TWI500366B - Multilayer printed wiring board and manufacturing method thereof - Google Patents

Description

Multilayer printed wiring board and method of manufacturing same

The present invention relates to a multilayer printed wiring board and a method of manufacturing the same, and more particularly to a multilayer printed wiring board having a hole-filling structure and a method of manufacturing the same.

In recent years, the miniaturization and high performance of electronic devices have become more and more advanced, and the demand for higher density of printed wiring boards has been increased. For this reason, a multi-layer printed wiring board having a high density has been bonded to a plurality of printed wiring boards, and has been widely spread around small electronic devices such as portable telephones and digital cameras. A multilayer printed wiring board in which a flexible printed wiring board is laminated is disclosed as an example of a printed wiring board having a high density (for example, see Patent Document 1).

Further, in Patent Documents 2 and 3, the through-holes have a vertical cross-sectional shape in a drum shape, or the tapered top portions are formed in a mutually matching shape to form a through hole filled with a plating metal (hereinafter referred to as a "filled through hole"). )Methods.

[Advanced technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2004-200260

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2004-311919

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2003-046248

Here, a method of manufacturing a multilayer flexible printed wiring board according to a comparative example will be described with reference to FIGS. 5A and 5B.

(1) First, a double-sided copper-clad laminate in which copper foil is formed on both surfaces of a flexible insulating base film made of polyimide. Further, the inner layer circuit substrate 100 is produced by forming a through hole, plating a copper plating, and patterning a copper foil on the double-sided copper clad laminate. As can be understood from Fig. 5A (1), the inner layer circuit substrate 100 has a wiring pattern formed on both surfaces of the insulating base film and a plated through hole electrically connecting the wiring patterns on both sides.

(2) Next, as can be understood from Fig. 5A (1), in order to insulate and protect both sides of the inner layer circuit substrate 100, a cover layer having the insulating film 130 and the adhesive layer 120 is used using a vacuum laminator or the like. 110, laminated on both sides of the inner layer circuit substrate 100. Thereby, the core substrate 200 is produced.

(3) Next, an outer layer circuit substrate 300 for the build-up layer is produced. The outer layer circuit substrate 300 processes the double-sided copper foil of the double-sided copper clad laminate in accordance with a predetermined pattern. The wiring pattern of the outer layer substrate 300 has an opening portion 310 at a blind hole forming portion. The opening portion 310 functions as a positive-shaped mask in the laser processing process in the subsequent stage.

(4) Next, the multilayer circuit substrate 300 is laminated by laminating the adhesive layer 210 on both surfaces of the core substrate 200, whereby the multilayer circuit substrate 400 shown in Fig. 5A (1) is produced.

(5) Next, as shown in Fig. 5A (2), blind vias and via holes are formed in the multilayer circuit substrate 400. More specifically, the opening portion 310 of the outer layer circuit substrate 300 is irradiated with laser light to perform laser processing to form a blind hole 410 in which the wiring pattern of the inner layer circuit substrate 100 is exposed on the bottom surface, and the outer circuit substrate 300 is exposed on the bottom surface. A blind hole 420 of the wiring pattern inside. Further, drilling is performed at a portion where the through hole is formed, thereby forming a through hole 430 penetrating the multilayer circuit substrate 400.

(6) Next, as shown in Fig. 5A (3), the multilayer circuit substrate 400 on which the blind vias 410, 420 and the via holes 430 are formed is subjected to a plating treatment to form a plating film 450. A plating film 450 is formed on the side faces of the blind holes 410, 420 and the through holes 430, whereby the plating blind holes 460, 470, 480 and the plated through holes 490 functioning as interlayer connection paths are formed.

(7) Next, as shown in Fig. 5B (4), the outer layer circuit wiring pattern 500 is formed by processing the conductive film on the surface of the outer layer substrate 300 in a predetermined pattern by a photosensitive etching process.

(8) Next, as shown in Fig. 5B (5), the insulating protective outer layer wiring pattern 500, the plating blind holes 460, 470, and 480, and the solder resist 510 of the plated through holes 490 are formed. The solder resist 510 has an opening 510a formed at a predetermined portion where the terminal for mounting the component and the terminal for connection are formed. Further, as the insulating protective material, a cover layer may be used instead of the solder resist.

(9) Next, the outer layer circuit wiring pattern 500 exposed on the bottom surface of the opening 510a is subjected to surface treatment such as gold plating or tin plating to form the terminal 520.

The multilayer flexible printed wiring board 600 having the plated blind holes 460, 470, and 480 and the plated through holes 490 is completed by the above process.

As can be understood from Fig. 5B, the terminal 520 is not disposed directly above the plating blind holes 460, 470, 480, and the plated through holes 490. This is for the parallel mounting of a multilayer flexible printed wiring board, which is typically a bare wafer such as a Chip Size Package (CSP). That is, when electronic components are mounted directly above the plating blind holes 460, 470, and 480 and the plated through holes 490, it is difficult to mount the electronic components in parallel with the printed wiring boards. In order to understand the reason, the installation process of the CSP is explained.

First, a plurality of solder balls provided on the terminals of the CSP are placed on the printed wiring board so as to be placed on the printed wiring board so as to be positioned directly above the plating blind holes 460, 470, and 480 and the plated through holes 490. Then, in the soldering process, the solder balls are dissolved to fix the CSP to the printed wiring board. However, as shown in FIG. 5B (5), since the depths of the plated blind holes 460, 470, 480, and the plated through holes 490 are different, the amount of molten solder sucked into the holes is different for each hole. . As a result, the CSP cannot be mounted in parallel to the printed wiring board.

Therefore, it is not possible to provide terminals directly above the plating blind holes 460, 470, 480, and the plated through holes 490, such as the terminal 520 shown in FIG. 5B (5), which must be in the self-plating blind holes 460, 470, 480, and A terminal is provided at a position where the plated through hole 490 is offset right and left.

In recent years, the miniaturization and high performance of electronic devices such as digital cameras have been amazing, and the pitch of CSP pads has become increasingly narrow. Specifically, the pitch of the pad of about 0.8 mm is 0.5 mm or less, and in response to this, the printed wiring board is required to have a higher density.

However, as described above, in order to limit the position of the terminal, it has been conventionally difficult to mount a chip having a narrow pitch and a plurality of stitches, for example, a CSP having a gate voltage of 10 × 10 or more pads is extremely difficult.

Therefore, it is considered to form a hole-filling structure by a filling plated process of filling a metal through a blind hole or a via hole. As described above, Patent Documents 2 and 3 propose a method in which the through hole has a vertical cross-sectional shape in a drum shape to form a through hole.

However, none of these documents is aimed at a single-layer substrate made of a single material, and it is not applicable to a multilayer printed wiring board. For example, in the case of the multilayer printed wiring board shown in Fig. 5B (5), the processed layer is formed by laminating various materials having different processing characteristics such as an insulating film, an adhesive, and a copper foil. Therefore, even if laser processing or the like is employed, it is extremely difficult to process the layer to be processed into a drum shape in a longitudinal section.

Furthermore, in the case of a multilayer printed wiring board, there are other problems. That is, the terminals of the electronic component are not only disposed on the through hole, but also must be disposed on the blind hole, but due to the through hole and the blind hole, the fluidity of the plating solution is different in structure, so there is a so-called It is quite difficult to handle in the same hole filling process. More specifically, the hole-fill plating treatment has a feature that the fluidity of the plating solution is low, and the efficiency is relatively easy. In the case of a bottomed blind hole, since the fluidity of the plating solution is low, a good hole-filling structure can be obtained. On the other hand, in the case of a through hole, since the fluidity of the plating solution is high, it is impossible to efficiently fill the plating metal into the through hole.

According to an aspect of the present invention, there is provided a first outer layer circuit substrate comprising: an inner layer circuit substrate; a dielectric layer laminated on a surface of the front inner circuit substrate; the dielectric layer is laminated in the pre-record a second outer layer circuit substrate of the inner layer circuit substrate; and a through hole for the first outer layer circuit substrate, the front inner layer circuit substrate, and the second outer layer circuit substrate, which are filled with the filling metal a through hole, a first pinhole through which the first outer layer circuit substrate is connected, an inner layer through hole penetrating the inner layer circuit substrate, and a second pin penetrating the second outer layer circuit substrate The hole, the first and second pinholes, has a multilayer printed wiring board characterized by a minimum opening diameter larger than the maximum opening diameter of the inner layer through hole.

According to another aspect of the present invention, there is provided a double-sided metal-clad laminate in which an insulating base film having flexibility and a metal foil formed on both surfaces of the insulating base film are prepared, and a metal-clad surface is formed in the thickness direction. The inner layer through hole of the laminated board is patterned by forming a metal foil of the double-sided metal-clad laminate, and an inner layer wiring pattern is formed, thereby preparing an inner layer circuit substrate, and preparing an insulating base film having flexibility: And the first and second metal-clad laminates of the metal foil formed on at least one of the insulating base films, and the metal foil of the first metal-clad laminate is patterned to form a first outer wiring pattern. The first outer circuit substrate is formed, and the metal foil of the second metal-clad laminate is patterned to form a second outer wiring pattern, thereby fabricating a second outer circuit substrate, which is preceded by the surface of the inner circuit substrate. The first outer layer circuit substrate is preceded by the first outer layer wiring pattern being placed on the outer side, and the insulating layer is laminated, and the second outer layer circuit substrate is preceded by the inner layer of the inner layer circuit substrate. Previously recorded The outer wiring pattern is placed on the outer side, and an insulating layer is laminated to form a multilayer circuit substrate, and a laser processing process for irradiating the laser light to a predetermined field of the pre-recorded multilayer circuit substrate is used. The first outer layer circuit substrate is a first pinhole that communicates with a minimum opening diameter larger than a maximum opening diameter of the inner layer through hole, and a through hole inner layer through hole and a second outer layer circuit substrate, and a second pinhole having a minimum opening diameter larger than a maximum opening diameter of the inner layer through hole of the preceding layer, forming a through hole penetrating the multilayer circuit substrate beforehand, and performing a filling plating process for filling the plating hole with the front via hole. A method of manufacturing a multilayer printed wiring board in which an inner layer wiring pattern, an upper first wiring pattern, and a second outer wiring pattern filled through hole are electrically connected is formed.

The through hole according to the embodiment of the present invention is configured to communicate with the first pinhole penetrating the first outer layer circuit substrate, the inner layer through hole penetrating the inner layer circuit substrate, and the second through hole of the second outer layer circuit substrate. Pinhole. Further, the first and second pinholes have a minimum opening diameter which is larger than the maximum opening diameter of the inner layer through hole. In the through hole having such a configuration, the connecting portion of the first pinhole and the inner layer through hole and the connecting portion of the second pinhole and the inner layer through hole form a corner portion, and the through hole is filled with the plating metal By having a corner portion, the fluidity of the plating solution is lowered, and the plating metal is easily precipitated. Furthermore, since the first and second pinholes are formed as a minimum opening diameter which is larger than the maximum opening diameter of the inner layer through hole, the through hole is made smaller toward the inner layer side. Therefore, at the time of the hole-fill plating treatment, the inner-layer through-holes are first blocked by the plating metal, and the upper and lower V-shaped recesses are formed. Thereby, since high-quality filled through-holes can be formed by suppressing generation of bubbles or the like, and the fluidity of the plating solution is further lowered, the efficiency of the hole-fill plating process is improved, and the formation time of the filled through-holes can be shortened.

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

The components having the same functions in the respective drawings are denoted by the same reference numerals, and the detailed description of the components of the same reference numerals will not be repeated. Further, the drawing surface is represented by the feature portion, and the relationship between the thickness and the plane size, the ratio of the thickness of each layer, and the like are different from the actual object.

The method for manufacturing the multilayer printed wiring board according to the present embodiment will be described with reference to FIGS. 1A, 1B, 2A, 2B, 3, 4A, and 4B.

First, the manufacturing method of the core substrate will be described using FIG. 1A.

(1) A double-sided copper clad laminate 4 having a flexible insulating base film 1 made of polyimide or the like, and a copper foil 2 and a copper foil 3 formed on both surfaces of the insulating base film 1 .

(2) Next, it can be understood from Fig. 1A (1) that the double-sided copper clad laminate 4 is formed by double-sided copper lamination by NC bit processing (or laser processing). The inner layer through hole 5 of the plate 4.

(3) Next, it can be understood from Fig. 1A (1) that after the desmear treatment and the conductive treatment are performed on the inner layer via hole 5, the double layer of the inner layer via hole 5 is formed. The copper laminate 4 is fully subjected to a plating treatment (for example, electrolytic copper plating treatment). Thereby, the plating film 6 is formed on the inner walls of the copper foils 2, 3 and the inner layer through holes 5, and the plated through holes 7 for electrically connecting the copper foil 2 and the copper foil 3 are formed.

(4) Next, the double-sided conductive film (the plating film 6 and the copper foils 2, 3) of the insulating base film 1 is processed in a predetermined pattern by a subtractive process. More specifically, an etching layer (not shown) of a dry film resist or the like is formed so as to cover the plating film 6 and the plated through hole 7, and then the etching layer is exposed and developed by a photolithography process. The pattern is used to process the etch layer. Then, the plating film 6 and the copper foils 2 and 3 are etched by using the patterned etching layer as a mask to form the inner layer wiring patterns 8A and 8B. Then, the etching layer is peeled off.

By the process thus far, as shown in FIG. 1A (1), the inner layer wiring patterns 8A and 8B are formed on the front surface and the inner surface, respectively, and the inner layer circuit substrate 10 having the plated through holes 7 is formed.

Further, in the above-described order, although the plating treatment is performed after the formation of the inner layer via hole 5, the patterning of the copper foils 2, 3 may be performed without performing the plating treatment.

(5) Next, a cover layer 13 having an insulating film 12 made of a polyimide film or the like and an adhesive layer 11 formed on one surface of the insulating film 12 is prepared. The subsequent agent layer 11 is made of, for example, an adhesive such as acryl, epoxy resin or the like. Further, in order to insulate and protect the inner layer wiring patterns 8A, 8B, the respective cover layers 13 are laminated on both sides of the inner layer circuit substrate 10 using a vacuum laminator or the like. Through this process, the core substrate 20 shown in Fig. 1 (2) is produced. Further, as shown in FIG. 1 (2), the inner layer wiring patterns 8A, 8B and the plated through holes 7 are filled by the adhesive layer 11.

Next, a method of manufacturing the outer layer circuit substrates 40 and 50 which are laminated layers in the core substrate 20 will be described with reference to FIG.

(1) First, a double-sided copper clad laminate 34 and a double-sided copper clad laminate 44 are prepared. The double-sided copper-clad laminate 34 (44) has a flexible insulating base film 31 (41) made of polyimide or the like, and a copper foil 32 (42) formed on both sides and Copper foil 33 (43).

(2) Next, the copper foils 32 and 33 of the double-sided copper clad laminate 34 are processed in a predetermined pattern by the subtractive method, thereby producing the outer layer substrate 40 shown in Fig. 1(a). . The copper foil 32 has openings 35, 37, and 38, and the copper foil 33 has an outer layer wiring pattern 39 including the opening 36.

Similarly, the copper foils 42 and 43 of the double-sided copper clad laminate 44 are processed in a predetermined pattern to fabricate the outer layer substrate 50 shown in Fig. 1B(b). The copper foil 42 has an outer layer wiring pattern 49 including an opening 47, and the copper foil 43 has openings 45, 46, and 48. The openings 35 to 38 and the openings 45 to 48 are provided in a predetermined area in which the through holes or the blind holes are formed, and function as a conformal mask in the laser processing in the subsequent stage.

Moreover, in FIGS. 1B (a) and (b), the shapes of the opening 36 and the opening 45 when viewed from the lower side in the drawing are shown. In the case of the opening portions 36 and 45, the opening portions 36 and 45 are formed in a star shape having a plurality of concave portions in a leaf shape with reference to the minimum opening diameter, and the inner opening is tried to be based on the maximum opening diameter. A plurality of protrusions are formed.

Next, a method of producing the flexible printed wiring board according to the present embodiment will be described using the core substrate 20, the outer layer circuit substrate 40, and the outer layer circuit substrate 50 which are produced as described above.

(1) As shown in Fig. 2A (1), the outer layer base materials 40 and 50 are interposed with the adhesive layer 51, and are laminated on the surface and the inside of the core substrate 20, respectively. Thereby, the multilayer circuit substrate 60 shown in FIG. 2A (2) is produced. The field of the unstacked multilayer circuit substrate is a flexible electric wire portion for pulling out wiring.

Further, as the adhesive material applied to the adhesive layer 51, it is desirable that the low flow type so-called pre-stained body or adhesive sheet has a small amount of outflow.

(2) Next, as shown in Figs. 2A (2) and (3), the openings 35, 37, 38, 45, 46, 48 of the multilayer circuit substrate 60 are irradiated with laser light (for example, a CO ₂ laser). , performing a Conformal laser. Thereby, the through hole 61 and the blind holes 62 to 65 are formed. Then, the through holes 61 and the blind holes 62 to 65 are cleaned by a glue removal process or the like.

As shown in FIG. 2A (3), the through hole 61 penetrates the multilayer circuit substrate 60 in the thickness direction, and penetrates the insulating base film 31, the adhesive layer 51 (upper side), and the insulating film in more detail from the upper side to the lower side in the drawing. 12 (upper side), adhesive layer 11 (upper side), adhesive layer 11 (lower side), insulating film 12 (lower side), adhesive layer 51 (lower side), and insulating base film 41.

The blind via 62 penetrates the insulating base film 31, the adhesive layer 51, the insulating film 12, and the adhesive layer 11, and the plating film 6 is exposed on the bottom surface thereof. The blind via 62 is a skip via hole that skips the outer wiring pattern 39 disposed inside the outer layer circuit substrate 40.

The blind via 63 penetrates the insulating base film 41, the adhesive layer 51, the insulating film 12, and the adhesive layer 11, and the plating film 6 is exposed on the bottom surface thereof. The blind hole 63 is a step via hole in which the copper foil 42 is exposed at the middle portion.

The blind via 64 penetrates the insulating base film 31, and the bottom surface thereof is a blind via which exposes the copper foil 33. The blind via 65 penetrates the insulating base film 41, and the bottom surface thereof is a blind via which exposes the copper foil 42.

Here, the structure of the through hole 61 will be described in more detail using FIG. Fig. 3 is an enlarged cross-sectional view showing a portion (A portion) which is framed by a broken line in Fig. 2A (3). The through hole 61 is configured to communicate with the inner layer through hole 5, the pinhole 67, and the pinhole 66.

The pinhole 67 is a stepped blind hole having an upper hole formed by the opening 35 of the copper foil 32 as a mask and a lower hole formed by using the opening 36 of the copper foil 33 as a mask. As shown in Fig. 3, the diameter is increased in the order of the inner layer through hole 5, the hole below the pinhole 67, and the hole above the pinhole 67. That is, the diameter of the through hole penetrating the multilayer circuit substrate is smaller as the step toward the inner layer side.

The pinhole 66 is a pinhole formed by the opening 45 of the copper foil 43 as a mask. As shown in Fig. 3, the diameter of the pinhole 66 is larger than the diameter of the inner layer through hole 5.

In general, the maximum opening diameter of the inner layer through holes 5 provided in the inner layer circuit substrate 10 is smaller than the minimum opening diameter of the pin holes 66, 67 provided in the outer layer circuit substrates 40, 50. Here, the maximum opening diameter means the maximum value of the opening diameter. If the cross-sectional shape of the inner layer through hole 5 is a circle as shown in Fig. 3, the maximum opening diameter is the diameter of the circle (the length a in Fig. 3).

Here, the minimum opening diameter means the minimum value of the opening diameter. If the cross-sectional shape of the lower hole of the pinhole 66 or the pinhole 67 is a star having a protrusion toward the inner side as shown in FIG. 3, the minimum opening diameter is such that the star faces face between the two protrusions. Distance (length b in Figure 3).

The top and bottom of the enlarged cross-sectional view of Fig. 3 are plan views showing the through holes 61 when the through holes 61 are viewed from the upper side and the lower side, respectively.

The cross section of the hole below the pinhole 67 is the same as the shape of the opening 36. Therefore, the side wall of the hole below the pinhole 67 reflects the star shape of the opening portion 36 to form irregularities. Similarly, the cross section of the pinhole 66 is the same as the shape of the opening 45. Therefore, the side wall of the pinhole 66 reflects the star shape of the opening 45 to form irregularities.

(3) Next, as shown in FIG. 2B (4), the via hole 61 and the blind via holes 62 to 65 are electrically conductive. Then, by using a plating solution (copper sulfate plating additive such as Top Lucina THF manufactured by Okuno Pharmaceutical Co., Ltd.) for the hole-fill plating treatment, a hole-fill plating process (electrolytic plating process), a through hole 61, and a blind hole The plating metal 68 is filled in 62 to 65 to form a filled through hole 71 and a filling hole 72 to 75.

Thereby, as shown in FIG. 2B (4), the multilayer circuit substrate 70 in which the through holes 61 are filled with the plating metal 68 and the blind holes 62 to 65 can be obtained.

Here, the manner in which the plating metal 68 is filled in the through hole 61 will be described in detail using FIGS. 4A and 4B.

As shown in Fig. 4A (1), at the initial stage of the hole-fill plating process, the plating metal 68 is deposited centering on the corner portion C having a small fluidity of the hole-fill plating solution. Then, the plating treatment is carried out in association, and as shown in Fig. 4A (2), the plating metal deposited in the through hole 61 is in the shape of a drum having the smallest diameter D in the through hole 61 as the top.

If the plating treatment is further performed, as shown in Figs. 4A (2) and (3), the through hole 61 is occluded in the field D by the plating metal 69. As a result, as shown in Fig. 4A (3), the upper and lower two recessed portions 69 are formed. Since the concave portion 69 is formed, the fluidity of the plating solution is further lowered, thereby promoting plating and filling.

Then, the hole-fill plating treatment is carried out, and as shown in Figs. 4B (4) and (5), the concave portion 69 becomes shallow, and finally becomes a predetermined depth or less, and the hole-fill plating treatment is completed.

In this manner, since the through hole 61 is formed to have a corner portion and the inner diameter is reduced, the through hole 61 can be filled with the plating metal 68 so that bubbles or the like can be generated quickly.

Moreover, the blind vias 62, 63, 64, 65 can also be filled with the plating metal 68 by the via plating process of the via 61. Therefore, the plating and hole filling process of the through hole 61 and the blind holes 62, 63, 64, 65 can be unified.

Further, as will be described with reference to Fig. 3, the lower hole of the pinhole 67 and the side wall of the pinhole 66 are provided with a plurality of concave portions in a pleated shape. Since the fluidity of the plating solution is also lowered by the concave portion, the plating metal is deposited to the concave portion during the hole filling plating treatment. As a result, the filling of the metal can be performed more quickly.

(4) Next, as shown in FIG. 2B (5), the outer layer wiring patterns 80A and 80B are formed by etching the conductive film on the surface layer of the multilayer circuit substrate 70 in accordance with a predetermined pattern by the above-described subtraction method.

(5) Next, as shown in Fig. 2B (6), the solder resist 91 for protecting the outer layer wiring patterns 80A, 80B is formed. The solder resist 91 has an opening 91a at a predetermined portion where the terminal for mounting the component and the terminal for connection are formed ^. Further, instead of the solder resist, a protective film of the outer layer wiring patterns 80A and 80B may be formed using a cover layer.

(6) Next, as shown in Fig. 2B (6), the plating metal 36 exposed on the bottom surface of the opening 91a is subjected to a surface treatment such as gold plating or tin plating to form the terminal 92.

Through the above process, the multilayer flexible printed wiring board 90 according to the embodiment of the present invention is completed.

Next, the configuration of the multilayer flexible printed wiring board 90 of the present embodiment will be described.

As shown in FIG. 2B (6), the multilayer flexible printed wiring board 90 is formed by laminating a plurality of circuit boards 40 and 50 on the front surface and the back surface of the inner layer circuit board 10. The multilayer circuit substrate 40 is laminated on the surface of the inner layer circuit substrate 10 via an insulating layer (the adhesive layer 11, the insulating film 12, and the adhesive layer 51). The multilayer circuit substrate 50 is laminated on the inside of the inner layer circuit substrate 10 via an insulating layer (the adhesive layer 11, the insulating film 12, and the adhesive layer 51).

Further, the multilayer flexible printed wiring board 90 is a through hole 61 that penetrates the outer layer circuit board 40, the inner layer circuit board 10, and the outer layer circuit board 50, and has a filled through hole 71 filled with a plating metal.

The through hole 61 is configured to communicate with a pinhole 67 penetrating the outer layer circuit substrate 40, an inner layer through hole 5 penetrating the inner layer circuit substrate 10, and a pinhole 66 penetrating the outer layer circuit substrate 50. Further, the pinholes 66 and 67 have a minimum opening diameter which is larger than the maximum opening diameter of the inner layer through hole 5.

The filled through hole 71 is a wiring pattern electrically connected to both surfaces of the outer layer circuit substrate 40, a wiring pattern provided on both surfaces of the inner layer circuit substrate 10, and a wiring pattern provided on both surfaces of the outer layer circuit substrate 50. A total of six floors. Further, a plating film 6 is provided on the side wall of the through hole 5, and the reliability of the interlayer connection filling the through hole 71 can be further improved.

Further, in the multilayer flexible printed wiring board 90, the blind holes are also provided with the filling holes 72 to 75 filled with the plating metal. The surface vias 74 and 75 are electrically connected to a double-layer wiring pattern provided on both sides of the outer layer circuit substrates 40 and 50 of the build-up layer. The surface via 72 is a wiring pattern electrically connected to the double layer of the outer layer circuit substrate 40 and the inner layer circuit substrate 10. Further, the surface via 73 electrically connects the wiring patterns provided on both surfaces of the outer layer circuit substrate 50 and the wiring patterns provided on both surfaces of the inner layer circuit substrate 10 in three layers.

As described above, in the multilayer flexible printed wiring board 90, the interlayer conductive circuit is constituted by a hole-filling structure. Thereby, as shown in FIG. 2B (6), the terminal 92 can be provided directly above the filling through hole 71 or the filling holes 72 to 75. Therefore, the degree of freedom in the arrangement of the terminals is increased, and electronic components such as a narrow-distance CSP or the like can be mounted in parallel to the multilayer flexible printed wiring board 90.

As described above, according to the present invention, a multilayer printed wiring board capable of mounting an electronic component such as a narrow-distance CSP or the like can be obtained with a high degree of integration.

Further, the multilayer flexible printed wiring board 90 may be provided with a replaceable cable portion having a high degree of freedom in pulling out. The flexible cable portion is formed to extend from a component mounting portion in which the outer layer circuit substrates 40 and 50 are laminated.

In the above description of the embodiment, the outer layer circuit substrates 40 and 50 are formed using the double-sided copper clad laminates 34 and 44. However, the present invention is not limited thereto, and a single-sided copper clad laminate may be used. Fig. 6(A) is a cross-sectional view showing the multilayer printed wiring board 90A laminated on the core substrate 20 by the outer layer circuit substrates 40A and 50A produced by using the single-sided copper clad laminate.

As shown in Fig. 6(A), the outer layer base materials 40A and 50A are outer layer wiring patterns formed by processing a copper foil of a single-sided copper-clad laminate, and the outer layer wiring pattern is positioned on the outer side to make the outer layer The circuit substrates 40A and 50A are laminated on the surface and the inside of the core substrate 20 via the adhesive layer 51A.

Further, in the above description of the embodiment, the core substrate 20 is formed by laminating the cover layer 13 on the inner layer circuit substrate 10, and then the outer layer circuit substrate is laminated on the core substrate 20. However, the present invention is not limited thereto. It is also possible to directly laminate the outer layer circuit substrate on the inner layer substrate 10. Fig. 6(B) is a cross-sectional view showing the multilayer printed wiring board 90B in which the outer layer circuit substrates 40B and 50B produced by the single-sided copper clad laminate are laminated on the inner layer circuit substrate 10.

As shown in Fig. 6(B), the outer layer base materials 40B and 50B are outer layer wiring patterns formed by processing a copper foil of a single-sided copper-clad laminate, and the outer layer wiring pattern is positioned on the outer side to make the outer layer The circuit substrates 40B and 50B are laminated on the surface and the inside of the inner layer circuit substrate 10 via the adhesive layer 51B. As can be seen from Fig. 6(B), in order to insulate and protect the inner layer wiring pattern of the inner layer circuit substrate 10, the outer layer circuit substrates 40B and 50B may be laminated on the flexible cable portion.

Further, there are two major methods for laminating the outer layer circuit substrates 40B and 50B on the inner layer circuit substrate 10.

In the first method, the adhesive layer 51B is formed by filling the inner wiring patterns 8A and 8B of the inner layer circuit substrate 10 and the plated through holes 7, and the outer layer circuit substrate 40B is laminated on the adhesive layer 51B. 50B method.

The second method is a method of using a single-sided copper-clad laminate having an adhesive layer having an adhesive layer on a side where no copper foil is formed. In this method, the copper foil of the single-sided copper-clad laminate is processed to form the outer-layer circuit substrates 40B and 50B, and the outer-layer circuit substrates 40B and 50B are laminated on the inner-layer circuit substrate 10. Further, after the adhesive layer single-sided copper-clad laminate is laminated on the inner layer substrate 10, the copper foil on the surface may be processed to form an outer wiring pattern.

Further, on the one side of the core substrate 20 (or the inner layer circuit substrate 10), the outer layer circuit substrate which has been formed may be laminated from the double-sided copper-clad laminate, and the other surface may be self-contained. The copper clad laminate begins to laminate the finished outer circuit substrate.

The multilayer printed wiring board and the method of manufacturing the same according to the present invention will be described above.

In the above description, the method of providing a wiring pattern and an opening by patterning a conductive film such as a copper foil is not limited thereto, and a semi-additive method (Semi) may be used. -additive process) and other methods.

Further, the opening portion functioning as a positive projection mask may be formed after the outer layer circuit substrate is laminated on the core substrate. In addition, as a laser processing method, it is also possible to use a method of directly projecting a reticle, or to directly irradiate the conductive film with laser light, and to remove the conductive film and the direct laser processing of the insulating layer below it. law.

Further, in the pinholes 66 and 67, the shape of the cross section is not limited to the star shape shown in Fig. 3. In the hole-fill plating process, a structure (concavity or the like) for degrading the fluidity of the plating solution may be provided. Further, not only the lower hole of the pinhole 67 but also the concave portion may be provided on the side wall of the upper hole.

Further, in the above-described embodiment, the multilayer flexible printed wiring board is described. However, the present invention is not limited thereto, and a Rigid-Flex printed wiring board or a multi-layer rigid printed (Rigid-Printed) wiring board is not limited thereto. Other multilayer printed wiring boards are also applicable to the present invention.

Moreover, the wiring pattern or the plating metal is not limited to copper. In other words, in the description of the above embodiment, the metal constituting the wiring pattern and the plating metal filled in the pinhole or the like are copper. However, the present invention is not limited thereto, and for example, other metals such as aluminum or silver may be used.

Further, the multilayer flexible printed wiring board according to the above embodiment is a wiring pattern having six layers, but is not limited thereto. The present invention can also be applied to a multilayer printed wiring board in which an outer layer circuit substrate is further laminated on the multilayer circuit substrates 40, 50.

According to the above description, the additional effects and various modifications of the present invention may be considered as long as the manufacturer is concerned, but the form of the present invention is not limited to the above embodiment. Various additions, modifications, and partial additions and deletions may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

1. . . Insulating base film

2, 3. . . Copper foil

4. . . Double-sided copper laminate

5. . . Inner through hole

6. . . Coating

7. . . Plated through hole

8A, 8B. . . Inner wiring pattern

10. . . Inner circuit substrate

11. . . Subsequent layer

12. . . Insulating film

13. . . Cover cover

20. . . Core substrate

31, 41. . . Insulating base film

32, 33, 42, 43. . . Copper foil

34, 44. . . Double-sided copper laminate

35, 36, 37, 38, 45, 46, 47, 48. . . Opening

39, 49. . . Outer wiring pattern

40, 40A, 40B, 50, 50A, 50B. . . Outer circuit substrate

51, 51A, 51B. . . Subsequent layer

60. . . Multilayer circuit substrate

61. . . Through hole

62, 63, 64, 65. . . Blind hole

66, 67. . . Pinhole

68. . . Plating metal

69. . . Concave

70. . . Multilayer circuit substrate

71. . . Filling through hole

72, 73, 74, 75. . . Fill hole

80A, 80B. . . Outer wiring pattern

90, 90A, 90B. . . Multilayer printed wiring board

91. . . Solder resist

91a. . . Opening

92. . . Terminal

100. . . Inner circuit substrate

110. . . Cover layer

120. . . Subsequent layer

130. . . Insulating film

200. . . Core substrate

210. . . Laminated adhesive layer

300. . . Outer circuit substrate

310. . . Opening

400. . . Multilayer circuit substrate

410, 420. . . Blind hole

430. . . Through hole

450. . . Coating

460, 470, 480. . . Plating blind hole

490. . . Plated through hole

500. . . Outer circuit wiring pattern

510. . . Solder resist

510a. . . Opening

520. . . Terminal

600. . . Multilayer printed wiring board

C. . . Corner

D. . . Central area

Fig. 1A is a cross-sectional view showing a process of a method of manufacturing a multilayer flexible printed wiring board according to an embodiment of the present invention.

Fig. 1B is a cross-sectional view showing a process of a method of manufacturing a multilayer flexible printed wiring board according to an embodiment of the present invention.

Fig. 2A is a cross-sectional view showing a process of manufacturing a multilayer flexible printed wiring board according to an embodiment of the present invention.

Fig. 2B is a cross-sectional view showing a process of manufacturing a multilayer flexible printed wiring board according to an embodiment of the present invention, taken along line 2A.

Fig. 3 is a cross-sectional view showing a portion A of Fig. 2A (3), and a plan view of the through hole.

Fig. 4A is a cross-sectional view showing a state in which a plating metal is filled in a through hole.

Fig. 4B is a cross-sectional view showing the form in which the plating metal is filled in the through hole, continued from Fig. 4A.

Fig. 5A is a process sectional view showing a method of manufacturing a multilayer flexible printed wiring board according to a comparative example.

Fig. 5B is a cross-sectional view showing a process of manufacturing a multilayer flexible printed wiring board according to a comparative example, taken along line 5A.

Fig. 6(A) is a cross-sectional view showing a multilayer flexible printed wiring board in which a completed outer layer circuit substrate is laminated on a core substrate from a single-sided copper clad laminate, and (B) is a single-sided copper clad layer. The laminated board starts a cross-sectional view of a multilayer flexible printed wiring board in which an outer layer circuit substrate which has been formed is laminated on an inner layer circuit substrate.

10. . . Inner circuit substrate

40, 50. . . Outer circuit substrate

68. . . Plating metal

70. . . Multilayer circuit substrate

71. . . Filling through hole

72, 73, 74, 75. . . Fill hole

80A, 80B. . . Outer wiring pattern

90. . . Multilayer printed wiring board

91. . . Solder resist

91a. . . Opening

92. . . Terminal

Claims (10)

A multilayer printed wiring board comprising: an inner layer circuit substrate; a first outer circuit substrate on which an insulating layer is laminated on a surface of the inner circuit substrate; the dielectric layer is laminated a second outer layer circuit substrate on the inner surface of the inner layer circuit substrate; and a through hole for the first outer layer circuit substrate, the front inner layer circuit substrate, and the second outer layer circuit substrate a through hole; a front through hole configured to communicate with a first pinhole penetrating through the first outer layer circuit substrate, an inner layer through hole penetrating the inner layer circuit substrate, and a second through hole of the second outer layer circuit substrate The pinholes, the first and second pinholes, have a minimum opening diameter larger than the maximum opening diameter of the inner layer through hole, and the filled through holes are formed by filling plating treatment of the through holes through the filling plating metal. The multilayer printed wiring board according to the first aspect of the invention, wherein the first pinhole and/or the second pinhole have a concavity and convexity on a side wall thereof. The multilayer printed wiring board according to the first aspect of the invention, wherein the cross section of the first pinhole and/or the second pinhole is a plurality of protrusions facing inward. The multilayer printed wiring board according to the first aspect of the invention, wherein the first outer layer circuit substrate and/or the second outer layer circuit substrate have a blind hole before the penetration, and further include a filling hole filled with the plating metal. The multilayer printed wiring board according to claim 1, further comprising zero from the first and second outer layer circuit substrates on which the first layer and the second outer layer are laminated The flexible cable portion where the mounting portion begins to extend. The multilayer printed wiring board according to claim 1, wherein the inner layer circuit substrate has a flexible first insulating base film and a first surface respectively disposed on both sides of the first insulating base film And a second inner layer wiring pattern; the first outer layer circuit substrate has: a flexible second insulating base film; and first and second outer layer wiring patterns respectively disposed on the surface and the inside of the second insulating base film The second outer layer circuit substrate has: a flexible third insulating base film; and third and fourth outer wiring patterns respectively disposed on the surface and the inner surface of the third insulating base film; the pre-filled through-hole is electric The first and second inner layer wiring patterns and the first to fourth outer layer wiring patterns are described before the sexual connection. A method for producing a multilayer printed wiring board, characterized in that a double-sided metal-clad laminate having a flexible insulating base film and a metal foil formed on both surfaces of the insulating base film is prepared, and is formed in a thickness direction. The inner layer through hole of the double-sided metal-clad laminate is patterned by patterning the metal foil of the double-sided metal-clad laminate to form an inner layer wiring pattern, thereby preparing an inner layer circuit substrate, and preparing to have: flexible insulation The base film and the first and second metal-clad laminates of the metal foil formed on at least one of the insulating base films, and the metal foil of the first metal-clad laminate is patterned to form the first outer wiring a pattern, whereby a first outer layer circuit substrate is formed, and a metal foil of a second metal-clad laminate is patterned to form a second outer wiring pattern, thereby fabricating a second outer circuit substrate, wherein the inner circuit substrate is The surface of the material will be preceded by the first outer circuit substrate, in which the first outer wiring pattern is placed on the outer side, and the insulating layer is laminated to form the inner layer of the inner circuit substrate. A multilayer circuit substrate is formed by laminating an insulating layer and interposing a second outer layer circuit substrate, which is previously described as a second outer layer wiring pattern, by a predetermined multilayer substrate substrate. The field performs a laser processing process for irradiating the laser light, and passes through the first outer layer circuit substrate as a first pinhole that communicates with a minimum opening diameter larger than the maximum opening diameter of the inscribed inner layer through hole, and The layer via hole and the second outer layer circuit substrate have a second pinhole having a minimum opening diameter larger than a maximum opening diameter of the inner layer through hole, and a through hole penetrating the multilayer circuit substrate is formed. A filling plating process for filling the via holes with the plating metal is performed to form a filled via hole electrically connected to the inner layer wiring pattern, the first outer wiring pattern, and the second outer wiring pattern. The method for manufacturing a multilayer printed wiring board according to claim 7, wherein before the laser processing process, the first metal-clad laminate and/or the metal of the second metal-clad laminate are pre-recorded. The foil is formed with a through hole forming opening portion having a plurality of protrusions facing the inner side; and in the laser processing process of the foregoing, a positive projection mask processing for irradiating the laser beam to the opening portion for forming the through hole is performed to form a horizontal The cross section is the first first pinhole having the same shape as the opening for forming the through hole. The method of manufacturing a multilayer printed wiring board according to the seventh aspect of the invention, wherein the front inner layer through hole is formed, and the front inner layer through hole is formed before the front inner layer wiring pattern is formed. The double-sided metal-clad laminate is subjected to a plating treatment, thereby forming a plated through hole of the metal foil provided on both sides of the first double-sided metal-clad laminate. Multilayer printed wiring board as described in claim 7 In the manufacturing method, the first metal-clad laminate and/or the second metal-clad laminate are formed with a blind hole forming opening; and the laser beam is irradiated onto the front blind hole forming opening to form a orthographic projection mask. Form a blind hole; in the pre-fill hole plating process, the metal is plated before the blind hole is filled to form a hole.