JP2005079402A - Circuit board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit board capable of both-side mounting mounting electronic components on both front and back surfaces by using a one-side circuit board as a mother board substrate. <P>SOLUTION: At least one part of an insulating base material 11 of the mother board substrate 10 formed with a conductive pattern 12 on one surface of the insulating base material 11 is partially removed and the back surface of the conductive pattern 12 is exposed at the removed part 19 of the insulating base material 11. From the side of the other surface of the insulating base material 11, the one-side circuit board 30 for a multilayer wiring board having an interlayer conducting part 34 and the conductive pattern 32 on one surface of the insulating base material 31 is laminated in a form of being conducted and connected to the back surface exposed part 12B of the conductive pattern 12. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a circuit board and a method for manufacturing the same, and more particularly to a circuit board that can be mounted on both sides and a method for manufacturing the same.

  In recent years, electronic devices have become smaller and lighter in addition to high-frequency signals and digital signals, and accordingly, printed wiring boards mounted on electronic devices are also required to be small and have high density mounting. As a printed wiring board that meets these requirements, there is a rigid-flex printed wiring board of a double-sided mounting type that includes a rigid part and a flex part and can mount electronic components on both the front and back sides (for example, Patent Document 1).

  In a double-sided printed wiring board, a double-sided circuit board having conductive patterns on both front and back surfaces of an insulating base material using a double-sided copper clad laminate as a main circuit board (core board) is used. A single-sided circuit board for multilayer wiring boards such as a single-sided copper-clad laminate is laminated on each of the front side and the back side.

A conventional double-sided printed wiring board requires a double-sided circuit board as a core substrate, but wastes material and resources by removing most of the conductive layer on one side in forming a conductive pattern. In addition, the manufacturing process becomes complicated, such as through-hole formation.
Japanese Patent Laid-Open No. 2002-158445

  The problem to be solved by the present invention is a circuit board that can be mounted on both sides as a core board (main circuit board), in other words, as a mother board, using a single-sided circuit board to mount electronic components on both sides. Is to realize.

  In the circuit board according to the present invention, at least one portion of the insulating base material of the main single-sided circuit board having a conductive pattern on one surface of the insulating base material is partially removed, and the removed portion of the insulating base material is removed. In the back surface of the conductive pattern is exposed, from the other surface side of the insulating base material of the main single-sided circuit board, the electronic component is mounted in a conductively connected form to the back surface exposed portion of the conductive pattern, Alternatively, and / or a single-sided circuit board for a multilayer wiring board having a conductive pattern on one side of the interlayer conductive part and the insulating base material is laminated in a conductive connection with the back side exposed part of the conductive pattern.

  The circuit board according to the present invention is mounted on the one surface of the main single-sided circuit board in a form in which an electronic component is conductively connected to the conductive pattern of the main single-sided circuit board for double-sided mounting, or / And a multilayer circuit board single-sided circuit board having a conductive pattern on one side of the interlayer conductive part and the insulating base material is laminated in a form of being conductively connected to the conductive pattern of the main single-sided circuit board.

  In the circuit board according to the present invention, preferably, the main single-sided circuit board is a flexible wiring board.

  Further, in the circuit board according to the present invention, the main single-sided circuit board constitutes a mother board, and the single-sided circuit board for multilayer wiring board is previously processed into an outer shape smaller than the outer shape of the mother board and arranged in an island shape on the mother board. Can be configured.

  In the method for manufacturing a circuit board according to the present invention, a single-sided conductor-clad laminate having a conductive layer only on one side of an insulating base material is used as a starting material for a main single-sided circuit board, and a conductive pattern is formed by the conductive layer. An electrically conductive pattern forming step and an insulating base material in which at least one portion of the insulating base material of the main single-sided circuit board is partially removed and the back surface of the conductive pattern is exposed at the removed portion of the insulating base material. And / or a back side mounting step of mounting the electronic component in a conductively connected form to the back side exposed portion of the conductive pattern from the other side of the insulating base of the main single-sided circuit board, and / or A back side laminating step of laminating a single-sided circuit board for a multilayer wiring board having a conductive pattern on one side of an interlayer conductive part and an insulating base material in a form connected to the back side exposed part of the conductive pattern; Circuit board A surface-side mounting process for mounting the electronic component in a form in which the electronic component is conductively connected to the back surface exposed portion of the conductive pattern on the one surface, or / and a conductive pattern on one surface of the interlayer conductive portion and the insulating substrate. And a front surface side lamination step of laminating the single-sided circuit board for a multilayer wiring board having a conductive connection with the back surface exposed portion of the conductive pattern.

  The insulating base material removing step in the circuit board manufacturing method according to the present invention can be performed by etching or laser processing.

  Moreover, the lamination | stacking of the several single-sided circuit board for multilayer wiring boards in the said back surface side lamination process in the manufacturing method of the circuit board by this invention and the said surface side lamination process can be performed by 1 process by batch lamination.

  In the circuit board according to the present invention, at least one portion of the insulating base material of the main single-sided circuit board is partially removed, and the back surface of the conductive pattern is exposed at the removed portion, so that the insulating base material of the main single-sided circuit board is exposed. A multilayer wiring board having a conductive pattern mounted on the back surface of the conductive pattern in an electrically conductive manner from the other surface side, or / and having a conductive pattern on one side of the interlayer conductive portion and the insulating substrate The single-sided circuit board can be laminated in a form in which the single-sided circuit board is conductively connected to the back surface exposed portion of the conductive pattern. A circuit board mounted on both sides can be obtained by mounting electronic components on one surface of the insulating base material of the main single-sided circuit board and / or laminating a single-sided circuit board for a multilayer wiring board.

  1 and 2 show an embodiment of a circuit board according to the present invention. This circuit board has a motherboard 10 and island-like partial multilayer wiring boards (multilayered portions) 20A, 20B, 20C, and 20D that are respectively stacked at a plurality of locations on the front and back of the motherboard 10.

  The partial multilayer wiring boards 20 </ b> A, 20 </ b> B, 20 </ b> C, and 20 </ b> D are collectively packaged with a plurality of single-sided circuit boards 30 for multilayer wiring boards that have been previously processed into a predetermined shape smaller than the outer shape of the motherboard 10. Laminated. In this embodiment, all of the partial multilayer wiring boards 20A, 20B, 20C, and 20D have two layers.

  Multi-layer wiring board single-sided circuit board 30 was bonded to insulating base 31, conductive pattern 32 formed on one side of insulating base 31, and the other side of insulating base 31. The adhesive layer 33 includes an interlayer conductive portion 34 formed by an inner via hole formed through the insulating base 31 and the adhesive layer 33.

  The single-sided circuit board 30 for the multilayer wiring board can be constituted by either a rigid printed wiring board made of phenol resin or epoxy resin, or a flexible wiring board made of polyester resin or polyimide resin. If the insulating base 31 itself of the single-sided circuit board 30 for a multilayer wiring board has interlayer adhesion, the adhesive layer 33 can be omitted.

  The surface of the insulating base 31 of the multilayer wiring board single-sided circuit board 30 among the multilayer wiring board single-sided circuit boards 30 of the partial multilayer wiring boards 20A, 20B, 20C, and 20D is covered with a solder resist 35. Has been.

  The electronic component 50 is mounted by bumps 51 on the multilayer wiring board single-sided circuit board 30 of the outermost layer of each of the partial multilayer wiring boards 20A, 20B, 20C, and 20D. Thereby, a double-sided multilayer / double-sided mounting circuit board is obtained.

  The motherboard 10 is a main single-sided circuit board having a conductive pattern 12 on one surface of the insulating base material 11. At least one place (two places in this embodiment) of the insulating base material 11 is partially removed from the mother board 10, and the back surface of the conductive pattern 12 is exposed at the removed portion 19 of the insulating base material 11. . Then, from the other surface side (back surface side) of the insulating base material 11, the multilayer wiring board single-sided circuit board 30 of the partial multilayer wiring boards 20 </ b> C and 20 </ b> D is conductively connected to the back surface exposed portion 12 </ b> B of the conductive pattern 12. Thus, partial multilayer wiring boards 20C and 20D are formed.

  The single-sided circuit board 30 for the multilayer wiring board of the partial multilayer wiring boards 20A and 20B is electrically connected to the surface exposed portion 12A of the conductive pattern 12 on one surface (front surface) of the insulating base material 11. To form partial multilayer wiring boards 20A and 20B.

  The motherboard 10 can also be formed of either a rigid printed wiring board made of phenol resin or epoxy resin, or a flexible wiring board made of polyester resin or polyimide resin.

  The surface of the motherboard 10 is covered with a cover layer 18. In addition, a solder resist 17 is applied and filled in the gaps between the cover layer 18 and the partial multilayer wiring boards 20A and 20B.

  Next, an embodiment of a circuit board manufacturing method according to the present invention will be described with reference to FIGS.

  3A to 3E show a manufacturing process of the motherboard 10. As shown in FIG. 3A, a general-purpose single-sided copper-clad polyimide substrate (single-sided conductor-clad laminate) 60 is prepared as a starting material. The single-sided copper-clad polyimide substrate 60 is a single-sided copper-clad laminate (CCL) having a copper foil 16 as a conductive layer only on one surface of the insulating substrate 11 made of a polyimide film.

  Here, considering the heat resistance and dielectric characteristics of the substrate, polyimide is selected as the insulating base material. Of course, a steel-clad phenol substrate consisting of a base material such as glass cloth, glass mat, synthetic fiber and thermosetting resin A copper-clad paper eboxy substrate, a steel-clad paper polyester substrate, a copper-clad glass epoxy substrate, a copper-clad crow polyimide substrate, or the like may be used. Moreover, you may use a copper clad polyester board | substrate, a copper clad polyetherimide board | substrate, a copper clad liquid crystal polymer board | substrate, etc. as a form which does not combine a base material.

  First, as a conductive pattern forming step, an etching resist is laminated on the copper foil 16 of the single-sided copper-clad polyimide substrate 60, and the wiring pattern is exposed and developed. Thereafter, the exposed copper is etched by a cupric chloride bath to form the conductive pattern 12. Next, the etching resist is removed to obtain a single-sided circuit board 61 as shown in FIG.

  As shown in FIG. 3C, a portion (surface-side multilayer) on which the multilayer circuit board single-sided circuit board 30 is laminated on the surface (upper surface) of the single-sided circuit board 61 for the purpose of protecting the conductive pattern 12. The cover layer 18 having the opening 14 formed in advance is provided. A solder resist or the like may be used as the cover layer.

  Next, as shown in FIG. 3D, as the insulating base material removing step, an etching resist 62 is laminated on both surfaces of the single-sided circuit board 61, and the copper foil surface side (surface side) is exposed on the entire surface. An opening pattern is exposed and developed on the polyimide surface side (back surface side).

  Thereafter, the insulating base material 11 made of polyimide is etched using oxygen plasma or a strong alkaline aqueous solution, and the etching resist 62 is removed after the etching is completed. As a result, as shown in FIG. 3E, the insulating base material 11 of the single-sided circuit board 61 is partially removed by a predetermined area, and the removed portion of the insulating base material 11 (rear side multilayered portion). 19 completes the motherboard 10 with the back surface 12B of the conductive pattern 12 exposed.

  Note that the insulating base material removing step of providing the removal portion 19 on the insulating base material 11 can also be performed by laser processing using a laser beam from the back surface side of the insulating base material 11.

  4 is a schematic plan view of the motherboard 10 and FIG. 3E is a cross-sectional view taken along line ee of FIG.

  5A to 5F show the manufacturing process of the single-sided circuit board 30 for a multilayer wiring board. As shown in FIG. 5A, a general-purpose single-sided copper-clad polyimide substrate (single-sided conductor-clad laminate) 70 is prepared as a starting material.

  The single-sided copper-clad polyimide base material 70 is the same as the single-sided copper-clad polyimide base material 60 for the motherboard 10, and the copper foil 36 as a conductive layer is provided only on one surface of the insulating base material 31 made of a polyimide film. It has a single-sided copper-clad laminate (CCL).

  Note that the insulating base material 11 of the motherboard 10 and the edge base material 31 of the multilayer wiring board single-sided circuit board 30 are preferably made of the same material from a thermal and mechanical viewpoint.

  First, as shown in FIG. 5B, the copper foil 36 of the single-sided copper-clad polyimide base material 70 is etched in the same manner as the motherboard substrate formation to form a conductive pattern 32.

  Next, as shown in FIG. 5C, thermoplastic polyimide is bonded to the surface of the insulating base 31 opposite to the conductive pattern 32 by a hot press to form an adhesive layer 33. As the adhesive layer 33, a phenol resin, a phenoxy resin, a polyimide resin, a xylene resin, or a mixed resin of two or more of these, a polyetherimide resin, a liquid crystal polymer, a polyamide resin, or the like can be used.

  Next, as shown in FIG. 5D, a laser is irradiated from the adhesive layer 33 side to any position where the interlayer connection is desired, and the copper foil (through the insulating base material 31 and the adhesive layer 33 is penetrated). A hole (via hole) 37 in contact with the conductive pattern 32) is formed.

  Next, as shown in FIG. 5E, the hole 37 is filled with a thermosetting silver paste by a printing method or the like to complete the interlayer conductive portion 34. The conductive paste that fills and fills the hole 37 is prepared by mixing gold, copper, nickel, carbon powder, or an alloy powder or mixed powder thereof with a binder component such as phenol resin, polyester resin, epoxy resin, or polyimide resin. The conductive composition thus prepared may be used.

  For printing and filling the conductive paste, a printing method using a metal mask, a printing method using a masking film, and a filling method using a dispenser can be applied.

  Next, the laminated base material 71 on which the silver paste is printed is heated in an oven to dry the silver paste.

  Next, as shown in dotted line C, the laminated base material 71 is pressed with a mold for the purpose of external processing to an external shape smaller than the external shape of the motherboard 10, as shown in FIG. As shown, a single-sided circuit board 30 for a multilayer wiring board having a desired size is obtained. This outer shape processing is performed in these openings so that the single-sided circuit board 30 for the multilayer wiring board can enter the surface-side multilayered portion (opening) 14 of the cover layer 18 and the removal portion 19 of the insulating base material (opening) 11. This is done with the exact size or slightly smaller than these openings.

  FIGS. 6A to 6C show the stacking process of the single-sided circuit board 30 for the multilayer wiring board. A plurality of single-sided circuit boards 30 for the multilayer wiring board thus obtained are prepared, and as shown in FIG. 6A, the surface side multilayered portion on the conductive pattern 12 side (surface side) of the motherboard 10 14 and each of the removed portions 19 on the back surface side of the insulating base material 11 are aligned with a predetermined number of single-sided circuit boards 30 for multilayer wiring boards, and then superposed and heated and pressurized by a vacuum press machine. A double-sided circuit board 80 as shown in FIG.

  For alignment, a pin alignment method may be used, but it is not preferable because a space for the guide hole is required. Therefore, alignment by image recognition was performed.

  Next, as shown in FIG. 6C, a solder resist 17 is formed by a printing method so as to cover a gap between the cover layer 18 and the multilayered portion of the motherboard 10 and a part of the surface of the multilayered portion. 35 was applied and cured.

  Finally, the exposed conductive pattern 32 for mounting the electronic component was covered with a noble metal 38 made of noble conductive material such as gold to complete a circuit board that can be mounted on both sides.

  In short, the circuit board described above has the following characteristics and effects.

(1) When a single-sided wiring board is used as a mother board, the problem that double-sided multilayering and double-sided mounting cannot be achieved is solved, and the single-sided wiring board is used as the mother board 10, ie, the main single-sided circuit board. Unlike the case of using a substrate, the conductive layer on one side is hardly removed in forming the conductive pattern, and waste of materials and resources can be reduced. Further, complicated manufacturing processes such as through-hole formation are not required.

(2) Since the single-sided wiring board is used as the mother board 10, when the mother board 10 is a flexible board, the flexibility of the non-multilayered portion is improved, and a high-density double-sided partial wiring board with excellent flexibility is obtained. Can do.

(3) Since the partial multilayer wiring board, that is, the single-sided circuit board 30 for multilayer wiring board, which is externally processed to the size of the partial multilayer wiring part is used, the substrate of the partial multilayer wiring part is the same as the motherboard 10. The amount of material of the single-sided circuit board 30 for the multilayer wiring board can be reduced as compared with the case of punching into the same outer shape as the outer shape of the motherboard substrate 10 when processing the outer shape of the motherboard substrate 10 with a large size, and reducing waste of materials. it can.

  The circuit board according to the present invention is not limited to the double-sided laminate as described above. As shown in FIG. 7, the conductive pattern 12 of the motherboard 10 and the removed portion of the insulating base 11 are removed. 19, the electronic component 50 may be directly mounted in a flip-chip manner. The electronic component 50 is mounted on the removed portion 19 of the insulating base material 11 in a form in which the electronic component 50 is conductively connected to the back surface exposed portion 12B of the conductive pattern 12.

It is sectional drawing which shows one Embodiment of the circuit board by this invention. 1 is a schematic plan view of a circuit board according to the present invention. (A)-(e) is process drawing which shows one Embodiment of the manufacturing process of the motherboard used with the circuit board by this invention. It is a typical top view of a motherboard. (A)-(f) is process drawing which shows one Embodiment of the manufacturing process of the single-sided circuit board for multilayer wiring boards used with the circuit board by this invention. (A)-(c) is process drawing which shows one Embodiment of the lamination | stacking process of the single-sided circuit board for multilayer wiring boards. It is sectional drawing which shows other embodiment of the circuit board by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Mother board 11 Insulating base material 12 Conductive pattern 14 Surface side multilayer part 16 Copper foil 17 Solder resist 18 Cover layer 19 Removal part 20A, 20B, 20C, 20D Partial multilayer wiring board 30 Single-sided circuit board for multilayer wiring boards 31 Insulating substrate 32 Conductive pattern 33 Adhesive layer 34 Interlayer conduction part 35 Solder resist 36 Copper foil 50 Electronic component 60, 70 Single-sided copper-clad polyimide substrate

Claims (7)

At least one portion of the insulating base material of the main single-sided circuit board having a conductive pattern on one surface of the insulating base material is partially removed, and the back surface of the conductive pattern in the removed portion of the insulating base material Is exposed,
Mounting the electronic component from the other surface side of the insulating base of the main single-sided circuit board in a conductively connected form to the back surface exposed portion of the conductive pattern, and / or an interlayer conductive portion and an insulating base A circuit board in which a single-sided circuit board for a multilayer wiring board having a conductive pattern on one side of a material is laminated in a conductive connection with a back surface exposed portion of the conductive pattern.   The electronic component is mounted on the one surface of the main single-sided circuit board in a form of being electrically connected to the conductive pattern of the main single-sided circuit board, or / and electrically conductive on one side of the interlayer conductive part and the insulating base. The circuit board according to claim 1, wherein the single-sided circuit board for a multilayer wiring board having a conductive pattern is laminated in a form of being electrically connected to the conductive pattern of the main single-sided circuit board.   The circuit board according to claim 1, wherein the main single-sided circuit board is a flexible wiring board.   The main single-sided circuit board constitutes a mother board, and the single-sided circuit board for multilayer wiring board is previously processed into an outer shape smaller than the outer shape of the mother board and arranged in an island shape on the mother board. The circuit board according to any one of claims. A conductive pattern forming step in which a single-sided conductor-clad laminate having a conductive layer only on one side of the insulating base material is used as a starting material of the main single-sided circuit board, and a conductive pattern is formed by the conductive layer;
An insulative base material removing step of partially removing at least one portion of the insulative base material of the main single-sided circuit board and exposing a back surface of the conductive pattern to a removed portion of the insulative base material;
Backside mounting process for mounting electronic components in a form connected to the backside exposed part of the conductive pattern from the other side of the insulating base of the main single-sided circuit board, and / or interlayer conductive part And a back side laminating step of laminating a single-sided circuit board for a multilayer wiring board having a conductive pattern on one side of an insulating base material in a form conductively connected to the back side exposed part of the conductive pattern;
A front side mounting process for mounting an electronic component on the one side of the main single-sided circuit board in a conductively connected form to the backside exposed part of the conductive pattern, or / and one side of the interlayer conductive part and the insulating base A front side laminating step of laminating a single-sided circuit board for a multilayer wiring board having a conductive pattern on the backside exposed portion of the conductive pattern in a conductive connection form;
A method of manufacturing a circuit board having The circuit board manufacturing method according to claim 5, wherein the insulating base material removing step is performed by etching processing or laser processing. The method for manufacturing a circuit board according to claim 5 or 6, wherein the plurality of single-sided circuit boards for a multilayer wiring board in the back side laminating step and the front side laminating step are laminated in one step by batch lamination.

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