JP2011091142A - Flex rigid substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flex rigid substrate capable of releasing heat generated from a heating element without using a special member for heat dissipation by conducting the heat generated from the heating element so that the heat is conducted from a conductive member (a copper foil) of a flexible substrate which configures a flex rigid substrate to a housing, in a flex rigid substrate mounting the heating element. <P>SOLUTION: A flex rigid substrate includes: a rigid part having a flexible substrate on which a heating element is mounted and which is formed so that a conductive member of a surface layer is laminated outside, and a conductive member of an inner layer is laminated inside; and a flexible part formed by extending the flexible substrate of the rigid part. The conductive member of the inner layer that forms the flexible substrate of a flexible part is brought into contact with a housing. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a flex-rigid board, and more particularly to a flex-rigid board having a structure for improving heat dissipation with respect to a printed wiring board on which an electronic component as a heating element is mounted.

  Various techniques for dissipating heat generated from a flex-rigid substrate in the prior art have been disclosed.

As a first example, there is a flex-rigid board having a structure provided with a metal plate to dissipate heat. This is disclosed in Japanese Patent Application Laid-Open No. 2003-249758, and as shown in FIG. 2, A is a rigid flex multilayer wiring board, which is a flexible part on which a rigid part 111 for mounting components and a power module 113 are mounted. 112, and a flexible part 112 on which the power module 113 is mounted has a structure in which a metal plate 114 is attached for heat dissipation. The rigid portion 111 is provided with a through hole 115 and a blind via hole (BVH).
The type, thickness, and number of layers of the metal plate 114 are not limited. The metal plate 114 is made of an aluminum plate, a copper plate, or the like when importance is placed on heat dissipation, or an iron plate or the like when importance is placed on rigidity.

  As a second example, a structure having a structure in which heat of a printed wiring board (flexible rigid board) is released to the housing and released by contacting the housing with a member having high thermal conductivity and cushioning properties. This is disclosed in Japanese Utility Model Publication No. 11-74427. As shown in FIG. 3, a second substrate 125 including a ground layer 123 and an insulating layer 124 is disposed above the CPU 122 mounted on the first substrate 121 which is a multilayer substrate. A heat conduction cushion 126 is interposed therebetween.

  The CPU 122 is in thermal contact with the grounding layer 123 of the second substrate 125 via an insulating thermal conductive cushion 126 as a thermal conductive member, so that the heat generated from the CPU 122 is transmitted via the thermal conductive cushion 126. It is transmitted to the ground layer 123 of the electric conductor layer formed on the second substrate 125 and is radiated from the ground layer 123.

  As a third example, the first example and the second example described above are combined, and a cushion material having high thermal conductivity is attached to the upper part of the heating element mounted on the first rigid part, and the attached cushion The material is brought into contact with the casing to dissipate heat, and a metal plate is attached to the second rigid part provided on the other side through the flexible substrate to dissipate heat.

  As shown in FIG. 4, a prepreg 135 and a copper foil 136 as a surface layer are formed on a flexible substrate 131 formed by laminating a copper foil 133 and an insulating cover lay 134 on both surfaces of a polyimide double-sided copper-clad laminate 132. A first rigid portion 141 formed by stacking a solder resist 137 as an insulator, and a heating element 138 such as an IC mounted on the solder resist 137, and a flexible substrate extended from the first rigid portion 141. The second rigid portion 145 is formed by laminating a prepreg 142, a copper foil 143 as a surface layer, and a solder resist 144 as an insulator, and a metal plate 146 for heat dissipation is attached to the top of the solder resist 144. ing.

A cushion material 139 having high thermal conductivity is attached to the upper portion of the heating element 138 mounted on the first rigid portion 141, and the cushion material 139 is in contact with the housing 140.
Then, the thermal via 147 is passed through the first rigid portion 141, and the surface layer copper foil 136 and the inner layer copper foil 133 forming the flexible substrate 131 are connected by the thermal via 147. Similarly, a thermal via 148 is also formed in the second rigid portion 145, and the surface layer copper foil 143 and the inner layer copper foil 133 forming the flexible substrate 131 are connected by the thermal via 148.

  In the flex-rigid board having such a structure, the heat generated by the heating element 138 such as an IC is radiated in the direction of the arrow of the housing 140 via the cushion material 139, and the heat generated by the heating element 138 is the first. The heat is transferred to the inner copper foil 133 of the flexible substrate 131 through the surface copper foil 136 connected by the thermal via 147 of the rigid portion 141, and the transferred heat is transferred to the inner copper foil 133 of the second rigid portion 145. And reaches the surface copper foil 143, and the heat reaching the surface copper foil 143 is dissipated from the metal plate 146 into the air.

JP 2003-249758 A Japanese Patent Laid-Open No. 11-74427

However, in various heat dissipation structures described in the prior art, it is necessary to attach a metal plate or a member with high thermal conductivity (cushion material) to the flex-rigid board, and the cost of the member and the number of steps for pasting are required. There is a problem that the cost of the product becomes higher accordingly.
If a metal plate or a highly heat conductive member (cushion material) is attached in the vicinity of the heating element, other electronic parts cannot be mounted in the attached region or place, and the area where the parts can be mounted is reduced. There is also a problem that it cannot be used effectively.

  Therefore, the flex-rigid board on which the heating element is mounted has a problem that must be solved in a structure that can release heat from the heating element without using other members.

  In order to solve the above problems, the flex-rigid board of the present invention has the following configuration.

(1) A rigid part having a flexible board on which a heating element is mounted, a conductive member of a surface layer is laminated on the outer side, and a conductive member of an inner layer is laminated on the inner side; The flexible substrate is formed by extending the flexible substrate of the rigid portion, and the conductive member of the inner layer forming the flexible substrate of the flexible portion is brought into contact with the housing.
(2) The thermal via is drilled in the rigid portion, and the conductive member of the surface layer and the conductive member of the inner layer are in a conductive state inside the thermal via. Flex rigid board.
(3) The flex-rigid substrate according to any one of (1) to (2), wherein a second rigid portion is provided in the flexible portion.

  ADVANTAGE OF THE INVENTION According to this invention, propagation | transmission of the heat | fever to a housing | casing can be implement | achieved cheaply and easily by using the electroconductive member (inner layer copper foil) of the flexible substrate which comprises a flex-rigid board as a heat dissipation path.

It is sectional drawing of the flex-rigid board | substrate which concerns on this invention. It is sectional drawing of the flex-rigid board | substrate of the 1st example in a prior art. It is sectional drawing of the flex-rigid board | substrate of the 2nd example in a prior art. It is sectional drawing of the flex-rigid board | substrate of the 3rd example in a prior art.

  Next, an embodiment of a flex-rigid substrate according to the present invention will be described below with reference to the drawings.

  The flex-rigid board of the present invention extends the flexible board from the end face of the flex-rigid board in order to use the conductive member (copper foil) of the inner layer of the flexible board constituting the flex-rigid board as a heat transmission path. The part of the copper foil on the free end side is stripped, and the stripped copper foil is brought into contact with the housing, etc., so that the copper foil on the inner layer of the flexible substrate is exposed to the housing and heat dissipation. It can be made easier.

  As shown in FIG. 1, the flex-rigid substrate has a structure in which a flexible substrate 11 is formed by laminating a conductive member (inner copper foil) 13 and an insulating coverlay 14 on both sides of a polyimide base 12. , A prepreg 15, a copper foil (conductive member) 16 as a surface layer, a solder resist 17 as an insulator, and a heating element 18 such as an IC mounted on the solder resist 17. A second rigid portion 24 formed by laminating a prepreg 21, a copper foil 22 as a surface layer, and a solder resist 23 as an insulator on the flexible substrate 11 extended from the portion 19 and the first rigid portion 19, and the second rigid portion 24 And a flexible portion 25 in which the flexible substrate 11 is extended from the end surface of the rigid portion 24.

The flexible part 25 is an extension of the flexible substrate 11, has a flexible structure that can be bent, and is a copper foil that is a conductive member on both sides of a polyimide base material 26 provided at the center position. 27a and 27b are provided, and an insulating cover lay 28a is laminated on the surface of the copper foil 27a, and an insulating cover lay 28b is laminated on the surface of the copper foil 27b. Then, one cover lay 28b on the free end side is peeled off, the copper foil 27b is exposed, and the exposed copper foil 27b is in direct contact with the housing 29.
In the embodiment, the copper foil 27b which is bent and exposed by bending the flexible portion 25 is configured to come into contact with a part of the casing 29. However, the present invention is not limited to this, and the copper foil 27a side is not bent. The structure which contacts the housing | casing 29 may be sufficient.

  On the other hand, a thermal via 20 is formed in the first rigid portion 19, and the surface layer copper foil 16 and the inner layer copper foil 13 forming the flexible substrate 11 are brought into contact with each other inside the thermal via 20.

  In this way, by bringing the copper foils 16 and 13 into contact with each other inside the thermal via 20, the heat generated from the heating element 18 is transmitted to the copper foils 16 and 13 of the first rigid portion 19, and the copper foils 16 and 13. The heat transferred to the copper foil 13 of the flexible substrate 11 is further transferred to the copper foil 13 of the second rigid portion 24, and the transferred heat passes through the copper foil 27 a of the flexible portion 25 in the direction indicated by the arrow P. Then, the heat is radiated to the side of the casing 29 that is in contact with it. Similarly, the transmitted heat reaches the copper foil 27b of the flexible portion 25 in the direction indicated by the arrow Q, and is radiated to the contacted casing 29 through the polyimide base material 26 and the copper foil 27a.

  In particular, the cover lay 28a is peeled off, and the heat radiation from the copper foil 27a that is in direct contact with the housing 29 with the exposed copper foil 27a enables heat radiation from the entire exposed surface, which is extremely good. Heat dissipation is obtained.

  In addition, the heat conductivity of the heat radiating member described as high thermal conductivity described in the prior art is at most about 16 W / m · K, generally about 1 to 3 W / m · K. The thermal conductivity of the copper foil of the flexible substrate (FPC) is much higher than that of the heat radiating member, which is 400 W / m · K.

  Do not use a special member to dissipate heat by transmitting the heat generated from the heating element to the housing from the copper foil of the flexible board that constitutes the flex-rigid board, in the flex-rigid board equipped with the heating element. Provided is a flex-rigid board capable of releasing heat generated from a heating element.

11 flexible substrate 12 polyimide base material 13 inner layer copper foil (conductive member)
14 Coverlay 15 Prepreg 16 Surface copper foil (conductive member)
17 Solder resist 18 Heating element 19 First rigid portion 20 Thermal via 21 Pre-preg 22 Surface layer copper foil 23 Solder resist 24 Second rigid portion 25 Flexible portion 26 Polyimide substrate 27a Copper foil 27b Copper foil 28a Cover lay 28b Cover lay 29 Housing body

Claims (3)

A rigid portion including a flexible board on which a heating element is mounted, a conductive member of a surface layer is laminated on the outside, and a conductive member of an inner layer is laminated on the inside;
It consists of a flexible part formed by extending the flexible substrate of the rigid part,
A flex-rigid board, wherein the inner layer conductive member forming the flexible board of the flexible part is brought into contact with a casing.   The flex-rigid substrate according to claim 1, wherein a thermal via is formed in the rigid portion, and the conductive member of the surface layer and the conductive member of the inner layer are brought into conduction in the thermal via. .   The flex-rigid substrate according to claim 1, wherein a second rigid portion is provided in the flexible portion.

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