JP3583036B2 - Non-reciprocal circuit device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a non-reciprocal circuit device used for a microwave circuit or the like.
[0002]
[Prior art]
2. Description of the Related Art A microwave circuit incorporated in a communication device using a high frequency uses a non-reciprocal circuit element such as an isolator or a circulator in order to improve communication quality such as multimedia wireless communication. Although the nonreciprocal circuit device is required to be miniaturized, the efficiency of the semiconductor device connected to the nonreciprocal circuit device is improved, and the power to be handled tends to increase. Further, in the case of manufacturing a non-reciprocal circuit device, in order to avoid soldering and a flux cleaning process, from the viewpoint of environmental problems, a solderless process in a metal joining process is being promoted.
[0003]
Here, a conventional non-reciprocal circuit device will be described with reference to FIG. 13A and 13B show a microstrip type isolator. FIG. 13A is a perspective view, and FIG. 13B is a cross-sectional view taken along line X-Y in FIG.
[0004]
As shown in FIG. 13A, the non-reciprocal circuit device includes a ferrite substrate 131, a line conductor 132 in close contact with the ferrite substrate 131, a ground conductor 133 in close contact with the opposite side of the line conductor 132, and a carrier in close contact with the ground conductor 133. It is composed of a plate 135, a magnet 135 that applies a magnetic field in the direction of the arrow Y through the line conductor 132 to magnetize the ferrite substrate 131 (magnets are omitted in the following drawings) 135, a terminator 136, and the like.
[0005]
The ferrite substrate 131 and the terminator 136, and the ground conductor 133 and the carrier plate 134 are joined by a joining material 137 such as solder or a conductive adhesive. In this case, the ground conductor 133 and the carrier plate 134 are electrically and thermally connected by the joining material 137.
[0006]
In the case of the non-reciprocal circuit device having the above-described configuration, the line conductor 132 and the ground conductor 133 are usually formed in close contact with the ferrite substrate 131 by metal deposition or thick film baking. However, in recent years, a method of directly joining the line conductor 132 and the ground conductor 133 to the ferrite substrate 131 using a DBC (Direct Bond Copper) technique for directly joining a copper plate has been put to practical use. Further, in the case of non-reciprocal circuit devices, it is desired to avoid soldering and flux cleaning steps from the viewpoint of environmental problems, and it is desired to reduce the number of steps in order to reduce costs.
[0007]
Next, another conventional non-reciprocal circuit device will be described with reference to FIG. 13A is a perspective view, and FIG. 13B is a cross-sectional view taken along line X-Y in FIG. 13A. Parts corresponding to those in FIG. 13 are denoted by the same reference numerals, and redundant description is partially omitted. In this example, the carrier plate 134 is made of copper, and the line conductor 132 and the carrier plate 134 made of copper are directly bonded to both surfaces of the ferrite substrate 131 by the DBC method.
[0008]
In the case of this configuration, the joining of the line conductor 132 and the carrier plate 134 is performed simultaneously in one step. Therefore, a complicated process such as cream solder printing → reflow → flux cleaning is not required.
[0009]
In the case of a conventional non-reciprocal circuit device, for example, a carrier plate-separated type non-reciprocal circuit device in which a carrier plate is bonded later, the ground conductor 133 and the carrier plate 134 are individually surface-treated. However, as shown in FIG. 14, when the line conductor 132 and the carrier plate 134 are integrated with the ferrite substrate 131 by the DBC method, respectively, there is an advantage that the surface treatment only needs to be performed once. Furthermore, since a material having high thermal resistance such as solder or conductive adhesive does not intervene in the joint portion, heat generated by loss of the non-reciprocal circuit element can be efficiently radiated to the case and the like, and there is an advantage that power durability is increased.
[0010]
[Problems to be solved by the invention]
In the conventional nonreciprocal circuit device, when the thickness of the carrier plate 134 is smaller than the thickness of the ferrite substrate 131, no problem such as breakage of the ferrite substrate 131 occurs. However, depending on the bonding area with the ferrite substrate 131, when the thickness of the carrier plate 134 is increased, the ferrite substrate 131 may be damaged.
[0011]
For example, in the method of joining the ferrite substrate 131 and the carrier plate 134 by the DBC method, the ferrite substrate 131 is melt-joined at about 1000 ° C., and then cooled and fixed. At this time, if the heat shrinkage stress of the carrier plate 134 is larger than the bending strength of the ferrite substrate 131, the ferrite substrate 131 is broken.
[0012]
Here, the state of destruction of the ferrite substrate 131 will be described.
[0013]
FIG. 15 shows a case where the ground conductor 133 having a thickness of 0.1 mm and the carrier plate 134 are joined by solder 137 in the structure of FIG. In this case, as shown in FIG. 15, no destruction occurs in the ferrite substrate 131. This is presumably because the solder 137 has flexibility, so that the stress due to the difference in the coefficient of thermal expansion is absorbed by the solder 137 at a temperature similar to the soldering.
[0014]
FIG. 16 shows a case in which a ferrite substrate 131 having a width of 10 mm, a length of 10 mm, and a thickness of 1 mm is used in the structure of FIG. 14 and the ferrite substrate 131 and carrier plates 134 of various thicknesses are directly bonded by the DBC method. ing. As shown in FIG. 16, when the thickness of the carrier plate 134 exceeds 0.5 mm, the ferrite substrate 131 is broken.
[0015]
By the way, the carrier plate 134 is required to have a certain thickness from the viewpoint of easy handling. For example, if the thickness of the carrier plate 134 is small, irregularities are likely to occur, and a gap is generated when the carrier plate 134 is attached to the case, so that grounding as a non-reciprocal circuit element becomes insufficient, and microwave characteristics such as insertion loss deteriorate. . In addition, heat radiation is deteriorated, which may cause a temperature change in various characteristics. In order to prevent the destruction of the ferrite substrate 131, it is conceivable to increase the thickness of the ferrite substrate 131 and increase its mechanical strength. However, the thickness is limited in terms of miniaturization and cost of the product.
[0016]
An object of the present invention is to provide a non-reciprocal circuit device which solves the above-mentioned drawbacks and in which a ferrite substrate and a metal conductor portion are joined by a DBC method so that the ferrite substrate is not broken even if the carrier plate is thickened. .
[0017]
[Means for Solving the Problems]
The present invention relates to a ferrite substrate, a line conductor disposed on one surface of the ferrite substrate, a ground conductor disposed on the other surface of the ferrite substrate, and a carrier plate disposed in contact with the ground conductor. And a magnet disposed on one or both sides of the ferrite substrate, in the non-reciprocal circuit device, the ground conductor and the carrier plate formed of copper are provided with holes that are displaced and penetrated so that the positions do not overlap. The ferrite substrate and the ground conductor, and the ground conductor and the carrier plate are each bonded by a DBC method.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIG. FIG. 1A is a perspective view as viewed from the carrier plate side, and FIG. 1B is a cross-sectional view of FIG. 1A taken along line XY in the direction of the arrow.
[0019]
A microstrip line 12 is joined to one surface of a ferrite substrate 11 having a thickness h by a DBC method, and a carrier plate 13 having a thickness H is joined to the other surface by a DBC method. A terminator 14 is connected to the carrier plate 13 using a small amount of bonding material 15 such as solder or conductive adhesive. The carrier plate 13 is provided with a plurality of small holes A1 penetrated by etching or press working.
[0020]
The diameter d of the hole A provided in the carrier plate 13 is determined in consideration of the operating frequency of the non-reciprocal circuit device, the insertion loss of the non-reciprocal circuit device, the joint area between the ferrite substrate 11 and the carrier plate 13, the heat generation amount, and the like. 11 is determined experimentally, for example, so as not to be damaged.
[0021]
According to the above-described configuration, the solder is used only in the connection portion between the carrier plate 13 and the terminator 14, and is suppressed to a small amount. For example, compared to the case where a conventional thick film type carrier plate is joined by soldering (FIG. 13), the amount of solder used is several percent or less. If the carrier plate 13 and the terminator 14 are joined with a conductive adhesive, the amount of solder used can be reduced to zero.
[0022]
Here, FIG. 2 shows a destruction state of the non-reciprocal circuit device having the configuration of FIG. FIG. 2 shows a case where the dimensions of the ferrite substrate 11 are 10 mm in width, 10 mm in length, and 1 mm in thickness (h), and the ferrite substrate 11 of this dimension and various thicknesses (H) in which a plurality of holes A1 are provided. 3 shows a state of destruction when the carrier plate 13 is joined by the DBC method.
[0023]
As can be seen by comparing FIG. 2 and FIG. 16, even when the thickness (H) of the carrier plate 13 increases, the ferrite substrate 11 does not break. This is presumably because the provision of the plurality of holes A1 in the carrier plate 13 reduced the bonding area between the ferrite substrate 11 and the carrier plate 13, and reduced the stress caused by the difference in the coefficient of thermal expansion. Therefore, when the plurality of holes A1 are provided in the carrier plate 13, the thickness (H) of the carrier plate 13 can be increased, and the handling strength as a non-reciprocal circuit device increases.
[0024]
Another embodiment of the present invention will be described with reference to FIG. 3A is a perspective view as viewed from the carrier plate side, and FIG. 3B is a cross-sectional view of FIG. 3A taken along line X-Y in the direction of the arrow, and the same portions as those in FIG. The reference numerals are used, and a duplicate description is partially omitted.
[0025]
In the case of this embodiment, a ground conductor 31 is provided between the ferrite substrate 11 and the carrier plate 13, and a plurality of holes B1 penetrating through the ground conductor 31 are provided as shown in the sectional view of FIG. The ferrite substrate 11 and the ground conductor 31, and the ground conductor 31 and the carrier plate 13 are respectively bonded by the DBC method.
[0026]
FIG. 4 shows a destruction state of the non-reciprocal circuit device having the configuration of FIG. As can be seen by comparing FIG. 4 with FIG. 16, also in this case, the thickness (H) of the carrier plate 13 can be increased.
[0027]
Next, another embodiment of the present invention will be described with reference to FIG. FIG. 5A is a perspective view as viewed from the carrier plate side, and FIG. 5B is a cross-sectional view of FIG. 5A taken along the line XY in the direction of the arrow. The same reference numerals are given, and duplicate description is partially omitted. .
[0028]
In this embodiment, the ferrite substrate 11 and the ground conductor 31 having a thickness t are joined by the DBC method, and at the same time, the ground conductor 31 and the carrier plate 13 provided with the hole A1 are joined by the DBC method. In this case, a ground conductor 31 having no hole is closely bonded to the ferrite substrate 11. Therefore, the insertion loss is reduced, and the heat radiation effect is improved. Further, since the ground conductor 31 is formed thin and the hole A1 is provided in the carrier plate 13, the ferrite substrate 11 can withstand residual stress due to a difference in thermal expansion coefficient.
[0029]
FIG. 6 shows the destruction state of the non-reciprocal circuit device having the configuration shown in FIG. FIG. 6 shows the state of destruction of the ferrite substrate 11 with respect to the carrier plate 13 having various thicknesses (H). As can be seen by comparing FIG. 6 and FIG. H) can be made thicker.
[0030]
Next, modified examples of the ground conductor 31 and the carrier plate 13 which are sequentially joined to one side of the ferrite substrate 11 will be described with reference to FIGS. 7 to 12, parts corresponding to those in FIGS. 1, 3, and 5 are denoted by the same reference numerals, and duplicate description is partially omitted.
[0031]
In FIG. 7, a plurality of depressions A2 having a certain depth are provided in the carrier plate 13, and the side of the carrier plate 13 where the depressions A2 are provided is joined to the ferrite substrate 11 by the DBC method. In this case as well, when the ferrite substrate 11 and the carrier plate 13 having various thicknesses were joined and the state of destruction was measured, the same result as in FIG. 2 was obtained. This is because the bonding area between the ferrite substrate 11 and the carrier plate 13 is reduced by providing the plurality of depressions A2 in the carrier plate 13, and the residual stress due to the difference in the coefficient of thermal expansion between the ferrite substrate 11 and the carrier plate 13 is reduced. Probably because. The depression A2 of the carrier plate 13 can be formed by etching or machining.
[0032]
In FIG. 8, the ferrite substrate 11 and the ground conductor 31 are joined by the DBC method, and the carrier plate 13 provided with the plurality of depressions A2 and the ground conductor 31 are joined by the DBC method. FIG. 9 shows that the ferrite substrate 11 and the ground conductor 31 and the ground conductor 31 and the carrier plate 13 are provided with a plurality of depressions B2 and A2, respectively. Are joined by the DBC method so that the positions of the two coincide. FIG. 10 shows a case where a plurality of holes B1 and a plurality of depressions A2 having a certain depth are provided in the ground conductor 31 and the carrier plate 13, respectively. The positions of the holes B1 and the depressions A2 are shifted and joined by the DBC method.
[0033]
In the case of FIGS. 7 to 10, the back surface of the ground conductor 31 or the carrier plate 13 located in the lower layer has a flat surface without any depression. Therefore, when the ground conductor 31 or the carrier plate 13 is joined to a case (not shown) or the like, good electrical and mechanical contact can be obtained. As shown in FIG. 10, when the positions of the holes B1 and the depressions A2 of the ground conductor 31 and the carrier plate 13 are shifted, a good heat radiation effect is obtained because the holes B1 and the depressions A2 having poor heat conduction are not continuous. .
[0034]
FIG. 11 shows that a plurality of dents B2 having a certain depth are provided in the ground conductor 31 and a plurality of holes A1 penetrating through the carrier plate 13 are provided. The ferrite substrate 11 and the ground conductor 31, and the ground conductor 31 and the carrier plate 13 are simultaneously bonded by the DBC method.
[0035]
FIG. 12 shows holes B1 and A1 penetrating the ground conductor 31 and the carrier plate 13, respectively. The positions of the holes B1 and A1 of the ferrite substrate 11 and the ground conductor 31, and the positions of the holes B1 and A1 of the ground conductor 31 and the carrier plate 13 match. As shown in FIG. In the case of this configuration, since the positions of the holes B1 and A1 of the ground conductor 31 and the carrier plate 13 are shifted, a good heat radiation effect can be obtained.
[0036]
7 to 12, the thickness of the carrier plate 13 can be made larger than that of the conventional structure.
[0037]
According to the above-described structure, a hole or a depression is formed in the ground conductor or the carrier plate to be bonded to the ferrite substrate, and the ground conductor and the carrier plate are DBC bonded to the ferrite substrate, or the ground conductor and the carrier plate are DBC bonded to the ferrite substrate. . In this case, the ferrite substrate does not break even if the thickness of the carrier plate is increased. Therefore, it is possible to realize a nonreciprocal circuit device having the mechanical strength required for mounting while maintaining characteristics such as heat dissipation and insertion loss in a practical range, and in which the ferrite substrate is not broken by a difference in thermal expansion coefficient. In addition, since the destruction of the ferrite substrate due to a difference in thermal expansion coefficient or the like is prevented, the ferrite substrate and the carrier plate, or the ferrite substrate and the ground conductor and the carrier plate can be simultaneously bonded by the DBC method. Therefore, an inexpensive nonreciprocal circuit device with a reduced number of steps can be realized. The amount of solder even trace amounts if Ku can realize non-reciprocal circuit element of zero.
[0038]
In the above embodiment, the case of an isolator has been described, but the present invention is also applicable to a circulator or a three-conductor type non-reciprocal circuit device.
[0039]
【The invention's effect】
According to the present invention, in a configuration in which a ferrite substrate and a metal conductor portion are joined by a DBC method, a nonreciprocal circuit device in which the ferrite substrate is not broken even when the carrier plate is thickened can be realized.
[Brief description of the drawings]
FIG. 1 is a structural diagram for describing an embodiment of the present invention.
FIG. 2 is a diagram for explaining characteristics of the embodiment of the present invention.
FIG. 3 is a structural diagram for explaining another embodiment of the present invention.
FIG. 4 is a diagram for explaining characteristics of another embodiment of the present invention.
FIG. 5 is a structural diagram for explaining another embodiment of the present invention.
FIG. 6 is a diagram for explaining characteristics of another embodiment of the present invention.
FIG. 7 is a schematic structural diagram for explaining a modified example of the ground conductor of the present invention.
FIG. 8 is a schematic structural diagram for explaining a modified example of the ground conductor and the carrier plate of the present invention.
FIG. 9 is a schematic structural diagram for explaining a modified example of the ground conductor and the carrier plate of the present invention.
FIG. 10 is a schematic structural diagram for explaining a modified example of the ground conductor and the carrier plate of the present invention.
FIG. 11 is a schematic structural diagram for explaining a modified example of the ground conductor and the carrier plate of the present invention.
FIG. 12 is a schematic structural diagram for describing a modified example of the ground conductor and the carrier plate of the present invention.
FIG. 13 is a structural diagram for explaining a conventional example.
FIG. 14 is a structural diagram for explaining another conventional example.
FIG. 15 is a diagram for explaining characteristics of a conventional example.
FIG. 16 is a diagram for explaining characteristics of another conventional example.
[Explanation of symbols]
11 Ferrite substrate 12 Line conductor 13 Carrier plate 14 Terminator 15 Bonding material A Hole penetrating the carrier plate d Diameter of hole penetrating the carrier plate

Claims (4)

A ferrite substrate; a line conductor disposed on one surface of the ferrite substrate; a ground conductor disposed on the other surface of the ferrite substrate; a carrier plate disposed in contact with the ground conductor; In a non-reciprocal circuit device including a magnet disposed on one or both sides of a substrate, the ground conductor and the carrier plate formed of copper are provided with holes that are shifted so as not to overlap with each other, and the ferrite substrate is provided . And a ground conductor, and the ground conductor and the carrier plate are respectively bonded by a DBC method. A ferrite substrate; a line conductor disposed on one surface of the ferrite substrate; a ground conductor disposed on the other surface of the ferrite substrate; a carrier plate disposed in contact with the ground conductor; In a non-reciprocal circuit device including a magnet disposed on one or both sides of a substrate, the ground conductor and the carrier plate are formed of copper, the ground conductor is provided with depressions, and the carrier plate is provided with the ground conductor. A hole penetrating the ferrite substrate and the ground conductor, and the ground conductor and the carrier plate are bonded by a DBC method, respectively, so that holes are provided so as to be shifted so as not to overlap with the depressions of the non-reciprocal circuit. element. A ferrite substrate; a line conductor disposed on one surface of the ferrite substrate; a ground conductor disposed on the other surface of the ferrite substrate; a carrier plate disposed in contact with the ground conductor; in non-reciprocal circuit element and a magnet disposed on one or both sides of the substrate, said ground conductor and said carrier plate is made of copper, a hole through provided on the ground conductor, wherein the said carrier plate A non-reciprocal circuit, wherein a recess is provided so as to be shifted so that the position of the hole does not overlap with the hole of the ground conductor, and the ferrite substrate and the ground conductor, and the ground conductor and the carrier plate are respectively bonded by a DBC method. element. A ferrite substrate; a line conductor disposed on one surface of the ferrite substrate; a ground conductor disposed on the other surface of the ferrite substrate; a carrier plate disposed in contact with the ground conductor; In a non-reciprocal circuit device including a magnet disposed on one side or both sides of a substrate, the ground conductor and the carrier plate formed of copper are provided with depressions so that the positions are not overlapped , and the ferrite substrate and the A non-reciprocal circuit device, wherein a ground conductor and the ground conductor and the carrier plate are respectively bonded by a DBC method.

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