A method for manufacturing a multilayer ceramic circuit board having a double-sided cavity structure

Abstract

The application relates to a preparation method of a double-face cavity structure multilayer ceramic circuit board, and belongs to the field of electronic components. The method comprises the following steps: perforating, filling, printing and drying a green ceramic strip, and then opening a cavity; printing an adhesive layer on the surface of a green ceramic sheet; aligning and stacking the green ceramic strips printed with the adhesive layer, and pressing the green ceramic strips into a green ceramic body; wrapping thin soft silica gel pads with preservative films, placing the soft silica gel pads on a flat stainless steel plate, placing the stacked green ceramic body on the soft silica gel pads, placing another soft silica gel pad wrapped with a preservative film on the green ceramic body, and then performing small pressure isostatic pressing after vacuum packaging; hot cutting the green ceramic body into single double-face cavity structure multilayer ceramic circuit board green bodies; and sintering to form a double-face cavity structure multilayer ceramic circuit board. The method solves the problems in the prior art, such as the use of rigid pads or soft and hard convex films to protect the cavity, and the need for large pressing pressure, which leads to ceramic deformation and even cracks. The method is widely applied to the preparation of various complex cavity multilayer circuit boards.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of electronic components, further to the field of multilayer ceramic circuit board, in particular, to a preparation method of double-sided cavity structure multilayer ceramic circuit board. BACKGROUND

[0002] Multilayer co-fired ceramic has been widely used in the fields of electronic industry, aerospace, etc. due to its high chemical structure strength, good chemical stability, excellent electrical and thermal performance, high wiring density, flexible shape design, etc. In recent years, with the development of microelectronic technology, communication technology, etc. towards high integration, high density, high reliability and miniaturization, more active and passive electronic components need to be integrated on multilayer co-fired ceramic circuit board to realize more functions. For example, highly integrated SiP products and radio frequency / microwave devices require the interconnection path between chips and components to be as short as possible, while the conventional structure can only assemble chips on the surface of two-dimensional planar substrate, resulting in that the size of the circuit board cannot be reduced, the interconnection leads cannot be shortened, and in addition, parasitic interference occurs between signals, thereby affecting the performance of the circuit. At the same time, due to the requirements of common ground / common plane, impedance matching, electromagnetic shielding, etc. for high-frequency signal transmission, opening a complex cavity on the ceramic substrate to realize the reasonable assembly of functional chips is the best solution at present.

[0003] Opening cavities on the front and back surfaces of a multilayer ceramic circuit board is called double-sided cavity structure. With the rapid development of electronic information technology, circuit boards with double-sided cavity structure are becoming more and more important in terms of miniaturization and high integration. Since multilayer co-fired ceramic is prepared by punching, filling, printing electrodes and opening cavities on a single green ceramic tape, and then stacking, isostatic pressing, cutting and sintering, etc. to obtain each single green ceramic tape, it is very difficult to isostatic press the circuit board with double-sided cavity structure.

[0004] At present, the preparation method of the circuit board with double-sided cavity structure usually adopts the way of filling rigid plugs or special soft and hard convex membranes or carbon paste, carbon tape and carbon block in the cavity for protection, and at the same time, a larger pressing force is needed for pressing, thereby increasing the risk of ceramic deformation or even cracks caused by the deformation of rigid plugs or special soft and hard convex membranes or carbon paste, carbon tape and carbon block during the pressing process of the ceramic green body.

[0005] Therefore, the present application is proposed. SUMMARY

[0006] The technical problem to be solved by the present application is to solve the problem of ceramic deformation or even cracks caused by the use of rigid pads or special soft and hard convex membranes to protect the cavity and the use of a larger pressing force for pressing in the preparation method of the existing double-sided cavity structure circuit board.

[0007] The inventive concept of the present application is that a thin adhesive is printed on the surface of the open-cavity green ceramic sheet before lamination, and then the lamination is performed on a high-precision laminator, and then the laminated bar block is wrapped with a thin soft silica gel pad, one side is placed on a steel plate, and the vacuum bagging is performed under a pressure of 3.5 MPa to 6.5 MPa to obtain the multi-layer ceramic circuit board with a double-sided cavity structure. The adhesive greatly increases the adhesion of the green ceramic tape between the layers under a lower pressing force, and the soft silica gel pad greatly improves the buffering capacity of the ceramic green body and the cavity between the silica gel pads during the pressing process, thereby greatly reducing the stress on the ceramic green body and the cavity during the pressing process using rigid pads or special soft and hard convex films to protect the cavity and high pressure pressing, thereby solving the problems of deformation, cracking and the like of the multi-layer ceramic circuit board with a double-sided cavity structure during the preparation process.

[0008] Therefore, the present application provides a preparation method of a multi-layer ceramic circuit board with a double-sided cavity structure, as shown in Fig. 1-2 The method comprises the following steps:

[0009] 1. The green ceramic tape is perforated, filled, printed with a conductor functional layer, dried, and then opened;

[0010] 2. A thin adhesive is printed on the surface of the open-cavity green ceramic sheet, and is naturally dried for 5 to 10 minutes;

[0011] 3. The dried green ceramic tape printed with the adhesive is high-precision aligned and laminated layer by layer according to the processing design drawing, and after the lamination is completed, the laminated whole bar block is pressed on the laminator for a certain period of time and then taken out;

[0012] 4. The thin soft silica gel pad is wrapped with a preservative film and placed on a flat stainless steel plate, and then the laminated ceramic green body is placed on the soft silica gel, and another soft silica gel wrapped with a preservative film is placed on the ceramic green body, and then the vacuum packaging is performed and isostatic pressing is performed.

[0013] 5. The pressed bar block is taken out, and the product is hot cut according to the designed cutting line to obtain the green body of the multi-layer ceramic circuit board with a double-sided cavity structure, and after sintering, the multi-layer ceramic circuit board with a double-sided cavity structure is obtained.

[0014] The green ceramic tape is an LTCC or HTCC green ceramic tape with a thickness of 120 to 130 microns and a size of 203 mm x 203 mm;

[0015] The adhesive is one or more of acrylic resin, LS glue, polyvinyl alcohol (PVA) and polyvinyl butyral (PVB) mixed, 30% to 50% alcohol is added as a diluent, and planetary ball milling is performed for 2 hours at a rotation speed of 200 r / min to obtain the adhesive.

[0016] The thickness of the adhesive is 2-5 microns;

[0017] The pressure of the pressing is 3-5 MPa, the time is 10-20 seconds, and the temperature is 30-50 degrees Celsius;

[0018] The preservative film is an oily preservative film, and the oily surface contacts the ceramic during pressing;

[0019] The thickness of the thin and soft silica gel is 0.5-5 mm, and the hardness is 0-10 degrees. The thickness is determined according to the depth of the cavity, and is selected according to the silica gel pad thickness: cavity depth = 1.5:1;

[0020] The pressure of the isostatic pressing is 3.5-6.5 MPa, the time is 10-30 minutes, and the water temperature is 60-75 degrees Celsius.

[0021] Compared with the prior art, the present application has the following advantages:

[0022] (1) Instead of filling rigid pads or using specific soft and hard convex films, carbon paste, carbon tape or carbon blocks in the two-cavity structure circuit board to protect, and using larger pressure (20-60 MPa) to press, the risk of ceramic deformation or even cracking caused by the deformation of rigid pads, specific soft and hard convex films, carbon paste, carbon tape or carbon blocks during pressing is increased.

[0023] (2) A thin adhesive layer is printed on the surface of the ceramic tape, and then a double-sided soft and thin silica gel pad is used to protect the ceramic tape after pressing under a large pressure. After isostatic pressing under a small pressure (≤6.5 MPa), the double-cavity structure multilayer ceramic circuit board is obtained. The small pressure and the protection of the silica gel pad can prevent the cavity from deforming and cracking during pressing, and the cross-sectional structure of the green body after pressing is observed. The layers are well combined and there is no delamination. It is suitable for preparing various complex cavity multilayer circuit boards.

[0024] It can be widely used in the preparation of various complex cavity multilayer circuit boards. BRIEF DESCRIPTION OF DRAWINGS

[0025] Fig. 1 It is a flow chart for preparing a double-cavity structure multilayer ceramic circuit board.

[0026] Fig. 2 It is an isostatic pressure encapsulation diagram of a double-cavity structure multilayer ceramic circuit board.

[0027] Fig. 3 It is an effect diagram of a double-cavity structure multilayer ceramic circuit board.

[0028] In the figure: 1 is the packaging bag; 2 is a stainless steel plate; 3 is a soft thin silica gel pad; 4 is an oily preservative film; 5 is a double cavity structure multilayer ceramic circuit board. DETAILED DESCRIPTION

[0029] As shown in the embodiment of the method for preparing the double cavity structure multilayer ceramic circuit board, the embodiment is as follows: Fig. 1-2

[0030] Embodiment 1:

[0031] 1. Green ceramic tape preparation: After punching, hole filling, conductor functional layer line printing, drying and cavity opening of the LTCC or HTCC green ceramic tape, the green ceramic tape is obtained.

[0032] 2. Adhesive preparation: uniformly stir acrylic resin and LS adhesive according to a mass ratio of 2:1, then add 30% to 50% alcohol as a diluent, and obtain adhesive A by planetary ball milling for 2h at a rotation speed of 200r / min.

[0033] 3. Green ceramic tape adhesive printing adhesive preparation: print a thin layer of adhesive A on the surface of the green ceramic piece with an opened cavity by silk screen printing, control the printing thickness to be 2μm to 5μm, and naturally air dry after placing for 5min.

[0034] 4. Lamination: laminate the dried green ceramic tape printed with adhesive A according to the high-precision layer-by-layer alignment of the processing design drawing, a certain pressure is required for each lamination for 5s to 10s, the pressure is controlled to be 1Mpa to 2Mpa, after lamination of all single-layer green ceramic tapes is completed, the whole is taken out after being pressed for 10s at a pressure of 5MPa on the laminator, and the temperature of the pressure head is set to be 30℃ during pressing.

[0035] 5. Vacuum packaging and isostatic pressing: wrap the thin soft silica gel pad with a thickness of 3mm with a preservative film, place it on a flat stainless steel plate, and the oily surface contacts the ceramic green body. Place the laminated ceramic green body on the soft silica gel, and place another thin soft silica gel with a thickness of 3mm wrapped with a preservative film on the ceramic green body, and the oily surface contacts the ceramic green body. Place the protected bar and the steel plate together in the packaging belt for vacuum packaging (packaging conditions: vacuum pressure: -0.1MPa, packaging time: 60s), and press the vacuum packaged bar in an isostatic pressing machine (pressing conditions: water temperature: 65-75℃, pressure: 3.5MPa-6.5MPa, pressing time: 10min-30min) to obtain a double cavity structure multilayer ceramic circuit board multilayer ceramic bar.

[0036] 6. Hot cutting: take out the pressed bar, and cut the product according to the designed cutting line to obtain the double cavity structure multilayer ceramic circuit board green body.

[0037] ​7. Sintering: sinter the green multilayer ceramic circuit board with double cavity structure according to the designed sintering curve to obtain the final multilayer ceramic circuit board with double cavity structure.

[0038] 8. Appearance inspection: observe the sintered multilayer ceramic circuit board with double cavity structure under a 100 times microscope to check whether the ceramic section has delamination or cracking.

[0039] Embodiment 2:

[0040] 1. Green ceramic tape preparation: punch, fill holes, print conductor functional layer, dry and open cavities on the LTCC or HTCC green ceramic tape;

[0041] 2. Adhesive preparation: uniformly stir acrylic resin and polyvinyl alcohol (PVA) according to a mass ratio of 2:1, then add 30% to 50% alcohol as a diluent, and use a planetary ball mill at 200 r / min for 2 h to obtain adhesive B;

[0042] 3. Green ceramic tape adhesive printing: print a thin layer of adhesive B on the surface of the green ceramic sheet with opened cavities using silk screen printing, control the printing thickness to be 2 μm to 5 μm, and naturally dry after 5 min;

[0043] 4. Lamination: laminate the dried green ceramic tape printed with adhesive B according to the processing design drawing with high-precision layer-by-layer alignment, and a certain pressure is required for 5 s to 10 s each time, with the pressure controlled at 1 MPa to 2 MPa. After all the single-layer green ceramic tapes are laminated, the whole is taken out after being pressed for 10 s at 5 MPa on the laminator, and the temperature of the pressing head is set to 30°C during pressing;

[0044] 5. Vacuum packaging and isostatic pressing: wrap a 3 mm thick thin soft silica gel pad with a preservative film, place it on a flat stainless steel plate with the oily surface upward to contact the ceramic green body. Place the laminated ceramic green body on the soft silica gel, and then place another 3 mm thick thin soft silica gel wrapped with a preservative film on the ceramic green body with the oily surface contacting the ceramic green body. Place the protected bar and steel plate together in a packaging belt for vacuum packaging (packaging conditions: vacuum pressure: -0.1 MPa, packaging time: 60 s), and then press the vacuum packaged bar in an isostatic pressing machine (pressing conditions: water temperature: 65 to 75°C, pressure: 3.5 MPa to 6.5 MPa, pressing time: 10 min to 30 min) to obtain a multilayer ceramic bar with double cavity structure multilayer ceramic circuit board;

[0045] 6. Hot cutting: take out the pressed bar and cut it according to the designed cutting line to obtain the green multilayer ceramic circuit board with double cavity structure;

[0046] 7. Sintering: sinter the green multilayer ceramic circuit board with double cavity structure according to the designed sintering curve to obtain the final multilayer ceramic circuit board with double cavity structure.

[0047] 8. Appearance inspection: observe the sintered multilayer ceramic circuit board with double cavity structure under a 100 times microscope to check whether the ceramic section has delamination or cracking.

[0048] Embodiment 3:

[0049] 1. Green ceramic tape preparation: punch, fill holes, print conductor functional layer, dry and open cavities on the LTCC or HTCC green ceramic tape;

[0050] 2. Adhesive preparation: uniformly stir acrylic resin and polyvinyl butyral (PVB) according to a mass ratio of 2:1, then add 30%-50% alcohol as a diluent, and use a planetary ball mill at 200 r / min for 2 h to obtain adhesive C;

[0051] 3. Green ceramic tape adhesive printing: print a thin layer of adhesive C on the surface of the green ceramic sheet with opened cavities using silk screen printing, control the printing thickness to be 2-5 μm, and naturally dry after 5 min;

[0052] 4. Lamination: laminate the dried green ceramic tape printed with adhesive C according to the processing design drawing with high-precision layer-by-layer alignment, and a certain pressure is required for 5-10 s for each lamination, the pressure is controlled to be 1-2 MPa, and after lamination of all single-layer green ceramic tapes is completed, the whole is taken out after being pressed for 10 s under a pressure of 5 MPa on the laminator, and the temperature of the pressure head is set to be 30°C during pressing;

[0053] 5. Vacuum packaging and isostatic pressing: wrap a 3-mm-thick thin soft silica gel pad with a preservative film, place it on a flat stainless steel plate with the oily surface upward to contact the green ceramic body, place the laminated green ceramic body on the soft silica gel, and then place another 3-mm-thick thin soft silica gel wrapped with a preservative film on the green ceramic body with the oily surface contacting the green ceramic body. Place the protected block and the steel plate together in a packaging belt for vacuum packaging (packaging conditions: vacuum pressure: -0.1 MPa, packaging time: 60 s), and press the vacuum-packaged block in an isostatic pressing machine (pressing conditions: water temperature: 65-75°C, pressure: 3.5-6.5 MPa, pressing time: 10-30 min) to obtain a multilayer ceramic block with double cavity structure multilayer ceramic circuit board;

[0054] 6. Hot cutting: take out the pressed block, and hot cut the product according to the designed cutting line to obtain the green multilayer ceramic circuit board with double cavity structure;

[0055] 7. Sintering: the green multilayer ceramic circuit board with double cavity structure is sintered according to the designed sintering curve to obtain the final multilayer ceramic circuit board with double cavity structure.

[0056] 8. Appearance inspection: the sintered multilayer ceramic circuit board with double cavity structure is observed under a 100 times microscope to check whether the ceramic section has delamination and cracking.

[0057] The sintered circuit boards with A, B and C glue respectively are observed under a 100 times microscope, and no delamination and cracking are found, and the whole cavity appearance is intact without deformation and cracking, and the flatness of the circuit board is less than or equal to 0.2%.

[0058] Finally, it should be noted that the above examples are only examples for clearly illustrating the present application, and the present application includes but is not limited to the above examples, and all the embodiments do not need to be exhausted here. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Any implementation scheme meeting the requirements of the present application belongs to the protection scope of the present application.

Claims

1. A method for fabricating a multilayer ceramic circuit board with a double-sided cavity structure, characterized in that, It comprises the following steps: (1) The green ceramic tape is punched, filled, printed with a conductor functional layer, dried, and then cavitated; (2) A thin layer of adhesive is printed on the surface of the cavitated green ceramic sheet, and is naturally dried for 5-10 minutes; (3) The dried green ceramic tape printed with adhesive is positioned according to the processing design drawing, and is laminated layer by layer, and after lamination, the laminated whole is pressed on the laminator for a certain time and then taken out; (4) The thin soft silica gel pad is wrapped with plastic wrap and placed on a flat stainless steel plate, the laminated ceramic green body is placed on the soft silica gel, and another soft silica gel wrapped with plastic wrap is placed on the ceramic green body, and then the vacuum packaging is subjected to isostatic pressing at a pressure of 3.5-6.5 MPa; (5) The pressed block is taken out, and the product is hot cut according to the designed cutting line to obtain the double-cavity structure multilayer ceramic circuit board green body, which can be sintered to obtain a double-cavity structure multilayer ceramic circuit board.

2. The method of manufacturing a multilayer ceramic circuit board having a dual-sided cavity structure of claim 1, wherein: The green ceramic tape is an LTCC or HTCC green ceramic tape with a thickness of 120-130 μm and a size of 203 mm x 203 mm.

3. The method of manufacturing a two-sided cavity structure multilayer ceramic circuit board of claim 1, wherein: The adhesive is a mixture of one or more of acrylic resin, LS glue, polyvinyl alcohol (PVA) and polyvinyl butyral (PVB), and 30-50% alcohol is added as a diluent, and is obtained by planetary ball milling for 2 h at 200 r / min.

4. The method of manufacturing a two-sided cavity structure multilayer ceramic circuit board of claim 1, wherein: The thickness of the adhesive is 2-5 μm.

5. The method of manufacturing a two-sided cavity structure multilayer ceramic circuit board of claim 1, wherein: The pressure on the laminator is 3-5 MPa, the time is 10-20 s, and the temperature of the press head is 30-50°C.

6. The method of manufacturing a two-sided cavity structure multilayer ceramic circuit board of claim 1, wherein: The plastic wrap is an oil-based plastic wrap, and the oil-based surface contacts the ceramic during pressing.

7. The method of manufacturing a two-sided cavity structure multilayer ceramic circuit board of claim 1, wherein: The thickness of the soft silica gel pad is 0.5-5 mm, and the hardness is 0-10 degrees. The thickness is determined according to the depth of the cavity, and the thickness of the silica gel pad: the depth of the cavity = 1.5:

1.

8. The method of manufacturing a two-sided cavity structure multilayer ceramic circuit board of claim 1, wherein: The isostatic pressing time is 10-30 min, and the water temperature is 60-75°C.

9. The method of manufacturing a two-sided cavity structure multilayer ceramic circuit board of claim 1, wherein, The specific steps are as follows: (1) Green ceramic tape preparation: The LTCC or HTCC green ceramic tape is punched, filled, printed with a conductor functional layer, dried, and then cavitated; (2) Adhesive preparation: acrylic resin is mixed with one or more of LS glue, polyvinyl alcohol (PVA) and polyvinyl butyral (PVB) in a certain proportion and stirred uniformly, and then 30-50% alcohol is added as a diluent, and is obtained by planetary ball milling for 2 h at 200 r / min; (3) Green ceramic tape glue printing: a thin layer of glue A is printed on the surface of the cavitated green ceramic sheet using silk screen printing, and the printing thickness is controlled to be 2-5 μm, and is naturally dried for 5 min; (4) Lamination: the dried green ceramic tape printed with glue A is positioned according to the processing design drawing, and is laminated with a certain pressure for 5-10 s, and the pressure is controlled to be 1-2 MPa, and after all the single-layer green ceramic tapes are laminated, the whole is pressed on the laminator for 10 s at a pressure of 5 MPa, and the temperature of the press head is set to 30°C during pressing. (5) vacuum packaging, isostatic pressing: the thickness of 3 mm soft silicone gel pad is wrapped with cling film and placed on a flat stainless steel plate, with the oily surface facing up to contact the ceramic green body, then the layered ceramic green body is placed on the soft silicone gel pad, and another soft silicone gel pad with a thickness of 3 mm wrapped with cling film is placed on the ceramic green body, with the oily surface contacting the ceramic green body; the protected bar and the steel plate are placed in a sealing belt for vacuum packaging treatment, the vacuum pressure of vacuum packaging is: -0.1 MPa, the packaging time is: 60 s, the vacuum packaged bar is placed in an isostatic pressing machine for pressing, the pressing conditions are: water temperature is 65~75℃, pressure is 3.5 MPa ~6.5 MPa, pressing time is 10 min~30 min; a multilayer ceramic circuit board multilayer ceramic bar with double cavity structure is obtained; (6) hot cutting: after the pressed bar is taken out, the product is hot cut according to the designed cutting line to obtain the double cavity structure multilayer ceramic circuit board green body; (7) sintering: the double cavity structure multilayer ceramic circuit board green body obtained by hot cutting is sintered according to the designed sintering curve to obtain the final double cavity structure multilayer ceramic circuit board; (8) appearance inspection: the sintered double cavity structure multilayer ceramic circuit board is observed under a 100 times microscope to check whether the ceramic cross section has delamination and cracking.

10. The method of manufacturing a two-sided cavity structure multilayer ceramic circuit board of claim 9, wherein, The composition of the adhesive glue is: acrylic resin: LS glue = 2:1, or acrylic resin: polyvinyl alcohol (PVA) = 2:1, or acrylic resin: polyvinyl butyral (PVB) = 2:1.

Images