JPS61185995A - Making of circuit board with resistor - 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] [Technical field of invention 1 The present invention relates to a method for manufacturing a circuit board with a resistor.

[Prior Art] FIG. 2 is an explanatory diagram of a circuit board with a resistor formed by a conventional manufacturing method. In the figure, (1) is an inorganic insulating substrate, (2) is a conductor, (3) is a resistor, and (4) is an overcoat. Conventional circuit boards with resistors are printed with conductive paste on the inorganic insulating substrate (1). After that, it is fired, then a resistor paste is printed and then fired, and then a glass paste is printed and then fired.

Materials for inorganic insulating substrates include alumina, silicon carbide,
P& materials such as aluminum nitride and beryllia, and enamel are used.

The paste is printed on an inorganic insulating substrate and then fired.
In addition to functional substances that function as conductors, resistors, and insulators, they are composed of binders such as glass, oxides, or mixtures thereof, and vehicles such as organic solvents and polymers.

As a functional substance for conductive paste, it is normal to U, ^2, ^
Fine metal powders such as g/Pd5Cu and Ni are used.

In addition, the functional material of the resistor paste is PdO/Pd
/＾g-based and ruthenium oxide-based ones are common, and the functional substances for glass paste include titanate bar II (1-J's up 7M!). r'y 1iill
MJ and me? / 3/ Jd 1m field! ? I'm here.

The binder and vehicle other than the functional components affect the bonding strength between the constituent materials after firing, and are therefore appropriately selected depending on the combination of each functional paste.

When manufacturing circuit boards with resistors using conventional methods,
After printing the conductor paste on the inorganic insulating substrate (1) using a conductor screen, it is usually
The conductor (2
) is formed. Next, after printing a resistor paste using a resistor screen, a resistor (3) is formed by firing at 800 to 900°C, and further, after printing an overcoat glass using an overcoat screen, By firing at 400 to 800°C, a circuit board with a resistor can be obtained.

[Problems to be solved by the invention] As mentioned above, in the conventional manufacturing method, the binders contained in each functional paste are melted and sintered with each other, so the adhesion between each material is excellent. Since the optimum firing temperature for each paste is different, it is not possible to fire them all at once, and it is necessary to print each paste and repeat the firing process, which requires precise control of the temperature profile at high temperatures. In addition, since screen printing technology is used to form the conductor, the thickness of 100μ! It is extremely difficult to scale the following fine patterns without leaving a gap, and it is difficult to oxidize even when fired at high temperatures ^u1
^9, it is necessary to use expensive noble metal paste such as Pd, and in order to further reduce the raw material cost, sCu,
When using a base metal paste such as Ni, there is a restriction that it must be fired in an inert or reducing atmosphere such as N2 or N2 to suppress the formation of an oxide film at high temperatures.

The present invention was made in order to eliminate the above-mentioned problems when manufacturing a circuit board with a resistor by the conventional method.

It is something that

[Means for Solving the Problems] The present invention involves printing a resistor paste on an inorganic insulating substrate and then firing it to form a resistor, forming a retaining film on a part of the resistor, Furthermore, the exposed portions of the inorganic insulating substrate and the resistor are simultaneously roughened with strong acid, and then electroless plating or electroless plating and electroplating is performed after catalyst/activation treatment, and then a circuit is formed by pattern etching. This invention relates to a method for manufacturing a circuit board with a resistor.

[Example] In the present invention, a resistor paste is first printed on an inorganic insulating substrate and then fired to form a resistor.

The inorganic insulating substrate and resistor paste used in the present invention are not particularly limited, and the above-mentioned inorganic insulating substrate and resistor paste used in conventional methods can be used.

When using the resistor paste, one that is compatible with the inorganic insulating substrate used can be arbitrarily selected, but a ruthenium oxide paste that has stable characteristics is usually preferred.

The resistor paste may be applied by printing and firing the resistor paste.

In the conventional method, an overcoat glass is provided on the resistor as shown in FIG. 2, but in the present invention, a protective aS is formed on the resistor corresponding to the portion where the overcoat glass is not provided. Thereafter, the exposed portions of the insulating substrate and the resistor are simultaneously roughened using strong acid.

The protective film formed in place of the overcoat glass to cover a part of the resistor improves the heat resistance and moisture resistance of the resistor, and reduces the drift of resistance value, and is made of photosensitive polyimide, Made from organic and inorganic materials such as polyimide, epoxy resin, and triazine, with a thickness of 4 to 20 μm! This refers to a film that is resistant to acids that will be used later in surface roughening treatment.

That protection! Methods for forming the film on the resistor include a spin code method, a roller coating method, a method in which parts other than the resistor are selectively etched using photolithography after tipping, and a screen printing method on the resistor. Although the old bodies are unevenly distributed, they are not limited to these. In cases where dimensional accuracy is required, it is particularly preferable to use a film made of photosensitive polyimide as the retainer IIK.
In cases where dimensional accuracy is not so required, the film having the above-mentioned characteristics may be made of an organic material or an inorganic material, and may be formed by a screen printing method.

The surface roughening treatment is performed by plating the exposed portions of the inorganic insulating substrate and the resistor! This treatment is performed mainly to enhance the adhesion of the film. Examples of strong acids used for this purpose include hepatic acid, chromic acid,
Examples include chromic acid/sulfuric acid, phosphoric acid, phosphoric acid/sulfuric acid, etc., but there are no particular limitations as long as the exposed parts of the inorganic insulating substrate and the resistor can be roughened as desired.The processing conditions using the processing liquid are as follows. This can be determined as appropriate depending on the substrate used, the resistor paste, etc. In the present invention, after the surface has been roughened as described above, in order to form plating nuclei as a pretreatment for electroless plating, The commonly used catalyst/activation process is used to produce normal electroless plating! Alternatively, a plating layer of a desired thickness is formed by electroless plating and electroplating. Thereafter, a circuit board consisting of a fine plated conductor pattern is obtained by pattern etching using a conventional photolithography technique. In addition, a semi-additive method that combines electroless plating and patterned electroplating, a full additive method that performs electroless plating in a pattern, etc. may be used, and if the semi-additive method is used, the etching thickness may be reduced. It can be made thinner, and if a fully additive method is used, there is no need for etching.

The plating film can be formed from not only copper but also any metal by changing the plating solution, and examples thereof include Ni, ^u1^t, and a combination thereof.

Next, the method of the present invention will be explained based on FIG. 1 showing an embodiment thereof.

In Figure 1, (1) is an inorganic insulating substrate and (3) is a resistor.The conventional method is to print a resistor paste on the inorganic insulating substrate (1) and then bake it to form the resistor. The same is true. (5) is a protective film of the resistor formed to expose the terminal portion (3a) of the resistor; (6) and (9) are inorganic insulating substrates obtained by immersion in strong acid (
Rough surface of 1) and rough surface of resistor terminal part (3&), (7
) is a plating film applied after the catalyst/activation process, and (8) is a conductor pattern obtained by etching plating IE (7) by photolithography.

When a circuit board with a resistor is manufactured in this manner, the baking process that requires precise temperature control as in the conventional method is only required for forming the resistor, thereby facilitating manufacturing. As a result, even if an inexpensive base metal is used instead of an expensive noble metal to form the conductor, there is no need to take measures to suppress the formation of an oxide film at high temperatures. Furthermore, since the pattern is formed from the plated conductor using photolithography, it is easy to trace the fine pattern.

Next, the method of the present invention will be explained based on examples.

Example 1 Emitio JI O-JLJ 4 and -1'l A,,
4-J-1+ M#7%/---Ruthenium oxide resistor paste (9 manufactured by Shoei Chemical Co., Ltd.) on the substrate.
0008 series) was screen printed and fired at 850° C. in an infrared belt furnace to form a resistor (3).

The surface roughness Rz of the resistor after firing varies depending on the sheet resistance value of the resistor paste used, but is approximately 0.5
It was in the range of ~1.5 μm.

Next, a photosensitive polyimide (7 Otonis manufactured by Toshiku Co., Ltd.) was applied by spin coating, and after prebaking at 80°C for 30 minutes, exposure and development were performed to expose the terminal portion (3a), and then 150~a o o 11! (5) of the resistor was formed by blowing air at 77°C at a temperature of 100.degree.
The surface was roughened by immersing it in 7th acid for 10 minutes. The surface roughening was carried out by selectively etching the glass components contained in the alumina substrate and the resistor. As a result, the surface roughness Rz of the terminal portion of the resistor and the alumina substrate were both 2 to 3 μR, and no change was observed in the protective film of the resistor during the surface roughening process.

After removing the etching residue by ultrasonic cleaning, the electroless copper plating film is removed by a known catalyst/activation process.
It was formed on the entire surface of the board to a thickness of 1 μm, and then electrolytic copper plating was applied to the thickness required for the conductor.

Next, the plating film (7) was etched using a known photolithography technique to obtain a conductive pattern (8).

According to the method of the present invention as described above, the firing process that requires high-temperature heating is necessary only when forming the resistor, so it is stable with little change in characteristics due to temperature, and is suitable for thick film resistors that are generally widely used. The combination of body and plated conductor can be changed. In addition, photolithography using photosensitive polyimide as a protective film for the resistor not only provides better dimensional accuracy than screen printing, but also produces extremely few pinholes with a film thickness of 4I1 or more. Acts as a protective film to resist moisture and reduce changes over time.
Resistance value l! I-regular trimming is also possible. In addition, since a copper plating film with good conductivity and soldering properties can be formed by etching, fine patterns of less than 100 μl can be obtained extremely easily, and parts can be easily soldered because there is no formation of oxide film. Very good.

Due to the surface roughening, the adhesion between each material, that is, between the inorganic insulating substrate and the conductor, and between the conductor and the resistor, is at a level that poses no practical problem, and sufficient ohmic connection between the conductor and the resistor can be achieved.

[Advantageous Effects of the Invention 1] According to the method of the present invention, the firing step when manufacturing a circuit board with a resistor is performed only once, at the time of forming the resistor. the result,
Manufacturing is facilitated, and a conductor can be formed without using a base metal to suppress the formation of an oxide film. Furthermore, since it can be patterned using photolithography, it can be patterned with a thickness of 100 μm! A circuit board with a resistor having the following fine pattern can be obtained more easily than with conventional manufacturing methods.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a circuit board in each step of the method of the present invention, and FIG. fjIJ2 is an explanatory diagram of a circuit board with a resistor according to a conventional method. (Main symbols in the drawing) (1): Inorganic insulating substrate (3): Resistor (3a): Terminal part of resistor (5): Protection [1I (6): Rough surface of inorganic insulating substrate (7): Plating Membrane (9): Rough surface of resistor terminal part

Claims (1)

[Claims] (1) After printing a resistor paste on an inorganic insulating substrate, baking it to form a resistor, forming a protective film on a part of the resistor, and exposing the inorganic insulating substrate and resistor using strong acid. A method for manufacturing a circuit board with a resistor, characterized in that the surface of the portion is simultaneously roughened, then electroless plating or electroless plating and electroplating are performed after catalyst/activation treatment, and then a circuit is formed by pattern etching.