JP2014132651A - Envelope for microwave power element, microwave power element and method for producing them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an envelope for a microwave power element capable of improving heat dissipation, the microwave power element, and a method for producing them.SOLUTION: An envelope 2 for a microwave power element includes: a ceramic frame 12 with a lead; and a metal base plate 13 consisting of one kind of Cu, Cu-diamond composite material and Al-diamond composite material. The ceramic frame 12 with the lead is airtightly joined to the metal base plate 13 with low temperature sinterable metal particles.

Description

  The present invention relates to an envelope for a microwave power element, a microwave power element including an internal matching circuit element, and a method for manufacturing the same.

  In recent years, the output of microwave power elements has been remarkably increased, and power elements of 100 W to 200 W have been used to replace electron tubes such as mobile phone base stations, radars, or magnetrons. Therefore, it is essential to improve the heat dissipation of the microwave power element and to reduce the price. A general configuration of a microwave power element including an internal matching circuit element is as follows. That is, an alumina substrate on which chip capacitors and distributed constant circuits are formed is disposed on the input side with respect to the semiconductor chip, and an alumina substrate on which distributed constant circuits are formed on the output side with respect to the semiconductor chip. . These are arranged in a ceramic frame constituting an envelope for a microwave power element (hereinafter referred to as an envelope). Patent Document 1 and the like show a configuration in which a semiconductor chip and an internal matching circuit element are connected by wiring with an Au wire, an aluminum wire or the like, and connected to a lead terminal of an envelope.

  The microwave power element is formed, for example, by mounting a semiconductor chip and an internal matching circuit element on an envelope, performing wiring, and then sealing. In general, the semiconductor chip and the internal matching circuit element are brazed to the envelope without using flux with AuSn eutectic solder. The mounting temperature when brazing with AuSn eutectic solder is 280-300 ° C.

  The envelope is manufactured by joining a ceramic frame with leads attached to a metal base plate. This joining is performed by silver brazing, and hermetic joining is performed at a high temperature of about 800 ° C. For this reason, the metal base plate is made of a material having a thermal expansion coefficient close to that of ceramic. For example, for the metal base plate, an alloy of CuW (thermal conductivity varies in the range of 180 to 230 W / mK depending on the composition ratio) and an alloy of CuMo (thermal conductivity of 160 to 280 W / mK) are used.

  In a large envelope for electric power, an alloy of CuW (11% Cu) close to the thermal expansion coefficient of ceramic is used. This envelope is sufficiently heat resistant to the mounting temperature.

  As for low-temperature bonding, a bonding technique using metal nanoparticles having high heat resistance and high bonding strength is known (for example, see Patent Document 2).

Japanese Patent Laid-Open No. 7-74557 (see page 3 [0016] and FIG. 1) JP 2007-44754 A (refer to page 3 [0013])

  In the microwave power element described above, the semiconductor chip and the internal matching circuit element are arranged at a high density, the number of parts is large, and the dimensions of each part are different. Therefore, the batch mounting method using a reflow furnace is not adopted. Each component is individually mounted by hand using tweezers under a microscope. And manual mounting is a factor of cost increase.

  In the case of an alloy of CuW (11% Cu) close to the thermal expansion coefficient of ceramic, the thermal conductivity is as low as 180 W / mK. That is, since the composition having lower thermal conductivity is closer to the thermal expansion coefficient of the ceramic, there is a problem that heat dissipation must be sacrificed.

  Then, an object of this invention is to provide the envelope for microwave power elements which can improve heat dissipation, a microwave power element, and those manufacturing methods.

  An envelope for a microwave power device of the present invention includes a ceramic frame with leads, and a metal base plate made of any one of Cu, Cu-diamond composite material, and Al-diamond composite material, wherein the lead The attached ceramic frame is hermetically bonded to the metal base plate with low temperature sintering metal particles.

  The microwave power element of the present invention is characterized in that a semiconductor element is mounted on the envelope for the microwave power element.

  A method for manufacturing an envelope for a microwave power element according to the present invention includes a leaded ceramic frame and a metal base plate made of any one of Cu, Cu-diamond composite material, and Al-diamond composite material. A method for manufacturing an envelope for a microwave power element, the step of disposing the lead-attached ceramic frame on a pattern including low-temperature sinterable metal particles formed on the metal base plate, and the metal particles And a step of sintering.

  A method of manufacturing a microwave power device according to the present invention includes an envelope including a leaded ceramic frame and a metal base plate made of any one of Cu, Cu-diamond composite material, and Al-diamond composite material. A method of manufacturing a microwave power device for mounting a semiconductor device, wherein the ceramic frame with leads and the semiconductor device are arranged on a pattern including low-temperature sinterable metal particles formed on the metal base plate. And a step of sintering the metal particles.

  According to the present invention, a metal base plate formed of any one of Cu, Cu-diamond composite material, and Al-diamond composite material and a ceramic frame are made of paste containing low-temperature sinterable metal particles. The heat dissipation can be improved by airtight joining.

1 is an external view of a microwave power device according to a first embodiment of the present invention. 1 is an external view of an envelope for a microwave power element according to a first embodiment of the present invention. It is a flowchart which shows an example of the manufacturing method of the microwave power element which concerns on 1st Embodiment of this invention. It is an external view explaining S1 step in the manufacturing method shown in FIG. It is an external view explaining S2 step in the manufacturing method shown in FIG. It is an external view explaining S4 step in the manufacturing method shown in FIG. It is an external view explaining S5 step in the manufacturing method shown in FIG. It is an external view explaining S6 step in the manufacturing method shown in FIG. It is a flowchart which shows an example of the manufacturing method of the microwave power element which concerns on 2nd Embodiment of this invention. It is an external view explaining S11 step in the manufacturing method shown in FIG. It is an external view explaining S12 step in the manufacturing method shown in FIG. It is an external view explaining S14 step in the manufacturing method shown in FIG. It is sectional drawing explaining an example of the manufacturing method of the microwave power element which concerns on the modification of 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1. First embodiment (overall configuration)
As an example of the microwave power element according to the present embodiment, there is an internal matching type microwave power element 1 including the internal matching circuit element shown in FIG.

  A microwave power element 1 shown in FIG. 1 includes an envelope 2. The envelope 2 is formed of a ceramic frame 12 with leads and a metal base plate 13. In the leaded ceramic frame 12, a semiconductor chip 15 as a semiconductor element, an input side distributed constant circuit board 16 and an output side distributed constant circuit board 17 as internal matching circuit elements, a chip capacitor 18 as a lumped constant element, and Is arranged.

  The input-side distributed constant circuit board 16 is an alumina substrate that is disposed on the input side with respect to the semiconductor chip 15 and has a distributed constant circuit formed thereon. The output-side distributed constant circuit board 17 is an alumina substrate that is disposed on the output side with respect to the semiconductor chip 15 and on which a distributed constant circuit is formed.

  As the semiconductor chip 15, Si-based LDMOS (Laterally Diffused Metal Oxide Semiconductor, lateral diffusion MOS) capable of high output operation, GaAs-based FET (Field effect transistor), GaN-based HEMT (High Electron Mobility Transistor), high An electron mobility transistor) is used.

  As shown in FIG. 2, the envelope 2 is provided with a ceramic frame 12 with leads on a metal base plate 13. The lead-attached ceramic frame 12 includes a ceramic frame 12a and leads 12b. The ceramic frame 12a is configured by a frame-shaped member that partitions a space into a rectangular shape and surrounds the space. The ceramic frame 12a can be formed of alumina, zirconia, silicon nitride, or the like, for example. Leads 12b are provided on opposite sides of the ceramic frame 12a.

  The metal base plate 13 is formed of any one of Cu, Cu-diamond composite material, and Al-diamond composite material. The metal-diamond composite material is manufactured by an impregnation method or a powder metallurgy method.

  As an example, a Cu-diamond composite material can be produced by compositing Cu powder and diamond particles, for example, under high temperature and pressure. In the Cu-diamond composite material, a fine composite material is obtained by mixing Cu powder having an average particle diameter of 10 μm and diamond particles of # 30/40 with a composition of about Cu-60 vol% and press-molding at a temperature equal to or higher than the melting temperature of Cu. Can be produced.

  As an example, an Al-diamond composite material can be manufactured by impregnating diamond powder with molten Al at high temperature and high pressure. The diamond powder preferably has an average particle size of 100 μm, and the diamond particle content is selected in the range of 40 vol% to 70 vol%.

  The composition ratios of these composite materials differ in thermal conductivity and thermal expansion coefficient. However, the difference in thermal expansion coefficient between the ceramic and the composite material is not a problem in low-temperature bonding at 200 to 300 ° C. Selection becomes easy.

  The lead-equipped ceramic frame 12a and the metal base plate 13 are hermetically bonded by sintering low-temperature sinterable metal particles. As the metal particles, metal particles having a sintering temperature of about 200 to 300 ° C., for example, Ag particles, Cu particles, and Ni particles can be used. For example, when Ag particles are used as the metal particles, it is preferably a mixture of micron-order Ag particles having a particle size of 300 nm to 2 μm and nano-order Ag particles having a particle size of 1 nm to 100 nm. The nano-order Ag particles contained in the metal particles are preferably 30 mass% or more.

  The semiconductor chip 15, the input side distributed constant circuit board 16, the output side distributed constant circuit board 17, and the chip capacitor 18 are hermetically bonded onto the metal base plate 13 by sintering the metal particles.

  It is preferable that an Au film or an Ag film is formed on the bonding surface where the metal particles are sintered and bonded. In this case, an Au film or an Ag film is formed on each bonding surface of the leaded ceramic frame 12a, the metal base plate 13, the semiconductor chip 15, the input side distributed constant circuit board 16, the output side distributed constant circuit board 17, and the chip capacitor 18. A film is preferably formed.

(Production method)
A method for manufacturing the microwave power device 1 according to the present embodiment will be described with reference to the drawings. In the manufacturing method according to the present embodiment, after forming the envelope 2, the microwave power element 1 is manufactured by mounting a semiconductor element. First, the envelope 2 is formed in steps S1 to S4 in FIG.

  In step S1, a frame pattern 19a is formed on the metal base plate 13 using a paste (FIG. 4). The paste includes the metal particles and a solvent. As the solvent, for example, alcohols such as decanol and octanediol can be used. In order for the metal particles to be dispersed in the solvent, it must be coated with an organic substance. The organic coating is preferably a fatty acid or an alcohol derivative. The viscosity of the paste is adjusted from 70 PaS to 230 PaS.

  When Ag particles are used as the metal particles, for example, Applied Nanoparticles Laboratory (product name: Arconano silver paste, average particle diameter of Ag nanoparticles: 1 nm to 100 nm (35 mass% or more), average particle diameter of Ag fine particles : 300 nm to 2 μm (60 mass%), thickener: isobornylcyclohexanol, solvent: decanol).

  The frame pattern 19a is an area to be joined on the metal base plate 13 to which the leaded ceramic frame 12 is joined. The frame pattern 19a can be formed by a method such as screen printing or dispense printing. The frame pattern 19a can also be formed by a method such as gravure printing.

  The frame pattern 19a preferably has a thickness of 10 to 50 μm. The pattern forming method and the pattern thickness are the same in step S5 described later and step S11 in FIG.

  In step S2, the ceramic frame 12 with leads is disposed on the frame pattern 19a (FIG. 5). Next, in step S3, heat treatment (dry baking) for volatilizing the solvent of the paste is performed. The solvent is volatilized by dry baking at 100 to 120 ° C. for about 5 minutes.

  Next, in step S4, a heat treatment for sintering the metal particles is performed. When Ag particles are used as the metal particles, the sintering temperature (heat treatment temperature) is 200 to 300 ° C., although it varies depending on the product. At this time, as shown in FIG. 6, the ceramic frame 12 a may be pressed against the metal base plate 13. By pressing, the metal particles are densely sintered. As a result, the ceramic frame 12a and the metal base plate 13 are joined with high airtightness. When the ceramic frame 12a is pressed at a pressure of 10 MPa or more, the ceramic frame 12a and the metal base plate 13 can be joined at a good level at which He does not leak. In this way, the envelope 2 can be manufactured.

  Next, in step S5, a semiconductor element pattern 19b is formed on the metal base plate 13 using a paste (FIG. 7). The semiconductor element pattern 19b is a region to be bonded on the metal base plate 13 where the semiconductor chip 15, the input side distributed constant circuit substrate 16, the output side distributed constant circuit substrate 17, and the chip capacitor 18 shown in FIG. is there.

  In step S6, the semiconductor chip 15, the input side distributed constant circuit board 16, the output side distributed constant circuit board 17, and the chip capacitor 18 are disposed on the semiconductor element pattern 19b (FIG. 8).

  In step S7, heat treatment (dry baking) for volatilizing the solvent contained in the paste is performed. The solvent is volatilized by dry baking at 100 to 120 ° C. for about 5 minutes.

  Next, in step S8, heat treatment for sintering the metal particles is performed. The sintering temperature (heat treatment temperature) of the metal particles is 200 to 300 ° C. as in step S4.

  In step S9, each component is wired and connected. Wiring is connected by ultrasonic thermocompression bonding using Au wire or Al wire. Next, sealing is performed in step S10. Sealing is performed, for example, by bonding a ceramic cap (not shown) to the ceramic frame 12 with leads using AuSn eutectic solder. In this case, it is preferable that an Au film or an Ag film is formed on the bonding surface between the leaded ceramic frame 12 and the ceramic cap. A ceramic cap may be bonded to the leaded ceramic frame 12 with a resin. In this case, it is not necessary to form an Au film or an Ag film on the bonding surface. As described above, the microwave power element 1 can be manufactured.

(Function and effect)
The envelope 2 includes a metal base plate 13 formed of any one of Cu, Cu-diamond composite material, and Al-diamond composite material, and a ceramic frame 12a, including low-temperature sinterable metal particles. The heat dissipation can be improved by airtight joining with the paste.

  In the present embodiment, since metal particles having a sintering temperature of 200 to 300 ° C. are used, the heat treatment temperature is 200 to 300 ° C. which is extremely lower than that in the case of conventional silver brazing (800 ° C.). Then, the envelope 2 can reduce the stress generated due to the difference in thermal expansion coefficient between the ceramic frame 12a and the metal base plate 13. Therefore, the envelope 2 can form the metal base plate 13 with Cu or a composite material containing Cu having high thermal conductivity at low cost.

  In addition, since the heat treatment temperature is low, the metal base plate 13 can be formed of a Cu-diamond composite material that is conventionally insufficient in heat resistance, such as segregation in a high temperature heat treatment. Since the Cu-diamond composite material has extremely high thermal conductivity (600 W / mK), the heat dissipation of the envelope 2 can be further improved.

  Moreover, since the Al-diamond composite material has the same thermal conductivity as the Cu-diamond composite material, the same effect can be obtained with respect to the heat dissipation of the envelope 2.

  By mounting a semiconductor element on the envelope 2 having high heat dissipation as described above, a microwave power element with improved heat dissipation can be obtained.

2. Second Embodiment Since the envelope and the microwave power element according to the present embodiment have the same configurations as those of the first embodiment, description thereof is omitted. This embodiment is different from the first embodiment only in the manufacturing method. That is, the present embodiment is different from the first embodiment in that the ceramic frame 12a with leads and the metal base plate 13 are joined together and the semiconductor element is mounted at the same time.

  In step S11 of FIG. 9, the frame pattern 19a and the semiconductor element pattern 19b are formed on the metal base plate 13 using the paste by the same method as in the first embodiment (FIG. 10). The frame pattern 19a is a region to be joined on the metal base plate 13 to which the leaded ceramic frame 12 shown in FIG. 2 is joined. The semiconductor element pattern 19b is a region to be bonded on the metal base plate 13 where the semiconductor chip 15, the input side distributed constant circuit substrate 16, the output side distributed constant circuit substrate 17, and the chip capacitor 18 shown in FIG. is there.

  Next, in step S12, the ceramic frame 12 with leads is disposed on the frame pattern 19a. At the same time, the semiconductor chip 15, the input side distributed constant circuit board 16, the output side distributed constant circuit board 17, and the chip capacitor 18 are arranged on the semiconductor element pattern 19b (FIG. 11).

  In step S13, heat treatment (dry baking) for volatilizing the solvent of the paste is performed. The solvent is volatilized by dry baking at 100 to 120 ° C. for about 5 minutes.

  Next, in step S14, a heat treatment for sintering the metal particles is performed in the same manner as in the first embodiment. At this time, as shown in FIG. 12, the ceramic frame 12a may be pressurized.

  Steps S15 and S16 are the same as steps S9 and S10 shown in FIG.

(Function and effect)
The envelope 2 includes a metal base plate 13 formed of any one of Cu, Cu-diamond composite material, and Al-diamond composite material, and a ceramic frame 12a, including low-temperature sinterable metal particles. Since the hermetic joining is performed with the paste, the same effect as in the first embodiment can be obtained.

  Furthermore, in the case of this embodiment, since the heat treatment temperature is low, the bonding of the leaded ceramic frame 12a and the metal base plate 13 and the mounting of the semiconductor element can be performed at the same time. Can be manufactured in a simple process.

  Ag particles as metal particles have high thermal conductivity (420 W / mK) among metals. Therefore, it is possible to form a bonding layer with extremely good heat dissipation as compared with the case of bonding using AuSn eutectic solder (Au 80%) having a conventional thermal conductivity of 57 W / mK.

(Modification)
FIG. 13 is a cross-sectional view showing a case where the semiconductor chip 15, the input side distributed constant circuit board 16, the output side distributed constant circuit board 17, and the chip capacitor 18 are pressed in addition to the pressurization of the ceramic frame 12 a. By inserting a spring 21 into the pressurizing body 20 that pressurizes the ceramic frame 12a, the pressurizing body 22 can press the semiconductor chip 15 and the like. As described above, since the Ag nanoparticles become a dense Ag sintered layer by pressurization, a joint having high migration resistance and high stress resistance can be formed.

3. The present invention is not limited to the above-described embodiment, and can be appropriately changed within the scope of the gist of the present invention.

  In the case of the above embodiment, a case where the semiconductor element mounted on the microwave power element 1 includes the semiconductor chip 15, the input side distributed constant circuit board 16, the output side distributed constant circuit board 17, and the chip capacitor 18 will be described. However, the present invention is not limited to this. For example, the input side may be composed of only the chip capacitor 18. A microwave power element having a maximum of 240 W (L band to S band) is commercially available as a microwave power element similar to this configuration. Note that the internal matching circuit elements (the input-side distributed constant circuit board 16 and the output-side distributed constant circuit board 17) are not mounted on the microwave power element having a small output of about several W, and thus the envelope is small.

DESCRIPTION OF SYMBOLS 1 Microwave power element 2 Envelope 12 Ceramic frame 12a with lead | read | reed Ceramic frame 12b Lead | read | reed 13 Metal base board 15 Semiconductor chip 16 Input side distributed constant circuit board 17 Output side distributed constant circuit board 18 Chip capacitor 19a Frame pattern 19b Semiconductor element pattern 20, 22 Pressurizing body 21 Spring

Claims (10)

A ceramic frame with leads,
An envelope for a microwave power device comprising a metal base plate made of any one of Cu, Cu-diamond composite material, and Al-diamond composite material,
An envelope for a microwave power element, wherein the ceramic frame with leads is hermetically bonded to the metal base plate with low-temperature sintering metal particles. The envelope for a microwave power device according to claim 1, wherein the metal particles are Ag particles. A microwave power element, wherein a semiconductor element is mounted on the microwave power element envelope according to claim 1. A ceramic frame with leads,
A method for manufacturing an envelope for a microwave power device comprising a metal base plate made of any one of Cu, Cu-diamond composite material and Al-diamond composite material,
Disposing the ceramic frame with leads on a pattern including low-temperature sinterable metal particles formed on the metal base plate;
And a step of sintering the metal particles. A method of manufacturing an envelope for a microwave power element. 5. The method for manufacturing an envelope for a microwave power device according to claim 4, wherein the metal particles are Ag particles. 6. The method for manufacturing an envelope for a microwave power device according to claim 4, wherein in the step of sintering the metal particles, the ceramic frame with leads is pressed against the metal base plate. A ceramic frame with leads,
A method of manufacturing a microwave power device in which a semiconductor device is mounted on an envelope including a metal base plate made of any one of Cu, Cu-diamond composite material, and Al-diamond composite material,
Placing the leaded ceramic frame and the semiconductor element on a pattern including low-temperature sinterable metal particles formed on the metal base plate;
And a step of sintering the metal particles. A method of manufacturing a microwave power device. The method for manufacturing a microwave power device according to claim 7, wherein the metal particles are Ag particles. 9. The method of manufacturing a microwave power device according to claim 7, wherein in the step of sintering the metal particles, the ceramic frame with leads is pressed against the metal base plate. The method for manufacturing a microwave power device according to claim 9, further comprising pressurizing the semiconductor device against the metal base plate.

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