JP2013258345A - Compound multilayer wiring board and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To combine a multilayer substrate having conventional plating vias with a multilayer substrate having paste vias to form a compound multilayer wiring board, thereby utilizing the advantages of both multilayer substrates.SOLUTION: In a compound multilayer wiring board 260, two intermediate wiring board parts 180, which respectively include first vias 130 formed by paste vias and second vias 170 formed by plating vias, are connected by a connection layer 220 having connection vias 210 formed by paste vias, and an outmost layer insulation layer 230 includes outmost layer vias 250 formed by plating vias. In the compound multilayer wiring board 260, the connection layer 220 and the outmost layer insulation layer 230 concurrently bury and thermal-harden the connection layer 220 side second vias 170 and the outmost layer insulation layer 230 side second vias 170, respectively.

Description

  The present invention relates to a multilayer wiring board used for manufacturing a mobile phone or the like, and relates to a composite multilayer wiring board formed by combining a plating via and a paste via and a manufacturing method thereof.

  In recent years, with the miniaturization and high performance of electronic devices, multilayer boards having what is manufactured using plating technology to manufacture vias for interlayer connection (hereinafter simply referred to as plating vias) are known. ing.

  On the other hand, problems such as lead time and plating waste liquid may occur in a multilayer substrate having plating vias. In order to deal with such a problem of plating vias, a multilayer substrate having a substrate manufactured by using a paste technique for manufacturing a via serving as an interlayer connection (hereinafter simply referred to as a paste via) is known.

  From such a background, it has been required to make use of both advantages by combining a multilayer substrate having a conventional plating via and a multilayer substrate having a paste via to form a composite multilayer wiring substrate.

  FIG. 14 is a cross-sectional view showing an example of a conventional composite multilayer wiring board. A conventional composite multilayer wiring substrate 10 shown in FIG. 14 is an example of a multilayer substrate in which a plating via 16 and a paste via 13 are combined.

  In FIG. 14, the first insulating layer 11 is formed with a through-hole (no number is assigned), and the through-hole is filled with a conductive paste (no number is assigned), and a plurality of copper foil patterns A paste via 13 is formed to connect the two. And in the case of further multilayering, a new first insulating layer 11, copper foil pattern 12, and paste via 13 on the first insulating layer 11 and copper foil pattern 12, as indicated by arrows 17a, 17b, etc. By stacking sequentially from the center (for example, the portion indicated by the arrow 17a) to both sides (for example, by further stacking based on the portion indicated by the arrow 17a, the portion indicated by the arrow 17b), it becomes possible to increase the number of layers. . Arrows 17a, 17b, 17c, and 17d in FIG. 14 indicate a state in which these members are multilayered by sequentially stacking them.

  As shown in FIG. 14, by providing the plated wiring 15 and the plated via 16 in the second insulating layer 14 which is the outermost layer, it is possible to obtain a composite multilayer wiring board in which the wiring is further miniaturized. However, as indicated by the arrows 17a to 17d, there is a possibility that the lamination process becomes longer and complicated as the number of layers increases.

  FIG. 15 is a cross-sectional view showing an example of a multilayer substrate previously proposed by the inventors (Patent Document 1). In FIG. 15, a multilayer substrate 21 has a plurality of copper foil patterns 12 connected to holes 19 formed in the first insulating layer 11 via paste vias 13 filled with a conductive paste 20. And this multilayer substrate 21 is laminated | stacked collectively through the adhesive sheet 23 (The adhesive sheet 23 contains the prepreg 18 and the electrically conductive paste 20 with which the hole 19 was filled), and is integrated, The conventional composite multilayer wiring board 10 Form.

  Here, it is useful to use the prepreg 18 as the adhesive sheet 23. It is also useful to provide the copper foil 22 via the prepreg 18 in the outermost layer. Further, after such lamination (or batch lamination), it is also useful to provide the plating wiring 15 and the plating via 16 in the outermost layer as shown in FIG. 14 and the like (in FIG. 15, the plating wiring 15 and the plating via). Via 16 is not shown).

  Further, in the case of the multilayer substrate as shown in FIG. 15, there are cases where the connection stability in the connection sheet portion varies depending on the lamination conditions and the like.

International Publication No. 2011/155162

  However, when multi-layer substrates having paste vias are laminated via the adhesive sheet 23, depending on the lamination conditions, connection stability using the conductive paste in the connection sheet portion may vary. .

  The present invention solves the problem related to connection stability when the above-described conductive paste is used, and combines an excellent portion of a conventional plating via and an excellent portion of a paste via as a composite multilayer wiring board. Thus, an object of the present invention is to provide a composite multilayer wiring board with higher connection reliability and a method for manufacturing the same.

  In order to achieve the above object, a composite multilayer wiring board of the present invention comprises a first via made of a paste via (or first paste via) and a plating via (or first plating via) formed on both surfaces. A plurality of intermediate wiring board portions having second vias, a connection layer having connection vias made of paste vias (or second paste vias) for connecting the intermediate wiring board portions, and the intermediate wiring board portions An outermost layer insulating layer and an outermost layer via made of a plating via (or a second plating via) on the outermost layer side, and the connection layer includes the second via on the connection layer side of the intermediate wiring board part, The outermost insulating layer is a composite multilayer wiring board obtained by embedding and thermosetting the second vias on the outermost insulating layer side of the intermediate laminated substrate.

  In order to achieve the above object, another example of the composite multilayer wiring board of the present invention is an electrical connection between the first insulating layer, the first wiring formed on both surfaces of the first insulating layer, and the first wiring. A plurality of intermediate wirings having a double-sided board portion having first vias to be connected, a second insulating layer filling the first wiring, a second wiring formed in the second insulating layer, and a second via A connection layer having a substrate portion, a connection layer having a thermosetting resin portion for bonding between the intermediate wiring substrate portions and a core material, and a connection via penetrating the connection layer; The outermost layer of the substrate portion is a composite multilayer wiring board having an outermost layer insulating layer, an outermost layer wiring formed in the outermost layer insulating layer, and an outermost layer via, wherein the first wiring is made of copper foil wiring, Both the first via and the connection via are paste vias, the second wiring and the outermost layer wiring. Both are composed of plated wiring, the second via and the outermost layer via are both plated vias, and the connection layer is embedded in the second wiring on the connection layer side, and the two second insulating layers Is a composite multilayer wiring board in which the second wiring on the side different from the connection layer side is buried and both are thermally cured at the same time.

  In order to achieve the above object, a method for manufacturing a composite multilayer wiring board of the present invention includes a plurality of sheets having a first via made of a first paste via and a second via made of a plating via formed on both surfaces. An intermediate wiring board part, a connection layer having a connection via made of a second paste via for connecting the intermediate wiring board part, and an outermost insulating layer and a plating via on the outermost layer side of the intermediate wiring board part A method for manufacturing a composite multilayer wiring board having an outermost layer via, comprising: a preparation step for preparing the intermediate wiring board part; and a connection in an uncured state having a conductive paste between the plurality of intermediate wiring board parts An installation step of installing an uncured outermost layer resin portion on the outermost layer side of the intermediate wiring board portion, and the connection layer in the uncured state with the second via on the connection layer side. The uncured outermost resin layer is the front A method for manufacturing a composite multilayer wiring board, comprising: an embedding process for embedding the second vias on the uncured outermost layer resin part side simultaneously; and an embedding thermosetting process for thermosetting simultaneously in the embedded state. It is.

  As described above, according to the present invention, the problems specific to paste vias are solved. By combining a superior portion of conventional plating vias and an excellent portion of paste vias as a composite multilayer wiring board, Therefore, it is possible to provide a composite multilayer wiring board with higher connection reliability and a method for manufacturing the same.

Sectional drawing which shows an example of the composite multilayer wiring board of this invention (A)-(D) are sectional drawings which show an example of the manufacturing method of an intermediate wiring board part using manufacture of a composite multilayer wiring board (A)-(D) are sectional drawings which show an example of the manufacturing method of an intermediate | middle wiring board part. Sectional drawing explaining a mode that it laminates as a connection layer the prepreg which provided the protrusion part which consists of electrically conductive paste between two intermediate | middle wiring board parts. Sectional view showing an example of pressurization and heating process Sectional drawing explaining how to embed each member flat and connect with connection vias Sectional drawing explaining how outermost layer wiring and outermost layer vias are formed in the outermost insulating layer using plating technology Sectional drawing which expands partially explaining a mode that 2nd wiring and the 2nd via are embed | buried in an uncured adhesive resin part Cross-sectional view showing a partially enlarged view of the outermost layer wiring and outermost layer via embedded in the uncured outermost layer resin part, and thermosetting and integrating in the embedded state Sectional drawing explaining the problem which may generate | occur | produce when using the intermediate | middle wiring board part which has the part which several plating vias arranged in series in the thickness direction Sectional drawing explaining the problem which may generate | occur | produce when using the intermediate | middle wiring board part which has the part which several paste vias arranged in series in the thickness direction Sectional drawing explaining an example of the mechanism in which the connection stability between the intermediate wiring board part and the conductive paste is increased in the invention Sectional drawing explaining an example of the mechanism in which the connection stability between the intermediate wiring board part and the conductive paste is increased in the invention Sectional view showing an example of a conventional composite multilayer wiring board Sectional drawing which shows an example of the multilayer substrate which the inventors proposed in the past

(Embodiment 1)
An embodiment of the present invention will be described with reference to FIG.

  FIG. 1 is a cross-sectional view showing an example of a composite multilayer wiring board of the present invention. In FIG. 1, 110 is a first insulating layer, 120 is a first wiring, and 130 is a first via. It is useful that the first wiring 120 is formed from a copper foil wiring and the first via 130 is formed from a paste via. Reference numeral 140 denotes a double-sided board unit. The double-sided board unit 140 includes at least a first insulating layer 110, a first wiring 120, and a first via 130 formed in a through hole formed in the first insulating layer 110. Have. Reference numeral 150 denotes a second insulating layer, which embeds the first wiring 120 formed on both surfaces of the double-sided substrate portion 140.

  Reference numeral 160 denotes a second wiring, and the second wiring 160 is formed on the surface of the second insulating layer 150, that is, on the side different from the double-sided substrate part 140 side of the second insulating layer 150. Reference numeral 170 denotes a second via, and the second via 170 is also formed in a bottomed hole (not numbered) formed in the second insulating layer 150 and has a bride via structure. Note that the difference between the second wiring 160 and the second via 170 is the presence or absence of a via portion formed in the second insulating layer 150. A bottom hole is provided on the second insulating layer 150 side of the second wiring 160, and a part of the second wiring 160 is filled in the bottomed via, and the second via 170 has a bride via structure. The second via 170 may be only a land. The second via 170 does not need to have a wiring pattern or the like that connects the land pattern to the land pattern.

  Reference numeral 180 denotes an intermediate wiring board unit. The intermediate wiring board unit 180 includes a double-sided board unit 140, a second insulating layer 150, a second wiring 160, and a second via 170 formed on both sides of the double-sided board unit 140. Have.

  Reference numeral 190 denotes a thermosetting resin portion, 200 denotes a core material, and 210 denotes a connection via. It is useful that the connection via 210 is formed of a paste via. Reference numeral 220 denotes a connection layer, and the connection layer 220 has at least a core material 200, a cured thermosetting resin portion 190, and a connection via 210 made of via paste (or a cured product of via paste).

  Reference numeral 230 denotes an outermost insulating layer, and an outermost layer wiring 240 and an outermost layer via 250 are further provided on the outermost layer side of the outermost insulating layer 230. The difference between the outermost layer wiring 240 and the outermost layer via 250 is the presence or absence of a bottomed hole (not numbered) formed in the outermost insulating layer 230.

  Reference numeral 260 denotes a composite multilayer wiring board according to the present invention. As shown in FIG. 1, the composite multilayer wiring board 260 electrically connects the first insulating layer 110, the first wiring 120 formed on both surfaces of the first insulating layer 110, and the first wiring 120. A double-sided board portion 140 having a first via 130 made of paste via, a second insulating layer 150 in which the first wiring 120 is embedded, and a second formed by plating formed in the second insulating layer 150. A wiring 160 and a second via 170 are provided.

  As shown in FIG. 1, the composite multilayer wiring board 260 includes a connection layer 220 having a plurality of intermediate wiring board parts 180, a thermosetting resin part 190 that bonds the intermediate wiring board parts 180, and a core material 200, A connection layer 220 having a connection via 210 penetrating through the connection layer 220.

  As shown in FIG. 1, the composite multilayer wiring board 260 includes an outermost layer insulating layer 230 on the outermost layer side of the intermediate wiring board portion 180, an outermost layer wiring 240 formed on the outermost layer insulating layer 230, and an outermost layer via. 250.

  As shown in FIG. 1, in the composite multilayer wiring board 260, the first wiring 120 is formed from a copper foil wiring (not assigned a number) obtained by patterning a predetermined copper foil. Such copper foil wiring (for example, the first wiring 120) has a smaller thickness variation than the plating wiring (for example, the second wiring 160). This is because a copper foil having a uniform thickness (for example, the first wiring 120) manufactured in a long length is etched to form a wiring. On the other hand, the plating wiring (for example, the second wiring 160) has a larger thickness variation than the copper foil wiring (for example, the first wiring 120). This is because the plating solution, the plating conditions, the pattern density, and the pattern width are increased. This is because it is easily affected by the above.

  In FIG. 1, both the first via 130 and the connection via 210 are conductive pastes having conductive powder such as copper powder (and Sn-Bi solder powder) filled in the through holes and resin such as thermosetting resin. It is composed of paste vias. Such a paste via is formed by pressurization and heating, and has excellent connection reliability against reheating and pressurization.

  Further, both the second wiring 160 and the outermost layer wiring 240 are formed of a plated wiring created by using a plating technique. The second via 170 and the outermost via 250 are both formed from plating vias, and the connection layer 220 embeds the first wiring 120 on the connection layer 220 side. The two second insulating layers 150 embed the first wiring 120 on the side different from the connection layer 220 side. The connection layer 220 and the two second insulating layers 150 (laminated on at least both surfaces of the connection layer 220) are in a semi-cured state (or uncured state) and have a predetermined thickness (or a high thickness). The second wiring 160 is thermally cured at the same time in a state where the second wiring 160 is buried so that the unevenness does not appear on the surface. As a result, the flatness of the component mounting surface such as a semiconductor of the composite multilayer wiring board 260 of the present invention can be improved, and the component mounting surface can be made into a fine pattern.

  The high wall thickness means that the wiring thickness is 0.5 times or more, further 0.7 times or more, further 1.0 times or more, and further 1.2 times or more the wiring width of the narrowest part. To do.

  The outermost layer wiring 240 and the outermost layer via 250 are thermally cured together with the connection layer 220. On the surface of the outermost insulating layer 230, the second wiring 160, the second via 170, and the like are formed in a state in which the occurrence of unevenness due to the wiring thickness or the like is suppressed. Thus, the outermost insulating layer 230 has high smoothness. Therefore, it is useful to form a bottomed hole on the surface of the outermost insulating layer 230 with increased smoothness again with a laser or the like and form the outermost layer wiring 240 and the outermost layer via 250 by using a plating technique. . Needless to say, by increasing the smoothness of the surface of the outermost insulating layer 230, the component mountability can be improved.

  Further, a plurality of intermediate wiring board portions 180 having a first via 130 made of via paste (or first paste via) and a second via 170 made of plating vias (or first plating vias) formed on both surfaces. A connection layer 220 having connection vias 210 made of paste vias (or second paste vias) that connect between the intermediate wiring board portions 180, and an outermost layer provided on the outermost layer side of the intermediate wiring board portions 180 It is useful to have the insulating layer 230 and the outermost layer via 250 composed of a plating via (or a second plating via). Further, the connection layer 220 embeds the second via 170 on the connection layer 220 side of the intermediate wiring board 180, and the outermost insulating layer 230 embeds the second via 170 on the outermost insulating layer 230 side of the intermediate wiring board 180, respectively. The composite multilayer wiring board 260 is formed by thermosetting. The process of embedding and thermosetting these members by the connection layer 220 and the outermost insulating layer 230 is performed in one process or the same process (that is, in a state where it is set in a mold used for heating or in a pressurized state). It is desirable to carry out without removing or removing from the mold or the like. By doing so, the outermost insulating layer 230 and the intermediate wiring board portion 180 function as a cushion layer or a planarization layer (or an uneven absorption layer, an uneven relief layer, etc.) by embedding unevenness, respectively.

  The first via paste and the second via paste may be paste vias using the same conductive paste, or may be paste vias using different conductive pastes. The first plating via and the second plating via may be the same.

  As described above, since the intermediate wiring board portion 180 has both the first via 130 made of paste via and the second via 170 made of plating via, even when stacked through the connection layer 220, Since a sufficient lamination pressure is transmitted to the connection via 210 formed in the connection layer 220, the connection reliability can be improved.

  Further, in the composite multilayer wiring board 260 formed by pressurizing and heating the intermediate wiring board parts 180 through the connection layer 220, the second wiring 160 provided so as to protrude from both surfaces of the intermediate wiring board part 180, The shape and the like of the second via 170 (for example, thickness, remaining copper ratio, coarse density, etc.) can be absorbed by embedding in the outermost insulating layer 230 and the connection layer 220 provided above and below, and the composite multilayer wiring having excellent flatness The substrate 260 is realized.

  Further, it is possible to increase the thickness (or increase the thickness) of the second wiring 160 and the like formed on both surfaces of the intermediate wiring board portion 180, but this means that the intermediate wiring board portion 180 having the second wiring 160 and the like. This is because the outermost insulating layer 230 and the connection layer 220 to be the uneven absorption layer (or cushion layer) are provided on both surfaces of the first and second layers, and the second wiring 160 and the like are embedded by the outermost insulating layer 230 and the connecting layer 220.

  A particularly stable via connection can be realized while suppressing the occurrence of unevenness due to the second wiring 160 on the surface of the composite multilayer wiring board 260.

  Further, since the intermediate wiring board portion 180 has both the first via 130 made of paste via and the second via 170 made of plating via, the via is formed on the intermediate wiring board portion 180 so as to overlap the straight line. Even when the serial vias formed as described above are formed, the connection stability by the connection via 210 made of the paste via filled in the hole formed in the connection layer 220 can be improved. This will be described with reference to FIGS. This is considered to be due to the pressure mechanism unique to the present invention.

(Embodiment 2)
In the second embodiment, an example of a method for manufacturing the composite multilayer wiring board 260 described in the first embodiment will be described with reference to FIGS.

  2A to 2D are cross-sectional views illustrating an example of a method for manufacturing an intermediate wiring board portion using manufacturing of a composite multilayer wiring board. 270 is a prepreg, 280 is a protective film, 290 is a through hole, 300 is a conductive paste, 310 is a squeegee, 320 is an arrow, 330 is a protrusion, and 340 is a copper foil.

  As shown in FIG. 2A, protective films 280 are provided on both sides of the prepreg 270. It is useful to use a commercially available prepreg 270 as the prepreg 270. As the commercially available prepreg 270, for example, a glass woven fabric or glass nonwoven fabric is used as the core material 200, and the core material 200 is impregnated with an uncured epoxy resin or the like, or a heat resistant film such as polyimide is used as the core material 200. It is useful to use an uncured epoxy resin or the like provided as the thermosetting resin portion 190 on one or both surfaces of the core material 200.

  Next, as shown in FIG. 2B, a through hole 290 is formed so as to penetrate the prepreg 270 and the protective film 280. As a method for forming the through hole 290, a laser, a drill, a punch, or the like may be used.

  Next, as shown in FIG. 2C, the squeegee 310 and the like are moved in the direction of the arrow 320 to fill the through-hole 290 with the conductive paste 300.

  Thereafter, the protective film 280 is removed, so that a part of the conductive paste 300 protrudes from the surface of the prepreg 270 as the protruding portion 330.

  Next, as shown in FIG. 2D, a copper foil 340 (for example, a commercially available copper foil having a thickness of 18 μm) is set on both surfaces of the prepreg 270 having the projecting portion 330, and as shown by an arrow 320, These members are heated under pressure using a mold (both not shown). It is useful to optimize the thickness of the copper foil depending on the application, and a copper foil having a high thickness of 20 μm or more may be used.

  FIGS. 3A to 3D are cross-sectional views illustrating an example of a method for manufacturing the intermediate wiring board 180, which is a process following FIGS. 2A to 2D.

  3A, the first insulating layer 110 is obtained by thermosetting the prepreg 270 shown in the step of FIG. 2D. Further, the first via 130 is a paste via (not assigned a number) formed by compressing and thermosetting the conductive paste 300 having the protruding portion 330 in the through hole 290 formed in the prepreg 270. Next, the surface layer copper foil 340 is patterned into a predetermined pattern to form a first wiring 120 made of a copper foil wiring, which has the shape shown in FIG.

  FIG. 3B is a cross-sectional view illustrating an example of the double-sided board portion 140. The double-sided substrate part 140 includes a first insulating layer 110, a first via 130 made of a paste via, and a first wiring 120 formed on both surfaces of the first insulating layer 110.

  FIG. 3C is a cross-sectional view showing a state in which the second wiring 160 and the like are further formed on the double-sided substrate portion 140 via the second insulating layer 150.

  As shown in FIG. 3C, the second insulating layer 150 is formed so as to bury the first wiring 120. In addition, it is useful to provide a copper foil 340 on the surface of the second insulating layer 150 as necessary during the formation. Here, it is easy to embed a thick copper foil by using the second insulating layer 150 having a sufficient resin amount and a resin flow. Here, JIS K7210 or the like may be referred to for the resin flow of various members used in the present invention.

  Next, as shown in FIG. 3D, a bottomed hole (not numbered) is provided in the second insulating layer 150 using a laser or the like, and the second wiring 160 and the second via are formed using a plating technique. 170 is provided. In addition, when providing the 2nd wiring 160 and the 2nd via | veer 170 using a plating technique, as shown in FIG.3 (C), using the copper foil 340 provided in the surface of the 2nd insulating layer 150 is utilized. Is useful.

  Next, a state in which a plurality of intermediate wiring board portions are stacked together will be described with reference to FIGS.

  FIG. 4 is a cross-sectional view illustrating a state in which a prepreg provided with a protruding portion made of a conductive paste is laminated as a connection layer between two intermediate wiring board portions.

  As shown in FIG. 4, a prepreg 270 provided with a protruding portion 330 made of a conductive paste 300 is set between two intermediate wiring board portions 180, and as shown by an arrow 320, a pressing device, a mold, etc. (Both not shown) are pressed, heated and integrated.

  In FIG. 4, 350 is an uncured outermost layer resin portion, and 360 is an uncured adhesive resin portion. As shown in FIG. 4, it is useful to set, for example, a sheet-like uncured outermost layer resin portion 350 and a copper foil 340 on the outermost layer side of the intermediate wiring board portion 180. By doing so, even the thick second wiring 160 and second via 170 can be embedded without unevenness.

  Further, as shown in FIG. 4, the prepreg 270 provided with the projecting portion 330 made of the conductive paste 300 between the two intermediate wiring board portions 180 has an uncured adhesive resin portion 360, so The second wiring 160 and the second via 170 can be buried without unevenness.

  FIG. 5 is a cross-sectional view showing an example of a pressurizing and heating process. As indicated by an arrow 320 in FIG. 5, the second wiring 160 formed on the prepreg 270 side of the intermediate wiring board portion 180 is applied to the uncured adhesive resin portion 360 constituting the prepreg 270 by applying pressure and heating. It is buried without unevenness.

  Simultaneously with this embedding, the conductive paste 300 filled in the through hole 290 formed in the connection layer 220 is pressed and compressed by the second wiring 160 and the second via 170 protruding from the surface of the intermediate wiring board portion 180. . The conductive paste 300 is more strongly compressed by the thickness of the second wiring 160 and the second via 170 in addition to the protruding amount of the protruding portion 330. This compression process reduces the conductivity of the conductive paste 300 (or paste via). Furthermore, the effect of reducing the contact resistance at the interface between the conductive paste 300 (or paste via) and the second wiring 160 or the second via 170 can be obtained.

  In addition, the second wiring 160 and the second via 170 protruding on the surface different from the prepreg 270 side (that is, the surface on the outermost layer side) of the intermediate wiring substrate portion 180 are embedded in the uncured outermost resin layer 350.

  Thus, the second wiring 160 and the second via 170 provided so as to protrude from both surfaces of the intermediate wiring board portion 180 are simultaneously formed on the prepreg 270 (or the uncured adhesive resin portion 360) and the uncured outermost layer resin portion 350. By embedding (or in a single step), unevenness due to the thickness of the second wiring 160 and the second via 170 is prevented. Further, no unnecessary stress is generated during the embedding.

  Here, as shown in FIG. 5, the uncured outermost layer resin portion 350 set on the outermost layer side of the intermediate wiring board portion 180 is uncured (may be in a semi-cured state). For this reason, even if the thickness of the second wiring 160 or the second via 170 is thick (or even a high thickness of 20 μm or more), it functions as a kind of cushion layer (or a fluidized layer whose thickness is reduced by flow). . As a result, an excellent embedding effect of unevenness or a flattening effect can be obtained. Further, no unnecessary stress is generated during the embedding. Here, it goes without saying that it is preferable to select an uncured outermost layer resin portion 350 having a resin amount and a resin flow sufficient to embed the second wiring 160 and the second via 170.

  FIG. 6 is a cross-sectional view for explaining how these members are embedded flat and connected by connection vias.

  As shown in FIG. 6, the second wiring 160 and the second via 170 provided so as to protrude from both surfaces of the intermediate wiring board portion 180 do not cause unevenness, and the prepreg 270 (or the uncured adhesive resin portion 360). Or embedded in the uncured outermost resin layer 350 at the same time (or in a single step). Then, in the embedded state, it is thermally cured at the same time (or in a single step).

  In FIG. 6, the outermost insulating layer 230 is obtained by thermally curing the second wiring 160 and the second via 170 embedded in the uncured outermost resin layer 350 and embedded. In addition, the connection layer 220 is thermally cured with the second wiring 160 and the second via 170 embedded therein.

  As described above, the outermost insulating layer 230 and the uncured adhesive resin portion 360 are both uncured, embedded in the second wiring 160 and the second via 170, and thermally cured in that state. The stress generated with thermosetting can be kept small. When the outermost insulating layer 230 and the uncured adhesive resin portion 360 are heated from the uncured state and thermally cured, the outermost insulating layer 230 and the uncured adhesive resin portion 360 are softened (and liquefied) to relieve the stress generated by the difference in thermal expansion coefficient. .

  For example, when a multilayer substrate using conventional plating vias (that is, a multilayer substrate having no paste via) is used as the intermediate wiring substrate portion 180 as a comparative example, the pressurization and heating steps shown in FIGS. In this case, the reliability of the connected portion may be affected.

  This is considered as follows. For example, while the plating via is integrated with the wiring portion as the coefficient of thermal expansion of the metal itself, the thermal expansion coefficient may be greatly different from that of an insulating layer (for example, a cured product of glass epoxy resin) covering the plating via or the like. For example, the formation of the plating via is performed at a plating solution temperature (for example, 20 ° C. to 60 ° C.), and is not performed at the curing temperature of the prepreg 270 (for example, 180 ° C. to 200 ° C.). In some cases, stress due to a difference in thermal expansion may occur.

  On the other hand, as shown in FIGS. 2 to 6 of the present invention, an inner layer paste via (for example, the first via 130) and a plating via (for example, the second via 170) on the surface layer are provided as the intermediate wiring board portion 180. In this case, in the pressurization and heating processes shown in FIGS. 4 to 5, the reliability of the connection portion is not easily affected. This is because the paste via (for example, the first via 130) is formed through these pressurizing and heating processes. Furthermore, the difference in coefficient of thermal expansion between the plated via and the paste via also has an effect of suppressing the generation of stress in the heating and pressing processes.

  FIG. 7 is a cross-sectional view for explaining how to prepare the outermost layer wiring 240 and the outermost layer via 250 in the outermost insulating layer 230 by using a plating technique. As shown in FIG. 7, after peeling the outermost copper foil 340, a bottomed hole is formed using a laser or the like. Thereafter, the outermost layer wiring 240 and the outermost layer via 250 are formed by using a plating technique, whereby the composite multilayer wiring substrate 260 as shown in FIG. 1 is obtained.

  In FIG. 7, the state in which the bottomed hole serving as the via via is formed by using a laser or the like after the outermost copper foil 340 has been peeled off has been described. However, it is also useful to form a bottomed hole to be a bride via using a laser or the like while leaving the outermost copper foil 340. For example, a bottomed hole that becomes a via via is formed using a laser or the like while leaving the outermost copper foil 340, and the outermost layer wiring 240 and the outermost layer via 250 are formed using a plating technique. A composite multilayer wiring board 260 as shown in FIG.

  Next, a state where the thick second wiring 160 and the second via 170 are embedded in the uncured adhesive resin portion 360 in the connection layer 220 will be described with reference to FIG.

  FIG. 8 is a cross-sectional view illustrating a partially enlarged manner in which the second wiring 160 and the second via 170 are embedded in the uncured adhesive resin portion 360. FIG. 8 is an enlarged cross-sectional view showing a state in which a plurality of intermediate wiring board portions 180 are integrated via a prepreg 270 having a core member 200. An arrow 320a shown in FIG. 8 indicates a state of pressurization and heating applied to embed the second vias 170a to 170b and the second wirings 160a to 160d formed in an uneven shape on the surface of the intermediate wiring board 180. Show. An arrow 320b indicates an uncured adhesive resin portion 360 in an uncured (or semi-cured) state contained in the prepreg 270 in a gap (or unevenness) between the second vias 170a to 170b and the second wirings 160a to 160d. Shows the state of being filled and buried. As shown in FIG. 8, the connection layer 220 is made of a glass woven fabric, a glass nonwoven fabric, or a heat resistant film such as polyimide, so that even in the pressurization and heating steps as shown in FIG. The two wirings 160 do not contact each other. Moreover, the handling property can be improved by using the member (for example, prepreg 270) using heat resistant films, such as a glass woven fabric, a glass nonwoven fabric, or a polyimide, for the prepreg 270. In addition, the conductive paste 300 is prevented from being crushed and spread during pressure compression.

  Here, the variation in thickness and shape (surface shape or pattern edge shape) of the second vias 170a to 170b and the second wirings 160a to 160d formed by using the plating technique was formed by patterning the copper foil 340. It becomes larger than the wiring (for example, the first wiring 120). This is because when the second vias 170a to 170b and the second wirings 160a to 160d are formed, the flow rate or activity of the plating solution is affected by the plating deposition rate such as the density of the wiring pattern or the presence or absence of vias. . For example, in FIG. 8, the wiring thickness of the second via 170a is thicker than the wiring thickness of the second via 170b. In FIG. 8, the wiring thickness of the second wirings 160a to 160d is 160d> 160a> 160b> 160c.

  Generally, the thickness variation of the plated wiring formed using the plating technique is larger than the thickness variation of the copper foil wiring formed by etching the copper foil 340. Also, the thickness variation of the plating wiring tends to be larger than the thickness variation of the copper foil wiring in both the plating technique + substruct method and the semi-additive method.

  Further, in the case of the plating technique + substruct method, the thickness variation of the wiring may be greatly different at the location in the entire wiring board even if the thickness variation is small between adjacent wirings. For example, when a 60 cm square wiring board is used, the wiring thickness may be different between the peripheral part and the central part of the wiring board.

  On the other hand, when the semi-additive method is used, even if the wiring thickness is substantially the same at the peripheral portion and the central portion of the 60 cm square wiring substrate, there may be a variation in thickness between adjacent wirings.

  The second vias 170a to 170b and the second wirings 160a to 160a formed by plating techniques having different wiring thicknesses (further different wiring widths or wiring patterns, and further positions on the entire wiring board). 160d is embedded in the connection layer 220 as indicated by an arrow 320c. The second vias 170a to 170b and the second wirings 160a to 160d formed by plating techniques having different wiring thicknesses (further different wiring widths or wiring patterns) are connected to the connection layer 220 (or uncured adhesive resin). When embedding in the portion 360), inherent stress is generated in each portion, and these stresses can be relaxed by the first via 130. This is because the first via 130 is made of a paste via, and the first via 130 made of a paste via is formed through a predetermined heating and pressing process. In this case, the paste via becomes a kind of stress relaxation layer because the paste via may have lower strength than the plating via.

  FIG. 9 is a partially enlarged cross-sectional view showing a state in which the outermost layer wiring and the outermost layer via are embedded in the uncured outermost layer resin portion 350 and are thermoset and integrated in the embedded state. An arrow 320a shown in FIG. 9 indicates a state of pressurization and heating applied to bury the second vias 170a to 170b and the second wirings 160a to 160d formed in an uneven shape on the surface of the intermediate wiring board 180. Show. An arrow 320b indicates that the uncured outermost resin layer 350 is filled and embedded in the gaps (or irregularities) between the second vias 170a to 170b and the second wirings 160a to 160d.

  In FIG. 9, a glass woven fabric, a glass nonwoven fabric, or a heat resistant film such as polyimide may be used as the core material 200 (not shown) for the uncured outermost layer resin portion 350. By providing these core members 200 (not shown in FIG. 9), the copper foil 340, the second vias 170a to 170b, and the second wirings 160a to 160d are in contact with each other in the pressurization and heating process. There is no. Moreover, the handling property can be improved by using the member (for example, prepreg 270) using heat resistant films, such as a glass woven fabric, a glass nonwoven fabric, or a polyimide, for the connection layer 220. FIG.

  In particular, variations in thickness and shape (surface shape or pattern edge shape) of the second vias 170a to 170b and the second wirings 160a to 160d are wirings formed by patterning the copper foil 340 (for example, the first wiring 120). This is because the second vias 170a to 170b and the second wirings 160a to 160d are formed using a plating technique. That is, the plating deposition rate is affected by the flow rate or activity of the plating solution depending on the density of the wiring pattern or the presence or absence of vias. For example, in FIG. 9, the wiring thickness of the second via 170a is thicker than the wiring thickness of the second via 170b. In FIG. 9, the wiring thicknesses of the second wirings 160a to 160d are 160d> 160a> 160b> 160c. As shown by the arrow 320c, the second vias 170a to 170b and the second wirings 160a to 160d formed by the plating technique having different wiring thicknesses (further different wiring widths or wiring patterns) are indicated by arrows 320c. Embed in the uncured outermost resin layer 350. The second vias 170a to 170b and the second wirings 160a to 160d formed by plating techniques having different wiring thicknesses (or different wiring widths or wiring pattern densities) are embedded in the uncured outermost resin layer 350. At this time, specific stresses are generated in each portion, but these stresses can be relaxed by the first via 130. This is because the first via 130 is made of a paste via, and the first via 130 made of a paste via is formed through a predetermined heating and pressing process.

  Further, in the present invention, the heating and pressing step shown in FIG. 8 and the heating and pressing step shown in FIG. 9 are performed in one heating and pressing step, so that the second vias 170a to 170b and the second wirings 160a to 160d are formed. The generation of stress caused by filling and embedding the uncured outermost resin layer 350 and the uncured adhesive resin portion 360 in the gap (or unevenness) can be made smaller. This is because the uncured outermost layer resin portion 350 and the uncured adhesive resin portion 360 are inserted as a kind of cushion material on both surfaces of the intermediate wiring board portion 180, and follow the uneven surface by being pressed. Because. That is, the uncured outermost layer resin portion 350 and the uncured adhesive resin portion 360 are softened and liquefied by being heated from room temperature (for example, 20 ° C.), so that the stress is relieved. Then, even if it is a case where it hardens | cures, even if it is a hardening state at the time of a heating, since an elasticity modulus falls, stress can be relieved.

  Furthermore, the uncured outermost layer resin portion 350 and the uncured adhesive resin portion 360 are inserted on both surfaces of the intermediate wiring substrate portion 180 as a kind of cushioning material and pressed, so that both surfaces of the intermediate wiring substrate portion 180 are pressed. Even if the patterns of the second vias 170a to 170b and the second wirings 160a to 160d formed on the back surface are different from each other on the back surface, this causes variations in compressive force on the conductive paste 300. There is no. This is a kind of “water bed” or “cushion” when the uncured outermost resin part 350 and the uncured adhesive resin part 360 installed on both surfaces of the intermediate wiring board part 180 are pressed and heated with the conductive paste 300. In order to bury and absorb the unevenness formed by the second vias 170a to 170b and the second wirings 160a to 160d formed on the surface thereof. Then, with the unevenness made up of the second vias 170a to 170b, the second wirings 160a to 160d, etc. buried as “water bed” or “cushion”, heat is applied simultaneously with the uncured outermost resin part 350 and the uncured adhesive resin part 360. Curing suppresses unnecessary stress generation.

  As described above, by performing the embedding to thermosetting steps shown in FIGS. 8 and 9 at the same time (or in one heating and pressing step), the influence of the density of the second wiring 160 and the second via 170, the second Specific problems that occur when the wiring 160 and the second via 170 are formed using a plating technique (pattern width variation, wiring thickness variation due to the presence or absence of vias, pattern edge variation variation, etc.) It can be absorbed at once, increasing the reliability of the connection part.

  As described above, the method for manufacturing the composite multilayer wiring board 260 of the present invention includes the first insulating layer 110, the first wiring 120 formed on both surfaces of the first insulating layer 110, and the first wiring 120. The double-sided board part 140 having the first via 130 electrically connected, the second insulating layer 150 filling the first wiring 120, the second wiring 160 and the second via 170 formed in the second insulating layer 150. A plurality of intermediate wiring board portions 180, and a connection layer 220 having a thermosetting resin portion 190 that is a cured product of an uncured adhesive resin and a core material 200 that bonds the intermediate wiring board portions 180. The connection layer 220 having a connection via 210 penetrating the connection layer 220 is further formed. Further, the outermost insulating layer 230 is formed on the outermost layer of the intermediate wiring board portion, and the outermost insulating layer 230 is formed on the outermost insulating layer 230. Outermost layer wiring 240 and outermost layer In the method of manufacturing the composite multilayer wiring board 260 having the via 250, the first wiring 120 is made of copper foil wiring, the first via 130 and the connection via 210 are both paste vias, and the second wiring 160 and the outermost layer wiring. 240 is a plating wiring, both the second via 170 and the outermost via 250 are plating vias, and the connection layer 220 is connected to the second via 170 (or the second wiring 160) on the connection layer 220 side. The outermost insulating layer 230 of the sheet includes a step of simultaneously burying the second via 170 (or the second wiring 160) on the side different from the connection layer 220 side, and the connection layer 220 is the first via on the connection layer 220 side. In the state where the two vias 170 (and the second wiring 160) are embedded, the two outermost insulating layers 230 have the second via 170 (and the second wiring 160) on the side different from the connection layer 220 side. In the state, a method of manufacturing the composite multilayer wiring board 260 having a step of thermosetting each simultaneously.

  In the case of the composite multilayer wiring board 260 of the present invention, the outermost layer wiring 240 and the outermost layer via 250 formed in the outermost layer are preferably formed after the connection layer 220 and the uncured outermost layer resin portion 350 are cured. This is because embedding of wiring or the like reduces the unevenness of the outermost layer. Further, by forming the outermost layer wiring 240 and the outermost layer via 250 in the outermost layer with few irregularities, it is possible to achieve high precision, high density, and finer.

  As described above, the second embodiment includes a plurality of intermediate wiring board portions 180 having the first vias 130 made of paste vias and the second vias 170 made of plating vias formed on both surfaces, and the intermediate wiring board portions. 180, a connection layer 220 having a connection via 210 made of paste via, and an outermost layer via 250 made of a plating via on the outermost layer side of the outermost insulating layer 230. The first wiring 120 is made of copper foil. The first via 130 and the connection via 210 are both paste vias, the second wiring 160 and the outermost layer wiring 240 are both plated wiring, and the second via 170 and the outermost layer via 250 are both plated vias. This is a method for manufacturing the composite multilayer wiring board 260.

  The composite multilayer wiring board 260 includes a preparation step for preparing a plurality of intermediate wiring board portions 180, and an uncured connection layer 220 (or prepreg 270) having a conductive paste 300 between the plurality of intermediate wiring board portions 180. The installation step of installing the uncured outermost resin layer 350 on the outermost layer side of the intermediate wiring board 180, and the uncured connection layer 220 (or prepreg 270) are connected to the connection layer 220 (or prepreg 270) side. In the second wiring 160, the two uncured outermost resin portions 350 are embedded in the second wiring 160 on the uncured outermost resin portion 350 side, and the connection layer 220 ( Alternatively, the composite multilayer wiring board 26 including a prepreg 270) and an embedded thermosetting process in which the uncured outermost resin layer 350 is thermally cured at the same time. The method of production.

(Embodiment 3)
In the third embodiment, an example of the trial results of the inventors will be described. The inventors created an ALIVH substrate (ALIVH: meaning Any Layer Interstitial Via Hole, ALIVH is a registered trademark of Panasonic Corporation) as the double-sided substrate portion 140. Then, a second insulating layer 150 is formed thereon, and a bottomed hole is formed by a laser. Then, a second wiring 160 and a second via 170 are formed by using a plating technique, and the intermediate wiring substrate portion 180 is obtained. In addition, when double-sided ALIVH is used as the core part of the intermediate wiring board part 180, it is useful that the intermediate wiring board part 180 corresponds to a four-layer board. In addition, when the four-layer ALIVH is used as the core portion of the intermediate wiring board portion 180, it is useful that the intermediate wiring board portion 180 is equivalent to a six-layer board. Thus, a plurality of intermediate wiring board portions 180 having four or more layers were prepared. If necessary, it is useful to use a multilayer board having six or more layers as the intermediate wiring board portion 180.

  Next, a commercially available prepreg (glass fiber impregnated with an uncured epoxy resin) is prepared, and a protective film 280 (for example, a PET film with a thickness of 20 μm) is pasted on both sides as shown in FIG. After attaching, the through-hole 290 was formed with the laser. Thereafter, a conductive paste 300 containing conductive powder and a thermosetting resin was filled in the through hole 290 as shown in FIG. Thereafter, the protective film 280 was peeled off to obtain the state shown in FIG.

  Next, as shown in FIG. 4, these members were integrated by heating and pressurizing using a press device and a mold. 6 to 7, a bottomed hole was formed in the outermost insulating layer 230 with a laser, and then the outermost wiring 240 and the outermost via 250 were formed using a plating technique.

  Below, an example of the trial result which the inventors performed is demonstrated. (Table 1) is a table for explaining an example of a trial result.

  As shown in FIG. 3D, the second wiring 160 and the second via 170, which are the surface layer wiring, used the plating technique as the intermediate wiring board portion 180 used for producing the invention product in (Table 1). A thing was used. In addition, the central portion of the intermediate wiring board portion 180 (for example, the double-sided board portion 140) used is the one having the first wiring 120 using copper foil wiring and the first via 130 made of paste via. Thus, as the intermediate wiring board portion 180 of the invention in (Table 1), the first wiring 120 that becomes the inner layer conductor (or the inner layer conductor that is not exposed to the outside), and the paste via and the copper foil wiring as the first via 130 As the second wiring 160 and the second via 170 serving as the outer layer conductor (or the exposed surface conductor), a four-layer substrate using a plating technique was prepared as the second wiring 160 and the second via 170. Here, as the second wiring (plating wiring) 160 and the second via (plating via) 170, those using a semi-additive method and having a line spacing / line width / wiring thickness = 30 μm / 30 μm / 30 μm were used. Thus, by using a plating technique for the surface layer, the second wiring 160 can be made thicker and finer.

  Next, the “first comparative product” described in (Table 1), which the inventors have made as a prototype for comparison, will be described. As an intermediate wiring board portion 180 of the first comparative product, a four-layer board without paste vias and having all layers made of plating vias and plating wirings was prepared. The surface layer of this four-layer substrate is formed of plated vias and plated wiring. By using a semi-additive method as the second wiring (plating wiring) 160 and the second via (plating via) 170 provided on the surface layer of the intermediate wiring board portion for the first comparative product, the line spacing / line width / Wiring thickness = 30 μm / 30 μm / 30 μm was possible.

  Next, the “second comparative product” manufactured by the inventors for comparison in (Table 1) will be described. As the second comparative product, the intermediate wiring board portion 180 was prepared as a four-layer board in which all layers were paste vias and had no plating vias or plating wirings. Since the surface layer of this four-layer substrate was formed by etching a copper foil wiring using a subtract method, it was sometimes difficult (△) to set the line spacing / line width / wiring thickness = 30 μm / 30 μm / 30 μm. .

  Next, the reliability of the connection via 220 in the connection layer 220 was examined for the inventive product, the first comparative product, and the second comparative product thus created. As a result, reliability ○ (good, no problem occurred) for the invention product, reliability △ (some problems may occur) for the first comparative product, reliability ○ (△ depending on the structure) for the second comparative product Met.

  As a result of analyzing the problems that occurred in the first comparative product, the inventors found that there was a problem in the series via structure (that is, a via structure in which a plurality of plating vias were laminated in a thickness direction and integrated in series). It has been found that this may occur.

  Similarly, as a result of analysis by the inventors on the problem that occurred in the second comparative product, in a serial via structure (that is, a via structure in which a plurality of paste vias are laminated in series in the thickness direction and integrated) , It was found that there may be challenges.

  On the other hand, in the invention, even when the direct via structure is used, such a problem does not occur.

  From the above, as a comprehensive evaluation, the invention product is ○ (good, no problem occurred), the first comparative product (all vias constituting the intermediate wiring board portion 180 are plating vias), and Δ (issue occurs) ), The second comparative product (all vias constituting the intermediate wiring board portion 180 are paste vias) was ◯ (good, no problem occurred), but △ ( In some cases, problems may occur.

  Therefore, the inventors further investigated this cause. A problem with the serial via structure that has been found for the first time by the inventors' experiments will be described with reference to the fourth embodiment.

(Embodiment 4)
The results of experiments conducted by the inventors will be described using the fourth embodiment. In the fourth embodiment, the influence of the difference in via structure particularly on the reliability of the connection via in the connection layer will be described.

  As a result of various experiments by the inventors, it has been found that when the intermediate wiring board portion 180 has a serial via structure, a problem occurs in the connection via in the connection layer.

  FIG. 10 is a cross-sectional view illustrating a problem that may occur when an intermediate wiring board having a plurality of plating vias in series in the thickness direction is used.

  In FIG. 10, 370 is a first comparison product, 380 has a first series via structure, and the first comparison product 370 has a first series via structure 380 in a part thereof. Here, the first series via structure 380 is a via structure in which a plurality of plating vias are stacked in series in the thickness direction. Further, all the vias constituting the serial via included in the first comparative product 370 are plating vias.

  As shown in FIG. 10, in the case of the first series via structure 380 in which all the series vias are plated vias, the applied pressure as shown by the arrow 320a is directly applied to the conductive paste 300 as shown by the arrow 320b. This is because all of the serial vias are plated vias made of a metal such as copper having high strength and are integrated with each other. Therefore, the applied lamination pressure is directly transmitted to the conductive paste 300 formed on the uncured adhesive resin portion 360 through the integrated high-strength first series via structure 380. As a result, the conductive paste 300 absorbs all of the thickness variation of the plurality of second vias (plating vias) 170 constituting the first series via structure 380, the thickness variation of the intermediate wiring board portion 180a, and the like. Therefore, when the thickness variation of the second via (plating via) 170 or the thickness variation of the intermediate wiring board portion 180a becomes large, this variation cannot be absorbed by the conductive paste 300. In some cases, stress is applied excessively, and defects such as microcracks occur in the plated via connection portion. This has been a factor of reducing the connection reliability of the serial via.

  In the above (Table 1), the intermediate wiring board portion 180 used for the production of the first comparative product is a four-layer board. However, as shown in FIG. There may be a case where a problem occurs in the connectivity between the connection via 210 formed by pressurizing and heating 300 and the second via 170. This is because the first serial via structure 380 of the intermediate wiring board portion 180a constituting the first comparative product 370 is all formed by plating vias, and the number of layers is 4 layers → 6 layers → 8 layers. This is because the thickness variation of the second via (plating via) 170 and the thickness variation of the intermediate wiring board portion 180 are integrated and increased as the increase increases, and all of this variation needs to be absorbed by the conductive paste 300. When this variation cannot be absorbed by the conductive paste 300, the connection reliability may be reduced at the plated via portion.

  Next, a problem that may occur when the intermediate wiring board portion 180 having a portion in which a plurality of paste vias are arranged in series in the thickness direction will be described with reference to FIG.

  FIG. 11 is a cross-sectional view for explaining a problem that may occur when an intermediate wiring board having a plurality of paste vias arranged in series in the thickness direction is used.

  In FIG. 11, reference numeral 390 denotes a second comparative product, 400 denotes a second serial via structure, and the second comparative product 390 has a second serial via structure 400 in a part thereof. Here, the second serial via structure 400 is a via structure in which a plurality of paste vias are stacked in series in the thickness direction. Further, the vias constituting the serial vias included in the second comparative product 390 are the second serial via structure 400 made of paste vias.

  As shown in FIG. 11, in the case of the second serial via structure 400 in which the serial vias are all composed of paste vias, the pressure as indicated by the arrow 320a is applied from a plurality of paste vias as indicated by the arrow 320b. It is transmitted to the conductive paste 300 through the first via 130. However, the paste via is obtained by pressurizing and compressing a plurality of metal powders such as copper powder, and includes a thermosetting resin, and therefore has a lower strength than the plating via. For this reason, there is a limit to increasing the stress that structurally compresses the conductive paste 300.

  Further, the serial via structure is a portion where the difference in thermal expansion from the adjacent base material is the largest because the vias are connected in the substrate thickness direction. In reliability tests such as heat cycle tests, stress due to the difference in thermal expansion coefficient occurs, but simulation results show that such fracture stress concentrates on the via located in the center of the stack via when viewed in the thickness direction of the board. know.

  As described above, the conductive paste 300 located at the center of the serial via structure has a structurally larger fracture stress. Therefore, in this structure, the stress compressing the conductive paste 300 is insufficient, and the connection reliability is lowered. It turned out that there is a case to let it. That is, it has been found that it is desirable that the conductive paste 300 be thermally cured with a high compressive force to have higher via connection reliability.

  In the above-mentioned (Table 1), the intermediate wiring board portion 180b used for the production of the second comparative product is a four-layer board. However, as shown in FIG. There may be a case where a problem occurs in the connectivity. Furthermore, even when the number of layers is increased from 4 layers → 6 layers → 8 layers, it is conceivable that the same problem occurs.

  12 and 13 are cross-sectional views for explaining an example of a mechanism for improving the connection stability between the intermediate wiring board portion and the conductive paste in the invention.

  12 to 13, the intermediate wiring board portion 180 forms an invention via structure 410 in which a first via 130 made of a paste via and a second via 170 made of a plating via are arranged in series in the thickness direction. Yes.

  In FIG. 12, the invention via structure 410 is obtained by stacking paste vias made of the first vias 130 and the like and plating vias made of the second vias 170 and the like in series in the thickness direction. In the invention via structure 410, the second via 170 embedded in the prepreg 270 and electrically connected to the conductive paste 300 is composed of a plated via. This is because the second via 170 embedded in the prepreg 270 and electrically connected to the conductive paste 300 is composed of a plating via (or plating wiring) having a strength higher than that of the paste via or copper foil wiring. It effectively applies a compressive force to the conductive paste 300.

  In FIG. 13, the invention via structure 410 is obtained by laminating a paste via made of the first via 130 and the like and a plating via made of the second via 170 and the like in series in the thickness direction. In the invention via structure 410, the second via 170 embedded in the prepreg 270 and electrically connected to the conductive paste 300 is composed of a plated via. This is because the second via 170 embedded in the prepreg 270 and electrically connected to the conductive paste 300 is composed of a plating via (or plating wiring) having a strength higher than that of the paste via or copper foil wiring. It effectively applies a compressive force to the conductive paste 300.

  On the other hand, as shown in FIG. 13, the invention via structure 410 is a paste via composed of the first via 130 and the like and a plating via composed of the second via 170 and the like laminated in series in the thickness direction, Furthermore, it is assumed that the second via 170 embedded in the prepreg 270 and electrically connected to the conductive paste 300 is composed of a plated via. Thus, the paste via made of the first via 130 and the like is softer than the plating via, and plays a role of relieving the stress applied to the plating via portion during the lamination press. With such a structure, it is possible to disperse the stress applied to the serial vias during the laminating press, and to achieve both the generation of microcracks in the plated via portion and the high compression of the paste made of the conductive paste 300.

  In the invention via structure 410, it is only necessary that the second via 170 embedded in at least the prepreg 270 and electrically connected to the conductive paste 300 is composed of a plated via. Therefore, even if the outer layer portion of the intermediate wiring board portion 180 is a multilayer wiring board having a plurality of plating vias, it is useful to have a paste via in a part thereof. Even if the second via 170 embedded in the prepreg 270 of the serial via and electrically connected to the conductive paste 300 is formed of a multi-layer plating via, the paste via is partially (particularly in the inside). It is useful to have a first via 130 consisting of This is because the paste via formed in a part of the serial via structure part (particularly the central part) absorbs the thickness variation of the intermediate wiring board part 180.

(Embodiment 5)
In the fifth embodiment, the composite multilayer wiring board 260 of the present invention described in the first embodiment will be described in more detail.

  The thickness of the second wiring (plating wiring) 160 and the second via (plating via) 170 formed on the surface layer of the intermediate wiring board portion 180 is desirably 20 μm or more. By increasing the thickness of the second wiring (plating wiring) 160 and the second via (plating via) 170 to 20 μm or more, and further increasing the thickness of the plating wiring to 20 μm or more for all layers, the current can be increased. It can correspond to. In addition, loss due to wiring resistance can be reduced, and it is useful to use in equipment using a high-frequency circuit. It is useful that the thickness of the second wiring (plating wiring) 160 and the second via (plating via) 170 formed on the surface layer of the intermediate wiring board 180 is 100 μm or less. When the thickness of the second wiring (plating wiring) 160 or the second via (plating via) 170 formed on the surface layer of the intermediate wiring board portion 180 exceeds 100 μm, it is difficult to planarize (or bury) the connection layer 220. There is a case.

  In the case of the composite multilayer wiring of the present invention, the second wiring (plating wiring) 160 and the second via (plating via) 170 are embedded in the connection layer 220 (or prepreg 270). The thickness of the wiring (and the volume of the plated wiring) can be effectively absorbed by the electrically insulating base material made of the connection layer 220 (or prepreg 270). At the same time, the conductive paste 300 is more strongly compressed, so that the connection stability is improved and the resistance of the paste via can be reduced.

  In the experiments of the inventors, when the uncured adhesive resin portion 360 is formed as the connection layer 220 on the core material 200 made of glass woven fabric or the like (or on both surfaces) with a thickness of 15 μm, the plating wiring thickness is In the case of 10 μm, there was a case where the paste of the conductive paste 300 was insufficiently compressed and the resistance value variation became large. In such a case, when the plating wiring thickness is 15 μm, the resistance value tends to decrease and the variation tends to decrease. Further, by setting the plating wiring thickness to 20 μm or more, both the resistance value and the variation are independent of the plating thickness. As a result, the tendency to stabilize at almost constant value was confirmed.

  The intermediate wiring board part 180 is a double-sided board part 140 that is electrically connected by a first via 130 whose center part is made of paste vias, and further has second wirings 160 made of plated wiring on both sides thereof. It is useful to make a four-layer wiring board.

  In particular, by using a four-layer wiring board in which paste vias and plating vias are used in combination, a via land can be reduced in diameter, and a multilayer wiring board capable of accommodating wiring at a higher density can be provided. Further, wiring is formed for the vias of the intermediate wiring board portion 180 (for example, when a bottomed hole is formed in the second insulating layer 150 to form the second wiring 160 and the second via 170), and a first via made of a paste via. By measuring the position of 130 and exposing using LDI (Laser Direct Imaging Method), it becomes possible to adjust the dimensional coefficient for each substrate and to correct the coordinate distortion in the substrate surface. Can be aligned.

  When forming the double-sided board where the via is completely covered with a conductor by using a normal plating method, it is necessary to create a state in which only one side is opened by laser via processing and copper is exposed on the bottom of the via However, there is a problem that it takes a lot of man-hours and costs increase, such as etching the copper foil only on one side to form an opening. In response to such a problem, in the composite multilayer wiring board 260 of the present invention, both the via formation and the pattern formation are performed as a process for forming the second via 170 serving as the plating via formed on both sides of the double-sided board portion 140. By using (or LDI), a very high-density four-layer intermediate wiring board can be realized by a simple method.

  Needless to say, the second wiring 160 serving as the surface wiring of the intermediate wiring board portion 180 is a plated wiring, so that the adjustment of the wiring thickness is facilitated.

  For example, when the copper foil 340 is used as a wiring material for the second wiring 160 of the intermediate wiring board portion 180, the copper foil 340 is produced in a large amount in a roll shape, so that a storage cost is generated. Further, when the copper foil 340 is used as the second wiring 160 of the intermediate wiring board portion 180, there is a problem that it is actually difficult to prepare a plurality of wiring thickness variations. In addition, it becomes difficult to adjust the wiring thickness according to the product design.

  Further, the volume (or the amount of the superposition resin) of the uncured adhesive resin portion 360 formed on the core material 200 (at least on one side and further on both sides) of the connection layer 220 is embedded in the connection layer 220. It is useful to make it larger than the wiring volume of the two wirings 160 and the second vias 170 (or the second wirings 160 and the second vias 170 formed on the connection layer 220 side of the intermediate wiring board part 180). In addition, it is useful that the volume ratio is 1.1 times or more and 10.0 times or less (further 1.5 times or more and 7.0 times or less, and further 2.0 times or more and 5.0 times or less). By doing so, the uncured adhesive resin portion 360 formed in the connection layer 220 does not become too large, and optimal compression can be applied to the via paste, and as a result, the connection resistance value can be stabilized at a low resistance. it can.

  As described above, it is important to accurately control the embedding of the plating wiring composed of the second wiring 160 formed on the surface layer of the intermediate wiring board portion 180, but in fact, the plating wiring pattern varies depending on the product. There is. In such a case, it is useful to further optimize the embedded state of the plated wiring depending on the product. Control not only the thickness of the plated wiring, but also the volume of the plated wiring (sometimes referred to as the residual copper ratio in the substruct method), and the amount of the uncured adhesive resin portion 360 necessary for embedding the plated wiring is sufficiently Securing is useful for solving the shortage of wiring embedding.

  Furthermore, the plating via (for example, the second via 170) formed in the intermediate wiring board portion 180 has a filled via structure, and it is useful that the recess on the via is 10 μm or less. By setting the recess on the via to 10 μm or less, it is possible to ensure sufficient compression to realize electrical connection even when the paste via is disposed at a location corresponding to the recess.

  For example, when a paste via is disposed on the second via 170 serving as a plating via of the intermediate wiring board portion 180, the plating surface shape affects the compression of the paste. Therefore, if there is a dent on the plating via, paste compression may be insufficient accordingly.

  In the experience of the inventors, for example, the connection layer 220 which is an electrically insulating substrate is bonded to a commercially available substrate having a thickness of 60 μm (for example, an uncured adhesive made of an uncured epoxy resin to a core material 200 made of glass fiber). In the case of using a prepreg 270 formed by forming the resin part 360 on both sides, when the dent on the via is 20 μm, the resistance value is large and the variation is large, and the resistance value change may be large with respect to the dent amount. there were. However, in such a case, it was confirmed that the resistance value of the via becomes substantially constant by setting the dent on the plated via to 15 μm or less (more preferably 10 μm or less).

  The surface roughness of the second wiring 160 made of plated wiring formed on the intermediate wiring board portion 180 and the second via 170 made of plating via is preferably set to 1.0 μm or more and 3.0 μm or less in Rz. It is. By setting the surface roughness Rz of the second wiring 160 and the second via 170 to a rough surface of 1.0 μm or more and 3.0 μm or less, the adhesion with the connection layer 220 which is an electrically insulating substrate is improved. Furthermore, the connection stability between the second wiring 160 and the second via 170 and the conductive paste 300 (or the connection via 210) is improved, in order to ensure the number of contact points with the conductive particles contained in the conductive paste 300.

  As the conductive paste 300 used for manufacturing the composite multilayer wiring board 260 of the present invention, it is useful in terms of cost to use a conductive particle having an average particle diameter of about 5 μm. When the surface roughness Rz of the second wiring 160 and the second via 170 is larger than 3.0 μm with respect to such a conductive paste 300, the electrical contact point may decrease and the resistance value may increase. In addition, when the surface roughness Rz of the second wiring 160 and the second via 170 is less than 1.0 μm, the anchor effect is reduced with the connection layer 220 serving as an electrically insulating base material, and reflow is used. There is a possibility of delamination phenomenon in the heat test.

In addition, it is useful that the number (or density) of paste vias provided in the connection layer 220 serving as an electrically insulating substrate is 30 / cm ² or more and 100,000 / cm ² or less. For example, there are cases where stress paste via is deformed by thermal expansion difference of the core material 200 and the intermediate circuit board 180 acts, the density of the paste via, by a 30 / cm ² or more, with respect to the stress Thus, the paste via becomes a pile and has an effect of suppressing deformation. As a result, a stable paste connection can be realized as a result. Needless to say, if the via density cannot be ensured in the product area, the same effect can be obtained even if the via density is formed outside the product area.

In the experiments by the inventors, when the number of paste vias provided in the connection layer 220 serving as an electrically insulating substrate is about 1 to 5 / cm ² , a mode in which the vias deform in the shearing direction may occur. In such a case, the resistance value tended to vary greatly, but by increasing the density of paste vias to 10 / cm ² or more, the resistance value started to decrease, and to 30 / cm ² or more. Thus, the mode that the via deforms in the shear direction can be improved. It is technically difficult to increase the number (or density) of paste vias to more than 100,000 / cm ² .

  It should be noted that it is useful to set the wiring occupancy ratio of the wiring composed of the second wiring 160 and the second via 170 formed on the surface layer of the intermediate wiring board portion 180 to 50% or more and 90% or less. By setting the wiring occupancy ratio of the wiring composed of the second wiring 160 and the second via 170 formed on the surface layer of the intermediate wiring board portion 180 to 50% or more and 90% or less, the uncured provided in the connection layer 220 It is desirable in terms of allowing the adhesive resin portion 360 to flow stably. This is also preferable in terms of reducing the uncured adhesive resin portion 360 necessary to fill the gap between the wirings including the second wiring 160 and the second via 170 by setting the wiring occupation ratio to 50% or more and 90% or less. It is also useful to adjust the wiring occupancy in the panel state as close as possible in the area other than the product. By doing so, the resin flow in the product portion can be optimized, and the connection stability using the paste via can be improved.

  As described above, the connection layer 220 including the connection via 210 including the paste via is provided between the two intermediate wiring board portions 180 including the first via 130 including the paste via and the second via 170 including the plating via. And the outermost layer insulating layer 230 has an outermost layer via 250 made of a plated via, and the connection layer 220 connects the second via 170 on the connection layer 220 side to the outermost layer insulating layer 230. The composite multilayer wiring board 260 is formed by simultaneously embedding the second vias 170 on the outermost insulating layer 230 side and simultaneously thermosetting them.

  By using the manufacturing method of the composite multilayer wiring board 260 as described above, a high-density multilayer wiring board such as a 200 μm land, a 150 μm land, or a 100 μm land can be manufactured with a short lead time.

  Furthermore, in the present invention, it is useful for the profile at the time of lamination by hot pressing to slow the rate of temperature rise to 3 ° C./min or less. When embedding the second wiring 160 and the second via 170 serving as the surface layer wiring of the intermediate wiring board portion 180 in the connection layer 220, it is useful to slow the temperature increase rate to 3 ° C./min or less. By doing so, it is possible to sufficiently secure the time during which the uncured adhesive resin portion 360 is softened, and the second wiring 160 and the second via 170 are easily embedded in the connection layer 220. In the softening temperature region where the uncured adhesive resin portion 360 is softened, it is also useful to make the temperature rising rate smaller than the temperature rising rate so far.

  Moreover, it is useful that the uncured outermost layer resin portion 350 also serves as a cushion layer (or cushion material). For that purpose, it is useful to make the resin flow of the uncured outermost resin part 350 larger than the resin flow of the uncured adhesive resin part 360. The cushion effect can be further enhanced by softening (or melting or flowing) the uncured outermost resin portion 350, which is the outermost layer, at a lower temperature than the uncured adhesive resin portion 360. The pressure applied to the connection layer 220 can be made more uniform by softening the uncured outermost resin layer 350 before (or at a lower temperature) the uncured adhesive resin portion 360. The connection stability of the connection via 210 made of paste via can be improved.

  The outermost insulating layer 230 (or the uncured outermost resin layer 350) may have the core material 200. By having the core member 200, the uncured outermost layer resin portion 350 can be easily handled, and the outermost insulating layer 230 can be increased in strength.

  Further, in order to improve the resin flow (or cushioning property or unevenness embedding property) of the outermost insulating layer 230 (or uncured outermost resin portion 350), the outermost insulating layer 230 (or uncured outermost resin portion 350). It is also useful that the core material 200 is not included. Since the core material 200 is not provided, the resin flow property can be improved.

  As described above, according to the present invention, it is possible to provide a high-performance and inexpensive composite multilayer wiring board that takes advantage of both plating vias and paste vias.

110 1st insulating layer 120 1st wiring (copper foil wiring)
130 First via (paste via)
140 Double-sided board part 150 Second insulating layer 160 Second wiring (plating wiring)
170 Second via (plating via)
180 Intermediate wiring board part 190 Thermosetting resin part 200 Core material 210 Connection via (paste via)
220 Connection layer 230 Outermost layer insulating layer 240 Outermost layer wiring (plating wiring)
250 Outermost layer via (plating via)
260 composite multilayer wiring board 270 prepreg 280 protective film 290 through hole 300 conductive paste 310 squeegee 320 arrow 330 protruding portion 340 copper foil 350 uncured outermost layer resin portion 360 uncured adhesive resin portion 370 first comparative product 380 first serial via structure (All plated vias)
390 Second comparative product 400 Second serial via structure (all paste vias)
410 Invention via structure (plating via + paste via)

Claims (11)

A plurality of intermediate wiring board portions having a first via made of a paste via and a second via made of a plating via formed on both surfaces;
A connection layer having a connection via made of a paste via that connects between the intermediate wiring board parts,
On the outermost layer side of the intermediate wiring board part, it has an outermost layer insulating layer and an outermost layer via made of a plating via,
The connection layer is embedded in the second via on the connection layer side of the intermediate wiring substrate portion, and the outermost insulating layer is embedded in the second via on the outermost insulating layer side of the intermediate wiring substrate portion and thermally cured. A composite multilayer wiring board. A double-sided substrate portion having a first insulating layer, a first wiring formed on both surfaces of the first insulating layer, and a first via for electrically connecting the first wiring, and filling the first wiring A plurality of intermediate wiring board portions each having a second insulating layer, a second wiring and a second via formed in the second insulating layer;
A connection layer having a thermosetting resin part and a core material for bonding between the intermediate wiring board parts, and a connection layer having a connection via penetrating the connection layer,
Furthermore, the outermost layer of the intermediate wiring board part has an outermost layer insulating layer, and the outermost layer wiring and outermost layer via formed in the outermost layer insulating layer,
The first wiring is composed of copper foil wiring, and the first via and the connection via are both paste vias,
The second wiring and the outermost layer wiring are both composed of plating wiring, and the second via and the outermost layer via are both plating vias,
The connection layer has the second wiring on the connection layer side buried, and the two outermost insulating layers have both the second wiring on the side different from the connection layer buried, and both are heated simultaneously. A composite multilayer wiring board that is cured. The composite multilayer wiring board according to claim 1, wherein the connection layer is a cured product of a prepreg. The composite multilayer wiring board according to claim 1, wherein the intermediate wiring board portion includes a core material made of glass cloth. The composite multilayer wiring board according to claim 1, wherein the intermediate wiring board portion includes a core material made of a heat resistant film. The composite multilayer wiring board according to claim 1, wherein the intermediate wiring board portion has six or more layers of wiring. 5. The composite multilayer wiring board according to claim 2, wherein the thickness of the second wiring made of the plated wiring is 20 μm or more and 100 μm or less. 5. The composite multilayer wiring board according to claim 1, wherein the second via made of a plated via formed in the intermediate wiring base has a filled via structure, and a recess on the via is 10 μm or less. 5. The composite multilayer wiring board according to claim 1, wherein the surface roughness Rz of the second wiring made of plated wiring or the second via made of plated via is 1.0 μm or more and 3.0 μm or less. 5. The composite multilayer according to claim 1, wherein the density of the connection vias made of paste vias formed in the connection layer is 30 / cm ² or more and 100,000 / cm ² or more. Wiring board. A plurality of intermediate wiring board portions having a first via made of a paste via and a second via made of a plating via formed on both surfaces;
A connection layer having a connection via made of a paste via that connects between the intermediate wiring board parts,
On the outermost layer side of the intermediate wiring board part, a method for producing a composite multilayer wiring board having an outermost layer insulating layer and an outermost layer via made of a plating via,
Preparing a plurality of the intermediate wiring board parts;
An installation step of installing an uncured connection layer having a conductive paste between the plurality of intermediate wiring substrate portions, and an uncured outermost layer resin portion on the outermost layer side of the intermediate wiring substrate portion;
The connection layer in the uncured state is embedded in the second via on the connection layer side, and the two uncured outermost layer resin parts are embedded in the second via on the uncured outermost layer resin part side simultaneously. Process,
A method for manufacturing a composite multilayer wiring board, comprising: an embedded thermosetting process in which each of the embedded thermosetting processes is simultaneously performed in an embedded state.

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