阅读说明：本技术 氮化硅陶瓷基板上围坝的烧结焊接方法 (Sintering welding method for upper box dam of silicon nitride ceramic substrate ) 是由 周孔礼 于 2020-05-14 设计创作，主要内容包括：本发明公开了一种氮化硅陶瓷基板上围坝的烧结焊接方法,包括如下步骤：第一步,将氮化硅陶瓷基板通过厚膜印刷技术印刷出金属线路涂层,该金属线路涂层形状与需要焊接到氮化硅陶瓷上的围坝的形状适配；第二步,在氮化硅陶瓷基板的金属线路涂层上放置合金焊料,再将围坝隔着合金焊料印刷或放置到氮化硅陶瓷基板上,围坝与金属线路涂层的形状对应；第三步,将氮化硅陶瓷基板和围坝放入到烧结装置中；第四步,向烧结装置中冲入保护气氛；第五步,启动烧结装置进行烧结,且烧结的温度为150℃-1500℃；第六步,烧结完成。本发明针对氮化硅陶瓷的围坝焊接采用烧结焊接的方式进行焊接,相对于现有技术中采用磁控溅射,更加方便操作,成本更低。(The invention discloses a sintering welding method of a box dam on a silicon nitride ceramic substrate, which comprises the following steps: firstly, printing a metal circuit coating on a silicon nitride ceramic substrate by a thick film printing technology, wherein the shape of the metal circuit coating is matched with that of a box dam needing to be welded on the silicon nitride ceramic; secondly, alloy solder is placed on the metal circuit coating of the silicon nitride ceramic substrate, and then the box dam is printed or placed on the silicon nitride ceramic substrate through the alloy solder, wherein the shape of the box dam corresponds to that of the metal circuit coating; thirdly, putting the silicon nitride ceramic substrate and the box dam into a sintering device; fourthly, injecting protective atmosphere into the sintering device; fifthly, starting a sintering device for sintering, wherein the sintering temperature is 150-1500 ℃; and sixthly, finishing sintering. The invention adopts a sintering welding mode to weld the enclosure dam of the silicon nitride ceramics, and is more convenient to operate and lower in cost compared with the magnetron sputtering adopted in the prior art.)

1. A sintering welding method of a box dam on a silicon nitride ceramic substrate is characterized by comprising the following steps:

firstly, printing a metal circuit coating on a silicon nitride ceramic substrate by a thick film printing technology, wherein the shape of the metal circuit coating is matched with that of a box dam needing to be welded on the silicon nitride ceramic;

secondly, alloy solder is placed on the metal circuit coating of the silicon nitride ceramic substrate, and then the dam is printed or placed on the silicon nitride ceramic substrate through the alloy solder, wherein the shape of the dam corresponds to that of the metal circuit coating;

thirdly, putting the silicon nitride ceramic substrate and the box dam into a sintering device;

fourthly, injecting protective atmosphere into the sintering device;

fifthly, starting the sintering device to sinter at the temperature of 150-1500 ℃;

and sixthly, finishing sintering.

2. The method for sinter welding of a dam on a silicon nitride ceramic substrate of claim 1, wherein said thick film printing technique comprises the steps of:

a first step of preparing a silicon nitride ceramic substrate for printing and a metal paste for printing and placing;

secondly, thick film screen printing is carried out on the silicon nitride ceramic substrate by utilizing the metal paste, and the thickness of a circuit formed by the metal paste is 10-200 mu m;

thirdly, sintering the circuit formed in the last step, and adding mixed gas through a high-temperature tunnel furnace to perform high-temperature sintering at the sintering temperature of 150-1500 ℃;

and fourthly, manufacturing the silicon nitride ceramic substrate with the metal circuit coating.

3. The method for sinter welding of a dam on a silicon nitride ceramic substrate of claim 2, wherein the protective atmosphere is nitrogen.

4. The method for sintering and welding a dam on a silicon nitride ceramic substrate according to claim 3, wherein the concentration of the nitrogen gas is 95 to 99%.

5. The method for sintering and bonding a dam on a silicon nitride ceramic substrate according to claim 4, wherein the pressure of the gas for sintering in said sintering apparatus is 2 to 3 atmospheres.

Technical Field

The invention relates to the technical field of glass packaging, in particular to a sintering welding method for a box dam on a silicon nitride ceramic substrate.

Background

Si₃N₄Has three crystal structures, namely an alpha phase, a beta phase and a gamma phase (wherein the alpha phase and the beta phase are the most common forms), which are all hexagonal structures, and the powder and the substrate are grey white. Si₃N₄The ceramic substrate has the advantages of 320GPa of elastic modulus, 920MPa of bending strength, 3.2 multiplied by 106/DEG C of thermal expansion coefficient, 9.4 of dielectric constant, high hardness, high strength, small thermal expansion coefficient, high corrosion resistance and the like. Due to Si₃N₄The ceramic crystal structure is complex and has large phonon scattering, so that the early research believes that the thermal conductivity is low, such as Si₃N₄The heat conductivity of products such as bearing balls, structural parts and the like is only 15W/(m.K) -30W/(m.K). In 1995, Haggerty et al showed by classical solid transmission theoretical calculation that Si₃N₄The main reasons for the low thermal conductivity of the material are related to defects, impurities and the like in crystal lattices, and the theoretical value of the material is predicted to be up to 320W/(m.K). Then, increasing Si₃N₄A great deal of research is carried out on the thermal conductivity of materials, the thermal conductivity of silicon nitride ceramics is continuously improved through process optimization, and 177W/(m.K) is broken through at present.

Si₃N₄The ceramic heat transfer mechanism is also phonon heat transfer. Impurities in crystal lattices are often accompanied with structural defects such as vacancies, dislocation and the like, so that the phonon mean free path is reduced, the heat conductivity is reduced, and the preparation of high-purity powder is to prepare high-heat-conductivity Si₃N₄The key of the ceramic. At present, Si is commercially available on the market₃N₄The preparation methods of the powder mainly comprise two methods, namely a direct silicon powder nitriding method and a silicon imine pyrolysis method. The former process is mature and the production cost is low, so most enterprises at home and abroad use the method to produce Si₃N₄And (3) powder lot. But produced by the process Si₃N₄The powder contains impurities such as Fe, Ca, Al and the like, and can be removed by acid cleaning, but the production cost is greatly increased. The latter can prepare Si with higher sintering activity₃N₄The powder material contains no metal impurity elements, has particle size distribution of 0.2-1 micron, great output and high technological difficulty.

Si₃N₄The ceramic sintering aid is typically a metal oxide, a rare earth oxide, or a mixture of the two. Zhou et al use Y₂O₃The thermal conductivity of the silicon nitride prepared by the MgO sintering aid reaches 177W/(m.K), which is the Si reported so far₃N₄The highest thermal conductivity of the ceramic. However, the oxide sintering aid may be in Si₃N₄Oxygen atoms are introduced into the crystal, resulting in a reduction in thermal conductivity. The use of non-oxide sintering aids to reduce oxygen content and to purify Si₃N₄The crystal lattice, the reduction of crystal boundary glass phase, the improvement of thermal conductivity and high-temperature mechanical property have important significance. MgSiN for Zhuangzhenhua et al₂And MgSiN₂And Y₂O₃The mixture is used as a sintering aid to prepare Si under the same conditions₃N₄The former has a thermal conductivity of 90W/(mK), while the latter is only 70W/(mK). Hayashi et al in Yb₂O₃-MgSiN₂And Yb₂O₃MgO as a sintering aid, Si3N4 ceramic was prepared under the same conditions, and as a result, the thermal conductivity of the former was found to be higher.

Si₃N₄The ceramic sintering method mainly comprises reaction sintering, normal pressure sintering, hot pressing sintering, discharge plasma sintering and the like. The reactive sintering has the advantages of low linear shrinkage rate, low cost and the like, but has low density, poor mechanical property and low thermal conductivity. Si prepared by normal pressure sintering and hot pressing sintering₃N₄The ceramic has better mechanical property, but low thermal conductivity and higher cost. Gas pressure sintering refers to the application of a gas (usually N) at a pressure of about 1MPa to about 10MPa during sintering₂) To suppress Si₃N₄Decomposing, promoting the powder densification and obtaining the high-density product. The spark plasma sintering is equivalent by a pressure field, a temperature field and a current fieldA new technique for preparing ceramics by sintering is needed.

Among the ceramic materials which have been used as substrate materials, Si₃N₄The ceramic has high bending strength (more than 800MPa) and good wear resistance, is a ceramic material with the best comprehensive mechanical property, and has the smallest thermal expansion coefficient, so the ceramic is considered to be a potential power device packaging substrate material. But the preparation process is complex, the cost is high, the thermal conductivity is low, and the method is mainly suitable for the field with high strength requirement and low heat dissipation requirement.

When the silicon nitride ceramic substrate is used as an LED substrate, a box dam needs to be welded, the existing welding is carried out in a magnetron sputtering mode, the operation is relatively complex, and the cost is higher.

Disclosure of Invention

In view of the above problems of the prior art, the present invention provides a sintering welding method for a dam on a silicon nitride ceramic substrate, comprising the steps of:

firstly, printing a metal circuit coating on a silicon nitride ceramic substrate by a thick film printing technology, wherein the shape of the metal circuit coating is matched with that of a box dam needing to be welded on the silicon nitride ceramic;

secondly, alloy solder is placed on the metal circuit coating of the silicon nitride ceramic substrate, and then the dam is printed or placed on the silicon nitride ceramic substrate through the alloy solder, wherein the shape of the dam corresponds to that of the metal circuit coating;

thirdly, putting the silicon nitride ceramic substrate and the box dam into a sintering device;

fourthly, injecting protective atmosphere into the sintering device;

fifthly, starting the sintering device to sinter at the temperature of 150-1500 ℃;

and sixthly, finishing sintering.

Preferably, the thick film printing technique comprises the steps of:

a first step of preparing a silicon nitride ceramic substrate for printing and a metal paste for printing and placing;

secondly, thick film screen printing is carried out on the silicon nitride ceramic substrate by utilizing the metal paste, and the thickness of a circuit formed by the metal paste is 10-200 mu m;

thirdly, sintering the circuit formed in the last step, and adding mixed gas through a high-temperature tunnel furnace to perform high-temperature sintering at the sintering temperature of 150-1500 ℃;

and fourthly, manufacturing the silicon nitride ceramic substrate with the metal circuit coating.

Preferably, the protective atmosphere is nitrogen.

Preferably, the concentration of the nitrogen is 95-99%.

Preferably, the pressure of the sintering gas in the sintering device is 2-3 atmospheric pressures.

Has the advantages that: the welding method is novel in concept, reasonable in design and convenient to use, and the welding method aims at welding the silicon nitride ceramic box dam by adopting a sintering welding mode, so that the operation is more convenient and the cost is lower compared with the method of adopting magnetron sputtering in the prior art.

Drawings

FIG. 1 is an exploded view of a bonding structure of a silicon nitride ceramic substrate according to an embodiment of the present invention.

Detailed Description

The invention is further illustrated by the following examples in conjunction with the accompanying drawings: