JP3006523B2 - Laminated circuit board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board having a plating lead cut hole obtained by forming a conductive material of a predetermined thickness on a conductive pattern by electrolytic plating and cutting a plating lead wire used for the electrolytic plating. The present invention relates to a bonded circuit board bonded to a circuit board.

[0002]

2. Description of the Related Art Conventionally, when a circuit on a flexible printed circuit board (hereinafter referred to as FPC) and a semiconductor element are electrically connected by wire bonding, the surface of a pad portion to be wire-bonded is formed by an electrolytic plating method.

[0003] The electrolytic plating method requires a lead wire (plated lead wire) connected to the conductor pattern in order to apply a potential to the conductor pattern to be plated. A predetermined current is applied between the plating lead wire and the outer peripheral electrode to perform electrolytic plating of a predetermined thickness on the conductor pattern. After the electrolytic plating, unnecessary plating leads are cut to form a predetermined circuit.

[0004] At this time, the plating lead wire is usually pulled out to the outer periphery of the circuit board, and after the electrolytic plating, when forming the FPC having a predetermined shape by punching or the like, the plating lead wire is cut at the same time.

[0005] However, as the circuit density increases, it becomes impossible to draw out all of the plating lead wires of the conductor pattern independent from the circuit to the outer periphery of the circuit board because of the space of the FPC.

In this case, the plating leads drawn from each conductor pattern are shared, and after electrolytic plating, FP
A hole (plating lead cut hole) penetrating C is punched out to cut the plating lead wire so that each conductor pattern is made independent.

[0007]

As described above, after the electroplating, a plating-lead cut hole that penetrates the FPC is punched out to cut the plating lead wire to make each conductor pattern independent. The FPC is shown in FIG. As shown in the figure, when it is put on the circuit board and adhered, as shown in part (A), the plated lead wire of the FPC is dripped along the through-hole by punching and approaches the conductor pattern of the circuit board to reduce the dielectric strength. A problem occurred.

Further, as shown in FIG. 3B, there is a problem that the plating lead wire is drooped along the through hole in FIG. 3A and the dielectric strength with respect to the conductor pattern of the circuit board is reduced. In order to solve the problem, a method of applying an insulating adhesive on the conductor pattern of the circuit board to improve the withstand voltage between the lead cut hole and the sag may be considered. However, in this method, the adhesive may protrude to the upper surface of the FPC through the plated lead cut hole, and in particular, a soldering pad or a wire bonding pad for a component or the like exists near the plated lead quad hole of the FPC. In such a case, there has been a problem in that soldering failure or inability to perform soldering occurs due to protrusion of the adhesive, or wire bonding failure or inability to perform wire bonding occurs.

[0009] The present invention solves these problems,
An object of the present invention is to provide a slightly large concave portion or a through hole in a bonding portion of a circuit board or the like corresponding to a plating lead cut hole of an FPC or the like so as to ensure the withstand voltage of the plating lead wire.

[0010]

Means for solving the problem will be described with reference to FIG. In FIG. 1, FPC1
Is a flexible printed circuit board, which has a plating lead cut hole 3 in which the plating lead 2 is cut by making a hole by a through hole.

The circuit board 5 has a recess or a through hole 8 which is slightly larger than the through hole of the plating lead cut hole 3. Next, a manufacturing method will be described.

A conductive material having a predetermined thickness is formed on a conductive pattern on an FPC 1 by electroplating, and then a recess or through hole 8 slightly larger than a plating lead cut hole 3 in which a plating lead wire is cut is provided. A portion of the circuit board 5 to be bonded is bonded with an adhesive.

At this time, a fixed circuit board (a circuit board that does not bend) is used as the board having the plated lead cut holes 3 in addition to the FPC. Further, as a substrate provided with the through hole 8, a fixed circuit substrate or a flexible circuit substrate having a conductive portion or a metal plate in a portion corresponding to the plating lead cut hole 3 is used.

Therefore, a slightly larger concave portion or a through hole is provided in the bonding portion of the circuit board corresponding to the plating lead cut hole 3 such as the FPC 1 and bonded with an adhesive.
It is possible to easily ensure the withstand voltage of the plating lead 2.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments and operations of the present invention will be sequentially described in detail with reference to FIGS.

FIG. 1 shows a structural diagram of one embodiment of the present invention.
FIG. 1A shows a plating lead on an FPC. This is, as shown in FIG. 1 (d) described later, after forming a conductor pattern 11 to be subjected to electrolytic plating and a lead wire 12 for electrolytic plating on the FPC 1 by, for example, an etching method.
Electroplating is performed by flowing a current in the electrolytic solution between the lead 12 for electrolytic plating and an electrode (not shown). The lead wire 12 for electrolytic plating at this time is called a plating lead 2 here,
As shown, it is electrolytically plated and has a predetermined thickness.

FIG. 1B shows a state where the plating lead 2 is cut by forming a plating lead cut hole through a through hole. The plating lead cut hole 3 at the time of this cutting is
As shown in the drawing, the plating lead 2 is formed in the through hole 4. In this state, there is a problem that the insulation resistance is inferior if it is adhered to a circuit board having a flat conductive pattern as shown in FIG. The configuration is as shown in FIG.

FIG. 1C shows a plated lead cut hole 3.
2 shows a state in which the through hole 8 in the portion corresponding to FIG. As shown in the figure, a through hole 8 corresponding to the plated lead cut hole 3 of the FPC 1 and slightly larger than the size of the plated lead cut hole 3 is formed on the circuit board 5.
As shown in part (A), even if sagging 4 of the plated lead cut hole 3 occurs, the size of the through hole 8 is large and the distance to the conductor pattern 6 of the circuit board 5 is large, so that the withstand voltage can be sufficiently increased. Can be secured. In addition, since the through hole 8 having a large diameter is provided on the circuit board 5, even if an adhesive is applied on the conductor pattern 6 and bonded to the FPC 1, the adhesive passes through the plating lead cut hole 3 and rises upward. Therefore, as described above with reference to FIG. 3B, the problem that the adhesive is applied to the pad on the FPC 1 near the plating lead cut hole 3 of the FPC 1 to cause a conduction failure is eliminated. The adhesive 7 adheres the circuit board 5 and the FPC 1 by placing a sheet-shaped heat-cured resin which is appropriately applied or cut on the conductor pattern 6.

FIG. 1D shows a state in which a conductor pattern 11 and a lead wire 12 for electrolytic plating are formed on the FPC 1 by an etching method or the like. In this state, a current is passed in the electrolytic solution between the lead 12 for electrolytic plating and an electrode (not shown) to electroplate nickel of a predetermined thickness on the predetermined conductor pattern 11 or gold on the nickel. I do. Then, the portion of the plated lead quad hole 3 is punched out by a press, and the patterns formed on the conductor pattern 11 are cut off. FIG. 2 shows an enlarged view of the portion B at this time.

As described above, the plated lead 2 on the FPC 1 is pressed to form the plated lead cut hole 3, and the through hole 8 is slightly larger than the diameter of the plated lead cut hole 3.
By bonding the circuit board 5 with the adhesive 7 with the adhesive 7, even if the plating lead cut hole 3 is sagged, the distance between the sagged portion and the conductor pattern 6 on the circuit board 5 can be sufficiently secured. The dielectric strength can be made complete and the adhesive 7 can be used when the FPC 1 and the circuit board 5 are bonded together.
Can pass through the plating lead cut hole 3 and soak on the FPC 1 and adhere to a nearby pad, thereby making it possible to eliminate the occurrence of poor contact during soldering or wire bonding.

FIG. 2 is an explanatory view of a plated lead cut hole. This is an enlarged view of part B of FIG. 1 (d) described above. Here, the lead 12 for electrolytic plating is used to connect the conductor pattern 11 of FIG. 1D during electrolytic plating and to perform electrolytic plating. After the electrolytic plating, the lead 12 is cut off to electrically connect each conductor pattern. It is for independence. Here, as shown in the figure, the portion of the intersection of the electrolytic plating lead wire 12 after the electrolytic plating is
A through hole is provided to separate each electrolytic plating lead wire 12 (plating lead 2).

As described above, after the electrolytic plating, the through-holes called the plating lead cut holes 3 are provided, and the respective lead-out lines 12 (plating leads 2) for electrolytic plating can be cut off to make each conductor pattern independent.

In the above embodiment, the through hole 8 slightly larger than the diameter of the plated lead cut hole 3 of the FPC 1 is provided in the circuit board 5, but a recess may be provided instead of the through hole 8. The recess may be formed by, for example, removing a hole in the circuit board 5 itself, removing the conductor pattern 6 corresponding to the recess, or selecting a portion without the conductor pattern 6 as the recess.

[0024]

As described above, according to the present invention,
Since a slightly larger concave portion or through hole is provided in the bonding portion of the circuit board 5 corresponding to the plating lead cut hole 3 of the FPC 1 or the like and bonded with an adhesive, the withstand voltage of the plating lead 2 can be easily and easily reduced. It is possible to reliably ensure, and it is possible to eliminate the occurrence of a defect in soldering or wire bonding due to the adhesive protruding from the plating lead cut hole 3 and adhering to a nearby pad.

[Brief description of the drawings]

FIG. 1 is a structural diagram of one embodiment of the present invention.

FIG. 2 is an explanatory diagram of a plating lead cut hole.

FIG. 3 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 1: FPC (flexible printed circuit board) 2: plating lead 3: plating lead cut hole 4: sag 5: circuit board 6: conductor pattern 7: adhesive 8: through hole 11: conductor pattern 12: lead wire for electrolytic plating

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05K 1/14

Claims (3)

(57) [Claims] A circuit board having a plating lead cut hole obtained by forming a conductive material of a predetermined thickness on a conductive pattern by electrolytic plating and cutting a plating lead wire used for the electrolytic plating is bonded to another circuit board. In the bonded circuit board, a slightly larger recess or through hole is provided in a portion of the other circuit board corresponding to the plated lead quad hole, and the circuit board is bonded to the other circuit board with an adhesive. Laminated circuit board. 2. The bonded circuit board according to claim 1, wherein the circuit board having the plated lead cut holes is a fixed board or a flexible circuit board. 3. The circuit board according to claim 1, wherein the other circuit board is a fixed board or a flexible circuit board having a conductive portion or a metal plate at a portion corresponding to the plated lead cut hole. Laminated circuit board.