JP2011201202A - Method for production of multilayer printed board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method for multilayer printed boards suppressing formation of pinholes or bubbles in a resin-impregnated sheet.SOLUTION: The production method for multilayer printed boards is characterized by including the processes of: overlapping a carrier film 30 conveyed while a first tension is applied, and a glass cloth 24 conveyed while a second tension greater than the first tension is applied; applying a resin paste to the glass cloth conveyed in such a state that the second tension is applied; and drying the glass cloth on which the resin paste is applied.

Description

  The present invention relates to a method for manufacturing a multilayer printed circuit board manufactured by applying a resin to a glass cloth.

  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 metal layer, 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. 5-114786 Japanese Patent Laid-Open No. 7-307568

  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 relates to a method for manufacturing a multilayer printed board capable of suppressing the formation of pinholes and bubbles in a resin-impregnated sheet.

In order to achieve the above object, a method for producing a multilayer printed board according to the present invention comprises:
A superimposing step of superimposing a carrier film conveyed while applying a first tension and a glass cloth conveyed while applying a second tension greater than the first tension;
An application step of applying a resin paste to the glass cloth conveyed in a state where the second tension is applied;
And drying the glass cloth coated with the resin paste.

  In the manufacturing method according to the present invention, since the resin paste is applied to the glass cloth that is conveyed in a state in which a larger tension than the carrier film is applied, the resin paste can easily penetrate into the glass cloth. . Therefore, the manufacturing method according to the present invention can suppress the phenomenon that pinholes and bubbles are formed in the glass cloth coated with the resin paste.

For example, the application process may include a first application process and a second application process,
The resin paste may have a first resin paste applied in the first application step and a second resin paste applied in the second application step,
In the first application step, the first resin paste is applied to the carrier film before the overlapping step, and the carrier film to which the first resin paste is applied is overlapped on the glass cloth. The first resin paste may be applied to the glass cloth from the first surface of the glass cloth facing the carrier film simultaneously with the overlapping step,
In the second application step, after the first application step, the second resin paste may be applied to the glass cloth from a second surface opposite to the first surface.

  A manufacturing method having a first application step of applying a resin paste from a first surface via a carrier film and a second application step of applying a resin paste from a second surface opposite to the first surface is a resin paste The phenomenon that pinholes and bubbles are formed in the glass cloth coated with can be more effectively suppressed.

  Further, for example, the amount of the first resin paste applied to the glass cloth in the first application step is larger than the amount of the second resin paste applied to the glass cloth in the second application step. May be.

  By making the amount of the first resin paste larger than the amount of the second resin paste, the phenomenon that pinholes and bubbles are formed in the glass cloth coated with the resin paste is more effectively suppressed. Can do.

In addition, for example, the application step includes
A smoothing step of leveling the first resin paste protruding from the second surface side of the glass cloth may be provided between the first application step and the second application step.

  By performing the smoothing process after the first application process, it is possible to suppress the phenomenon that the resin paste entrains bubbles in the second application process.

  Further, for example, the coating step may be characterized in that the resin paste is pressed and applied toward the glass cloth.

  In the manufacturing method according to the present invention, the coating step is not simply a method of immersing the glass cloth in the resin tank, but a method of applying force by applying the force to the resin paste and pressing the resin paste toward the glass cloth. It is preferable. As a result, the phenomenon of pinholes and bubbles being formed in the glass cloth to which the resin paste is applied can be more effectively suppressed.

  For example, the viscosity of the resin paste may be 2.5 Pa · s or less.

  By setting the viscosity of the resin paste to 2.5 Pa · s or less, the resin paste can easily penetrate into the glass cloth. Therefore, pinholes and bubbles are formed in the glass cloth to which the resin paste is applied. It is possible to further suppress the phenomenon that is formed.

  Further, for example, the second tension may be 1.2 to 1.5 times the first tension.

  By setting the tension of the glass cloth to 1.2 times or more of the tension of the carrier film, the phenomenon that the resin paste easily penetrates into the glass cloth becomes more remarkable. Further, by setting the tension of the glass cloth to 1.5 times or less of the tension of the carrier film, wrinkles and the like can be prevented from being generated on the glass cloth being conveyed.

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 view in which the periphery of the overlapping portion in the coating apparatus shown in FIG. 4 is further enlarged. FIG. 6 is an enlarged view showing the glass cloth after passing through the second coating part in the coating apparatus shown in FIG. FIG. 7 is a view showing a part of a coating apparatus in which the manufacturing method according to the second embodiment of the present invention is performed. FIG. 8 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, 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, the resin paste 22 to be applied to the glass cloth 24 in the paste application step S002 is prepared. In the present embodiment, the first resin paste 22a and the second resin paste 22b are used in the paste application step S002 (see FIG. 4), but the first resin paste 22a and the second resin paste 22b are the same. Has composition and viscosity. That is, the first resin paste 22a and the second resin paste 22b are the same resin paste 22 used at different stages of the manufacturing process, but pastes having different viscosities may be used depending on the coating method. .

  In the resin paste preparation step S001, the resin paste 22 is mixed by mixing the resin, solvent, filler, and the like, which are the raw materials of the resin paste 22, with the stirrer 10, and then performing mill dispersion or the like as necessary. obtain. 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. Examples of the solvent blended in the resin paste preparation step S001 include, but are not particularly limited to, MEK, toluene, and tetrahydrofuran. Moreover, in resin paste preparation process S001, fillers, such as a silica, an alumina, aluminum hydroxide, a 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, For example, it can be 0.5-5.0 Pa.s at room temperature.

  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 coating apparatus 12. Although it does not specifically limit as the glass cloth 24 used for a paste application | coating process, For example, the thing of thickness 25-150 micrometers can be used. The paste application step S002 will be described in detail later.

  The glass cloth 24 coated with the resin paste 22 is dried in the drying step S003 and then cut in the cutting step S004, thereby obtaining the resin-impregnated sheet 26. The thickness of the resin-impregnated sheet 26 is not particularly limited. For example, when a glass cloth 24 having a thickness of 70 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 winding device 19 associated therewith.

  As shown in FIG. 3, a continuous belt-like glass cloth 24 and a carrier film 30 are conveyed using a plurality of rotating rolls inside the coating device 12, the drying device 14, and the winding device 19. 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 winding apparatus 19, and is wound up by the glass cloth winding section 68. . 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.

  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 surface 30 a (see FIG. 6) 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 is conveyed through the carrier film coating unit 46 and the second coating unit 58 in the coating device 12 and the inside of the drying device 14 while being applied with a first tension. The first tension applied to the carrier film 30 is adjusted by the rotational load of the carrier film feeding section 42, the pressure of the first nip roll 44 and the second nip roll 66, the winding speed of the carrier film winding section 70, and the like. The

  The first tension applied to the carrier film 30 is such that excessive looseness does not occur in the glass cloth 24 conveyed by the carrier film 30, and wrinkles or the like do not occur in the glass cloth 24. Considering the tension per unit length in the width direction, it can be about 1.0 to 5.0 N / cm, but is not particularly limited.

  In addition, the glass cloth 24 is conveyed through the overlapping unit 54 and the second coating unit 58 in the coating device 12 and the inside of the drying device 14 while being applied with the second tension. The second tension applied to the glass cloth 24 is adjusted by the rotational load of the roll in the glass cloth feeding section 40, the pressure of the second nip roll 66, the rotational speed of the glass cloth winding section 68, and the like.

  The second tension applied to the glass cloth 24 is preferably larger than the first tension applied to the carrier film 30 and is 1.2 to 1.5 times the first tension. As a result, in the coating device 12, the resin paste 22 is applied to the glass cloth 24 that is being transported in a state where a larger tension than the carrier film 30 is applied. 24 can be easily penetrated. Further, by making the second tension 1.2 times or more of the first tension, the effect of reducing the number of bubbles remaining in the glass cloth 24 to which the resin paste 22 is applied, The effect of suppressing the occurrence becomes more remarkable. Further, by setting the second tension to 1.5 times or less of the first tension, it is possible to prevent wrinkles and the like from being generated on the glass cloth 24 being conveyed.

  As shown in FIG. 2, in the coating apparatus 12 shown in FIG. 3, a carrier film coating step S101 is performed. FIG. 4 is an enlarged view in which a coating process portion surrounded by a dotted line IV in FIG. 3 is enlarged. As shown in FIG. 4, in the carrier film application step S <b> 101, the first resin paste 22 a is applied to the carrier film 30 before being superimposed on the glass cloth 24.

  The coating device 12 includes a carrier film coating unit 46 that applies the first resin paste 22 a to the carrier film 30. The carrier film application unit 46 includes a first ink pan 48 filled with the first resin paste 22 a and a first application roll 50 for applying the first resin paste 22 a of the first ink pan 48 to the carrier film 30. The carrier film coating unit 46 applies the first resin paste 22a to the surface 30a (see FIG. 6) of the carrier film 30 that faces the glass cloth 24.

  As shown in FIG. 2, after the carrier film application step S101, a step S102 of superimposing the carrier film 30 and the glass cloth 24 is performed. As shown in FIG. 4, the glass cloth 24 and the carrier film 30 are both superimposed on the overlapping portion 54 by being pressed against the outer peripheral surface of one overlapping roll 52. In the overlapping step, the glass cloth 24 and the carrier film 30 are overlapped so that the carrier film 30 is positioned on the inner peripheral side (the overlapping roll 52 side) and the glass cloth 24 is positioned on the outer peripheral side (see FIG. 5). ).

  Moreover, since the 1st resin paste 22a is apply | coated to the surface 30a which opposes the glass cloth 24 in the carrier film 30, the 1st resin paste 22a is apply | coated to the glass cloth 24 simultaneously with superposition process S102 ( First application step). That is, in the overlapping portion 54, the first resin paste 22 a applied to the surface 30 a of the carrier film 30 is pressed against the glass cloth 24. Therefore, the first resin paste 22 a is applied to the glass cloth 24 from the first surface 24 a of the glass cloth 24 facing the carrier film 30.

  As shown in FIG. 2, after the overlapping step S102, a smoothing step S103 for leveling the first resin paste 22a protruding to the second surface 24b side of the glass cloth 24 is performed. As shown in FIG. 4, the coating device 12 is provided with a smoother 56 for leveling the first resin paste 22 a protruding to the second surface 24 b side of the glass cloth 24.

  FIG. 5 is an enlarged view in which a portion surrounded by a dotted line V in FIG. 4 is enlarged. As shown in FIG. 5, the first resin paste 22 a applied in the overlapping portion 54 penetrates into the glass cloth 24 from the first surface 24 a of the glass cloth 24. Furthermore, a part of the first resin paste 22a applied to the glass cloth 24 passes through the gap 24c inside the glass cloth 24 and protrudes to the second surface 24b which is the surface opposite to the first surface 24a.

  The smoother 56 is in contact with the first resin paste 22a that protrudes to the second surface 24b side of the glass cloth 24, and leveles the first resin paste 22a that protrudes to the second surface 24b side of the glass cloth 24. As the smoother 56, as shown in FIG. 5, a rod-shaped one disposed substantially parallel to the overlapping roll 52 or a plate-shaped one may be used, and the shape of the smoother 56 is There is no particular limitation.

  As shown in FIG. 4, the smoother 56 is disposed on the outer peripheral side of the overlapping roll 52 and between the overlapping portion 54 and the second coating portion 58. Therefore, the smoothing step S103 by the smoother 56 is performed between the first coating step performed at the same time as the overlaying step S102 and the second coating step S104 performed in the second coating unit 58.

  As shown in FIG. 2, the second coating step S104 is performed after the smoothing step S103. As shown in FIG. 4, in the second coating step S <b> 104, the second resin paste 22 b is applied to the glass cloth 24 in the second coating unit 58.

  The second coating unit 58 includes a second ink pan 60 filled with the second resin paste 22 b and a comma roll 62 disposed adjacent to the overlapping roll 52. The comma roll 62 has a notch 62a. The gap between the comma roll 62 and the overlapping roll 52 is determined in consideration of the amount of the resin pastes 22a and 22b applied to the glass cloth 24.

  The glass cloth 24 overlapped with the carrier film 30 with the second surface 24b facing the outer peripheral side passes between the smoother 56 and the overlapping roll 52 and is conveyed to the second coating unit 58. The glass cloth 24 conveyed to the second coating unit 58 passes through the second ink pan 60 filled with the second resin paste 22b while being pressed against the overlapping roll 52 together with the carrier film 30. Further, when the glass cloth 24 passes between the comma roll 62 and the overlapping roll 52, the second resin paste 22b is pressed from the second surface 24b side, and the application amount of the second resin paste 22b is adjusted. The

  Thus, in the 2nd coating part 58, when passing the glass cloth 24 through the 2nd ink pan 60, and when passing between the comma roll 62 and the superimposition roll 52, it is from 2nd surface 24b. The second resin paste 22b is applied. FIG. 6 is an enlarged view of a portion surrounded by a dotted line VI in FIG. 4, and is an enlarged view showing the glass cloth 24 after passing through the second coating part 58.

  As shown in FIG. 6, the glass cloth 24 to which the resin pastes 22a and 22b are applied in the first application process S102 to the second application process S104 has few pinholes and bubbles. This is because, in the first coating step S102 to the second coating step S104, the resin paste 22a, by applying a large tension to the glass cloth 24 or by applying the time shifted from the first surface 24a side and the second surface 24b side. This is because 22b easily penetrates into the glass cloth 24 and air bubbles hardly remain in the gap 24c of the glass cloth 24. Moreover, the glass cloth 24 to which the resin pastes 22a and 22b are applied in the first application step S102 to the second application step S104 has high thickness uniformity.

  The amount of the first resin paste 22a applied to the glass cloth 24 in the first application step S102 is preferably larger than the amount of the second resin paste 22b applied to the glass cloth 24 in the second application step S104. This is because by making the amount of the first resin paste 22a larger than the amount of the second resin paste 22b, it becomes difficult for bubbles to remain in the gap 24c of the glass cloth 24.

  As shown in FIG. 2, a drying step S003 is performed after the second coating step S104. The drying step S003 is performed in the drying device 14 shown in FIG. 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.

  Further, after the drying step S003, a winding step S105 of the glass cloth 24 is performed as shown in FIG. As shown in FIG. 3, the glass cloth 24 that has passed through the drying device 14 is conveyed to the winding device 19. The winding device 19 includes a separation unit 64 including a second nip roll 66, and the glass cloth 24 coated with the resin pastes 22 a and 22 b is separated from the carrier film 30 in the separation unit 64.

  The glass cloth 24 to which the resin pastes 22a and 22b are applied is separated from the carrier film 30 and then taken up by the glass cloth take-up unit 68. The carrier film 30 separated from the glass cloth 24 is wound up by the carrier film winding unit 70.

  Further, the glass cloth 24 coated with the resin pastes 22a and 22b is cut by the cutting device 16 as shown in FIG. The process of obtaining the multilayer printed board 20 from the resin impregnated sheet 26 is as described above.

  As shown in FIGS. 2 and 3, the glass cloth 24 coated with the resin pastes 22a and 22b may be wound once after being wound in the winding step S105, but immediately after the drying step S003. It may be cut. When performing such a manufacturing method, it replaces with the 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 pastes 22a and 22b are applied to the glass cloth 24 that is being conveyed in a state in which a larger tension than the carrier film 30 is applied. Easy to penetrate. Therefore, the manufacturing method according to the present embodiment can suppress the phenomenon that pinholes and bubbles are formed in the glass cloth 24 to which the resin pastes 22a and 22b are applied. Moreover, according to the manufacturing method which concerns on this embodiment, the highly smooth resin impregnation sheet | seat 26 and the multilayer printed circuit board 20 containing this can be obtained.

  In the manufacturing method according to the present embodiment, the first resin paste 22a is applied from the first surface 24a, and the second resin paste 22b is applied from the second surface 24b opposite to the first surface 24a. A second coating step of coating. In the manufacturing method according to the present embodiment, the resin paste 22a is applied from one surface (first surface 24a) of the glass cloth 24, and then the resin paste 22b is applied from the other surface (second surface 24b) of the glass cloth 24. Therefore, the phenomenon that pinholes and bubbles are formed in the glass cloth 24 coated with the resin pastes 22a and 22b can be more effectively suppressed.

  In addition, the manufacturing method according to the present embodiment suppresses the phenomenon that the resin pastes 22a and 22b entrap bubbles in the second application step S104 by performing the smoothing step S103 (see FIG. 2) after the first application step S102. Can do. In the manufacturing method according to the present embodiment, the resin pastes 22a and 22b are pressed and applied toward the glass cloth 24 in the first application step S102 and the second application step S104. For this reason, the manufacturing method according to the present embodiment causes pinholes and bubbles to be formed in the glass cloth 24 coated with the resin pastes 22a and 22b, rather than a method of simply immersing the glass cloth 24 in the resin tank. Can be effectively suppressed.

Second Embodiment FIG. 7 is a view showing a part of a coating apparatus 82 in which a manufacturing method according to a second embodiment of the present invention is performed. The coating apparatus 82 according to the second embodiment is different from the coating apparatus 12 according to the first embodiment in that the carrier film coating unit 46 and the smoother 56 are not provided, but the other parts are the first embodiment. It is the same as that of the coating device 12 concerning.

  That is, in the coating device 82, as in the coating device 12, the second tension applied to the glass cloth 24 is greater than the first tension applied to the carrier film 30. Also in the coating device 82, similarly to the coating device 12, the second resin paste 22 b applied by the second coating unit 58 can easily penetrate into the glass cloth 24.

  In the manufacturing method according to the second embodiment, the resin paste 22 (second resin paste 22b) is applied only from the second surface 24b side of the glass cloth 24 in the second coating part 58. The manufacturing method according to the second embodiment is the same as the manufacturing method according to the first embodiment except that the carrier film application step S101 to the smoothing step S103 shown in FIG. 2 are not performed.

  In the manufacturing method according to the second embodiment, it is preferable to use the second resin paste 22b having a lower viscosity than the manufacturing method according to the first embodiment. This is because the resin paste 22b is easily soaked into the glass cloth 24.

  In the manufacturing method according to the second embodiment, the force with which the second resin paste 22b is pushed into the glass cloth 24 is preferably greater than the manufacturing method according to the first embodiment. That is, in the manufacturing method according to the second embodiment, it is preferable that the resin paste 22 b is strongly pressed by the glass cloth 24 when the glass cloth 24 passes between the comma roll 62 and the overlapping roll 52. This is because the resin paste 22b is easily soaked into the glass cloth 24.

  Similarly to the manufacturing method according to the first embodiment, the manufacturing method according to the second embodiment also adjusts the tension applied to the glass cloth 24, the viscosity of the resin paste 22b, and the like. It is possible to suppress the phenomenon that pinholes and bubbles are formed in the cloth 24.

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 to Sample 6
As samples 1 to 6, resin pastes 22a and 22b were applied to a glass cloth 24 using a coating apparatus 12 shown in FIG. That is, Sample 1 to Sample 6 are produced by a two-time coating method (see FIG. 2) in which the resin pastes 22a and 22b are applied at different times from the first surface 24a side and the second surface 24b side of the glass cloth 24. did.

  Resin pastes 22a and 22b used in Samples 1 to 6 were prepared by adding 16 parts by weight of a novolak type epoxy resin as a resin, 28 parts by weight of MEK (methyl ethyl ketone) as a solvent, and 54 parts by weight of silica as a filler. It was obtained by stirring and mill dispersion. The viscosity of the resin pastes 22a and 22b used for Sample 1 to Sample 6 was 2.5 Pa · s at room temperature (20 ° C.) as measured by an E-type viscometer.

  Samples 1 to 6 were prepared using a glass cloth having a thickness of 50 μm as the glass cloth 24 and using a PET film having a thickness of 75 μm as the carrier film 30. Samples 1 to 6 each have a ratio (second tension / first tension) of the second tension applied to the glass cloth 24 and the first tension applied to the carrier film 30 in the coating apparatus 12 to 1 respectively. 0.0, 1.1, 1.2, 1.4, 1.5, 1.6. In addition, the drying conditions in drying process S003 (refer FIG. 2) were 100 degreeC and 15 minutes.

Samples 1 to 6 obtained under the above conditions are observed under a microscope (20 to 50 times), and the number of pin poles observed per unit area (1 cm ² ) of the resin-impregnated sheet 26 and bubbles Was counted. FIG. 8 is a sketch drawing of a micrograph of the resin-impregnated sheet 126 according to the reference example. In FIG. 8, a shadow of the bubble can be seen at a position indicated by a circle 128. For Sample 1 to Sample 6, the shadows of the bubbles and pin poles as shown in FIG. 8 were observed from both surfaces of the resin-impregnated sheet 26. As a result of the measurement, those having 3 or less bubbles per unit area and 1 or less pin poles were judged as non-defective products. Table 1 shows the production conditions and evaluation results of Sample 1 to Sample 6.

  As shown in Table 1, the sample 1 in which the ratio of the second tension to the first tension is 1.0 shows that 24 bubbles and 16 pinholes per unit area are observed. there were. Samples 2 to 5 in which the second tension was greater than the first tension had a smaller number of bubbles and pinholes per unit area than sample 1. Thereby, it was confirmed that a phenomenon in which pinholes and bubbles are formed in the resin-impregnated sheet 26 can be suppressed by applying a greater tension to the glass cloth 24 than the carrier film 30.

  In particular, Sample 3 to Sample 5 in which the ratio of the second tension to the first tension is 1.2 to 1.5 have 3 or less bubbles per unit area and the number of pin poles is 1. It was less than the number and was a good product. However, in the sample 6 in which the ratio of the second tension to the first tension was 1.6, wrinkles occurred on the glass cloth 24 being conveyed, and the resin pastes 22a and 22b could not be applied. Thus, it can be seen that the ratio of the second tension applied to the glass cloth 24 and the first tension applied to the carrier film 30 is preferably 1.2 to 1.5.

Sample 7 to Sample 9
Samples 7 to 9 were produced by the same manufacturing method as Sample 3 except that the viscosity of the resin pastes 22a and 22b used in the coating process was changed. Specifically, sample 7 to sample 9 are 25 parts by weight, 30 parts by weight, and 40 parts by weight of the solvent added to the compound that is the raw material of the resin pastes 22a and 22b, respectively. Same as Sample 3. The viscosities of the resin pastes 22a and 22b used in Samples 7 to 9 were 3.0 Pa · s, 1.5 Pa · s, and 1.0 Pa · s at room temperature, respectively, as measured with an E-type viscometer.

For Sample 7 to Sample 9, 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 in the same manner as Sample 3. Table 2 shows production conditions and evaluation results of Samples 7 to 9 and Sample 3.

  As shown in Table 2, Sample 7 in which the viscosity of the resin pastes 22a and 22b was 3.0 Pa · s was a defective product because 29 bubbles and 14 pinholes were observed per unit area. However, Sample 3, Sample 8 and Sample 9 in which the viscosity of the resin pastes 22a and 22b is 2.5 Pa · s or less have 3 or less bubbles per unit area and 1 or less pin poles. Yes, it was a good product. Thereby, it turns out that it is preferable that the viscosity of resin paste 22a, 22b shall be 2.5 Pa * s or less.

Sample 10 to Sample 15
As Sample 10 to Sample 15, the second resin paste 22b was applied to the glass cloth 24 using the coating apparatus 82 shown in FIG. That is, Sample 10 to Sample 16 were produced by a one-time coating method in which the second resin paste 22b was applied only from the second surface 24b side of the glass cloth 24.

  The second resin paste 22b used in Samples 10 to 15 was obtained by adding 20 parts by weight of (novolak type epoxy resin) as a resin, 40 parts by weight of (MEK (methyl ethyl ketone)) as a solvent, and 55 parts by weight of silica as a filler. The formulation was obtained by stirring and mill dispersing. The viscosity of the second resin paste 22b used for Sample 10 to Sample 15 was 1.0 Pa · s at room temperature as measured by an E-type viscometer.

The preparation conditions of Sample 10 to Sample 15 are the same as the preparation conditions of Sample 1 to Sample 6, except that the single coating method is used and the viscosity of the second resin paste 22b is 1.0 Pa · s. is there. For Sample 10 to Sample 15, 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 in the same manner as Sample 1 to Sample 6. Table 3 shows the production conditions and evaluation results of Samples 10 to 15.

  As shown in Table 3, in the sample 10 in which the ratio of the second tension to the first tension is 1.0, 12 bubbles and 7 pinholes are observed per unit area, and the sample 10 is defective. there were. In Samples 11 to 14 in which the second tension was greater than the first tension, the number of bubbles and the number of pinholes per unit area were smaller than in Sample 10. Thus, it was confirmed that the number of pinholes and bubbles formed in the resin-impregnated sheet 26 can be reduced by applying a greater tension to the glass cloth 24 than the carrier film 30.

  In particular, Sample 12 to Sample 14 in which the ratio of the second tension to the first tension is 1.2 to 1.5 has 3 or less bubbles per unit area and the number of pin poles is 1. It was less than the number and was a good product. However, in the sample 15 in which the ratio of the second tension to the first tension was 1.6, wrinkles occurred on the glass cloth 24 being conveyed, and the second resin paste 22b could not be applied. Thus, it can be seen that the ratio of the second tension applied to the glass cloth 24 and the first tension applied to the carrier film 30 is preferably 1.2 to 1.5.

DESCRIPTION OF SYMBOLS 12, 82 ... Coating device 14 ... Drying device 20 ... Multilayer printed circuit board 22 ... Resin paste 22a ... First resin paste 22b ... Second resin paste 24 ... Glass cloth 24a ... First surface 24b ... Second surface 26 ... Resin impregnated sheet 28 ... Metal layer 30 ... Carrier film 46 ... Carrier film coating part 48, 60 ... Ink pan 50 ... First coating roll 52 ... Superposition roll 54 ... Superposition part 56 ... Smoother 58 ... Second coating part 62 ... Comma roll

Claims (7)

A superimposing step of superimposing a carrier film conveyed while applying a first tension and a glass cloth conveyed while applying a second tension greater than the first tension;
An application step of applying a resin paste to the glass cloth conveyed in a state where the second tension is applied;
And a drying step of drying the glass cloth on which the resin paste is applied. The application process includes a first application process and a second application process,
The resin paste has a first resin paste applied in the first application step and a second resin paste applied in the second application step,
In the first application step, the first resin paste is applied to the carrier film before the overlapping step, and the carrier film to which the first resin paste is applied is overlapped on the glass cloth. The first resin paste is applied to the glass cloth from the first surface of the glass cloth facing the carrier film simultaneously with the overlapping step,
The second resin paste is applied to the glass cloth from the second surface opposite to the first surface after the first application step in the second application step. The manufacturing method as described in.   The amount of the first resin paste applied to the glass cloth in the first application step is greater than the amount of the second resin paste applied to the glass cloth in the second application step. The manufacturing method according to claim 2. The coating process includes
3. A smoothing step of leveling the first resin paste protruding from the second surface side of the glass cloth between the first coating step and the second coating step. The manufacturing method according to claim 3.   The manufacturing method according to any one of claims 1 to 4, wherein, in the application step, the resin paste is applied by being pressed toward the glass cloth.   The manufacturing method according to claim 1, wherein the resin paste has a viscosity of 2.5 Pa · s or less.   The manufacturing method according to any one of claims 1 to 6, wherein the second tension is 1.2 to 1.5 times the first tension.

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