A method for preparing a chip-type solid electrolytic capacitor

Abstract

The embodiment of the present application provides a method for preparing a chip-type solid electrolytic capacitor, including: connecting a valve metal body to a valve metal wafer through a connecting colloid; sintering the valve metal wafer carrying the valve metal body; sequentially forming a dielectric layer and a cathode layer on the surface of the sintered valve metal body, so that the valve metal body dielectric layer and the cathode layer constitute a capacitor element; molding and encapsulating the valve metal wafer carrying the capacitor element, and exposing the cathode end of the capacitor element; connecting the cathode end plate to the cathode end of the capacitor element; cutting the valve metal wafer to form a chip-type solid electrolytic capacitor with an anode end plate and a cathode end plate. The present application realizes a chip-type solid electrolytic capacitor without a lead frame structure through the above method, improves the bonding strength between the valve metal porous body and the anode end plate, and at the same time improves the flatness and reliability of the cathode terminal.

Description

Technical Field

[0001] The present application relates to the technical field of capacitors, and in particular to a method for preparing a chip-type solid electrolytic capacitor. Background Art

[0002] Chip solid electrolytic capacitors have the characteristics of high volumetric efficiency, high reliability and high process compatibility. They are one of the most popular small surface mount capacitors in applications such as consumer electronics, automotive electronics, aerospace and medical devices, and have made important contributions to the miniaturization of electronic circuits.

[0003] Traditional chip solid electrolytic capacitors use lead frames as capacitor element carriers, and use bonding materials to achieve electrical connection between capacitor elements and external leads to form an electrical circuit. Then, through molded packaging, the irregular shape of functional capacitor elements is transformed into an ideal packaging structure that is very suitable for high-speed mounting. However, about 50% of the packaging volume of capacitors with this packaging structure is occupied by wire connections and lead frame components, and the volume utilization rate is low. At the same time, the lead frame is an inductive loop, which increases the inductive reactance and impedance of the capacitor, which is not conducive to the miniaturization and high-frequency development of capacitors. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a method for preparing a chip-type solid electrolytic capacitor, which can realize a lead frame-free capacitor, and improve space utilization, mechanical strength and performance.

[0005] The present application provides a method for preparing a chip-type solid electrolytic capacitor, comprising: connecting a valve metal body to a valve metal wafer through a connecting colloid; sintering the valve metal wafer carrying the valve metal body; sequentially forming a dielectric layer and a cathode layer on the surface of the sintered valve metal body, so that the dielectric layer and the cathode layer of the valve metal body constitute a capacitor element; molding and packaging the valve metal wafer carrying the capacitor element, and exposing the cathode end of the capacitor element; connecting a cathode end plate to the cathode end of the capacitor element; and cutting the valve metal wafer to form a chip-type solid electrolytic capacitor having an anode end plate and a cathode end plate.

[0006] The present application realizes a chip-type solid electrolytic capacitor with a lead frame-free structure through the above method, improves the volume utilization rate of the chip-type solid electrolytic capacitor, reduces the equivalent series resistance (ESR) and equivalent series inductance (ESL) values ​​of the capacitor, and can realize a chip-type solid electrolytic capacitor with a small volume, extremely low ESL and ESR values, which is suitable for ultra-high density packaging and high-frequency applications; in addition, in the above method, the valve metal body is first connected to the valve metal wafer through a connecting colloid, and then the valve metal wafer carrying the valve metal body is sintered to improve the bonding strength between the valve metal porous body and the anode end plate, avoid relative slip between the valve metal porous body and the anode end plate, reduce the defective rate of subsequent sintering and packaging processes, and ensure the structural stability of the capacitor; further, the cathode end plate is connected to the cathode end of the capacitor element to increase the overall strength of the capacitor, while improving the flatness of the cathode terminal (cathode load connection end), and also improving the capacitor's ability to withstand external thermal stress and mechanical stress impact, thereby improving the reliability of the capacitor.

[0007] In some embodiments, the step of pasting a cathode end plate at the cathode end of the capacitor element includes: coating a conductive silver paste on the cathode end of the capacitor element; pasting a cathode end plate on the conductive silver paste and curing it at high temperature; and coating the surface of the cathode end plate after high temperature curing again with conductive silver paste so that the conductive silver paste covers the cathode end plate, and then curing it at high temperature.

[0008] The present invention first applies a layer of conductive silver paste on the cathode end, and then affixes a metal sheet of substantially the same size as the cathode end as the cathode end plate on the conductive silver paste, and then cures at high temperature; then, another layer of conductive silver paste is applied on the cathode end plate, so that the conductive silver paste covers the cathode end plate, and then cures at high temperature. This method can block the subsequent tin soldering plating solution from penetrating into the capacitor element, ensuring reliable capacitor performance.

[0009] In some embodiments, before connecting the valve metal body to the valve metal wafer via a connecting colloid, the method further includes: performing a pre-burning process on the valve metal body.

[0010] After the valve metal body is pressed from the valve metal powder, it is first pre-burned, and then placed on the connection colloid before being sintered as a whole. The pre-burning treatment not only improves the structural strength of the valve metal body itself, but also facilitates the connection and combination of the valve metal porous body and the anode end plate, reduces deformation during high-temperature sintering, facilitates subsequent plating and packaging, and improves the overall specification consistency of the capacitor.

[0011] In some embodiments, the sintering process of the valve metal wafer carrying the valve metal body includes: sintering the valve metal wafer carrying the valve metal body under high temperature and high vacuum conditions so that the valve metal wafer and the valve metal body are melted and connected together through the connecting colloid; and removing impurities from the valve metal body.

[0012] In some embodiments, the cutting process of the valve metal wafer to form a chip-type solid electrolytic capacitor having an anode terminal plate and a cathode terminal plate includes: cutting the valve metal wafer into capacitors in an array in a row; and marking an anode polarity band on a molded packaging layer.

[0013] In some embodiments, the cutting process of the valve metal wafer to form a chip-type solid electrolytic capacitor having an anode terminal plate and a cathode terminal plate further includes: cutting the capacitor on the valve metal wafer into individual units along the packaging layer; coating and curing the anode terminal plate and the cathode terminal plate respectively to form an anode conductive silver layer and a cathode conductive silver layer; and coating a solder plating layer on the anode conductive silver layer and the cathode conductive silver layer.

[0014] In some embodiments, the dielectric layer and the cathode layer are sequentially formed on the surface of the valve metal body after sintering so that the dielectric layer and the cathode layer of the valve metal body constitute a capacitor element, including: using the valve metal chip as an anode connection, forming a dielectric layer on the surface of the valve metal body after sintering by an electrochemical method; depositing a solid electrolyte of a predetermined thickness on the surface of the dielectric layer; and sequentially coating a carbon coating and a silver coating on the surface of the solid electrolyte by immersion and drying.

[0015] In some embodiments, before pre-firing the valve metal body, the method includes: taking a valve metal wafer and forming one or more patterns on the surface of the valve metal wafer; applying a connecting colloid at the pattern position on the surface of the valve metal wafer; taking valve metal powder and pressing the valve metal powder into a shape corresponding to the pattern to form a valve metal body.

[0016] In some embodiments, after coating the solder plating layer on the anode conductive silver layer and the cathode conductive silver layer, the method includes: subjecting the prepared chip-type solid electrolytic capacitor to aging, high and low temperature measurement, and electrical measurement, and eliminating failed products. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A flow chart of a method for preparing a chip-type solid electrolytic capacitor provided in an embodiment of the present application. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0020] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0021] Figure 1 A flow chart of a method for preparing a chip-type solid electrolytic capacitor provided in an embodiment of the present application.

[0022] Reference Figure 1 , an embodiment of the present application provides a method for preparing a chip-type solid electrolytic capacitor, including: step S11, step S12, step S13, step S14, step S15 and step S16.

[0023] In step S11, the valve metal body is connected to the valve metal wafer via a connecting glue.

[0024] A valve metal wafer can be taken and one or more patterns can be formed on the surface of the valve metal wafer; a connecting colloid can be applied at the pattern position on the surface of the valve metal wafer; valve metal powder can be taken and the valve metal powder can be pressed into a shape corresponding to the pattern to form a valve metal body; then, the valve metal body can be connected to the valve metal wafer through the connecting colloid.

[0025] For example, a laser marking device can be used to mark rectangles of specified size and quantity in an array on the surface of a valve metal wafer; a dispensing machine can be used to connect a colloid at the locations where the rectangles are marked on the wafer surface; high-purity valve metal powder can be pressed into a rectangular block of specified size and weight; and the valve metal rectangular block can be placed on the connected colloid.

[0026] In step S12, the valve metal wafer carrying the valve metal body is sintered.

[0027] For example, the valve metal wafer carrying the valve metal body is sintered under high temperature and high vacuum conditions, so that the valve metal wafer and the valve metal body are melted and connected together through the connecting colloid; impurities in the valve metal body are driven out to improve its mechanical strength.

[0028] In step S13, a dielectric layer and a cathode layer are sequentially formed on the surface of the sintered valve metal body, so that the valve metal body dielectric layer and the cathode layer constitute a capacitor element.

[0029] For example, a valve metal wafer is used as an anode connection, and a dielectric layer is formed on the surface of the sintered valve metal body by an electrochemical method; a solid electrolyte of a predetermined thickness is deposited on the surface of the dielectric layer; a carbon coating and a silver coating are sequentially coated on the surface of the solid electrolyte by dipping and drying to form a capacitor element.

[0030] In step S14, the valve metal wafer carrying the capacitor is molded and packaged, and the cathode end of the capacitor is exposed.

[0031] For example, the valve metal wafer carrying the capacitor element is molded and packaged using a multi-array packaging device, and the molded packaging layer is tightly attached to the capacitor element and the cathode end of the capacitor element is exposed.

[0032] In step S15, a cathode terminal plate is connected to the cathode terminal of the capacitor element.

[0033] In step S16, the valve metal wafer is cut to form a chip-type solid electrolytic capacitor having an anode terminal plate and a cathode terminal plate.

[0034] For example, the valve metal wafer is cut into long strips of capacitors arranged in an array; the anode polarity band is marked on the molded packaging layer to distinguish the anode and the cathode. Further optionally, the capacitor on the valve metal wafer is cut into individual units along the packaging layer; conductive silver paste is coated and cured on the anode end plate and the cathode end plate respectively to form an anode conductive silver layer and a cathode conductive silver layer; and a solder plating layer is coated on the anode conductive silver layer and the cathode conductive silver layer. The prepared chip-type solid electrolytic capacitor is subjected to aging, high and low temperature measurement, electrical measurement and other operations to eliminate early failure products and improve the reliability of the capacitor.

[0035] The present application realizes a chip-type solid electrolytic capacitor with a lead frame-free structure through the above method, improves the volume utilization rate of the chip-type solid electrolytic capacitor, reduces the ESL and ESR values ​​of the capacitor, and can realize a chip-type solid electrolytic capacitor with a small volume and extremely low ESL and ESR values, which is suitable for ultra-high density packaging and high-frequency applications; in addition, in the above method, the valve metal body is first connected to the valve metal chip through a connecting colloid, and then the valve metal chip carrying the valve metal body is sintered to improve the bonding strength between the valve metal porous body and the anode end plate, avoid relative slip between the valve metal porous body and the anode end plate, reduce the defective rate of subsequent sintering and packaging processes, and ensure the structural stability of the capacitor; further, the cathode end plate is connected to the cathode end of the capacitor element to increase the overall strength of the capacitor, while improving the flatness of the cathode terminal (cathode load connection end), and also improving the capacitor's ability to withstand external thermal stress and mechanical stress impact, thereby improving the reliability of the capacitor.

[0036] In some embodiments, the above step S15 includes: coating the cathode end of the capacitor element with conductive silver paste; pasting the cathode end plate on the conductive silver paste and curing it at high temperature; coating the surface of the cathode end plate after high temperature curing with conductive silver paste again so that the conductive silver paste covers the cathode end plate, and then curing it at high temperature.

[0037] In the embodiment of the present application, a layer of conductive silver paste is first applied to the cathode end, and then a metal sheet with substantially the same size as the cathode end is attached to the conductive silver paste as the cathode end plate, and then cured at high temperature; then, another layer of conductive silver paste is applied to the cathode end plate, so that the conductive silver paste covers the cathode end plate, and then cured at high temperature. This method can prevent the plating solution from penetrating into the capacitor element during subsequent tin soldering plating, ensuring reliable capacitor performance.

[0038] In some embodiments, before step S11, the preparation method further includes: pre-sintering the valve metal body. After the valve metal body is pressed from the valve metal powder, it is first pre-sintered, and the pre-sintered valve metal body is placed on the connecting colloid, and then sintered as a whole. The pre-sintering treatment improves the structural strength of the valve metal body itself, facilitates the connection and combination of the valve metal porous body and the anode end plate, reduces deformation during high-temperature sintering, facilitates subsequent plating and packaging, and improves the overall specification consistency of the capacitor.

[0039] In several embodiments provided in the present application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely schematic. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the devices, methods and computer program products according to multiple embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the module, a program segment or a part of a code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0040] In addition, the functional modules in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0041] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0042] The above description is only an embodiment of the present application and is not intended to limit the scope of protection of the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0043] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the scope of the rights.

[0044] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

Claims

1. A method for preparing a chip-type solid electrolytic capacitor, characterized in that: include: Taking a valve metal wafer, and forming one or more patterns on a surface of the valve metal wafer; taking valve metal powder and pressing the valve metal powder into a shape corresponding to the pattern to form a valve metal body; Pre-sintering the valve metal body; Applying a connection colloid at a pattern position on the surface of the valve metal wafer; Connecting the valve metal body to the valve metal wafer via a connecting colloid; Sintering a valve metal wafer carrying a valve metal body; Sequentially forming a dielectric layer and a cathode layer on the surface of the sintered valve metal body, so that the dielectric layer and the cathode layer of the valve metal body constitute a capacitor element; Molding and packaging the valve metal wafer carrying the capacitor element, and exposing the cathode end of the capacitor element; Connecting a cathode terminal plate to the cathode terminal of the capacitor element; The valve metal wafer is cut and processed to form a chip-type solid electrolytic capacitor having an anode terminal plate and a cathode terminal plate.

2. The method for preparing a chip-type solid electrolytic capacitor according to claim 1, characterized in that: The step of attaching a cathode end plate to the cathode end of the capacitor element comprises: Coating a conductive silver paste on the cathode end of the capacitor element; Paste the cathode terminal plate on the conductive silver paste and cure it at high temperature; The surface of the cathode end plate after high temperature curing is coated with conductive silver paste again, so that the conductive silver paste covers the cathode end plate, and then cured at high temperature.

3. The method for preparing a chip-type solid electrolytic capacitor according to claim 1, characterized in that: The sintering process of the valve metal wafer carrying the valve metal body comprises: Sintering the valve metal wafer carrying the valve metal body under high temperature and high vacuum conditions, so that the valve metal wafer and the valve metal body are melted and connected together through the connecting colloid; Remove impurities from the valve metal body.

4. The method for preparing a chip-type solid electrolytic capacitor according to claim 1, characterized in that: The step of cutting the valve metal wafer to form a chip-type solid electrolytic capacitor having an anode terminal plate and a cathode terminal plate comprises: cutting the valve metal wafer into capacitors arrayed in a row; Identify the anode polarity band on the molded encapsulation layer.

5. The method for preparing a chip-type solid electrolytic capacitor according to claim 1, characterized in that: The step of cutting the valve metal wafer to form a chip-type solid electrolytic capacitor having an anode terminal plate and a cathode terminal plate further comprises: Cutting the capacitors on the valve metal wafer into individual units along the packaging layer; Conductive silver paste is coated on the anode end plate and the cathode end plate respectively and cured to form an anode conductive silver layer and a cathode conductive silver layer; A solder plating layer is applied on the anodic conductive silver layer and the cathodic conductive silver layer.

6. The method for preparing a chip-type solid electrolytic capacitor according to claim 1, characterized in that: The step of sequentially forming a dielectric layer and a cathode layer on the surface of the sintered valve metal body so that the dielectric layer and the cathode layer of the valve metal body constitute a capacitor element comprises: Using the valve metal wafer as an anode connection, a dielectric layer is formed on the surface of the sintered valve metal body by an electrochemical method; Depositing a solid electrolyte of a predetermined thickness on the surface of the dielectric layer; The carbon coating and the silver coating are sequentially coated on the surface of the solid electrolyte by dipping and drying.

7. The method for preparing a chip-type solid electrolytic capacitor according to claim 5, characterized in that: After coating the solder plating layer on the anode conductive silver layer and the cathode conductive silver layer, the method comprises: The prepared chip solid electrolytic capacitors are subjected to aging, high and low temperature measurement, and electrical measurement to eliminate failed products.

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