JP2009290193A - Rigid flexible multilayer printed wiring board and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rigid flexible multilayer printed wiring board capable of securing connection reliability of a through-hole even in a thick board of more than 1.2 mm of total thickness and preventing warp and torsion of the board. <P>SOLUTION: In the rigid flexible multilayer printed wiring board, a flexible board is laid on an outer layer of only one side of a core substrate as a build-up layer and the thickness of the build-up layer on the flexible board side is made approximately same as a build-up layer formed on an outer layer of the other side of the core substrate where the flexible board is not laid thereon. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rigid-flex multilayer printed wiring board comprising a rigid part that can be mounted with a component and a flexible part that can be bent, and a method of manufacturing the same.

  A conventional rigid-flex multilayer printed wiring board is generally configured as shown in the schematic sectional view of FIG.

  That is, a flexible base substrate 13 made of polyimide or the like, a wiring pattern 2 formed on the front and back of the flexible base substrate 13, a flexible substrate 14a made of a coverlay 16 that protects the wiring pattern 2, and a flexible substrate 14a The interlayer insulating layer 4 having the penetrating portion 12 in the portion that becomes the flexible portion F after being laminated on the front and back of the wiring pattern 2, the wiring pattern 2 formed on the interlayer insulating layer 4, the flexible substrate 14a and the interlayer insulating layer 4 And a lead hole 10 (hereinafter referred to as “BH”) connected to the wiring pattern 2 provided in the wiring pattern 2 and a portion that becomes the flexible portion F after being laminated on the interlayer insulating layer 4. Build-up insulating layer 4c having a portion 12 (hereinafter, “build-up insulating layer” is referred to as “BU insulating layer”), and the BU insulating layer c, a wiring pattern 2 formed on c, a through hole 10a for connecting the wiring pattern 2 of each layer (hereinafter referred to as "THL"), and a blind via for connecting the wiring pattern 2 adjacent in the vertical direction A hole 10b (hereinafter, “blind via hole” is expressed as “BVH”) and a solder resist 15 that protects the wiring pattern 2 on the outer layer (“R” in the figure is “rigid portion”, “ "F" indicates "flexible part").

  As described above, the rigid-flex multilayer printed wiring board includes the flexible portion F that can be partially bent. Therefore, the rigid-flex multilayer printed wiring board can be used for mobile phone main and sub boards, various module boards, etc. Many have been adopted.

  However, the rigid-flex multilayer printed wiring board as shown in FIG. 8 in which the flexible substrate is disposed at the center has a general reliability up to a specification of a total board thickness of 1.2 mm at the maximum {for example, 1000 cycles of thermal shock Since the through-hole connection reliability by the test (30 minutes at −65 ° C. and 30 minutes at + 125 ° C. as one cycle) has not been secured, for example, the total plate thickness is 1 as in the case of automobile-related equipment. It was not possible to meet the requirements of thicker than 2 mm specifications (for example, 1.6 mm) and more severe through-hole connection reliability (for example, securing 2000 to 3000 cycles by a thermal shock test).

  More specifically, the rigid-flex multilayer printed wiring board Pa in the form of FIG. 8 is composed of three base materials (three base materials composed of the flexible base substrate 13, the cover lay 16, and the interlayer insulating layer 4) having different central layers. As a result, the stress generated during hot is concentrated in the central layer, and as a result, cracks occur in the portion (the portion surrounded by a circle in the figure) located in the central layer of the through hole 10a. Met.

  Accordingly, a rigid-flex multilayer printed wiring board Pb as shown in FIG. 9 has been reported as one that can avoid such a problem (see Patent Document 1).

  That is, the core substrate 11a having four wiring pattern layers, the flexible substrate 14 laminated on one surface of the core substrate 11a via the BU insulating layer 4c, and the flexible protection for protecting the wiring pattern 2 of the flexible substrate 14 The conductive solder resist 15b and the solder resist 15 that protects the wiring pattern on the other surface of the core substrate 11a.

  In this way, if a flexible substrate having a coefficient of linear expansion different from that of the core substrate is disposed in the outer layer, the stress generated by the thermal shock test can be relaxed, thereby ensuring the connection reliability of the through hole. it can.

  However, this type of rigid-flex multilayer printed wiring board has a build-up layer (a build-up layer made up of the flexible substrate 14 in the figure) laminated only on one side of the core substrate (that is, the core substrate) Since the thickness differs between the front and back surfaces, there has been a problem that warpage is likely to occur during heat treatment during lamination or component mounting.

  With respect to such a problem, Patent Document 1 describes that the warp is absorbed by reducing the thickness of the core substrate 11a. However, if the thickness is used, the product specifications are limited (for example, the core). When the number of layers of the substrate is increased or when the interlayer insulating layer has to be thickened, it is difficult to cope with it).

JP 2004-187202 A

  The present invention provides a rigid flex multilayer print that can ensure the connection reliability of through-holes and suppress the occurrence of warping and twisting even when the total plate thickness is thicker than 1.2 mm. It is an object of the present invention to provide a wiring board and a manufacturing method for easily obtaining the rigid-flex multilayer printed wiring board.

  The present invention is a rigid-flex multilayer printed wiring board comprising a rigid part that can be mounted with a component and a flexible part that can be bent, and includes at least a core substrate having a desired number of wiring pattern layers, From a first buildup layer having a flexible substrate laminated on at least one outer layer via a buildup insulating layer, and a buildup insulating layer and wiring pattern laminated on the outer layer on the other surface of the core substrate A second buildup layer, a via hole that connects the wiring patterns in the vertical direction, a solder resist that protects the wiring pattern on the outer layer, and a cover that protects the wiring pattern formed on the flexible portion of the wiring pattern on the outer layer The first build has a lay and a punched portion formed in a portion corresponding to the flexible portion. The rigid-flex multilayer printed wiring board, characterized in that the-up layer and the second buildup layer is formed substantially in the same thickness is obtained by solving the above problems.

  The present invention also provides a rigid-flex multilayer printed wiring board comprising a rigid part that can be mounted on a component and a flexible part that can be bent, the core substrate having at least a desired number of wiring pattern layers, and the core A first buildup layer having a flexible substrate laminated on at least one outer surface of the substrate via a buildup insulating layer, and a buildup insulating layer and wiring laminated on an outer layer on the other surface of the core substrate A second build-up layer made of a pattern, via holes connecting the wiring patterns in the vertical direction, a solder resist that protects the wiring pattern in the outer layer, and a hollow portion formed in a portion corresponding to the flexible portion And the wiring pattern formed in the portion corresponding to the flexible portion of the flexible substrate is formed only on the inner layer side. And a coverlay that protects the wiring pattern is partially formed in the wiring pattern forming portion, and that the first buildup layer and the second buildup layer are formed to have substantially the same thickness. The above-described problems are solved by the featured rigid-flex multilayer printed wiring board.

  The present invention also relates to a method of manufacturing a rigid-flex multilayer printed wiring board comprising a rigid part that can be mounted with a component and a flexible part that can be bent, and includes a core substrate having at least a desired number of wiring pattern layers. A first step of forming, a second step of forming a first buildup layer formed by sequentially laminating a buildup insulating layer and a flexible substrate on an outer layer of one surface of the core substrate, and the other of the core substrate Form a third step to form a second buildup layer consisting of a buildup insulating layer and metal foil on the outer layer of the surface, a fourth step to form a via hole to connect the wiring pattern in the vertical direction, and form a wiring pattern of the outer layer A fifth step of forming a solder resist that protects the outer layer wiring pattern, and a wiring formed in the flexible portion of the outer layer wiring pattern. A seventh step of forming a cover lay for protecting the pattern, and an eighth step of forming a cut-out portion in a portion that later becomes a flexible portion, and the thickness and the second build-up of the first build-up layer The above-described problems are solved by a method for manufacturing a rigid-flex multilayer printed wiring board, wherein the layers are formed to have substantially the same thickness.

  The present invention also relates to a method of manufacturing a rigid-flex multilayer printed wiring board comprising a rigid part that can be mounted with a component and a flexible part that can be bent, and includes a core substrate having at least a desired number of wiring pattern layers. A first step to form, a second step to form a flexible substrate in which the wiring pattern of the flexible part is formed only on the inner layer side, and a coverlay that protects the wiring pattern formed on the inner layer side of the flexible part Forming a first buildup layer formed by sequentially laminating a buildup insulating layer and a flexible substrate obtained in the second and third steps on the outer layer of one surface of the core substrate. Four steps, a fifth step of forming a second buildup layer made of a buildup insulating layer and a metal foil on the outer layer on the other side of the core substrate, and a vertical arrangement. The sixth step of forming via holes for connecting the patterns, the seventh step of forming the outer layer wiring pattern, the eighth step of forming the solder resist for protecting the outer layer wiring pattern, and the portion that will later become the flexible portion A rigid-flex multilayer printed wiring comprising: a ninth step of forming a cut-out portion; and forming the first buildup layer and the second buildup layer to have substantially the same thickness. The above-described problems are solved by a plate manufacturing method.

  By adopting the rigid-flex multilayer printed wiring board according to the configuration of the present invention, it is possible to ensure the connection reliability of the through hole without being restricted by product specifications and to suppress the occurrence of warping and twisting. . In addition, the rigid flex multilayer printed wiring board can be obtained efficiently and easily by the production method of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic cross-section manufacturing-process figure for demonstrating 1st embodiment of the rigid-flex multilayer printed wiring board of this invention. FIG. 2 is a schematic cross-sectional manufacturing process diagram following FIG. 1. FIG. 3 is a schematic cross-sectional manufacturing process diagram following FIG. 2. The schematic sectional drawing for demonstrating 2nd embodiment of the rigid-flex multilayer printed wiring board of this invention. The schematic cross-section manufacturing-process figure for demonstrating 3rd embodiment of the rigid-flex multilayer printed wiring board of this invention. (A) is an expanded sectional view of the flexible part in 3rd embodiment, (b) is an expanded sectional view of the flexible part in 1st embodiment. The schematic sectional drawing for demonstrating the example which forms a soldering resist collectively. The schematic sectional drawing of the conventional rigid flex multilayer printed wiring board. The schematic sectional drawing of the conventional rigid flex multilayer printed wiring board which solves the problem of the rigid flex multilayer printed wiring board of FIG. The schematic cross-section manufacturing-process figure for demonstrating 4th embodiment of the rigid-flex multilayer printed wiring board of this invention. FIG. 11 is a schematic cross-sectional manufacturing process diagram following FIG. 10. (A) is schematic sectional drawing at the time of forming a counterbore part in a core substrate in 4th embodiment, (b) is an electromagnetic wave shield in the upper layer of the wiring pattern of a flexible part in 4th embodiment. The schematic sectional drawing at the time of providing a layer. The schematic sectional drawing for demonstrating 5th embodiment of the rigid-flex multilayer printed wiring board of this invention. The schematic cross-section manufacturing-process figure for demonstrating 6th embodiment of the rigid-flex multilayer printed wiring board of this invention. FIG. 15 is a schematic cross-sectional manufacturing process diagram following FIG. 14. (A) is schematic sectional drawing at the time of leaving a slit remainder on a core board | substrate in 6th embodiment, (b) is a flexible insulation adhesive bond layer instead of BU insulation layer in 4th embodiment. The schematic sectional drawing at the time of using.

  A first embodiment of the present invention will be described with reference to schematic sectional process diagrams shown in FIGS. The “interlayer insulating layer” and “BU insulating layer” appearing in the text actually refer to a semi-cured “interlayer insulating adhesive layer” that is cured and laminated by heating and pressing. However, for convenience of explanation, explanation of the heating / pressing press process is omitted, and the explanation will be made in the form of “lamination of an interlayer insulating layer and a BU insulating layer” from the beginning.

  First, as shown to Fig.1 (a), the double-sided printed wiring board 3 is obtained by forming the wiring pattern 2 in the front and back of the insulating substrates 1, such as a glass epoxy board | substrate.

  Here, as a means for forming the wiring pattern 2, it can be formed by a subtractive method in which a metal foil is etched or an additive method in which plating is deposited.

  Next, after roughening the surface of the wiring pattern 2 (for example, a soft etching process mainly composed of formic acid or an amine complexing agent), the interlayer insulating layer 4 and copper are formed on the front and back of the double-sided printed wiring board 3. A metal foil 5 such as a foil is sequentially laminated (or a metal foil with resin 6 in which an interlayer insulating layer 4 is previously laminated on one surface of the metal foil 5 is laminated so that the interlayer insulating layer 4 is in contact with the double-sided printed wiring board 3. Thus, the substrate of FIG. 1B in which the interlayer insulating layer 4 and the metal foil 5 are laminated on the front and back of the double-sided printed wiring board 3 is obtained.

  Next, the through hole 7 is drilled at a desired position by drilling or the like, and then the through hole 7 is cleaned by performing a desmear treatment such as sodium permanganate or potassium permanganate (FIG. 1 (c)).

  Next, by sequentially performing an electroless plating process (for example, “electroless copper plating process”) and an electrolytic plating process (for example, “electrolytic copper plating process”), the plating 8 is deposited on the entire surface of the substrate including the through holes 7. Next, the through-hole 7 in which the plating 8 is formed is filled with a hole-filling resin 9 to obtain the substrate shown in FIG.

  Next, by forming a circuit such as a subtractive method, a four-layer core substrate 11 on which the wiring pattern 2a and the BH 10 that connects the wiring patterns of each layer are formed is obtained (see FIG. 1 (e1)).

  Next, the first counterbore planned portion 12a (the portion surrounded by the dotted line in FIGS. 1 (e1) and (e2)) of the portion that becomes the flexible portion F after the core substrate 11 is removed by the first counterbore processing ( Next, after roughening the wiring pattern 2a of the core substrate 11, the first buildup layer C is formed on the outer layer of one surface of the core substrate 11, and the core substrate 11 Each of the second buildup layers D is laminated on the outer layer on the other surface (see FIG. 2B). Incidentally, FIG. 1 (e2) is an enlarged plan view of the main part when the “first counterbore planned portion 12a” is viewed from above, and FIG. 2 (a2) is after the “first counterbore planned portion 12a” is removed. The principal part enlarged plan view at the time of seeing "the spot facing part 12b" from the top is shown.

  Here, the first build-up layer C on which the first counterbore process is laminated on the side A is composed of the flexible substrate 14 (the flexible base substrate 13 and the metal foil 5) laminated via the BU insulating layer 4a. And a second build-up layer D on which the second counterbore process to be processed later is laminated on the side B is a metal foil 5 (or alternatively laminated) via a BU insulating layer 4b. , A resin-attached metal foil 6a in which a BU insulating layer 4b is laminated in advance on one side of the metal foil 5, but the thicknesses of the first buildup layer C and the second buildup layer D are substantially the same. It is thick.

  Further, the BU insulating layers 4a and 4b are not particularly limited, but using a prepreg in which a glass woven fabric or a glass nonwoven fabric is impregnated with an epoxy resin can satisfactorily fill the wiring pattern 2a, or It is preferable for suppressing warping and twisting.

  Furthermore, in the present embodiment, an example is shown in which the punched portion 12d is formed in advance in the portion corresponding to the flexible portion F of the BU insulating layer 4a, but it is not always necessary to provide it. However, it is preferable to provide the punched portion 12d in order to improve the flexibility of the flexible portion F when it is a finished product.

  Next, a through hole 7a and a non-through hole 7b are drilled by drilling, laser processing, or the like in a portion where a via hole (TH or BVH) for interlayer connection is formed (see FIG. 2C), and then desmear treatment The substrate shown in FIG. 2D is obtained by sequentially performing the plating process.

  Next, as shown in FIG. 3A, by forming the circuit of the outer layer by the subtractive method, the wiring patterns 2b, TH10a, BVH10b are formed, and then the solder resist 15 for protecting the wiring pattern 2b and A cover lay 16 that protects the wiring pattern 2b located in the flexible portion F is formed (see FIG. 3B).

  Here, in the solder resist 15, in order to satisfactorily perform the spot facing when removing the second spot facing portion 12c (that is, the cracking of the solder resist due to the spot facing is prevented). For this reason, it is preferable to provide a solder resist removal portion 15a.

  Further, as the coverlay 16 that protects the wiring pattern 2b located in the flexible portion F, a flexible film having an adhesive layer, a flexible insulating adhesive layer having flexibility even after curing (a so-called “bonding sheet”). ) Or a flexible solder resist, and any of them may be selected.

  Next, the remaining second counterbore planned portion 12c is removed by the second counterbore processing to form the punched portion 12 in the flexible portion F, and then the outer shape processing such as punching by a die or router processing. To obtain the rigid-flex multilayer printed wiring board P shown in FIG.

  The remarkable point of the present invention is that a flexible substrate as a build-up layer is laminated only on one outer layer of the core substrate, and one build-up layer on which the flexible substrate is laminated and the other build-up on which the flexible substrate is not laminated. The thickness of the layers is the same.

  Thereby, the connection reliability of the through hole can be ensured and the occurrence of warping and twisting can be suppressed without being restricted by product specifications (substrate thickness or the like).

Next, a second embodiment will be described with reference to FIG.
In FIG. 4, instead of laminating the flexible substrate 14, the metal foil 5 is laminated via a flexible insulating adhesive layer 18 (for example, a bonding sheet made of polyimide or the like) that has flexibility even after curing. It is what I did.

  According to the present embodiment, the flexible portion F can be formed easily and at a low cost because it does not require the effort as in the first embodiment in which the flexible substrate 14 is laminated via the BU insulating layer 4a. Can do.

  4A shows an example in which the flexible insulating adhesive layer 18 is provided only on one side. However, it is a diagram in which the upper and lower materials are aligned in that the manufacturing process is easy and warpage and twisting can be further suppressed. The configuration of 4 (b) is preferable.

  Next, a third embodiment will be described with reference to FIG. Since FIG. 5A1 is the same as FIG. 1E1, the description of the manufacturing process up to that point is omitted. 5 (a2) is an enlarged plan view of a main part when the “first slit machining scheduled portion 17a” is viewed from above, and FIG. 5 (b2) is a slit machining on the “first slit machining scheduled portion 17a”. The principal part enlarged plan view at the time of seeing the "slit part 17" after performing this from the top is shown.

  First, the first slit processing by router processing, laser processing, or the like is performed on the first slit processing scheduled portion 17a of the core substrate 11 shown in FIGS. 5A1 and 5A2 (the portion indicated by the dotted line in the drawing). As a result, the slit portion 17 shown in FIGS. 5B1 and 5B2 is formed.

  Here, the slit portion 17 is processed along the outline of the punched portion 12 to be formed later in the portion that becomes the flexible portion F, and the processing is stopped halfway through the core substrate 11 (for example, the core substrate 11). The remaining portion of the slit 17c is left.

  Next, as in the first embodiment, the first build-up layer C is laminated on the side A1 of the first slit process, and the second build-up layer D is laminated on the side B1 of the second slit process ( Next, the formation of TH and BVH, the formation of the outer layer wiring pattern, the formation of the solder resist and the coverlay are sequentially performed.

  Next, it corresponds to the flexible part F in the second slit processing (symbol “17b” in the figure indicates the “second slit processing scheduled portion” processed by “second slit processing”) reaching the slit portion 17. A rigid-flex multilayer printed wiring board P shown in FIG. 5 (d) is obtained by forming a punched portion 12 in the portion to be cut and then performing external processing such as punching with a die or router processing. is there.

  What should be noted in this embodiment is that, instead of removing the first counterbore planned portion 12a removed in the first embodiment, the slit portion 17 is formed and the remaining slit portion 17c is left. In the point.

  As a result, when the wiring pattern is formed in the portion located in the flexible portion F (the portion surrounded by a circle in FIG. 5C), the slit remaining portion 17c is supported, and therefore the length L of the flexible portion F (FIG. 5). Even if the specification (see (d)) is long (for example, 10 mm or more), the bending of the flexible substrate 14 can be suppressed (see the enlarged cross-sectional view of the main part in FIG. 5C shown in FIG. 6A).

  Accordingly, in the first embodiment, since the flexure of the flexible portion F increases due to this lack of support, if the length L of the flexible portion F is long (for example, 10 mm or more), a dry film for forming a circuit (Etching resist film) could not follow, and as a result, it was difficult to form a good wiring pattern (that is, in the first embodiment, if the flexible portion F is not a short specification (for example, 5 mm or less), it can be handled. However, in the third embodiment, since such bending can be suppressed, it is possible to easily cope with a specification in which the length L of the flexible portion F is long.

  Moreover, although the example which formed the dummy pattern 21 in the slit remaining part 17c was shown in this Embodiment, since the bending of the flexible part F can be suppressed even if the said dummy pattern 21 is not provided, it does not necessarily need to provide. However, since the gap with the core substrate 11 can be reduced and the bending of the flexible portion F can be further suppressed, it is preferable to leave the dummy pattern 21 in order to form a good wiring pattern (see FIG. 6A). .

  Further, in the present embodiment, a recessed portion 19 depending on the slit portion 17 is formed in a portion corresponding to the slit portion 17 of the flexible substrate 14 (that is, a boundary portion between the flexible portion F and the rigid portion R of the flexible substrate 14). This is one of the characteristics (see FIG. 6A).

  That is, in both the first embodiment and the third embodiment, the resin of the BU insulating layer 4a that flows out when the flexible substrate 14 is laminated (the “resin shown in FIGS. 6A and 6B). (Corresponding to the reinforced portion 20 "), which is common in that the adhesive strength between the flexible substrate 14 and the BU insulating layer 4a can be increased (FIG. 6 (a) shows the flexible portion F of the third embodiment. 6B is an enlarged cross-sectional view of the flexible portion F of the first embodiment, wherein the slit remaining portion 17c and the dummy pattern 21 in FIG. Although they are removed, the shape of the flexible portion F does not change after the removal, and the recessed portion 19 remains formed.)

  However, as can be seen from FIGS. 6A and 6B, when the lengths of the flexible portions F are the same, the third embodiment is the first embodiment. As compared with the above, the bent portion of the flexible substrate 14 can be shortened (the “flexible portion” is the length “LL” of the “dent 19” in FIG. 6A and “ This corresponds to the length “L” of the flexible part F).

  Therefore, since the angle θ (see FIG. 6B) formed by the BU insulating layer 4a and the flexible substrate 14 can be made smaller than that in the first embodiment, the resin of the BU insulating layer 4a (“resin reinforcement” in the figure). Portion 20 ”) can be suppressed from flowing into the central side of the flexible portion F, and therefore, a decrease in the flexibility of the flexible portion F can be suppressed as compared with the first embodiment.

  In describing the first and third embodiments, an example in which different parts are formed in the rigid portion R and the flexible portion F as the protective means for the wiring pattern formed in the outer layer has been described. As described above, the manufacturing process can be shortened by integrating the flexible solder resist 15b having flexibility even after curing (that is, the solder resist can be collectively formed).

  Next, a fourth embodiment will be described with reference to FIGS.

  First, the core substrate 11b having the wiring pattern 2 on the front and back of the insulating substrate 1 and having the slits 17 similar to those shown in FIG. 5B1 is prepared (see FIG. 10A).

  Next, after roughening the wiring pattern 2 of the core substrate 11b, the first buildup layer C is formed on the outer layer on one surface of the core substrate 11b, and the second buildup is performed on the outer layer on the other surface of the core substrate 11b. Each layer D is stacked (see FIG. 10C). The thicknesses of the build-up layers C and D are substantially the same as in the first to third embodiments, and in the following embodiments, both are substantially the same thickness. Is omitted.

  Here, the first buildup layer C on which the first slit processing is laminated on the front surface A1 is a flexible substrate 14 laminated via a BU insulating layer 4a having a hollow portion 12d in a portion corresponding to the flexible portion F. The second build-up layer D, which is made of (the flexible substrate 14 composed of the flexible base substrate 13 and the metal foil 5) and laminated on the side B1 of the second counterbore processed later, is BU insulating. The metal foil 5 is laminated via the layer 4b (or the metal foil 6a with resin in which the BU insulating layer 4b is laminated in advance on one side of the metal foil 5) (see FIGS. 10B and 10C). .

  Next, after drilling the through-hole 7 at a desired position by drilling or the like, desmear treatment such as sodium permanganate or potassium permanganate is performed (see FIG. 10 (d)), then After the plating 8 is deposited on the entire surface including the through holes 7, the filling resin 9 is filled into the through holes 7 in which the plating 8 is formed (see FIG. 10E).

  Next, by forming a circuit such as a subtractive method on the substrate of FIG. 10 (e), an intermediate multilayer printed wiring board MP having a lead hole 10 connecting the wiring pattern 2b and the wiring pattern 2b on the front and back sides is formed. Then, after roughening the wiring pattern 2b (for example, soft etching processing mainly composed of formic acid or amine complexing agent), flexible insulation is provided on the front and back of the intermediate multilayer printed wiring board MP. The adhesive layer 18 and the metal foil 5 are sequentially laminated (see FIG. 11A).

  Next, through-holes 7a and non-through-holes 7b are drilled by drilling, laser processing, or the like in portions where via holes (TH or BVH) for interlayer connection are formed, and then sodium permanganate or potassium permanganate The substrate shown in FIG. 11B is obtained by sequentially performing a desmear process such as a system and a plating process.

  Next, as shown in FIG. 11C, by forming the circuit of the outer layer by the subtractive method, the wiring patterns 2d, TH10a, and BVH10b are formed, and then the solder resist 15 that protects the wiring pattern 2d is formed. Form.

  Next, the second slit processing is performed on the second slit processing scheduled portion 17b to form the punched portion 12 in the portion corresponding to the flexible portion F, and then the outer shape processing such as punching by a die or router processing. To obtain the rigid flex multilayer printed wiring board P shown in FIG.

  The remarkable point of this embodiment is that the flexible insulating adhesive layer 18 having flexibility even after curing formed on the entire outer layer of the flexible substrate 14 as a protection means for the wiring pattern 2b formed in the flexible portion F. It is in the point using.

Thereby, as a means for protecting the wiring pattern 2b formed in the flexible portion F, it is possible to save the trouble of providing a partial cover lay, and further to the upper layer of the flexible substrate 14 formed in the outer layer. A pattern (corresponding to “wiring pattern 2d” in FIG. 11C) can be formed.
Incidentally, although the example in which the wiring pattern 2d is provided on the flexible insulating adhesive layer 18 is shown in the present embodiment, it is not always necessary to provide the wiring pattern 2d. The pattern 2b can be exposed and used as a solder resist function.

  Further, in the present embodiment, as in the third embodiment, the description has been given by using the core substrate 11b in a state where the remaining slit portion 17c is left. Of course, it is also possible to use the core substrate 11c in which the cutout part 12b is formed (see FIG. 12A).

  Furthermore, in the present embodiment, the wiring pattern formed on the outer layer can also be formed on the flexible portion F (see FIG. 12B). Therefore, if a solid wiring pattern 2e connected to a ground layer (not shown) is formed in the flexible portion F and nickel plating or the like is deposited on the solid wiring pattern 2e, the upper layer of the wiring pattern 2b of the flexible portion F It is also possible to form the electromagnetic wave shielding layer 22 (in this case, it is necessary to form the cover lay 16 or the like in order to protect the shielding layer 22).

  Next, a fifth embodiment will be described with reference to FIG.

  In the present embodiment, in the first, third, and fourth embodiments, the flexible substrate in which the wiring pattern 2b is formed only on the outer layer side is laminated, but on the inner layer side of the flexible portion F. Also, a flexible substrate 14b on which the wiring pattern 2c is formed is laminated.

  Therefore, similarly to the fourth embodiment, it is easy to increase the wiring pattern (in this embodiment, only the flexible portion F increases) or to form an electromagnetic wave shielding layer on the flexible portion F. In the present embodiment, the wiring pattern 2c formed on the inner layer side of the flexible portion F has a configuration in which the plating 8 for forming the via hole is not formed. Compared with the fourth embodiment in which the plating 8 for forming the via hole is formed, the flexibility of the flexible portion F can be improved.

  Incidentally, FIG. 13A shows an example in which the cover lay 16 is provided as a protective layer of the wiring pattern 2c, but instead of the cover lay 16 and the BU insulating layer 4a according to the second embodiment, It is also possible to provide a flexible insulating adhesive layer 18 having flexibility even after curing (see FIG. 13B) and align the BU insulating layers 4a and 4b on the front and back with the flexible insulating adhesive layer 18 ( (Refer FIG.13 (c)).

  In addition, as a manufacturing method of the rigid flex multilayer printed wiring board of the present embodiment, for example, a flexible substrate 14b in which a metal foil such as a copper foil is laminated on the front and back of the flexible base substrate 13 is prepared, and the flexible portion F If the wiring pattern 2c is formed only on the portion located on the inner layer side (a coverlay is also formed if necessary), it is applied to the flexible substrate laminating step in the steps of FIGS. 2B and 5C. Thus, the rigid flex multilayer printed wiring board of the present embodiment can be easily obtained.

  Next, a sixth embodiment will be described with reference to FIGS. Since FIG. 14A has the same configuration as FIG. 2A1, the description of the manufacturing steps up to that point is omitted.

  First, as in FIG. 2 (b), the first counterbore processing of the core substrate 11 of FIG. 14 (a) in which the counterbore portion 12b is processed is laminated with the first buildup layer C on the side A, A second buildup layer D is laminated on the second counterbore surface B of the core substrate 11 (see FIG. 14C).

  Next, through-holes 7a and non-through-holes 7b are drilled by drilling, laser processing, or the like in portions where via holes (TH or BVH) for interlayer connection are formed, and then sodium permanganate or potassium permanganate The substrate shown in FIG. 14D is obtained by sequentially performing a desmear process such as a system and a plating process.

  Next, as shown in FIG. 15A, by forming the circuit of the outer layer by the subtractive method, the wiring patterns 2b, TH10a, and BVH10b are formed, and then the solder resist 15 that protects the wiring pattern 2b is formed. It forms (refer FIG.15 (b)).

  Next, the remaining second counterbore planned portion 12c is removed by the second counterbore processing to form the punched portion 12 in the flexible portion F, and then the outer shape processing such as punching by a die or router processing. To obtain the rigid flex multilayer printed wiring board P shown in FIG.

  What should be noted in the present embodiment is that the wiring pattern (corresponding to the wiring pattern 2c in FIG. 15C) formed in the flexible portion F is set to the inner layer side (that is, the first spot facing in FIG. 14A). The processing is formed only on the side facing the flange surface A).

  Thereby, since the plating 8 at the time of forming the via hole is not deposited on the wiring pattern 2c of the flexible part F, and the wiring pattern thickness of the flexible part F does not increase, it is compared with the first to fifth embodiments. And the flexibility of the said flexible part F can be improved.

  Further, in the present embodiment, the description has been given using the core substrate 11 on which the hollow portion 12b is formed in advance, but the slit remaining portion 17c (or the dummy pattern 21 is also included) as in the third embodiment. Of course, it is also possible to laminate the flexible substrate 14b in the state of remaining (see FIG. 16A). Also in this case, the effect that the wiring pattern formed on the outer layer side of the flexible part F can be satisfactorily formed is obtained.

  Further, as in the second embodiment, if the flexible substrate 14b is laminated through the flexible insulating adhesive layer 18 having flexibility even after curing instead of the BU insulating layer 4a, the flexible portion F is formed. The step of forming the partial coverlay 16 that protects the wiring pattern 2c to be protected can be omitted, and the opposite surface side (that is, the side facing the counterbore surface B in FIG. 14A). If the insulating layer is also a flexible insulating adhesive layer 18, warping and twisting can be further suppressed (see FIG. 16B).

  In describing the present invention, a six-layer rigid-flex multilayer printed wiring board has been described. However, the configuration is not limited to this, and it is of course possible to change within the scope allowed by the present invention.

  For example, even if the first buildup layer has a larger number of layers than in the embodiment of the present invention, the first counterbore processing and the step are performed before the BU insulating layer 4a and the flexible substrate 14 are laminated on the outermost layer. If the first slit processing is performed, a rigid-flex multilayer printed wiring board similar to that shown in the embodiment of the present invention can be easily obtained.

1: Insulating substrate 2, 2a, 2b, 2c, 2d: Wiring pattern 2e: Solid wiring pattern 3: Double-sided printed wiring board 4: Interlayer insulating layers 4a, 4b, 4c: BU (build-up) insulating layer 5: Metal foil 6, 6a: Metal foil 7 with resin, 7a: Through hole 7b: Non-through hole 8: Plating 9: Filling resin 10: Belle hole 10a: TH (through hole)
10b: BVH (blind via hole)
11, 11a, 11b: Core substrate 12, 12d: Bored portion 12a: First counterbore planned portion 12b: Counterbore portion 12c: Second counterbore planned portion 13: Flexible base substrates 14, 14a, 14b: Flexible Substrate 15: Solder resist 15a: SR (solder resist) extraction part 15b Flexible SR (solder resist)
16: Coverlay 17: Slit portion 17a: First slit processing scheduled portion 17b: Second slit processing planned portion 17c: Slit remaining portion 18: Flexible insulating adhesive layer 19: Recessed portion 20: Resin reinforcing portion 21: Dummy pattern P , Pa, Pb: Rigid flex multilayer printed wiring board MP: Intermediate multilayer printed wiring board R: Rigid part F: Flexible part A: First counterbore side B: Second counterbore side A1: first Slit processing side B1: Second slit processing side C: First buildup layer D: Second buildup layer L: Length of flexible portion LL: Length of recess

Claims (36)

  A rigid-flex multilayer printed wiring board comprising a rigid part that can be mounted on a component and a flexible part that can be bent, and includes at least a core substrate having a desired number of wiring pattern layers and one surface of the core substrate. A second build consisting of a first buildup layer having a flexible substrate stacked on the outer layer via at least a buildup insulating layer, a buildup insulating layer stacked on the outer layer on the other surface of the core substrate, and a wiring pattern Via layer that connects the upper layer, vertical wiring pattern, solder resist that protects the outer layer wiring pattern, coverlay that protects the wiring pattern formed in the flexible part of the outer layer wiring pattern, and flexible A hollow portion formed in a portion corresponding to the portion, and the first buildup layer Rigid-flex multilayer printed wiring board, characterized in that the two buildup layers are formed in substantially the same thickness.   The rigid-flex multilayer printed wiring board according to claim 1, wherein the build-up insulating layer is made of a glass woven fabric or a glass nonwoven fabric impregnated with a thermosetting resin.   The rigid-flex multilayer printed wiring board according to claim 1 or 2, wherein a cut-out portion is formed in a portion corresponding to the flexible portion in the build-up insulating layer on which the flexible substrate is laminated.   4. The rigid flex multilayer according to claim 3, wherein a boundary portion between the flexible substrate and the buildup insulating layer in the punched-out portion is covered with a resin reinforcing portion made of a resin that has flowed out of the buildup insulating layer. Printed wiring board.   The rigid-flex multilayer printed wiring board according to any one of claims 1 to 4, wherein a recess is formed in a boundary portion between the rigid portion and the flexible portion in the flexible substrate.   The rigid-flex multilayer printed wiring board according to claim 1, wherein a flexible insulating adhesive layer and a wiring pattern having flexibility even after curing are sequentially laminated instead of the build-up insulating layer and the flexible substrate of the first build-up layer. A rigid-flex multilayer printed wiring board characterized by being made.   The rigid-flex multilayer printed wiring board according to claim 1, wherein a flexible insulating adhesive layer and a wiring pattern having flexibility even after curing are sequentially laminated instead of the build-up insulating layer and the flexible substrate of the first build-up layer. In addition, instead of the build-up insulating layer and the wiring pattern of the second build-up layer, a flexible insulating adhesive layer and a wiring pattern having flexibility even after curing are sequentially laminated. Rigid flex multilayer printed wiring board.   The cover lay formed in the outer layer and the solder resist formed in the same layer as the cover lay are collectively formed of a flexible solder resist having flexibility even after curing. 8. The rigid-flex multilayer printed wiring board according to any one of 7 above.   The cover lay formed in the outer layer and the solder resist formed in the same layer as the cover lay are collectively formed of a flexible insulating adhesive layer having flexibility even after curing. The rigid-flex multilayer printed wiring board of any one of 1-7.   The rigid-flex multilayer printed wiring board according to any one of claims 1 to 9, wherein a wiring pattern formed on a flexible portion of the flexible substrate is also formed on the inner layer side.   A rigid-flex multilayer printed wiring board comprising a rigid part that can be mounted on a component and a flexible part that can be bent, and includes at least a core substrate having a desired number of wiring pattern layers and one surface of the core substrate. A second build consisting of a first buildup layer having a flexible substrate stacked on the outer layer via at least a buildup insulating layer, a buildup insulating layer stacked on the outer layer on the other surface of the core substrate, and a wiring pattern The flexible substrate having an upper layer, a via hole for connecting the wiring patterns in the vertical direction, a solder resist for protecting the wiring pattern of the outer layer, and a hollow portion formed in a portion corresponding to the flexible portion; The wiring pattern formed in the part corresponding to the flexible part is formed only on the inner layer side and A coverlay for protecting the wiring pattern is partially formed in the wiring pattern forming portion, and the first buildup layer and the second buildup layer are formed to have substantially the same thickness. Rigid flex multilayer printed wiring board.   The rigid-flex multilayer printed wiring board according to claim 11, wherein the build-up insulating layer is made of glass woven fabric or glass nonwoven fabric impregnated with thermosetting resin.   The rigid-flex multilayer printed wiring board according to claim 11 or 12, wherein a cut-out portion is formed in a portion corresponding to the flexible portion in the build-up insulating layer on which the flexible substrate is laminated.   The rigid flex multilayer according to claim 13, wherein a boundary portion between the flexible substrate and the buildup insulating layer in the punched-out portion is covered with a resin reinforcing portion made of a resin that has flowed out of the buildup insulating layer. Printed wiring board.   The rigid-flex multilayer printed wiring board according to any one of claims 11 to 14, wherein a recess is formed in a boundary portion between the rigid portion and the flexible portion in the flexible substrate.   The rigid-flex multilayer printed wiring board according to claim 11, wherein the flexible insulating adhesive layer has flexibility even after curing, instead of the flexible substrate on which the build-up insulating layer and the coverlay of the first build-up layer are formed. A rigid-flex multilayer printed wiring board, in which a flexible substrate on which no coverlay is formed is sequentially laminated.   The rigid-flex multilayer printed wiring board according to claim 11, wherein the flexible insulating adhesive layer has flexibility even after curing, instead of the flexible substrate on which the build-up insulating layer and the coverlay of the first build-up layer are formed. And a flexible insulating adhesive layer having flexibility even after curing instead of the build-up insulating layer and the wiring pattern of the second build-up layer A rigid-flex multilayer printed wiring board, wherein wiring patterns are sequentially laminated.   A method of manufacturing a rigid-flex multilayer printed wiring board comprising a rigid part capable of component mounting and a flexible part that can be bent, and a first step of forming a core substrate having at least a desired number of wiring pattern layers; A second step of forming a first buildup layer formed by sequentially laminating a buildup insulating layer and a flexible substrate on an outer layer on one surface of the core substrate; and a buildup on an outer layer on the other surface of the core substrate. A third step of forming a second buildup layer composed of an insulating layer and a metal foil, a fourth step of forming a via hole connecting the wiring patterns in the vertical direction, a fifth step of forming a wiring pattern of the outer layer, Protects the wiring pattern formed on the flexible part of the outer layer wiring pattern and the sixth step of forming the solder resist that protects the outer layer wiring pattern A seventh step of forming a coverlay and an eighth step of forming a hollow portion in a portion that will later become a flexible portion, and the thickness of the first buildup layer and the thickness of the second buildup layer A method for manufacturing a rigid-flex multilayer printed wiring board, wherein the thicknesses are formed to have substantially the same thickness.   The method for producing a rigid-flex multilayer printed wiring board according to claim 18, wherein the build-up insulating layer is made of a glass woven fabric or a glass nonwoven fabric impregnated with a thermosetting resin.   The rigid-flex multilayer printed wiring board according to claim 18 or 19, wherein the second step of laminating the flexible substrate is laminated via a build-up insulating layer having a cut-out portion in a portion corresponding to the flexible portion. Manufacturing method.   In the step of forming the punched portion in the eighth step, the slit portion along the contour of the cutout portion is first formed at the stage before the buildup insulating layer and the flexible substrate are laminated on the outer layer of the first buildup layer. At the stage where the first slit processing to form from the buildup layer side to the middle of the core substrate and the sixth and seventh steps to form the solder resist and coverlay, the first slit processing from the second buildup layer side 21. The method of manufacturing a rigid flex multilayer printed wiring board according to any one of claims 18 to 20, wherein the method is performed by second slit processing reaching a remaining slit portion of a portion corresponding to the formed flexible portion.   The method of manufacturing a rigid-flex multilayer printed wiring board according to claim 21, wherein a dummy pattern is formed on the upper surface of the remaining slit portion.   19. The method of manufacturing a rigid-flex multilayer printed wiring board according to claim 18, wherein the flexibility has flexibility even after curing instead of laminating the build-up insulating layer and the flexible substrate in the second step for forming the first build-up layer. A method for producing a rigid-flex multilayer printed wiring board, comprising sequentially laminating an insulating adhesive layer and a metal foil.   19. The method of manufacturing a rigid-flex multilayer printed wiring board according to claim 18, wherein the flexibility has flexibility even after curing instead of laminating the build-up insulating layer and the flexible substrate in the second step for forming the first build-up layer. Insulating adhesive layer and metal foil are laminated in order, and in place of lamination of build-up insulating layer and metal foil in the third step to form the second build-up layer, flexible insulation adhesion that has flexibility even after curing A method for producing a rigid-flex multilayer printed wiring board, comprising sequentially laminating an agent layer and a metal foil.   25. The solder resist removal portion is formed in a portion corresponding to the hollow portion of the second buildup layer in the sixth step of forming the solder resist. Manufacturing method of rigid flex multilayer printed wiring board.   In the sixth and seventh steps of forming the solder resist and the cover lay, the flexible solder having flexibility even after curing the cover lay formed in the outer layer and the solder resist formed in the same layer as the cover lay. The method for producing a rigid-flex multilayer printed wiring board according to any one of claims 18 to 25, wherein the method is formed in a lump with a resist.   In the sixth and seventh steps of forming the solder resist and the cover lay, the flexible insulation that has flexibility even after curing the cover lay formed in the outer layer and the solder resist formed in the same layer as the cover lay. The method for producing a rigid-flex multilayer printed wiring board according to any one of claims 18 to 25, wherein the formation is performed collectively with an adhesive layer.   28. The rigid flex according to any one of claims 18 to 27, wherein a flexible substrate in which a wiring pattern is previously formed on the inner layer side of the flexible portion is laminated as the flexible substrate laminated in the second step. A method for producing a multilayer printed wiring board.   A method of manufacturing a rigid-flex multilayer printed wiring board comprising a rigid part capable of component mounting and a flexible part that can be bent, and a first step of forming a core substrate having at least a desired number of wiring pattern layers; A second step of forming a flexible substrate in which the wiring pattern of the flexible portion is formed only on the inner layer side, and a third step of forming a coverlay for protecting the wiring pattern formed on the inner layer side of the flexible portion; A fourth step of forming a first buildup layer formed by sequentially laminating a buildup insulating layer and a flexible substrate obtained in the second and third steps on an outer layer of one surface of the core substrate; and the core Connect the 5th step of forming the second buildup layer consisting of the buildup insulating layer and metal foil on the outer layer of the other side of the board, and the wiring pattern in the vertical direction A sixth step of forming a via hole, a seventh step of forming a wiring pattern of the outer layer, an eighth step of forming a solder resist for protecting the wiring pattern of the outer layer, and a hollow portion in a portion that will later become a flexible portion A rigid-flex multilayer printed wiring board having a ninth step of forming, and forming the first buildup layer and the second buildup layer in substantially the same thickness Method.   30. The method of manufacturing a rigid-flex multilayer printed wiring board according to claim 29, wherein the build-up insulating layer is made of glass woven fabric or glass nonwoven fabric impregnated with thermosetting resin.   31. The rigid-flex multilayer printed wiring board according to claim 29 or 30, wherein the fourth step of laminating the flexible substrate is laminated via a build-up insulating layer having a hollow portion in a portion corresponding to the flexible portion. Manufacturing method.   The step of forming the hollow portion in the ninth step is a step before the build-up insulating layer and the flexible substrate are laminated on the outer layer of the first build-up layer, and the slit portion along the contour of the hollow portion is first In the stage where the first slit processing to be formed from the buildup layer side to the middle of the core substrate and the eighth step of forming the solder resist, the flexible part formed by the first slit processing from the second buildup layer side 32. The method of manufacturing a rigid-flex multilayer printed wiring board according to any one of claims 29 to 31, wherein the method is performed by a second slit process that reaches a remaining slit portion of a corresponding portion.   The method for manufacturing a rigid-flex multilayer printed wiring board according to claim 32, wherein a dummy pattern is formed on the upper surface of the remaining slit portion.   30. The method of manufacturing a rigid flex multilayer printed wiring board according to claim 29, wherein the fourth build-up layer forming the first build-up layer is replaced with a laminate of a flexible substrate on which a cover-lay is formed, and after curing. A method for producing a rigid-flex multilayer printed wiring board, comprising: sequentially laminating a flexible insulating adhesive layer having flexibility and a flexible substrate obtained in a second step in which a coverlay is not formed.   30. The method of manufacturing a rigid flex multilayer printed wiring board according to claim 29, wherein the fourth build-up layer forming the first build-up layer is replaced with a laminate of a flexible substrate on which a cover-lay is formed, and after curing. A fifth build-up insulating layer in which a flexible insulating adhesive layer having flexibility and a flexible substrate obtained in the second step where the coverlay is not formed are sequentially laminated and a second build-up layer is formed. A method of manufacturing a rigid-flex multilayer printed wiring board, wherein a flexible insulating adhesive layer having flexibility even after curing and a metal foil are sequentially laminated instead of laminating metal foil and metal foil.   36. In the eighth step of forming a solder resist, the solder resist removal portion is formed in a portion corresponding to the hollow portion of the second buildup layer. Manufacturing method of rigid flex multilayer printed wiring board.