JPH0677611A - Rigid and flexible printed board - Google Patents

Abstract

PURPOSE:To enhance through hole drilling performance by extending the coating layer of a flexible printed wiring slightly to the side of hard printed wiring region at a joint with the hard printed wiring to be drilled with a through hole. CONSTITUTION:Hard printed wirings 7, 7' are laminated through a flexible printed wiring 6 and then they are integrated. At a predetermined region, the hard printed wirings 7, 7' are partially exfoliated to expose a part of the flexible printed wiring 6 coated through an adhesive layer 9 with a surface protective layer 8. When a through hole 7a is drilled at the wiring parts 7, 7' spaced apart inwardly by about 2mm from the edges thereof in a joint region between the exposed flexible printed wiring 6 and the hard printed wirings 7, 7', leading end face of the surface protective layer 8 is set in the edge region of about 2mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rigid flexprint wiring board, and more particularly to a rigid flexprint wiring board having good through-hole drilling workability and improved / improved thermal stability.

[0002]

2. Description of the Related Art Conventionally, the following structure has been adopted as a circuit structure which also serves as a wiring connection portion and a device housing which are required to have flexibility, or as a laminated or compact structure of wiring or circuit units. Rigid flex printed wiring boards that can be bent are known. That is, a rigid printed wiring body unit is appropriately laminated on a flexible wiring body surface provided with a surface protective coating layer integrally (adhesion / integration), and is bent by a flexible wiring body forming the separation portion. There is known a printed wiring board configured to be possible. FIG. 3 is a cross-sectional view showing the configuration of the main part of such a rigid / flex printed wiring board. Reference numeral 1 is a flexible wiring in which a surface protective layer (coverlay film) 3 is covered via an adhesive layer 2. Body, 4,
Reference numeral 4'denotes a hard printed wiring body integrally arranged so as to sandwich the flexible wiring body 1 from both main surfaces (in a laminated manner). That is, in the rigid / flex printed wiring board, the hard printed wiring bodies 4 and 4'are laminated and integrated through the flexible printed wiring body 1, and the hard printed wiring bodies 4 and 4 are hardened in a predetermined area. ′
A part of the flexible printed wiring body 1 having a protective layer 3 (for example, a polyimide resin film) coated on the surface thereof via an adhesive layer 2 such as a thermoplastic resin is exposed. Is done.

Then, such a rigid flex printed wiring board is manufactured as follows. FIG. 4 is a schematic view showing a cross section of a main part of the embodiment, in which both sides of a flexible printed wiring body 1 whose surface is covered with a protective layer 3 via an adhesive layer 2 can be cut off and peeled off. Hard printed wiring boards 4, 4'having V grooves 4a, 4b provided in advance
After stacking and integrating, while performing the required external shape processing,
When the outermost layer is copper foil-clad, so-called photo-etching is performed on this copper foil to form a required wiring pattern. Then, the hard printed wiring boards 4 and 4'are separated by the V-grooves 4a and 4b, and non-circuit forming regions between the wiring unit portions on the same surface are selectively peeled and removed to obtain the flexible wiring body. It is manufactured by selectively exposing a part of No. 1 of FIG. In this manufacturing process, in order to protect the surface of the exposed flexible wiring body 1, not only the planned exposed area surface but also at least the area sandwiched between the hard printed wiring boards 4 and 4 ', for example, about several mm. The surface protection layer 3 is extended / interposed to the hard printed wiring boards 4 and 4'with a width larger than that.

[0004]

However, in the rigid / flex printed wiring board, the following inconveniences are recognized in practical use. That is, rigid
A junction area between the exposed flexible printed wiring body 1 and the hard printed wiring bodies 4, 4'of the flex printed wiring board, in other words, a hard printed wiring connected to the exposed flexible printed wiring body 1. Body 4,
When the through hole 4c is drilled in the connection side edge region of 4 ', the surface which covers the exposed flexible printed wiring board 1 and extends / interposes on the hard printed wiring board 4, 4'side. Protective layer 3, especially adhesive layer 2 in that area
However, in drilling the through hole 4c, for example, drilling, the drilling workability tends to be impaired. That is, since the adhesive layer 2 is generally formed of a thermoplastic resin, it is difficult to form the through holes 4c, but the coefficient of thermal expansion is larger than that of the hard printed wiring boards 4 and 4 '. If the diameter is as small as about 1 mm or less, there is also a problem that the reliability of the through hole 4c is likely to be impaired.

The problem is that the surface protective layer 3 of the flexible printed wiring body 1 is extended / interposed to the side of the hard printed wiring boards 4 and 4'with a width of several mm or more, and the through hole is formed. Select the 4c drilling location deep inside the hard printed wiring boards 4 and 4 '.
Although it can be solved to some extent by setting, on the other hand, a new problem arises in terms of wiring density, such as reducing the area where wiring is possible.

The present invention has been made to solve the above-mentioned problems, and does not cause a reduction in wiring density and the like.
An object of the present invention is to provide a rigid / flex printed wiring board capable of achieving punching workability and reliability of through holes.

[0007]

Rigidity according to the present invention
In the flex printed wiring board, a hard printed wiring body is laminated and integrated via a flexible printed wiring body, and a part of the hard printed wiring body is peeled off / removed in a predetermined area to form a protective layer on the surface. A rigid / flex printed wiring board having a structure in which a part of a flexible printed wiring body covered via an adhesive layer is exposed, wherein the exposed flexible printed wiring body and a hard printed wiring body are joined to each other. In the area, when a through hole is formed in the hard printed wiring body part in the inner area, which is separated from the edge of the hard printed wiring body by about 2 mm, the tip surface of the surface protective coating layer is set to the edge of about 2 mm. The feature is that it is set in the area.

In the above construction, even if the end surface of the surface protective layer of the flexible printed wiring body is within the edge area of about 2 mm from the end surface of the hard printed wiring body, it is a through hole (through hole row) forming area. Good but usually 2mm wide
It is desirable to select and set the inside (of a hard printed wiring body) of the edge region of the degree.

[0009]

According to the rigid / flex printed wiring board of the present invention, the coating layer that covers the surface of the flexible printed wiring body at the connection portion with the hard printed wiring body region where the through holes are drilled is Only a small width (a width of at most about 2 mm) is provided on the hard printed wiring board region side. In other words, the hard printed wiring body area does not have the surface protection layer and the adhesive layer for bonding and integrating the surface protection layer in the area other than the edge portion having a width of about 2 mm. Not only is the reliability of through holes improved and improved, but also the reduction of the wirable area in the hard printed wiring body area is suppressed, so that a high wiring density can be maintained.

[0010]

Embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 is a sectional view showing an example of the essential structure of a rigid / flex printed wiring board 5 according to the present invention. Hard printed wiring bodies 7 and 7'are laminated and integrated via a flexible printed wiring body 6. Of the flexible printed wiring body 6 which is formed into a predetermined area and has a portion of the hard printed wiring body 7, 7 ′ peeled off and removed to cover the surface with a protective layer 8 via an adhesive layer 9. The part is exposed. In the rigid-flex printed wiring board 5 having the above-described structure, the rigid printed wiring bodies 7 and 7'are connected to the exposed flexible printed wiring body 6 and the hard printed wiring bodies 7 and 7 '. When the through hole 7a is formed in the hard printed wiring body 7 or 7'in the inner area separated by about 2 mm from the edge (end face),
The tip surface of the surface protective coating layer 8 is selected and set within the edge region 10 of about 2 mm. In the figure, 11
Indicates a prepreg cured layer that fills and integrates between the flexible printed wiring body 6 and the hard printed wiring bodies 7, 7 '.

Next, a manufacturing example of the rigid-flex printed wiring board 5 having the above-mentioned structure will be described with reference to FIG.

First, hard printed wiring bodies 7 and 7'having a thickness of 0.2 mm, one main surface of which has a wiring pattern and the other main surface of which is covered with copper foil, are prepared. 7 '
A predetermined slit was formed using a Victoria mold, for example, at a predetermined position, that is, along the periphery of the wiring unit on the wiring-patterned surface. Here, on the copper foil surface side of the hard printed wiring bodies 7 and 7 ', a wiring unit forming region and a non-circuit forming portion for separating the wiring units from each other are provided corresponding to a wiring unit having one main surface made of a wiring pattern. The slit is provided along the periphery of the wiring unit, and the slit has a depth reaching the copper foil surface stretched on the other main surface. On the other hand, the necessary wiring patterns are provided on both main surfaces, and the peripheral portion 10 of the finally exposed area surface is further expanded by about 2 mm so that the surface protection layer (coverlay film) 8, for example, a polyimide resin film is formed. A flexible wiring body 6 integrated with an adhesive layer 9 is prepared. That is,
The area surface to be finally formed as an inner layer in the hard printed wiring board 7, 7'is formed in advance so that the surface protection layer 8 is inner layer / sealed over the area 10 having a width of about 2 mm. A flexible wiring body 6 in which 8 is selectively integrated is used. Here, the diameter of the through hole drill, the surface protection layer 8
Depending on the bonding accuracy of and the positioning accuracy at the time of stacking, in the inner layer / sealing region 10 of the surface protection layer 8,
Drilling through holes is also possible if the clearance is machined with a clearance of 0.1 mm.

Then, the prepared hard printed wiring bodies 7 and 7'and the flexible wiring body 6 are laminated and arranged by arranging a prepreg layer 11 in a required region as shown in a sectional view in FIG. After that, a heating / pressurizing molding process is performed to form a hard printed wiring body 7 on both sides of the flexible wiring body 6.
A printed wiring board in which 7'are integrated is obtained. After that, the copper foil forming the outer surface of the integrated hard printed wiring board 7, 7'is subjected to a required photoetching treatment to form a wiring unit, and then the hard printed wiring body 7, 7'is formed. By the slit provided,
Desired rigid / flexprint wiring in which the flexible wiring body 6 having the surface protection layer 8 is exposed by separating the wiring unit portion and the non-circuit forming area and selectively peeling / removing the non-circuit forming area. A board is obtained.

[0015]

As described above, according to the rigid / flex printed wiring board of the present invention, the coverlay film and the adhesive agent, which contribute to the surface protection of the flexible wiring body 6 exposed in the through hole punching portion area, are provided. The layer is substantially absent. Therefore, in the through hole drilling process, the through hole drilling processability has been significantly improved and improved by, for example, increasing the number of stacked sheets from 2 to 3 and the drill life (drilling 0.4 mm in diameter) from 1000 bits to 2000 bits. obtain. Further, due to the substantial absence of the thermoplastic resin-based adhesive layer, the reliability of the through holes to be drilled is also good, for example, the plating layer on the inner wall surface of the through hole is 20 μm (the thermoplastic resin-based adhesive layer is If it exists
A reliable connection can be achieved even at 40 μm). Moreover,
Since the thermoplastic resin-based adhesive layer whose thermal expansion coefficient differs greatly from that of a hard printed wiring body is greatly reduced, it retains and exhibits excellent thermal cycle resistance as a wiring board.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration example of a main part of a rigid / flex printed wiring board according to the present invention.

FIG. 2 is a cross-sectional view schematically showing an embodiment of a method for manufacturing a rigid / flex printed wiring board according to the present invention.

FIG. 3 is a cross-sectional view showing a configuration example of a main part of a conventional rigid-flex printed wiring board.

FIG. 4 is a sectional view schematically showing an embodiment of a conventional method for manufacturing a rigid / flex printed wiring board.

[Explanation of symbols]

1, 6 ... Flexible wiring body 2, 9 ... Adhesive layer
3, 8 ... Surface protective layer (Coverlay film) 4,
4 ', 7, 7' ... hard printed wiring body 4a, 4b ... separation groove 4c, 7a ... through hole 5 ... rigid flex printed wiring board 10 ... inner layer of surface protection layer / sealing area (edge area of about 2 mm ) 11 ... Prepreg layer (prepreg cured layer)

Claims (1)

[Claims] 1. A hard printed wiring body is laminated / integrated via a flexible printed wiring body, and a part of the hard printed wiring body is peeled off / removed in a predetermined region to adhere a protective layer to the surface. A rigid / flex printed wiring board having a structure in which a part of a flexible printed wiring body covered via an agent layer is exposed, wherein the exposed flexible printed wiring body and hard printed wiring body are joined to each other. In the case where a through hole is formed in the hard printed wiring body part in the inner area separated by about 2 mm from the end surface of the hard printed wiring body, the front end surface of the surface protective coating layer should be placed within the edge area of about 2 mm. Rigid flex printed wiring board characterized by setting to.