JPH05206673A - Hybrid integrated circuit device - Google Patents

Abstract

PURPOSE:To avoid the leakage of noise through gaps of the overlapping part of a shielding case by a method wherein the overlapping part of the shielding case which covers all the surfaces of a hybrid integrated circuit device except the surface on which outer leads are provided is spot-welded with a predetermined interval. CONSTITUTION:A shield case 40 covers all the surfaces of a hybrid integrated circuit device except the surface on which outer leads 30 are provided and is composed of two metal components taking the difficulty of a press process into account. Heat radiation holes 44 whose diameters are not larger than 1/10 of the wavelength of a noise in question are formed in the side surfaces of the shielding case 40 and the problems of heat radiation and the noise are resolved simultaneously. Further, the overlapping part of the shielding case 40 composed of two metal components is spot-welded 46 with an interval not larger than 1/10 of the wavelength of the noise. With this constitution, the leakage of the noise through gaps of the overlapping part of the shielding case 40 can be avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid integrated circuit device for a digital TV, and more particularly to a technique for reducing its leakage noise.

[0002]

2. Description of the Related Art A digital TV is an analog type because it can achieve high image quality, can easily process an image, can obtain a highly reliable circuit without adjustment, and can easily be integrated into a circuit. I'm winning A digital TV and a hybrid integrated circuit device for a digital TV will be described with reference to FIGS.

Referring to FIG. 8, a digital TV has 50
A tuner (50) that demodulates TV radio waves of MHZ to 1 GHz and outputs a luminance signal Y and color difference signals RY and BY having a band of approximately 4.5 MHz, and operates at a sampling frequency of 13.5 MHz 6 It is composed of a 10-bit A / D conversion circuit (52), an image memory (54), an arithmetic circuit (56), a D / A conversion circuit (58), a video output circuit (60) and a CRT (62).

FIG. 9 shows a hybrid integrated circuit device for digital TV (hereinafter simply referred to as a hybrid integrated circuit device) proposed by the present applicant. In this hybrid integrated circuit device (70), the A / D conversion circuit (52), the image memory (54), the arithmetic circuit (56), and the D / A conversion circuit (58) in the broken line of FIG. It is a thing.

Referring to FIG. 9, two insulating metal substrates (7
For (0) and (72), aluminum having a thickness of about 2 mm, whose surface is anodized, is used in consideration of heat dissipation characteristics and workability. Then, after forming a dead hole at a predetermined position of this insulating metal substrate, a clad material of a thermosetting insulating resin having adhesiveness such as a polyimide resin and a copper foil having a thickness of about 35 μm is hot-pressed to remove this copper foil. By photo-etching or the like, pads, conductive paths, etc. are formed in a predetermined pattern. The thermosetting insulating resin becomes an insulating layer having a thickness of about 35 μm after hot pressing.

After that, the bridge portion of the dead hole of the insulating metal substrate is cut and divided into two insulating metal substrates (70) and (72) so that mutual circuit patterns are conductive paths in the bridge portion. Two connected insulating metal substrates are obtained.
A / D conversion circuit (52), image memory (54), arithmetic circuit (56),
A semiconductor element such as an integrated circuit element constituting the D / A conversion circuit (58) is fixed in a chip shape by using silver paste or the like on a predetermined pad, and atypical parts such as a chip resistor are fixed by soldering (both are (Not shown in Figure 9).

The insulating metal substrate (70) (72) on which this circuit element is mounted is made of a metal case (7) using an adhesive resin.
4) and the lid (76) are sealed, and the entire structure is inserted into a frame-shaped shield case (78) that covers the resin adhesive portion.

[0008]

[Problems to be Solved by the Invention] Conventional digital TV
Although the hybrid integrated circuit device can provide a digital TV at a small size and at a low cost, image distortion has been confirmed in a TV set with a special structure such as a TV set with an antenna. According to the basic research conducted by the inventors of the present invention, the cause is that harmonic components of noise generated inside the hybrid integrated circuit device leak from the slight gap between the external lead and the insulating metal substrate and the shield case, and the antenna circuit It has been clarified that it is caused by being mixed into the. That is, it has been clarified that the adhesive gap between the insulating metal substrate and the metal case and the gap between the insulating metal substrate and the shield case have sufficient spans for leaking the generated noise, particularly the wavelength of the noise in question.

Further, it has been known that noise leaks from the overlapping portion of the shield case in which the surface material is pressed into a box shape, but continuous welding of the overlapping portion of the shield case causes a problem of cost increase. Therefore, an object of the present invention is to provide an inexpensive hybrid integrated circuit structure which prevents noise leakage from the gap between the overlapping portions of the shield case.

[0010]

SUMMARY OF THE INVENTION The main feature of the present invention is that spots are welded at predetermined intervals to overlapping portions of a shield case that covers all surfaces except the surface on which external leads are provided.

[0011]

Since all the surfaces except the surface on which the external leads are provided are covered with the shield case, noise leakage from the gap between the shield case and the hybrid integrated circuit device is prevented. Further, since the overlapping portions of the shield case are spot welded at a predetermined interval, the shield case can be joined at a lower cost than in continuous welding. Furthermore, since spot welding is performed at intervals that do not leak noise, which is a problem, noise leakage from the overlapping portion can be sufficiently prevented.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A hybrid integrated circuit device for a digital TV (hereinafter referred to as a hybrid integrated circuit device) of the present invention will be described with reference to FIGS. 1 is an equivalent circuit diagram of an embodiment of the present invention, and corresponds to the circuit within the broken line of FIG. 8 used in the description of the conventional example. 2 is a perspective view of one integrated circuit board, FIG. 3 is a sectional view of one embodiment, and FIG. 4 is a perspective view of one embodiment.

Referring to FIG. 1, in this embodiment, an A / D conversion circuit (12), an image memory (14), an arithmetic circuit (16), and a D / A conversion circuit (18) are a hybrid integrated circuit device (10). As a result, it is divided and formed on two insulating metal substrates, the two insulating metal substrates are arranged to face each other, and a circuit formed into a hybrid integrated circuit is cut off from an external circuit to prevent noise leakage. In addition, a chip-shaped ferrite bead core (36) or a resistor (38) is inserted between all external lead terminals except the power supply terminal and the internal circuit of the hybrid integrated circuit device. It is also possible to prevent noise leakage.

Referring to FIGS. 2 and 3, the two insulating metal substrates (20) and (22) are anodized on their surfaces in consideration of heat dissipation characteristics and workability (the oxide film is denoted by reference numeral 24). Show)
Aluminum of approximately 2 mm thickness is used. Then, after forming a dead hole at a predetermined position of this insulating metal substrate, a thermosetting insulating resin having an adhesive property such as a polyimide resin is used to form approximately 35 μm.
A pad material (26), a conductive path (28), etc. are formed in a predetermined pattern by hot pressing a clad material with an m-thick copper foil and photoetching the copper foil.

A pad to which an external lead terminal for grounding is fixed and its conductive path (28) are formed on both sides of the insulating metal substrates (20) and (22), and a mother substrate on which the hybrid integrated circuit device of this embodiment is mounted. The ground pattern formed above connects the ground circuit of the hybrid integrated circuit device and the ground pin of the shield case described later with low impedance. Also, the conductive path (2
Since the line width of 8) is as fine as about 35 μm, which is equal to the copper foil thickness, it is formed in a smooth curved pattern in order to prevent noise generation due to electric charge concentration. Further, a radius is given to a portion where the conductive path pattern has an acute angle. In addition, the thermosetting insulating resin is an insulating layer (24) having a thickness of approximately 35 μm after hot pressing.
Becomes

After that, the bridge portion of the dead hole of the insulating metal substrate is cut and divided into two insulating metal substrates (20) and (22), so that mutual circuit patterns are conductive paths in the bridge portion. Two connected insulating metal substrates (20) (22) are obtained. However, it is also possible to individually form the two insulating metal substrates (20) and (22) and connect the respective circuits by appropriate connecting means.

A predetermined pad (26) formed on the two insulating metal substrates (20) and (22) has the above-mentioned A / D conversion circuit (12), image memory (14), arithmetic circuit (16), Semiconductor elements such as integrated circuit elements constituting the D / A conversion circuit (18), circuit elements such as chip resistors and chip capacitors, and atypical parts such as ferrite bead cores (36) or resistors (38) for suppressing terminal noise are It is fixed with a brazing material such as solder.

Then, a predetermined circuit is connected by wire bonding, and the two insulating metal substrates (20) and (22) to which the external leads (30) are fixed by soldering are mounted using an adhesive sheet so that their mounting elements face each other. As described above, the frame-shaped resin case (32) is fixed and integrated. As shown in FIG. 3, the circuit connecting portions (folded portions) of the two insulating metal substrates (20) and (22) are arranged in the end portions of the two insulating metal substrates (20) and (22). Become.

FIG. 5 is a development view of an example of a shield case characteristic of the present invention. The shield case (40) used in the present invention has a structure that covers all surfaces of the hybrid integrated circuit device except the surface on which the external leads (30) are provided. After pressing the materials individually into a lid shape and overlapping them, the overlapping part (the surface of the spot welded part (46) in Fig. 4) is used to determine the wavelength of the generated noise, especially the wavelength of the noise in question. Spot welding is performed at intervals of about 1/10 or less, and they are joined to form a box.

Shield case whose thickness is less than 10 mm
Continuation of the overlapping portion of (40), complete welding has a high joining cost, and workability is low, whereas the present invention for spot welding the overlapping portion of the shield case (40) reduces the joining cost. It is possible to prevent noise leakage sufficiently.

As described above, the shield case (40) has a low impedance between the ground circuit of the hybrid integrated circuit and the shield case (40) by the ground pattern formed on the mother board on which the hybrid integrated circuit device is mounted. A plurality of heat dissipation holes (44) are formed so as to include a ground pin (42) for connection and not to interfere with heat dissipation from the insulating metal substrates (20) and (22). Although the embodiment shows a circular heat dissipation hole, any major shape can be used as long as its major axis is about 1/10 or less of the wavelength of noise in question. In this embodiment, the heat dissipation holes (44) are formed in a matrix on the side surface of the shield case (40).
In consideration of the positional relationship of the circuit elements mounted on the insulating metal substrates (20) and (22), they may be formed in a puddle arrangement or partially formed in a region where heat dissipation is required.

FIG. 6 and FIG. 7 show the harmonic noise characteristics of the conventional example and the example, which were measured with an arbitrary external lead. The figure shows center frequencies of 500 MHz, 150 KHz / div and 10 d.
b / div. As shown in the figure, the noise level of the conventional hybrid integrated circuit device reaches -20db, whereas the noise level of -40db or less is achieved in the hybrid integrated circuit device of the present invention. The measurement condition is that a resistance of 1 KΩ is connected between the terminal to be measured and ground, and the current flowing through this resistance is 5 mV.
It is converted at an efficiency of / mA.

[0023]

As described above, in the hybrid integrated circuit device of the present invention, noise leakage from the gap between the insulating metal substrate and the shield case is prevented because all the surfaces except the surface on which the external leads are provided are covered with the shield case. In addition to being prevented, the heat dissipation characteristics are not impaired because the heat dissipation holes are formed in the shield case in a size that does not allow problematic noise to pass through. Further, since the superposed portion of the shield case is spot-welded at intervals of about 1/10 or less of the wavelength of noise in question, leakage noise can be sufficiently suppressed without increasing the joining cost.

Further, since chip-shaped ferrite beads cores or resistors are inserted between all the external lead terminals except the power source and the internal circuit, noise leakage from the external leads is prevented. Further, since the ground circuits of all the integrated circuit elements are connected to the insulating metal substrate in the vicinity of each integrated circuit element and where the pattern impedance is low, the operating potential of the integrated circuit element is stable and noise generation is prevented. ..

Since the ground pattern and the external lead terminals are formed on at least both sides of the two insulating metal substrates, the shield case is connected to the ground pattern with low impedance on the mother substrate on which the hybrid integrated circuit device is mounted. , The potential of the shield case is stable and noise generation is prevented. Furthermore, since the circuit pattern is formed smoothly, noise generation due to electric charge concentration is prevented.

[0026]

[Brief description of drawings]

FIG. 1 is an equivalent circuit diagram of an embodiment of the present invention.

FIG. 2 is a perspective view of an integrated circuit board of the present invention.

FIG. 3 is a sectional view of an embodiment of the present invention.

FIG. 4 is a perspective view of an embodiment of the present invention.

FIG. 5 is a development view of the shield case of the present invention.

FIG. 6 is a noise characteristic diagram of a conventional example.

FIG. 7 is a noise characteristic diagram of the present invention.

FIG. 8 is an equivalent circuit diagram of a digital TV.

FIG. 9 is a perspective view of a conventional example.

[Explanation of symbols]

 10 hybrid integrated circuit device 12 A / D conversion circuit 14 image memory 16 arithmetic circuit 18 D / A conversion circuit 20 insulating metal substrate 22 insulating metal substrate 24 oxide film 26 pad 28 conductive path 30 external lead 32 case 36 ferrite bead core 38 resistance 40 Shield Case 42 Ground Pin 44 Heat Dissipation Hole

Claims (4)

[Claims] 1. An integrated circuit in which at least one circuit element required for a digital TV, such as an A / D conversion circuit, an image memory, an arithmetic circuit, and a D / A conversion circuit, is integrated on a circuit pattern formed on an insulating metal substrate. A circuit board, a case material for hermetically sealing the circuit elements formed on the insulating metal substrate, and a shield case that covers all surfaces except the surface on which the external leads are provided, and the overlapping portion of the shield case is predetermined. A hybrid integrated circuit device characterized in that spot welding is performed at intervals of. 2. The hybrid integrated circuit device according to claim 1, wherein the spot welding interval of the cider case is set to about 1/10 or less of a wavelength of noise in question. 3. The hybrid integrated circuit according to claim 1, wherein chip-shaped ferrite bead cores and / or chip resistors are arranged between all external lead terminals except the power source formed on the substrate and internal circuits. circuit. 4. A ground circuit of an integrated circuit device such as the A / D conversion circuit, the image memory, the arithmetic circuit, the D / A conversion circuit, etc. is located in the vicinity of each integrated circuit device and has a relatively low pattern impedance. 2. The hybrid integrated circuit device according to claim 1, wherein the hybrid integrated circuit device is connected to the insulating metal substrate by.