阅读说明：本技术 一种无引脚堆叠型陶瓷电容器及其制备方法 (Pin-free stacked ceramic capacitor and preparation method thereof ) 是由 吴文辉 吴明钊 朱江滨 蔡约轩 王凯星 于 2021-06-03 设计创作，主要内容包括：一种无引脚堆叠型陶瓷电容器及其制备方法,电容器包括依次堆叠的多个陶瓷电容芯体,陶瓷电容芯体相对的两端分别设置有端电极,其特征在于:相邻两陶瓷电容芯体之间设置有用于固定的粘结剂,多个陶瓷电容芯体的同侧端电极之间通过焊料相互焊接形成焊接接头,在相邻两陶瓷电容芯体之间设置有用于固定的粘结剂,这样可以使堆叠后的陶瓷电容芯体相互固定在一起不会相对移动错位,从而有效防止堆叠后的陶瓷电容芯体在后续的焊接工艺中不会因焊料熔化而相对移动错位,有效提高产品的良率。(A leadless stacked ceramic capacitor and a preparation method thereof are provided, the capacitor comprises a plurality of ceramic capacitor cores which are stacked in sequence, and two opposite ends of the ceramic capacitor cores are respectively provided with an end electrode.)

1. A pin-free stacked ceramic capacitor comprises a plurality of ceramic capacitor cores which are sequentially stacked, wherein end electrodes are respectively arranged at two opposite ends of each ceramic capacitor core.

2. The leadless stacked ceramic capacitor of claim 1, wherein: and the welding flux coats the end electrodes at the same side of the ceramic capacitor cores to form welding joints.

3. The leadless stacked ceramic capacitor of claim 1, wherein: the binder is one of thermosetting epoxy resin, organic silicon, polyurethane, polyimide, acrylics and UV curing glue.

4. The leadless stacked ceramic capacitor of claim 1, wherein: the liquidus of the solder is greater than 260 ℃.

5. The leadless stacked ceramic capacitor of claim 4, wherein: the solder is lead-based solder, gold-based solder, conductive silver paste or sintered silver paste.

6. The leadless stacked ceramic capacitor of claim 1, wherein: the ceramic capacitor core is a multilayer ceramic capacitor core.

7. A method for preparing a pin-free stacked ceramic capacitor is characterized by comprising the following steps: the method comprises the following steps:

(1) arranging a binder between two adjacent ceramic capacitor cores, so that the ceramic capacitor cores are orderly stacked and fixed together, and the binder is cured;

(2) and arranging solder at the position corresponding to the terminal electrodes in the mould, putting the stacked ceramic capacitor cores into the mould, and then putting the mould into a vacuum eutectic furnace for heating and welding to ensure that the solder is melted and diffused to the surfaces of the terminal electrodes at the same side of the ceramic capacitor cores to form welding joints.

8. The method according to claim 7, wherein the method comprises: the adhesive is thermosetting epoxy resin, the curing temperature is 130-170 ℃, and the curing time is 2-10 min.

9. The method according to claim 7, wherein the method comprises: the adhesive is organic silicon, the curing temperature is 100-120 ℃, the curing time is 1-2 h, or the curing time is 20-26 h at normal temperature.

10. The method according to claim 7, wherein the method comprises: the welding temperature of the vacuum eutectic furnace is 320-350 ℃, and the welding time is 7-15 min.

Technical Field

The invention relates to a pin-free stacked ceramic capacitor and a preparation method thereof.

Background

The existing pin-free stacked ceramic capacitor comprises a plurality of ceramic capacitor cores stacked in sequence, the ceramic capacitor cores stacked in sequence are generally composed of two ceramic capacitor cores stacked mutually, end electrodes are respectively arranged at two opposite ends of the ceramic capacitor cores, welding joints are formed between the end electrodes at the same side of the two ceramic capacitor cores through welding materials in a mutual welding mode, and the specific preparation process is as follows: the two ceramic capacitor cores are placed into the die, the welding materials are arranged at the end electrodes, the welding materials are melted and metallurgically welded to form welding joints through a high-temperature welding process, although the die cavity of the die is matched with the total volume of the two ceramic capacitor cores and the welding materials, mutual dislocation of the two ceramic capacitor cores can be limited within a certain range, the welding materials are diffused to the surface of the end electrodes to form intermetallic bonding after being melted, the total volume of the ceramic capacitor cores is reduced, the die cavity can not well limit the displacement of the two ceramic capacitor cores, and the problem of dislocation of the two ceramic capacitor cores can often occur.

Disclosure of Invention

The invention aims to provide a leadless stacked ceramic capacitor capable of preventing dislocation of a ceramic capacitor core body aiming at the defects of the prior art.

The purpose of the invention is realized by the following technical scheme:

a pin-free stacked ceramic capacitor comprises a plurality of ceramic capacitor cores which are sequentially stacked, wherein end electrodes are respectively arranged at two opposite ends of each ceramic capacitor core.

And the welding flux coats the end electrodes at the same side of the ceramic capacitor cores to form welding joints.

The binder is one of thermosetting epoxy resin, organic silicon, polyurethane, polyimide, acrylics and UV curing glue.

The liquidus of the solder is greater than 260 ℃.

The solder is lead-based solder, gold-based solder, conductive silver paste or sintered silver paste.

The ceramic capacitor core is a multilayer ceramic capacitor core.

A method for preparing a pin-free stacked ceramic capacitor is characterized by comprising the following steps: the method comprises the following steps:

(1) arranging a binder between two adjacent ceramic capacitor cores, so that the ceramic capacitor cores are orderly stacked and fixed together, and the binder is cured;

(2) and arranging solder at the position corresponding to the terminal electrodes in the mould, putting the stacked ceramic capacitor cores into the mould, and then putting the mould into a vacuum eutectic furnace for heating and welding to ensure that the solder is melted and diffused to the surfaces of the terminal electrodes at the same side of the ceramic capacitor cores to form welding joints.

The adhesive is thermosetting epoxy resin, the curing temperature is 130-170 ℃, and the curing time is 2-10 min.

The adhesive is organic silicon, the curing temperature is 100-120 ℃, the curing time is 1-2 h, or the curing time is 20-26 h at normal temperature.

The welding temperature of the vacuum eutectic furnace is 320-350 ℃, and the welding time is 7-15 min.

The invention has the following beneficial effects:

the adhesive for fixing is arranged between the two adjacent ceramic capacitor cores, so that the stacked ceramic capacitor cores are mutually fixed together and cannot relatively move and misplace, the stacked ceramic capacitor cores are effectively prevented from relatively moving and misplacing due to the fact that the solder is melted in the subsequent welding process, and the yield of products is effectively improved.

Drawings

The present invention will be described in further detail with reference to the accompanying drawings.

FIG. 1 is a schematic structural diagram of the present invention.

Fig. 2 is an exploded view of the components of the present invention.

Fig. 3 is a partial cross-sectional view of the present invention.

Fig. 4 is a graph comparing the effect of reflow times on bond strength.

FIG. 5 is a graph comparing creep resistance at elevated temperatures.

Detailed Description

Referring to fig. 1 to 3, a leadless stacked ceramic capacitor is formed by stacking two ceramic capacitor cores 1, each ceramic capacitor core 1 is substantially a rectangular parallelepiped, two opposite ends of each ceramic capacitor core 1 are respectively provided with a terminal electrode 11, each ceramic capacitor core 1 is a multilayer ceramic capacitor core, a first internal electrode 12 and a second internal electrode 13 are arranged inside each ceramic capacitor core 1, each first internal electrode 12 is electrically connected with one terminal electrode 11, each second internal electrode 13 is electrically connected with the other terminal electrode 11, the first internal electrodes 12 and the second internal electrodes 13 are arranged in a staggered and parallel spaced manner, a ceramic dielectric material is arranged between each first internal electrode 12 and each second internal electrode 13, each terminal electrode 11 is sequentially provided with a base metal layer 111, a barrier layer 112 and an outermost plating layer 113 from inside to outside, wherein the base metal 111 is copper or silver; the barrier layer 112 is a layer of nickel with a thickness of 1-5 μm; the outermost plating layer 113 is a tin-lead layer with the thickness of 5-20 μm, the lead content of the tin-lead layer is more than or equal to 81% (wt), and the nickel layer electroplating time is as follows: 30min-150 min; the current for nickel electroplating was: 4A-14A; electroplating time of the tin-lead layer: 45-150 min, and the current of electroplating tin and lead is as follows: 3A-10A.

A binder 3 for fixing is arranged between the two ceramic capacitor cores 1, the same-side end electrodes 11 of the two ceramic capacitor cores 1 are mutually welded through a solder 2 to form a welding joint, the solder 2 coats the same-side end electrodes 11 of the two ceramic capacitor cores 1 to form the welding joint, the binder 3 is one of thermosetting epoxy resin, organic silicon, polyurethane, polyimide, acrylate and UV curing adhesive, in the embodiment, the binder 3 adopts thermosetting epoxy resin, the liquidus of the solder is more than 260 ℃, and the solder is lead-based solder, gold-based solder, conductive silver adhesive or sintered silver paste, wherein the lead-based solder is Sn5Pb92.5Ag2.5, Sn10Pb88Ag2 or Pb92.5In5Ag2.5; gold-based solders such as Au80Sn20, Au88Ge 12.

In a first embodiment, a method for manufacturing a leadless stacked ceramic capacitor is characterized in that: the method comprises the following steps:

(1) the adhesive 3 is arranged between the two ceramic capacitor cores 1, so that the two ceramic capacitor cores 1 are stacked and fixed together in order, the adhesive 3 is cured, the adhesive 3 is thermosetting epoxy resin, the curing temperature is 150 ℃, and the curing time is 5 min.

(2) Arranging solder 2 at the position corresponding to the terminal electrode 11 in the mold, placing the stacked ceramic capacitor cores 1 in the mold, then placing the mold in a vacuum eutectic furnace for heating and welding, so that the solder 2 is melted and diffused to the surfaces of the terminal electrodes 11 at the same side of the two ceramic capacitor cores 1 to form a welding joint, wherein the welding temperature of the vacuum eutectic furnace is 320 ℃, and the welding time is 15 min.

(3) And (4) carrying out appearance screening on the welded capacitor by using a body type microscope, and screening out the defects of cracks, defects and the like on the capacitor body.

(4) Testing the capacitance and the loss tangent of the capacitor with the sorted appearance by using a capacitance tester; testing the dielectric voltage resistance of the product by using a voltage resistance insulation analyzer; the insulation resistance of the product was tested using a high resistance meter.

Embodiment two, a method for preparing a leadless stacked ceramic capacitor, comprising: the method comprises the following steps:

(1) the adhesive 3 is arranged between the two ceramic capacitor cores 1, so that the two ceramic capacitor cores 1 are stacked and fixed together in order, the adhesive 3 is cured, the adhesive 3 is organic silicon, the curing temperature is 100 ℃, the curing time is 1-2 h, or the curing time is 24h at normal temperature.

(2) Arranging solder 2 at the position corresponding to the terminal electrode 11 in the mould, putting the stacked ceramic capacitor cores 1 into the mould, then putting the mould into a vacuum eutectic furnace for heating and welding, so that the solder 2 is melted and diffused to the surfaces of the terminal electrodes 11 at the same side of the two ceramic capacitor cores 1 to form a welding joint, wherein the welding temperature of the vacuum eutectic furnace is 350 ℃, and the welding time is 7 min.

(3) And (4) carrying out appearance screening on the welded capacitor by using a body type microscope, and screening out the defects of cracks, defects and the like on the capacitor body.

(4) Testing the capacitance and the loss tangent of the capacitor with the sorted appearance by using a capacitance tester; testing the dielectric voltage resistance of the product by using a voltage resistance insulation analyzer; the insulation resistance of the product was tested using a high resistance meter.

In a third embodiment, a method for manufacturing a leadless stacked ceramic capacitor is characterized in that: the method comprises the following steps:

(1) the adhesive 3 is arranged between the two ceramic capacitor cores 1, so that the two ceramic capacitor cores 1 are stacked and fixed together in order, the adhesive 3 is cured, the adhesive 3 is thermosetting epoxy resin, the curing temperature is 170 ℃, and the curing time is 3 min.

(2) Arranging solder 2 at the position corresponding to the terminal electrode 11 in the mold, placing the stacked ceramic capacitor cores 1 in the mold, then placing the mold in a vacuum eutectic furnace for heating and welding, so that the solder 2 is melted and diffused to the surfaces of the terminal electrodes 11 at the same side of the two ceramic capacitor cores 1 to form a welding joint, wherein the welding temperature of the vacuum eutectic furnace is 320 ℃, and the welding time is 10 min.

(3) And (4) carrying out appearance screening on the welded capacitor by using a body type microscope, and screening out the defects of cracks, defects and the like on the capacitor body.

(4) Testing the capacitance and the loss tangent of the capacitor with the sorted appearance by using a capacitance tester; testing the dielectric voltage resistance of the product by using a voltage resistance insulation analyzer; the insulation resistance of the product was tested using a high resistance meter.

The invention adopts the vacuum eutectic furnace welding process, can ensure that the hole rate of the welding joint formed by melting and metallurgy of the welding flux is lower than 3 percent, and the welding joint has high strength and bright and smooth appearance.

Product performance testing

1. Adhesive strength test of the adhesive with epoxy resin:

epoxy boards were used for the tests: applying a block-shaped adhesive on an epoxy resin plate FR-4 with the thickness of 1.60mm, wherein the length, the width and the height of the block-shaped adhesive are shown in the following table, and then adhering a corresponding ceramic capacitor on the block-shaped adhesive for curing under the curing conditions: and (3) placing the epoxy resin plate on a high-low temperature oven to be heated, and keeping the temperature for 5min after the temperature reaches 150 ℃. And (3) the strength measured by pulling back the ceramic capacitor in the direction of the long axis using a push-pull dynamometer.

2. Adhesive bond Strength comparison after welding

The determination method comprises the following steps: sample preparation: stacking 2 ceramic capacitors with 2220 specification, adopting epoxy resin as a binder, and curing the binder at 150 ℃ for 5 min. The stacked capacitor samples were soldered in a vacuum eutectic oven set at 340 ℃ for 10s and left at room temperature for 30 minutes (simulating a product soldering environment). Then, the solder was reflowed for 30 seconds at a temperature set to 260 ℃ and left at room temperature for 30 minutes, and this was reflowed once (simulating a customer soldering environment). As shown in fig. 4, the adhesive strength of the adhesive was measured at room temperature for each of the capacitors after repeated reflow, and it was found from fig. 4 that the adhesive did not melt or denature under various simulated use environments, and the two ceramic capacitor core bodies did not fall off, separate, or shift.

3. High temperature creep resistance comparison

2 ceramic capacitors with 2220 specifications are adopted for stacking and welding, and the ceramic capacitors are not fixed by adopting a bonding agent. These stacked capacitors are divided into 3 equal groups of 10 stacked capacitors each. Wherein the 2 groups are control groups S1 and S2, respectively, and the last group is invention group F1. S1, welding by adopting a welding material SAC 305; s2, welding by adopting a solder Sn90Sb 10; f1 was soldered with Sn5Pb92.5Ag2.5 solder. The 3 groups of samples are subjected to high-temperature load test, the stacked capacitor is fixed by adopting an upper part body, and a weight 50g is loaded (suspended) on the lower part body and is suspended in the oven. Setting the temperature of the oven at 220 ℃, and keeping the temperature for 10min when the temperature is increased from room temperature to 220 ℃. After the heat preservation time is up to 270 ℃ after the heat preservation time is up to standard after 10min, the separation condition of the upper capacitor and the lower capacitor is checked in a stepping mode at 10 ℃, the separation temperature is recorded, the specific data is shown in figure 5, and as can be seen from figure 5, the higher service temperature can be achieved between the two ceramic capacitor cores by selecting Sn5Pb92.5Ag2.5 as the solder.

The above description is only a preferred embodiment of the present invention, and therefore should not be taken as limiting the scope of the invention, which is defined by the appended claims and their equivalents and modifications within the scope of the description.