CN109905981B - Method for manufacturing low-temperature co-fired ceramic circuit board - Google Patents
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Abstract
The invention discloses a method for manufacturing a low-temperature co-fired ceramic circuit board, which is characterized in that before laminating low-temperature co-fired ceramic green ceramic chips printed by conduction bands, the low-temperature co-fired ceramic green ceramic chips are subjected to hot pressing pretreatment, the surface appearance of through hole slurry is modified, the through hole slurry can be densely filled, and the diffusion degree of the interlayer slurry is improved, so that microcracks at the interface between through holes of the low-temperature co-fired ceramic circuit board are prevented, and the reliability of the low-temperature co-fired ceramic circuit board is ensured.
Description
Technical Field
The invention belongs to the technical field of hybrid microelectronics, and particularly relates to a manufacturing method of a low-temperature co-fired ceramic circuit board for preventing microcracks of interfaces of adjacent through holes.
Background
Modern electronic information technology has increasingly high requirements on the volume, weight, performance and reliability of electronic equipment, and electronic components are promoted to be continuously promoted in the directions of high density, high frequency, high reliability, miniaturization and the like. The Low Temperature Co-fired Ceramic (LTCC) multilayer wiring circuit board has high integration density and excellent high-frequency characteristics, and plays an important role in the fields of System In Package (SiP), miniaturization of microwave T/R components and the like.
The LTCC multilayer wiring circuit board technology is that low-temperature sintering ceramic powder is made into a green ceramic film belt with a certain thickness by a tape casting process, the green ceramic film belt is cut into pieces to be used as a green ceramic substrate, required circuit patterns and resistance patterns (when applicable) are respectively made on each layer of the green ceramic substrate by the processes of punching, conductor slurry hole filling, wiring pattern printing and the like according to the pre-designed wiring patterns, the number of layers and the structure, then each layer of the green ceramic substrate is laminated and then hot-pressed together, and the conductor patterns, passive elements, a substrate and the like are fired at one time at 850-900 ℃ to form the LTCC multilayer wiring circuit board. This is a technique that can realize a 3D (three-dimensional) high-density wiring structure, high-performance microwave circuit package. In the manufacture of a high-reliability LTCC multilayer wiring circuit board, gold (Au) conductor paste is generally adopted as conductor paste and through hole paste.
The vertical interconnection structure can improve the wiring density of the substrate and further reduce the volume of an electronic component. The reliability of interconnection between the through holes of the respective layers directly affects the reliability of the wiring circuit board. After the circuit board is co-sintered, the contact interfaces of two adjacent layers of through holes are in a compact connection in an ideal state, and if the circuit board is co-sintered, a tiny non-compact connection is locally formed at the contact interfaces of two adjacent layers of through holes, which is shown as a microcrack. When the substrate with the through hole microcracks undergoes subsequent high and low temperature cycling or mechanical impact examination, electrical interconnection open circuit failure may occur, and the failure mode is a hidden danger of a high-reliability LTCC multilayer wiring circuit board.
Disclosure of Invention
Based on the method, the invention provides a method for manufacturing a low-temperature co-fired ceramic circuit board for preventing microcracks on the interface of adjacent through holes, and the filling morphology of the through hole slurry is modified by adopting a hot-pressing pretreatment method on the low-temperature co-fired ceramic green ceramic chip after conduction band printing. Through the modification, the filling of the through hole slurry is compact, and the diffusion degree of the conductor slurry between the through holes of each layer is improved, so that the microcrack phenomenon caused by non-compact connection at the interface of the adjacent through holes is solved, and the reliability of the LTCC multilayer wiring circuit board is improved.
In order to achieve the purpose, the invention adopts the following technical scheme:
a manufacturing method of a low-temperature co-fired ceramic circuit board comprises the steps of punching a low-temperature co-fired ceramic green chip, filling holes, conducting belt printing, laminating, hot pressing and co-firing, and hot pressing pretreatment is further included between the conducting belt printing step and the laminating step. In the conventional process, the manufacture process of the LTCC circuit board is that the LTCC green ceramic chip is subjected to punching, hole filling, conduction band printing and lamination hot pressing and then co-fired, in the process, a certain micro area of a contact interface of adjacent through holes is easy to be not fully contacted, after the co-firing, tiny non-compact connection is formed at the part of the interface, so that the phenomenon of microcrack is caused at the interface of the adjacent through holes, and during subsequent high-low temperature circulation or mechanical impact examination, electrical interconnection open circuit failure is caused, so that potential safety hazards are caused. According to the invention, before the LTCC green ceramic chips are laminated, the hot pressing pretreatment method is adopted to modify the filling morphology of the slurry of the through holes on the LTCC green ceramic chips, so that the slurry of the through holes is densely filled, and the microcrack phenomenon of the interface of the adjacent through holes of the LTCC circuit board is solved.
Further, the hot pressing pretreatment comprises the following specific steps: and placing the low-temperature co-fired ceramic green chip with mylar films clamped on two surfaces between two hard flat plates, then placing the low-temperature co-fired ceramic green chip on a working area table top of a hot press, carrying out hot pressing, and taking out the low-temperature co-fired ceramic green chip after hot pressing pretreatment after the hot pressing is finished. Mylar films are clamped on two surfaces of the low-temperature co-fired ceramic green ceramic chips to prevent the low-temperature co-fired ceramic green ceramic chips from being stuck on a hard flat plate after being heated. The Mylar film can be a Mylar carrier tape film obtained by peeling off the LTCC green tiles, and preferably, the thickness of the Mylar film is 0.04-0.05 mm. More specifically, after the hot-pressed and pretreated LTCC green ceramic chip is taken out, the upper surface and the lower surface of the substrate are inspected under a microscope with the magnification of 10-20 times, foreign matters on the upper surface and the lower surface are cleaned by a soft brush, and after the appearance of the hot-pressed and pretreated LTCC green ceramic chip is qualified, the subsequent LTCC circuit board manufacturing process is carried out.
Preferably, the stereoplasm flat board is the smooth stainless steel flat board in surface, prevents to appear the pit on the LTCC green porcelain piece when hot pressing preliminary treatment, if the flat board is not smooth, appears the pit on the LTCC green porcelain piece easily when hot pressing preliminary treatment, and is preferred, and its thickness is 0.2~0.6 mm.
Further, according to the requirements of the invention, the technological parameters of the hot-pressing pretreatment are optimized, the temperature of the hot-pressing pretreatment is 30-50 ℃, the pressure of the hot-pressing pretreatment is 0.1-0.4 kpsi, and the pressure maintaining time of the hot-pressing pretreatment is 1-15 s. Under such hot pressing parameters, the effect of preventing microcracks at the interface of adjacent through holes is best.
Further, the hot press pretreatment may be performed in a hot press leveler or an isostatic press.
According to the invention, the hot-pressing pretreatment is preferably carried out in an isostatic press. The hot pressing pretreatment is carried out in the isostatic pressing machine, so that the hot pressing pretreatment of a plurality of LTCC green ceramic chips can be simultaneously realized at one time, and the manufacturing efficiency and the yield of the LTCC circuit board are greatly improved.
Compared with the prior art, the manufacturing method modifies the surface appearance of the through hole slurry before lamination, thereby preventing microcracks between adjacent through holes of the LTCC multilayer wiring circuit board. After the surface of the slurry filled in the through hole is subjected to hot-pressing pretreatment modification, the through hole slurry can be densely filled, so that the interfaces of the slurry of the upper layer and the lower layer of the through hole are in close contact during the subsequent hot pressing of the lamination, the mutual diffusion of the slurry at the interfaces of the upper layer and the lower layer of the through hole is facilitated, the diffusion degree of the conductor slurry between layers is improved, the compact combination is formed at the interface, and the reliability of the prepared circuit board is guaranteed.
Drawings
FIG. 1 is a sectional view of an LTCC substrate made of an LTCC ceramic circuit board produced in example 2;
fig. 2 is a sectional view of an LTCC substrate made of the LTCC ceramic circuit board made in the comparative example.
Detailed Description
In order that the invention may be more fully understood, reference will now be made to the specific embodiments illustrated. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
Example 1
The LTCC ceramic circuit board in the embodiment is manufactured according to the steps of punching, hole filling, conduction band printing, hot pressing pretreatment, lamination, hot pressing and co-firing, wherein the hot pressing pretreatment adopts an isostatic press, and the hot pressing pretreatment specifically comprises the following steps:
and (3) mounting: and sequentially assembling 8 raw ceramic chips into a stainless steel flat plate, a mylar film, a first LTCC raw ceramic chip, a mylar film, a stainless steel flat plate, a mylar film, a second LTCC raw ceramic chip, a mylar film, a stainless steel flat plate, a mylar film, a third LTCC raw ceramic chip and a mylar film … … from bottom to top in the same manner until the stainless steel flat plate, the mylar film, an eighth LTCC raw ceramic chip, the mylar film and the stainless steel flat plate are assembled.
And (3) encapsulation: fixing the LTCC green ceramic chip with the piece by using a transparent adhesive tape, and then placing the fixed LTCC green ceramic chip into a vacuum rubber skin to enable the vacuum rubber to completely wrap the LTCC green ceramic chip with the piece; and then the wrappage is placed into a vacuum envelope bag to form a vacuum envelope.
Hot pressing: placing the vacuum encapsulating piece in an isostatic pressing machine at the temperature of 30 ℃ and the pressure of 0.3kpsi for hot pressing, wherein the pressure maintaining time is 12 s; and after hot pressing is finished, taking out the vacuum encapsulating piece, and cooling and taking out the LTCC green ceramic chip subjected to hot pressing pretreatment.
And (3) inspecting the upper surface and the lower surface of the hot-pressed raw LTCC chip under a microscope with the magnification of 10-20 times, and removing foreign matters by using a soft brush.
Example 2
The LTCC ceramic circuit board in the embodiment is manufactured according to the steps of punching, hole filling, conduction band printing, hot pressing pretreatment, lamination, hot pressing and co-firing, wherein the hot pressing pretreatment adopts an isostatic press, and the hot pressing pretreatment specifically comprises the following steps:
and (3) mounting: and (3) sequentially loading 20 raw ceramic chips into a stainless steel flat plate, a mylar film, a first LTCC raw ceramic chip, a mylar film, a stainless steel flat plate, a mylar film, a second LTCC raw ceramic chip, a mylar film, a stainless steel flat plate, a mylar film, a third LTCC raw ceramic chip and a mylar film … … from bottom to top in the same manner until the stainless steel flat plate, the mylar film, a twentieth LTCC raw ceramic chip, the mylar film and the stainless steel flat plate are loaded in the sequence.
And (3) encapsulation: fixing the LTCC green ceramic chip with the piece by using a transparent adhesive tape, and then placing the fixed LTCC green ceramic chip into a vacuum rubber skin to enable the vacuum rubber to completely wrap the LTCC green ceramic chip with the piece; and then the wrappage is placed into a vacuum envelope bag to form a vacuum envelope.
Hot pressing: placing the vacuum encapsulating piece in an isostatic pressing machine at the temperature of 50 ℃ and the pressure of 0.1kpsi for hot pressing, wherein the pressure maintaining time is 15 s; and after hot pressing is finished, taking out the vacuum encapsulating piece, and cooling and taking out the LTCC green ceramic chip subjected to hot pressing pretreatment.
And (3) inspecting the upper surface and the lower surface of the hot-pressed raw LTCC chip under a microscope with the magnification of 10-20 times, and removing foreign matters by using a soft brush.
Example 3
The LTCC ceramic circuit board in the embodiment is manufactured according to the steps of punching, hole filling, conduction band printing, hot pressing pretreatment, lamination, hot pressing and co-firing, wherein the hot pressing pretreatment adopts an isostatic press, and the hot pressing pretreatment specifically comprises the following steps:
and (3) mounting: the sheets are sequentially arranged from bottom to top according to the sequence of a stainless steel flat plate, 2 mylar films, a first LTCC green ceramic sheet, 2 mylar films and a stainless steel flat plate.
Hot-pressing pretreatment: placing the assembled LTCC green ceramic chip into a hot pressing leveling machine with the temperature of 40 ℃ and the pressure of 0.4kpsi for hot pressing, wherein the pressure maintaining time is 10 s; and after hot pressing is finished, taking out the vacuum encapsulating piece, and cooling and taking out the LTCC green ceramic chip subjected to hot pressing pretreatment.
And (3) inspecting the upper surface and the lower surface of the hot-pressed raw LTCC chip under a microscope with the magnification of 10-20 times, and removing foreign matters by using a soft brush.
The remaining 7 green LTCC tiles were processed in sequence according to the previous steps.
After the LTCC green ceramic chips subjected to the hot pressing pretreatment and qualified in appearance inspection in the embodiments 1-3 are sequentially subjected to lamination hot pressing and adhesive removal co-firing, the co-fired LTCC circuit board through holes are subjected to section sample preparation analysis. Meanwhile, the LTCC green ceramic chip which is not subjected to the hot pressing pretreatment in the embodiment 2 is subjected to lamination hot pressing and adhesive removal co-firing in sequence to be used as a comparative example, and the through hole of the co-fired LTCC circuit board is subjected to section sample preparation analysis, wherein the section sample preparation analysis method comprises the following steps: placing the LTCC circuit board sample in a mould, and pouring and curing by using a curing agent; taking out the solidified sample from the die, cutting, grinding and polishing the section, and exposing the section of the through hole; corroding in aqua regia for 1-4 min, cleaning with deionized water, and wiping with filter paper; and finally, observing the surface appearance of the section of the through hole under a microscope with the magnification of 200-500.
Fig. 1 is a sectional surface topography of a circuit board of embodiment 2 of the present invention, and fig. 2 is a sectional surface topography of a circuit board of a comparative example, and it can be seen from fig. 1 and fig. 2 that adjacent through holes of a circuit board manufactured in embodiment 2 of the present invention are densely combined without microcracks, while an interface of adjacent through holes of a comparative example is not dense and has microcracks, which shows that microcracks are effectively prevented from being generated at an interface of adjacent through holes of a low-temperature co-fired ceramic circuit board by the method of the present invention.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (5)
1. A manufacturing approach of the ceramic circuit board of low temperature cofiring, the said manufacturing approach of ceramic circuit board of low temperature cofiring includes punching the ceramic green chip of low temperature cofiring, hole filling, conduction band printing, lamination, hot pressing and cofiring, characterized by, between printing and said lamination step of the conduction band, also include the hot pressing preconditioning;
the hot-pressing pretreatment comprises the following specific steps: and placing the low-temperature co-fired ceramic green ceramic chip with the mylar film clamped on both sides after the conduction band printing between two hard flat plates, performing hot pressing, and taking out after the hot pressing is completed.
2. The method according to claim 1, wherein the hard flat plate is a stainless steel flat plate having a smooth surface and a thickness of 0.2 to 0.6 mm.
3. The method according to claim 1, wherein the temperature of the hot-pressing pretreatment is 30 to 50 ℃, the pressure of the hot-pressing pretreatment is 0.1 to 0.4kpsi, and the dwell time of the hot-pressing pretreatment is 1 to 15 seconds.
4. A method according to any one of claims 1 to 3, wherein the hot press pretreatment is carried out in a hot press leveler or isostatic press.
5. The method of claim 4, wherein the hot press pretreatment is performed in an isostatic press.
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| CN111031727B (en) * | 2019-12-26 | 2021-07-06 | 中国电子科技集团公司第四十四研究所 | Parallel seam welding packaging point frequency source assembly and manufacturing method thereof |
| CN112493557A (en) * | 2020-11-11 | 2021-03-16 | 深圳麦克韦尔科技有限公司 | Heating element and heating atomization device |
| CN112739006B (en) * | 2020-11-16 | 2022-05-27 | 中国科学院空天信息创新研究院 | Manufacturing method of LTCC circuit substrate |
| CN112786519A (en) * | 2021-01-13 | 2021-05-11 | 中国兵器工业集团第二一四研究所苏州研发中心 | Green ceramic lamination device and method |
| CN114743787B (en) * | 2022-03-29 | 2023-11-21 | 中国电子科技集团公司第四十三研究所 | Manufacturing method of detachable LTCC planar transformer |
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