JPH07211994A - Surface-mounting hybrid ic - Google Patents

Abstract

PURPOSE:To provide the structure of a surface-mounting hybrid IC which shields a circuit pattern on the rear surface of a ceramic substrate with an insulating film so as to prevent the circuit pattern from coming into contact with a copper foil pattern on one printed wiring board. CONSTITUTION:In a surface-mounting hybrid IC in which a joining surface which joins a circuit and chip element, etc., to each other is formed of a circuit pattern 2 on the front surface of a ceramic substrate 1 and another circuit which is engaged with the circuit is formed of another circuit pattern 3 on the rear surface of the substrate, and then, the front surface of the substrate 1 is coated with a shell 5 and which is provided with a terminal section 4 extended from the circuit on its side face an insulating film 6 is formed on the rear surface of the substrate 1 by applying insulating paste to the rear surface and baking the paste. The insulating film 6 can be formed by sticking and fixed an insulating sheet to the rear surface of the substrate 1. The insulating film 6 can be also formed by applying and fixing an epoxy resin to the rear surface.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a surface mount hybrid IC.
The present invention relates to an exterior insulating structure in more detail.

[0002]

2. Description of the Related Art As shown in the side view of FIG. 3, the structure of an assembly typified by a conventional surface mount hybrid IC has a circuit pattern 22 on a surface of a ceramic substrate 21, for example, a circuit and a chip element. A bonding surface to be bonded is formed, a circuit that engages with the circuit is formed on the back surface by the circuit pattern 23, and electrodes 24 that extend from both circuits and are connected to the outside are provided on the side surface, and the front surface of the ceramic substrate 21. A box-shaped shell 25 whose bottom is opened with a resin material for the above circuit.
Then, the opening edge of the shell 25 is adhered to the surface of the ceramic substrate 21 with an epoxy resin to seal the circuit pattern 22 on the surface of the ceramic substrate 21 and a mounting component such as a chip element. It is generally done as a completed body. However, the bottom surface of these surface mount hybrid ICs, that is, the ceramic substrate 2
The circuit pattern 23 formed on the back surface of 1 may be protected by a fired glass film or the like, but if the film thickness is thin and printing resistance is present, trimming with a laser is performed on this glass film. Because of this, the cut surface of the printing resistor is exposed. Therefore, while the surface mount hybrid IC is placed on the circuit pattern 27 of the printed wiring board 26 that constitutes one circuit and the assembly process such as solder reflow is performed, Foreign matter such as metal powder may enter the gap between the circuit pattern 27 and short-circuit the cut surface of the circuit pattern 23 and the circuit pattern 27.
In addition, when the circuit pattern 27 has fine protrusions or the like, when the solder melts, the solder often comes into contact with the circuit pattern 23 on the back surface of the ceramic substrate 21 via the protrusions.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a circuit pattern on one printed wiring board is formed by shielding the circuit pattern on the bottom surface of the surface mount hybrid IC with an insulating film. The present invention provides a surface mount hybrid IC that prevents contact with the surface mount hybrid IC.

[0004]

In order to solve the above-mentioned problems, the first invention of the present application is to form a circuit pattern on both surfaces of a substrate and electrodes on the side surfaces and mount a chip component on the front surface.
In a surface mount hybrid IC in which the front surface of the substrate is covered with a shell, an insulating film is formed on the back surface of the substrate, and the insulating film forms a circuit pattern on the back surface of the substrate and a circuit pattern on one printed wiring board. It is characterized by being insulated. A second invention of the present application relates to the first invention of the present application, characterized in that a conductive paste is applied and baked on the back surface of the substrate. A third invention of the present application relates to the first invention of the present application, wherein the surface mounting hybrid IC according to claim 1, wherein an insulating sheet is attached to the back surface of the substrate. A fourth invention of the present application relates to the first invention of the present application, characterized in that an epoxy resin is applied to the back surface of the substrate.

[0005]

With the above-described structure, according to the surface mount hybrid IC of the present invention, an insulating film having an insulating property is formed on the circuit pattern surface on the back surface of the ceramic substrate.
Even if the bottom surface of the surface-mount hybrid IC is brought into close contact with one of the printed wiring boards on which the surface-mount hybrid IC is mounted, the circuit pattern surface of the ceramic substrate and the circuit pattern surface of the printed wiring board are separated from each other. Since the insulating layer formed by the insulating film is closely intervened, no foreign matter is mixed in, and even if there is a protrusion or the like on the circuit pattern, it is blocked by the insulating film and therefore no short circuit occurs.

[0006]

Embodiments of the present invention will be described in detail below with reference to the drawings. 1 is a bottom view showing the surface mount hybrid IC, and FIG. 2 is a side sectional view showing the surface mount hybrid IC of FIG. In the figure, reference numeral 1 is a ceramic substrate, on the surface of which a bonding surface for bonding a circuit and a chip element or the like is formed by a circuit pattern 2, and on the back surface, a circuit for engaging the circuit is formed by a circuit pattern 3 And an electrode 4 extending from the circuit and connected to a circuit pattern of an external printed wiring board. Reference numeral 5 denotes a shell, which is made of a resin material and formed into a box shape having an open bottom surface. The shell 5 is covered on the surface of the ceramic substrate 1 so that the opening edge of the bottom surface and the surface of the ceramic substrate 1 are made of epoxy. The circuit pattern 2 on the surface of the ceramic substrate 1 and the mounting components such as chip elements are sealed by adhering with the resin of FIG. Reference numeral 6 denotes an insulating film, and the entire area of the outer periphery of the circuit pattern 3 excluding the vicinity of the electrode 4 requires, for example, a marking paste composed of a resin material as a material in the second feature of the present application. And the thickness is formed on the surface of the circuit pattern 3 through a firing (firing temperature of about 150 ° C.) step.

Therefore, in the manufacturing process, since the bottom surface of the surface mount hybrid IC mounted on the circuit pattern 3 of the printed wiring board 1 is insulated by the insulating film 6, the solder reflow or the like may occur. Even if foreign matter such as metal powder is mixed in the process, the insulating film 6 does not shield and contact the circuit pattern 3. Moreover, even if the circuit pattern 3 has a protrusion or the like, the circuit pattern 3 is blocked by the insulating film 6 to prevent the patterns of both substrates from contacting each other. By controlling the firing temperature of the insulating film 6 to about 150 ° C., the substances already used in the previous step, that is, cream solder (about 225 ° C.) and glass paste (about 515 ° C.) are used.
(.Degree. C.) melting temperature is not affected. In the third characteristic part of the present application, for example, a polyester-based sheet is bonded to the surface of the circuit pattern 3 on the back surface of the ceramic substrate 1 by using a silicone rubber-based adhesive having a constant viscosity. Then, the sheet is insulated and an insulating film similar to the above is formed. In the fourth feature of the present application, an epoxy resin material that cures at room temperature may be applied to the surface of the circuit pattern 3 on the back surface of the ceramic substrate 1 to form an insulating film.

[0008]

As described above, in the surface mount hybrid IC according to the present invention, the circuit pattern on the bottom surface of the surface mount hybrid IC is insulated by the insulating film so that the circuit pattern of the surface mount hybrid IC is separated from the circuit pattern of the printed wiring board. Therefore, even if a fine protrusion on the circuit pattern of the printed wiring board or a foreign substance such as metal powder is mixed in at the time of soldering, both patterns are not short-circuited. The effect is great.

[Brief description of drawings]

FIG. 1 is a surface mount hybrid I applied to the present invention.
It is a bottom view showing C.

FIG. 2 is a surface mount hybrid I applied to the present invention.
It is a side sectional view showing C.

FIG. 3 is a side sectional view showing a conventional surface mount hybrid IC.

[Explanation of symbols]

 1 Ceramic substrate 2 Circuit pattern 3 Circuit pattern 4 Electrode 5 Shell 6 Insulating film

Claims (4)

[Claims] 1. A surface mount hybrid IC comprising a circuit pattern formed on both sides of a substrate and electrodes formed on the sides thereof, chip components mounted on the front side, and a shell covering the front side of the substrate to form an insulating film on the back side of the substrate. A surface mount hybrid IC, which is formed by insulating the circuit pattern on the back surface of the substrate from the circuit pattern on one printed wiring board by the insulating film. 2. The surface mount hybrid IC according to claim 1, wherein a conductive paste is applied and baked on the back surface of the substrate. 3. The surface mount hybrid IC according to claim 1, wherein an insulating sheet is attached to the back surface of the substrate. 4. The surface mount hybrid IC according to claim 1, wherein an epoxy resin is applied to the back surface of the substrate.