Abstract:
An apparatus to clean an electronic device may include a head structure having a first surface adapted to face a body to be cleaned, and a plurality of supply openings and return openings on the first surface. At least a portion of the supply openings and return openings are positioned as alternating rows of supply openings and return openings. The supply openings are larger in area than the return openings in at least a majority of the alternating rows. The supply openings and the return openings are adapted to transmit at least one of a gas and a liquid therethrough. The head structure is adapted to permit the transmission of at least one of a gas and a liquid through the supply openings and at the same time the head structure is also adapted to permit the transmission of at least one of a gas and a liquid through the return openings. Other embodiments are described and claimed.

Description:
RELATED ART 
       [0001]    Integrated circuits may be formed on semiconductor wafers made of materials such as silicon. The semiconductor wafers are processed to form various electronic devices. The wafers are diced into semiconductor chips (a chip is also known as a die), which may then be attached to a package substrate using a variety of known methods. During certain types of procedures, for example, testing, a thermal interface fluid may be placed onto a surface of an electronic device in order to control the temperature of the device during operations. After testing, it is desired to remove the interface fluid and foreign material that has accumulated on the surface of the electronic device. Such a removal process may be termed a de-application (or De-App) process. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0002]    Embodiments are described by way of example, with reference to the accompanying drawings, which are not drawn to scale, wherein: 
           [0003]      FIG. 1  illustrates a view of a surface of a head that may be used for cleaning an electronic device surface in accordance with certain embodiments; 
           [0004]      FIG. 2  illustrates a blown up view of the region B in  FIG. 1 , showing openings in the surface, in accordance with certain embodiments; 
           [0005]      FIG. 3  illustrates a view of an intermediate level in a head structure, in accordance with certain embodiments; 
           [0006]      FIG. 4  illustrates a view of an upper surface of a head structure, in accordance with certain embodiments; 
           [0007]      FIG. 5  illustrates a cross-sectional view of an apparatus including an assembly of components including a head, a manifold, and a gasket, in accordance with certain embodiments; 
           [0008]      FIG. 6  illustrates a portion of a head including supply and return openings positioned over a surface to be cleaned, and directions of flow, in accordance with certain embodiments; 
           [0009]      FIG. 7  illustrates a cross-sectional view of a gasket structure positioned between a head and a device having a surface to be cleaned, in accordance with certain embodiments; 
           [0010]      FIG. 8  illustrates a cross-sectional view of a gasket structure positioned between a head and a device having a surface to be cleaned, in accordance with certain embodiments; 
           [0011]      FIG. 9  illustrates an arrangement of supply and return openings that may be positioned on a head, in accordance with certain embodiments; and 
           [0012]      FIG. 10  illustrates a flow chart of process operations, in accordance with certain embodiments. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    The need for cleaning a surface of an electronic device may arise after an interface fluid is utilized on the surface. The interface fluid may act to collect foreign material on and upon evaporation or other removal of the interface material, a quantity of foreign material may remain on the surface in the form of stains. Certain embodiments relate to cleaning of an electronic device surface and removal of remaining interface fluid and foreign materials that have accumulated on the surface. This may be carried out using an apparatus including a head structure positioned adjacent to a surface to be cleaned. 
         [0014]      FIG. 1  illustrates a first surface  16  of a head  10  that may be used for cleaning an electronic device surface in accordance with certain embodiments. Examples of electronic device surfaces include, but are not limited to, a semiconductor die and a lid positioned to cover a semiconductor die in a package. As indicated by the arrows in  FIG. 1 , the surface  16  of the head  10  includes a plurality of rows R 1 -R 23  of openings  12   a,    12   b,  and  14 . As illustrated in  FIG. 1 , the uppermost and lowermost rows R 1  and R 23  include openings  12   a . Between the rows R 1  and R 23  are alternating rows of openings  14  and openings  12   b.  The openings  12   a,    12   b,  and  14  are used to transmit gas and fluid to the surface to be cleaned and to remove the gas, fluid, and foreign material from the surface to be cleaned. 
         [0015]    In accordance with certain embodiments, the head  10  may be used together with several other components as illustrated in  FIG. 5 , in order to clean a surface of an electronic device  6 . The head  10  is positioned below a manifold  2 . The manifold  2  is a structure that directs and receives gas and liquid to and from the head  10 . A gasket  4  may be positioned between the head  10  and the electronic device  6 . The gasket  4  acts to form a seal between the head  10  and the device  6 , to form a closed region on the surface to be cleaned by inhibiting the flow of gas and liquid off of the sides of the surface to be cleaned on the device  6 . 
         [0016]    As noted above, the openings  12   a,    12   b,  and  14  illustrated in  FIG. 1  are used to transmit gas and fluid to the surface to be cleaned and to remove the gas, fluid, and foreign material from the surface to be cleaned. In the embodiment of  FIG. 1 , the rows alternate between supply openings and return openings. By supply openings it is meant that these openings supply gas and/or liquid to the surface to be cleaned. By return openings it is meant that these openings are used to remove the supply gas and/or liquid and any foreign material from the surface to be cleaned. The supply openings include openings  12   a  and  12   b . The difference between the openings  12   a  and  12   b  is that the  12   a  openings are smaller than the  12   b  openings. In this embodiment, only the end rows (top and bottom as illustrated in  FIG. 1 ) of openings are the smaller openings  12   a.  The rest of the supply openings are the larger openings  12   b.  The return openings include the openings  14 . These openings are smaller than the supply openings  12   b.  The relative size of the openings  12   b  and  14  of  FIG. 1  can be seen more clearly in  FIG. 2 , which is an expanded up view of a portion B of the surface  16  of the head  10 . 
         [0017]    The openings may take a variety of shapes, including, but not limited to, rectangular, round, and oval. The embodiment illustrated in  FIG. 1  includes openings that are substantially rectangular in shape. In certain embodiments the openings may include length and width dimensions ranging from 100 microns to 1000 microns. Other embodiments may include length and width dimensions ranging from 200 microns to 800 microns. One specific example of sizes of the openings  12   a,    12   b,  and  14  in  FIG. 1  includes length and width dimensions of  450  microns by  350  microns for the openings  12   a  and  14 , and 740 microns×350 microns for the openings  12   b.    
         [0018]      FIG. 6  illustrates a portion of the head  10  and a surface to be cleaned on device  6  and includes arrows showing the direction of flow of fluid (for example, gas and/or liquid) from the supply openings  12   b  to the return openings  14 .  FIG. 6  shows two supply openings  12   b  and two return openings  14 . As indicated by the arrows, a fluid flows through the head and through the supply openings  12   b  and is directed towards the surface to be cleaned  9  on the device  6 . The fluid contacts the surface  9  and is then drawn towards the return openings. Foreign material on the surface  9  will be impacted by the fluid and removed from the surface  9  through the return openings  14 . 
         [0019]    In certain embodiments, the distance between the surface to be cleaned and the head surface containing the supply and return openings is no greater than about 1000 microns. It has been found that the use of larger sized supply openings than return openings leads to better cleaning. This is believed to be due to the ability to generate relatively high shear stresses and high gas velocity through the supply openings, across the surface to be cleaned, and back through the return openings in the head. In addition, the use of a relatively large number of openings spaced close to the surface to be cleaned has been found to be more effective than using fewer openings spaced further apart from one another. Having a large number of openings minimizes the presence of stagnation zones (where there is little flow across a portion of the surface to be cleaned). 
         [0020]    The head structure  10  may be formed to include a plurality of layers including paths that lead from the top surface of the head  10  that is coupled to the manifold  2 , to the bottom surface of the head that includes the surface having the supply and return openings and which faces the surface to be cleaned, as illustrated in  FIG. 5 . These paths act to guide the flow of gas, liquid, and other materials towards the surface to be cleaned and away from the surface to be cleaned. 
         [0021]      FIG. 3  illustrates an intermediate level  21  in the head structure between the head surface  16  adjacent to the surface to be cleaned and the head surface  26  adjacent to the manifold  2 . The intermediate level  21  in the head  10  includes a number of slots of alternating width. As illustrated in  FIG. 3 , slots  50 ,  54 ,  58 ,  62 ,  66 ,  70 ,  74 ,  78 ,  82 ,  86 , and  90  are positioned over and in communication with the supply openings  12   a  or  12   b  in corresponding rows R 1 , R 3 , R 5 , R 7 , R 9 , R 11 , R 13 , R 15 , R 17 , R 19 , R 21 , and R 23  of  FIG. 1 . Likewise, the slots  52 ,  56 ,  60 ,  64 ,  68 ,  72 ,  76 ,  80 ,  84 ,  88 , and  92  are positioned over and in communication with the return openings R 2 , R 4 , R 6 , R 8 , R 10 , R 12 , R 14 , R 16 , R 18 , R 20 , and R 22  of  FIG. 1 . From the surface  16  to the intermediate level  21  in the head  10 , each row of the supply openings  12   a,    12   b  and return openings  14  is in communication with a corresponding slot. 
         [0022]      FIG. 4  illustrates the top surface  26  of the head  10 . This top surface  26  is adjacent to the manifold  2  as illustrated in  FIG. 5 . A plurality of slots are positioned at this top surface  26  (upper level) of the head  10 . The slots at this surface  26  are configured in alternating rows of one intermediate length slot (positioned in communication with a row of supply openings) and two short slots (in communication with a row of return openings), with the slots all spaced a larger distance apart at this surface than at the intermediate level  21 . Such spacing may make it easier to provide proper alignment between the manifold and head for transmission of gas, fluid, etc. therebetween. These slots will be in communication with the corresponding slots therebelow and in communication with the manifold  2 . Slots  102 ,  112 ,  122 ,  132 ,  142 ,  152 ,  162 ,  172 ,  182 ,  192 ,  202 , and  212  are positioned over and in communication with slots  50 ,  54 ,  58 ,  62 ,  66 ,  70 ,  74 ,  78 ,  82 ,  86 ,  90 , and  94 . Slots  104  and  106  are relatively short slots and are positioned over and in communication with slot  52 . 
         [0023]    Similarly, slots  114  and  116  are positioned over and in communication with slot  56 , slots  124  and  126  are positioned over and in communication with slot  60 , slots  134  and  136  are positioned over and in communication with slot  64 , slots  144  and  146  are positioned over and in communication with slot  68 , slots  154  and  156  are positioned over and in communication with slot  72 , slots  164  and  166  are positioned over and in communication with slot  76 , slots  174  and  176  are positioned over and in communication with slot  80 , slots  184  and  186  are positioned over and in communication with slot  84 , slots  194  and  196  are positioned over and in communication with slot  88 , and slots  204  and  206  are positioned over and in communication with slot  92 . 
         [0024]    As illustrated in  FIG. 5 , the gasket  4  acts to form a closed system and inhibit the flow of supply and return materials off of the sides of the surface being cleaned. Depending on the size and shape of the surface to be cleaned, a variety of gasket configurations may be used. For example, in certain embodiments, the gasket may sit on a flat outer portion of a surface to be cleaned. In another embodiment, the gasket includes an angled surface which is designed to engage the upper edges of the surface to be cleaned.  FIG. 7  illustrates an embodiment in which a gasket  4  positioned between a head  10  and device  6  is positioned to engage a portion of the upper surface  9  to be cleaned on the device  6 . The gasket  4  includes an end region  4 ′ having a flat surface that is positioned on the surface  9 .  FIG. 8  illustrates and embodiment in which a gasket includes an angled end region  4 ″ that is configured to engage a corner edge region of the device  6 . This is carried out by forming the gasket to include an angled surface, for example, 30° from horizontal. 
         [0025]      FIG. 9  illustrates an example of a configuration of openings  212 ,  213 ,  214  that may be used on the surface of a cleaning head. In practice more rows and more openings may be present but this view is intended to show the relative positioning of the rows and shape of the openings. In this embodiment the openings  212 ,  213 ,  214  are all round in shape. The openings are arranged in rows and include two rows spaced close to one another and then one row spaced further apart. The pattern repeats itself, with an alternating pattern of two closely spaced rows of openings (one row includes openings  212  and the second includes openings  213 ) and one further spaced apart row of openings  214 . In certain embodiments, the openings  212  and  213  in the closely spaced rows act as supply openings, and the openings  214  in the spaced apart row act as return openings. The openings  212 ,  213 , and  214  may in certain embodiments be the same size, which may lead to advantages in manufacturing the head. 
         [0026]      FIG. 10  illustrates a flowchart of operations, in accordance with certain embodiments. Box  300  is aligning a surface to be cleaned with the head and gasket. Box  302  is applying a vacuum to return openings in the head. Box  304  is providing gas (for example, air) to the supply openings in the head and in turn to the surface to be cleaned. Box  306  is providing a liquid (for example, distilled water) to the supply openings so that the liquid can be supplied to the surface to be cleaned. Box  308  is ending the supply of liquid to the supply openings. Box  310  is ending the flow of gas to the supply openings. Box  312  is ending the vacuum to the return openings. 
         [0027]    In certain embodiments of a De-App process, the vacuum CFM flow may be between 0.8 and 4.0 CFM, with a vacuum pressure between 10 and 25 in of Hg. In certain embodiments, the air pressure may include and air CFM flow of between 0.8 and 4.0 CFM, and an air pressure of between 10 psi and 100 psi. In certain embodiments, the air temperature may be between 10° C. and 100° C. In certain embodiments, the total amount of liquid (for example, water) used during a De-App process may be between 0.1 cc and 5 cc. Another range of water use is between 0.3 cc and 2 cc of water. During one specific De-App process, the entire process takes approximately 4 seconds, with 0.5 seconds air flow through the supply openings, followed by 0.5 seconds of both air flow and distilled water flow, followed by 3 seconds of just air flow. Such a process may utilize a very small quantity of distilled water, for example, one or two drops. It is believed that the use of a liquid aids in stain removal. In certain embodiments, the additional of a liquid may not be necessary. 
         [0028]    It should be appreciated that an assembly including a head structure such as described above may be used for not only cleaning operations but in certain embodiments may also be used during other operations, for example, to deliver and remove liquids and gases to a surface. For example, during certain testing procedures, a thermal interface material may be placed onto a device to control the temperature during testing and then removed after the testing. A head structure including supply openings and return openings may be used for carrying out such operations. After those operations are complete, the same head may be used to carry of a De-App operation to clean any staining off the device as described above. 
         [0029]    Terms such as “above”, “below”, “first”, “second”, and the like as used herein to not necessarily denote any particular order, quantity, or importance, but are used to distinguish one element from another. Terms such as “top”, “bottom”, “upper”, and “lower” and the like as used herein refer to the orientation of features as illustrated in the attached figures. The term opening refers to an aperture or orifice through which a material may flow. 
         [0030]    While certain exemplary embodiments have been described above and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative and not restrictive. For example, the exact layout of openings and pathways through a head may vary from that described above. Embodiments are not restricted to the specific constructions and arrangements shown and described since modifications may occur to those having ordinary skill in the art.