JP2009212227A - Wiring substrate and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an improved wiring substrate and its manufacturing method, wherein the generation of stress between an electronic component and a substrate is suppressed while connection reliability is maintained. <P>SOLUTION: In the wiring substrate 100 comprising at least one insulating layer, at least one insulating layer of the wiring substrate has a stiffness distribution in the same plane, and stiffness is set relatively high in a region comprising an electrode where at least an electronic component 200 is mounted. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to single-layer and multilayer wiring boards manufactured using a copper-clad laminate and a prepreg, and a manufacturing method.

In addition to mobile phones and personal digital assistants, notebook personal computers, video and music playback devices, and electronic devices such as game devices are increasingly being carried. These electronic devices are required to ensure reliability in various usage environments, and require high-strength component mounting technology against vibrations during carrying and loads during drop impacts.
On the other hand, since the number of components to be mounted in the device increases due to the function enhancement, there is a strong demand for development of high-density mounting technology and thin mounting technology. In order to solve the conflicting problems of high density and thinning and high strength, various proposals regarding high density and thinning have been made.

  On the other hand, in recent years, portable electronic devices have become more important in terms of their higher functionality and higher performance, and the design of the devices has become important, and curved surfaces are being frequently used in the case shape for the purpose of improving usability and appearance. In order to efficiently use the space in the housing, it is necessary to incorporate the substrate into the housing in a curved shape.

Among these, when a substrate on which electronic components are mounted in a housing having a curved shape is incorporated, in order to ensure the connection reliability of the electronic components, for example, a flexible substrate on the surface of a multilayer wiring substrate is used. A mounting structure in which a reinforcing layer having a high elastic modulus is formed and selectively etched has been proposed.
Moreover, patent documents 2-5 are mentioned as a technique relevant to a mounting structure.
The invention described in Patent Document 2 is an invention related to a printed wiring board, which is a printed wiring board including a base material having flexibility and a conductor formed on at least one side of the base material, and is bent. The conductor formed in the bent region has a thickness of 1 to 30 μm, and the conductor formed in the non-bent region has a thickness of 30 to 150 μm.

  According to this printed wiring board, the rigid portion and the flexible portion are included in an integral structure by having a conductor having a predetermined thickness in each of the bent region and the non-bent region. -Significantly thinner than a flex substrate, etc., and no extra space is required. Therefore, it can be stored at high density even in a limited space of the electronic device.

  The invention described in Patent Document 3 is an invention related to a flexible printed circuit board, and is a flexible printed circuit board having a conductive layer on one or both sides or an inner layer of a film-like base material and an insulating layer on the conductive layer. And having a bent region and a non-bent region, the remaining amount of the conductive layer in the non-bent region is larger than the remaining amount of the conductive layer in the bent region.

  According to this flexible printed circuit board, since the remaining amount of the conductive layer in the non-bent region is larger than the remaining amount of the conductive layer in the bent region, the rigidity of the non-bent region can be made higher than that of the bent region. Therefore, with respect to this non-bending region, it is possible to improve handling such as accurate positioning and mounting accuracy when mounting components, and to ensure stability and durability after mounting the components. It is said that high-density mounting of components is possible as in the case of a rigid board.

  The invention described in Patent Document 4 is an invention related to a multilayer flexible electrical board, and includes an electronic component mounting portion formed by superimposing a plurality of substrates on which a circuit pattern layer is formed, and the number of substrate layers than the electronic component mounting portion. In a multilayer flexible electrical board having a small number of connection wiring parts, the electronic component mounting part maintains rigidity and the connection wiring part maintains flexibility.

  According to this multilayer flexible electrical board, the electronic component mounting portion maintains rigidity, so that electronic components can be mounted on both sides, and the connection wiring portion maintains flexibility, so that it can be bent freely. . Since the electronic component mounting portion and the connection wiring portion are integrally formed, no special area for the connection wiring portion is required, and no connection process is required.

  The invention described in Patent Document 5 is an invention related to an epoxy-based flexible printed wiring board, and is formed by stacking a plurality of epoxy resin circuit boards each having a copper foil pattern provided on at least one surface of a plate-like epoxy resin. An epoxy-based flexible printed circuit board, which has a flexible part with a thin plate thickness and flexibility, and a rigid part with a thick plate and high rigidity, and at least the flexible part is provided with a protective layer made of epoxy resin It is a thing.

According to this epoxy-based flexible printed wiring board, since all the resins are epoxy resins, the circuit characteristics obtained with the glass-based epoxy resin flexible circuit board and the glass-based epoxy resin circuit board are maintained, and rigidity is maintained. Highly rigid part and flexible part with flexibility can be formed, so the chemical treatment, manufacturing equipment and storage conditions in the production of glass base epoxy resin flexible circuit board and glass base epoxy resin circuit board are adopted as they are Since the circuit characteristics obtained with the glass base epoxy resin substrate can be adopted as they are, the electrical characteristics generated by using different resin materials can be complicated. Simulation is not required and cost increase can be suppressed It is.
JP 2003-62945 A JP 2006-352103 A JP 2007-250884 A JP-A-6-334279 JP-A-9-36499

By the way, as a curved wiring board, it is conceivable to form a flexible substrate hot, but there is a problem that the flexible substrate cannot maintain basic rigidity.
In the technique described in Patent Document 1, the reliability of the mounting portion can be ensured by the reinforcing plate, but there is a problem that the component cannot be mounted in the area where the reinforcing plate is attached to the surface of the wiring board where the reinforcing plate is attached. . Furthermore, there is also a problem that the total thickness of the substrate is increased by adding a reinforcing plate. Further, the techniques described in Patent Documents 2 to 5 are insufficient in suppressing the generation of stress between the electronic component and the wiring board.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a wiring board and a manufacturing method that suppresses the generation of stress between an electronic component and a board and maintains and improves connection reliability.

  In the wiring board of the present invention, in the wiring board having one or more insulating layers, at least one insulating layer of the wiring board has a rigidity distribution in the same plane, and at least an electrode portion on which an electronic component is mounted is provided. It is characterized by having relatively high rigidity in the included region.

  The manufacturing method of the present invention is a method for manufacturing a wiring board having one or more insulating layers, wherein at least one insulating layer of the wiring board has a relative rigidity of a region including at least an electrode portion on which an electronic component is mounted. It is characterized by forming a high rigidity distribution.

  According to the present invention, since the distribution of rigidity can be generated in the same plane of the wiring board, it is possible to increase the rigidity for the electronic component mounting portion and decrease the rigidity for the non-mounting portion to ensure flexibility. Is possible.

  The present invention is a flexible circuit board that uses an insulating material in which a glass cloth is mainly impregnated with a resin. The rigidity of the woven fabric fiber is locally changed by providing a portion that can be curved and a high-rigidity portion on which an electronic component is mounted.

  In one embodiment of the wiring board according to the present invention, in the wiring board having one or more insulating layers, at least one insulating layer of the wiring board has a rigidity distribution in the same plane, and at least the electronic component is The region including the electrode portion to be mounted is configured to have relatively high rigidity.

  According to the above configuration, since the distribution of rigidity can be generated in the same plane of the wiring board, it is possible to increase the rigidity for the electronic component mounting portion and decrease the rigidity for the non-mounting portion to ensure flexibility. Is possible.

  Another embodiment of the wiring board according to the present invention is characterized in that, in addition to the above configuration, the rigidity distribution is a distribution of the fiber rigidity of the fiber woven fabric contained in the insulating layer.

  Another embodiment of the wiring board according to the present invention is characterized in that, in addition to the above-described configuration, the stiffness distribution has a stiffness difference depending on the fiber diameter.

  Another embodiment of the wiring board according to the present invention is characterized in that, in addition to the above-described configuration, the rigidity distribution is obtained by giving a difference in rigidity by partially chemically reinforcing the fibers.

  Another embodiment of the wiring board according to the present invention is characterized in that, in addition to the above configuration, the fibers whose rigidity is reinforced are both warp and weft.

  Another embodiment of the wiring board according to the present invention is characterized in that, in addition to the above configuration, the material of the fiber is any one of glass fiber, aramid fiber, and Kevlar fiber.

  One embodiment of a method of manufacturing a wiring board according to the present invention is a method of manufacturing a wiring board having one or more insulating layers, wherein at least an electronic component is mounted on at least one insulating layer of the wiring board. A rigidity distribution having a relatively high rigidity in a region including the portion is formed.

  According to the above configuration, since the distribution of rigidity can be generated in the same plane of the wiring board, it is possible to increase the rigidity for the electronic component mounting portion and decrease the rigidity for the non-mounting portion to ensure flexibility. Is possible.

  Another embodiment of the method for manufacturing a wiring board according to the present invention is characterized in that, in addition to the above configuration, the distribution of the fiber stiffness of the fiber woven fabric contained in the insulating layer is distributed to form a stiffness distribution. To do.

  Another embodiment of the method for manufacturing a wiring board according to the present invention is characterized in that, in addition to the above configuration, the rigidity distribution is formed by providing a difference in rigidity depending on the fiber diameter.

  Another embodiment of the method for manufacturing a wiring board according to the present invention is characterized in that, in addition to the above configuration, the rigidity distribution is formed by giving a difference in rigidity by partial chemical strengthening of fibers.

  Another embodiment of the method for manufacturing a wiring board according to the present invention is characterized in that, in addition to the above configuration, the fibers whose rigidity is reinforced are both warp and weft.

  Another embodiment of the method for manufacturing a wiring board according to the present invention is characterized in that, in addition to the above configuration, the material of the fiber is any one of glass fiber, aramid fiber, and Kevlar fiber.

  The above-described embodiment shows an example of a preferred embodiment of the present invention, and the present invention is not limited thereto, and various modifications can be made without departing from the scope of the invention. is there.

[Description of structure]
Next, an embodiment of a wiring board according to the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing an embodiment of a wiring board according to the present invention.
A printed circuit is formed from the wiring board 100 and the electronic component 200 mounted on the wiring board 100, and a connecting portion 300 is formed between the wiring board 100 and the electronic component 200 for connection by solder.
The wiring board 100 is, for example, a glass cloth material impregnated with an epoxy resin, and the fiber rigidity of the high-rigidity part 102 immediately below and in the vicinity of the electronic component is relatively smaller than that of the low-rigidity part 101 that is a non-mounting part. Is getting higher.
As a means for increasing the rigidity, the outer diameter of the glass fiber is increased. As another means, there is a means for increasing the rigidity without changing the fiber outer diameter by locally chemically reinforcing the fiber.

The electronic component shown in FIG. 1 is a BGA (ball grid array) type semiconductor package, but other package forms, for example, a lead type connection method, may be used as long as it is a surface mountable component. It is.
Further, although the connection portion 300 is soldered in FIG. 1, a resin-based adhesive such as a conductive paste or a conductive film may be used.

FIG. 2 is a schematic view of fiber orientation of a glass woven fabric used for the wiring board shown in FIG.
A wavy line portion shown in FIG. 2 indicates a mounting position of the electronic component 200. In this way, highly rigid fibers are arranged only at the component mounting locations.

[Description of operation]
FIGS. 3A and 3B are explanatory views showing the difference between the wiring board according to the present invention and the wiring board according to the related art. FIG. 3B shows a wiring board according to the related art. If a normal wiring board has a curved surface structure, an electronic component cannot be mounted on a curved surface portion, or even if an electronic component is mounted, stress is applied to the outer peripheral portion. It is easy to cause connection failure because of the concentration.
On the other hand, when the wiring board according to the present invention is used, as shown in FIG. 3 (a), the component mounting portion has high rigidity, so that even if it is curved, it is curved. There is nothing. For this reason, stress is not concentrated on the connection part 300, and the wiring board 100 and the electronic component 200 do not cause a connection failure.

4A and 4B are cross-sectional views showing another embodiment of the wiring board according to the present invention.
In the embodiment shown in FIGS. 4A and 4B, the wiring board is multilayered. 4A and 4B, the wiring board includes a first conductor layer 111, a second conductor layer 112, a third conductor layer 113, a fourth conductor layer 114, a fifth conductor layer 115, and The 6th conductor layer 116 and the 1st insulating layer 121, the 2nd insulating layer 122, the 3rd insulating layer 123, the 4th insulating layer 124, and the 5th which insulate between each conductor layers 111-116 Of the insulating layer 125.
In FIG. 4A, the fiber stiffness of the first, second, fourth, and fifth insulating layers near the center of the wiring board is high. An electronic component can be mounted on one side or both sides of the highly rigid portion 101.

On the other hand, in FIG. 4B, the first insulating layer 121 and the second insulating layer 122, and the fourth insulating layer 124 and the fifth insulating layer 125 are different from each other in the highly rigid portion A (103). And the highly rigid part B (104) is formed.
In double-sided mounting, the mounting positions of electronic components cannot always be matched on both sides of the board.
On the other hand, if all the parts shifted in position are made highly rigid, there will be no flexible part that can have a curved surface structure. As shown in FIG. 4 (b), the high-rigidity portion A (103) is shifted and installed, so that the reinforcement as shown in FIG. 4 (a) cannot be obtained, but it can sufficiently cope with double-sided mounting.

5A and 5B are cross-sectional views showing another embodiment of the wiring board according to the present invention.
The wiring board shown in FIGS. 5A and 5B has a multilayered wiring board as in the first embodiment, and has six conductive layers equivalent to FIGS. 4A and 4B. It is.
In FIGS. 5A and 5B, the second insulating layer 122 and the fourth insulating layer 124 are layers that do not include a glass cloth material, and the rigidity of the entire wiring board is relatively low. It is possible to ensure flexibility.

FIG. 6 is a sectional view showing another embodiment of the wiring board according to the present invention.
The wiring board shown in FIG. 6 is a wiring board having four conductor layers.
In this embodiment, the high-rigidity portion C (105) is provided in the second insulating layer, which is the central insulating layer. Further, the high rigidity portion D (106) is provided in the insulating layer 3 continuously. An electronic component is attached to the fourth conductor layer, and the connection is maintained by the high-rigidity portion D (106). However, the high-rigidity portion C (105) has a large amount of deformation while having rigidity, so that it is highly elastic. It can be deformed.
Further, the low-rigidity portion E (107) has a structure with relatively high flexibility, such as a portion having flexibility, a portion having high elasticity, and a portion having high rigidity depending on the portion of the wiring board. It is possible to change according to.

7A and 7B are schematic views of a wiring board showing another embodiment of the wiring board according to the present invention.
FIG. 7A shows the crossing of fibers having different rigidity, and FIG. 7B shows the rigidity distribution of FIG. 7A. In the present embodiment, the high-rigidity part is set in both the vertical direction and the horizontal direction, and the intersection part of the two can be very high in rigidity. Moreover, by doing in this way, a rigidity difference can be freely given in a plane and it can respond to various forms including multilayering.
According to the present embodiment, since the distribution of rigidity can be generated in the same plane of the wiring board, the rigidity is increased for the electronic component mounting portion, and the rigidity is decreased for the non-mounting portion to ensure flexibility. Is possible.

  In a multilayer board, the rigidity distribution of each layer can be adjusted freely. Therefore, if the fiber rigidity of the substrate surface layer is increased, bending becomes difficult, and if the fiber rigidity at the center is increased, the elastic deformation region is increased while maintaining rigidity. Can take. In the multilayer substrate, when the fiber rigidity of all the layers is further reduced, it is possible to have characteristics such as flexible bending of the portion. In the multilayer substrate, the rigidity can be changed in a plane by further changing the longitudinal and lateral fiber rigidity.

[Function and effect]
The first effect of the present invention is that, in a wiring board having a curved structure, it is possible to maintain the rigidity of the mounting part of the electronic component while keeping it flat and to reliably maintain the connection between the electronic component and the wiring board. is there.

  The second effect of the present invention is that, in a wiring board having a curved structure, the flexibility in a region where electronic components are not mounted is ensured, and molding into a curved structure is easy.

  The third effect of the present invention is that, in the wiring board, when external force such as temperature change, bending load, impact load and the like is strong, the rigidity of the electronic component mounting part is high and the rigidity of the non-mounting region is low. The stress concentration can be mitigated by the wiring board in the non-mounting region while avoiding stress concentration on the part.

  The fourth effect of the present invention is that the flexible and thin wiring board is a freely deformable board, and at the same time the rigidity of the mounting part of the electronic part is maintained, so that the electronic component and the wiring board This is a point where the connection can be reliably maintained.

It is sectional drawing showing one Example of the wiring board which concerns on this invention. It is a schematic diagram of the fiber orientation of the glass woven fabric used for the wiring board shown in FIG. (A), (b) is explanatory drawing which shows the difference with the wiring board which concerns on this invention, and the wiring board which concerns on related technology. (A), (b) is sectional drawing which shows the other Example of the wiring board based on this invention. (A), (b) is sectional drawing which shows the other Example of the wiring board based on this invention. It is sectional drawing which shows the other Example of the wiring board which concerns on this invention. (A), (b) is a schematic diagram of the wiring board which shows the other Example of the wiring board which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Wiring board 101 Low-rigidity part 102 High-rigidity part 111 1st conductor layer 112 2nd conductor layer 113 3rd conductor layer 114 4th conductor layer 115 5th conductor layer 116 6th conductor layer 121 1st Insulating layer 122 Second insulating layer 123 Third insulating layer 124 Fourth insulating layer 125 Fifth insulating layer 200 Electronic component 300 Connection portion

Claims (12)

  In a wiring board having one or more insulating layers, at least one insulating layer of the wiring board has a rigidity distribution in the same plane and is relatively in a region including at least an electrode portion on which an electronic component is mounted. A wiring board characterized by having high rigidity.   The wiring board according to claim 1, wherein the rigidity distribution is a distribution of fiber rigidity of the fiber woven fabric contained in the insulating layer.   The wiring board according to claim 1, wherein the rigidity distribution has a rigidity difference depending on a fiber diameter.   The wiring board according to claim 1, wherein the rigidity distribution is obtained by giving a difference in rigidity by partial chemical strengthening of fibers.   The wiring board according to any one of claims 2 to 4, wherein the fibers whose rigidity is reinforced are both warp and weft.   The wiring board according to any one of claims 1 to 5, wherein a material of the fiber is any one of glass fiber, aramid fiber, and Kevlar fiber.   In a method for manufacturing a wiring board having one or more insulating layers, a rigidity distribution having a relatively high rigidity in a region including at least an electrode portion on which an electronic component is mounted is formed on at least one insulating layer of the wiring board. A method for manufacturing a wiring board, comprising:   8. The method for manufacturing a wiring board according to claim 7, wherein the rigidity distribution is formed by giving a distribution to the fiber rigidity of the fiber woven fabric contained in the insulating layer.   The method of manufacturing a wiring board according to claim 7, wherein the rigidity distribution is formed by giving a difference in rigidity depending on a fiber diameter.   9. The method of manufacturing a wiring board according to claim 7, wherein the rigidity distribution is formed by giving a difference in rigidity by partial chemical strengthening of fibers.   The method for manufacturing a wiring board according to any one of claims 8 to 10, wherein the fibers whose rigidity is reinforced are both warp and weft.   The method of manufacturing a wiring board according to any one of claims 7 to 11, wherein the material of the fiber is any one of glass fiber, aramid fiber, and Kevlar fiber.

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