JPH0636475B2 - Multilayer printed wiring board - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a multilayer printed wiring board having good heat dissipation.

[Prior art]

Conventionally, a multilayer printed wiring board has a structure in which a plurality of layers of conductive circuits are laminated via insulating layers as shown in FIG. In FIG. 3, 1 is an outermost conductor circuit surface forming a conductive circuit, 2 is a conductor circuit surface immediately inside thereof, and 3 is a conductor circuit surface inside thereof. These conductor circuit planes are
The layers are laminated with a prepreg 4 which is an insulating layer interposed therebetween. 5
Is a through hole communicating from the upper surface to the lower surface. The through hole 5 is a hole for mounting components and forming an electric circuit between conductor circuit surfaces. As the prepreg 4, a glass cloth as a base material is impregnated with an epoxy resin, a polyimide resin, a modified polyimide resin, or the like.

However, such a prepreg 4 as an insulating layer is inferior in heat dissipation, and therefore heat is generated when a heat-generating component is mounted on the outermost conductor circuit surface 1 or in high-density mounting. Alternatively, there are drawbacks such as failure due to heat storage. In addition, there is a problem that there is a limit to the mounting of heat-generating components to prevent this failure. Therefore, in order to promote heat dissipation, a radiation fin is provided on the heat-generating component to be mounted, or a radiation fin is provided at the end of the conductor circuit surface 1. However, this is because the radiation fin itself is bulky. In addition, there are problems that there is a limit to miniaturization of the obtained electronic device and that the packaging density of the card assembly cannot be increased.

Therefore, recently, as shown in FIG. 2 in addition to the structure shown in FIG. 3, a heat conductive metal plate-like member is provided between the outermost conductor circuit surface 1 and the conductor circuit surface 2 immediately inside thereof. A multilayer printed wiring board in which 6 are arranged has been proposed (Japanese Patent Laid-Open No. 61-2).
41999 No.). However, even in this case, there is a problem that the heat dissipation is not sufficient.

[Object of the Invention]

The present invention has been made to solve the above-mentioned drawbacks and problems, and an object thereof is to provide a multilayer printed wiring board having good heat dissipation. This multilayer printed wiring board can be suitably used especially for electronic equipment using high-speed and high-density integrated circuit elements, such as high-speed computers and LSI testers.

[Structure of Invention]

Therefore, in the present invention, in a multilayer printed wiring board in which a plurality of layers of conductor circuits are laminated with an insulating layer of a non-heat conductive material, the outermost conductor circuit surface and the conductor circuit surface immediately inside thereof are formed. A metallic plate-shaped body having heat conductivity is arranged in a limited manner, and the thermal conductivity is 0 around the metallic plate-shaped body.
It is characterized in that an insulating heat-dissipating material of 5 × 10 ⁻³ cal / cm · sec · ° C. or more is arranged, and a plurality of layers of conductor circuits are provided inside the conductor circuit surface immediately inside.

Hereinafter, the configuration of the present invention will be described in detail with reference to the drawings. The same parts and parts as those in FIGS. 2 and 3 are represented by the same numbers.

FIG. 1 is a cross-sectional explanatory view of an example of the multilayer printed wiring board of the present invention. In FIG. 1, a thermally conductive metallic plate-like body 6 is arranged between the outermost conductor circuit surface 1 and the conductor circuit surface 2 immediately inside thereof. Inside the conductor circuit surface 2, a plurality of layers of conductor circuits are provided via an insulating layer of a non-thermally conductive material, which is represented by the prepreg 4.

The metallic plate member 6 may be arranged either between the upper conductor circuit surface 1 and the conductor circuit surface 2 immediately inside thereof, or between the lower conductor circuit surface 1 and the conductor circuit surface 2 immediately inside thereof. It may be both between the upper conductor circuit surface 1 and the conductor circuit surface 2 immediately inside thereof, and between the lower conductor circuit surface 1 and the conductor circuit surface 2 immediately inside thereof.

The metallic plate-shaped body 6 has good heat dissipation and good thermal conductivity, and includes, for example, an aluminum plate, a silicon steel plate, an iron plate,
A metal plate typified by a stainless steel plate, a copper plate or the like, or a powdered, fiberized or cut fiberized material of these metals which is solidified with a small amount of a binder to form a sheet or layer. The thickness of the metallic plate-like body 6 is not particularly limited, but if it is too thin, the heat dissipation effect decreases, and if it is too thick, it becomes heavy, so it is suitable that it is 10 μm to 5.0 mm, preferably 50 μm to 2 mm. Is. In this metallic plate-shaped body 6, clearance processing is previously applied to a portion where the through hole 5 penetrates. That is, a hole having a diameter slightly larger than the hole diameter of the through hole 5 is preliminarily formed in an appropriate portion of the metallic plate body 6.

By arranging the metallic plate-like body 6 in this way, it is possible to disperse the heat over the entire wiring board even when the mounted electronic components generate heat, so that the concentration of heat can be avoided,
Therefore, since the entire wiring board serves as a heat dissipation area, the heat dissipation effect is improved.

Further, in order to further enhance the heat dissipation effect, in the present invention, as shown by 7 in FIG. 1, around the metallic plate-like body 6,
Insulating heat dissipation material is placed. The heat dissipation material has a thermal conductivity of 0.5 × 10 ⁻³ cal / cm · sec · ° C. or higher, and for example, ceramic powder such as alumina or aluminum nitride, or mica mixed with an organic material. Is. Examples of the organic material include epoxy resin, acrylic resin, polyimide resin, modified polyimide resin, and silicone resin. By disposing this heat dissipation material, it becomes easy to dissipate the heat generated from the mounted electronic components to the metallic plate-like body 6 through the heat dissipation material, and the heat dissipated to the metallic plate-like body 6 is wired through the heat dissipation material. It is easy to dissipate from the surface of the plate.

In the present invention, the insulating heat-dissipating material 7 is the metallic plate-like body 6.
At the same time, it is arranged only between the outermost conductor circuit surface 1 and the conductor circuit surface 2 immediately inside thereof. That is, the heat dissipation material 7 is arranged only on the outer side portion of the multilayer printed wiring board. This is because the heat dissipation material (for example, alumina) has the property of increasing the dielectric constant of the multilayer printed wiring board and changing the impedance. Therefore, if it is placed in the inner layer, the signal propagation speed of the inner layer circuit will be increased. This is because the electrical characteristics of the wiring board are changed, such as delaying, which causes a deviation of the circuit characteristics from the design value.

Further, since the electronic components are generally arranged on the surface of the multilayer printed wiring board, the metallic plate-shaped body 6 and the heat dissipation material 7 are
If and are limitedly arranged between the outermost conductor circuit surface 1 and the conductor circuit surface 2 immediately inside thereof, it is possible to suppress the inhibition of the electrical characteristics of the wiring board as much as possible and use the minimum amount of material. It is possible to maximize the heat dissipation effect of electronic components.

In order to further enhance the heat radiation effect, as shown in FIG. 4, a material having a heat radiation property may be disposed between the mounted electronic component and the surface of the wiring board to eliminate the gap. Fourth
In the figure, a heat dissipation material 7 is arranged between an electronic component 8 which is a flat type IC and a conductor circuit surface 1 and between an electronic component 9 which is a DIP type IC and a conductor circuit surface 1. Thereby, the heat generated in the electronic component can be dissipated to the wiring board through the heat dissipation material 7 and further to the metallic plate-like body 6, and the heat dissipation effect can be further enhanced. The heat dissipation material 7 may be arranged by screen printing or a dispenser.

Further, on the outermost conductor circuit surface 1, it is preferable to leave, as a heat dissipation promotion area, a portion where a circuit is not formed at an appropriate portion thereof (either the end portion, the central portion, or any portion thereof).
As a result, the heat dissipated in the metallic plate-shaped body 6 can be guided to the heat dissipation promoting area and dissipated to the outside, so that the heat dissipation effect can be further enhanced.

Next, an example of a procedure for manufacturing the multilayer printed wiring board of the present invention will be specifically described.

 Preparation of inner layer material.

The inner layer material may be manufactured by a general method for manufacturing a multilayer board. For example, a double-sided copper-clad laminate is faced, a photosensitive photoresist is laminated on the face, and a circuit is formed on both sides through steps such as exposure, development, etching, and photoresist stripping, and further black if necessary. Treat with copper oxide and dry. One of the laminated plates having circuits formed on both sides in this manner is an inner layer material, or a plurality of the laminated plates are intercalated with a prepreg obtained by impregnating glass cloth with epoxy resin, polyimide resin, modified polyimide resin or the like. The laminated material is the inner layer material.

 Preparation of outer layer material.

As shown in FIG. 5, clearance processing is performed on a portion of the metallic plate-shaped body 6 (for example, an aluminum plate) through which the through hole penetrates. That is, the hole 10 is formed with a diameter slightly larger than the diameter of the through hole. The hole 10 can be opened by a drilling method or an etching method. Next, preferably, in order to stabilize the adhesiveness, a surface treatment such as etching treatment or primer treatment is performed on the surface of the metallic plate-shaped body 6.

On the surface of the metallic plate-shaped body 6, as shown in FIG. 5, an insulating heat-dissipating material 7 is arranged around. Bond copper foil 11 on it. The lamination of the copper foil 11 may be performed by using a hot roll laminator or a heating press as appropriate.
In this way, the outer layer material is obtained.

 Lamination of inner layer material and outer layer material.

The outer layer material shown in FIG. 5 is, as shown in FIG.
It is superposed on the inner layer material via the prepreg 4. Next, by thermocompression bonding, a multilayer board having copper foils 11 bonded to both surfaces is obtained.

Further, only the outer layer material is heated or thermocompression-bonded in advance to cure the heat radiation material, the hole filling material, etc., and then it is laminated on the inner layer material via the prepreg 4, and thermocompression bonded to the copper foil 11 on both sides in the same manner.
It is possible to obtain a multilayer board in which

When the depth of the hole 10 of the metallic plate-shaped body 6 is deep, that is, when the thickness of the metallic plate-shaped body 6 is large, the prepreg 4
When the outer layer material and the inner layer material are stacked through the
Air may accumulate in the holes 10 due to insufficient flow of resin or the like into the holes 10. In order to prevent this air accumulation, holes will be formed when vacuum forming is performed using a vacuum press or an autoclave.
A dent is formed on the surface of the copper foil 11 corresponding to. These problems do not become a problem when the metallic plate-shaped body 6 is thin, but become apparent when the thickness of the metallic plate-shaped body 6 exceeds 0.2 mm. As a countermeasure against this, for example, a resin compound corresponding to the volume of the hole 10 may be injected into the hole 10. The resin composition preferably has the same composition as that of the heat dissipation material 7, but it is difficult to inject when the compounding amount of ceramic powder or mica in the resin compounding is large. It is better to use less. Further, when the amount of the solvent is large, when the solvent is dried, the recesses in the portion increase, so that it is best to use a solventless epoxy resin or the like. As a method of injecting the resin composition into the hole 10, for example, a dispenser which can inject a trace component that is commercially available recently can be used with high precision, or a resin composition as a simple method. May be embedded with a squeegee to make the surface smooth. When the resin composition is injected into the hole 10 as described above, in order to prevent the resin composition from flowing out from the hole 10, the surface of the metallic plate-shaped body 6 on the opposite side of the copper foil 11 is coated with 1 It is better to stick resin compound layers that do not flow in layers. The insulating heat dissipation material described above can be used for this resin compound layer.

 Processing after lamination.

From the top surface to the bottom surface of the multilayer board thus obtained,
As shown in FIG. 3A, the through holes 5 are penetrated, desmearing is performed (residues such as resin components adhering to the inside of the through holes 5 are removed), and the inside of the through holes 5 is pre-treated by chemical copper plating. Next, as shown in FIG. 7 (B), the inside of the through hole 5 is chemically copper-plated to deposit copper 20, and then, as shown in FIG. 7 (C), panel plating (electro-copper plating) is performed. To attach electrolytic copper 21. Then, Figure 7 (D)
As shown in Fig. 7, a photoresist 22 is provided on the electrolytic copper 21, and the circuit is imaged (baked), and pattern plating (electroplating = copper plating and solder plating) is performed as shown in Fig. 7 (E). Copper and solder 23 is attached, and the seventh
As shown in FIG. 7F, the photoresist 22 is peeled off and etched, and then solder reflow (fading) is performed as shown in FIG. 7G, or solder removal is performed as shown in FIG. 7H. I do. Next, as shown in FIG. 7 (I), solder resist printing is performed (the place where the heat-generating component is mounted may be clear or may not be printed), and sympol printing 24 is provided, and FIG. Provide solder 25 (solder leveler) as shown in (J). In this way, a multilayer printed wiring board can be obtained.

Examples and comparative examples are shown below.

Example A heat-dissipating material was applied to a non-glossy surface of an electrolytic copper foil having a thickness of 18 μm using a comma coater so that the solid content after drying was 50 μm and dried. The heat dissipation material used here had a thermal conductivity of 5.1 × 10 ^-3 cal / cm · sec · ° C,
80 parts by weight of alumina powder having an average particle size of 5μ, CTBN modified bisphenol A type epoxy resin (epoxy equivalent 250) 25
Parts by weight, solid bisphenol A type epoxy resin (epoxy equivalent 260) 20 parts by weight, diaminodiphenyl sulfone 5
One part by weight and 100 parts by weight of methyl ethyl ketone were mixed using a high-speed stirrer, dried and cured.

A large number of holes with a diameter of 2 mm were drilled in predetermined places on the surface of the heat-dissipating material of the copper foil with heat-dissipating material obtained in this way, and the thickness was etched with a mixed solution of sulfuric acid and chromic acid.
A 150 μ aluminum plate was put together, and then 50 parts by weight of a liquid bisphenol A type epoxy resin (epoxy equivalent 190) and 5 parts by weight of diaminodiphenyl sulfone were used to embed the resin mixture in the hole. A solvent-type epoxy resin composition was prepared and embedded in the hole with a squeegee to smooth the surface.

Next, a 100 μm-thick sheet of heat-dissipating material, which was separately applied to the release film, was applied to the surface of the aluminum plate by
The pieces were laminated with a hot roll laminator heated to ℃, and the aluminum plate was covered with the heat dissipation material. The obtained laminate was heated and pressed at 200 ° C. for 2 hours to be cured by pressing. As a result, an aluminum core outer layer material was obtained. Both the copper foil surface and the heat dissipation material surface were smooth on the surface of this aluminum core outer layer material.

Then, the outer layer material was laid on both sides via a prepreg (thickness 100 μ) on the inner layer material with circuits already formed on both sides, and cured by a press at 170 ° C. for 2 hours at a pressure of 40 kg / cm ₂ ,
A multilayer board having copper foil bonded to both sides was obtained. No dents or bulges were observed on the copper foil surface of this multilayer board.

The multilayer printed wiring board of the present invention was obtained by punching a through hole having a diameter of 1 mm or the like in this multilayer board by a usual method for manufacturing a multilayer printed wiring board. However, at the end of the outermost conductor circuit surface, a portion not forming a circuit was left as a heat dissipation promotion area. The area of this heat dissipation promotion area was 15% of the total area of the heat dissipation promotion area and the outermost conductor circuit surface.

Comparative Example 1 A large number of holes with a diameter of 2 mm were previously drilled at predetermined locations,
A degreased aluminum plate with a thickness of 50 μm was produced.

Next, the aluminum plate is overlaid on the inner layer material with circuits already formed on both sides via prepreg (thickness 100 μ, 2 sheets),
Prepreg (thickness 100μ, 2 sheets) is stacked on the aluminum plate, 18μ copper foil is stacked on it, and pressed at 170 ° C.
The prepreg was cured for 2 hours at a pressure of 40 kg / cm ² to obtain a multi-layer board having copper foils bonded to both sides. No dents or bulges were observed on the copper foil surface of this multilayer board.

A multi-layer printed wiring board was obtained by punching through holes having a diameter of 1 mm in the multi-layer board by a usual method for producing a multi-layer printed wiring board.

Comparative Example 2 A heat-dissipating material was applied to the non-glossy surface of an electrolytic copper foil having a thickness of 18 μm using a comma coater so that the solid content after drying was 50 μm, and dried. The heat-dissipating material used here was 80 parts by weight of alumina powder having an average particle size of 3μ, and CTBN-modified bisphenol A type epoxy resin (epoxy equivalent 25
0) 45 parts by weight, 5 parts by weight of diaminodiphenylmethane and 100 parts by weight of methyl ethyl ketone were mixed using a high speed stirrer.

On the surface of the heat-dissipating material of the copper foil with heat-dissipating material obtained in this way, many holes with a diameter of 2 mm were previously drilled at predetermined places, and a degreased aluminum plate with a thickness of 150 μ was put together.
An outer layer material was produced by pasting through a hot roll laminator heated at 0 ° C.

Next, the outer layer material was laminated on both sides with a prepreg (thickness 100 μ, 2 sheets) on the inner layer material with circuits already formed on both sides, and pressed at 170 ° C. for 2 hours at a pressure of 40 kg / cm ² . The prepreg was cured to obtain a multilayer board in which copper foil was attached to both surfaces. No dents or bulges were observed on the copper foil surface of this multilayer board.

A multi-layer printed wiring board was obtained by punching through holes having a diameter of 1 mm in the multi-layer board by a usual method for producing a multi-layer printed wiring board. However, at the end of the outermost conductor circuit surface, a portion not forming a circuit was left as a heat dissipation promotion area. The area of this heat dissipation promotion area is 15% of the total area of the heat dissipation promotion area and the outermost conductor circuit surface.
Met.

Comparative Example 3 A multilayer printed wiring board was obtained by a conventional method without inserting a metal plate (layer).

At this time, the thickness of the copper foil used for the outermost layers on both sides was 18 μm, and two 100 μm prepregs were used as the insulating layer between the circuits thereunder as in the case of Examples and Comparative Examples 1-2. .

Next, in order to see the heat dissipation effect of these multilayer printed wiring boards (Examples, Comparative Examples 1 to 3), as shown in FIG. When the component 8 and the electronic component 9 which is a DIP type IC are mounted, the electronic component 8 which is a flat type IC and the DIP type I are mounted on the multilayer printed wiring board 30 of Comparative Example 3 as shown in FIG.
When the electronic component 9 which is C is placed and the heat radiation fin (heat sink) 31 is provided on these electronic components 8 and 9, as shown in FIG. 10, the multilayer printed wiring board of Comparative Example 1 is obtained.
When the electronic component 8 which is a flat type IC and the electronic component 9 which is a DIP type IC are placed on 30, the flat type IC is mounted on the multilayer printed wiring board 30 with the heating promotion area 32 of Comparative Example 2 as shown in FIG. When the electronic component 8 which is a DIP type IC and the electronic component 9 which is a DIP type IC are mounted, the electronic component 8 which is a flat type IC is mounted on the multilayer printed wiring board 30 with the heat dissipation promoting area 32 of the embodiment as shown in FIG. An electronic component 9 which is a DIP type IC is placed, and a heat radiation material 7 is screen-printed to a thickness of 200 μ between these electronic components 8 and 9 and the multilayer printed wiring board 30, and As shown in FIG. 13, the multilayer printed wiring board 30 with the heat dissipation promoting area 32 of the embodiment is shown in FIG.
When the electronic component 8 which is a flat type IC and the electronic component 9 which is a DIP type IC are mounted on the above, the heat dissipation properties of the heat generated by the electronic components 8 and 9 were evaluated. The results are shown in Table 1. In FIG. 8 to FIG. 13, the arrow shows the state of heat dissipation.

Evaluation method of heat dissipation: 23 ± 2 for a multilayer printed wiring board on which electronic components 8 and 9 are mounted
It was placed horizontally on a desk in a room at ℃, turned on, and allowed to stand for 30 minutes until thermal equilibrium was reached. Next, electronic components 8 and 9
A temperature-measuring probe was applied to the surface of and the temperature was measured after about 5 minutes. The evaluation was made as 0% in the case of FIG. 8 (without the heat dissipation fin) and 100% in the case of FIG. 9 (with the heat dissipation fin).

As is clear from Table 1, the multilayer printed wiring board of the present invention (FIGS. 12 and 13) is the conventional multilayer printed wiring board (without the heat radiation fins of FIG. 8 and without the heat radiation material of FIG. 10). It is clear that the heat dissipation property, that is, the heat dissipation property is superior to the case where the heat dissipation material exists only between the outermost conductor circuit surface and the metal plate in FIG. 11). .

〔The invention's effect〕

As described above, according to the present invention, the following effects can be obtained.

Since heat is dispersed throughout the multilayer printed wiring board, heat concentration can be avoided.

The entire multilayer printed wiring board serves as a heat dissipation area, and the heat dissipation effect is increased.

By providing the heat dissipation promotion area, heat can be guided from the heat dissipation area to the outside, and the heat dissipation effect can be further enhanced.

Since the heat radiation fin is unnecessary, the mounting density of the card assembly can be increased.

Since the temperature inside the device provided with the multilayer printed wiring board does not rise, the reliability of the device is improved.

The inhibition of the signal propagation speed and other electrical characteristics of the multilayer printed wiring board is suppressed as much as possible, and a high heat dissipation effect is effectively obtained.

[Brief description of drawings]

FIG. 1 is a sectional explanatory view of an example of a multilayer printed wiring board of the present invention, FIGS. 2 and 3 are sectional explanatory views of an example of a conventional multilayer printed wiring board, and FIG. 4 is an electronic diagram of a multilayer printed wiring board. It is explanatory drawing which shows a mode that the component was mounted. 5, 6 and 7 (A) to 7 (J) are explanatory views showing an example of a manufacturing process of the multilayer printed wiring board of the present invention. FIG. 8 to FIG. 13 are explanatory views showing a state in which electronic components are mounted on a multilayer printed wiring board and a heat radiation test is performed. 1, 2, 3 ... Conductor circuit surface, 4 ... Prepreg, 5 ...
Through hole, 6 ... Metal plate, 7 ... Heat dissipation material,
8, 9 ... Electronic parts, 11 ... Copper foil, 30 ... Multilayer printed wiring board, 31 ... Radiation fins, 32 ... Heat radiation promotion area.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mankio Goto 1-28-1 Minamihara, Hiratsuka City, Kanagawa Prefecture (72) Inventor Akira Furuki 3-12-18 Jiyugaoka, Meguro-ku, Tokyo (72) Inventor Takehiro Furuse Kanagawa 1427 Yamanishi, Ninomiya-cho, Naka-gun, prefecture (72) Inventor Hyoshiro Hashiba 1-1-28 Higashi-Nagatani, Minami-ku, Yokohama-shi, Kanagawa (72) Inventor Shoichi Terada 2-4-6, Tamagawa, Ota-ku, Tokyo (72) Invention Toshio Komine 3970-4 Otani, Ebina City, Kanagawa Prefecture (72) Inventor Hiroshi Fujii 213, Irisawa, Fujisawa City, Kanagawa Prefecture (56) References JP 61-241999 (JP, A) JP 60-171791 (JP, JP, 17171791, JP, A) JP-A-60-171792 (JP, A)

Claims (1)

[Claims] 1. A multilayer printed wiring board comprising a plurality of layers of conductor circuits laminated with an insulating layer of a non-thermally conductive material interposed between the outermost conductor circuit surface and the conductor circuit surface immediately inside thereof. As a limitation, arrange a heat conductive metal plate,
Furthermore, a thermal conductivity of 0.5 × 10 is provided around the metallic plate.
^-3 cal / cm ・ sec ・ Insulating heat dissipation material above ℃ is placed,
A multilayer printed wiring board in which a plurality of layers of conductor circuits are provided inside the conductor circuit surface immediately inside.