阅读说明：本技术 一种金属-陶瓷封装外壳的引出端结构及其制作工艺 (Leading-out terminal structure of metal-ceramic packaging shell and manufacturing process thereof ) 是由 钟永辉 袁小意 田晓忠 方军 于 2020-07-23 设计创作，主要内容包括：本发明公开了一种金属-陶瓷封装外壳的引出端结构及其制作工艺,其包括陶瓷基板,在所述陶瓷基板上设有金属焊盘,所述金属焊盘上设有金属引出端,所述金属引出端为弯折金属引出片,所述弯折金属引出片由依次连接的连接部、弯折部和引出部构成,其中,所述连接部设于所述金属焊盘上,且所述连接部和所述引出部平行。通过特殊的金属引线端和金属焊盘进行焊接,提高了引线端和陶瓷基板的结合力,使得外壳的可靠性高、环境适应性强。(The invention discloses a leading-out end structure of a metal-ceramic packaging shell and a manufacturing process thereof, wherein the leading-out end structure comprises a ceramic substrate, a metal bonding pad is arranged on the ceramic substrate, a metal leading-out end is arranged on the metal bonding pad, the metal leading-out end is a bent metal leading-out piece, and the bent metal leading-out piece is composed of a connecting part, a bent part and a leading-out part which are sequentially connected, wherein the connecting part is arranged on the metal bonding pad, and the connecting part is parallel to the leading-out part. The special metal lead terminal and the metal welding disc are welded, so that the binding force of the lead terminal and the ceramic substrate is improved, and the shell is high in reliability and strong in environmental adaptability.)

1. The leading-out end structure of the metal-ceramic packaging shell comprises a ceramic substrate, wherein a metal bonding pad is arranged on the ceramic substrate, and a metal leading-out end is arranged on the metal bonding pad.

2. The leading-out end structure of metal-ceramic package housing of claim 1, wherein the bending portion is suspended above the metal pad, and a bending angle between the bending portion and the connecting portion is 10 ° -20 °.

3. The metal-ceramic package can's lead-out structure of claim 1, wherein the ceramic substrate is an aluminum nitride substrate.

4. The lead-out structure of metal-ceramic package housing of claim 1, wherein the bent metal lead-out piece is made of 4J42 or 4J29 constant expansion alloy.

5. The metal-ceramic package can's outlet structure of claim 1, wherein the bent metal tab has a thickness of 0.1-0.2mm and a width of 0.2-0.5 mm.

6. The process for manufacturing the terminal structure of the metal-ceramic package shell according to any one of claims 1 to 5, comprising the steps of:

the metal leading-out end is manufactured by mechanical punch forming and consists of a connecting part, a bending part and a leading-out part;

manufacturing a metal bonding pad on a ceramic substrate, and carrying out nickel plating treatment on the ceramic substrate;

placing sheet-shaped brazing solder between the connecting part of the metal leading-out end and the metal pad and attaching the sheet-shaped brazing solder to the metal pad to form a pre-assembly body;

and feeding the preassembly into a brazing furnace, and brazing under the protection of a mixed atmosphere of a first gas and a second gas, wherein the first gas is nitrogen or inert gas, and the second gas is hydrogen.

7. The process of claim 6 wherein the brazing sheet is a silver copper alloy solder having a composition of Ag72Cu 28.

8. The manufacturing process according to claim 6, wherein the volume ratio of the second gas in the mixed atmosphere is 5 to 100%.

9. The manufacturing process according to claim 6, wherein the brazing process is as follows: firstly, heating from normal temperature to 750-; then heating to 790-810 ℃ at the heating rate of 10-20 ℃/min, and preserving the heat for 2-8 min; rapidly cooling to 750-770 ℃ at a cooling rate of 20-40 ℃/min, and then slowly cooling to room temperature at a cooling rate of 5-10 ℃/min.

Technical Field

The invention belongs to the field of electronic packaging, and particularly relates to a leading-out terminal structure of a metal-ceramic packaging shell and a manufacturing process thereof.

Background

A large number of passive circuits can be arranged in the ceramic substrate, and the metal-ceramic shell meets the requirements of miniaturization and high reliability of a packaging shell after the packaging density of electronic components is improved, so that the metal-ceramic shell becomes one of the packaging shells commonly used in the field of electronic packaging. However, as the packing density increases, the span between the terminals of the metal-ceramic case becomes denser and the size of the terminals becomes smaller. The lead span has been reduced from the conventional 2.54mm to 0.6mm in the limit, and the width of the lead has been reduced from the conventional 1.0mm to 0.2 mm.

In the existing manufacturing scheme of the metal-ceramic shell, the leading-out end of the metal-ceramic shell horizontally connects the flat metal leading-out end with the ceramic substrate through silver-copper brazing filler metal in a high-temperature brazing mode, the size of the metal leading-out end is only reduced, the leading-out end density of the metal-ceramic shell is simply improved, and the leading-out end is welded on the ceramic substrate due to small size, so that the bonding force between the leading-out end and the ceramic substrate is reduced, pins are easy to fall off under external force, the reliability of the shell is low, and the environmental adaptability is poor.

Disclosure of Invention

In view of the above, the present invention is directed to a metal-ceramic package case terminal structure and a manufacturing process thereof, in which a special metal lead terminal and a metal pad are soldered to each other, so that the bonding force between the lead terminal and a ceramic substrate is improved, the case has high reliability and strong environmental adaptability, and the above-mentioned problems are solved.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a leading-out end structure of a metal-ceramic packaging shell, which comprises a ceramic substrate, wherein a metal bonding pad is arranged on the ceramic substrate, a metal leading-out end is arranged on the metal bonding pad, the metal leading-out end is a bent metal leading-out piece, and the bent metal leading-out piece consists of a connecting part, a bent part and a leading-out part which are sequentially connected, wherein the connecting part is arranged on the metal bonding pad, and the connecting part is parallel to the leading-out part.

Furthermore, the bending part is arranged above the metal bonding pad in a suspended mode, and the bending angle between the bending part and the connecting part is 10-20 degrees.

Further, the ceramic substrate is an aluminum nitride substrate.

Furthermore, the material of the bent metal lead-out sheet is 4J42 or 4J29 fixed expansion alloy.

Furthermore, the thickness of the bent metal leading-out sheet is 0.1-0.2mm, and the width is 0.2-0.5 mm.

The invention also provides a manufacturing process of the leading-out terminal structure of the metal-ceramic packaging shell, which comprises the following steps:

the metal leading-out end is manufactured by mechanical punch forming and consists of a connecting part, a bending part and a leading-out part;

manufacturing a metal bonding pad on a ceramic substrate, and carrying out nickel plating treatment on the ceramic substrate;

placing sheet-shaped brazing solder between the connecting part of the metal leading-out end and the metal pad and attaching the sheet-shaped brazing solder to the metal pad to form a pre-assembly body;

and feeding the preassembly into a brazing furnace, and brazing under the protection of a mixed atmosphere of a first gas and a second gas, wherein the first gas is nitrogen or inert gas, and the second gas is hydrogen.

Further, the sheet brazing solder is silver-copper alloy brazing solder, and the composition of the brazing solder is Ag72Cu 28.

Further, in the mixed atmosphere, the volume proportion of the second gas is 5-100%.

Further, the specific process of brazing is as follows: firstly, heating from normal temperature to 750-; then heating to 790-810 ℃ at the heating rate of 10-20 ℃/min, and preserving the heat for 2-8 min; rapidly cooling to 750-770 ℃ at a cooling rate of 20-40 ℃/min, and then slowly cooling to room temperature at a cooling rate of 5-10 ℃/min.

Compared with the existing packaging shell, in the leading-out end structure of the packaging shell, due to the existence of the bending part, the metal leading-out end is flexible and not easy to fall off when being subjected to external force, so that the risk of rigid falling off is effectively avoided.

According to the invention, the metal leading-out end is bent in the brazing area, and the bent part is suspended over the ceramic metal bonding pad, so that brazing filler metal is accumulated between the ceramic metallized bonding pad and the bent part of the leading-out end during welding, and the leading-out end plays a role in flexible transition when being subjected to external force subsequently, thereby avoiding the risk of stress failure, improving the reliability and environmental adaptability of the shell, and further improving the qualification rate of products.

In addition, the conventional brazing process is not suitable for the welding of the bent lead terminals, so that the brazing process of the lead terminals is optimized, and the reliability of the pins is effectively improved through the step-by-step brazing process, particularly through rapid cooling.

Drawings

FIG. 1 is a schematic top view of a ceramic substrate 10 according to a preferred embodiment of the present invention;

FIG. 2 is a schematic top view of the leading end structure of the metal-ceramic package in accordance with a preferred embodiment of the present invention;

FIG. 3 is a schematic side view of the lead-out structure of the metal-ceramic package housing of FIG. 2;

fig. 4 is a schematic side view of the bent metal tab 30 of fig. 2;

fig. 5 is a schematic top view of the bent metal tab 30 of fig. 2;

fig. 6 is a schematic view of a connection structure between the bent metal tab 30 and the ceramic substrate 10 in fig. 2;

FIG. 7 is an enlarged view of a portion A of FIG. 6;

FIG. 8 is a temperature profile of a brazing process according to the present invention.

In the figure: 10-ceramic substrate, 20-metal pad, 30-bent metal lead-out sheet, 40-solder, 301-connection part, 302-bending part and 303-lead-out part.

Detailed Description

In order that the invention may be more fully understood, reference will now be made to the specific embodiments illustrated. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

The embodiment of the invention discloses a leading-out terminal structure of a metal-ceramic packaging shell, which comprises a ceramic substrate 10, as shown in fig. 1, the material of the ceramic substrate 10 can be selected conventionally in the field, and is not described again here, in the embodiment, the ceramic substrate 10 is an aluminum nitride substrate. Referring to fig. 1, the metal pads 20 are disposed on the ceramic substrate 10, the fixing manner of the metal pads 20 is conventional in the art, and will not be described in detail herein, and the positions thereof can be adjusted according to actual situations, in this embodiment, the metal pads 20 are disposed on the edges of two opposite sides of the ceramic substrate 10, respectively. Further, as shown in fig. 2 and 3, a metal terminal is welded on the metal pad 20, in this embodiment, the metal terminal is a bent metal tab 30, and its specific structure is as shown in fig. 4 and 5, the bent metal tab 30 is composed of a connection portion 301, a bent portion 302 and a lead portion 303 which are connected in sequence, specifically, referring to fig. 3 and 4, the connection portion 301 is welded on the metal pad 20, the bent metal tab 30 is led out from the metal pad 20 to the outside of the ceramic substrate 10, and the connection portion 301 and the lead portion 303 are parallel to each other. Referring to fig. 4, the bent portion 302 is suspended above the metal pad 20, and the solder 40 is deposited between the bent portion 302 and the metal pad 20, so that when the bent metal tab 30 is subsequently subjected to an external force, the bent portion 302 plays a role of flexible transition, as shown in fig. 6 and 7, thereby avoiding a risk of stress failure of the metal tab, and further improving reliability, environmental suitability, and product yield of the housing. Further, the bending angle of the bending portion 302 should not be too large or too small, and can be adjusted according to the requirement, in this embodiment, the bending angle of the bending portion 302 and the connecting portion 301 is between 10 ° and 20 °. In addition, the material of the bent metal tab 30 should be adapted according to the material of the ceramic substrate 10, and particularly, the thermal expansion coefficient should be close to that of the ceramic substrate 10, so in this embodiment, the material of the bent metal tab 30 is 4J42 or 4J29 fixed expansion alloy. The width of the bent metal lead-out piece 30 is not specifically limited, and can be adjusted according to the density of the welding lead-out ends on the ceramic substrate 10; the thickness of the bent metal tab 30 should be selected to have a certain strength and a certain flexibility, so that in this embodiment, the thickness of the bent metal tab 30 is 0.1-0.2mm and the width is 0.2-0.5 mm.

The invention also provides a manufacturing process of the leading-out end structure of the metal-ceramic packaging shell, which comprises the following steps:

the metal leading-out end is manufactured by mechanical punch forming and consists of a connecting part, a bending part and a leading-out part, and it can be understood that the metal leading-out end is integrally formed by mechanical punch forming, and the specific forming process is a conventional process in the field, so detailed description is omitted;

manufacturing a metal bonding pad on a ceramic substrate, and performing nickel plating treatment on the ceramic substrate, wherein the manufacturing of the metal bonding pad and the nickel plating treatment both adopt conventional technologies in the field, and therefore detailed description is omitted;

placing sheet-shaped brazing solder between the connecting part of the metal leading-out end and the metal pad and attaching the brazing solder to the metal pad to form a pre-assembly body;

and feeding the preassembly into a brazing furnace, and brazing under the protection of a mixed atmosphere of a first gas and a second gas, wherein the first gas is nitrogen or inert gas, and the second gas is hydrogen.

Further, the sheet brazing solder is silver-copper alloy brazing solder, and the composition of the brazing solder is Ag72Cu 28.

Further, in the mixed atmosphere, the volume proportion of the second gas is 5-100%.

Furthermore, compared with the existing lead-out part, the lead-out part can improve the peeling force of the pin to a certain extent by bending the metal lead-out end, but the lead-out part is welded by adopting the conventional silver-copper eutectic soldering process, the welding temperature is generally 810 and 830 ℃ (30-50 ℃ higher than the melting point of the solder), and the welding quality is not controlled due to high temperature and long time in the welding process. Therefore, the specific process of brazing in the present invention is: firstly, heating from normal temperature to 750-770 ℃ at a heating rate of 10-20 ℃/min, and preheating for 5-10min, thereby ensuring that the assembled metal leading-out end and the ceramic substrate are heated uniformly; then heating to 790-810 ℃ at the heating rate of 10-20 ℃/min, and preserving the heat for 2-8 min; after the temperature is rapidly reduced to 750-770 ℃ at the cooling rate of 20-40 ℃/min, the molten solder is ensured to be rapidly solidified, the phenomenon that the metalized pad of the ceramic substrate is damaged due to excessive metallurgical reaction of the silver-copper alloy solder is avoided, then the temperature is slowly reduced to room temperature at the cooling rate of 5-10 ℃/min, at the moment, the metal leading-out end is connected with the ceramic substrate into a whole through the solidified silver-copper alloy solder, the welding stress of the metal leading-out end and the ceramic substrate can be relieved through slow temperature reduction, the bonding force of the metal leading-out end and the ceramic substrate is improved, and the specific temperature change curve of the brazing process is shown in fig. 8.

The following will more clearly and completely describe the manufacturing method of the metal-ceramic shell leading-out end structure in the present invention with reference to specific embodiments, the structures in embodiments 1 to 3 are all as shown in fig. 1 to 5, and the differences only lie in the differences of materials, thicknesses, etc., and are not described in detail here.