TWI479972B - Multi-layer flexible printed wiring board and manufacturing method thereof - Google Patents

Description

Multilayer flexible printed wiring board and method of manufacturing same

The present invention relates to a multilayer flexible printed wiring board and a method of manufacturing the same, and more particularly to a build-up type multilayer flexible printed wiring board including a flexible cable portion, and a method of manufacturing the same.

In recent years, the high functionality of electronic devices, especially mobile phones, has been increasingly carried out. Accordingly, the components mounted on the multilayer flexible printed wiring board have also been replaced by chip-size packages (Chip-Size Package). Known as the Chip-Scale Package (hereinafter referred to as CSP), it has a tendency to be packaged with high functionality and high density, and does not increase the size of the substrate to add high functionality.

The gasket pitch of this CSP was originally 0.8 mm pitch, but in recent years, the system began to have a narrow pitch of 0.4 mm pitch. In the case of a narrow pitch CSP in which a CSP pad having a number of pads of 10 shims × 10 shims or more is placed in a full grid, the multilayer flexible printed wiring of the prior art is used. In the board, it is very difficult.

Here, the necessity of mounting the narrow pitch CSP on the multilayer flexible printed wiring board is as follows.

(1) There is no through hole in the CSP mounting spacer.

This is in order not to allow the solder required for installation to flow in.

(2) High-density configuration of the conduction portion is possible.

Since the spacer is directly connected to the wiring layer below from the narrow pitch CSP, it is necessary to set the pitch to be the same as the pitch of the spacer of the mounted CSP.

(3) Fine wiring forming ability.

This is because, regardless of the outer layer or the inner layer, it is necessary to wire the wires from a plurality of spacers of 100 or more. Moreover, the number of wirings to be wound between the CSP mounting pads is an important factor for determining the specifications of the mountable CSP. In particular, when the CSP is mounted, it is effective to make the wiring of the inner layer below the wiring of the outer layer of the CSP mounting pad fine.

(4) The flatness of the CSP mounting gasket.

This is because when the CSP is flip-chip mounted face down on the multilayer flexible printed wiring board, it is necessary to mount the CSP by the height of the solder ball on the CSP side spacer. The bumps are absorbed. In the multilayer flexible printed wiring board, it is necessary to fill the step difference due to the thickness of the conductor layer of each layer by a bonding material or the like to ensure flatness.

A flexible printed wiring board having a six-layer structure described in Patent Document 1 is a multilayer flexible printed wiring board that satisfies such a requirement. On the other hand, in the main substrate such as a mobile phone or a digital video camera, if the structure is a six-layer structure, the number of layers of the wiring layer is insufficient, and the case of using an eight-layer structure substrate is increased.

Another reason for using a substrate having an 8-layer structure is that a member is mounted on the first conductive layer of the substrate, and a ground layer is disposed on the second conductive layer, and the signal line is wound at the third conductive layer. The reason for this. The routing of the signal line is determined by the number of wires passing between the pins of the CSP. Therefore, the signal line connected to the lower layer is connected by a through hole disposed directly under the CSP mounting pad. The structure is most suitable for high density.

Further, by passing a plurality of signal lines between the pads in which the wiring layers of the signal lines are present, it is possible to correspond to the high-density CSP. Therefore, it is necessary to reduce the above-mentioned pad diameter as much as possible and to form the signal line as fine.

Fig. 5 is a view showing a constructor of a multilayer flexible printed wiring board of a 6-layer structure of the prior art. This wiring board is an 8-layer structure in which each of the stacked layers is provided in one layer.

In order to manufacture the wiring board, first, as shown in FIG. 5, a double-sided copper-clad laminate having copper foil on both sides of a flexible insulating base material such as polyimide or the like is prepared as a starting point. A double-sided flexible wiring board 101 of material.

Next, a double-sided flexible wiring substrate 102 as a stacked layer of the double-sided flexible printed wiring board 101 is prepared, and a cover layer 103 is formed on the inner layer side thereof. The double-sided flexible wiring substrate 102 to which the cover layer 103 is applied on the inner layer side is bonded to the double-sided flexible printed wiring board 101 via the adhesive material 104, and is a wiring substrate 105 of six layers.

Next, with respect to the wiring substrate 105 of the six layers, a via hole is formed by a laser processing or the like, and via-hole plating is performed to obtain interlayer conduction. Further, in order to stack one layer by one layer, via fill plating is selected in the via plating, whereby the via holes of the stacked layers are formed on the via holes of the wiring layer 102 of the 6 layers. The overlap is formed, and it can be set as a so-called stacked structure.

The single-sided flexible printed wiring board 107 is bonded to the wiring substrate 105 of the six layers via the bonding material 106, whereby stacking is performed. Then, a general-purpose hole is formed by laser processing or the like, and through-hole plating is performed to form a pattern of the outer layer, thereby obtaining a multilayer flexible printed wiring board 108 having an eight-layer structure.

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2007-128970

However, in the case of the multilayer flexible printed wiring board having the above-described six-layer structure, a multilayer flexible printed wiring board having an eight-layer structure in which one layer of each of the stacked layers is provided is used, The positional accuracy at the time of stacking and the size of the substrate when the multilayer flexible printed wiring board having a six-layer structure of the core substrate is manufactured is stretched and stretched, and the diameter of the pad cannot be reduced, and it is made to be between the pins of the CSP. Limitation when wiring is passed.

Further, in order to stack a single layer on a multilayer flexible printed wiring board having a six-layer structure, it is necessary to fill the holes of the core substrate by filling holes or the like, or to fill the through holes. Thick stacked backing material.

Therefore, there is also a problem that it is difficult to ensure the reliability of the interlayer connection of the stacked layers, or because the thickness of the stacked adhesive is thick, so that the amount of expansion and contraction of the substrate during hardening becomes large, so even It is an 8-layer structure, and it is difficult to manufacture a multilayer flexible printed wiring board in which a high-density CSP can be suitably mounted.

The present invention has been made in view of the above, and an object thereof is to provide a multilayer flexible printed wiring board capable of mounting a high-density CSP having a narrow pitch, and to manufacture the wiring board at low cost and in a stable manner. The method.

In order to achieve the above object, in the present application, the following inventions are provided.

According to the first aspect of the invention, there is provided a multilayer flexible printed wiring board having a three-layered stacked layer on at least one side of a core substrate having a wiring pattern on both sides, characterized in that: from the foregoing stacked layer The first conductive layer of the first layer from the side of the outer layer is provided with a mounting spacer having a package of a wafer size mounted thereon, and at least the second conductive layer of the second layer from the outer layer side of the stacked layer is at least a ground layer is provided directly under the region in which the wafer-sized package is mounted, and the third conductive layer of the third layer from the outer layer side of the stacked layer is provided with the jump from the mounting spacer a wiring pattern for guiding the signal circuit to be turned on by the jump-through via of the ground layer of the conductive layer, wherein the jump-through via is a bottomed blind via, and the bottom of the blind via is The back surface of the mounting pad of the first conductive layer is in contact with each other, and is provided with a through hole different from the stepped via hole for conducting the stacked layer and the core substrate, and is provided with the stacked layer Integrated flexible cable section.

According to the second aspect of the invention, there is provided a method of manufacturing a multilayer flexible printed wiring board having a three-layered stacked layer on at least one side of a core substrate having a wiring pattern on both sides thereof, wherein The method includes: (a) forming an opening for laser processing on a portion of the conductive hole formed on one of the two-sided flexible wiring substrate, and forming a ground layer on the other surface and guiding And (b) a surface of the flexible wiring substrate on which the wiring pattern is formed and a flexible insulating base material side of the single-sided flexible wiring substrate; The surface of the wiring substrate of the three-layer structure is bonded to the surface via the bonding material; and (c) the third layer of the conductive layer from the outer layer side of the wiring substrate which is the three-layer structure (3) the opening of the portion where the conductive hole of the conductive layer is formed is subjected to laser processing, and the bottomed conductive hole reaching the first conductive layer of the conductive layer of the first layer from the outer layer side is formed; and d) conducting the conductive portion for the aforementioned common hole And forming a blind via hole by electrolytic plating; and (e) forming a wiring pattern at the third conductive layer; and (f) forming a cap layer on the wiring pattern of the third conductive layer ( The work of the coverlay); and (g) the side of the stacked layer on which the cover layer is formed, toward the side of the core substrate to be separately fabricated, and laminated on the core substrate via the bonding material; and (h) a step of forming a conductive hole from the portion where the conductive hole of the first conductive layer is formed and reaching the conductive hole of the alloy substrate; and (i) conducting a conductive treatment on the conductive hole And the process of forming a through hole by electrolytic plating.

By virtue of the above features, the present invention achieves the following general effects.

In the multilayer flexible printed wiring board according to the present invention, since the first conductive layer (CSP mounting layer) is aligned with the third conductive layer (signal layer), the third conductive layer pad can be used. The small diameter is reduced, and the electrical characteristics can be improved by arranging the ground layer at the second conductive layer. Since the CSP mounting surface is the bottom side of the through hole, the flatness is ensured, and the CSP can be appropriately mounted without being affected by the recess of the through hole.

Moreover, in this case, since the cable can be disposed in the third conductive layer, the member mounting portion can be connected at the shortest distance. When the signal line exists in the second conductive layer, it is also possible to correspond to the arrangement of the cable in the second conductive layer.

Further, by directly connecting the stacked layers on both sides to the core substrate, the through holes or the through holes can be reduced. As a result, it is possible to manufacture a multilayer flexible printed wiring board capable of mounting a high-density CSP having a narrow pitch at a low cost and in a stable manner.

Hereinafter, embodiments of the invention will be described with reference to the attached drawings.

[Example 1]

1A to 1D are drawings showing the manufacturing method of the present invention. By this drawing, a manufacturing method of a multilayer flexible printed wiring board having an eight-layer structure having a cable portion is shown.

First, as shown in Fig. 1A (1), in the case of the double-sided copper-clad laminate 4, the positive-shaped mask 2a and the circuit pattern 2b at the time of laser processing of the copper foil 2 on the inner layer side are formed. The double-sided copper-clad laminate 4 is used, for example, on both sides of a flexible insulating base material 1 such as polyimine (here, a polyimide having a thickness of 12.5 μm), and has a thickness of 12 μm of copper foil 2 and 3 of them.

The positive mask 2a and the circuit pattern 2b are formed by etching the copper foil 2 by a photofabrication method. Moreover, the positive mask 3a at the time of laser processing is formed in the copper foil 3 which becomes the outer side. It is also possible to form the alignment mark and the like between the subsequent third conductive layer and the like. By this work, the wiring substrate 5 is obtained.

Then, as shown in FIG. 1A (2), generally, a thickness is provided at one side of a flexible insulating base material 6 such as polythenimine (here, a polyimide having a thickness of 12.5 μm). The so-called single-sided copper-clad laminate 8 of the copper foil 7 of 12 μm is used for demolding the alignment guides and the like, and the laminate 9 for laminating the wiring substrate 5 is previously prepared. Demoulding, and performing the alignment. The wiring substrate 5 on both sides and the wiring substrate on one side are laminated by roll bonding, flat plate pressing, vacuum pressing, or the like via the bonding material 9. In the engineering up to this point, a three-layer multilayer wiring substrate was obtained.

Next, as shown in FIG. 1A (3), laser processing is performed using the positive mask 7a, and the conductive hole 10 is formed. As the laser used in the laser processing, in addition to the infrared laser such as a carbon dioxide gas laser or a YAG laser, an ultraviolet laser such as an excimer laser or a UV-YAG laser may be selected.

The diameter of each of the common holes is set as follows. First, the general-purpose hole 10, when the flexible insulating base material 1 and 6 is used as in the case of the first embodiment, is 12.5 μm thick polyimine, since it can be used even at a diameter of 50 μm. The necessary plating thickness for ensuring reliability is about 10 μm, and therefore, the diameter is 50 μm.

Then, as shown in FIG. 1A (4), in general, a multilayer circuit substrate having three layers of the conductive holes 10 is subjected to electrolytic plating of about 10 μm to obtain interlayer conduction, and is formed as a stepped through hole 11. Here, a so-called buckle plating method in which plating is not applied except for the general-purpose hole is employed.

Next, as shown in FIG. 1A (5), generally, the outer layer side and the inner layer side of the three-layer multilayer wiring substrate, that is, the first conductive layer 7 and the third conductive layer 3, are formed on both sides. Circuit patterns 7b, 3c. A positive mask 7a for laser processing, a positive mask 3b for laser processing on the third conductive layer 3, and a positive mask 3b for laser processing are formed on the first conductive layer 7 by an etching method by photosensitive etching. Circuit pattern 3c. In the work up to this point, three layers of the wiring substrate 12 having the pattern formed thereon were obtained.

The alignment of the two sides at this time is performed for the flat material. Therefore, it is not affected by the expansion or the like of the material, and the high positional accuracy can be easily ensured. An exposure machine capable of high-precision alignment can also be used as necessary.

It is assumed that the first conductive layer 7 is a component mounting surface, the second conductive layer is a substantially flat wiring layer mainly formed of a ground layer, and the third conductive layer functions as a signal line. Since the alignment accuracy between the first conductive layer 7 and the third conductive layer 3 is directly related to the size of the pass pad of the via hole, etc., it is important in the formation of a high-density circuit.

Here, it is assumed that the mounting portion of the place where the high-density member such as the multi-pin CSP is mounted is the bottom side of the through hole of the above-described stepped through hole 11, and the mounting surface (first conductive layer) is There is no recess having a through hole, and a direct connection to the signal line of the third conductive layer 3 can be performed.

Further, since the circuit pattern of the third conductive layer 3 is not plated, it can function as a curved cable. On the other hand, the positional accuracy between the second conductive layer 2, the first conductive layer 7, and the third conductive layer 3 is compared with the alignment between the first conductive layer 7 and the third conductive layer 3 described above. It is not so important as long as it can form a margin of the via hole or a large-sized pad with a large diameter for grounding.

Needless to say, when importance is placed on the alignment between the first conductive layer 7 and the second conductive layer 2, the layers may be aligned with each other as long as they are fitted.

Next, as shown in FIG. 1B (6), a so-called cover layer 15 having a laminate 14 of propylene, epoxy resin or the like having a thickness of 25 μm is provided on, for example, a 12 μm-thick polyimide film 13 .

The cover layer 15 is attached by vacuum pressing, vacuum lamination, or the like on the third conductive layer 3 side of the wiring layer 12 on which the pattern is formed. As a result, since the inner side of the stepped through hole 11 is completely filled with the adhesive material 14, the phenomenon of expansion or the like does not occur in the reflow process in the state after moisture absorption. In the work up to this point, the stacked layer 16 to which the cover layer is attached is obtained.

Here, a series of projects from FIG. 1A (1) up to FIG. 1B (6) can be automated by a roll to roll. The multilayer flexible printed wiring board is produced at low cost.

Fig. 1B (7) is an enlarged cross-sectional view showing the periphery of the stepped through hole 11 in an actual size ratio, and the size of the actual through hole can be compared with the thickness of the cover layer 15 or the like. From this, it can be seen that the inside of the plated hole having a thickness of 10 μm can be filled in the stepped through hole 11 having a positive mask diameter of 50 μm by the cover layer 14 having a thickness of 25 μm. .

Fig. 1B(8) is a view showing the construction of the stacked layer 16b with the other one of the cover layers stacked on the opposite side of the double-sided copper-clad laminate.

1B(9) shows the structure of the double-sided copper-clad laminate which is to be held between the two stacked layers 16, 16b, that is, the core substrate 21. As shown in FIG. 1B (9), in general, the conductive hole 18 is formed by an NC drill or the like for the double-sided copper-clad laminate, and the conductive hole 18 is electrically conductively treated and electrically conductive. The electrolytic plating treatment after the treatment forms an interlayer conduction circuit.

The double-sided copper-clad laminate is provided on both sides of a flexible insulating base material 17 such as polyimine (here, a polyimide having a thickness of 25 μm), and has a copper foil having a thickness of 8 μm. . In the electrolytic plating treatment, an electrolytic plating film of about 10 μm is formed. In the project so far, the shape The through hole 18 is formed into a through-type conduction portion.

Further, the circuit patterns 19 and 20 are formed by a series of processes such as formation of a photoresist layer, exposure, development, etching, and photoresist layer peeling to form a circuit pattern on both sides by a photosensitive etching process. In the work up to this FIG. 1B (9), the double-sided core substrate 21 was obtained.

Next, as shown in Fig. 1C (10), the bonding material 22 for stacking the stacked layers 16 and 16b with the overcoat layer on the double-sided core substrate 21 is previously demolded and aligned.

Then, the stacked layer with the cover layer and the double-sided core substrate 21 are laminated by vacuum pressing or the like via the bonding material 20. In the work up to this point, the multilayer wiring substrate 23 is obtained. As the backing material 22, it is preferable to use a low-flow prepreg or a solder flake or the like. Next, the thickness of the material 22 can be selected to be about 15 μm.

Next, as shown in Fig. 1C (11), laser processing is performed using the positive masks 2a, 3a, and 7a, and four types of conductive holes 24, 25 for connecting the four layers are formed. In laser processing, UV-YAG laser, carbon dioxide laser, excimer laser, etc. can be selected for use.

The diameter of each of the common holes is set as follows. The general-purpose holes 24 and 25 have a problem of the degree of integration and the reliability of the interlayer connection. However, in the first embodiment, in the conductor layer of the eight layers, the layer from the second layer to the seventh layer Since the thickness of the conductor layer can be made thin by about 10 μm, the thickness of the binder 9 or the binder 14 and the binder 22 which are required for filling can be made thin.

As a result, even a thin plating thickness ensures reliability. The aperture which can ensure reliability with a plating thickness of 15 to 20 μm is set to a lower aperture of 100 μm at the common hole 24, and the upper aperture is considered to be aligned with the lower aperture, and the lower aperture is considered. When 100 μm was added to the upper surface and 200 μm was added, the hole was set to have a hole diameter of 100 μm. Further, desmear treatment and conductivity treatment for performing interlayer connection are performed by electroplating.

In addition, in the laser processing, in addition to the above-described general processing using a positive mask, it is also possible to apply a large window in which a copper mask having a larger beam diameter is offset and laser processing is performed in advance. (large window) method. Needless to say, a direct laser method in which copper foil and resin are directly penetrated by laser light can also be applied.

Further, the above-described processing using a positive mask can be combined with a large window method and a direct laser method. Further, when the direct laser method is used, as in the first embodiment, the thickness of the copper foil is preferably 20 μm or less.

Next, as shown in FIG. 1D (12), in general, the multilayer wiring substrate 26 having the conductive holes 24 and 25 is subjected to electrolytic plating of about 15 to 20 μm to conduct interlayer conduction. In the above-mentioned process, the stage through hole 27 obtained by the common hole 24 can be formed by one laser processing and plating process (the first conductive layer 7' and the second conductive layer are formed). The layer 2', the third conductive layer 3' and the fourth conductive layer 20' are connected to each other, and the jump-holes 28 obtained by the common via 25 (the first conductive layer 7 and the fourth conductive layer 19) It is connected) and can conduct all interlayer conduction from the outer layer to the inner layer.

In the work up to this point, the multilayer wiring substrate 29 in which the interlayer conduction is completed is obtained. Further, when it is necessary to insert a through hole for mounting a member or the like, the through hole may be formed by an NC drill or the like at the time of forming the common hole, and the through hole may be simultaneously formed during the plating of the through hole.

Next, as shown in Fig. 1D (13), the pattern 30 of the outer layer is formed by a usual photosensitive etching process. At this time, if there is a plating layer deposited on the overcoat layer 13 positioned on the inner layer side of the stacked layer 16 or 16b, this will also be removed.

Thereafter, a surface treatment such as solder plating, nickel plating, gold plating, or the like is applied to the surface of the substrate as needed, and a photo solder resist layer is formed, and a silver paste, a film, or the like is used to form a pair of outer layers of the cable. The protective layer on the side and the outer shape processing are used to obtain a multilayer flexible printed wiring board 32 having an eight-layer structure of the cable portion 31 on the outer layer.

2 is a longitudinal cross-sectional view showing a state in which the wafer size package 33 is mounted on the mounting pad 34 on the bottom side of the through hole of the stepped through hole 11. 2 is a view showing a multilayer flexible printed wiring board 32 having an 8-layer structure in which a wafer size package is mounted, in a ratio of a practical size, which is about 1 mm in thickness with respect to a general wafer size package. The thickness of the eight-layer flexible printed wiring board 32 is about 0.3 mm. Thereby, it can be seen that the eight-layer flexible printed wiring board 32 is extremely thin.

[Embodiment 2]

Fig. 3 is a cross-sectional view showing the structure of a second embodiment of the present invention. As shown in FIG. 3, by changing the place where the portion of the stacked layer 16b is broken, the cable portion of the outer layer can be formed in a single layer at the circuit 35 of the second conductive layer. form. As a result, an eight-layer flexible printed wiring board 37 having a single-layer cable at the outer layer was obtained.

With such a cable structure, it can be suitably applied to a portion where bending is required, such as a hinge portion of a mobile phone. Further, all of the layers can be directly connected by being combined with the through vias 38 as shown in FIG.

[Example 3]

Fig. 4 is a cross-sectional view showing the structure of a third embodiment of the present invention. As shown in FIG. 4, in general, by stacking one of the stacked layers and stacking in a bent state, the circuit 39 of the third conductive layer can be directly connected to the third conductive layer 3' on the opposite side. Further, the signal of the third conductive layer 3 which is the signal layer of the member mounted on the first conductive layer 7 can be efficiently connected to the third conductive layer 3' (the opposite signal layer) of the opposite surface.

Further, as the interlayer connecting four layers, the via hole 40 (the first conductive layer 7 and the core substrate 21 are connected) and the step via 41 (the first conductive layer 7' and the third conductive layer) may be formed. 3' and the core substrate 21 are connected to each other), the stage through hole 27 (the first conductive layer 7', the second conductive layer 2', the third conductive layer 3', and the core substrate 21 are connected to each other), and the stepped through hole 28 (the first conductive layer 7 is connected to the core substrate 21), and all of the interlayer conduction from the outer layer to the inner layer can be performed.

The multilayer flexible printed wiring board having an 8-layer structure resulting from the present invention is in alignment with the first conductive layer 7, 7' (CSP mounting layer) and the third conductive layer 3, 3' (signal layer). Therefore, the pads of the third conductive layers 3 and 3' can be made small in diameter, and the ground layer can be disposed on the second conductive layers 2 and 2' to improve the electrical characteristics.

Further, in this case, since the cable can be disposed at the third conductive layers 3, 3', the member mounting portion can be connected at the shortest distance. When the signal line exists in the second conductive layers 2, 2', it is also possible to correspond to the arrangement of the cable in the second conductive layers 2, 2'. Although it is necessary to arrange the through holes connecting the first conductive layers 7, 7' (CSP mounting layer) and the third conductive layers 3, 3' (signal layer) with a narrow pitch, due to the stepped through holes 28 (The first conductive layer 7 and the third conductive layer 3 are connected to each other) and have a small diameter of 70 μm. Therefore, the pitch can be set to a pitch of 0.3 mm or less.

Due to the above-mentioned situation, it is possible to use a multilayer flexible printed wiring board of 8-layer structure capable of carrying a high-density CSP having a narrow pitch without going through a high-cost perforation plating or other hole filling work. Manufacturing. Moreover, since there is no through hole in the CSP mounting spacer for other requirements, the flatness of the mountable CSP is also sufficiently ensured.

Further, since the stacked layer of the three-layer structure can be separated from the core substrate until the process of forming the cover layer and the flow is continuously performed by the roller to the roller, the automation and the humanization system are possible, and Can produce at low prices.

1. . . Flexible insulating substrate

2. . . Copper foil

2a. . . Orthotropic mask

2b. . . Circuit pattern

3. . . Copper foil

3a, 3b. . . Orthotropic mask

3c. . . Circuit pattern

4. . . Double-sided copper laminated board

5. . . Wiring substrate

6. . . Flexible insulating substrate

7. . . Copper foil

7a. . . Orthotropic mask

8. . . Single-sided copper laminated board

9. . . Subsequent

10. . . Universal hole

11. . . Jump through hole

12. . . Wiring substrate

13. . . Polyimine film

14. . . Subsequent

15. . . Cover layer

16, 16b. . . Stacking layer

17. . . Flexible insulating substrate

18. . . Through hole

19, 21. . . Circuit pattern

twenty one. . . Double-sided core substrate

twenty two. . . Subsequent

twenty three. . . Multilayer wiring substrate

24, 25. . . Universal hole

26. . . Multilayer wiring substrate with conductive holes

27. . . Stage via (connecting the first conductive layer - the third conductive layer to the core substrate)

28. . . Jump through hole (connecting the first conductive layer to the core substrate)

29. . . Multi-layer wiring substrate that ends the interlayer conduction

30. . . Outer layer pattern

31. . . Cable department

32. . . 8-layer flexible printed wiring board with cable section

33. . . Wafer size package

34. . . Mounting gasket

35. . . Cable portion of the second conductive layer

36. . . Cable portion of the third conductive layer

37. . . Multilayer flexible printed wiring board having an 8-layer structure with a single-layer cable at the outer layer

38. . . Through hole

39. . . Circuit of the third conductive layer (directly connected to the third conductive layer on the opposite side)

40. . . Through hole (connecting the first conductive layer to the core substrate)

41. . . Stage via (connecting the first conductive layer and the third conductive layer to the core substrate)

101. . . Double-sided flexible printed wiring board

102. . . Double-sided flexible wiring substrate

103. . . Cover layer

104. . . Next, the wiring substrate of the 1056 layer

106. . . Subsequent

107. . . Single-sided flexible printed wiring board

1088. . . Multilayer flexible printed wiring board

Fig. 1 is a conceptual sectional view showing a manufacturing process of a multilayer flexible printed wiring board of the present invention.

Fig. 2 is a cross-sectional structural view showing a multilayer flexible printed wiring board having an 8-layer structure in which a CSP is mounted, in one embodiment of the present invention.

Fig. 3 is a conceptual cross-sectional structural view showing another embodiment of the present invention.

Fig. 4 is a conceptual cross-sectional structural view showing another embodiment of the present invention.

Fig. 5 is a conceptual cross-sectional structural view of a multilayer flexible printed wiring board by a prior art method.

1. . . Flexible insulating substrate

2a. . . Orthotropic mask

2b. . . Circuit pattern

3a, 3b. . . Orthotropic mask

3c. . . Circuit pattern

4. . . Double-sided copper laminated board

5. . . Wiring substrate

6. . . Flexible insulating substrate

7. . . Copper foil

7a. . . Orthotropic mask

7b. . . Circuit pattern

8. . . Single-sided copper laminated board

9. . . Subsequent

10. . . Universal hole

11. . . Jump through hole

12. . . Wiring substrate

Claims (7)

A multilayer flexible printed wiring board is a multilayer flexible printed wiring board having a three-layer build-up layer on at least one side of a core substrate having a wiring pattern on both sides, and is characterized in that The first conductive layer of the first layer from the outer layer side of the stacked layer is provided with a mounting pad on which a wafer size package is mounted, and the second conductive layer of the second layer from the outer layer side of the stacked layer The layer is provided with a ground layer directly under the region in which the wafer-sized package is mounted, and the third conductive layer of the third layer from the outer layer side of the stacked layer is provided with the mounting spacer And a wiring pattern for guiding the signal circuit to be turned on by skipping the jump hole of the ground layer of the second conductive layer, wherein the jump hole is a blind via having a bottom, the blind The bottom of the through hole is in contact with the back surface of the mounting pad of the first conductive layer, and has a through hole that is different from the stepped through hole and that electrically connects the stacked layer and the core substrate. Flexible cable integrated with the aforementioned stacked layers unit. The multilayer flexible printed wiring board according to the first aspect of the invention, wherein the flexible cable portion is formed only by the second conductive layer of the stacked layer or the third conductive layer. A single layer cable. The multilayer flexible printed wiring board according to the first or second aspect of the invention, wherein the stacked layer is bent to the core The substrate is stacked on both sides of the substrate, and is provided with a flexible cable portion that connects the stacked layers. A method for producing a multilayer flexible printed wiring board, which is characterized in that a multilayer flexible printed wiring board having a three-layered stacked layer is provided on at least one side of a core substrate having a wiring pattern on both sides thereof, and is characterized in that The present invention includes: (a) forming an opening for laser processing on a portion of the conductive hole formed on one of the two-sided flexible wiring substrate, and forming a ground layer on the other surface; And (b) a flexible insulating substrate on which the surface of the flexible wiring substrate on which the wiring pattern is formed and the single-sided flexible wiring substrate; The surface of the material side is bonded to the wiring material to form a wiring substrate having a three-layer structure; and (c) the conductive layer of the third layer from the outer layer side of the wiring substrate which is the three-layer structure. The opening of the portion where the conductive hole of the third conductive layer is formed is subjected to laser processing to form a bottomed conductive hole reaching the first conductive layer of the conductive layer of the first layer from the outer layer side; And (d) for the aforementioned general purpose hole Conducting a conductive process and forming a blind via hole by electrolytic plating; and (e) forming a wiring pattern at the third conductive layer; and (f) forming the wiring pattern on the third conductive layer Forming a coverlay; and (g) forming a side of the aforementioned stacked layer forming the aforementioned cover layer, facing Further, the side of the foregoing core substrate is fabricated and stacked on the core substrate via a bonding material to form a stacked wiring substrate; and (h) for the aforementioned stacked wiring substrate, a guide from the first conductive layer is formed a process of forming a general-purpose hole to reach a common hole of the core substrate; and (i) performing a conductive process on the conductive hole and forming a through hole by electrolytic plating. The method for producing a multilayer flexible printed wiring board according to the fourth aspect of the invention, wherein the (e) project includes forming a wiring pattern on the third conductive layer, and the first The formation of the opening for the laser processing is performed at the portion where the conductive hole of the conductive layer is formed, and the (h) engineering is for forming the portion of the conductive hole of the first conductive layer with respect to the stacked wiring substrate. The opening for laser processing is used as a mask, and a project to reach a common hole at the core substrate by laser processing is formed. The method for producing a multilayer flexible printed wiring board according to the fourth aspect of the invention, wherein the (h) engineering is for the stacked wiring substrate, and the conductive hole of the first conductive layer At the formation site, a process of forming a common hole through which the entire core layer is formed including the core substrate is formed by a drill. The method for producing a multilayer flexible printed wiring board according to the fourth aspect of the invention, wherein In the above (g), the side of the stacked layer in which the cover layer is formed is bent toward the side of the core substrate which is separately formed, and is stacked on both sides of the core substrate via the adhesive. Engineering.