JPS6290997A - Thick film printed circuit device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to thick film printed circuit devices such as resistive networks and hybrid ICs.

BACKGROUND OF THE INVENTION In recent years, as thick film printed circuit devices such as resistor networks and hybrid ICs have become smaller and thinner, the circuit patterns of these types of printed circuit devices have become increasingly dense. The electrode patterns constituting this type of printed circuit device were conventionally made of silver, but with the increase in density, there was a problem in durability against migration, and palladium Pd
Electrode patterns made of silver-palladium containing i have become common.

The structure of the printed circuit pattern of this type of thick film printed circuit device will be explained below with reference to FIG.

FIG. 4 shows a printed circuit pattern of a conventional resistor network, in which 1 is a wiring board made of a material such as ceramic or alumina, and 02 is the wiring board 1 on which an electric circuit is provided on the surface. With an electrode pattern 2 made of silver palladium formed by screen printing and baking on top,
Adjacent electrode portions are provided at intervals of about one word. 3
is a resistance pattern 3 made of a ruthenium-based resistance material formed on the wiring board 1 by screen printing and baking to overlap a part of the electrode pattern 2, and is connected to the electrode part of the electrode pattern to form an electric circuit. do. The resistor network having the above-mentioned configuration is mounted on a printed circuit board with the terminal 4 shown in FIG. 3 attached, the entire exterior coated, and a required voltage applied to each electrode portion at a timely manner.

Problems to be Solved by the Invention However, in the above structure, when the electrode pattern is formed of gold and silver, when the circuit device operates, a potential difference is generated between the electrodes formed on the electrode pattern at a pitch of about one song. , a direct current electric field is formed, and migration oxidation due to mug ionized by moisture on the surface area of the wiring board 1 is likely to occur. To prevent this, the electrode pattern must be formed from a silver-palladium alloy containing palladium. Palladium in silver-palladium alloys is usually 15
~25 wt% is added, and the cost is about 4 to 5 times that of silver, making it a major issue in reducing the cost of this type of thick film printed circuit device, which has a high material weight in the manufacturing cost. Ta.

The present invention solves these conventional problems, and its entire purpose is to reduce the amount of silver palladium used.

Means for Solving the Problems In order to solve the above problems, in the present invention, the portion of the electrode pattern where a potential difference occurs between the electrodes is made of silver palladium, and the remaining electrode pattern is made of the above silver palladium pattern. It is made of silver and overlaid on top of it.

By forming silver-palladium electrodes in the areas where a potential difference occurs between the electrodes of the electrode pattern made of active silver, durability against migration is increased, and by forming silver-palladium electrodes in areas where a potential difference occurs between the electrodes, the areas where no potential difference occurs are formed using silver-palladium '/i-'A. By forming it with silver, which is inexpensive, the amount of silver-palladium used can be reduced, and the material cost can be significantly reduced.

Embodiments Embodiments of the thick film printed circuit device according to the present invention are shown in FIGS. 1 to 3.
This will be explained using figures.

Figure 1 shows an example of the electrode pattern of the resistive network.As shown in Figure 1, adjacent electrode parts 25Li silver palladium are printed and fired to create a potential difference in the electrode pattern. 0 The ratio of palladium wt% of silver palladium is 15 to 25%.
The configuration of the resistor pattern 3 is the same as that of the conventional example.

With the above structure, the amount of silver palladium used can be reduced from the conventional 60%.
%, and by making the remaining 40% of silver, the material cost can be significantly reduced.And when making it into a finished product as a resistor network,
As shown in FIG. 2, the terminals 4t are connected to the electrode portions 2IL, respectively, and the entire structure is covered with resin 6, thereby producing a completed product.

Next, other embodiments of the present invention will be described.

FIG. 3 shows another embodiment. In this embodiment, the outer periphery of adjacent electrode portions 2C where a potential difference occurs in the electrode pattern is printed with silver-palladium.

The central part 2d of the electrode part 2c whose outer periphery is formed of the silver-palladium and the remaining electrode part 2b are formed by printing and firing the connecting parts overlapped with silver. The palladium wt% of silver palladium and the structure of the resistance pattern 3 are the same as in the first embodiment.
%, resulting in a significant reduction in material costs.

Effects of the Invention According to the present invention, as the electrode pattern of this type of thick film printed circuit device becomes more dense, the electrode pattern was made of all silver palladium due to the durability problem of silver migration. By forming a silver-palladium electrode in the part where a potential difference occurs between the electrodes of the electrode pattern,
The amount of silver-palladium used, which is 4 to 5 times as expensive as silver, can be significantly reduced, and material costs can be reduced.

In addition, to form the electrode pattern, two types of silver and silver palladium are used.
However, the material cost of the electrode pattern in thick film printed circuit devices is much higher than the manufacturing cost, and the number of man-hours increases. Significant cost reductions are also possible. Furthermore, the part where the potential difference occurs can be made of silver palladium, and the remaining part can be made of silver with a sheet resistance of 0 to 0 compared to the molecular c silver palladium, so if the pattern width of the silver part is made of silver palladium. This type of thick film printed circuit device has a wide range of industrial applications due to its increased density.

[Brief explanation of drawings]

FIG. 1 is a plan view of a thick film printed circuit device according to an embodiment of the present invention, FIG. 2 is a partially cutaway perspective view of the device completed as a resistor network, and FIG. 3 is a plan view of a thick film printed circuit device according to another embodiment of the present invention. A plan view of a thick film printed circuit device, FIG. 4 is a plan view of a conventional thick film printed circuit. 1...Wiring board, 2a, 2b, 2c...
・Electrode part, 3...Resistance pattern. Name of agent: Patent attorney Toshio Nakao and 1 other person・ku ku - Usage Height h ku to ku Tsuzuka Jo

Claims (1)

[Claims] A thick film printed circuit device that has an electrode pattern made of silver, and the portion of the electrode pattern where a potential difference occurs is made of silver palladium.