An inner insulation single tube package structure

Abstract

The utility model discloses a kind of inner insulation single tube packaging structures, including the heat dissipation fin, ceramic insulation layer, carrier stage, semiconductor chip and the plastic package body wrapped in outside from bottom to top are sequentially stacked, resistance temperature sensor for directly monitoring semiconductor chip junction temperature is co-sintered and embedded in the inside of ceramic insulation layer, electrically conductive via is equipped in ceramic insulation layer, hole metal is filled in electrically conductive via, the electrode of resistance temperature sensor is electrically led to the sensor electrode on the upper surface of ceramic insulation layer by hole metal, the beneficial effects of the utility model is that resistance temperature sensor is embedded in ceramic insulation layer by co-sintering process, establishes direct heat conduction path, can realize chip junction temperature directly, accurate and fast monitoring, eliminate temperature measurement error, effectively improve the long-term reliability and stability of temperature monitoring system, solve the problem that traditional single tube packaging cannot integrate temperature sensor due to carrier stage size limitation.

Description

Technical Field

[0001] This utility model relates to the field of power semiconductor technology, and in particular to an internally insulated single-tube package structure. Background Technology

[0002] In the field of single-tube power semiconductor packaging, traditional packaging architectures such as the TO series and DFN series are limited by compact space and high voltage isolation requirements, making it impossible to integrate temperature sensors internally. Therefore, temperature monitoring can only rely on external solutions, such as mounting the sensor on the surface of a heat sink, outside the molding compound, or in a non-die area of ​​the lead frame. This forced spatial isolation, where multiple layers such as ceramic substrate, solder layer, and molding compound exist between the sensor and the chip's heat source, prevents the sensor from directly sensing the chip junction temperature Tj, and only measures the "indirect ambient temperature." For example, in the TO-247 package, even when the sensor is attached to the surface of the heat sink, the temperature difference between its reading and the actual Tj can reach 8-15℃; when placed on the surface of the molding compound, the temperature difference is still 5-10℃, which is insufficient to meet the high-precision data requirements of over-temperature protection and dynamic junction temperature compensation.

[0003] Even more serious is that single-tube packages often operate in high-temperature, high-frequency vibration environments, such as automotive electric drives and industrial frequency converters. Over time, the molding and potting materials undergo irreversible aging, such as shrinkage and cracking, leading to a continuous increase in the contact thermal resistance between the external sensor and the package structure. This further exacerbates monitoring deviations and reduces long-term reliability. At the same time, the internal space of a single tube is extremely compact, and the high-current metal traces of the power circuit, i.e., the stage and lead pins, generate Joule heat, which is easily coupled to the nearby external sensor through thermal conduction, especially under full load. This heat interference from non-chip heat sources causes a serious "decoupling" between the sensor temperature rise and the chip junction temperature. Current single-tube packaging technology cannot solve the temperature measurement deviation and reliability problems caused by traditional single-tube architecture.

[0004] Chinese invention patent application number 202410957176.X discloses an internally insulated through-hole plastic-encapsulated single-tube package structure, comprising a substrate assembly, a chip assembly, and a plastic encapsulator. The substrate assembly includes a ceramic substrate, an inner metal conductive layer, an outer metal conductive layer, a first through-hole, and a second through-hole, which are coaxially arranged. The plastic encapsulator has a third through-hole, which is coaxially arranged with the first through-hole, and the diameter of the third through-hole is smaller than the diameter of the first through-hole. However, this internally insulated through-hole plastic-encapsulated single-tube package structure cannot integrate a temperature sensor internally, resulting in the sensor not being able to directly sense the chip junction temperature. Furthermore, the contact thermal resistance between the external sensor and the package structure continuously increases, further exacerbating monitoring deviations and reducing long-term reliability. It is also susceptible to heat interference from external heat sources, leading to reduced temperature detection accuracy. Summary of the Invention

[0005] The purpose of this invention is to provide an internally insulated single-tube encapsulation structure.

[0006] To achieve the above objectives, the technical solution proposed by this utility model is as follows: An internally insulated single-tube package structure includes a heat sink, a ceramic insulating layer, a wafer stage, a semiconductor chip, and a plastic encapsulation body stacked from bottom to top. A resistance temperature sensor for directly monitoring the junction temperature of the semiconductor chip is co-sintered and embedded inside the ceramic insulating layer. The ceramic insulating layer has conductive through holes filled with metal. The two electrodes of the resistance temperature sensor are electrically led out to the sensor electrodes on the upper surface of the ceramic insulating layer through the metal in the holes.

[0007] The resistance temperature sensor is made of a material that can withstand the high-temperature environment of ceramic co-firing. The material is platinum, tungsten, or a high-temperature resistant metal, or a composite material formed by incorporating high-TCR metal or alloy powder into a ceramic matrix slurry.

[0008] The patterned structure of the resistance temperature sensor is prepared by screen printing and is located in the projection area directly below the semiconductor chip. Its patterned structure is at least one of a strip structure, a serpentine structure, or a parallel structure of multiple strips, so as to be uniformly distributed directly below the chip.

[0009] The number of resistance temperature sensors is multiple, and these multiple resistance temperature sensors are arranged along different areas below the projection area of ​​the semiconductor chip to synchronously collect the real-time temperature of different areas of the chip in order to monitor the uniformity of heat distribution.

[0010] The heat sink is soldered to the first surface of the ceramic insulating layer, the second surface of the ceramic insulating layer is soldered to the wafer stage, and the wafer stage is soldered to the semiconductor chip.

[0011] The beneficial effects of this utility model are: The resistance temperature sensor is embedded in the ceramic insulating layer through a co-sintering process, establishing a direct heat conduction path. This enables direct, accurate, and rapid monitoring of the chip junction temperature, eliminating measurement errors and effectively improving the long-term reliability and stability of the temperature monitoring system. Furthermore, multiple resistance temperature sensors can be deployed in different areas under the chip to simultaneously acquire temperature data from multiple points on the chip, thereby monitoring the uniformity of the chip's heat distribution in real time. It adopts a mature ceramic process route based on tape casting, screen printing, via filling, lamination, and co-sintering, and seamlessly integrates with subsequent standard semiconductor packaging processes such as welding, bonding, and molding, ensuring the manufacturability and consistency of the single-tube package structure. This solves the problem that traditional single-tube packages cannot integrate temperature sensors due to limitations in the size of the wafer stage. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of this utility model; Figure 2 This is a schematic diagram of the cross-section of the screen-printed resistance temperature sensor on the first ceramic sheet, according to Embodiment 4 of this utility model. Figure 3 This is a top view of Embodiment 4 of the present invention, showing the lamination of a first green ceramic sheet and a second green ceramic sheet. Figure 4 This is a top view of the internally insulated single-tube package of the embedded temperature sensor in Embodiment 4 of this utility model; Figure 5 This is a top view of the internally insulated single-tube package of the embedded temperature sensor in Embodiment 5 of this utility model.

[0013] In the diagram: 1. Heat sink; 2. Ceramic insulating layer; 2-1. First green ceramic sheet; 2-2. Second green ceramic sheet; 3. Resistance temperature sensor; 4. Through hole; 5. Stage; 6. Solder; 7. Semiconductor chip; 8. Conductor; 9. Molded enclosure; 10. First pin; 11. Second pin; 12. Third pin; 13. Fourth pin; 14. Sensor positive electrode pad; 15. Sensor negative electrode pad; 16. Chip first pad; 17. Chip second pad; 18. Metal inside the hole. Detailed Implementation

[0014] The present invention will now be described in further detail with reference to the accompanying drawings. Example 1: An internally insulated single-tube package structure includes a heat sink 1, a ceramic insulating layer 2, a die carrier 5, a semiconductor 8 chip 7, and a plastic encapsulation body 9 stacked from bottom to top. A resistance temperature sensor 3 for directly monitoring the junction temperature of the semiconductor 8 chip 7 is co-sintered and embedded inside the ceramic insulating layer 2.

[0015] The ceramic insulating layer 2 has a conductive through hole 4, which is filled with a metal 18. The two electrodes of the resistance temperature sensor 3 are electrically led out to the sensor electrode on the upper surface of the ceramic insulating layer 2 through the metal 18. The sensor electrode includes a positive electrode Pad 14 and a negative electrode Pad 15. The first Pad 16, the second Pad 17, the positive electrode Pad 14, and the negative electrode Pad 15 are connected to the first pin 10, the second pin 11, the third pin 12, and the fourth pin 13 through a conductor 8.

[0016] The resistance temperature sensor 3 is made of a material that can withstand the high temperature environment of ceramic co-firing. The material is platinum, tungsten, or a high-temperature resistant metal, or a composite material formed by incorporating high-TCR metal or alloy powder into a ceramic matrix slurry.

[0017] The patterned structure of the resistance temperature sensor 3 is prepared by screen printing and is located in the projection area directly below the semiconductor chip 7. Its patterned structure is at least one of strip structure, serpentine structure or multiple strip parallel structure, so as to be uniformly distributed directly below the chip. The resistance temperature sensor 3 is uniformly covered and the leads are symmetrically led out, which effectively reduces the temperature measurement error.

[0018] There are multiple resistance temperature sensors 3, which are arranged in different areas below the projection area of ​​the semiconductor chip 7. They are used to synchronously collect the real-time temperature of different areas of the chip to monitor the uniformity of heat distribution. The multiple resistance temperature sensors 3 can effectively shield the influence of the external environment on the temperature detection signal, ensuring the authenticity of the temperature difference data and the reliability of temperature monitoring.

[0019] The heat sink 1 is soldered to the first surface of the ceramic insulating layer 2, the second surface of the ceramic insulating layer 2 is soldered to the substrate 5, and the substrate 5 is soldered to the semiconductor chip 7. A schematic diagram of the overall structure of Embodiment 1 of this utility model is shown below. Figure 1 As shown.

[0020] Example 2: A method for manufacturing an internally insulated single-tube encapsulation structure includes the following steps: S1: Provide the first raw porcelain tile 2-1 and the second raw porcelain tile 2-2; S2: Print resistance paste in the preset area of ​​the first ceramic tile 2-1 and perform the first sintering and curing to form the resistance temperature sensor 3; S3: A through hole 4 is formed at a predetermined position on the second green ceramic sheet 2-2, and a conductor paste is filled into the through hole 4 and then sintered and solidified for the second time to form the metal 18 inside the hole; S4: Align and bond the first green ceramic sheet 2-1 and the second green ceramic sheet 2-2 so that the electrode of the resistance temperature sensor 3 is precisely connected with the corresponding metal 18 in the hole. Then, perform lamination and high-temperature co-sintering to form an integral ceramic insulating layer 2 with the resistance temperature sensor 3 embedded in it. S5: Weld the first surface of the ceramic insulating layer 2 to the heat sink 1, and weld the second surface of the ceramic insulating layer 2 to the carrier stage 5; S6: The semiconductor chip 7 is soldered onto the wafer stage 5 and electrical connections are achieved through interconnection technology; S7: Perform plastic sealing and rib cutting to complete the packaging process.

[0021] In step S1, the first green ceramic sheet 2-1 and the second green ceramic sheet 2-2 are prepared by tape casting process. The ceramic slurry contains inorganic additives for adjusting the sintering temperature. The inorganic additives are at least one of alumina, mullite, silica or nickel powder.

[0022] In step S3, the process for machining the through hole 4 is one of mechanical punching, laser drilling, or photolithography etching. Among them, mechanical punching is formed by one-time stamping using a multi-head die designed based on the position coordinates of the three electrodes of the resistance temperature sensor; Laser drilling uses CO2 lasers, ultraviolet lasers, or green lasers to perform ablation. The photolithography etching process involves patterning the surface of the raw ceramic sheet with photolithography, followed by plasma etching or wet chemical etching to form through holes 4.

[0023] In step S3, the process of filling the through hole 4 with conductor 8 is one of conductive paste sintering, magnetron sputtering or double-sided copper self-filling process. Among them, the conductive paste sintering process involves screen printing conductive paste and then sintering and curing it. The magnetron sputtering process uses a tungsten target as the sputtering source to deposit tungsten pillars inside the through-hole 4. The double-sided copper cladding self-filling process does not pre-fill the holes during the raw ceramic tile stage. Instead, it uses hot-press bonding during the double-sided copper cladding stage to fill and densify the entire through-hole 4-cavity using copper foil material under high temperature and high pressure.

[0024] In step S4, the lamination process is uniaxial lamination or isostatic lamination; Among them, the uniaxial lamination uses a uniaxial hydraulic press equipped with a heating plate to apply pressure along the thickness direction of the green ceramic tile assembly; Isostatic lamination involves vacuum-sealing green ceramic sheets in a high-temperature resistant polymer bag and placing them in an isostatic press, where hydrostatic pressure is applied from all directions using a fluid medium to achieve lamination.

[0025] In step S5, the lead frame is soldered to the second surface of the ceramic insulating layer 2 of the embedded temperature sensor using solder 6. The lead frame includes a stage 5, a first pin 10, a second pin 11, a third pin 12, a fourth pin 13, a sensor positive electrode Pad 14, and a sensor negative electrode Pad 15.

[0026] In step S6, the bottom electrode of semiconductor chip 7 can be brought out through the wafer stage 5.

[0027] Among them, the resistance temperature sensor 3 can withstand the high temperature environment of ceramic co-firing process and can still work normally after sintering. High temperature resistant metals such as platinum and tungsten can be selected as thermistor materials to avoid damage to the resistance characteristics caused by the high temperature of co-firing. Ceramic matrix composite materials can also be used, including but not limited to adding high TCR metal or alloy powder to alumina green ceramic slurry, and adding elements such as silicon to aluminum nitride green ceramic slurry. The resistance temperature sensor 3 is prepared by screen printing process, covering the area below the chip projection area, and is configured to be as evenly distributed as possible under the chip and have a symmetrical lead layout to reduce temperature measurement error. The structure of the resistance temperature sensor 3 includes at least one of the following: strip structure, serpentine structure or multi-strip parallel structure.

[0028] Multiple temperature sensors can be deployed below the projection area of ​​semiconductor chip 7. Temperature sensors can be simultaneously soldered on the wafer stage 5. Multiple temperature sensors are used to simultaneously collect real-time temperature values ​​corresponding to different key areas of the chip. Key areas include current concentration areas, gate or terminal proximity areas, chip center areas, and edge areas. By acquiring temperature data of the corresponding areas, the uniformity of chip thermal distribution, potential overload areas, and thermal stress-related failure modes can be monitored, providing data support for chip thermal management strategies and improving system reliability and service life.

[0029] Solder 6 is selected from Sn-Ag-Cu, Sn-Pb or Au-Sn solder 6 and is used for the connection between semiconductor chip 7 and lead frame. The electrode interconnection process adopts wire bonding process, including gold wire bonding, copper wire bonding or aluminum wire bonding, to realize the electrical connection between the surface electrode of semiconductor chip 7, the positive and negative electrode Pad of temperature sensor and the corresponding pin. The bonding can be completed by thermo-ultrasonic bonding or ultrasonic bonding process.

[0030] The ceramic slurry used in the first raw ceramic sheet 2-1 and the second raw ceramic sheet 2-2 has a ceramic matrix material selected from at least one of alumina, aluminum nitride, boron nitride, magnesium oxide, silicon nitride, beryllium oxide, SiAlON, SiC-based composite materials or multilayer gradient ceramics. The thermal conductivity of the ceramic matrix material is not less than 1 W / (m·K). The ceramic slurry contains inorganic additives to adjust the sintering temperature of the ceramic layer. The inorganic additives are selected from at least one of alumina, mullite, silicon dioxide or nickel powder. Their composition and proportion are set according to the target temperature measurement accuracy and the temperature resistance range of the temperature sensor.

[0031] The casting process includes: ball milling the prepared ceramic slurry, placing the ball-milled slurry in a vacuum degassing device, removing air bubbles under stirring, and coating the degassed slurry onto a continuously moving casting substrate using a doctor blade. The gap between the doctor blade and the casting substrate is set to the required wet film thickness of the green ceramic sheet to control the final thickness of the green ceramic sheet. The final thickness of the green ceramic sheet is determined based on the bus voltage level, the dielectric strength of the ceramic material, and the safety margin factor.

[0032] The green ceramic tile lamination process can be achieved through either uniaxial lamination or isostatic lamination. The uniaxial lamination process uses a uniaxial hydraulic press equipped with a heating plate to apply uniaxial pressure along the thickness direction of the stacked green ceramic tile assembly. The isostatic lamination process involves placing the stacked green ceramic tile assembly into a high-temperature resistant polymer film bag, vacuum sealing it, and then placing it in an isostatic laminator. The static water pressure generated by the heated fluid medium is used to apply pressure to the green ceramic tile assembly from all directions to achieve lamination.

[0033] Among them, the through holes 4 of the second green ceramic sheet 2-2 can be processed by mechanical punching, laser drilling or photolithography etching: mechanical punching is based on the design of a multi-head mold based on the position coordinates of the temperature sensor electrode, and all through holes 4 are formed by punching in one go; laser drilling is performed after precise positioning, and a laser, including but not limited to CO2 laser, ultraviolet laser or green laser, is used to remove material layer by layer by ablation to form through holes 4; the photolithography etching process is to perform a pre-patterned photolithography treatment on the surface of the ceramic insulating layer 2, and then form through holes 4 by chemical etching process. The chemical etching process can be plasma etching based on CF4 / SF6 / CHF3 gas or wet chemical etching based on hot H3PO4 / concentrated H2SO4 / molten NaOH / KOH.

[0034] The via 4 can be filled by conductive paste sintering, magnetron sputtering, or double-sided copper self-filling process: the conductive paste sintering process involves filling the via 4 with a fully stirred conductive paste through screen printing, followed by sintering and curing in an atmosphere-protected sintering furnace; the magnetron sputtering process uses a tungsten target as the sputtering source, and high-energy particles bombard the via 4 to deposit tungsten into the via 4 to form a tungsten pillar; the double-sided copper self-filling process does not pre-fill the via 4 during the green ceramic stage, but tightly attaches the copper foil to the opening end of the ceramic insulating layer 2 during the double-sided copper stage, and performs hot-press bonding under the protection of an inert atmosphere such as nitrogen or argon, using high temperature and high pressure to fill and densify the entire cavity of the via 4 with copper foil material, and forms a conductive via 4 after cooling.

[0035] Example 3: A method for fabricating an internally insulated single-tube encapsulation structure specifically includes the following steps: Step 1: Preparation and pretreatment of raw ceramic sheets: Prepare ceramic powder as the base material, add organic binder, plasticizer and solvent, and make a uniform ceramic slurry by ball milling and stirring. Use the ceramic slurry to make the first raw ceramic sheet 2-1 and the second raw ceramic sheet 2-2 by casting process. Place the raw ceramic sheets in an inert atmosphere for heating and degreasing treatment to complete the pretreatment.

[0036] Step 2: Preparation and curing of resistance temperature sensor 3: Prepare conductor 8 powder, binder and organic carrier, mix them evenly, prepare resistance paste, and use screen printing process to accurately apply the resistance paste to the preset area of ​​the first green ceramic sheet 2-1, control the wet film thickness, place the printed first green ceramic sheet 2-1 in a sintering furnace, and sinter it in an inert atmosphere according to the heating curve to form resistance temperature sensor 3.

[0037] Step 3: Drilling the second green ceramic tile 2-2: Drill holes at the preset positions on the second green ceramic tile 2-2, corresponding to the electrodes of the resistance temperature sensor 3 on the first green ceramic tile 2-1. Clean and remove ceramic debris from the holes, heat and dry to ensure that the inner wall of the holes is dry and free of impurities.

[0038] Step 4: Metal filling and curing in through hole 4: Prepare conductor 8 powder, binder and organic carrier, mix them evenly, and prepare conductor slurry; fill the through hole 4 with conductor slurry, remove excess conductor slurry, place the second green ceramic sheet 2-2 after filling the hole into the sintering furnace, and sinter in an inert atmosphere according to the heating curve to form metal 18 in the hole.

[0039] Step 5: Green ceramic sheet lamination and co-sintering: Place the first green ceramic sheet 2-1 with the side containing the resistance temperature sensor 3 facing upwards, and align it with the second green ceramic sheet 2-2. Ensure that the electrode of the resistance temperature sensor 3 on the first green ceramic sheet 2-1 is precisely aligned with the metal 18 inside the hole of the second green ceramic sheet 2-2. Place the assembled green ceramic sheets in a laminator, and after heating and pressurizing, the two green ceramic sheets are tightly bonded together to form a green ceramic composite layer. Transfer the green ceramic composite layer to a high-temperature sintering furnace and sinter it in an inert atmosphere according to the heating curve to form a structurally stable ceramic layer. At the same time, the resistance temperature sensor 3 and the metal 18 inside the hole are reliably electrically connected.

[0040] Step 6: Welding the ceramic layer to the heat sink 1: Using solder 6, the first surface of the ceramic insulating layer 2 of the embedded resistance temperature sensor 3 is reflow soldered to the heat sink 1 to form an efficient heat conduction path.

[0041] Step 7: Soldering the ceramic layer to the lead frame: Using the same type of solder 6 as in Step 6, the second surface of the ceramic insulating layer 2 is soldered and fixed to the lead frame using a surface mount process. The lead frame includes a substrate 5, a first pin 10, a second pin 11, a third pin 12, a fourth pin 13, and positive and negative electrode pads for the sensor. The bottom electrode of the chip is connected to the substrate 5 through the solder 6 to achieve surface contact. The chip electrode signal is led out through the pins extended from the substrate 5. The electrodes at both ends of the resistance temperature sensor 3 are electrically connected to the positive and negative electrode pads of the sensor on the surface of the ceramic layer through the metal 18 inside the through hole 4.

[0042] Step 8: Interconnection process to achieve electrical connection: The bonding process is used as the interconnection process. The first Pad 16 of the chip is connected to the third pin 12 through the bonding machine, the second Pad 17 of the chip is connected to the second pin 11, and the positive and negative poles of the sensor are connected to the first pin 10 and the fourth pin 13 respectively.

[0043] Step 9: Molding Material Injection and Curing: Fix the assembly completed in Step 8 into a custom mold. Use epoxy resin as the molding material and inject it into the mold cavity using an injection molding machine. Ensure that the epoxy resin completely fills every corner of the mold cavity, wrapping the chip, lead frame, and ceramic layer components of the assembly without any air bubbles or missing resin. Transfer the epoxy resin-injected assembly and the mold together to a curing oven for curing, allowing the epoxy resin to completely cure and form the molding compound 9. The molding compound 9 completely wraps the chip, lead frame, ceramic layer, and interconnect structure of the assembly.

[0044] Step 10: Lead cutting and shaping: Transfer the semi-finished product after molding in step 9 to a fully automatic lead cutting machine. Cut off the connecting ribs and waste edges on the lead frame that connect each packaging unit, and retain the independent pins of each packaging unit. Perform lead pin shaping on the packaged unit after lead cutting. Use a bending die to bend the lead pins to the target angle, and finally form a structurally complete and stable internally insulated single-tube packaged product.

[0045] In step 8, a bonding process is used as the interconnection process, specifically gold wire bonding, copper wire bonding, or aluminum wire bonding.

[0046] Example 4: A method for fabricating an internally insulated single-tube encapsulation structure specifically includes the following steps: Step 1: Preparation and Pretreatment of Green Ceramic Sheets: The ceramic powder formulation uses high-purity aluminum nitride powder as the ceramic matrix, and adds sintering aids, binders, and plasticizers. A mixed solvent of ethanol and toluene is used as the dispersion medium to ensure that the slurry has good rheological properties suitable for casting. In the casting process, the above-mentioned ceramic powder and inorganic additives are first fully mixed and dispersed with an organic carrier in a ball mill to form a uniform and stable slurry. Then, it is coated onto a uniformly moving carrier by a doctor blade of the casting machine to form a wet film. The wet film after casting is dried, and finally, after degreasing and pretreatment, green ceramic sheets are obtained.

[0047] Step 2: Preparation and Curing of Resistance Temperature Sensor 3: A chemically stable conductor powder with good resistance characteristics, such as platinum or tungsten powder, is selected to prepare a resistance paste. The prepared resistance paste is precisely applied to a predetermined area of ​​the first green ceramic sheet 2-1 using a screen printing process. A squeegee is used to scrape across the screen surface at a constant pressure and speed, allowing the paste to pass through the mesh and transfer onto the first green ceramic sheet 2-1. After printing, the first green ceramic sheet 2-1 is placed in a precision sintering furnace and sintered and cured under a flowing inert nitrogen atmosphere, ultimately forming the resistance temperature sensor 3. A cross-sectional view of the screen-printed resistance temperature sensor 3 on the first green ceramic sheet 2-1 in Embodiment 4 of this utility model is shown below. Figure 2 As shown.

[0048] Step 3: Processing of through hole 4 in the second green ceramic sheet 2-2: During the preparation of the second green ceramic sheet 2-2, a hole is drilled directly above the electrode terminal of the resistance temperature sensor 3 to form a vertical interconnection channel. The drilling process adopts a high-precision mechanical punching process, using a punch made of hard alloy material with a precision-ground end face. The punch applies a set impact force along a trajectory perpendicular to the surface of the green ceramic sheet to complete the through punching, thereby forming a microhole with uniform diameter and vertical hole wall. After the punching is completed, the green ceramic sheet is transferred to an ultrasonic cleaning device and cleaned with deionized water as the cleaning medium to thoroughly remove ceramic debris and contaminants remaining in and around the hole. Subsequently, the cleaned green ceramic sheet is placed in a clean drying oven and heated to ensure that the inner wall of the hole is completely dry and free of any impurities, finally obtaining through hole 4.

[0049] Step 4: Metallization and Electrical Connection of Through Holes 4: High-purity tungsten metal powder is used as the conductive paste. The prepared conductive paste is then filled into the through holes 4 of the second green ceramic sheet 2-2 using a precision scraper. Under the pressure and movement of the scraper, the paste is fully pressed in and completely fills the entire through hole 4. After filling, a flexible scraper or a clean roller is used to move along the surface of the green ceramic sheet to remove excess paste remaining outside the hole. Finally, the second green ceramic sheet 2-2 with the hole-filling treatment is transferred to a high-temperature sintering furnace and sintered under the protection of flowing pure nitrogen or nitrogen-hydrogen mixed reducing atmosphere to form vertical interconnect metal conductors 8.

[0050] Step 5: Green Ceramic Sheet Lamination and Co-sintering: Precise alignment is performed. The side of the first green ceramic sheet 2-1 with the resistive pattern faces upwards, while the side of the second green ceramic sheet 2-2 with the tungsten metal paste through-hole 4 faces downwards. Using the positioning hole as a reference, ensure that the two electrode endpoints of the resistance temperature sensor 3 on the first green ceramic sheet 2-1 are precisely aligned and physically contacted with the corresponding metal 18 in the hole on the second green ceramic sheet 2-2 in three-dimensional space. The aligned green ceramic sheet assembly is then moved into a hot press laminator for hot pressing, tightly bonding it into a structurally complete multilayer green body. Finally, this laminated green ceramic composite layer is moved to a high-temperature sintering furnace for co-firing under an inert atmosphere to form a ceramic layer. The top view of the lamination of the first green ceramic sheet 2-1 and the second green ceramic sheet 2-2 in Embodiment 4 of this utility model is shown below. Figure 3 As shown.

[0051] Step 6: Welding the ceramic layer to the heat sink 1: Using Sn-Ag-Cu solder 6, the first surface of the ceramic insulating layer 2 of the embedded resistance temperature sensor 3 is reflow soldered to the heat sink 1 to form an efficient heat conduction path.

[0052] Step 7: Soldering the ceramic layer to the lead frame: Using the same Sn-Ag-Cu solder 6 as in Step 6, the second surface of the ceramic insulating layer 2 is soldered and fixed to the lead frame using a surface mount process. The lead frame includes a substrate 5, a first pin 10, a second pin 11, a third pin 12, a fourth pin 13, and positive and negative electrode pads for the sensor. The bottom electrode of the semiconductor chip 7 is connected to the substrate 5 through the solder 6 to achieve surface contact. The electrode signal of the semiconductor chip 7 is led out through the pins extended from the substrate 5. The electrodes at both ends of the resistance temperature sensor 3 are electrically connected to the positive and negative electrode pads of the sensor on the surface of the ceramic insulating layer 2 through the metal 18 inside the through hole 4.

[0053] Step 8: Interconnection process to achieve electrical connection: Connect the first Pad 16 of the chip to the third pin 12 through a bonding machine, connect the second Pad 17 of the chip to the second pin 11, and connect the positive and negative Pads of the sensor to the first pin 10 and the fourth pin 13 respectively.

[0054] Step 9: Molding Material Injection and Curing: Fix the assembly completed in Step 8 into a custom mold. Use epoxy resin as the molding material and inject it into the mold cavity using an injection molding machine. Ensure that the epoxy resin completely fills every corner of the mold cavity, wrapping the chip, lead frame, and ceramic insulation layer 2 of the assembly without any air bubbles or missing glue. Transfer the epoxy resin-injected assembly and the mold together to a curing oven for curing, so that the epoxy resin is completely cured to form the molding body 9. The molding body 9 completely wraps the chip, lead frame, ceramic insulation layer 2, and interconnect structure of the assembly.

[0055] Step 10: Lead Cutting and Shaping: The semi-finished product after molding in Step 9 is transferred to a fully automatic lead cutting machine. The connecting ribs and waste edges of each packaging unit on the lead frame are cut off, retaining the independent pins of each packaging unit. The lead pins of the packaged unit after lead cutting are formed by bending the lead pins to the target angle using a bending die, finally forming a structurally complete and stable internally insulated single-tube packaged product. The top view of the internally insulated single-tube packaged product with embedded temperature sensor in Embodiment 4 of this utility model is shown below. Figure 4 As shown.

[0056] Example 5 A method for fabricating an internally insulated single-tube encapsulation structure specifically includes the following steps: Based on Embodiment 4, keeping the remaining steps unchanged, the positive electrode Pad14 and negative electrode Pad15 of the temperature sensor in step 7 are directly extended into pins, and the first Pad16 of the chip in step 8 is connected to the third pin 12, and the second Pad17 of the chip is connected to the second pin 11. The top view of the internally insulated single-tube package of the embedded temperature sensor in Embodiment 5 of this utility model is shown below. Figure 5 As shown.

[0057] Working principle: The package uses ceramic insulating material with embedded temperature sensing elements to achieve electrical isolation between the chip electrodes and the metal heat sink 1 on the back of the package. This avoids the risk of the heat sink becoming electrified due to damage, contamination or aging of the insulating pad in traditional single-tube packages, significantly improving the electrical safety performance of the system. At the same time, it breaks through the technical bottleneck of traditional structures that are difficult to integrate temperature sensors due to the size constraints of the carrier stage 5. With the help of the extremely short heat conduction path between the sensor and the chip, high-precision and fast-response detection of the junction temperature of the power chip is achieved, effectively eliminating the measurement error generated during the temperature rise decoupling process.

[0058] The beneficial effects of this invention are that the resistance temperature sensor is embedded in the ceramic insulating layer through a co-sintering process, establishing a direct heat conduction path. This enables direct, accurate, and rapid monitoring of the chip junction temperature, eliminating temperature measurement errors and effectively improving the long-term reliability and stability of the temperature monitoring system. Furthermore, multiple resistance temperature sensors can be deployed in different areas under the chip to simultaneously acquire temperature data from multiple points on the chip, thereby monitoring the uniformity of the chip's heat distribution in real time. It adopts a mature ceramic process route based on tape casting, screen printing, via filling, lamination, and co-sintering, and seamlessly integrates with subsequent welding, bonding, and molding standard semiconductor packaging processes, ensuring the manufacturability and consistency of the single-tube package structure. This solves the problem that traditional single-tube packages cannot integrate temperature sensors due to limitations in the size of the wafer stage.

[0059] The above description details one embodiment of the present utility model, but it is merely a preferred embodiment and should not be construed as limiting the scope of the present utility model. All equivalent variations and improvements made within the scope of the present utility model application should still fall within the patent coverage of the present utility model.

Claims

1. An internally insulated single-tube encapsulation structure, comprising a heat sink (1), a ceramic insulating layer (2), a wafer stage (5), a semiconductor chip (7), and a plastic encapsulation body (9) stacked sequentially from bottom to top, characterized in that: A resistance temperature sensor (3) for directly monitoring the junction temperature of the semiconductor chip (7) is co-sintered and embedded inside the ceramic insulating layer (2). The ceramic insulating layer (2) has a conductive through hole (4) and the conductive through hole (4) is filled with a metal (18). The two electrodes of the resistance temperature sensor (3) are electrically led out through the metal (18) to the sensor electrode on the upper surface of the ceramic insulating layer (2).

2. The internally insulated single-tube encapsulation structure as described in claim 1, characterized in that, The resistance temperature sensor (3) is made of a material that can withstand the high temperature environment of ceramic co-firing. The material is platinum, tungsten, or a high-temperature resistant metal, or a composite material formed by incorporating high-TCR metal or alloy powder into a ceramic matrix slurry.

3. The internally insulated single-tube encapsulation structure as described in claim 1 or 2, characterized in that, The patterned structure of the resistance temperature sensor (3) is prepared by screen printing and is located in the projection area directly below the semiconductor chip (7). Its patterned structure is at least one of strip structure, snake structure or multiple strip parallel structure, so as to be uniformly distributed directly below the chip.

4. The internally insulated single-tube encapsulation structure as described in claim 1, characterized in that, The number of the resistance temperature sensors (3) is multiple. The multiple resistance temperature sensors (3) are arranged in different areas below the projection area of ​​the semiconductor chip (7) to synchronously collect the real-time temperature of different areas of the chip to monitor the uniformity of heat distribution.

5. The internally insulated single-tube encapsulation structure as described in claim 1, characterized in that, The heat sink (1) is soldered to the first surface of the ceramic insulating layer (2), the second surface of the ceramic insulating layer (2) is soldered to the substrate (5), and the substrate (5) is soldered to the semiconductor chip (7) using solder (6).

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