Manufacturing method of enhanced chip-type laminated filter

Abstract

The invention discloses a manufacturing method of an enhanced chip-type laminated filter, which belongs to the technical field of laminated filter preparation, and comprises the following steps: selecting MLCC raw materials; ball-milling the raw materials; casting to form an MLCC ceramic green tape; cutting into raw ceramic chips; opening holes in the raw ceramic chip; copper paste printing; laminating to form a Bar block; isostatic pressing treatment; discharging glue; performing MLCC sintering; sand blasting; chamfering is conducted; performing MLCC end capping; burning the end of the MLCC; electroplating is conducted; and testing and summing. Microcracks and holes in the device can be reduced, the insulation resistance between the leading-out ends of the device is enhanced, and the failure ratio of the device caused by reduction of the insulation resistance is reduced.

Description

Technical Field

[0001] This invention belongs to the field of stacked filter fabrication technology, specifically relating to a method for fabricating an enhanced chip stacked filter. Background Technology

[0002] With the development of electronic information technology, chip-type multilayer filters are widely used in various fields such as computers, communications, automotive electronics, and military. In chip-type multilayer filter components, the IN, OUT, and GND terminals are not always connected. Any two connected terminals are interconnected through via layers and internal electrode layers to form a conductive structure. The non-conductive terminals are blocked by microwave dielectric ceramics, forming an open circuit. The insulation resistance and withstand voltage of the non-conductive terminals can break down or decrease in insulation resistance under different application scenarios. This can lead to device failure, affecting customer use. Therefore, manufacturers must improve the insulation resistance and withstand voltage of their devices to meet market demands.

[0003] Existing chip-type multilayer filter devices are monolithic structures composed of internal electrodes, a ceramic body, and external electrodes. The internal electrode material is silver, and its main function is to form a series and parallel structure of inductors and capacitors to filter signals. The product is manufactured using low-temperature co-fired ceramic technology. The ceramic body is the overall framework of the filter and serves as the filling medium for the internal electrodes. The ceramic body is sintered at a low temperature (around 900℃). The internal ceramic medium may have defects such as microcracks and pores, which can lead to a decrease in insulation resistance or short circuits. Consequently, the product may fail during use and fail to meet electrical performance specifications. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for manufacturing an enhanced chip-type stacked filter, which reduces the occurrence of microcracks and holes inside the device, enhances the insulation resistance between the device leads, and reduces the proportion of device failures caused by a decrease in insulation resistance.

[0005] The technical solution adopted in this invention is as follows:

[0006] A method for fabricating an enhanced chip stacked filter, the method comprising the following steps:

[0007] Step 1: MLCC raw material preparation: Prepare MLCC raw materials;

[0008] Step 2, ball milling: The raw materials mixed in Step 1 are ball milled to obtain a slurry. The ball milling parameters are: rotation speed 250 rpm, ball milling for 18 hours.

[0009] Step 3, Casting: The ball milling slurry obtained in Step 2 is used to prepare MLCC ceramic green ceramic tapes of a set thickness on PET film by scraping or waterfall casting.

[0010] Step 4: Cutting: Cut the MLCC ceramic green ceramic tape prepared in step 3 into green ceramic pieces of a set size;

[0011] Step 5, Hole making: A high-energy multi-laser beam is emitted by a laser oscillator and transmitted through a specific optical system to the designated position of the green ceramic sheet cut from the MLCC ceramic green ceramic tape in step 4. The green ceramic sheet is burned and vaporized to form small holes. Holes of a set size are made at the designed positions on the green ceramic sheet by laser hole making.

[0012] Step 6, Copper paste printing: Fill the holes of the MLCC green ceramic sheet cut from the MLCC green ceramic tape in step 5 with copper paste by electrode printing. The thickness of the copper paste is 3~5um.

[0013] Step 7, Stacking: The green ceramic sheet and blank green ceramic sheet from Step 6, with the printed electrode pattern, are stacked neatly layer by layer according to the structure of the filter under set temperature and pressure to form a Bar block of set thickness.

[0014] Step 8, Isostatic pressing: The Bar block from step 7 is densified by isostatic pressing to form a blank with a set strength and tight bonding.

[0015] Step 9, Degumming: Using heating equipment, the blank obtained in step 8 is first degummed at a temperature below 500°C.

[0016] Step 10, MLCC sintering: The debinding preform is sintered in a sintering device at a temperature of 1100~1300℃ for ≥50min, with a hydrogen content of 0.4~1.5% and an oxygen content of 0ppm, to prepare a chip component with set electrical characteristics.

[0017] Step 11, Sandblasting: Insert the components into the JIG board, and use a dry blasting machine to spray dust to rub the product surface, so that the electrodes are fully exposed;

[0018] Step 12, Chamfering: Grind the edges and corners of the ceramic body of the component;

[0019] Step 13, MLCC end capping: Coating the IN / OUT / GND lead electrodes of the product with copper end paste to prepare the inner layer of the component end electrodes;

[0020] Step 14, MLCC end sintering: The end-sealed product from step 13 is sintered under a protective atmosphere to form a tight connection between the external electrode and the ceramic body (internal electrode).

[0021] Step 15, Electroplating: Electroplating is a method to plate nickel and tin layers onto the copper outer electrodes at both ends of the product.

[0022] Step 16, Testing: Use a network analyzer to test the electrical performance of the electroplated device;

[0023] Step 17: Screening: Screen the products tested in Step 16. Those that meet the electrical performance indicators and reliability requirements are qualified products.

[0024] Step 18, Tapeing: Package the product in the carrier tape according to the set rules.

[0025] Furthermore, the MLCC raw materials include: MLCC ceramic powder: 53.75wt%, solvent: 28.81wt%, dispersant: 2.15wt%, binder: 13.31wt%, and plasticizer: 1.98wt%.

[0026] The beneficial effects of this invention are as follows: Compared with the prior art, this invention replaces the LTCC ceramic powder with microwave dielectric ceramic powder used in specific MLCC products, and performs device model design and simulation optimization to meet certain electrical performance indicators. Then, it uses the internal electrode paste of MLCC products to achieve co-firing matching between the internal electrode paste and the ceramic material. Production is carried out according to MLCC process technology, which reduces the occurrence of microcracks and pores inside the device. This produces an in-situ replacement of LTCC products based on MLCC process with insulation resistance comparable to that of MLCC products. Ultimately, this enhances the insulation resistance between the device leads and reduces the proportion of device failures caused by a decrease in insulation resistance. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the filter structure;

[0028] Figure 2 This is a diagram showing the correspondence between the internal electrodes in layers 4 to 8 of the filter configuration;

[0029] Figure 3 This is a diagram showing the correspondence between the internal electrodes in layers 8 to 12 of the filter configuration;

[0030] Figure 4 This is a diagram showing the correspondence between the internal electrodes in layers 12 to 16 of the filter configuration;

[0031] Figure 5 This is a diagram showing the correspondence between the electrodes in layers 16-20 of the filter configuration;

[0032] Figure 6 This is a diagram showing the correspondence between the electrodes in layers 20-24 of the filter configuration;

[0033] Figure 7 This is a flowchart illustrating a method for fabricating an enhanced chip stacked filter.

[0034] Figure 8 Defect diagram of stacked filters fabricated using MLCC process;

[0035] Figure 9 Defect diagram of a stacked filter fabricated using the LTCC process. Detailed Implementation

[0036] The present invention will be further described below with reference to specific embodiments.

[0037] Terminology Explanation: LTCC: Low Temperature Co-Fired Ceramics;

[0038] MLCC: Multilayer Ceramic Capacitor.

[0039] Insulation resistance: The ability of electrical equipment to isolate current between two electrodes or dielectrics. It is defined as the current flowing through the insulator under a unit voltage and is usually expressed in ohms (Ω). Higher insulation resistance can ensure the safety and stability of the equipment.

[0040] like Figure 1 As shown, the components described in the filter design scheme are divided into 28 logic modules, namely left and right lead electrodes and left and right end electrodes, ground electrode, inductor coil layer, capacitor layer, through-hole conductive pillar, long through-hole conductive pillar, ceramic substrate, etc.

[0041] Module Introduction:

[0042] Logical structure diagram as follows Figure 1 As shown: An electronic component has a hexahedral structure, having a top surface A, a bottom surface B, a side surface C, a side surface D, a front surface F, and a back surface E. The top surface A is parallel to the bottom surface B, the side surface C is parallel to the side surface D, and the front surface F is parallel to the back surface E. The parallel surfaces of the top surface A and bottom surface B, the side surface C and side surface D, and the front surface F and back surface E are perpendicular to each other, forming an X, Y, and Z coordinate system.

[0043] Layers 4-17 are inductor coil layers; layers 18, 19, 20, 21, 22, 23, and 24 are capacitor layers; layer 27 is a long through-hole conductive post responsible for interlayer conduction; layers 26 and 28 are the upper and lower connection layers, respectively, responsible for connecting the long through-hole conductive posts in series; layer 25 is a microwave dielectric ceramic. All of the above parts typically use microwave dielectric ceramic as the substrate and form the main structure of the component; layers 5, 19, 22, and 23 are the IN / OUT / GND leads, responsible for outward conduction; these five are typically conductive copper / nickel circuits, connected via... Figure 1The connection methods are combined to form the inductors and capacitors in the circuit design diagram. 1, 2, and 3 are the IN / OUT and GND terminals, respectively, and are mainly composed of three parts: an inner copper or nickel layer, primarily responsible for connecting to the internal circuitry and adhering to the substrate to form a stable connection; a middle copper layer, primarily responsible for connecting the copper / nickel layer to the outermost tin layer; and an outermost tin layer, primarily responsible for SMT soldering. All of these parts together constitute the components described in this patent design scheme.

[0044] in, Figure 2 Device structure Figures 4-8 Diagram showing the correspondence between electrodes within the layer. Figure 3 Device structure Figure 8~1 Correspondence diagram of the two inner electrodes. Figure 4 This is a diagram showing the correspondence between the electrodes in layers 12-16 of the device structure. Figure 5 This is a diagram showing the correspondence between the electrodes in layers 16-20 of the device structure. Figure 6 This is a diagram showing the correspondence between the electrodes in layers 20-24 of the device structure; the components are combined according to the above correspondence to form... Figure 1 The structure.

[0045] Example 1: A method for fabricating an enhanced chip stacked filter, the method comprising the following steps:

[0046] Step 1: MLCC raw material preparation: MLCC ceramic powder: 53.75wt%, solvent: 28.81wt%, dispersant: 2.15wt%, binder: 13.31wt%, plasticizer: 1.98wt%; see Table 1 for detailed formula.

[0047] Step 2, Ball milling: The raw materials mixed in Step 1 are ball milled to obtain a slurry. The ball milling parameters are: speed 250 rpm, ball milling for 18 hours (the first ball milling is 6 hours, and the second ball milling is 12 hours. The first ball milling is to mix: powder + dispersant + solvent, and the second ball milling is to mix: slurry + binder + plasticizer. The first ball milling is mainly for dispersing, and the second ball milling is to increase the plasticizing effect of organic matter and give the slurry a certain plasticity. The two ball millings effectively avoid the problem of possible agglomeration of dispersant, plasticizer and binder).

[0048] The slurry was ball-milled twice according to the slurry formula in Table 1.

[0049] Table 1 MLCC slurry formulation in Example 1

[0050]

[0051] Step 3, Casting: The ball milling slurry obtained in Step 2 is used to prepare MLCC ceramic green ceramic tapes of a set thickness on PET film by scraping or waterfall casting.

[0052] Step 4: Cutting: Cut the MLCC ceramic green ceramic tape prepared in step 3 into green ceramic pieces of a set size;

[0053] Step 5, Hole making: A high-energy multi-laser beam is emitted by a laser oscillator and transmitted through a specific optical system to the designated position of the green ceramic sheet cut from the MLCC ceramic green ceramic tape in step 4. The green ceramic sheet is burned and vaporized to form small holes. Holes of a set size are made at the designed positions on the green ceramic sheet by laser hole making.

[0054] Step 6, Copper paste printing: Fill the holes of the MLCC green ceramic sheet cut from the MLCC green ceramic tape in step 5 with copper paste by electrode printing. The thickness of the copper paste is 3~5um.

[0055] Step 7, Stacking: The green ceramic sheet and blank green ceramic sheet from Step 6, with the printed electrode pattern, are stacked neatly layer by layer according to the structure of the filter under set temperature and pressure to form a Bar block of set thickness.

[0056] Step 8, Isostatic pressing: The Bar block from step 7 is densified by isostatic pressing to form a blank with a set strength and tight bonding.

[0057] Step 9, Debonding: Using heating equipment such as a box furnace, the green body obtained in step 8 is first debonded at a temperature below 500°C to remove the adhesive and other organic substances in the product, so as to prevent the rapid volatilization of organic substances during sintering from causing product delamination and cracking.

[0058] Step 10, MLCC sintering: The debinding preform is sintered in a bell furnace (tunnel furnace) or other sintering equipment at a temperature of 1100~1300℃ for ≥50min, with a hydrogen content of 0.4~1.5% and an oxygen content of 0ppm, to prepare a chip component with set electrical characteristics.

[0059] Step 11, Sandblasting: Insert the components into the JIG board, and use a dry blasting machine to spray dust to rub the product surface, so that the electrodes are fully exposed;

[0060] Step 12, Chamfering: Grind the edges of the ceramic body of the component to allow the terminal electrode paste to adhere to the ceramic body surface;

[0061] Step 13, MLCC end capping: Coating the IN / OUT / GND lead electrodes of the product with copper end paste to prepare the inner layer of the component end electrodes;

[0062] Step 14, MLCC end sintering: The end-sealed product from step 13 is sintered under a protective atmosphere to form a tight connection between the external electrode and the ceramic body (internal electrode).

[0063] Step 15, Electroplating: Electroplating is a method to plate nickel and tin layers onto the copper outer electrodes at both ends of the product.

[0064] Step 16, Testing: Use a network analyzer to test the electrical performance of the electroplated device;

[0065] Step 17: Screening: Screen the products tested in Step 16. Those that meet the electrical performance indicators and reliability requirements are qualified products.

[0066] Step 18, Tape and Reel: Package the product in carrier tape (paper tape or plastic tape) according to the set rules for customer surface mount technology (SMT) production;

[0067] Step 19, Packaging / Shipping: Print labels according to customer requirements, pack and seal the boxes.

[0068] By replacing the LTCC ceramic powder with the microwave dielectric ceramic powder used in specific MLCC products, and optimizing the device model design through simulation to meet certain electrical performance indicators, and then using the internal electrode paste of the MLCC product to achieve co-firing matching between the internal electrode paste and the ceramic material, and producing according to MLCC process technology, the occurrence of microcracks and voids inside the device is reduced. This produces an in-situ replacement of LTCC products based on MLCC process with insulation resistance comparable to that of MLCC products. Ultimately, this enhances the insulation resistance between the device leads and reduces the proportion of device failures due to decreased insulation resistance.

[0069] Comparative Example: A method for fabricating an enhanced chip stacked filter, the method comprising the following steps:

[0070] Step 1: LTCC raw material preparation: LTCC ceramic powder: 49.69wt%, solvent: 36.05wt%, dispersant: 2.41wt%, binder: 8.95wt%, plasticizer: 2.91wt%; see Table 2 for detailed formula.

[0071] Step 2, ball milling: The mixed raw materials in Step 1 are ball milled separately to obtain slurry. The ball milling parameters are: rotation speed 250 rpm, ball milling for 18 hours (the first ball milling is 6 hours, the second ball milling is 12 hours, the same as the ball milling method in Example 1, and ball milling is carried out according to Table 2).

[0072] Table 2 LTCC slurry formulations in comparative examples

[0073]

[0074] Step 3, Casting: The slurry obtained in Step 2 is used to prepare LTCC ceramic green ceramic tapes of a set thickness on PET film by scraping or waterfall casting.

[0075] Step 4, Cutting: Cut the LTCC ceramic green ceramic strip prepared in Step 3 into green ceramic pieces of a set size that can be processed.

[0076] Step 5, Hole making: A high-energy multi-laser beam is emitted by a laser oscillator and transmitted through a specific optical system to the designated position of the green ceramic sheet cut by the LTCC ceramic green ceramic belt in step 4. The green ceramic sheet is burned and vaporized to form small holes. Holes of a set size are made at the designed positions on the green ceramic sheet by laser hole making.

[0077] Step 6, Silver paste printing: Fill the holes of the LTCC green ceramic sheet cut from the LTCC green ceramic tape in step 5 with silver paste by electrode printing. The thickness of the silver paste is 8~12um.

[0078] Step 7, Stacking: The green ceramic sheet and blank green ceramic sheet from Step 6, with the printed electrode pattern, are stacked neatly layer by layer according to the structure of the filter under set temperature and pressure to form a Bar block of set thickness.

[0079] Step 8, Isostatic pressing: The Bar block from step 7 is densified by isostatic pressing to form a blank with a set strength and tight bonding.

[0080] Step 9, Debonding: Use heating equipment such as a box furnace to debond the green body at a temperature below 500°C to remove the adhesive and other organic substances in the product, so as to prevent the rapid volatilization of organic substances during sintering from causing product delamination and cracking.

[0081] Step 10, LTCC sintering: The debinded green body is sintered in air atmosphere at 880~900℃ for ≥50min using sintering equipment such as mesh belt furnace or box furnace;

[0082] Step 11, Sandblasting: Insert the components into the JIG board, and use a dry blasting machine to spray dust to rub the product surface, so that the electrodes are fully exposed;

[0083] Step 12, Chamfering: Grind the edges of the ceramic body of the component to allow the terminal electrode paste to adhere to the ceramic body surface;

[0084] Step 13, LTCC end capping: Apply silver end paste to the IN / OUT / GND lead electrodes of the product to prepare the inner layer of the component end electrodes;

[0085] Step 14, LTCC Sintering: The end-sealed product from Step 13 is sintered in an air atmosphere to form a tight connection between the outer electrode and the ceramic body (inner electrode).

[0086] Step 15, Electroplating: Electroplating is a method to plate nickel and tin layers onto the copper outer electrodes at both ends of the product.

[0087] Step 16, Testing: Use a network analyzer to test the electrical performance of the electroplated device;

[0088] Step 17: Screening: Screen the products tested in Step 16. Those that meet the electrical performance indicators and reliability requirements are qualified products.

[0089] Step 18, Tape and Reel: Package the product in carrier tape (paper tape or plastic tape) according to the set rules for customer surface mount technology (SMT) production;

[0090] Step 19, Packaging / Shipping: Print labels according to customer requirements, pack and seal the boxes.

[0091] Table 3 Comparison of voltage withstand capabilities of devices manufactured using MLCC and LTCC processes in Example 1 and the comparative example, respectively.

[0092]

[0093] Table 4 Comparison of breakdown voltage capabilities of devices manufactured using MLCC and LTCC processes in Example 1 and the comparative example.

[0094]

[0095] A comparison of internal ceramic defects in devices manufactured using MLCC and LTCC processes is shown below. Figure 8 and Figure 9 .

[0096] The core of this invention is the integration of MLCC production filter components. Based on the mature LTCC simulation model, the raw materials are changed, using ceramic materials and internal electrode raw materials of MLCC, which have the characteristics of high-temperature sintering (1100~1300℃).

[0097] The copper / nickel paste printed on the sheet is 3~5um thick, which reduces material defects caused by the height difference of the internal electrodes on the sheet.

[0098] This invention utilizes MLCC ceramic materials and process technology to achieve in-situ replacement of LTCC products based on MLCC process, resulting in a denser ceramic substrate structure for the manufactured chip-type multilayer filter, reducing the proportion of microcracks and pores in the ceramic between filling electrodes, increasing the insulation resistance of the device, and significantly increasing the device's withstand voltage and high reliability.

Claims

1. A method for fabricating an enhanced chip-type stacked filter, characterized in that, The method includes the following steps: Step 1: MLCC raw material preparation: Prepare MLCC raw materials; Step 2, ball milling: The raw materials mixed in Step 1 are ball milled to obtain a slurry. The ball milling parameters are: rotation speed 250 rpm, ball milling for 18 hours. Step 3, Casting: The ball milling slurry obtained in Step 2 is used to prepare MLCC ceramic green ceramic tapes of a set thickness on PET film by scraping or waterfall casting. Step 4: Cutting: Cut the MLCC ceramic green ceramic tape prepared in step 3 into green ceramic pieces of a set size; Step 5, Hole making: A high-energy multi-laser beam is emitted by a laser oscillator and transmitted through a specific optical system to the designated position of the green ceramic sheet cut from the MLCC ceramic green ceramic tape in step 4. The green ceramic sheet is burned and vaporized to form small holes. Holes of a set size are made at the designed positions on the green ceramic sheet by laser hole making. Step 6, Copper paste printing: Fill the holes of the MLCC green ceramic sheet cut from the MLCC green ceramic tape in step 5 with copper paste by electrode printing. The thickness of the copper paste is 3~5um. Step 7, Stacking: The green ceramic sheet and blank green ceramic sheet from Step 6, with the printed electrode pattern, are stacked neatly layer by layer according to the structure of the filter under set temperature and pressure to form a Bar block of set thickness. Step 8, Isostatic pressing: The Bar block from step 7 is densified by isostatic pressing to form a blank with a set strength and tight bonding. Step 9, Degumming: Using heating equipment, the blank obtained in step 8 is first degummed at a temperature below 500°C. Step 10, MLCC sintering: The debinding preform is sintered in a sintering device at a temperature of 1100~1300℃ for ≥50min, with a hydrogen content of 0.4~1.5% and an oxygen content of 0ppm, to prepare a chip component with set electrical characteristics. Step 11, Sandblasting: Insert the components into the JIG board, and use a dry blasting machine to spray dust to rub the product surface, so that the electrodes are fully exposed; Step 12, Chamfering: Grind the edges and corners of the ceramic body of the component; Step 13, MLCC end capping: Coating the IN / OUT / GND lead electrodes of the product with copper end paste to prepare the inner layer of the component end electrodes; Step 14, MLCC end sintering: The end-sealed product from step 13 is sintered under a protective atmosphere to form a tight connection between the external electrode and the ceramic body. Step 15, Electroplating: Electroplating is a method to plate nickel and tin layers onto the copper outer electrodes at both ends of the product. Step 16, Testing: Use a network analyzer to test the electrical performance of the electroplated device; Step 17: Screening: Screen the products tested in Step 16. Those that meet the electrical performance indicators and reliability requirements are qualified products. Step 18, Tapeing: Package the product in the carrier tape according to the set rules.

2. The method for fabricating an enhanced chip-type stacked filter according to claim 1, characterized in that, MLCC raw materials include: MLCC ceramic powder: 53.75wt%, solvent: 28.81wt%, dispersant: 2.15wt%, binder: 13.31wt%, and plasticizer: 1.98wt%.

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