JPH0531838B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a rigid/flexible wiring board that is made partially flexible by fixing a rigid board to a flexible board, and a method for manufacturing the same. (Prior Art) Rigid-flexible wiring boards are bent at their exposed flexible portions, and are being used more frequently as various products become smaller. In other words, this type of rigid/flexible wiring board has become indispensable for storing and mounting various electronic components within a limited space. By the way, a conventional rigid/flexible wiring board is as shown in FIG. This conventional rigid-flexible wiring board 30 is shown bent at the exposed portion 31a of the flexible board 31, but it has one flexible board 31 at its center and a rigid board 32 on one or both sides. By fixing the flexible substrate 31, a part of the flexible substrate 31 is exposed and the exposed portion 31a is
was formed. In this conventional rigid-flexible wiring board 30, the exposed portion 31
The end 3 of each rigid substrate 32 located near a
2a is formed as a right-angled surface due to manufacturing problems. Therefore, when the rigid-flexible wiring board 30 is bent into the state shown in FIG. There will be direct contact. If the right-angled portion of the end portion 32a of each rigid substrate 32 comes into direct contact with the flexible substrate 31 or the conductor layer 33 formed on the surface thereof, the following adverse effects may occur. That is, since the conductor layer 33 formed on the flexible substrate 31 side is for conducting electricity to each substrate, if the end portion 32a of the rigid substrate 32, especially the right angle portion thereof, comes into contact with this conductor layer 33, , this conductor layer 33 may be damaged, thereby inhibiting conduction.
Moreover, the exposed portion 3 of this flexible substrate 31
1a is likely to be bent many times during the mounting of the electronic parts, and if such bending is repeated, the above-mentioned problem becomes noticeable. Even if the conductor layer 33 is not formed on the flexible substrate 31, the same problem will occur only in that the flexible substrate 31 itself that connects each substrate will be damaged; There is no change. Furthermore, in manufacturing such a conventional rigid/flexible wiring board 30, after each rigid board 32 is fixed to a flexible board 31, a conductor circuit is formed on the surface of the rigid board 32 by etching, plating, etc. is formed,
Etching liquid, plating liquid, etc. used in this case may remain in the gap formed by the end portion 32a of the flexible substrate 31 and the rigid substrate 32. This accumulated etching solution, plating solution, etc. may have an adverse effect on other parts after the rigid/flexible wiring board 30 is completed, so it is necessary to completely remove it. Another process is required, and the liquid must also be treated. (Problems to be Solved by the Invention) The present invention has been made in view of the above-mentioned circumstances, and the problems to be solved are the ease of damage in conventional rigid-flexible wiring boards of this type. Moreover, it is inefficient in manufacturing rigid/flexible wiring boards. First of all, it is an object of the present invention to provide a rigid-flexible wiring board having a structure that can easily avoid damage at bent portions of this type of rigid-flexible wiring board. . The second object is to provide a method that can easily manufacture this type of rigid-flexible wiring board. (Means for Solving the Problems) The means taken by the first invention to solve the above problems include a flexible substrate 11 and a part of the flexible substrate 11 that is fixed to the flexible substrate 11. It consists of a rigid substrate 12 to be exposed,
The rigid/flexible wiring board 10 is formed by forming conductive circuits at necessary locations on each of the flexible substrates 11 and the rigid substrates 12, and the flexible substrates 11 are provided at the ends of the rigid substrates 11 near the exposed portions of the flexible substrates 11. A rigid board characterized by forming step portions 12a that become thinner in sequence toward the exposed portion 11a of the substrate 11, and sandwiching the bent portion of the flexible substrate 11 between the thinnest portions of the step portions 12a. -Flexible wiring board 10. The second invention as a method for manufacturing such a rigid/flexible wiring board is a method for manufacturing a rigid/flexible wiring board comprising the following steps. (a) The groove portion 12b corresponding to the exposed portion 11a of the flexible substrate 11 is inserted into the rigid substrate 1.
(b) A step of laminating and bonding the rigid substrate 12 to the flexible substrate 11 via the adhesive sheet 14 so that the groove 12b of the rigid substrate 12 faces the flexible substrate 11; (c) Each rigid substrate 12 (d) Cutting along the groove 12b of the rigid substrate 12 to form a stepped portion 12a at the end of the rigid substrate 12; This is a step of exposing the exposed portion 11a of the. (Actions of the Invention) By adopting the above measures, the present invention has the following effects. First, in the rigid/flexible wiring board 10 according to the present invention, since the stepped portion 12a is formed at the end of each rigid substrate 12 corresponding to the exposed portion 11a of the flexible substrate 11, the rigid substrate 12 The bent portion of the flexible substrate 11 is held between the two. Since each step portion 12a sandwiching the bent portion of the flexible substrate 11 is the thinnest portion, even if the rigid substrate 12 is made of a material with high strength, the step portion 12a The thinnest part of has some degree of flexibility. Therefore, when the flexible substrate 11 is bent, each step portion 12a holding the bent portion of the flexible substrate 11 supports the bent portion with elasticity. Therefore, since the bent portion of the flexible substrate 11 or the conductor layer 13 formed thereon is elastically supported, even if the flexible substrate 11 is frequently bent, the edges of each rigid substrate 12 There will be no effect at all. Further, when the rigid/flexible wiring board 10 is manufactured by the method according to the present invention, the conductor layer 13 is etched on the surface of the rigid board 12.
Since the exposed portion 11a of the flexible substrate 11 is formed after being formed by plating or the like, the etching liquid, plating liquid, etc. when forming the conductor layer 13 on the surface of the rigid substrate 12 may be in the vicinity of the exposed portion 11a. There is nothing left behind. Therefore, the rigid/flexible wiring board 10 after completion
In this case, the etching solution, plating solution, etc. do not have any adverse effects, especially in the vicinity of the exposed portion 11a of the flexible substrate 11. (Examples) Next, each invention will be described in more detail based on examples shown in the drawings. FIG. 1 shows a longitudinal sectional view of a rigid-flexible wiring board 10 according to the present invention. This rigid-flexible wiring board 10 mainly consists of a flexible substrate 11 placed at the center and a plurality of rigid substrates 12 fixed to both sides of the flexible substrate 11 via adhesive sheets 14. There is. The flexible substrate 11 is connected to each rigid substrate 12.
, and an exposed portion 11a is formed approximately in the center thereof. A stepped portion 12a is formed at the end of each rigid substrate 12 on the exposed portion 11a side. Since the stepped portion 12a is for elastically supporting the bent portion of the flexible substrate 11, the first stepped portion 12a
It may be a simple thin wall as shown in the figure, or it may be a shape that gradually slopes toward the center of the exposed portion 11a. Further, as shown in FIG. 5, the stepped portion 12a may be formed in a stepped manner so as to become gradually thinner. Furthermore, a conductor layer 13 is formed on each of the flexible substrates 11 and rigid substrates 12 as required, and electronic components (not shown) are mounted on the surface of each rigid substrate 12. Each of these flexible substrates 11 and rigid substrates 12 is
They are fixed to each other by an adhesive sheet 14 interposed between them. Of course, flexible substrate 1
An opening 14a is formed in a portion of the adhesive sheet 14 corresponding to the exposed portion 11a of the adhesive sheet 1. As the adhesive sheet 14, it is preferable to use a glass cloth impregnated with a non-flowable semi-hardening resin. When the flexible substrate 11 and the rigid substrate 12 are bonded together using the adhesive sheet 14, a portion of the adhesive sheet 14 is prevented from flowing into the opening 14a, and a portion of the rigid substrate 12 to be removed later is prevented from flowing into the opening 14a. This is to prevent adhesion to the flexible substrate 11 side. In addition, if a fluid adhesive sheet 14 must be used, an opening 14a must be made in advance in a portion corresponding to the exposed portion of the flexible substrate 11 before laminating the flexible substrate 11 and each rigid substrate 12. At the same time, the adhesive sheet 1
It is preferable that a mold release material having the same thickness as 4 is interposed in the opening 14a. This is to prevent a part of the rigid substrate 12 to be removed later from being adhered to the flexible substrate 11 side by using the release material having the same thickness as the adhesive sheet 14. Moreover, as a material for forming each flexible substrate 11 described above, the following materials may be used. That is, materials suitable for the flexible substrate 11 include phenolic resin, unsaturated polyester resin, epoxy resin, polyimide resin,
Triazine resins, polybutadiene resins, fluorine resins, and polysulfonate resins may be used alone, or they may be modified products or mixtures thereof. On the other hand, as a material for forming the above-mentioned rigid substrate 12, the following materials may be used. In other words, materials suitable for the rigid substrate 12 include phenolic resin, unsaturated polyester resin, epoxy resin, polyimide resin, triazine resin, polybutadiene resin, fluorine resin, polysulfonate resin, or modified products thereof. mixture or ceramics. Next, this rigid flexible wiring board 10
The method according to the present invention for manufacturing the same will be explained with reference to FIGS. 2 and 3. This method consists of the following steps. That is, (a) forming a groove on the inside of the rigid substrate corresponding to the exposed portion of the flexible substrate; (b) attaching the rigid substrate to the flexible substrate via an adhesive sheet so that the groove faces the flexible substrate; The process of laminating and bonding; (c) The process of performing various processing such as forming a conductor circuit on the front side of each rigid board; (d) The process of cutting along the grooves of the rigid board to form a step at the edge of the rigid board. In this step, the exposed portion of the flexible substrate is exposed. The groove portion 12b is formed in a portion of the rigid substrate 12 corresponding to the exposed portion 11a of the flexible substrate 11 using an etching liquid, plating liquid, etc. used when forming a conductive circuit on the surface of the rigid substrate 12. However, this is to prevent the particles from remaining near the exposed portion 11a of the flexible substrate 11 until the rigid-flexible wiring board 10 is completed. That is, after forming the conductor circuit on the surface of the rigid substrate 12, the exposed portion 11a is exposed for the first time by cutting the rigid substrate 12 along the groove portion 12b. Various shapes can be considered for the groove portion 12b, but any shape is sufficient as long as the stepped portion 12a of the rigid substrate 12 described above can be used as a resilient clamping portion.
It may be triangular as shown in FIGS. 2 and 3, or may be square or arcuate. Each rigid substrate 12 having such a groove 12b formed therein is fixed to both surfaces of the flexible substrate 11 via each adhesive sheet 14. Of course, the openings 1 are formed in advance in the portions of each of these adhesive sheets 14 that correspond to the exposed portions 11a of the flexible substrate 11.
4a is preferably formed. Without this opening 14a, when the portion corresponding to the stepped portion 12a of each rigid substrate 12 is cut, the portion of the rigid substrate 12 that is removed due to the cutting will be easily separated from each rigid substrate 12 due to the remaining adhesive sheet 14. Because it will disappear. After doing the above, various processes such as necessary conductor circuit formation are performed on the front side of each rigid substrate 12. The etching liquid, plating liquid, etc. used in this case will not flow into the vicinity of the exposed portion 11a because the portion of each rigid substrate 12 that faces the exposed portion 11a of the flexible substrate 11 remains. . After forming the necessary conductor circuits etc. on the surface of each rigid board 12 in this way, each rigid board 12
The portion corresponding to each groove portion 12b is cut from the surface side. This cutting does not need to be performed to cover the thickness of the rigid substrate 12. Since each groove portion 12b is inserted into each rigid substrate 12 by a predetermined amount, the thickness of the rigid substrate 12 makes it difficult for the groove portion 12b to
The rigid substrate 12 may be cut inward by an amount equal to the depth of the rigid substrate 12. That is, the purpose of this cutting is to remove unnecessary portions of the rigid substrate 12. Next, the present invention will be explained with reference to examples. Example 1 A single-sided substrate, that is, a conductor layer is formed only on one side, is used as the flexible substrate 11,
A double-sided board and a three-layer board were used as the rigid board 12. As the base material of this rigid substrate 12, a glass cloth base material impregnated with polyimide resin was used. Then, a V-shaped groove (this becomes the groove portion 12b) shallower than the thickness of each plate was formed in each rigid substrate 12. Each of these rigid substrates 12 was bonded and fixed to the flexible substrate 11 with one adhesive sheet 14 (product name: SAF, manufactured by Nikkan Industries) interposed therein, which was a non-flow type prepreg and had a thickness of 40 μm. . In this case, an opening 14a was formed in a portion of the adhesive sheet 14 corresponding to the exposed portion 11a of the flexible substrate 11, and Tedlar manufactured by DuPont was used as a release paper for the opening 14a.
The lamination conditions in this case are 20Kg/cm ² at a temperature of 150℃.
The pressure was applied for about 40 minutes. After completing the lamination as described above, necessary through holes were formed through each flexible substrate 11 and rigid substrate 12, and necessary conductor layers were formed on the front side of each rigid substrate 12. Thereafter, cutting along the portions corresponding to the respective grooves 12b was performed using an ordinary cutting tool, as shown in FIG. The cutting depth in this case was shallower than the thickness of each rigid substrate 12, and the cross-sectional shape of the cut hole was approximately U-shaped. Example 2 Each flexible substrate 11 and rigid substrate 12
form. In this case, Kapton (polyimide material) manufactured by DuPont is used as the base material of the flexible substrate 11, and the rigid substrate 12
As the base material, a glass cloth base material impregnated with polyimide resin was used, and as the adhesive sheet 14, Pyralux, a trade name manufactured by DuPont, was used. The steps from this step to cutting the portion of the rigid substrate 12 corresponding to each groove 12b are as follows:
Since this is the same as the first embodiment described above, the description thereof will be omitted. In this embodiment, the method of cutting each groove portion 12b is different. That is, the surface of the rigid substrate 12 corresponding to each groove portion 12b is first cut into a larger size. After that, a second cutting, which is smaller than the first cutting, is performed. This second cutting, as shown in Figure 5,
Cut a little deeper than the first cut. As a result, the shape of the step portion 12a of each rigid substrate 12 for elastically supporting the exposed portion 11a of the flexible substrate 11 can be formed to become gradually thinner, and each step portion 12a can be formed to have a thinner shape. This allows it to have even more elasticity. (Effects of the Invention) As described in detail above, in the present invention, as exemplified in each of the above embodiments, a flexible substrate 11 and a part of the flexible substrate 11 fixed to the flexible substrate 11 are provided. It consists of a rigid substrate 12 to be exposed, and each of these flexible substrates 11 and rigid substrate 1
Rigid film made by forming a conductor layer at the required locations of 2.
In the flexible wiring board 10, a stepped portion 12a is formed at an end of each rigid substrate 11 close to an exposed portion of the flexible substrate 11, and the step portion 12a becomes thinner toward the exposed portion 11a of the flexible substrate 11. The feature is that the bent portions of the flexible substrate 11 are sandwiched between the thinnest portions of the stepped portions 12a, and this makes it possible to easily avoid damage at the bent portions. - A flexible wiring board 10 can be provided. That is, by simply forming a step portion 12a facing toward the exposed portion 11a of the flexible substrate 11 at the end of each rigid substrate 12, this step portion 12
a allows the bent portion of the flexible substrate 11 to be supported more elastically than conventional ones, so even if the flexible substrate 11 is bent many times, The rigid
The flexible wiring board 10 is a flexible substrate 11
This makes it possible to prevent damage to itself and the conductor layer 13 formed thereon. Furthermore, the method for manufacturing the rigid-flexible wiring board 10 according to the present invention includes: (a) forming the groove portion 12b corresponding to the exposed portion 11a of the flexible substrate 11 on the rigid substrate 1;
(b) A step of laminating and bonding the rigid substrate 12 to the flexible substrate 11 via the adhesive sheet 14 so that the groove 12b of the rigid substrate 12 faces the flexible substrate 11; (c) Each rigid substrate 12 (d) Cutting along the groove 12b of the rigid substrate 12 to form a stepped portion 12a at the end of the rigid substrate 12; The method is characterized in that it consists of each step of exposing the exposed portion 11a of the wiring board 11a, thereby making it possible to easily and reliably manufacture the rigid/flexible wiring board 10 having the above-mentioned effects.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a rigid/flexible wiring board according to the present invention, FIG. 2 is an exploded perspective view of each member for explaining the method of manufacturing a rigid/flexible wiring board according to the present invention, and FIG. 3 is an exploded perspective view of each member. A vertical cross-sectional view corresponding to FIG. 1 showing the state before cutting of the part corresponding to the groove, FIG. 4 is an enlarged vertical cross-sectional view of the part marked with - in FIG. The corresponding enlarged partial vertical cross-sectional view, FIG. 6, is a vertical cross-sectional view of a conventional rigid flexible wiring board. Explanation of symbols, 10... Rigid/flexible wiring board, 11... Flexible board, 11a...
Exposed portion, 12... Rigid substrate, 12a... Step portion, 12b... Groove portion, 13... Conductor layer, 14...
Adhesive sheet, 14a...opening.

Claims (1)

[Scope of Claims] 1. Consists of a flexible substrate and a rigid substrate fixed to the flexible substrate to expose a part of the flexible substrate, and conductor circuits are formed at necessary locations on each of the flexible substrate and the rigid substrate. A rigid/flexible wiring board comprising: forming a stepped portion that becomes thinner sequentially toward the exposed portion of the flexible substrate at an end of each of the rigid substrates close to the exposed portion of the flexible substrate; A rigid/flexible wiring board characterized in that the bent portion of the flexible substrate is sandwiched between the thinnest parts of the rigid substrates. 2. The flexible substrate is made of phenolic resin,
A patent claim characterized in that it is formed from an unsaturated polyester resin, an epoxy resin, a polyimide resin, a triazine resin, a polybutadiene resin, a fluorine resin, a polysulfonate resin, or a modified product or a mixture thereof. Range 1
Rigid/flexible wiring board described in section. 3. The rigid substrate is made of a phenolic resin, an unsaturated polyester resin, an epoxy resin, a polyimide resin, a triazine resin, a polybutadiene resin, a fluorine resin, a polysulfonate resin, or a modified product or mixture thereof, or ceramics. The rigid film according to claim 1 or 2, characterized in that
Flexible wiring board. 4 The flexible substrate and rigid substrate are:
A rigid-flexible wiring board according to any one of claims 1 to 3, each having one or more conductor layers. 5. A method for manufacturing a rigid/flexible wiring board consisting of the following steps. (a) forming a groove portion corresponding to the exposed portion of the flexible substrate inside the rigid substrate; (b) attaching the rigid substrate to the flexible substrate via an adhesive sheet so that the groove portion faces the flexible substrate; (c) A step of performing various processing such as forming a conductor circuit on the front side of each of the rigid substrates; (d) A step of laminating and bonding the rigid substrates by cutting along the grooves of the rigid substrates; forming a step at an end of the substrate and exposing the exposed portion of the flexible substrate; 6. The adhesive sheet has an opening formed in advance in a portion corresponding to the exposed portion of the flexible substrate before each rigid substrate is laminated on the flexible substrate, and an opening having the same thickness as that of the adhesive sheet. 6. The manufacturing method according to claim 5, wherein a mold release material is interposed within the opening. 7. The manufacturing method according to claim 5, wherein the adhesive sheet is a glass cloth impregnated with a non-flowable semi-hardening resin.