 as shown in FIG. 2, and the capacitor chip element comprises a thin film capacitor array 2 as shown in FIG.

The thin-film inductor array 1 has a width of 5
The thin film inductors L1 to L6 are formed by winding conductors in a spiral shape so that portions of 400 μm are exposed from both ends of a thin film magnetic core having a length of 00 μm and a length of 3700 μm. They are juxtaposed on the substrate so as to be aligned in the direction. That is, the thin-film inductor array 1 here is manufactured by assembling the thin-film inductors L1 to L6 each having a magnetic core, and this assembly makes it possible to manufacture a large and wide inductor with a small area. , Not only high efficiency and high efficiency are obtained, but also thin film inductors L1 to L6
Is more simplified in terms of mounting time and cutting time than in the case of individually manufacturing the same, which is advantageous in terms of cost.

By the way, when the occupied area used in the case where a bandpass filter is formed by using such a thin-film inductor array 1 and in the case where a bandpass filter is formed using an existing chip inductor element are compared, Dimensions are 500 μm wide and 1600 μm long
When using the thin film inductor array 1 of
When the configuration is such that 10 pieces are arranged side by side, the total area S becomes S =
It is 8.8 mm ² , and ten inductor elements can be put in an area of 1.6 mm × 5.5 mm. On the other hand, when a chip inductor element is used, the element size is 1600 μm × It is 800 μm in width. In addition to increasing the width of the solder land by 100 μm and increasing the length by 200 μm in order to solder by SMT technology, in addition to increasing the length of the solder land, it is necessary to make it easy to handle according to the inclination of the element at the time of mounting. Since it is necessary to leave at least 200 μm between the solder lands, the total area S is S = 23.8 mm
² , which occupies a mounting area of 2 mm × 12 mm. As a result, it has been found that the area that is configured using the chip inductor element is about 2.7 times as large. Therefore, if an array element such as the thin-film inductor array 1 is used, it is effective to reduce the size of the filter.

On the other hand, the thin film capacitor array 2 has 12 conductor electrodes around the center, a ground (GND) location at one corner,
And a signal pattern (Signal) at one end of the opposite side.
Vertical 500 provided with a conductor pattern including -1, -2)
By applying a band-shaped conductor pattern to a conductor portion on a substrate of 0 μm × 5000 μm in width, the thin film capacitors C1 to C12 are collectively formed between the band-shaped conductor patterns, thereby producing the capacitor. The thin-film capacitor array 2 serves as a stand for mounting the thin-film capacitors C1 to C12 and the thin-film inductors L1 to L6, in addition to being a solder-bonded board stage at the time of mounting. In the case of the thin-film capacitor array 2, as in the case of the thin-film inductor array 1, the assembly work simplifies the mounting labor and cutting time, and is therefore advantageous in terms of cost.

Each of the thin film inductor array 1 and the thin film capacitor array 2 is configured as a discrete thin film band pass filter having an operating frequency band in the range of 10 MHz to 500 MHz having a thin film structure and joined to each other. Thickness of 200μm ~ 600μ
Since it is as thin as m, it can be arranged above, below, and around a semiconductor element, a power supply element, and the like.

Therefore, when a discrete thin-film bandpass filter is constructed, a thin-film inductor L1 having a magnetic core is used.
To L6 and the thin film capacitor array 2 in which the thin film capacitors C1 to C12 are assembled to form a thin film structure for surface mounting.
In this connection method, the bonding portion is connected by soldering using a gold bonding wire, which is an existing technology, and is thermocompression-bonded using a solder ball (containing a copper core), which is a new technology, or is under development. It is sufficient to perform ultrasonic thermocompression bonding using gold bumps, which is a technique of the above, to perform pressure bonding.

FIG. 4 is a perspective view showing the external structure of a discrete thin-film bandpass filter manufactured by soldering a thin-film inductor array 1 and a thin-film capacitor array 2 using a gold bonding wire 3 having a wire diameter of 50 μm. is there. This discrete thin-film bandpass filter is composed of an electrode in which the magnetic cores at both ends of the thin-film inductors L1 to L6 in the thin-film inductor array 1 provided for connection are exposed, and a thin-film capacitor C1 in the thin-film capacitor array 2.
1 to 12 are connected by soldering with a total of 12 gold bonding wires 3. The equivalent circuit is the same as that shown in FIG.

FIG. 5 shows a thin-film inductor array 1 and a thin-film capacitor array 2 with cored solder balls 4 and gold bumps 5.
FIG. 4 is a perspective view showing an external configuration of a discrete thin-film bandpass filter manufactured by press-bonding using. The discrete thin-film bandpass filter includes a thin-film inductor array 1 connected to each other, a thin-film inductor L1 to L6 at one end of an electrode in which the magnetic cores are exposed, and a thin-film capacitor C in a thin-film capacitor array 2.
Solder balls 4 are used for bonding to one side of the electrode pattern connected to C1 to C12 (the left side in the drawing).
And the remaining one side of the electrode and the remaining one side of the electrode pattern (all shown on the right side)
The bonding is performed by ultrasonic thermocompression bonding using gold bumps 5 and bonding the thin film inductor array 1 and the thin film capacitor array 2 by compression bonding, and the equivalent circuit is the same as that shown in FIG.

When the solder is melted, the shape of the solder ball 4 is deformed and the space between the thin-film inductor array 1 and the thin-film capacitor array 2 is eliminated. It is preferable to use one with a plated core. Also, gold bump 5
Is obtained by pressing the above-mentioned gold bonding wire 3 to an electrode or an electrode pattern and pulling it out as it is to have a height of 40 μm.
Can be formed by ultrasonic thermocompression bonding with the mating side.

The bonding between the thin-film inductor array 1 and the thin-film capacitor array 2 may be thermocompression bonding using only the solder balls 4 or ultrasonic thermocompression bonding using only the gold bumps 5. The arrangement shown in FIG. 5 when the balls 4 and the gold bumps 5 are combined is an example, and any arrangement is possible. In any case, a compact and small discrete thin-film bandpass filter is formed.

That is, when manufacturing the discrete thin-film bandpass filter shown in FIG. 5, a thin-film inductor array manufacturing process for manufacturing a thin-film inductor array 1 by assembling thin-film inductors L1 to L6 each having a magnetic core, A thin-film capacitor array manufacturing process of manufacturing the thin-film capacitor array 2 by assembling the thin-film capacitors C1 to C12; and a crimp-bonding process of crimp-bonding the thin-film inductor array 1 and the thin-film capacitor array 2 using the solder balls 4 and the gold bumps 5. In the pressure bonding step, pressure bonding is performed using an ultrasonic thermocompression bonding method.

FIG. 6 shows attenuation (dB) with respect to frequency (MHz) in a discrete thin film band-pass filter manufactured by press-bonding a thin film inductor array 1 and a thin film capacitor array 2 using a solder ball 4 having a copper core.
The results of measuring the characteristics (filter characteristics) are shown in comparison with those of the simulation results. From FIG. 6, the thin-film inductors L1 to L having a Q value of 18 indicated by solid lines are shown.
It can be seen that the measurement result of the attenuation characteristic of the thin film bandpass filter using the thin film inductor array 1 having the value 6 has a good agreement with the simulation result of the Q value 18 indicated by the dotted line.

FIG. 7 shows the attenuation (dB) characteristic with respect to frequency (MHz) in the filter including the thin film inductor array 1 having the thin film inductors L1 to L6 having different Q values 30 in the discrete thin film band pass filter of FIG. (Filter characteristics) are shown in comparison with those of FIG. 6 and those of the existing SAW type. From FIG. 7, the insertion loss when using the thin film inductors L1 to L6 having a Q value of 30 shown by the dotted line is smaller than that when using the Q value of 18 shown by the solid line, and is indicated by the broken line. It can be seen that the same characteristics can be obtained as compared with the SAW type shown, and that the frequency band is further extended.

Incidentally, the Q value of the thin film inductors L1 to L6 was about 20 in the past, but can be increased to about 30 recently. The condition for setting the Q value to 30 at about 100 MHz can be realized by reducing the loss of the magnetic material by 8/9 and reducing the DC and AC copper loss caused by the coil by 3/4. In order to reduce these, in the case of a magnetic material, it is only necessary to perform a composite multilayer in which the insulating layer of the multilayer film is partially thickened.In the case of a copper coil conductor, the DC resistance can be reduced by increasing the thickness of the conductor, and Dividing the conductor thickness into multiple layers by the insulating layer can reduce AC eddy current loss. As a result, loss at 100 MHz can be reduced, and a Q value of 30 or more can be obtained.

The number of the thin film inductors L1 to L6 of the thin film inductor array 1 and the thin film capacitors C1 to C12 of the thin film capacitor array 2 in the discrete thin film bandpass filter according to the above-described embodiment, and the resistances R1 and R2 in the equivalent circuit. The number is not limited to this, and can be changed depending on the application and design.

[0032]

As described above, according to the present invention, a thin-film inductor array composed of an aggregate of thin-film inductors and a thin-film capacitor array composed of an aggregate of thin-film capacitors are separately manufactured. Are bonded to form a bandpass filter having a thin film structure, so that each array element can be manufactured with high yield,
Since only these array elements need only be formed by pressure bonding, the number of mounting steps is reduced, and a small-sized, light-weight, band-pass filter having a small surface-mounting thin film structure for surface mounting can be easily manufactured. In addition, if a thin film inductor having a Q value exceeding 30 is used, the filter characteristics can be assured with the same insertion loss as that of the existing SAW type, and the frequency band is extended to obtain excellent characteristics. Taking advantage of the advantages of cost and shape compared to the device, it is possible to arrange the device above and below or around the semiconductor element and power supply element, thereby contributing to thinning and miniaturization of the device. Become like Furthermore, since the thin-film inductor array and the thin-film capacitor array are joined by thermocompression bonding or ultrasonic thermocompression bonding using either solder balls or gold bumps, the height of the filter can be reduced. become.

[Brief description of the drawings]

FIG. 1 shows an equivalent circuit of a discrete thin-film bandpass filter according to one embodiment of the present invention.

FIG. 2 is a plan view showing a detailed configuration of a thin film inductor array used in the discrete thin film band pass filter shown in FIG.

FIG. 3 is a plan view showing a detailed configuration of a thin film capacitor array used in the discrete thin film band pass filter shown in FIG.

4 is a perspective view showing an external configuration of a discrete thin-film bandpass filter manufactured by soldering the thin-film inductor array shown in FIG. 2 and the thin-film capacitor array shown in FIG. 3 using a gold wire bonding wire.

FIG. 5 is a perspective view showing an external configuration of a discrete thin film bandpass filter produced by pressure bonding the thin film inductor array shown in FIG. 2 and the thin film capacitor array shown in FIG. 3 using a cored solder ball and gold bumps. FIG.

FIG. 6 is a diagram illustrating attenuating characteristics (filter characteristics) of a discrete thin-film bandpass filter manufactured by crimping the thin-film inductor array shown in FIG. 2 and the thin-film capacitor array shown in FIG. 3 using a solder ball having a copper core; ) Is shown in comparison with the result of the simulation.

FIG. 7 is a graph showing a result of measuring an attenuation characteristic (filter characteristic) with respect to frequency in a filter having a configuration including a thin film inductor array having thin film inductors having further different Q values in the discrete thin film band pass filter of FIG. 6;
And in comparison with the existing SAW type.

[Explanation of symbols]

 Reference Signs List 1 thin-film inductor array 2 thin-film capacitor array 3 gold bonding wire 4 cored solder ball 5 gold bump C1-C12 thin-film capacitor L1-L6 thin-film inductor R1, R2 resistance

Claims (4)

[Claims] 1. A band-pass filter having a thin-film structure in which a thin-film inductor array in which several thin-film inductors having a magnetic core are assembled and a thin-film capacitor array in which several thin-film capacitors are assembled are joined. 2. The band-pass filter according to claim 1, wherein an operating frequency band is in a range of 10 MHz to 500 MHz. 3. A thin-film inductor array manufacturing process for manufacturing a thin-film inductor array by assembling several thin-film inductors having a magnetic core, and a thin-film capacitor array manufacturing process for manufacturing a thin-film capacitor array by assembling several thin-film capacitors. And a pressure bonding step of pressure bonding the thin film inductor array and the thin film capacitor array using any of solder balls and gold bumps. 4. The method for manufacturing a bandpass filter according to claim 3, wherein in the pressure bonding step, the pressure bonding is performed by thermocompression bonding or ultrasonic thermocompression bonding.