JPH0744084B2 - Electrode structure of electronic parts - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrode structure of an electronic component based on a base electrode formed using a metal organic paste or a conductive thin film as a circuit pattern.

<Prior Art> In recent years, demands for miniaturization, high density, and low cost of electronic components have been increasing more and more from consumers. To meet this requirement, Au and Au / Pt are low cost and have high electrical reliability.
The present inventors have already proposed a technique for forming an electrode part of an electronic component using such a metal organic paste (Japanese Patent Application No. 1-197936, Japanese Patent Application No. 2-117446).

A base electrode portion of a chip resistor, or a lead-out electrode portion for connecting adjacent circuits to each other when a hybrid IC or a resistance network is formed is raised to this electrode portion. When connecting to other conductors of each of these electrode parts, (1) a conductor part is formed of a metal organic paste of the same material on the electrode part formed of the metal organic paste, and the electrode part and the conductor are formed. Structure that directly joins the parts.

(2) Ag of the electrode part formed using the metal organic paste
After covering with a thick film conductor paste such as / Pd, 600 ℃ -850 ℃
Of high temperature to form a thick film conductor, and the thick film conductor and the resistor are joined together.

Etc.

<Problems to be Solved by the Invention> However, as in the conventional case, the electrode portion and the conductor portion are joined,
When immersed in a Sn / Pb / Ag solder bath (250 ° C) for about 10 seconds, in the electrode structure of (1) above, the conductive thin film formed by firing the metal organic paste does not get wet and the solder does not Cracks occur and the conductive thin film dissolves in the solder in the bath. Further, in the electrode structure of (2) above,
Although the solder is wet on the thick film conductor, there is a problem that the solder wettability of 95% or more cannot be secured.

It is also considered to form a Ni plating film on the electrode part to protect the electrode part and subject it to heat treatment at 250 ° C to 350 ° C. However, Ni is weak in heat resistance, so the electrode part due to strain is Not only is the bondability between the electrode and Ni poor, but there is also the drawback that the electrical properties deteriorate due to the diffusion of Ni from the electrode.

The present invention has been made to solve the above drawbacks, and its object is to form an electrode using a metal organic paste.
Electrode structure of electronic parts that has good solder wettability, excellent electrical conductivity and mechanical strength, and ensures the electrical characteristics of the metal organic paste so as to improve the bondability with the conductor portion forming the circuit pattern, etc. To provide.

<Means for Solving the Problems> The present invention has been made in view of the above objects, and the gist thereof is an electrode structure of an electronic component using a metal organic paste, which comprises firing the metal organic paste. , A conductive thin film as a base electrode or a circuit pattern formed on the insulating substrate of the electronic component, and Cr formed on the conductive thin film.
Or a first metal film made of any one of Ti or an alloy in which Ti is combined, and a second metal film made of Cu or an alloy containing Cu as a main component and formed on the uppermost layer of the electrode structure. The electrode structure of the electronic component is characterized in that the first and second metal films are formed by a sputtering method or a vapor deposition method at a low temperature of less than 100 ° C.

Here, as the metal organic paste, Au, Pt or Pd
It is preferable that the organic compound of any one of the above or a combination thereof is made into a paste.

<Operation> One of Cr and Ti forming the first metal film or an alloy in which these are combined has high rigidity against heat,
Moreover, it has excellent adhesion and mechanical strength to the conductive thin film and the insulating substrate thereunder. Further, Cu or an alloy containing Cu as a main component for forming the second metal film is a material excellent in solder wettability as well as conductivity. Therefore, the first and second metal films act to protect the conductive thin film formed by firing the metal organic paste and enhance the mechanical strength and solder wettability.

Further, by forming the first and second metal films at a low temperature of less than 100 ° C., mutual reaction diffusion hardly occurs between the other metal in the lowermost layer and the conductive thin film which is easily diffused. Acts like.

<Example> Of the electrode structures of the electronic component according to the present invention, a hybrid
The electrode structure A of the extraction electrode when forming an IC or a resistance network will be described in the order of steps based on FIG.

First, a conductive thin film 12 forming a circuit pattern is formed on an insulating substrate 10 made of alumina ceramics. The conductive thin film 12 is formed by patterning a gold resinate paste containing gold as a metal organic substance by a screen printing method or a photo-etching method and baking it at a high temperature of about 850 ° C.

Next, a resistor 13 as a thick film element is formed on the conductive thin film 12 at a predetermined position so that both ends thereof overlap. This resistor 13
The pattern is printed by a resistance printing paste such as RuO ₂ series or Pb ₂ Ru ₂ O _6.5 series by a screen printing method and baked at about 850 ° C. Further, a glass coat 14 is applied so as to cover the resistor 13 thus formed to protect the thick film element.

Further, a thin film resistor 15 as a thin film element is formed on the conductive thin film 12 so that both ends thereof overlap. This thin film resistor 15
Is formed by a conventional thin film forming method such as a vapor deposition method or a sputtering method, and patterned by a photo etching method or the like.

Next, when forming a resistance network or the like, extraction electrodes for connecting adjacent circuits to each other are formed. In the formation of the extraction electrode, firstly, at a predetermined position of the conductive thin film 12, the first adhesive made of Cr, which has excellent adhesion to the conductive thin film 12 and the insulating substrate 10, and also has excellent heat resistance and mechanical strength.
The metal film 16 is formed by a sputtering method or a vapor deposition method.
The temperature during formation is about 95 ° C. Further, the first metal film 16 is patterned by an etching method or a lift-off method. Then, the patterned first metal film
16, and secondly made of Cu, which has excellent solder wettability
The metal film 17 is formed by a sputtering method or a vapor deposition method. The temperature during this formation is about 95 ° C. Then, patterning is performed by an etching method or a lift-off method.

The first metal film 16 may be formed of Ti or an alloy of a combination of Cr and Ti in addition to Cr, and the second metal film 17 may be formed of Cu or Cu in addition to Cu. It can also be formed of an alloy containing the main component.

Further, in the electrode structure of the electronic component according to the present invention, the electrode structure B of the base electrode in the chip resistor is
The steps will be described with reference to the drawings.

Nazu, a ceramic chip substrate 20 as an insulating substrate
A pattern of gold resinate paste containing gold as a metal organic material is pattern-printed on both upper ends by a well-known photo-etching method or a screen printing method, and the pair of base electrodes 21 is fired at a high temperature of about 850 ° C. Form. next,
A Ru-based paste is printed on the pair of base electrodes 21 by a screen printing method so that both ends thereof overlap with each other, and is baked at about 850 ° C. to form the resistance film 22.

Next, on the base electrode 21, a first metal film 24 made of Cr, which is excellent in adhesion to the base electrode 21 and the chip substrate 20, and is also excellent in heat resistance and mechanical strength, is formed by a vapor deposition method. The temperature during this formation is about 95 ° C. Thus, by covering the base electrode 21 with the first metal film 24, the measurement probe and the base electrode for trimming
The electrical contact with 21 can be improved, and the disadvantage that the base electrode 21 containing gold is weakly worn can be compensated.

Further, trimming is performed by a well-known method to adjust to a desired resistance value, and the overcoat film 23 for protecting the resistance film 22 at the time of plating treatment performed thereafter and for withstanding various use environments is formed by a well-known method. .

Next, the end surface electrodes 26 and the back surface electrodes are formed on both end surfaces of the chip substrate 20.
After forming 27, the first metal film 24 and the electrodes 26, 27
A second metal film 25 made of a Cu alloy having excellent solder wettability is formed thereon by electroplating, electroless plating, vapor deposition or the like. The temperature during this formation is the same as in electroplating.
The temperature is about 20 to 60 ° C, the electroless plating method is about 60 to 95 ° C, and the vapor deposition method is about 90 to 95 ° C.

The first metal film 24, the first metal film 16,
The second metal film 25 may be formed of Cr or Ti or an alloy thereof, and the second metal film 25 may be formed of Cu or an alloy containing Cu as a main component.

Further, in the present embodiment, the first metal film and the second metal film are continuously laminated, but another metal film is interposed between the first metal film and the second metal film. Even with the inclusion of the above, the same operational effect as the present invention is exhibited.

<Effect> According to the electrode structure of the electronic component of the present invention, the first metal film formed of either Cr or Ti or an alloy of a combination thereof formed on the conductive thin film is the conductive thin film. The second metal film made of Cu or an alloy containing Cu as a main component has excellent conductivity and solder wettability. Excellent material. Therefore, the first and second metal films can protect the conductive thin film formed by firing the metal organic paste, and can improve heat resistance, mechanical strength, solder wettability, and the like. In addition, since the first and second metal films are formed by a sputtering method or a vapor deposition method at a low temperature of less than 100 ° C., Cr, Ti, Cu, etc. are not distorted by heat, and therefore the lowermost layer is formed. Since the adhesiveness between the conductive thin film and the conductive thin film is excellent and mutual reaction diffusion hardly occurs, desired electrical characteristics can be surely obtained, and an electron having high electrical reliability can be obtained. An electrode structure for the component can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view of a circuit board showing an example in which the electrode structure according to the present invention is applied to an extraction electrode, and FIG. 2 shows an example in which the electrode structure according to the present invention is applied to a base electrode of a chip resistor. It is sectional drawing of a chip resistor. A: Electrode structure of extraction electrode, 10 ... Insulating substrate, 12 ...
Conductive thin film, 16 ... First metal film, 17 ... Second metal film, B ... Electrode structure of base electrode, 20 ... Chip substrate (insulating substrate), 21 ... Base electrode (conductive thin film) ),twenty four…
… First metal film, 25 …… Second metal film.

Claims (1)

[Claims] 1. An electrode structure of an electronic component using a metal organic paste, comprising: a base electrode formed on an insulating substrate of the electronic component by firing the metal organic paste; and a conductive thin film as a circuit pattern, A first metal film formed on the conductive thin film, which is made of an alloy of Cr or Ti or a combination thereof, and Cu or Cu
And a second metal film formed on the uppermost layer of the electrode structure, the first and second metal films being formed by a sputtering method or an evaporation method at a low temperature of less than 100 ° C. An electrode structure for an electronic component, which is formed.