Brazing method for low-void-ratio uncooled infrared detector tube shell

Abstract

The invention provides a brazing method for a low-void-ratio uncooled infrared detector tube shell, and relates to the technical field of brazing, and the brazing method comprises the steps that the side edge of a sealing ring is plated with gold to limit solder climbing, the solder is fixed in situ after being completely molten, and the void ratio is reduced. And meanwhile, the brazing temperature is adjusted, so that the welding flux is completely melted in a welding area, the viscosity of the welding flux is reduced, bubbles in the welding flux are discharged under the pressurization action of the clamp, and the void rate of ceramic welding conducted through a chain type brazing furnace is effectively reduced to be within 5%.

Description

Technical Field

[0001] The invention relates to the technical field of brazing, and in particular to a brazing method for a low-porosity non-refrigerated infrared detector tube shell. Background Art

[0002] HTCC multilayer ceramic material is one of the most commonly used materials in the field of infrared detector production. It has good corrosion resistance, high temperature resistance, electrical insulation and sealing properties. The commonly used brazing furnace for HTCC ceramics is a chain furnace. Under the protection of nitrogen-hydrogen mixed gas, metal parts are not easily oxidized, and the bonding strength with solder is high. It can operate continuously and heat up quickly. Chain furnaces are commonly used in the HTCC packaging industry. The conventional chain furnace brazing method is to metallize the ceramic surface, fix the welding piece and the metal part with a graphite clamp, and then put it into the chain furnace. The temperature is raised to 780℃~820℃ to melt the solder and connect the ceramic and metal parts together. Because a vacuum environment cannot be achieved in a conventional chain furnace, and the interior of the furnace is usually a nitrogen-hydrogen mixed gas, using conventional brazing methods will result in the following Figure 1 and Figure 2 As shown in the figure, a large number of welding voids are generated. Since the infrared detector is in a close vacuum environment, the welding voids will slowly release gas after long-term service in a vacuum, causing the infrared detector to fail. Therefore, the brazing void rate is inversely proportional to the service life of the infrared detector shell. At present, the main way to reduce the void rate is to adjust the chain furnace parameters, optimize the brazing fixture and other methods, but the generation of brazing voids involves many factors and has a certain randomness in the production process, so it is difficult to achieve stable and efficient improvement. Although vacuum brazing furnaces are used to improve the ceramic brazing void rate, vacuum brazing furnaces are expensive and the brazing cost is high, which greatly increases the brazing cost. In addition, vacuum furnaces cannot achieve complete vacuum, and there will be residual oxygen, which may cause oxidation and discoloration of the product surface and poor appearance. Summary of the invention

[0003] The object of the present invention is to provide a method for brazing a tube shell of an uncooled infrared detector with a low porosity, so as to solve the technical problem that a large number of welding voids occur during brazing in a conventional chain furnace.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A method for brazing a low-porosity uncooled infrared detector shell comprises the following steps:

[0006] 1) Nickel plating is performed on the surface of the ceramic metallized area;

[0007] 2) Sandblast the surface of metal parts and gold plate the non-welding areas;

[0008] 3) Use a fixture to clamp and fix the ceramic, metal parts and silver-copper solder so that the welding surfaces are in close contact. During this period, increase the clamping pressure to discharge the atmosphere inside the solder;

[0009] 4) Set the brazing furnace temperature zone, add a heat preservation zone before reaching the highest temperature, and the heat preservation zone duration is 1 to 30 minutes;

[0010] 5) Set the maximum temperature to 700-900℃ and keep it warm for 5-30 minutes to completely melt the silver-copper solder and reduce the viscosity of the solder. Under the pressure of the fixture, the bubbles inside the solder will be completely discharged. After the bubbles are completely discharged, it enters the cooling zone, the solder is cooled and fixed, and the brazing process is completed.

[0011] Preferably, in step 1), the ceramic metallization area is nickel plated on the surface by chemical plating or electroplating, and the nickel plating thickness is 0.1 to 9 μm.

[0012] Preferably, in step 1), the surface of the metal part is sandblasted using 150-1000 mesh glass sand or alumina sand, wherein the sandblasting particle size is recommended to be 220-320 mesh sand.

[0013] Preferably, the method of increasing the clamping pressure in step 3) includes tightening the screws in the clamp to increase the pressure or providing a pressure block above the clamp.

[0014] Preferably, a heat preservation zone is added before the temperature is raised to the highest temperature in step 4) to make the temperature of various parts of the ceramic, solder, and metal parts uniform, ensuring that the solder in each area can reach the melting point temperature at the same time.

[0015] The present invention includes two technical solutions in step 2):

[0016] First, after the metal part surface is sandblasted in step 2), the welding area of ​​the metal part is covered, and the non-welding area is gold-plated, wherein the thickness of the gold layer of the gold-plated metal part is 0.03-2 μm, and preferably, the thickness of the gold layer is 0.1-0.5 μm.

[0017] Second, after the surface of the metal part is sandblasted in step 2), nickel is plated on the welding area of ​​the metal part, and then the nickel-plated area is covered and gold is plated on the non-welding area, wherein the nickel layer thickness in the welding area of ​​the metal part is 0.1 to 9 μm, and the gold layer thickness of the gold-plated area is 0.03 to 2 μm, and preferably, the gold layer thickness is 0.1 to 0.5 μm.

[0018] The beneficial effects of the present invention are as follows: in the low-cost brazing process, the present invention adds a solder mask by gold plating in the non-welding area of ​​the metal part, and at the same time adjusts the brazing temperature so that the solder is completely melted in the welding area, reducing the viscosity of the solder, and under the action of the clamp pressurization, the bubbles in the solder are discharged, effectively reducing the void rate of ceramic welding using a chain brazing furnace, and reducing the void rate to less than 5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is an X-ray scan of the uncooled infrared detector shell using conventional brazing technology;

[0020] Figure 2 This is an X-ray scan of another uncooled infrared detector housing using conventional brazing technology;

[0021] Figure 3 This is a schematic diagram of the gold-plating area of ​​the metal part;

[0022] Figure 4 This is a schematic diagram of the nickel plating area of ​​a metal part;

[0023] Figure 5 This is an X-ray scan of the uncooled infrared detector shell after using the low-porosity brazing method; DETAILED DESCRIPTION

[0024] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0026] The specific embodiments of the present invention are described below with reference to the accompanying drawings.

[0027] Example 1

[0028] In this embodiment, a brazing method for a low-porosity uncooled infrared detector shell is proposed. The brazing objects are ceramic parts and metal parts, and the solder is silver-copper solder. The brazing method is as follows:

[0029] 1) The ceramic metallized area is nickel plated on the surface by chemical plating or electroplating, and the thickness of the nickel layer is preferably 0.1-9 μm. In this embodiment, the thickness of the nickel layer is 5 μm;

[0030] 2) The surface of the metal part is sandblasted with 150-1000 mesh glass sand or alumina sand, wherein the sandblasting particle size is recommended to be 220-320 mesh sand, and 280 mesh sand is used in this embodiment;

[0031] 3) After the metal welding area is covered with rubber, gold is plated in the non-covered area by chemical plating or electroplating, and the thickness of the gold layer is 0.03 to 2 μm. In this embodiment, the thickness of the gold layer is 0.2 μm;

[0032] 4) After assembling and fixing the ceramic, metal welding parts and silver-copper solder with a fixture, tighten the screws to make the welding surfaces closely contact and increase a certain pressure. The purpose is to continuously pressurize the fixture during the welding process to discharge the atmosphere inside the solder;

[0033] 5) Set the brazing furnace temperature zone, add a heat preservation zone before rising to the highest temperature, the heat preservation zone duration is 1 to 30 minutes, in this embodiment, the heat preservation zone duration is 25 minutes, the purpose is to make the temperature of each part of the ceramic, solder, and metal parts uniform, to ensure that the solder in each area can reach the melting point temperature at the same time;

[0034] 6) Set the maximum temperature to 800℃ and keep it warm for 15 minutes to completely melt the silver-copper solder and reduce the viscosity of the solder. Under the pressure of the fixture, the bubbles inside the solder will be completely discharged. At this time, the completely molten solder will spread and climb along the ceramic metallized area and the surface of the metal part. When it climbs to the gold-plated area, the solder climbing speed slows down and it is difficult to continue to spread over the gold layer, so that the solder is fixed in the welding area and enters the cooling zone. The solder is cooled and fixed, and the brazing process is completed.

[0035] Example 2

[0036] In this embodiment, a brazing method for a low-porosity uncooled infrared detector shell is proposed. The brazing objects are ceramic parts and metal parts, and the solder is silver-copper solder. The brazing method is as follows:

[0037] 1) The ceramic metallized area is nickel plated on the surface by chemical plating or electroplating, and the thickness of the nickel layer is preferably 0.1-9 μm. In this embodiment, the thickness of the nickel layer is 5 μm;

[0038] 2) The surface of the metal part is sandblasted with 150-1000 mesh glass sand or alumina sand, wherein the sandblasting particle size is recommended to be 220-320 mesh sand, and 280 mesh sand is used in this embodiment;

[0039] 3) After the surface of the metal part is sandblasted, nickel is plated on the welding area of ​​the metal part, and then the nickel-plated area is covered and gold is plated on the non-welding area; wherein the thickness of the gold layer is 0.03 to 2 μm, and in this embodiment, the thickness of the gold layer is 0.2 μm; the thickness of the nickel layer is 0.03 to 2 μm, and in this embodiment, the thickness of the nickel layer is 5 μm;

[0040] 4) After assembling and fixing the ceramic, metal welding parts and silver-copper solder with a fixture, tighten the screws to make the welding surfaces closely contact and increase a certain pressure. The purpose is to continuously pressurize the fixture during the welding process to discharge the atmosphere inside the solder;

[0041] 5) Set the brazing furnace temperature zone, add a heat preservation zone before rising to the highest temperature, the heat preservation zone duration is 1 to 30 minutes, in this embodiment, the heat preservation zone duration is 25 minutes, the purpose is to make the temperature of each part of the ceramic, solder, and metal parts uniform, to ensure that the solder in each area can reach the melting point temperature at the same time;

[0042] 6) Set the maximum temperature to 800℃ and keep it warm for 15 minutes to completely melt the silver-copper solder and reduce the viscosity of the solder. Under the pressure of the fixture, the bubbles inside the solder will be completely discharged. At this time, the completely molten solder will spread and climb along the ceramic metallized area and the surface of the metal part. When it climbs to the gold-plated area, the solder climbing speed slows down and it is difficult to continue to spread over the gold layer, so that the solder is fixed in the welding area and enters the cooling zone. The solder is cooled and fixed, and the brazing process is completed.

[0043] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0044] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A brazing method for a low porosity uncooled infrared detector shell, characterized in that: The following steps are involved: 1) Nickel plating is performed on the surface of the ceramic metallized area; 2) Sandblast the surface of metal parts and gold plate the non-welding areas; 3) Use a fixture to clamp and fix the ceramic, metal parts and silver-copper solder so that the welding surfaces are in close contact. During this period, increase the clamping pressure to discharge the atmosphere inside the solder; 4) Set the brazing furnace temperature zone, add a heat preservation zone before reaching the highest temperature, and the heat preservation zone duration is 1 to 30 minutes; 5) Set the maximum temperature to 700-900℃ and keep it warm for 5-30 minutes to completely melt the silver-copper solder and reduce the viscosity of the solder. Under the pressure of the fixture, the bubbles inside the solder will be completely discharged. After the bubbles are completely discharged, it enters the cooling zone, the solder is cooled and fixed, and the brazing process is completed.

2. The brazing method of a low porosity uncooled infrared detector shell according to claim 1, characterized in that: In step 1), the ceramic metallization area is nickel plated on the surface by chemical plating or electroplating, and the nickel plating thickness is 0.1 to 9 μm.

3. The brazing method of a low porosity uncooled infrared detector shell according to claim 1, characterized in that: In step 1), the surface of the metal part is sandblasted using 150-1000 mesh glass sand or alumina sand.

4. The brazing method of a low porosity uncooled infrared detector shell according to claim 1, characterized in that: In step 2), after the surface of the metal part is sandblasted, the welding area of ​​the metal part is covered and the non-welding area is gold plated.

5. The brazing method of a low porosity uncooled infrared detector shell according to claim 4, characterized in that: In step 2), the thickness of the gold layer of the gold-plated metal part is 0.03 to 2 μm.

6. The brazing method of a low porosity uncooled infrared detector shell according to claim 1, characterized in that: In step 2), after the surface of the metal part is sandblasted, the welding area of ​​the metal part is nickel-plated, and then the nickel-plated area is covered and the non-welding area is gold-plated.

7. A method for brazing a low porosity uncooled infrared detector shell according to claim 6, characterized in that: In step 2), the thickness of the nickel layer in the welding area of ​​the metal part is 0.1-9 μm, and the thickness of the gold layer of the gold plating is 0.03-2 μm.

8. The brazing method of a low porosity uncooled infrared detector shell according to claim 1, characterized in that: In step 3), the clamping pressure can be increased by tightening the screws in the clamp to increase the pressure or by placing a pressure block above the clamp.

9. The method for brazing a low porosity uncooled infrared detector shell according to claim 1, characterized in that: In step 4), before the temperature is raised to the highest level, a heat preservation zone is added to make the temperature of the ceramic, solder, and metal parts uniform, ensuring that the solder in each area can reach the melting point temperature at the same time.

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