JPH01172289A - Paste - Google Patents

Abstract

PURPOSE:To facilitate inspection of a wiring pattern and to improve detection precision of the wiring pattern by allowing a fluorescent material to be incorporated into paste for forming the pattern. CONSTITUTION:One kind of two or more kinds of fluorescent materials selected among a benzoic acid derivative, naphthalene derivative, phenol derivative, phenylporphyrin derivative and fluorescence derivative are blended with 100 parts paste for forming a pattern consisting of tungsten powder, a binder (e.g., ethyl cellulose) and a solvent (e.g., diethylene glycol), etc., at <=1/10 parts.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a paste for pattern formation.

[Conventional technology]

In recent years, from the viewpoint of downsizing and increasing the reliability of single circuit boards, ceramic wiring boards whose main components are alumina, low-melting glass, mullite, etc. have been widely used as boards on which IC chips and electronic components are mounted.

The materials for the ceramic wiring board are a green sheet or sintered ceramic plate made of ceramic powder bonded with resin, a wiring conductor paste containing metal powder as its main component, and an insulating paste containing insulating powder as its main component.

The method for manufacturing a ceramic wiring board involves forming a wiring pattern on a green sheet using the above-mentioned material, and then firing the green sheet. Alternatively, a conductor layer is printed and fired on a ceramic plate, followed by an insulating layer.

It is produced by repeating these steps further.

[Problem that the invention seeks to solve]

However, with the development of electronic devices, ceramic wiring boards are also required to have increasingly higher wiring densities. As a result, the following new problems have arisen. This is a problem caused by the rapid miniaturization of wiring patterns as the circuit density of ceramic wiring boards increases. In other words, the general appearance inspection of green sheets and ceramic boards on which wiring patterns are printed, especially inspections for disconnections and short circuits, has traditionally been done visually, but this method is no longer compatible with the miniaturization of wiring patterns, and inspections have become more difficult. Automation is currently being actively promoted.

The principle of this inspection method is to inspect wiring patterns on green sheets and ceramic plates by utilizing reflection and scattering of light. However, since light reflection and scattering occur not only by metal particles in the wiring pattern but also by green sheets and ceramic plates, it takes a long time to inspect the wiring pattern, and There are drawbacks such as detection errors. Furthermore, it is thought that the current methods described above will no longer be able to keep up with the inspection of wiring patterns, which are expected to become increasingly finer in the future.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide a pattern forming paste that facilitates inspection of wiring patterns.

Measures to solve problem C] The basic idea of the present invention will be described below.

Conventionally, wiring layer patterns were inspected using visible light, but by mixing a fluorescent material into the paste that forms the pattern, it is now possible to inspect wiring layer patterns using ultraviolet light. It is to be.

[Effect]

That is, when ultraviolet light is irradiated onto a green sheet and a ceramic plate in which a pattern is formed using a paste containing a fluorescent material, the pattern emits fluorescence, but no fluorescence is emitted from the green sheet or the ceramic plate.

As a result, the shading of the wiring layer pattern becomes clearer, making it easier to inspect the wiring layer pattern.

The amount of the fluorescent material to be added is determined not to exceed 1/10 part based on 100 parts of the paste for reasons described later.

In addition, as fluorescent materials, benzoic acid derivatives and naphthalene derivatives are used for the reasons described later.

Phenol derivatives, phenylporphyrin derivatives.

Preferably, it consists of one or more fluorescein derivatives.

〔Example〕

Examples of the present invention will be described below.

(Example 1) A case will be described in which a wiring pattern is formed on an alumina green sheet using tungsten paste as a conductor paste for wiring.

First, a method for producing a tungsten paste using tungsten powder for forming a wiring pattern will be described. As tungsten powder, 0.5 μm powder and 3
．． 80% by weight of powder mixed with 0 μm powder at a weight ratio of 3, 2.5% by weight of ethyl cellulose as a binder for paste, and 17.5% of diethylene glycol.
1/100 part of fluorescein powder was added to 100 parts by weight of the mixture, and the mixture was kneaded for 3 hours using a mortar and pestle made of alumina.

Subsequently, this mixture was mixed with three rolls lined with alumina for 30 minutes with a gap of 30 μm, and then n-butylcarpitol acetate was added to adjust the viscosity to obtain a printing paste.

Next, an alumina green sheet (ceramic raw sheet) with a thickness of 0.3 mm was produced using a Dr. Plaid type casting device, and was cut into pieces of 200 m square in external dimension to obtain a green sheet for wiring printing. Subsequently, a wiring pattern for an inspection test was formed by screen printing using the fluorescent agent-containing tungsten paste prepared as described above.

Next, using a pattern recognition type inspection device.

The test wiring pattern was inspected.

In addition, as a comparative example, a wiring pattern for inspection testing was formed on a green sheet in the same manner as described above using tungsten paste without the addition of fluorescent material, and inspection was performed using a pattern recognition type inspection device. .

As for the inspection conditions, ultraviolet light was used for the wiring pattern of the fluorescent material mixed paste, and visible light was used for the wiring pattern of the conventional paste containing no fluorescent material.

The number of samples used for each measurement was 100. The test results are shown in Table 1.

As is clear from Table 1, the accuracy of wiring pattern inspection is higher when the paste containing the fluorescent material according to the present invention is used.

In addition, in the above example, the content of the fluorescent material was reduced to 10
Although the content is about 1/100 parts (relative to 100 parts of paste), sufficient detection accuracy can be obtained if the content is about 1/1,000,000 parts. However, if the content exceeds 1/10 part, it will have an adverse effect on the firing of the paste, resulting in deterioration of the properties as a wiring conductor (increase in specific resistance, decrease in adhesion strength).

Furthermore, in this example, fluorescein was used as the fluorescent material, but any aromatic compound may be used. These include, for example, those with relatively high fluorescence quantum yields and high vapor pressures, benzoic acid derivatives.

There are naphthalene derivatives, phenol derivatives, etc., and those with extremely high fluorescence quantum yields and relatively large molecular weights, phenylporphyrin derivatives, fluorescein derivatives, etc. The former has the advantage of being easily removed due to its high vapor pressure and does not cause any hindrance during firing, and the latter having only a small amount and not causing any hindrance during firing.

(Example 2) A case will be described in which a wiring pattern is formed on a sintered alumina plate using Ag/Pd paste as a pattern forming paste.

The ratio of Ag and Pd is 8=2, and the average particle size is 0.2
Organic vehicle (5% ethyl cellulose α-terpineol solution) was added at 30% by weight to 70% μm mixed powder.
One-hundredth part of fluorescein powder was added to 100 parts by weight of the mixture and kneaded to form a paste.

In addition, a paste to which no fluorescent material was added was also prepared in the same manner as above.

Subsequently, a wiring pattern was formed on the alumina board using the above two types of paste in the same manner as in Example 1,
Pattern inspection was performed using a pattern recognition type inspection device. As for the inspection conditions, ultraviolet light was used for the fluorescent material mixed paste, and visible light was used for the paste that did not contain the fluorescent material. The test results are shown in Table 2.

Table 2 As is clear from Table 2, the accuracy of wiring pattern inspection is higher when a paste containing a fluorescent material is used.

The test results of Examples 1 and 2 show that detection accuracy can be improved simply by adding a fluorescent material to the paste, regardless of the composition of the paste. Namely.

It is applicable if it is a paste.

[Effects of the Invention] As described above, according to the present invention, by adding a fluorescent material to a pattern forming paste, it becomes possible to inspect wiring patterns with high precision.

Claims (1)

[Claims] 1. A paste characterized in that it contains a fluorescent material in an amount not exceeding 1/10 part based on 100 parts of pattern-forming paste.