Tape Bonding Solution for Reducing Thermal Stress on an Intermittently Operable Chipset that Controls RF Application for Cooking

Abstract

A power amplifier electronic device for controlling the application of radio frequency (RF) energy generated using solid-state electronic devices can be further configured to control the RF energy application within a cycle between high power and low power. The power amplifier electronic device can include: a semiconductor wafer on which one or more RF power transistors are fabricated; an output matching network configured to provide impedance matching between the semiconductor wafer and an external component operably coupled to an output tab; and an adhesive tape that is bonded at its terminal ends to operably couple the one or more RF power transistors of the semiconductor wafer to the output matching network. The width of the adhesive tape can be greater than approximately five times the thickness of the adhesive tape.

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of priority of U.S. Application No. 62 / 769,225, filed on Nov. 19, 2018, and U.S. Application No. 16 / 686,521, filed on Nov. 18, 2019, the entire contents of which are incorporated herein by reference. Technical field

[0003] Example embodiments generally relate to ovens, and more particularly to an oven that uses radio - frequency (RF) heating provided by solid - state electronic devices and a solution for protecting oven components. Background art

[0004] Combination ovens capable of cooking using more than one heat source (e.g., convection, steam, microwave, etc.) have been in use for decades. Each cooking source has its own distinct set of characteristics. Thus, combination ovens generally can take advantage of the benefits of each different cooking source to attempt to provide an improved cooking process in terms of time and / or quality. More recently, ovens with an even better ability to cook food have been introduced, which utilize a combination of controllable RF energy and convection energy. Different from the relatively undifferentiated food bombardment that typically occurs in microwave cooking, the use of controllable RF energy can enable more refined control of the cooking process. This refined control of the cooking process can result in excellent results in a significantly shorter period of time.

[0005] Of course, over the decades, RF applications have also developed rapidly in other technical fields. Thus, with the development of this new technical field, it is not surprising that courses, as well as various components and assemblies used in other technical fields, are applied to the field of RF cooking. However, the use of components that have been well - tested in other RF applications (especially those related to power amplifier electronics) has led to an alarming number of failures of such components. In this regard, for example, power amplifier electronics that operate almost continuously at high power in other applications unexpectedly fail when transferred to an oven environment where their performance requirements seemingly decrease.

[0006] Upon investigation, the solution to the mystery of why these generally robust components fail in what seemingly is a less challenging operating environment than they normally face appears to be simple. However, as will be discussed in more detail below, the seemingly simple solution is not the panacea that is desired. Thus, the example embodiments employ a relatively counter - intuitive approach to connect the components within the power amplifier electronics. Summary of the invention

[0007] In an exemplary embodiment, an oven is provided. The oven can include: a cooking chamber configured to receive food; and an RF heating system configured to provide RF energy into the cooking chamber using solid state electronics. The solid state electronics includes power amplifier electronics configured to provide a signal into the cooking chamber via a transmitter assembly, the transmitter assembly being operably coupled to the cooking chamber via a waveguide assembly. The power amplifier electronics can be configured to control the application of RF energy into the cooking chamber at least in part based on a learning program that, when executed, produces a power cycle between high power and low power. The power amplifier electronics can include: a semiconductor wafer on which one or more RF power transistors are fabricated; an output matching network configured to provide impedance matching between the semiconductor wafer and an external component operably coupled to an output tab; and an adhesive tape that is bonded at its terminal ends to operably couple the one or more RF power transistors of the semiconductor wafer to the output matching network. The width of the adhesive tape can be greater than approximately five times the thickness of the adhesive tape.

[0008] In another exemplary embodiment, a power amplifier electronics for an oven can be provided. The oven can be configured to provide RF heating via RF energy generated using solid state electronics, the solid state electronics being configured to control the application of RF energy into a cooking chamber of the oven at least in part based on a learning program that, when executed, produces a power cycle between high power and low power. The power amplifier electronics can include: a semiconductor wafer on which one or more RF power transistors are fabricated; an output matching network configured to provide impedance matching between the semiconductor wafer and an external component operably coupled to an output tab; and an adhesive tape that is bonded at its terminal ends to operably couple the one or more RF power transistors of the semiconductor wafer to the output matching network. The width of the adhesive tape can be greater than approximately five times the thickness of the adhesive tape.

[0009] In another exemplary embodiment, a method of coupling devices in a power amplifier electronics is provided. The method may include providing a semiconductor wafer within a package of the power amplifier electronics, on which one or more RF power transistors are fabricated, the power amplifier electronics being configured to control the application of radio frequency (RF) energy generated using solid state electronics, wherein the power amplifier electronics is configured to control the RF energy application within a cycle between high power and low power. The method may further include: providing an output matching network configured to provide impedance matching between the semiconductor wafer and an external component operably coupled to an output tab of the package adjacent to the semiconductor wafer; and operably coupling one or more RF power transistors of the semiconductor wafer to the output matching network via an adhesive tape. The adhesive tape may bond its terminal ends to a respective one of the one or more RF power transistors of the semiconductor wafer and the output matching network. The width of the adhesive tape may be greater than about five times the thickness of the adhesive tape. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] After having thus generally described the invention, reference will now be made to the drawings, which are not necessarily to scale, and in which:

[0011] Figure 1 A perspective view of an oven capable of employing at least two energy sources in accordance with an exemplary embodiment is shown;

[0012] Figure 2 A functional block diagram of an oven in accordance with an exemplary embodiment is shown; Figure 1 of the oven is shown;

[0013] Figure 3 A cross-sectional view of the oven taken along a plane cutting through from the front side to the back side of the oven in accordance with an exemplary embodiment is shown;

[0014] Figure 4 A top plan view of a top plan view area of the oven in accordance with an exemplary embodiment is shown;

[0015] Figure 5 A block diagram of control electronics for providing an electronic circuit system for controlling the application of RF in the oven in accordance with an exemplary embodiment is shown;

[0016] Figure 6 A partially isolated cross-sectional view through a package of a power amplifier electronics of the oven in accordance with an exemplary embodiment is shown;

[0017] Figure 7 A plan view of a transistor array of a semiconductor wafer employing a tape bonding technique in accordance with an exemplary embodiment is shown;

[0018] Figure 8Shows a cross-sectional view of a bonded joint according to an example embodiment; and

[0019] Figure 9 Displays a block diagram of a method for providing internal bonding within a power amplifier electronic device according to an example embodiment. Detailed Description

[0020] Some example embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, example embodiments are shown. In fact, the examples described and depicted herein should not be construed as limiting the scope, applicability, or configuration of the present disclosure. Rather, these example embodiments are provided so that the present disclosure will satisfy applicable legal requirements. Like reference numerals refer to like elements throughout the drawings. Additionally, as used herein, the term "or" will be interpreted as a logical operator such that the result is true if one or more of its operands are true. As used herein, operatively coupled should be understood to include both direct and indirect connections, which in each case enable functional interconnection of the components that are operatively coupled to each other.

[0021] Some example embodiments can improve the cooking performance of an oven and / or can improve the operator experience of an individual employing the example embodiment. In this regard, based on the application of RF energy under the instruction of a control electronic device, the oven can cook food relatively quickly and evenly, and the control electronic device is configured to employ protection strategies and structures to prevent damage to the control electronic device described herein.

[0022] As described above, power amplifier electronic devices that operate at high power on a nearly continuous basis in other technical fields involving RF power amplifiers unexpectedly fail in an oven environment. This is surprising because, due to the fact that the oven cycles between high power and low power (as will be discussed in more detail below), the oven environment does not require continuous operation of these components. However, upon further investigation, it was determined that the connecting wires that couple the high-power RF section to the microwave transistors, which are part of the impedance matching network within the power amplifier electronic device, are the primary source of the failure. The initial idea for solving this problem was to increase the size of the connecting wires and the bonding at the placement pads of the components to which they are operatively coupled to make them more tolerant to power fluctuations associated with the thermal stress caused by the oven cycling between high power and low power. However, this intuitive solution was also ineffective because the larger size actually caused a resonant frequency at the operating frequency, resulting in increased thermal stress in the power cycling application. Therefore, due to the smaller thermal stress generated at the resonant frequency during normal operation, a somewhat counterintuitive approach of using other structural changes (i.e., bonding tapes instead of multiple wires) improved the performance. Below will be referred toFigures 6 to 8 Let's discuss additional specific examples that describe the solution. However, first, we will refer to Figures 1 to 5 to discuss a further description of the environmental background that gives rise to the problem.

[0023] Figure 1 A perspective view of an oven 100 according to an exemplary embodiment is shown. As Figure 1 shown, the oven 100 may include a cooking chamber 102 in which food items can be placed to apply heat by any one of at least two energy sources that the oven 100 can utilize. The cooking chamber 102 may include a door 104 and an interface panel 106 that may be located near the door 104 when the door 104 is closed. The door 104 may be operated via a handle 105 that may extend across the front of the oven 100 parallel to the ground. In some cases, in alternative embodiments, the interface panel 106 may be located substantially above the door 104 (as Figure 1 shown) or beside the door 104. In the exemplary embodiment, the interface panel 106 may include a touchscreen display that is capable of providing visual indications to an operator and is further capable of receiving touch inputs from the operator. The interface panel 106 may be the mechanism through which instructions are provided to the operator and is the mechanism through which feedback regarding the status of the cooking process, options, etc. is provided to the operator.

[0024] In some embodiments, the oven 100 may include multiple shelves or may include a shelf (or tray) support 108 or guide slots to facilitate the insertion of one or more shelves 110 or trays for holding food items to be cooked. In the exemplary embodiment, air delivery apertures 112 may be positioned near the shelf support 108 (e.g., in one embodiment, just below the height of the shelf support) such that heated air can be forced into the cooking chamber 102 via a heated air circulation fan ( Figure 1 not shown in the figure). The heated air circulation fan may draw air into / from the cooking chamber 102 via a chamber outflow port 120 disposed at the back wall or rear wall of the cooking chamber 102 (i.e., the wall opposite the door 104). The air may be circulated back into the cooking chamber 102 from the chamber outflow port 120 via the air delivery apertures 112. After the air is removed from the cooking chamber 102 via the chamber outflow port 120, the air may be cleaned, heated, and pushed through the system by other components, and then the cleaned, hot, and velocity-controlled air returns to the cooking chamber 102. This air circulation system including the chamber outflow port 120, the air delivery apertures 112, the heated air circulation fan, the cleaning components, and all the ducts therebetween may form a first air circulation system within the oven 100.

[0025] In an example embodiment, radio frequency (RF) energy can be used, at least in part, to heat food placed on a tray or on one of the shelves 110 (or, in embodiments where the shelf 110 is not employed, only on the chassis of the cooking chamber 102). At the same time, the airflow that may be provided can be heated to enable further heating or even charring. It is worth noting that a metal tray can be placed on one of the shelf supports 108 or the shelves 110 in some example embodiments. However, the oven 100 can be configured to employ frequencies and / or mitigation strategies to detect and / or prevent any arcing that might otherwise occur by using RF energy in conjunction with metal components.

[0026] In an example embodiment, the RF energy can be delivered to the cooking chamber 102 via an antenna assembly 130 disposed adjacent to the cooking chamber 102. In some embodiments, multiple components can be provided in the antenna assembly 130, and these components can be arranged on opposite sides of the cooking chamber 102. The antenna assembly 130 can include one or more instances of a power amplifier, a transmitter, a waveguide, etc. configured to couple the RF energy into the cooking chamber 102.

[0027] The cooking chamber 102 can be configured to provide RF shielding on its five sides (e.g., the top side, the bottom side, the back side, and the right and left sides), but the door 104 can include a choke 140 to provide RF shielding for the front side. Thus, the choke 140 can be configured to fit tightly with the opening defined at the front side of the cooking chamber 102 to prevent RF energy from leaking out of the cooking chamber 102 when the door 104 is closed and RF energy is applied into the cooking chamber 102 via the antenna assembly 130.

[0028] In an example embodiment, a gasket 142 can be provided to extend around the outer periphery of the choke 140. In this regard, the gasket 142 can be formed of a material such as wire mesh, rubber, silicone, or other such materials that can have a degree of compressibility between the door 104 and the outer periphery of the opening leading into the cooking chamber 102. In some cases, the gasket 142 can provide a substantially airtight seal. However, in other cases (e.g., in the case of using wire mesh), the gasket 142 can allow air to pass through it. Especially in cases where the gasket 142 is substantially airtight, it may be desirable to provide an air cleaning system associated with the first air circulation system described above.

[0029] The antenna assembly 130 can be configured to generate a controllable RF emission in the cooking chamber 102 using solid state components. Thus, the oven 100 can generate and control the RF energy applied to the cooking chamber 102 using only solid state components without any magnetron. The use of solid state components can provide distinct advantages in terms of allowing a greater degree of control over the characteristics of the RF energy (e.g., power / energy level, phase, and frequency) compared to what may be possible with the use of a magnetron. However, since the power required to cook food is relatively high, the solid state components themselves will also generate a relatively large amount of heat that must be effectively removed to keep the solid state components cool and avoid damaging them. To cool the solid state components, the oven 100 can include a second air circulation system.

[0030] The second air circulation system can operate within the oven body 150 of the oven 100 to circulate cooling air, thereby preventing overheating of the solid state components that power the cooking chamber 102 and control the RF energy applied thereto. The second air circulation system can include an inlet array 152 formed at the bottom (or base) portion of the oven body 150. In particular, the base region of the oven body 150 can be a substantially hollow cavity within the oven body 150 that is disposed below the cooking chamber 102. The inlet array 152 can include a plurality of inlet ports that are proximate the base and disposed on respective opposite sides of the oven body 150 (e.g., the right and left sides when viewing the oven 100 from the front), and also proximate the base and disposed on the front side of the oven body 150. The portions of the inlet array 152 disposed on the respective sides of the oven body 150 can be formed at an angle with respect to a majority of the oven body 150 on each corresponding side. In this regard, the portions of the inlet array 152 disposed on the respective sides of the oven body 150 can taper towards each other at an angle of approximately twenty degrees (e.g., between ten degrees and thirty degrees). This tapering can ensure that even when the oven 100 is inserted into a space that is just wide enough to accommodate the oven body 150 (e.g., due to walls or other equipment being adjacent to the respective sides of the oven body 150), a space is formed at a location proximate the base to allow air to enter into the inlet array 152. At the front portion of the oven body 150 proximate the base, when the door 104 is closed, the corresponding portion of the inlet array 152 can be in the same plane as (or at least in a plane parallel to) the front of the oven 100. Such tapering is not required to provide a passage for air to enter the inlet array 152 in the front portion of the oven body 150 since this region must remain clear to allow the door 104 to open.

[0031] Starting from the base, the duct can provide a path for air entering the base through the inlet array 152, causing the air (under the influence of the cold air circulation fan) to move upward through the oven body 150 to the top shelf, within which control electronics (e.g., solid state components) are disposed in the top shelf top shelf portion. The top shelf top shelf portion can include various structures to ensure that the air traveling from the base to the top shelf top shelf and ultimately exiting the oven body 150 via the outlet exhaust window 154 passes near the control electronics to remove heat from the control electronics. The hot air (i.e., the air that has had heat removed from the control electronics) is then exhausted from the outlet exhaust window 154. In some embodiments, the outlet exhaust window 154 can be disposed on the right and left sides of the oven body 150 and at the rear of the top shelf oven body 150 near the top shelf. Disposing the inlet array 152 at the base and the outlet exhaust window 154 at the top shelf top shelf ensures that the normal tendency for hotter air to rise will prevent the air exhausted (from the outlet exhaust window 154) from being recirculated through the system by being drawn into the inlet array 152. Additionally, due to the shape of the base at the sides of the oven (which includes both the inlet array 152 and the outlet exhaust window 154 portions), a tapered structure of the inlet array 152 is provided on a wall that is also slightly concave to form a protrusion 158 that blocks any air path between the inlet and the outlet, so the inlet array 152 is at least partially isolated from any direct communication path from the outlet exhaust window 154. Thus, the air drawn into the inlet array 152 can reliably be expected to be ambient room temperature air rather than recirculated exhausted cooled air.

[0032] Figure 2 A functional block diagram of an oven 100 according to an example embodiment is shown. As Figure 2 shown, the oven 100 can include at least a first energy source 200 and a second energy source 210. The first energy source 200 and the second energy source 210 can each correspond to a respective different cooking method. In some embodiments, the first energy source 200 and the second energy source 210 can be an RF heating source and a convection heating source, respectively. However, it should be understood that in some embodiments, additional or alternative energy sources can also be provided. Additionally, some example embodiments can be practiced in the context of an oven that includes only a single energy source (e.g., the second energy source 210). Thus, the example embodiments can be practiced on other conventional ovens that use, for example, gas or electricity for heating to apply heat.

[0033] As previously mentioned, the first energy source 200 can be an RF energy source (or RF heating source) configured to generate relatively wide-spectrum RF energy, or a phase-controlled energy source of a specific narrow band, for cooking food placed in the cooking chamber 102 of the oven 100. Thus, for example, the first energy source 200 can include the antenna assembly 130 and the RF generator 204. The RF generator 204 of an example embodiment can be configured to generate RF energy at a selected level with a selected frequency and phase. In some cases, these frequencies can be selected in the range of approximately 6 MHz to 246 GHz. However, in some cases, other RF bands can be employed. In some examples, frequencies can be selected from the unlicensed frequency (e.g., ISM) band for application by the RF generator 204.

[0034] In some cases, the antenna assembly 130 can be configured to transmit RF energy into the cooking chamber 102 and receive feedback indicative of the absorption levels of the corresponding different frequencies in the food. Then, the absorption levels can be used to control the generation of RF energy to provide even cooking of the food. However, feedback indicative of the absorption levels is not required in all embodiments. For example, some embodiments can employ an algorithm for selecting frequencies and phases based on a predetermined strategy identified for a specific combination of a selected cooking time, power level, food type, recipe, etc. In some embodiments, the antenna assembly 130 can include multiple antennas, waveguides, transmitters, and an RF transparent cover that provide an interface between the antenna assembly 130 and the cooking chamber 102. Thus, for example, four waveguides can be provided, and in some cases, each waveguide can receive RF energy generated by its own corresponding power module or a power amplifier of the RF generator 204 operating under the control of the control electronics 220. In an alternative embodiment, a single multiplexing generator can be employed to deliver different energies into each waveguide or a pair of waveguides to provide energy into the cooking chamber 102.

[0035] In an example embodiment, the second energy source 210 can be an energy source capable of causing browning and / or convective heating of the food. Thus, for example, the second energy source 210 can be a convective heating system including an air flow generator 212 and an air heater 214. The air flow generator 212 can be implemented as or include a heated air circulation fan or another device capable of driving an air flow (e.g., via the air delivery orifice 112) through the cooking chamber 102. The air heater 214 can be an electrical heating element or other type of heater that heats the air to be driven by the air flow generator 212 towards the food. Both the temperature of the air and the speed of the air flow will affect the cooking time obtained using the second energy source 210 and especially the combination of the first energy source 200 and the second energy source 210.

[0036] In an example embodiment, the first energy source 200 and the second energy source 210 may be directly or indirectly controlled by control electronics 220. The control electronics 220 may be configured to receive inputs that describe a selected recipe, food, and / or cooking conditions in order to provide instructions or control to the first energy source 200 and the second energy source 210 to control the cooking process. In some embodiments, the control electronics 220 may be configured to receive static inputs and / or dynamic inputs regarding the food and / or cooking conditions. The dynamic inputs may include feedback data regarding the phase and frequency of the RF energy applied to the cooking chamber 102. In some cases, the dynamic inputs may include adjustments made by an operator during the cooking process. The static inputs may include parameters input by the operator as initial conditions. For example, the static inputs may include a description of the selection of food type, initial state or temperature, final desired state or temperature, number and / or size of portions to be cooked, location of the item to be cooked (e.g., when multiple trays or heights are employed), recipe (e.g., defining a sequence of cooking steps), etc.

[0037] In some embodiments, the control electronics 220 may be configured to also provide instructions or control to the air flow generator 212 and / or the air heater 214 to control the air flow through the cooking chamber 102. However, rather than relying solely on the control of the air flow generator 212 to affect the characteristics of the air flow in the cooking chamber 102, some example embodiments may further employ the first energy source 200 to also apply the energy used for cooking the food, such that the control electronics 220 manages the balance of the amount of energy applied to each source or the management thereof.

[0038] In an example embodiment, the control electronics 220 may be configured to access algorithms and / or data tables that define RF cooking parameters for driving the RF generator 204 to generate RF energy at corresponding levels, phases, and / or frequencies at corresponding times determined by the algorithm or data table based on information regarding the initial conditions of the food and / or based on a recipe that defines the sequence of cooking steps. Thus, the control electronics 220 may be configured to employ RF cooking as the primary energy source for cooking the food, while convective heat application is an auxiliary energy source for browning and faster cooking. However, other energy sources (e.g., a third energy source or other energy sources) may also be employed during the cooking process.

[0039] In some cases, cooking tags, programs, or recipes may be provided to define the cooking parameters to be employed for each of a plurality of possible cooking stages or steps (definable for food items), and the control electronics 220 may be configured to access and / or execute the cooking tags, programs, or recipes (collectively referred to herein as recipes). In some embodiments, except in cases where dynamic inputs (i.e., changes to cooking parameters while the program is being executed) are provided, the control electronics 220 may be configured to determine which recipe to execute based on inputs provided by a user. In an example embodiment, the input to the control electronics 220 may further include a browning instruction. In this regard, for example, the browning instruction may include instructions regarding air speed, air temperature, and / or the time for a set combination of applied air speed and temperature (e.g., start time and stop time for certain speed and heating combinations). The browning instruction may be provided via a user interface accessible to an operator or may be part of a cooking tag, program, or recipe.

[0040] As described above, the first air circulation system may be configured to drive heated air through the cooking chamber 102 to maintain a stable cooking temperature within the cooking chamber 102. At the same time, the second air circulation system may cool the control electronics 220. The first air circulation system and the second air circulation system may be isolated from each other. However, each respective system typically uses a pressure differential (e.g., formed by a fan) within the respective compartments formed in the respective systems to drive the corresponding airflows required for each system. While the airflow of the first air circulation system is intended to heat the food in the cooking chamber 102, the airflow of the second air circulation system is intended to cool the control electronics 220. Thus, the cooling fan 290 provides cooling air 295 to the control electronics 220, as Figure 2 shown.

[0041] The structure for forming the air cooling passage (through which the cooling fan 290 cools the control electronics 220) can be designed to efficiently deliver the cooling air 295 to the control electronics 220 and also minimize the scaling problem or dust / debris accumulation in the sensitive areas or the areas that are difficult to access and / or clean of the oven 100. At the same time, the structure for forming the air cooling passage can also be designed to maximize the ability to access and clean the areas where dust / debris are more likely to accumulate. In addition, the structure for forming the air cooling passage (through which the cooling fan 290 cools the control electronics 220) can be designed to strategically employ various natural phenomena to further promote the efficient and effective operation of the second air circulation system. In this regard, for example, the upward trend of hot air and the management of the high-pressure and low-pressure zones that are inevitably generated by the operation of the fans within the system can be strategically employed through the design and arrangement of various structures so that some difficult-to-access areas remain relatively clean while making other areas that were originally relatively easy to access more likely to become areas that need to be cleaned.

[0042] Figure 3 A typical airflow path and various structures of the second air circulation system can be seen therein. In this regard, Figure 3 A cross-sectional view of the oven 100 as viewed from a plane passing through the front to the back of the oven 100 is shown. The base (or base region 300) of the oven 100 is defined below the cooking chamber 102 and includes an intake cavity 310. During operation, air is drawn into the intake cavity 310 through the inlet array 152 and further into the cooling fan 290, and then forced to radially outward (as shown by arrow 315) to leave the cooling fan 290 and enter the riser tube 330 (e.g., flue), which extends from the base region 300 to the top shelf (or top shelf region 340) to turn the air upward (as shown by arrow 315). The air is forced upward through the riser tube 330 into the top shelf region 340, where the components of the control electronics 220 are arranged. The air then cools the components of the control electronics 220 and then leaves the main body 150 of the oven 100 via the outlet exhaust window 154. The components of the control electronics 220 can include power supply electronics 222, power amplifier electronics 224, and display electronics 226.

[0043] When air reaches the top deck region 340, the air is first directed from the riser tube 330 to the power amplifier housing 350. The power amplifier housing 350 may house the power amplifier electronics 224. In particular, the power amplifier electronics 224 may be located on an electronic board to which all such components are mounted. The power amplifier electronics 224 may thus include one or more power amplifiers that are mounted to the electronic board for powering the antenna assembly 130. Thus, the power amplifier electronics 224 may generate a relatively large heat load. To facilitate dissipation of this relatively large heat load, the power amplifier electronics 224 may be mounted to one or more heat sinks 352. In other words, the electronic board may be mounted to one or more heat sinks 352. The heat sinks 352 may include large metal fins that extend away from the circuit board on which the power amplifier electronics 224 are mounted. Thus, these fins may extend downward (toward the cooking chamber 102). These fins may also extend away from the centerline of the oven 100 (front to back) in a lateral direction to direct the air provided into the power amplifier housing 350 and pass the air over the fins of the heat sink 352.

[0044] Figure 4 A top view of the top deck region 340 is shown and various components of the power amplifier housing 350 and the antenna assembly 130 are illustrated, including the waveguides of the transmitter assembly 400 and the waveguide assembly 410. Power is provided from the power amplifier electronics 224 to each transmitter of the transmitter assembly 400. The transmitter assembly 400 operably couples the signals generated by the power amplifiers of the power amplifier electronics 224 into a corresponding one of the waveguides of the waveguide assembly 410 for transmitting the corresponding signals into the cooking chamber 102 via the antenna assembly 130 as described above.

[0045] The power amplifier electronics 224 are defined by a plurality of electronic circuit system components including operational amplifiers, transistors, etc., which are configured to generate waveforms of corresponding power levels, frequencies, and phases required for a particular scenario or cooking program. In some cases, the cooking program may select an algorithm for controlling the power amplifier electronics 224 to direct RF emissions into the cooking chamber 102 at a selected power level, frequency, and phase. One or more learning processes may be initiated to select one or more corresponding algorithms for directing power application. These learning processes may include detecting feedback on the efficacy of applying power to the cooking chamber 102 at a particular frequency (and / or phase). To determine efficacy, in some cases, the learning process may measure efficiency and compare the efficiency to one or more thresholds. The efficiency may be calculated as the difference between the forward power (P fwd ) and the reflected power (P refl ) divided by the forward power (Pfwd )。In this way, for example, the power entering the cooking chamber 102 (i.e., the forward power) and the reflected power can be measured to determine the amount of power that has been absorbed into the food (or workload) entering the cooking chamber 102. Then the efficiency can be calculated as: Efficiency (eff) = (P fwd -P refl ) / P fwd .

[0046] As can be understood from the above description, measuring the transfer efficiency of RF energy to food can be beneficial in determining the effectiveness of a particular (e.g., current) selection of the combination (or pair) of frequency and phase parameters of the RF energy applied to the cooking chamber 102 in transferring thermal energy to the food. Thus, measuring the efficiency may be beneficial in selecting the optimal combination or algorithm of energy application. Therefore, it is desirable that the measurement of efficiency should also be as accurate as possible to ensure that meaningful control is affected by the monitored efficiency.

[0047] Figure 5 is a block diagram of a control electronic device 220 for providing an electronic circuit system for instantiating power cycling during oven operation. In some embodiments, the control electronic device 220 may include or otherwise communicate with a processing circuit system 600, which may be configured to perform actions in accordance with the example embodiments described herein. In this way, for example, functions attributable to the control electronic device 220 may be performed by the processing circuit system 600.

[0048] According to an example embodiment of the present invention, the processing circuit system 600 may be configured to perform data processing, control function execution, and / or other processing and management services. In some embodiments, the processing circuit system 600 may be implemented as a chip or a chipset. In other words, the processing circuit system 600 may include one or more physical packages (e.g., chips) that include materials, components, and / or wires on a structural component (e.g., a substrate). The structural component may provide physical strength, size savings, and / or electrical interaction limitations for the component circuitry included thereon. Thus, in some cases, the processing circuit system 600 may be configured to implement embodiments of the present invention on a single chip or as a single "system-on-chip". In this way, in some cases, the chip or chipset may constitute a device for performing one or more operations to provide the functions described herein.

[0049] In an example embodiment, the processing circuitry 600 may include one or more instances of each of a processor 610 and a memory 620 that may communicate with or otherwise control a device interface 630 and a user interface 570. As such, the processing circuitry 600 may be implemented as a circuit chip (e.g., an integrated circuit chip) configured (e.g., in hardware, software, or a combination of hardware and software) to perform the operations described herein. However, in some embodiments, the processing circuitry 600 may be implemented as part of an on-board computer.

[0050] The user interface 570 (which may be implemented as, include, or be part of an interface panel 106) may communicate with the processing circuitry 600 to receive indications of user input and / or provide an auditory output, a visual output, a mechanical output, or other output to the user (or operator) at the user interface 570. As such, the user interface 570 may include, for example, a display (e.g., a touch screen such as the interface panel 106), one or more hard or soft buttons or keys, and / or other input / output mechanisms.

[0051] The device interface 630 may include one or more interface mechanisms for enabling communication with a connected device 650, such as other components of the oven 100, sensors of the sensor network of the oven 100, removable memory devices, wireless or wired network communication devices, etc. In some cases, the device interface 630 may be any device, such as a device or circuitry implemented in hardware or a combination of hardware and software, configured to receive and / or transmit data from / to a sensor that measures any one of a plurality of device parameters, such as frequency, phase, temperature (e.g., in the cooking chamber 102 or in an air passage associated with the second energy source 210), air speed, etc. Thus, in one example, the device interface 630 may receive input at least from a temperature sensor that measures the above temperature, or from any of the other above parameters, such that such parameters can be transmitted to the processing circuitry 600 for performing certain protection or control functions. Alternatively or additionally, the device interface 630 may provide an interface mechanism for any device capable of communicating with the processing circuitry 600, either wired or wirelessly. In still other alternative scenarios, the device interface 630 may provide a connection and / or interface mechanism such that the processing circuitry 600 can control the various components of the oven 100.

[0052] In an exemplary embodiment, the memory 620 may include one or more non-volatile memory devices, which may be fixed or removable volatile and / or non-volatile memories. The memory 620 may be configured to store information, data, cooking tags, programs, recipes, applications, instructions, etc., such that the control electronics 220 can perform various functions according to the exemplary embodiments of the present invention. For example, the memory 620 may be configured to buffer input data for processing by the processor 610. Additionally or alternatively, the memory 620 may be configured to store instructions for execution by the processor 610. As yet another alternative, the memory 620 may include one or more databases that may store various data sets in response to input from a sensor network or in response to programming of any of the various cooking programs. Among the contents of the memory 620, applications may be stored for execution by the processor 610 to perform functions associated with each respective application. In some cases, the applications may include control applications that utilize parameter data to control heat application through the first energy source 200 and the second energy source 210 as described herein. In this regard, for example, the applications may include operating guides that use a corresponding table of frequency, phase, RF energy level, temperature, and air speed to define the expected cooking speed for a given set of initial parameters (e.g., food type, size, initial state, location, etc.). Thus, some applications that may be executed by the processor 610 and stored in the memory 620 may include tables that define combinations of RF energy parameters and air speed and temperature to determine cooking times for certain degrees of doneness and / or for executing specific cooking recipes. Thus, different cooking programs may be executed to generate different RF and / or convection environments to achieve the desired cooking results. In still other examples, as described above, data tables may be stored for defining calibration values and / or diagnostic values. Alternatively or additionally, the memory 620 may store applications for defining responses to stimuli, which responses include the generation of protective actions and / or notification functions.

[0053] Processor 610 can be implemented in a variety of different ways. For example, processor 610 can be implemented as various processing devices, such as a microprocessor or other processing elements, a coprocessor, a controller, or various other computing or processing devices (including integrated circuits, such as ASICs (application specific integrated circuits), FPGAs (field programmable gate arrays), etc.). In an example embodiment, processor 610 can be configured to execute instructions stored in memory 620 or otherwise accessible to processor 610. Thus, whether configured by hardware or by a combination of hardware and software, processor 610 can represent an entity that, when correspondingly configured, is capable of performing the operations according to the exemplary embodiments of the present invention (e.g., physically implemented as a circuit - such as in the form of processing circuitry 600). Thus, for example, when any instance of processor 610 is implemented as an ASIC, FPGA, etc., processor 610 can be specially configured hardware for performing the operations described herein. Alternatively, as another example, when processor 610 is implemented as an executor of one or more software instructions, the instructions can specifically configure processor 610 to perform the operations described herein.

[0054] In an example embodiment, processor 610 (or processing circuitry 600) can be implemented as, include, or otherwise control control electronics 220 and / or power amplifier electronics 224. Thus, in some embodiments, it can be said that processor 610 (or processing circuitry 600) causes each operation described in connection with control electronics 220 and / or power amplifier electronics 224 by guiding control electronics 220 and / or power amplifier electronics 224 to assume corresponding functions in response to the execution of instructions or algorithms that correspondingly configure processor 610 (or processing circuitry 600). As an example, control electronics 220 can be configured to control responses to various stimuli that are associated with performing the learning procedures discussed above and guiding RF application within oven 100 based on that learning procedure. Additionally, control electronics 220 can be configured to determine efficiency parameters and take protective measures based on the efficiency parameters or based on various values, measurements, and / or parameters determined by or received at control electronics 220 for performing the learning procedure. In some cases, different instances of the processor (or processors) and memory can be associated with different portions of control electronics 220 (e.g., including different processors for controlling power amplifier electronics 224 and other possible components).

[0055] In an example embodiment, the control electronics 220 may also access and / or execute instructions for controlling the RF generator 204 and / or the antenna assembly 130 to control the application of RF energy to the cooking chamber 102. Thus, for example, an operator may provide a static input to define the type, quality, quantity, or other descriptive parameters (e.g., a recipe) related to the food(s) disposed within the cooking chamber 102. The control electronics 220 may then utilize the static input to locate an algorithm or other program to be executed to define the application of RF energy and / or convective energy to be applied within the cooking chamber 102. The control electronics 220 may also monitor dynamic inputs to modify the amount, frequency, phase, or other characteristics of the RF energy to be applied within the cooking chamber 102 during the cooking process and may also perform protection functions. Finally, the control electronics 220 may execute instructions for calibration and / or fault analysis. Thus, for example, the control electronics 220 may be configured to act locally to protect the power amplifier electronics 224 by stopping the RF application to the cooking chamber 102, by adjusting components to provide a calibrated output, and / or by warning the user when various anomalies or correctable conditions are detected.

[0056] In some embodiments, as part of a learning procedure, efficiency calculations may be performed periodically throughout the cooking process. In this regard, the control electronics 220 may be configured to infer, calculate, or otherwise determine the amount of energy to be directed to the food (i.e., the forward power value 520) and the amount of energy reflected back from the cooking chamber 102 (i.e., the reflected power value 522) such that an accurate estimate of the absorbed power (or energy) may be estimated and an efficiency parameter may be determined. The control electronics 220 may then control the operation of the RF generator 204 and / or the antenna assembly 130 based on the measured efficiency as part of a calibration or cooking process. Thus, for example, if a learning process is performed during cooking, it may be expected that the measured efficiency is at least above a threshold (e.g., 40%) as long as there is food or a load present in the cooking chamber 102. If the efficiency is below the threshold, the control electronics 220 may communicate with the user interface 570 to make the user aware of the need to check the cooking chamber 102 to ensure that there is a load present therein. Discrete efficiency measurements may be made at any desired time interval (e.g., every 100 milliseconds) to perform the protection or warning functions described herein. If the reflected power is very high, the power amplifier electronics 224 may be turned off. If certain temperatures of components (e.g., the temperature of one or both of the heat sink 352, the processor 610, or the air temperature) are too high, an alert may be provided via the user interface 570 and / or the power amplifier electronics 224 may be turned off. Other protective measures are possible.

[0057] One aspect of the oven 100 of the example embodiment enables the oven 100 to provide an improvement in cooking capabilities because the power amplifier electronics 224 employs the above-described learning procedure. The learning procedure may be performed, and then RF energy of an amplitude, phase, and / or frequency selected based on the most efficient combination learned from the learning procedure may be applied. The process may be cyclical, because as the properties of the food change due to cooking, the learning procedure may be repeated several times during the cooking operation to ensure maximum efficiency. Thus, the power level may cycle between a high level and a low level during the learning / cooking cycle. As described above, these cycles between high power and low power may create thermal stresses on the components of the power amplifier electronics 224.

[0058] Figure 6 Demonstrated through Figure 3 FIG. 2 is a partially isolated cross-sectional view of a portion of the power amplifier electronics 224 of FIG. Figure 6 As shown, the package / flange 700 can be operably coupled to the lid 710 to surround or contain a semiconductor die 720. The semiconductor die 720 can be a block of semiconductor material on which at least a portion of a functional circuit is fabricated, the functional circuit forming the power amplifier electronics 224 or being part of the power amplifier electronics. In an example embodiment, the semiconductor die 720 can include one or more instances or high power transistor components associated with RF or microwave frequency signal amplification. Examples of such high power transistor components include laterally diffused metal oxide semiconductor (LDMOS) RF power transistors and gallium nitride (GaN) RF power transistors. These types of RF power transistors typically operate with very low drain / collector load impedances (e.g., about 0.5Ω to about 5Ω), and these low load impedances are typically required by best power matching rules. In order to match these low load impedances with the nominal characteristic impedance values ​​of other system components to which the RF power transistors are operably coupled (some of which may be in the range of about 50Ω to about 75Ω), an impedance transformation network can be employed.

[0059] exist Figure 6 In the example of FIG. 7 , the input matching network 730 is operably coupled to an input lug 732 that extends outside the cover 710 to interface with the power amplifier electronics 224 and / or other components of the oven 100. Meanwhile, the output matching network 740 is operably coupled to an output lug 742 that extends outside the cover 710 to interface with the power amplifier electronics 224 and / or other components of the oven 100. The external circuit system to which the input lug 732 and / or the output lug 742 are connected may include one or more printed circuit boards made of high frequency materials and some passive components mounted on the printed circuit boards.

[0060] Each of the input matching network 730 and the output matching network 740 may include a bonding strip 750 and circuitry for forming a corresponding impedance transformation network. Respective instances of the bonding strip 750 may operatively couple the input tab 732 to the circuitry of the impedance transformation network for forming the input matching network 730, couple the circuitry of the impedance transformation network for forming the input matching network 730 to the semiconductor wafer 720, couple the semiconductor wafer 720 to the circuitry of the impedance transformation network for forming the output matching network 740, and couple the circuitry of the impedance transformation network for forming the output matching network 740 to the output tab 742.

[0061] The bonding strip 750 may be formed to include an arcuate section that extends to a plane outside the top surfaces of both the semiconductor wafer 720 and the input and output matching networks 730 and 740. The terminal ends of the bonding strip 750 may extend away from the arcuate section so as to be disposed substantially flat on the pads to which the terminal ends are bonded. The terminal ends may then be bonded using wedge bonding or other suitable techniques. The presence of the arcuate section may ensure that the bonding strip 750 must be longer than the distance between the semiconductor wafer 720 and the wafer on which the input or output matching network 730 or 740 is fabricated. In some cases, the length of the bonding strip 750 may be at least 1.5 times the distance between the semiconductor wafer 720 and the wafer on which the input or output matching network 730 or 740 is fabricated. However, in some cases, other lengths (shorter or longer) are possible.

[0062] Generally, the higher the power and operating frequency used in RF application, the more suitable it is to form the first stage of the output matching network 740 that is physically close to the drain / collector of the semiconductor wafer 720. The goal of achieving physical proximity aims to improve the efficiency of the power amplifier (e.g., optimized use of DC power, reduced heat dissipation, lower junction temperature, and improved device reliability) or the application bandwidth and complexity of other stages of the output matching network 740 (e.g., the size and number of components), and other stages of the output matching network may be added to the outside of the lid 710 of the package to achieve a nominal characteristic impedance in the range of approximately 50 Ω to approximately 75 Ω.

[0063] The first stage of the output matching network 740 (intended for impedance transformation or reactance compensation) can typically be inside the package of the high-power transistor of the RF power amplifier. The input matching network 730 can operate at a limited stress level. Thus, typical geometries and materials can withstand the worst-case scenarios of the device without reliability issues. Therefore, it should be understood at this point that, relative to the worst-case operating conditions, the output matching network 740 and in particular the bonding tape 750 used to connect to the output matching network 740 become limiting components. In particular, when power cycling between high and low power occurs within the RF power amplifier, the thermal stress on the bonding tape 750 operably coupled to the output matching network 740 is typically the highest.

[0064] The output matching network 740 is typically configured to operably couple the output of the semiconductor wafer 720 (i.e., the drain or collector of the active device formed inside the semiconductor wafer 720) to the output tab 742. The output matching network 740 can also be configured to provide compensation for the capacitive reactance of the active device formed in the semiconductor wafer 720 (e.g., in a partial reduction in the first stage). This capacitive reactance can be associated with the equivalent drain-source or collector-emitter capacitance. The compensation provided by the partial reduction in the first stage may be required to reduce the complexity of the further impedance transformation stages employed. The output matching network 740 can also be configured to provide the first stage of impedance transformation. The first stage of impedance transformation may be required to reduce the total number of stages of any external output matching circuit (e.g., the overall size and number of passive components). The output matching network 740 can include passive devices (e.g., capacitors such as ceramic capacitors or MOScaps (metal-oxide semiconductor capacitors)) and connection lines (e.g., including the bonding tape 750). When MOScaps are employed, the capacitors can be made of different sections of the semiconductor (e.g., such that the input matching network 730 and the output matching network 740 each have their own corresponding semiconductor wafer, as shown by the respective rectangular boxes associated in Figure 6 ), or can be embedded in the wafer together with the active device section (e.g., such that both the RF power transistor and the MOScap are diffused and formed in the same semiconductor wafer (i.e., the semiconductor wafer 720)). In each case, the bonding tape 750 may be required to form a suitable topology for the impedance matching network.

[0065] From the above discussion, it can be understood that the output matching network 740 is configured to operate at very low impedance and very high power levels. Therefore, it can be expected that the output matching network 740 experiences very high current values at its interconnections with other components. Thus, it can be expected that any wire connection (e.g., bonding tape 750 or other individual groups of wires for performing the same function) experiences very high levels or RF / microwave currents. The skin effect that causes the RF / microwave current to flow only (or mainly) on the surface of the connecting wire may result in higher thermal stress. In this regard, the connecting wire (or bonding tape 750) needs to be configured to withstand significant stress due to the current density and / or operating temperature.

[0066] For continuous waveform (CW) applications or long pulse applications, the maximum RF power is experienced over a relatively long period of time. In any case, the period of time during which such RF power is experienced is longer than the time constants of the semiconductor wafer 720 and the flange / package 700 of the device. This may cause high temperatures to accumulate within wire segments such as the bonding tape 750 or alternative connecting wires. The high value of the wire temperature can significantly reduce the reliability of the wire segments in the alternative connecting wires due to various phenomena. For example, both the electromigration phenomenon and bonding failure may reduce the reliability. The electromigration phenomenon may occur when the current density and temperature are very high, and this phenomenon may affect the wire due to reduced strength until a failure may occur especially in the weaker segments of the wire. The weaker segments are typically the arcuate portions (or annular portions) or the bonding portions.

[0067] The end points of the wire (e.g., the longitudinal ends) are typically bonded to the components to which they are connected. For example, the bonding tape 750 or other connecting wires for the output matching network 740 can be bonded at one end to the pad at the drain / collector on the semiconductor wafer 720 and at the other end to the output matching network 740. In the case where the temperature difference between the high power operating state (i.e., the on state) and the low power operating state (e.g., the off state) is large, the bonding joint may be a weak point during power cycling (e.g., for long pulse modulation, in which case the power cycles at a low rate with a repetition period of more than 100 milliseconds). Additionally, the above learning procedure should be understood to meet the following conditions: namely, that the power is cycled to a low level after the learning process ends and before the power returns to a high level. This temperature cycling caused by the power cycling subjects the bonding terminals to mechanical stress until the fatigue failure point. The same effect may occur at the bent segments of the connecting wire.

[0068] Figure 7Shows a plan view of a high-power RF / microwave transistor wafer (e.g., semiconductor wafer 720) including a plurality of transistor cells operating in parallel (e.g., an array 800 of transistor cells). The semiconductor wafer 720 includes gate / base (input) conductive rails 810 and drain / collector (output) conductive rails 820 disposed on opposite sides of the array 800. One or more instances of an adhesive tape 750 can be bonded to the gate / base (input) conductive rail 810 and can also be bonded to the input matching network 730. Another instance or another set of instances of the adhesive tape 750 can be bonded to the drain / collector (output) conductive rail 820 and can also be bonded to the output matching network 740. In an example embodiment, an adhesive joint can be formed at the terminal end of the adhesive tape 750 via wedge bonding or other suitable techniques. Wedge bonding can include bonding the terminal end of a wire when the wire extends parallel to the surface of a pad (e.g., at the drain / collector (output) conductive rail) to form a horizontal bond.

[0069] For common RF / microwave power LDMOS or GaN devices, wired connections between internal sections and towards interface tabs can be employed. In conventional devices, fine metal wires are used as the adhesive tape 750. The diameter of the fine metal wires can range from approximately 10 microns up to approximately 100 microns. The material used to form the fine metal wires is typically aluminum alloy (e.g., an aluminum-silicon alloy with a silicon content of approximately 1%), or a corrosion-resistant variant with some nickel. Due to the wafer structure (which typically includes an array of devices on the same wafer), the relatively high total RF and DC current values involved and the geometry of the output conductive rails (e.g., the drain / collector (output) rail 820) on the wafer may result in the use of multiple thin wires to attempt to limit the stress on the connection sections. The higher the frequency, the thinner the wires that are typically should be used. At the same time, higher power means higher DC or RF current. Given the high power levels at higher frequencies and the corresponding power cycling that occurs for RF cooking associated with the oven 100 described herein, the reliability limits of the typical wire bonding techniques described above can be easily reached and the reliability margins can be overcome. Thus, it has been shown that typical aluminum alloy-based materials (even in the case of optimal alloy compositions) have limited strength in a power cycling environment where significant power fluctuations can occur. This behavior severely limits the ability to develop or use high-power RF / microwave LDMOS or GaN transistors in power cycling applications using conventional bonding wires and techniques.

[0070] To improve the reliability and performance of the RF power amplifier of the power amplifier electronics 224 of the oven 100 of the exemplary embodiment, the semiconductor wafer 720 can be operably coupled to the output matching network 740 via the adhesive tape 750 described herein. Thus, for the semiconductor wafer 720 of the exemplary embodiment (on which LDMOS or GaN active devices can be fabricated), a single thin tape can replace multiple aluminum alloy wires to increase strength in a power cycling environment rather than simply making the wire diameter thicker. In this regard, due to the resonant frequencies generated in the larger wires at the bonding and / or arcuate sections, simply making the wire diameter thicker will generally result in poorer performance or at least no significant improvement for the frequencies involved in the oven 100 of the exemplary embodiment. At the same time, the use of the adhesive tape 750 can demonstrate an increase in the number of cycles that can be tolerated in fatigue tests involving high power cycling and high temperature variations without failure. Thus, the use of the adhesive tape 750 is crucial for the performance of high power RF amplifiers used in a power cycling environment. In addition, the use of the adhesive tape 750 enables higher RF power and power cycling resistance during operation. The advantages provided by the adhesive tape 750 are a higher RF fuse current, a lower thermal resistance, and a higher melting point, thus enabling use at higher temperatures. In this regard, the operating temperature will actually be reduced, thereby reducing the temperature drop between the on-cycle and the off-cycle. Additionally, compatibility issues with existing pad sizes and surface pad finishes (low intermetallic growth) can also enhance the value of the adhesive tape 750 as a candidate for further high power LDMOS and GaN transistor development at RF / microwave frequencies. The adhesive tape 750 can be made of the same or different materials (e.g., aluminum, copper, etc.) that can otherwise be used for connecting wires. However, by being formed as the adhesive tape 750, improved performance can be achieved without increasing the space occupied by the adhesive tape 750. In this regard, Figure 7 A top view of the adhesive tape 750 and a series (in this case three) of connecting wires 840 are shown, which could otherwise be used in place of the adhesive tape 750, and the connecting wires are shown in dashed lines at the locations where they would be approximately fixed when switched to using the connecting wires 840.

[0071] Figure 8 A cross-sectional view is shown, which similarly shows the cross-section of one of the adhesive tapes 750, where the dashed lines show the approximate dimensions of the connecting wires 840 that would otherwise be used. Figure 8 The dashed lines on both the adhesive tape 750 and the connecting wires 840 show the approximate depth to which the skin effect penetrates and thus also show the amount of material on which the skin effect is distributed in each alternative. As can be seen from Figure 7 and Figure 8It can be understood that the thickness of the adhesive tape 750 is approximately equal to the diameter of the connection line 840. Therefore, using the adhesive tape 750 does not change the profile of the connection between components. However, the connection lines 840 must be spaced apart from each other transversely by a distance proportional to the diameter of the lines in order to enable wedge bonding. At the same time, the cross-section of the corresponding adhesive tape 750 having a skin effect can be much wider than the sum of the amounts of material where the skin effect occurs on the connection lines 840. Therefore, for the same amount of space occupied by three connection lines 840, the adhesive tape 750 can have more material on which heat diffusion can occur, so that the temperature change (and the resulting temperature for a given power) remains small without changing the resonant characteristics of the adhesive tape 750 and thus not actually increasing the thermal stress or at least achieving a sufficient reduction in thermal stress. The adhesive tape reduces the RF power dissipation and the thermal resistance towards the pads and / or tabs. In this way, the peak temperature of the connection lines is lower. Under power cycling conditions, the on / off temperature drop is reduced and the reliability is greatly improved.

[0072] The adhesive tapes 750 can have stable mechanical properties and can have high reliability at their respective adhesive joints. Therefore, the loop stability of the arcuate section can also be high, and the formation of intermetallic phases in the adhesive tapes 750 can be significantly reduced. The reduced intermetallic growth rate, lower resistance, and lower heat generation of the adhesive tapes 750 (especially relative to an aluminum baseline with a diameter equal to the thickness of the bonding tape 750) can contribute to a reduced increase in resistance over time, and the aging rate of the adhesive tapes 750 is slowed down. The service life of the adhesive tapes 750 can thus be increased, and the service life of the corresponding RF power amplifier and ultimately the oven 100 can also be increased. In an exemplary embodiment, if the diameter of the connection lines 840 is between approximately 10 microns and approximately 100 microns, the thickness of the adhesive tape 750 replacing such lines can be between approximately 10 microns and approximately 100 microns. At the same time, the width of the adhesive tape 750 can be equal to or greater than five times the thickness (e.g., 50 microns to about 500 microns).

[0073] In an exemplary embodiment, an oven may be provided. The oven may include: a cooking chamber configured to receive food; and an RF heating system configured to provide RF energy into the cooking chamber using solid state electronics. The solid state electronics includes power amplifier electronics configured to provide a signal into the cooking chamber via a transmitter assembly, the transmitter assembly being operably coupled to the cooking chamber via a waveguide assembly. The power amplifier electronics may be configured to control the application of RF energy into the cooking chamber based at least in part on a learning program that, when executed, produces a power cycle between high power and low power. The power amplifier electronics may include: a semiconductor wafer on which one or more RF power transistors are fabricated; an output matching network configured to provide impedance matching between the semiconductor wafer and an external component operably coupled to an output tab; and an adhesive tape that is bonded at its terminal ends to operably couple the one or more RF power transistors of the semiconductor wafer to the output matching network. The width of the adhesive tape may be greater than approximately five times the thickness of the bond tape.

[0074] In some embodiments, additional optional features may be included, or the above features may be modified or enhanced. Each of the additional features, modifications, or enhancements may be combined with the above features and / or with each other to practice. Thus, in some embodiments, some, all, or none of the additional features, modifications, or enhancements may be utilized. For example, in some cases, the thickness of the adhesive tape is from about 10 microns to about 100 microns, and wherein, the width of the adhesive tape is from about 50 microns to about 500 microns. In an example embodiment, the adhesive tape may be formed to include an arcuate section that extends out of the plane forming the top surfaces of both the semiconductor wafer and the output matching network. In some cases, the terminal ends of the adhesive tape may be bent from the arcuate section to be substantially parallel to the top surface of each of the semiconductor wafer and the output matching network. In some cases, the terminal ends of the adhesive tape may be bonded to the pad surface of the output conductive rail of the semiconductor wafer and the pad surface of the wafer on which the output matching network is fabricated by wedge bonding. In some cases, the length of the adhesive tape may be at least 1.5 times the distance between the semiconductor wafer and the wafer on which the output matching network is fabricated. In an example embodiment, the power amplifier electronic device may further include an input matching network. Additional examples of adhesive tapes may be provided between the input conductive rail of the semiconductor wafer and the pad surface of the wafer on which the input matching network is fabricated. In some cases, additional corresponding examples of adhesive tapes may be provided between the input tab of the package in which the semiconductor wafer is disposed and the wafer on which the input matching network is fabricated, and between the output tab and the wafer on which the output matching network is fabricated. In an example embodiment, the output matching network may be configured to provide impedance matching between the drain / collector impedance of the semiconductor wafer and about 50Ω to about 75Ω at the output tab.

[0075] Figure 9 A block diagram showing a method of providing internal adhesion within a power amplifier electronic device according to an example embodiment. As Figure 9As shown, the method may include: at operation 900, providing a semiconductor wafer within a package of a power amplifier electronic device, on which one or more RF power transistors are fabricated, the power amplifier electronic device being configured to control the application of radio frequency (RF) energy generated using solid-state electronic devices. The power amplifier electronic device may be configured to control the application of RF energy within a cycle between high power and low power. The method may further include: at operation 910, providing an output matching network configured to provide impedance matching between the semiconductor wafer and an external component operably coupled to an output tab of the package proximate the semiconductor die; and at operation 920, operably coupling one or more RF power transistors of the semiconductor wafer to the output matching network via an adhesive tape. The adhesive tape may have its terminal ends adhered to a respective one of the one or more RF power transistors of the semiconductor wafer and the output matching network. The width of the adhesive tape may be greater than approximately five times the thickness of the adhesive tape.

[0076] Benefiting from the teachings given in the foregoing specification and the associated drawings, those skilled in the art to which these inventions pertain will envision many modifications and other embodiments of the inventions described herein. Accordingly, it is to be understood that the inventions are not limited to the specific embodiments disclosed, and that modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although the foregoing description and associated drawings describe exemplary embodiments in the context of certain exemplary combinations of elements and / or functions, it should be understood that different combinations of elements and / or functions may be provided by alternative embodiments without departing from the scope of the appended claims. In this regard, for example, different combinations of elements and / or functions other than those explicitly described above are also contemplated as some of the appended claims set forth. Where advantages, benefits, or solutions to problems are described herein, it should be understood that such advantages, benefits, and / or solutions may apply to some example embodiments but not necessarily to all example embodiments. Accordingly, any advantages, benefits, or solutions described herein should not be considered critical, required, or essential for all embodiments or for what is claimed herein. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. An oven, comprising: A cooking chamber configured to receive food; And A radio frequency (RF) heating system configured to use solid-state electronics to provide RF energy into the cooking chamber to heat the food, Wherein the solid-state electronics includes power amplifier electronics configured to provide a signal into the cooking chamber via a transmitter assembly, the transmitter assembly being operably coupled to the cooking chamber via a waveguide assembly, Wherein the power amplifier electronics is configured to control the application of RF energy into the cooking chamber at least in part based on a learning program that, when executed, produces a power cycle between high power and low power, Wherein the power amplifier electronics includes: A semiconductor wafer on which one or more RF power transistors are fabricated, An output matching network configured to provide impedance matching between the semiconductor wafer and an external component operably coupled to an output tab, and An adhesive tape that is bonded at its terminal ends to operably couple the one or more RF power transistors of the semiconductor wafer to the output matching network, and Wherein the width of the adhesive tape is greater than five times the thickness of the adhesive tape.

2. The oven according to claim 1, wherein, The thickness of the adhesive tape is from 10 microns to 100 microns, and wherein the width of the adhesive tape is from 50 microns to 500 microns.

3. The oven according to claim 1, wherein, The adhesive tape is formed to include an arcuate section that extends beyond the plane forming the top surfaces of both the semiconductor wafer and the output matching network.

4. The oven according to claim 3, wherein, The terminal ends of the adhesive tape are bent from the arcuate section to be substantially parallel to the top surface of each of the semiconductor wafer and the output matching network.

5. The oven according to claim 1, wherein, The length of the adhesive tape is at least 1.5 times the distance between the semiconductor wafer and the wafer on which the output matching network is fabricated.

6. The oven according to claim 5, wherein, The power amplifier electronics further includes an input matching network, and Wherein additional instances of the adhesive tape are provided between the input conductive traces of the semiconductor wafer and the pad surface of the wafer on which the input matching network is fabricated.

7. The oven according to claim 6, wherein, Additional corresponding instances of the adhesive tape are provided between the input tab of the package in which the semiconductor wafer is disposed and the wafer on which the input matching network is fabricated, and between the output tab and the wafer on which the output matching network is fabricated.

8. The oven according to claim 1, wherein, The output matching network is configured to provide impedance matching between the drain / collector impedance of the semiconductor wafer and 50Ω to 75Ω at the output tab.

9. The oven according to claim 1, wherein, The power amplifier electronics is configured to control the application of RF energy into the cooking chamber at least in part based on a learning program that, when executed, produces a power cycle between high power and low power to determine an effective combination of frequency and phase for applying RF energy to the cooking chamber.

10. A power amplifier electronic device for controlling the application of radio frequency (RF) energy generated using solid-state electronic devices, the power amplifier electronic device being configured to control the application of RF energy within a cycle between high power and low power, the power amplifier electronic device comprising: A semiconductor wafer on which one or more RF power transistors are fabricated; An output matching network configured to provide impedance matching between the semiconductor wafer and an external component operatively coupled to an output tab; And An adhesive tape adhesively bonded at its terminal ends to operatively couple the one or more RF power transistors of the semiconductor wafer to the output matching network, Wherein the width of the adhesive tape is greater than five times the thickness of the adhesive tape.

11. The power amplifier electronic device according to claim 10, wherein, The thickness of the adhesive tape is from 10 microns to 100 microns, and wherein the width of the adhesive tape is from 50 microns to 500 microns.

12. The power amplifier electronic device according to claim 10, wherein, The adhesive tape is formed to include an arcuate section that extends beyond the plane forming the top surfaces of both the semiconductor wafer and the output matching network.

13. The power amplifier electronic device according to claim 12, wherein, The terminal ends of the adhesive tape are bent from the arcuate section to be substantially parallel to the top surface of each of the semiconductor wafer and the output matching network.

14. The power amplifier electronic device according to claim 10, wherein, The length of the adhesive tape is at least 1.5 times the distance between the semiconductor wafer and the wafer on which the output matching network is fabricated.

15. The power amplifier electronic device according to claim 14, wherein, The power amplifier electronic device further includes an input matching network, and Wherein additional instances of the adhesive tape are provided between the input conductive rail of the semiconductor wafer and the pad surface of the wafer on which the input matching network is fabricated.

16. The power amplifier electronic device according to claim 15, wherein, Additional corresponding instances of the adhesive tape are provided between the input tab of the package in which the semiconductor wafer is disposed and the wafer on which the input matching network is fabricated, and between the output tab and the wafer on which the output matching network is fabricated.

17. The power amplifier electronic device according to claim 10, wherein, The output matching network is configured to provide impedance matching between the drain / collector impedance of the semiconductor wafer and 50Ω to 75Ω at the output tab.

18. The power amplifier electronic device according to claim 10, applying RF energy to a cooking chamber based on a learning program, wherein when the learning program is executed, the power amplifier electronic device is configured to control the application of RF energy within a cycle between high power and low power to determine an effective combination of frequencies and phases for applying RF energy to the cooking chamber.

19. A method of coupling components in a power amplifier electronic device, the method comprising: Providing a semiconductor wafer within a package of a power amplifier electronic device, on which one or more RF power transistors are fabricated, the power amplifier electronic device being configured to control the application of radio frequency (RF) energy generated using solid-state electronic devices, the power amplifier electronic device being configured to control the application of RF energy within a cycle between high power and low power; Provide an output matching network configured to provide impedance matching between the semiconductor wafer and an external component operably coupled to an output tab of the package proximate the semiconductor wafer; and Operably couple the one or more RF power transistors of the semiconductor wafer to the output matching network via an adhesive tape that adhesively bonds its terminal ends to a respective one of the one or more RF power transistors of the semiconductor wafer and the output matching network, Wherein the width of the adhesive tape is greater than five times the thickness of the adhesive tape.

20. The method according to claim 19, wherein, The thickness of the adhesive tape is from 10 microns to 100 microns, and wherein the width of the adhesive tape is from 50 microns to 500 microns.

21. The method according to claim 19, wherein, Operably coupling the one or more RF power transistors of the semiconductor wafer to the output matching network via the adhesive tape includes forming the adhesive tape to include an arcuate section that extends out of a plane forming a top surface of both the semiconductor wafer and the output matching network.

22. The method according to claim 21, wherein, Operably coupling the one or more RF power transistors of the semiconductor wafer to the output matching network via the adhesive tape includes forming the adhesive tape such that the terminal ends of the adhesive tape are bent from the arcuate section to be substantially parallel to a top surface of each of the semiconductor wafer and the output matching network.

23. The method of claim 19, applying RF energy to the cooking chamber based on a learning procedure, wherein when the learning procedure is executed, the power amplifier electronics are configured to control the application of RF energy within a cycle between high power and low power to determine an effective combination of frequencies and phases for applying RF energy to the cooking chamber.

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