JP2005123390A - Chip type noise filter, its manufacturing method, and semiconductor package using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a chip type noise filter wherein noises of a strip of millimeter waves and submillimeter waves can be absorbed, the reliability is excellent with no out-gas, and a mass-production is excellent. <P>SOLUTION: The chip type noise filter has a signal line composed of a conductor and a magnetic body arranged so as to be adhered to the signal line. The magnetic body has Fe<SB>2</SB>O<SB>3</SB>as a main component and is constituted of a sintered body containing NiO in its remainder. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a chip-type noise filter for removing high-frequency noise that enters a signal line of an electronic device, and a method for manufacturing the same.

  In recent years, in response to market demands for high-speed and large-capacity information communication by optical communication and wireless communication, the operating frequency and signal frequency of electronic devices used for such communication are steadily increasing year by year.

  In particular, the frequency of electrical signals of electronic devices used for high-speed optical communication and wireless communication has been increased to a frequency band of 10 GHz or more called quasi-millimeter wave or millimeter wave, and this is a common problem in devices that handle these frequencies. As a point, the problem of noise has become obvious.

  When the frequency of the electric signal reaches the quasi-millimeter wave and millimeter wave regions, the electric signal flowing through the signal line is handled as an electromagnetic wave, and it can be considered that the electric signal is transmitted by propagating the electromagnetic wave along the signal line.

  Such an electric signal as an electromagnetic wave is likely to be radiated into space, for example, at a discontinuous surface or a bent portion of the signal line, and may generate so-called radiation noise.

  Such radiated noise is reflected multiple times inside the casing of the electronic device, enters into other signal lines as noise, and causes a noise problem called crosstalk.

  As a component for removing so-called conduction noise that has entered such a signal line, a small chip-type noise filter that is soldered onto a substrate is used.

  This type of filter forms an equivalent circuit composed of L1, L2, and C as shown in FIG. 4, and functions as a so-called low-pass filter that cuts high frequencies and passes low frequencies.

  A conventional chip type noise filter uses ceramics as a dielectric, and as a manufacturing method thereof, a ceramic green sheet having a predetermined thickness is formed, and then a circuit member and an electrode member are formed thereon by a method such as screen printing. It is obtained by arranging and assembling a plurality of green sheets as necessary, and then integrating them by firing (Patent Document 1).

In addition, noise filters that can be used in the high-frequency region, including quasi-millimeter waves and millimeter-wave bands, are in close contact with the surface of a composite material in which soft magnetic material powder is dispersed and mixed in a matrix such as rubber or plastic. A chip type noise filter (Patent Document 2) having a signal line made of a conductor is disclosed.
JP 2000-21640 A JP 2002-171104 A

  However, the frequency of noise that can be removed by a filter as disclosed in Patent Document 1 is about 3 GHz at the maximum, and quasi-millimeter wave and millimeter wave noise could not be removed. Also in the manufacturing method, the processing cost is high, and there is a problem in terms of cost reduction of parts.

  The filter disclosed in Patent Document 2 can remove quasi-millimeter wave and millimeter-wave band noise. However, since rubber, plastic, or the like is used as a matrix, manufacturing of electronic devices is possible. Depending on conditions and use conditions, there is a problem that outgas is generated when the temperature rises, and the surrounding electronic circuits and signal lines are corroded and the characteristics are deteriorated.

  In particular, the use of such a filter in a part that requires high airtightness, such as the inside of a semiconductor package, causes outgassing at the time of temperature rise in the manufacturing process and use environment of the semiconductor package, and deteriorates the characteristics of the semiconductor element. There is a problem that the transmission characteristics are deteriorated by causing the signal lines to corrode and surrounding signal lines.

As a result of repeated investigations on the above problems, the present invention provides a chip-type noise filter having a signal line made of a conductor and a magnetic body disposed so as to be in close contact with the signal line. It consists of a sintered body containing Fe ₂ O ₃ as a main component and NiO in the remainder.

The chip-type noise filter of the present invention is characterized in that the content of Fe ₂ O _{3 in} the magnetic material is 70 to 95 mol%.

Furthermore, the manufacturing method of the chip-type noise filter of the present invention includes a step of manufacturing a magnetic body containing Fe ₂ O ₃ as a main component and NiO in the balance, and forming a signal line made of a conductor on the magnetic body. And a step of dividing the magnetic body into predetermined individual dimensions. The semiconductor package of the present invention is characterized in that the chip noise filter is disposed in an internal space in which a semiconductor element is hermetically sealed. It is characterized by the arrangement.

According to the present invention, in a chip-type noise filter having a signal line made of a conductor and a magnetic body disposed in close contact with the signal line, the magnetic body is mainly composed of Fe ₂ O ₃ , By using a sintered body containing NiO in the balance, it is possible to effectively absorb and attenuate quasi-millimeter and millimeter-wave noise, and at the same time, even when used inside a semiconductor package, depending on the assembly process and conditions of use. Outgassing does not occur when the temperature rises, and it is possible to improve the characteristics of the semiconductor package and at the same time obtain high reliability.

  Hereinafter, a chip type noise filter and a semiconductor package using the chip type noise filter will be described as embodiments of the present invention.

  FIG. 1 is a perspective view showing an example of a chip type noise filter of the present invention.

  FIG. 1A shows a chip-type noise filter 10 in which a signal line 12 is formed on the entire surface so as to be in close contact with the surface of a flat magnetic body 11, and FIG. 1B shows a reduced area. In addition to the signal line 13, terminal electrodes 14 and 15 for connecting to an external circuit are formed at both ends to form a chip-type noise filter 20 (in the case where the same part is shown in the figure) (Indicated by the same symbol).

  Both show the basic shape of a chip-type noise filter in which signal lines 12 and 13 are formed on the surface of the magnetic body 11.

  Since the magnetic body 11 is a magnetic material, it has the effect of absorbing and attenuating high-frequency electrical signals. Since the signal lines 12 and 13 are formed on the magnetic body 11, the signal lines 12 and 13 It is possible to effectively absorb high-frequency noise components flowing in the.

In addition, it is important that the magnetic body 11 is a sintered body containing Fe ₂ O ₃ as a main component and NiO in the balance.

By making the magnetic body 11 into a sintered body containing Fe ₂ O ₃ as a main component and NiO in the balance, the magnetic body 11 has excellent noise absorption characteristics for electromagnetic waves in the quasi-millimeter wave and millimeter wave regions. Therefore, it is excellent in heat resistance, and when joining parts by heat treatment, there is little alteration, deformation and strength deterioration, and generation of degassing can be eliminated.

Further, the magnetic body 11 preferably has a content of Fe ₂ O ₃ of 50 to 95 mol%, more preferably 70 to 95 mol%.

This is because, when the content of Fe ₂ O ₃ is less than 50 mol%, it becomes difficult to obtain sufficient noise absorption characteristics in the quasi-millimeter wave band and the millimeter wave band, and these frequencies that have entered the signal lines 12 and 13 are difficult to obtain. Therefore, when the content of Fe ₂ O ₃ is 50 mol% or more and less than 70 mol%, the noise absorption characteristics in the quasi-millimeter wave band and the millimeter wave band are good. This is because a change in noise absorption characteristics remains due to slight fluctuations in the content of Fe ₂ O ₃ , which makes it difficult to design the chip-type noise filter 20.

On the other hand, if the content of Fe ₂ O ₃ is 95 mol% or less, if it exceeds 95 mol%, it becomes difficult to sinter depending on the pressure during shaping, and good noise absorption characteristics cannot be obtained, This is because the yield decreases.

  In addition, when NiO is not contained at all, the volume resistivity of the magnetic body 11 is increased and good noise absorption characteristics cannot be obtained and sintering is performed at a low temperature. This is because it becomes difficult.

  The average grain size of the magnetic body 11 is preferably in the range of 1.0 to 100 μm, and more preferably in the range of 1.0 to 20 μm. This is because, if the crystal grain size is outside the above range, the strength of the magnetic body 11 is lowered, causing cracks during processing or mounting, and good noise absorption characteristics cannot be obtained.

  Further, the porosity of the magnetic body 11 is preferably 0.5% or less. This is because if the porosity exceeds 0.5%, the surface smoothness of the transmission lines 12 and 13 is impaired, and solder wettability and wire bonding properties during mounting are deteriorated. In addition, it is difficult to clean the grinding fluid or wax used in the manufacturing process of the chip-type noise filter 20.

  The signal lines 12 and 13 are made of metal such as Au, Ag, Pt, Ti, Al, Sn, Zn, Pd, Cu, Ni, and Fe in consideration of electrical resistance and adhesion with a magnetic material. It is preferable to use an alloy containing these, and the structure may be one layer or two or more layers.

  Next, the magnetic body 11 of the present invention is manufactured by the following method.

_First, the raw material powder of Fe ₂ O 3 50mol% or more of the raw material powder and NiO, after turning formulated into a ball mill or bead building with water, by performing 6-10 hours wet mixed to obtain a slurry having a predetermined viscosity .

Here, when Fe ₂ O ₃ raw material powder or NiO raw material powder is charged and prepared in a ball mill or bead building, known curing agents, curing aids, plasticizers, dispersants, mold release agents, coloring agents within the scope of the present invention. There is no problem even if a small amount of an agent or a bulking agent (inorganic material) is added.

In order to ensure sinterability, it is preferable to use Fe ₂ O ₃ raw material powder or NiO raw material powder having an average particle size of 1 μm or less, preferably 0.85 μm or less.

Furthermore, from the viewpoint of enabling molding at a lower pressure, it is preferable to add at least one raw material powder of ZnO, CuO, Bi ₂ O ₃ , and the total addition amount is 5 to 10 mol%. This is particularly suitable, and by doing so, it is possible to reduce the cost of the apparatus used for molding, and it is also possible to manufacture the magnetic body 11 having a complicated shape.

  Next, after drying and granulating the slurry using a spray dryer, the obtained granulated powder is obtained into a desired shape by, for example, a powder pressure molding method.

  Alternatively, the dried slurry is subjected to calcining synthesis at about 700 to 900 ° C., pulverized with a ball mill or bead mill, and dried again with a spray dryer, and then desired molding means, for example, powder pressure molding You may produce the molded object of arbitrary shapes by the method.

  Here, when using the powder pressure molding method, the molding pressure may be, for example, 100 to 300 MPa.

  And after baking the said molded object at 1000-1400 degreeC and holding time 0-2 hours, the magnetic body 11 of this invention is obtained by temperature-falling at 300-500 degreeC / hour.

  On the surface of the magnetic body 11 thus obtained, for example, a signal line 12 is formed by forming a film of Ni as a base layer and Au as a surface protective layer by a vacuum deposition method, and then a dicing machine is formed to a predetermined chip size. By using and cutting, the chip-type noise filter 10 of the present invention can be obtained.

  Further, in the case of the chip type noise filter 20, the signal line 13 is formed instead of the signal line 12 of the chip type noise filter 10, and then cut into a predetermined chip size. The terminal electrodes 14 and 15 made of, for example, may be formed by dipping in an electrode paste and then baked at a predetermined temperature. If necessary, Ni, Au, etc. may be formed by a method such as electrolytic plating. The plating may be applied.

  In addition, although the terminal electrodes 14 and 15 were shown in the shape formed in the whole surface of the both ends of the magnetic body 11 in FIG.1 (b), it is not necessary to stick to this shape, and a part of both ends, or the magnetic body 11 is not necessarily required. It may be formed only on the surface.

  Further, when cutting into the above chip size, V-grooves for dividing the magnetic material 11 are formed in advance, and the signal lines 12 and 13 are formed by a thin film method or a thick film printing method. , And may be divided into individual pieces along the V-groove.

  Next, FIG. 2 is a perspective view showing an example of another embodiment of the chip type noise filter of the present invention.

  2A shows a chip-type noise filter 30 in which a signal line 17 is formed by penetrating the inside of a prismatic magnetic body 16, and FIG. 2B shows a plate-shaped conductor as a signal line 19 in the vertical direction. It is the chip type noise filter 40 produced by sticking the magnetic body 18 (18a, 18b) so that it may be pinched | interposed from.

  Since these chip type noise filters 30 and 40 are formed with magnetic bodies 16 and 18 so as to surround the signal lines 17 and 19, respectively, the noise flowing through the signal lines 17 and 19 is shown in FIG. As compared with the chip-type noise filters 10 and 20 of (b), the magnetic bodies 16 and 18 can absorb more effectively.

In the magnetic bodies 16 and 18 as well, it is important to make the sintered body containing Fe ₂ O ₃ as a main component and NiO in the remainder, like the magnetic body 11.

Furthermore, in order to manufacture the magnetic body 16, a prismatic shaped body having a through hole in the central portion is obtained by a general powder pressure molding method of ceramic in the same manner as in the case of the magnetic body 11. After
After baking at 1000 to 1400 ° C. and holding time of 0 to 2 hours, the temperature may be lowered at 300 to 500 ° C./hour, and then a conductor to be the signal line 17 is inserted and bonded or pasty After the conductor is filled, the signal line 17 is formed by heat treatment, and the chip noise filter 30 may be formed.

  Further, in the case of the chip type noise filter 40 or the like, the thin plate conductor may be used as the signal electrode 19 in advance, and the magnetic members 18a and 18b may be closely attached so as to be sandwiched from above and below to form the chip type noise filter 40. Further, a paste-like conductor to be the signal electrode 19 is formed on at least one of the magnetic bodies 18a and 18b by printing or the like, and the magnetic bodies 18a and 18b are arranged so that the signal electrode 19 is on the inside. May be joined by heat treatment.

  Next, a semiconductor package using the chip type noise filter of the present invention will be described by taking the chip type noise filter 10 as an example.

  FIG. 3 is a cross-sectional view showing the semiconductor package of the present invention. (In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals.) The semiconductor element 51 is made of, for example, a Ga—As compound, and a method such as a eutectic mounting method on an island pattern provided on the ceramic substrate 53. It is fixed by.

  The input / output of the high frequency signal is connected to the semiconductor element 51 through the external wiring lead 54, the electrode 56 formed on the package substrate 61, and the bonding wire 61.

  The external wiring lead 55 for bias voltage input is connected to the chip-type noise filter 10 via the electrode 57 and the bonding wire 59, and further connected to the semiconductor element 51 via the bonding wire 60.

  The internal space 62 of the semiconductor package 50 is hermetically sealed with a lid (not shown) made of a metal plate, thereby protecting the semiconductor element 51 having poor moisture resistance and gas resistance.

  Here, by arranging the chip-type noise filter 10 of the present invention in a semiconductor package, high-frequency noise radiated from the electrode 56 for high-frequency signal input / output, the bonding wire 61, the semiconductor element 51, and their connecting portions is reduced. As a result of multiple reflections on the side wall portion of the package case 52 and the internal space surface of the lid (not shown), high frequency noise entering the wiring portion for bias voltage is absorbed, and the operation of the semiconductor element 51 can be stabilized. It becomes possible.

Further, the chip-type noise filter 10 is a sintered body containing a magnetic material containing Fe ₂ O ₃ as a main component and NiO in the remainder, and thus outgas is generated when the temperature rises in a package manufacturing process or a use environment. Therefore, outgas generation can be significantly reduced as compared with a chip-type noise filter using a conventional resin or rubber, and the reliability of the semiconductor element 51 can be improved.

  An embodiment of the present invention will be described based on the case where the chip type noise filter 10 of FIG.

  First, the magnetic body 11 was produced by the following method.

First, what was weighed so that the raw material powders of Fe ₂ O ₃ and NiO were in the ratio shown in Table 1 was used as the starting material. This starting material was put into a ball mill together with water and prepared, and then wet mixing was performed for 8 hours to obtain a slurry having a predetermined viscosity.

  Next, after drying and granulating the slurry using a spray dryer (spray dryer), the resulting granulated powder was molded at a molding pressure of 100 MPa by a powder pressure molding method to obtain a molded body. .

  And the magnetic body 11 was obtained by baking the said molded object in the atmosphere of 1300 degreeC in the air.

  Further, after forming the signal line 12 of the base Ni and the surface layer Au on one main surface of the obtained magnetic body 11 by a thin film method, it is cut into a predetermined individual shape using a dicing machine, and chip-type noise is obtained. A filter 10 was obtained.

First, in order to verify the optimum range of the content of Fe ₂ O ₃ and NiO in the magnetic body 11, a chip-type noise filter is manufactured using the magnetic body 11 in which each content is changed, and a high-frequency electric signal The amount of absorption was verified.

  The amount of absorption is measured by connecting the port 1 and port 2 of the network analyzer to both ends of the signal line 12 of the chip-type noise filter 10 via a coaxial cable and a contact probe, and measuring the power transmission coefficient S21 at 100 MHz to 40 GHz. Absorption amount.

  Here, the absorption amount at 100 MHz is 0.01 dB or less, and the absorption amount at 10 GHz or more is 0.5 dB or more. The absorption amount at 100 MHz is 0.01 dB or less, and at 10 GHz or more. An object having an absorption amount of 2.0 dB or more was evaluated as “◎”, and an object having an absorption amount at 100 MHz of 0.01 dB or less and an absorption amount at 10 GHz or more of less than 0.5 dB was determined as “bad”.

  Further, as shown in FIG. 3, the chip-type noise filter 10 of the present invention and the semiconductor element 51 are fixed on a ceramic substrate 53 by an Au—Sn alloy brazing and a eutectic mounting method, respectively, and a bonding wire 58 59, 60 to external wiring leads 54, 55, and a lid (not shown) made of a metal plate is joined by a seam welding method to hermetically seal the internal space 62 of the package 52, A semiconductor package 50 was obtained.

  Then, the obtained semiconductor package 50 was put into a reliability test at 150 ° C. for 2000 hours, and the presence or absence of organic gas generation in the internal space of the semiconductor package 50 was measured by a gas chromatograph.

  Based on the above results, the overall evaluation as a semiconductor package 50 was evaluated as “poor”, the good one as “good”, and the particularly excellent one as “good”.

In addition, sample No. in a table | surface. * Indicates outside the scope of the present invention, and the comparative example is based on the conventional method and does not use a sintered body containing the Fe ₂ O ₃ of the present invention as the main component and NiO in the remainder. Shows the case of using rubber + permalloy.

The results are shown in Table 1.

  As a result, in the case of using the chip type noise filter within the scope of the present invention (No. 2 to No. 9), the attenuation at 100 MHz is extremely small as 0.01 dB or less, and at the same time, a so-called quasi-millimeter wave of 10 GHz or more. The attenuation amount for noise in the millimeter wave band is 0.5 dB or more, and can be suitably used as the chip-type noise filter of the present invention. Even in a semiconductor package using the same, it is in process compared to the comparative example. In addition, it can be seen that there is no outgassing under the usage environment and that the noise absorbing characteristics are excellent.

  On the other hand, the samples (No. 1, No. 10) outside the scope of the present invention are inferior in noise absorption characteristics and have an attenuation of 0.5 dB or less with respect to 10 GHz or more quasi-millimeter wave and millimeter wave band noise. It is small and cannot be used as the chip type noise filter 10 of the present invention.

Furthermore, by making the content of Fe ₂ O ₃ in the range of 70 to 95%, it becomes possible to manufacture in a region where the attenuation amount of noise is stable with respect to the change in the content of Fe ₂ O ₃ , It can be seen that the manufacturing conditions can be easily managed and stable characteristics can be obtained as a magnetic material, so that the yield is improved and the design of the chip-type noise filter is facilitated, which is advantageous.

  In addition, the chip type noise filter obtained in this way can be used inside a semiconductor package in which a semiconductor element or the like is mounted in a hermetically sealed space and can be used for absorbing and suppressing high frequency noise. Since no outgas is generated, deterioration of the semiconductor element can be prevented and the reliability of the semiconductor package can be improved.

  The present invention can be used particularly for electronic circuits and optical element packages and high-frequency circuit packages used for high-speed information communication and high-frequency measurement, and as a result, the characteristics and reliability of various electronic circuits and packages can be improved. It will be.

(A), (b) is a perspective view which shows the chip-type noise filter of this invention. (A), (b) is a perspective view which shows other embodiment of the chip-type noise filter of this invention. It is a cross-sectional view showing a semiconductor package of the present invention. It is an equivalent circuit diagram of a conventional chip type noise filter.

Explanation of symbols

10, 20, 30, 40... Chip type noise filter 11, 16, 18, 18a, 18b... Magnetic body 12, 17, 19. Lines 13, 14, 15 ... Terminal electrode 50 ... Semiconductor package 51 ... Semiconductor element 52 ... Package case 53 ... Ceramic Substrate 54, 55 .. External wiring lead 56, 57 .. Electrode 58, 59, 60 ... Bonding wire 61 ... Package substrate

Claims (4)

In a chip-type noise filter having a signal line made of a conductor and a magnetic body disposed so as to be in close contact with the signal line, the magnetic body contains Fe ₂ O ₃ as a main component and NiO in the remainder A chip-type noise filter comprising a sintered body. _2. The chip-type noise filter according to claim 1, wherein the magnetic substance has a content of Fe ₂ O ₃ of 70 to 95 mol%. A step of producing a magnetic body containing Fe ₂ O ₃ as a main component and NiO in the remainder, a step of forming a signal line made of a conductor on the magnetic body, and dividing the magnetic body into predetermined individual dimensions The method for manufacturing a chip-type noise filter according to claim 1, further comprising a step of: 3. A semiconductor package, wherein the chip noise filter according to claim 1 is disposed in an internal space in which a semiconductor element is hermetically sealed.

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