JP3515368B2 - High thermal conductive electromagnetic shielding sheet for mounting element, method of manufacturing the same, heat radiation of mounting element and electromagnetic shielding structure - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to the dissipate heat generated from the electronic equipment, and high thermal conductivity electromagnetic shielding sheet and a manufacturing method thereof electromagnetic noise shielding, parallel
And the heat radiation and electromagnetic wave shielding of the elements mounted on the printed circuit board.
Related to the field structure .

[0002]

2. Description of the Related Art Recently, countermeasures against heat generated from electronic devices have become a very important issue due to high-density mounting and high integration and high-speed of LSI accompanying with high performance and miniaturization of electronic devices. . Normally, for heat diffusion of the element that generates heat, between the heat source and the radiator or between the heat source and the metal heat transfer plate,
Silicone grease having a high thermal conductivity and a flexible thermally conductive silicone rubber material are interposed for the purpose of reducing the contact thermal resistance.

Further, since heat-generating elements having different sizes and heights are mounted at a high density, a heat-conductive material capable of filling various gaps is required, and a high heat-conductive silicone which is flexible and conforms to the shape. Rubber materials are being studied.

On the other hand, various obstacles caused by electromagnetic waves generated from mobile phones, televisions, personal computers, home electric appliances and the like have become problems, and materials and methods for shielding these electromagnetic waves have been earnestly desired. Electromagnetic wave shield materials include copper, nickel,
Compound metal foil such as chrome, aluminum, stainless steel, form metal film by treating case and parts by painting, plating, vapor deposition, and kneading metal fiber and metal filler. Methods such as molding housings and parts from various polymeric materials and magnesium alloys are being studied.

Conventionally, some heat conductive sheets in which conductive materials are compounded have been proposed. For example, JP-A-6
JP-A-291226 discloses a laminated structure of a metal foil and a heat-dissipating silicone sheet having a specific hardness, and JP-A No. 7-14950 discloses a heat-dissipating sheet having a specific hardness compounded with a metal mesh, and JP-A No. 9-55456. The publication discloses a cooling structure for a semiconductor device using a heat conductive sheet provided with a metal mesh made of metal having high thermal conductivity.

[0006]

These structures are intended for high heat conductivity, and a metal foil or metal mesh having high rigidity is combined with a heat conductive sheet. However, these composite heat conductive sheets are
When cutting or bending, there has been a problem that the metal foil or the metal mesh is bent or damaged. Furthermore, these inventions are aimed at high heat dissipation and were not developed for the purpose of imparting electromagnetic wave shielding properties.

On the other hand, Japanese Patent Publication No. 5-17720 discloses that
A heat-dissipation shield sheet in which a conductive layer for electromagnetic wave shielding is screen-printed on a heat-dissipative electrically insulating sheet is presented. Since this sheet does not use a metal foil, it was possible to avoid problems at the time of cutting or bending a heat conductive sheet in which a metal foil or a metal net-like material is combined. However, the number of steps for newly screen-printing the conductive layer is reduced to reduce productivity, and the conductive layer is limited to a material capable of being screen-printed, so that sufficient electromagnetic wave shielding properties are not exhibited.

The present invention provides a highly heat conductive electromagnetic wave shield sheet for a mounting device which is particularly excellent in thermal conductivity and electromagnetic wave shielding properties and has shape conformability to a heat generating device, workability and productivity, and a method for producing the same. The present invention provides a heat radiation and electromagnetic wave shield structure for an element mounted on a printed circuit board. That is, the present invention is a printed circuit board
High thermal conductivity electromagnetic wave shield for mounting element mounted on the mounting element.
Regarding a sheet, a graphite film having a large number of openings is embedded inside a silicone rubber layer containing a heat conductive filler and having an Asker C hardness of 30 or less after curing.
And, and the opening, shea <br/> silicone rubbers forming the silicone rubber layer is cured in a through-state, the silicone rubber
A high thermal conductive electromagnetic wave shield sheet for a mounting element, which is characterized in that it is formed by reinforcing a film layer . The present invention also provides a high thermal conductivity for the mounting device according to the present invention.
For manufacturing a conductive electromagnetic wave shielding sheet, wherein a graphite film having a large number of openings is placed on a silicone rubber layer containing a thermally conductive filler, and further a silicone rubber layer containing a thermally conductive filler. The present invention provides a method for producing a high thermal conductive electromagnetic wave shield sheet for a mounting element , comprising: stacking and curing the silicone rubber forming the silicone rubber layer while penetrating the silicone rubber into the opening of the graphite film. Further, the present invention provides the mounting device according to the present invention.
The high thermal conductivity electromagnetic wave shielding sheet of the above makes the lower surface side over the multiple elements mounted on the printed circuit board while deforming following the height difference, and the upper surface side contacts the radiator. The present invention provides a heat dissipation and electromagnetic wave shield structure for a mounting element that is mounted by mounting it.

The graphite film used in the present invention is not limited to a particular manufacturing method or shape as long as it is a two-dimensional sheet having a graphite structure. A carbon film obtained by carbonizing a polymer sheet having a chemical structure such as aromatic polyimide is further heated at a high temperature, for example, 3000 ° C. in an inert atmosphere.
A film-like material with a graphite structure developed by heat treatment with, graphite powder was soaked in acid and then heated, and the expansive graphite powder with the expanded graphite crystal layers was pressed to form a film. Expandable graphite film and so on. Flexible graphite films made from natural graphite, flexible graphite sheets, and what are called graphite sheets are included. Although the thickness of the graphite film is not specified, it is preferably in the range of 0.05 to 1.2 mm. If it is thinner than 0.05 mm, it is fragile and difficult to handle, and if it exceeds 1.2 mm, the flexibility and shape conformability to the element when it is made into a high thermal conductive electromagnetic wave shielding sheet are poor. Furthermore, the preferable thickness is 0.07 to 0.8 m.
The range is m.

As a measure against noise, the graphite film composited with the high thermal conductive electromagnetic wave shield sheet of the present invention is provided with terminals for connecting to the zero-volt power line of equipment in advance or the high thermal conductive electromagnetic wave shield sheet is provided. Make a hole and connect it to the equipment's zero-volt power line with a metal screw or bolt.

The heat conductive filler used in the present invention includes metal oxides and metal nitrides having good heat conductivity such as aluminum oxide, boron nitride, aluminum nitride, zinc oxide, silicon carbide, quartz and aluminum hydroxide. , Metal carbide, metal hydroxide, and at least one spherical, powder, fibrous, acicular, or scaly heat selected from metals and alloys such as silver, copper, gold, tin, iron, aluminum, and magnesium. Conductive fillers may be mentioned. Among them, aluminum oxide,
At least one thermally conductive filler selected from boron nitride, aluminum nitride, silicon carbide, and aluminum hydroxide is preferable because it has excellent electric insulation.

The blending amount of the thermally conductive filler is preferably 100 to 1000 parts by weight with respect to 100 parts by weight of the organopolysiloxane, although it varies depending on the types of the thermally conductive filler and the organopolysiloxane. 10
If it is less than 0 parts by weight, the thermal conductivity will be low, and if it is more than 1000 parts by weight, the filling property into the organopolysiloxane will be poor, and the viscosity will increase and the processability will deteriorate, which is not suitable.
The dispersibility can be improved by treating the surface of the thermally conductive filler with a known coupling agent.

The silicone rubber used as the base material of the present invention is obtained by curing a known organopolysiloxane. The curing method is not limited, and it is an addition reaction type consisting of an organopolysiloxane containing a vinyl group, an organopolysiloxane containing a hydrogen group on a silicon atom and a platinum catalyst, a radical reaction type using an organic peroxide, a condensation reaction. Examples include a type and a curing type by ultraviolet rays or electron beams. Above all, it is preferable to use a liquid addition reaction type organopolysiloxane which is easy to be filled with the thermally conductive filler.
In addition, known reinforcing silica, flame retardants, colorants, heat resistance improvers, adhesion aids, pressure sensitive adhesives and the like can be appropriately added.

The hardness of the silicone rubber layer after curing is excellent in flexibility when the Asker C hardness is 30 or less, and the shape conformability is further improved corresponding to the gap between the heating element and the radiator or the case having different heights. Get better The thickness of the sheet that determine the application but is typically in the range of 0.2mm~10mm practical.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The electromagnetic wave shielding sheet with high thermal conductivity of the present invention comprises a silicone rubber layer containing a thermally conductive filler, at least one surface of which a graphite film is laminated, or a silicone rubber containing a thermally conductive filler. The structure is characterized in that a graphite film is embedded in the layer.

As a method for embedding the graphite film, a silicone rubber layer containing a thermally conductive filler is inserted into a silicone rubber layer containing a thermally conductive filler by a bar coater method, a doctor blade method or a T-die. After film formation by extrusion molding method, calendar molding method, etc. by
It can be manufactured by placing a graphite film and then again forming a silicone rubber layer containing a thermally conductive filler of a certain thickness on the composite sheet.
The heat curing conditions of the silicone rubber layer at that time are not specified, and even if the silicone rubber layer containing the thermally conductive filler on one side is uncured or completely cured even after being partially cured. It doesn't matter afterwards.

In the present invention in which a graphite film is embedded in a silicone rubber layer containing a thermally conductive filler and having an Asker C hardness after curing of 30 or less, a plurality of openings having a diameter of 0.05 mm or more are previously formed in the graphite film. If the previously provided parts, by silicone rubber containing the upper and lower thermally conductive filler is cured through the opening in the graphite film, grayed to silicone rubber layer
The reinforcement effect by the Laphite film can be brought about. Regarding the shape of the opening, besides the circle and ellipse,
It may be polygonal.

The upper and lower silicone rubber layers containing the thermally conductive filler may have the same composition or different compositions. For the purpose of improving the handleability of the sheet, the hardness of the silicone rubber layer on one side is set to be large, and the entire sheet is reinforced by interposing a glass cloth or resin mesh or cloth-like thing in the silicone rubber layer. It is also possible to let.

On the other hand, the method for producing a high heat conductive electromagnetic wave shield sheet of the present invention is characterized in that an uncured silicone rubber containing a heat conductive filler is laminated on a graphite film, cured and integrally molded. And Therefore, it becomes unnecessary to use a fluororesin sheet such as Teflon or various release sheets reinforced with a glass fiber cloth, which has been used in the conventional manufacturing method, and it is possible to efficiently produce. In addition, the graphite film to be laminated or buried,
It is possible to improve the adhesiveness of the interface between the graphite film surface and the silicone rubber by performing a known surface treatment using a coupling agent, a primer, an adhesion-imparting agent, etc. after degreasing and washing in advance.

[0020]

EXAMPLE 1 The present invention will be described in more detail with reference to examples. FIG. 1 shows an embodiment of a high thermal conductive electromagnetic wave shield sheet of the present invention, which is embedded in a silicone rubber layer 1 using a graphite film having a thickness of 0.127 mm and containing aluminum oxide as a thermal conductive filler. It is sectional drawing of the made structure.

An addition type heat conductive liquid silicone compound (TSE3081 manufactured by Toshiba Silicone Co., Ltd.) containing aluminum oxide powder as a heat conductive filler is used, developed into a sheet by a doctor blade method, and heat cured, A heat conductive sheet having a thickness of 2 mm and an Asker C hardness of 27 was produced. The thickness of 0.127 on one side
mm graphite film (Grafoil GTA manufactured by Yuker Carbon Co., USA), and a heat conductive liquid silicone compound (TSE3081 manufactured by Toshiba Silicone Co., Ltd.) with a thickness of 2 mm and heat-cured to obtain a high heat conductive electromagnetic wave shielding sheet. Was produced.

The apparent thermal conductivity of the obtained high thermal conductive electromagnetic wave shield sheet was measured by a rapid thermal conductivity meter (QTM-500 manufactured by Kyoto Electronics Manufacturing Co., Ltd.). The electromagnetic wave shielding property was evaluated by the Advantest method. The workability was evaluated as "○" when the state of the cut surface when cut with a cutter was good, and "X" when the state of the cut surface was poor. Conformability properties, the upper portion of the substrate height was implement different semiconductor device, by placing the resultant high thermal conductivity electromagnetic shield sheet in contact with the radiator, what shape followability is good "○", Those with poor followability were marked with "x" . The results are shown in Fig. 7.

[0023]

Example 2 A graphite film (Nikafilm FL400 manufactured by Nippon Carbon Co., Ltd.) having a thickness of 0.2 mm in which numerous circular holes having a diameter of 0.5 mm were formed was used. A high thermal conductive electromagnetic wave shield sheet was produced in the same manner as in Example 1 except for the above. The thermal conductivity, electromagnetic wave shielding property, workability, and shape following property were evaluated in the same manner as in Example 1, and the results are shown in FIG. 7.

[0024]

Example 3 100 parts by weight of addition type liquid silicone (SE91 manufactured by Toray Dow Corning Silicone Co., Ltd.
87 L), a silane coupling agent (TSL-81 manufactured by Toshiba Silicone Co., Ltd.) as a thermally conductive filler.
A heat conductive silicone compound was prepared by filling 400 parts by weight of aluminum oxide powder (Alumina AS-20 manufactured by Showa Denko KK) surface-treated with 12). A thermal conductive sheet having a thickness of 2 mm and an Asker C hardness of 17 was produced by the doctor blade method in the same manner as in Example 1. The graphite film of Example 1 was laminated on one side thereof to prepare a high thermal conductivity electromagnetic wave shield sheet. The thermal conductivity, electromagnetic wave shielding property, workability, and shape following property were evaluated in the same manner as in Example 1, and the results are shown in FIG. 7.

[0025]

[Example 4] The heat conductive liquid silicone compound of Example 1 was laminated on the graphite film used in Example 1 to a thickness of 2 mm by the doctor blade method and heat-cured to obtain a high heat conductive electromagnetic wave shield sheet. Was produced. The thermal conductivity, electromagnetic wave shielding property, workability, and shape following property were evaluated in the same manner as in Example 1, and the results are shown in FIG. 7.

[0026]

Example 5 A graphite film having a thickness of 0.3 mm (Nikafilm FL400 manufactured by Nippon Carbon Co., Ltd.)
A high thermal conductive electromagnetic wave shield sheet was produced in the same manner as in Example 4 except that was used. The thermal conductivity, electromagnetic wave shielding property, workability, and shape following property were evaluated in the same manner as in Example 1, and the results are shown in FIG. 7.

[0027]

[Comparative Example 1] Similar to Example 1, an addition type heat conductive liquid silicone compound (Toshiba Silicone Co., Ltd. T containing aluminum oxide powder as a heat conductive filler)
SE3081) was developed into a sheet by the doctor blade method and heat-cured to prepare a heat conductive sheet having a thickness of 2 mm and an Asker C hardness of 27. The thermal conductivity, electromagnetic wave shielding property, workability, and shape following property were evaluated in the same manner as in Example 1, and the results are shown in FIG. 7.

[0028]

Comparative Example 2 Similar to Example 1, an addition type heat conductive liquid silicone compound (Toshiba Silicone Co., Ltd. T containing aluminum oxide powder as a heat conductive filler)
SE3081) was developed into a sheet by the doctor blade method and heat-cured to prepare a heat conductive sheet having a thickness of 2 mm and an Asker C hardness of 27. A 80 mesh mesh made of copper was laminated on one side of the layer, and a thermally conductive liquid silicone compound (Toshiba Silicone Co., Ltd.
SE3081) was laminated in a thickness of 2 mm and cured by heating to prepare a high thermal conductive electromagnetic wave shield sheet. The thermal conductivity, electromagnetic wave shielding property, workability, and shape following property were evaluated in the same manner as in Example 1, and the results are shown in FIG. 7.

According to FIG. 7, the high thermal conductive electromagnetic wave shield sheets of Examples 1 to 3 of the present invention and the high thermal conductive electromagnetic wave shield sheets obtained by the manufacturing method of the present invention of Examples 4 and 5 are high. It has thermal conductivity and electromagnetic wave shielding properties. In addition, the obtained high heat conductive electromagnetic wave shielding sheet is also excellent in workability in cutting and shape conformability in use. On the other hand, Comparative Example 1, which is a conventional heat conductive sheet, has good workability and shape conformability, but poor thermal conductivity and poor electromagnetic wave shielding properties. Comparative example 2
Has good electromagnetic wave shielding properties, but its thermal conductivity is
It can be seen that there are problems in workability and shape conformability during cutting.

The high thermal conductivity electromagnetic wave shielding sheet of the present invention has excellent thermal conductivity and electromagnetic wave shielding properties, and has good workability during cutting and punching, and good shape conformability during use.
The manufacturing method of the high thermal conductivity electromagnetic shield sheet of the present invention is an efficient production possible way. Therefore, since it is very useful as a sheet material that is required to have high heat dissipation and electromagnetic wave shielding properties that combine shape conformability that can be installed in a gap between a radiator and a high-density mounted electronic device having different heights , Of the present invention utilizing
High heat dissipation and electromagnetic wave shielding with a magnetic wave shield structure
Ru can achieve gender. It is also possible to provide a tube-shaped or cap-shaped molded article by applying the high thermal conductivity electromagnetic wave shield sheet of the present invention and the manufacturing method thereof.

[Brief description of drawings]

FIG. 1 is a sectional view of a high thermal conductivity electromagnetic wave shield sheet of the present invention.

FIG. 2 is a perspective view of a graphite film having a plurality of openings used in the present invention.

FIG. 3 is a cross-sectional view of the high thermal conductivity electromagnetic wave shield sheet of the present invention.

FIG. 4 is a cross-sectional view of the high thermal conductivity electromagnetic wave shield sheet of the present invention.

FIG. 5 is a cross-sectional view of the high thermal conductivity electromagnetic wave shield sheet of the present invention.

FIG. 6 is a cross-sectional view of an example in which the high thermal conductive electromagnetic wave shield sheet of the present invention is used in a gap between a heat generating element and a radiator .

FIG. 7 shows evaluation results of thermal conductivity, electromagnetic wave shielding property, workability, and shape following property.

Continuation of front page (56) Reference JP-A-2-82559 (JP, A) JP-A-2-39933 (JP, A) JP-A-6-291226 (JP, A) JP-A-3-199153 (JP , A) JP 62-261199 (JP, A) JP 54-33959 (JP, A) JP 7-266356 (JP, A) Actual flat 2-136386 (JP, U) Actual flat 4-40589 (JP, U) Japanese Patent Publication 3-51302 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) H05K 9/00 B32B 7/02 B32B 25/20 C01B 31 / 04 C08L 83/04

Claims (4)

(57) [Claims] 1.Actual mounting on the mounting element of the printed circuit board
For mounting deviceHigh thermal conductivityElectromagnetic wave shield sheet, Thermal conductive fillerContainsAsker C hardness after curing is 30
The following silicone rubber layer has a large number of openings
Graphite filmEmbedded in, and in the opening,
Forming the silicone rubber layerSilicone rubber penetrated
Cure with, The graphite film is
For mounting elements characterized by reinforcing the rubber layer
High thermal conductivity electromagnetic wave shield sheet. 2. The graphite film is 0.05-1.
The highly heat conductive electromagnetic wave shield sheet for a mounting element according to claim 1, which has a thickness of 2 mm. 3.The mounting element according to claim 1 or 2.
A method for manufacturing a high thermal conductivity electromagnetic wave shield sheet for a child.
I mean A number of silicone rubber layers containing a thermally conductive filler
Place a graphite film with openings, and
Laminating a silicone rubber layer containing a thermally conductive filler,
The silicone rubber forming the silicone rubber layer is
Curing while penetrating the opening of the filmMounting element
ForManufacturing method of high thermal conductivity electromagnetic wave shield sheet. 4. The mounting element according to claim 1 or 2.
A high-thermal-conductivity electromagnetic wave shielding sheet for a child covers the lower surface side of a plurality of elements mounted on a printed circuit board while subjecting it to deformation while following the height difference, and then disposing the upper surface side of the radiator. The heat radiation and electromagnetic wave shield structure of the mounting element that comes in contact with the mounting.