Patent Publication Number: US-2011054104-A1

Title: Composite for heat-dissipating film

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention generally relates to a composite for coating and sputtering on an object for enhanced heat-dissipating performance so that there is no need to rely on heat-sinking fins of large surface area, the production cost is reduced, recycling is easier, and the highly contaminating anodizing treatment could be avoided without sacrificing the robustness against erosion and harsh weather. 
     DESCRIPTION OF THE PRIOR ART 
     Computer processors, high-brightness light emitting diode (LED) circuit boards, and those having heat producing elements all require superior heat dissipation to maintain their normal operation. Conventionally, heat-sinking fins are installed on these heat producing elements to help heat dissipation. The heat-sinking fins and the heat producing elements are jointly referred to as “objects to be heat-dissipated.” Some may even have fans for additional ventilation. However, heat-sinking fins, as no power consumption is involved, are still the most popular means. 
     As the heat producing elements are getting more powerful, more heat is produced and the heat-sinking fins have to be bigger for increased surface area, making the product larger and heavier and contradicting the downsizing trend of electronic products. 
     Additionally, as some of the heat producing elements are for outdoor usage and are exposed directly to sun light and rain, and some are installed around salt marshes and hot spring and have to withstand the harsh environment. Therefore, for aluminum-made heat-sinking fins, they have to be further treated by anodizing anti-oxidation processing. However, anodizing treatment is not environment friendly, causing high production and waste processing cost. 
     SUMMARY OF THE INVENTION 
     The invention provides a composite for coating and sputtering a heat-dissipating film. The composite contains silicon carbide of 25˜30 wt. % (weight percentage), teflon-based resin of 9-11 wt. %, and diluted ketones/alcohols-group material of 60˜65 wt. %. These components are mixed and blended to be capable of being coated, sputtered, and cured on the surface of an object to be heat-dissipated. According to experiment result, if sputtered on iron, the composite is able to achieve heat dissipation 20˜30 times better than baking varnish. In addition, the composite could be directly applied to aluminum and is able to achieve heat dissipation 10˜15 times better than aluminum of anodizing treatment. As such, there is no need to adopt heat-sinking fins of large surface area. The product therefore could be effectively downsized, conforming to the compactness trend of current product design. This is a major objective of the present invention. 
     Furthermore, the composite, after being sputtered and coated on the object to be heat-dissipated, is able to provide resistance to erosion and harsh weather. The conventional anodizing treatment therefore could be omitted and the production and recycling cost is significantly reduced. This is another objective of the present invention. 
     Additionally, to recycle a product coated with a heat-dissipating film made of the composite, there is no need to scrape and scrub the heat-dissipating film. When the product is burned in a furnace, due to the composite has different specific weight and material characteristics, the composite would be automatically separated and recovered. This is yet another objective of the present invention. 
     More importantly, the composite could be sputtered and coated on the surface of various metals (such as Fe, Al, Cu), various non-metallic materials (such as PP, PC, ABS), soft ceramic, various soft petroleum-based materials (such as acrylic, silicon), pure graphite, etc. In other words, the composite is widely applicable and, regardless the applied surface&#39;s shape and condition, the heat-dissipating performance could be easily enhanced. This is still another objective of the present invention. 
     The foregoing objectives and summary provide only a brief introduction to the present invention. To fully appreciate these and other objects of the present invention as well as the invention itself, all of which will become apparent to those skilled in the art, the following detailed description of the invention and the claims should be read in conjunction with the accompanying drawings. Throughout the specification and drawings identical reference numerals refer to identical or similar parts. 
     Many other advantages and features of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram showing the components of a composite for a heat-dissipating film according to the present invention. 
         FIG. 2  is a flow-chart diagram showing the process of manufacturing the composite of  FIG. 1 . 
         FIG. 3  is a flow-chart diagram showing the application of the composite of  FIG. 1  on an object to be heat-dissipated. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following descriptions are exemplary embodiments only, and are not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Various changes to the described embodiments may be made in the function and arrangement of the elements described without departing from the scope of the invention as set forth in the appended claims. 
       FIG. 1  is a schematic diagram showing the composition of a heat-dissipating film according to the present invention. As illustrated, the heat-dissipating film is made of a composite containing silicon carbide of 25˜30 wt. % (weight percentage), teflon-based resin of 9-11 wt. %, and diluted ketones/alcohols-group material of 60˜65 wt. %. The foregoing composition is obtained from repeated experiments and the composite thus formed could be coated and cured on the surface of an object to be heat-dissipated into a heat-dissipating film for enhanced heat dissipation performance. With such a heat-dissipating film, there is no need to rely on heat-sinking fins of large surface area. Therefore, production cost is reduced, recycling is easier, and highly contaminating anodizing treatment is avoided without sacrificing the robustness against erosion and harsh weather. The experiments are summarized in the following table: 
                                                 Major                           component   Percentage   Additives   Percentage   Outcome   Accepted                  aluminum   70   PU resin   10   The major   No       nitride       methanol   20   component                       deposits; caking is                       produced; the                       composite is                       sticky, cannot be                       stirred, and is not                       usable.       aluminum   30   PU resin   20   The phenomenon   No       nitride       toluene   50   of caking,                       stickiness,                       deposition is                       worse and                       the composite has                       unacceptable                       odor.       aluminum   30   PU resin   10   Deposition still   No       nitride       acetone   60   presents but the                       composite could                       be sputtered;                       however, there is                       too much wasted                       major component and                       no practical                       value.       aluminum   40   PU resin   10   Deposition and   No       nitride       methyl   50   caking are               ethyl       improved but the               ketone       composite still                       cannot be                       bucketed and                       sputtered and, if                       stored under room                       temperature, has                       the danger of                       evaporation.       aluminum   50   PP   10   Components are   No       nitride       methanol   40   not blended                       together and the                       composite is not                       usable.       aluminum   50   PP   10   Components are   No       nitride       acetone   40   not blended                       together and the                       composite is not                       usable.       aluminum   40   PP   10   Components are   No       nitride       methyl   50   not blended               ethyl       together and the               ketone       composite is not                       usable.       aluminum   50   acrylicresin   10   Components are   No       nitride       methanol   40   not blended                       together and the                       composite is not                       usable.       aluminum   60   acrylic   10   The composite is   No       nitride       acetone   30   sticky, has caking                       and low fluidness,                       and cannot be                       sputtered.       aluminum   50   acrylic   10   The composite is   No       nitride       methyl   30   sticky, has caking               ethyl       and low fluidness,               ketone       and cannot be                       sputtered.       aluminum   60   silicon   10   Components are   No       nitride       methanol   40   not blended                       together and the                       composite is not                       usable.       aluminum   70   silicon   10   Components are   No       nitride       acetone   20   not blended                       together and the                       composite is not                       usable.       aluminum   40   silicon   10   Components are   No       nitride       methyl   50   not blended               ethyl       together and the               ketone       composite is not                       usable.       aluminum   50   epoxy   10   Components are   No       nitride       methanol   40   not blended                       together and the                       composite is not                       usable.       aluminum   60   epoxy   10   Components are   No       nitride       acetone   30   not blended                       together and the                       composite is not                       usable.       aluminum   60   epoxy   10   Components are   No       nitride       methyl   30   not blended               ethyl       together and the               ketone       composite is not                       usable.       aluminum   60   teflon   10   Components are   No       nitride       methanol   20   not blended                       together and the                       composite is not                       usable.       aluminum   60   teflon   10   Components are   No       nitride       toluene   30   not blended                       together and the                       composite is not                       usable.       aluminum   70   teflon   10   Deposition still   No       nitride       acetone   20   presents but the                       composite could                       be sputtered;                       however, there is                       too much wasted                       major component                       and no practical                       value.       aluminum   50   teflon   10   Deposition still   No       nitride       methyl   40   presents but the               ethyl       composite could               ketone       be sputtered;                       however, there is                       too much wasted                       major component                       and no practical                       value.       boron   70   PU   10   The major   No       nitride       methanol   20   component                       deposits; caking is                       produced; the                       composite is                       sticky, cannot be                       stirred, and is not                       usable.       boron   60   PU   10   The major   No       nitride       toluene   30   component                       deposits; caking is                       produced; the                       composite is                       sticky, cannot be                       stirred, and is not                       usable.       boron   50   PU   10   The major   No       nitride       acetone   40   component&#39;s                       deposition is                       improved but the                       composite still                       cannot be                       bucketed and                       sputtered.       boron   50   PU   10   The phenomenon   No       nitride       methyl   40   of the major               ethyl       component&#39;s               ketone       deposition,                       stickiness, caking,                       and unable-to-stir                       is improved but                       the composite still                       cannot be                       bucketed and                       sputtered.       boron   60   PU   10   Components are   No       nitride       methanol   30   not blended                       together and the                       composite is not                       usable.       boron   60   PP   10   The major   No       nitride       toluene   30   component                       deposits; caking is                       produced; the                       composite is                       sticky, cannot be                       stirred, and is not                       usable.       boron   50   PP   10   Deposition still   No       nitride       acetone   40   presents but the                       composite could                       be sputtered;                       however, there is                       too much wasted                       major component                       and no practical                       value.       boron   50   acrylic   10   Components are   No       nitride       methanol   40   not blended                       together and the                       composite is not                       usable.       boron   50   acrylic   10   The composite is   No       nitride       toluene   20   sticky, has caking                       and low fluidness,                       and cannot be                       sputtered.       boron   70   acrylic   10   The composite is   No       nitride       acetone   20   sticky, has caking                       and low fluidness,                       and cannot be                       sputtered.       boron   40   acrylic   10   Caking is still   No       nitride       methyl   50   present but               ethyl       fluidness is               ketone       improved; and,                       even the                       composite is                       usable, it cannot                       be mass-produced.       boron   30   silicon   10   Components are   No       nitride       methanol   60   not blended                       together and the                       composite is not                       usable.       boron   40   silicon   10   Components are   No       nitride       acetone   50   not blended                       together and the                       composite is not                       usable.       boron   30   silicon   10   The phenomenon   No       nitride       toluene   60   of caking,                       stickiness, sinking                       is worse and the                       composite has                       unacceptable                       odor.       boron   30   silicon   10   Caking is still   No       nitride       methyl   60   present but               ethyl       fluidness is               ketone       improved; and,                       even the                       composite is                       usable, it cannot                       be mass-produced.       boron   70   epoxy   10   Components are   No       nitride       methanol   20   not blended                       together and the                       composite is not                       usable.       boron   70   epoxy   10   The phenomenon   No       nitride       toluene   20   of caking,                       stickiness, sinking                       is worse and the                       composite has                       unacceptable                       odor.       boron   40   epoxy   10   Deposition still   No       nitride       acetone   50   presents but the                       composite could                       be sputtered;                       however, there is                       too much wasted                       major component                       and no practical                       value.       boron   20   epoxy   10   Deposition still   No       nitride       methyl   70   presents but the               ethyl       composite could               ketone       be sputtered;                       however, there is                       too much wasted                       major component                       and no practical                       value.       boron   70   teflon   10   Components are   No       nitride       methanol   20   not blended                       together and the                       composite is not                       usable.       boron   40   teflon   10   The major   No       nitride       toluene   50   component                       deposits; caking is                       produced; the                       composite is                       sticky, cannot be                       stirred, and is not                       usable.       boron   20   teflon   10   Deposition still   No       nitride       acetone   70   presents but the                       composite could                       be sputtered;                       however, there is                       too much wasted                       major component                       and no practical                       value.       boron   40   teflon   10   The major   No       nitride       methyl   50   component               ethyl       deposits; caking is               ketone       produced, the                       composite is                       sticky, cannot be                       stirred, and is not                       usable.       silicon   20   PU   10   The composite is   No       carbide       methanol   70   better than the                       previous one but                       still cannot be                       bucketed and                       sputtered and, if                       stored under room                       temperature, has                       the danger of                       evaporation.       silicon   10   PU   10   Deposition still   No       carbide       acetone   80   presents but the                       composite could                       be sputtered;                       however, there is                       too much wasted                       major component                       and no practical                       value.       silicon   10   PP   10   The major   No       carbide       methanol   80   component                       deposits; caking is                       produced; the                       composite is                       sticky, cannot be                       stirred, and is not                       usable.       silicon   10   PP   10   The phenomenon   No       carbide       toluene   80   of caking,                       stickiness, sinking                       is worse and the                       composite has                       unacceptable                       odor.       silicon   30   acrylic   10   The composite is   No       carbide       methanol   60   better than the                       previous one but                       still cannot be                       bucketed and                       sputtered and, if                       stored under room                       temperature, has                       the danger of                       evaporation.       silicon   50   silicon   10   The components   No       carbide       toluene   40   are effectively                       blended but                       deposition is                       obvious; and the                       composite has to                       be further worked                       by continuous                       shaking,                       increasing the                       production                       difficulty       silicon   50   silicon   10   The components   No       carbide       acetone   40   begin to dissolve                       but there is highly                       sticky caking                       whose                       concentration is                       too high to                       decompose.       silicon   10   epoxy   10   The major   No       carbide       methanol   80   component                       deposits; caking is                       produced; the                       composite is                       sticky, cannot be                       stirred, has bad                       odor, and is not                       usable.       silicon   30   epoxy   10   Caking is still   Close to       carbide       methyl   60   present but   be               ethyl       fluidness is   accepted               ketone       improved; and,                       even the                       composite is                       usable, it cannot                       be                       mass-produced;                       the composite has                       bad odor and                       probably cannot                       pass examination;                       however, the                       composite could                       be actually                       applied by                       sputtering despite                       a weak adhesion                       and more                       suspended                       matters.                    
From the last experiment, the following conclusion could be drawn:
         1. Silicon carbide has the highest feasibility as the major component.   2. Compared to other experimented major components, there are more and stable sources and suppliers for silicon carbide, and therefore the composite&#39;s cost is more controllable.   3. To enhance the decomposition of suspended matters and adhesion strength of sputtering, more extensive analysis has to be conducted so as to increase the stability of the composite&#39;s manufacturing.   4. The most important issue is how well silicon carbide is integrated with high-level resin and whether heat conductivity could be continuously maintained after sputtering.   5. Additional components are required to achieve uniform coating without causing accumulated spots.   6. Numerous dissolvents for chemical combination are available and those that are hazardous could be avoided for enhanced safety.   7. The major component is easy to obtain and there is no concern over shortage or monopoly.
 
Accordingly, additional experiments are conducted and summarized in the following table:
       

                                                 Major                           com-   Percent-       Percent-       ponent   age   Additives   age   Outcome   Accepted                  silicon   30   teflon   9-11   There are   OK       carbide       acetone   60   extraneous                       suspended matters                       but, if well                       shaken, the                       composite&#39;s                       adhesion is not                       affected; the                       composite                       evaporates faster                       but has feasible                       adhesion; the                       composite seems                       satisfactory yet                       the adhesion is not                       uniform as spots                       are present.       silicon   30   teflon   9-11   There are   OK       carbide       acetone   60   extraneous                       suspended matters                       but, if well                       shaken, the                       composite&#39;s                       adhesion is not                       affected; the                       composite                       evaporates faster                       but has feasible                       adhesion; the                       composite seems                       satisfactory yet                       the adhesion is not                       uniform as spots                       are present; and,                       up to now, it                       seems that spots                       are standard                       phenomenon.       silicon   30   teflon   9-11   There are   OK       carbide       methyl   60   extraneous               ethyl       suspended matters               ketone       but, if well                       shaken, the                       composite&#39;s                       adhesion is not                       affected; the                       composite                       evaporates faster                       but has feasible                       adhesion; the                       composite seems                       satisfactory yet                       the adhesion is not                       uniform as spots                       are present.       silicon   30   teflon   9-11   There are   OK       carbide       methyl   60   extraneous               ethyl       suspended matters               ketone       but, if well                       shaken, the                       composite&#39;s                       adhesion is not                       affected; the                       composite                       evaporates faster                       but has feasible                       adhesion; the                       composite seems                       satisfactory yet                       the adhesion is not                       uniform as spots                       are present; and,                       up to now, it                       seems that spots                       are standard                       phenomenon.       silicon   30   teflon   9-11   There are   OK       carbide       acetone   30   extraneous               methyl   30   suspended matters               ethyl       but, if well               ketone       shaken, the                       composite&#39;s                       adhesion is not                       affected; the                       composite                       evaporates faster                       but has feasible                       adhesion; the                       composite seems                       satisfactory yet                       the adhesion is not                       uniform as spots                       are present; and,                       up to now, it                       seems that spots                       are standard                       phenomenon;                       ionizing state is                       more obvious and                       distribution is                       more uniform                       with no                       deposition; using                       a single dissolvent                       would have even                       better effect with                       enhanced                       volatility;                       however, lack of                       film thickness is                       still an issue.       silicon   30   teflon   9-11   There are   OK       carbide       acetone   25   extraneous               methyl   30   suspended matters               ethyl   10   but, if well               ketone       shaken, the               methanol       composite&#39;s                       adhesion is not                       affected; the                       composite                       evaporates faster                       but has feasible                       adhesion; the                       composite seems                       satisfactory yet                       the adhesion is not                       uniform as spots                       are present; and,                       up to now, it                       seems that spots                       are standard                       phenomenon;                       ionizing state is                       more obvious and                       distribution is                       more uniform                       with no                       deposition; using                       a single dissolvent                       would have even                       better effect with                       enhanced                       volatility;                       however, lack of                       film thickness is                       still an issue; the                       ionizing state is                       even more evident                       after adding                       methanol; the                       uniformity of                       particle sputtering                       is improved with                       even better                       volatility; gaps                       between particles                       and film thickness                       are stable; there is                       no non-uniformity                       problem;                       however, the                       volatility of                       methanol could be                       dangerous.       silicon   30   teflon   9-11   There are       carbide       acetone   25   extraneous               methyl   30   suspended matters               ethyl   10   but, if well               ketone       shaken, the               ethanol       composite&#39;s                       adhesion is not                       affected; the                       composite                       evaporates faster                       but has feasible                       adhesion; the                       composite seems                       satisfactory yet                       the adhesion is not                       uniform as spots                       are present; and,                       up to now, it                       seems that spots                       are standard                       phenomenon;                       ionizing state is                       more obvious and                       distribution is                       more uniform                       with no                       deposition; using                       a single dissolvent                       would have even                       better effect with                       enhanced                       volatility;                       however, lack of                       film thickness is                       still an issue; the                       ionizing state is                       even more evident                       after adding                       methanol; the                       uniformity of                       particle sputtering                       is improved with                       even better                       volatility; gaps                       between particles                       and film thickness                       are stable; there is                       no non-uniformity                       problem;                       however, the                       volatility of                       methanol could be                       dangerous;                       however, there is                       no volatile gas                       that would be                       hazardous to                       human.       silicon   25   teflon   9-11   For repeated   OK       carbide       acetone   25   applications for               methyl   30   20 times, the               ethyl   10   result is stable and               ketone       there is no               ethanol       non-uniform                       sputtering.                    
Up to now, the composition of the composite is determined.
 
     From the above experiments, the ketones/alcohols-group material  3  could be a composite of acetone, methyl ethyl ketone, methanol, and ethanol of appropriate amounts. The composite is then added and blended into the silicon carbide  1  to obtain a coating composite for sputtering onto an object to be heat-dissipated for enhanced heat dissipation. Up to the present time, coating with 0.02 um˜0.05 um has been successfully developed. To satisfy the requirement for a specific color, after repeated experiments, the present inventor found that gemstone powders could be optionally added and, by the interaction between the gemstone powders and the major component, the composite of a specific color could be achieved. In other words, the added gemstone powders are mainly used for mixing and fixing colors without sacrificing the heat conductivity. Therefore, depending on the color requirement, gemstone powders of appropriate amount could be added. The percentage of the gemstone powders could affect the shading of the color. 
     The manufacturing of the composite of the present invention could be conducted according to  FIG. 2 . As illustrated, after the silicon carbide is obtained, it first undergoes spheroidization and grinding/granulation, and dispensing. Then it is combined and mixed with a fixed amount of additives (teflon resin, gemstone powders). It is then blended with a fixed amount of dissolvent (acetone, methyl ethyl ketone, ethanol). Finally, it is dispensed for future application. 
     The composite&#39;s coating operation is depicted in  FIG. 3 . As illustrated, the composite is precisely sputtered and coated on the object to be heat-dissipated, and then cured to form a heat dissipation film. There are various types of curing, such as drying under room temperature, low- and mid-temperature sintering. The chose of curing method depends on the required film thickness and color. As the film thickness and color are also determined by the percentages of the major component and gemstone powders. These factors have to be jointly considered to determine the way of application of the composite. The working time would also vary accordingly and there is no fixed application procedure. 
     According to the foregoing description, the composite of the present invention, according to detailed experiments, is capable of being directly coated and sputtered on the surface of the object to be heat-dissipated, and then cured to a film of pre-determined thickness. As such, the heat-dissipating performance could be conveniently enhanced. There is no need to rely on heat-sinking fins of large surface area. The production cost is reduced, recycling is easier, and the highly contaminating anodizing treatment could be avoided, while the robustness against erosion and harsh weather is still maintained. 
     While certain novel features of this invention have been shown and described and are pointed out in the annexed claim, it is not intended to be limited to the details above, since it will be understood that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation can be made by those skilled in the art without departing in any way from the spirit of the present invention.