JP7311985B2 - Rigid-flex multilayer printed wiring board - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rigid-flex multilayer printed wiring board having a rigid area where components can be mounted and a bendable flexible area.

In recent years, the automatic control of automobiles has progressed more and more, and the number of mounted parts and various sensors has increased significantly. As a result, there is an increasing demand for rigid-flex multilayer printed wiring boards, which are used for parts and sensors, and which can contribute to a high degree of installation freedom in devices and miniaturization of devices.

As conventional rigid-flex multilayer printed wiring boards, for example, those shown in Patent Documents 1 and 2 are known.
An example of manufacturing the rigid-flex multilayer printed wiring board of Patent Documents 1 and 2 will be described with reference to schematic sectional process diagrams shown in FIGS. 7(a) to 7(c).
First, as shown in FIG. 7A, wiring patterns 19 are formed on the front and rear surfaces of the flexible substrate 2, and then the flexible substrate 1 is obtained by laminating the coverlay 3 for protecting the wiring patterns 19. As shown in FIG. Here, a coverlay with a metal foil is laminated as the coverlay 3, and then an etching process is performed to provide a dummy pattern 5a slightly larger than the flexible region F in the flexible region F. As shown in FIG.

Next, after laminating an arbitrary number of insulating adhesive layers 6 (for example, 20 to 60 μm thick) and wiring patterns 19 on the coverlay 3 on which the dummy patterns 5a are formed, the wiring patterns 19 of the outermost layer are laminated. By forming a protective solder resist 9, a multilayer board 14a as an intermediate substrate is obtained.
Next, as shown in FIGS. 7B and 7C, the unnecessary portion 20 laminated on the flexible region F is hollowed out by laser processing or removed by cutting, and then the exposed dummy pattern 5a is etched. to obtain a rigid-flex multilayer printed wiring board pw.

In the above-described manufacturing method, the multilayer board 14a (the multilayer laminated board before removing the unnecessary portion 20 of the flexible region F shown in FIG. 7A) can be manufactured by the same method as the normal build-up method. , miniaturization and high-density wiring of the rigid-flex multilayer printed wiring board pw can be achieved.

However, the thickness of the insulating adhesive layer 6 laminated on the flexible substrate 1 is as thin as 20 to 60 μm, and accordingly the reinforcing base material such as glass cloth contained therein is also thin. As a product that requires vibration resistance and mounting of heavy parts, there was a concern that the rigidity would be insufficient.

JP 2013-51325 A Japanese Patent No. 5778825

In order to avoid the above concern, as shown in FIG. 8, a core substrate 4a having a thickness of 100 μm or more, for example, a thickness of 100 μm or more, which is thicker and more rigid than the thin insulating adhesive layer 6, is used as a multilayer board. A configuration is conceivable in which the thickness adjusting layer 4 is disposed on the inner layer side of 14b, and a normal buildup layer composed of a thin insulating adhesive layer 6 is laminated on the outer layer side. By doing so, it is possible to ensure high density wiring on the outer layer side where the components are mounted, and to impart high rigidity.

However, when laser processing is performed on materials with different thicknesses (insulating adhesive layer 6, core base material 4a) as shown in FIG. 8, materials with uniform thickness as shown in FIG. Since it is more difficult than the laser processing performed on the insulating adhesive layer 6) (for example, when high-energy laser processing is performed in accordance with the thick core base material 4a, the dummy pattern 5a There is a risk of damaging the positioned flexible substrate 1. In order not to damage the flexible substrate 1, laser processing is performed by adjusting the energy corresponding to each of the insulating adhesive layer 6 and the core base material 4a. is a very troublesome process.), and there is a problem that it is difficult to remove the unnecessary portion 20 on the flexible region F.

Therefore, the inventor thought that the above problem could be solved by removing the unnecessary part 20 by router processing as shown in FIG. 9, and tried to implement it.
That is, as the core base material 4a, a core base material 4a having a dummy pattern 5 formed thereon as a receiving pattern for a router bit is laminated at a position corresponding to the flexible region F, and a slit is formed along the outer shape of the dummy pattern 5 by router processing. By forming the dummy pattern 5, the unnecessary portion 20 including the dummy pattern 5 is removed.

However, the removal processing of the unnecessary portion 20 is performed one side at a time by removing the unnecessary portion on one surface of the flexible substrate 1 and then removing the unnecessary portion on the other surface. When removing the unnecessary part of the surface, there was a problem that the processing depth of the router processing was not stable.
The outline of this problem will be described with reference to the processed cross-sectional view shown in FIG.

First, as shown in FIGS. 10A and 10B, after the multilayer board 14 is formed, router processing is performed to remove the unnecessary portion 20a on one surface of the flexible substrate 1, and the unnecessary portion 20a is removed. The portion 20a is removed (reference numeral 29 in FIG. 10(b) indicates a "router bit"). After that, the multilayer board 14 is turned over and router processing is performed to remove the unnecessary portion 20b on the other surface. ), such as when router processing is applied to the one surface, there is a support during router processing (the support in this case corresponds to the “unnecessary portion 20b” on the other surface) does not exist. As a result, the flexible substrate 1 is bent by the pressing pressure of the router bit 29 during the router processing of the other side, and the router processing depth is not stable. Problems such as contact with the substrate 1 and the flexible substrate being damaged, or the unnecessary part 20b not being properly removed due to excessively shallow processing, have arisen.

The present invention has been made in view of the conventional circumstances as described above, and the thickness of the inner layer side is 100 μm or more in order to provide high rigidity while ensuring high density wiring on the outer layer side where parts are mounted. The object of the present invention is to provide a rigid-flex multilayer printed wiring board having a thickness adjusting layer made of a core base material of and

As a result of various studies aimed at solving the above problems, the inventor of the present invention has found that at least at the boundary between the rigid area and the flexible area on one side of the flexible substrate, which is first subjected to router processing, a The present inventors have found that providing a reinforcing portion that serves as a support during the router processing can provide extremely good results, and have completed the present invention.

That is, the present invention provides a rigid-flex multilayer printed board having a rigid area where components can be mounted and a bendable flexible area, comprising a flexible substrate and a wiring pattern formed on the flexible substrate. and a flexible substrate comprising a coverlay for protecting the wiring pattern; a multilayer portion comprising an arbitrary number of laminated bodies of insulating resin layers and wiring layers laminated in the rigid region of the flexible substrate; and the multilayer and a solder resist that protects the wiring pattern of the outermost layer in the part, and among the insulating resin layers of the multilayer part, the insulating resin layer located between the flexible substrate and the wiring layer closest to the flexible substrate , a first insulating resin layer, a thickness adjusting layer made of a core base material having a thickness of 100 μm or more laminated on the first insulating resin layer , and a second insulating resin layer laminated on the thickness adjusting layer At the boundary between the rigid region and the flexible region on at least one surface of the flexible substrate, a plate-shaped protruding portion protruding from the first insulating resin layer of the multilayer portion on the flexible substrate to the flexible region is provided by router processing. The above problems are solved by a rigid-flex multilayer printed wiring board characterized by:

The present invention also provides a rigid-flex multilayer printed board having a rigid area where components can be mounted and a flexible area that can be bent, comprising a flexible base material and a wiring pattern formed on the flexible base material. and a flexible substrate comprising a coverlay for protecting the wiring pattern; a multilayer portion comprising an arbitrary number of laminated bodies of insulating resin layers and wiring layers laminated in the rigid region of the flexible substrate; and the multilayer and a solder resist that protects the wiring pattern of the outermost layer in the part, and among the insulating resin layers of the multilayer part, the insulating resin layer located between the flexible substrate and the wiring layer closest to the flexible substrate , a first insulating resin layer, a thickness adjusting layer made of a core base material having a thickness of 100 μm or more laminated on the first insulating resin layer , and a second insulating resin layer laminated on the thickness adjusting layer and a wall-like protruding portion formed by router processing protruding from the multilayer portion on the flexible substrate to the flexible region at the boundary between the rigid region and the flexible region on one surface of the flexible substrate. The flex multilayer printed wiring board solves the above problems.

According to the rigid-flex multilayer printed wiring board of the present invention, among the insulating resin layers of the multilayer portion, which is a laminate of an arbitrary number of insulating resin layers and wiring layers, the flexible substrate and the nearest one from the flexible substrate Since the insulating resin layer positioned between the wiring layer and the thickness adjusting layer made of the thick core base material is provided, high density wiring can be ensured and high rigidity can be achieved.
In addition, at the boundary between the rigid area and the flexible area on one surface of the flexible substrate (the surface to be routed first), a plate-like or wall-like protrusion is provided as a reinforcing portion when performing the router processing on the other surface. Therefore, it is possible to stabilize the router processing depth of the other surface, thereby eliminating problems caused by the router processing depth being too deep or too shallow.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional explanatory view showing a first embodiment of the rigid-flex multilayer printed wiring board of the present invention; FIG. 2 is a schematic cross-sectional process diagram showing an example of manufacturing the rigid-flex multilayer printed wiring board of FIG. 1 ; FIG. 3 is a schematic cross-sectional process diagram following FIG. 2 ; FIG. 4 is a schematic cross-sectional process diagram following FIG. 3 ; FIG. 2 is a schematic cross-sectional explanatory view showing a second embodiment of the rigid-flex multilayer printed wiring board of the present invention; FIG. 6 is a schematic cross-sectional explanatory view showing a bent state of the rigid-flex multilayer printed wiring board of FIG. 5 ; 1A to 1D are schematic cross-sectional process diagrams showing an example of manufacturing a conventional rigid-flex multilayer printed wiring board; FIG. 8 is a schematic cross-sectional explanatory view for explaining a configuration in which a thick core base material is arranged on the inner layer side of the rigid-flex multilayer printed wiring board of FIG. 7 ; FIG. 9 is a schematic cross-sectional explanatory view for explaining a configuration in which dummy pattern formation locations of the rigid-flex multilayer printed wiring board of FIG. 8 are changed; FIG. 10 is a processed cross-sectional view for explaining an outline of a problem that occurs in the rigid-flex multilayer printed wiring board of FIG. 9;

A first embodiment of the rigid-flex multilayer printed wiring board of the present invention will be described below with reference to FIG. In the drawings, the dimensional ratios of the components may be changed from the actual ones in order to facilitate understanding.
Incidentally, the "insulating adhesive layer" that appears in the description of the manufacturing method of the rigid-flex multilayer printed wiring board of the present invention is actually an adhesive in a semi-cured state after being cured by heating and laminating press. However, for convenience of explanation, the term "insulating adhesive layer" will be used in this specification regardless of whether it is before or after curing.

(First embodiment)
In FIG. 1 showing the first embodiment of the present invention, PW1 is a rigid-flex multilayer printed wiring board, which is composed of a rigid area R where parts can be mounted and a flexible area F which can be bent.
The flexible region F is a flexible substrate 1 composed of a flexible base material 2, first wiring patterns 21 formed on both front and back surfaces of the flexible base material 2, and a coverlay 3 protecting the first wiring patterns 21. consists of
In addition, the rigid region R consists of a multilayer portion 12 composed of a laminate of an arbitrary number of insulating resin layers and wiring layers laminated on both the front and back surfaces of the flexible substrate 1, and the outermost layer of the multilayer portion 12. It is composed of a solder resist 9 that protects the third wiring pattern 23 .

The multilayer portion 12 includes a first insulating resin layer 24, a thickness adjusting layer 4 composed of a core substrate 4a having a thickness of 100 μm or more laminated on the first insulating resin layer 24, and laminated on the thickness adjusting layer 4. The second wiring pattern 22 laminated on the insulating resin layer, and the second wiring pattern 22 laminated on the second wiring pattern 22, and the second wiring pattern 25 is laminated alternately. , a third insulating resin layer 26, a third wiring pattern 23, and a buried hole 11 filled with a filling resin 27 connecting between the second wiring patterns 22 formed on both surfaces of the flexible substrate 1; Blind via holes 15 connecting between the second wiring pattern 22 and the third wiring pattern 23 and between the vertically adjacent third wiring patterns 23 are provided.

In addition, part of the first insulating resin layer 24 of the multilayer part 12 laminated on the flexible substrate 1 extends over the boundary between the rigid region R and the flexible region F on both the front and back surfaces of the flexible substrate 1 . A plate-like protruding portion 28 protruding to the side is formed to face each other.

One of the points to be noted in the present invention is that the thickness adjusting layer 4 made of the core base material 4a having a thickness of 100 μm or more is arranged between the flexible substrate 1 and the flexible substrate 1 among the insulating resin layers of the multilayer portion 12. Insulating resin layer located between the closest wiring layer (layer in which the second wiring pattern 22 is formed), here, the first insulating resin layer 24, the thickness adjusting layer 4, and the second insulating resin layer 25 and the insulating resin layer.
Since the core base material 4a having a thickness of 100 μm or more has a very high rigidity (that is, the glass cloth is thick), the thickness adjustment layer 4 made of the core base material 4a is formed between the flexible substrate 1 in the multilayer portion 12 and the flexible substrate. 1 and the closest wiring layer (the layer in which the second wiring pattern 22 is formed), it is possible to provide high rigidity while ensuring high wiring density.

In the present invention, the insulating resin layer ( Since the first insulating resin layer 24) has a plate-like projecting portion 28 projecting to the flexible region F, after removing an unnecessary portion (unnecessary portion 20a described later) on one surface of the flexible substrate 1, the other surface is removed. When removing unnecessary portions (unnecessary portions 20b described later) by router processing, the processing depth of the router processing can be stabilized. It is possible to avoid problems such as the flexible substrate 1 being scratched by the pressure, or the unnecessary portion 20b not being properly removed due to excessively shallow processing.
Although the dimensions of the projecting portion 28 are not particularly limited, it preferably has a plate shape projecting from the boundary between the rigid region R and the flexible region F of the flexible substrate 1 toward the flexible region F by 50 μm to 1000 μm. The reason for this is that if the distance from the boundary is less than 50 μm, the position of the router when removing the unnecessary portion 20b on the other surface is greatly deviated from the position of the router on the one surface (for example, 20 μm to 20 μm). 30 μm), there is a possibility that the function as a reinforcing portion for suppressing the bending of the flexible substrate 1 cannot be fulfilled. Since the dimension of F must be larger than necessary (the flexible area F must be made large enough to form the protrusion 28 to ensure an effective folding area), rigid-flex multilayer printing is used. This is because the wiring board becomes large.
Moreover, the thickness of the projecting portion 28 is preferably 30 μm or more. The reason for this is that by setting the thickness to 30 μm or more, it is possible to leave the reinforcing base material such as glass cloth in the projecting portion 28, thereby preventing the projecting portion 28 from cracking due to the pushing pressure of the router bit. .

In this embodiment, as shown in FIG. 1, the plate-like protruding portion 28 is formed to face the entire boundary between the rigid region R and the flexible region F on both the front and back surfaces of the flexible substrate 1. , and need not be on both sides, and may be formed on at least one side of the flexible substrate at the boundary between the rigid area and the flexible area. Also, a partial area may be used instead of the entire area. However, since the boundary between the rigid region R and the flexible region F can be reinforced, it is preferable to have the projecting portion 28 in the entire boundary between the rigid region R and the flexible region F on both the front and back sides of the flexible substrate 1 (the reinforcement , when the flexible substrate 1 is bent, the load applied to the first wiring pattern 21 positioned at the boundary portion can be reduced, so disconnection of the first wiring pattern 21 can be suppressed).

In this embodiment, as shown in FIG. 1, the multilayer portion 12 is composed of a laminated body in which three insulating resin layers and three wiring layers are alternately laminated, but the number of layers is not particularly limited. can be selected arbitrarily.

Next, a method for manufacturing the rigid-flex multilayer printed wiring board PW1 will be described with reference to FIGS.

First, as shown in FIG. 2A, a flexible base material 2 having a thickness of about 25 to 100 μm is prepared, and first wiring patterns 21 are formed on both front and back surfaces of the flexible base material 2 . Next, on the surface on which the first wiring pattern 21 is formed, a coverlay 3 having a thickness of about 25 to 70 μm (for example, an adhesive layer 16 that adheres to the first wiring pattern 21 and a cover film 17 that protects the surface layer (for example, “ A flexible substrate 1 is produced by laminating a coverlay consisting of two layers (polyimide film)).
As the flexible base material 2, a bendable insulating base material made of polyimide, polyethylene terephthalate, or the like is generally used.

Next, as shown in FIG. 2(b), a core base material 4a having a thickness of 100 μm or more provided with a conductor layer 18 is prepared, etched, and etched to form a portion that will be in contact with a flexible region F later. A dummy pattern 5 is formed in the .
Here, the thickness of the conductor layer 18 is, for example, about 35 to 105 μm. As the core base material 4a having a thickness of 100 μm or more provided with the conductor layer 18, a commonly used reinforcing base material such as glass cloth is impregnated with a thermosetting resin such as epoxy resin and laminated with copper foil. A copper clad laminate or the like can be preferably used.

Subsequently, as shown in FIG. 2(c), a first insulating adhesive layer 24a is prepared for bonding the flexible substrate 1 and the core substrate 4a on which the dummy pattern 5 is formed. An opening 7 is formed at a location corresponding to the dummy pattern 5 by processing or the like.
For the first insulating adhesive layer 24a, a prepreg or the like, which is obtained by impregnating a reinforcing base material such as a glass cloth with a thermosetting resin such as an epoxy resin and semi-curing it, is generally used.
It is desirable that the thickness of the first insulating adhesive layer 24a is equal to that of the dummy pattern 5 or thinner than that of the dummy pattern 5 by about 5 to 10 μm.
The reason for this is that if the thickness of the first insulating adhesive layer 24a is equal to or thinner than that of the dummy pattern 5, the resin of the first insulating adhesive layer 24a will flow toward the dummy pattern 5 during lamination. This is because the dummy pattern 5 and the coverlay 3 can be laminated without being firmly adhered by the resin. If the adhesion between the dummy pattern 5 and the coverlay 3 is weak, the unnecessary portions (20a, 20b) located on the flexible region F can be easily removed later.

Next, as shown in FIG. 2(d), a first insulating adhesive layer 24a having openings 7 formed thereon, a core substrate 4a having dummy patterns 5 formed thereon, and a core substrate 4a having dummy patterns 5 formed thereon are formed so as to sandwich the flexible substrate 1 from both sides. A second insulating adhesive layer 25a having a thickness of 20 to 60 μm and a metal foil 8 (preferably copper foil) are laminated in this order, and all-in-one lamination press is performed.

In this embodiment, only the dummy pattern 5 is formed on the core substrate 4a. However, it is of course possible to form a wiring pattern on the surface opposite to the surface on which the dummy pattern 5 is formed. It is possible. In this case, if the thickness of the conductor layer 18 laminated on the core base material 4a is about 35 μm, the wiring pattern may be formed by etching as it is. In this case, the conductor layer 18 is first thinned by down-etching, and then the wiring pattern is formed by etching.

Next, as shown in FIG. 3(e), by a conventional method, a through hole is formed by drilling, a copper plating layer is formed on the surface layer and inside the through hole by copper plating, and the inside of the through hole where the copper plating layer is formed is Then, the second wiring pattern 22 and the land 10 of the buried hole 11 are formed by filling the hole-filling resin 27 and etching.

Subsequently, a third insulating adhesive layer 26a having a thickness of about 20 to 60 μm and a metal foil (preferably copper foil) are laminated by a conventional method, non-through holes are formed by laser drilling, and metal (copper) plating is performed. , the formation of the third wiring pattern 23 and the blind via hole 15 by etching is repeated twice each, and two layers of the third insulating adhesive layer 26a and the third wiring pattern 23 are alternately laminated to form an insulating resin layer and a A multilayer portion 12 is formed of a laminated body in which three wiring layers are alternately laminated one after another. Finally, a solder resist 9 is formed to protect the third wiring pattern 23, which will be the outer layer circuit, to obtain the multilayer board 14 (see FIG. 3(f)).

Next, a method of removing unnecessary portions on the flexible area F will be described with reference to FIGS. 3(g) and 4(h) to (j).
First, as shown in FIGS. 3(g) and 4(h), the unnecessary portion 20a on one side of the flexible substrate 1 is removed by performing router processing from one side of the multilayer board 14. .
In the router processing performed here, at the boundary between the rigid region R and the flexible region F, and at the edge of the outer shape of the dummy pattern 5 and the edge of the opening 7 provided in the first insulating adhesive layer 24a. , forming the slit 13 .
As described above, the unnecessary portion 20a can be easily removed because the bonding strength between the dummy pattern 5 and the coverlay 3 is weak (both may not be bonded at all). (See FIG. 4(h)).

In addition, in the boundary portion between the rigid region R and the flexible region F, a part of the first insulating adhesive layer 24a protrudes toward the flexible region F over the entire boundary portion, and a plate-like protruding portion 28 is formed to face each other. . The protruding portion 28 can be used as a support (reinforcing portion) for router processing that is performed when removing the unnecessary portion 20b on the other surface of the flexible substrate 1. It is possible to perform router processing with high accuracy when removing the portion 20b (that is, since it is possible to suppress bending of the flexible substrate 1 due to the pushing pressure of the router bit, it is possible to perform router processing with a stable processing depth. can).

In addition, as described above, the dimension of the plate-like protruding portion 28 is preferably within the range of 50 μm to 1000 μm from the boundary portion toward the flexible region F side. Moreover, the thickness of the projecting portion 28 is preferably 30 μm or more.
Incidentally, the size adjustment of the protruding portion 28 can be easily adjusted by adjusting the size of the dummy pattern 5, the size of the opening 7 provided in the first insulating adhesive layer 24a correspondingly thereto, and the diameter of the router bit. can be done.

Subsequently, as shown in FIGS. 4(i) and 4(j), the substrate is reversed and the other surface of the flexible substrate 1 is processed. The procedure is the same as that for one surface of the flexible substrate 1 (the first router-processed surface), and consists of two steps, a step of processing the slits 13 and a step of removing the unnecessary portion 20b. When the surface is routed, the projecting portion 28 formed on one surface serves as a reinforcing portion, so that the bending of the flexible substrate 1 due to the pushing pressure of the router bit can be suppressed, and thus the router processing can be performed with high accuracy. (That is, damage to the flexible substrate 1 can be avoided, and the unnecessary portion 20b can be removed accurately).

Next, the outer shape is processed. The outer shape is processed by router processing or punching press processing, and the rigid-flex multilayer printed wiring board is separated from the outer frame. This processing completes the rigid-flex multilayer printed wiring board PW1 of the present invention.

(Second embodiment)
Next, a second embodiment of the rigid-flex multilayer printed wiring board of the present invention will be described with reference to FIG.
In FIG. 5 showing the second embodiment of the present invention, PW2 is a rigid-flex multilayer printed wiring board, and the layer structure of the multilayer part 12 laminated on the rigid region of the flexible substrate 1 is the same as that of the first embodiment. is. Only parts different from the first embodiment will be described below.

A feature of the rigid-flex multilayer printed wiring board PW2 is that, on one side of the flexible substrate 1, a boundary between the rigid region R and the flexible region F protrudes from the multilayer portion 12 on the flexible substrate 1 to the flexible region F. The difference is that wall-like protruding portions 28a are formed to face each other. The wall-like projecting portion 28a fits within the flexible area F on the other surface of the flexible substrate 1 when the flexible substrate 1 is projected.

In this manner, a wall-like structure protruding from the multilayer portion 12 on the flexible substrate 1 to the flexible region F is formed at the boundary between the rigid region R and the flexible region F on one surface of the flexible substrate 1 (the surface to be routed first). By having the projecting portion 28a, when removing the unnecessary portion 20b on the other surface of the flexible substrate 1 by router processing, the projecting portion 28a functions as a reinforcing portion. It is possible to suppress the bending of the flexible substrate 1 due to the pushing pressure of the router bit, thereby performing highly accurate router processing (that is, it is possible to avoid damage to the flexible substrate 1). can be removed).
For the same reason as in the first embodiment, the dimension of the wall-shaped projecting portion 28a should be within a range of 50 μm to 1000 μm from the boundary between the rigid region R and the flexible region F of the flexible substrate 1 to the flexible region F side. is preferred.
The wall-like projecting portion 28a projecting from the multilayer portion 12 on the flexible substrate 1 to the flexible region F in the rigid-flex multilayer printed wiring board PW2 is formed after removing the unnecessary portion 20a on one surface of the flexible substrate 1. The flexible substrate 1 is arranged so that the flexible region F formed after the removal of the unnecessary portion 20b on the other surface of the flexible substrate 1 is within the area of the flexible region F when the flexible substrate 1 is projected. is formed by removing the unnecessary portion 20a on one side of the by router processing.

Incidentally, in the second embodiment, as shown in the schematic cross-sectional view of FIG. If one surface smaller than the dimension of the region F is bent outward and the other surface is bent inward, the bending load (arrow L) can be suppressed by the wall-like protruding portion 28a, so there is an advantage that disconnection of the first wiring pattern 21 at the boundary portion can be suppressed.

In describing the present invention, an example of a rigid-flex multilayer printed wiring board in which a multilayer portion having three wiring layers is formed on the front and back sides of a double-sided flexible substrate having two wiring layers has been used. The configuration of the present invention is not limited to this, and it is of course possible to use other configurations without departing from the scope of the present invention. Also, the plate thickness, number of layers, materials, etc. can be changed within the scope of the present invention.

1: Flexible substrate 2: Flexible base material 3: Coverlay 4: Thickness adjusting layer 4a: Core base material 5, 5a: Dummy pattern 6: Insulating adhesive layer 7: Opening 8: Metal foil 9: Solder resist 10: Land 11: Buried hole 12: Multilayer part 13: Slits 14, 14a, 14b: Multilayer board 15: Blind via hole 16: Adhesive layer 17: Cover film 18: Conductor layer 19: Wiring patterns 20, 20a, 20b: Unnecessary part 21: First wiring pattern 22: Second wiring pattern 23: Third wiring pattern 24: First insulating resin layer 24a: First insulating adhesive layer 25: Second insulating resin layer 25a: Second insulating adhesive layer 26: Third Insulating resin layer 26a: Third insulating adhesive layer 27: Filling resin 28: Plate-like protrusion 28a: Wall-like protrusion 29: Router bit F: Flexible region R: Rigid region PW1, PW2, pw: Rigid flex multilayer printed wiring board

Claims (6)

A rigid-flex multilayer printed board having a rigid area where components can be mounted and a flexible area that can be bent, comprising a flexible substrate, a wiring pattern formed on the flexible substrate, and the wiring pattern A flexible substrate comprising a coverlay for protection; A multilayer portion comprising an arbitrary number of laminated layers of an insulating resin layer and a wiring layer laminated in a rigid region of the flexible substrate; Wiring in the outermost layer of the multilayer portion a first insulating resin layer on an insulating resin layer having a solder resist for protecting a pattern and positioned between a flexible substrate and a wiring layer closest to the flexible substrate among the insulating resin layers of the multilayer portion; and a thickness adjusting layer made of a core base material having a thickness of 100 μm or more laminated on the first insulating resin layer , and a second insulating resin layer laminated on the thickness adjusting layer , and the flexible substrate Rigid characterized by having a plate-like protruding part by router processing protruding from the first insulating resin layer of the multilayer part on the flexible substrate to the flexible region at the boundary between the rigid region and the flexible region on at least one surface.・Flex multi-layer printed wiring board. 2. The rigid-flex multilayer printed wiring according to claim 1, wherein the plate-shaped protruding portion protrudes from the boundary between the rigid region and the flexible region of the flexible substrate by 50 μm to 1000 μm toward the flexible region. board. 3. The rigid-flex multilayer printed wiring board according to claim 1, wherein the thickness of the plate-like protrusion is 30 [mu]m or more. 4. The rigid-flex multilayer printed wiring board according to claim 1, wherein the projecting portions are provided on both front and back surfaces of the flexible substrate. A rigid-flex multilayer printed board having a rigid area where components can be mounted and a flexible area that can be bent, comprising a flexible substrate, a wiring pattern formed on the flexible substrate, and the wiring pattern A flexible substrate comprising a coverlay for protection; A multilayer portion comprising an arbitrary number of laminated layers of an insulating resin layer and a wiring layer laminated in a rigid region of the flexible substrate; Wiring in the outermost layer of the multilayer portion a first insulating resin layer on an insulating resin layer having a solder resist for protecting a pattern and positioned between a flexible substrate and a wiring layer closest to the flexible substrate among the insulating resin layers of the multilayer portion; and a thickness adjusting layer made of a core base material having a thickness of 100 μm or more laminated on the first insulating resin layer , and a second insulating resin layer laminated on the thickness adjusting layer , and the flexible substrate 1. A rigid-flex multilayer printed wiring board, characterized in that a wall-like protruding portion protruding from a multi-layered portion on the flexible substrate to the flexible region by router processing is provided at a boundary portion between a rigid region and a flexible region on one surface. 6. The rigid-flex multilayer printed wiring according to claim 5, wherein the wall-like protruding portion protrudes from the boundary between the rigid region and the flexible region of the flexible substrate by 50 μm to 1000 μm toward the flexible region. board.