Millimeter wave chip packaging structure based on substrate integrated waveguide and artificial magnetic conductor

Abstract

The utility model discloses a millimeter wave chip packaging structure based on a substrate integrated waveguide and an artificial magnetic conductor, which relates to the technical field of millimeter wave chip packaging, and comprises a chip, a cover plate and a base, the cover plate is in sealing fit with the base, the chip is arranged in the base, and the cover plate comprises a metal flat plate and a plurality of metal columns connected below the metal flat plate and distributed in an array. The metal column is not contacted with the base; the base comprises a frame, an SIW substrate, a direct current feed terminal and a heat sink, a first groove is formed in the center of the upper surface of the heat sink, and second grooves are formed in the two sides of the first groove and communicated with the first groove. According to the utility model, the SIW substrate is adopted to replace a traditional strip line terminal to serve as the millimeter wave input end and the millimeter wave output end of the shell, and the conductive materials on the upper surface and the lower surface of the SIW substrate are titanium tungsten / nickel / gold in sequence, so that the structure is simple, the processing technology is simple, the assembly technology is simple, the price is low, and the like; and the cable also has the advantages of wide working frequency band, large bearing power, small reflection loss, small transmission loss and the like, and also has the advantages of static electricity prevention and lightning protection.

Description

Technical Field

[0001] The utility model relates to the technical field of millimeter wave chip packaging, in particular to a millimeter wave chip packaging structure based on substrate integrated waveguide and artificial magnetic conductor. Background Art

[0002] Human society has entered an era of informatization and intelligence. Chips, software, big data and artificial intelligence are the material basis of our era. Millimeter wave technology has been widely used in communications, radar, electronic countermeasures, scientific research and other fields, which is inseparable from the rapid development of millimeter wave MMIC chips and millimeter wave MEMS chips.

[0003] In the process of manufacturing and using electronic products, chips cannot be exposed to the air for a long time. In order to improve the environmental adaptability of the product, various shells need to be used to seal the chip. The package shell can provide mechanical support, electrical path, thermal path and airtight environment for the chip, and is an important bridge connecting the internal chip with the external circuit. Low-power chips working in shortwave / ultra-shortwave, decimeter wave bands and centimeter wave bands can use standard package shells such as CFP, QFP, QFN, BGA, etc., and high-power chips can use metal ceramic package shells. However, these package shells are difficult to apply to millimeter wave chips due to large reflection loss and large transmission loss.

[0004] Currently, in millimeter wave circuits and systems, standard rectangular waveguides are generally used to interconnect modules, modules and feeders, and feeders and antennas. In order to prevent salt spray, mold, water vapor and dust from entering the module through the waveguide port, the millimeter wave chip inside the module is usually sealed in the following four ways:

[0005] The first is to use waveguide-coaxial-microstrip conversion, and weld the coaxial insulator into the fixed hole of the module shell for sealing. The millimeter wave chip and the microstrip circuit substrate are interconnected by gold wire bonding. The microstrip circuit substrate and one end of the coaxial insulator are welded with metal alloy solder to form an electrical connection. The other end of the coaxial insulator forms a dipole antenna inserted in the middle of the H-plane of the rectangular waveguide. The main electromagnetic wave transmission mode of the millimeter wave chip and the microstrip circuit substrate is the quasi-TEM mode, and the port characteristic impedance is generally 50Ω; the main electromagnetic wave transmission mode of the rectangular waveguide is the TE10 mode, and the wave impedance is 376.62Ω; the main electromagnetic wave transmission mode of the coaxial insulator is the pure TEM mode, and the coaxial insulator plays the role of impedance matching and mode conversion. This method has very high requirements on the processing accuracy and assembly accuracy of materials, especially in the millimeter wave high frequency band (for example, the millimeter wave W band, the frequency increases, the wavelength decreases, the corresponding device size is also decreasing, and the influence of processing errors and assembly errors on device characteristics is becoming more and more significant). The cost is high and the yield rate is low. In particular, coaxial insulators are prone to solder overflow, solder splashing, solder crystallization, solder void bubbles, solder wetting angle, solder plugging holes, coaxial insulator skew and bias, hole misalignment, hole plating blistering and shedding, microstrip line solder accumulation and other problems during the welding process.

[0006] The second is to use waveguide-microstrip conversion, and cover the waveguide mouth with the H-surface probe of the microstrip circuit substrate to seal it. The H-surface probe of the microstrip circuit substrate replaces the coaxial insulator, forms a dipole antenna in the waveguide, and radiates electromagnetic waves to the waveguide. The electromagnetic wave produces total reflection on the waveguide short-circuit surface. The place where the distance from the waveguide short-circuit surface is an odd multiple of a quarter of the wavelength is the peak of the electromagnetic field, that is, the place where the electric field intensity is the largest, which is consistent with the electric field distribution of the waveguide TE10 mode to be excited. Inserting the H-surface probe here has the highest coupling efficiency. This method has three disadvantages: First, there must be grooves around the waveguide mouth to install and fix the microstrip circuit substrate. If the groove is small, it will lead to poor sealing effect. If the groove is large, it will cause electromagnetic wave resonance, making it difficult to achieve full-band operation of the waveguide. Second, in the process of welding the microstrip circuit substrate to the grooves around the waveguide mouth, due to insufficient processing accuracy, insufficient assembly accuracy, solder diffusion and other reasons, the microstrip circuit substrate is not completely attached to the module housing on the side of the waveguide short-circuit surface, which will also cause electromagnetic wave resonance, making it difficult to achieve full-band operation of the waveguide. Third, the input and output waveguides of the module face downward, and the heat generated by the normal operation of the chip is difficult to be directly transferred to the air-cooled radiator or liquid-cooled radiator through the module shell. Therefore, this method is difficult to seal the third-generation wide bandgap semiconductor materials (SiC and GaN that have been widely used) and the fourth-generation wide bandgap semiconductor materials (AlN, GaN that are being rapidly developed). 2 O 3 and Diamond) with wide-band, high-power millimeter-wave chips.

[0007] The third method is to use a waveguide sealing window, and use ceramic metallization and brazing processes to weld dielectric sheets such as alumina, sapphire or diamond to the waveguide window to make a waveguide sealing window, and then use low-temperature solder or laser sealing welding machine to weld the waveguide sealing window to the input and output waveguide ports of the module. This method is very expensive, especially the manufacture of waveguide sealing windows requires a special vacuum brazing furnace or hydrogen brazing furnace and professional process technicians. At present, only a few state-owned enterprises and universities that make microwave vacuum electronic devices in China have such supporting facilities. Therefore, this method is not suitable for the research and development and production of multi-variety and small-batch military products, especially small and medium-sized private enterprises.

[0008] Fourth, MEMS bulk silicon packaging is used. Through processes such as lithography, etching, through-silicon vias (TSV), through-hole metallization, electroplating, chip sintering, gold wire bonding, wafer stacking, wafer bonding, capping, and dicing, the millimeter-wave MMIC chip is packaged in a multi-layer silicon substrate, and it is easy to integrate with the millimeter-wave MEMS chip. Different from traditional thick film processes such as multi-layer printed circuit boards (PCBs), low-temperature co-fired ceramics (LTCC) and high-temperature co-fired ceramics (HTCC), MEMS bulk silicon packaging enables the product to have the advantages of high processing accuracy, high assembly accuracy, and good batch consistency. The cost of this method is also very high. At present, only a few state-owned enterprises in China that make microwave solid-state electronic devices have this supporting system. Therefore, this method is not suitable for the research and development and production of military products with multiple varieties and small batches, especially small and medium-sized private enterprises. This method is prone to problems such as cavity resonance and insufficient heat dissipation, and is not suitable for sealing wide-band, high-power millimeter-wave chips.

[0009] To this end, a millimeter-wave chip packaging structure based on substrate integrated waveguide and artificial magnetic conductor is proposed. Utility Model Content

[0010] The main purpose of the utility model is to provide a millimeter wave chip packaging structure based on substrate integrated waveguide and artificial magnetic conductor, which can effectively solve the problems in the background technology.

[0011] To achieve the above-mentioned purpose, the utility model provides a millimeter wave chip packaging structure based on substrate integrated waveguide and artificial magnetic conductor, comprising a chip, a cover plate and a base, wherein the cover plate is sealed and matched with the base, the chip is placed in the base, the cover plate comprises a metal plate, and a plurality of metal columns connected to the bottom of the metal plate and distributed in an array, wherein the metal columns are not in contact with the base; the base comprises a frame, an SIW substrate, a DC feeding terminal and a heat sink, a first groove is provided in the center of the upper surface of the heat sink, second grooves are provided on both sides of the first groove and communicated with the first groove, the DC feeding terminal is provided at both ends of the first groove, the SIW substrate is provided in the second grooves on both sides of the first groove, and the frame is connected to the upper surface of the heat sink; the chip is connected to the first groove of the heat sink through a carrier, and the chip is connected to the SIW substrate and the DC feeding terminal.

[0012] According to one embodiment of the present invention, the cross section of the metal column is square.

[0013] According to an embodiment of the utility model, a 50Ω microstrip line and a tapered microstrip line are respectively provided on both sides of the surface of the SIW substrate, the 50Ω microstrip line and the tapered microstrip line are connected, and metal-filled grounding vias are provided on the other two sides of the surface of the SIW substrate.

[0014] According to one embodiment of the utility model, the cover plate is integrally formed by metal powder injection molding using 4J29 Kovar alloy, and the thermal conductivity of the 4J29 Kovar alloy is 16.4W / mK, the specific heat capacity is 460J / Kg.K, the thermal expansion coefficient is 7.85ppm / ℃, the elastic modulus is 170GPa, and the Poisson's ratio is 0.27.

[0015] According to one embodiment of the present invention, the heat sink is integrally formed by metal powder injection using tungsten / copper, molybdenum / copper, diamond / copper or silicon carbide / aluminum composite materials.

[0016] According to one embodiment of the utility model, the frame is made of 4J29 Kovar alloy by mechanical processing or electric spark wire cutting.

[0017] According to one embodiment of the utility model, the SIW substrate adopts a double-sided ground and polished white alumina ceramic substrate, the adhesion layer material is TiW, the barrier layer material is Ni, and the conductive layer material is Au. The purity of the white alumina ceramic substrate is 99.6%, the material density is 3.88g / cm3, the surface roughness is less than 0.03um, the dielectric constant is 9.9, the dielectric loss tangent value is 0.0001, the thermal conductivity is greater than 29.3W / , and the thermal expansion coefficient is less than 7.0ppm / ℃.

[0018] According to one embodiment of the utility model, the DC feed terminal adopts HTCC multilayer white alumina ceramic with a purity of 95%, whose thermal conductivity is 25W / mK, specific heat capacity is 795J / Kg.K, thermal expansion coefficient is 7.7ppm / ℃, elastic modulus is 304GPa, and Poisson's ratio is 0.27.

[0019] Compared with the prior art, the utility model has the following beneficial effects:

[0020] 1. The utility model adopts a SIW substrate instead of a traditional stripline terminal as the millimeter wave input and output ends of the housing base. The conductive materials on the upper and lower surfaces of the SIW substrate are titanium tungsten / nickel / gold respectively. It has the advantages of simple structure, simple processing technology, simple assembly technology, low price, etc., as well as wide working frequency band (can cover millimeter wave K band, millimeter wave Ka band, millimeter wave Q band, millimeter wave U band, millimeter wave V band, millimeter wave E band or millimeter wave W band), high power bearing, small reflection loss, small transmission loss, etc., and also has the advantages of anti-static and lightning protection (substrate integrated waveguide has the natural advantage of DC short circuit to ground, which can prevent static electricity discharge and lightning strikes on the human body).

[0021] 2. The present invention is not only applicable to millimeter wave equipment (K band, Ka band, Q band, U band, V band, E band and W band), but also to airborne / missile-borne / satellite-borne centimeter wave equipment (C band, X band and Ku band) that has requirements on size, weight, airtightness, electromagnetic compatibility, etc.

[0022] 3. The utility model uses the design of metal plates and metal columns to form a sealed fit between the cover and the base, thereby protecting the chip from the influence of the external environment. Secondly, the synergy of components such as the frame, SIW substrate, DC feed terminal and heat sink not only provides a stable heat conduction path for the chip, but also facilitates the electrical connection between the chip and the external circuit. In addition, the use of a carrier to connect the chip to these components effectively improves the stability and performance of the entire packaging structure, thereby meeting the application requirements of millimeter wave chips in harsh environments such as high temperature and high frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0024] Figure 2 This is a schematic diagram of the split structure of the utility model;

[0025] Figure 3 This is a three-dimensional assembly diagram of the utility model;

[0026] Figure 4 This is an explosion diagram of the utility model;

[0027] Figure 5 This is a schematic diagram of the structure of the SIW substrate of the utility model;

[0028] Figure 6 This is the S parameter simulation curve of the millimeter wave K-band SIW substrate of the utility model;

[0029] Figure 7 This is the characteristic impedance simulation curve of the 32-port SIW substrate of the millimeter wave K-band of the utility model;

[0030] Figure 8 This is the electric field intensity distribution cloud diagram of the millimeter wave K-band SIW substrate of the utility model;

[0031] Fig. 9 This is a cloud diagram of magnetic induction intensity distribution of the millimeter wave K-band SIW substrate of the utility model;

[0032] Fig.10 This is the S parameter simulation curve of the millimeter wave Ka-band SIW substrate of the utility model;

[0033] Fig.11 This is the simulation curve of the characteristic impedance of the millimeter-wave Ka-band SIW substrate port of the utility model;

[0034] Fig.12 This is a cloud diagram of the electric field intensity distribution of the millimeter wave Ka-band SIW substrate of the utility model;

[0035] Fig.13 This is a cloud diagram of magnetic induction intensity distribution of the millimeter wave Ka-band SIW substrate of the utility model;

[0036] Fig.14 It is a three-dimensional electromagnetic model of the millimeter wave K-band chip packaging shell of the utility model;

[0037] Fig.15 It is a cloud diagram simulation of the cavity resonance electric field intensity distribution of the millimeter wave K-band chip package shell of the utility model;

[0038] Fig.16 It is a three-dimensional electromagnetic model of the millimeter wave Ka-band chip packaging shell of the utility model;

[0039] Fig.17 It is a cloud diagram simulation of the cavity resonance electric field intensity distribution of the millimeter wave Ka-band chip package shell of the utility model;

[0040] Fig.18 It is a three-dimensional model of the artificial magnetic conductor AMC of the utility model;

[0041] Fig.19 A three-dimensional electromagnetic model of the millimeter wave K-band chip package housing loaded with AMC for the utility model;

[0042] Fig. 20 The electric field intensity distribution cloud map simulation of the millimeter wave K-band chip package shell loaded with AMC for the utility model;

[0043] Fig.21 The S parameter simulation curve of the millimeter wave K-band chip package shell loaded with AMC of the utility model;

[0044] Fig. 22The port characteristic impedance simulation curve of the millimeter wave K-band chip package shell loaded with AMC of the utility model;

[0045] Fig.23 A three-dimensional electromagnetic model of the millimeter wave Ka-band package housing loaded with AMC for the utility model;

[0046] Fig.24 The electric field intensity distribution cloud diagram simulation of the millimeter wave Ka-band package shell loaded with AMC for the utility model;

[0047] Fig.25 The S parameter simulation curve of the millimeter wave Ka-band package shell loaded with AMC of the utility model;

[0048] Fig.26 This is a port characteristic impedance simulation curve of the millimeter wave Ka-band package shell loaded with AMC of the utility model.

[0049] Parts and numbers in the picture:

[0050] 1-chip; 2-cover plate; 3-base; 4-carrier; 21-metal plate; 22-metal column; 31-frame; 32-SIW substrate; 33-DC feed terminal; 34-heat sink; 341-first groove; 342-second groove. DETAILED DESCRIPTION

[0051] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but is not intended to limit the present invention. Any technical solution based on the transformation or inference of the present invention falls within the protection scope of the present invention.

[0052] Embodiment 1

[0053] like Figure 1-2 As shown, the technical solution adopted by the utility model is: a millimeter wave chip packaging structure based on substrate integrated waveguide and artificial magnetic conductor, including a chip 1, a cover plate 2 and a base 3, the cover plate 2 and the base 3 are sealed, the chip 1 is placed in the base 3, the cover plate 2 includes a metal plate 21, and a plurality of metal pillars 22 connected to the bottom of the metal plate 21 and distributed in an array, and the metal pillars 22 are not in contact with the base 3; the base 3 includes a frame 31, an SIW substrate 32, a DC feeding terminal 33 and a heat sink 34, a first groove 341 is opened in the center of the upper surface of the heat sink 34, and second grooves 342 are opened on both sides of the first groove 341 to communicate with the first groove 341, the DC feeding terminal 33 is arranged at both ends of the first groove 341, the SIW substrate 32 is arranged in the second grooves 342 on both sides of the first groove 341, and the frame 31 is connected to the upper surface of the heat sink 34; the chip 1 is connected to the first groove 341 of the heat sink 34 through the carrier 4, and the chip 1 is connected to the SIW substrate 32 and the DC feeding terminal 33.

[0054] The utility model is mainly composed of a cover plate 2 and a base 3. Figure 2 As shown. The chip 1 and the carrier 4 are made of preformed Au 80 Sn 20 Gold-tin alloy solder sheet (melting point 280°C) is used for eutectic welding. The chip to be sealed 1 is preformed with Sn 96.5 Ag 3 Cu 0.5 Tin-silver-copper alloy solder sheet (melting point 220°C) is welded on the base 3, the chip 1 is interconnected with the SIW substrate 32 and the DC feed terminal 33 by gold wire bonding, and the cover plate 2 and the base 3 are made of preformed Au 80 Sn 20 The gold-tin alloy solder sheet (melting point 280°C) is flip-chip and parallel-seam welded to form a package shell structure.

[0055] Furthermore, the structure of the cover plate 2 has a metal flat plate 21 on one side and metal pillars 22 evenly distributed in an array on the other side. The cross section of the metal pillars 22 is square. The cover plate 2 is made of 4J29 Kovar alloy material and is integrally formed using a metal injection molding (MIM) process. The thermal conductivity of 4J29 Kovar alloy is 16.4W / mK, the specific heat capacity is 460J / Kg.K, the thermal expansion coefficient is 7.85ppm / ℃, the elastic modulus is 170GPa, and the Poisson's ratio is 0.27.

[0056] Further, such as Figure 3 , 4 As shown, the base 3 includes a frame 31, a SIW substrate 32, a DC feed terminal 33 and a heat sink 34. The base 3 is positioned and fastened by a fixture. The contact surface between the SIW substrate 32 and the frame 31, the contact surface between the SIW substrate 32 and the heat sink 34, the contact surface between the DC feed terminal 33 and the frame 31, and the contact surface between the DC feed terminal 33 and the heat sink 34 are made of preformed Ag. 72 Cu 28The heat sink 34 is made of tungsten / copper, molybdenum / copper, diamond / copper or silicon carbide / aluminum composite material, and is integrally formed by metal injection molding (MIM). The frame 31 is made of 4J29 Kovar alloy material, and the required dimensions are obtained by mechanical processing or electric spark wire cutting. The SIW substrate 32 is a double-sided polished white alumina ceramic substrate (the adhesion layer material is TiW, the barrier layer material is Ni, and the conductive layer material is Au). The material purity is 99.6%, the material density is 3.88g / cm3, the surface roughness is less than 0.03um, the dielectric constant is 9.9, the dielectric loss tangent is 0.0001, the thermal conductivity is greater than 29.3W / mK, and the thermal expansion coefficient is less than 7.0ppm / ℃. The DC feed terminal 33 is made of HTCC multilayer white alumina ceramic with a purity of 95%, a thermal conductivity of 25W / mK, a specific heat capacity of 795J / Kg.K, a thermal expansion coefficient of 7.7ppm / ℃, an elastic modulus of 304GPa, and a Poisson's ratio of 0.27. The SIW substrate 32 and the DC feed terminal 33 can also be processed by MEMS bulk silicon processes such as photolithography, through-hole reactive ion etching, sputtering, electroplating, and gold-gold bonding.

[0057] Further, such as Figure 5 As shown, a 50Ω microstrip line and a tapered microstrip line are respectively provided on both sides of the surface of the SIW substrate 32 , the 50Ω microstrip line and the tapered microstrip line are connected, and metal-filled grounding vias are provided on the other two sides of the surface of the SIW substrate 32 .

[0058] Substrate Integrated Waveguide (SIW) is a new type of planar waveguide structure evolved from metal cavity rectangular waveguide and dielectric filled rectangular waveguide. The conductive metal layer is covered on the top and bottom of the dielectric substrate, and two rows of periodic metallized conductive through holes arranged in a certain pattern are used as two side walls to form a substrate integrated waveguide. The top conductive metal layer and the bottom conductive metal layer of the substrate integrated waveguide are equivalent to the wide side of the metal cavity rectangular waveguide and the dielectric filled rectangular waveguide. When the spacing between the two rows of periodic metallized conductive through holes is small enough, the electromagnetic waves leaking from the through hole gap are so small that they can be ignored. At this time, the two rows of periodic metallized conductive through holes are equivalent to the narrow side of the metal cavity rectangular waveguide and the dielectric filled rectangular waveguide. The discontinuity of the inner wall of the narrow side cuts off the longitudinal current of the inner wall, so that the inner wall of the substrate integrated waveguide will not generate a transverse magnetic field. From the electromagnetic field distribution characteristics of the TM mode and the TE mode, it can be seen that the characteristic of the TM mode is that it has a transverse magnetic field, and the TM mode cannot be transmitted in the substrate integrated waveguide. Therefore, the substrate integrated waveguide has similar transmission characteristics to the metal cavity rectangular waveguide and dielectric filled rectangular waveguide, and the main mode of the transmitted electromagnetic wave is TE 10mode, but the working frequency band of the main mode is wider than that of the metal cavity rectangular waveguide and the dielectric filled rectangular waveguide. The disadvantages of the metal cavity rectangular waveguide and the dielectric filled rectangular waveguide are that they are large and heavy, which is not conducive to the integration of circuits and systems and low-cost mass production. Substrate integrated waveguide can take into account the advantages of microstrip lines and rectangular waveguides. It can be planarized and integrated with microstrip lines using printed circuit boards (PCBs), low-temperature co-fired ceramics (LTCC), high-temperature co-fired ceramics (HTCC), ceramic thin film circuits, high-resistance silicon MEMS thin film circuits and other processes. The main mode of electromagnetic wave propagation in SIW is TE 10 Mode, the main mode of electromagnetic wave propagation in 50Ω microstrip line is quasi-TEM mode, the cross-sectional electric field distributions of these two modes are similar, and a low insertion loss matching connection can be achieved through a section of tapered microstrip line.

[0059] Embodiment 2

[0060] The utility model is based on a millimeter wave chip packaging structure of substrate integrated waveguide and artificial magnetic conductor, and adopts SIW substrate 32 to replace the traditional stripline terminal as the millimeter wave input terminal and millimeter wave output terminal of the housing base, eliminating the processes of HTCC multilayer alumina ceramic casting, blanking, punching, hole filling, printing, lamination, hot cutting, sintering, etc. The conductive material of the stripline terminal is tungsten (tungsten and alumina cannot form a good combination. In order to make tungsten and alumina have higher conductivity and higher adhesion strength after co-firing, Y needs to be added to the tungsten powder. 2 O 3 Sintering aid, Al 2 O 3 Ceramic powder, etc., formulated into tungsten conductive slurry, so the resistivity is relatively large), the dielectric material is HTCC liquid phase sintered polycrystalline alumina ceramic (alumina white porcelain with a purity of 95%, which has a large dielectric loss due to the influence of sintering additives in the form of glass phase), which has been widely used in packaging shells below the centimeter wave X band, but the transmission loss of electromagnetic waves above the centimeter wave X band is relatively large and is not applicable. The intermediate layer dielectric material of the SIW substrate 32 can be polished alumina ceramic (purity 99.6%), fused quartz or CVD diamond, and the conductive materials on the upper and lower surfaces of the SIW substrate 32 are titanium tungsten / nickel / gold respectively. It has the advantages of simple structure, simple processing technology, simple assembly technology, low price, etc., as well as wide working frequency band (can cover millimeter wave K band, millimeter wave Ka band, millimeter wave Q band, millimeter wave U band, millimeter wave V band, millimeter wave E band or millimeter wave W band), high power bearing capacity, small reflection loss, small transmission loss, etc., and also has the advantages of anti-static and lightning protection (substrate integrated waveguide has the natural advantage of DC short-circuit to ground, which can prevent static electricity discharge and lightning strikes on the human body).

[0061] The S parameter simulation curve of the SIW substrate 32 in the millimeter wave K band (18 GHz to 26 GHz) is as follows: Figure 6 As shown, the port characteristic impedance simulation curve is as follows Figure 7 As shown. Figure 6 and Figure 7 It can be seen that in the entire millimeter wave K band, the return loss (S11 parameter) is less than -30dB, the insertion loss (S21 parameter) is less than 0.3dB, and the port characteristic impedance is approximately equal to 50Ω.

[0062] The electric field intensity distribution cloud diagram of the SIW substrate 32 in the millimeter wave K band (18 GHz to 26 GHz) is as follows: Figure 8 As shown, the magnetic field intensity distribution cloud diagram is as follows Fig. 9 As shown. Figure 8 and Fig. 9 It can be seen that the electric field and magnetic field are almost all concentrated in the substrate. When an electromagnetic wave with a frequency of 22GHz and a power of 100W is fed into the port, the maximum electric field strength is 6.633×105V / m=6.633V / mm, and the air breakdown electric field strength is about 3000V / mm, which is less than one-third of this value, and can work safely and reliably.

[0063] The S parameter simulation curve of the SIW substrate 32 in the millimeter wave Ka band (26 GHz to 40 GHz) is as follows: Fig.10 As shown, the port characteristic impedance simulation curve is as follows Fig.11 As shown. Fig.10 and Fig.11 It can be seen that in the entire millimeter wave Ka band, the return loss (S11 parameter) is less than -27dB and the insertion loss (S21 parameter) is less than 0.3dB. Figure 7 It can be seen that in the entire millimeter wave Ka band, the port characteristic impedance is approximately equal to 50Ω.

[0064] The electric field intensity distribution cloud diagram of the SIW substrate in the millimeter wave Ka band (26GHz~40GHz) is as follows Fig.12 As shown, the magnetic field intensity distribution cloud diagram is as follows Fig.13 As shown. Fig.12 and Fig.13 It can be seen that the electric field and magnetic field are almost all concentrated in the substrate. When an electromagnetic wave with a frequency of 33GHz and a power of 100W is fed into the port, the maximum electric field strength is 6.371×105V / m=637.1V / mm, and the air breakdown electric field strength is about 3000V / mm, which is less than one-third of this value, and can work safely and reliably.

[0065] When the millimeter wave chip is working normally in the package shell, it is easy to generate self-excitation and oscillation, such as Figure 14-17 As shown. For the millimeter wave K-band chip package, the electromagnetic wave with a frequency of 22.7GHz generates TE101 Mode cavity resonance. For the millimeter wave K-band chip package shell, it is necessary to suppress the electromagnetic wave TE near 22.7GHz 101 Mode cavity resonance. For the millimeter wave Ka band chip package shell, the electromagnetic wave with a frequency of 32.5GHz produces TE 101 Mode cavity resonance. For millimeter wave Ka band chip packaging shell, it is necessary to suppress electromagnetic waves TE near 32.5GHz 101 Mode cavity resonance. The traditional solution is to use epoxy resin glue to stick sheet carbonyl iron absorber material on the inner wall of the cover plate 2 or on the inner wall of the frame 31 to suppress the cavity resonance of electromagnetic waves, but this may bring a certain degree of power loss, deteriorate gain flatness, and increase assembly and debugging time. In addition, the complex magnetic permeability of traditional carbonyl iron absorber materials in the frequency band above about 60GHz is close to 1+j0, reflecting non-magnetic characteristics, and can only rely on dielectric loss to absorb electromagnetic waves. Compared with pure dielectric loss materials, it has no advantage at all, so it is necessary to consider the use of new materials or new structures.

[0066] An infinite perfect electric conductor (PEC) plane and an infinite perfect magnetic conductor (PMC) plane are placed parallel and not in contact. According to the Maxwell equations and boundary conditions, when the distance d between the PEC plane and the PMC plane and the operating wavelength λ satisfy λ>4d, there is no propagation mode in the solution of the wave equation between the two planes, thus forming a frequency bandgap, forming an electromagnetic bandgap (EBG) structure. PMC does not exist in nature, and an artificial magnetic conductor (AMC) can replace PMC. AMC is an artificial electromagnetic structure with a virtual magnetic wall effect on electromagnetic waves. It consists of two metal plates, one of which is loaded with a periodically arranged array of metal pillars 22, such as Fig.18 As shown. When an electromagnetic wave is incident on two metal plates, the entire metal pillar 22 array structure can be equivalent to an LC parallel resonant circuit model composed of inductance and capacitance. When the frequency of the incident electromagnetic wave is close to the resonant frequency of the above equivalent circuit (spacing d = λ / 4), the surface of the metal pillar 22 array exhibits high resistance characteristics. When the frequency of the incident electromagnetic wave is less than the resonant frequency (spacing d ≤ λ / 4), the surface of the metal pillar 22 array exhibits inductive reactance and supports the propagation of TM mode surface waves. When the frequency of the incident electromagnetic wave is greater than the resonant frequency (λ / 4 < d ≤ λ / 2), the surface of the metal pillar array exhibits capacitive reactance and supports the propagation of TE mode surface waves.

[0067] The utility model loads a periodically distributed array of square metal pillars 22 or circular metal pillars 22 on the inner wall of the cover plate 2. In the millimeter wave K band (18GHz to 26GHz), the artificial magnetic conductor square metal pillars 22 have a width of 1.00mm, a height of 4.30mm, a spacing of 1.70mm, and a ground clearance of 0.80mm; in the millimeter wave Ka band (26GHz to 40GHz), the artificial magnetic conductor square metal pillars 22 have a width of 0.70mm, a height of 2.80mm, a spacing of 1.30mm, and a ground clearance of 0.8mm. Figure 19-26 As shown, the equivalent spacing between the cover plate 2 and the base 3 is λ / 4 to form an AMC structure, which can form an electromagnetic band gap for electromagnetic waves within the working frequency band, prevent the electromagnetic wave cavity resonance phenomenon, and help the electromagnetic waves to be concentrated inside the substrate and chip to transmit in a quasi-TEM mode. For the millimeter wave K band (18GHz~26GHz), the low-end frequency of the electromagnetic band gap formed by the AMC structure must be less than 18GHz, and the high-end must be greater than 26GHz. For the millimeter wave Ka band (26GHz~40GHz), the low-end frequency of the electromagnetic band gap formed by the AMC structure must be less than 26GHz, and the high-end must be greater than 40GHz. For other millimeter wave bands, the characteristics of the electromagnetic band gap formed by the AMC structure are similar.

[0068] The utility model eliminates the need for absorbing materials and has the advantages of simple process and low price as well as wide working frequency band (can cover millimeter wave K band, millimeter wave Ka band, millimeter wave Q band, millimeter wave U band), millimeter wave V band, millimeter wave E band or millimeter wave W band), high power bearing capacity, small reflection loss and small transmission loss.

[0069] The above description shows the basic principle and main features of the utility model and the advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments. The above embodiments and the description are only for explaining the principle of the utility model. Without departing from the spirit and scope of the utility model, the utility model may have various changes and improvements, which fall within the scope of the utility model to be protected. The scope of protection of the utility model is defined by the attached claims and their equivalents.

Claims

1. A millimeter wave chip packaging structure based on substrate integrated waveguide and artificial magnetic conductor, comprising a chip (1), a cover plate (2) and a base (3), wherein the cover plate (2) and the base (3) are sealed and matched, and the chip (1) is placed in the base (3), characterized in that: The cover plate (2) comprises a metal flat plate (21) and a plurality of metal columns (22) connected to the bottom of the metal flat plate (21) and distributed in an array, wherein the metal columns (22) are not in contact with the base (3); The base (3) comprises a frame (31), a SIW substrate (32), a DC feeding terminal (33) and a heat sink (34); a first groove (341) is provided in the center of the upper surface of the heat sink (34); second grooves (342) are provided on both sides of the first groove (341) and are connected to the first groove (341); the DC feeding terminal (33) is provided at both ends of the first groove (341); the SIW substrate (32) is provided in the second grooves (342) on both sides of the first groove (341); and the frame (31) is connected to the upper surface of the heat sink (34); The chip (1) is connected to a first groove (341) of a heat sink (34) via a carrier (4), and the chip (1) is connected to a SIW substrate (32) and a DC feed terminal (33).

2. The millimeter wave chip packaging structure based on substrate integrated waveguide and artificial magnetic conductor according to claim 1, characterized in that: The cross section of the metal column (22) is square.

3. The millimeter wave chip packaging structure based on substrate integrated waveguide and artificial magnetic conductor according to claim 1, characterized in that: A 50Ω microstrip line and a tapered microstrip line are respectively provided on two sides of the surface of the SIW substrate (32), the 50Ω microstrip line and the tapered microstrip line are connected, and metal-filled grounding vias are provided on the other two sides of the surface of the SIW substrate (32).

4. The millimeter wave chip packaging structure based on substrate integrated waveguide and artificial magnetic conductor according to any one of claims 1 to 3, characterized in that: The cover plate (2) is formed in one piece by metal powder injection molding using 4J29 Kovar alloy, wherein the thermal conductivity of the 4J29 Kovar alloy is 16.4 W / mK, the specific heat capacity is 460 J / Kg.K, the thermal expansion coefficient is 7.85 ppm / °C, the elastic modulus is 170 GPa, and the Poisson's ratio is 0.

27.

5. The millimeter wave chip packaging structure based on substrate integrated waveguide and artificial magnetic conductor according to any one of claims 1 to 3, characterized in that: The heat sink (34) is formed in one piece by metal powder injection using a tungsten / copper, molybdenum / copper, diamond / copper or silicon carbide / aluminum composite material.

6. The millimeter wave chip packaging structure based on substrate integrated waveguide and artificial magnetic conductor according to any one of claims 1 to 3, characterized in that: The frame (31) is made of 4J29 Kovar alloy by mechanical processing or electric spark wire cutting.

7. The millimeter wave chip packaging structure based on substrate integrated waveguide and artificial magnetic conductor according to any one of claims 1 to 3, characterized in that: The SIW substrate (32) is a double-sided ground and polished white alumina ceramic substrate, the adhesion layer material is TiW, the barrier layer material is Ni, and the conductive layer material is Au. The white alumina ceramic substrate has a purity of 99.6%, a material density of 3.88 g / cm3, a surface roughness of less than 0.03 um, a dielectric constant of 9.9, a dielectric loss tangent of 0.0001, a thermal conductivity greater than 29.3 W / mK, and a thermal expansion coefficient less than 7.0 ppm / °C.

8. The millimeter wave chip packaging structure based on substrate integrated waveguide and artificial magnetic conductor according to any one of claims 1 to 3, characterized in that: The DC feed terminal (33) is made of HTCC multilayer white alumina ceramic with a purity of 95%, a thermal conductivity of 25 W / mK, a specific heat capacity of 795 J / Kg.K, a thermal expansion coefficient of 7.7 ppm / °C, an elastic modulus of 304 GPa, and a Poisson's ratio of 0.27.

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