JPH0223010Y2 - - Google Patents

Description

[Detailed description of the invention] This invention prevents separation of the conductive layer and the insulating substrate by interposing an intermediate layer that absorbs mechanical stress between the insulating substrate and the conductive layer formed on the surface of the insulating substrate. Regarding the substrate structure.

Conventionally, for electrode substrates used in gas discharge display panels, liquid crystal displays, etc., a metal paste is printed in a predetermined pattern on an insulating substrate 1 made of glass or ceramic, as shown in FIG. 1, and then fired. In this case, the conductor layer 2 is formed by
Since the metal paste contains a glass binder, the glass binder 2a melts and settles and adheres to the insulating substrate 1, as shown in FIG. It has a structure in which the powder 2b is concentrated. There is no problem if the above-mentioned conductive layer 2 is used as it is as an electrode part A, a wiring part B, etc., but if it is used as an external terminal lead-out part C and soldered as shown in FIG. When the external terminal 5 is connected using a molten metal 4 such as the above, the phenomenon that the conductive layer 2 is easily peeled off from the insulating substrate 1 occurs. This is because there is usually a large difference in the coefficient of thermal expansion between the insulating substrate 1 and the molten metal 4, so the mechanical stress caused by the contraction of the molten metal as the temperature drops causes the insulating substrate to expand as shown in FIG. This is because cracks D occur at the bonding interface between conductor layer 1 and conductor layer 2, and the cracks D further progress due to thermal and mechanical shocks during manufacturing or use. The above-mentioned peeling phenomenon occurs when the difference in thermal expansion coefficient between the insulating substrate and the molten metal is 20×10 ^-7 /°C or more, and as this value increases, the difference between the conductive layer and the insulating substrate also increases. The frequency of occurrence increases as the joint area and amount of molten metal increase.

The present invention was developed in view of the above points, and it is useful to utilize the various advantages of molten metal such as solder (reliability of connection, ease of work, cost, The difference in thermal expansion coefficient between the molten metal and the insulating substrate is
An object of the present invention is to provide a substrate structure that can prevent separation of a conductor layer and an insulating substrate even at temperatures of 20×10 ^-7 /°C or higher.

In order to achieve the above objectives, we devised a substrate structure in which an intermediate layer was interposed between the conductor layer and the insulating substrate to absorb mechanical stress, and as a result of various studies on the structure, we found that cement was added to the structure of the concrete. The present invention was developed by focusing on the fact that by mixing not only sand and pebbles, its mechanical strength is increased. That is, the substrate structure of the present invention includes an intermediate layer made of crystallized glass containing glass crystals or amorphous glass mixed with inorganic powder between the conductive layer formed on the insulating substrate and the insulating substrate. An embodiment of the present invention will be described below based on the drawings.

FIG. 5 is a perspective view of a main part of a substrate structure of an embodiment of the present invention applied to a substrate of a gas discharge display panel, and FIG. 6 is a sectional view thereof. In the figure,
The electrode section A and the wiring section B of the gas discharge display panel are formed by directly adhering a conductor layer 2 to an insulating substrate 1 made of glass, ceramic, etc., and the external terminal lead-out section C is a feature of the present invention. It is formed on an insulating substrate 1 with a certain intermediate layer 3 interposed therebetween.

The intermediate layer 3 may be a crystallized powder glass paste containing glass crystals 3a having a size of 1 to 20 μm and a crystallinity of 20 to 70%, or a crystallized powder glass paste containing glass crystals 3a having a size of 1 to 20 μm and a crystallinity of 20 to 70%.
After printing a thick film of amorphous powder glass paste such as lead borosilicate glass containing 20 to 70% (volume ratio) of inorganic powder 3a of 20 μm on the insulating substrate 1, it is fired to form a paste with a thickness of 1 to 50 μm. It is applied as a layer. Furthermore, by printing and firing a powdered glass binder and a metal paste containing metal powder such as Ag or Ag-PD on the intermediate layer 3, the glass binder 2a melts and settles and adheres to the intermediate layer 3, On the other hand, the metal powder 2b gathers on the surface to form the conductor layer 2. The inorganic powder 3a is preferably an insulating material that has a higher melting point than the amorphous glass to be mixed and does not decompose at the above melting point, such as Al ₂ O ₃ Cr ₂ O ₃ , MgO, etc. Can be used.
In addition, the size and content of the glass crystal or inorganic powder and the thickness of the intermediate layer are determined by the difference in thermal expansion coefficient between the molten metal and the insulating substrate, the bonding area between the conductor layer and the insulating substrate, and the thickness of the molten metal. It is appropriately selected within the above-mentioned range depending on the amount and required peel strength.

As shown in FIG. 7, an external terminal 5 is connected to the conductor layer 2 with a molten metal 4 such as solder having a thermal expansion coefficient difference of 20×0 ^-7 /°C or more with the insulating substrate 1. For example, the molten metal 4 contracts when the temperature decreases and mechanical stress is applied, causing a crack D in the intermediate layer 3 as shown in FIG. However, since glass crystals and inorganic powder 3a are present in the intermediate layer 3, the crack D is caused by glass crystals and inorganic powder 3a.
When it reaches point a, it stops and does not proceed any further. In the above-mentioned embodiment, an example was shown in which the present invention was applied to a substrate of a gas discharge display panel, but the present invention is not limited to this, and can be widely applied to other electrode substrates such as liquid crystals. In addition, although the above-mentioned conductor layer is an example in which metal powder is applied to the intermediate layer using a glass binder, the same effect can be obtained for a conductor layer that is directly applied by plasma spraying, vapor deposition, etc. It is something that plays.

As described above, the substrate structure of the present invention has an intermediate layer made of a glass medium containing glass crystals or inorganic powder interposed between the insulating substrate and the conductor layer, so it is not susceptible to mechanical stress caused by soldering etc. Even if a crack occurs in the intermediate layer due to this, the progress of the crack is stopped by the glass crystals and inorganic powder, so separation between the conductive layer and the insulating substrate can be reliably prevented.

[Brief explanation of drawings]

Fig. 1 is a perspective view of the main parts showing a conventional board structure, Fig. 2 is a sectional view of Fig. 1, and Fig. 3 is a cross-sectional view showing a state in which external terminals are connected to the external terminal lead-out portions of Fig. 1. , FIG. 4 is a vertical sectional view of FIG. 3, FIG. 5 is a perspective view of the main part showing the substrate structure of the present invention, FIG. 6 is a sectional view of FIG. 5, and FIG. 7 is a cross-sectional view of FIG. 5. FIG. 8 is a cross-sectional view showing a state in which the external terminal is connected to the external lead-out portion, and FIG. 8 is a partially enlarged view of FIG. 7. DESCRIPTION OF SYMBOLS 1...Insulating substrate, 2...Conductor layer, 3...Intermediate layer, 3a...Glass crystal or inorganic powder.

Claims (1)

[Claims for Utility Model Registration] (1) An intermediate layer made of crystallized glass containing glass crystals or amorphous glass mixed with inorganic powder between the conductive layer formed on an insulating substrate and the above insulating substrate. A substrate structure characterized by intervening layers. (2) The substrate structure according to claim 1, wherein the crystallization rate of crystallized glass or the mixing ratio of inorganic powder is 20 to 70%. (3) The size of the glass crystal or inorganic powder is 1 to 1
The substrate structure according to claim 1 or 2 of the utility model registration claim, characterized in that the thickness is 20 μm. (4) The substrate structure according to any one of claims 1 to 3, wherein the intermediate layer has a thickness of 5 to 50 μm.