JP2004023770A - Irreversible circuit element and communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an irreversible circuit element and a communication apparatus capable of efficient heat radiation outside produced in a terminating resistor. <P>SOLUTION: An isolator 1 is broadly provided with a metallic case including a metallic upper-side case 4 and a metallic lower-side case 8, a permanent magnet 9, a center electrode assembly 13 including a ferrite 20 and center electrodes 21 to 23, and a laminate substrate 30. The laminate substrate 30 has radiation via holes 19 disposed below terminating resistors R through a dielectric layer (dielectric sheet 42). Preferably, the radiation via holes 19 are formed on as many dielectric sheets as possible, and the end portions of the radiation via holes 19 reach a surface of the laminate substrate 30. Further, a conductive paste filled in the radiation via holes 19 is preferably formed of material having high thermal conductivity such as Ag, Cu and Ag-Pd. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a non-reciprocal circuit device, particularly a non-reciprocal circuit device such as an isolator used in a microwave band, and a communication device.
[0002]
[Prior art]
Generally, an isolator has a function of passing a signal only in a transmission direction and preventing transmission in a reverse direction, and is used in a transmission circuit unit of a mobile communication device such as a car phone or a mobile phone.
[0003]
For example, an isolator of this type is known from Japanese Patent Application Laid-Open No. 9-289402. In this isolator, a terminating resistor is printed and baked on a dielectric substrate containing a matching capacitor. Then, when power is absorbed by the terminating resistor, for example, when reflected power is input to the isolator, the terminating resistor generates heat. The heat is finally dissipated by radiation (radiation) or convection from a metal case or a terminal of the isolator, or dissipated by heat conduction to a printed circuit board on which the isolator is mounted.
[0004]
[Problems to be solved by the invention]
By the way, the transfer of heat from the terminating resistor to the metal case and the terminal is mainly based on the heat conduction of the dielectric substrate. The thermal conductivity varies depending on the dielectric, but is 20 W / mk for alumina. This is considerably worse when compared to the thermal conductivity of metal, for example, about 300 W / mk for silver. Therefore, the thermal resistance of this portion causes a rise in the temperature of the terminating resistor, and is one of the main factors that limit the withstand power of the isolator.
[0005]
Here, the withstand power is set to a continuous load state (for example, inputting 1 W of reverse power) for a sufficient time (1000 hours or 2000 hours, for example) in a prescribed use environment (eg, −45 to + 85 ° C.). , Meaning that the characteristics such as isolation are not impaired and do not change beyond the range of normal temperature characteristics.
[0006]
In an isolator or a circulator, a dielectric material having a higher dielectric constant is used in addition to alumina. However, they generally have a lower thermal conductivity than alumina, which is disadvantageous in terms of heat dissipation.
[0007]
Therefore, an object of the present invention is to provide a non-reciprocal circuit device and a communication device that can efficiently radiate heat generated by a terminating resistor to the outside.
[0008]
In the field of hybrid ICs including semiconductors, as described in JP-A-6-296106, a through-hole filled with a thick-film electrode material is provided between a dielectric substrate surface on which a semiconductor is mounted and a ground surface on the bottom surface of the substrate. (Thermal via) is provided, the bottom surface of the semiconductor is connected to the thermal via with a conductive paste (or a conductive adhesive) or a heat conductive paste, and heat generated by the semiconductor is radiated through the thermal via. This is because even if the bottom surface of the semiconductor is covered with an insulator or an electrode is provided on the bottom surface, the electrode has the same potential as the thermal via.
[0009]
However, a structure in which the thermal vias are directly connected cannot be adopted as the terminating resistor. This is because the thermal via has good electrical conductivity, and if it is directly connected to the terminating resistor, a desired resistance cannot be obtained. Further, in the structure in which the thermal via is connected to the terminating resistor via a heat conductive paste (or a heat conductive adhesive) having an insulating property, the thermal resistance increases due to voids (bubbles) generated in the heat conductive paste. Also, it is difficult to obtain a terminal resistor having a stable resistance value due to a pinhole. In addition, the manufacturing process becomes complicated.
[0010]
Means and action for solving the problem
To achieve the above object, the non-reciprocal circuit device according to the present invention includes:
(A) a permanent magnet;
(B) a ferrite to which a DC magnetic field is applied by a permanent magnet;
(C) a plurality of central electrodes arranged on the ferrite so as to cross each other in an electrically insulated state;
(D) a laminated substrate having a dielectric layer, a terminating resistor, and a heat-radiating conductor at least partially overlapping in plan view with the dielectric layer interposed between the terminating resistor;
It is characterized by having.
[0011]
The heat dissipation conductor is constituted by, for example, one or more heat dissipation via holes provided in the dielectric layer. It is preferable that the heat dissipation via hole is disposed in the metal case and is thermally connected to the metal case. Further, the thickness of the dielectric layer provided between the terminating resistor and the heat dissipation via hole is preferably 3 μm or more and 800 μm or less. If the thickness is less than 3 μm, pinholes are formed in the dielectric layer, causing a problem in withstand voltage. On the other hand, if the thickness exceeds 800 μm, the heat dissipation via hole and the terminating resistor are too far apart, which causes an increase in thermal resistance.
[0012]
Further, the dielectric layer provided between the terminating resistor and the heat dissipation via hole is made of alumina, a composite dielectric material mainly composed of alumina and glass, aluminum nitride, or a composite dielectric material of these. Is preferred. This is because the dielectric loss is small and the thermal conductivity and workability are excellent.
[0013]
With the above configuration, even if the terminating resistor generates heat by absorbing the reflected power entering the non-reciprocal circuit element, the heat is efficiently transmitted to the heat-radiating via hole through the thin dielectric layer with little thermal resistance. Conduct. Further, heat is conducted from the heat dissipation via hole to the metal case. The heat transmitted to the metal case is radiated to the outside by radiation (radiation), convection of air, and conduction from the ground terminal also serving as the metal case to the printed circuit board on which the non-reciprocal circuit element is mounted.
[0014]
Further, from the viewpoint of heat dissipation, it is preferable that the heat dissipation via holes are formed in as many dielectric layers as possible, and the ends thereof reach the surface of the laminated substrate. Further, the conductive paste filling the via holes for heat dissipation is preferably a material having good thermal conductivity such as silver, copper, a silver alloy, a copper alloy, and a thick film paste material composed of these metals and frit.
[0015]
It is preferable that the area of the cross section of the heat dissipation via hole is set to 20% or more and 400% or less of the area of the terminating resistor. This is because if the cross section of the heat dissipation via hole is smaller than 20% of the area of the terminating resistor, the improvement in power resistance is slight, and an effect corresponding to the cost of providing the heat dissipation via hole cannot be obtained. Further, even if a large heat dissipation via hole exceeding 400% is provided, the power resistance tends to be saturated, and on the other hand, cracks are likely to occur around the heat dissipation via hole. When a plurality of heat dissipation via holes are provided, the sum of the cross-sectional areas of the heat dissipation via holes is set to 20% or more and 400% or less of the area of the terminating resistor.
[0016]
Further, one end of the heat dissipation via hole may be electrically connected to the cold end side of the terminating resistor. Further, the heat dissipation via hole may be electrically connected to the hot end side of the terminating resistor, and a dielectric layer may be interposed between one end of the heat dissipation via hole and the ground. The terminating resistor may be disposed inside the laminated substrate or may be disposed on the surface of the laminated substrate.
[0017]
Further, the communication device according to the present invention includes the above-described non-reciprocal circuit device, so that performance and reliability are improved. A heat-generating electronic component such as a high-frequency power amplifier may be mounted on the laminated substrate of the non-reciprocal circuit device. The present invention is more effective under such severe operating conditions in a thermal environment.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a nonreciprocal circuit device and a communication device according to the present invention will be described with reference to the accompanying drawings.
[0019]
[First Embodiment, FIGS. 1 to 9]
FIG. 1 is an exploded perspective view of one embodiment of the nonreciprocal circuit device according to the present invention. The non-reciprocal circuit device 1 is a lumped constant type isolator. As shown in FIG. 1, the lumped-constant isolator 1 generally includes a metal case including a metal upper case 4 and a metal lower case 8, a permanent magnet 9, a ferrite 20, and center electrodes 21 to 23. And a laminated substrate 30.
[0020]
The metal upper case 4 has a substantially box shape and includes an upper portion 4a and four side portions 4b. The lower metal case 8 includes left and right sides 8b and a bottom 8a. In order to form a magnetic circuit, the metal upper case 4 and the metal lower case 8 are formed of, for example, a material made of a ferromagnetic material such as soft iron, and their surfaces are plated with Ag or Cu.
[0021]
The center electrode assembly 13 includes three sets of center electrodes 21 to 23 arranged on the upper surface of a rectangular microwave ferrite 20 so as to intersect at approximately 120 degrees with an insulating layer (not shown) interposed therebetween. I have. In the first embodiment, the center electrodes 21 to 23 are constituted by two lines. The center electrodes 21 to 23 may be wound around the ferrite 20 using a copper foil, or may be formed by printing a silver paste on or inside the ferrite 20. However, since the positional accuracy of the center electrodes 21 to 23 is higher when printing is performed, the connection with the laminated substrate 30 is stabilized. In particular, in the case of connecting with minute center electrode connection electrodes P1 to P3 (described later) as in this case, printing and forming the center electrodes 21 to 23 has better reliability and workability.
[0022]
As shown in FIG. 2, the laminated substrate 30 includes a center electrode connecting electrodes P1 to P3, a ground connecting electrode 31, a dielectric sheet 41 provided with via holes 18, a hot side capacitor electrodes 71a to 73a, and a circuit electrode 17 as shown in FIG. Sheet 42 provided with hot-side capacitor electrodes 71b-73b, heat dissipation via holes 19, etc., ground electrode 74, heat dissipation via holes 19, etc. And the dielectric sheet 43, 45, the input terminal electrode 14, the output terminal electrode 15, the ground terminal electrode 16, and the like.
[0023]
This laminated substrate 30 is manufactured as follows. That is, the dielectric sheets 41 to 45 are made of Al ₂ O ₃ With SiO as the main component ₂ , SrO, CaO, PbO, Na ₂ O, K ₂ O, MgO, BaO, CeO ₂ , B ₂ O ₃ It is made of a low-temperature sintered dielectric material containing one or more of the above as subcomponents.
[0024]
Further, a shrinkage suppression sheet 46 for suppressing the shrinkage of the laminated substrate 30 in the substrate plane direction (the XY direction) without producing the laminated substrate 30 under the firing conditions (especially, the firing temperature of 1000 ° C. or lower) is produced. The material of the shrinkage suppression sheet 46 is a mixed material of alumina powder and stabilized zirconia powder. The thickness of the sheets 41 to 46 is about 10 μm to 200 μm.
[0025]
The electrodes P1 to P3, 14 to 17, 31, 71a to 73a, 71b to 73b, 74 are formed on the sheets 41 to 46 by a method such as pattern printing. As a material for the electrodes P1 to P3 and the like, Ag, Cu, Ag-Pd or the like, which has a low resistivity and can be co-fired with the dielectric sheets 41 to 45, is used. These electrode materials are generally fixed to the laminated substrate 30 by mixing with a glass-based material called a frit. However, in some cases, the firing temperature of the laminated substrate 30 may be higher than the melting point of the electrode material, and the electrodes P1 to P3 may be once melted and fixed to the laminated substrate 30.
[0026]
The surfaces of the electrodes P1 to P3 and the like are plated with Au using Ni plating as a base. The Ni plating increases the bonding strength between the Ag and Au plating of the electrodes P1 to P3 and the like. The Au plating improves the solder wettability and has a high conductivity, so that the isolator 1 can have low loss. Further, in the case where there is an electrode to which a DC voltage is applied among the electrodes P1 to P3, if Ag is exposed on the surface of the electrode, the electrode may cause migration. ing. The thickness of the electrodes P1 to P3 is about 5 μm to 10 μm.
[0027]
The terminating resistor R is formed on the surface of the dielectric sheet 42 by a method such as pattern printing. Cermet, carbon, ruthenium or the like is used as a material of the resistor R.
[0028]
The signal via holes 18 and the heat dissipation via holes 19 are formed by forming via hole holes in advance in the dielectric sheets 41 to 45 by laser processing or punching processing and then filling the via hole holes with a conductive paste. . Generally, the same electrode material as the electrodes P1 to P3 (Ag, Cu, Ag-Pd, etc.) is used as the material of the conductive paste.
[0029]
If the cross-sectional shape of the heat dissipation via hole 19 is circular, the processing cost is reduced. The reason is that the manufacturing cost of the mold is low and the laser drilling can cope with it, and in that case, the mold cost is unnecessary. Further, there is an advantage that bubbles are hardly generated when the conductive paste is filled in the heat dissipation via hole. Further, the diameter of the heat dissipation via hole 19 is preferably set to be 0.05 mm or more and 0.5 mm or less. If the diameter is smaller than this, it is necessary to provide a very large number of via holes in a dense manner in order to enhance the heat radiation effect, which increases the cost. If the diameter is larger than this, cracks may occur during firing due to a difference in shrinkage ratio between the dielectric portion and the heat dissipation via hole 19 portion, or cracks may occur when a thermal cycle is applied. This is because there is concern and it is difficult to secure a space for providing such a large via hole.
[0030]
The capacitor electrodes 71a, 71b, 72a, 72b, 73a, 73b face the ground electrode 74 with the dielectric sheets 42 to 44 interposed therebetween to form matching capacitors C1, C2, C3. The matching capacitors C1 to C3 and the terminating resistor R together with the electrodes P1 to P3, 17, 31 and the signal via hole 18 constitute an electric circuit inside the multilayer substrate 30.
[0031]
The above dielectric sheets 41 to 45 are stacked, and further, a shrinkage suppression sheet 46 (an upper shrinkage suppression sheet is not shown) is stacked on the upper and lower sides thereof, and then fired. As a result, a sintered body is obtained, and thereafter, the unsintered shrinkage suppressing material is removed by an ultrasonic cleaning method or a wet honing method to obtain a laminated substrate 30 as shown in FIG.
[0032]
An input terminal electrode 14, an output terminal electrode 15, and a ground terminal electrode 16 are provided on the bottom surface of the laminated substrate 30. The input terminal electrode 14 is electrically connected to the capacitor electrodes 71a and 71b via the signal via hole 18, and the output terminal electrode 15 is electrically connected to the capacitor electrodes 72a and 72b. The ground terminal electrodes 16 are electrically connected to the circuit electrode 17 and the ground electrode 74, respectively. Particularly, on the input / output terminal electrodes 14 and 15, a protruding thick-film electrode is formed by applying a conductive paste such as Ag, Ag-Pd, or Cu, and then baking.
[0033]
The heat dissipation via holes 19 provided in each of the dielectric sheets 43 to 45 are connected in the stacking direction of the dielectric sheets 41 to 45 to form a columnar heat dissipation via hole. In plan view, part of the columnar heat dissipation via hole 19 overlaps the terminating resistor R. The upper end of the columnar heat dissipation via hole 19 is close to the terminating resistor R with the dielectric sheet 42 interposed therebetween, and the lower end is exposed on the back surface of the dielectric sheet 45 and is electrically connected to the ground terminal electrode 16.
[0034]
Note that the laminated substrate 30 is usually created in a motherboard state. Half cut grooves are formed on the mother board at a predetermined pitch, and the mother board is folded along the half cut grooves to obtain a laminated substrate 30 having a desired size from the mother board. Alternatively, the motherboard may be cut with a dicer, a laser, or the like to cut out a laminated substrate 30 having a desired size from the motherboard.
[0035]
The multilayer substrate 30 thus obtained has matching capacitors C1 to C3 and a terminating resistor R inside. The matching capacitors C1 to C3 are manufactured with required capacitance accuracy. However, trimming is performed before connecting the matching capacitors C1 to C3 and the center electrodes 21 to 23. That is, the laminated substrate 30 is trimmed (eliminated) with the inner (second layer) capacitor electrodes 71a, 72a, 73a together with the surface dielectric material in a single state. For the trimming, for example, a laser of a fundamental wave, a second harmonic, and a third harmonic of a cutting machine or YAG is used. If a laser is used, quick and accurate processing can be obtained. The trimming may be efficiently performed on the laminated substrate 30 in a motherboard state.
[0036]
As described above, since the capacitor electrodes 71a to 73a located on the outermost layer among the capacitor electrodes 71a to 73b are used as the trimming capacitor electrodes, the thickness of the dielectric layer to be removed at the time of trimming can be minimized. Furthermore, since the number of electrodes that cause an obstacle to trimming is reduced (only the connection electrodes P1 to P3 and 31 in the case of the first embodiment), the capacitor electrode area that can be trimmed is widened, and the capacitance adjustment range can be widened.
[0037]
The laminated substrate 30 also has a built-in terminating resistor R. Like the matching capacitors C1 to C3, the terminating resistor R can be adjusted in resistance value by trimming with the surface dielectric. Since the resistance value increases when the width of the resistor R is reduced even at one location, the resistor R is partially cut in the width direction.
[0038]
The above components are assembled as follows. That is, as shown in FIG. 1, the permanent magnet 9 is fixed to the ceiling of the metal upper case 4 by an adhesive. On the laminated substrate 30, the center electrode assembly 13 is soldered to one of the center electrodes 21 to 23 of the center electrode assembly 13 on the center electrode connection electrodes P1 to P3 formed on the surface of the laminated substrate 30. The other end of each of the center electrodes 21 to 23 is mounted on the ground connection electrode 31 by soldering. The soldering of the center electrodes 21 to 23 and the connection electrodes P1 to P3, 31 may be efficiently performed on the laminated substrate 30 in a motherboard state.
[0039]
The laminated substrate 30 is placed on the bottom 8a of the metal lower case 8, and the ground terminal electrodes 16 provided on the back surface of the sheet 45 are fixed to the bottom 8a by solder and are electrically connected. As a result, the ground can be sufficiently secured, so that the electrical characteristics of the isolator 1 can be improved.
[0040]
Then, the side portion 8b of the lower metal case 8 and the side portion 4b of the upper metal case 4 are joined by soldering or the like to form a metal case, which also functions as an electromagnetic shield, a ground terminal, and a yoke. That is, the metal case forms a magnetic path surrounding the permanent magnet 9, the center electrode assembly 13, and the laminated substrate 30. The permanent magnet 9 applies a DC magnetic field to the ferrite 20.
[0041]
FIG. 3 is a vertical sectional view of the isolator 1, and FIG. 4 is an electric equivalent circuit diagram thereof. In the laminated substrate 30 of the isolator 1 having the above configuration, the heat dissipation via holes 19 are provided below the terminating resistor R via a dielectric layer (dielectric sheet 42). Therefore, even if the terminating resistor R generates heat by absorbing the reflected power entering the isolator 1, the heat is efficiently transmitted to the heat dissipation via hole 19 through the thin dielectric layer with little thermal resistance. . Further, heat is conducted from the heat dissipation via hole 19 to the metal lower case 8 (metal case) via the ground terminal electrode 16. The heat transmitted to the metal case is radiated to the outside by radiation (radiation), convection of air, and conduction from the ground terminal also serving as the metal case to the printed circuit board on which the isolator 1 is mounted.
[0042]
Therefore, even when the same power is absorbed, the temperature at which the terminating resistor R rises is kept lower than before, and the reliability of the isolator 1 improves. Further, it is possible to obtain the isolator 1 that can handle the reflected power larger than before without changing the size of the isolator 1 or the terminating resistor R.
[0043]
Further, from the viewpoint of heat dissipation, the heat dissipation via holes 19 are preferably formed in as many dielectric sheets as possible, and the ends thereof preferably reach the surface of the multilayer substrate 30. Further, as the conductive paste filling the inside of the heat dissipation via hole 19, a material having good thermal conductivity such as Ag, Cu, Ag-Pd is preferable. In particular, when the same thick film electrode material as the electrodes P1 to P3 is used, the thermal conductivity is about 70% of that of a pure metal. Therefore, the heat dissipation via hole 19 formed by a method of solidifying and fixing the electrode once melted in the laminated substrate 30 is more advantageous in terms of heat conduction (= heat dissipation).
[0044]
Further, in the case of the first embodiment, the two are arranged so that the projection from above the heat dissipation via hole 19 overlaps the lower metal case 8 and is an adhesive excellent in soldering or thermal conductivity. The laminated substrate 30 and the lower metal case 8 are joined by a (heat conductive adhesive). That is, the ground terminal electrode 16 provided on the bottom surface of the multilayer substrate 30 is joined to the lower metal case 8 by soldering. Thereby, the thermal connection between the heat radiating via hole 19 and the metal case becomes more reliable, and the effect of the present invention is further enhanced. Note that the laminated substrate 30 and the lower metal case 8 do not necessarily have to be soldered, and may simply be pressed or adhered.
[0045]
When the heat dissipation via hole 19 is grounded, a capacitance is generated between the heat dissipation via hole 19 and the terminating resistor R. Since this capacitance is connected in series to the terminating resistor R, it is a large loss capacitance. Usually, such capacitance is not preferable for a tank circuit (parallel resonance circuit) such as the center electrode 21 (or 22) of the isolator 1 and the matching capacitor C1 (or C2). This is because the Q of the resonance circuit is lowered. However, in the case of the present invention, since the capacitance including the loss is connected to the terminal port P3 of the isolator 1, it does not pose a fatal problem. In addition, since the original capacitance can be reduced by the capacitance generated in this portion, the matching capacitor C3 of the termination port P3 can be reduced in size, and the isolator 1 can be further reduced in size. It becomes.
[0046]
Further, the thickness of the dielectric layer (in other words, the dielectric sheet 42) provided between the terminating resistor R and the heat dissipation via hole 19 is preferably 3 μm or more and 800 μm or less. This is because if the thickness is smaller than 3 μm, a short circuit may occur in a pinhole that may exist in the dielectric sheet 42. On the other hand, if the thickness exceeds 800 μm, the heat dissipation via hole 19 is too far from the terminating resistor R, and the effect of the heat dissipation via hole 19 is hardly obtained.
[0047]
Further, the dielectric sheet 42 is preferably made of alumina, a composite dielectric material containing alumina and glass as main components, aluminum nitride, or a composite dielectric material of these. This is because alumina and aluminum nitride have excellent thermal conductivity among dielectrics and insulators, and are easy to produce a laminated substrate. In particular, when mixed with glass, it is suitable for forming a multilayer substrate and providing a desired via hole therein.
[0048]
It is preferable that the area of the cross section of the heat dissipation via hole 19 is set to 20% or more and 400% or less of the area of the terminating resistor R. This is because, as shown in FIG. 5, when the cross section of the heat dissipation via hole 19 is smaller than 20% of the area of the terminating resistor R, the power durability is slightly improved, and an effect commensurate with the cost of providing the heat dissipation via hole 19 is obtained. It is not possible. Further, even if a large heat radiating via hole 19 exceeding 400% is provided, the withstand power tends to be saturated, while cracks around the heat radiating via hole 19 easily occur.
[0049]
Note that the area of the terminating resistor R means the area of the resistor film excluding the both ends overlapping the electrodes 73a and 17, that is, the area of the area actually functioning as a resistor. In the case of the first embodiment, the diameter of the heat dissipation via hole 19 is 0.8 mm, the area of the terminating resistor R is 0.50 mm × 0.45 mm, and the cross-sectional area of the heat dissipation via hole 19 is the area of the terminating resistor R. Was set to about 55%.
[0050]
Further, in the first embodiment, when the area of the cross section of the heat dissipation via hole 19 is S and the thickness of the laminated substrate 30 is T, the relational expression S> T ² / 16.
[0051]
Further, the heat dissipation via hole can be variously modified as shown in FIGS. The heat dissipation via hole 19A shown in FIG. 6 is not connected to any electrode, and is in a so-called electrically floating state. In general, a laminated substrate formed of a low-temperature sintered dielectric material has a larger shrinkage during firing of a thick-film conductor portion (via hole portion) than a dielectric portion, so that the via hole portion protrudes from the surface of the laminated substrate after firing. May be. Therefore, by adopting a structure in which the heat dissipation via hole 19A is sandwiched between dielectric sheets having no heat dissipation via hole 19A, the portion of the heat dissipation via hole 19A is prevented from protruding from the surface of the laminated substrate 30A.
[0052]
Further, the heat dissipation via hole 19B shown in FIG. 7 is in parallel with the signal via hole 18 connected to the cold end side of the terminating resistor R, and its position is eccentric from the center of the terminating resistor R. Thereby, the effective heat conduction path between the terminal resistor R at the upper end of the heat dissipation via hole 19B and the heat dissipation via hole 19B is shortened, and the heat resistance can be reduced. In addition, the lower end of the heat dissipation via hole 19B can be brought into thermal contact with the metal lower case 8 having a large heat capacity via the ground terminal electrode 16, and an excellent heat dissipation effect can be obtained.
[0053]
Further, the heat dissipation via hole 19C shown in FIG. 8 is connected to the hot-side capacitor electrode 73b connected to the hot end side of the terminating resistor R. Thereby, the thermal resistance between the terminal resistance R at the upper end of the heat dissipation via hole 19C and the heat dissipation via hole 19C can be reduced.
[0054]
Further, a dielectric layer is sandwiched between the lower end of the heat dissipation via hole 19C and the ground terminal electrode 16. As a result, the terminal resistor R and the heat dissipation via hole 19C have the same potential, and no capacitance is generated between them. On the other hand, the capacitance generated between the lower end of the heat radiating via hole 19C and the ground terminal electrode 16 does not include the loss, but only slightly widens the isolation bandwidth of the isolator.
[0055]
Further, the laminated substrate 30D shown in FIG. 9 is used when the diameter of the heat dissipation via hole cannot be increased due to design constraints or when only the heat dissipation via hole having a diameter of about 0.2 mm to 0.5 mm can be achieved due to manufacturing constraints. In order to realize good heat dissipation, two heat dissipation via holes 19D are provided.
[0056]
[Second Embodiment, FIGS. 10 and 11]
As shown in FIG. 10, the lumped-constant isolator 101 generally includes a metal case including a metal lower case 104 and a metal upper case 108, a permanent magnet 109, a ferrite 120, and center electrodes 121 to 123. A multilayer board 140 provided with matching capacitors C1 to C3, Cs, a trapping coil L and a terminating resistor R, and a resin terminal case 103 are provided.
[0057]
The metal lower case 104 has left and right side portions 104a and a bottom portion 104b, and is substantially U-shaped. The metal lower case 104 is formed integrally with the resin terminal case 103 by an insert molding method. Two ground terminals 117 extend from a pair of opposite sides of the bottom portion 104b of the metal lower case 104, respectively.
[0058]
At the bottom of the resin terminal case 103, the bottom 104b of the metal lower case 104 and the ground extraction electrode 117a are exposed. Further, input terminals 115 and output terminals 116 are insert-molded in the resin terminal case 103. The input terminal 115 and the output terminal 116 have one end exposed to the outer surface of the resin terminal case 103 and the other end exposed to the bottom of the resin terminal case 103 to be an input extraction electrode 115a and an output extraction electrode 116a. .
[0059]
As shown in FIG. 11, the laminated substrate 140 includes a dielectric sheet 141 provided with a center electrode 123, a terminating resistor R, a relay electrode 157, and a signal via hole 148, a center electrode 121, a trap coil L, and a ground-side capacitor electrode. 156, a dielectric sheet 142 provided with a heat dissipation via hole 149, etc., a dielectric sheet 143 provided with a center electrode 122, a heat dissipation via hole 149, etc., an input side connection electrode 151, an output side connection electrode 152, and a ground side connection electrode. 153 to 155 are formed on a dielectric sheet 144 provided on the back surface.
[0060]
The L-shaped port portion P1 of the center electrode 121 faces the ground-side connection electrodes 153 and 155 with the dielectric sheets 142 to 144 interposed therebetween, and constitutes matching capacitors C1 and Cs, respectively. The port portion P2 of the center electrode 122 faces the ground-side capacitor electrode 156 with the dielectric sheet 142 interposed therebetween to form a matching capacitor C2. The port portion P3 of the center electrode 123 faces the ground-side connection electrode 154 with the dielectric sheets 141 to 144 interposed therebetween to form a matching capacitor C3. The matching capacitors C1 to C3 and Cs and the terminating resistor R, together with the electrodes 151, 152 and 157 and the via hole 148, form an electric circuit inside the laminated substrate 140.
[0061]
The heat dissipation via holes 149 provided in each of the dielectric sheets 142 to 144 are connected in the stacking direction of the dielectric sheets 141 to 144 to form a columnar heat dissipation via hole. In plan view, part of the columnar heat dissipation via hole 149 overlaps the terminating resistor R. The upper end of the columnar heat dissipation via hole 149 is close to the terminating resistor R with the dielectric sheet 141 interposed therebetween, and the lower end is exposed on the back surface of the dielectric sheet 144 and is electrically connected to the ground-side connection electrode 154.
[0062]
After the above dielectric sheets 141 to 144 are laminated, they are integrally fired to form a laminated substrate 140 as shown in FIG. The laminated substrate 140 is housed in the bottom of the resin terminal case 103 together with the ferrite 120. The back surface of the ferrite 120 is in surface contact with the bottom 104b of the lower metal case 104, and the laminated substrate 140 is disposed on the top surface of the ferrite 120.
[0063]
At this time, the input-side connection electrodes 151 provided on the bottom surface of the laminated substrate 140 are soldered to the input lead-out electrodes 115a exposed on the bottom of the resin terminal case 103. The output side connection electrode 152 and the ground side connection electrodes 153 to 155 are also soldered to the output extraction electrode 116a and the ground extraction electrode 117a, respectively. Similarly, the lower end of the columnar heat dissipation via hole 149 exposed on the bottom surface of the laminated substrate 140 is also soldered to the ground extraction electrode 117a.
[0064]
Further, a metal upper case 108 is mounted from above. On the ceiling of the metal upper case 108, a permanent magnet 109 is arranged. The permanent magnet 109 applies a DC magnetic field to the ferrite 120. After the metal upper case 108 and the metal lower case 104 are fitted, they are electrically connected by a method such as solder reflow. Thus, the metal upper case 108 and the metal lower case 104 form a metal case, and constitute a magnetic circuit.
[0065]
Thus, the isolator 101 is obtained. The isolator 101 having the above configuration has the same operation and effect as the isolator 1 of the first embodiment.
[0066]
[Third embodiment, FIG. 12]
In the third embodiment, a mobile phone will be described as an example of the communication device according to the present invention.
[0067]
FIG. 12 is an electric circuit block diagram of the RF portion of the mobile phone 220. In FIG. 12, 222 is an antenna element, 223 is a duplexer, 231 is a transmission-side isolator, 232 is a transmission-side power amplifier, 233 is a transmission-side interstage bandpass filter, 234 is a transmission-side mixer, 235 is a reception-side power amplifier, 236 is a reception-side interstage bandpass filter, 237 is a reception-side mixer, 238 is a voltage controlled oscillator (VCO), and 239 is a local bandpass filter.
[0068]
Here, the irreversible circuit element 240 uses the lumped-constant type isolators 1 and 101 of the first and second embodiments as the transmission-side isolator 231, and the transmission-side power amplifier 232 is mounted on the laminated substrates 30 and 140. It is a compound type mounted. By mounting the non-reciprocal circuit element 240, a highly reliable mobile phone 220 with improved electrical characteristics can be realized.
[0069]
More specifically, in the case where a heat-generating electronic component such as a power amplifier is combined with an isolator, the area occupied by each component tends to be reduced. Is optimal. In particular, when combined with the transmission-side power amplifier 232, if the temperature of the laminated substrates 30 and 140 themselves rises, the output of the power amplifier 232 using FETs decreases, and the power amplifier 232 using bipolar transistors decreases. This may cause the amplifying element to break down due to thermal runaway. Therefore, the present invention in which heat is radiated to the outside with low thermal resistance without increasing the temperature of the laminated substrates 30 and 140 is extremely advantageous.
[0070]
[Other embodiments]
It should be noted that the present invention is not limited to the above embodiment, and can be variously modified within the scope of the gist. For example, the terminating resistor may be disposed inside the laminated substrate as in the above embodiment, or may be disposed on the surface of the laminated substrate.
[0071]
The capacitor formed inside the multilayer substrate is not limited to the matching capacitor, but may be a capacitor for forming a low-pass filter, a trap circuit, or the like. Further, the non-reciprocal circuit device according to the present invention may be a circulator or a non-reciprocal circuit device with a built-in coupler other than the isolator.
[0072]
The shape of the cross section of the heat dissipation via hole is arbitrary, and may be a rectangular shape in addition to a circular shape. With a rectangular shape, the shape of the terminating resistor R and the shape of the heat dissipation via hole can be made to substantially correspond to each other, and when space is limited, maximum heat dissipation performance can be obtained with a minimum area.
[0073]
【The invention's effect】
As is apparent from the above description, according to the present invention, the heat dissipation via hole is provided below the terminating resistor via the dielectric layer. Therefore, even if the terminating resistor generates heat by absorbing the reflected power entering the non-reciprocal circuit element, the heat is efficiently transmitted to the heat dissipation via hole through the thin dielectric layer with low thermal resistance. Further, heat is conducted from the heat dissipation via hole to the metal case. The heat transmitted to the metal case is radiated to the outside by radiation (radiation), convection of air, and conduction from the ground terminal also serving as the metal case to the printed circuit board on which the non-reciprocal circuit element is mounted. As a result, a high-performance, highly-reliable and small non-reciprocal circuit device or communication device can be obtained.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing one embodiment of a non-reciprocal circuit device according to the present invention.
FIG. 2 is an exploded perspective view of the laminated substrate shown in FIG.
FIG. 3 is a vertical sectional view of the non-reciprocal circuit device shown in FIG.
FIG. 4 is an electrical equivalent circuit diagram of the non-reciprocal circuit device shown in FIG.
FIG. 5 is a graph showing power resistance characteristics.
FIG. 6 is a vertical sectional view showing a modified example of the laminated substrate shown in FIG. 1;
FIG. 7 is a vertical sectional view showing another modified example of the laminated substrate shown in FIG. 1;
FIG. 8 is a vertical sectional view showing still another modified example of the laminated substrate shown in FIG. 1;
FIG. 9 is a vertical sectional view showing still another modified example of the laminated substrate shown in FIG. 1;
FIG. 10 is an exploded perspective view showing another embodiment of the non-reciprocal circuit device according to the present invention.
11 is an exploded perspective view of the multilayer substrate shown in FIG.
FIG. 12 is an electric circuit block diagram of a communication device according to the present invention.
[Explanation of symbols]
1,101… Lumped constant type isolator
4,108… Metal upper case
8,104 ... Metal lower case
9,109 ... permanent magnet
13 ... Center electrode assembly
19, 149: Thermal via holes
20,120 ... Ferrite
21-23, 121-123 ... Center electrode
30, 30A, 30B, 30C, 30D, 140 ... laminated substrate
41 to 45, 141 to 144 ... dielectric sheet
220… mobile phone
232 ... Power amplifier
240 ... non-reciprocal circuit element
C1 to C3 ... matching capacitors
R: Terminating resistor

Claims (18)

A permanent magnet,
A ferrite to which a DC magnetic field is applied by the permanent magnet;
A plurality of center electrodes arranged in an electrically insulated state crossing on the ferrite,
A dielectric substrate, a terminating resistor, and a laminated substrate having a heat-radiating conductor at least partially overlapping in plan view with the dielectric layer interposed between the terminating resistors,
A non-reciprocal circuit device comprising: 2. The non-reciprocal circuit device according to claim 1, wherein the heat-dissipating conductor includes one or more heat-dissipating via holes provided in the dielectric layer. 3. 3. The non-reciprocal circuit device according to claim 2, wherein an end of the heat dissipation via hole opposite to the end arranged on the terminating resistor reaches the surface of the multilayer substrate. 4. The laminated substrate includes, in addition to the dielectric layer provided between the terminating resistor and the heat dissipation via hole, a dielectric layer not provided with the heat dissipation via hole. The non-reciprocal circuit device according to claim 2. The non-reciprocal circuit device according to any one of claims 2 to 4, wherein a thickness of a dielectric layer provided between the terminating resistor and the heat dissipation via hole is 3 µm or more and 800 µm or less. . The non-reciprocal circuit device according to any one of claims 2 to 5, wherein one end of the heat dissipation via hole is electrically connected to a cold end side of the terminating resistor. The heat dissipation via hole is electrically connected to a hot end side of the terminating resistor, and a dielectric layer is interposed between one end of the heat dissipation via hole and ground. The non-reciprocal circuit device according to claim 5. 8. The non-reciprocal circuit device according to claim 2, wherein an area of a cross section of the heat dissipation via hole is 20% or more and 400% or less of an area of the terminal resistor. 9. The non-reciprocal circuit device according to any one of claims 2 to 8, wherein a cross-sectional shape of the heat dissipation via hole is substantially rectangular or substantially circular. 9. The non-reciprocal circuit according to claim 2, wherein a cross-sectional shape of the heat dissipation via hole is substantially circular, and a diameter is 0.05 mm or more and 0.5 mm or less. 10. element. The dielectric layer disposed between the terminating resistor and the heat dissipation via hole may be any one of alumina, a composite dielectric material containing alumina and glass as main components, aluminum nitride, and a composite dielectric material thereof. The non-reciprocal circuit device according to any one of claims 2 to 10, wherein The material of the heat dissipation via hole is any one of silver, copper, a silver alloy, a copper alloy, and a thick film paste material composed of these metals and a frit. The non-reciprocal circuit device according to claim 1. A metal case surrounding the permanent magnet, the ferrite, and the center electrode, wherein the heat dissipation via hole is arranged in the metal case such that a projection of the heat dissipation via hole overlaps the metal case. The nonreciprocal circuit device according to any one of claims 2 to 12. The non-reciprocal circuit device according to claim 13, wherein the heat dissipation via hole and the metal case are thermally connected. The non-reciprocal circuit device according to claim 2, wherein a matching capacitor is provided on the laminated substrate. 16. The non-reciprocal circuit device according to claim 2, wherein a heat-generating electronic component is mounted on the laminated substrate. The non-reciprocal circuit device according to claim 16, wherein the heat-generating electronic component is a high-frequency power amplifier. A communication device comprising the non-reciprocal circuit device according to claim 1.

Images