Terminal electrode glass composition, terminal electrode copper paste, multilayer ceramic capacitor and manufacturing method thereof

Abstract

The invention provides a terminal electrode glass composition, terminal electrode copper paste, a multilayer ceramic capacitor and a manufacturing method of the multilayer ceramic capacitor. The termination electrode glass composition includes a first main component, a first sub-component, and a second sub-component. The first main component comprises an alkaline earth metal oxide; the first auxiliary component comprises a zinc element; and the second auxiliary component comprises an aluminum element and a silicon element. Based on 100 wt% of the terminal electrode glass composition, the first main component is 70 wt% to 75 wt%. Based on 100 wt% of the first main component, the first auxiliary component is 25 wt% to 30 wt%, and the second auxiliary component is 7 wt% to 11 wt%. Therefore, the terminal electrode has acid etching resistance, and the burning temperature in the multilayer ceramic capacitor process is reduced.

Description

Technical Field

[0001] This invention relates to a terminal electrode glass composition, and more particularly to a terminal electrode glass composition, a terminal electrode copper paste, a multilayer ceramic capacitor, and a method for manufacturing the same. Background Technology

[0002] Multilayer ceramic capacitors (MLCCs) can be classified into base metal electrode (BME) and noble metal electrode (NME) processes based on the electrode materials. Generally, the terminal electrodes of a BME MLCC are formed from the inside out by sintering copper, electroplating nickel, and electroplating tin. The sintering copper process involves sintering copper paste to allow the copper metal to alloy with the nickel of the inner electrode at high temperature, thus forming a conductive alloy and creating the terminal electrode.

[0003] The copper paste raw materials mentioned above must contain glass components to act as a medium for bonding with the ceramic materials in the ceramic capacitor element. The constituent elements of the glass components will affect the quality and electrical performance of the resulting terminal electrodes.

[0004] Due to the current trend of product miniaturization, MLCC element layer thickness is becoming increasingly thinner, and the number of layers is being increased to meet high capacitance requirements. However, this design causes stress accumulation in MLCCs, thereby reducing their reliability. In addition, it has been found that nickel plating penetrates into the terminal electrodes after the electroplating process, causing device abnormalities, and the proportion of products cracking is also increasing.

[0005] The end electrodes can coat the nickel of the inner electrodes, thus providing a protective effect. Therefore, the end electrodes must be resistant to subsequent acidic electroplating processes to prevent the plated nickel from penetrating into the inner electrodes. Furthermore, lowering the sintering temperature of the end electrodes can reduce internal stress in the MLCC, thereby improving the reliability of thin-film MLCCs.

[0006] In view of this, there is an urgent need to provide a glass composition for the end electrode and a copper paste for the end electrode to enhance the acid resistance of the end electrode and reduce the sintering temperature of the end electrode. Summary of the Invention

[0007] One aspect of the present invention is to provide an end electrode glass composition containing specific constituent elements and contents to achieve the effects of reducing sintering temperature and resisting acid etching.

[0008] Another aspect of the present invention is to provide a terminal electrode copper paste comprising the terminal electrode glass composition described above.

[0009] Another aspect of the present invention is to provide a method for manufacturing a multilayer ceramic capacitor, which produces the multilayer ceramic capacitor by means of a lower sintering temperature.

[0010] Another aspect of the present invention is to provide a multilayer ceramic capacitor, which is manufactured using the method described above.

[0011] According to one aspect of the present invention, an end electrode glass composition is provided, comprising a first main component, a first secondary component, and a second secondary component. The first main component comprises an alkaline earth metal oxide; the first secondary component comprises zinc; and the second secondary component comprises aluminum and silicon. Based on a 100 wt% end electrode glass composition, the first main component comprises 70 wt% to 75 wt%. Based on a 100 wt% first main component, the first secondary component comprises 25 wt% to 30 wt%, and the second secondary component comprises 7 wt% to 11 wt%.

[0012] According to one embodiment of the present invention, based on the first main component being 100 wt%, the content of aluminum element is 5 wt% to 7.9 wt%.

[0013] According to one embodiment of the present invention, based on the first main component being 100 wt%, the content of silicon element is 2 wt% to 3.1 wt%.

[0014] According to one embodiment of the present invention, the content ratio of silicon to aluminum is not greater than 1 / 2.

[0015] According to one embodiment of the present invention, the content ratio of silicon to aluminum is 1 / 5 to 1 / 2.

[0016] According to another aspect of the present invention, a terminal electrode copper paste is provided, comprising copper powder and a terminal electrode glass composition as described above.

[0017] According to one embodiment of the present invention, the copper powder is 100 wt% and the end electrode glass composition is 9 wt% to 11 wt%.

[0018] According to another aspect of the present invention, a method for manufacturing a multilayer ceramic capacitor is provided. The method includes providing a multilayer capacitor element; applying the terminal electrode copper paste of the above-described aspect onto the multilayer capacitor element to obtain a multilayer ceramic capacitor semi-finished product; and performing a sintering process on the multilayer ceramic capacitor semi-finished product to obtain a multilayer ceramic capacitor, wherein the sintering temperature of the sintering process is less than 850°C.

[0019] According to one embodiment of the present invention, the sintering temperature is 760°C to less than 850°C.

[0020] According to another aspect of the present invention, a multilayer ceramic capacitor is provided, which is manufactured using the manufacturing method of the multilayer ceramic capacitor described above.

[0021] The terminal electrode glass composition, terminal electrode copper paste, multilayer ceramic capacitor, and manufacturing method of the present invention are used to improve the acid corrosion resistance of the terminal electrode by using a terminal electrode glass composition with specific constituent elements and contents, and to reduce the sintering temperature in the multilayer ceramic capacitor process, thereby improving the reliability of the obtained multilayer ceramic capacitor. Attached Figure Description

[0022] A better understanding of the features disclosed herein will be achieved by reading the following detailed description in conjunction with the accompanying drawings. It should be noted that, as is standard practice in the industry, many features are not drawn to scale. In fact, for clarity of discussion, the dimensions of many features may be arbitrarily scaled.

[0023] Figure 1 A cross-sectional view of a multilayer ceramic capacitor according to some embodiments of the present invention is shown. Detailed Implementation

[0024] The following disclosure provides numerous different embodiments or illustrations to implement various features of the invention. The specific examples of elements and configurations described below are for the purpose of simplifying this disclosure. These are, of course, merely illustrative and are not intended to be limiting. For example, a description of a first feature being formed on or above a second feature includes embodiments where the first and second features are in direct contact, as well as embodiments where other features are formed between the first and second features such that the first and second features are not in direct contact. Furthermore, element symbols and / or letters are repeated in various specific examples in this disclosure. This repetition is for the purpose of simplifying and clarifying the description and does not imply a relationship between the various discussed embodiments and / or configurations.

[0025] The manufacture and use of embodiments of the present invention are discussed in detail below. However, it will be understood that the embodiments provide many applicable inventive concepts that can be implemented in a wide variety of specific contexts. The specific embodiments discussed are for illustrative purposes only and are not intended to limit the scope of the invention.

[0026] As used in this invention, “around,” “about,” “approximately,” or “substantially” generally mean within 20 percent, 10 percent, or 5 percent of the stated value or range.

[0027] As described above, the present invention provides a terminal electrode glass composition, a terminal electrode copper paste, a multilayer ceramic capacitor, and a method for manufacturing the same. By using a terminal electrode glass composition with specific constituent elements and contents, the acid corrosion resistance of the terminal electrode is improved, and the sintering temperature in the multilayer ceramic capacitor process is reduced, thereby improving the reliability of the resulting multilayer ceramic capacitor.

[0028] The terminal electrode glass composition of the present invention comprises a first main component, a first secondary component, and a second secondary component. The first main component comprises an alkaline earth metal oxide, wherein the alkaline earth metal oxide comprises oxides of beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), and / or barium (Ba). In some embodiments, based on 100 wt% of the terminal electrode glass composition, the content of the first main component is from about 70 wt% to about 75 wt%. If the content of the first main component is too low (e.g., less than about 70 wt%), the temperature during subsequent sintering of the terminal electrode will be too high, and the thin-layered multilayer ceramic capacitor may crack due to excessive internal stress; conversely, if the content of the first main component is too high (e.g., greater than about 75 wt%), the resulting terminal electrode will have poor acid corrosion resistance, which will lead to a decrease in the reliability of the multilayer ceramic capacitor.

[0029] The aforementioned first secondary component includes zinc. Adding zinc helps lower the sintering temperature of the terminal electrodes and also serves to bond the zinc to the ceramic material of the ceramic capacitor element. In some specific examples, the zinc may be sourced from zinc oxide. In some embodiments, based on a first primary component of 100 wt%, the amount of the first secondary component added is approximately 25 wt% to approximately 30 wt%. If the amount of the first secondary component added is too small (e.g., less than approximately 25 wt%), the sintering temperature of the terminal electrodes cannot be effectively reduced, and the bonding effect with the ceramic is poor; conversely, if the amount of the first secondary component added is too large (e.g., greater than approximately 30 wt%), the resulting terminal electrodes will have poor acid corrosion resistance, which in turn will lead to a decrease in the reliability of the multilayer ceramic capacitor.

[0030] The second auxiliary component mentioned above includes aluminum and silicon. The addition of aluminum and silicon contributes to the acid corrosion resistance. In some specific examples, the aluminum may be sourced from alumina, and the silicon may be sourced from silicon oxide. In some embodiments, based on a first main component of 100 wt%, the amount of the second auxiliary component added is from about 7 wt% to about 11 wt%. If the amount of the second auxiliary component added is too small (e.g., less than about 7 wt%), the resulting end electrode will have poor acid corrosion resistance; conversely, if the amount of the second auxiliary component added is too large (e.g., greater than about 11 wt%), the sintering temperature of the end electrode cannot be effectively reduced.

[0031] In some embodiments, based on a first main component of 100 wt%, the content of aluminum is 5 wt% to 7.9 wt%, and the content of silicon is 2 wt% to 3.1 wt%. Since aluminum and silicon have better resistance to different types of acids, the acid corrosion resistance of the terminal electrode can be improved when the added amounts of aluminum and silicon are within the aforementioned ranges.

[0032] In some embodiments, the ratio of silicon to aluminum is no more than 1 / 2, preferably about 1 / 5 to about 1 / 2. When the ratio of silicon to aluminum is controlled within the aforementioned range, excessive silicon can be avoided from affecting the effect of reducing the sintering temperature.

[0033] The terminal electrode copper paste of the present invention comprises copper powder and a terminal electrode glass composition dispersed in the copper powder. In some embodiments, based on 100 wt% copper powder, the terminal electrode copper paste comprises about 9 wt% to about 11 wt% of the terminal electrode glass composition. The terminal electrode glass composition having the aforementioned content range enables the terminal electrode copper paste to have high surface density and appropriate conductivity after sintering.

[0034] Please see Figure 1 The diagram illustrates a cross-sectional view of a multilayer ceramic capacitor 100 according to some embodiments of the present invention. The following utilizes... Figure 1 This describes a method for manufacturing a multilayer ceramic capacitor. First, a multilayer capacitor element 110 is provided, wherein the multilayer capacitor element includes internal electrodes 120. The aforementioned terminal electrode copper paste is applied to both sides of the multilayer capacitor element 110 to obtain a multilayer ceramic capacitor semi-finished product. Next, a sintering process is performed on the multilayer ceramic capacitor semi-finished product to sinter the terminal electrode copper paste into terminal electrodes 130, thereby producing a multilayer ceramic capacitor 100.

[0035] In some embodiments, the sintering temperature of the above-described sintering process is less than about 850°C, preferably from about 760°C to less than about 850°C, and more preferably about 760°C. Existing methods require sintering temperatures above 850°C to achieve a 95% density level in the resulting terminal electrodes, but this leads to a significant increase in stress accumulation, resulting in a higher risk of cracking in the resulting multilayer ceramic capacitors, and a reliability test yield of only 50%. In contrast, the present invention, while reducing the sintering temperature, still achieves a terminal electrode density level of over 95%, and the reliability test yield is even higher, with a 95% pass rate. It should be noted that the aforementioned reliability test mainly refers to testing the electrical insulation resistance at 85°C and rated voltage for 500 hours; if the insulation resistance does not decrease, it is defined as a passable level.

[0036] Existing methods for fabricating multilayer ceramic capacitors with a dielectric layer thickness of only about 0.8 μm and nearly two hundred effective area layers pose a high risk due to residual stress, resulting in low reliability testing yields. However, the terminal electrode glass composition and terminal electrode copper paste of this invention can reduce the impact of stress by lowering the sintering temperature.

[0037] Furthermore, since the terminal electrodes require electroplating of nickel and tin onto the copper in addition to sintering copper, the terminal electrode glass composition and terminal electrode copper paste of the present invention, after sintering, show that the eroded area in an electroplating acid solution with a pH below 5 can be less than 1%. Therefore, the resulting multilayer ceramic capacitor can have high reliability, which is beneficial for mass production.

[0038] The following examples illustrate the application of the present invention, but are not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention.

[0039] Experimental Examples 1 to 9

[0040] Examples 1 to 9 involve mixing alkaline earth metal oxides, zinc oxide, aluminum oxide, and silicon oxide to prepare end electrode glass compositions. With alkaline earth metal oxides at 100 wt%, examples 1 to 9 involve mixing zinc oxide, aluminum oxide, and silicon oxide in different proportions, as shown in Table 1.

[0041] The end electrode glass compositions of Experimental Examples 1 to 9 were mixed with copper powder to form an end electrode copper paste, wherein the content of the end electrode glass composition was 12 wt% relative to the copper powder. Then, sintering was performed at a temperature of 760°C (±5°C) to measure the surface density of the copper layer of the end electrode. The measurement results are shown in Table 1 below.

[0042] To clarify, the measurement procedure for the copper layer surface density involves photographing the surface of the sintered terminal electrode using a scanning electron microscope (SEM) at 3k magnification. Then, the surface density is obtained by calculating the porosity using plotting software. Fewer porosity results in greater surface density. Over-sintering can lead to significant glass deposition on the terminal electrode surface, increasing surface resistance and reducing subsequent electroplating efficiency.

[0043] Table 1

[0044]

[0045] Experimental Examples 1-1 to 1-5 and Experimental Examples 6-1 to 6-5

[0046] According to Table 1, although the surface density of the end electrode glass composition in Experimental Examples 1 and 6 was over-burned, over-burning indicates that there is a chance to obtain a surface density that meets the standard (i.e., 95% to 100%). Therefore, the formulations of the end electrode glass compositions in Experimental Examples 1 and 6 were used, and the mixing ratio of the end electrode glass composition and copper powder was changed to prepare the end electrodes of Experimental Examples 1-1 to 1-5 and Experimental Examples 6-1 to 6-5. The surface density of the copper layer was measured under the same conditions as above. The mixing ratio and surface density are shown in Table 2 below.

[0047] Table 2

[0048]

[0049] According to Table 2, the surface density results for Experiments 1, 6, and 6-1 were "overburned," indicating a large amount of glass precipitation, which may lead to a decrease in conductivity. Experiments 1-4, 1-5, 6-4, and 6-5, however, contained too little end-electrode glass composition, failing to achieve the required surface density. Therefore, Experiments 1-1 to 1-3, 6-2, and 6-3 were selected for further testing.

[0050] The sintered terminal electrodes of Examples 1-1 to 1-3, 6-2, and 6-3 were immersed in an electroplating acid solution with a pH below 5, and the proportion of the copper layer surface area etched by acid was observed. It should be noted that the test procedure for the proportion of the copper layer etched by acid included immersing the sintered terminal electrodes in an electroplating nickel acid solution at 60°C for 2 hours. After immersion, the electrodes were cleaned and dried, and then photographed using a scanning electron microscope. The change in surface density after acid etching was then calculated using graphing software. In addition, the sintered terminal electrodes of Examples 1-1 to 1-3, 6-2, and 6-3 were subjected to a reliability test, i.e., tested at 85°C and rated voltage for 500 hours to measure the rate of insulation resistance degradation. The results of the above two tests are shown in Table 3 below.

[0051] Table 3

[0052]

[0053] According to Table 3, the acid-etched area ratio of Experiments 1-1 to 1-3 is less than 1%, and the insulation resistance degradation ratio is no greater than 5%. In contrast, the acid-etched area ratio and insulation resistance degradation ratio of Experiments 6-2 and 6-3 are higher. Therefore, it can be seen from the above experimental examples that Experiments 1-1 to 1-3, which use end electrode glass compositions with specific composition ratios, and the end electrode copper paste prepared by mixing the end electrode glass compositions with copper powder in specific proportions, can still have high surface density, low acid-etched area ratio, and low insulation resistance degradation ratio under long-term high temperature after a low-temperature sintering process.

[0054] According to the above embodiments, the terminal electrode glass composition, terminal electrode copper paste, multilayer ceramic capacitor and manufacturing method provided by the present invention can improve the acid corrosion resistance of the terminal electrode and reduce the sintering temperature in the multilayer ceramic capacitor process by using a terminal electrode glass composition with specific constituent elements and contents, thereby improving the reliability of the obtained multilayer ceramic capacitor.

[0055] Although the present invention has been disclosed above with reference to several embodiments, it is not intended to limit the present invention. Those skilled in the art to which this invention pertains can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

[0056] [Symbol Explanation]

[0057] 100: Multilayer ceramic capacitor

[0058] 110: Multilayer capacitor element

[0059] 120: Internal electrode

[0060] 130: Terminal electrode.

Claims

1. A glass composition for end electrodes, characterized in that, Include: The first principal component comprises an alkaline earth metal oxide, wherein the end electrode glass composition is 100 wt% and the first principal component is 70 wt% to 75 wt%. The first secondary component contains zinc, wherein, based on the first primary component being 100 wt%, the first secondary component is 25 wt% to 30 wt%; and The second component comprises aluminum and silicon, wherein the first principal component is 100 wt% and the second component is 7 wt% to 11 wt%.

2. The end electrode glass composition according to claim 1, characterized in that, The first principal component is 100 wt%, and the aluminum content is 5 wt% to 7.9 wt%.

3. The end electrode glass composition according to claim 1, characterized in that, The first principal component is 100 wt%, and the silicon content is 2 wt% to 3.1 wt%.

4. The end electrode glass composition according to any one of claims 1 to 3, characterized in that, The ratio of silicon to aluminum is no more than 1 / 2.

5. The end electrode glass composition according to any one of claims 1 to 3, characterized in that, The ratio of silicon to aluminum is 1 / 5 to 1 / 2.

6. A copper paste for terminal electrodes, characterized in that, Include: Copper powder; and The end electrode glass composition according to any one of claims 1 to 5.

7. The terminal electrode copper paste according to claim 6, characterized in that, The copper powder comprises 100 wt%, and the end electrode glass composition comprises 9 wt% to 11 wt%.

8. A method for manufacturing a multilayer ceramic capacitor, characterized in that, Include: Provides multilayer capacitor components; Applying the terminal electrode copper paste according to claim 6 or 7 onto the multilayer capacitor element to obtain a multilayer ceramic capacitor semi-finished product; and The multilayer ceramic capacitor semi-finished product is subjected to a sintering process to obtain the multilayer ceramic capacitor, wherein the sintering temperature of the sintering process is less than 850℃.

9. The method for manufacturing a multilayer ceramic capacitor according to claim 8, characterized in that, The sintering temperature is between 760°C and less than 850°C.

10. A multilayer ceramic capacitor, characterized in that, It is manufactured using the manufacturing method of the multilayer ceramic capacitor according to claim 8 or 9.

Images