A process method for preventing solder overflow of AMB substrates during soldering

Abstract

The application discloses a process method for preventing solder overflow of an AMB substrate in a soldering process, and specifically comprises the following steps: S1. First, an AMB ceramic copper-clad plate substrate is cleaned and dried to obtain a ceramic sheet with a clean surface; S2. Active solder is screen-printed onto the surface of the ceramic sheet, so that the active solder is uniformly coated on the surface of the ceramic sheet, and an active solder layer with a uniform active solder metal powder structure is obtained; S3. A pre-prepared oxygen-free copper foil is attached to the surface of the ceramic sheet coated with the active solder, and the oxygen-free copper foil is positioned; S4. The frame edge of the oxygen-free copper foil is covered with a soft pad, a supporting plate is used as a cover plate before soldering, and the supporting plate is placed into a soldering furnace for soldering; and S5. A pressure structure in which a high-pressure area surrounds a low-pressure area is formed, so that high-temperature liquid solder cannot overflow. The application prevents solder overflow and greatly increases the internal solder thickness.

Description

Technical Field

[0001] This invention relates to the field of AMB ceramic substrate technology, and in particular to a process method to prevent solder overflow during the brazing process of AMB substrates. Background Technology

[0002] The bonding in the AMB ceramic substrate is achieved through a chemical reaction between the ceramic and the active metal solder at a certain temperature. Compared with traditional ceramic substrates, the ceramic used in AMB has higher thermal conductivity and a coefficient of thermal expansion closer to that of silicon. Therefore, the AMB substrate has higher bonding strength and reliability. Combined with silver sintering process and high-power silicon carbide chips, the AMB copper layer with active metal coating can realize high-power, high-efficiency heat dissipation and high-reliability packaging modules that can withstand 8,000 thermal shocks. It has been widely used in electric vehicles, electric locomotives and high-speed trains.

[0003] At high temperatures, the solder is in a molten state. Due to the pressure involved in the substrate brazing process, the solder is squeezed to a certain extent, causing the molten solder to be squeezed out of the interface layer between the copper foil and the ceramic, resulting in poor bonding. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to overcome the shortcomings of the prior art and provide a process method to prevent solder overflow during the soldering process of AMB substrates.

[0005] Technical solution: A process method to prevent solder overflow during the soldering process of AMB substrates, the specific steps of which include:

[0006] S1. First, the AMB ceramic copper-clad laminate substrate is cleaned and dried to obtain a ceramic sheet with a clean surface morphology. The ceramic sheet serves as the interface for the active solder coating.

[0007] S2. The active solder is screen-printed onto the surface of the ceramic sheet, so that the active solder is evenly coated onto the surface of the ceramic sheet. Through the pre-baking process, the organic matter in the active solder is removed by debinding, and an active solder layer with a uniform active solder metal powder structure is obtained.

[0008] S3. Attach the pre-prepared oxygen-free copper foil to the surface of the ceramic sheet coated with active solder, and position the oxygen-free copper foil;

[0009] S4. After the oxygen-free copper foil is pre-assembled, a soft pad is used to cover the frame edge of the oxygen-free copper foil. Before brazing, a graphite cover is used, and the foil is placed into the brazing furnace for brazing. During the brazing process, the oxygen-free copper foil, the active solder layer and the AMB ceramic copper-clad laminate substrate are fully brazed and fused together.

[0010] S5. Under the same pressure, the pressure around the edge of the oxygen-free copper foil is enhanced by the increased thickness of the soft pad, and the pressure in the central area of the oxygen-free copper foil is relatively low, so that the liquefied solder is not easy to flow out to the interface layer of the oxygen-free copper foil and the ceramic sheet, forming a high-pressure area surrounding a low-pressure structure, so that the high-temperature liquid solder cannot overflow, thereby eliminating solder overflow.

[0011] Further improvement of the application is that in step S2, the active solder is printed through a silk screen frame.

[0012] Further improvement of the application is that in step S2, the temperature of the pre-baking process is 50-150 DEG C.

[0013] Further improvement of the application is that in step S3, the copper content of the oxygen-free copper foil is not limited.

[0014] Further improvement of the application is that in step S4, the soft pad is a high-temperature-resistant soft material.

[0015] Further improvement of the application is that the thickness of the high-temperature-resistant soft material is not limited to a specific thickness value.

[0016] Further improvement of the application is that the width of the high-temperature-resistant soft material is not limited.

[0017] Further improvement of the application is that the mesh number of the silk screen frame is 100-600 meshes, which is determined according to the solder type.

[0018] Further improvement of the application is that the temperature of the AMB ceramic copper-clad plate substrate for drying treatment is 150-600 DEG C, which is determined according to the solder type, and the duration of the drying treatment is not limited.

[0019] Compared with the prior art, the process method for eliminating solder overflow during the soldering process of the AMB substrate provided by the application at least achieves the following beneficial effects:

[0020] The pressure around the edge of the application is enhanced by the increased thickness of the soft pad, and the pressure in the central area is relatively low, so that the liquefied solder is not easy to flow out to the interface layer of the copper foil and the ceramic, forming a high-pressure area surrounding a low-pressure structure, so that the high-temperature liquid solder cannot overflow, thereby eliminating solder overflow. The internal solder thickness is greatly increased, so that the active solder layer and the ceramic sheet and the oxygen-free copper foil can effectively and fully react, achieving excellent bonding effect. BRIEF DESCRIPTION OF DRAWINGS

[0021] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

[0022] Fig. 1 is a structural front view of the present application;

[0023] Fig. 2 is a structural top view of the present application.

[0024] Reference signs: 1 - ceramic sheet; 2 - active solder layer; 3 - oxygen-free copper foil; 4 - soft pad. DETAILED DESCRIPTION

[0025] Various exemplary embodiments of the present application will now be described in detail. It should be noted that the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments are not limiting to the scope of the present application unless otherwise specifically stated. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way limiting to the scope of the present application and its applications or uses.

[0026] Techniques, methods, and apparatus known to those of ordinary skill in the relevant art can not be discussed in detail herein, but should be considered as if the discussion were incorporated herein in its entirety. In the interests of brevity and clarity, all examples given herein are illustrative only, and are not intended to be in any way limiting. Other examples of the exemplary embodiments will be apparent to those of ordinary skill in the art from consideration of the specification and practice of the exemplary embodiments as described herein.

[0027] As shown in Figs. 1-2 , a process method for preventing solder overflow of an AMB substrate during soldering, the specific steps include:

[0028] S1. First, the AMB ceramic copper-clad plate substrate is cleaned and dried to obtain a ceramic sheet 1 with a clean surface morphology, which serves as the interface of the active solder coating;

[0029] S2. The active solder is screen printed onto the surface of the ceramic sheet 1, so that the active solder is uniformly coated onto the surface of the ceramic sheet 1. Through a pre-baking process, the organic matter in the active solder is removed by degassing to obtain an active solder layer 2 with a uniform active solder metal powder structure;

[0030] S3. The pre-prepared oxygen-free copper foil 3 is attached to the surface of the ceramic sheet 1 coated with active solder, and the oxygen-free copper foil 3 is positioned;

[0031] S4. After the oxygen-free copper foil 3 is pre-assembled, the soft pad 4 is used to cover the frame edge of the oxygen-free copper foil 3, and graphite is used as a cover plate before soldering, and placed into a soldering furnace for soldering. During the soldering process, the oxygen-free copper foil 3, the active solder layer 2, and the AMB ceramic copper-clad plate substrate are fully soldered and fused.

[0032] S5. Under the same pressure, the pressure around the edge of the oxygen-free copper foil 3 is enhanced by the increased thickness of the soft pad 4, and the pressure in the central area of the oxygen-free copper foil 3 is relatively low, so that the liquefied solder is not easy to flow out to the interface layer of the oxygen-free copper foil 3 and the ceramic sheet 1, forming a high-pressure area surrounding a low-pressure structure, so that the high-temperature liquid solder cannot overflow, thereby preventing solder overflow.

[0033] The further improvement of the present application is that the active solder is printed through a silk screen frame.

[0034] The further improvement of the present application is that the temperature of the pre-baking process is 50-150℃.

[0035] The further improvement of the present application is that the copper content of the oxygen-free copper foil 3 is not limited.

[0036] The further improvement of the present application is that the soft pad 4 is a high-temperature-resistant soft material, which is not only light in weight, high in strength and hardness, but also has a certain flexibility and is environmentally friendly.

[0037] The further improvement of the present application is that the thickness of the high-temperature-resistant soft material is not limited to a specific value.

[0038] The further improvement of the present application is that the width of the high-temperature-resistant soft material is not limited.

[0039] The further improvement of the present application is that the silk screen mesh of the silk screen frame is 100-600 mesh, which is determined according to the solder type.

[0040] The further improvement of the present application is that the temperature of the drying treatment of the AMB ceramic copper-clad plate substrate is 150-600℃, which is determined according to the solder type, and the duration of the drying treatment is not limited.

[0041] In summary, the present application provides a process method for preventing solder overflow during the soldering process of the AMB substrate. The pressure around the edge is enhanced by the increased thickness of the soft pad, and the pressure in the central area is relatively low, so that the liquefied solder is not easy to flow out to the interface layer of the copper foil and the ceramic, forming a high-pressure area surrounding a low-pressure structure, which prevents the high-temperature liquid solder from overflowing, thereby achieving the technical effect of preventing solder overflow. The internal solder thickness is greatly increased, so that the active solder layer and the ceramic sheet and the oxygen-free copper foil can effectively and fully react, achieving excellent bonding effect and being convenient and reliable.

[0042] The specific embodiments described herein are merely illustrative of the spirit of the present application. Those skilled in the art of the present application can make various modifications or supplements to the described specific embodiments or replace them with similar ways, without deviating from the spirit of the present application or exceeding the scope defined by the appended claims.

Claims

1. A process for eliminating solder overflow during soldering of an AMB substrate, comprising: The specific steps include: S1. First, the AMB ceramic copper-clad plate substrate is cleaned and dried to obtain a ceramic sheet (1) with a clean surface morphology, which serves as the interface of the active solder coating; S2. The active solder is screen printed onto the surface of the ceramic sheet (1), so that the active solder is uniformly coated on the surface of the ceramic sheet (1). After pre-baking process treatment, the organic matter in the active solder is discharged, and an active solder layer (2) with a uniform active solder metal powder structure is obtained; S3. The pre-prepared oxygen-free copper foil (3) is attached to the surface of the ceramic sheet (1) coated with active solder, and the oxygen-free copper foil (3) is positioned; S4. After the oxygen-free copper foil (3) is pre-assembled, a soft pad (4) is used to cover the frame edge of the oxygen-free copper foil (3). Before soldering, a supporting plate is used as a cover plate, and is placed into a soldering furnace for soldering. During the soldering process, the oxygen-free copper foil (3), the active solder layer (2) and the AMB ceramic copper-clad plate substrate are fully soldered and fused; S5. Under the same pressure, the pressure around the edge of the oxygen-free copper foil (3) is enhanced by the increased thickness of the soft pad (4), and the pressure in the central area of the oxygen-free copper foil (3) is relatively low, so that the liquefied solder is not easy to flow out to the interface layer between the oxygen-free copper foil (3) and the ceramic sheet (1), forming a high-pressure area surrounding a low-pressure pressure structure, so that the high-temperature liquid solder cannot overflow, thereby preventing solder overflow.

2. The process method for preventing solder overflow during soldering of an AMB substrate according to claim 1, characterized in that: In step S2, the active solder is screen printed through a screen printing screen frame.

3. The process method for preventing solder overflow during soldering of an AMB substrate according to claim 1, characterized in that: In step S2, the pre-baking process treatment temperature is 50-150°C.

4. The process method for preventing solder overflow during soldering of an AMB substrate according to claim 1, characterized in that: In step S3, the copper content of the oxygen-free copper foil (3) is not limited.

5. The process method for preventing solder overflow during soldering of an AMB substrate according to claim 1, characterized in that: In step S4, the soft pad (4) is a high-temperature resistant soft material.

6. The process method for preventing solder overflow during soldering of an AMB substrate according to claim 5, characterized in that: The thickness of the high-temperature resistant soft material is not limited to a specific thickness value.

7. The process method for preventing solder overflow during soldering of an AMB substrate according to claim 5, characterized in that: The width of the high-temperature resistant soft material is not limited.

8. The process method for preventing solder overflow during soldering of an AMB substrate according to claim 2, characterized in that: The mesh count of the screen printing screen frame is 100-600 mesh, which is determined according to the solder type.

9. The process method for preventing solder overflow during soldering of an AMB substrate according to claim 1, characterized in that: In the step S1, the temperature for drying the AMB ceramic copper clad plate substrate is 150-600℃, and the duration for drying is not limited according to the solder type.

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