A high-power microwave millimeter-wave load with an electromagnetic field confinement structure

Abstract

The present invention belongs to the field of microwave technology and specifically relates to a high-power microwave millimeter-wave load with an electromagnetic field confinement structure, comprising an electromagnetic field confinement metal carrier, a high-power load, and a gold wire. The electromagnetic field confinement metal carrier has a concave structure. The high-power load is disposed within a recessed portion of the electromagnetic field confinement metal carrier and comprises a dielectric layer substrate, a first gold-plated contact on the upper surface of the dielectric layer substrate, a tantalum nitride resistor film, and a second gold-plated contact. The second gold-plated contact also has a concave structure, with the opening direction of its recess aligned with the opening direction of the recessed portion of the electromagnetic field confinement carrier. The tantalum nitride resistor film is connected to the first gold-plated contact and then embedded within the recessed portion of the second gold-plated contact. The electromagnetic field confinement carrier and the second gold-plated contact are bonded together via a gold wire or gold ribbon. The present invention improves the performance of the high-power microwave millimeter-wave load and reduces the impact of existing SMD high-power loads on the frequency response of high-power microwave circuits when operating in the high-frequency band.

Description

Technical Field

[0001] The invention belongs to the field of microwave technology, and in particular relates to a high-power microwave millimeter wave load with an electromagnetic field constraint structure. Background Art

[0002] With the development of science and technology, the performance requirements for power devices in microwave circuits are becoming higher and higher: such as small size, high power, high performance, low cost, and high reliability.

[0003] High-power microwave loads, as specialized passive components, primarily absorb high-power microwave energy. While protecting transmitters, amplifiers, or other microwave equipment from overload, they must also maintain a minimal standing wave ratio within the operating frequency range to prevent strong reflected signals from flowing back into preceding components. Surface-mounted devices (SMDs) are widely used electronic components in modern electronic devices and circuits and are also a common form of high-power microwave load. Because they can be mounted at high speed using automated equipment, they facilitate large-scale production and application. Furthermore, their compactness, lightness, high density, and low cost make them widely used in various RF microwave circuits and systems.

[0004] The main supplier of SMD high-power microwave loads commonly used in existing technologies is EMC. Some domestic companies have also made domestic substitutions, such as Shenzhen Yantong High Frequency Technology Co., Ltd. Taking the 0402 package high-power microwave load as an example: EMC CT0402D and TD0402 uses CVD-deposited diamond as the substrate, gold-plated nickel for the input port, platinum-plated gold for the GND (ground terminal), and tantalum nitride thin film for the resistor layer. Its performance parameters are as follows:

[0005] Resistance: 50Ω±5%;

[0006] Operating frequency range: DC-26.5GHz;

[0007] Input power: 10Watts;

[0008] Peak power: 100Watts (1μs pulse width / 1% duty cycle);

[0009] Voltage Standing Wave Ratio (VSWR):

[0010] DC-8.0GHz:1.35:1

[0011] 8.0-12.4GHz:1.50:1

[0012] 12.4-18.0GHz:1.70:1

[0013] 18.0-26.5GHz:1.95:1;

[0014] Working temperature: -55℃-150℃, storage temperature: -55℃-150℃;

[0015] Temperature coefficient: ±200PPM / ℃ Max.

[0016] However, in the actual application of microwave circuits, when the above-mentioned high-power load operates in the high-frequency band, the frequency response of the high-power microwave circuit is not ideal, which is mainly reflected in the following aspects:

[0017] 1. Narrow operating frequency range: The nominal maximum operating frequency is 26.5 GHz. At this frequency, the nominal standing wave is relatively poor. However, in actual use, due to the influence of assembly and bonding wire, the measured value of the maximum operating frequency often cannot reach the nominal value.

[0018] 2. Large standing waves: Due to high-power applications, the reflection coefficient needs to be as close to 1:1 as possible to prevent the front-end components from being interfered with or burned by the strong echo signal. However, the reflection coefficient of this high-power load is 1.50:1 at an operating frequency of 12.4 GHz, which is much larger than the application requirement.

[0019] 3. High manufacturing costs for resistors: Existing commercial high-power resistors require metallization of one sidewall of the resistor to connect the front circuitry with the back GND, creating a 3D structure. This sidewall metallization process has a low yield rate, and the cost can increase several or even ten times compared to planar 2D circuits.

[0020] In order to continuously improve the power performance of microwave circuits to meet the needs of military electronic countermeasures, high-power equipment, long-distance communications, etc., designing and realizing a high-power load with a higher operating frequency band, smaller standing wave ratio and lower cost has great practical significance for the development of high-power microwave circuits. Summary of the Invention

[0021] The purpose of the present invention is to provide a low-cost, low standing wave, wide-band high-power microwave millimeter wave load with an electromagnetic field constraint structure to reduce the impact of existing SMD high-power loads on the frequency response of high-power microwave circuits when operating in the high frequency band.

[0022] To achieve the above object, the present invention adopts the following technical solutions:

[0023] A high-power microwave and millimeter-wave load with an electromagnetic field constraint structure, comprising an electromagnetic field constraint metal carrier, a high-power load, and a gold wire, characterized in that:

[0024] The electromagnetic field confinement metal carrier is arranged in a concave structure;

[0025] The high-power load is arranged in the recessed portion of the electromagnetic field constraining metal carrier; the high-power load includes a dielectric layer substrate, a first gold-plated contact, a tantalum nitride resistor film, and a second gold-plated contact arranged on the upper surface of the dielectric layer substrate; the second gold-plated contact is also arranged in a concave structure, and the opening direction of its recessed portion is consistent with the opening direction of the recessed portion of the electromagnetic field constraining carrier; the tantalum nitride resistor film is connected to one end of the first gold-plated contact, and is embedded in the recessed portion of the second gold-plated contact together, and is connected to the bottom of the recessed portion of the second gold-plated contact, and the other end of the first gold-plated contact extends to the opening of the recessed portion of the second gold-plated contact;

[0026] In order to reduce standing waves, the second contact is connected to the electromagnetic field confinement metal carrier through dense gold wires or gold ribbons.

[0027] Furthermore, in order to prevent the high-voltage discharge problem of the device under high-power conditions, a chamfer is provided on each side of the opening of the recessed portion of the electromagnetic field restraining metal carrier.

[0028] Furthermore, the chamfers on both sides of the electromagnetic field constrained metal carrier are C-shaped chamfers.

[0029] Furthermore, the sheet resistance of the tantalum nitride resistor film is 50Ω / □.

[0030] Furthermore, the electromagnetic field confinement carrier is prepared by copper-gold plating.

[0031] Furthermore, the size of the dielectric layer substrate is slightly smaller than the size of the recessed portion of the electromagnetic field confinement metal carrier.

[0032] Furthermore, the dielectric layer substrate is made of diamond.

[0033] Furthermore, the length of the first contact is L pad1 , width W pad1 The second contact is in the shape of a concave letter and has a length of L. pad2 , width W res , the characteristic width is W pad2 ; The length of the tantalum nitride resistor film is L TaN , width W TaN , the length of the dielectric layer substrate is L res , width W res .

[0034] Furthermore, the length of the electromagnetic field confined metal carrier is L cav , width W cav, with a 45° chamfer on both sides with a depth of C. To facilitate assembly, a W is provided between the dielectric layer substrate and the electromagnetic field confinement metal carrier. gap spacing.

[0035] The working principle of the high-power load of the present invention is:

[0036] When a signal is injected into a high-power load, the equivalent resistance of the tantalum nitride resistor film is 50Ω, acting as a terminal matching load for a 50Ω characteristic impedance transmission line. The electromagnetic field energy is converted into heat, most of which is channeled into the metal cavity through the high thermal conductivity of the diamond substrate for dissipation.

[0037] Table 1 Thermal conductivity parameters of various materials

[0038] Material Thermal conductivity, W / (m·K) diamond 2000 copper 401 aluminum 237 ceramics 30

[0039] Due to the outward radiation characteristics of electromagnetic waves in existing commercial high-power loads, when signals flow through these loads, some of the energy is not attenuated and converted into heat through the tantalum nitride resistor film, but is instead radiated into the air through the sidewalls of the resistor. During this signal energy radiation process, some energy is always reflected back to the input port due to signal discontinuities (generally speaking, the higher the frequency, the greater the discontinuity and the larger the reflected signal). This is also the key reason why existing commercial high-power loads have difficulty achieving low standing wave ratios at high frequencies. In this case, if electromagnetic field confinement metal layers are introduced on three sides of the resistor, the outward radiated electromagnetic waves can be effectively controlled, allowing the signal to flow through the tantalum nitride resistor film as much as possible, thereby improving the standing wave ratio of the input port.

[0040] The electromagnetic field confinement metal layer can be achieved by gold plating on the side of the resistor's dielectric substrate. However, existing gold plating processes for diamond substrates have numerous issues, including high production costs and low yields. A separate electromagnetic field confinement metal carrier, connected to the load surface via dense gold wires, achieves the same effect while significantly reducing costs.

[0041] In summary, the present invention has the following advantages after adopting the above technical solution:

[0042] 1. Low cost: The present invention adopts surface processing technology, that is, a flat 2D structure instead of a three-dimensional 3D structure, which significantly reduces production costs and improves yield rate;

[0043] 2. Low standing wave: The present invention uses electromagnetic fields to constrain the metal carrier, making the standing wave ratio of the load significantly better than commercial high-power surface mount loads;

[0044] 3. Wide frequency band: The high-power surface mount load of the present invention has a wide operating frequency band, covering the Ka band from DC to 40 GHz. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a schematic diagram of a high-power load structure according to an embodiment;

[0046] Figure 2 2. It is a schematic structural diagram of an electromagnetic field constrained metal carrier according to an embodiment;

[0047] Figure 3 This is a high-power microwave millimeter wave load test circuit diagram with an electromagnetic field confinement structure according to an embodiment;

[0048] Figure 4 This is a physical diagram of a high-power microwave millimeter-wave load test circuit with an electromagnetic field confinement structure according to an embodiment;

[0049] Figure 5 The following is a simulation result diagram of the ceramic substrate with and without electromagnetic field confinement carrier;

[0050] Figure 6 Figure 1 is a simulation result diagram using ceramic substrate and diamond substrate;

[0051] Figure 7 This is a graph showing the VSWR test results of a high-power microwave and millimeter-wave load with an electromagnetic field confinement structure using a ceramic substrate.

[0052] Figure numerals: 1 is a dielectric layer substrate, 2 is a tantalum nitride resistor film, 3 is a gold-plated contact, 4 is an electromagnetic field constraint metal carrier, 5 is a gold wire, 6 is a printed circuit board PCB substrate, 7 is a 50Ω impedance transmission line, and 8 is a metal cavity. DETAILED DESCRIPTION

[0053] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the contents of this specification. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be varied based on different viewpoints and applications without departing from the spirit of the present invention.

[0054] Example 1

[0055] like Figure 1 and Figure 2 As shown, this embodiment provides a high-power microwave and millimeter-wave load with an electromagnetic field constraint structure, including an electromagnetic field constraint metal carrier, a high-power load, and a gold wire.

[0056] The electromagnetic field constraint metal carrier has a concave structure. When implemented, based on the 0402 package size, the electromagnetic field constraint carrier can be expanded to loads of different sizes. The electromagnetic field constraint metal carrier is copper-plated with gold. Considering tolerance and assembly factors, the actual concave part width is slightly larger than the width W of the high-power load.res , easy to install.

[0057] The high-power load is disposed within the recess of the electromagnetic field constraining metal carrier; the high-power load comprises a dielectric layer substrate, two gold-plated contacts disposed on the upper surface of the dielectric layer substrate, and a tantalum nitride resistor film. The two gold-plated contacts are respectively a first gold-plated contact and a second gold-plated contact. The second gold-plated contact is similarly concave, with the opening direction of its recess aligning with the opening direction of the recess of the electromagnetic field constraining carrier. The tantalum nitride resistor film is integrally connected to one end of the first gold-plated contact, then embedded within the recess of the second gold-plated contact and connected to the bottom of the recess of the second gold-plated contact. The other end of the first gold-plated contact extends to the opening of the recess of the second gold-plated contact. The electromagnetic field constraining carrier and the second gold-plated contact are bonded together by gold wire or gold ribbon.

[0058] In order to verify the advantages of the high-power microwave millimeter wave load with electromagnetic field constraint structure in this embodiment, this embodiment is based on Figure 3 and Figure 4 As shown, a test circuit is designed. The test circuit includes a printed circuit board (PCB) substrate, a 50Ω impedance transmission line provided on the upper surface of the PCB substrate, and a metal cavity. The PCB uses Rogers 4350, with a dielectric layer thickness of 0.254mm and a metal layer thickness of 40um. The 50Ω impedance transmission line is used to transmit signals, and the metal cavity serves to fix and protect the circuit and provide grounding. A high-power microwave and millimeter wave load with an electromagnetic field constraint structure is placed in the metal cavity, and the electromagnetic field constraint carrier is bonded to the metal cavity with conductive adhesive, and the metal cavity is connected to the ground. The tantalum nitride resistor film is used to attenuate the signal. The recessed portion of the electromagnetic field constraint metal carrier opens toward and is in close contact with the PCB. The first gold-plated contact is connected to the 50Ω impedance transmission line by a gold wire.

[0059] Existing commercial high-power loads have insufficient operating frequency bands and poor standing wave ratios, especially when the frequency is greater than 12.4GHz, the VSWR exceeds 1.50. Through modeling and simulation analysis of commercial high-power loads, it is known that when the electromagnetic wave signal is attenuated by the load, a portion of the energy is radiated outward through the air and the resistor's own dielectric layer substrate, affecting the performance of the load. To address this problem, the side gold plating process used in existing commercial high-power loads can be used to connect the second gold-plated contact on the top surface of the dielectric layer substrate and the gold-plated layer on the side walls and bottom surface of each side wall of the load. However, this method is costly and has a low yield rate. The dielectric layer substrate is usually made of diamond with a dielectric constant of 6.0 and an extremely high thermal conductivity, which further increases the difficulty of the process and is not suitable for mass production.

[0060] Therefore, this embodiment designs a concave structure electromagnetic field constrained metal carrier, which confines more electromagnetic wave energy within the resistor and allows it to be lost through the tantalum nitride resistor film, thereby improving the yield of high-power load preparation.

[0061] In order to verify the effectiveness of the electromagnetic field constrained metal structure in improving the performance of high-power loads, this embodiment simulates loads with and without electromagnetic field constrained structures. The simulation results are as follows: Figure 5 shown.

[0062] It should be noted that in high-power applications, the use of a diamond substrate can better dissipate heat. Due to the high cost of diamond substrates, and the fact that this embodiment is primarily a verification test (to evaluate the effect of introducing a metal carrier on standing waves), a lower-cost ceramic substrate was used for simulation and actual measurement.

[0063] In this simulation model, a Perfect E idealized electrical wall plane was first added to a single side of the narrow side of the ceramic substrate, effectively grounding the second gold-plated contact through a single side. Then, Perfect E idealized electrical wall planes were added to a single side of the narrow side and two sides of the wide side of the ceramic substrate, effectively grounding all three sides of the second gold-plated contact. Figure 5 This is a simulation result diagram of the carrier with and without electromagnetic field constraint using ceramic substrate, see Figure 5 It can be seen that the electromagnetic field confinement structure with a concave structure significantly improves the performance of high-power loads.

[0064] To achieve optimal testing results, this embodiment addresses the discharge issues of a high-power microwave and millimeter-wave load with an electromagnetic field confinement structure under high power conditions by providing inverted C-shaped chamfers on both sides of the recessed opening of the electromagnetic field confinement metal carrier. Multiple gold wires connect the first gold-plated contact to the 50Ω impedance transmission line, and the second gold-plated contact to the electromagnetic field confinement metal carrier. These wires are kept as short as possible to minimize parasitic inductance while meeting requirements. To address high-voltage discharge and gold wire bonding issues under high-power conditions, the shape and size of the tantalum nitride resistor film and the gold-plated contacts are designed to maintain a distance between the high-power load and the 50Ω impedance transmission line.

[0065] After simulation and optimization using the electromagnetic simulation software Ansoft HFSS, the optimal parameter dimensions were obtained, as shown in Table 2:

[0066] Table 2 High power load parameters (ceramic substrate)

[0067]

[0068]

[0069] The above example can achieve high power load resistance in the range of 4-43.5GHz. Figure 7 This is a graph showing the VSWR test results of a high-power microwave and millimeter-wave load with an electromagnetic field confinement structure using a ceramic substrate. Figure 7 As can be seen, the VSWR of the high-power microwave millimeter-wave loads in this implementation is less than 1.5, far superior to existing commercial high-power loads, as shown in Table 3. Due to the operating frequency of the TRL calibration component itself, based on engineering experience and common sense, it can be concluded that the standing wave performance is generally better when the operating frequency is below 4 GHz.

[0070] Table 3 Comparison with existing commercial high-power loads (VSWR)

[0071]

[0072] In order to demonstrate the effect of dielectric layer substrate on standing wave ratio, this embodiment simulates diamond substrate with dielectric constant 6.0 and ceramic substrate with dielectric constant 9.9. Figure 6 .pass Figure 6 It can be seen that the standing wave ratio of the dielectric layer substrate is diamond and is close to that of the ceramic substrate (from Figure 6 It can be seen that the standing wave ratio of the two is not much different, and the effect of the ceramic substrate is better. This is mainly due to the second contact width W of the ceramic substrate at this time. pad1 The physical dimensions of the diamond substrate are similar to the characteristic impedance of a 50-ohm transmission line, which is more compatible with the 50-ohm characteristic impedance of a microstrip line. Therefore, in practical applications, using diamond as the dielectric substrate can achieve better heat dissipation and is more suitable for high-power applications.

[0073] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A high-power microwave and millimeter-wave load with an electromagnetic field confinement structure, comprising an electromagnetic field confinement metal carrier, a high-power load, and a gold wire, characterized in that: The electromagnetic field confinement metal carrier is arranged in a concave structure; The high-power load is arranged in the recessed portion of the electromagnetic field constraining metal carrier; the high-power load includes a dielectric layer substrate, a first gold-plated contact arranged on the upper surface of the dielectric layer substrate, a tantalum nitride resistor film, and a second gold-plated contact; the second gold-plated contact is also arranged in a concave structure, and the opening direction of its recessed portion is consistent with the opening direction of the recessed portion of the electromagnetic field constraining carrier; the tantalum nitride resistor film is connected to one end of the first gold-plated contact, and is embedded in the recessed portion of the second gold-plated contact together, and is connected to the bottom of the recessed portion of the second gold-plated contact, and the other end of the first gold-plated contact extends to the opening of the recessed portion of the second gold-plated contact; The electromagnetic field confinement carrier is bonded to the first gold-plated contact through gold wire.

2. The high-power microwave and millimeter-wave load with an electromagnetic field confinement structure according to claim 1, characterized in that: In order to prevent the high-voltage discharge problem of the device under high-power conditions, a chamfer is provided on each side of the opening of the recessed portion of the electromagnetic field restraining metal carrier.

3. The high-power microwave and millimeter-wave load with an electromagnetic field confinement structure according to claim 2, characterized in that: The chamfers on both sides of the electromagnetic field confinement metal carrier are C-shaped chamfers.

4. The high-power microwave and millimeter-wave load with an electromagnetic field confinement structure according to claim 1, characterized in that: The sheet resistance of the tantalum nitride resistance film is 50Ω / □.

5. The high-power microwave and millimeter-wave load with an electromagnetic field confinement structure according to claim 1, characterized in that: The electromagnetic field confinement carrier is prepared by copper-gold plating.

6. The high-power microwave and millimeter-wave load with an electromagnetic field confinement structure according to claim 1, characterized in that: The size of the dielectric layer substrate is slightly smaller than the size of the recessed portion of the electromagnetic field confinement metal carrier.

7. A high-power microwave and millimeter-wave load with an electromagnetic field confinement structure according to any one of claims 1 to 6, characterized in that: The dielectric layer substrate is made of diamond.

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