JPH0228392A - Printed wiring board of ceramic - Google Patents

Abstract

PURPOSE:To obtain a printed wiring board of ceramic having high accuracy and high characteristics and being cheap by arranging a thick resistor layer formed by burning, a thick conductor terminal layer, an insulator layer, and a conductor circuit part formed by electric plating. CONSTITUTION:A thick resistor layer 2 formed by burning, a thick conductor terminal layer 1, and an insulator layer 3, and further a conductor circuit part 4 formed by electric plating are arranged on a ceramic substrate 5. By providing the insulating layer 3 on the thick resistor layer 1, the resistor layer 2 can be protected from erosion by strong alkaline and strong acid chemicals used for wet plating process. Hereby, without losing the essential characteristics of the thick resistor 2, a conductor pattern 4 can be formed finely and very accurately by plating conductor, especially, by copper plating, and high accuracy advancement and high characteristics advancement of the printed wiring board of ceramic can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application 1f) The present invention relates to a ceramic printed wiring board with high precision and high characteristics.

(Prior Art) Efforts have already been made to combine a thick film fired resistor layer with a plated conductor circuit section in a ceramic printed wiring board using a wet plating method. For example, after forming a thick film resistor layer by firing, a glass paste containing palladium is printed on the end r part of the thick film resistor layer in contact with the conductor circuit part and then fired to form the end r part, and the photosensitive A method is known in which polyimide is coated as an insulating layer and a plating resist, and a conductor circuit portion is formed by chemical plating. Further, JP-A-49-82966 discloses a method of forming thick film conductor pads, printing and firing a resistor between the conductor pads, and forming a conductor circuit by chemical plating.

(Problems to be Solved by the Invention) When producing a ceramic printed wiring board using a wet plating method, if you try to use it as is on a board containing thick film resistors, the resistor will be damaged by the treatment chemicals included in the wet plating process. is affected, and the hypochondriacal properties of the resistor are significantly deteriorated.

In addition, if a resistor is to be manufactured after the conductor circuit is formed, for example, if the resistor is a thick film fired resistor, the temperature is 800°C.
Here it is! Since the 1J degree is required to be increased, if the previously formed wet-plated conductor is a copper conductor, various properties of the conductor will be impaired. Further, as described above, when a glass layer containing palladium is interposed in the terminal portion of the resistor, there is a drawback in that the resistor, in particular, is accompanied by an increase in current noise. Also, in ``Unexamined Japanese Patent Publication No. 49-82988J,
Since the resistor-1- is covered with a non-activated coating film, the laser trimmability is extremely poor, and since the conductor part is formed by chemical plating, it takes a lot of time to obtain the desired film thickness. However, the physical properties of the film are inferior to those of electroplated films.

(Means for Solving the Problems) As a result of intensive studies to solve the problems of the conventional technology and to produce a ceramic printed wiring board having high precision and high characteristics, the present inventors found that a thick film on a ceramic substrate A conductor terminal layer, a thick-film resistor layer, and an insulator layer for protecting the thick-film resistor layer are formed by firing, and then, for example, chemical plating is applied to the entire surface of the substrate, and a part of the thick-film conductor terminal or The method of forming a conductor circuit by electroplating to connect all the parts has been found to be a ceramic printed wiring board that has the above-mentioned high precision and high characteristics, and is cheaper because no metal is used for the conductor circuit. I found it.

That is, the present invention provides a ceramic substrate having a thick film resistor layer formed by firing, a thick film conductor terminal, an insulator layer, and a conductor circuit portion formed by electroplating. This is a ceramic printed wiring board with special features.

The ceramic substrate in the present invention refers to an alumina-based substrate,
These are ceramic-based substrates such as aluminum nitride substrates, silicon carbide substrates, and glass-based substrates. Although the ceramic substrate can be used as is, it is preferable to use a ceramic substrate whose surface has been mechanically or chemically roughened in order to improve the adhesion of the plated conductor circuit.

The thick film conductor terminal layer in the present invention refers to a thick film resistor layer,
This is an intermediate terminal layer for connecting the plated conductor circuit part forming the conductor circuit pattern, and is formed using a so-called conductor firing paste, such as silver, palladium, platinum,
It is made of conductive fine powder of gold, copper, nickel, etc., a metal oxide, an organic vehicle, or, if necessary, a small amount of glassy frit, and is formed by printing on a ceramic substrate and then firing it under suitable conditions F. As a method for interposing the thick film conductor terminal layer between the thick film resistor layer and the plated conductor circuit section, examples shown in FIGS. 1 to 3 can be considered, but any method may be used. Further, it is sufficient that a thick film conductor layer is interposed between the thick film resistor layer and the plated conductor circuit, and the present invention is not limited to the example shown in the figure. The thick film resistor layer is made of, for example, silver,
Palladium, ruthenium compound, Ta, Sn+ In
oxide, conductive fine powder such as L a Bo, glassy frit, metal oxide and organic vehicle, and a resistor layer at a position connected to a part or all of the Y-layer at the end of the thick film conductor. was printed and fired under appropriate conditions. The insulator layer is a chemical-resistant layer that protects the thick film resistor layer and is a thick film insulator. A thick film insulator is printed on the layer and fired under appropriate conditions.

Chemical plating in the present invention refers to plating of copper, silver, platinum, platinum metal, gold, ruthenium, nickel, and cobalt. Electroplating refers to the electroplating of copper, nickel, gold, chromium, zinc, etc. The method for forming the conductor circuit is the semi-additive method, in which conductor circuits are formed by chemically plating the entire surface of the board, then forming a negative plating resist, and then electroplating. attached,
There is a subtract method in which a positive etching resist is then formed and the non-circuit portion is etched away to form a conductor circuit, but either method can be used.

The present invention has achieved II) functionality due to (1) thick film resistor layer i.
- The resistor layer is protected from corrosion by high-temperature strong alkali and strong acid chemicals used in the wet plating process by providing an insulator layer on the plated conductor layer forming the conductor circuit section. It is conceivable that a thick film conductor end T-layer is interposed in the connection of the film resistor layer to create an ideal end r structure. (3) The insulator layer is obtained by firing and is suitable for laser trimming.

(Example) Examples will be given to explain the present invention in more detail.
The present invention is not limited in any way by these Examples.

Measurements for performance evaluation were performed using the following method. TCR (temperature resistance coefficient) characteristics: A predetermined circuit pattern is formed, the board is connected to a terminal in a constant temperature chamber, and the inside of the chamber is
The temperature was adjusted to 5° C., and the value at that time was taken as the resistance value, and then the temperature was raised to 125° C., the resistance value at that time was recorded, and the TCR was calculated using the following formula.

Noise (current noise coefficient) characteristics analysis circuit
ch Re5istor-N1se Te5t SET
Measured using 315B.

Example 1 Containing 96% alumina, length: 50.8 mm - width: 50 mm.
8■■, thickness 0.835■ white ceramic substrate 3
The substrate surface was appropriately roughened by immersing it in molten caustic soda maintained at 40° C. for 10 minutes. Next, thick film conductor firing paste (#9601 rESL, Inc.) was used.

'') was applied to the desired location using the screen printing method.
After drying at .degree. C. for 10 minutes, air baking was performed at 900.degree. C. for 10 minutes (35 minutes in total) to form a thick film conductor terminal. The spacing between the thick film conductor terminal layers was set to 1.0■■. Next, a thick film resistor firing paste (R931ONr Shoei Kagaku Kogyo ■) was coated on each thick film conductor terminal layer by screen printing, and dried at 150°C for 10 minutes, and then dried at 850°C for 10 minutes. Air baking was performed for 35 minutes (35 minutes in total). Historically, in order to protect the thick film resistor, thick film insulator firing paste (#9137 r
Dupont Japan LTD, J) was applied by screen printing method, dried at 150°C for 10 minutes,
Thereafter, it was baked in air at 550° C. for 2 minutes (20 minutes in total). The shape of the thick film resistor layer after firing is medium 1.0-n.
, 1.5 mm long and 10 mm thick. The shape of the thick film insulator layer after firing has a width of 1.2. ,,length 1.7. , , thickness is 10IJJa.

After forming the above thick film conductor terminal layer, thick film resistor layer and thick film insulator layer, a plated conductor circuit pattern is formed on the alumina substrate by a semi-additive method so as to become a part of the thick film conductor terminal layer. did. Specifically, first, the entire surface of the substrate was coated with chemical steel plating. Chemical steel plating is performed by PTH process 4 [5hlplay Far East Co., Ltd., 1.
0 chemical steel plating films were obtained. Furthermore, a negative plating resist was formed in a circuit pattern using a photosensitive dry film so as to partially overlap the thick film conductor terminal layer, and electrical steel plating was deposited for about 10 seconds. After electrical steel plating,
Peel off the resist and apply thin chemical steel plating to O, I
M [20210, IM Removed with H2SO4 etching solution. Table 1 shows the measurement results of the electrical properties.

(Example 2) Thick film fired resistor paste (R931O
Nr Shoei Kagaku Kogyo ■'') was applied to desired areas by screen printing, dried at 120°C for 10 minutes, and then air-baked at 850°C for 10 minutes (total 35 minutes). Next, a thick film conductor firing paste (TR-4940r [TI
After drying at 150° C. for 10 minutes, air baking was performed at 850° C. for 10 minutes (total 35 minutes).

Thick film resistor layer to protect the thick film resistor layer] Insulator firing pace) (#9137rDupo
nt Japan LTD, J) by a screen printing method, dried at 150°C for 10 minutes, and then air-baked at 550°C for 2 minutes (total 20 minutes). The shape of the thick film resistor layer after firing is 1.0 ms in width and 1.5 ms in length. ,, 10 doors thick. The shape of the thick film insulator layer after firing is medium 1.
．． 2ml+, length 1. Q+*m, thickness 10-.

1. After forming the thick film resistor layer, the thick film conductor terminal layer, and the thick film insulator layer, the alumina substrate is coated with a part or all of the thick film conductor terminal layer using the semi-additive method as in Example 1. Thus, a plated conductor circuit pattern was formed. The electrical characteristics are shown in Table 1.

(Example 3) A thick film conductor terminal layer was formed by a semi-additive method on an alumina substrate on which a thick film conductor terminal layer, a thick film resistor layer, and a thick film insulator layer were formed by the same method as shown in Example 1. A plated conductor circuit pattern was formed so as to overlap the area. Specifically, first, the entire surface of the substrate was coated with chemical nickel-boron plating.

For chemical nickel boron plating, after catalytically activating the substrate, 1. A chemical nickel-boron plating film of opll was obtained. Further, using a photosensitive dry film, a negative plating resist was formed on a part of the thick film conductor terminal layer to form a circuit pattern, and electrical steel plating was deposited to a thickness of about 10 mm. After electrical steel plating, remove the resist and apply thin chemical nickel-boron plating to O, IM n
It was removed with an etching solution of 2o□10 and LM 112S04. Table 1 shows the measurement results of the electrical characteristics.

(Example 4) A part of the thick film conductor terminal was formed by a subtractive method on an alumina substrate on which a thick film conductor terminal layer, a thick film resistor layer, and a thick film insulator layer were formed by the same method as shown in Example 1. A plated conductor circuit pattern was formed to match the pattern. First, the entire surface of the substrate is coated with chemical steel plating to a coating thickness of 1 μm.
Then, the entire surface was electroplated to obtain a 10.0/f11 thick electrical steel plating film. After that, a positive etching resist was formed on the circuit pattern using a photosensitive dry film, and 0, 1M
The non-conductive circuit portions were removed using an etching solution of H2O210, 1M 112SO4. Table 1 shows the measurement results of the electrical characteristics.

(Comparative Example 1) Thick film fired resistor paste (R9
31ON r Showa Kagaku 1-mata'') was applied in a desired pattern by screen printing method, and then heated at 850°C for 10 minutes (
A resistor layer was formed by firing in air for a total of 35 minutes. Thick film glass paste for protecting the resistor (
#9137 rDupontJapan LTD, J
) was applied by screen printing to cover the resistor surface and wall, leaving the resistor terminals, and heated at 550°C.
It was baked in the air for 2 minutes (total 20 minutes). After firing, the resistor layer has a width of 1.0 mm, a length of 1.5 mm, and a thickness of 10 mm.

The shape of the baking machine for the glass insulating layer is width 1.0-1 length 1.5
It has a thickness of 11 lOu, forms a cross shape with the resistor layer, and 250+tl at both ends of the resistor layer as resistor terminal portions are not covered with a glass insulating layer.

A plated conductor circuit pattern was formed on the substrate after forming the resistor layer and the protective insulating layer by the same semi-additive method as shown in Example 1 so as to overlap the resistor terminal portion. The electrical characteristics are shown in Table 1.

(Comparative Example 2) Thick film resistor firing paste (#6829 rD
upont Japan LTD, J),
Apply it in a desired pattern by screen printing method, and
Air baking was performed at 0° C. for 10 minutes. Next, a thick film palladium glass layer was applied to both ends of the thick film resistor layer by screen printing using a thick film palladium glass firing paste so that
Air baking was performed at ℃ for 10 minutes (total 35 minutes). Historically, insulator firing paste (#
9137rDupont Japan LTD, J
) was applied by screen printing method and heated at 150°C for 10
After drying for a minute, air baking was performed at 550° C. for 2 minutes (20 minutes in total).

The shape of the thick film resistor layer after firing is 1.0 mm in width and 1.5 mm in length.
■-1 The thickness is 10 units. The shape of the thick film insulator layer after firing is Irjl, 2sn+, length 1.0mm, and thickness 10mm. 1- After forming the thick film resistor layer, the thick film palladium/glass terminal, and the thick film insulator layer, a plated conductor was applied to the alumina substrate using the semi-additive method as in Example 1 so as to overlap the thick film palladium/glass layer. A circuit pattern was formed. The electrical characteristics are shown in Table 1.

Table 1 (Effects of the Invention) By carrying out the present invention, conductor patterns can be formed finely and with high precision using plated conductors, especially copper plating, without damaging the original characteristics of thick film resistors. This is extremely useful for improving precision and characteristics.

[Brief explanation of the drawing]

1 to 3 are illustrations (cross-sectional views) of a method for interposing a thick film conductor terminal layer between a thick film resistor layer and a plated conductor circuit. Each symbol in the figure indicates the following content. ■ Thick film conductor terminal layer ■ Thick film resistor layer ■ Insulator layer ■ Plated conductor circuit section ■ Ceramic substrate

Claims (1)

[Claims] (1) In a ceramic printed wiring board in which at least a thick film resistor layer and a conductor circuit section formed by plating are arranged on a ceramic substrate, the thick film resistor layer, the thick film conductor terminal, and the insulator layer are formed by firing. What is claimed is: 1. A ceramic printed wiring board, characterized in that a conductor circuit section formed by electroplating is disposed on the ceramic printed wiring board.