Solder patterning preparation process suitable for ceramic copper-clad substrate

Abstract

The invention discloses a solder patterning preparation process suitable for a ceramic copper-clad substrate, which comprises the following specific steps of: S1, preparing a ceramic substrate, molding slurry into the ceramic substrate, and drying the ceramic substrate; s2, circuit printing is carried out, only a circuit pattern is subjected to silk-screen printing, and no solder is subjected to silk-screen printing in a non-pattern area; s3, brazing treatment is conducted, and a reaction layer capable of being wetted by the liquid brazing filler metal is generated; s4, film pasting exposure treatment: enabling ultraviolet light to penetrate through the mask plate to irradiate the photoresist surface of the product to be exposed, enabling the ultraviolet light to penetrate through the transparent part of the mask plate to cause photoresist reaction, and projecting a pattern on the mask plate onto the photoresist coating on the mother card; and S5, performing copper etching treatment, forming an etching pattern, controlling the etching speed, and forming a copper-solder-ceramic step. According to the invention, the use of solder is saved, the production process is simplified, the quality and performance of a product are improved, the pollution of a chemical solution to the environment is avoided, and the production cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of copper-clad ceramic substrate technology, and specifically relates to a solder patterning process suitable for copper-clad ceramic substrates. Background Technology

[0002] Etching is a technique that removes part of the material using chemical reactions or physical impacts. Etching technology can be divided into two categories: wet etching and dry etching. Etching was originally used to manufacture printing plates such as copper plates and zinc plates. With continuous improvement and the development of process equipment, it can be used to process precision etched products of electronic thin-film parts in the aerospace, machinery and chemical industries. Especially in semiconductor manufacturing, etching is an indispensable technology.

[0003] In existing technologies, chemical etching is commonly used to remove solder from non-circuit areas. This method primarily uses a specific chemical solution to dissolve the unwanted solder, thereby forming the desired circuit pattern. Etching solder from non-circuit areas is a complex and time-consuming operation, requiring precise control of etching depth and accuracy to avoid damage to the circuit areas. The chemical solutions used in chemical etching may pollute the environment, and the etching rate is difficult to control, easily leading to uneven etching and affecting product quality. Additional cleaning and drying steps are required, increasing the complexity and cost of the production process.

[0004] Existing technologies also include laser etching, which uses a high-energy laser beam to irradiate and burn away the solder in non-circuit areas. Laser etching equipment is expensive, and laser irradiation may damage the ceramic substrate, affecting its performance. Additional cleaning and drying steps are required, which increases the complexity and cost of the production process. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to overcome the shortcomings of the prior art and provide a solder patterning process suitable for ceramic copper-clad substrates.

[0006] A solder patterning process suitable for copper-clad ceramic substrates includes the following steps: S1. A ceramic substrate is prepared by selecting high-purity ceramic powder, organic binder, and solvent as raw materials. The raw materials are screened and ground to ensure the uniformity and fineness of the powder. The high-purity ceramic powder, organic binder, and solvent are mixed in a certain proportion and stirred and homogenized to obtain a uniform slurry. The well-mixed slurry is then degassed. The slurry is molded into a ceramic substrate and then dried. S2. For circuit printing, first take the active metal solder out of the sub-zero temperature environment and leave it at room temperature for a period of time to ensure adhesion and printing performance; centrifuge and stir the thawed active metal solder to remove air bubbles in the solder and ensure that the solvent and activator are fully mixed. When screen printing, directly screen print the solder according to the circuit pattern or use graphic solder pads. Only screen print the circuit pattern and do not screen print solder in non-graphic areas. S3. Perform brazing treatment, using active metal solder to combine copper and ceramic substrates. The solder reacts chemically with the ceramic to generate a reaction layer that can be wetted by liquid solder. S4. Film exposure process: Ultraviolet light penetrates the mask and shines on the photoresist surface of the product to be exposed. The ultraviolet light penetrates the transparent part of the mask, causing the photoresist to react and project the pattern on the mask onto the photoresist coating on the master card. S5. Copper etching process: After treatment with developer, the copper parts on the mother card surface that are not covered by photoresist are etched away, leaving the parts protected by photoresist to form an etching pattern. The etching speed is controlled to form copper-solder-ceramic steps.

[0007] A further improvement of the present invention is that, in step S1, vacuum degassing or centrifugal degassing is used during the degassing process.

[0008] A further improvement of the present invention is that, in step S1, the slurry forming method includes compression molding, injection molding, and extrusion molding.

[0009] A further improvement of the present invention is that, during the compression molding process, the degassed and filtered slurry is placed into the mold, and a constant pressure is applied to fully fill the mold cavity and form the desired shape.

[0010] A further improvement of the present invention is that, in step S5, the etching depth is controlled by the concentration of the acid solution and the soaking time of the mother card.

[0011] A further improvement of the present invention is that, in step S5, the temperature during copper etching is 35-40°C and the etching time is 40 minutes.

[0012] A further improvement of the present invention is that vacuum degassing is used to remove air bubbles and solvents from the slurry, improve the fluidity of the slurry and the density of the ceramic substrate, and the slurry after vacuum degassing is filtered to remove impurities and particles from the slurry.

[0013] A further improvement of the present invention is that, in step S1, the drying process includes low-temperature drying and high-temperature sintering. Low-temperature drying is used to remove residual solvents and moisture from the green body, and high-temperature sintering causes the ceramic powder particles to bond together to form a dense ceramic matrix.

[0014] Compared with the prior art, the solder patterning process for ceramic copper-clad substrates provided by the present invention achieves at least the following beneficial effects: This invention allows for direct solder screen printing based on the circuit pattern or the use of patterned solder pads during screen printing, eliminating the solder etching process in non-circuit areas, greatly simplifying the production process and improving production efficiency. Since only the circuit pattern is silkscreened, the non-pattern areas do not need to be silkscreened with solder, which can save solder usage; By eliminating the solder etching process, the potential damage to the ceramic substrate caused by chemical solutions or laser irradiation is avoided, thereby improving the quality and performance of the product. By simplifying the production process and reducing cleaning and drying steps, production costs are reduced. At the same time, the elimination of the need for chemical solutions or laser equipment also reduces environmental impact and equipment investment, thus lowering production costs. Since no chemical solutions are needed, the environmental pollution caused by chemical solutions is avoided; This invention forms a copper-solder-ceramic step, which can reduce the thermal stress caused by the difference in the coefficient of thermal expansion (CTE) between copper and ceramic, thereby improving product reliability. Attached Figure Description

[0015] Figure 1 This is a flowchart of the present invention; Figure 2 To form a cross-sectional view of the copper-solder-ceramic step; Detailed Implementation

[0016] Various exemplary embodiments of the present invention will now be described in detail. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0017] Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0018] See the attached instruction manual. Figure 1-2 A solder patterning process suitable for ceramic copper-clad substrates, the specific steps of which include: S1. A ceramic substrate is prepared by selecting high-purity ceramic powder, organic binder, and solvent as raw materials. The raw materials are screened and ground to ensure the uniformity and fineness of the powder. The high-purity ceramic powder, organic binder, and solvent are mixed in a certain proportion and stirred and homogenized to obtain a uniform slurry. The well-mixed slurry is then degassed. The slurry is molded into a ceramic substrate and then dried. S2. For circuit printing, first take the active metal solder out of the sub-zero temperature environment and leave it at room temperature for a period of time to ensure adhesion and printing performance; centrifuge and stir the thawed active metal solder to remove air bubbles in the solder and ensure that the solvent and activator are fully mixed. When screen printing, directly screen print the solder according to the circuit pattern or use graphic solder pads. Only screen print the circuit pattern and do not screen print solder in non-graphic areas. S3. Perform brazing treatment, using active metal solder to combine copper and ceramic substrates. The solder reacts chemically with the ceramic to generate a reaction layer that can be wetted by liquid solder. S4. Film exposure process: Ultraviolet light penetrates the mask and shines on the photoresist surface of the product to be exposed. The ultraviolet light penetrates the transparent part of the mask, causing the photoresist to react and project the pattern on the mask onto the photoresist coating on the master card. S5. Copper etching process: After treatment with developer, the copper parts on the mother card surface that are not covered by photoresist are etched away, leaving the parts protected by photoresist to form an etching pattern. The etching speed is controlled to form copper-solder-ceramic steps.

[0019] A further improvement of the present invention is that, in step S1, vacuum degassing or centrifugal degassing is used during the degassing process.

[0020] A further improvement of the present invention is that, in step S1, the slurry forming method includes compression molding, injection molding, and extrusion molding.

[0021] A further improvement of the present invention is that, during the compression molding process, the degassed and filtered slurry is placed into the mold, and a constant pressure is applied to fully fill the mold cavity and form the desired shape.

[0022] A further improvement of the present invention is that, in step S5, the etching depth is controlled by the concentration of the acid solution and the soaking time of the mother card.

[0023] A further improvement of the present invention is that, in step S5, the temperature during copper etching is 35-40°C and the etching time is 40 min.

[0024] A further improvement of the present invention is that vacuum degassing is used to remove air bubbles and solvents from the slurry, improve the fluidity of the slurry and the density of the ceramic substrate, and the slurry after vacuum degassing is filtered to remove impurities and particles from the slurry.

[0025] A further improvement of the present invention is that, in step S1, the drying process includes low-temperature drying and high-temperature sintering. Low-temperature drying is used to remove residual solvents and moisture from the green body, and high-temperature sintering causes the ceramic powder particles to bond together to form a dense ceramic matrix.

[0026] In summary, the present invention provides a solder patterning process suitable for copper-clad ceramic substrates. During screen printing, solder is directly screen-printed according to the circuit pattern or patterned solder pads are used, eliminating the solder etching process in non-circuit areas, greatly simplifying the production process and improving production efficiency. Since only the circuit pattern is screen-printed, solder is not required in non-pattern areas, saving solder usage. Furthermore, eliminating the solder etching process avoids potential damage to the ceramic substrate from chemical solutions or laser irradiation, thereby improving product quality and performance. By simplifying the production process and reducing cleaning and drying steps, production costs are reduced. Furthermore, the elimination of chemical solutions or laser equipment minimizes environmental impact and equipment investment, further lowering production costs. The absence of chemical solutions also avoids environmental pollution. The invention forms a copper-solder-ceramic step, reducing thermal stress between copper and ceramic due to their different coefficients of thermal expansion (CTE), thus improving product reliability.

[0027] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A solder patterning process suitable for copper-clad ceramic substrates, characterized in that, The specific steps include: S1. A ceramic substrate is prepared by selecting high-purity ceramic powder, organic binder, and solvent as raw materials. The raw materials are screened and ground to ensure the uniformity and fineness of the powder. The high-purity ceramic powder, organic binder, and solvent are mixed in a certain proportion and stirred and homogenized to obtain a uniform slurry. The well-mixed slurry is then degassed. The slurry is molded into a ceramic substrate and then dried. S2. For circuit printing, first take the active metal solder out of the sub-zero temperature environment and leave it at room temperature for a period of time to ensure adhesion and printing performance; centrifuge and stir the thawed active metal solder to remove air bubbles in the solder and ensure that the solvent and activator are fully mixed. When screen printing, directly screen print the solder according to the circuit pattern or use graphic solder pads. Only screen print the circuit pattern and do not screen print solder in non-graphic areas. S3. Perform brazing treatment, using active metal solder to combine copper and ceramic substrates. The solder reacts chemically with the ceramic to generate a reaction layer that can be wetted by liquid solder. S4. Film exposure process: Ultraviolet light penetrates the mask and shines on the photoresist surface of the product to be exposed. The ultraviolet light penetrates the transparent part of the mask, causing the photoresist to react and project the pattern on the mask onto the photoresist coating on the master card. S5. Copper etching process: After treatment with developer, the copper parts on the mother card surface that are not covered by photoresist are etched away, leaving the parts protected by photoresist to form an etching pattern. The etching speed is controlled to form copper-solder-ceramic steps.

2. The solder patterning process for ceramic copper-clad substrates according to claim 1, characterized in that, In step S1, vacuum degassing or centrifugal degassing is used during the degassing process.

3. The solder patterning process for ceramic copper-clad substrates according to claim 1, characterized in that, In step S1, the slurry forming methods include compression molding, injection molding, and extrusion molding.

4. The solder patterning process for ceramic copper-clad substrates according to claim 3, characterized in that, In the compression molding process, the degassed and filtered slurry is placed into the mold, and constant pressure is applied to fully fill the mold cavity and form the desired shape.

5. The solder patterning process for ceramic copper-clad substrates according to claim 1, characterized in that, In step S5, the etching depth is controlled by the concentration of the acid solution and the soaking time of the mother card.

6. The solder patterning process for ceramic copper-clad substrates according to claim 1, characterized in that, In step S5, the temperature for copper etching is 35-40°C, and the etching time is 40 minutes.

7. The solder patterning process for ceramic copper-clad substrates according to claim 2, characterized in that, Vacuum degassing is used to remove air bubbles and solvents from the slurry, improve the slurry's fluidity and the density of the ceramic substrate. The slurry after vacuum degassing is then filtered to remove impurities and particles.

8. The solder patterning process for ceramic copper-clad substrates according to claim 1, characterized in that, In step S1, the drying process includes low-temperature drying and high-temperature sintering. Low-temperature drying is used to remove residual solvents and moisture from the green body, and high-temperature sintering causes the ceramic powder particles to bond together, forming a dense ceramic matrix.

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