JPH04147601A - Electrode structure of electronic parts - Google Patents

Abstract

PURPOSE:To provide an electrode structure excellent in solder wetting and in mechanical strength so as to securely fix a conduct part forming a circuit pattern and the like by forming an electrode using metal organic paste. CONSTITUTION:A title structure comprises a conductive thin film 12 which is formed on an insulting substrate 12 which is formed of electronic parts after burning metal organic paste, a first metal film 16 formed on the conductive thin film 12 and comprising any of Cr, Ni, Ti, Pb or any alloy yielded by combination thereof, and a second metal film 17 comprising any of Cu, Sn or Pb or an alloy yielded by combination thereof and formed on an uppermost layer of the electrode structure. The first and second metal films are formed at a temperature lower than 300 deg.C. For the metal organic paste, there are preferably used a pasty organic compound of any of Au, Pt or Pd or an alloy of combination thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electrode structure of an electronic component based on a conductive thin film formed using a metal-organic paste.

<Conventional Technology> In recent years, demand for electronic components to be smaller, more dense, and lower in cost has become increasingly strong. In order to meet this demand, Au
The present inventor has already proposed a technique for forming electrode portions of electronic components using a metal-organic paste such as
).

This electrode part may be used as the base electrode part of a chip resistor, or when configuring a hybrid IC or resistance network,
There are lead-out electrode parts and the like for connecting adjacent circuits to each other. When connecting each of these electrode parts to another conductor part, (1) Form a conductor part with a metal organic paste made of the same material on the electrode part formed using the metal organic paste, and connect the electrode part and the conductor part. A structure in which the parts are directly joined.

(2) Electrode part formed using metal-organic paste
After covering with thick film conductor paste such as g/Pct.

A structure in which a thick film conductor is formed by firing at a high temperature of 600° C. to 850”C, and this thick film conductor and the conductor portion are bonded.

etc.

<Problem to be solved by the invention> However, it is difficult to connect the electrode part and the conductor part as in the past,
S n / P b / A g type solder bath (250
℃) for about 10 seconds, in the electrode structure of (1) above, the solder does not wet the conductive thin film formed by firing the metal-organic paste, and moreover, the solder cracks occur and the conductive thin film does not leak into the bath. It will dissolve into the solder inside. Also,
In the electrode structure (2) above, although the solder wets the thick film conductor, there was a problem in that it was not possible to ensure solder wettability of 95% or more. The present invention was made to solve the above drawback. The purpose of this is to create electronic components with good solder wettability and excellent mechanical strength so that electrodes formed using metal-organic paste can be securely fixed to conductor parts forming circuit patterns, etc. The purpose of this invention is to provide an electrode structure.

Means for Solving the Problems The present invention has been made in view of the above objects, and its gist is an electrode structure for an electronic component using a metal-organic paste, which comprises firing the metal-organic paste. , a conductive thin film formed on the insulating substrate of the electronic component; a first metal film formed on the conductive thin film and made of Cr, Ni, or Ti or an alloy of a combination thereof; and Cu.
.

a second metal film formed on the top layer of the electrode structure, the first and second metal films being made of either Sn or Pb or an alloy of a combination thereof; The electrode structure of an electronic component is characterized by being formed at a low temperature.

Here, the metal-organic paste is Au.

It is preferable to use an organic compound of PT or Pd, or an alloy of a combination thereof, in the form of a paste.

<Function> Any one of Cr, Ni, or Ti, or an alloy of a combination of these, forming the first metal film has excellent adhesion and mechanical strength to the conductive thin film and the underlying insulating substrate. There is. Further, the second metal film is formed (:u, Sn
or Pb or an alloy combining these,
This material has excellent solder wettability. Therefore, these first
The second metal film protects the conductive thin film formed by firing the metal-organic paste and acts to improve mechanical strength, solder wettability, and the like.

In addition, the above-mentioned No. 1. By forming the second metal film at a low temperature of 300° C. or lower, almost no mutual reaction and diffusion occurs between the second metal film and the lowermost conductive thin film.

<Example> Among the electrode structures of an electronic component according to the present invention, an electrode structure A of an extraction electrode when configuring a hybrid IC or a resistor network will be explained in order of steps based on FIG. 1.

First, an insulating substrate made of alumina ceramics.

A conductive thin film 12 constituting a circuit pattern is formed thereon. This conductive thin film 12 is formed by patterning a gold resinate paste containing gold as a metal organic substance by screen printing or photo etching, 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 overlap. This resistor 13 is made by printing a pattern of RuO2-based, Pb2Ru, O,, etc.-based resistance paste using a screen printing method.
Bake at about 50°C. Further, a glass coat 14 is applied to cover the resistor 13 formed in this manner 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 overlap.

The thin film resistor 15 is formed by a conventional thin film forming method such as a vapor deposition method or a sputtering method, and is patterned by a photoetching method or the like.

Next, when configuring a resistor network or the like, lead-out electrodes are formed to connect adjacent circuits to each other. In forming the extraction electrode, first, a first metal film made of Cr, which has excellent adhesion to the conductive thin film 12 and the insulating substrate 10 and has excellent mechanical strength, is applied to a predetermined location of the conductive thin film 12. 16 is formed by sputtering or vapor deposition. Note that the temperature during formation is approximately 90°C to 300°C. Furthermore, this first metal film 16 is etched or lifted.
Create a pattern using the off method. Next, a second metal film 17 made of Cu, which has excellent solder wettability, is formed on the patterned first metal film 16 by sputtering, vapor deposition, or the like. The temperature during this formation is 90°C to 300'C.
That's about it.

Note that the first metal film 16 is made of Ni or T in addition to Cr.
In addition to Cu, the second metal film 17 may be formed of Cu or an alloy of a combination thereof.
It can be formed of n, Pb, or an alloy of a combination thereof.

In addition, among the electrode structures of electronic components according to the present invention, the electrode structure B of the base electrode in a chip resistor is
The process will be explained in order based on the drawings.

First, a ceramic chip substrate 2 as an insulating substrate
A pattern of gold resinate paste containing gold as a metal-organic material is printed on both ends of the base electrode 21 by a well-known photo-etching method or screen printing method, and is fired at a high temperature of about 850° C. to form a pair of base electrodes 21. 0 forming
Next, a Ru-based paste is printed on the pair of base electrodes 21 by screen printing so that both ends overlap,
The resistive film 22 is formed by firing at about 850°C.

Next, a first metal film 24 made of Ni, which has excellent adhesion to the base electrode 21 and the chip substrate 20 and has excellent mechanical strength, is formed on the base electrode 21 by electroless plating. The temperature during this formation is approximately 60°C to 95°C. in this way.

By covering the base electrode 21 with the first metal film 24, the electrical contact between the measurement probe and the base electrode 21 during trimming is improved, and the wear resistance of the base electrode 21 containing gold is improved. This can make up for the drawback of being weak.

Furthermore, the resistive film 22 is trimmed using a well-known method to adjust the resistance to a desired value, and the resistive film 22 is then trimmed to a desired resistance value.
An overcoat film 23 is formed by a known method to protect the device and withstand various usage environments.

Next, after forming end electrodes 26 and back electrodes 27 on both end surfaces of the chip substrate 20, Sn/Pb, which has excellent solder wettability, is placed on the first metal film 24 and each electrode 26, 27.
A second metal film 25 made of an alloy is formed by electroplating, electroless plating, vapor deposition, or the like. The temperature during this formation is approximately 20°C to 60°C for electroplating, approximately 60°C to 95°C for electroless plating, and 90°C to 90°C for vapor deposition.
The temperature is about 300°C.

Note that the first metal film 24 is different from the first metal film 16.
can be formed of Cr, Ti, or an alloy thereof in addition to Ni, and the second metal film 25 can be formed of S
Besides n/Pb alloy, Cu.

It can be formed of Sn or Pb or an alloy thereof.

Further, in this example, the first metal film and the second metal film were laminated in succession, but another metal film was formed between the first metal film and the second metal film. Even if it is interposed, the same effects as the present invention can be achieved.

According to the electrode structure of the electronic component according to the present invention, the first metal film formed on the conductive thin film and made of any one of Cr, Ni, or Ti, or an alloy of a combination of these, The second metal film is made of Cu, Sn, or Pb, or an alloy of a combination thereof, and has excellent solder wettability. It is an excellent material. Therefore, these first and second metal films protect the conductive thin film formed by firing the metal-organic paste; they can improve mechanical strength, solder wettability, and the like. Further, since the first and second metal films are formed at a low temperature of 300°C or less,
To provide an electrode structure for an electronic component that can reliably obtain desired electrical characteristics and has high electrical reliability since almost no mutual reaction and diffusion occurs between the conductive thin film and the lowermost conductive thin film. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a cross-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 is a cross-sectional view showing an example in which the electrode structure according to the present invention is applied to a base electrode of a chip resistor. FIG. 2 is a cross-sectional view of a chip resistor. A... Electrode structure of extraction electrode, 1o... Insulating substrate, 12
...Conductive thin film, 16..First metal film, 17..Second
B... electrode structure of base electrode, 20... chip substrate (insulating substrate), 21... base electrode (conductive thin film), 24... first metal film, 25... second metal film. Patent applicant Mitsubishi Mining Cement Co., Ltd. Kamaya Electric Co., Ltd.

Claims (1)

[Claims] An electrode structure for an electronic component using a metal-organic paste, comprising: a conductive thin film formed on an insulating substrate of the electronic component by firing the metal-organic paste; a first metal film made of Cr, Ni or Ti, or an alloy of a combination thereof; and Cu, Sn or P.
Consisting of any one of b or an alloy of a combination of these,
and a second metal film formed on the uppermost layer of the electrode structure, the first and second metal films being formed at a low temperature of 300° C. or lower.