阅读说明：本技术 一种高可靠多层陶瓷穿芯电容及其制作方法 (High-reliability multilayer ceramic through capacitor and manufacturing method thereof ) 是由 郑朝勇 叶斌 于 2021-02-09 设计创作，主要内容包括：本发明公开了一种高可靠多层陶瓷穿芯电容器,包括多层陶瓷穿芯电容器本体,多层陶瓷穿芯电容器本体具备至少一个用于穿设第一定膨胀合金管的内孔；第一定膨胀合金管内穿设有导针；第一定膨胀合金管经过退火后进行表面电镀处理；所述导针与第一定膨胀合金管、第一定膨胀合金管与内孔之间均使用无铅焊料焊接固定。本发明第一定膨胀合金管一起焊于盘状多层陶瓷电容器的内孔,以此来增强盘状多层电容器抗应力的能力。使得多层陶瓷穿心电容器生产用的焊料不局限于含铅高的、延展性好的焊接材料,可以承受多次的高温、低温快速变化的温度冲击后不会因温差变化导致陶瓷体崩裂而失效,从而获得在恶劣的外部环境下也具备高可靠性的多层陶瓷穿心电容器。(The invention discloses a high-reliability multilayer ceramic through-core capacitor, which comprises a multilayer ceramic through-core capacitor body, wherein the multilayer ceramic through-core capacitor body is provided with at least one inner hole for penetrating a first certain expansion alloy pipe; a guide pin penetrates through the first certain expansion alloy pipe; annealing the first certain expansion alloy pipe and then carrying out surface electroplating treatment; and the guide pin and the first definite expansion alloy pipe as well as the first definite expansion alloy pipe and the inner hole are welded and fixed by using lead-free solder. The first definite expansion alloy pipe of the invention is welded in the inner hole of the disc-shaped multilayer ceramic capacitor together, thereby enhancing the stress resistance of the disc-shaped multilayer ceramic capacitor. The solder for producing the multilayer ceramic feedthrough capacitor is not limited to welding materials with high lead content and good ductility, and can bear multiple temperature impacts with rapid change of high temperature and low temperature, so that the ceramic body cannot crack and fail due to temperature difference change, and the multilayer ceramic feedthrough capacitor with high reliability under severe external environment is obtained.)

1.A high-reliability multilayer ceramic feedthrough capacitor comprises a multilayer ceramic feedthrough capacitor body (1), wherein the multilayer ceramic feedthrough capacitor body (1) is provided with at least one inner hole (6); be equipped with guide pin (4) in hole (6), its characterized in that: the side wall of the inner hole (6) is connected with a first definite expansion alloy pipe (2); the first definite expansion alloy pipe (2) needs to be subjected to surface electroplating treatment after being annealed.

2. The highly reliable multilayer ceramic feedthrough capacitor of claim 1, wherein: the guide pin (4) is arranged in the first definite expansion alloy pipe (2) in a penetrating way; the guide pin (4) and the first definite expansion alloy pipe (2) are welded and fixed by lead-free solder (3); the first definite expansion alloy pipe (2) and the inner hole are welded and fixed or directly sintered and fixed by using lead-free solder (3).

3. The highly reliable multilayer ceramic feedthrough capacitor of claim 1, wherein: the first definite expansion alloy pipe (2) is a seamless pipe; and two ends of the fixed expansion alloy pipe (2) respectively extend out of an inner hole of the multilayer ceramic through-core capacitor body (1).

4. The highly reliable multilayer ceramic feedthrough capacitor of claim 1, wherein: the surface of the first definite expansion alloy pipe (2) is plated with one or a composite plating layer consisting of a plurality of plating layers of copper plating, nickel plating, silver plating, gold plating, tin plating and tin-lead plating.

5. The highly reliable multilayer ceramic feedthrough capacitor of claim 1, wherein: the multilayer ceramic through-core capacitor body (1) is a disc-shaped multilayer ceramic through-core capacitor, and the center of the multilayer ceramic through-core capacitor body is provided with an inner hole for penetrating a first certain expansion alloy pipe (2); and a second fixed expansion alloy tube (5) is welded and fixed on the periphery of the multilayer ceramic through-core capacitor body (1) by using a solder.

6. The highly reliable multilayer ceramic feedthrough capacitor of claim 1, wherein: the multilayer ceramic through-core capacitor body (1) is a planar array capacitor, and the center of the multilayer ceramic through-core capacitor body is provided with a plurality of inner holes which are arranged in a matrix manner; a first definite expansion alloy pipe (2) penetrates through the inner hole, and a guide pin (4) penetrates through the first definite expansion alloy pipe (2).

7. The method for preparing a highly reliable multilayer ceramic feedthrough capacitor as claimed in any of claims 1 to 5, comprising the steps of:

s1: selecting a fixed expansion alloy pipe with the diameter slightly smaller than the inner hole; the fixed expansion alloy pipe is a seamless pipe;

s2: cutting the fixed expansion alloy pipe into a length equivalent to the thickness of the multilayer ceramic through-core capacitor body;

s3: deburring the cut fixed expansion alloy pipe;

s4: carrying out vacuum annealing on the deburring-treated fixed expansion alloy pipe to eliminate machining stress and eliminate machining hardening;

s5: electroplating the inner and outer surfaces of the annealed definite expansion alloy pipe to prepare a first definite expansion alloy pipe;

s6: installing a first definite expansion alloy pipe in an inner hole of the multilayer ceramic through-core capacitor body through a tool, and inserting a guide pin in the inner hole; the multilayer ceramic through-core capacitor body is a disc-shaped multilayer ceramic through-core capacitor or a planar array capacitor;

s7: adding welding fluxes between the guide pin and the first definite expansion alloy pipe as well as between the first definite expansion alloy pipe and the inner hole for welding;

s8: finally, cleaning and drying the welded product; products with metal shells also require potting and curing.

8. The method for preparing a highly reliable multilayer ceramic feedthrough capacitor according to claim 7, wherein: the vacuum annealing process is to heat the material to 900 +/-50 ℃ in hydrogen atmosphere, preserve heat for 1-2h, cool the material to below 200 ℃ at the speed of not more than 5 ℃/min and take the material out of the furnace.

9. A highly reliable multilayer ceramic feedthrough capacitor as claimed in any of claims 1-6, characterized in that: the first definite expansion alloy pipe (2) is one of iron-nickel, iron-nickel-cobalt and iron-nickel-chromium series alloys.

10. The highly reliable multilayer ceramic feedthrough capacitor of claim 5, wherein: the second fixed expansion alloy pipe (5) is sleeved on the periphery of the disc-shaped multilayer ceramic through-core capacitor, and the size of the second fixed expansion alloy pipe is matched with that of the disc-shaped multilayer ceramic through-core capacitor; the second fixed expansion alloy pipe (5) is one of iron-nickel, iron-nickel-cobalt and iron-nickel-chromium series alloys.

11. The highly reliable multilayer ceramic feedthrough capacitor of claim 5, wherein: the multilayer ceramic through-core capacitor is arranged in a metal shell and encapsulated to prepare the anti-electromagnetic interference filter.

Technical Field

The invention relates to the technical field of capacitors, in particular to a high-reliability multilayer ceramic through capacitor and a manufacturing method thereof.

Background

Multilayer ceramic feedthrough capacitors are based on multilayer chip capacitor (MLCC) technology with only internal construction changes. They are fabricated similarly to MLCCs in that the layers of ceramic dielectric material are interleaved with noble metal electrodes, they are fabricated to form a monolithic structure, and then holes are drilled into the ceramic body to make contact with the inner or outer electrodes. A capacitance is formed between the aperture and the outer edge. In the case of a planar array, a capacitance is formed between each aperture and the outer edge. The capacitance characteristics of each aperture may vary within limits.

Single well devices are commonly referred to as "disks" and multi-well devices are referred to as planar arrays. The manufacturing process of the single-hole disc-shaped multilayer ceramic capacitor is roughly as follows: preparing porcelain slurry, casting, screen overlapping, laminating, processing appearance, high-temperature sintering, end sealing, end burning and surface treatment. After a series of processes, a disk-shaped multilayer ceramic capacitor composed of a ferroelectric ceramic body and a metal electrode is produced. The materials used are typically BaTiO3 ceramic dielectrics and PdAg or Ni inner electrodes. The structural interface of a typical discoidal multilayer ceramic capacitor is shown in fig. 1 and comprises a ferroelectric ceramic body 21 and metal electrodes 22 arranged inside and outside, and a centrally arranged bore 6 for fixing a pin.

The finished capacitor device is used to assemble anti-electromagnetic interference filters and filter assemblies. Their special construction gives them superior high frequency performance compared to surface mount patch filtering. This is very important for some applications, such as military, aviation and medical treatment. In the manufacture of filters against electromagnetic interference, the disc-shaped article or array is welded into a carrier tank or carrier and a centrally penetrating guide pin is welded. The assembly may then be sealed for improved mechanical and environmental protection. The signal to be filtered passes through the pin, and the outside of the filter body is grounded. The pins and the filter body are usually made of copper or a copper alloy, plated with nickel, silver or gold. A typical electromagnetic interference filter is constructed as shown in fig. 2, and includes a disk-shaped multilayer ceramic capacitor 23 and its central lead 24 and solder 25 for soldering, an outer metal case 26; an epoxy 27 for integral external sealing.

For several years, it has been recognized that soldering copper or copper alloy leads to the internal holes of disk-shaped ceramic capacitors can induce cracks in the ceramic structure. The cracks produced by this procedure are called "long bow" or "comma" cracks because they have such a very distinctive shape when viewed from the side or top cross-section, respectively.

These cracks may be benign but may also lead to complete electrical failure depending on whether they pass through the electrode footprint. It may be more feared that cracks may develop in the solder but only propagate during further processing or use, and then the capacitor may fail in operation.

Capacitor failures always tend to be short circuits. If the power supply is strong enough, the components can become very hot and can become a source of combustion.

The materials of the ceramic and the needle are usually fixed and can not be changed, so that the generation of welding cracks can be effectively avoided by using high-lead welding fluxes which are commonly used as 50Pb/50In, 95Pb/5In and 93.5Pb/5Sn/1.5Ag through continuous experiments In the prior art; high lead solder is used because of its high ductility, preventing excessive force from being transferred to the ceramic dielectric material, thereby avoiding the generation of cracks in a short period of time. Although a welding material with high lead content and good ductility is used, the ferroelectric ceramic of the disc-shaped multilayer ceramic capacitor is cracked to different degrees after being subjected to a plurality of temperature shocks of rapid change of high temperature and low temperature or being influenced by stress in a severe external environment, and the cracks are more likely to occur particularly at the welding position of the hole and the guide pin. Meanwhile, the use of the high-lead solder is obviously not beneficial to the lead-free process of electronic products, and can cause serious pollution to the environment.

Therefore, lead-free solder is used to ensure that the multilayer ceramic feedthrough capacitor does not generate cracks when being welded and the reliability under the severe external environmental conditions is a technical problem which needs to be solved at present.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a high-reliability multilayer ceramic feedthrough capacitor with low cost and no welding crack and a preparation method thereof.

The invention is realized by the following modes: a high-reliability multilayer ceramic feedthrough capacitor comprises a multilayer ceramic feedthrough capacitor body, wherein the multilayer ceramic feedthrough capacitor body is provided with at least one inner hole; a guide pin is arranged in the inner hole, and the side wall of the inner hole is connected with a first definite expansion alloy pipe; and the first certain expansion alloy pipe is subjected to surface electroplating treatment after annealing.

Further, the guide pin is arranged in the first certain expansion alloy pipe in a penetrating mode; the guide pin and the first definite expansion alloy pipe are welded and fixed by lead-free solder; and the first definite expansion alloy pipe and the inner hole are welded and fixed by using lead-free solder or directly sintered and fixed.

Further, the first definite expansion alloy pipe is a seamless pipe; two ends of the fixed expansion alloy pipe respectively extend out of an inner hole of the multilayer ceramic through-core capacitor body;

further, the surface of the first definite expansion alloy tube is electroplated with one or a composite coating of a plurality of coatings of copper plating, nickel plating, silver plating, gold plating, tin plating and tin-lead plating.

Furthermore, the multilayer ceramic feedthrough capacitor body is a disc-shaped multilayer ceramic feedthrough capacitor, and the center of the multilayer ceramic feedthrough capacitor body is provided with an inner hole for penetrating a first certain expansion alloy tube; and a second fixed expansion alloy tube is welded and fixed on the periphery of the multilayer ceramic through-core capacitor body by using welding flux.

Furthermore, the multilayer ceramic through-core capacitor body is a planar array capacitor, and the center of the multilayer ceramic through-core capacitor body is provided with a plurality of inner holes which are arranged in a matrix manner; a first definite expansion alloy pipe is arranged in the inner hole in a penetrating mode, and a guide pin is arranged in the first definite expansion alloy pipe in a penetrating mode.

A method for preparing a high-reliability multilayer ceramic through-core capacitor comprises the following steps:

s1: selecting a fixed expansion alloy pipe with the diameter slightly smaller than the inner hole; the fixed expansion alloy pipe is a seamless pipe;

s2: cutting the fixed expansion alloy pipe into a length equivalent to the thickness of the multilayer ceramic through-core capacitor body;

s3: deburring the cut fixed expansion alloy pipe;

s4: carrying out vacuum annealing on the deburring-treated fixed expansion alloy pipe to eliminate machining stress and eliminate machining hardening;

s5: electroplating the inner and outer surfaces of the annealed definite expansion alloy pipe to prepare a first definite expansion alloy pipe;

s6: installing a first definite expansion alloy pipe in an inner hole of the multilayer ceramic through-core capacitor body through a tool, and inserting a guide pin in the inner hole; the multilayer ceramic through-core capacitor body is a disc-shaped multilayer ceramic through-core capacitor or a planar array capacitor;

s7: adding welding fluxes between the guide pin and the first definite expansion alloy pipe as well as between the first definite expansion alloy pipe and the inner hole for welding;

s8: finally, cleaning and drying the welded product; products with metal shells also require potting and curing.

Further, the vacuum annealing process is to heat the material to 900 +/-50 ℃ in hydrogen atmosphere, preserve heat for 1-2h, and discharge the material from the furnace after cooling to below 200 ℃ at a speed of not more than 5 ℃/min.

Further, the first fixed expansion alloy pipe is one of iron-nickel, iron-nickel-cobalt and iron-nickel-chromium alloy.

Further, the second fixed expansion alloy pipe is sleeved on the periphery of the disc-shaped multilayer ceramic through-core capacitor, and the size of the second fixed expansion alloy pipe is matched with that of the disc-shaped multilayer ceramic through-core capacitor; the second fixed expansion alloy pipe is one of iron-nickel, iron-nickel-cobalt and iron-nickel-chromium series alloys.

Furthermore, the multilayer ceramic through-core capacitor is arranged in a metal shell and is encapsulated to prepare the anti-electromagnetic interference filter.

The invention has the beneficial effects that: the first expansion alloy pipe is welded to the inner hole or the inner hole and the outer ring of the disc-shaped multilayer ceramic capacitor together, so that the stress resistance of the disc-shaped multilayer ceramic capacitor is enhanced. The solder for producing the multilayer ceramic feedthrough capacitor is not limited to a welding material with high lead content and good ductility, and can bear multiple temperature impacts of high temperature and low temperature rapid change and then does not fail when the ductility of the used welding material is not good. Thereby obtaining a multilayer ceramic feedthrough capacitor of high reliability. By adding the first certain expansion alloy pipe, the direct transmission of overlarge stress to the ceramic dielectric material is avoided, and the direct transmission of the stress during expansion with heat and contraction with cold can be effectively reduced in an interval mode; meanwhile, the first certain expansion alloy pipe is added, so that the use of welding flux is reduced, and the requirement on high ductility of the welding flux is reduced. The first constant expansion alloy pipe and the ceramic have similar expansion coefficients, so that cracks can be avoided under the severe environment of cold and hot alternation, and the reliability of the capacitor is further improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a cross-sectional view of a typical discoidal multilayer ceramic capacitor;

FIG. 2 is a typical anti-electromagnetic interference filter structure;

FIG. 3 is a multilayer ceramic feedthrough capacitor structure of the present invention;

FIG. 4 is a diagram of an anti-EMI filter structure made with a multilayer ceramic feedthrough capacitor of the present invention;

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings. It is to be understood that the described embodiments are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front", "rear", "both ends", "one end", "the other end", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "provided," "connected," and the like are to be construed broadly, such as "connected," which may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those of ordinary skill in the art according to specific situations.

Example 1:

as shown in fig. 3, a high-reliability multilayer ceramic feedthrough capacitor comprises a multilayer ceramic feedthrough capacitor body 1, wherein the multilayer ceramic feedthrough capacitor body 1 is provided with an inner hole for penetrating a first definite expansion alloy tube 2; a guide pin 4 is arranged in the first definite expansion alloy pipe 2 in a penetrating way; the first definite expansion alloy pipe 2 is subjected to surface electroplating treatment after vacuum annealing; the guide pin 4 and the first definite expansion alloy pipe, and the first definite expansion alloy pipe and the inner hole are welded and fixed by using the lead-free solder 3.

In the present embodiment, the first definite expansion alloy tube 2 is a seamless tube; two ends of the fixed expansion alloy pipe 2 respectively extend out of an inner hole of the multilayer ceramic through-core capacitor body 1;

in this embodiment, the surface of the first definite expansion alloy pipe 2 is plated with copper.

In the embodiment, the vacuum annealing process is to heat the material to 900 +/-50 ℃ in a hydrogen atmosphere, preserve heat for 1-2 hours, and cool the material to below 200 ℃ at a speed of not more than 5 ℃/min and discharge the material.

In this embodiment, the first definite expansion alloy tube 2 is made of an iron-nickel alloy.

Example 2:

as shown in fig. 4, a high-reliability multilayer ceramic feedthrough capacitor includes a multilayer ceramic feedthrough capacitor body 1, the multilayer ceramic feedthrough capacitor body 1 is a disc-shaped multilayer ceramic feedthrough capacitor, and the multilayer ceramic feedthrough capacitor body 1 has an inner hole for inserting a first definite expansion alloy tube 2; and a second fixed expansion alloy pipe 5 is welded and fixed on the periphery of the multilayer ceramic through-core capacitor body 1 by using a solder. A guide pin 4 is arranged in the first definite expansion alloy pipe 2 in a penetrating way; the first definite expansion alloy pipe 2 is subjected to surface electroplating treatment after vacuum annealing; the guide pin 4 and the first definite expansion alloy pipe, and the first definite expansion alloy pipe and the inner hole are welded and fixed by using the lead-free solder 3.

In the present embodiment, the first definite expansion alloy tube 2 is a seamless tube; two ends of the fixed expansion alloy pipe 2 respectively extend out of an inner hole of the multilayer ceramic through-core capacitor body 1;

in this embodiment, the surface of the first definite expansion alloy tube 2 is plated with gold.

In the embodiment, the vacuum annealing process is to heat the material to 900 +/-50 ℃ in a hydrogen atmosphere, preserve heat for 1-2 hours, and cool the material to below 200 ℃ at a speed of not more than 5 ℃/min and discharge the material.

In this embodiment, the first definite expansion alloy tube 2 is made of an iron-nickel alloy.

In this embodiment, the second fixed expansion alloy tube 5 is sleeved on the periphery of the disc-shaped multilayer ceramic feedthrough capacitor, and the size of the second fixed expansion alloy tube is matched with that of the disc-shaped multilayer ceramic feedthrough capacitor; the second fixed expansion alloy pipe 5 is made of iron-nickel alloy.

In this embodiment, a metal shell 26 is provided outside the multilayer ceramic feedthrough capacitor; the second fixed expansion alloy pipe 5 is welded with the metal shell 26 to form the filter for resisting electromagnetic interference.

Example 3:

as shown in fig. 3, a high-reliability multilayer ceramic feedthrough capacitor comprises a multilayer ceramic feedthrough capacitor body 1, wherein the multilayer ceramic feedthrough capacitor body 1 is provided with an inner hole for penetrating a first definite expansion alloy tube 2; a guide pin 4 is arranged in the first definite expansion alloy pipe 2 in a penetrating way; the first definite expansion alloy pipe 2 is subjected to surface electroplating treatment after vacuum annealing; the guide pin 4 and the first definite expansion alloy pipe 2 are welded and fixed by lead-free solder 3; and the first definite expansion alloy pipe 2 is directly sintered and fixed with the inner hole.

In one embodiment of the invention, a method for preparing a high-reliability multilayer ceramic through-core capacitor comprises the following steps:

s1: selecting a fixed expansion alloy pipe with the diameter slightly smaller than the inner hole; the fixed expansion alloy pipe is a seamless pipe;

s2: cutting the fixed expansion alloy pipe into a length equivalent to the thickness of the multilayer ceramic through-core capacitor body;

s3: deburring the cut fixed expansion alloy pipe;

s4: carrying out vacuum annealing on the deburring-treated fixed expansion alloy pipe to eliminate machining stress and eliminate machining hardening;

s5: electroplating the inner and outer surfaces of the annealed definite expansion alloy pipe to prepare a first definite expansion alloy pipe;

s6: installing a first definite expansion alloy pipe in an inner hole of the multilayer ceramic through-core capacitor body through a tool, and inserting a guide pin in the inner hole; the multilayer ceramic through-core capacitor body is a disc-shaped multilayer ceramic through-core capacitor or a planar array capacitor;

s7: adding welding fluxes between the guide pin and the first definite expansion alloy pipe as well as between the first definite expansion alloy pipe and the inner hole for welding;

s8: finally, cleaning and drying the welded product; products with metal shells also require potting and curing.

Experimental example 1:

an array was assembled using 62Sn/36Pb/2Ag solder and the solder was reflowed using a 5-zone hot air reflow oven. As the array passes the final weld area, some of the needles are removed. After washing and drying, the array was sectioned and analyzed for internal structure. As a result, the crack is found around the hole where the lead is still in place. There are no "long arch splits" where the lead has been removed.

This shows that cracks are only created in the cooling section of the weld curve and the pin must be in place to create the stress that creates the long arch crack. This shows that the stress placed on the ceramic is external to the capacitor.

In view of the stresses generated during the cooling cycle, it is clear that the decisive stresses are generated by the shrinkage of the solder/pin as it cools. This force is generated by a mismatch between the amount of shrinkage and the rate at which the ceramic/solder/lead are attached to each other. In order to prevent cracking, it is necessary to change the properties of the connection to each other. And under the environment of alternating cold and hot changes, the changes are more obvious, and the probability of generating cracks is further improved.

Experimental example 2:

to analyze the effect of the different flux alloys, a set of tests were performed using the following alloys:

the present matrix represents examples of solder, conventional tin-lead solder and lead-free alternative solder currently used for filter assembly for emi protection.

In addition to the two refractory alloys, two sets of filter coupons were assembled in each solder case and reflowed using a 5-zone hot air reflow oven. Sample set 1 was forced cooled after zone 5 with a blower and had a standard weld curve. Sample set 2 was reflowed using the same solder profile, but the blower used for cooling was turned off and allowed to cool gradually to reduce the stress on the ceramic body.

The 95Pb/5In flux had a high melting point of 300 deg.C/313 deg.C and 93.5Pb/5In/1.5Ag, and also had a high melting point of 296 deg.C/301 deg.C. Both cannot be welded using a hot air furnace. These samples were assembled using a hot plate at 425 ℃. Preheating is not employed. The sample set 1 part was forced to cool directly in front of the bench fan. The sample set 2 part was gradually cooled.

After the finished products of the parts of the sample group 1 and the parts of the sample group 2 are kept in a test box at the low temperature of 55 ℃ for 15 minutes, the test samples are moved to a test box at the temperature of 125 ℃ for 15 minutes and then moved to a low-temperature box, and the transfer time of the test process from the low temperature to the high temperature or from the high temperature to the low temperature is not more than 5 minutes, so that the cycle is realized.

The sample is then sectioned and the capacitor structure around the solder joint is inspected for cracks.

The results are as follows:

1. flux variety 62Sn/36Pb/2Ag

A.62Sn/36Pb/2Ag sample 1 (forced Cooling)

80% of the junctions taken in cross-section have long arch cracks adjacent to the weld. All joints examined had some cracks in the ceramic body, mostly corner cracks.

B.62Sn/36Pb/2Ag sample 2 (Cooling gradually)

20% of the junctions taken in cross-section have long arch cracks adjacent to the weld. In total 60% of the joints had corner cracks associated with the flux meniscus.

2. Flux variety 60Sn/40Pb

A.60Sn/40Pb sample 1 (forced Cooling)

All cross-sectional joints have long arch splits adjacent the weld. All joints also have corner slits.

B.60Sn/40Pb sample 2 (Cooling gradually)

60% of the junctions taken in sections show long arch cracks adjacent to the weld points. In total 80% of the joints had corner cracks associated with the flux meniscus.

3. Flux variety 99.3Sn/0.7Cu

A.99.3Sn/0.7Cu sample 1 (forced Cooling)

All cross-sectional joints have long arch splits adjacent the weld. All joints also have corner slits.

B.99.3Sn/0.7Cu sample 2 (gradual cooling)

All cross-sectional joints have long arch splits adjacent the weld. All joints also have corner slits.

4. Flux variety 95.5Sn/3.8Ag/0.7Cu

A.95.5Sn/3.8Ag/0.7Cu sample 1 (forced Cooling)

All cross-sectional joints have long arch splits adjacent the weld. All joints also have corner slits.

B.95.5Sn/3.8Ag/0.7Cu sample 2 (gradual cooling)

40% of the joints in the cross-section have long arch cracks adjacent to the weld. A total of 80% of the joints had angular cracks, mainly the corner cracks associated with the bond pads.

5. Flux variety 50In/50Pb

A.50Pb/50In sample 1 (forced Cooling)

All joints taken in cross-section did not show any signs of induced cracking in the ceramic body.

B.50Pb/50In sample 2 (Cool Down)

All joints taken in cross-section did not show any signs of induced cracking in the ceramic body.

6. Flux variety 95Pb/5In

A.95Pb/5In sample 1 (forced Cooling)

All joints taken in cross-section did not show any signs of induced cracking in the ceramic body.

B.95Pb/5In sample 2 (gradual Cooling)

All joints taken in cross-section did not show any signs of induced cracking in the ceramic body.

7. Flux variety 93.5Pb/5Sn/1.5Ag

A.93.5Pb/5Sn/1.5Ag sample 1 (forced Cooling)

10% of the joints examined showed very small long arch cracks adjacent to the weld. These cracks were significantly smaller than those seen in the other samples.

B.93.5Pb/5Sn/1.5Ag sample 2 (gradual Cooling)

All cross-sectioned joints did not show any signs of induced cracking in the ceramic.

Summary of results

The invention uses the fixed expansion alloy pipe to be welded on the inner hole of the disc-shaped multilayer ceramic capacitor together for welding.

Experimental example 3:

to analyze the effect of the different flux alloys, a set of tests were performed using the following alloys:

in each case of the fluxes, two sets of filter coupons were assembled, with the exception of the two high melting point alloys, and the multilayer ceramic feedthrough capacitors within the filters were soldered using the structure of example 1, but the lead-free solder was replaced with a different solder required for the test and reflowed using a 5-zone hot air reflow oven. Sample set 1 was forced cooled after zone 5 with a blower and had a standard weld curve. Sample set 2 was reflowed using the same solder profile, but the blower used for cooling was turned off and allowed to cool gradually to reduce the stress on the ceramic.

The 95Pb/5In flux had a high melting point of 300 deg.C/313 deg.C and 93.5Pb/5In/1.5Ag, and also had a high melting point of 296 deg.C/301 deg.C. Both cannot be welded using a hot air furnace. These samples were assembled using a hot plate at 425 ℃. Preheating is not employed. The sample set 1 part was forced to cool directly in front of the bench fan. The sample set 2 part was gradually cooled.

After the finished products of the parts of the sample group 1 and the parts of the sample group 2 are kept in a test box at the low temperature of 55 ℃ for 15 minutes, the test samples are moved to a test box at the temperature of 125 ℃ for 15 minutes and then moved to a low-temperature box, and the transfer time of the test process from the low temperature to the high temperature or from the high temperature to the low temperature is not more than 5 minutes, so that the cycle is realized.

The sample is then sectioned and the capacitor structure around the solder joint is inspected for cracks.

The results are as follows:

1. flux variety 62Sn/36Pb/2Ag

A.62Sn/36Pb/2Ag sample 1 (forced Cooling)

All joints taken in cross-section did not show any signs of induced cracking in the ceramic body.

B.62Sn/36Pb/2Ag sample 2 (Cooling gradually)

All joints taken in cross-section did not show any signs of induced cracking in the ceramic body.

2. Flux variety 60Sn/40Pb

A.60Sn/40Pb sample 1 (forced Cooling)

All joints taken in cross-section did not show any signs of induced cracking in the ceramic body.

B.60Sn/40Pb sample 2 (Cooling gradually)

All joints taken in cross-section did not show any signs of induced cracking in the ceramic body.

3. Flux variety 99.3Sn/0.7Cu

A.99.3Sn/0.7Cu sample 1 (forced Cooling)

All joints taken in cross-section did not show any signs of induced cracking in the ceramic body.

B.99.3Sn/0.7Cu sample 2 (gradual cooling)

All joints taken in cross-section did not show any signs of induced cracking in the ceramic body.

4. Flux variety 95.5Sn/3.8Ag/0.7Cu

A.95.5Sn/3.8Ag/0.7Cu sample 1 (forced Cooling)

All joints taken in cross-section did not show any signs of induced cracking in the ceramic body.

B.95.5Sn/3.8Ag/0.7Cu sample 2 (gradual cooling)

All joints taken in cross-section did not show any signs of induced cracking in the ceramic body.

5. Flux variety 50In/50Pb

A.50Pb/50In sample 1 (forced Cooling)

All joints taken in cross-section did not show any signs of induced cracking in the ceramic body.

B.50Pb/50In sample 2 (Cool Down)

All joints taken in cross-section did not show any signs of induced cracking in the ceramic body.

6. Flux variety 95Pb/5In

A.95Pb/5In sample 1 (forced Cooling)

All joints taken in cross-section did not show any signs of induced cracking in the ceramic body.

B.95Pb/5In sample 2 (gradual Cooling)

All joints taken in cross-section did not show any signs of induced cracking in the ceramic body.

7. Flux variety 93.5Pb/5Sn/1.5Ag

A.93.5Pb/5Sn/1.5Ag sample 1 (forced Cooling)

All joints taken in cross-section did not show any signs of induced cracking in the ceramic body.

B.93.5Pb/5Sn/1.5Ag sample 2 (gradual Cooling)

All joints taken in cross-section did not show any signs of induced cracking in the ceramic body.

Summary of results

According to the experiment, the disc-shaped multilayer ceramic feedthrough capacitor with the structure of the invention is welded by using the common welding flux, no long arch crack is generated, and the problem of welding crack is effectively solved. Meanwhile, the lead-free solder is preferably used, and the environment is more environment-friendly than the high-lead solder.

The first expansion alloy pipe is welded to the inner hole or the inner hole and the outer ring of the disc-shaped multilayer ceramic capacitor together, so that the stress resistance of the disc-shaped multilayer ceramic capacitor is enhanced. The solder for producing the multilayer ceramic feedthrough capacitor is not limited to a welding material with high lead content and good ductility, and can bear a plurality of temperature impacts of rapid change of high temperature and low temperature even if the ductility of the used welding material is not good, so that the multilayer ceramic feedthrough capacitor with high reliability is obtained. By adding the first certain expansion alloy pipe, the direct transmission of overlarge stress to the ceramic dielectric material is avoided, and the direct transmission of the stress during expansion with heat and contraction with cold can be effectively reduced in an interval mode; meanwhile, due to the addition of the first certain expansion alloy pipe, the use of welding flux is reduced, and the requirement on high ductility of the welding flux is reduced; the first constant expansion alloy pipe and the ceramic have similar expansion coefficients, so that cracks can be avoided under the severe environment of cold and hot alternation, and the reliability of the capacitor is improved.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.