JPH08148031A - Conductive paste - Google Patents

Abstract

PURPOSE: To ensure sufficient adhesive strength to a part main unit of an external electrode even after a plating process is applied. CONSTITUTION: Conductive paste consists of silver, copper, borosilicate lead system glass frit and an organic vehicle. Further, compounding ratio of copper relating to 100 pts.wt. silver is set to within a 0.5 to 5 pts.wt. range. In addition, the copper may be added in any form of metal copper, copper oxide and copper organic matter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive paste containing silver as a main conductive component and used for forming external electrodes of electronic parts.

[0002]

2. Description of the Related Art Conventionally, chip resistors and the like have been known as electronic parts equipped with external electrodes, and the external electrodes in these electronic parts are the ends of the parts body made of ceramics such as alumina. It is provided in a state of covering the surface on a predetermined portion such as a part. When providing these external electrodes, the lower electrode layer is formed by depositing a conductive paste on the surface of the component body by a technique such as dipping or screen printing and baking it, and at the same time, forming a nickel (Ni ) A procedure of forming an intermediate electrode layer covering the lower electrode layer by performing a plating treatment and then forming an upper electrode layer on the intermediate electrode layer by performing a tin (Sn) plating treatment or a solder plating treatment It is generally done.

In this case, the conductive paste contains silver (Ag) as a main conductive component, that is, Ag.
It is common to use a silver electrode paste obtained by dispersing a powder and a non-reducing glass frit in an organic vehicle.As the glass frit in this silver electrode paste, a lead borosilicate-based material, and as an organic vehicle, Resins such as ethyl cellulose dissolved in a solvent such as butyl carbitol or xylene are used.

[0004]

By the way, when the lower electrode layer of the external electrode is formed by using the silver electrode paste having the above conventional composition, the lower electrode layer is formed by the action of the glass frit contained in the silver electrode paste. The electrode layer is firmly bonded to the component body. However, when the intermediate electrode layer and the upper electrode layer are respectively formed on the lower electrode layer by the subsequent plating treatment, since the glass frit is eroded by the plating solution, the external electrode after the plating treatment with respect to the component body The adhesive strength was supposed to deteriorate.

The present invention was devised in view of such inconvenience, and is a conductive paste capable of ensuring a sufficient adhesive strength of an external electrode to a component body even after being plated. The purpose is to provide.

[0006]

In order to achieve such an object, a conductive paste according to the present invention comprises silver and copper, a lead borosilicate-based glass frit, and an organic vehicle, and silver It is characterized in that the compounding ratio of copper to 100 parts by weight is within the range of 0.5 to 5 parts by weight. The copper here may be added in the form of any of metallic copper, copper oxide, and copper organic matter.

[0007]

Embodiments of the present invention will be described below.

The conductive paste according to the present embodiment is used for forming external electrodes of component bodies of electronic components such as chip resistors, that is, component bodies made of ceramics such as alumina. And is made of silver and copper, a lead borosilicate glass frit, and an organic vehicle. The blending ratio of silver to the entire conductive paste in this example is 65w.
The composition ratio of t% and glass frit is 10 wt%, while the balance of the conductive paste except copper is an organic vehicle obtained by dissolving 10 parts of ethyl cellulose resin with 90 parts of terpineol solvent. . In addition,
Here, when silver is 100 parts by weight, the compounding ratio of the glass frit is represented as 15.4 parts by weight.

First, a silver (Ag) powder, which is a main conductive component, a metallic copper (Cu) powder as copper, a glass frit, and an organic vehicle are prepared.
A conductive paste having the component composition shown in Sample 1 in Table 1 is prepared by preparing the mixture such that the compounding ratio of Cu with respect to 00 parts by weight is 0.5 parts by weight and thoroughly kneading. Also, copper oxide (Cu
O) and then CuO for 100 parts by weight of Ag
The conductive paste having the component composition shown in Samples 2, 3, and 4 of Table 1 was added by changing the compounding ratio of each of 0.62, 3.1, and 6.2 while kneading and kneading. Create. At this time, since the conductive paste of Sample 4 contained CuO in an amount of more than 5 parts by weight, it was out of the scope of the present invention.

[0010]

[Table 1]

Further, Cu soap as a copper organic substance was prepared, Cu soap having a mixing ratio of 7.7 with respect to 100 parts by weight of Ag was added, and the mixture was kneaded.
A conductive paste to be Sample 5 is obtained. In addition, this C
Since the copper content in u soap is 11 wt%, A
The substantial amount of copper added to 100 parts by weight of g is 0.85 parts by weight. Furthermore, a silver electrode paste as in the conventional example to which no copper is added, that is, the conductive pastes shown as samples 6 and 7 in Table 1 are prepared as comparative samples. The conductive pastes of Samples 6 and 7 are naturally outside the scope of the present invention.

Next, although not shown, a plurality of 96% alumina substrates were prepared, and the conductive pastes of Samples 1 to 7 were separately applied on the surfaces of the alumina substrates by screen printing, and then 120 ° C. It was dried by leaving it at the temperature of. In addition, continue to 800
The conductive paste is baked to form a lower electrode layer by firing at a temperature of ℃ for 1 hour, and a nickel (Ni) plating treatment is performed to form an intermediate electrode layer with a thickness of 1 μm that covers the lower electrode layer. Then, tin (Sn) plating treatment is applied to form a thickness of 3 μm on the intermediate electrode layer.
The upper electrode layer of was formed.

After that, the adhesive strength of each of the external electrodes made of the conductive paste of Samples 1 to 7 formed according to the above procedure to the component body, that is, the adhesive strength of the external electrode after the plating treatment was measured. The results shown in Appendix 1 were obtained. The adhesive strength (N: Newton) here is a value obtained by pulling the lead wire after soldering the lead wire to each external electrode, and in this embodiment, 60 Sn / A 40Pb solder is used to solder a lead wire with a diameter of 0.8mm to an external electrode with a size of 2mm x 2mm, and the lead wire is pulled by a tensile tester at a speed of 20mm / min (min). The adhesive strength measured by pulling is shown.

Then, when the adhesive strength measured as described above is examined, the adhesive strength of the external electrode made of the sample 6 equivalent to the conventional example is 9N, while the sample 1 containing copper is added. It is apparent that the adhesive strength is significantly improved to 20 N or more in any of the external electrodes formed using any of the conductive pastes 5, 5, and 7. By the way, the conductive paste of Sample 7 is supposed to exhibit the highest adhesive strength because the amount of copper added is large, although it is outside the range of the present invention. However, in the external electrode made of the conductive paste of Sample 7, copper was diffused over a wide range with respect to the component body made of alumina, and discoloration of alumina was caused. Therefore, in the present invention, 100 wt. The mixing ratio of copper to parts is regulated within the range of 0.5 to 5 parts by weight.

[0015]

As described above, according to the conductive paste of the present invention, copper having a compounding ratio of 0.5 to 5 parts by weight to 100 parts by weight of silver is added. As a result, it is possible to obtain a sufficient adhesion strength of the external electrode to the component body even after the plating process.

Claims (2)

[Claims] 1. A conductive paste comprising silver and copper, lead borosilicate glass frit, and an organic vehicle, wherein the compounding ratio of copper to 100 parts by weight of silver is 0.5 to 5 parts by weight. A conductive paste characterized by being within the range. 2. The copper is added in the form of any one of metallic copper, copper oxide, and a copper organic substance.
The conductive paste according to.