JP2003145681A - Gel-like soft sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gel-like soft sheet capable of being increased in stretching strength without damaging the original flexibility and adhesion, excellent in handleability at the time of actual mounting and capable of well suppressing radiation of heat or electromagnetic waves. SOLUTION: The gel-like soft sheet 1 is formed by gelling a silicone resin to mold the same into a sheet but a heat conductive powder and a soft magnetic powder are mixed with the sheet and at least one rubberized layer 10 having high hardness is formed. The rubberized layer 10 is set as one surface layer to be held between a radiation block 2 and other gel-like layer 11 brought into contact with CPU 3. Since the heat conductive powder and the soft magnetic powder are mixed, the formed sheet has radiation characteristics and electromagnetic wave absorbing characteristics to suppress radiation of heat and electromagnetic waves. The rubberized layer is densified by increasing crosslinking density to be increased in strength in a stretching direction and has proper stiffness to become easy to handle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gel-like soft sheet, and more specifically, it has heat dissipation properties and electromagnetic wave absorption properties by mixing a heat conductive powder and a soft magnetic powder. The present invention relates to improvement of the distraction strength of a gel soft sheet.

[0002]

BACKGROUND OF THE INVENTION Recently, a personal computer (P
C) etc., so-called IT (Information Te
development of electronic devices in a field called chnology),
Applications are thriving.

Since there is a strong demand for miniaturization of such electronic devices, there is a problem in that so-called internal noise such as heat generation and electromagnetic waves generated in circuit elements such as ICs increases. For example, in a notebook PC, especially CP
Heat generation and electromagnetic waves generated in U are problems, and measures for heat radiation and common mode radiation noise flowing from the CPU to the device housing via the heat radiation sheet are required.

Therefore, as a technique for coping with the heat radiation and the radiation noise, a flexible soft sheet material having heat radiation characteristics and electromagnetic wave absorption characteristics has been developed, and this soft sheet material is provided between the CPU and the heat radiation block. Take the configuration to be sandwiched between. As a soft sheet material for heat dissipation and electromagnetic wave suppression, for example, a silicone resin is mixed with a powder such as alumina and boron nitride for improving thermal conductivity and a magnetic powder for suppressing electromagnetic waves to form a gel. It is qualitatively formed into a sheet.

Since the surface of the soft sheet material becomes tacky due to gelation, it can adhere well to the object, but it must have appropriate flexibility in terms of heat conduction efficiency. In other words, heat conduction is impaired when there are many portions that do not come into contact with the CPU (object), and therefore flexibility that adheres to minute irregularities on the CPU surface is required.

However, the flexibility as a soft sheet material is an essential element, but there is a problem that it is too soft and stretches when the sheet material is mounted.
That is, since the gel is highly flexible and easily deformed, the problem of stretching becomes large when it is thin, and the thin sheet gel causes stretching due to its own weight when it is lifted, and the surface of When the protective film is peeled off and handled, it is unwieldy and causes misalignment.

Therefore, as a measure for improving the handling property,
A thin PET film is attached to the surface of a flexible sheet material to increase the elongation strength. But in this case, P
The ET film is not flexible and its adhesion to an object is deteriorated, and the number of attachment steps is increased, resulting in an increase in cost in materials and processing.

Further, since the PET film cannot be cut by an ordinary cutter device, a special cutter device is required for the cutting step of cutting the product sheet material out of the work sheet, which makes the cutting process difficult.

The present invention has been made in view of the above background, and an object of the present invention is to solve the above problems and to increase the elongation strength without impairing the original flexibility and adhesion. Another object of the present invention is to provide a gel soft sheet which is excellent in handleability at the time of mounting and can satisfactorily dissipate heat and / or suppress electromagnetic waves.

[0010]

In order to achieve the above object, the gel soft sheet according to the present invention is premised on a gel soft sheet obtained by gelling a silicone resin to form a sheet. Heat conductive powder, soft magnetic powder, or both powders were mixed in the sheet body, and at least one rubberized layer having high hardness was formed.

The rubberized layer may be at least one surface layer, or a double-sided adhesive sheet material having adhesive front and back may be attached to the rubberized layer. Further, the rubberized layer may be an inner layer that is not exposed.

Further, the heat conductive powder is alumina,
At least one kind or a mixture of plural kinds of oxides, nitrides, and carbides containing boron nitride, silicon carbide, etc. is used, and the soft magnetic powder is at least one of ferrite, carbonyl iron, and flat magnetic metal powder. The composition may be one kind or a mixture of plural kinds.

In the present invention, since the silicone resin is mixed with the heat conductive powder, the soft magnetic powder, or both powders, the formed sheet body has a heat radiation property and an electromagnetic wave absorption property depending on the mixed powder. It has heat dissipation and electromagnetic wave suppression.

Since at least one rubberized layer is formed, the rubberized layer has higher strength in the direction of extension than the gelled layer due to the increased crosslink density.
Therefore, as the gelled soft sheet having a multi-layered structure with the gelled layer, the elongation strength is increased and so-called stiffness is appropriately imparted, and thus the handling becomes easy.

* Definition of terms A "soft sheet" is a sheet having a softness such that it is elastically deformed when pressed against the surface of an object and the surface of the sheet is deformed into a shape conforming to the surface shape of the object. . However, the elastic deformation does not necessarily have a restoring force that returns to the original sheet shape when peeled from the object. For example, the rubber hardness of 50 or less is evaluated. Of course, this rubber hardness is a standard, and a rubber hardness of more than 50 is sufficient as long as it has the above-mentioned characteristics.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of the present invention. In this embodiment, the gel soft sheet 1
Is basically formed into a sheet by gelling a silicone-based resin. The sheet body is mixed with a heat conductive powder and a soft magnetic powder, and a rubberized layer 10 having a high hardness is formed. Is formed in at least one layer.

Here, the rubberized layer 10 is used as one surface layer. As shown in FIG. 2, the rubberized layer 10 side is brought into contact with the heat dissipation block 2 and the other gelled layer 11 side is brought into contact with the CPU 3. Insert it between the two in a posture. The heat dissipation block 2 is fixed to the lid plate 20, and the CPU 3 is attached to the printed board 30.

The thermally conductive powder has a composition in which at least one kind or a plurality of kinds of oxides, nitrides, carbides and the like containing alumina, boron nitride, silicon carbide and the like are mixed. As soft magnetic powder, ferrite, carbonyl iron,
The composition is such that at least one kind or a plurality of kinds of flat magnetic metal powder or the like is mixed.

The gel soft sheet 1 can be manufactured by a method of simultaneously forming layers having different crosslink densities by a doctor blade method or an extrusion molding method. That is, the silicone resin, which is the main material, has a chain structure in which chains are entwined with each other, and silicone oil is stored between the chains. Therefore, it exhibits excellent flexibility and stretchability against a mechanical load from the outside, and has good elasticity and stretchability. By changing the chain density (crosslink density), the property can be freely changed from liquid to solid (rubbery), and various forms can be taken.

Therefore, in the present invention, only one surface layer is formed with a high cross-linking density showing a rubbery property, and the other is formed with a low cross-linking density giving a gel-like property. As a result, the rubberized layer 10 and the gelled layer 11 have a two-layer structure.

As a method for increasing the crosslink density of the formed film layer, the silicone oil (low molecular weight component) in the formed film layer may be removed by drying at a high temperature of 200 ° C. or higher, for example. This is because the low-molecular-weight siloxane gas that forms an electrically insulating film is deposited on the outside, preventing contact failure of circuit parts that have electrical contacts, such as relays near the applied mounting site. It is effective to do. Further, this high temperature drying method may be used in combination with the formation of the film layer by the above-mentioned doctor blade method or extrusion molding method.

As described above, the gel soft sheet 1 has a multi-layer structure of the rubberized layer 10 and the gelled layer 11, but is essentially the same silicone resin and only the surface film layer is cured. Therefore, the rubberized layer 10 cannot be peeled off by a physical force such as a peeling force applied by hand.
Since the sheet has a higher density, the strength in the direction of extension increases, and the sheet has a so-called moderate elasticity, which makes it easy to handle.

Therefore, as shown in FIG. 2, the rubberized layer 10 side can be easily sandwiched between the heat radiation block 2 and the other gelled layer 11 side in contact with the CPU 3. There is no risk of misalignment when mounting. Then, a predetermined pressure is applied to the soft gel sheet 1 by pressing down the heat dissipation block 2 so that the adhesiveness is improved, which allows good heat dissipation,
You can surely suppress electromagnetic waves.

Further, since the rubberized layer 10 is a polymer layer having an increased crosslink density, the insulation resistance is increased and the insulation property is improved. The rubberized layer 10 is essentially the gelled layer 1
Since it is the same material as No. 1, it has good familiarity and can be processed as it is with a cutter device that cuts ordinary rubber materials and has good cutability. In order to demonstrate the effect of the present invention, a sample was manufactured and the characteristics such as rubber hardness were measured and compared with the conventional product.

* Production and Comparison of Sample First, the production conditions of the sample will be described. The sample has a sheet thickness of 0.5 mm, which is 30 x 3
Cut into 0 mm pieces. This is made by molding a slurry in which a soft magnetic powder and a thermally conductive powder are appropriately mixed with a silicone resin, one surface of which is formed into a thin rubberized layer 10, and the other is mostly a gelled layer. 11 formed.

Further, the conventional sample of the comparative example had the same shape and size and the same composition, but the rubberized layer 10 was not formed.

As a result, both the conventional sample and the sample of the present invention had an initial permeability of 6 [μiac] and a thermal conductivity of 3 [W /
m · K]. The volume resistance is 1 × 10 10 [Ω · m] for the conventional sample (gelling layer 11) and 1 × 10 13 [Ω · m] for the rubberized layer 10 of the present invention sample. The rubber hardness of the conventional sample (gelling layer 11) is 30
[ASKER C], which is a rubberized layer 1 of the sample of the present invention.
At 0, it was 40 [ASKERC].

That is, in the gel soft sheet 1 according to the present invention, the original softness of the soft sheet is that the gelling layer 11 due to the low cross-linking density shows its properties, and the gelling layer 11 has adhesive properties. It was confirmed that the other surface is rubberized layer 10 having a high cross-linking density, so that the higher density increases the strength in the stretching direction.

FIG. 3 shows a second embodiment of the present invention. In the second embodiment, the rubberized layer 10
Then, a double-sided adhesive sheet material 4 having adhesive front and back is attached. The gel soft sheet 1 itself is the first
The configuration is the same as that of the first embodiment, and the description of the respective components will be omitted.

Since the double-sided pressure-sensitive adhesive sheet material 4 generally has a structure in which a silicone-based pressure-sensitive adhesive is applied to the front and back surfaces, it is difficult to attach it to the gel-like surface due to the silicone oil. But here rubberized layer 1
0 is the bonding partner, and when the material becomes rubbery, the oil bleeding on the surface disappears, so that it can be bonded to the surface of the rubberized layer 10, and reliable fixation can be performed.

By the way, it is advantageous to make the sheet thickness as thin as possible when prioritizing the thermal conductivity in the mounting such that the sheet is sandwiched between the heat dissipation block 2 and the CPU 3, for example, the sheet thickness is 0.2 to 0.2. It may be thinned to about 0.3 mm. However, at this time, by pressing down the heat dissipation block 2 as in the first embodiment, the distribution of the pressing force varies, so that the proper load distribution is applied to the entire surface of the gel soft sheet 1 having a thin sheet thickness. Will be difficult to give. As a result, the adhered state of the gel soft sheet 1 may vary, and conversely the heat conduction may be deteriorated. Also, since the load distribution to the CPU varies,
It is not preferable in terms of mechanical stress, and it is essentially desired to avoid mechanical stress in a semiconductor IC.

Therefore, in the gel soft sheet 1 according to the second embodiment, the double-sided adhesive sheet material 4 is fixedly attached to the heat dissipation block 2, and the surface of the gelling layer 11 is brought into contact with the CPU 3. The heat radiation block 2 is configured so as not to be pressed down.

In this way, since the double-sided adhesive sheet material 4 is attached to the surface of the rubberized layer 10, the double-sided adhesive sheet material 4 causes the heat dissipation block 2 to cover the gel soft sheet 1.
The CPU 3 (semiconductor I
Mounting can be done without applying a load to C). Therefore, even if vibration or impact is applied to the mounting portion, the position is not displaced, and heat radiation and electromagnetic wave suppression can be stably performed.

FIG. 4 shows a third embodiment of the present invention. In the third embodiment, the rubberized layer 10
In the same manner as in the second embodiment, the double-sided adhesive sheet material 4 having adhesive front and back surfaces is attached, but the gel soft sheet 1 has a configuration in which the heat conductive powder is not mixed, and the It has no function.

That is, here, a soft magnetic powder is mixed with a silicone resin as a main material so as to have a function of suppressing an electromagnetic wave, and as shown in FIG. The flexible board 5 is connected to the printed board 30 by a connector 6.

Since the double-sided pressure-sensitive adhesive sheet material 4 is attached to the surface of the rubberized layer 10 in this manner, the double-sided pressure-sensitive adhesive sheet material 4 can be surely attached to the bent portion of the flexible substrate 5 or the like. Easy to implement. As a result, it is possible to reliably suppress electromagnetic waves and suppress interference of radiation noise.

FIG. 5 shows a fourth embodiment of the present invention. In the fourth embodiment, the front and back are formed into a gel layer with a low cross-linking density, and only the intermediate layer is formed into a thin film layer with a high cross-linking density showing a rubbery property. It has a three-layer structure of a gelling layer 11, a rubberizing layer 10, and a gelling layer 11. And the gel soft sheet 1
The same as that of the first embodiment described above,
The description of each of those components will be omitted.

As described above, since the rubberized layer 10 is provided as the intermediate layer, the strength in the extending direction is increased, the sheet has a proper amount of so-called stiffness, which makes it easy to handle and makes the front and back surfaces exhibit tackiness. be able to. Therefore, FIG.
As shown in FIG. 3, when mounted on the CPU 3, the gelling layer 11 can be adhered even on the heat dissipation block 2 side.
Good adhesiveness can be obtained on both sides of U3, whereby heat dissipation and electromagnetic wave suppression can be performed well. For the fourth embodiment, in order to demonstrate the effect of the present invention, a sample was manufactured and the characteristics such as rubber hardness were measured and compared with the conventional product.

* Manufacturing conditions of the sample and the comparative sample are the same as those of the first embodiment described above. Here, the sample is formed to have a sheet thickness of 0.5 mm. It was cut into small pieces of 30 mm. This is made by molding a slurry in which a soft magnetic powder and a heat conductive powder are appropriately mixed with a silicone resin, the front and back are formed into a gelling layer 11, and a space between them is formed into a thin rubberized layer 10. . Further, the conventional sample of the comparative example had the same shape and size and the same composition, but was manufactured without the rubberized layer 10.

As a result, both the conventional sample and the sample of the present invention had an initial magnetic permeability of 6 [μiac] and a thermal conductivity of 3 [W /
m · K]. The volume resistance is 1 × 10 10 [Ω · m] for the conventional sample (gelling layer 11) and 1 × 10 13 [Ω · m] for the rubberized layer 10 of the present invention sample. The rubber hardness of the conventional sample (gelling layer 11) is 30
[ASKER C], which is a rubberized layer 1 of the sample of the present invention.
At 0, it was 50 [ASKERC].

That is, in the gel soft sheet 1 according to the present invention, it was confirmed that the rubberized layer 10 serving as the intermediate layer increases the strength in the extending direction.

In each of the above embodiments, the soft magnetic powder and the heat conductive powder are used together as the powder to be mixed, but it is of course possible to mix either one.

[0043]

As described above, in the gel soft sheet according to the present invention, since the thermally conductive powder, the soft magnetic powder, or both powders are mixed with the silicone resin, the formed sheet body is It has heat dissipation properties and electromagnetic wave absorption properties, and can perform heat dissipation and electromagnetic wave suppression.

Since at least one rubberized layer is formed, the rubberized layer has a higher strength in the extending direction than the gelled layer due to the increased crosslink density.
Therefore, as the gelled soft sheet having a multi-layered structure with the gelled layer, the elongation strength is increased, so-called stiffness is moderately added, and the handling becomes easy. That is, the elongation strength can be increased without impairing the original flexibility and adhesiveness, and heat dissipation and electromagnetic wave suppression can be satisfactorily performed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a gel soft sheet showing a first embodiment.

FIG. 2 is a side view illustrating mounting of a gel soft sheet.

FIG. 3 is a side view illustrating mounting of the gel soft sheet according to the second embodiment.

FIG. 4 is a side view illustrating mounting of a gel soft sheet according to a third embodiment.

FIG. 5 is a cross-sectional view of a gel soft sheet showing a fourth embodiment.

FIG. 6 is a side view illustrating mounting of a gel soft sheet.

[Explanation of symbols]

1 Gel soft sheet 2 heat dissipation block 3 CPU 4 Double-sided adhesive sheet material 5 Flexible substrate 6 connector 10 Rubberized layer 11 Gelling layer 20 lid plate 30 printed circuit boards

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshio Matsuo             F-de, 5-36-1 Shimbashi, Minato-ku, Tokyo             K.K Co., Ltd. F-term (reference) 4F100 AA14B AA16B AA19B AA23B                       AB01B AK52A AN00B BA02                       BA03 BA07 BA10A BA10C                       DE01B DE02B GB41 JD08                       JG06B JJ01B JK12B JL13C                       JM10A                 5E321 BB25 BB32 BB51 BB53 BB55                       GG11 GH03                 5E322 FA05

Claims (8)

[Claims] 1. A gel soft sheet which is formed into a sheet by gelling a silicone resin, wherein a thermally conductive powder is mixed with the sheet body and a rubberized layer having a high hardness is formed. At least one layer is formed, and a gel-like soft sheet characterized by the above-mentioned. 2. A gel soft sheet formed by gelling a silicone-based resin into a sheet, wherein soft magnetic powder is mixed with the sheet, and at least a rubberized layer having high hardness is formed. A gel soft sheet, which is formed by one layer. 3. A gel soft sheet, which is formed into a sheet by gelling a silicone resin, wherein the sheet body is mixed with a heat conductive powder and a soft magnetic powder and has a high hardness. A gel-like soft sheet comprising at least one rubberized layer. 4. The gel soft sheet according to claim 1, wherein the rubberized layer is at least one surface layer. 5. The gel soft sheet according to claim 4, wherein a double-sided adhesive sheet material having adhesive front and back surfaces is attached to the rubberized layer. 6. The gel soft sheet according to claim 1, wherein the rubberized layer is an inner layer which is not exposed. 7. The thermally conductive powder has a composition in which at least one kind or a mixture of plural kinds of oxides, nitrides and carbides containing alumina, boron nitride, silicon carbide and the like is mixed. The gel soft sheet according to 1 or 3. 8. The soft magnetic powder according to claim 2, wherein the soft magnetic powder has a composition in which at least one kind or a plurality of kinds of ferrite, carbonyl iron and flat magnetic metal powder are mixed. Gel soft sheet.