阅读说明：本技术 一种梯度电子封装壳体的制备方法 (Preparation method of gradient electronic packaging shell ) 是由 吴昊 于 2020-03-30 设计创作，主要内容包括：本发明公开一种梯度电子封装壳体的制备方法,该方法具体为：根据功率与基板材料对T/R组件进行结构、热设计,确定底板导热率、热膨胀系数与厚度及壳体外形；根据底板热导率、热膨胀系数确定金刚石比例；根据封装壳体结构外形,制造石墨模具,并在石墨模具表面刷脱模剂,晾干；按封装壳体底板形状与厚度,在模具内填充填入金刚石颗粒粉末,预成型压实,形成预制体；将熔炼铝或铝合金熔液采用压力铸造的方法注入磨具内；脱模,得到近净成型的梯度壳体坯料,整体退火；对坯料进行精加工；然后去机加工应力退火。(The invention discloses a preparation method of a gradient electronic packaging shell, which comprises the following steps: carrying out structural and thermal design on the T/R assembly according to the power and the substrate material, and determining the heat conductivity, the thermal expansion coefficient and the thickness of the bottom plate and the appearance of the shell; determining the proportion of the diamond according to the heat conductivity and the thermal expansion coefficient of the bottom plate; manufacturing a graphite mold according to the structural shape of the packaging shell, brushing a release agent on the surface of the graphite mold, and airing; filling diamond particle powder into the mold according to the shape and thickness of the bottom plate of the packaging shell, performing and compacting to form a prefabricated body; pouring molten aluminum or aluminum alloy into a grinding tool by adopting a pressure casting method; demolding to obtain a near-net-shape gradient shell blank, and integrally annealing; carrying out finish machining on the blank; and then removing the machining stress and annealing.)

1. A preparation method of a gradient electronic packaging shell is characterized by comprising the following steps:

(1) carrying out structural and thermal design on the T/R assembly according to the power and the substrate material, and determining the heat conductivity, the thermal expansion coefficient and the thickness of the bottom plate and the appearance of the shell;

(2) determining the proportion of the diamond according to the heat conductivity and the thermal expansion coefficient of the bottom plate;

(3) manufacturing a graphite mold according to the structural shape of the packaging shell, brushing a release agent on the surface of the graphite mold, and airing;

(4) filling diamond particle powder into the mold according to the shape and thickness of the bottom plate of the packaging shell, performing and compacting to form a prefabricated body;

(6) pouring molten aluminum or aluminum alloy into a grinding tool by adopting a pressure casting method;

(7) demolding to obtain a near-net-shape gradient shell blank;

(8) integral annealing;

(9) carrying out finish machining on the blank;

(10) and (5) removing machining stress and annealing.

2. The method for manufacturing a gradient electronic packaging shell according to claim 1, wherein the base plate thermal conductivity is required to be 250W/m-K to 550W/m-K according to calculation, the thermal expansion coefficient is 5.5 to 13.5ppm/° c, and the diamond volume fraction ratio is determined to be 30% to 70%.

3. The method of claim 1, wherein the diamond powder is pre-screened to a particle diameter of 50 μm to 200 μm.

4. The method of claim 1, wherein the molten metal is pure aluminum or aluminum alloy 6063, 6061.

5. The method of claim 1, wherein the melting temperature is between 1000 ℃ and 1200 ℃.

6. The method for preparing a gradient electronic packaging shell according to claim 1, wherein the pressure is kept at 0.8-1.5 MPa for 10-15 min during die casting.

7. The method of claim 1, wherein the near net shape housing is made of two layers of different materials, namely a diamond aluminum composite material as a base material; the enclosure frame metal is pure metal or aluminum alloy.

Technical Field

The invention relates to the field of forming and processing of electronic packaging shells, in particular to a preparation method of a gradient electronic packaging shell.

Background

With the development of modern phased array radars, the output power is higher and higher, and the integration level of internal devices is higher and higher. The core component T/R assembly is often integrated by electronic packaging means, and its structural components include a housing, a substrate, a cover plate, and the like. The housing and the cover plate are usually machined from a metal material, and the substrate material is sintered from a ceramic. When the shell and the substrate are welded in a large area, the shell and the substrate are cracked frequently due to overlarge difference of thermal expansion coefficients of the shell and the substrate, and potential reliability hazards exist.

The metal matrix composite maintains the characteristics of high heat conductivity and excellent machining performance of metal, and simultaneously takes the characteristic of low expansion coefficient of the reinforcement material into consideration, and the finally obtained composite has the advantages of controllable expansion coefficient, high heat conductivity, plating capability and the like, and meets the requirement of T/R component packaging of a component.

In recent years, many studies and patents have been made based on metal matrix composites, including

Patent application No. 201810776288.X introduces a preparation method of an aluminum-silicon composite material for electronic packaging, and the preparation method has the disadvantages of complex preparation steps, high energy consumption and repeated smelting. Meanwhile, the thermal conductivity of the aluminum-silicon material is limited and is not more than 180W/m.K.

Patent application No. 201810668511.9 describes an aluminum silicon/aluminum silicon carbide gradient composite material and a preparation method thereof, which provides a thought for preparing gradient aluminum silicon alloy, but the composite material prepared by the method has limited thermal conductivity, and the thermal conductivity of a bottom heat dissipation area does not exceed 200W/m.K.

Conventional package housings are typically made from pure metal or homogeneous aluminum silicon composites by machining; in recent years, a method for preparing an aluminum silicon/silicon carbide aluminum material by using a spray deposition method and then machining the packaging shell has appeared. On one hand, the two technical routes are that the preparation process needs repeated smelting, the process is complex, the cost is high, and the requirements of environmental protection cannot be met; on the other hand, the thermal conductivity is limited by the thermophysical properties of the raw materials, and is limited and not more than 200W/m.K.

Therefore, the method for preparing the electronic packaging shell with low cost and high efficiency can effectively reduce the cost of the packaging structure and improve the production efficiency of the packaging shell.

Object of the Invention

The invention aims to provide a preparation method of a gradient electronic packaging shell.

The method can improve the heat conductivity of the bottom packaging structural part, the packaging surrounding frame material is different from the bottom material, and the airtight packaging can be realized by utilizing a high-efficiency and reliable laser fusion welding method. The method can realize near net shape forming, the repeated smelting is not needed in the manufacturing process, the process is green and environment-friendly, the energy consumption is low, and the production cost is effectively controlled.

The technical scheme for realizing the purpose of the invention is as follows:

in order to solve the problems, the solution of the invention is as follows:

(1) carrying out structural and thermal design on the T/R assembly according to the power and the substrate material, and determining the heat conductivity, the thermal expansion coefficient and the thickness of the bottom plate and the appearance of the shell;

(2) determining the proportion of the diamond according to the heat conductivity and the thermal expansion coefficient of the bottom plate;

(3) manufacturing a graphite mold according to the structural shape of the packaging shell, brushing a release agent on the surface of the graphite mold, and airing;

(4) filling diamond particle powder into the mold according to the shape and thickness of the bottom plate of the packaging shell, performing and compacting to form a prefabricated body;

(6) pouring molten aluminum or aluminum alloy into a grinding tool by adopting a pressure casting method;

(7) demolding to obtain a near-net-shape gradient shell blank;

(8) integral annealing;

(9) carrying out finish machining on the blank;

(10) and (5) removing machining stress and annealing.

Furthermore, the heat conductivity of the base plate is required to be 250-550W/mK and the thermal expansion coefficient is 5.5-13.5 ppm/DEG C according to calculation, and the volume fraction ratio of the diamond is determined to be 30-70%.

Further, the diamond powder needs to be pre-screened, and the diameter of the screened particles is 50-200 μm;

further, the molten metal can be pure aluminum or aluminum alloy 6063 or 6061. The smelting temperature is 1000-1200 ℃.

Further, the pressure is kept at 0.8-1.5 MPa for 10-15 min during die casting.

Furthermore, two layers of different materials exist in the prepared near net shape shell, namely, the bottom plate material is a diamond aluminum composite material; the enclosure frame metal is pure metal or aluminum alloy.

Compared with the prior art, the invention has the following remarkable advantages:

(1) the method overcomes the defects that the traditional preparation process needs repeated smelting, the process is complex, the cost is high, and the requirement of environmental protection cannot be met; the near-net-shape rough blank can be obtained by one-time smelting and die-casting, and the material removal in the finish machining process is little and almost no waste is generated;

(2) overcomes the defects that the thermal conductivity is limited by the thermophysical properties of the raw materials and is limited not to exceed 200W/m.K; the bottom thermal conductivity of the gradient composite shell prepared according to the invention exceeds 500W/m.K, and the thermal conductivity is high;

(3) the method of preparing the rough blank by near net shape forming overcomes the problems that the material removing is difficult and the cost is high when the homogeneous diamond/aluminum composite material is used for manufacturing the shell, and a common cutter cannot process; meanwhile, the problem that homogeneous diamond/aluminum cannot be subjected to laser sealing welding is solved by using the aluminum alloy as a frame opening material;

(4) the production efficiency of the packaging assembly is greatly improved, and the personalized customization needs are met.

Drawings

FIG. 1 is a schematic view of a T/R assembly housing.

FIG. 2 is a schematic view of a mold and a preform.

FIG. 3 is a schematic view of the die and preform casting relationship.

Fig. 4 is a schematic view of a near net shape blank after demolding.

Detailed Description

The invention will be further explained with reference to the drawings

Taking the radar T/R package assembly as an example, the substrate material is low temperature co-fired ceramic (L TCC):

(1) determining the structure of the T/R component according to the power and the substrate material, as shown in the attached figure 1;

(2) performing thermal design according to heat loss and chip crusting temperature, and determining that the bottom thermal conductivity of the shell is not lower than 450W/m.K, and the thermal expansion coefficient is not higher than 8 ppm/DEG C (0-200 ℃);

(3) determining the ratio of diamond to aluminum alloy in the composite material to be 70:30 (volume ratio) according to the heat conductivity and the thermal expansion coefficient of the bottom plate;

(4) manufacturing a graphite mold according to the structural shape of the packaging shell, brushing a release agent on the surface of the graphite mold, and airing; filling diamond particle powder into the mold according to the shape and thickness of the bottom plate of the packaging shell, performing and compacting to form a preform, as shown in fig. 2;

(5) injecting the smelted 6063 aluminum alloy melt into a grinding tool by adopting a pressure casting method, as shown in figure 3;

(6) demolding to obtain a near-net-shape gradient shell blank, as shown in FIG. 4;

(7) integral annealing;

(8) carrying out finish machining on the blank;

(9) and (5) removing machining stress and annealing.