JPH01303790A - Ceramic printed wiring board and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve a ceramic printed wiring board in accuracy and characteristic by a method wherein a thick film resistor layer and a conductor layer are laminated on a terminal section of a thick film resistor layer and the terminal section is roughened, and a conductor layer constituting metal is diffused into the thick film resistor layer. CONSTITUTION:A thick film resistor layer is formed on a ceramic board, which is covered with a chemical resistant protective insulating layer except the terminal section of the thick film resistor layer, the surface of the terminal section is treated to be rough and then a conductor layer is formed thereon through a wet plating method. Next, a thick film resistor layer and a conductor layer are laminated on the terminal section, and at least the laminated part is subjected to a heat treatment at a temperature of 150 to 900 deg.C. By these processes, a conductor pattern can be finely and accurately formed out of a plating metal, especially, a copper plating without deteriorating a thick film resistor in an intrinsic characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a ceramic printed wiring board having high precision and high characteristics, and a method for manufacturing the same.

(Prior technology) A ceramic printed wiring board and its manufacturing method using a wet plating method, which uses a thick film resistor (layer) and a plated conductor (layer).
Attempts to combine the two have already been proposed. For example, after forming a resistor layer using a thick film firing paste, printing a glass paste containing palladium on the terminal part and then firing it, and covering the terminal part with a photosensitive polyimide layer as an insulating layer and a plating resist layer, leaving the terminal part. A method of forming a conductor layer by electroless copper plating is known.

(Problem to be Solved by the Invention) If a method for manufacturing a ceramic printed wiring board using a wet plating method is applied to a substrate on which a thick film resistor layer is formed, there will be problems in the wet plating process. The resistor layer is attacked by the processing chemicals, and the electrical characteristics of the resistor are significantly deteriorated. Furthermore, if a resistor is to be formed after forming a conductor layer by wet plating, for example, if the resistor is formed by thick film firing paste, the conductor layer will also be exposed to temperatures of 800°C or higher. , which impairs the various properties of the conductor. Further, when a glass layer containing palladium is interposed in the terminal portion of the resistor as in the above example, there is a drawback that the resistor is accompanied by an increase in current noise. For this reason, it is preferable to deposit a conductive metal layer directly on the terminals of the resistor, but the surface of the resistor is extremely smooth, and it may be difficult to obtain terminal adhesion that can withstand thermal shock tests, etc. It had problems such as poor electrical characteristics.

(Means for Solving the Problems) The present inventors have arrived at the present invention as a result of studies aimed at solving the problems of the prior art and obtaining a ceramic printed wiring board with high precision and high characteristics. That is, the present invention provides a ceramic printed wiring board in which at least a thick film resistor layer and a conductor layer formed by wet plating are arranged on a ceramic substrate. A ceramic printed wiring board characterized in that a conductor layer and a conductor layer are laminated, the terminal portion is surface-illuminated, and the metal constituting the conductor layer is diffused into the thick film resistor layer. In addition, after forming a thick film resistor layer on a ceramic substrate, the parts other than the terminals of the thick film resistor layer are covered with a chemical-resistant protective insulating layer, and one end of the thick film resistor layer is subjected to surface roughening treatment. , then forming a conductor layer using a wet plating method, laminating a thick film resistor layer and a conductor layer in a terminal portion, and heat-treating at least the laminated portion at 150° C. to 900° C. This is a method for manufacturing a printed wiring board.

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

The thick film resistor layer in the present invention is, for example, R7IO2 type, ruthenate pyrochlore type oxide type, nitrogen fired type L-B
It is formed by printing a thick film firing type resistor paste of E type and tin oxide type on a ceramic substrate-L and then firing it under appropriate conditions.

The chemical-resistant protective insulating layer used to cover areas other than the terminal portions of the resistor in the present invention is selected from thick-film sintered insulator pastes and resin compositions.

Wet plating in the present invention refers to copper, silver, platinum, platinum 1
+4 refers to electroless plating of gold, ruthenium, nickel, cobalt, etc., and/or electroplating using these as the lower layer.

Mechanical and/or chemical surface roughening of the edge 1 of the present invention means that the adhesion between the plated conductor and the thick-film resistor (laminated portion) is reduced by 1-1, and the surface roughening is performed by heating. Mechanical roughening is intended to withstand reliability tests such as Ij Drop for 1 minute.
This refers to physically roughening the surface of the end 1 by, for example, spraying a relatively fine powder such as ceramic powder onto the terminal portion of the resistor.

Chemical roughening refers to a method of forming pores on the surface of the terminal portion of the resistor using an aqueous solution or molten salt of a fluorine compound, an acid or an alkali compound. Although each of the above-mentioned surface roughening methods shows good terminal adhesion even in the r portion, higher terminal adhesion can be obtained by further performing chemical roughening after mechanical roughening. At this time, the surface roughness of the terminal part is 0.05 to 3 in R1.
．． 0 μm, preferably 0.1 to 1.0 μm.

In the present invention, between the conductor layer and the thick film resistor layer that are joined at the terminal part, the metal of the conductor layer is diffused into the thick film resistor layer, which causes noise generation at the connection part. Since the two-layer structure as a source and barrier layer is eliminated, it is thought that an ideal terminal structure will be obtained, and in order to achieve such a structure, it is necessary to heat-treat at least the joint part (laminated part). Become.

The heat treatment in the present invention may be performed at any stage after forming the conductor on the resistor I]. Heating conditions are temperature 150
°C or higher - L 900"C or higher, preferably 200"C or higher
L: 600°C or higher, 1 portion per hour: 15 hours or less,
Preferably, the time required for 5 fractions is 1-2 hours or less. The heat treatment atmosphere is not particularly limited, and includes air, an inert atmosphere, a reducing atmosphere, and the like.

Ceramic substrate is the method for obtaining the product of the present invention! - A thick film resistor layer is formed on (a), and the resistor layer other than the terminal portion is resistant to i! Ii! Coating with an acidic protective insulating layer (0), coating the terminal part with an acidic protective insulating layer (c), forming a conductor layer by wet plating (d), and coating the laminated resistor layer and conductor layer at the terminal part (1).
The order of heat treatment at 50° C. to 900° C. is preferable ((e)), but the order of (b) and (c) may be reversed.

(Examples and Comparative Examples) *(Comparative Example 1) A vertical 50.8 mm containing 96% alumina. ．． 1 side 50.
A white ceramic substrate having a thickness of 8 m −1 and a thickness of 0.835 −=1 was immersed in molten caustic soda maintained at 340° C. for 10 minutes to appropriately roughen the substrate surface. Then, llj, id
Thick film, fired resistor paste #6829 (sheet resistance: lKΩ/mouth) [1]
(Japan LTI) was coated in a desired pattern using a screen printing method, and 850
C. for 10 minutes (total 35 minutes) in air to form a resistor layer. #9137[D
(upont Jal)anLT+), 1. Apply a thick-film sintered glass paste for resistor protection by screen printing to cover the resistor surface and wall, leaving only the resistor terminals, and heat at 550°C for 2 minutes (total 20 minutes) in air. The width of the resistor layer after firing is 1.0
mm length 1.5 mm, thickness 10 μm, and the shape of the glass insulating layer after firing is width 1.5 mm. Olen, length 1.5m, thickness 10
μm, forming a 1-shape with the resistor layer, and 250 μm1] at both ends of the resistor layer serving as the resistor terminal portion are not covered with a glass insulating layer.

1°, on the substrate after forming the resistor layer and protective insulating layer,
A small plating conductor circuit pattern was formed on the terminal portion of the resistor by a semi-additive method.

Specifically, first, the entire surface of the substrate was coated with electroless steel plating. Electroless steel plating is PTH process 4[5hil
) leV Far East Co., 1.0μm
No. 1! ! (An electrolytic copper plating film was obtained. After electroless steel plating, this substrate was heat-treated at 400°C for 10 minutes in a nitrogen atmosphere. Furthermore, a negative plating resist was applied to the circuit using a photosensitive dry film. A pattern was formed, and electrolytic copper plating was deposited to a thickness of about 1.0 μm. After the electrolytic copper plating, the resist was separated by 211 cm, and the thin electrolytic steel plated portion was removed with an etching solution of 0.1 MH2O210, 1MH2SO4. .

For electrical properties, sheet resistance, current noise, and temperature coefficient of resistance were measured. Initial electrical properties and thermal shock test (immersed in -55°C trichloride for 5 minutes i:j-+ chamber/!111O seconds → soaked in +125°C silicone oil for 5 minutes iA i
t't→Heat shock with one cycle of leaving for 10 seconds at room temperature °7
Test) The electrical characteristic values after 25 cycles are shown in Table 1.

(Comparative Example ■) By the same method as shown in Comparative Example I, a thick film resistor protected by a glass insulating layer was formed on a white ceramic substrate with a roughened surface. 500 m e s h over the entire surface of this board
a-Alumina powder at a pressure of 1 kg/cya, 0.5
Spray on the shuttle to perform mechanical lljing, and further 50°
After immersion in a 4M NaOH aqueous solution of C for 30 minutes and ultrasonic cleaning in pure water, a plated conductor circuit pattern was formed in the same manner as in Comparative Example I. Table 1 shows the results of the initial electrical properties and the electrical properties after 25 cycles of the thermal shock test.

*(Example I) By the same method as shown in Comparative Example I, a thick film resistor protected by a glass insulating layer was formed on a white ceramic substrate with a roughened surface. This substrate was placed in a 4M NaOH aqueous solution at 50°C for 3
Soak for 0 minutes and soak in pure water? After cleaning, a plated conductor circuit pattern was formed by the same method as shown in Comparative Example I. During the process 1 of forming a plated conductor circuit, 1! (After electrolytic copper plating, at 400°C for 110 minutes in a nitrogen atmosphere. The initial electrical properties and the electrical properties after 25 cycles of the thermal shock test are shown in Table 1.

*(Example ■) A resistor protected by a glass insulating layer was formed on a white ceramic substrate with a 11-surface layer by the same method as shown in Comparative Example ■. Mechanical roughening was performed by applying 500 mesh α-alumina powder to the entire surface of the substrate at a pressure of 1 kg/Cra for 0.5 seconds, and after ultrasonic cleaning in pure water, the same method as shown in Comparative Example I was performed. A plated conductor circuit pattern was formed. During the process of forming a plated conductor circuit, heat treatment was performed at 400° C. for 10 minutes in a nitrogen atmosphere after electroless copper plating.

Table 1 shows the results of the initial electrical properties and the electrical properties after 25 cycles of the thermal shock test.

(Example ■) In the same manner as shown in Comparative Example I, a resistor protected by a glass insulating layer was formed on a white ceramic substrate with a roughened surface. 500mesh α-alumina powder was applied on the entire surface of the substrate at a pressure of 1 kg/CIJ for 0.5 seconds to perform mechanical molarization, and the substrate was immersed in a 4M NaOH aqueous solution at 50°C for 30 minutes, and super-sintered in pure water. After 7-wave cleaning, a plated conductor circuit pattern was formed in the same manner as in Comparative Example I. During the plating conductor circuit formation process, power! (After electrolytic steel plating, heat treatment was performed at 400° C. for 10 minutes in a nitrogen atmosphere. Table 1 shows the initial electrical properties and the results of the electrical properties after 25 cycles of the thermal?jjfP test.

Table 1 Measured values of comparative examples and examples are average values of n = 20 (Effect of the invention) By implementing the present invention, the conductor pattern can be made into a plated conductor without damaging the original characteristics of the thick film resistor. In particular, the ability to form finely and precisely with copper plating is extremely useful for improving the precision and characteristics of ceramic printed wiring boards.

Claims (2)

[Claims] (1) In a ceramic printed wiring board in which at least a thick film resistor layer and a conductor layer formed by wet plating are arranged on a ceramic substrate, the thick film resistor layer is connected to the terminal portion of the thick film resistor layer. 1. A ceramic printed wiring board comprising: a conductor layer laminated thereon; the terminal portion thereof having a roughened surface; and a metal constituting the conductor layer being diffused into a thick film resistor layer. (2) After forming a thick-film resistor layer on a ceramic substrate, cover the thick-film resistor layer other than the terminal portion with a chemical-resistant protective insulating layer, subject the terminal portion to surface roughening treatment, and then A method for manufacturing a ceramic printed wiring board, comprising forming a conductor layer using a wet plating method, laminating a thick film resistor layer and a conductor layer in a terminal portion, and heat-treating at least the laminated portion at 150°C to 900°C. .