JP2020155537A - Wiring board with metal piece - Google Patents

Abstract

To provide a wiring board with a metal piece suppressing the corrosion of a joint portion.SOLUTION: A wiring substrate 3 with a metal piece includes: a flexible printed board 1 that has a first coverlay 10 formed with a first opening portion 10a, a second coverlay 20 formed with a second opening portion 20a, and a wiring pattern 30 sandwiched between the first coverlay 10 and the second coverlay 20; and a metal piece 2. The wiring pattern 30 has a through-hole 32 at least partially overlapped with the first opening portion 10a and the second opening portion 20a, and a projecting portion 33 that projects out toward the inside of the through-hole 32. The projecting portion 33 is jointed to the metal piece 2.SELECTED DRAWING: Figure 1

Description

The present invention relates to a wiring board with a metal piece.

Conventionally, as shown in Patent Document 1 below, a wiring board with a metal piece including a wiring board and a metal piece bonded to the wiring board has been known.

Japanese Unexamined Patent Publication No. 2000-307202

In this type of wiring board with a metal wire, corrosion at the joint between the wiring board and the metal piece may become a problem. In particular, if water adheres to the joint, galvanic corrosion or corrosion due to an oxygen concentration cell may occur.

The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a wiring board with a metal piece in which corrosion of a joint is suppressed.

In order to solve the above problems, the wiring board with a metal piece according to one aspect of the present invention includes a first coverlay having a first opening, a second coverlay having a second opening, and the first coverlay. A flexible printed circuit board having a wiring pattern sandwiched between the 1 coverlay and the 2nd coverlay and a metal piece are provided, and the wiring pattern is the first opening and the second opening in a plan view. It has a through hole that overlaps at least a part of the opening, and a protrusion that projects inward of the through hole, and the protrusion is joined to the metal piece.

According to the above aspect, when the sealing resin is injected from the first opening of the first coverlay, the resin is provided so as to surround the joint with the metal piece formed in the protruding portion of the wiring pattern. Can be done. As a result, the joint portion is sealed with a resin to block contact with the outside air, and corrosion of the joint portion can be suppressed. Further, when the protruding portion is joined to the metal piece, stretching deformation and internal tensile stress are unlikely to occur in the metal constituting the wiring pattern. Therefore, the reliability of the joint can be improved.

Here, the tip end portion of the protruding portion may be joined to the metal piece.

In this case, the joint portion between the protruding portion and the metal piece can be arranged away from the base end portion (the portion connected to the inner peripheral edge of the through hole) of the protruding portion. As a result, it becomes easier to provide the resin on the back side of the base end portion, and the joint portion can be more reliably surrounded by the resin and sealed.

Further, the protruding portion may have a connecting portion that connects the inner peripheral edge of the through hole and the tip portion, and the width of the connecting portion may be smaller than that of the tip portion.

In this case, the range in which the joint portion can be arranged at the tip portion can be increased to increase the joint strength. In addition, the joint portion can be easily arranged isotropically at the tip portion, and the reliability of the joint can be further improved.

Further, the tip portion has an arcuate contour, and a plurality of joints between the protrusion and the metal piece may be provided along the arcuate contour at intervals.

In this case, a plurality of joints can be arranged isotropically, and the force acting on each joint can be made uniform. Therefore, the reliability of joining can be further improved.

Further, the protruding portion may have a straight portion extending linearly toward the inside of the through hole, and the straight portion may be joined to the metal piece.

In this case, the length of the joint can be increased. Further, when the protruding portion is deformed toward the metal piece, the straight portion is unlikely to be displaced in a direction orthogonal to the direction in which the straight portion extends. Therefore, the alignment at the time of joining becomes easier, and the difficulty of manufacturing the wiring board with a metal piece can be reduced.

According to the above aspect of the present invention, it is possible to provide a wiring board with a metal piece that suppresses corrosion of the joint.

It is sectional drawing of the wiring board with a metal piece which concerns on this Embodiment. It is a figure explaining the manufacturing method of the wiring board with a metal piece of FIG. It is a top view of FIG. 2 (f). It is a figure explaining the manufacturing method of the wiring board with a metal piece of FIG. 1, and shows the process following FIG. It is a top view of the wiring board with a metal piece of FIG. It is a top view of the wiring board with a metal piece which concerns on 1st modification. It is a top view of the wiring board with a metal piece which concerns on the 2nd modification, and shows the state before filling with resin. It is a top view of the wiring board with a metal piece which concerns on 3rd modification, and shows the state before filling with resin. It is a top view of the wiring board with a metal piece which concerns on 4th modification, and shows the state before filling with resin. It is a top view of the wiring board with a metal piece which concerns on 5th modification, and shows the state before filling with resin. It is a top view of the wiring board with a metal piece which concerns on 6th modification, and shows the state before filling with resin.

Hereinafter, the wiring board with a metal piece of the present embodiment will be described with reference to the drawings.
As shown in FIG. 1, the wiring board 3 with a metal piece includes a flexible printed circuit board (FPC) 1 and a metal piece 2 joined to the wiring pattern 30 of the flexible printed circuit board 1.
The flexible printed circuit board 1 has a first cover ray 10, a second cover ray 20, and a wiring pattern 30. The flexible printed circuit board 1 is rich in flexibility, and is configured so that the wiring pattern 30 functions even when it is greatly bent.

(Direction definition)
In the present embodiment, the thickness direction of the flexible printed circuit board 1 is simply referred to as the thickness direction. Further, along the thickness direction, the flexible printed circuit board 1 side is referred to as an upper side, and the metal piece 2 side is referred to as a lower side. Viewing from the thickness direction is called plan view.
The flexible printed circuit board 1 has a laminated structure in which the second cover lay 20, the wiring pattern 30, and the first cover lay 10 are laminated in this order from the bottom to the top.

(Flexible printed circuit board)
The first coverlay 10 has a first insulator 11 and a first adhesive layer 12 applied to the first insulator 11. The second coverlay 20 has a second insulator 21 and a second adhesive layer 22 applied to the second insulator 21. The first insulator 11 is located on the uppermost layer of the flexible printed circuit board 1, and the second insulator 21 is located on the lowermost layer of the flexible printed circuit board 1.
The first insulator 11 and the second insulator 21 are formed in a thin film shape. As the insulators 11 and 21, flexible and insulating materials such as polyimide and liquid crystal polymer can be used. In this embodiment, a polyimide film having a thickness of 25 μm is used as the insulators 11 and 21.

The first adhesive layer 12 adheres the wiring pattern 30 and the first insulator 11, and the second adhesive layer 22 adheres the wiring pattern 30 and the second insulator 21. As the material of the adhesive layers 12 and 22, resins having insulating properties and adhesive properties such as epoxy-based, acrylic-based, and polyimide-based resins can be used. In the present embodiment, an epoxy adhesive having a thickness of 25 μm is used as the adhesive layers 12 and 22.

The first coverlay 10 is formed with the first opening 10a, and the second coverlay 20 is formed with the second opening 20a. The openings 10a and 20a can be formed by subjecting the coverlays 10 and 20 to laser processing, mold processing, NC processing (Numerical Control machining) and the like. The first opening 10a and the second opening 20a are arranged at positions where they overlap each other when viewed from the thickness direction. The first opening 10a and the second opening 20a are formed in a square shape, and the first opening 10a is larger than the second opening 20a. The shapes, sizes, arrangements, etc. of the openings 10a and 20a may be changed as appropriate.

The wiring pattern 30 is sandwiched between the first cover ray 10 and the second cover ray 20.
As the material of the wiring pattern 30, a thin film of a conductive metal such as copper, stainless steel, or aluminum can be used. In this embodiment, an electrolytic copper foil having a thickness of 35 μm is used as the wiring pattern 30. The wiring pattern 30 can be formed by, for example, a subtractive method or a semi-additive method.

In the present embodiment, the portion of the wiring pattern 30 exposed from between the first cover lay 10 and the second cover lay 20 through the openings 10a and 20a is referred to as an exposed portion 31. A through hole 32 and a protruding portion 33 are formed in the exposed portion 31 (see FIG. 3). In a plan view, the through hole 32 overlaps the first opening 10a and the second opening 20a, and the protruding portion 33 projects inward of the through hole 32. A part of the protruding portion 33 is joined to the metal piece 2 to form a joint portion 34. The metal piece 2 and the wiring pattern 30 are electrically connected by the joint portion 34. Details of the protrusion 33 and the joint 34 will be described later.

Although not shown, electronic components may be mounted on the flexible printed circuit board 1. The electronic component may be a capacitor, a resistor, a thermistor, an IC, an LED, or the like. When mounting an electronic component, an opening for electrically connecting the electronic component and the wiring pattern 30 may be provided in the first cover lay 10 or the second cover lay 20.

(Metal piece)
The metal piece 2 is formed of a metal such as aluminum into a film shape, a rod shape, or a plate shape. The material and shape of the metal piece 2 may be changed as appropriate. In the present embodiment, plate-shaped aluminum (A1050) having a thickness of 1 mm is used as the metal piece 2.
The metal piece 2 covers the second opening 20a of the second insulator 21 from below. The metal piece 2 is joined to the joint portion 34 of the wiring pattern 30, and is electrically connected to the wiring pattern 30.

(resin)
As shown in FIG. 1, the wiring board 3 with a metal piece of the present embodiment includes a resin R. As the material of the resin R, a thermosetting resin such as an epoxy resin, an acrylic resin, and a urethane resin, a thermoplastic resin, a UV curable resin, or the like can be used.

The resin R is filled in the inside of the first opening 10a, the inside of the second opening 20a (between the exposed portion 31 and the metal piece 2), and the gap between the flexible printed circuit board 1 and the metal piece 2. There is. Further, the resin R is filled so as to protrude upward from the first opening 10a. Therefore, the resin R covers the opening edge of the first opening 10a from above and is formed in a rivet shape. A part of the resin R is located on the upper surface 11a (upper surface of the first insulator 11) of the flexible printed circuit board 1. A part of the resin R protrudes from the lower surface 21a of the flexible printed circuit board 1 (the lower surface of the second insulator 21). Therefore, a part of the resin R located below the flexible printed circuit board 1 is visible from above (see FIG. 5).

In this way, the joint portion 34 is sealed with the resin R. The resin R located between the flexible printed circuit board 1 and the metal piece 2 is in the form of an extremely thin thin film. The resin R has an effect of fixing the flexible printed circuit board 1 to the metal piece 2 in addition to the effect of sealing the joint portion 34.

(Production method)
Next, an example of a method for manufacturing the wiring board 3 with a metal piece having the above configuration will be described with reference to FIGS. 2 (a) to 2 (f), FIGS. 3 and 4 (a) to 4 (d). .. FIGS. 2 (a) to 2 (f) show steps from manufacturing the flexible printed circuit board 1 to joining the wiring pattern 30 to the metal piece 2. FIG. 3 shows a state after the wiring pattern 30 is joined to the metal piece 2. FIGS. 4A to 4D show a step of filling the resin R.

First, a preparatory step for preparing the flexible printed circuit board 1 is performed. In the preparatory step, as shown in FIG. 2A, the first coverlay 10 and the conductor sheet S are prepared. The first coverlay 10 is provided with a first opening 10a in advance. The first adhesive layer 12 of the first coverlay 10 is in a semi-cured state. The sheet S is a conductive metal foil such as copper, stainless steel, and aluminum.

Next, the first cover lay 10 and the seat S are aligned so as to face each other. Then, as shown in FIG. 2B, the first coverlay 10 and the sheet S are laminated and integrated by a heating press. As a result, the first adhesive layer 12 is cured, and the first coverlay 10 and the sheet S are fixed. The heating press is preferably in the range of, for example, a temperature of 100 to 200 ° C., a pressure of 0.1 to 10 MPa, and a pressurization time of 1 to 120 minutes. Further, if necessary, it may be heated in an oven after the above heating press.

Next, as shown in FIG. 2C, the sheet S integrated with the first coverlay 10 is processed to form the wiring pattern 30. The wiring pattern 30 can be obtained by a subtractive method or laser processing. In the present embodiment, the subtractive method is adopted, and the wiring pattern 30 is formed by etching the sheet S. At this time, a through hole 32 and a protruding portion 33 are formed in the portion (exposed portion 31) of the wiring pattern 30 exposed from the first opening 10a. In this embodiment, the through hole 32 has a substantially square shape (see FIG. 3). However, the shape of the through hole 32 can be changed as appropriate. Further, the through hole 32 and the protruding portion 33 may be formed by mold processing, laser processing, or the like after the wiring pattern 30 is formed.

Next, as shown in FIG. 2D, the second coverlay 20 is arranged below the wiring pattern 30. The second coverlay 20 is provided with a second opening 20a in advance. Then, the first cover lay 10 and the wiring pattern 30 and the second cover lay 20 are positioned and laminated, and integrated by a heating press. As a result, the second adhesive layer 22 is cured, and the members 10, 20, and 30 are fixed (see FIG. 2E). The conditions for the heating press may be the same as when the first coverlay 10 and the sheet S are integrated.

Next, as shown in FIG. 2E, the metal piece 2 is arranged below the integrated first coverlay 10, the wiring pattern 30, and the second coverlay 20.
Then, as shown in FIG. 2 (f), a part of the exposed portion 31 (protruding portion 33) of the wiring pattern 30 and the metal piece 2 are joined (joining step). As a bonding method, resistance welding, ultrasonic bonding, laser welding and the like can be used. At the time of joining, the protruding portion 33 is deformed downward and comes into contact with the metal piece 2 when a jig or the like is pressed against it.

Of the protruding portion 33, the portion joined to the metal piece 2 becomes the joint portion 34. When the joint portion 34 is formed by welding, an alloy layer composed of the wiring pattern 30 and the metal piece 2 is formed on the joint portion 34.

Here, in the present embodiment, as shown in FIG. 3, the protruding portion 33 has a tip portion 33a and a connecting portion 33b. The connecting portion 33b connects the tip portion 33a and the inner peripheral edge of the through hole 32. The joint portion 34 between the wiring pattern 30 and the metal piece 2 is formed at the tip portion 33a. The tip portion 33a is formed in a substantially circular shape and has an arcuate contour. The connecting portion 33b is a straight portion extending linearly toward the inside of the through hole 32. The width of the connecting portion 33b is smaller than the width (outer diameter) of the tip portion 33a. In other words, the protruding portion 33 has a constricted shape.

A plurality of joint portions 34 are provided at intervals along the arcuate contour of the tip portion 33a. In the example of FIG. 3, since the distance between the plurality of joints 34 is substantially equal, it can be said that the joints 34 are isotropically provided at the tip 33a. However, the distance between the joints 34 may be non-uniform, and the number of joints 34 provided at the tip 33a may be one.

In FIG. 3, the joint portion 34 extends inward from the contour of the tip portion 33a. However, the joint portion 34 may extend outward from the contour of the tip portion 33a. Further, in the state after the joining step, the contour of the tip portion 33a is not necessarily a well-organized arc shape as shown in FIG. 3, and may be distorted due to the formation of the joining portion 34. ..

The electronic component may be mounted on the flexible printed circuit board 1 before or after joining the wiring pattern 30 to the metal piece 2.
Next, a method of sealing the joint portion 34 with the resin R will be described with reference to FIGS. 4A to 4D.

First, as shown in FIG. 4A, the position of the nozzle N of the dispenser for pouring out the resin R is aligned with the first opening 10a. The tip of the nozzle N may be located inside the first opening 10a or above the first opening 10a. The distance from the tip of the nozzle N to the metal piece 2 is preferably 0.1 to 5 mm.

Next, as shown in FIG. 4B, the uncured resin R for sealing is poured out from the nozzle N and injected into the first opening 10a (injection step). At this time, the resin R covers the joint portion 34 from above and flows between the connection portion 33b and the metal piece 2. As a result, the resin R surrounds the joint portion 34.

When the resin R is continuously poured out from the nozzle N, it flows into the gap G (see FIG. 4B) between the flexible printed circuit board 1 and the metal piece 2 as shown in FIG. 4C. When the injection is continued, the resin R protrudes from the gap G. After determining visually or by image recognition that the resin R protrudes laterally from the gap G, the injection of the resin R from the nozzle N may be stopped. Alternatively, the injection amount for pouring out the resin R so as to protrude from the gap G may be grasped in advance, and the resin R of this pouring amount may be poured out from the nozzle N.

A minute gap G is formed between the flexible printed circuit board 1 and the metal piece 2 due to the surface roughness of the member, the distortion of the surface, and the like. Then, when the liquid resin R before curing comes into contact with such a minute gap G, a capillary force acts. Due to this capillary force, the resin R enters the gap G and flows so as to spread over the entire lower surface 21a of the flexible printed circuit board 1. For example, in the states of FIGS. 4A and 4B, the flexible printed circuit board 1 may be pushed upward by a jig or the like so that the gap G has an appropriate size.

When the injection of the resin R from the nozzle N is continued, as shown in FIG. 4D, the resin R is formed in the entire space in the first opening 10a and a part of the upper surface 11a of the flexible printed circuit board 1. Adhere to. In this state, the resin R is cured by heating, irradiation with ultraviolet rays, or the like to seal the joint portion 34. By the above steps, the wiring board 3 with a metal piece can be obtained.

As shown in FIG. 5, in a plan view, the resin R protruding upward from the first opening 10a and the resin R protruding upward from the gap between the flexible printed circuit board 1 and the metal piece 2 are separated from each other. It may be.

As described above, in the wiring board 3 with a metal piece of the present embodiment, the first coverlay 10 on which the first opening 10a is formed, the second coverlay 20 on which the second opening 20a is formed, and the first coverlay 20 are formed. A flexible printed circuit board 1 having a wiring pattern 30 sandwiched between the coverlay 10 and the second coverlay 20 and a metal piece 2 are provided. Further, the wiring pattern 30 has a through hole 32 that overlaps at least a part of the first opening 10a and the second opening 20a in a plan view, and a protrusion 33 that projects inward of the through hole 32. The protruding portion 33 is joined to the metal piece 2.

With this configuration, when the resin R is injected from the first opening 10a, the sealing resin R can be provided so as to surround the joint portion 34 formed in the protruding portion 33. As a result, the joint portion 34 is sealed with the resin to block contact with the outside air, and corrosion of the joint portion 34 can be suppressed. Further, when the protruding portion 33 is joined to the metal piece 2, stretch deformation and internal tensile stress are unlikely to occur in the metal constituting the wiring pattern 30. Therefore, the reliability of the joint portion 34 can be improved.

Further, the tip portion 33a of the protruding portion 33 is joined to the metal piece 2. Therefore, the joint portion 34 can be arranged away from the base end portion (the portion connected to the inner peripheral edge of the through hole 32) of the protruding portion 33. Therefore, it becomes easy to provide the resin on the back side of the base end portion of the protruding portion 33, and the joint portion 34 can be more reliably surrounded by the resin R and sealed.

Further, the protruding portion 33 has a connecting portion 33b that connects the inner peripheral edge of the through hole 32 and the tip portion 33a, and the width of the connecting portion 33b is smaller than that of the tip portion 33a. With this configuration, the range in which the joint portion 34 can be arranged at the tip portion 33a can be increased, and the joint strength can be increased. Further, the joint portion 34 can be easily arranged isotropically on the tip portion 33a. Therefore, the reliability of joining can be further improved.

Further, the tip portion 33a has an arcuate contour, and a plurality of joint portions 34 are provided at intervals along the arcuate contour. With this configuration, a plurality of joint portions 34 can be arranged isotropically, and the force acting on each joint portion 34 can be made uniform. Therefore, the reliability of joining can be further improved.

The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, the range in which the resin R is provided may be appropriately changed. In the example shown in FIG. 6, in a plan view, the resin R protruding upward from the first opening 10a and the resin R protruding upward from the gap between the flexible printed circuit board 1 and the metal piece 2 are integrated. In this case, the flexible printed circuit board 1 can be firmly fixed by the metal piece 2 by the resin R.

Further, as shown in FIG. 7, the joint portion 34 may extend along the arcuate contour of the tip portion 33a. In this case, the length of the joint portion 34 can be increased to increase the joint strength, and the joint portion 34 can be formed isotropically to increase the reliability of the joint.

Further, as shown in FIG. 8, the entire protruding portion 33 may be formed in a straight line extending inward of the through hole 32. Then, the linearly extending portion (straight line portion) may be joined to the metal piece 2. In this case as well, the length of the joint portion 34 can be increased. Further, when the protruding portion 33 is deformed toward the metal piece 2, the straight portion is unlikely to be displaced in a direction orthogonal to the direction in which the straight portion extends (the left-right direction in FIG. 8). Therefore, the alignment at the time of joining becomes easier, and the difficulty of manufacturing the wiring board 3 with a metal piece can be reduced. Further, since the shape of the protruding portion 33 is simple, the difficulty of the step of forming the through hole 32 and the protruding portion 33 can be reduced.

Further, as shown in FIG. 9, a plurality of protrusions 33 may be provided inside one through hole 32, and each protrusion 33 may be joined to the metal piece 2. In this case, the number and area of the joints 34 can be increased to further improve the joint strength and the reliability of the joint.

Further, as shown in FIG. 10, the contour of the tip of the protruding portion 33 which is not constricted may be formed into an arc shape, and the joint portion 34 may be provided along the arc-shaped contour.
Further, as shown in FIG. 11, the joint portion 34 may be provided inside the protruding portion 33 (a portion away from the contour) instead of the contour (outer edge portion) of the protruding portion 33. Even in this case, a sealing resin can be provided so as to surround the joint portion 34.

In addition, it is possible to replace the components in the above-described embodiment with well-known components as appropriate without departing from the spirit of the present invention, and the above-described embodiments and modifications may be appropriately combined.

1 ... Flexible printed circuit board 2 ... Metal piece 3 ... Wiring board with metal piece 10 ... 1st coverlay 10a ... 1st opening (opening) 20 ... 2nd coverlay 20a ... 2nd opening (opening) 30 ... Wiring pattern 32 ... Through hole 33 ... Projection 33a ... Tip 33b ... Connection 34 ... Joint R ... Resin

Claims (5)

A flexible having a first coverlay on which the first opening is formed, a second coverlay on which the second opening is formed, and a wiring pattern sandwiched between the first coverlay and the second coverlay. Printed circuit board and
With a piece of metal,
The wiring pattern has, in a plan view, a through hole that at least partially overlaps the first opening and the second opening, and a protrusion that projects inward of the through hole.
A wiring board with a metal piece in which the protruding portion is joined to the metal piece. The wiring board with a metal piece according to claim 1, wherein the tip end portion of the protruding part is joined to the metal piece. The protruding portion has a connecting portion that connects the inner peripheral edge of the through hole and the tip portion.
The wiring board with a metal piece according to claim 2, wherein the width of the connecting portion is smaller than that of the tip portion. The tip has an arcuate contour
The wiring board with a metal piece according to claim 2 or 3, wherein a plurality of joints between the protruding part and the metal piece are provided along the arcuate contour at intervals. The wiring board with a metal piece according to claim 1, wherein the protruding part has a straight part extending linearly toward the inside of the through hole, and the straight part is joined to the metal piece.

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