JPH0480539B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thick film integrated circuit suitable for reducing the conductor resistance of a thick film conductor, and a method for manufacturing the same.

[Conventional technology]

Conventionally, in thick film integrated circuits, thick film conductors that form the electrodes of resistors are installed on a substrate made of a ceramic plate or the like by printing and firing a conductive paste containing silver and palladium (Ag, Pd).
A resistor is installed between the thick film conductors by printing and baking a resistor paste. An overcoat is applied on the resistor, and after trimming, a plating resist layer is installed to protect the resistor, etc., and copper (Cu) is deposited on the substrate exposed from the plating resist layer. ) A film is formed and a specific circuit pattern is formed. Then, an etching resist layer is selectively placed on the thick film integrated circuit on which the Cu film is formed, and after etching the exposed portions of the etching resist layer,
A solder resist layer is installed.

In addition, for thick film integrated circuits in which circuit patterns are formed using Cu film through such plating processing, circuit patterns are formed through thick film conductors by printing and firing conductor paste containing Ag and Pd. Thick film integrated circuits have been put into practical use.

[Problem to be solved by the invention]

By the way, it is possible to directly coat the board by plating.
In thick film integrated circuits plated with Cu, a circuit pattern is formed by applying an etching resist layer on the Cu film and etching it.Resist printing makes it difficult to obtain fine lines and requires an additional etching process. The drawback was that the manufacturing process took a long time. In addition, Cu film requires specific technology for the wire bonding process between it and the IC.
The disadvantage was that the wire bonding process was complicated.

In addition, in thick film integrated circuits in which circuit patterns are formed by thick film conductors printed and fired with conductor paste containing Ag and Pd, if solder is placed on the thick film conductors, deterioration over time such as solder erosion may occur. There is a possibility that this may occur. For example, if solder is fixed on a thick film conductor and left in a high temperature atmosphere of around 150℃ for several hundred hours,
Tin (Sn) in the solder is diffused into the thick film conductor, and Ag in the thick film conductor is diffused into the solder. When Sn in the solder diffuses into the thick film conductor, the adhesion strength as a solder decreases, and the Ag in the thick film conductor decreases.
When Ag is diffused into the solder, Ag escapes from the thick film conductor, reducing the strength of the thick film conductor.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a thick film integrated circuit and a method for manufacturing the same, which can reduce the conductor resistance of a thick film conductor, prevent deterioration over time, and facilitate wire bonding processing.

[Means to solve the problem]

In the thick film integrated circuit of the present invention, a conductive film is selectively installed on a thick film conductor to be connected to any circuit element installed on a substrate with a conductor wire, and the parts where this conductive film is not installed are provided. The conductor wire is connected between the circuit element and the circuit element.

Further, in the thick film integrated circuit of the present invention, the thick film conductor may be constructed of a conductor paste containing silver and palladium, and a copper film may be provided as a conductive film on the thick film conductor.

Next, the method for manufacturing a thick film integrated circuit of the present invention is as follows:
A resist layer is placed on the connection portion of the thick film conductor that is to be connected to any circuit element installed on the board using a conductor wire, and the thick film conductor exposed from the resist layer is plated. a conductive film is placed on the substrate, the resist layer is peeled off, the circuit element is placed on the substrate, and the circuit element is placed between the connection part of the thick film conductor from which the resist layer is peeled off. It connects conductor wires.

[Effect]

In the thick film integrated circuit of the present invention, a conductive film is provided on the thick film conductor provided on the substrate.
The resistivity of a conductor circuit made of a thick film conductor is reduced by the conductive coating. When a conductive film is installed on a thick film conductor, the conductive film also functions as a protective film against solder etc. for the thick film conductor.
Since direct contact between the thick film conductor and the solder can be avoided, deterioration over time such as solder erosion of the thick film conductor can be prevented. In addition, since the circuit element is installed on the substrate and the conductor wire is connected between the thick film conductor and the circuit element where the resist layer has been peeled off, there is no need to take into account the characteristics of the conductive film.
Electrical connections between thick film conductors and circuit elements can be made with conductor wires.

Then, the thick film conductor is formed with a conductor paste containing Ag and Pd, and if a Cu film is placed as a conductive film on the thick film conductor, Pd acts as a catalyst for Cu, so a special plating is applied. A Cu film can be easily formed by simply immersing a substrate on which a thick film conductor is formed in a plating solution capable of Cu plating, without requiring any processing operations. Further, the portion of the thick film conductor on which the Cu film is not provided and the circuit element can be easily connected by welding with the conductor wire.

In addition, if a conductive film made of Cu film is installed as a protective film on a thick film conductor formed using a conductor paste containing Ag and Pd, when solder is installed, Sn in the solder will diffuse into the thick film conductor. , diffusion of Ag in the thick film conductor to the solder is prevented, protecting the solder and the thick film conductor from deterioration over time, and maintaining connection reliability.

Next, in the method for manufacturing a thick film integrated circuit of the present invention, a resist layer is provided to cover a part of the thick film conductor placed on the substrate, and the portion of the thick film conductor exposed from the resist layer is plated. If a conductive film is provided, the conventional etching process becomes unnecessary, and the conductor resistance of the thick film conductor can be easily reduced, making it possible to shorten the processing time. Then, from the thick film conductor covered with a resist layer,
After peeling off the resist layer, a circuit element is placed on the substrate, and a conductor wire is connected between the thick film conductor and the circuit element at the part where the resist layer is peeled off.

〔Example〕

FIG. 1 shows an embodiment of the thick film integrated circuit of the present invention.

A plurality of thick film conductors 4 and 6 are selectively installed at specific intervals according to a specific circuit pattern on the front and back surfaces of a substrate 2 made of an insulating material such as ceramic or alumina. On the membrane conductor 4 side, there is an installation area 8 where circuit elements such as ICs are installed.
is set. This installation area 8 is defined by the space on the substrate 2 where the thick film conductor 4 is not installed. A bonding pad portion 9 is provided on the thick film conductor 4 at the peripheral portion of the installation area 8 as a connection portion for connecting with a circuit element within a certain range. A conductive film 12 made of a highly conductive metal such as Cu is selectively formed on the surfaces of the thick film conductors 4 and 6 except for the portion set in the bonding pad portion 9.

Furthermore, in the installation area 8, a bare chip 14 as a circuit element is fixed with an adhesive 16, and a highly conductive metal such as Au or Al is placed between the electrode part 18 of the bare chip 14 and the bonding pad part 9. A conductor wire 20 consisting of the two is connected by welding to establish an electrical connection between the two.

Then, on the surface of the substrate 2, a resin coat 22 covering the bare chip 14 extends over the thick film conductor 4 covered with the conductive film 12, and the bare chip 14 is protected by the resin coat 22.

Further, a solder resist layer 24 is selectively provided on the conductive film 12 on the thick film conductor 4 side, but no solder resist layer is provided on the thick film conductor 6 side for convenience of soldering. Not yet.

With this configuration, the surfaces of the thick film conductors 4 and 6 are covered with the conductive film 12, thereby protecting the surfaces and reducing the resistance of the conductor circuit. Furthermore, when a Pd-Ag based conductor paste containing Ag and Pd is used for the thick film conductors 4 and 6 and the conductive film 12 is formed of a Cu film, the Cu film functions as a diffusion preventer. , the diffusion of Sn in the solder to the thick film conductors 4 and 6, or
Diffusion of Ag in the thick film conductors 4 and 6 to the solder can be prevented, and a decrease in adhesion strength such as solder erosion and a decrease in reliability of the conductor circuit can be prevented.

Further, since the conductive film 12 is not formed on the bonding pad portion 9, there is no need to consider the characteristics of the conductive film 12 installed on the thick film conductor 4. For example, Cu film requires oxidation prevention treatment such as nickel plating or gold plating to improve wire bonding properties. The conductor wire 20 can be easily connected to the membrane conductor 4.

Next, FIGS. 2 to 4 show an embodiment of the method for manufacturing a thick film integrated circuit according to the present invention in the order of steps.

As shown in FIG. 2A, the substrate 2 is made of an insulating material such as ceramic or alumina.

Next, as shown in FIG. 2B, on the front and back surfaces of this substrate 2, for example,
Thick film conductors 4 and 6 made of a system conductor paste are selectively installed by printing and firing according to a specific conductive pattern. That is, a plurality of thick film conductors 4 are installed on the front side of the substrate 2, leaving an area 8 where bare chips 14 are installed. Then, on the front and back surfaces of the substrate 2 on which the thick film conductors 4 and 6 are installed,
Thick film elements such as thick film resistors and thick film capacitors necessary for the circuit are installed.

Next, on the surface of the substrate 2, for example, as shown in FIG. 2C and FIG. A plating resist layer 10 is selectively applied to cover 9, and plating processing portions are selected. In this case, the not-illustrated portions of the thick-film conductors 4 and 6 can be covered, and the plating-treated portions can be selected as necessary.

Next, the thick film conductors 4 and 6 of the substrate 2 on which the plating resist layer 10 is installed are coated with a conductive film 12 by electroless plating, electrolytic plating, etc.
will be installed. For example, Cu as a conductive film.
To form a film, the thick film conductors 4 and 6 are immersed in a Cu plating solution selected for plating, and as shown in FIG. 12 are selectively installed. A bonding pad portion 9, which is not plated, is formed at the end of the thick film conductor 4.

By the way, when Ag-Pd conductor paste is used for the thick film conductors 4 and 6, the plating resist layer 1
Since the exposed Pd acts as a catalyst for Cu, Cu effectively adheres to the thick film conductors 4 and 6, and the conductive film 12 made of the Cu film is efficiently formed. In this case, the plating thickness of the Cu film is set arbitrarily.

Then, the substrate 2 on which such a conductive film 12 is installed is immersed in a stripping solution for stripping the plating resist layer 10, and the plating resist layer 10 is stripped off. Therefore, the plating resist layer 10
It is necessary to consider the stripping process and select the resist material in relation to the stripping solution.

Next, the plating resist layer 10 is removed from the installation area 8 and the bonding pad portion 9 of the thick film conductor 4, and the bare chip 14 as a circuit element is bonded to the installation area 8, as shown in E of FIG. Agent 1
6 will be installed.

Next, as shown in FIG.
A conductor wire 20 is connected between the electrode portion 18 of No. 4 and the bonding pad portion 9 set on the thick film conductor 4 by welding.

Next, as shown at G in FIG.
A resin coat 22 is installed to cover the conductive film 12, and the resin coat 22 is set in a range that covers the area where the conductive film 12 is installed. As a result, the bonding pad portion 9, which is the exposed portion of the thick film conductor 4, is protected.

Next, a solder resist layer 24 is selectively formed leaving the soldered parts etc., and the thick film integrated circuit shown in FIG. 1 is formed.

By setting the unplated part as the bonding pad part 9 at the end of the thick film conductor 4 in this way, the conductor part containing Ag and Pd is exposed, and then the conductor wire 20 can be made of gold wire or When aluminum wire is used, special techniques unlike Cu coatings are not required, making welding easier, simplifying welding work and shortening welding time.

In this thick film integrated circuit manufacturing method, even if the circuit pattern is divided in the middle, the conductive film 1
When electroless plating is used to form conductor 2, there is no need to apply a current, so there is an advantage that the conductive film 12 can be uniformly formed on the thick film conductors 4 and 6. If there is continuity in the circuit pattern or if electrical connection is possible to the circuit pattern on which the conductive film 12 is to be formed, it is also possible to use electrolytic plating, and similarly the conductive film 12 can be formed. You can also. It is also possible to use electrolytic plating and electroless plating together.

In the embodiment, a case has been described in which a conductive film 12 made of Cu is installed on the thick film conductors 4 and 6 using a conductive paste containing Ag and Pd. This method can also be applied to the case where a conductive film other than a Cu film is installed on a thick film conductor.

Furthermore, although the embodiments have shown examples in which bare chips are used as circuit elements, the present invention can also be applied to cases where elements other than bare chips that require wire bonding processing are used.

〔Effect of the invention〕

According to the thick film integrated circuit of the present invention, since the conductive film is provided on the thick film conductor installed on the substrate, the resistivity of the conductor circuit can be reduced by the conductive film, and the conductive The thick film conductor can be protected by the protective film, and deterioration over time such as solder erosion of the thick film conductor can be prevented.

In addition, if a conductive film made of Cu is installed on a thick film conductor using a conductive paste containing Ag and Pd,
When soldering is installed, it is possible to prevent the diffusion of Sn in the solder to the thick film conductor and the diffusion of Ag in the thick film conductor to the solder, protect the solder and the thick film conductor from deterioration over time, and improve the reliability of the integrated circuit. You can increase your sexuality.

According to the method for manufacturing a thick film integrated circuit of the present invention, a resist layer is provided that covers a part of the thick film conductor installed on the substrate, so the portion of the thick film conductor exposed from the resist layer is plated. The conductive film can be easily installed by the following method.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a thick film integrated circuit according to the invention, and FIGS. 2 to 4 are diagrams showing an embodiment of a method for manufacturing a thick film integrated circuit according to the invention. 2... Substrate, 4... Thick film conductor, 9... Bonding pad part (connection part), 10... Plating resist layer (resist layer), 12... Conductive film, 14
...Bare chip (circuit element), 20...Conductor wire.

Claims (1)

[Scope of Claims] 1. A conductive film is selectively installed on a thick film conductor to be connected to an arbitrary circuit element installed on a substrate using a conductor wire, and a portion where this conductive film is not installed and the above-mentioned A thick film integrated circuit in which the conductor wire is connected between circuit elements. 2. The thick film integrated circuit according to claim 1, wherein the thick film conductor is made of a conductor paste containing silver and palladium, and a copper film is provided as a conductive film on the thick film conductor. 3. A resist layer is installed at the connection part set on the thick film conductor to be connected to any circuit element installed on the board using a conductor wire, and a plating process is applied to the thick film conductor exposed from this resist layer. Therefore, a conductive film is installed, the resist layer is peeled off, and the circuit element is installed on the substrate, and between this circuit element and the connection part of the thick film conductor from which the resist layer is peeled off. A method of manufacturing a thick film integrated circuit connecting the conductor wires.