Abstract:
Adhesives with a specific viscose component to provide good thermal conductivity, insulation and flame retardant and high temperature resistant is provided. The adhesive composition form may be single-sided or double-sided with a substrate or not. The substrate may be metal foil, glass fiber, thermal pad or organic polymers. Adhesive composition includes polymerized siloxane, metal hydroxides, and metal oxides. Nitrides, aluminum powder or coupling agent may be added. The coupling agent is specially used in non-silica resin substrate, which enhances the adhesion to substrate surface. Optionally, the adhesive may include a release film.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 61/588,661, filed Jan. 20, 2012. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention generally relates to a novel composition, which is thermal conductive, electric insulating, high temperature resistant and flame retardant as well as an adhesive containing this composition. In particular, the present invention is directed to a composition which is rated to UL 94V-0 standard specification, as well as an adhesive containing this composition. Both the composition and the adhesive are thermal conductive, electric insulating, high temperature resistant and flame retardant at the same time, and suitable to serve as a single-sided or double-sided adhesive. 
         [0004]    2. Description of the Prior Art 
         [0005]    The general purpose of an adhesive composition is to make two objects firmly adhere to together, so it is widely used. In some circumstances, the adhesive composition needs more practical usages. For example, a special adhesive composition is used in the computer motherboards. On one hand, the adhesive composition is needed to make the heating source and the heat-dissipating device firmly adhered together by the adhesive composition. On the other hand, the adhesive composition is also needed to conduct the heat coming from the heat source to the heat-dissipating device. 
         [0006]    There are already double-sided adhesives, which are commercially available and known as thermal conductive adhesives, to conduct the heat coming from the heat source to the heat-dissipating device. These thermal conductive and double-sided adhesives are generally a substrate coated with acrylic-based adhesive to adhere the heat source to the heat-dissipating device. However, since the main ingredients of the adhesive are acrylic-based organic compounds, these thermally conductive double-sided adhesives have drawbacks. For example, it is neither high temperature resistant (not over 100° C. in general) nor flame retardant. Also, the thermal conductive property is not good. 
         [0007]    In addition, although there are also commercially available double-sided and thermal conductive adhesives with silicone-coated substrates, and they are temperature resistant (not over 180° C. in general), but these silicone-based adhesives are not flame retardant. Also, although there are also some commercially available thermal conductive adhesives of very small thickness, this material is obviously not strong enough due to its insufficient thickness. 
         [0008]    Accordingly, it is still needed to provide a novel composition and an adhesive which are thermal conductive, electric insulating, high temperature resistant and flame retardant. In particular, they are rated to the international standard of UL 94V-0, in order to meet the strict and stringent industrial demands. 
       SUMMARY OF THE INVENTION 
       [0009]    In view of the above, the present invention proposes a thermal conductive, electric insulating, high temperature resistant and flame retardant composition as well as an adhesive containing the composition. The features of the composition and the adhesive of the present invention resides in that they are not only highly thermal conductive and electric insulating, but they are also rated to the specification of UL 94V-0 standard, which is fully able to meet the strict and stringent industrial demands. Optionally, the composition and the adhesive of the present invention may have an extremely small thickness or include a release film, to be a single-sided or double-sided product. 
         [0010]    In a first aspect, the present invention proposes an adhesive which is thermal conductive, electric insulating, high temperature resistant and flame retardant. The thermal conductive, electric insulating, high temperature resistant and flame retardant adhesive of the present invention includes a substrate and an adhesive composition. The substrate may be a metal foil, glass fiber, an organic polymer, or a thermal conductive silicone sheet. In a second aspect, the present invention also proposes an adhesive composition which is thermal conductive, electric insulating, high temperature resistant and flame retardant. The adhesive composition includes a siloxane resin, a metal hydroxide and a metal oxide, or optionally needed nitride or aluminum powder, as well as a coupling agent serving as an adhesion enhancer when a silicon-free substrate is utilized. 
         [0011]    The siloxane resin is 10% to 90% (weight percent, wt.) of the total adhesive composition. The metal hydroxide is 0.01% to 75% (wt.) of the total adhesive composition and releases water and the corresponding metal oxide when heated. The metal hydroxide may be at least one of aluminum hydroxide and magnesium hydroxide. The metal oxide is 0.01% to 80% (wt.) of the total adhesive composition and may be at least one of alumina, zinc oxide and magnesium oxide in the form of sheet-like (flakes), irregular or spherical shape. 
         [0012]    The optional nitride may be 0.01% to 30% (wt.) of the total adhesive composition and may be a metal nitride or a non-metal nitride, such as at least one of aluminum nitride and boron nitride. The optional aluminum powder may be 0.01% to 3% (wt.) of the total adhesive composition. 
         [0013]    The optional coupling agent may be a silane alone or mixed with a solvent. The optional coupling agent may be 0.01% to 5% (wt.) of the total adhesive composition and may be used alone or mixed with a solvent. In the siloxane resin, a cross-linking reaction of the siloxane resin is used to improve adhesion to enhance the adhesion between the siloxane resin and the silicon-free substrates. 
         [0014]    In one embodiment of the present invention, the thermal conductive, electric insulating, high temperature resistant and flame retardant adhesive may further include at least one release film to cover at least one side of the adhesion composition. Preferably, when the thermal conductive, electric insulating, high temperature resistant and flame retardant adhesive is in the form of a double-sided adhesive, the release films respectively cover a first adhesion composition and a second adhesive composition of the adhesive. 
         [0015]    In another embodiment of the present invention, the thermal conductive, electric insulating, high temperature resistant and flame retardant adhesive may be a single-sided adhesive product. The release film covers either one side of the adhesion composition. 
         [0016]    In another embodiment of the present invention, the thermal conductive, electric insulating, high temperature resistant and flame retardant adhesive may further include a first adhesion composition and a second adhesive composition. The first adhesion composition covers a first side and the second adhesive composition covers a second side, so that the substrate is sandwiched between the first adhesive composition and the second adhesive composition. 
         [0017]    In another embodiment of the present invention, the thermal conductive, electric insulating, high temperature resistant and flame retardant adhesive may be a single-sided adhesive product. The release film covers either one side of the adhesion composition so that the adhesion composition is sandwiched between the substrate and the release film. 
         [0018]    In another embodiment of the present invention, the thermal conductive, electric insulating, high temperature resistant and flame retardant adhesive composition may be applied on the surface of a substrate or used alone without a substrate. 
         [0019]    In another embodiment of the present invention, the thermal conductive, electric insulating, high temperature resistant and flame retardant adhesive composition has a thickness of from 0.5 mm to 20 mm. 
         [0020]    In another embodiment of the present invention, the thermal conductive, electric insulating, high temperature resistant and flame retardant adhesive composition has a thermal resistance not greater than 5° C./watt. 
         [0021]    In another embodiment of the present invention, the thermal conductive, electric insulating, high temperature resistant and flame retardant adhesive composition has a volume resistivity which is greater than 10 8  (ohm-cm). 
         [0022]    In another embodiment of the present invention, the thermal conductive, electric insulating, high temperature resistant and flame retardant adhesive composition is rated to the standard of the specification of UL 94V-0. 
         [0023]    In another embodiment of the present invention, the substrate may have a thickness from 0.02 mm to 20 mm. 
         [0024]    These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  illustrates the method to form a single-sided product of the adhesive composition of the present invention to go with a substrate. 
           [0026]      FIG. 2  illustrates a single-sided product of extremely small thickness formed by the adhesive of the present invention. 
           [0027]      FIG. 3  illustrates the adhesive of the present invention forms a single-sided adhesive product. 
           [0028]      FIG. 4  illustrates the adhesives of the present invention form a double-sided adhesive of very small thickness without a substrate. 
           [0029]      FIG. 5  illustrates the adhesive of the present invention forms a double-sided product with a substrate. 
           [0030]      FIG. 6  illustrates the adhesive of the present invention forms a double-sided product with a substrate. 
           [0031]      FIG. 7  illustrates the adhesive of the present invention forms a double-sided product with a substrate. 
           [0032]      FIG. 8  illustrates the adhesive of the present invention forms a single-sided adhesive product which is compressible. 
           [0033]      FIG. 9  illustrates the adhesives of the present invention forms a double-sided adhesive with a substrate. 
       
    
    
     DETAILED DESCRIPTION 
       [0034]    The present invention provides a thermal conductive, electric insulating, high temperature resistant and flame retardant composition and an adhesive containing the composition. The adhesive of the present invention contains at least a silicon oxide resin, a metal hydroxide and a metal oxide, and optional nitride or aluminum powder. In addition, a coupling agent based on silane is optionally employed when a silicon-free substrate is used. 
         [0035]    The siloxane resin is used as the carrier for the high temperature resistant property, and the metal hydroxide as well as the metal oxide may be used to enhance the flame retardant property. At least one of the nitride and aluminum powder may be used to enhance the thermal conductive property. The coupling agent such as silane may be used alone or mixed with a solvent to form the chemical bonding with the silicon-free substrates to enhance the bonding strength. When the metal oxide is present in a higher ratio, it is possibly more thermal conductive and flame retardant. Preferably, the composition in the adhesive of the present invention may be not fully cured to be sufficiently sticky. 
         [0036]    The siloxane resin may be 10% to 90% (wt.) of the overall adhesive composition, preferably from 20% to 50% by weight. These siloxane resins are materials which are able to withstand a temperature above 150° C. without substantially cracking at a temperature around 150° C., and its hardness does not substantially change with a change of the temperature. The term “substantially” used in the present invention is considered as the overall hardness change of the siloxane resin less than 10 degrees as the temperature changes, which meets the international standard of UL157 of O-ring and sealing gasket. In other words, the functions of the adhesive composition are not deteriorated accordingly. Supposing the change of the hardness of the thermoplastic material is within ±10 degrees, the function of the material is not compromised. The siloxane resin may be the products from USA Momentive (GE), USA Dow Corning or Japan Shin Etsu. For example, the Momentive series, which is used in pressure sensitive adhesives (PSA series), may be the siloxane resin for use in the present invention. 
         [0037]    The metal hydroxide may be 0.01% to 75% (wt.) of the overall adhesive composition, preferably from 20% to 50% by weight. The metal hydroxide generates water and a corresponding metal oxide when heated. The metal hydroxide may be, for example, at least one of zinc hydroxide, aluminum hydroxide and magnesium hydroxide. The metal hydroxide helps to improve the flame retardant property of the overall adhesive composition. 
         [0038]    The metal oxide may be 0.01% to 80% (wt.) of the overall adhesive composition, preferably from 20% to 50% by weight. The metal oxide may be a main group metal oxide or a transition metal oxide, such as at least one of alumina (aluminum oxide), zinc oxide and magnesium oxide. The metal oxide helps to improve the thermal conductive, flame retardant and electric insulating properties of the overall adhesive composition. 
         [0039]    The optional nitride may be 0.01% to 30% (wt.) of the total adhesive composition, preferably from 10% to 20% by weight. The nitride may be a metal nitride, or a non-metal nitride, which helps to improve the thermal conductive property of the overall adhesive composition. For example, aluminum nitride or boron nitride may be added to the siloxane resin to make it more thermal conductive. The aluminum nitride has a thermal conductivity of 70-210 W/mK in the form of poly crystalline, and the single crystal boron nitride has a thermal conductivity about 100 W/mK. 
         [0040]    The aluminum powder may be 0.01% to 3% (wt.) of the total adhesion composition, preferably from 0.5% to 1% by weight. The aluminum powder of high purity, high sphericity and less oxidized status may has an average particle size between 1 micrometer to 50 micrometer. The aluminum powder may have a heat transfer coefficient about 230 W/mK and helps to improve the thermal conductive property of the overall adhesion composition. 
         [0041]    The optional coupling agent may be 0.01% to 5% (wt.) of the total adhesion composition, preferably from 1% to 3% by weight. The coupling agent mainly functions to enhance the interaction between the siloxane resin and a non-silicone substrate. The coupling agent may be a silane used alone such as from USA Momentive (GE), USA Dow Corning, Japan Shin Etsu or Germany Degussa AG, or a blended silane coupling agent with a solvent. The solvent may be toluene, xylene, isopropanol, butanone or ISOPAR®. The silane-based coupling agent may combine the two through the organic functional groups in the silane and a hydrolysis reaction of the non-silicone substrate. The cross-linking reaction helps to enhance the interaction between the siloxane resin and a non-silicone substrate. 
         [0042]    After appropriately formulated, the adhesive composition of the present invention is thermal conductive, electric insulating, high temperature resistant and flame retardant at the same time. The formulation may be done by a closed mixer or an open mixer. The thermal resistance of the adhesive composition may be less than 5° C./w, and the thermal conductivity may be well adjusted in accordance with the addition of different ingredients. The volume resistivity of the adhesive composition is at least greater than 10 8 (ohm-cm), usually greater than 10 11  (ohm-cm), preferably greater than 10 14  (ohm-cm). The adhesive composition of the present invention is rated to an international standard, such as the specification of UL 94V-0. 
         [0043]    UL 94 V-0 is the international standard of flammability of plastic materials for parts in device and appliances. It rates the plastic and rubber flammability by judging the after flame time, burning rate and the falling flaming particles or drops. The details of UL 94V-0 are available to the public. Please refer to the specification of UL 94V-0. 
         [0044]    Optionally, the adhesive composition as well as the adhesive of the present invention may have an extremely small thickness. For example, the thickness of the adhesion composition may be between 0.05 mm to 20 mm, typically between 0.5 mm to 0.05 mm, preferably between 0.2 mm to 0.05 mm. Therefore, the adhesive composition of the present invention may form a single-sided or a double-sided product of extremely small thickness. 
         [0045]      FIG. 1  illustrates the method to form a single-sided product of the adhesive composition of the present invention to go with a substrate, such as Kapton®. First, a layer of silane coupling agent is applied on one side of a Kapton® substrate and dried at room temperature. After that, a layer of adhesive composition of the present invention which has been pre-formulated is uniformly applied on the silane coupling agent. The adhesive composition of the present invention may have, for example 50% siloxane resin, 30% alumina, 18% of aluminum nitride and 2% silicon silane coupling agent. Next, it is placed in an oven at 130° C. for 20 minutes to undergo a cross-linking reaction. Afterwards, it is taken out and a release film is applied on. 
         [0046]    In one embodiment of the present invention, the adhesive of the present invention may form a single-sided product of extremely small thickness.  FIG. 2  illustrates a single-sided product of extremely small thickness formed by the adhesive of the present invention. The adhesive  9  of the present invention includes a substrate  11 , an adhesive composition  12  and a release film  13 . The element  10  is a silane-containing coupling agent. The substrate  11  may be a metal foil of excellent thermal conductive property, such as aluminum foil. Please refer to the above for the details of the adhesive composition  12 . The total thickness of the substrate  11  and the adhesive composition  12  can be as small as about 0.05 mm. The coupling agent  10  helps to strengthen the adhesion between the adhesive composition  12  and the non-silicone substrate  11 . 
         [0047]    The adhesive composition  12  covers one side of the substrate  11 , and the release film  13  covers the other side of the adhesion composition  12 , so that the adhesion composition  12  is sandwiched between the substrate  11  and the release film  13 . Tear the release film  13  off to adhere the adhesive composition  12  to a target object (not shown).  FIG. 2  illustrates the adhesives  9  of the present invention, which has the substrate  11  of excellent thermal conductivity property, particularly suitable for a heat source of continuous high temperature and for use in high thermal conductive purposes, such as the motherboards of computers, central processor units or power supplies to bind the heat source and the heat sink. 
         [0048]    In another embodiment of the present invention, the adhesive of the present invention may form another single-sided adhesive product.  FIG. 3  illustrates the adhesive of the present invention forms a single-sided adhesive product. The adhesive  19  of the present invention includes a substrate  20 , an adhesive composition  22  and a release film  23 . The element  21  is a silane-containing coupling agent. The substrate  20  may be an organic polymer, preferably a thermal stable, high electric resistant and robust organic polymer, for example Kapton®, which is basically a polyimide (PI) insulating film or tape, a trademark of DuPont Inc. Kapton® is highly flexible, puncture-proof, and has good electrical properties. Alternatively, other commercially available polyimide materials will do, too. If the substrate is required to withstand a temperature no more than 80° C. to 150° C., commercially available polyethylene terephthalate (PET) or polycarbonate (PC) material may be considered as the substrate. Please refer to the above for the details of the adhesive composition  22 . The coupling agent  21  helps to strengthen the adhesion between the adhesive composition  22  and the non-silicone substrate  20 . 
         [0049]    The adhesive composition  22  covers one side of the substrate  20 , while the release film  23  coves the other side of the adhesive composition  22 , so that the adhesive composition  22  is sandwiched between the substrate  20  and the release film  23 . Tear the release film  23  off to adhere the adhesive composition  22  to a target object (not shown).  FIG. 3  illustrates the adhesives  19  of the present invention, which has the substrate  21  of high tensile strength, high tearing strength and withstand voltage property, is particularly suitable for the high voltage and high temperature purposes. 
         [0050]    In another embodiment of the present invention, the adhesive of the present invention may form a single-sided adhesive product of a minimum thickness.  FIG. 4  illustrates the adhesives of the present invention form a double-sided adhesive of very small thickness without substrate. The adhesive  30  of the present invention may contain nothing but an adhesion composition  32  and completely go without a substrate. The presence of the release film  33  is optional. Please refer to the above for the details of the adhesion composition  32 . 
         [0051]    The release films  33  cover both sides of the adhesive composition  32  so that the adhesive composition  32  is sandwiched between the release films  33 . Tear the release film  33  off to adhere the adhesive composition  32  to a target object (not shown).  FIG. 4  illustrates the adhesive  30  of the present invention to completely omit the thickness of a substrate, and particularly suitable for use in limited space. 
         [0052]    In another embodiment of the present invention, the adhesive of the present invention may also form a double-sided product with a substrate.  FIG. 5  illustrates the adhesive of the present invention forms a double-sided product with a substrate. The adhesive  39  of the present invention includes a substrate  40 , a first adhesive composition  42 , a second adhesive composition  44  and a release film  43 . The element member  41  is a silane-containing coupling agent. The substrate  40  may be a metal foil of excellent thermal conductive property, such as aluminum foil. Please refer to the above for the details of the first adhesive composition  42  and the second adhesive composition  44 . The coupling agent  41  helps to strengthen the adhesion between the first adhesive composition  42  as well as the second adhesive composition  44  and the non-silicone substrate  40 . 
         [0053]    The first adhesive composition  42  and the second adhesive composition  44  respectively cover the first side  40   a  and the second side  40   b  of the substrate  40 , so that the substrate  40  is sandwiched between the first adhesive composition  42  and the second adhesive composition  44 . The release films  43  cover both the first adhesive composition  42  and the second adhesive composition  44  at the same time so that the substrate  40 , the first adhesive composition  42  and the second adhesive composition  44  are also sandwiched between the release films  43 . Tear the release film  43  off to respectively adhere the first adhesive composition  42  and the second adhesive composition  44  to a target object (not shown).  FIG. 5  illustrates the adhesive  39  of the present invention, which has the substrate  40  of excellent thermal conductivity property, particularly suitable for a heat source of continuous high temperature and for use in high thermal conductive purposes, such as the motherboards of computers, central processor units or power supplies to bind the heat source and the heat sink. 
         [0054]    In another embodiment of the present invention, the adhesive of the present invention may also form a double-sided adhesive product with a substrate.  FIG. 6  illustrates the adhesive of the present invention forms a double-sided product with a substrate. The adhesive  49  of the present invention includes a substrate  50 , a first adhesive composition  52 , a second adhesive composition  54  and a release film  53 . The element  51  is a silane-containing coupling agent. The substrate  50  may be an organic polymer, preferably a thermal stable, high electric resistant and robust organic polymer, for example Kapton®, which is basically a polyimide (PI) insulating film or tape, a trademark of DuPont Inc. Kapton® is highly flexible, puncture-proof, and has good electrical properties. Alternatively, other commercially available polyimide materials will do, too. If the substrate is required to withstand a temperature no more than 80° C. to 150° C., commercially available polyethylene terephthalate (PET) or polycarbonate (PC) material may be considered as the substrate. Please refer to the above for the details of the first adhesive composition  52  and the second adhesive composition  54 . The coupling agent  51  helps to strengthen the adhesion between the first adhesive composition  52  as well as the second adhesive composition  54  and the non-silicone substrate  50 . 
         [0055]    The first adhesive composition  52  and the second adhesive composition  54  respectively cover the first side  50   a  and the second side  50   b  of the substrate  50 , so that the substrate  50  is sandwiched between the first adhesive composition  52  and the second adhesive composition  54 . The release films  53  cover both the first adhesive composition  52  and the second adhesive composition  54  at the same time so that the substrate  50 , the first adhesive composition  52  and the second adhesive composition  54  are also sandwiched between the release films  53 . Tear the release film  53  off to respectively adhere the first adhesive composition  52  and the second adhesive composition  54  to a target object (not shown).  FIG. 6  illustrates the adhesive  49  of the present invention, which has the substrate  50  of high tensile strength, high tearing strength and withstand voltage property, is particularly suitable for the high voltage and high temperature purposes. 
         [0056]    In another embodiment of the present invention, the adhesive of the present invention may also form a double-sided adhesive product with a substrate.  FIG. 7  illustrates the adhesive of the present invention forms a double-sided product with a substrate. The adhesive  59  of the present invention includes a substrate  60 , a first adhesive composition  62 , a second adhesive composition  64  and a release film  63 . The element  61  is a silane-containing coupling agent. The substrate  60  may be an inorganic material, preferably glass fiber. Glass fiber is dimensionally stable under high temperature, electrical resistant, flame retardant, and robust. Please refer to the above for the details of the first adhesive composition  62  and the second adhesive composition  64 . The coupling agent  61  helps to strengthen the adhesion between the first adhesive composition  62  as well as the second adhesive composition  64  and the non-silicone substrate  60 . 
         [0057]    The first adhesive composition  62  and the second adhesive composition  64  respectively cover the first side  60   a  and the second side  60   b  of the substrate  60 , so that the substrate  60  is sandwiched between the first adhesive composition  62  and the second adhesive composition  64 . The release films  63  cover both the first adhesive composition  62  and the second adhesive composition  64  at the same time so that the substrate  60 , the first adhesive composition  62  and the second adhesive composition  64  are also sandwiched between the release films  63 . Tear the release film  63  off to respectively adhere the first adhesive composition  62  and the second adhesive composition  64  to a target object (not shown).  FIG. 7  illustrates the adhesive  59  of the present invention is particularly for use as strips because the substrate  60  is dimensionally stable under high temperature, electrical resistant, flame retardant, and robust. 
         [0058]    In another embodiment of the present invention, the adhesive of the present invention may form a compressible single-sided adhesive.  FIG. 8  illustrates the adhesive of the present invention forms a single-sided adhesive product. The adhesive  70  of the present invention includes a substrate  71 , an adhesive composition  72  and a release film  73 . The substrate  71  may be a thermal conductive, flame retardant and electric insulating silicone sheet of different hardness. The main component of this thermally conductive silicone sheet may be a siloxane resin, and other additives, such as ceramic powder, are added to be thermal conductive. In this way, the thermal conductive silicone sheet is flexible and, not sticking foreign particles, and closely in contact with the heat source to improve the thermal conductive effect. The substrate  71  may have a thickness between 0.5 mm to 20 mm. Please refer to the above for the details of the adhesive compositions  72 . 
         [0059]    The adhesive composition  72  covers one side of the substrate  71 , and the release film  73  covers the other side of the adhesive composition  72 , so that the adhesive composition  72  is sandwiched between the substrate  71  and the release film  73 . Tear the release film  73  off to adhere the adhesive composition  72  to a target object (not shown).  FIG. 8  illustrate the compressible, flexible, temperature resistant and electric insulating adhesive  70  of the present invention to be particularly suitable in contact with a heating source whose surface may not be even, such as IC chips. 
         [0060]    In another embodiment of the present invention, the adhesive of the present invention may form a double-sided adhesive with a substrate.  FIG. 9  illustrates the adhesives of the present invention forms a double-sided adhesive with a substrate. The adhesive  74  of the present invention includes a substrate  75 , a first adhesive composition  76 , a second adhesive substance  77  and a release film  78 . The substrate  75  may be a thermal conductive, flame retardant and electric insulating silicone sheet of different hardness. The main component of this thermally conductive silicone sheet may be a siloxane resin, and other additives, such as ceramic powder, are added to be thermal conductive. In this way, the thermal conductive silicone sheet is flexible and, not sticking foreign particles, and closely in contact with the heat source to improve the thermal conductive effect. 
         [0061]    The compressible, flexible, temperature resistant and electric insulating adhesive  74  of the present invention is particularly for use in assembling electronic products or in a heating source whose surface may not be even. Please refer to the above for the details of the adhesive compositions  72 . Tear the release film  73  off to adhere the adhesive composition  72  to a target object (not shown). Due to its superior adhesion, the target object would not come off or dislocate during transportation or being fetched after the adhesive composition adheres to a target object. 
         [0062]    Table 1 summarizes the properties of the single-sided or double-sided adhesives of the present invention formed by the adhesion composition of the present invention with various substrates, in particular low thermal resistance, high temperature resistance, high flame resistance and high voltage resistance. The adhesion composition of the present invention is thermal conductive, electric insulating, high temperature resistant and flame retardant. 
         [0000]    
       
         
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                   
                   
                   
                   
                 Test 
               
               
                   
                 EXAMPLE 1 
                 EXAMPLE 2 
                 EXAMPLE 3 
                 EXAMPLE 4 
                 EXAMPLE 5 
                 mode 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 substrate 
                 Fiber 
                 Aluminum 
                 — 
                 Kapton ® 
                 siloxane 
                   
               
               
                   
                 glass 
                 foil 
                   
                   
                 resin 
               
               
                 thickness 
                 0.1 +/− 0.05 
                 0.05~0.25 
                 0.05~20 
                 0.02~0.15 
                  0.1~20 
                 Thickness 
               
               
                 (mm) 
                   
                   
                   
                   
                   
                 meter 
               
               
                 form 
                 single/ 
                 single/ 
                 single/ 
                 single/ 
                 single/ 
               
               
                   
                 double-sided 
                 double-sided 
                 double- 
                 double-sided 
                 double- 
               
               
                   
                   
                   
                 sided 
                   
                 sided 
               
               
                 Holding 
                 above 250 
                 above 250 
                 above 1 
                 above 250 
                 above 1 
                 ASTM D 
               
               
                 strength 
                   
                   
                   
                   
                   
                 1000 
               
               
                 gf/in 2   
               
               
                 Thermal 
                 below 5 
                 below 0.6 
                 below 5 
                 below 3.5 
                 below 5 
                 ASTM D 
               
               
                 resistance 
                   
                   
                   
                   
                   
                 5470 
               
               
                 (° C. 
               
               
                 in/watt) 
               
               
                 volume 
                 above 108 
                   
                 above 
                 above 108 
                 above 
                 ASTM D 
               
               
                 resistivity 
                   
                   
                 108 
                   
                 108 
                 257 
               
               
                 (ohm- 
               
               
                 cm) 
               
               
                 Breakdown 
                 above 2.0 
                   
                 0.5 
                 above 5 
                 0.5 
                 ASTM D 
               
               
                 Voltage 
                   
                   
                   
                   
                   
                 149 
               
               
                 (kV) 
               
               
                 Tensile 
                 above 150 
                 above 
                   
                 above 250 
                   
                 ASTM D 
               
               
                 Strength 
                   
                 12 
                   
                   
                   
                 412 
               
               
                 (Kgf/cm 2 ) 
               
               
                 (Elongation) 
                 above 2 
                 above 5 
                   
                 above 20 
                   
                 ASTM D 
               
               
                 (%) 
                   
                   
                   
                   
                   
                 412 
               
               
                 Operating 
                 −40~180 
                  −40~180 
                  −40~180 
                  −40~180 
                 −40~180 
               
               
                 temperature 
               
               
                 (° C.) 
               
               
                 UL 
                 94V-0 
                 94V-0 
                 94V-0 
                 94V-0 
                 94V-0 
                 UL No. 
               
               
                 flammability 
                   
                   
                   
                   
                   
                 E153203 
               
               
                 RoHS 
                 pass 
                 pass 
                 pass 
                 pass 
                 pass 
                 SGS 
               
               
                   
                   
                   
                   
                   
                   
                 ICP 
               
               
                 Halogen 
                 pass 
                 pass 
                 pass 
                 pass 
                 pass 
                 SGS 
               
               
                 content 
               
               
                   
               
             
          
         
       
     
         [0063]    In brief, the adhesive of the present invention has the following advantages: 
         [0000]    1. Comply with the international standards of UL 94 V-0.
 
2. Re-workable, re-stickable even after a long period of use.
 
3. High thermal conductivity (thermal resistance of less than 5° C./Watt) and long-term resistance to high temperature (−40° C. to 150° C.)
 
4. Insoluble in water, non-hydrolysis, resistant to UV light, sweat, cosmetics and etc.
 
5. Both single or double-sided products possible, high temperature resistant and flame retardant when in use.
 
         [0064]    Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.