JPS58148484A - Ceramic thick film board with electromagnetic shield - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ceramic thick film substrate with electromagnetic shielding.

Hybrid IC uses thick film technology to print resistors, wiring patterns, etc. on a ceramic thick film substrate.
A capacitor or the like is added, each is connected by wire bonding or the like, and an appropriate number of pins are provided protrudingly.

A hybrid IC is used by being soldered to a printed circuit board. Various circuit elements are provided on the printed circuit board.

A large number of hybrid ICs may be mounted on the same printed circuit board. In this way, higher density and higher integration of circuits can be achieved. However, on the other hand, interference is likely to occur between each hybrid IC or between the hybrid IC and other circuit components.

Electromagnetic interactions between hybrid ICs and between hybrid LCs and circuit components cause malfunctions and noise. The faster the operating speed and the closer the distance between parts, the more significant the electromagnetic interaction will be.

Conventionally, in order to suppress interference between high frit ICs, a third
As shown in the figure, a shield structure with a conductor sandwiched between them was used.

In FIG. 3, a hybrid IC 11, 11 is soldered onto a printed circuit board 12. In FIG. In order to avoid interference between the two, a conductive plate 13 is interposed between the hybrid ICs 11 and 11, and grounded to the ground pattern 14 of the printed circuit board 12 via a suitable conductor 15.

The conductive plate is made of a metal plate such as copper or aluminum, or a conductive plastic plate.

As described above, the method of electromagnetically shielding a hybrid IC by attaching an independent conductor to a printed circuit board has the disadvantage that the mounting density of the hybrid IC on the printed circuit board is reduced. This is because mounting the conductive plate requires space, and additional wiring patterns must be provided to ground the conductive plate.

Furthermore, since a conductive plate for electromagnetic shielding must be attached to the printed circuit board, the number of components to be mounted increases, and the number of man-hours required for mounting to the printed circuit board increases.

The present invention aims to solve these difficulties. The thick film substrate of the present invention has an electromagnetic shielding film formed on the back surface of the substrate by printing a conductive material using thick film technology.

Hereinafter, the configuration, operation, and effects of the present invention will be explained with reference to drawings showing examples.

FIG. 1 is a rear view of a thick film substrate according to an embodiment of the present invention.

The hybrid IC 1 has a resistance pattern, a wiring pattern, a glass film, etc. printed on the surface of a ceramic thick film substrate 2, an IC chip attached thereto, and a wiring part electrode and an IC electrode connected by wire bonding. Individual components such as capacitors and transistors may also be soldered. The structure of the surface of the ceramic thick film substrate 2 is arbitrary.

A plurality of pins 3 are taken out from the ceramic thick film substrate 2. The number of pins is arbitrary. Of these, there is always a pin that should be grounded. The position of the earth pin (GND) 4 may also be arbitrary.

The feature of the present invention is that an electromagnetic shielding film 5 is printed on the back surface of the ceramic thick film substrate 2.

The electromagnetic shielding film 5 is formed by printing a conductive material using thick film technology, and is electrically connected to the earth pin 4. Any conductive material can be used, for example silver palladium (AgPd) paste. This is a material frequently used to construct wiring patterns.

In the example shown in FIG. 1, the electromagnetic shielding film 5 is uniformly formed over almost the entire back surface of the thick film substrate 2. In the example shown in FIG. Since the electromagnetic shielding film 5 is grounded via the earth pin 4, it is possible to block interference from other circuit components of the other hybrid IC 1, and this hybrid 1c gives electromagnetic interaction to other hybrid ICs. There will be no more.

It is possible to block electromagnetic interaction between hybrid ICs and circuit components that can mutually become noise sources.

In some cases, the purpose can be sufficiently achieved without forming an electromagnetic shielding film on the entire back surface of the thick film substrate 2.

FIG. 2 shows another such embodiment.

On the back surface of the ceramic thick film substrate 2 of the hybrid IC 1, five mesh-like electromagnetic shielding films (shown in black) are formed.

By making it into a mesh shape, the amount of conductor material can be reduced and the cost can be lowered. The mesh dimensions, line width, etc.
You just have to decide appropriately.

In this example, the meshes are arranged vertically and horizontally, but they may be arranged diagonally.

Furthermore, the electromagnetic shielding film is not limited to a mesh shape, and may be a comb-toothed (not shown) electromagnetic shielding film. It may be concentric circles, or it may be a complicated maze-like shape pattern.

In this example, the earth pin 4 is used to ground the electromagnetic shielding film 5, but other grounding mechanisms are possible. The ground pattern of the printed circuit board and the electromagnetic shielding film 5 may be directly coupled using a separate conductive material.

The present invention provides a hybrid IC in which a conductive material is printed on the back side of a thick film printed substrate to form an electromagnetic shielding film.
Electromagnetic interaction between the hybrid IC and electronic circuit components can be suitably suppressed.

It can also block out noise from outside.

゛Compared to a mechanism that inserts a separate conductive plate between hybrid ICs to provide electromagnetic shielding, installation is easier, no extra space is required, and hybrid ICs can be mounted more densely on printed circuit boards. There is no decline.

It can be widely applied to automotive electronic equipment and other electronic equipment. This is a useful invention.

[Brief explanation of the drawing]

FIG. 1 is a rear view of a ceramic thick film substrate according to an embodiment of the present invention. FIG. 2 is a rear view of a ceramic thick film substrate according to another embodiment of the present invention. FIG. 3 is a perspective view showing a conventional configuration in which a conductive plate is inserted between hybrid ICs mounted on a printed circuit board for electromagnetic shielding. 1... Hybrid TC 2... Ceramic thick film substrate 3... Pin 4... Earth pin 5... Electromagnetic shielding film inventor Fukuma Sakamoto 1 ) Toshitake Nakamasa (2nd patent applicant) Sumitomo Electric Industries, Ltd.

Claims (4)

[Claims] (1) A ceramic thick film board with an electromagnetic shield, characterized in that a conductive material is printed on the back side of the thick film printed board to form an electromagnetic shield film. (2) A ceramic thick film substrate with an electromagnetic shield according to claim 1, wherein the electromagnetic shield film is connected to a ground pin of a hybrid IC. (3) A ceramic thick film substrate with an electromagnetic shield according to claim gJ2, wherein the electromagnetic shield film is uniformly formed over almost the entire back surface of the thick film printed board. (4) A ceramic thick film substrate with an electromagnetic shield according to claim 2, wherein the electromagnetic shield film is printed in a mesh pattern.