Metallization preparation method for side cavity wall of small-size multi-layer co-fired ceramic product

Abstract

The invention discloses a metallization preparation method for a side cavity wall of a small-size multi-layer co-fired ceramic product. The metallization preparation method comprises the following steps: reserving process edges around a plurality of single small-size multi-layer co-fired ceramic products, and arranging the single small-size multi-layer co-fired ceramic products on a green ceramic chip in an array; processing the green ceramic chip and the metal slurry by adopting a multi-layer co-fired ceramic product manufacturing process to obtain a full-page formed green ceramic body; processing a side cavity on the green ceramic body; two cavity opening tools are manufactured, a whole green ceramic body is fixed in the two cavity opening tools, the surfaces of the cavity opening tools are scraped through rubber scrapers, metal slurry is squeezed into side face cavities, redundant metal slurry is pumped away through a vacuum adsorption table, and the metal slurry is attached to the walls of the side face cavities; separating a single product to obtain an independent multilayer ceramic product green body; and sintering to obtain a multilayer ceramic product with metalized side cavity walls. According to the invention, the problems of deformation of a metallized cavity of a side cavity wall of a small-size multi-layer co-fired ceramic product, high operation difficulty and low production efficiency can be solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of co-fired ceramics, and particularly relates to a method for metallizing the side cavity wall of a small-sized multi-layer co-fired ceramic product. Background Art

[0002] Multi-layer co-fired ceramic products mainly include low-temperature co-fired ceramics (LTCC) and high-temperature co-fired ceramics (HTCC). The products have advantages such as corrosion resistance, high temperature resistance, low loss, high integration, and high reliability, and have been widely used in fields such as communication, aerospace, and automotive electronics. With the development of electronic technology, the application scope of multi-layer co-fired ceramic technology is becoming wider and wider, the demand is also increasing, the manufacturing requirements for multi-layer co-fired ceramic products are getting higher and higher, and the manufacturing cycle is getting shorter and shorter.

[0003] Most multi-layer co-fired ceramic products are three-dimensional circuit boards, electronic packaging housings, SIP modules, integrated modules, etc. For most products such as packaging housings and SIP modules, in order to improve the firmness of leads during subsequent assembly, it is necessary to semi-open a cavity on the side of the product and metallize the cavity wall. During subsequent soldering, the liquid solder flows along the external pins and the ceramic sidewall metal layer, thereby increasing the solder stacking area.

[0004] At present, there are two methods for metallizing the side cavity wall of multi-layer co-fired ceramic products. One method is to print the conductor first, then open the cavity, print the metal paste on the side cavity wall of each green ceramic sheet respectively, and then obtain the finished product through lamination, hot pressing, cutting, and co-firing. The problem with this method is that due to the shrinkage during the processing of the green ceramic sheet, there is a certain deviation in the cavity alignment between the upper and lower layers, and the cavity edge is prone to deformation after lamination. Another method is to open the cavity on the side after obtaining a single product through lamination, hot pressing, and cutting, and brush the metal paste to complete the side cavity metallization. This method is only suitable for multi-layer co-fired ceramic products with larger sizes. For small-sized products, it is difficult to operate with this method, and the production efficiency is low. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for metallizing the side cavity wall of a small-sized multi-layer co-fired ceramic product, solve the problems of cavity deformation, large operation difficulty, and low production efficiency in the metallization of the side cavity wall of small-sized multi-layer co-fired ceramic products, effectively improve the product yield and operation efficiency, and save economic costs.

[0006] To achieve the above purpose, one aspect of the present invention provides a method for metallizing the side cavity wall of a small-sized multi-layer co-fired ceramic product, including:

[0007] Step S1, arranging a plurality of single small-sized multi-layer co-fired ceramic products on a green ceramic sheet in an array after reserving a process margin around them;

[0008] Step S2: Process the green ceramic sheets and metal paste using the multi-layer co-fired ceramic product manufacturing process to obtain a green ceramic blank in one-piece form;

[0009] Step S3: On the obtained green ceramic blank, process side cavities at positions where sidewall metallization is required;

[0010] Step S4: Fabricate two cavity-opening toolings, where the positions and sizes of the cavities opened in the toolings are the same as those of the side cavities;

[0011] Step S5: Fix the one-piece green ceramic blank within the two cavity-opening toolings, scrape the surface of the cavity-opening toolings using a rubber squeegee to squeeze the metal paste into the interior of the side cavities, and use a vacuum adsorption table to suck away the excess metal paste, thereby completing the attachment of the metal paste to the side cavity walls;

[0012] Step S6: Separate individual products through thermal cutting, remove the excess process edges, and obtain independent green multi-layer ceramic products;

[0013] Step S7: Sinter the individual products to obtain multi-layer ceramic products with metallized side cavity walls.

[0014] Preferably, Step S2 includes:

[0015] Provide multi-layer green ceramic sheets, and process electrical vias on each layer of green ceramic sheets using a mechanical punching machine;

[0016] Use a printing press to fill the electrical vias on each layer of green ceramic sheets with metal paste, and perform drying after filling;

[0017] Use a screen printing press to print metal paste patterns on the surface of each layer of green ceramic sheets, and perform drying after printing;

[0018] Stack each layer of green ceramic sheets in sequence, and use an isostatic laminating press to laminate the stacked green ceramic sheets to obtain a green ceramic blank in one-piece form.

[0019] Preferably, the size of the green ceramic sheets is 4 inches to 8 inches, and the width of the process edges is 0.3 mm to 1 mm.

[0020] Preferably, in Step S3, alignment holes are also processed on the green ceramic blank. In Step S4, alignment holes are processed on the cavity-opening toolings, which are in the same positions as the alignment holes on the green ceramic blank. In Step S5, positioning pins are inserted into the alignment holes to fix the green ceramic blank and the cavity-opening toolings.

[0021] Preferably, the cavity-opening tooling is made of stainless steel material, and the thickness of the tooling is 0.05 mm to 0.2 mm.

[0022] Preferably, the Shore hardness of the rubber squeegee is 70 to 90, and the angle of the rubber squeegee is 30 degrees to 60 degrees.

[0023] Preferably, the metal paste is one of gold paste, silver paste, tungsten paste, gold-platinum-palladium paste, and palladium-silver paste, and the viscosity of the metal paste is 200 Pa·s to 300 Pa·s at 10 RPM.

[0024] Preferably, the pressure of the vacuum adsorption table is 18 KPa to 30 KPa, and the running time is 15 s to 30 s.

[0025] Preferably, the temperature of the thermal cutting is 50 °C to 80 °C, and the preheating time is 5 min.

[0026] According to the method for metallizing the side cavity wall of a small-size multi-layer co-fired ceramic product in the above aspect of the present invention, it can solve the problems of cavity deformation, large operation difficulty, and low production efficiency in the metallization of the side cavity wall of a small-size multi-layer co-fired ceramic product, effectively improve the product yield and operation efficiency, and save economic costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts:

[0028] Figure 1 It is a three-dimensional structure diagram of a single multi-layer co-fired ceramic product according to an embodiment of the present invention, where (a) represents a multi-layer co-fired ceramic product whose entire side cavity wall needs to be metallized, and (b) represents a multi-layer co-fired ceramic product whose partial side cavity wall needs to be metallized;

[0029] Figure 2 It is a plan view of a multi-layer co-fired ceramic product with multiple products in a panel design and processed together according to an embodiment of the present invention;

[0030] Figure 3 For Figure 2 a partial enlarged view of the layout distribution of a single product in

[0031] Figure 4 It is a process flow diagram of the manufacturing process of a multi-layer co-fired ceramic product according to an embodiment of the present invention;

[0032] Figure 5 It is a placement diagram of the tooling for metallizing the side cavity wall of a multi-layer co-fired ceramic product according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Apparently, the described embodiments are only a part rather than all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the scope of protection of the present invention.

[0034] An embodiment of the present invention provides a method for preparing side cavity wall metallization of a small-size multi-layer co-fired ceramic product, including steps S1 to S7.

[0035] In step S1, a plurality of single small-size multi-layer co-fired ceramic products (unit products) with the same outer dimensions are arranged in an array on a green ceramic sheet. The size of the green ceramic sheet can be flexibly selected according to the production line process. For example, the size of the green ceramic sheet is 4 inches to 8 inches. When arranging the panel, a narrow edge is reserved around the unit product as the process edge of the unit product, which is used to design the side cavity of the unit product as a closed cavity, facilitating subsequent side cavity wall metallization operations. The width of the process edge is 0.3 mm to 1 mm.

[0036] In step S2, according to the layout design, the green ceramic sheet and the metal paste are processed by using the multi-layer co-fired ceramic product manufacturing process, including processes such as drilling, hole filling, conductor printing, laminating and lamination, to obtain a green ceramic blank with a whole-panel shape.

[0037] In step S3, side cavities and alignment holes are processed on the green ceramic blank at the designed positions. Generally, it can be processed by mechanical or laser means. A mechanical drill bit or ultraviolet laser can be used. The cavity pattern can be appropriately enlarged towards the reserved process edge position to obtain a green ceramic blank with a through cavity.

[0038] In step S4, two cavity-opening toolings are prepared. The cavity-opening tooling can be made of stainless steel material, and the thickness of the tooling is 0.05 mm to 0.2 mm. The cavity-opening position and size of the tooling are the same as those of the side cavity punched on the green ceramic blank. Cavities and alignment holes are processed on the stainless steel cavity-opening tooling. The positions and sizes of the cavities and alignment holes are the same as those of the cavities and alignment holes on the whole-panel green ceramic blank that need side cavity wall metallization.

[0039] In step S5, the whole green ceramic blank is clamped between two cavity-opening toolings. Check that the cavity-opening positions of the toolings are consistent with the cavity positions of the green ceramic blank. Insert positioning pins into the alignment holes to fix the green ceramic blank and the toolings. Place the green ceramic blank and the toolings together on a flat operating table. Apply metal paste on a rubber squeegee and scrape it forcefully across the surface of the tooling to squeeze the metal paste into the cavity interior. The Shore hardness of the rubber squeegee is 70 - 90, and the angle of the rubber squeegee is 30 degrees - 60 degrees. Use a vacuum adsorption table to suck away the excess paste, and then perform drying to cure the metal paste, completing the attachment of the metal paste on the side cavity walls. The pressure of the vacuum adsorption table is 18 KPa - 30 KPa, and the running time is 15 s - 30 s. The metal paste can be one of gold paste, silver paste, tungsten paste, gold-platinum-palladium paste, and palladium-silver paste. The viscosity of the metal paste is 200 Pa·s - 300 Pa·s at 10 RPM.

[0040] In step S6, through thermal cutting processing, separate individual products, remove the excess process edges, and obtain independent green blanks of multi-layer co-fired ceramic products. The thermal cutting temperature is 50°C - 80°C, and the preheating time is 5 min.

[0041] In step S7, obtain multi-layer co-fired ceramic products with metallized side cavity walls through sintering.

[0042] The following takes the production of a product with all side cavity walls of a six-layer HTCC multi-layer ceramic needing to be metallized as an example to further illustrate in detail each step of the method of the embodiment of the present invention.

[0043] In step S1, as Figure 1 and Figure 2 shown, arrange and design the processing of multiple unit products 1 in an array layout. When arranging the panel layout, reserve the process edges 5 of the unit products for designing the cavity-opening pattern 3 of the closed cavity for the parts 2 that need to be metallized on the side cavity walls, facilitating subsequent side cavity wall metallization operations, as Figure 2 and Figure 3 shown. The width of the process edge 5 of the unit product is 0.8 mm, the processed green ceramic chip size is 4 inches, and six layers need to be metallized on the side cavity walls.

[0044] In step S2, according to the layout design, a multi-layer co-fired ceramic product manufacturing process is used to process green ceramic wafers and metal pastes. Provide green ceramic wafers for the first to sixth layers, and use a mechanical punching machine to process electrical vias and alignment holes on each layer of green ceramic wafer; use a printing machine to fill the electrical vias on each layer of green ceramic wafer with metal paste, and the drying temperature after filling is 50°C and the drying time is 20 min; then use a screen printing machine to print metal paste patterns on the surface of each layer of green ceramic wafer, and the drying temperature after printing is 50°C and the drying time is 20 min; then stack each layer of green ceramic wafer in the order required by electricity, and use an isostatic laminator to laminate the stacked green ceramic wafers. The water temperature is 55°C, the pressure is 10 Mpa, and the pressure holding time is 10 min to obtain a green ceramic blank 6 with a whole-board shape. The process is as Figure 4 shown.

[0045] In step S3, cavities are opened on the green ceramic blank according to the designed position pattern. Use an ultraviolet laser device to process the designed cavity pattern 3 and alignment holes 4 on the whole-board-shaped green ceramic blank 6. The laser parameters are a power of 5 W, a pulse frequency of 50 Hz, and a laser cutting speed of 800 mm / s. The processing method is selected as inward processing, and the path width is set to 30 um to obtain a green ceramic blank with a through cavity.

[0046] In step S4, prepare two cavity-opening toolings, select stainless steel material with a thickness of 0.15 mm, and process cavity pattern 3 and alignment holes 4 on the stainless steel sheet. The positions of the cavity pattern and alignment holes are the same as those of the side cavity wall metallized cavity and alignment holes of the whole-board green ceramic blank.

[0047] In step S5, as Figure 5 shown, clamp the whole-board green ceramic blank 6 between two cavity-opening toolings 7, check that the cavity-opening position of the tooling is the same as the cavity position of the green ceramic blank, insert a positioning pin 8 into the alignment hole 4 to fix the green ceramic blank and the tooling. Place the green ceramic blank and the tooling together on a flat operating table, apply metal paste on a rubber squeegee, and scrape the surface of the tooling forcefully with the rubber squeegee to squeeze the metal paste into the cavity. The Shore hardness of the rubber squeegee is 70, and the angle of the rubber squeegee is 45 degrees. Then place the green ceramic blank and the tooling together on a table with a vacuum source, turn on the vacuum, set the pressure of the vacuum adsorption table to 22 KPa, and the running time to 20 s to create a pressure difference up and down in the cavity, so that the metal paste is subjected to a downward suction force, flows through the side cavity wall, and the excess paste is pumped away. Dry and cure the side wall metal paste in an oven. The oven temperature is 50°C and the drying time is 15 min.

[0048] If a product with a metallized side cavity wall part needs to be made, such as Figure 1As shown in (b) of , the green ceramic wafers that require the side cavity wall metallization layer and those that do not require the metal layer are stacked and laminated in sequence to obtain the green ceramic blanks formed into a whole plate. After the green ceramic blanks that require side cavity wall metallization are processed according to steps S3, S4, and S5, they are bonded together with the green ceramic wafers that do not require the metallization layer using an organic solvent adhesive in sequence to obtain the whole plate green ceramic blank with the side cavity wall metallized integrally.

[0049] In step S6, the whole plate green ceramic blank is processed by thermal cutting using an automatic cutting machine to separate individual products and remove the excess process edges, obtaining the green blanks of independent multi-layer co-fired ceramic products. The thermal cutting temperature is 55 °C and the preheating time is 5 min.

[0050] In step S7, the unit products are placed in an HTCC sintering furnace for debinding and sintering. The sintering temperature is 1575 °C to obtain the multi-layer co-fired ceramic products with the side cavity wall metallized.

[0051] The present invention can be widely applied to the research and development and mass production of LTCC and HTCC multi-layer co-fired ceramic products. It has strong operability, can flexibly and efficiently prepare the metallization of the side cavity wall of multi-layer co-fired ceramic products, is applicable to a variety of small-sized multi-layer co-fired ceramic products, is not limited by the product shape, and both the full-sidewall metallization and semi-sidewall metallization of the cavity can use this method. The present invention can realize the rapid and efficient batch processing of the metallization of the side cavity wall of multi-layer co-fired ceramic products, solve the problem of cavity deformation after lamination when metallizing the side cavity wall before lamination, and at the same time solve the problem of low efficiency of metallizing the side cavity wall of individual products after lamination and cutting, effectively improving the product yield and operation efficiency and saving economic costs.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] (1) By adopting the present invention, both low-temperature co-fired ceramic (LTCC) and high-temperature co-fired ceramic (HTCC) materials can be applied, and it is not limited by the product material, size, and shape. It is a general method for fabricating the metallization of the side cavity wall of multi-layer co-fired ceramic products;

[0054] (2) The present invention reduces the operation difficulty, reduces the operation steps, has strong operability, is simple and easy to implement, and is especially suitable for mass production;

[0055] (3) The tooling cost used in the present invention is low, and the tooling can be reused.

[0056] Only certain exemplary embodiments of the present invention have been described above by way of illustration. Without doubt, for those of ordinary skill in the art, the described embodiments can be modified in various different ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for preparing metallization of the side cavity wall of a small-sized multi-layer co-fired ceramic product, characterized in that, Including: Step S1: After leaving a processing margin around multiple single small-sized multi-layer co-fired ceramic products, arrange them in an array on a green ceramic sheet. Step S2: Use the manufacturing process of multi-layer co-fired ceramic products to process the green ceramic sheet and metal paste to obtain a green ceramic blank formed as a whole plate. Step S3: On the obtained green ceramic blank, process side cavities at positions where sidewall metallization is required. Step S4: Manufacture two cavity-opening toolings, where the positions and sizes of the cavities opened in the toolings are the same as those of the side cavities. Step S5: Fix the whole-plate green ceramic blank in the two cavity-opening toolings, scrape across the surface of the cavity-opening toolings with a rubber squeegee to squeeze the metal paste into the interior of the side cavities, and use a vacuum adsorption table to suck away the excess metal paste to complete the attachment of the metal paste to the side cavity walls. Step S6: Separate the single products by thermal cutting, remove the excess processing margins to obtain independent green multi-layer ceramic products. Step S7: Sinter the single products to obtain multi-layer ceramic products with metallized side cavity walls.

2. The method according to claim 1, wherein Step S2 includes: Provide multi-layer green ceramic sheets, and use a mechanical punching machine to process electrical vias on each layer of green ceramic sheet. Use a printing machine to fill the electrical vias on each layer of green ceramic sheet with metal paste, and dry it after filling. Use a screen printing machine to print metal paste patterns on the surface of each layer of green ceramic sheet, and dry it after printing. Stack each layer of green ceramic sheet in sequence, and use an isostatic laminator to laminate the stacked green ceramic sheets to obtain a green ceramic blank formed as a whole plate.

3. The method according to claim 1 or 2, characterized in that, The size of the green ceramic sheet is 4 inches to 8 inches, and the width of the processing margin is 0.3 mm to 1 mm.

4. The method according to claim 1 or 2, characterized in that, In Step S3, alignment holes are also processed on the green ceramic blank. In Step S4, alignment holes are processed on the cavity-opening toolings, which are in the same positions as the alignment holes on the green ceramic blank. In Step S5, positioning pins are inserted into the alignment holes to fix the green ceramic blank and the cavity-opening toolings.

5. The method according to claim 1 or 2, characterized in that, The cavity-opening tooling is made of stainless steel material, and the thickness of the tooling is 0.05 mm to 0.2 mm.

6. The method according to claim 1 or 2, characterized in that, The Shore hardness of the rubber squeegee is 70 to 90, and the angle of the rubber squeegee is 30 degrees to 60 degrees.

7. The method according to claim 1 or 2, characterized in that, The metal paste is one of gold paste, silver paste, tungsten paste, gold-platinum-palladium paste, and palladium-silver paste. The viscosity of the metal paste at 10 RPM is 200 Pa·s to 300 Pa·s.

8. The method according to claim 1 or 2, characterized in that The pressure of the vacuum adsorption table is 18 KPa to 30 KPa, and the running time is 15 s to 30 s.

9. The method according to claim 1 or 2, characterized in that, The temperature of the thermal cutting is 50°C to 80°C, and the preheating time is 5 min.

Images