JPH03190195A - Circuit device shielding structure and formation of shield - Google Patents

Abstract

PURPOSE:To realize a shielding structure excellent in shielding effect by a method wherein terminal leads are extracted out of an insulating coating layer, and a conductive film is connected to a terminal lead which serves as a grounding terminal through a terminal piece provided between the insulating coating layer and the conductive film. CONSTITUTION:The surface of a circuit device 2 is electrically insulated through an insulating coating film 6 and covered with a conductive film 8, and the circuit device 2 can be shielded by the conductive film 8. The conductive film 8 is connected to a terminal lead 40 which serves as a grounding terminal through the intermediary of a grounding lead 7. Other terminal leads other than the terminal lead which serves as a grounding terminal are selectively removed, a terminal piece electrically connected to the terminal lead which is used as a grounding terminal is installed on the upside of an insulating coating layer, a conductive film is formed thereon, and a circuit device is covered with a conductive film to serve as a shielded case.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a shield structure and a shield forming method for a circuit device used in a hybrid integrated circuit or the like in which a plurality of electronic components are mounted on a circuit board.

[Conventional technology]

Conventionally, circuit devices such as hybrid integrated circuits require shielding depending on the circuit to be mounted.
A shield case or the like is used, and for example, a method is adopted in which a circuit device is housed in a metal case to electrostatically or magnetically isolate it from an external circuit.

[Problem to be solved by the invention]

By the way, in the case of a metal case, manufacturing costs are high because a metal plate is molded using a mold or the like into a form having a shape, volume, etc. corresponding to the circuit device to be housed. In addition, when a metal case is used, an insulating gap is required between the built-in circuit device components, which increases the volume.
This prevents miniaturization of the entire device. When attaching the metal case to the circuit board, it is a hassle to make the connection claws formed on the metal case penetrate the circuit board and then solder and fix the metal case to the conductor pattern on the circuit board.

For this reason, a shield structure for a circuit device has been proposed in which the structure is simplified by forming a conductive film in place of the shield case on an insulating coating layer covering the outer surface of the circuit device.

Therefore, the present invention provides a shield structure for a circuit device in which the insulation coating layer and the grounding terminal lead are electrically connected to form a shield structure in which the circuit device and the insulation coating layer are integrated, thereby increasing the shielding effect. The primary purpose is to provide information.

A second object of the present invention is to provide a method for forming a shield for a circuit device that improves the shielding effect.

[Means for Solving the Problems] (Claim 1) That is, in order to achieve the first object, the shield structure of the circuit device of the present invention includes a circuit board (10) having a plurality of electronic components (141, 142, . . 14N) and a plurality of terminal leads (40, 41, 42... 4N) are installed on the circuit device (2), and an insulating coating layer (2) that exposes the terminal leads and covers the peripheral surface of the circuit device. 6), and a terminal piece (
A method for forming a shield for a circuit device according to the present invention is characterized by comprising: a ground lead (7); and a conductive film (8) disposed on the surface of the insulating coating layer to cover the terminal piece. , second
In order to achieve the above purpose, a process of forming a circuit device (2) in which a plurality of electronic components (141, 142...14N) are mounted on a circuit board (10) and a plurality of terminal leads are installed; forming an insulating coating layer (6) covering the circuit board and the electronic components by selectively exposing leads, and electrically connecting the surface of the insulating coating layer to at least one of the terminal leads; The method is characterized by a step of forming a conductive film (8) on the surface of the insulating coating layer except for the other terminal leads after disposing the terminal piece (earth lead 7).

(Function) (Claim 1) In this circuit device, an insulating coating layer is provided on the circumferential surface of the circuit device in which a plurality of electronic components are installed and a terminal lead is attached, and the insulating coating layer A plurality of terminal leads are drawn out, and a conductive film is formed on the surface of the insulating coating layer.

Since the conductive film is connected to a terminal lead used as a grounding terminal through a terminal piece installed between the insulating coating layer and the conductive film, a constant potential can be set through the terminal lead.

In other words, this circuit device realizes a shield structure with high shielding effect.

(Claim 2) The circuit device is formed by mounting necessary electronic components on a circuit board and attaching a plurality of terminal leads to the circuit board. If the surface of this circuit device is coated with an insulating coating layer except for the terminal leads, this constitutes a substantial exterior means for the circuit device, and electrical insulation is achieved with respect to each electronic component and conductor pattern.

Then, selectively remove other terminal leads from the terminal lead used for the grounding terminal, and install a terminal piece electrically connected to the terminal lead used for the grounding terminal on the top surface of the insulating coating layer. By forming a conductive film thereon, the circuit device can be covered with the conductive film, and this is formed as a substantial shield case.

[Example] Hereinafter, the present invention will be described in detail with reference to an example shown in the drawings.

1 to 3 show an embodiment of a shield structure for a circuit device according to the present invention.

The circuit device 2 includes a plurality of terminal leads 4o, 41.42.
...4N is formed, and in this embodiment, the terminal lead 40 is set as a grounding terminal. This circuit device 2
The surface portion of is covered with an insulating coating layer 6 made of an insulating synthetic resin or the like, and an L-shaped ground lead 7 made of a conductor wire or the like is installed as a terminal piece on the surface, and terminal leads 41 to 4N are placed on the surface. The conductive film 8 is installed to avoid this.

The end of the ground lead 7 drawn out from the conductive film 8 is wrapped around and electrically connected to a terminal lead 40 used as a ground terminal, and the connection means may use, for example, solder. I can do it.

As shown in FIG. 2, the circuit device 2 is equipped with a circuit board 10 as a mounting medium for mounting arbitrary electronic components. Conductor patterns 12 and 13 are formed,
A plurality of electronic components 141, 142, 143... 14N such as capacitors and ICs are fixed on the conductive pattern 12, and electrical connections are made with each electrode.
Moreover, on the conductor pattern 12 at the end of the circuit board 10,
Terminal leads 41 to 4N are attached and electrically connected by solder 16. In the case of this embodiment, since the conductor pattern 13 is set as a ground wiring, a terminal lead 40 used as a ground terminal is attached to this conductor pattern 13 and electrically connected with solder 16. . Note that 18 is a solder resist.

Further, as shown in FIG. 2, the conductive film 8 is in contact with a terminal lead 40 used as a ground terminal, and as shown in FIG. It is formed on the surface of the insulating coating layer 6.

With such a configuration, the surface of the circuit device 2 is electrically insulated by the insulating coating layer 6 and the conductive coating 8
This conductive film 8 realizes a shield. The conductive film 8 is connected to a terminal lead 40 used as a ground terminal through an earth lead 7 installed between the insulating coating layer 6 and the conductive film 8, so that conductive film 8 can be conducted through the terminal lead 40. By connecting the conductive film 8 to a reference potential or a ground point, the peripheral surface of the circuit device 2 can be surrounded by an equipotential surface through the conductive film 8, and electrostatically and magnetically connected to adjacent external circuits. It is possible to block the gap between the two.

In addition, in such a shield structure, an insulating coating layer 6 is provided integrally with the circuit device 2, and a conductive coating 8 is provided on the surface of the insulating coating layer 6.
is formed, so there is no waste in terms of shape due to molding of the metal plate, which occurs when a conventional metal case is used, and an optimal shield structure can be realized. Since the shield is formed by the conductive film 8, there is no need for molding work or a mold for the metal case, and when mounting on a circuit board, connection claws are formed in advance on the metal case and connected. Since there is no need to carry out any additional steps, manufacturing costs can also be reduced.

Next, FIGS. 4 and 5 show an embodiment of a method for forming a shield for a circuit device according to the present invention.

As shown in FIG. 4A, the electronic components 141 to 14N are mounted at predetermined mounting positions on the conductor pattern 12.13 formed on the surface of the circuit board 10, and
Terminal leads 40 to 4N are attached, and circuit device 2 is formed with solder 16.

In addition, in the dip treatment of the solder 16, a solder resist 1 is selectively applied to the conductor pattern 12 of the circuit board 10.
8 and identify the appropriate solder dip area.

Next, as shown in FIG. 4(B), the terminal leads 40 to
A resin mold is applied to the surface portion of the circuit device 2 using an insulating resin, including a part of the 4N, to form an insulating coating layer 6. In this case, the insulating coating layer 6 forms a flat surface portion on which the earth lead 7 is to be installed. The molding resin constituting this insulating coating layer 6 includes, for example, epoxy-modified phenol resin, epoxy resin, silicone, polyvinyl,
Any one of polybutadiene or a combination of two or more thereof can be used. The insulating coating layer 6 with high reliability can be formed on the circumferential surface of the circuit device 2 by utilizing the properties of these resins that are liquid at room temperature, have appropriate viscosity, and harden by means such as heating. can. To form the insulating coating layer 6, liquid molding resin is stored in a dip bath, and the circuit board 10, which is the main body of the circuit device 2, and its It is formed by dipping the electronic components 141 to 14N mounted thereon.

Next, as shown in FIG. 4C, an earth lead 7 made of a conductor wire or the like is extended in an L-shape over the surface of the insulating coating layer 6 and fixed using a conductive adhesive. At this time, one end of the ground lead 7 is wound around the terminal lead 40 to be electrically connected.

Next, as shown in FIG. 4(D), mending tape 20 is applied to the terminal leads 41 to 4N exposed from the insulation coating layer 6 as a covering means to cover the vicinity of the insulation coating layer 6. The masking resin 22 is applied thereon to selectively cover the terminal leads 41 to 4N.

The mending tape 20 is, for example, (Dl) in FIG.
Terminal lead 4 used as a ground terminal as shown in
Each terminal lead 4 including a part of the insulation coating layer 6 except 0
Paste 1 to 4N on both the front and back sides of the root part. next,
As shown in FIG. 5 (D2), a part of the insulation coating layer 6 and the terminal leads 41 to 4N are attached so as to cover the mending tape 20 attached to the root part. Masking resin 22 is applied to both the front and back surfaces. A vinyl strip mask resin can be used as the masking resin 22, and when such a resin is used, the curing condition is set at an ambient temperature of 130°C and left in that temperature for 10 minutes. In this way, an appropriate cured state can be obtained.

Next, as shown in FIG. 4 (E) and FIG. A conductive film 8 is formed and coated so as to cover it. For this conductive film 8, Cu paste or the like can be used as a conductive paste.

For example, when Cu paste is used, the circuit device 2 on which the insulating coating layer 6 is formed is immersed in the Cu paste stored in a dip tank, and the Cu paste is applied to a thickness of about IIIIIIl, after which the curing conditions are set. for 30 to 60 minutes,
By setting the ambient temperature to 150''C, a suitable cured state can be obtained.

Next, when the mending tape 20 is peeled off and the masking resin 22 is removed together with the mending tape 20, the conductive film 8 adhering to the masking resin 22 is removed, and the circuit device shown in FIGS. 1 to 3 is removed. A second shield structure is realized.

According to the above-described formation method, a shield structure with a high shielding effect can be extremely easily realized in the circuit device 2.

In the example, before forming the conductive film 8, the end of the ground lead 7 was wrapped around the terminal lead 40 for electrical connection. However, after forming the conductive film 8, the ground lead 7 was 40 for electrical connection.

Next, FIG. 6 shows another embodiment of the method for forming a shield for a circuit device according to the present invention.

In the embodiment described above, the conductive film 8 was formed using a liquid conductor such as Cu paste, but the present invention can also be applied to a case where the conductive film 8 is formed by electroless plating.

That is, as shown in FIG. 6(A), after installing the insulating coating layer 6 on the circuit board 10 side of the circuit device 2, the terminal leads 4
After installing the mending tape 20 that selectively covers 1 to 4N and the masking resin 22, a catalyst 24 for electroless plating is applied to a part of the masking resin 22 and the surface of the insulating coating layer 6.

In the electroless plating process, as shown in (D2) in FIG. After the leads 7 are installed, a degreasing process is performed as a pretreatment for the electroless plating process, followed by an etching process, a surface activation process, and a cleaning process, and then the catalyst 24 is installed. That is, the degreased circuit device 2 is immersed in xylene for about 1 minute, then immersed in methanol for about 1 minute, immersed in about 5% HCJ2 solution, washed with water, and then immersed in xylene for about 1 minute. Perform some sensitizer treatment. For the sensitizer, for example, S n CL 2 H2O: 20 to 40 g #! H
C12: Use 10 to 20 m 1/1.

After the sensitizer treatment, the insulating coating layer 6 of the circuit device 2 is washed with water, and then an activator treatment is performed for about 1 minute. The activator includes, for example, Pd(42.2H20:
0.1~0.3 g/IHCn: 3~5mff
Use 1/j2.

Next, after washing the insulating coating layer 6 which has been subjected to the sensitizer treatment with water, the mending tape 20 and the masking resin 22 are removed in the same manner as in the previous embodiment, as shown in FIG. 6(B). , selectively removes the catalyst 24 and performs an electroless plating process. In this case, since the mending tape 20 and the masking resin 22 are selectively installed on the terminal leads 41 to 4N side except for the terminal lead 40, the catalyst 24 is applied to the terminal lead 40 together with the insulating coating layer 6. has been done. Then, the circuit device 2 is immersed in a plating solution for electroless plating, and the conductive film 8 is formed by electroless plating on the portion to which Pd as the catalyst 24 is attached. The conductive film 8 is formed, for example, by electroless plating at a rate of about 4 μm/h, and the electroless plating includes, for example, Cu5O-:0.04M, EDTA-4
Using a plating solution with a composition consisting of H: 0.09M, HCHO: 0.06M, and other additives and set at pH = 12.2, the temperature was set at 70 ° C, and after the treatment, If the circuit device 2 is washed with water, the shield structure of the circuit device 2 can be realized by electroless plating in the same manner as in the above embodiment.

According to the above formation method, the catalyst 24 can be selectively removed by removing the masking resin 22.
By electroless plating except for the terminal leads 41 to 4N, the conductive film 8 necessary for the surface of the insulating coating layer 6 and a part of the terminal lead 40 continuous to the insulating coating layer 6 is formed, for example, 5
Formed with a Cu layer of ~25 μm, a shield structure with high shielding effect can be realized in the circuit device 2 very easily.

As a result, the conductive film 8 is formed to cover the ground lead 7 installed on the surface of the insulating coating layer 60, and the ground lead 7 and the conductive film 8 are electrically connected. In the case of , 2, if a conductive film 8 is formed on the terminal lead 40 around which the ground lead 7 is wound by electroless plating, the ground lead 7 and the terminal lead 40 can be electrically strengthened by the formation of the conductive film 8. can be connected to. In addition, in this example, a case was explained in which Pd was used as a catalyst to be selectively attached to the surface of the insulating coating layer 16.
Even if Ag, Au, PC, etc. are used, a metal layer suitable for a shield, that is, a conductive film 8 can be formed.

Then, after installing the mold resin forming the insulating coating layer 6, if wax is impregnated inside it, the insulating coating layer 6
Moisture resistance is further improved.

Further, although not shown, an insulating coating layer may be further provided on the conductive film 8, and in this way, the conductive film 8 can be protected from damage.

In the embodiments shown in FIGS. 4 to 6, the mending tape 20 and the masking resin 22 are used together as coating means to selectively form the conductive film 8. You may also use only

Further, in the embodiment, a case has been described in which a conductor wire is used as the ground lead 7 as a terminal piece, but the same effect can be expected even if a plate-shaped conductor foil is used.

[Effects of the Invention] As explained above, according to the present invention, the following effects can be obtained.

(a) According to the shield structure of the circuit device of the present invention, since the conductive film is formed on the surface of the insulating coating layer of the circuit device to obtain the shield structure, the conductive film installed along the surface of the circuit device This increases the shielding effect, and by excluding the shield case, the shield structure can be simplified and miniaturized, and costs can be reduced.

(b) According to the method for forming a shield for a circuit device of the present invention, a shield structure with high shielding effect can be realized extremely easily and at low cost.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of the shielding structure of the circuit device of the present invention, and FIG. 2 is a plan view of the shielding structure of the circuit device shown in FIG. 1.
■ Line cross-sectional view, Figure 3 shows the shield structure of the circuit device shown in Figure 1.
[-I [[ Line sectional view, FIG. 4 is a sectional view showing an embodiment of the method for forming a shield for a circuit device of the present invention, and FIG. 5 is a sectional view showing an embodiment of the method for forming a shield for a circuit device of the present invention. FIG. 6 is a plan view and a sectional view showing another embodiment of the method for forming a shield for a circuit device according to the present invention. 2... Circuit device 6... Insulating coating layer 7... Earth lead (terminal piece) 8... Conductive film 10... Circuit board 40... Terminal lead (earth terminal) 41.42・・・
・4N...Terminal lead 141.142.143...
14N...Subparts/Electric Figure 1 (Example of shield structure for circuit device) Figure 6

Claims (2)

[Claims] 1. A circuit device in which a plurality of electronic components and a plurality of terminal leads are installed on a circuit board; an insulating coating layer covering a peripheral surface of the circuit device with the terminal leads exposed; and a circuit device installed on a surface of the insulating coating layer. and a terminal piece electrically connected to at least one terminal lead among the terminal leads, and a conductive film disposed on the surface of the insulating coating layer covering the terminal piece. Features a shield structure for circuit devices. 2. forming a circuit device in which a plurality of electronic components are mounted on a circuit board and a plurality of terminal leads are installed; and forming an insulating coating layer covering the circuit board and the electronic components by selectively exposing the terminal leads. and at least one of the terminal leads on the surface of the insulating coating layer.
a step of forming a conductive film on the surface of the insulating coating layer excluding other terminal leads after arranging a terminal piece to be electrically connected to the circuit device. How to form a shield.