Patent Publication Number: US-2021180889-A1

Title: Copper-alloy heat-dissipation structure with milled surface

Description:
FIELD OF THE DISCLOSURE 
     The present disclosure relates to a heat dissipation structure, and more particularly, to a copper-alloy heat-dissipation structure with a milled surface. 
     BACKGROUND OF THE DISCLOSURE 
     In order to make heat dissipation more efficient, some heat sinks are made from a copper alloy. However, the copper alloy fabricated by means of powder metallurgy is generally porous. During fabrication, the final diameters of pores in a metal porous material are affected by various factors, such as fineness, distribution, shapes, and sintering temperature of selected powders.  FIG. 1  schematically shows a heat sink  1 A made from a copper alloy, which has surface pores  11 A. Consequently, a void  13 A is easily formed in tin solder  12 A after soldering (as shown in  FIG. 2 ), greatly reducing the quality of solder bonding. 
     In view of this, the inventor of the present disclosure has conceived of improvements to the related art after years of experience in development and design of related products, and based on deep study and application of relevant theory, finally proposed the heat-dissipation structure of the present disclosure that is sensibly designed and that can effectively alleviate the foregoing issue. 
     SUMMARY OF THE DISCLOSURE 
     The main objective of the present disclosure is to provide a copper-alloy heat-dissipation structure with a milled surface, so as to solve the foregoing issue. 
     To solve the foregoing technical issue, a technical solution adopted by the present disclosure is to provide a copper-alloy heat-dissipation structure with a milled surface, which includes a heat-dissipation main body. The heat-dissipation main body has a first milled surface and a second milled surface that are opposite each other, where heat-dissipation fins are formed on the first milled surface, and the maximum height roughness Rz of the second milled surface ranges from 1.5 μm to 5.4 μm. 
     In an exemplary embodiment, an average length Rsm of roughness curves of the second milled surface ranges from 0.05 mm to 0.50 mm. 
     In an exemplary embodiment, the heat-dissipation main body is made from a porous copper alloy. 
     In an exemplary embodiment, the heat-dissipation main body contains nickel, chrome, cobalt, and copper. 
     In an exemplary embodiment, the first milled surface and the second milled surface are formed by milling. 
     Therefore, in the copper-alloy heat-dissipation structure with a milled surface provided by the present disclosure, a heat-dissipation main body has a first milled surface and a second milled surface which are opposite to each other, and the maximum height roughness Rz of the second milled surface ranges from 1.5 μm to 5.4 μm. In this way, surface pores are avoided in the heat-dissipation main body, and thus voids are further avoided in tin solder after soldering, thereby improving the quality of solder bonding. Moreover, an average length Rsm of roughness curves of the second milled surface ranges from 0.05 mm to 0.50 mm Thus, the surface can be highly refined, and further, a stable and regular surface condition can stabilize the quality of solder bonding. 
     These and other aspects of the present disclosure will become apparent from the following description of the embodiment taken in conjunction with the following drawings and their captions, although variations and modifications therein may be affected without departing from the spirit and scope of the novel concepts of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more fully understood from the following detailed description and accompanying drawings. 
         FIG. 1  schematically shows a heat sink in the related art; 
         FIG. 2  schematically shows a heat sink and tin solder thereon in the related art; 
         FIG. 3  schematically shows a copper-alloy heat-dissipation structure with a milled surface in the present disclosure; 
         FIG. 4  schematically shows the maximum height roughness and an average length of roughness curves of a second milled surface in the present disclosure; and 
         FIG. 5  schematically shows a copper-alloy heat-dissipation structure with a milled surface and tin solder thereon in the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
     The present disclosure is more particularly described in the following examples that are intended as illustrative only since numerous modifications and variations therein will be apparent to those skilled in the art. Like numbers in the drawings indicate like components throughout the views. As used in the description herein and throughout the claims that follow, unless the context clearly dictates otherwise, the meaning of “a”, “an”, and “the” includes plural reference, and the meaning of “in” includes “in” and “on”. Titles or subtitles can be used herein for the convenience of a reader, which shall have no influence on the scope of the present disclosure. 
     The terms used herein generally have their ordinary meanings in the art. In the case of conflict, the present document, including any definitions given herein, will prevail. The same thing can be expressed in more than one way. Alternative language and synonyms can be used for any term(s) discussed herein, and no special significance is to be placed upon whether a term is elaborated or discussed herein. A recital of one or more synonyms does not exclude the use of other synonyms. The use of examples anywhere in this specification including examples of any terms is illustrative only, and in no way limits the scope and meaning of the present disclosure or of any exemplified term. Likewise, the present disclosure is not limited to various embodiments given herein. Numbering terms such as “first”, “second” or “third” can be used to describe various components, signals or the like, which are for distinguishing one component/signal from another one only, and are not intended to, nor should be construed to impose any substantive limitations on the components, signals or the like. 
     The following describes an implementation disclosed by the present disclosure by using a specific embodiment. Persons skilled in the art can understand the advantages and effects of the present disclosure from the content disclosed in the specification. The present disclosure can be embodied or applied through other different embodiments. Based on different opinions and applications, details of the present specification can also be modified and changed without departing from the concepts of the present disclosure. In addition, it should be stated beforehand that, the accompanying drawings of the present disclosure are merely for brief illustration and not drawn according to actual dimensions. The following implementation will further explain related technical content of the present disclosure, but the disclosed content is not intended to limit the scope of the present disclosure. 
     Refer to  FIG. 3 , which schematically shows a copper-alloy heat-dissipation structure with a milled surface in the present disclosure. As shown in  FIG. 3 , the copper-alloy heat-dissipation structure with a milled surface in the present disclosure has a heat-dissipation main body  1 . 
     The heat-dissipation main body  1  is exemplarily made from a copper alloy, but can also be made from an aluminum alloy, a magnesium alloy, or a titanium alloy. 
     In this embodiment, the heat-dissipation main body  1  is made from a copper alloy, thus achieving optimal heat conduction. In further detail, the copper alloy used for fabricating the heat-dissipation main body  1  contains nickel (Ni), chrome (Cr), cobalt (Co), copper (Cu), and inevitable impurities. The inevitable impurities are substances that exist in the raw materials or inevitably pass into the alloy during fabrication but do not affect the properties of the copper alloy, and therefore are considered acceptable impurities. 
     Specifically, the copper alloy, for example, can contain 1.5 to 3.6 weight percent nickel, 0.20 to 0.40 weight percent chrome, and 0.01 to 0.15 weight percent cobalt, thus ensuring the strength of the copper alloy. In addition, the copper alloy can also contain 0.05 to 3.0 weight percent zinc (Zn), which can improve the quality of solder bonding. 
     Moreover, the shape and the thickness of the heat-dissipation main body  1  are not specifically limited, and can be appropriately adjusted as required. In this embodiment, the heat-dissipation main body  1  has a first milled surface  11  and a second milled surface  12  that are opposite each other. 
     Heat-dissipation fins  111  are formed on the first milled surface  11 , and the shapes of the heat-dissipation fins  111  are not limited. The heat-dissipation main body  1  and the heat-dissipation fins  111  may be integrally formed, or they may be separately formed and then joined by welding or stamping. In this embodiment, the heat-dissipation main body  1  and the heat-dissipation fins  111  on its first milled surface  11  are integrally formed. In further detail, the heat-dissipation fins  111  may be formed by means of mechanical processing (cutting or grinding). 
     The second milled surface  12  is formed on one side of the heat-dissipation main body  1  by a milling process. Therefore, plastic deformation may be implemented within a certain range by a specific milling process, to eliminate surface pores from one side of the heat-dissipation main body  1  and achieve low surface roughness, thus improving the quality of solder bonding. 
     Referring to  FIG. 4  and  FIG. 5 ,  FIG. 4  schematically shows the maximum height roughness Rz and an average length Rsm of roughness curves of the second milled surface  12  in this embodiment. 
     Specifically, the maximum height roughness Rz of the second milled surface  12  in this embodiment ranges from 1.5 μm to 5.4 μm. Within this range, the surface pores can be avoided, and voids can be further avoided in tin solder  13  after soldering, thereby improving the quality of solder bonding (as shown in  FIG. 5 ). If the maximum height roughness Rz exceeds 5.4 μm, it would be difficult to meet a range of the average length Rsm of roughness curves described below. 
     More specifically, the average length Rsm of roughness curves of the second milled surface  12  in this embodiment ranges from 0.05 mm to 0.50 mm Within this range, the second milled surface  12  can be highly refined. If the average length Rsm of the roughness curves exceeds 0.50 mm, intervals between tips of surface protrusions are increased, thus making it difficult to meet the range of the maximum height roughness Rz described above. 
     In addition, various milling processes can all be taken into consideration to achieve the maximum height roughness Rz and the average length Rsm of the roughness curves of the second milled surface  12 . 
     Moreover, various milling tools, such as a face mill made from tungsten carbide steel and a bull end mill made from tungsten steel, can all be taken into consideration for use. However, the milling tools and their materials are not limited to the above description. 
     In conclusion, in the copper-alloy heat-dissipation structure with a milled surface provided by the present disclosure, a heat-dissipation main body  1  has a first milled surface  11  and a second milled surface  12  that are opposite to each other, and the maximum height roughness Rz of the second milled surface  12  ranges from 1.5 μm to 5.4 μm. In this way, surface pores are avoided in the heat-dissipation main body  1 , and thus voids are further avoided in tin solder  13  after soldering, thereby improving the quality of solder bonding. Moreover, an average length Rsm of roughness curves of the second milled surface  12  ranges from 0.05 mm to 0.50 mm, such that the surface can be highly refined. 
     The foregoing description of the exemplary embodiments of the disclosure has been presented only for the purposes of illustration and description and is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Many modifications and variations are possible in light of the above teaching. 
     The embodiments were chosen and described in order to explain the principles of the disclosure and their practical application so as to enable others skilled in the art to utilize the disclosure and various embodiments and with various modifications as are suited to the particular use contemplated. Alternative embodiments will become apparent to those skilled in the art to which the present disclosure pertains without departing from its spirit and scope.