JPH043991A - Formation of wiring conductor of thick film integrated circuit - Google Patents

Abstract

PURPOSE:To obtain low impedance of a wiring conductor by forming a circuit pattern on the surface of a substrate by conductor paste containing an organic metal compound and firing this to form a first conductor layer followed by forming a second conductor layer thereon by electroless plating. CONSTITUTION:A circuit pattern is formed on the surface of a substrate 2 of conductor paste containing an organic metal compound, that is, of resinate paste 4 by screen printing or the like. Next, this resinate paste 4 is fired to form a first conductor layer 40. When resinate paste is fired, the film thickness of the obtained conductor 40 becomes less than 1/10 of the film thickness owned by the resinate paste 4 at the time of printing. Next, conductors of copper, nickel are plated to form a second conductor layer 6 on the conductor layer 40 by electroless plating treatment. As a result, a wiring conductor 8 consisting of the conductors 40 and 6 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for forming a wiring conductor for a thick film integrated circuit, which is used for forming a wiring pattern of a thick film integrated circuit into a composite conductor.

[Conventional technology]

Conventionally, in thick film integrated circuits, a circuit pattern is formed by printing on the surface of a substrate using Ag paste or Ag/Pd paste as a conductor paste forming a lower layer conductor, and then copper plating is applied to the upper layer conductor. The impedance of the wiring conductor is reduced by combining the lower layer conductor, which is the base of the upper layer conductor, and the upper layer conductor on the surface of the lower layer conductor.

[Problem to be solved by the invention]

By the way, such a composite wiring conductor process is nothing but an attempt to reduce impedance by using a composite conductor, but the lower layer conductor, which is the base for the upper layer conductor, functions as a bonding means to the board on which the upper layer conductor is installed. It is something that has. In other words, it is no exaggeration to say that if copper plating can be performed directly on the board, there will be no need for a lower layer conductor, and if the upper layer conductor is copper, the lower impedance of the wiring conductor will be ensured by the upper layer conductor. Become.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for forming a wiring conductor for a thick film integrated circuit, in which a lower layer conductor is formed thinner to form an upper layer conductor, thereby achieving lower impedance.

[Means to solve the problem]

That is, the method of forming a wiring conductor for a thick film integrated circuit according to the present invention involves forming a circuit pattern on the surface of a substrate (2) using a conductor paste (resinate paste 4) containing an organometallic compound;
After the conductor paste is fired to form the first conductor layer (40), the second conductor layer (6) is formed on the first conductor layer by electroless plating. .

[For production]

When the second conductor layer is formed by electroless plating, the first conductor layer, which is the lower conductor, acts as a catalyst during the plating of the second conductor layer. therefore,
The first conductor layer does not need to be thick; it is sufficient to provide conditions that allow the second conductor layer to be installed.

Therefore, if a conductor paste containing an organic metal compound is used for the first conductor layer, after firing, the metal density will be higher than that of conventional conductor pastes, and the film thickness will be thinner. It works better as a catalyst,
Precipitation of the plating layer becomes easier. Therefore, if a second conductor layer is formed by electroless plating on a first conductor layer formed of a conductor paste containing an organometallic compound, a composite conductor consisting of the first and second conductor layers can be easily formed. This reduces the amount of conductive paste made of conventional noble metals, and also reduces the impedance of the wiring conductor, resulting in a circuit pattern with high reliability.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.

FIG. 1 shows an embodiment of the method for forming a wiring conductor for a thick film integrated circuit according to the present invention.

As shown in FIG. 1A, a flat substrate 2 is formed of an insulating material such as alumina porcelain.

Next, as shown in FIG. 1B, a circuit pattern is formed on the surface of the substrate 2 using a conductor paste containing an organic metal compound, that is, a resinate paste 4, by screen printing or the like.

Next, this resinate paste 4 is fired, and it becomes (
As shown in C), a first conductor layer 40 is formed. When the resinate paste 4 is fired, the organic chains in the resinate paste 4 are removed due to the firing, so that the thickness of the conductor layer 40 obtained by the resinate paste 4 is 1/1 of the thickness of the resinate paste 4 during printing. Becomes 10 or less.

Next, copper,
A conductor such as nickel is plated to form a second conductor layer 6 as shown in FIG. 1(D).

As a result, wiring conductor 8 consisting of conductor layer 40.6 is formed.

As shown in FIG. 2, the wiring conductor 8 obtained by such a formation method has a resistance r1 of the conductor layer 40 as a lower layer conductor and a resistance r2 of the conductor layer 6 as an upper layer conductor.
The resistance r of the wiring conductor 8 is r,
・rz/(r+10rz), and the magnitude relationship is r
Since <r, , r<r2, the impedance can be reduced.

When Resinate Paste 4 is used, the metal density after firing is higher than that of conventional conductor pastes, so it acts more as a catalyst when forming plating, and prevents the precipitation of the plating layer. It is extremely effective as it is easy to fabricate, and moreover, since the film thickness can be reduced, the amount of metal used can be reduced, manufacturing costs can be reduced, and the overall film thickness of the wiring conductor 8 can be reduced. In this way, the wiring conductor 8 formed with a thin film thickness can not only lower impedance but also prevent problems such as solder cracking and migration when solder is attached.

Furthermore, the resinate paste 4 can be printed using a printing method similar to that used for conventional conductor pastes, and the use of the resinate paste 4 does not require changes to equipment.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to reduce the impedance of the wiring conductor and reduce the manufacturing cost by reducing the amount of metal used. If resin paste is used as the conductor paste containing an organometallic compound, After the firing process, the metal density is higher than that of conventional conductor paste, so it acts as a catalyst when forming plating, making it easier to deposit a coating layer, thereby increasing the reliability of the circuit pattern. can.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the method of forming a wiring conductor for a thick film integrated circuit according to the present invention, and FIG. 2 is a diagram showing an equivalent circuit of the wiring conductor shown in FIG. 1. 2... Substrate 4... Resinate paste (conductor paste containing an organic metal compound) 6... Second conductor layer 8... Wiring conductor 40... First conductor layer non-first conductor layer ship

Claims (1)

[Claims] A circuit pattern is formed on the surface of the substrate using a conductor paste containing an organic metal compound, and this conductor paste is fired to form the first
1. A method for forming a wiring conductor for a thick film integrated circuit, the method comprising forming a second conductor layer on the first conductor layer by electroless plating.