JPH0151075B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of manufacturing a ceramic multilayer circuit board for a hybrid integrated circuit.

Conventional Structures and Their Problems In recent years, as demands for electronic devices to be smaller, lighter, and more functional have increased, increasing the density of these electronic circuits has become an important issue.

Under these circumstances, various measures have recently been taken as a means of increasing the density of electronic circuits.In particular, electronic circuits are constructed using modular parts (unitization) by converting circuits into functional blocks. Mounting methods that aim at higher density are now being adopted in many electronic devices.

This functional block modular part is
Hybrid integrated circuit components, also known as hybrid ICs, have been put into practical use in a variety of forms, contributing to smaller, lighter weight, higher functionality, and lower prices of electronic devices.

Currently, the configuration of hybrid integrated components that is widely used is to form a circuit conductor layer using a metal glaze-based thick film conductor material made of silver-palladium on a ceramic insulating substrate such as alumina, and to form a circuit conductor layer on the same surface. A resistor circuit layer is formed using a ruthenium oxide thick film resistor material on top of the circuit board. Circuit elements necessary to construct a functional block circuit, such as capacitors, transistors, and ICs, are mounted on the circuit board and electrically connected. This is what I did.

Nowadays, there has been a rapid increase in demand for higher integration of hybrid integrated circuit components themselves, and along with this, multi-layering of circuit boards has become an indispensable condition.

Various manufacturing methods have been used to date for this multilayer circuit board, and an example of a typical manufacturing process for a multilayer circuit board based on a ceramic substrate is shown in FIGS. 1A to 1C.

The method for manufacturing this multilayer circuit board is shown in Figure 1A.
As shown in the figure, a metal glaze conductor paste made of silver-palladium and a metal glaze resistor paste made of ruthenium oxide are screen printed on the surface of a ceramic insulating substrate 1 made of alumina or the like, respectively. A first circuit conductor layer 2, a resistor layer 2, and a resistor layer 3 are formed by coating the first circuit conductor layer 2, and then an insulating layer made of a photopolymer is applied on the surface of the first circuit conductor layer 2 as shown in FIG. 4 and this insulating layer 4
A micro hole 5 in the form of a via hole is made in the first circuit conductor layer 2 so that a part of it is exposed on the surface, and then electroless plating and electric plating are applied to the surface of the insulating layer 4 as shown in FIG. 1C. This is a manufacturing method in which the second circuit conductor layer 6 is formed by a semi-additive method using a bonding technique, and is electrically connected to the first circuit conductor layer through the micro holes 5 to form a multilayer circuit conductor layer.

However, a serious drawback of the multilayer circuit board produced by this method is that the insulator layer 4 made of photopolymer
In the method of forming the second circuit conductor layer 6 on the surface of the insulating layer 4 by a plating method, the glass component contained in the metal glaze-based first circuit conductor layer 2 exposed from the insulating layer 4 is exposed to an electroless plating solution or an electric metal. The problem is that it is extremely easily attacked by acids and alkalis contained in the soaking liquid, and therefore, the reliability of the connection between the first circuit conductor layer 2 and the second circuit conductor layer 6 cannot be sufficiently ensured.

OBJECT OF THE INVENTION An object of the present invention is to provide a method for manufacturing a multilayer circuit board that improves the reliability of connections between interlayer conductor layers.

Structure of the Invention The method for manufacturing a multilayer circuit board of the present invention includes forming a metal glaze-based thick film circuit conductor layer and a thick film resistor layer on at least one main surface of a ceramic insulating substrate, and then forming a thick film circuit conductor layer and a thick film resistor layer on at least one main surface of a ceramic insulating substrate. An insulating layer made of a photopolymer is formed on the layer and the thick film resistor layer, and micro holes in the form of via holes are formed in the necessary locations of this insulating layer using photographic technology to form the thick film circuit conductor. After exposing a portion and filling the micropores with a highly heat-resistant resin-based conductive paste, a circuit conductor layer is formed on the insulator layer by electroless plating.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 2A to 2D show steps in a method for manufacturing a multilayer circuit board according to an embodiment of the present invention.

In FIG. 2, 7 is a ceramic insulating substrate;
9 is a thick film first circuit conductor layer, 9 is a thick film resistor layer, and 10 is a thick film first circuit conductor layer.
is a photopolymer insulator layer, 11 is a micropore, 12
1 is a high heat-resistant resin conductive layer, and 13 is a second circuit conductor layer.

The manufacturing process of the multilayer circuit board of this embodiment configured as described above will be explained in detail below.
First, as shown in FIG. 2A, a metal glaze-based conductive paste is prepared by mixing fine powder of silver or silver-palladium with glass frit and a resin binder on one main surface of a ceramic insulating substrate 7 made of alumina or the like. is applied by screen printing method,
By firing at a high temperature of 850 to 900℃, the first thick film
A circuit conductor layer 8 is formed, and then a resistor paste made by mixing fine powder of ruthenium oxide with glass frit and a resin binder into a paste is applied on the same surface of this thick film circuit conductor layer by the same screen printing method. Then, a thick film resistor layer 9 was formed by firing at a high temperature of 800° C. to 850° C., and adjusted to a predetermined resistance value by a laser trimming method. Then, as shown in FIG. 2B, a photopolymer type insulator layer 10 is applied to the entire surface of the thick film first circuit conductor layer 8, and a photopolymer type insulator layer 10 is applied to form the thick film first circuit conductor to which connection is required. A fine hole 11 is made in the form of a via hole so that a part of the layer is exposed on the surface, and then this fine hole 11 is made as shown in FIG. 2C.
The conductive layer 12 is formed by filling a conductive paste with high heat resistance into the conductive paste by screen printing and hardening it by heating.

In this step, the photopolymer used as the insulating layer is required to have excellent properties such as heat resistance, electrical insulation properties, and chemical resistance.

In this example, a dry film of an epoxy-modified acrylic resin and a cyclized rubber-based polybutadiene resin was used as a photopolymer that met this purpose.

Further, the conductive layer 12 filling the micropores 11 is required to have high heat resistance as well as excellent chemical resistance and thermal shock resistance. Fine silver powder was dispersed in a high-molecular-weight epoxy resin, and a conductive paste using an aromatic amine as a hardening agent was used.

Then, as shown in FIG. 2D, electroless plating and electroplating are applied to the entire surface of the insulating layer 10 made of photopolymer to form a conductive metal layer,
Furthermore, a second circuit conductor layer 13 made of a conductive metal layer was formed in a desired wiring circuit shape by an etching method, and a multilayer circuit board electrically connected to the thick film first circuit conductor layer 8 was produced.

As described above, according to this embodiment, the micropores 11 provided in the photopolymer insulating layer 10 are filled with a conductive paste 12 made of a high heat-resistant resin, and the conductive layer 1
Since the second circuit conductor layer 13 is formed by the plating method through the interlayer conductor layer 2, there is no erosion of the thick film first circuit conductor layer 8 during the plating process, so the reliability of the connection between the interlayer conductor layers can be ensured.

Furthermore, since the insulator layer 10 is composed of a photopolymer, there is no need for high-temperature firing to form the insulator layer as in the conventional case. Therefore, manufacturing of the multilayer circuit board becomes very easy. not only that,
Since there is no fear that the resistance value of the thick film resistor layer 9 will change when the insulator layer 10 is formed, the insulator layer 1
A multilayer circuit board suitable for high-density packaging can be obtained, which has a thick film resistor layer 9 under the layer 9.

Next, other embodiments of the present invention will be described with reference to the drawings.

3A to 3D show the manufacturing process of a multilayer circuit board according to another embodiment of the present invention.

First, FIGS. 3A and 3B are completely similar to FIGS. 2A and 2B shown in the above-mentioned embodiment, and first, as shown in FIG. 1. After forming a circuit conductor layer 8 and a thick film resistor layer 9 on the same surface thereof, a photopolymer insulator layer 10 is formed on this surface as shown in FIG. A shaped micropore 11 is made. Thereafter, as shown in FIG. 3C, the fine holes 11 are filled with a highly heat-resistant resin conductive paste 12 made of fine silver powder and epoxy resin by screen printing, and the surface of the photopolymer insulator layer 10 is also filled with a conductive paste 12. , the conductive paste 12 is applied in the shape of a desired wiring circuit, cured by heating, and as shown in FIG. A multilayer circuit board is produced by forming a second circuit conductor layer 13 by depositing a layer of conductive metal such as copper or nickel on layer 12.

In this example, a multilayer circuit board with better adhesion between the second circuit conductor layer 13 and the photopolymer insulator layer 10 than the multilayer circuit board obtained in the above-described example can be realized. Since it can be formed only by electroless plating, it has the advantage of simplifying the process.

In the above-mentioned embodiments, a method was described in which a circuit conductor layer is multilayered on one side of a ceramic insulating substrate, but in the present invention, a thick film circuit conductor layer and a resistor are formed on both the front and back sides of a ceramic insulating substrate. It goes without saying that it is also possible to form a body layer, connect the front and back circuit conductor layers through through holes, and then multilayer the circuit conductor layers on each surface using the method described above.

Effects of the Invention As is clear from the above description, the present invention forms a thick film circuit conductor layer on at least one main surface of a ceramic insulating substrate, a thick film resistor layer on the same surface, and a photopolymer layer on the surface thereof. At the same time as forming an insulator layer using a method of forming an insulator layer, a micro hole in the form of a via ear hole is made using photographic technology at the location where a connection is required to expose a part of the thick film circuit conductor layer. Filled with heat-resistant resin conductive paste,
A second coating is applied to the surface of the photopolymer layer using plating technology.
A multilayer circuit board is created by forming a circuit conductor layer, and by filling micro holes provided in a photopolymer insulator layer with conductive paste.
The exposed thick film circuit conductor layer is completely protected, and therefore the glass components contained in the thick film circuit conductor layer will not be eluted by acid or alkaline solutions during the subsequent plating process, and the electricity in the interlayer circuit conductor layer will be protected. In addition to ensuring reliable physical connections, the reliability of interlayer connections in thermal shock and moisture resistance tests was significantly improved.

In addition, by printing a circuit in the form of a circuit on the photopolymer insulator layer using a conductor paste that fills the micropores to form the second circuit conductor layer, we have created a multilayer structure with extremely high adhesion of the outermost circuit conductor layer. A circuit board can be obtained, and since the second circuit conductor layer can be formed only by electroless plating, the process can be simplified.

Furthermore, since the insulator layer is comprised of a photopolymer, high temperature firing as in conventional multilayer circuit board manufacturing is not required. Therefore, manufacturing of the multilayer circuit board becomes very easy. In addition, there is no fear that the resistance value of the thick film resistor layer will change during the formation of the insulator layer, making it possible to provide a multilayer circuit board that has a thick film resistor layer under the insulator layer and is suitable for high-density packaging. This effect can be obtained.

[Brief explanation of drawings]

FIGS. 1A to 1C are manufacturing process diagrams of a conventional multilayer circuit board, FIGS. 2A to D are manufacturing process diagrams of a multilayer circuit board according to an embodiment of the present invention, and FIGS. 3A to D are manufacturing process diagrams of a conventional multilayer circuit board. It is a part of manufacturing process diagram of the multilayer circuit board in Example. 7... Ceramic insulating substrate, 8... Thick film first circuit conductor layer, 9... Thick film resistor layer, 10... Photopolymer insulating layer, 11... Micropore, 12... High heat resistant resin conductive layer Layer 13...Second circuit conductor layer.

Claims (1)

[Claims] 1. Forming a metal glaze-based thick film circuit conductor layer on at least one main surface of a ceramic insulating substrate, and forming a thick film resistor layer on the same main surface of the ceramic insulating substrate. a step of forming an insulating layer made of a photopolymer on the thick film circuit conductor layer and the thick film resistor layer; A step of forming a hole to expose a part of the thick film circuit conductor, a step of filling the fine hole with a conductive paste made of a high heat resistant resin, and a step of forming a circuit on the insulating layer by an electroless plating method. 1. A method for manufacturing a multilayer circuit board, comprising the step of forming a conductor layer. 2 A conductive paste made of a high heat-resistant resin is filled into the micropores provided in the insulating layer made of photopolymer, and at the same time, it is applied on the surface of the insulating layer in the form of a wiring circuit, and then electroless plating is performed. 2. The method of manufacturing a multilayer circuit board according to claim 1, wherein the second circuit conductor layer is formed by depositing a conductive metal layer by a method.