JP2008172030A - Method of manufacturing multilayer circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a multilayer circuit board which can cause less deformation in a conductor pattern or less mutual positional displacement therein, and can suppress an increase in the resistance of a conductive material for interlayer connection, with a high reliability. <P>SOLUTION: When a laminate 20 of n resin films 10a to 10g is viewed from a compressing direction by thermal pressing plates 80, and when a conductor presence rate (%) as a rate of overlap between conductor patterns 2 of layers is defined as (m/n)×100 (m: the number of overlapped layers of the conductor patterns 2 at an arbitrary position, or an integer from 0 to n); such a pressing pressure correcting sheet 40 having a projection 42 formed thereon is prepared to be associated with a low conductor presence rate region 30 having a conductor presence rate smaller than the maximum conductor presence rate of the laminate 20 in a pressing plane, the sheet 40 is positioned so that the projection 42 is opposed to the low conductor presence rate region 30, and compression is carried out with the pressing pressure correcting sheet 40 disposed between the thermal pressing plate 80 and the laminate 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In the present invention, a plurality of resin films made of a thermoplastic resin on which a conductor pattern made of a metal foil is formed are laminated while being positioned, and the laminate is heated and pressed to bond the resin films to each other. The present invention relates to a method for manufacturing a multilayer circuit board.

  A method for producing a multilayer circuit board in which a plurality of resin films made of a thermoplastic resin having a conductor pattern made of metal foil is laminated, and the laminate is heated and pressurized to bond the resin films to each other. Are known. In this method of manufacturing a multilayer circuit board, a plurality of resin films are bonded together, so that the multilayer circuit board can be manufactured at low cost.

  Further, a press method for heating and pressurizing in the above-described multilayer circuit board manufacturing method is disclosed in, for example, Japanese Patent Application Laid-Open No. 2003-273511 (Patent Document 1).

In the press method disclosed in Patent Document 1, a pressing member (buffer material) having a buffering effect is interposed between a laminated body of a resin film on which a hot press plate and a conductor pattern are formed during heating and pressurization. . Accordingly, it is possible to cancel the thickness distribution of the multilayer body due to the presence of the conductor pattern and apply a uniform pressure to the whole. For this reason, the mutual position shift of the conductor pattern currently formed in each resin film can be suppressed, and a product yield can be raised.
JP 2003-273511 A

  In the production of multilayer circuit boards, in recent years, the thickness distribution of the laminate due to the presence of the conductor pattern tends to increase with the increase in the number of laminated resin films, and the thickness distribution cannot be covered only with the cushioning material. ing. For example, in the case of manufacturing a multilayer circuit board by laminating 25 resin films having conductor patterns formed using 12 μm copper foil, a thickness distribution of 12 × 25 = 300 μm at the maximum at each position of the laminate. Occurs. For this reason, if there is a region in which the conductor pattern of each layer overlaps greatly in the pressing surface of the laminate, the press pressure cannot be applied uniformly, and the conductor pattern may be deformed or misaligned. As a result, the resistance of the conductive material connecting the conductor patterns between the layers increases, and the reliability of the multilayer circuit board decreases.

  In view of this, the present invention laminates a plurality of resin films made of thermoplastic resin on which a conductor pattern made of metal foil is formed, and bonds the resin films to each other by heating and pressurizing the laminate. A method for manufacturing a multilayer circuit board, in which deformation of a conductor pattern and mutual positional deviation are unlikely to occur, and it is possible to suppress an increase in resistance of a conductive material connecting the conductor patterns of each layer between layers, and to have high reliability. It aims at providing the manufacturing method of a board | substrate.

  In the invention according to claim 1, n (n is a plurality) resin films made of a thermoplastic resin on which a conductive pattern made of a metal foil is formed are laminated while being positioned, and the n pieces of the positioned n films are laminated. A method for producing a multilayer circuit board in which a resin film laminate is pressed while being heated by a hot press plate to bond the resin films to each other, wherein the laminate is viewed from the direction of pressurization by the hot press plate. When seen through, the conductor abundance ratio [%], which is the ratio at which the conductor patterns of each layer overlap at an arbitrary position in the pressing surface of the laminate, is (m / n) × 100, where m is an arbitrary position. The number of overlapping layers of conductor patterns, which is an integer from 0 to n), a low conductor abundance region having a conductor abundance smaller than the maximum conductor abundance in the pressure surface within the pressure surface of the laminate. In Correspondingly, a press pressure correction sheet having a convex portion with a predetermined thickness is prepared, and when the heat press plate is heated and pressed, the low conductor existence ratio region and the convex portion are opposed to each other. And pressurizing with the press pressure correcting sheet interposed between the hot press plate and the laminate.

  In the method for manufacturing a multilayer circuit board, a convex portion having a predetermined thickness is provided so as to face the low conductor abundance ratio region in a low conductor abundance ratio area having a relatively low conductor abundance ratio in the pressing surface of the laminate. A press pressure correction sheet formed with a portion is interposed between the hot press plate and the laminate, and is pressed under pressure while heating. As a result, when the pressure applied by the hot press plate is low, the applied pressure is less likely to be transmitted than the surrounding area due to the low conductor existing rate. Can compensate for the shortage. Therefore, compared with the case where no press pressure correction sheet is interposed during heating and pressurization, the applied pressure in the pressurization surface of the laminate can be made uniform. For this reason, the non-uniform flow of the resin plasticized by heat can be suppressed, and deformation of the conductor pattern and mutual displacement can be suppressed. In addition, a uniform and sufficient pressure can be applied to the conductive material for connecting the conductive patterns of the respective layers to each other, and an increase in resistance of the conductive material in the low conductor existence ratio region can be suppressed.

  As described above, in the method for manufacturing a multilayer circuit board, a plurality of resin films made of a thermoplastic resin on which a conductor pattern made of a metal foil is formed are laminated while being positioned, and the laminate is heated and pressurized. This is a method for manufacturing a multilayer circuit board in which resin films are bonded to each other, and it is difficult for deformation of the conductor patterns and mutual positional deviation to occur, and to suppress an increase in resistance of the conductive material connecting the conductor patterns of each layer to each other. Thus, a method for manufacturing a multilayer circuit board having high reliability can be obtained.

  According to a second aspect of the present invention, it is preferable that the conductor abundance ratio is calculated and calculated from a drawing of a conductor pattern in the n resin films by CAD (Computer Aided Design). According to this, even if it is a multilayer circuit board in which a complicated conductor pattern is formed over each layer, the conductor presence rate can be calculated accurately and easily.

  According to a third aspect of the present invention, the press pressure correction sheet is preferably made of a resin sheet on which a metal pattern corresponding to the convex portion is formed. In this case, even if the low conductor existence ratio region has a complicated pattern shape, the corresponding convex portion of the press pressure correction sheet can be easily formed as a metal pattern by etching.

  In this case, for example, as described in claim 4, the metal pattern may be made of the metal foil. According to this, since the metal pattern corresponding to the convex part of the press pressure correction sheet is composed of a metal foil made of the same material as the conductor pattern of the resin film, it is easier to stack compared to the case of using other materials. The applied pressure in the pressing surface of the body can be made uniform.

  In this case, for example, as described in claim 5, a plurality of the press pressure correction sheets are interposed between the hot press plate and the laminate to pressurize the low conductor existence ratio region. It is possible to make up for a necessary shortage with respect to around the applied pressure at.

  Furthermore, in this case, the maximum overlapping layer number of conductor patterns in the low conductor abundance region, the hot press plate, and the hot press plate, as described in claim 6, so as not to overcorrect the applied pressure in the low conductor abundance region It is preferable that the sum of the number of the press pressure correction sheets interposed between the laminates is set to be smaller than the maximum number of layers of conductor patterns overlapping in the pressing surface of the laminate.

  In the method for manufacturing the multilayer circuit board, as described in claim 7, it is preferable to dispose a buffer member between the press pressure correction sheet and the hot press plate. By using the press pressure correction sheet and the buffer member in combination, the uniformity of the applied pressure in the pressing surface of the laminate can be further increased.

  In the present invention, n (n is a plurality) resin films made of a thermoplastic resin on which a conductive pattern made of a metal foil is formed are laminated while being positioned, and a laminate of the positioned n resin films. It is related with the manufacturing method of the multilayer circuit board which adheres the said resin films mutually by pressing while heating with a hot press board.

In the present invention, when the laminated body is seen through from the pressing direction of the hot press plate, the conductor existence ratio [%], which is a ratio in which the conductor pattern of each layer overlaps at an arbitrary position in the pressing surface of the laminated body. ,
(M / n) × 100, (m is the number of overlapping layers of conductor patterns at an arbitrary position, an integer from 0 to n),
In the pressurization surface of the laminate, the low conductor abundance region is opposed to the low conductor abundance region corresponding to the low conductor abundance region that is smaller than the maximum conductor abundance in the pressurization surface. A press pressure correction sheet having convex portions having a predetermined thickness is prepared, and when the heat press plate is heated and pressed, the low conductor existence ratio region and the convex portions are positioned, The pressing is performed with the press pressure correction sheet interposed between the plate and the laminate.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram for explaining the conductor abundance ratio, and shows a state in which seven resin films 10a to 10g made of a thermoplastic resin 1 on which a conductor pattern 2 made of metal foil is formed are positioned and laminated. 2 is a schematic cross-sectional view of a stacked body 20. Reference numeral 3 in FIG. 1 is a conductive paste, which is sintered at the same time as the bonding of the resin films 10a to 10g by heating and pressurization, and the conductive material 3a in FIG. Become. Moreover, the white arrow has shown the pressurization direction.

  In the following description, the lamination of seven resin films 10a to 10g is taken as an example, but the number of laminations of the resin film is not limited to this, and may be an arbitrary plural lamination. In the production of multilayer circuit boards in recent years, the number of laminated resin films tends to increase, and multilayer circuit boards having 20 or more laminated resin films have been produced.

  In the position of the alternate long and short dash line A in the laminate 20 of FIG. 1, the conductor patterns 2 of the seven resin films 10 a to 10 g are all overlapped, and the number of overlapping layers of the conductor patterns 2 is seven. Accordingly, the conductor existence ratio [%] is (7/7) × 100 = 100 [%]. At the position of the two-dot chain line B in the laminate 20, the conductor patterns 2 of the five resin films 10a to 10e are overlapped, and the number of overlapping layers of the conductor patterns 2 is five. Therefore, the conductor existence ratio [%] is (5/7) × 100 = 71 [%]. In FIG. 1, the region indicated by reference numeral 30 has a conductor abundance ratio (71 [%] or less) smaller than the maximum conductor abundance ratio (100 [%]) in the pressure surface in the pressure surface of the laminate 20. Corresponds to the low conductor abundance region.

  FIG. 2 is a diagram showing the distribution of the above-described conductor existence ratio in the pressurization surface in a shaded manner with respect to the laminate 20a of the multilayer circuit board actually manufactured.

  The distribution of conductor abundance shown in FIG. 2 is obtained by calculation from a drawing of conductor patterns in 24 resin films by CAD (Computer Aided Design). As described above, by using a conductor pattern drawing by CAD, the conductor existence ratio can be calculated accurately and easily even in a multilayer circuit board in which a complicated conductor pattern is formed over each layer.

  FIG. 3 is a schematic cross-sectional view showing the positional relationship of each member when the laminate 20 of FIG. 1 is heated and pressed by the hot press plate 80. FIG. 4 is a schematic cross-sectional view showing a state of heating and pressurizing the laminate 20. A black arrow indicates an applied pressure. FIG. 5 is a schematic cross-sectional view of the finally manufactured multilayer circuit board 100.

  In the heating and pressurizing process of the laminate 20 shown in FIGS. 3 and 4, a press pressure correction sheet 40 is prepared, and the press pressure correction sheet 40 is interposed between the hot press plate 80 and the laminate 20, Heat and pressurize.

  The press pressure correction sheet 40 is a sheet in which a convex portion 42 having a predetermined thickness is formed corresponding to the above-described low conductor existence ratio region 30 in the pressing surface of the laminate 20. In the press pressure correction sheet 40 shown in FIG. 3, convex portions 42 are formed on the surface of the resin sheet 41 in a metal pattern. The press pressure correction sheet 40 may have another configuration as long as the convex portion 42 having a predetermined thickness corresponding to the low conductor existence ratio region 30 is formed. Even when the conductor abundance ratio region 30 has a complicated pattern shape, the corresponding protrusion 42 of the press pressure correction sheet 40 can be easily formed as a metal pattern by etching.

  As shown in the arrangement relationship of FIG. 3, when the laminated body 20 is heated and pressed by the hot press plate 80, the low conductor existence ratio region 30 of the laminated body 20 and the convex portion 42 of the press pressure correcting sheet 40 are roughly positioned. Thus, the press pressure correction sheet 40 is interposed between the hot press plate 80 and the laminate 20. In the arrangement of FIG. 3, release films 50, 60 and 70 are arranged between the hot press plate 80, the laminate 20 and the press pressure correction sheet 40, respectively. Reference numeral 90 denotes a buffer member made of a fibrous metal molded body.

In the heating / pressurizing step shown in FIG. 4, the low conductor abundance ratio region 30 of the positioned laminated body 20 and the convex portion 42 of the press pressure correction sheet 40 are opposed to each other and pressed with heating. Thus, the thermoplastic resins 1 of the resin films 10a to 10g shown in FIG. 3 are bonded to each other, and the conductive paste 3 is sintered to become the conductive material 3a shown in FIG. Also,
In the heating / pressurizing step shown in FIG. 4, the press pressure correction sheet is applied to the low conductor abundance ratio region 30 in which the applied pressure is difficult to be transmitted compared to the surroundings because the conductor abundance ratio is low when pressed by the hot press plate 80. Forty convex portions 42 can compensate for the shortage with respect to the applied pressure. Therefore, compared with the case where the press pressure correction sheet 40 is not interposed at the time of heating and pressing, the applied pressure in the pressing surface of the laminate 20 can be made uniform. For this reason, the nonuniform flow of the resin 1 plasticized by heat can be suppressed, and deformation of the conductor pattern 2 and mutual positional deviation can be suppressed. Further, uniform and sufficient pressure can be applied to the conductive material 3a (conductive paste 3) for connecting the conductive patterns 2 of each layer to each other, and the resistance of the conductive material 3a in the low conductor existence region 30 is increased. Can be suppressed.

  As described above, the multilayer circuit board 100 shown in FIG. 5 is manufactured. A concave portion 142 corresponding to the convex portion 42 of the press pressure correction sheet 40 is formed on the surface of the multilayer circuit board 100 manufactured by the above method.

  In the method of manufacturing the multilayer circuit board 100, it is preferable to dispose the buffer member 90 between the press pressure correction sheet 40 and the hot press plate 80 as shown in FIGS. By using the press pressure correction sheet 40 and the buffer member 90 in combination, the uniformity of the applied pressure in the pressing surface of the laminate 20 can be further increased.

  FIG. 6 is an example of a press pressure correction sheet used at the time of heating / pressing the laminate 20a shown in FIG. 2, and is a plan view showing the pattern shape of the convex portions 42a of the press pressure correction sheet 40a. A press pressure correction sheet 40a shown in FIG. 6 is obtained by forming a convex portion 42a painted black on the surface of a resin sheet 41 with a metal pattern. The convex portions 42a in FIG. 6 are arranged corresponding to the low conductor existence ratio regions shown lightly in the stacked body 20a in FIG. As shown in FIG. 6, even if the convex portion 42a has a complicated pattern shape, it can be easily formed as a metal pattern by etching.

  The metal pattern of the convex portions 42 and 42a of the press pressure correction sheets 40 and 40a shown in FIGS. 3 and 6 may be made of the same metal foil as the conductor pattern 2 of the resin films 10a to 10g shown in FIG. . In this case, in the arrangement relationship shown in FIG. 3, the metal pattern corresponding to the convex portion 42 of the press pressure correction sheet 40 is composed of a metal foil made of the same material as the conductor pattern 2 of the resin films 10a to 10g. Compared with the case where other materials are used, in the heating / pressing step shown in FIG. 4, the applied pressure in the pressing surface of the laminate 20 can be made uniform more easily.

  Moreover, when the convex part 42 of the press pressure correction sheet 40 is formed of the same metal foil as the conductor pattern 2 of the resin films 10a to 10g as described above, the press pressure correction sheet 40 is used in the steps of FIGS. By interposing and pressing a plurality of sheets between the hot press plate 80 and the laminated body 20, a necessary shortage with respect to the applied pressure around the low conductor existence ratio region 30 can be compensated. Further, in this case, in order not to over-correct the applied pressure in the low conductor abundance region 30, the maximum number of overlapping layers of the conductor pattern 2 in the low conductor abundance region 30 and between the hot press plate 80 and the laminate 20 are not. The sum of the number of intervening press pressure correction sheets 40 is preferably set to be smaller than the maximum number of overlapping layers of the conductor pattern 2 in the pressing surface of the laminate 20.

  Next, when the convex part of the press pressure correction sheet is formed of the same metal foil as the conductor pattern of the resin film, and a plurality of press pressure correction sheets are interposed between the hot press plate and the laminate and heated and pressed. The characteristics of the manufactured multilayer circuit board will be described.

  FIG. 7 shows the relationship between the number of the press pressure correction sheets 40 used in the heating / pressurizing step (FIG. 4) of the manufacturing method described above and the depth of the recess 142 formed in the manufactured multilayer circuit board 100. FIG. In the heating / pressurizing step, the difference in thickness between the position A and the position B shown in FIG. 1 in the laminate 20 before heating / pressurizing was about 100 μm.

  As shown in FIG. 7, when the number of press pressure correction sheets 40 is zero, that is, in the previous heating / pressing step, the press is performed on the laminate 20 without using the press pressure correction sheet 40. When pressure was applied from the plate 80, the depth of the recess formed in the manufactured multilayer circuit board was 46 μm. In this case, since the press pressure correction sheet 40 is not used, the concave portion 142 is basically not formed on the back surface of the multilayer circuit board 100. Therefore, the lower surface of the laminate 20 is compressed by 46% as a whole, and a multilayer circuit board having a thickness of 54 μm is manufactured. Further, when the number of press pressure correction sheets is one or two, that is, when the pressure applied to the low conductor existence ratio region 30 is increased by using one or two press pressure correction sheets 40, The depths of the recesses 142 formed in the low conductor existence ratio region 30 were 51 μm and 54.5 μm, respectively. In either case, since the deeper concave portion 142 is formed than when the press pressure correction sheet 40 is not used, the pressure applied to this portion is increased by the press pressure correction sheet 40. Furthermore, the greater the number of press pressure correction sheets 40, the higher the effect of increasing the pressure applied to the low conductor existence ratio region 30.

  Thus, when the pressure applied to the low conductor abundance region 30 is increased, the Vickers hardness of the conductive material 3 a in the low conductor abundance region 30 is also improved.

  FIG. 8 shows the number of press pressure correction sheets 40 used in the heating / pressurizing step (FIG. 4) of the manufacturing method described above, and the conductive material 3a in the low conductor existence region 30 of the manufactured multilayer circuit base. It is a figure which shows the relationship with no Vickers hardness.

  As shown in FIG. 8, when the number of press pressure correction sheets 40 is zero, the Vickers hardness of the conductive material 3a in the low conductor existence ratio region 30 of the manufactured multilayer circuit board 100 is 110 to 155 HV. It was. When the number of press pressure correction sheets was one or two, the Vickers hardness of the conductive material 3a in the low conductor abundance ratio region 30 was 130 to 175 HV and 145 to 205 HV, respectively. In any case, the Vickers hardness of the conductive material 3a in the low conductor existence ratio region 30 is increased as compared with the case where the press pressure correction sheet 40 is not used.

  The increase in the Vickers hardness in this way means that a sufficiently large pressure has been applied to the conductor paste 3 which is a material for forming the conductive material 3 a in the low conductor existence ratio region 30. That is, if a sufficiently large pressure is applied to the conductor paste 3, the metal particles of the conductor paste 3 are strongly bonded to each other, and the Vickers hardness of the conductive material 3a in the low conductor existence ratio region 30 is increased. At the same time, the electrical resistance value also decreases.

  FIG. 9 shows the state of the conductive material 3a in the low conductor abundance region 30 of the multilayer circuit board 100, depending on the number of the press pressure correction sheets 40 used in the heating / pressurizing step (FIG. 4) of the manufacturing method described above. It is a figure which shows the increase aspect of the electrical resistance value by an electricity test. In this energization test, the fluctuation range of the electric resistance value after the temperature of the multilayer circuit board is changed 1000 times from low temperature to high temperature in the range of −55 ° C. to 125 ° C. is measured.

  As shown in FIG. 9, when the number of the press pressure correction sheets 40 is zero, the electric resistance value of the conductive material 3a in the low conductor existence ratio region 30 has a fluctuation range of 0.01Ω to 0.30Ω. Settled. The conductive material 3a at this time is formed without applying a sufficiently large pressure to the conductive paste 3 because the press pressure correction sheet 40 is not used in the previous heating / pressurizing step. Therefore, since the metal particles constituting the conductive material 3a are not strongly bonded, it is considered that the fluctuation range of the electric resistance value of the conductive material 3a is increased by repeating the temperature change. When a sample with a large variation in electrical resistance value was examined, there was a crack in the conductive material 3a. That is, it is considered that the electric resistance value of the conductive material 3a is changed due to the occurrence of such cracks. Further, when the pressure applied to the low conductor abundance region 30 is increased by using one or two press pressure correction sheets 40, the electric resistance value of the conductive material 3a formed in the low conductor abundance region 30 Were within the fluctuation ranges of 0.01 to 0.15Ω and 0.01 to 0.02Ω, respectively. The conductive material 3a at this time is formed by applying a sufficiently large pressure to the conductive paste 3 because the press pressure correction sheet 40 is used in the previous heating / pressurizing step. Therefore, even if the metal particles constituting the conductive material 3a are strongly bonded and the temperature change is repeated, the conductive material 3a is hardly cracked due to the difference in thermal expansion coefficient. That is, there is little variation in the electric resistance value of the conductive material 3a. Therefore, the fluctuation range of the electric resistance value of the conductive material 3a is small.

  As described above, in the above-described method for manufacturing a multilayer circuit board, a plurality of resin films made of thermoplastic resin on which a conductor pattern made of metal foil is formed are stacked while being positioned, and the laminate is heated and heated. This is a method of manufacturing a multilayer circuit board in which resin films are bonded to each other by pressing, so that deformation of the conductor pattern and mutual displacement are unlikely to occur, and an increase in resistance of the conductive material connecting the conductor patterns of each layer is suppressed. This is a method for manufacturing a multilayer circuit board having high reliability.

In the figure for explaining the conductor abundance ratio, a laminate 20 showing a state in which the seven resin films 10a to 10g made of the thermoplastic resin 1 on which the conductor pattern 2 made of metal foil is formed are positioned and laminated. FIG. It is the figure which imaged and showed distribution of the conductor presence rate in the pressurization surface about the laminated body 20a of the multilayer circuit board actually manufactured. 5 is a schematic cross-sectional view showing the arrangement relationship of each member when the laminated body 20 is heated and pressed by a hot press plate 80. FIG. FIG. 3 is a schematic cross-sectional view showing a state of heating and pressurizing a laminated body 20. 1 is a schematic cross-sectional view of a finally manufactured multilayer circuit board 100. FIG. It is an example of the press pressure correction sheet used at the time of heating and pressurizing the laminated body 20a shown in FIG. 2, and is a plan view showing the pattern shape of the convex portions 42a of the press pressure correction sheet 40a. FIG. 5 is a diagram showing the relationship between the number of press pressure correction sheets 40 used in the heating / pressurizing step of FIG. 4 and the depth of a recess 142 formed in the manufactured multilayer circuit board 100. FIG. 5 is a diagram showing the relationship between the number of press pressure correction sheets 40 used in the heating / pressurizing step of FIG. 4 and the Vickers hardness of the conductive material 3a in the low conductor existence ratio region 30 of the manufactured multilayer circuit base. is there. In addition to the number of press pressure correction sheets 40 used in the heating / pressurizing step of FIG. 4, an increase in the electric resistance value by an energization test of the conductive material 3 a in the low conductor existence ratio region 30 of the multilayer circuit board 100 is shown. FIG.

Explanation of symbols

10a to 10g Resin film 1 Thermoplastic resin 2 Conductive pattern 3 Conductive paste 3a Conductive material 20, 20a Laminate 30 Low conductor abundance area 40, 40a Press pressure correction sheet 41 Resin sheet 42, 42a Protrusion 50, 60, 70 Separation Mold film 80 Hot press plate 90 Buffer member 100 Multilayer circuit board 142 Recess

Claims (7)

Laminating while positioning n (n is a plurality) resin films made of thermoplastic resin in which a conductor pattern made of metal foil is formed,
A method of manufacturing a multilayer circuit board in which the resin films are bonded to each other by applying pressure while heating the laminated body of the n resin films positioned by a hot press plate,
When the laminate is seen through from the pressing direction of the hot press plate, the conductor abundance ratio [%], which is the ratio of the conductor patterns of each layer overlapping at an arbitrary position in the pressing surface of the laminate,
(M / n) × 100, (m is the number of overlapping layers of conductor patterns at an arbitrary position, an integer from 0 to n),
When defined in
A press pressure correction sheet in which a convex portion having a predetermined thickness is formed in a pressurizing surface of the laminate, corresponding to a low conductor existing rate region having a conductor existing rate smaller than the maximum conductor existing rate in the pressurizing surface. Prepare
When heating and pressurizing with the hot press plate, the low conductor existence ratio region and the convex portion are positioned so as to face each other, and the press pressure correction sheet is interposed between the hot press plate and the laminate. A method for producing a multilayer circuit board, wherein pressurization is performed.   2. The method of manufacturing a multilayer circuit board according to claim 1, wherein the conductor abundance ratio is calculated from a drawing of a conductor pattern in the n resin films by CAD (Computer Aided Design).   The method for manufacturing a multilayer circuit board according to claim 1, wherein the press pressure correction sheet is made of a resin sheet on which a metal pattern corresponding to the convex portion is formed.   The method for manufacturing a multilayer circuit board according to claim 3, wherein the metal pattern is made of the metal foil.   5. The method of manufacturing a multilayer circuit board according to claim 4, wherein a plurality of the press pressure correction sheets are interposed between the hot press plate and the laminated body and pressed.   The sum of the maximum number of overlapping conductor patterns in the low conductor abundance region and the number of press pressure correction sheets interposed between the hot press plate and the laminate is the conductor pattern in the pressing surface of the laminate. 6. The method for manufacturing a multilayer circuit board according to claim 5, wherein the number of overlapping layers is set smaller than the maximum number of layers.   The method for manufacturing a multilayer circuit board according to claim 1, wherein a buffer member is disposed between the press pressure correction sheet and the hot press plate.

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