JPH01286395A - Printed wiring board - Google Patents

Abstract

PURPOSE:To obtain a printed wiring board having high heat dissipating property, a reduced thickness in a simple structure, and large degree of freedom of circuit design by laminating a plurality of prepregs and a printed board with a copper foil on both side faces of a plurality of heat pipes. CONSTITUTION:A plurality of small-diameter heat pipes 34 each having, for example, 1mm of diameter are provided at a predetermined interval in parallel by positioning means 36, and a plurality of prepregs 32 and a printed board 30 with a copper foil are laminated on both side faces of the pipes 34. The laminated pipes 34, the prepregs 32 and the board 30 are heated and press- bonded from both side faces to form printed wiring boards, and heats generated from electronic components at the time of the amount and conduction of the components are dissipated by a plurality of fine pipes 34. Thus, since a printed wiring board can be formed by using the small-diameter heat pipes, the thickness is reduced, its heat dissipating property is enhanced, and the degree of freedom of circuit design is made large.

Description

[Detailed Description of the Invention] Overview Regarding a printed wiring board on which electronic components are mounted, the present invention aims to provide a printed wiring board that has a simple structure, has high heat dissipation, is thin, and has a large degree of freedom in circuit design. , A plurality of heat pipes are arranged in parallel at predetermined intervals by a positioning means, a plurality of prepregs and a printed board with copper foil are laminated on both sides of the plurality of heat pipes, and the laminated heat pipes, prepreg, and A printed board with copper foil is formed by heating and press-bonding both sides, and the heat generated by the electronic components is dissipated by the plurality of heat pipes during electronic component mounting and operation.

Industrial applications The present invention relates to a printed wiring board on which electronic components are mounted.

BACKGROUND OF THE INVENTION As various electronic devices are required to be smaller, faster, and more multifunctional, semiconductor devices are becoming faster and more highly integrated. Moreover, there is a trend towards smaller packages and multi-terminals, and D I
In addition to insertion mounting such as P (DIAL IN LINE PACKAGE) and PGA (PIN GRID ARRAY), imposition mounting such as flat packages has become widely used.

Printed wiring boards on which such packages are mounted are required to increase wiring capacity through high density and high multi-layering, and to improve heat dissipation. This has become an important topic as the amount of heat generated and the density of heat generation increases due to the high-density mounting of components.

Since this heat dissipation performance is particularly closely related to system performance, reliability, lifespan, etc., it is desired to provide a printed wiring board with high heat dissipation efficiency.

2. Description of the Related Art As shown in FIG. 6, a conventional printed wiring board has a metal core 10 made of copper or aluminum covered with an insulating layer 12 made of epoxy resin, etc., and has a plurality of through holes 14 and circuits at predetermined locations. A pattern 16 and the like are formed.

A plurality of holes 18 are formed at a predetermined pitch in the width direction of the metal core 10 by a drill or the like, and a heat pipe 20 is inserted into each of the holes 18 .

The heat pipe 20 is made of a metal with good thermal conductivity, such as copper, and has a working fluid such as water sealed inside it, and when a temperature difference occurs, the internal working fluid repeatedly evaporates and condenses. , which transports heat.

A heat pipe insertion hole 18 is formed in the metal core 10 using a drill or the like, but the depth of this process is generally limited to approximately 20 times the hole diameter, and the hole 18 is formed in the axial direction of the heat pipe 20. If you want dimensions in the order of 100 to 200, the diameter A of the heat pipe insertion hole 18 should be φ5 to 10.
It is necessary to make it into a position. As a result, the dimensions of each part were, for example, the diameter of the heat pipe 20 was 5 to 10 mm, the diameter B of the through hole 14 was 0.9 mm, and the pitch C was about 10 mm.

FIG. 7 shows how electronic components (resistors) 22 are mounted in the through holes of this printed wiring board. Even if the electronic component 22 generates heat when energized, the heat pipe 20 works to disperse and dissipate the heat throughout the wiring board. This prevents localized high temperatures and prevents the electronic components 22 from deteriorating.

Problems to be Solved by the Invention As described above, conventionally, a heat pipe insertion hole with a diameter of 5 to 10 mm was formed, and a heat pipe having a diameter to fit into the hole was inserted. It was not possible to narrow the dimension C) of the DIP type IC24 with a distance between lead pins of 2.54 mm, as shown in
etc., could not be mounted on a printed wiring board in a direction perpendicular to the axial direction of the heat pipe.

Further, the thickness of the printed wiring board cannot be similarly reduced, and the leads of ICs and the like do not reach the opposite surface, so there is a problem that soldering cannot be performed by flow soldering.

Another problem was that the process of drilling holes in the width direction of the metal core and inserting the heat pipe into the holes was complex and difficult.

The present invention has been made in view of these points, and its purpose is to have a simple configuration, high heat dissipation, and
An object of the present invention is to provide a printed wiring board that is thin and has a high degree of freedom in circuit design.

Means for Solving the Problems A plurality of small diameter heat pipes each having a diameter of, for example, φlrnrn are arranged in parallel at a predetermined interval by a positioning means, and a plurality of prepregs are placed on both sides of the plurality of heat pipes, and Laminate printed boards with copper foil.

A printed wiring board is formed by heating and press-bonding laminated heat pipes, prepreg, and a printed board with copper foil from both sides, and when electronic components are mounted and energized, the heat generated by the electronic components is dissipated through multiple small-diameter heat pipes. Configure it to do so.

Function According to the configuration of the present invention, a small diameter heat pipe (for example, φ
By using 1mm), the thickness of printed wiring boards can be made much thinner than before, and electronic components with short leads can be soldered using flow soldering.

In addition, the distance between the heat pipes is set to 2.54 mm, for example.
Or, if the number is a multiple of this, the through holes can be formed at a pitch of 2°54mm, making it possible to mount DIP type ICs in a direction perpendicular to the axis of the heat pipe, etc., thereby improving circuit pattern design. Greater freedom.

Furthermore, the heat pipes can be arranged in parallel at a higher density than before, and the heat generated by the electronic components when energized can be efficiently dissipated by the small diameter heat pipe.

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

1 and 2 are diagrams for explaining one embodiment of the present invention, with FIG. 1 being a perspective view and FIG. 2 being a front view. 30
is a printed board with copper foil 30a formed on one side of an epoxy board, 32 is a prepreg made of glass cloth impregnated with epoxy resin, 34 is a heat pipe with a diameter of φl mm,
Reference numeral 36 denotes a positioning means made of woven glass cloth having a diameter of 0 mm.

As shown in the figure, the positioning means 36 can insert a plurality of heat pipes 34. At this time, the distance between adjacent heat pipes 34 is formed to be a predetermined value (2° 54 mm), and this positioning means 36 can be inserted. By the means 36, the vicinity of both ends of the plurality of heat pipes 34, or the vicinity of both ends and the intermediate part are connected like a raft. Four to five prepregs 32 each having a thickness of about 0.1 mm are laminated on both sides of the heat pipes 340 arranged in parallel by the positioning means 36, and further sandwiched between two printed boards 30.

Both sides are heated and pressurized using a press or the like.

As a result, the prepreg 32 flows into the gaps between the heat pipes 34 and then solidifies, fixing the heat pipes 34 at predetermined intervals, and bonding the two printed boards 30 together to form an integral body as shown in FIG. This is a laminate with copper foil on both sides.

Through holes and circuit patterns are formed on this laminate to form a printed wiring board.

In addition to the positioning means shown in FIGS. 1 and 2, the positioning means may be one made of epoxy resin or the like as shown in FIG. It may also be formed by

The positioning means made of glass cloth or epoxy resin is integrated with the prepreg when heated and pressurized, and the positioning means shown in FIG. 5 is removed after heating and pressurizing.

When forming a multilayer printed wiring board, a circuit pattern is previously formed on the other surface (inner surface) of the printed board 30 shown in FIG. This can be easily realized by laminating a plurality of other printed boards that have been formed.

With this configuration, the thickness of the printed wiring board can be 2.4 mm in the case of a double-sided board and 3°Q mm in the case of a multilayer board (4 layers). Note that when the insulation distance is 0.3 mm, the diameter of the through hole can be up to 0.94 mm, and after plating, the diameter of the through hole is 0.8 mm.

In this embodiment, the pitch of the heat pipes (the pitch of the through holes) was set to 2.54 m+n so that a DIP type IC could be mounted, but it is of course possible to use a pitch other than this.

According to this embodiment, it is possible to increase the density of heat pipes arranged in parallel, thereby improving heat dissipation and reducing restrictions on circuit pattern design. Furthermore, the manufacturing process simply adds a step of supplying a plurality of heat pipes arranged side by side at a predetermined interval using a positioning means to the laminated press molding step of a printed wiring board made of commonly used prepreg. Since no major design changes are required, it is advantageous in terms of cost.

Moreover, if the end portion of the heat pipe is made to protrude and a heat dissipation fin is attached to this protrusion, the heat dissipation performance can be further improved.

Effects of the Invention As detailed above, the present invention allows a printed wiring board to be formed using a small-diameter heat pipe, resulting in a thin board, high heat dissipation, and a high degree of freedom in circuit design. Since the structure is simple, it is possible to provide a printed wiring board that requires fewer manufacturing steps.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the structure of an embodiment of the present invention, Fig. 2 is a front view of the structure of an embodiment of the invention, Fig. 3 is a diagram showing the laminate after heating and pressure bonding, and Fig. 4 is a diagram of the positioning means. Figure 5 showing an example
6 is a perspective view of the configuration of a conventional printed wiring board, FIG. 7 is a diagram showing a state in which electronic components are mounted on a conventional printed wiring board, and FIG. 8 is a diagram showing another example of the positioning means. FIG. 2 is a diagram for explaining problems in the conventional technology. 30... Printed board, 32... Prepreg, 34... Heat pipe, 36... Positioning means.

Claims (1)

[Claims] A plurality of heat pipes (34) are arranged in parallel at predetermined intervals by a positioning means (36), and a plurality of prepregs (32) and copper are placed on both sides of the plurality of heat pipes (34). Laminated printed boards with foil (30), and the laminated heat pipes (34) and prepregs (32)
, and a printed board (30) with copper foil are formed by heating and pressing on both sides, and the heat generated by the electronic components is radiated by the plurality of heat pipes (34) when electronic components are mounted and energized. A printed wiring board featuring: