JP2007311723A - Multi-layer circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-layer circuit board with improved quality of product, reduced manufacturing cost, thinned body, and improved heat dissipation characteristics. <P>SOLUTION: In the multi-layer circuit board 1, since a first dummy pattern 3b and a second dummy pattern 4b which do not contact with a first inner layer circuit pattern 3a and a second inner layer circuit pattern 4a are formed at peripheries of a first internal conductor layer 3 and a second internal conductor layer 4, respectively, a spacing between adjacent multi-layer circuit boards 1 in a coupling wiring board 12 is made short at manufacture. Consequently, a small space is required for embedding a resin material constituting a second insulating layer 5 and a third insulating layer 7 between the adjacent multi-layer circuit boards 1 at lamination press process, so that generation of air bubbles, etc. is prevented. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a multilayer circuit board used for various electronic devices such as automobile electronic devices such as electrical connection boxes, industrial devices, and communication devices, and more particularly to a multilayer circuit substrate in which a dummy pattern is formed on an internal conductor layer.

  The conventional method for manufacturing a multilayer circuit board has a problem that voids and the like are generated in the pattern of the inner layer circuit and the gap between lands during the lamination pressing process.

  Thus, a technique has been proposed in which generation of voids and the like is reduced by forming a dummy pattern or a dummy land in the gap portion.

  For example, Patent Document 1 discloses a method for manufacturing a multilayer printed wiring board, in which an outer layer metal foil and an inner layer circuit board having circuit groups separated from each other on the same surface are formed through prepreg. By placing a dummy printed circuit board with a pattern resembling the circuit-free area of the circuit board into the position in the press stage and applying heat and pressure, voids and sleds that are likely to occur in places where the remaining copper ratio of the inner layer circuit board is low Techniques for reducing the occurrence of twisting and the like have been proposed.

  Further, in Patent Document 2, in a multilayer wiring board in which two or more wiring patterns are alternately laminated on an insulating substrate via insulating layers, a portion where the distance between the wiring patterns is 400 μm or more is provided. By providing at least one or more dummy patterns and reducing the space between the wiring pattern and the dummy pattern to less than that, the generation of voids can be prevented by supporting an insulating layer (for example, a polyimide resin film and an adhesive layer film) in a bridge shape. Technology has been proposed. .

  Furthermore, in Patent Document 3, when manufacturing a multilayer printed board formed by laminating a plurality of substrates having a copper foil pattern formed on the surface, the copper foil pattern is formed on the same substrate when formed on the substrate. A dummy land is formed so as not to come into contact with the copper foil pattern, and the arrangement and size of the dummy land on the substrate are formed by drilling for forming a connector through hole penetrating the multilayer printed board. Techniques have been proposed for setting so that all dummy lands are removed.

  By the way, in the conventional manufacturing method of a multilayer circuit board, in order to improve product productivity, one panel-like connecting wiring board is cut along a predetermined cutting line to obtain a plurality of units (pieces). Each printed wiring board is separated (for example, see Patent Document 4).

  9A to 9D and FIGS. 10A to 10C are cross-sectional views for explaining an example of a conventional method for manufacturing a multilayer circuit board.

  In the conventional multilayer circuit board manufacturing method, first, as shown in FIG. 9A, a first insulating layer 50 made of an insulating resin material is prepared, and as shown in FIG. The first inner conductor layer 51 is formed on the surface of the first insulating layer 50, and the second inner conductor layer 52 is formed on the back surface of the first insulating layer 50.

  Next, as shown in FIG. 9C, the first inner conductor layer 51 is etched to form a first inner layer circuit pattern 51a, and the second inner conductor layer 52 is etched to form a second inner layer circuit. A pattern 52a is formed.

  Next, as shown in FIG. 9D, a resin material such as a prepreg (a cloth made of glass cloth or the like impregnated with an epoxy resin) on the surfaces of the first inner layer circuit pattern 51a and the first insulating layer 50. A second insulating layer 53 made of metal and a first outer conductor layer made of metal foil (for example, copper foil) are stacked, and a resin such as a prepreg is formed on the second inner circuit pattern 52a and the back surface of the first insulating layer 50. A third insulating layer 55 made of a material and a second outer conductor layer 56 made of a metal foil (for example, a copper foil) are stacked, heated, pressed, and integrated.

  Next, as shown in FIG. 10A, the first outer conductor layer 54 is etched to form the first outer layer circuit pattern 54a, and the second outer conductor layer 56 is etched to form the second outer layer circuit. A pattern 56a is formed.

  Next, as shown in FIG. 10B, a first resist layer 57 is laminated on the first outer layer circuit pattern 54a, and a second resist layer 58 is laminated on the second outer layer circuit pattern 56a. Thereby, the connection wiring board 59 is obtained.

Thereafter, the connection wiring board 59 is cut along a predetermined cutting line CL by router processing, press processing, or the like, and is separated into a plurality of multilayer circuit boards 60 as shown in FIG.
JP 2001-185849 A Japanese Patent Laid-Open No. 2003-124737 JP 2004-247427 A JP 2000-133913 A

  In the conventional method for manufacturing a multilayer circuit board, in order to cut the connection wiring board 59 along the cutting line CL, as shown in FIG. This is longer than the gap between lands. For this reason, the embedding property of the resin material constituting the second insulating layer 53 and the third insulating layer 55 between the adjacent multilayer circuit boards 60 is deteriorated during the laminating press process, and bubbles K and the like are formed in the portions not filled with the resin. It becomes easy to do. As a result, inconvenience occurs in the workability of the post-process and the finished shape of the product, and there is a problem that the quality of the product is lowered. For the purpose of energizing a large current, this tendency is further increased as the inner layer circuit becomes thicker.

  Although measures such as increasing the thickness of the resin material or increasing the number of the resin materials can be considered for the above problems, there has been a problem that the material cost increases and the manufacturing cost increases.

  In addition, there is a problem that the multilayer circuit board 60 becomes thicker than necessary, and the product cannot be thinned.

  Further, when the inner layer circuit becomes thick, a large amount of current is applied to increase the amount of heat generation, and heat is accumulated inside the substrate, which tends to cause a high temperature, which may cause various problems.

  The present invention has been made to solve the above-described problems, and provides a multilayer circuit board capable of improving product quality, reducing manufacturing costs, reducing product thickness, and improving heat dissipation. With the goal.

  In the multilayer circuit board of the present invention, in the multilayer circuit board having an inner conductor layer on which a predetermined circuit pattern is formed, a dummy pattern that does not contact the circuit pattern is formed on a peripheral portion of the inner conductor layer. It is a feature.

  All or part of the end face of the dummy pattern may be exposed to the outside.

  The dummy pattern may be formed so as to extend to a formation region of the circuit pattern.

  You may further have a metal core layer.

  According to the first aspect of the invention, since the dummy pattern that does not contact the inner layer circuit pattern is formed on the peripheral portion of the inner conductor layer, the interval between the adjacent multilayer circuit boards at the time of manufacture is shortened. The space necessary for filling the resin material constituting the insulating layer between the adjacent multilayer circuit boards during the laminating press process is reduced, and generation of bubbles and the like can be prevented. As a result, there is no inconvenience in the workability of the post-process and the finished shape of the product, and the quality of the product can be improved.

  Further, since it is not necessary to increase the thickness of the resin material or increase the number of the resin materials, the manufacturing cost can be reduced and the product can be made thinner.

  Furthermore, heat generated by the inner layer circuit can be easily released to the outside through a dummy pattern formed in the peripheral portion, and heat dissipation can be improved.

  According to the second aspect of the present invention, the heat generated by the inner layer circuit can be released to the outside from the exposed end face of the dummy pattern, so that the heat dissipation can be further improved.

  According to the third aspect of the present invention, the heat generated by the inner layer circuit can be efficiently released to the outside by the dummy pattern extending to the circuit pattern formation region, so that the heat dissipation can be further improved.

  According to the fourth aspect of the present invention, the heat generated by the inner layer circuit can be radiated to the metal core layer, and the heat dissipation can be further improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 is a cross-sectional view showing a multilayer circuit board according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1, and FIG. 3 is a cross-sectional view taken along line III-III in FIG.

  As shown in FIGS. 1 to 3, the multilayer circuit board 1 according to the first embodiment of the present invention includes a first insulating layer 2 made of an insulating resin material and the surface of the first insulating layer 2. The first inner conductor layer 3 formed on the second inner conductor layer 4, the second inner conductor layer 4 formed on the back surface of the first insulating layer 2, and the surfaces of the first inner conductor layer 3 and the first insulating layer 2 A second insulating layer 5 formed of a resin material such as a prepreg (a cloth such as a glass cloth impregnated with an epoxy resin), and a metal foil (for example, formed on the second insulating layer 5) A first outer conductor layer 6 made of a copper foil), a third insulating layer 7 made of a resin material such as a prepreg, formed on the back surfaces of the second inner conductor layer 4 and the first insulating layer 2; A second outer conductor layer 8 made of a metal foil (for example, copper foil) formed on the third insulating layer 7 and a first outer conductor layer 6 are formed. Having a first resist layer 9, a second resist layer 10 formed on the second outer conductor layer 8.

  A first inner layer circuit pattern 3a is formed on the first inner conductor layer 3 by etching, and a first dummy pattern 3b that does not contact the first inner layer circuit pattern 3a is formed on the periphery thereof. ing.

  A second inner layer circuit pattern 4a is formed on the second inner conductor layer 4 by etching, and a second dummy pattern 4b that is not in contact with the second inner layer circuit pattern 4a is formed on the periphery thereof. ing.

  A first outer layer circuit pattern 6a is formed on the first outer conductor layer 6 by etching, and a second outer layer circuit pattern 8a is formed on the second outer conductor layer 8 by etching.

  A through hole 11 is formed to penetrate between the first outer conductor layer 6 and the second outer conductor layer 8 and to be electrically connected to each other.

  4 and 5 are cross-sectional views for explaining an example of the manufacturing method of the multilayer circuit board 1 according to the first embodiment of the present invention.

  First, as shown in FIG. 4A, a first insulating layer 2 made of an insulating resin material is prepared. As shown in FIG. 4B, a first insulating layer 2 is formed on the surface of the first insulating layer 2. The inner conductor layer 3 is formed, and the second inner conductor layer 4 is formed on the back surface of the first insulating layer 2.

  Next, as shown in FIG. 4C, the first inner conductor layer 3 is etched to form the first inner layer circuit pattern 3a and the first dummy pattern 3b, and the second inner conductor layer 4 is etched. Then, the second inner layer circuit pattern 4a and the second dummy pattern 4b are formed.

  Next, as shown in FIG. 4D, a resin material such as a prepreg (a cloth such as a glass cloth impregnated with an epoxy resin) on the surfaces of the first inner conductor layer 3 and the first insulating layer 2. A second insulating layer 5 made of the above and a first outer conductor layer 6 made of a metal foil (for example, copper foil) are stacked, and a resin such as a prepreg is placed on the back surfaces of the second inner conductive layer 4 and the first insulating layer 2. A third insulating layer 7 made of a material and a second outer conductor layer 8 made of a metal foil (for example, a copper foil) are stacked, heated, pressed, and integrated.

  Next, as shown in FIG. 5 (A), a through hole 11 penetrating the first outer conductor layer 6 and the second outer conductor layer 8 is formed, and a plating layer 11a is formed in that portion, The first outer conductor layer 6 and the second outer conductor layer 8 are electrically connected. The first outer conductor layer 6 and the second outer conductor layer 8 are etched to form a first outer layer circuit pattern 6a and a second outer layer circuit pattern 8a, respectively.

  Next, as shown in FIG. 5B, the first resist layer 9 is laminated on the first outer conductor layer 6, and the second resist layer 10 is laminated on the second outer conductor layer 8. Thereby, the connection wiring board 12 is obtained.

  Thereafter, as shown in FIG. 5C, the connection wiring board 12 is cut along a predetermined cutting line CL by router processing, press processing, or the like, and the multilayer circuit board 1 for each of a plurality of units (see FIG. 1). ).

  According to the multilayer circuit board 1 according to the first embodiment of the present invention, the first inner layer circuit pattern 3a and the second inner layer circuit pattern 3 are formed on the peripheral portions of the first inner conductor layer 3 and the second inner conductor layer 4, respectively. Since the first dummy pattern 3b and the second dummy pattern 4b that are not in contact with the inner layer circuit pattern 4a are formed, the distance H2 between the adjacent multilayer circuit boards 1 in the connection wiring board 12 at the time of manufacture (FIG. 4). (See (D)) is shorter than the interval H1 of the conventional multilayer circuit board 1 having no dummy pattern. As a result, the space required to fill the resin material constituting the second insulating layer 5 and the third insulating layer 7 between the adjacent multilayer circuit boards 1 during the laminating press process is reduced, and the generation of bubbles and the like is prevented. it can.

  As a result, there is no inconvenience in the workability of the post-process and the finished shape of the product, and the quality of the product can be improved.

  In addition, since it is not necessary to increase the thickness of the resin material constituting the second insulating layer 5 and the third insulating layer 7 or increase the number of the resin materials, the manufacturing cost can be reduced and the product can be made thinner. Can be planned.

  Furthermore, the heat generated by the inner layer circuit can be easily released to the outside through the dummy patterns 3b and 4b formed on the peripheral portion, and the heat dissipation can be improved.

  FIG. 6 is a sectional view showing a multilayer circuit board according to the second embodiment of the present invention.

  As shown in FIG. 6, the multilayer circuit board 1a according to the second embodiment of the present invention is characterized in that all or part of the end face of the dummy pattern is exposed to the outside. According to this multilayer circuit board 1a, the heat generated by the inner layer circuit can be released from the exposed end face of the dummy pattern to the outside, so that the heat dissipation can be further improved.

  The multilayer circuit board 1a is manufactured by cutting the connection wiring board 12 in which the dummy patterns 3b and 4b of the adjacent multilayer circuit boards are connected by the cutting line CL.

  FIG. 7 is a sectional view showing a multilayer circuit board according to a third embodiment of the present invention.

  As shown in FIG. 7, the multilayer circuit board 1 b according to the third embodiment of the present invention is characterized in that a metal core layer 13 is formed in the first insulating layer 2. The metal core layer 13 is made of a plate material made of a metal having good thermal conductivity, such as copper, aluminum, or an alloy containing them as a main component.

  According to this multilayer circuit board 1b, the heat generated by the inner layer circuit can be radiated to the metal core layer 13 via the first insulating layer 2, and the heat dissipation can be further improved.

  FIG. 8 is a plan view showing a dummy pattern of the multilayer circuit board according to the fourth embodiment of the present invention.

  As shown in FIG. 8, the dummy pattern 14 of the multilayer circuit board 1c according to the fourth embodiment of the present invention is characterized in that it extends to the inner layer circuit pattern formation region 15. According to this multilayer circuit board 1c, the heat generated by the inner layer circuit can be efficiently released to the outside by the dummy pattern 14 extending to the inner layer circuit pattern forming region 15, so that the heat dissipation can be further improved.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical matters described in the claims. For example, the dummy patterns 3b and 4b may be formed over the entire circumference of the peripheral edge, or may be formed while being interrupted.

  Also, a via hole (not shown) may be formed for passing through and electrically connecting between the first inner conductor layer 3 and the second inner conductor layer 4.

  Further, the through hole 11 and the via hole may not be formed.

  Further, the inner conductor layer, the insulating layer, and the outer conductor layer may be laminated on only one of the front surface and the back surface of the first insulating layer 2.

  The present invention is used for various electronic devices such as automotive electronic devices such as electrical junction boxes, industrial devices, and communication devices.

1 is a cross-sectional view showing a multilayer circuit board according to a first embodiment of the present invention. It is the II-II sectional view taken on the line of FIG. It is the III-III sectional view taken on the line of FIG. (A)-(D) are sectional drawings for demonstrating an example of the manufacturing method of the multilayer circuit board based on the 1st Example of this invention. (A)-(C) are sectional drawings for demonstrating an example of the manufacturing method of the multilayer circuit board based on the 1st Example of this invention. It is sectional drawing which shows the multilayer circuit board based on the 2nd Example of this invention. It is sectional drawing which shows the multilayer circuit board based on the 3rd Example of this invention. It is a top view which shows the dummy pattern of the multilayer circuit board based on the example of 4th Embodiment of this invention. (A)-(D) are sectional drawings for demonstrating an example of the manufacturing method of the conventional multilayer circuit board. (A)-(C) are sectional drawings for demonstrating an example of the manufacturing method of the conventional multilayer circuit board, (D) is sectional drawing for demonstrating the subject of the conventional multilayer circuit board.

Explanation of symbols

1, 1a, 1b, 1c: multilayer circuit board 2: first insulating layer 3: first inner conductor layer 3a: first inner layer circuit pattern 3b: first dummy pattern 4: second inner conductor layer 4a : Second inner layer circuit pattern 4b: second dummy pattern 5: second insulating layer 6: first outer conductor layer 6a: first outer layer circuit pattern 7: third insulating layer 8: second outer Conductor layer 8a: second outer layer circuit pattern 9: first resist layer 10: second resist layer 11: through hole 11a: plating layer 12: connecting wiring board 13: metal core layer 14: dummy pattern 15: inner layer circuit Pattern formation area

Claims (4)

In a multilayer circuit board having an inner conductor layer on which a predetermined circuit pattern is formed,
A multilayer circuit board, wherein a dummy pattern that does not contact the circuit pattern is formed on a peripheral edge portion of the inner conductor layer.   2. The multilayer circuit board according to claim 1, wherein all or part of the end face of the dummy pattern is exposed to the outside.   The multilayer circuit board according to claim 1, wherein the dummy pattern is formed so as to extend to a formation region of the circuit pattern.   The multilayer circuit board according to any one of claims 1 to 3, further comprising a metal core layer.

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