JP2009218441A - Multilayer circuit board, and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer circuit board in which cracks are hardly generated in an insulating base existing around a chip component, and to provide a method for manufacturing the multilayer circuit board. <P>SOLUTION: In the multilayer circuit board 100, the insulating base 1 is formed by sticking resin films composed of thermoplastic resin and the chip component is buried in the insulating base 1. intermediate insulating materials 5a, 5b of which the coefficient of thermal expansion in a base thickness direction (Z direction) is a middle between that of the insulating base 1 and that of the chip component 3 are arranged so as to be abutted on the side face of the chip component 3 in the base thickness direction (Z direction). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a multilayer circuit board in which resin films made of a thermoplastic resin are bonded to each other to form an insulating base material, and chip components are embedded in the insulating base material, and a method for manufacturing the same.

  A multilayer circuit board in which resin films made of thermoplastic resin are bonded to each other to form an insulating base material and chip components are embedded in the insulating base material is disclosed in, for example, Japanese Patent Application Laid-Open No. 2006-73763 (Patent Document 1). ).

  FIG. 10 is a view showing an example of the conventional multilayer circuit board, and FIG. 10A is a top view schematically showing the multilayer circuit board 90. FIG. 10B and FIG. 10C are cross-sectional views of the dashed-dotted line AA and the alternate long and two short dashes line BB in FIG.

  A multilayer circuit board 90 shown in FIG. 10 is a multilayer circuit board in which resin films made of thermoplastic resin are bonded to each other to form an insulating base material 1 and chip components 3 are embedded in the insulating base material 1. is there. In FIG. 10B and FIG. 10C, reference numeral 2 represents a conductor pattern made of copper, and reference numeral 4 represents a connection conductor portion obtained by sintering conductive paste.

When an electric circuit element such as a resistor or a capacitor is built in the insulating base 1 of the multilayer circuit board, the insulating base 1 is not limited to the chip component 3 as described above but is formed by a thin film or thick film technique. It is also possible to embed in However, in the production of the multilayer circuit board in which a plurality of resin films are bonded together by hot pressing, the former chip component 3 is attached to the multilayer circuit board from the formation range and formation accuracy of the resistance value and the capacitance value. Often built-in.
JP 2006-73763 A

  FIG. 11 is an example of a result of simulating the stress applied to the insulating base material 1 around the chip component 3 for the multilayer circuit board 90 of FIG. FIG. 11A is a perspective view of the ¼ analysis model, and FIG. 11B is a diagram showing the simulation result by isostress lines. In addition, the broken line in Fig.11 (a) has shown the boundary of the resin film before the adhesion which comprises the insulating base material 1. FIG.

  As shown in FIG. 11 (b), according to the simulation result, the portion of the insulating substrate 1 that is in contact with the vicinity of the central portion in the thickness direction of the chip component 3 becomes a stress concentration portion, and a stress of about 25 to 30 MPa is applied. appear. Even in the actually manufactured multilayer circuit board 90, cracks are likely to occur due to changes over time in the insulating base material 1 on the long side of the chip component 3 to which the maximum stress of about 30 MPa is applied.

  Accordingly, the present invention provides a multilayer circuit board in which resin films made of a thermoplastic resin are bonded to each other to form an insulating base material, and chip components are embedded in the insulating base material, and a method for manufacturing the same. An object of the present invention is to provide a multilayer circuit board in which cracks are unlikely to occur in an insulating base material around a component and a method for manufacturing the same.

  The multilayer circuit board according to claim 1, wherein a resin film made of a thermoplastic resin is bonded to each other to form an insulating base material, and a chip component is embedded in the insulating base material. An intermediate insulating material whose thermal expansion coefficient in the thickness direction is intermediate between the thermal expansion coefficient of the insulating base material and the thermal expansion coefficient of the chip component is disposed so as to contact the side surface of the chip component in the substrate thickness direction. It is characterized by.

  In a conventional multilayer circuit board in which a plurality of resin films made of a thermoplastic resin are bonded to each other to form an insulating base material, and chip components are embedded in the insulating base material, The insulating base material and the chip component are in direct contact with each other. When a simulation was performed on a conventional multilayer circuit board having such a structure, a portion of the insulating base material in contact with the vicinity of the central portion in the thickness direction of the chip component becomes a stress concentration portion, and a stress of about 25 to 30 MPa is generated. For this reason, even in a conventional multilayer circuit board actually manufactured, cracks are likely to occur due to changes over time or the like, particularly in the insulating base on the long side of a chip component to which a maximum stress of about 30 MPa is applied.

  As a result of analyzing the stress, it was concluded that the stress was generated due to the following factors. That is, chip parts such as resistors and capacitors generally have a thickness of 0.1 mm or more, and are often made of a ceramic material. Therefore, the linear expansion coefficient tends to be as low as 10 ppm or less. is there. On the other hand, the insulating base material in which a plurality of resin films made of the thermoplastic resin of the multilayer circuit board are bonded to each other has the linear expansion coefficient of the conductor pattern made of copper as the linear expansion coefficient in the substrate surface. The linear expansion coefficient in the thickness direction is generally several times to several tens of times larger than the linear expansion coefficient in the substrate surface. For this reason, due to the difference in linear expansion coefficient in the thickness direction between the chip component and the insulating substrate in the multilayer circuit board, the portion in contact with the vicinity of the central portion in the thickness direction of the chip component in the insulating substrate becomes a stress concentration portion, A stress of about 30 MPa is generated.

  Accordingly, in the multilayer circuit board according to claim 1, an intermediate insulating material having a thermal expansion coefficient in the substrate thickness direction between the thermal expansion coefficient of the insulating base and the thermal expansion coefficient of the chip component is used as the substrate of the chip component. It arrange | positions so that it may contact | abut on the side surface in the thickness direction. As a result, the difference in linear expansion coefficient between the chip component and the insulating base material in the thickness direction can be relaxed by the intermediate insulating material, and the stress applied to the insulating base material around the chip part can be reduced. According to the simulation, for example, with respect to the chip component having a linear expansion coefficient of 10 ppm, an intermediate insulating material having a linear expansion coefficient of 17 ppm is interposed between the insulating base material and the insulating base material around the chip component. Such stress can be reduced to about 13 to 16 MPa. For this reason, even in the multilayer circuit board that is actually manufactured, cracks are unlikely to occur due to changes over time, and the multilayer circuit board is a highly reliable multilayer circuit board.

  As described above, the multilayer circuit board is a multilayer circuit board in which resin films made of a thermoplastic resin are bonded to each other to form an insulating base material, and chip components are embedded in the insulating base material. Thus, a multilayer circuit board in which cracks are unlikely to occur in the insulating base material around the chip component can be obtained.

  In the multilayer circuit board, as described in claim 2, when the chip component has a substantially rectangular parallelepiped shape, the intermediate insulating material abuts on four side surfaces in the substrate thickness direction of the chip component. It is preferable that they are arranged in this manner. In particular, a configuration in which the intermediate insulating material is disposed so as to surround four side surfaces in the substrate thickness direction of the chip component is preferable. Thereby, the stress applied to the insulating base material around the chip component can be reduced evenly around the four side surfaces.

  In the multilayer circuit board, as described in claim 4, the intermediate insulating material abuts on a thickness region of 1/3 or more including a central portion in a thickness direction on a side surface of the chip component. Are preferably arranged. According to the simulation, the stress generated by the difference in linear expansion coefficient in the thickness direction between the chip component and the insulating base described above becomes a stress concentration portion near the center in the thickness direction of the chip component. Therefore, by arranging the intermediate insulating material so as to contact the thickness region of 1/3 or more including the central portion in the thickness direction on the side surface of the chip component as described above, the stress reducing effect by the intermediate insulating material Can be effectively exhibited. In particular, as described in claim 5, it is effective if the intermediate insulating material is arranged so as to be in contact with the entire region of the side surface of the chip component.

  In the multilayer circuit board, it is preferable that the width of the intermediate insulating material in the substrate surface is 1/10 or more of the thickness of the chip component. From the viewpoint of the stress reduction effect, it is desirable that the width of the intermediate insulating material is thicker. However, according to the simulation, it is remarkable that the width of the intermediate insulating material is 1/10 or more of the thickness of the chip component as described above. A stress reduction effect can be obtained.

  The multilayer circuit board is particularly preferably configured as described in claim 7. That is, in the multilayer circuit board, the fibrous molecules constituting the resin film are arranged in the film plane of the resin film so that the major axis directions of the fibrous molecules are substantially parallel to each other, and the fibers When the direction of the resin film obtained by averaging the major axis directions of the molecular molecules is MD and the direction of the resin film perpendicular to the MD is TD, the resin film has a linear expansion coefficient between the MD and the TD or It is an anisotropic film having a difference in strength, and is arranged so that the MD of the resin film is in the substrate thickness direction and the resin film is in contact with the side surface of the chip component in the substrate thickness direction. Thus, the resin film is used as the intermediate insulating material.

  A resin film constituting an insulating substrate in the multilayer circuit board in which a plurality of resin films made of thermoplastic resin are bonded to each other to form an insulating substrate, and chip parts are embedded in the insulating substrate. Is usually cut out from a sheet material manufactured by a sheet forming machine using a roller or the like. In addition, the microstructure of the thermoplastic resin is generally an aggregate of fibrous molecules that are constituent components of the thermoplastic resin. Therefore, in the sheet material, the fibrous molecules are arranged side by side with the major axis direction being substantially parallel to the flow direction of the sheet material in the sheet forming machine, and the sheet material flowing direction (MD , Machine Direction) and the width direction (TD, Traverse Direction) of the sheet material, the sheet material has anisotropy reflecting the orientation of the fibrous molecules. Therefore, even in the resin film of the component of the multilayer circuit board cut out in an arbitrary direction with respect to the sheet material, the fibrous molecules are aligned with the major axis direction being substantially parallel within the film surface of the resin film. The direction of the resin film averaged in the long axis direction of the fibrous molecules is MD, the direction of the resin film perpendicular to MD is the TD, and the resin film is generally MD and TD. Thus, an anisotropic film having a direction difference in linear expansion coefficient and strength is obtained. Needless to say, the linear expansion coefficient and strength are different from those in MD and TD in the thickness direction ZD of the resin film (sheet material). In the measurement example of the linear expansion coefficient of MD and ZD of the resin film, the linear expansion coefficient of MD was about 18 ppm, whereas the linear expansion coefficient of ZD was about 200 ppm. Moreover, in the measurement example of the tensile strength of MD and ZD of the resin film, the tensile strength of MD was about 140 MPa, whereas the tensile strength of ZD was 20 to 35 MPa.

  In the multilayer circuit board having the structure according to claim 7, the resin film constituting the insulating base material and the resin film used as the intermediate insulating material can be cut out from the same sheet material, and are the same material. Even when the resin films made of resin are heated and pressed to be bonded to each other, a uniform joint can be formed. Moreover, it is possible to give the stress reduction effect by relaxation of the thermal expansion difference mentioned above by arrange | positioning this resin film with the said orientation relationship as an intermediate | middle insulating material. Furthermore, the arrangement of the resin film having the azimuth relationship as an intermediate insulating material is an arrangement in which the stress generated by the difference in thermal expansion is received by an MD having high tensile strength.

  As described above, each of the multilayer circuit boards is a multilayer circuit in which resin films made of thermoplastic resin are bonded to each other to form an insulating base material, and chip components are embedded in the insulating base material. It is a board | substrate, Comprising: It can be set as the multilayer circuit board which a crack does not generate | occur | produce easily in the insulation base material around a chip component.

  The invention described in claims 8 to 11 relates to a method of manufacturing the multilayer circuit board.

  The invention according to claim 8 is a multilayer circuit board in which resin films made of thermoplastic resin are bonded to each other to form an insulating base material, and chip parts are embedded in the insulating base material. An intermediate insulating material whose thermal expansion coefficient in the direction is intermediate between the thermal expansion coefficient of the insulating base material and the thermal expansion coefficient of the chip component is arranged so as to contact the side surface of the chip component in the substrate thickness direction. A method for manufacturing a multilayer circuit board, comprising: a resin film preparation step for preparing the resin film in which a through hole for inserting the chip component and the intermediate insulating material is formed; and a resin for laminating a plurality of the resin films A film laminating step, a chip component arranging step of inserting and arranging the chip component and the intermediate insulating material in the through hole, and pressing the laminated body of the laminated resin films from both sides Heating and pressurizing step of embedding the chip part inserted in the through hole and the intermediate insulating material in the insulating base material while heating and bonding the resin films to each other to form the insulating base material It is characterized by having.

  Thus, the multilayer circuit board according to the first aspect can be manufactured at low cost. The effect of the multilayer circuit board manufactured by this is as described above, and the description thereof is omitted.

  In particular, when the multilayer circuit board according to claim 7 is manufactured by the manufacturing method according to claim 9, for example, according to claim 10, in the chip component arranging step, the intermediate insulating material is passed through the through-hole. In inserting and arranging in the hole, it can be manufactured by inserting and arranging a part of the resin film arranged above or below the through hole so as to be bent into the through hole. Further, according to the eleventh aspect, in the chip component arranging step, when the intermediate insulating material is inserted and arranged in the through hole, the MD of the resin film is in the substrate thickness direction of the chip component. In addition, the resin film may be inserted and disposed in the through hole in a state where the resin film is wound around the side surface of the chip component.

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

  FIGS. 1A and 1B are diagrams showing examples of multilayer circuit boards according to the present invention, respectively, and are schematic portions showing the periphery of the chip component 3 in the multilayer circuit boards 100 and 101 in an enlarged manner. It is a cross-sectional perspective view. Dotted lines XX, YY, and ZZ in FIGS. 1A and 1B are axes of symmetry of the chip component 3, and FIGS. 1A and 1B show the multilayer circuit board 100, The figure shows a 1/8 view in which the periphery of the chip component 3 in 101 is divided into a cross section XY, a cross section YZ, and a cross section ZX.

  FIG. 2 is an example of a result of simulating the stress applied to the insulating base material 1 around the chip component 3 for the multilayer circuit board 100 of FIG. FIG. 2A is a perspective view of the 1/8 analysis model including a wider range than that in FIG. 1A. FIG. 2B is an insulating view around the side surface of the chip part 3. FIG. It is the figure which showed the simulation result of the stress concerning the base material 1 by the iso-stress line.

  In the multilayer circuit boards 100 and 101 shown in FIGS. 1 and 2, the same parts as those in the multilayer circuit board 90 shown in FIGS. 10 and 11 are denoted by the same reference numerals. Moreover, the broken line in Fig.2 (a) has shown the boundary of the resin film before the adhesion which comprises the insulating base material 1. FIG.

  The multilayer circuit boards 100 and 101 shown in FIGS. 1A and 1B are both formed by bonding resin films made of a thermoplastic resin to form an insulating base material 1. This is a multilayer circuit board in which the chip component 3 is embedded. In the multilayer circuit boards 100 and 101 of FIGS. 1A and 1B, the intermediate insulating materials 5a to 5c are arranged so as to be in contact with the side surfaces of the chip component 3 in the substrate thickness direction (Z direction). Has been. The intermediate insulating materials 5 a to 5 c are insulating materials having a thermal expansion coefficient in the substrate thickness direction (Z direction) between the thermal expansion coefficient of the insulating base material 1 and the thermal expansion coefficient of the chip component 3. The chip parts 3 of the multilayer circuit boards 100 and 101 in FIGS. 1A and 1B have a substantially rectangular parallelepiped shape. In the multilayer circuit board 100 in FIG. 1A, the intermediate insulating materials 5 a and 5 b are the chip parts 3. Are arranged so as to contact four side surfaces in the substrate thickness direction (Z direction). In particular, in the multilayer circuit board 101 of FIG. 1B, the intermediate insulating material 5c is arranged so as to surround four side surfaces of the chip component 3 in the board thickness direction.

  As shown in FIGS. 10 and 11, a plurality of resin films made of thermoplastic resin are bonded to each other to form an insulating base material 1, and a chip component 3 is embedded in the insulating base material 1. The conventional multilayer circuit board 90 has a structure in which the insulating base 1 made of a plurality of resin films and the chip component 3 are in direct contact with each other. When a simulation was performed on the conventional multilayer circuit board 90 having this structure, as shown in FIG. 11, the portion of the insulating base material 1 that was in contact with the vicinity of the central portion in the thickness direction of the chip component 3 became a stress concentration portion. A stress of about 25 to 30 MPa was generated. For this reason, even in the conventional multilayer circuit board 90 actually manufactured, the insulating base material 1 on the long side of the chip component to which the maximum stress of about 30 MPa is applied is likely to be cracked due to changes over time. It was.

  Therefore, as a result of analyzing the stress shown in FIG. 11 of the multilayer circuit board 90, it was concluded that the stress is generated due to the following factors. That is, the chip component 3 such as a resistor or a capacitor generally has a thickness of 0.1 mm or more in general and is often made of a ceramic material, so that the linear expansion coefficient tends to be as low as 10 ppm or less. There is. On the other hand, in the insulating base material 1 in which a plurality of resin films made of thermoplastic resin of the multilayer circuit board 90 are bonded to each other, the linear expansion coefficient in the substrate surface is the linear expansion coefficient of the conductor pattern 2 made of copper. The linear expansion coefficient in the thickness direction is generally several times to several tens of times the linear expansion coefficient in the substrate surface. For this reason, the portion of the insulating base material 1 that is in contact with the vicinity of the central portion in the thickness direction of the chip component 3 due to the difference in linear expansion coefficient between the chip component 3 and the insulating base material 1 in the multilayer circuit board 90 is stressed. It became a concentrated part, and it was found that a stress of about 25 to 30 MPa was generated.

  For this reason, in the multilayer circuit boards 100 and 101 shown in FIGS. 1A and 1B, the thermal expansion coefficient in the board thickness direction (Z direction) is the thermal expansion coefficient of the insulating base material 1 and the heat of the chip component 3. The intermediate insulating materials 5 a to 5 c that are in the middle of the expansion rate are arranged so as to contact the side surface of the chip component 3 in the substrate thickness direction (Z direction). Accordingly, the difference in linear expansion coefficient between the chip component 3 and the insulating base material 1 in the thickness direction is relaxed by the intermediate insulating materials 5a to 5c, and the stress applied to the insulating base material 1 around the chip component 3 is reduced. Can do. As exemplified in the multilayer circuit board 100 of FIG. 2, according to the simulation, for example, the intermediate insulating materials 5a and 5b having a linear expansion coefficient of 17 ppm to 20 ppm are insulated from the chip component 3 having the linear expansion coefficient of 10 ppm. By interposing it with the material 1, the stress applied to the insulating base 1 around the chip component 3 can be reduced to about 13 to 16 MPa. For this reason, even in the multilayer circuit board 100 that is actually manufactured, cracks are unlikely to occur due to changes over time, and the multilayer circuit board 100 is a highly reliable multilayer circuit board.

  As described above, in the multilayer circuit boards 100 and 101 shown in FIGS. 1A and 1B, the insulating base material 1 is formed by bonding the resin films made of thermoplastic resin to each other. 1 is a multilayer circuit board in which the chip component 3 is embedded, and the insulating substrate 1 around the chip component 3 is less likely to crack.

  In the multilayer circuit boards 100 and 101 of FIGS. 1A and 1B, the intermediate insulating materials 5a and 5b are in contact with four side surfaces of the substantially rectangular parallelepiped chip component 3, or the intermediate insulating material 5c is The chip parts 3 are arranged so as to surround the four side surfaces. As a result, the stress applied to the insulating substrate 1 around the chip component 3 can be evenly reduced around the four side surfaces. However, the present invention is not limited to this. For example, the intermediate insulating material may be disposed only on the two long side surfaces of the chip component 3 facing each other. Further, not only the substantially rectangular chip part 3 but also a cylindrical chip part, for example, even if an intermediate insulating material is disposed so as to contact the side surface in the substrate thickness direction, a similar stress reduction effect is obtained. be able to.

  Further, in the multilayer circuit boards 100 and 101 of FIGS. 1A and 1B, the intermediate insulating materials 5 a to 5 c are arranged so as to be in contact with the entire region of the side surface of the chip component 3. However, the intermediate insulating material does not necessarily have to contact the entire area of the side surface of the chip component 3.

  FIG. 3 is a diagram showing an example of another multilayer circuit board, and is a schematic partial cross-sectional perspective view showing the periphery of the chip component 3 in the multilayer circuit board 102 in an enlarged manner. FIG. 3 is also a 1/8 diagram in which the periphery of the chip component 3 in the multilayer circuit board 102 is divided into a cross section XY, a cross section YZ, and a cross section ZX, as in FIGS. Yes.

  In the multilayer circuit board 102 of FIG. 3, the intermediate insulating material 5 d abuts on a thickness region of 1/3 or more including the central portion (cross section XY) in the thickness direction (Z direction) on the side surface of the chip component 3. It is arranged like that. In other words, as shown in FIG. 3, when the height (thickness) of the chip component 3 is h and the height of the intermediate insulating material 5d is d, the intermediate insulating material 5d is located at the center of the chip component 3. It arrange | positions so that it may become d> = h / 3 including a part (cross section XY). For example, if the height h of the chip component 3 is 300 μm, the intermediate insulating material 5d having a height d of 100 μm or more is disposed so as to contact the side surface so as to include the central portion (cross section XY) of the chip component 3. To do.

  As shown in the simulation results of FIG. 2B and FIG. 11B, the stress generated by the difference in linear expansion coefficient between the chip component 3 and the insulating base 1 in the thickness direction is the thickness of the chip component 3. The vicinity of the central portion (cross section XY) in the vertical direction is a stress concentration portion. Therefore, according to the simulation, as shown in the multilayer circuit board 102 shown in FIG. 3, the intermediate insulating material 5d is applied to a thickness region of 1/3 or more including the central portion in the thickness direction on the side surface of the chip component 3. Even if it arrange | positions so that it may contact, the remarkable stress reduction effect is acquired.

  In the multilayer circuit board, the width of the intermediate insulating material in the substrate surface is preferably 1/10 or more of the thickness of the chip component. That is, as exemplified in the multilayer circuit board 102 of FIG. 3, the width t of the intermediate insulating material 5 d is preferably t ≧ h / 10 with respect to the height h of the chip component 3. For example, if the height of the chip part 3 is 300 μm, the width t of the intermediate insulating material 5d is set to 30 μm or more. From the viewpoint of the stress reduction effect, it is desirable that the width t of the intermediate insulating material is thicker. However, according to the simulation, by setting the width t of the intermediate insulating material to 1/10 or more of the thickness of the chip component as described above, A remarkable stress reduction effect can be obtained.

  FIG. 4 is also a diagram showing an example of another multilayer circuit board, and is a schematic partial cross-sectional perspective view of 1/8 showing the periphery of the chip component 3 in the multilayer circuit board 103 in an enlarged manner. In FIG. 1 and FIG. 3, the multilayer circuit boards 100 to 102 did not clearly show the resin film before bonding that constitutes the insulating base 1, but in the multilayer circuit board 103 of FIG. The resin films 1a to 1d before bonding to be configured are clearly shown, and boundaries thereof are indicated by broken lines.

  The multilayer circuit board 103 shown in FIG. 4 is disposed in contact with the side surface of the chip component 3, and has an intermediate insulating material 5e having a thermal expansion coefficient intermediate between the insulating base material 1 and the chip component 3 in the substrate thickness direction. , 5f, the same resin film as the resin films 1a to 1d constituting the insulating base material 1 is used.

  First, resin films 1a to 1d, which are constituent elements of the multilayer circuit board 103 shown in FIG. 4, will be described in detail with reference to FIGS.

  FIG. 5 is a view showing a sheet material 10 that is a cut material of the resin films 1a to 1d, and FIG. 5 (a) is a view showing an appearance of the sheet material 10 from which a roll-shaped tip is drawn. FIG. 2B is a perspective view schematically showing the fine structure of the sheet material 10.

  Moreover, Fig.6 (a) is a figure which showed an example of the cut-out state of resin film 1a-1d from the sheet | seat raw material 10, and FIG.6 (b) is orientation of the fibrous molecule FM in the cross section of the resin film 1a. It is the expanded view which showed sex. 6 is a through hole formed in the resin films 1a and 1b for inserting the chip component 3 and the intermediate insulating materials 5e and 5f shown in FIG.

  In the multilayer circuit board 103 of FIG. 4, the resin films 1a to 1d constituting the insulating base material 1 are usually cut out from the sheet material 10 shown in FIG. 5 (a) manufactured by a sheet molding machine using a roller or the like. used. Further, the microstructure of the thermoplastic resin is generally an aggregate of fibrous molecules FM that are constituent components of the thermoplastic resin. Therefore, in the sheet material 10 manufactured using the roller or the like, as shown in FIG. 5B, the long axis direction is substantially parallel to the direction in which the fibrous molecules FM flow in the sheet forming machine. Will be arranged side by side. Accordingly, the sheet material 10 manufactured using a roller or the like is the above in the sheet forming machine in the flow direction (MD, Machine Direction) and the width direction (TD, Traverse Direction) of the sheet material 10 in the sheet forming machine. It becomes an anisotropic sheet material reflecting the orientation of the fibrous molecule FM. Therefore, even in the resin film of the constituent elements of the multilayer circuit board cut out in any direction with respect to the sheet material 10, the fibrous molecules FM are arranged so that the major axis direction is substantially parallel within the film plane of the resin film. The resin film is generally arranged in a line, and the direction of the resin film, which is the average of the major axis directions of the fibrous molecules FM, is MD, and the direction of the resin film perpendicular to MD is the TD. And TD are anisotropic films having a direction difference in linear expansion coefficient and strength. Needless to say, also in the thickness direction ZD of the resin film (sheet material), the linear expansion coefficient or strength is a value different from MD and TD.

  Specifically, for example, in the resin films 1a to 1d of FIG. 6, the fibrous molecules FM are arranged side by side with the major axis direction substantially parallel to the short side direction of the resin films 1a to 1d. As described above, in the resin films 1a to 1d in which the fibrous molecules FM are arranged so that the major axis directions thereof are substantially parallel to each other, the direction in the film plane of the resin films 1a to 1d is as described above. MD which averaged the major axis direction of molecule | numerator FM and TD of the direction perpendicular | vertical to this MD can be defined. Moreover, as shown in FIG.6 (b), as a cross section of resin film 1a-1d, the MD cross section cut | disconnected by MD and including the major axis direction of the fibrous molecule FM in a cross section, and the cross section cut | disconnected by TD A TD cross section in which the major axis directions of the fibrous molecules FM intersect perpendicularly can be defined. Therefore, as can be seen from FIG. 6B, in the chip part 3 formed in the resin films 1a and 1b and the through holes H3 of the intermediate insulating materials 5e and 5f, the long side is the MD cross section and the short side is the TD cross section. Become.

  In the measurement examples of the MD and ZD linear expansion coefficients of the resin films 1a to 1d, the linear expansion coefficient of MD was about 18 ppm, whereas the linear expansion coefficient of ZD was about 200 ppm. The linear expansion coefficient of TD was about 20 ppm. Moreover, in the measurement example of the tensile strength of MD and ZD of the resin films 1a to 1d, the tensile strength of MD was about 140 MPa, whereas the tensile strength of ZD was 20 MPa (TD cross section) to 35 MPa (MD cross section). Met.

  By utilizing the anisotropy of the resin films 1a to 1d, the multilayer circuit board 103 of FIG. 4 uses a resin film cut out from the same sheet material 10 as the resin films 1a to 1d as the intermediate insulating materials 5e and 5f. The resin film MD is arranged so as to be in contact with the side surface of the chip component 3 so that the MD of the resin film is in the substrate thickness direction (Z direction).

  7 (a) and 7 (b), the difference in the orientation of each resin film around the chip component 3 in the multilayer circuit board 103 shown in FIG. 4 and the conventional multilayer circuit board 90 shown in FIG. Comparison was made using the fibrous molecules FM constituting the resin film.

  In the multilayer circuit board 103 of FIG. 4, since the resin films 1a to 1d constituting the insulating base material 1 and the resin films used as the intermediate insulating materials 5e and 5f can be cut out from the same sheet material 10, they are the same material. Even when the resin films made of a thermoplastic resin are heated and pressed to adhere to each other, a uniform joint can be formed. Further, by arranging the resin film with the above azimuth relationship as the intermediate insulating materials 5e and 5f, it is possible to have the stress reduction effect due to the relaxation of the thermal expansion difference described above. Furthermore, the arrangement of the resin film having the orientation relationship as the intermediate insulating materials 5e and 5f is an arrangement in which the stress generated by the difference in thermal expansion is received by the MD having high tensile strength.

  As described above, in each of the multilayer circuit boards 100 to 103, the insulating base material 1 is formed by bonding the resin films made of thermoplastic resin to each other, and the chip component 3 is formed in the insulating base material 1. Is a multilayer circuit board in which cracks are unlikely to occur in the insulating base material 1 around the chip component.

  Next, the method for manufacturing the multilayer circuit board will be described using the multilayer circuit board 103 of FIG. 4 as an example. FIGS. 8A and 8B are schematic partial cross-sectional perspective views showing states of the multilayer circuit board 103 of FIG. 4 being manufactured.

  In manufacturing the multilayer circuit board 103 of FIG. 4, first, as shown in FIG. 6A, in the resin film preparation process, through-holes for inserting the chip component 3 and the intermediate insulating materials 5e and 5f are inserted. Resin films 1a and 1b on which H3 is formed are prepared. Next, as shown in FIG. 8A, in the resin film laminating step, a plurality of prepared resin films 1a and 1b are laminated. Next, as shown in FIG. 8B, in the chip component arranging step, the chip component 3 and the intermediate insulating materials 5e and 5f are inserted and arranged in the through hole H3. Next, after laminating the resin films 1c and 1d on the laminate of FIG. 8B, in the final heating and pressing step, the laminate of the laminated resin films 1a to 1d is heated while being pressed from both sides, The resin films 1 a to 1 d are bonded to each other to form the insulating base 1, and the chip component 3 and the intermediate insulating materials 5 e and 5 f inserted and disposed in the through hole H 3 are embedded in the insulating base 1. Thereby, the multilayer circuit board 103 of FIG. 4 can be manufactured.

  Since the method for manufacturing the multilayer circuit board can perform bonding of the resin films 1a to 1d and embedding of the chip component 3 and the intermediate insulating materials 5e and 5f all at once by one heating and pressurization, the multilayer circuit board Can be manufactured at low cost.

  In the above-described multilayer circuit board manufacturing method, various methods can be used to insert and arrange the intermediate insulating material in the predetermined through hole. For example, in the chip component arranging step of FIG. 8B, the resin film is placed on the side surface of the chip component 3 so that the MD of the resin film serving as an intermediate insulating material is in the substrate thickness direction (Z direction) of the chip component 3. You may make it insert and arrange | position in a predetermined through-hole in the state wound around. According to this, a multilayer circuit board similar to the multilayer circuit board 101 shown in FIG. 1B can be manufactured. Further, for example, in a state where the chip component 3 is inserted and arranged in a predetermined through-hole, it is also possible to insert and arrange the material as an intermediate insulating material.

  FIG. 9 is a diagram showing a method for manufacturing a multilayer circuit board 104 similar to the multilayer circuit board 103 shown in FIG. FIGS. 9A and 9B are schematic partial cross-sectional perspective views showing states of the multilayer circuit board 104 in the middle of manufacture.

  In the method of manufacturing the multilayer circuit board 104 shown in FIGS. 9A and 9B, the intermediate insulating materials 5g and 5h are inserted and arranged in the through holes H4 of the laminated resin films 1e to 1i in the chip component arranging step. In doing so, a part of the resin films 1h and 1i disposed above or below the through hole H4 is inserted and disposed so as to be bent by the chip component 3 into the through hole H4. As a result, the MD of the bent portions of the resin films 1h and 1i becomes the substrate thickness direction (Z direction), and the multilayer circuit board 104 used as the intermediate insulating materials 5g and 5h can be manufactured.

  As described above, the multilayer circuit board and the method for manufacturing the multilayer circuit board are multilayer films in which resin films made of thermoplastic resin are bonded to each other to form an insulating base material, and chip components are embedded in the insulating base material. A circuit board and a manufacturing method thereof are a multilayer circuit board and a manufacturing method thereof in which cracks are unlikely to occur in an insulating base material around a chip component.

(A), (b) is the figure which showed the example of the multilayer circuit board which concerns on this invention, respectively, The typical partial cross-section perspective view which expanded the periphery of the chip components 3 in the multilayer circuit boards 100 and 101, and was shown. FIG. FIG. 3 is an example of a result of simulating stress applied to the insulating base material 1 around the chip component 3 for the multilayer circuit board 100 of FIG. (A) is a perspective view of a 1/8 analysis model including a wider range than that in FIG. 1 (a), and (b) is an insulating substrate 1 around the side surface of the chip component 3. It is the figure which showed the simulation result of this stress by the iso-stress line. FIG. 10 is a diagram showing an example of another multilayer circuit board, and is a schematic partial cross-sectional perspective view showing an enlargement of the periphery of the chip component 3 in the multilayer circuit board 102. FIG. 10 is a diagram showing another example of the multilayer circuit board, and is a schematic partial cross-sectional perspective view of 1/8 showing the periphery of the chip component 3 in the multilayer circuit board 103 in an enlarged manner. It is a figure which shows the sheet raw material 10 which is the cutting material of resin film 1a-1d, (a) is a figure which shows the external appearance of the sheet raw material 10 by which the roll-shaped front-end | tip was pulled out, (b) is a sheet raw material 10 It is the perspective view which showed typically the fine structure. (A) is the figure which showed an example of the cut-out state of resin film 1a-1d from the sheet | seat raw material 10, (b) is the expanded view which showed the orientation of the fibrous molecule FM in the cross section of the resin film 1a. It is. (A), (b) shows the difference in orientation of each resin film around the chip component 3 between the multilayer circuit board 103 shown in FIG. 4 and the conventional multilayer circuit board 90 shown in FIG. It is the figure shown in comparison using the fibrous molecule | numerator FM which comprises the film. (A), (b) is the typical partial cross-sectional perspective view which showed each state of the multilayer circuit board 103 of FIG. 4 in the middle of manufacture, respectively. FIGS. 5A and 5B are diagrams illustrating a method of manufacturing a multilayer circuit board 104 similar to the multilayer circuit board 103 illustrated in FIG. 4. FIGS. 5A and 5B are diagrams illustrating states of the multilayer circuit board 104 in the process of manufacturing. It is the typical fragmentary sectional perspective view which showed. It is a figure which shows an example of the conventional multilayer circuit board, (a) is the top view which showed the multilayer circuit board 90 typically. Moreover, (b) and (c) are the figures which respectively showed the cross section of the dashed-dotted line AA and the dashed-two dotted line BB in (a) with the photograph of the real thing. FIG. 11 is an example of a result of simulating the stress applied to the insulating base material 1 around the chip component 3 for the multilayer circuit board 90 of FIG. 10. (A) is a perspective view of a 1/4 analysis model, (b) is the figure which showed the simulation result by the iso-stress line.

Explanation of symbols

90, 100 to 104 Multilayer circuit board 1 Insulating substrate 1a to 1i Resin film 3 Chip component 5a to 5g Intermediate insulating material 10 Sheet material FM Fibrous molecule H3, H4 Through hole

Claims (11)

In a multilayer circuit board in which resin films made of thermoplastic resin are bonded to each other to form an insulating base, and chip components are embedded in the insulating base,
Arranged so that an intermediate insulating material whose thermal expansion coefficient in the substrate thickness direction is intermediate between the thermal expansion coefficient of the insulating base and the thermal expansion coefficient of the chip component contacts the side surface of the chip component in the substrate thickness direction. A multilayer circuit board characterized by being made. The chip component has a substantially rectangular parallelepiped shape;
2. The multilayer circuit board according to claim 1, wherein the intermediate insulating material is disposed so as to abut on four side surfaces of the chip component in the substrate thickness direction.   3. The multilayer circuit board according to claim 2, wherein the intermediate insulating material is disposed so as to surround four side surfaces of the chip component in the substrate thickness direction.   4. The intermediate insulating material according to claim 1, wherein the intermediate insulating material is disposed so as to abut on a thickness region of 1/3 or more including a central portion in a thickness direction on a side surface of the chip component. The multilayer circuit board according to any one of the above.   5. The multilayer circuit board according to claim 4, wherein the intermediate insulating material is disposed so as to be in contact with an entire region of a side surface of the chip component.   6. The multilayer circuit board according to claim 1, wherein a width of the intermediate insulating material in the substrate surface is 1/10 or more of a thickness of the chip component. 7. In the film surface of the resin film, the fibrous molecules constituting the resin film are arranged side by side with the major axis direction of the fibrous molecules being substantially parallel,
When the direction of the resin film averaged in the long axis direction of the fibrous molecule is MD, and the direction of the resin film perpendicular to the MD is TD,
The resin film is an anisotropic film having a difference in linear expansion coefficient or strength between the MD and the TD,
The resin film is arranged so that the MD of the resin film is in the substrate thickness direction, and the resin film is in contact with the side surface of the chip component in the substrate thickness direction,
The multilayer circuit board according to claim 1, wherein the resin film is used as the intermediate insulating material. In a multilayer circuit board in which resin films made of thermoplastic resin are bonded to each other to form an insulating base, and chip components are embedded in the insulating base,
Arranged so that an intermediate insulating material whose thermal expansion coefficient in the substrate thickness direction is intermediate between the thermal expansion coefficient of the insulating base and the thermal expansion coefficient of the chip component contacts the side surface of the chip component in the substrate thickness direction. A method for producing a multilayer circuit board, comprising:
A resin film preparing step of preparing the resin film in which a through hole for inserting the chip component and the intermediate insulating material is formed;
A resin film laminating step for laminating a plurality of the resin films;
A chip component arranging step of inserting and arranging the chip component and the intermediate insulating material in the through hole;
The laminated body of the laminated resin films is heated while being pressurized from both sides, and the resin films are bonded to each other to form the insulating base material, and the chip component inserted and disposed in the through hole and the intermediate A method of manufacturing a multilayer circuit board, comprising: a heating and pressing step of embedding an insulating material in the insulating base material. In the film surface of the resin film, the fibrous molecules constituting the resin film are arranged side by side with the major axis direction of the fibrous molecules being substantially parallel,
When the direction of the resin film averaged in the long axis direction of the fibrous molecule is MD, and the direction of the resin film perpendicular to the MD is TD,
The resin film is an anisotropic film having a difference in linear expansion coefficient or strength between the MD and the TD,
The multilayer circuit board comprises:
The resin film is arranged so that the MD of the resin film is in the substrate thickness direction, and the resin film is in contact with the side surface of the chip component in the substrate thickness direction,
The method for producing a multilayer circuit board according to claim 8, wherein the resin film is a multilayer circuit board used as the intermediate insulating material. In the chip component placement step, in placing the intermediate insulating material in the through hole,
10. The method for manufacturing a multilayer circuit board according to claim 9, wherein a part of the resin film disposed above or below the through hole is inserted and disposed so as to be bent into the through hole. In the chip component placement step, in placing the intermediate insulating material in the through hole,
The resin film is inserted and disposed in the through hole in a state where the resin film is wound around a side surface of the chip component so that the MD of the resin film is in the substrate thickness direction of the chip component. A method for producing a multilayer circuit board according to claim 9.

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