JP2012191101A - Manufacturing method of circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board having a double side structure or a multilayer structure which has high density and an excellent wiring housing function and achieves stable interlayer electrical connection.SOLUTION: A circuit board for an inner layer electrically connects with an outer layer circuit through conduction holes of an insulation base material for interlayer connection, and a hardening part is selectively formed on the insulation base material for the interlayer connection. The structure minimizes variations caused in the manufacturing processes of the circuit board, dimension changes of the insulation base material or the insulation base material for the interlayer connection, and the like and improves the positioning accuracy of the lamination of the circuit board having the multilayer structure.

Description

  The present invention relates to a method of manufacturing a circuit board in which both surfaces or multilayer layers are electrically connected through a conduction hole.

  In recent years, with the downsizing and higher performance of electronic devices, multilayer circuit boards capable of mounting LSI chips and other semiconductor chips at a high density have been supplied at low cost not only for industrial use but also in the field of consumer equipment. Has been strongly requested. In such a multilayer circuit board, it is important that a plurality of layers formed with a fine wiring pitch can be electrically connected with high connection reliability.

  Conventionally, in response to such market demand, an all-layer IVH structure capable of interlayer connection at an arbitrary position instead of the metal plating conductor on the inner wall of the through hole, which has been the mainstream of interlayer connection of conventional multilayer circuit boards, The so-called inner via hole connection method has attracted attention.

  In the above-described structure, it is possible to connect only the necessary layers, and the inner via hole can be provided directly under the component mounting land, so that the substrate size can be reduced and high-density mounting can be realized. be able to. Further, since the electrical connection in the inner via hole uses a conductive paste, the stress applied to the via hole can be relieved and a stable electrical connection can be realized against a dimensional change due to a thermal shock or the like. .

  This multi-layer circuit board having an all-layer IVH structure is manufactured by a process as shown in FIG. This conventional circuit board manufacturing method will be described below.

  First, as shown to Fig.5 (a), the PET film 24 is affixed on both sides of the insulating base material 21 by a lamination. As the insulating base material 21, a porous base material having compressibility, a three-layer structure in which an adhesive layer is formed on both sides of the core film, a composite base material of fiber and resin, or the like is used. .

  Since the insulating base material 21 and the PET film 24 are bonded at a high temperature during the above-described lamination, stress due to the difference in thermal expansion coefficient between the insulating base material 21 and the PET film 24 is generated at the interface between them. Yes.

  Next, as shown in FIG. 5B, through holes 25 are formed in the insulating base material 21 and the PET film 24 by laser processing or the like.

  Next, as shown in FIG. 5 (c), the conductive paste 26 is filled in the through holes 25. The PET film 24 serves to prevent the conductive paste 26 from remaining on the surface of the insulating base material 21.

  Next, as shown in FIG. 5D, the PET films 24 on both sides are peeled off. In this peeling process, since the stress between the two that has been generated when the PET film 24 is formed on the insulating base material 21 is released, a dimensional change occurs in the insulating base material 21.

  Next, as shown in FIG. 5 (e), the copper foil 28 is laminated from both sides of the insulating base material 21, and the copper foil 28 is insulated by heating and pressing as shown in FIG. 5 (f). Adhere to 21. At this time, since the insulating substrate 21 contracts in the thickness direction, the conductive paste 26 is also compressed in the thickness direction. As a result, the metal fillers in the conductive paste 26 come into contact with each other at high density, and the copper foil 28 and the conductive paste 26 are electrically connected.

  Next, as shown in FIG. 5G, a circuit 29 is formed on the copper foil 28 to obtain a double-sided circuit board 30.

  Next, as shown in FIG. 6 (a), an insulating substrate for interlayer connection in which conductive paste 26 formed in the same process as in FIGS. 5 (a) to 5 (d) is filled on both sides of the circuit board 30. 22 and copper foil 28 are laminated. The insulating base material 22 for interlayer connection also has a dimensional change when the PET film 24 is peeled off, as in the above example.

  Next, as shown in FIG. 6B, the copper foil 28, the insulating base material 22, and the circuit board 30 are bonded by heating and pressing.

  In this heating and pressurizing step, the insulating base material 22 contracts in the thickness direction, the conductive paste 26 is compressed in the thickness direction, and the copper foil 28 and the circuit 29 of the circuit board 30 are electrically connected.

  Next, a multilayered circuit board 40 shown in FIG. 6C is obtained by forming a circuit on the surface copper foil 28.

  For example, Patent Document 1 is known as prior art document information related to the invention of this application.

JP 2009-188311 A

  However, in the conventional circuit board manufacturing method, the PET film laminated on the surface of the insulating substrate is used in addition to the dimensional change at the time of circuit formation or heating and pressurization, and the variation in the processing position accuracy of the through hole. When it peels, the dimensional change etc. of an insulating base material arise.

  This makes it difficult to match the connection lands formed in the circuit with the conduction holes provided in the insulating base material, and when it is extremely bad, there is a possibility that insulation failure occurs between adjacent circuits.

  In order to solve this, it was considered to increase the land diameter for connection so as to allow variation in processing in the above process and dimensional change of the insulating base material. It was contradictory in improving the property. In particular, when the diameter of the conductive hole is reduced, the circuit is thinned, or the thickness of the insulating base material is reduced, the above problem becomes remarkable, which is a problem in manufacturing a high-definition multilayer circuit board.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described conventional problems and to provide a double-sided or multilayer circuit board having a high density and high wiring capacity.

  In order to achieve the above object, a method of manufacturing a circuit board according to the present invention includes a step of preparing a semi-cured insulating base, a step of selectively forming a cured portion on the insulating base, and the insulating base. The method includes a step of forming a conduction hole in the material, a step of laminating a metal foil on the surface of the insulating base material, heating and pressing, and a step of forming a circuit on the metal foil.

  A step of preparing an inner layer circuit board and a semi-cured interlayer connection insulating base material; a step of selectively forming a cured portion on the interlayer connection insulating base material; and the interlayer connection insulating base material. A step of forming a conductive hole, a step of laminating a metal foil on the inner layer circuit board, the interlayer connecting insulating base material and the outermost layer, a step of heating and pressing the metal foil, and a step of forming a circuit on the metal foil Are provided.

  The structure of the circuit board of the present invention has a cured portion selectively formed in the insulating base material or the insulating base material for interlayer connection. Therefore, it is possible to minimize the dimensional change of the insulating base material for use and improve the positioning and stacking accuracy of the circuit board having a multilayer structure.

  Thereby, the formation position of a conduction hole or a wiring circuit can be stabilized, and a high-definition all-layer IVH structure wiring board can be provided. Furthermore, the same effect can be obtained even when the conductor is miniaturized and the insulating base material is thinned.

Sectional drawing which shows the process of the manufacturing method of the circuit board in embodiment of this invention Schematic which shows one process of the manufacturing method of the circuit board in the embodiment Sectional drawing which shows the process of the manufacturing method of the circuit board in the embodiment Schematic which shows one process of the manufacturing method of the circuit board in the embodiment Sectional drawing which shows the process of the manufacturing method of the conventional circuit Sectional drawing which shows the process of the manufacturing method of the conventional circuit

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1A to 1I are process cross-sectional views illustrating a circuit board manufacturing method according to an embodiment of the present invention.

  First, as shown to Fig.1 (a), the semi-hardened state (B stage state) insulating base material 1 is prepared.

  In this embodiment, a 60 μm-thick glass fiber woven fabric and an epoxy resin composite material are used as the insulating substrate 1. As the insulating substrate 1, in addition to glass fibers, a composite material with a thermosetting resin or the like can be used for an aramid woven fabric or a nonwoven fabric substrate. Moreover, you may use a polyimide film, an aramid film, a liquid crystal polymer film, etc.

  As will be described later, the insulating base material 1 can also be used as an insulating base material 2 for interlayer connection in the manufacture of a circuit board having a multilayer structure.

  Next, as shown in FIG. 1B, the cured portion 3 is selectively formed on the insulating base material 1.

  The hardened portion 3 can be performed by laser processing, and is preferably formed in a linear shape or a strip shape. The laser processing conditions in this case are performed under laser energy conditions that do not destroy the base material such as glass fiber in the insulating base material 1, or under conditions where the focus is shifted and only the resin is cured in a band shape.

  Thereby, when a part of the semi-cured insulating base material 1 is cured, the dimensions can be stabilized, and distortion of the dimensions can be prevented.

  Moreover, the hardening part 3 can be formed into a concave shape by heating and pressurizing the insulating base material 1 or the interlayer connecting insulating base material 2 with a heating means, thereby stabilizing the dimensions and will be described later. In the laminating and heating / pressing process, the flow of resin can be prevented, and so-called “via collapse” (conduction hole tilt / deformation due to resin flow) can be formed, and the interlayer connection can be stabilized. Has the effect of being able to.

  In addition, the presence of the cured portion 3 in the semi-cured insulating base material 1 or the interlayer connection insulating base material 2 makes it difficult for distortion and deformation to occur even when tension is applied to the base material in the laminating process described later. . That is, due to the presence of the cured portion 3 where the resin is cured, the elastic modulus of the entire base material is reduced, variation in the manufacturing process of the circuit board, and dimensional change of the insulating base material 1 or the insulating base material 2 for interlayer connection. Etc. can be minimized.

  Further, the circuit board according to the embodiment of the present invention has a product part region P to be a product on which electronic components and the like are mounted and an outer shape in the final stage of the manufacturing process as shown in FIG. It is preferable that the hardened portion 3 is formed in the non-product portion region R by being divided into non-product portion regions R that are removed by processing or removed after being mounted on the electronic device after being mounted.

  Thereby, the influence on the circuit and conduction | electrical_connection hole by the hardening part 3 being formed can be excluded.

  In particular, by forming the hardened portion 3 near the boundary between the product portion region P and the non-product portion region R, it is effective in stabilizing the dimensions in the product portion region P efficiently with a small area.

  Note that the vicinity of the boundary includes an area on the boundary line Q between the product part region P and the non-product part region R, but does not belong to the product part region P.

  When the boundary is on the outer shape processing line of the product portion, the dimension in the product portion region P can be more effectively stabilized by forming the hardened portion 3 in the vicinity thereof.

  In forming the hardened portion 3 in the vicinity of the outer shape processing line of the product portion, it can be easily and accurately formed at an accurate position by using the laser processing described above.

  Next, as shown in FIG.1 (c), the PET film 4 is affixed on both sides of the insulating base material 1 which has the hardening part 3 by lamination.

  During the lamination, the insulating base material 1 and the PET film 4 are bonded at a high temperature, and therefore stress is generated at the interface between the insulating base material 1 and the PET film 4 due to the difference in thermal expansion coefficient between the insulating base material 1 and the PET film 4. However, the stress value decreases due to the presence of the hardened portion 3.

  Next, as shown in FIG.1 (d), the through-hole 5 is formed in the insulating base material 1 and the PET film 4 by laser processing etc. FIG.

  Next, as shown in FIG. 1E, the through-hole 5 is filled with a conductive paste 6. The PET film 4 serves to prevent the conductive paste 6 from remaining on the surface of the insulating base 1. The conductive paste 6 is mainly composed of a metal filler such as copper powder and a thermosetting resin.

  Next, as shown in FIG. 1 (f), the PET films 4 on both sides are peeled, and the through holes 5 are filled with the conductive paste 6 to form the conductive holes 7 in the uncured state.

  In this peeling process, since the stress between the PET film 4 and the insulating base material 1 generated when the PET film 4 is formed on the insulating base material 1 is released, the insulating base material 1 usually undergoes a dimensional change. The value of the change decreases due to the presence of the hardened portion 3.

  Next, as shown in FIG. 1 (g), copper foils 8 as metal foils are laminated on both sides of the insulating substrate 1, and heated and pressurized as shown in FIG. Adhere to material 1. At this time, since the insulating substrate 1 contracts in the thickness direction, the conductive paste 6 in the through hole 5 is also compressed in the thickness direction. As a result, the metal fillers in the conductive paste 6 come into contact with each other at high density, and the copper foils 8 on both sides are electrically connected through the conduction holes 7.

  Next, as shown in FIG. 1I, a circuit 9 is formed on the copper foil 8 to obtain a circuit board 10 on both sides.

  Note that the cured portion 3 selectively formed on the semi-cured insulating base material 1 provided with the conduction holes is formed by the heating and pressurization in the step of FIG. It seems that it becomes difficult to distinguish the non-cured part, but in fact, it can be left by heating and alteration when it is formed into a linear or belt-shaped cured part by laser processing. It is also possible to leave the insulating base material by heating and pressing it with a heating means to form a concave shape.

  Next, a method of manufacturing a multilayer circuit board will be described with reference to the drawings.

  3A to 3C are process cross-sectional views illustrating a method for manufacturing a circuit board according to an embodiment of the present invention.

  First, as shown in FIG. 3A, an inner layer circuit board 11 having circuits on both sides and a semi-cured interlayer connection insulating base material 2 are prepared.

  The inner layer circuit board 11 may be a copper through-hole wiring board that is conductive on both sides by plating or the like, but the double-sided circuit board 10 manufactured in the steps of FIGS. Is desirable.

  The inner layer circuit board 11 in the present embodiment has a high density and high wiring capacity, and has a stable dimension due to the presence of the hardened portion 3 selectively formed on the insulating base material 1.

  Further, the insulating base material 2 for interlayer connection is formed in the process of FIGS. 1A to 1F, that is, the cured portion 3 is selectively formed on the insulating base material 1, and the PET is formed on both sides of the insulating base material 1. After laminating film 4, through-hole 5 is formed, conductive paste 6 is filled in through-hole 5, and conductive film 7 obtained by peeling PET film 4 is used as insulating base material 2 for interlayer connection. Used as

  As in the case of the insulating base material 1, the interlayer connecting insulating base material 2 also undergoes a dimensional change when the PET film 4 is peeled off. The value becomes smaller.

  Next, as shown in FIG. 3A, the interlayer connection insulating base 2 and the copper foil 8 as the metal foil are laminated on both sides of the circuit board as the inner layer circuit board 11. In addition, in the lamination, a plurality of inner layer circuit boards 11 and interlayer connection insulating base materials 2 are prepared, and they are alternately laminated while being aligned, and the copper foil 8 is laminated on the outermost layer. Good.

  The conduction hole 7 of the interlayer connection insulating substrate 2 positioned and fixed to the inner layer circuit board 11 recognizes the position of the land 12 formed in the inner layer circuit board 11, and the conduction hole 7 is the center of the land 12. Alternatively, the positioning is fixed so as not to protrude from at least the land 12.

  Further, in the above-described laminating step, as shown in FIG. 4, it can be performed while applying a tension T to the cured portion 3 formed on the interlayer connection insulating base 2.

  That is, by applying tension T to the interlayer connection insulating base material 2 in the B stage state so that the recognition marks formed on the inner layer circuit board 11 and the interlayer connection insulating base material 2 match each other, the dimensions can be reduced. Can be adjusted.

  In particular, since the cured portion 3 is formed, it is possible to prevent the interlayer connection insulating base material 2 from being greatly elongated or deformed due to the influence of the tension T as compared with the case where the cured portion 3 is not formed. it can.

  Next, as shown in FIG. 3B, the copper foil 8 and the inner layer circuit board 11 are bonded and cured through the interlayer connection insulating substrate 2 by heating and pressing.

  In this heating and pressurizing step, the interlayer connection insulating base material 2 shrinks in the thickness direction, and the conductive paste 6 in the conduction hole 7 is compressed in the thickness direction, so that the copper foil 8 and the circuit 9 of the inner layer circuit board 11 Are electrically connected through the conduction hole 7.

  Next, as shown in FIG. 3C, a surface layer copper foil 8 is formed into a circuit, and an outer layer circuit 9 electrically connected to the inner layer circuit board 11 is formed. Obtainable.

  In the circuit board 20 in the present embodiment, the inner layer circuit board 11 and the interlayer connection insulating base material 2 are selectively formed with the hardened portion 3, so that the positional accuracy between the layers and the electrical connection between the layers are improved. It can be stabilized.

  Moreover, since the hardening part 3 of the insulating base material 2 for interlayer connection has a function as a prevention wall, the flow of the resin in the base material in the laminating and heating and pressing processes is suppressed, and the inclination of the conduction hole 7 due to this is suppressed. The deformation can be prevented, and the present invention can also stabilize the electrical connection between the layers of the multilayer circuit board.

  In the present embodiment, an example of a circuit board having a multilayer structure of four layers using both-side circuit boards 10 as an inner layer circuit board has been shown, but the circuit board 20 having a multilayer structure of the present embodiment is used as an inner layer. It is possible to further increase the number of layers by using it as a circuit board.

  As described above, the present invention is characterized in that a cured portion is selectively formed on an insulating base material or an insulating base material for interlayer connection that constitutes a circuit board. With this configuration, variations in the circuit board manufacturing process, changes in dimensions of the insulating base material or the insulating base material for interlayer connection, and the like can be minimized, and the positioning and stacking accuracy of the circuit board having a multilayer structure can be improved.

  Therefore, the present invention can provide a stable quality circuit board, and can be said to have great industrial applicability.

DESCRIPTION OF SYMBOLS 1 Insulation base material 2 Insulation base material for interlayer connection 3 Curing part 4 PET film 5 Through-hole 6 Conductive paste 7 Conductive hole 8 Copper foil 9 Circuit 10, 20 Circuit board 11 Circuit board for inner layer 12 Land

Claims (11)

Preparing a semi-cured insulating substrate;
Selectively forming a cured portion on the insulating substrate;
Forming a conduction hole in the insulating substrate;
Laminating a metal foil on the surface of the insulating substrate and heating and pressing; and
And a step of forming a circuit on the metal foil. Preparing an inner layer circuit board and a semi-cured interlayer connection insulating base;
Selectively forming a cured portion on the insulating substrate for interlayer connection;
Forming a conduction hole in the insulating substrate for interlayer connection;
Laminating a metal foil on the inner layer circuit board, the interlayer connection insulating base and the outermost layer;
Heating and pressurizing it;
And a step of forming a circuit on the metal foil. The inner layer circuit board includes an insulating base material having a conduction hole and an inner layer circuit electrically connected to the front and back through the conduction hole, and a cured portion is selectively formed on the insulating base material. The circuit board manufacturing method according to claim 2, wherein The method for manufacturing a circuit board according to claim 1, wherein the hardened portion is formed in a linear shape or a strip shape. The method for manufacturing a circuit board according to claim 1, wherein the hardened portion is formed in a concave shape by pressurization. The circuit board manufacturing method according to claim 1, wherein the circuit board has a product part region and a non-product part region, and the cured part is formed in the non-product part region. 3. The circuit according to claim 1, wherein the circuit board has a product part region and a non-product part region, and the hardened part is formed near a boundary between the product part region and the non-product part region. A method for manufacturing a substrate. The circuit board manufacturing method according to claim 7, wherein a boundary between the product part region and the non-product part region is on an outer shape processing line of the product part. The method for manufacturing a circuit board according to claim 1, wherein the step of selectively forming the hardened portion is performed by laser processing. The method for manufacturing a circuit board according to claim 1 or 2, wherein the step of selectively forming the hardened portion is performed by heating and pressurizing the heating means to the insulating base material or the insulating base material for interlayer connection. . The step of laminating a metal foil on the inner layer circuit board, the interlayer connection insulating base material, and the outermost layer is performed while applying tension to the cured portion formed on the interlayer connection insulating base material. Item 3. A method for manufacturing a circuit board according to Item 2.