JP5927946B2 - Manufacturing method of multilayer wiring board - Google Patents

Description

  The present invention generally relates to a method for manufacturing a multilayer wiring board and a multilayer wiring board, and more specifically, a multilayer wiring including a step of thermocompression bonding a plurality of laminated resin sheets by a collective multilayer press method. The present invention relates to a board manufacturing method and a multilayer wiring board manufactured by such a method.

  Regarding a conventional method of manufacturing a multilayer wiring board, for example, Japanese Patent Application Laid-Open No. 2003-304071 discloses a multilayer substrate for the purpose of preventing the generation of voids by eliminating air and gas from between laminated resin films. Is disclosed (Patent Document 1).

  In the method for manufacturing a multilayer substrate disclosed in Patent Document 1, a multilayer substrate is manufactured by pressing a laminated body composed of a plurality of single-sided conductor pattern films while heating from above and below both surfaces. Under the present circumstances, a resin sheet, a press plate, and a buffer material are arrange | positioned from the side close | similar to a laminated body between a laminated body and a hot press board. The resin sheet is provided to prevent the thermoplastic resin constituting the single-sided conductor pattern film from adhering to the press plate, and is formed of polyimide or Teflon (registered trademark). The press plate is provided in order to more completely eliminate air and gas from the single-sided conductor pattern film, and is formed from a stainless steel thin plate or the like. The buffer material is provided to apply the pressure applied from the hot press plate to the entire press plate, and is formed of asbestos, glass fiber, resin fiber, or the like.

JP 2003-304071 A

  As disclosed in Patent Document 1 described above, a multilayer substrate is obtained by laminating a thermoplastic resin film having a conductor pattern formed on the surface in multiple layers and pressing the resulting laminate while heating. The method is known.

  However, when a multilayer substrate is manufactured using such a method, the positions where the conductor patterns are densely arranged and the positions where the conductor patterns are sparsely arranged are arranged between the hot press plates at the time of heating and pressing the laminated body. Arise. In this case, the pressure acting on the laminated body from the hot press plate becomes relatively large at the positions where the conductor patterns are densely arranged, so that the resin softened by heating becomes less sparse from the positions where the conductor patterns are densely arranged. It flows greatly toward the position where it is arranged. As a result, with such a resin flow, the conductor pattern is displaced or deformed, resulting in a problem that the dimensional stability and the shape accuracy of the manufactured multilayer substrate are lowered.

  Accordingly, an object of the present invention is to solve the above-mentioned problems, and a method for manufacturing a multilayer wiring board from which a multilayer wiring board excellent in dimensional stability and shape accuracy can be obtained, and a multilayer wiring manufactured by such a method Is to provide a board.

The method for manufacturing a multilayer wiring board according to the present invention is a method for manufacturing a multilayer wiring board having a plurality of wiring layers and connecting the plurality of wiring layers by inner vias. A method for producing a multilayer wiring board includes a step of forming a conductor pattern serving as a wiring layer on a surface of a thermoplastic resin sheet, and a laminate formed by laminating a plurality of resin sheets, the first press plate and the first The graphite sheet is positioned between the two press plates, and has a compressibility and is obtained by pressing expanded graphite at least one of the laminate and the first press plate and the second press plate. A step of disposing a cushion sheet to be formed; and a step of pressing the laminated body in the laminating direction while heating the laminated body between the first press plate and the second press plate. During the step of applying pressure while heating the laminate, the cushion sheet is deformed so that the shape of the conductor pattern is transferred. The step of positioning the laminate and arranging the cushion sheet includes the step of superposing a cushion sheet having a total thickness larger than the total thickness of the laminate in the stacking direction of the plurality of resin sheets on the laminate. The cushion sheet is deformed so as to cover the entire circumference of the laminate during the step of applying pressure while heating the laminate.

According to the method for manufacturing a multilayer wiring board configured as described above, the cushion sheet is deformed so that the shape of the conductor pattern is transferred during the process of heating and pressurizing the laminated body. Instead, the pressure is applied more uniformly to the laminate. Thereby, it can suppress that the resin material which forms a resin sheet flows largely due to the density of a conductor pattern. As a result, it is possible to prevent the conductor pattern from being displaced or deformed during the process of applying pressure while heating the multilayer body, and to obtain a multilayer wiring board excellent in dimensional stability and shape accuracy.
The cushion sheet is formed of a graphite sheet obtained by pressurizing expanded graphite. With such a configuration, it is possible to realize a cushion sheet having both compressibility and high thermal conductivity.
Further, the step of positioning the laminate and arranging the cushion sheet includes the step of superposing a cushion sheet having a total thickness larger than the total thickness of the laminate in the stacking direction of the plurality of resin sheets on the laminate. Including. With such a configuration, the cushion sheet can have a sufficient thickness to be deformed in accordance with the shape of the conductor pattern during the step of applying pressure while heating the laminate.
In addition, the cushion sheet is deformed so as to cover the entire circumference of the laminated body during the step of applying pressure while heating the laminated body. With such a configuration, during the process of applying pressure while heating the resin sheet, the movement of the resin material forming the resin sheet from the peripheral side of the laminate can be regulated by the cushion sheet.

  Preferably, the step of positioning the laminate and disposing the cushion sheet includes a step of disposing a release sheet between the first press plate and the second press plate so as to contact the laminate.

  Preferably, the release sheet is made of polytetrafluoroethylene or polyimide. According to the multilayer wiring board manufacturing method configured as described above, the obtained multilayer wiring board is easily detached from between the first press board and the second press board after the step of applying pressure while heating the resin sheet. be able to.

  Preferably, the cushion sheet is formed of a porous material. According to the method for manufacturing a multilayer wiring board configured as described above, the cushion sheet can be easily deformed during the step of applying pressure while heating the laminate.

Also preferably, positioning the laminate cushion sheet having placing a cushion sheet, the laminated body, an area greater than the area of the laminate when viewed from the stacking direction of the plurality of resin sheets The process of superimposing.

According to the configured method for manufacturing a multilayer wiring board, the time step of pressing while heating the laminate, a sufficient surface product to deform in accordance with the shape of the conductor pattern, be provided to the seat cushion Can do.

  A multilayer wiring board according to the present invention is a multilayer wiring board manufactured by any one of the above-described multilayer wiring board manufacturing methods. The multilayer wiring board includes a resin portion and a plurality of wiring layers embedded in the resin portion. The resin part has a first side surface and a second side surface disposed on the back side of the first side surface. The plurality of wiring layers are stacked in a direction orthogonal to the first side surface and the second side surface. At least one of the first side surface and the second side surface is convex at a position where the plurality of wiring layers are densely arranged when the first side surface and the second side surface are viewed from the front. Concave and convex shapes that are concave at the sparsely arranged positions are formed.

  According to the multilayer wiring board configured as described above, excellent dimensional stability and shape accuracy can be obtained, so that the quality and reliability of the multilayer wiring board can be improved.

  As described above, according to the present invention, there is provided a method for manufacturing a multilayer wiring board from which a multilayer wiring board excellent in dimensional stability and shape accuracy is obtained, and a multilayer wiring board manufactured by such a method. be able to.

It is sectional drawing which shows the multilayer wiring board manufactured by the manufacturing method of the multilayer wiring board in Embodiment 1 of this invention. It is sectional drawing which shows the 1st process of the method of manufacturing the multilayer wiring board in FIG. It is sectional drawing which shows the 2nd process of the method of manufacturing the multilayer wiring board in FIG. It is sectional drawing which shows the 3rd process of the method of manufacturing the multilayer wiring board in FIG. It is sectional drawing which shows the 4th process of the method of manufacturing the multilayer wiring board in FIG. It is a graph which shows the change of the temperature which acts on the temperature of a resin sheet, and a laminated body in the thermocompression bonding process of the method of manufacturing the multilayer wiring board in FIG. It is sectional drawing which shows the 5th process of the method of manufacturing the multilayer wiring board in FIG. It is sectional drawing which shows the 6th process of the method of manufacturing the multilayer wiring board in FIG. It is sectional drawing which expands and shows the range enclosed by the dashed-two dotted line IX in FIG. It is sectional drawing which shows the process of the manufacturing method of the multilayer wiring board in Embodiment 2 of this invention.

  Embodiments of the present invention will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are denoted by the same reference numerals.

(Embodiment 1)
1 is a cross-sectional view showing a multilayer wiring board manufactured by the method for manufacturing a multilayer wiring board according to Embodiment 1 of the present invention. Referring to FIG. 1, multilayer wiring board 10 includes a plurality of wiring layers 30A, 30B, 30C, 30D (hereinafter referred to as wiring layer 30 unless otherwise specified), resin portion 20, and inner via 32. Have.

  The multilayer wiring board 10 has a rectangular parallelepiped shape in which the resin portion 20 makes an appearance. The resin part 20 has a side surface 20a and a side surface 20b disposed on the back side of the side surface 20a. The resin part 20 is formed from an insulating resin. The resin part 20 is formed from a thermoplastic resin. The resin part 20 is made of, for example, polyimide, LCP (liquid crystal polymer), PEEK (polyether ether ketone), or PPS (polyphenylene sulfide).

  The plurality of wiring layers 30 are provided on the surface layer and inside of the resin portion 20. The wiring layer 30 </ b> A is provided so as to be exposed on the side surface 20 a of the resin portion 20. The wiring layer 30B, the wiring layer 30C, and the wiring layer 30D are embedded in the resin portion 20.

  The wiring layers 30 </ b> A, 30 </ b> B, 30 </ b> C, and 30 </ b> D are stacked side by side in a direction indicated by an arrow 101 at intervals (hereinafter, the direction indicated by the arrow 101 is also referred to as the stacking direction of the wiring layer 30). Each of the wiring layers 30A, 30B, 30C, and 30D is formed in a predetermined pattern shape and constitutes an electric circuit. Each of the wiring layers 30 </ b> A, 30 </ b> B, 30 </ b> C, and 30 </ b> D is formed in a plane orthogonal to the stacking direction of the wiring layers 30. An insulating layer made of the resin part 20 is interposed between the wiring layers 30 adjacent to each other.

  The wiring layer 30 is made of a conductive material. The wiring layer 30 is made of a metal such as copper, silver, aluminum, stainless steel, nickel or gold, an alloy containing these metals, or the like.

  The inner via 32 is formed from a conductive material. The inner via 32 is embedded in the resin portion 20. The inner via 32 extends in the stacking direction of the wiring layer 30 inside the resin portion 20. The inner via 32 is provided so as to connect the wiring layers 30A, 30B, 30C, and 30D adjacent to each other. More specifically, the inner via 32 connects the wiring layer 30A and the wiring layer 30B, connects the wiring layer 30B and the wiring layer 30C, and connects the wiring layer 30C and the wiring layer 30D. It is provided to connect.

  The resin part 20 has an uneven shape on at least one of the side surface 20a and the side surface 20b. The uneven shape is formed on the side surface on the side where the cushion sheet is arranged in the thermocompression bonding step of the multilayer wiring board manufacturing method described later, and is formed on the side surface 20a and the side surface 20b in the present embodiment. When the side surface 20a and the side surface 20b are viewed from the front, the uneven shape is convex at positions where the wiring layers 30A, 30B, 30C, 30D are densely arranged, and the wiring layers 30A, 30B, 30C, 30D are sparsely arranged. It is formed to be concave at the position.

  More specifically, the resin part 20 has the convex part 25 which protrudes locally from the side surface 20a and the side surface 20b. The convex portion 25 is formed so as to overlap the position where the wiring layer 30 is disposed when the side surface 20a and the side surface 20b are viewed from the front. The convex portion 25 is formed so as to protrude more greatly at a position where the total thickness of the wiring layers 30A, 30B, 30C, and 30D in the stacking direction is large.

  Then, the manufacturing method of the multilayer wiring board in FIG. 1 is demonstrated. 2 to 5 are cross-sectional views showing the steps of the method of manufacturing the multilayer wiring board in FIG.

  Referring to FIG. 2, first, a plurality of resin sheets 21 are prepared. The resin sheet 21 is formed from a thermoplastic resin, and has a surface 21a and a surface 21b disposed on the back side thereof. The resin sheet 21 has a rectangular shape when the surface 21a and the surface 21b are viewed from the front. That is, the resin sheet 21 has a rectangular plan view. The resin sheet 21 has a size of 6 inches square, for example.

  In the present embodiment, a strip-shaped thermoplastic resin film having a conductor foil 36 formed on the surface 21 a is prepared as the resin sheet 21. An example of the conductor foil 36 is a copper foil having a thickness of 18 μm. The conductor foil 36 preferably has a thickness of 3 μm or more and 40 μm or less so that a circuit can be formed in a subsequent process.

  The surface roughness of the conductor foil 36 on the side in contact with the resin sheet 21 is preferably larger than the surface roughness on the surface opposite to the side in contact with the resin sheet 21. In this case, the bonding strength between the resin sheet 21 and the conductor foil 36 can be increased by the conductor foil 36 biting deeper into the resin sheet 21.

  With reference to FIG. 3, next, a conductor pattern 37 is formed on the surface 21 a of the resin sheet 21. The conductor pattern 37 has a pattern shape corresponding to each layer of the wiring layer 30 in FIG. In the present embodiment, the conductor pattern 37 is formed by patterning the conductor foil 36 using a circuit forming method such as photolithography.

  Next, referring to FIG. 4, a via hole 31 reaching the conductor pattern 37 from the surface 21 b side is formed in the resin sheet 21. At this time, via holes 31 are formed at positions corresponding to the inner vias 32 in FIG. 1 by laser processing using a carbon dioxide gas laser or the like. After perforating the resin sheet 21, smear that is a resin residue is removed.

  Next, the inner via 32 is formed by filling the via hole 31 with a conductive paste as a conductor using a screen printing method or the like. At this time, an appropriate amount of metal powder that forms an alloy layer with the conductor metal that forms the conductor pattern 37 at the bonding temperature may be added to the conductive paste. For example, when the conductor pattern 37 is formed of copper, a combination of at least one of Ag, Cu, and Ni and at least one of Sn, Bi, and Zn is added to the conductive paste.

  Through the above steps, a plurality of resin sheets 21A, 21B, 21C, and 21D on which the conductor pattern 37 and the inner via 32 are formed are obtained.

  A plurality of holes are formed in the peripheral region of the resin sheet 21 by punching, and in the step shown in FIG. 3, the conductor foil 36 is left on the surface 21a so as to include the region where the holes are formed. May be. In this case, a hole formed in the resin sheet 21 is used as a pin insertion hole in a thermocompression bonding process to be described later, thereby preventing positional deviation of the plurality of resin sheets 21.

  Next, referring to FIG. 5, a laminate 121 of a plurality of resin sheets 21, release sheets 41 and 42, and cushion sheets 51 and 52 are arranged between a press plate 61 and a press plate 62.

  At least one of the press plate 61 and the press plate 62 is provided so as to be movable in the stacking direction of the resin sheets 21. The press plates 61 and 62 are formed with an oil passage 63 as a heating means. The oil flow path 63 extends while meandering in a plane orthogonal to the stacking direction of the resin sheets 21, and oil is circulated. The press plates 61 and 62 may be provided with heaters as heating means.

  The laminated body 121 is obtained by laminating a plurality of resin sheets 21A, 21B, 21C, and 21D in one direction. In the present embodiment, a plurality of resin sheets 21 are laminated so that the surfaces 21 a on which the conductor patterns 37 are formed between adjacent resin sheets 21 do not face each other. More specifically, the press plate 61 and the surface 21a of the resin sheet 21A face each other, the surface 21b of the resin sheet 21A and the surface 21a of the resin sheet 21B face each other, and the surface 21b of the resin sheet 21B and the resin sheet A plurality of sheets such that the surface 21a of the 21C faces each other, the surface 21b of the resin sheet 21C and the surface 21a of the resin sheet 21D face each other, and the surface 21b of the resin sheet 21D and the press plate 62 face each other. The resin sheet 21 is laminated.

  The number of the resin sheets 21 to be laminated and the direction in which the resin sheets 21 are laminated are not limited to the numbers and combinations described above, and can be changed as appropriate.

  The release sheets 41 and 42 are provided in contact with the laminate 121 between the press plate 61 and the press plate 62. More specifically, the release sheet 41 is disposed between the laminate 121 and the press plate 61, and the release sheet 42 is disposed between the laminate 121 and the press plate 62.

  The release sheets 41 and 42 have heat resistance, and are formed of a resin material that has good followability to deformation of the resin sheet 21 in the subsequent thermocompression bonding process. In the present embodiment, release sheets 41 and 42 are formed of polytetrafluoroethylene. The release sheets 41 and 42 have a thickness of 25 μm, for example. The release sheets 41 and 42 may be formed of polyimide. The release sheets 41 and 42 are formed of thin sheet members. The release sheets 41 and 42 are for preventing the resin material forming the resin sheet 21 from being bonded to the cushion sheets 51 and 52 during the thermocompression bonding process.

  The cushion sheets 51 and 52 are arranged between at least one of the laminate 121 and the press plate 61 and between the laminate 121 and the press plate 62. In the present embodiment, the cushion sheet 51 is disposed between the laminate 121 and the press plate 61, and the cushion sheet 52 is disposed between the laminate 121 and the press plate 62. More specifically, the cushion sheet 51 is disposed between the release sheet 41 and the press plate 61, and the cushion sheet 52 is disposed between the release sheet 42 and the press plate 62.

The cushion sheets 51 and 52 have compressibility. That is, the cushion sheets 51 and 52 can be deformed when a force is applied in the thickness direction. The cushion sheets 51 and 52 are formed of a porous material. The cushion sheets 51 and 52 are formed of a material having excellent thermal conductivity. In the present embodiment, cushion sheets 51 and 52 are formed of a graphite sheet obtained by pressurizing expanded graphite. The graphite sheet has, for example, a thickness of 2.0 mm and a density of 0.8 g / cm ³ . The cushion sheets 51 and 52 have elasticity that recovers to the original shape to some extent when released from the force applied in the thickness direction.

  The cushion sheets 51 and 52 are formed by a sheet member extending in a plane orthogonal to the stacking direction of the resin sheets 21. The cushion sheets 51 and 52 have greater compressibility than the release sheets 41 and 42. That is, when a force equal to the thickness direction is applied to the cushion sheets 51 and 52 and the release sheets 41 and 42, the cushion sheets 51 and 52 are deformed more greatly than the release sheets 41 and 42.

  The cushion sheets 51 and 52 may be formed of a porous resin film or foam. The cushion sheets 51 and 52 may be formed of a low resilience foam, asbestos, or rock wool.

  In the process shown in FIG. 5, the total thickness of the cushion sheets 51 and 52 is smaller than the total thickness of the laminated body 121. That is, the cushion sheet 51 and the cushion sheet 52 have a thickness of h1 and h2, respectively, and the resin sheet 21A, the resin sheet 21B, the resin sheet 21C, and the resin sheet 21D on which the conductor pattern 37 is formed are respectively H1, When the thicknesses are H2, H3, and H4, the relationship of h1 + h2> H1 + H2 + H3 + H4 is satisfied.

  In the process shown in FIG. 5, the area S <b> 2 of the cushion sheets 51 and 52 when viewed from the stacking direction of the resin sheet 21 is larger than the area S <b> 1 of the stacked body 121 when viewed from the stacking direction of the resin sheet 21.

  In the process shown in FIG. 5, the thickness h1 of the cushion sheet 51 and the thickness h2 of the cushion sheet 52 are larger than the thickness h3 of the release sheet 41 and larger than the thickness h4 of the release sheet 42.

  In this embodiment, the release sheets 41 and 42 are used. However, the release sheet is not necessarily used. That is, when positioning the laminated body 121 between the press plate 61 and the press plate 62, the release sheets 41 and 42 may not be disposed so as to contact the laminated body 121. However, in the thermocompression bonding step to be described later, in order to sufficiently obtain the releasability between the laminate 121 and the cushion sheets 51 and 52 or the releasability between the laminate 121 and the press plates 61 and 62, the laminate 121 is used. When positioning between the press plate 61 and the press plate 62, it is preferable to arrange the release sheets 41 and 42 so as to be in contact with the laminate 121. Further, the release sheet may be disposed only on either the press plate 61 side or the press plate 62 side.

  FIG. 6 is a graph showing changes in the temperature of the resin sheet and the pressure applied to the laminate in the thermocompression bonding step of the method of manufacturing the multilayer wiring board in FIG. 7 and 8 are cross-sectional views showing the steps of the method for manufacturing the multilayer wiring board in FIG. FIG. 9 is an enlarged cross-sectional view of a range surrounded by a two-dot chain line IX in FIG.

  Referring to FIG. 6, next, between the press plate 61 and the press plate 62, the plurality of resin sheets 21 are heated and pressurized in the stacking direction (thermocompression bonding step). In the present embodiment, the thermocompression bonding process is performed by a two-stage process described below.

  6 and 7, first, resin sheet 21 is heated to temperature T1 at which the resin sheet does not soften.

  More specifically, high-temperature oil is circulated through the oil passage 63 in a state where the laminate 121, the release sheets 41 and 42, and the cushion sheets 51 and 52 are sandwiched between the press plate 61 and the press plate 62. . Thereby, the resin sheet 21 is heated to the temperature T1 (time 0 to t1), and is held at the temperature for a certain time (time t1 to t2). By this step, the solvent or bubbles contained in the resin sheet 21 are removed.

  The pressure P1 applied to the laminate 121 in this step is based on the contact pressure between the press plate 61 and the press plate 62, and is a value close to zero.

  Next, referring to FIGS. 6 and 8, the plurality of resin sheets 21 are pressurized while being heated to a temperature T2 higher than the temperature T1. More specifically, the press plate 61 and the press plate 62 are brought close to each other while flowing higher temperature oil through the oil flow path 63. Thereby, the resin sheet 21 is heated to the temperature T2 (time t2 to t3), and is maintained at the temperature for a certain time (time t3 to t4). In the meantime, the pressure P2 is applied to the laminated body 121, and the state is maintained.

  Since the resin sheet 21 is formed of a flexible sheet member, when a plurality of resin sheets 21 are laminated, the surface of the laminated body 121 is pushed by the conductor pattern 37 and becomes a raised shape. More specifically, the surface of the multilayer body 121 is greatly raised at a position where the conductor patterns 37 are densely arranged as viewed from the lamination direction of the resin sheet 21 and is slightly raised at a position where the conductor patterns 37 are sparsely arranged. It becomes a shape.

  In this step, when the pressure P <b> 2 starts to be applied to the laminate 121, the cushion sheets 51 and 52 are deformed according to the surface shape of the laminate 121. That is, the cushion sheets 51 and 52 are deformed so that the shape of the conductor pattern 37 is transferred. As shown in FIG. 9, the cushion sheets 51 and 52 are formed including a large number of gaps 54. The cushion sheets 51 and 52 are deformed when the gap 54 is crushed in the thickness direction of the cushion sheets 51 and 52. At this time, in the positions where the conductor patterns 37 are densely arranged, the crushing margin of the gap 54 is large, and in the positions where the conductor patterns 37 are sparsely arranged, the crushing margin of the gap 54 is small, whereby the cushion sheet 51. , 52 can be freely deformed in accordance with the shape of the conductor pattern 37.

  Furthermore, when the temperature of the resin sheet 21 rises, the resin material forming the resin sheet 21 starts to soften. Accordingly, the resin material forming the resin sheet 21 is integrated with each other between the plurality of resin sheets 21 while including the conductor pattern 37.

  In the present embodiment, since the cushion sheets 51 and 52 are deformed in accordance with the shape of the conductor pattern 37, a force can be applied more uniformly to the laminate 121 during the thermocompression bonding process. Thereby, it can prevent that the resin material which forms the resin sheet 21 flows largely toward the position where the conductor pattern 37 is arrange | positioned densely from the position arrange | positioned loosely.

  Further, by setting the total thickness of the cushion sheets 51 and 52 to be sufficiently larger than the total thickness of the laminated body 121, the cushion sheets 51 and 52 are surrounded by the entire circumference of the laminated body 121 during the thermocompression bonding process. To deform. At this time, a part of the cushion sheets 51 and 52 is disposed on the peripheral side of the laminate 121 as the side portion 53. Thereby, the movement which the resin which forms the resin sheet 21 tends to flow out from the peripheral side of the laminated body 121 can be controlled by the cushion sheets 51 and 52.

  With reference to FIGS. 1 and 6, the low-temperature oil is then circulated through the oil flow path 63 to cool the plurality of thermocompression-bonded resin sheets 21 (time t4 to t5). After cooling, the plurality of thermocompression-bonded resin sheets 21 are removed from between the press plate 61 and the press plate 62. Through the above steps, the multilayer wiring board 10 shown in FIG. 1 is completed.

  The steps of the multilayer wiring board manufacturing method according to Embodiment 1 of the present invention described above will be described together. The multilayer wiring board manufacturing method according to the present embodiment includes a plurality of wiring layers 30, and This is a method for manufacturing a multilayer wiring board in which a plurality of wiring layers 30 are connected by inner vias 32. The method for manufacturing a multilayer wiring board includes a step of forming a conductor pattern 37 to be a wiring layer 30 on a surface 21a of a thermoplastic resin sheet 21, and a laminate 121 formed by laminating a plurality of resin sheets 21. Positioning is performed between a press plate 61 as a first press plate and a press plate 62 as a second press plate, and at least one of the laminate 121 and the press plate 61 and the press plate 62 is compressed. And a step of pressing the laminated body 121 between the press plate 61 and the press plate 62 in the laminating direction. At the time of applying pressure while heating the laminated body 121, the cushion sheets 51 and 52 are deformed so that the shape of the conductor pattern 37 is transferred.

  In addition, the method for manufacturing a multilayer wiring board in the present embodiment is a method for manufacturing a multilayer wiring board having a plurality of wiring layers 30 and connecting between the plurality of wiring layers 30 by an inner via 32. The method for manufacturing a multilayer wiring board includes a step of forming a conductor pattern 37 to be a wiring layer 30 on a surface 21a of a thermoplastic resin sheet 21, and a laminate 121 formed by laminating a plurality of resin sheets 21. Positioning between a press plate 61 as a first press plate and a press plate 62 as a second press plate, and a release sheet 41 as a first sheet for release so as to come into contact with the laminate 121, 42, disposing cushion sheets 51 and 52 as second sheets having compressibility in at least one of the laminate 121 and the press plate 61 and the press plate 62; And pressing the plurality of resin sheets 21 in the laminating direction while heating the plurality of resin sheets 21. In the step of applying pressure while heating a plurality of resin sheets 21, the cushion sheets 51 and 52 are deformed so that the shape of the conductor pattern 37 is transferred.

  According to the multilayer wiring board manufacturing method in Embodiment 1 of the present invention configured as described above, the resin material forming the resin sheet 21 flows due to the density of the conductor pattern 37 during the thermocompression bonding process. This can be suppressed. Thereby, the delamination between the resin sheets 21 and the occurrence of displacement of the wiring layer 30 can be prevented, and the multilayer wiring board 10 excellent in dimensional stability and shape accuracy can be obtained.

  In this embodiment, one set of laminated bodies 121 is disposed between the press plate 61 and the press plate 62, but a plurality of sets of laminated bodies 121 may be stacked while interposing a metal plate such as a stainless steel plate. Good. Thereby, it becomes possible to implement a thermocompression bonding process collectively with respect to multiple sets of laminated bodies 121, and the production efficiency of the multilayer wiring board 10 can be improved.

(Embodiment 2)
FIG. 10 is a cross-sectional view showing steps of a method for manufacturing a multilayer wiring board in accordance with Embodiment 2 of the present invention. FIG. 10 is a diagram corresponding to FIG. 7 in the first embodiment. The method for manufacturing a multilayer wiring board in the present embodiment basically includes the same steps as the method for manufacturing the multilayer wiring board in the first embodiment. Hereinafter, the description of the overlapping steps will not be repeated.

  Referring to FIG. 10, in the present embodiment, cushion sheet 51 is arranged between laminated body 121 and press plate 61, and no cushion sheet is arranged between laminated body 121 and press plate 62. Even in such a process, when the cushion sheet 51 is deformed in accordance with the shape of the conductor pattern 37 during the thermocompression bonding process, a force can be applied to the laminate 121 more uniformly.

  Further, by setting the thickness of the cushion sheet 51 to be sufficiently larger than the total thickness of the laminated body 121, the cushion sheet 51 is deformed so as to surround the laminated body 121 during the thermocompression bonding step. Thereby, the movement which the resin which forms the resin sheet 21 tends to flow out from the peripheral side of the laminated body 121 can be controlled by the cushion sheet 51.

  Referring to FIGS. 1 and 10, in the multilayer wiring board obtained in the present embodiment, a concavo-convex shape is formed on side surface 20a on the side where cushion sheet 51 is disposed, and the side surface on which the cushion sheet is not disposed. Uneven shape is not formed on 20b. When such a multilayer wiring board is mounted on a printed circuit board, for example, the printed circuit board is arranged on the side surface 20a side where the concavo-convex shape is formed, and an electronic component such as an IC positioned at a narrow pitch is excellent in flatness It is preferable to arrange on the side surface 20b side.

  According to the method for manufacturing a multilayer wiring board according to the second embodiment of the present invention configured as described above, the effects described in the first embodiment can be similarly obtained.

  The multilayer wiring board manufacturing method and multilayer wiring board according to the present invention will be described from another aspect as follows.

  The method for manufacturing a multilayer wiring board according to the present invention is a method for manufacturing a multilayer wiring board having a plurality of wiring layers and connecting the plurality of wiring layers by inner vias. A method for producing a multilayer wiring board includes a step of forming a conductor pattern serving as a wiring layer on a surface of a thermoplastic resin sheet, and a laminate formed by laminating a plurality of resin sheets, the first press plate and the first Positioning between the two press plates and disposing a first sheet for release so as to be in contact with the laminate, and at least one of the laminate and the first press plate and the second press plate And a step of arranging a second sheet having compressibility and a step of pressing a plurality of resin sheets in the laminating direction while heating the plurality of resin sheets between the first press plate and the second press plate. In the step of pressing while heating a plurality of resin sheets, the second sheet is deformed so that the shape of the conductor pattern is transferred.

  According to the method of manufacturing a multilayer wiring board configured as described above, the second sheet is deformed so that the shape of the conductor pattern is transferred during the process of applying pressure while heating a plurality of resin sheets. Regardless of the density, the pressure is applied more uniformly to the laminate. Thereby, it can suppress that the resin material which forms a resin sheet flows largely due to the density of a conductor pattern. As a result, it is possible to prevent the displacement and deformation of the conductor pattern during the process of applying pressure while heating a plurality of resin sheets, and to obtain a multilayer wiring board excellent in dimensional stability and shape accuracy.

  Preferably, the second sheet is formed of a porous material. According to the method of manufacturing a multilayer wiring board configured as described above, the second sheet can be easily deformed during the step of applying pressure while heating a plurality of resin sheets.

  Preferably, the second sheet is formed of a graphite sheet obtained by pressurizing expanded graphite. According to the multilayer wiring board manufacturing method configured as described above, a second sheet having both compressibility and high thermal conductivity can be realized.

  Preferably, the step of pressing while heating the plurality of resin sheets is after the step of heating the plurality of resin sheets to the first temperature at which the resin sheet does not soften and the step of heating to the first temperature. And pressurizing the plurality of resin sheets while heating them to a second temperature higher than the first temperature.

  According to the method of manufacturing a multilayer wiring board configured as described above, the solvent, bubbles, and the like contained in the resin sheet are removed from the laminate by heating the plurality of resin sheets to the first temperature. Subsequently, when the step of pressurizing the plurality of resin sheets while heating to the second temperature is started, first, the second sheet is deformed according to the surface shape of the resin sheet on which the shape of the conductor pattern appears. Further, when the temperature of the resin sheet rises, the resin material forming the resin sheet is softened, and the plurality of resin sheets are integrated while including the conductor pattern.

  Preferably, the step of positioning the laminate and arranging the first sheet and the second sheet has a total thickness larger than the total thickness of the laminate in the stacking direction of the plurality of resin sheets with respect to the laminate. A step of superimposing the second sheet. Further preferably, the step of positioning the laminate and arranging the first sheet and the second sheet has an area larger than the area of the laminate when viewed from the lamination direction of the plurality of resin sheets with respect to the laminate. A step of superimposing a second sheet having

  According to the method for manufacturing a multilayer wiring board configured as described above, the thickness or area sufficient to be deformed in accordance with the shape of the conductor pattern in the step of applying pressure while heating a plurality of resin sheets, The sheet can be held.

  Preferably, the second sheet is deformed so as to cover the entire circumference of the laminate in the step of applying pressure while heating the plurality of resin sheets. According to the method for manufacturing a multilayer wiring board configured as described above, the resin material forming the resin sheet is about to flow out from the peripheral side of the laminate by the second sheet during the step of applying pressure while heating the resin sheet. Can regulate movement.

  Preferably, the first sheet is made of polytetrafluoroethylene or polyimide. According to the multilayer wiring board manufacturing method configured as described above, the obtained multilayer wiring board is easily detached from between the first press board and the second press board after the step of applying pressure while heating the resin sheet. be able to.

  A multilayer wiring board according to the present invention is a multilayer wiring board manufactured by any one of the above-described multilayer wiring board manufacturing methods. The multilayer wiring board includes a resin portion and a plurality of wiring layers embedded in the resin portion. The resin part has a first side surface and a second side surface disposed on the back side of the first side surface. The plurality of wiring layers are stacked in a direction orthogonal to the first side surface and the second side surface. At least one of the first side surface and the second side surface is convex at a position where the plurality of wiring layers are densely arranged when the first side surface and the second side surface are viewed from the front. Concave and convex shapes that are concave at the sparsely arranged positions are formed.

  According to the multilayer wiring board configured as described above, excellent dimensional stability and shape accuracy can be obtained, so that the quality and reliability of the multilayer wiring board can be improved.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention is mainly used for manufacturing a multilayer wiring board having a plurality of wiring layers embedded in a resin.

  10 multilayer wiring board, 20a, 20b side surface, 20 resin part, 21, 21A, 21B, 21C, 21D resin sheet, 21a, 21b surface, 25 convex part, 30, 30A, 30B, 30C, 30D wiring layer, 31 via hole, 32 inner via, 36 conductor foil, 37 conductor pattern, 41, 42 release sheet, 51, 52 cushion sheet, 54 gap, 61, 62 press plate, 63 oil flow path, 121 laminate.

Claims (5)

A method of manufacturing a multilayer wiring board having a plurality of wiring layers, wherein the plurality of wiring layers are connected by inner vias,
Forming a conductive pattern to be the wiring layer on the surface of the thermoplastic resin sheet;
A laminate formed by laminating a plurality of the resin sheets is positioned between the first press plate and the second press plate, and between the laminate, the first press plate and the second press plate. A step of placing a cushion sheet formed of a graphite sheet having compressibility and obtained by pressurizing expanded graphite in at least one of
A step of applying pressure in the laminating direction while heating the laminated body between the first press plate and the second press plate,
During the step of applying pressure while heating the laminate, the cushion sheet is deformed so that the shape of the conductor pattern is transferred ,
The step of positioning the laminated body and arranging the cushion sheet is performed by overlapping the cushion sheet having a total thickness larger than the total thickness of the laminated body in the stacking direction of the plurality of resin sheets on the laminated body. Including the step of combining,
The method for manufacturing a multilayer wiring board , wherein the cushion sheet is deformed so as to cover the entire circumference of the laminate when the laminate is heated and pressed .   The step of positioning the laminate and disposing the cushion sheet includes a step of disposing a release sheet between the first press plate and the second press plate so as to contact the laminate. The manufacturing method of the multilayer wiring board of Claim 1.   The method for manufacturing a multilayer wiring board according to claim 2, wherein the release sheet is formed of polytetrafluoroethylene or polyimide.   The said cushion sheet is a manufacturing method of the multilayer wiring board of any one of Claim 1 to 3 formed with a porous material. The step of positioning the laminated body and disposing the cushion sheet includes the cushion sheet having an area larger than an area of the laminated body when viewed from a lamination direction of the plurality of resin sheets with respect to the laminated body. The manufacturing method of the multilayer wiring board of any one of Claim 1 to 4 including the process of superimposing.

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