JPH10154857A - Flexible printed circuit board device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible printed circuit board device which is stable against noise and has an excellent heat radiating property. SOLUTION: A flexible printed circuit board device is constituted by sticking a metallic plate 2 to part of a flexible printed circuit board 1 and electrically connecting the first potential section 7 of a circuit pattern 3 to the metallic plate 2 through the through hole of the potential section 7. In addition, a through hole having such a size that can pass the semiconductor element 8 of the circuit board 1 is provided and, in the through hole, the element 8 is fixed to the metallic plate 2 with a conductive adhesive, etc., and connected to the circuit pattern 3 through thin metallic wires 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a flexible printed circuit board device in which a metal plate and a flexible printed circuit board are bonded and integrated.

[0002]

2. Description of the Related Art FIG. 11 shows a partial cross-sectional view of a conventional technique. Metal plate 101 made of aluminum or iron
An insulating layer 102 made of an epoxy resin is formed thereon. An inner circuit pattern 103 is formed of copper foil on the insulating layer 102, and an insulating layer 104 is formed so as to cover the inner circuit pattern 103. An upper circuit pattern 105 is formed on the insulating film 104 with a copper foil. The connection between the inner circuit pattern 103 and the upper circuit pattern 105 is made by forming a through hole 106. Components such as the semiconductor element 108 and the capacitor chip 111 are mounted on the upper layer circuit pattern 105. The semiconductor element 108 is connected to the upper layer circuit pattern 105 by wire bonding of a thin metal wire 109 such as a gold wire or an aluminum wire.
11 is connected to the upper circuit pattern 105 by soldering or the like. The ground potential portion of the inner layer circuit pattern 103 is connected to the ground electrode of the upper layer circuit pattern 105 via a through hole 106. This ground electrode is formed on a metal plate 101 from which a part of the insulating layer has been removed, such as a gold wire or an aluminum wire. The metal wires 109 are connected by wire bonding.
Here, the protective film and the like are omitted and not shown.

[0003]

As described above, in the prior art, the ground potential portion of the inner layer circuit pattern 103 is connected to the ground electrode of the upper layer circuit pattern 105 through the through hole 106, and the metal plate 101 is connected to the ground potential. Since the connection is made by wire bonding, not only the wiring becomes complicated, but also the length of the wiring pattern becomes long, so that the resistance of the wiring pattern becomes large and there is a problem that it is susceptible to noise. Furthermore, since the heat conduction path of the semiconductor element reaches the metal plate via the insulating layer having a large thermal resistance, there is a problem in heat dissipation.

It is a first object of the present invention to provide a flexible printed circuit board device which is stable against noise and has excellent heat dissipation. It is a second object of the present invention to provide a flexible printed circuit board device in which a warp stress generated due to heat dissipation of a semiconductor element, attachment to another device, or the like is cancelled, and no warp stress occurs in the semiconductor element and its periphery.

[0005]

In order to achieve the above object, in a flexible printed circuit board device in which a metal plate and at least a part of a flexible printed circuit board are bonded and integrated, a circuit of the flexible printed circuit board is provided. The first potential portion and the metal plate are electrically connected via a through hole provided in the first potential portion of the pattern. Further, it is preferable that a through hole having a size through which the semiconductor element penetrates is provided in the flexible printed circuit board, and the semiconductor element is fixed to the metal plate and electrically connected in the through hole. Further, a plurality of through holes are provided in the first potential portion of the circuit pattern of the flexible printed circuit board, and the first potential portion, the semiconductor element on the first potential portion and the metal plate are fixed and electrically connected through the through holes. It is also effective to connect to.

[0006] With this configuration, the connection between the metal plate and the first potential portion of the circuit pattern can be made with the shortest length, and the semiconductor element can be directly or through-hole provided in the first potential portion. Connected to the metal plate through
A flexible printed circuit board device that is stable against noise and has excellent heat dissipation can be provided. Further, a groove is provided on one of the surface of the metal plate to be bonded to the flexible printed circuit board and the surface on the opposite side. Grooves may be provided on both sides of the surface of the metal plate to be bonded to the flexible printed circuit board and the opposite surface. Further, a groove may be provided in the metal plate so as to be located between a mounting hole for mounting to another device and the semiconductor element. It is effective to provide a groove in the metal plate so as to be located between the semiconductor elements.

[0007] With such a configuration, a difference in expansion coefficient between the metal plate, the flexible printed circuit board, and the adhesive is generated as a warp stress due to heat generation of the semiconductor element, but the warp stress is canceled by the groove formed in the metal plate. Also, when the flexible printed circuit board is mounted on another device, a warp stress is generated around the mounting hole, but the warp stress is canceled by the groove formed in the metal plate, so that the warp stress reaches the semiconductor element and its periphery. It is possible to provide a flexible printed circuit board device that is not required.

[0008]

FIG. 1 is a structural view showing a first embodiment of the present invention, wherein FIG. 1 (a) is a plan view and FIG. 1 (b) is a side view. The flexible printed circuit board 1 usually has a thickness of 0.018 to 0.1 mm, and a part thereof is bonded to a metal plate 2 of aluminum, copper, stainless steel or the like with an epoxy or polyester adhesive 5. The thickness of the metal plate 2 is, for example, 1 to 2 mm. A single-layer or multi-layer circuit pattern 3 is formed of copper foil on the flexible printed circuit board 1, and external connection terminals 4 for connecting to other external devices are provided. It is placed on top and connected. Further, the flexible printed circuit board 1 is provided with a first potential portion 7 in the circuit pattern 3, and has the same potential as the metal plate 2 by a through hole provided in the first potential portion 7. Usually, the first potential section is a ground potential. The semiconductor element 8 is directly fixed and electrically connected to the metal plate 2 at a predetermined hollow portion of the flexible printed circuit board 1. The electrode portion of the semiconductor element 8 and the circuit pattern 3 are connected by a thin metal wire 9 such as a gold wire or an aluminum wire. Although a coating resin for protecting these is applied, it is not shown. A mounting hole for mounting with another device is provided, but is not shown.

FIG. 2 is a sectional view of the first potential portion 7 of FIG. For example, an upper layer circuit pattern 13 is formed of copper foil on one surface of a base film 16 made of a polyimide film having a thickness of 25 μm, a cover layer 15 made of a polyimide film is provided, and an inner layer made of copper foil is formed on the other surface of the base film 16. The circuit pattern 14 is formed, and a cover layer 19 made of a polyimide film is provided. A through-hole is provided in a portion of the upper circuit pattern 13 where the cover layer 15 is partially removed, and a through-hole plating 17 is applied to a side surface of the through-hole.
This through-hole plating is, for example, copper plating.
The through-hole plating 17 is preferably applied to a part of the surface of the upper circuit pattern in order to complete the connection. The upper circuit pattern 13 and the inner circuit pattern 14 are electrically connected by through-hole plating 17. The above components show a part of the flexible printed circuit board 1. The cover layer 19 is bonded to the metal plate 2 with the adhesive 5
Are pasted together. The through-hole portion is not bonded by the adhesive 5 and becomes a non-bonded portion 6. The non-adhesive portion 6 of this through hole is electrically connected to the metal plate 2 with a conductive adhesive or solder.

FIG. 3 is a sectional view of a portion where the semiconductor element 8 of FIG. 1 is fixed to the metal plate 2. An upper layer circuit pattern 13 is formed on one surface of the base film 16, a cover layer 15 is provided on a predetermined portion of the upper layer circuit pattern 13, and an inner layer circuit pattern 14 is formed on the other surface of the base film 16. Is provided.
A through-hole having a size to penetrate the semiconductor element 8 is provided, and a through-hole plating 1 is formed on a side surface of the through-hole.
7 is given. The upper circuit pattern 13 and the inner circuit pattern 14 are electrically connected by through-hole plating 17. The cover layer 19 is bonded to the metal plate 2 with the adhesive 5
Are pasted together. The semiconductor element 8 is fixed to and electrically connected to the semiconductor element bonding portion 10 of the metal plate 2 through, for example, a conductive adhesive or solder 18 through the through hole. This conductive adhesive or solder 18 is also connected to the through-hole plating 17. Semiconductor element 8
And the upper circuit pattern 13 are connected by a thin metal wire 9 such as a gold wire or an aluminum wire.

With such a configuration, it is possible to obtain a flexible printed circuit board device which is stable against noise and excellent in heat dissipation. 4A and 4B are configuration diagrams showing a second embodiment of the present invention. FIG. 4A is a plan view, and FIG. 4B is a side view. FIG. 5 is a sectional view of a portion of the semiconductor device of FIG.

FIG. 6 is a plan view of the first potential portion in the case of FIG. In these figures, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. The first potential portion 67 of the flexible printed circuit board 1 is formed of copper foil as a part of the circuit pattern 3, and a part thereof is joined to the terminal 64 of the external terminal board 60 by solder or the like. FIG. 6 is a plan view showing an example in which 21 circular through holes 66 are provided in a portion of a dotted line 80 on which the semiconductor element 8 is mounted on the first potential portion 67, and FIG. FIG. 2 is a sectional view showing a semiconductor element 8
And the first potential portion 67 and the metal plate 2 are fixed and electrically connected with a conductive adhesive or solder 68 or the like.

FIG. 7 shows an example of a plan view of a first potential portion 67 having four rectangular through holes 76 in a portion indicated by a dotted line 80. FIGS. 6 and 7 show circular and rectangular shapes of the through-holes provided in the first potential portion, but are not limited thereto. With this configuration, it is possible to obtain a flexible printed circuit board device that is stable against noise and has excellent heat dissipation, as in the first embodiment.

FIG. 8 is a structural view showing a third embodiment of the present invention. FIG. 8A is a plan view, and FIG. 8B is a side view. A circuit pattern is formed on the flexible printed circuit board 21 and a semiconductor element 28 and the like are mounted thereon to constitute a circuit. A coating resin 30 is applied for protection. Flexible printed circuit board 21
In this case, a groove 50 is provided on the surface opposite to the surface of the metal plate 22 bonded with the adhesive 25. A mounting hole 40 for mounting to another device is provided. In this embodiment, the groove 50 is formed into a V-shape by machining, but the processing does not damage the flexible printed circuit board 21 due to the formation of the groove 50.

It is effective to provide the groove between the mounting hole 40 and the semiconductor element 28, between the semiconductor elements 28, and the like. As a method of forming the groove, a method by chemical corrosion (etching) is also possible in addition to the above-described machining.
A difference in expansion coefficient between the metal plate 22, the flexible printed circuit board 21, and the adhesive 25 is generated as warpage stress due to heat generation of the semiconductor element 28. Since the warpage stress is canceled by the groove 50, the semiconductor element 28 and its surroundings are removed. Does not reach the warp stress. Therefore, it is possible to prevent cracking of the semiconductor element and separation of the bonding surface between the coating resin and the flexible printed circuit board 21. In addition, when the other device is warped and attached to another device in the vicinity of the mounting hole 40 when the screw is tightened with the mounting hole 40, the groove 5 may be used.
Since the warp stress is canceled by 0, the warp stress does not reach the semiconductor element 28 and its surroundings.

FIG. 9 is a side view showing a fourth embodiment of the present invention. Flexible printed circuit board 21 and adhesive 2
5 shows a case where a groove 50 is provided on the surface of the metal plate 22 bonded together. The groove 50 in this case is U-shaped. This U-shaped groove 50 is preferably formed by U-shaped pressing. FIG. 10 is a side view showing a fifth embodiment of the present invention. This is a case where the heat generated by the semiconductor element 28 is small and warpage stress due to heat is not a problem, and mainly corresponds to the screw tightening stress. The groove 50 is provided between the mounting hole 40 and the semiconductor element 28.

FIGS. 8 to 10 show an embodiment in which a groove is provided on one surface of a metal plate, but grooves may be provided on both surfaces of the metal plate. Although the V-shape and U-shape are shown as the cross-sectional shapes of the groove, the present invention is not limited thereto.

[0018]

According to the present invention, the first potential portion and the metal plate are electrically connected to each other by the through holes provided in the first potential portion of the circuit pattern of the flexible printed circuit board. A through hole of a size through which the semiconductor element penetrates is provided and the semiconductor element is fixed to a metal plate and electrically connected in this through whirl,
A plurality of through holes are provided in the first potential portion of the circuit pattern of the flexible printed circuit board, and the first potential portion, the semiconductor element on the first potential portion, and the metal plate are fixed and electrically connected through the through holes. Therefore, it is possible to obtain a flexible printed circuit board device which is stable against noise and excellent in heat dissipation. Furthermore, by providing a groove on the surface of the metal plate in contact with the flexible printed circuit board or on any surface of the back surface, or on both surfaces, the groove cancels out the heat generated by the heat generation of the semiconductor element and the warpage stress caused by attachment to another device, It is possible to obtain a flexible printed circuit board device in which a warp stress does not occur in a semiconductor element and its periphery.

[Brief description of the drawings]

1A and 1B are configuration diagrams showing a first embodiment, wherein FIG. 1A is a plan view and FIG. 1B is a side view.

FIG. 2 is a cross-sectional view of a first potential unit in FIG.

FIG. 3 is a sectional view of a part of the semiconductor device of FIG. 1;

4A and 4B are configuration diagrams showing a second embodiment, wherein FIG. 4A is a plan view and FIG. 4B is a side view.

FIG. 5 is a sectional view of a portion of the semiconductor device of FIG. 4;

FIG. 6 is a plan view of a first potential unit in FIG. 5;

FIG. 7 is a plan view of a first potential portion having a rectangular through hole.

8A and 8B are configuration diagrams showing a third embodiment, in which FIG. 8A is a plan view and FIG. 8B is a side view.

FIG. 9 is a side view showing a fourth embodiment.

FIG. 10 is a side view showing a fifth embodiment.

FIG. 11 is a partial cross-sectional view of a conventional metal insulating substrate.

[Explanation of symbols]

 1, 21: Flexible printed circuit board 2, 22: Metal plate 3: Circuit pattern 4: External connection terminal 5, 25: Adhesive 6: Non-adhesive part 7 67: First potential part 8, 28: Semiconductor element 9, 29 : Metal thin wire 10: semiconductor element bonding part 11: capacitor chip 13: upper layer circuit pattern 14: inner layer circuit pattern 15, 19: cover layer 16: base film 17: through-hole plating 18, 68: conductive adhesive 30: coating resin 40: Mounting hole 50: Groove

Claims (7)

[Claims] 1. A flexible printed circuit board device in which a metal plate and at least a part of a flexible printed circuit board are bonded and integrated with each other, through a through hole provided in a first potential portion of a circuit pattern of the flexible printed circuit board. And electrically connecting the first potential portion and the metal plate with each other. 2. A flexible printed circuit board having a through hole through which a semiconductor element penetrates, wherein the semiconductor element is fixed to a metal plate and electrically connected in the through hole. The flexible printed circuit board device according to the above. 3. A plurality of through holes are provided in a first potential portion of a circuit pattern of a flexible printed circuit board, and the first potential portion, a semiconductor element on the first potential portion, and a metal plate are fixed through the through holes. 2. The flexible printed circuit board device according to claim 1, wherein the flexible printed circuit board device is electrically connected. 4. A flexible printed circuit board device in which a metal plate and at least a part of a flexible printed circuit board are bonded and integrated, wherein a surface of the metal plate bonded to the flexible printed circuit board and a surface on the opposite side thereof are bonded. A flexible printed circuit board device, wherein a groove is provided on any one of the surfaces. 5. The flexible printed circuit board device according to claim 4, wherein grooves are provided on both sides of the surface of the metal plate bonded to the flexible printed circuit board and the opposite surface. 6. The flexible printed circuit board device according to claim 4, wherein a groove is provided in the metal plate so as to be located between the mounting hole for mounting to another device and the semiconductor element. 7. The flexible printed circuit board device according to claim 4, wherein a groove is provided in the metal plate so as to be located between the semiconductor elements.