JP2012174772A - Manufacturing method of multilayer printed board, multilayer printed board and coating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of multilayer printed board in which formation of pinholes or bubbles can be suppressed in a resin-impregnated sheet.SOLUTION: The manufacturing method of multilayer printed board includes a first coating step for forming a solution layer (32a) by coating with a solution (32) a glass cloth (24) which is to be conveyed in a state of being superimposed with a carrier film (30), a second coating step for forming a resin-impregnated sheet (26) where the glass cloth is impregnated with a resin paste (22) by coating the glass cloth, on which the solution layer is formed, with the resin paste, and a drying step for drying the resin-impregnated sheet.

Description

  The present invention relates to a method for manufacturing a multilayer printed board that is manufactured by applying a resin to a glass cloth, a multilayer printed board, and a coating apparatus.

  As a manufacturing method of a multilayer printed board used as a heat dissipation board or a circuit board in an electronic device or the like, after producing a resin-impregnated sheet obtained by applying a resin to a glass cloth and drying it, the sheet, A method of laminating is known. In addition, a method for producing a resin-impregnated sheet by immersing a glass cloth in a resin tank and then passing it through a drying furnace (see Patent Document 1 and Patent Document 2) is known.

Japanese Patent Laid-Open No. 7-307568 JP-A-8-150683

  However, in the method for manufacturing a multilayer printed circuit board according to the prior art, there are problems that holes (pinholes) are formed in the resin-impregnated sheet or bubbles are formed in the resin-impregnated sheet. The pinhole formed in the resin-impregnated sheet reduces the smoothness of the resin-impregnated sheet surface. In addition, bubbles in the resin-impregnated sheet may be repelled when the sheet is heated, thereby reducing the smoothness of the surface of the resin-impregnated sheet.

  The present invention is made in view of such a situation, and a method for manufacturing a multilayer printed board capable of suppressing the formation of pinholes and bubbles in a resin-impregnated sheet, a multilayer printed board manufactured by the manufacturing method, and the manufacturing method The present invention relates to a coating apparatus used.

In order to achieve the above object, a method for producing a multilayer printed board according to the present invention comprises:
A first application step of forming a solution layer by applying a solution to a glass cloth that is superimposed and conveyed with a carrier film;
A second application step of applying a resin paste on the glass cloth over the solution layer, and forming a resin-impregnated sheet impregnated with the resin paste on the glass cloth; and a drying step of drying the resin-impregnated sheet; It is characterized by having.

  In the manufacturing method according to the present invention, before applying the resin paste, a solution is applied to a glass cloth to form a solution layer, and the resin paste is applied over the solution layer. Thereby, in the manufacturing method according to the present invention, the resin paste applied to the glass cloth is easily impregnated into the glass cloth by being diluted with the solvent of the solution layer in the vicinity of the surface of the glass cloth. Therefore, according to the manufacturing method according to the present invention, the resin paste easily penetrates into the glass cloth and prevents the formation of holes (pinholes) in the resin-impregnated sheet or the formation of bubbles in the resin-impregnated sheet. it can. According to the production method of the present invention, it is possible to improve the smoothness of the surface of the resin-impregnated sheet, and it is possible to suppress an increase in the defective rate due to the formation of pinholes and bubbles, thereby contributing to an improvement in production yield.

  Further, for example, the second application step may be performed within one minute after the first application step is performed.

  By performing the second coating step within one minute after the first coating step is performed, the solvent contained in the solution layer is reduced or eliminated between the formation of the solution layer and the application of the resin paste. Can be prevented. Therefore, such a manufacturing method can make the solvent of a solution layer and resin paste act more effectively in the glass cloth surface vicinity. Moreover, the effect | action which becomes easy to osmose | permeate a resin paste by glass cloth by this can be show | played more effectively.

  For example, the viscosity of the solution may be 0.1 Pa · s or less, and the viscosity of the resin paste may be 2.0 to 5.0 Pa · s.

  The viscosity of the resin paste according to the present invention is not particularly limited, but is preferably 2.0 to 5.0 Pa · s. A resin paste having a viscosity of 2.0 Pa · s or more is suitable as a resin paste used in the second coating step because separation of the solute and the solvent accompanying sedimentation of the filler is suppressed. Further, according to the production method of the present invention, it is possible to suitably prevent formation of bubbles or the like in the resin-impregnated sheet even when the resin viscosity is as high as 2.0 Pa · s or higher. In particular, in the range where the resin viscosity is 5.0 Pa · s or less, formation of bubbles or the like in the resin-impregnated sheet can be more suitably prevented. Moreover, the effect | action which becomes easy to osmose | permeate a glass cloth by making the viscosity of a solution 0.1 Pa * s or less can be obtained more effectively.

  For example, the resin paste may contain the same solvent component as the solution applied to the glass cloth in the first application step.

  By making the resin paste contain the same solvent component as the solution applied in the first application step, the resin paste applied over the solution layer is preferably diluted with the solvent contained in the solution layer. Is done. Therefore, according to such a manufacturing method, the effect | action which a resin paste becomes easy to osmose | permeate a glass cloth can be show | played more effectively.

The coating apparatus according to the present invention includes a transport unit that transports a carrier film and a glass cloth in an overlapping manner, and
A first application part that forms a solution layer by applying a solution to the glass cloth that is superimposed and conveyed with the carrier film;
And a second application part that forms a resin-impregnated sheet in which the resin cloth is impregnated with the resin cloth over the solution layer.

  The coating apparatus according to the present invention includes a first coating unit that coats a solution on a glass cloth to form a solution layer before coating a resin paste. Therefore, it is possible to prevent the resin paste applied in the second application part from easily penetrating into the glass cloth and forming holes (pinholes) in the resin-impregnated sheet or forming bubbles in the resin-impregnated sheet.

  Moreover, the coating device which concerns on this invention may convey the said carrier film and the said glass cloth to a said 2nd application part within 1 minute after passing a said 1st application part. Such a coating apparatus can more effectively exhibit the function of allowing the resin paste to easily penetrate into the glass cloth. Further, the solution applied by the first application part and the resin paste applied by the second application part may have the same viscosity or components as those in the above-described manufacturing method, and thereby, the effects described in the above-described manufacturing method can be achieved.

FIG. 1 is a conceptual diagram illustrating a manufacturing method according to an embodiment of the present invention. FIG. 2 is a flowchart showing the paste application process and the drying process shown in FIG. FIG. 3 is a schematic view of a coating device, a drying device, and a winding device. FIG. 4 is an enlarged view of a part of the coating apparatus shown in FIG. FIG. 5 is an enlarged cross-sectional view schematically showing the glass cloth after passing through the resin coating portion in the coating apparatus shown in FIG. FIG. 6 is a sketch drawing of a micrograph of a resin-impregnated sheet according to a reference example.

  FIG. 1 is a conceptual diagram illustrating a manufacturing method according to an embodiment of the present invention. As shown in FIG. 1, the multilayer printed circuit board 20 is manufactured through a resin paste preparation step S001-1, a paste application step S002, a drying step S003, a cutting step S004, a laminating step S005, a pressing step S006, and the like.

  In the resin paste preparation step S001-1, the resin paste 22 to be applied to the glass cloth 24 in the paste application step S002 is prepared. In the resin paste preparation step S001-1, the resin paste 22 is mixed with a resin, a solvent, a filler, and the like as raw materials. The mixture is stirred with the stirrer 10 and then milled as necessary to obtain a resin paste. Get 22. Examples of the resin used as the raw material of the resin paste 22 include novolac type epoxy resins and bisphenol type epoxy resins, but are not particularly limited. As a solvent mix | blended in resin paste preparatory process S001-1, although MEK, toluene, tetrahydrofuran etc. are mentioned, for example, it is not specifically limited. Moreover, in resin paste preparatory process S001-1, fillers, such as a silica, an alumina, aluminum hydroxide, boron nitride, are mix | blended according to the resin and solvent mix | blended. Although it does not specifically limit as a viscosity of the resin paste 22 produced by resin paste preparation process S001-1, For example, it can be 2.0-5.0 Pa.s at room temperature.

In the solution preparation step S001-2, a solvent such as MEK, toluene, tetrahydrofuran or the like may be added to the resin paste 22 and stirred to dilute the solution to 0.1 Pa · s or less. , Toluene, tetrahydrofuran may be used as a solution.

  In the paste application step S002 shown in FIG. 1, the resin paste 22 is applied to the continuous strip-shaped glass cloth 24 using the application device 12. Although it does not specifically limit as the glass cloth 24 used for paste application | coating process S002, For example, the thing of thickness 25-150 micrometers can be used. The paste application step S002 will be described in detail later.

  The resin-impregnated sheet 26 formed by applying the resin paste 22 to the glass cloth 24 is dried in the drying step S003 and then cut in the cutting step S004. The thickness of the resin-impregnated sheet 26 is not particularly limited. For example, when a glass cloth 24 having a thickness of 35 to 75 μm is used, the thickness of the resin-impregnated sheet 26 can be set to 100 to 150 μm. The drying device 14 used in the drying step S003 is not particularly limited, and a horizontal or vertical drying furnace can be used.

  In the lamination step S005, one or a plurality of resin-impregnated sheets 26 and a metal layer 28 made of a conductive metal material are laminated. Further, in the pressing step S006, the multilayer body produced in the laminating step S005 is heated and pressed by the pressing device 18 to obtain the multilayer printed circuit board 20.

  FIG. 2 is a flowchart showing detailed steps such as paste application step S002 and drying step S003 shown in FIG. FIG. 3 is a schematic diagram of the coating device 12 and the drying device 14 in which the paste coating step S002 and the drying step S003 shown in FIG. 1 are performed, and the separation winding device 19 associated therewith.

  As shown in FIG. 3, in the coating device 12, the drying device 14, and the separation and winding device 19, a continuous belt-like glass cloth 24 and a carrier film 30 are formed by a transport unit configured using a plurality of rotating rolls. Be transported. The glass cloth 24 is fed from the glass cloth feeding section 40 in the coating apparatus 12, passes through the inside of each apparatus in the order of the coating apparatus 12, the drying apparatus 14, and the separation winding apparatus 19, and is wound by the glass cloth winding section 68. It is done. Further, the carrier film 30 is fed out from the carrier film feeding section 42 in the coating apparatus 12, and after passing through the inside of each apparatus 12, 14, and 19, similarly to the glass cloth 24, the carrier film 30 is wound up by the carrier film winding section 70. It is done. Since the glass cloth 24 is impregnated with the resin paste 22 in the coating device 12, it becomes a resin-impregnated sheet 26 (see FIG. 5) when it comes out of the drying furnace.

  The material of the carrier film 30 used in the present embodiment is not particularly limited. For example, a resin sheet such as a PET film can be used as the carrier film 30. Further, a release agent layer may be provided on the facing surface 30a (see FIG. 5) of the carrier film 30 facing the glass cloth 24 in order to facilitate separation of the glass cloth 24 and the carrier film 30. .

  The carrier film 30 and the glass cloth 24 are conveyed through the first application unit 46 and the second application unit 58 in the coating apparatus 12 and the inside of the drying apparatus 14 while applying a predetermined tension. The tension applied to the carrier film 30 and the glass cloth 24 is the rotational load of the carrier film feeding part 42 and the glass cloth feeding part 40, the pressure of the nip roll 66, the carrier film winding part 70, and the glass cloth winding part 68. It is adjusted by the winding speed or the like.

  The tension applied to the carrier film 30 and the glass cloth 24 is adjusted so that excessive looseness does not occur in the conveyed glass cloth 24 and wrinkles or the like do not occur in the glass cloth 24. For example, the tension applied to the carrier film 30 and the glass cloth 24 may be about 0.3 to 1.5 N / cm in consideration of the tension per unit length in the width direction of the carrier film 30 and the glass cloth 24. Yes, but not particularly limited.

  During conveyance, the tension applied to the carrier film 30 and the tension applied to the glass cloth 24 may be the same, but a greater tension than the carrier film 30 may be applied to the glass cloth 24. As a result, the resin paste 22 easily penetrates into the glass cloth 24 in the resin application step S103 described later. In this case, in order to obtain the effect of improving the permeability of the resin paste 22 without causing wrinkles or the like in the glass cloth 24, the tension applied to the glass cloth 24 is 1.2 of the tension applied to the carrier film 30. It is preferable that it is -1.5 times.

  As shown in FIG. 2, in the coating apparatus 12 shown in FIG. 3, first, an overlaying step S101 (step S101) is performed. In the superimposing step (step S101), as shown in FIG. 3, the glass cloth 24 fed from the glass cloth feeding portion 40 and the carrier film 30 fed from the carrier film feeding portion 42 are overlapped on the overlapping roll 44. Adapted.

  Next, the carrier film 30 and the glass cloth 24 superimposed on the superimposing roll 44 are conveyed to the first coating unit 46 in the coating device 12. FIG. 4 is an enlarged view in which a portion surrounded by a dotted line in FIG. 3 is enlarged. As shown in FIG. 4, the first application unit 46 in the application apparatus 12 includes a first ink pan 48 filled with the application solution 32, and a solution application roll for applying the application solution 32 of the first ink pan 48 to the glass cloth 24. 50.

  In the 1st application part 46, the 1st application process shown by Step S102 in Drawing 2 is carried out. In the first coating step S102, the coating solution 32 is applied to the glass cloth 24 that is conveyed while being superimposed on the carrier film 30 to form a solution layer 32a. The solution application roll 50 shown in FIG. 4 rotates in the direction opposite to the conveyance direction of the glass cloth 24 (clockwise in FIG. 4), and the application solution 32 of the first ink pan 48 is transferred to the glass cloth 24 by a so-called reverse gravure method. Apply to.

  In the first application part 46, the application solution 32 is applied to the first surface 24 a that is the surface opposite to the surface facing the carrier film 30 in the glass cloth 24. Thereby, a solution layer 32 a made of the coating solution 32 is formed at least in the vicinity of the first surface 24 a of the glass cloth 24. The application solution 32 applied in the first application unit 46 may penetrate into the glass cloth 24. For example, the solution layer 32a may be formed not only in the vicinity of the first surface 24a of the glass cloth 24 but also in the vicinity of the second surface 24b (see FIG. 5) that is the surface facing the carrier film 30 in the glass cloth 24. .

  Next, the glass cloth 24 and the carrier film 30 on which the solution layer 32 a is formed are transported to the second coating unit 58 in the coating apparatus 12. The second application unit 58 includes a second ink pan 60 and a comma roll 62 disposed adjacent to the backup roll 52. The comma roll 62 has a notch 62a. The gap between the comma roll 62 and the backup roll 52 is determined in consideration of the amount of resin paste 22 applied to the glass cloth 24. The second ink pan 60 is filled with the resin paste 22 manufactured in the resin paste preparation step S001-1. The resin paste 22 is supplied to the second ink pan 60 by a conveyance pump (not shown).

  In the 2nd application part 58, the 2nd application process shown by Step S103 in Drawing 2 is carried out. As shown in FIG. 4, in the second coating step S103, the resin paste 22 is applied to the glass cloth 24 so as to overlap the solution layer 32a.

  The glass cloth 24 conveyed to the second application unit 58 passes through the second ink pan 60 filled with the resin paste 22 while being pressed against the backup roll 52 together with the carrier film 30. Further, when the glass cloth 24 passes between the comma roll 62 and the backup roll 52, the resin paste 22 is pressed from the first surface 24a side, and the amount of the resin paste 22 applied is adjusted.

  Thus, in the 2nd application part 58, when passing the glass cloth 24 through the 2nd ink pan 60, and when passing between the comma roll 62 and the backup roll 52, it is resin from the 1st surface 24a. Paste 22 is applied. Thereby, in resin application process S103, the resin impregnation sheet | seat 26 in which the glass paste 24 was impregnated with the resin paste 22 is formed.

  FIG. 5 is an enlarged view of a portion surrounded by a dotted line V in FIG. 4, and is an enlarged view showing the resin-impregnated sheet 26 formed in the second application step S103. The resin paste 22 applied from the first surface 24 a in the resin application portion 58 fills the gap 24 c of the glass cloth 24 and penetrates to the second surface 24 b and is impregnated into the glass cloth 24.

  The resin-impregnated sheet 26 formed by the first application step S102 and the second application step S103 according to the present embodiment has few pinholes and bubbles. This is because, in the second coating step S103, the resin paste 22 is applied over the solution layer 32a formed in the first coating step S102, so that the glass cloth 24 is easily impregnated. This mechanism is related to the action of the resin paste 22 being diluted with the coating solution 32 constituting the solution layer 32a, the action of the solute in the resin paste 22 moving to the coating solution 32 constituting the solution layer 32a, and the like. it seems to do.

  In this embodiment, it is preferable that the time from the end of the first application step S102 to the start of the second application step S103 is shorter, and the second application step S103 is within one minute after the first application step S102 is performed. It is preferable to be performed. When the time from the completion of the first coating step S102 to the start of the second coating step S103 is long, the coating solution 32 constituting the solution layer 32a decreases or disappears due to volatilization or the like, and the effect of promoting the impregnation of the resin paste 22 Because it becomes weaker.

  Note that the first coating step S102 and the second coating step S103 may be performed simultaneously (at substantially the same position in the coating apparatus 12). Further, the resin paste 22 applied in the first application step S102 may contain the same solvent component as that of the application solution 32 constituting the solution layer 32a. For example, if the main component of the coating solution 32 is MEK, the resin paste 22 may include MEK. By setting it as such a structure, the resin paste 22 applied in piles on the solution layer 32a is suitably diluted with the coating solution 32 which comprises the solution layer 32a.

  As shown in FIG. 3, the resin-impregnated sheet 26 formed in the second application unit 58 is then conveyed to the drying device 14. In the drying apparatus 14, the drying process shown by step S003 in FIG. 2 is performed. In the drying step S003, the resin-impregnated sheet 26 is conveyed along with the carrier film 30 in the drying furnace. Although the drying conditions in drying process S003 are not specifically limited, For example, they can be 50 to 150 degreeC and 10 to 30 minutes.

  As shown in FIG. 3, the resin-impregnated sheet 26 dried in the drying device 14 is conveyed to the separation and winding device 19. In the separation winding device 19, a separation winding process shown in step S104 in FIG. 2 is performed. In the separation winding step S <b> 104, the resin-impregnated sheet 26 is conveyed to a separation unit 64 including a nip roll 66, and is separated from the carrier film 30 in the separation unit 64.

  In the separation winding step S <b> 104, the resin-impregnated sheet 26 is separated from the carrier film 30 and then taken up by the glass cloth winding unit 68. The carrier film 30 separated from the resin-impregnated sheet 26 is wound up by the carrier film winding unit 70.

  Further, the resin impregnated sheet 26 is cut by a cutting device 16 as shown in FIG. The process of obtaining the multilayer printed circuit board 20 from the cut resin impregnated sheet 26 is as described above.

  As shown in FIGS. 2 and 3, the resin-impregnated sheet 26 formed in the paste application step S002 and the drying step S003 may be cut after being wound once in the separation winding step S104. You may cut | disconnect immediately after process S003. When performing such a manufacturing method, it replaces with the separation winding apparatus 19 in FIG. 3, and the cutting device 16 (FIG. 1) is arrange | positioned after the drying apparatus 14. FIG.

  In the manufacturing method according to the present embodiment, the resin paste 22 is applied so as to overlap the solution layer 32a formed in the first application step S102, and thus is easily impregnated into the glass cloth 24. Therefore, the manufacturing method according to the present embodiment can effectively suppress the phenomenon that pinholes and bubbles are formed in the resin-impregnated sheet 26.

  The viscosity of the resin paste 22 used in the above embodiment is preferably 0.5 to 5.0 Pa · s, and more preferably 2.0 to 3.0 Pa · s. The resin paste 22 having a viscosity equal to or higher than a predetermined value is suitable as the resin paste 22 used in the second coating step S103 because separation due to sedimentation of the filler is suppressed. Further, according to the manufacturing method according to the present embodiment, it is possible to more effectively prevent bubbles and the like from being formed in the resin-impregnated sheet 26 by setting the viscosity of the resin paste 22 to a predetermined value or less. It is.

  The above-described embodiment is merely one embodiment of the present invention, and various modifications can be made. For example, in the above-described embodiment, the first coating step S102 is a reverse gravure method and the second coating step S103 is a comma roll method, but a specific coating method in the first coating step S102 and the second coating step S103. Is not limited to this, and other coating methods may be used.

EXAMPLES Hereinafter, the present invention will be described based on more detailed examples, but the present invention is not limited to these examples.

Sample 1
A resin-impregnated sheet 26 was produced using the coating apparatus 12 and the drying apparatus 14 shown in FIG. That is, in sample 1, after applying solvent MEK as coating solution 32 to glass cloth 24 to form solution layer 32a (first coating step S102), resin paste 22 is applied over solution layer 32a (first coating step). 2 coating step S103) and then dried (drying step S003).

  Resin paste 22 used for sample 1 is a mixture of 100 parts by weight of novolak type epoxy resin as resin, 450 parts by weight of MEK (methyl ethyl ketone) as solvent, and 1000 parts by weight of silica as filler, and stirring and mill-dispersing. Was obtained by The viscosity of the resin paste 22 used for Sample 1 was 1.188 Pa · s at room temperature (20 ° C.) as measured by an E-type viscometer.

  Sample 1 was prepared using a glass cloth having a thickness of 50 μm as the glass cloth 24 and a PET film having a thickness of 75 μm as the carrier film 30. At the time of conveyance, substantially equal tension was applied to the glass cloth 24 and the carrier film 30. The drying conditions in the drying step S003 (see FIG. 2) were 100 ° C. and 15 minutes.

Moreover, the sample 1 obtained on the above-mentioned conditions was observed under a microscope (20 to 50 times), and the number of bubbles observed per unit area (1 cm ² ) of the resin-impregnated sheet 26 was measured. FIG. 6 is a sketch drawing of a micrograph of the resin-impregnated sheet 126 according to the reference example. In FIG. 6, a bubble shadow is seen at a position indicated by a circle 128. For Sample 1, the shadows of bubbles as shown in FIG. 6 were observed from both surfaces of the resin-impregnated sheet 26. Table 1 shows the evaluation conditions and evaluation results of Sample 1.

Sample 2 and Sample 3
Sample 2 and Sample 3 were produced in the same manner as Sample 1 except that the composition of the resin paste 22 used for production was changed. The resin paste 22 used in Sample 2 was blended with 100 parts by weight of novolac epoxy resin, 350 parts by weight of MEK (methyl ethyl ketone), and 1000 parts by weight of silica. In addition, the resin paste 22 used in the sample 3 was mixed with 100 parts by weight of a novolac type epoxy resin, 300 parts by weight of MEK (methyl ethyl ketone), and 1000 parts by weight of silica.

The viscosity of the resin paste 22 used for Sample 2 and Sample 3 was 2.010 Pa · s and 3.083 Pa · s, respectively, at room temperature (20 ° C.) as measured by an E-type viscometer. For the resin-impregnated sheets 26 according to Sample 2 and Sample 3, as with Sample 1, the number of bubbles observed per unit area (1 cm ² ) was measured. Table 1 shows the evaluation conditions and evaluation results of Sample 2 and Sample 3.

Sample 4 to Sample 6
Samples 4 to 6 were prepared in the same manner as Samples 1 to 3 except that the coating apparatus in which the first coating unit 46 was removed from the coating apparatus 12 shown in FIG. That is, in the samples 4 to 6, the first coating step S102 is not performed, and the resin paste 22 is applied to the glass cloth 24 on which the solution layer 32a is not formed in the second application unit 58, and then dried. It was prepared by.

Samples 4 to 6 were prepared using the same resin paste 22 as the resin paste 22 used for Samples 1 to 3 (see Table 1). Further, for the resin-impregnated sheets according to Samples 4 to 6, the number of bubbles observed per unit area (1 cm ² ) was measured in the same manner as Samples 1 to 3. Table 1 shows the evaluation conditions and evaluation results of Sample 4 to Sample 6.

As shown in the comprehensive evaluation table 1 of Sample 1 to Sample 6, no bubbles were found in the evaluation of the resin-impregnated sheet 26 according to Sample 1 to Sample 3. Since the resin-impregnated sheet 26 according to Samples 1 to 3 was produced by applying the resin paste 22 on the solution layer 32a, the phenomenon that pinholes and bubbles are formed in the resin-impregnated sheet 26 is suppressed. Conceivable. On the other hand, in the evaluation of the resin-impregnated sheets according to Sample 4 to Sample 6, bubbles were found in the resin-impregnated sheets. In particular, in Sample 5 and Sample 6 in which the resin paste 22 has a high viscosity, it is considered that the resin paste 22 was difficult to be impregnated in the glass cloth 24, and thus many bubbles were formed in the resin-impregnated sheet 26.

  Thus, from the evaluation results of Sample 1 to Sample 6, after applying the coating solution 32 to the glass cloth 24 to form the solution layer 32a, the resin paste 22 is applied over the solution layer 32a, thereby impregnating the resin. It was confirmed that the phenomenon that bubbles are formed in the sheet 26 can be effectively suppressed. Further, such an effect is particularly remarkable when the viscosity of the resin paste 22 is high. In the manufacturing method in which the resin paste 22 is applied to the solution layer 32a, the resin paste 22 is 2.0 to 3.0 Pa · s. In this case, it was confirmed that there was a particularly remarkable effect.

Sample 7 to Sample 10
Samples 7 to 10 were prepared in the same manner as Sample 2 except that MEK was applied to the glass cloth 24 as the coating solution 32 and the time interval until the resin paste 22 was applied to the same place was changed. That is, in each of Sample 7 to Sample 10, after applying the coating solution 32 to the glass cloth 24 to form the solution layer 32a (first coating step S102), the resin paste 22 is applied over the solution layer 32a ( The second coating step S103) and then dried (drying step S003) were produced (see FIGS. 2 and 3).

  However, Samples 7 to 10 have a time period from application of the application solution 32 to the glass cloth 24 to application of the resin paste 22, 0.5 minutes, 1.0 minute, 1.5 minutes, and 2. It was 0 minutes. The time from application of the application solution 32 to the glass cloth 24 to application of the resin paste 22 was adjusted by the application speed of the application device 12 shown in FIG.

Samples 7 to 10 were observed under a microscope (20 to 50 times), and the number of pin poles and the number of bubbles observed per unit area (1 cm ² ) of the resin-impregnated sheet 26 were measured. Table 2 shows production conditions and evaluation results of Sample 7 to Sample 10.

As shown in General Evaluation Table 2 of Sample 7 to Sample 10, in Sample 7 and Sample 8 in which the time from application of the coating solution 32 to the glass cloth 24 to application of the resin paste 22 is within 1 minute, bubbles And no pinholes were found. The resin-impregnated sheet 26 according to the sample 7 and the sample 8 has a phenomenon that pinholes and bubbles are formed in the resin-impregnated sheet 26 when the resin paste 22 and the coating solution 32 constituting the solution layer 32a are preferably in contact with each other. It is thought that it was able to suppress effectively.

  On the other hand, bubbles and pinholes were found in Sample 9 and Sample 10 in which the time from application of the coating solution 32 to the glass cloth 24 to application of the resin paste 22 was 1.5 minutes or longer. In addition, as the time from application of the application solution 32 to the glass cloth 24 to application of the resin paste 22 becomes longer, more pinholes and bubbles are formed in the resin-impregnated sheet 26. In Sample 9 and Sample 10, since the time from the end of the first coating step S102 to the start of the second coating step S103 is long, the coating solution 32 constituting the solution layer 32a decreases or disappears due to volatilization or the like. It is considered that the effect of promoting the impregnation of the paste 22 is weakened.

Sample 11 to Sample 12
Samples 11 to 12 use a solvent MEK so that the solution 32 applied to the glass cloth 24 is different from the sample 2 and the viscosity of the resin paste 22 approaches 0.1 Pa · s or 0.15 Pa · s. The coating solution 32 was prepared by diluting while stirring. Further, in each of the samples 11 to 12, the coating solution 32 is applied to the glass cloth 24 (first coating step S102), and the resin paste 22 is further applied to the solution layer 32a (second coating step S103). It produced by drying (dry process S003) (refer FIG.2 and FIG.3). Table 3 shows production conditions and evaluation results of Sample 2, Sample 11, and Sample 12.

As shown in the comprehensive evaluation table 3 of Sample 11 to Sample 12, in Sample 2 where MEK was applied in the first application step, and in Sample 11 where the solution viscosity in the first application step was 0.095 Pa · s, both were bubbles. However, in Sample 12 where the solution viscosity in the first coating step was 0.152 Pa · s, more bubbles were formed than Sample 2 and Sample 11. It is considered that the effect of promoting the impregnation of the resin paste 22 was weakened in the sample 12 because the solution viscosity in the first application process was high.

DESCRIPTION OF SYMBOLS 12 ... Coating device 14 ... Drying device 19 ... Separation winding device 20 ... Multilayer printed circuit board 22 ... Resin paste 24 ... Glass cloth 24a ... First surface 24b ... Second surface 24c ... Gap 26 ... Resin impregnated sheet 28 ... Metal layer 30 ... Carrier film 30a ... Opposite surface 32 ... Coating solution 32a ... Solution layer 40 ... Glass cloth feeding part 42 ... Carrier film feeding part 44 ... Superposition roll 46 ... First coating part 48, 60 ... Ink pan 50 ... Solution coating roll 52 ... Backup roll 58 ... Second application part 62 ... Comma roll

Claims (9)

A first application step of forming a solution layer by applying a solution to a glass cloth that is superimposed and conveyed with a carrier film;
A second application step of applying a resin paste to the glass cloth over the solution layer, and forming a resin-impregnated sheet in which the resin cloth is impregnated with the glass cloth;
And a drying step of drying the resin-impregnated sheet.   The manufacturing method according to claim 1, wherein the second application step is performed within one minute after the first application step is performed.   The manufacturing method according to claim 1 or 2, wherein the solution has a viscosity of 0.1 Pa · s or less, and the resin paste has a viscosity of 2.0 to 5.0 Pa · s.   The manufacturing method according to claim 1, wherein the resin paste contains the same solvent component as the solution applied to the glass cloth in the first application step.   The multilayer printed circuit board manufactured by the manufacturing method of the multilayer printed circuit board in any one of Claim 1- Claim 4. A transport unit that transports the carrier film and the glass cloth by overlapping each other;
A first application part that forms a solution layer by applying a solution to the glass cloth that is superimposed and conveyed with the carrier film;
And a second application unit that applies a resin paste to the glass cloth so as to overlap the solution layer and forms a resin-impregnated sheet in which the glass cloth is impregnated with the resin paste.   The coating apparatus according to claim 6, wherein the transport unit transports the carrier film and the glass cloth to the second coating unit within one minute after passing through the first coating unit. .   The viscosity of the solution applied by the first application part is 0.1 Pa · s or less, and the viscosity of the resin paste applied by the second application part is 2.0 to 5.0 Pa · s. The coating apparatus according to claim 6 or 7, wherein the coating apparatus is characterized in that: 9. The resin paste applied by the second application part includes a solution component similar to the solution applied by the first application part, according to any one of claims 6 to 8. Coating device.

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