JPS6242438A - Film substrate for transmission - Google Patents

Abstract

PURPOSE:To enhance an adhesive strength to a conductive paste by a method wherein a grounding conductor is formed at intervals from the side ends of a tabular matter without covering the whole surface of a grounding surface with metal. CONSTITUTION:A strip conductor 1 is provided on the upper surface of a dielectric tabular matter 3 and a wide grounding conductor 10 is provided on its lower surface in parallel to the conductor 1 conforming its center line to that of the conductor 1. Its width is taken several times or thereabouts wider than that of the strip conductor 1. Side end parts 4 between the grounding conductor and the side ends of the tabular matter 3 are exposed to become dielectric member surfaces. When the above-mentioned film substrate 9 is bonded on a container 7 with a conductive paste 5, the side end parts 4 are firmly bonded because their wetting is very good to the conductive paste 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a film substrate used as a transmission line in a high frequency IC.

[Conventional technology]

A strip line, which is one type of microwave transmission circuit, is a modification of a parallel plate waveguide, and has a ground conductor serving as a ground plane and a strip conductor on both sides of a dielectric material. This stripline has a planar structure, can be made small and lightweight, and can be manufactured as an economical transmission line. It also has excellent compatibility when used in combination with semiconductor components. Therefore, it is widely used as a high frequency transmission line in semiconductor devices.

By the way, the method of die-bonding and adhering the above-mentioned strip line to the semiconductor container as an M&temporary method is not to use the eutectic die-bonding method using solder or gold thread alloy, which is used in the case of ordinary semiconductor devices, but to use a conductive method. Room-temperature bonding methods using paste are increasingly being used.

This is because in high frequency bands, dimensional accuracy is difficult to align with other mounted components, and with the eutectic die bonding method, the position tends to shift and dimensional accuracy is difficult to maintain. Since the 4-electro paste method uses room-temperature bonding, dimensional accuracy can be easily achieved and work costs can be reduced.

[Problem that the invention seeks to solve]

However, there are many problems when bonding a membrane substrate to a container using conductive paste. In Figure 3, the membrane substrate 8 is 1)
Seven conductors, 3 a dielectric plate, and 2 a ground conductor form a strip line. The container 7 and the ground conductor 2 are bonded with the 24-electrode paste 5, but the wetting properties of the 4-electrode paste 5 on the interface of the ground conductor 2 are poor, and outgas is generated during paste curing, resulting in poor wetting properties. This weakens the adhesive strength, and also tends to create cavities 6 due to outgas. The position of the cavity 6 also affects the adhesion force.

Therefore, in order to eliminate the above drawbacks, it is sufficient to select a low outgassing paste that has good wettability (+7) and does not easily form cavities. There is no electric paste.

In view of the above circumstances, an object of the present invention is to provide a membrane substrate having a structure in which sufficient adhesion strength between the membrane substrate and the container can be obtained even with conventional conductive pastes and conventional construction methods. Means for Solving the Problem] The membrane substrate of the present invention is provided with a strip conductor on one side of a dielectric plate, and a strip conductor on the other side that is parallel to the strip conductor and whose center line is aligned with the strip conductor. A ground conductor is provided at a full distance from the side edge of the plate-like body. A high frequency transmission path can be formed by bonding this film substrate to a container of a semiconductor device using a conductive paste.

[Effect]

Although the conductive paste does not have good interfacial wetting properties compared to a ground conductor, it has much better interfacial wetting properties than dielectric members. Therefore, as in the present invention, as in the case of the ground conductor surface side of the membrane substrate, there is a gap between the side edge and the ground conductor. When the material is exposed, the interfacial wettability at this portion is extremely good, so that the adhesion between the membrane substrate and the container can be made sufficiently strong.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the membrane substrate of the example, and FIG. 2 shows the state where it is adhered to a container with 4-ton paste. As shown in the figure, a strip conductor 1 is provided on one surface (upper surface) of a dielectric plate-like body 3, and a wide ground conductor 10t is provided on the other surface (lower surface) in parallel with the strip conductor 1 with its centers ik aligned. Its width is about several times the width of the strip conductor 1. The side end portion 4 between the side ends of the plate-like body 3 is exposed and serves as a dielectric member surface.

When the membrane substrate 9 is bonded to the container 7 with the conductive paste 5,
As shown in FIG. 2, the conductive paste 5 has very good wetting between the conductive paste 5 and the side end portion 4, and the adhesive force is strong. At this time, since the 4t paste 5 is a conventional one, it is possible that a cavity 6 will be formed after 7 hours, but since the side edge part 4 has good wettability, almost no cavity 6 will be formed in this part, so there is no effect on the adhesive strength. do not have.

Next, the influence on high frequency transmission characteristics due to the fact that the ground conductor 10 is not present on the entire surface of the plate-shaped body 3 facing the strip conductor 1 will be described. Generally, if the width of the grounding member 10 is several times the width of the strip conductor 1, 75 to 85 inches of the electric field between the conductors will be concentrated in the vertical vertical direction. This can be calculated theoretically from the ratio of the thickness of the strip conductor l to the thickness of the plate-shaped body 3 and the dielectric constant, and if you select a design value that suits the purpose by considering the characteristics required as a high-frequency transmission line. good.

[Effects of the Invention J As explained above, as for the structure of the membrane substrate, the ground plane is not entirely covered with metal, but the ground conductor is formed at a distance from the side edge of the plate-like body, thereby improving the conventional conductive structure. Sufficient adhesive strength could be obtained even when the paste was used to adhere to the container. Since the work using the 4-electrode paste is performed at room temperature, the relationship f with other parts in the semiconductor device can be set with high dimensional accuracy.

Furthermore, the structure of the membrane substrate can be designed so as not to impair high frequency transmission characteristics.

[Brief explanation of the drawing]

1 and 2 show one embodiment of the present invention.
2 is a perspective view of the membrane substrate, FIG. 2 is a diagram showing the state in which the membrane substrate is adhered to a container, and FIG. 3 is a diagram showing the state in which the conventional membrane substrate is adhered. DESCRIPTION OF SYMBOLS 1... Strip conductor, 2.10... Grounding conductor, 3... Plate-shaped body (induction), 4... Side end portion, 5... Conductive paste, 6
...Cavity, 7...Container, 8.9...
membrane substrate.

Claims (1)

[Claims] A strip conductor is provided on one side of a dielectric plate, and a ground conductor, which is wider than the strip conductor and parallel to the strip conductor with its center line aligned with the other side, is provided on the other side with a space between it and the side edge of the plate. 1. A membrane substrate for transmission in a semiconductor device, which is bonded to a container of a semiconductor device with a conductive paste to form a high frequency transmission path.