A thick film and thin film hybrid circuit and a method for implementing the same

Abstract

The application provides a thick film and thin film hybrid circuit and an implementation method thereof. The hybrid circuit comprises four laminated ceramic substrates. The top ceramic substrate is a thin film ALN ceramic substrate, the top surface of which is plated with a thin film circuit layer through a thin film process, and the surface of the thin film circuit layer is plated with a good conductor plating layer. The two middle ceramic substrates are blank ALN ceramic substrates, which are used as sacrificial layers, and the surfaces thereof are flattened through thinning, polishing and polishing. The top surface of the bottom ceramic substrate is printed with a thick film circuit layer. A metal ground layer is arranged on the bottom surface of the bottom ceramic substrate. The thin film circuit layer is electrically connected with the thick film circuit layer and the metal ground layer through a metallized hole embedded in each ceramic substrate. The multi-layer layout structure is changed, the sacrificial layers are flattened, and the electrical connection between the thick film circuit and the thin film circuit is realized through the metallized via, so that the thick film and thin film hybrid integration is achieved, and the deformation problem that may occur during firing is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of thick film integrated radio frequency circuit, in particular to a kind of thick film thin film hybrid circuit and implementation method thereof. BACKGROUND

[0002] In the firing process of thick film integrated circuit, uneven heating of each layer can cause local bending of the ceramic substrate, which can cause unevenness of the surface circuit; In addition, the thermal expansion and contraction phenomenon in the firing process can also cause the diffusion or contraction of the surface metal conductor, thereby changing the size of the metal conductor and causing errors, causing signal transmission mutation, reflection, interference or impedance changes and other problems. In addition, the surface metal in thick film technology is generally tungsten, which has low electrical conductivity and can cause large loss, and the unevenness of the surface will cause problems in assembly, and will also change the signal transmission characteristics at high frequency. SUMMARY

[0003] In order to solve the above problems of the prior art, the present application provides a kind of thick film thin film hybrid circuit and implementation method thereof, changes multilayer layout structure, and the sacrificial layer is flattened, and the electrical connection of thick film circuit and thin film circuit is realized by metallized via, to achieve the purpose of thick film and thin film hybrid integration, and to improve the deformation problem that may occur in firing.

[0004] In order to achieve the above purpose, the present application adopts the following technology:

[0005] A kind of thick film thin film hybrid circuit, comprising:

[0006] Four stacked ceramic substrates, the top ceramic substrate is a thin film ALN ceramic substrate, the top surface of which is plated with a thin film circuit layer by thin film technology, and the surface of the thin film circuit layer is plated with a good conductor plating layer, the middle two ceramic substrates are blank ALN ceramic substrates, which are used as sacrificial layers, and the surfaces are flattened by thinning, polishing and polishing, and the top surface of the bottom ceramic substrate is printed with a thick film circuit layer;

[0007] Metal ground layer, provided on the bottom surface of the bottom ceramic substrate;

[0008] Wherein, the thin film circuit layer is electrically conductive with the thick film circuit layer and the metal ground layer through the metallized hole embedded in each ceramic substrate.

[0009] Further, the thin film circuit layer and the thick film circuit layer are both tungsten layers, and the tungsten layers are formed with microstrip line circuits or metal conductor circuits by photolithography process. Fine circuits are formed on the thin film circuit layer by photolithography.

[0010] A kind of implementation method of thick film thin film hybrid circuit, comprising the steps of:

[0011] Two blank ALN ceramic substrates are provided, the surfaces of which are thinned, polished and polished to be flat, and a plurality of metallized holes are processed through, and the two blank ALN ceramic substrates are laminated and stacked to be used as a sacrifice layer;

[0012] A thin film ALN ceramic substrate is processed on the top surface of the sacrifice layer, and a thin film circuit layer is processed on the top surface of the thin film ALN ceramic substrate by a thin film process, and dry metallized holes are processed through;

[0013] A good conductor plating layer is plated on the surface of the thin film circuit layer;

[0014] A ceramic substrate is provided, a thick film circuit layer is printed on the top surface of the ceramic substrate, and a plurality of metallized holes are processed through, and then the ceramic substrate is laminated and stacked on the bottom surface of the sacrifice layer;

[0015] A metal ground layer is provided, and the metal ground layer is laminated and stacked on the bottom surface of the ceramic substrate with the thick film circuit layer;

[0016] Firing is performed to make the metallized holes correspondingly connected, so that the thin film circuit layer, the thick film circuit layer and the metal ground layer are electrically connected.

[0017] The beneficial effects of the present application are:

[0018] 1. By arranging the thin film circuit layer and the thick film circuit layer on different ceramic substrates, and separating them by the sacrifice layer, and conducting by the metallized through holes, hybrid integration is realized, and the purpose of hybrid integration of thick film and thin film is achieved;

[0019] 2. The good conductor layer plated on the surface of the thin film circuit layer can increase the solderability and assembly of the entire circuit structure, also provides oxidation protection for the thin film circuit layer, and can improve the electrical conductivity of the circuit and reduce the loss;

[0020] 3. The surface of the blank ALN ceramic substrate of the sacrifice layer is flat, so that the thin film ALN ceramic substrate is reprocessed on the smooth surface, which can improve the bending deformation problem that may occur in the thick film process firing;

[0021] 4. To a certain extent, the problem of large loss of radio frequency signal transmission caused by low processing precision and uneven surface of pure thick film circuit is solved, and the problems of heating, radio frequency line sparking, dielectric breakdown and other problems caused by high power signal are also solved.

[0022] 5. Fine circuits are fabricated on the thin-film circuit layer using photolithography to form an integrated circuit. This avoids the problem of assembling individual circuits onto the surface of the thick-film circuit by soldering, which can block the lateral heat dissipation path and hinder heat dissipation under high power conditions. By realizing fine circuits through this solution, there are no installation gaps. In addition, ALN ceramic can provide good heat dissipation performance, and the good conductor plating layer also acts as a heat dissipation layer, which helps to dissipate heat. Attached Figure Description

[0023] Figure 1 This is an exploded view of the thick-film / thin-film hybrid circuit structure according to an embodiment of this application.

[0024] Figure reference numerals: Ceramic substrate-1, Thin film circuit layer-11, Thick film circuit layer-12, Good conductor plating-2, Metal ground layer-3, Metallized via-4, Fine circuit-5. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the implementation methods of the present invention will be described in detail below with reference to the accompanying drawings. However, the embodiments described in this invention are only some embodiments of the present invention, and not all embodiments.

[0026] A thick-film / thin-film hybrid circuit according to an embodiment of this application, such as Figure 1 As shown, it includes: a four-layer ceramic substrate 1 and a metal ground layer 3 stacked together.

[0027] The top ceramic substrate 1 is a thin-film ALN ceramic substrate. A thin-film circuit layer 11, a tungsten metal layer, is deposited on its top surface using a thin-film process. Microstrip line circuits or metal conduction band circuits are formed on this layer using photolithography. Simultaneously, fine circuits 5, such as Langer bridge circuits, can be formed on another portion of the thin-film circuit layer 11 using photolithography. The processing precision of the width between the metal lines needs to reach a certain level. The micrometers allow for the formation of an integrated circuit, avoiding the problem of assembling separate fine circuits onto the surface of a thick-film circuit through methods such as soldering, which would block the lateral heat dissipation path and hinder heat dissipation under high power conditions.

[0028] The thin film circuit layer 11 is coated with a good conductor plating layer 2, which can increase the solderability of the circuit and improve the assembly characteristics. In addition, the good conductor plating layer 2 can provide oxidation protection for the thin film circuit layer 11. Furthermore, since tungsten has low conductivity, the good conductor plating layer 2 will increase the conductivity of the surface conductor layer and reduce circuit loss.

[0029] Using the method in this example, the integrated fine circuit 5 has no mounting gaps. In addition, the high thermal conductivity of the ALN ceramic substrate can achieve good heat dissipation. The good conductor plating layer 2 on the surface of the thin film circuit layer 11 also acts as a heat dissipation layer, which helps to dissipate heat.

[0030] The middle two ceramic substrates 1 are blank ALN ceramic substrates, which are used as sacrificial layers and are thinned, polished and smoothed on the surface.

[0031] The top surface of the bottom ceramic substrate 1 is printed with a thick film circuit layer 12, which is a tungsten layer, and the microstrip circuit or metal conductor circuit is formed on the thick film circuit layer 12 by a photoetching process.

[0032] The metal ground layer 3 is arranged on the bottom surface of the bottom ceramic substrate 1.

[0033] The thin film circuit layer 11 is electrically connected to the thick film circuit layer 12 and the metal ground layer 3 through the metallized holes 4 embedded in the ceramic substrates 1, so as to realize the electrical connection of the thick film circuit and the thin film circuit, achieve the system function of the design, and achieve the purpose of thick film and thin film hybrid integration.

[0034] The implementation method of the thick film and thin film hybrid circuit according to the embodiment of the application comprises the following steps:

[0035] A ceramic substrate 1 is provided, the top surface of which is printed with a thick film circuit layer 12, and the bottom surface of which is provided with a metal ground layer 3, and a plurality of metallized holes 4 are processed through the ceramic substrate 1;

[0036] Two blank ALN ceramic substrates are provided, the surfaces of which are thinned, polished and smoothed, and a plurality of metallized holes 4 are processed through the two blank ALN ceramic substrates, and the two blank ALN ceramic substrates are laminated and arranged as sacrificial layers and are laminated on the ceramic substrate 1;

[0037] A thin film ALN ceramic substrate is laminated on the top surface of the sacrificial layer, a thin film circuit layer 11 is processed on the top surface of the thin film ALN ceramic substrate by a thin film process, and the metallized holes 4 are processed through the thin film circuit layer 11; then, a good conductor plating layer 2 is formed on the surface of the thin film circuit layer 11;

[0038] The thick film and the thin film are fired to form a thick film and thin film hybrid circuit, so that the thin film circuit layer 11, the thick film circuit layer 12 and the metal ground layer 3 are electrically connected.

[0039] The thin film processing process comprises sputtering, evaporation, electroplating, etching and other process steps on the ceramic substrate. During processing, the metal via or internal line between the thin film and the thick film is aligned, so as to obtain a multi-layer circuit which takes into account the advantages of thin film high precision, high flatness, high smoothness and thick film multi-layer interconnection.

[0040] The order of thick film first and then thin film, i.e. from high temperature to low temperature, avoids the oxidation of the surface layer of the thin film circuit at high temperature.

[0041] The above descriptions are only the preferred embodiment of the application, not intended to limit the application. Obviously, a person of ordinary skill in the art can make various modifications and variations to the application without departing from the spirit and scope of the application.

Claims

1. A thick film thin film hybrid circuit, characterized by comprising: The application relates to a four-layer ceramic substrate (1) which comprises: a top-layer ceramic substrate (1) which is a thin-film ALN ceramic substrate, the top surface of the thin-film ALN ceramic substrate is plated with a thin-film circuit layer (11) through a thin-film process, a good conductor plating layer (2) is plated on the surface of the thin-film circuit layer (11), the middle two ceramic substrates (1) are blank ALN ceramic substrates which are used as sacrifice layers, the surfaces of the blank ALN ceramic substrates are thinned, polished and smoothed, and the top surface of the bottom-layer ceramic substrate (1) is printed with a thick-film circuit layer (12); a metal ground layer (3) is arranged on the bottom surface of the bottom-layer ceramic substrate (1); the thin-film circuit layer (11) is electrically connected with the thick-film circuit layer (12) and the metal ground layer (3) through metalized holes (4) which are arranged in the ceramic substrates (1); the thin-film circuit layer (11) and the thick-film circuit layer (12) are both metal tungsten layers, and microstrip line circuits or metal conductor band circuits are formed on the metal tungsten layers through a photoetching process; and a fine circuit (5) is further formed on another part of the thin-film circuit layer (11) through a photoetching process. The application further relates to a manufacturing method of the four-layer ceramic substrate (1) which comprises the following steps: a ceramic substrate (1) is provided, a thick-film circuit layer (12) is printed on the top surface of the ceramic substrate (1), a metal ground layer (3) is arranged on the bottom surface of the ceramic substrate (1), and a plurality of metalized holes (4) are processed through the ceramic substrate (1); two blank ALN ceramic substrates are provided, the surfaces of the two blank ALN ceramic substrates are thinned, polished and smoothed, a plurality of metalized holes (4) are processed through the two blank ALN ceramic substrates, and the two blank ALN ceramic substrates are laminated and arranged on the ceramic substrate (1) as sacrifice layers; a thin-film ALN ceramic substrate is laminated on the top surface of the sacrifice layers, a thin-film circuit layer (11) is processed on the top surface of the thin-film ALN ceramic substrate through a thin-film process, and a plurality of metalized holes (4) are processed through the thin-film circuit layer (11); then, a good conductor plating layer (2) is plated on the surface of the thin-film circuit layer (11); the ceramic substrate (1) and the sacrifice layers are fired to make the metalized holes (4) correspondingly connected, so that the thin-film circuit layer (11), the thick-film circuit layer (12) and the metal ground layer (3) are electrically connected, and a thick-film thin-film mixed circuit is obtained; the thin-film circuit layer (11) and the thick-film circuit layer (12) are both formed of metal tungsten; after the thin-film circuit layer (11) and the thick-film circuit layer (12) are respectively processed, microstrip line circuits or metal conductor band circuits are formed on the thin-film circuit layer (11) and the thick-film circuit layer (12) through a photoetching process; and a fine circuit (5) is further formed on another part of the thin-film circuit layer (11) through a photoetching process. ​ ​ ​ ​ 2. A method of implementing a thick film thin film hybrid circuit, characterized by ​ ​ ​ ​ ​ ​ ​ ​

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