Patent Publication Number: US-2023154818-A1

Title: Header for semiconductor package

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims priority to Japanese Patent Application No. 2021-187285, filed on Nov. 17, 2021, the entire contents of which are incorporated herein by reference. 
     FIELD 
     Certain aspects of the embodiments discussed herein are related to headers for semiconductor packages. 
     BACKGROUND 
     A header for a semiconductor package may be mounted with a semiconductor device, such as a light emitting element, for example. A known configuration of the header may include a disk shaped eyelet, and a metal block protruding from an upper surface of the disk shaped eyelet, for example. The metal block includes a surface forming a device mounting surface on which the semiconductor device is to be mounted. The eyelet is provided with a plurality of through holes to be inserted with leads, and the leads are sealed inside the through holes by a sealer, such as glass or the like. 
     An example of the header for the semiconductor device is proposed in Japanese Laid-Open Patent Publication No. 2004-235212, for example. 
     In the header for the semiconductor package described above, the leads penetrate the eyelet and protrude from a lower surface of the eyelet, to thereby extend in a direction perpendicular to the lower surface of the eyelet. For this reason, when a heat sink, such as a heat spreader or the like, is disposed on the lower surface of the eyelet, it is necessary to provide a hole for inserting the lead in the heat spreader or the like. Accordingly, it is not easy to dispose the heat sink on the lower surface of the eyelet. 
     SUMMARY 
     Accordingly, it is an object in one aspect of the embodiments to provide a header for a semiconductor package that enables a heat sink to be easily disposed on a lower surface of an eyelet. 
     According to one aspect of the embodiments, a header for a semiconductor package includes an eyelet having a first surface, a second surface opposite to the first surface, a side surface, and a first through hole penetrating the eyelet from the first surface to the second surface; a lead inserted through the first through hole; and a metal base bonded to the second surface of the eyelet, wherein the lead is bent at the second surface of the eyelet and protrudes from the side surface of the eyelet in a plan view, the metal base is spaced apart from the lead, and the lead, located at a position overlapping the eyelet in the plan view, is disposed within a thickness range of the metal base in a side view. 
     The object and advantages of the embodiments will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1 A  and  FIG.  1 B  are perspective views illustrating an example of a header for a semiconductor package according to a first embodiment; 
         FIG.  2 A  and  FIG.  2 B  are diagrams illustrating the example of the header for the semiconductor package according to the first embodiment; 
         FIG.  3    is a partially enlarged cross sectional view of a part B illustrated in  FIG.  2 B ; 
         FIG.  4    is a diagram (part 1) illustrating a manufacturing process of the header for the semiconductor package according to the first embodiment; 
         FIG.  5 A ,  FIG.  5 B , and  FIG.  5 C  are diagrams (part 2) illustrating manufacturing processes of the header for the semiconductor package according to the first embodiment; and 
         FIG.  6    is perspective view illustrating an example of a state of use of the header for the semiconductor package. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, those parts that are the same are designated by the same reference numerals, and a repeated description of the same parts may be omitted. 
     First Embodiment 
       FIG.  1 A  and  FIG.  1 B  are perspective views illustrating an example of a header for a semiconductor package according to a first embodiment.  FIG.  1 A  is the perspective view viewed from above, and  FIG.  1 B  is the perspective view viewed from below.  FIG.  2 A  and  FIG.  2 B  are diagrams illustrating the example of the header for the semiconductor package according to the first embodiment.  FIG.  2 A  is a plan view, and  FIG.  2 B  is a cross sectional view along a line A-A in  FIG.  2 A . 
     As illustrated in  FIG.  1 A  through  FIG.  2 B , a header  1  for the semiconductor package (hereinafter also referred to as a “semiconductor package header  1 ”) according to the first embodiment includes an eyelet  10 , a metal block  30 , a first lead  41 , a second lead  42 , a sealer  50 , and a metal base  60 . 
     The eyelet  10  is a disk-shaped member. In the present specification, the term “disk-shaped member” refers to a member having an approximately circular planar shape and a predetermined thickness. The predetermined thickness relative to the diameter of the disk-shaped member is not particularly limited. In addition, the disk-shaped member may partially include a portion formed with a recess, a protrusion, a through hole, or the like. 
     Moreover, in the present specification, a plan view of an object refers to a view of the object from above the object, viewed in a normal direction to an upper surface  10   a  of the eyelet  10 , and a planar shape of the object refers to the shape of the object in the plan view viewed in the normal direction to the upper surface  10   a  of the eyelet  10 . Further, in the present specification, the terms “parallel”, “perpendicular”, and “right angle” can tolerate a difference within ±5 degrees, unless specifically referred to as being perfectly (or exactly) “parallel”, “perpendicular”, and “right angle”. 
     Cutouts  11  and  12 , that are flat surfaces on opposite ends, may be formed on a side surface of the eyelet  10 . The cutouts  11  and  12  may be used for positioning a device mounting surface or the like when the semiconductor package header  1  is mounted with a semiconductor device, for example. The cutouts  11  and  12  may be used for positioning the semiconductor package header  1  in a rotating direction. The cutouts  11  and  12  may be provided, as required. 
     A diameter of the eyelets  10  is not particularly limited, and may be determined appropriately according to needs or purpose. The diameter of the eyelet  10  may be 5.6 mm (ø5.6 mm), 9.0 mm (ø9.0 mm), or the like, for example. The thickness of the eyelet  10  is not particularly limited, and may be determined appropriately according to the needs or purpose. The thickness of the eyelet  10  may be in a range of approximately 0.5 mm to approximately 3 mm, for example. 
     The eyelet  10  can be formed of a metallic material, such as iron, stainless steel, or the like, for example. The eyelet  10  may be formed of a metallic material (for example, a so-called cladding material) in which multiple metal layers (copper layers, iron layers, or the like) are laminated. A surface of the eyelet  10  may be plated. The plating provided on the surface of the eyelet  10  may be gold plating, for example. 
     A through hole  10   x  formed in the eyelet  10  penetrates from the upper surface  10   a  to the lower surface  10   b  of the eyelet  10 . A first end of the metal block  30  is inserted into the through hole  10   x  provided in the eyelet  10 , and a second end of the metal block  30 , opposite to the first end, protrudes from the upper surface  10   a  of the eyelet  10 . In the present embodiment, the metal block  30  includes a pedestal  31 , and a columnar part  32  protruding from an upper surface  31   a  of the pedestal  31 , for example. The pedestal  31  and the columnar part  32  are integrally formed. The columnar part  32  includes a device mounting surface  30   r  on which a semiconductor device (for example, a light emitting element, such as a laser or the like) is to be mounted. The device mounting surface  30   r  is provided so as to be perpendicular to the upper surface  10   a  of the eyelet  10 . The upper surface  31   a  of the pedestal  31  is not limited to a flat surface. 
     The first end of the metal block  30  is bonded to the metal base  60 . In the present embodiment, the pedestal  31  is inserted into the through hole  10   x  of the eyelet  10 , and the lower surface of the pedestal  31  (that is, a lower surface  30   b  of the metal block  30 ) is bonded to the metal base  60 , for example. The columnar part  32  includes a portion protruding from the upper surface  10   a  of the eyelet  10 . A large portion of the columnar part  32  protrudes from the upper surface  10   a  of the eyelet  10 . The entire columnar part  32  may protrude from the upper surface  10   a  of the eyelet  10 , however, a portion of the columnar part  32  at the pedestal  31  is preferably located inside the through hole  10   x . The lower surface  30   b  of the metal block  30  approximately coincides with the lower surface  10   b  of the eyelet  10 , for example. 
     In the plan view, an outer periphery of the upper surface  31   a  of the pedestal  31  is exposed around the columnar part  32 . At the outer periphery of the upper surface  31   a  of the pedestal  31  exposed around the columnar part  32 , a width of the upper surface  31   a  at the device mounting surface  30   r  is narrower than the width of the upper surface  31   a  at surfaces other than the device mounting surface  30   r . In other words, in the plan view, a center of the columnar part  32  is offset with respect to a center of the pedestal  31  along a direction of a line A-A toward the first lead  41  and second lead  42 . At the outer periphery of the upper surface  31   a  of the pedestal  31  exposed around the columnar part  32 , the width of the upper surface  31   a  at the device mounting surface  30   r  may be approximately 0.05 mm, and the width of the upper surface  31   a  at the surfaces other than the device mounting surface  30   r  may be approximately 0.5 mm, for example. Such a shape of the columnar part  32  can positively secure a sufficiently large area to dispose the first lead  41  and the second lead  42  in the eyelet  10 . 
     In the plan view, the pedestal  31  has a generally rectangular shape, but corners at both ends of a first side of the pedestal  31  at the device mounting surface  30   r  (on the side of the first lead  41  and the second lead  42 ) are rounded, and corners at both ends of a second side of the pedestal  31 , opposing the first side, are rounded with a radius larger than that of the corners at both ends of the first side. Such a shape of the pedestal  31  facilitates the arrangement of the pedestal  31  along the shape of the eyelet  10 . 
     In the plan view, the columnar part  32  has a generally rectangular shape, but corners at both ends of a first side of the columnar part  32  at the device mounting surface  30   r  are rounded, and corners at both ends of a second side opposing the first side are rounded to the same extent as the corners at both ends of the first side. The columnar part  32  is a part for mounting and fixing the semiconductor device when the semiconductor package header  1  is used as a semiconductor package mounted with the semiconductor device, and also functions as a heat sink for dissipating heat generated from the semiconductor device. Such a shape of the columnar part  32  described above can secure a sufficiently large volume of the columnar part  32 , and improve the heat dissipation. 
     A distance between the upper surface  30   a  of the metal block  30  and the upper surface  10   a  of the eyelet  10 , that is, a protruding distance of the columnar part  32   from the upper surface  10   a  of the eyelet  10 , may be in a range of approximately 3 mm to approximately 4 mm, for example. A material having a higher thermal conductivity than the eyelet  10  may be used for the metal block  30 . If the material used for the eyelet  10  is iron, the material used for the metal block  30  may be copper, for example. 
       FIG.  3    is a cross sectional view, on an enlarged scale, illustrating a portion of a part B illustrated in  FIG.  2 B . As illustrated in  FIG.  3   , a portion of the device mounting surface  30   r  is preferably located inside the through hole  10   x . Due to reasons during the process of forming (or preparing) the metal block  30 , the rollover occurs in a rollover region at the pedestal  31  of the device mounting surface  30   r . The term “rollover” refers to a rounded edge that is made in an area of a material next to an edge of a die by yielding in the direction of the applied force when the material is forged in the die. The rollover region becomes rounded and does not become flat. Because a portion of the device mounting surface  30   r  is located inside the through hole  10   x , the rollover region of the device mounting surface  30   r  can be inserted into the through hole  10   x . Preferably, the entire rollover region of the device mounting surface  30   r  is located inside the through hole  10   x . In this case, it is possible to increases an area of a flat region of the device mounting surface  30   r  at the portion protruding from the upper surface  10   a  of the eyelet  10 . As a result, it is possible to mount relatively large devices. 
     Referring back to  FIG.  1 A  through  FIG.  2 B , two through holes  10   y  formed in the eyelet  10  penetrate from the upper surface  10   a  to the lower surface  10   b  of the eyelet  10 . The first lead  41  and the second lead  42  are inserted into the two different through holes  10   y , respectively. The first lead  41  and the second lead  42  may be inserted into a single through hole  10   y  in a state insulated from each other. The first lead  41  and the second lead  42  are bent at the lower surface  10   b  of the eyelet  10 , and protrude from the side surface of the eyelet  10  in the plan view. Diameters of the first lead  41  and the second lead  42  may be in a range of approximately 0.3 mm to approximately 1 mm, for example. 
     The first lead  41  has a first part  41 A penetrating the eyelet  10 , and a second part  41 B continuous with the first part  41 A and parallel to the lower surface  10   b  of the eyelet  10 . Similarly, the second lead  42  has a first part  42 A penetrating the eyelet  10 , and a second part  42 B continuous with the first part  42 A and parallel to the lower surface  10   b  of the eyelet  10 . 
     The first part  41 A of the first lead  41  is inserted into the through hole  10   y  penetrating the eyelet  10  from the upper surface  10   a  to the lower surface  10   b , so as to be perpendicular to the upper surface  10   a  of the eyelet  10 . Similarly, the first part  42 A of the second lead  42  is inserted into the through hole  10   y  penetrating the eyelet  10  in a thickness direction, so as to be perpendicular to the upper surface  10   a  of the eyelet  10 . Inside the through holes  10   y  of the eyelet  10 , peripheries of the first part  41 A of the first lead  41 , and peripheries of the first part  42 A of the second lead  42 , are sealed by the sealer  50 . 
     In the first lead  41 , an angle formed by the first part  41 A and the second part  41 B is at a right angle, for example. In the second lead  42 , an angle formed by the first part  42 A and the second part  42 B is at a right angle, for example. The second part  41 B of the first lead  41  and the second part  42 B of the second lead  42  are parallel to each other, for example. However, the second part  41 B of the first lead  41  may be non-parallel to the second part  42 B of the second lead  42 . 
     The first part  41 A of the first lead  41  is parallel to the first part  42 A of the second lead  42 , for example. Portions of the first part  41 A of the first lead  41  and the first part  42 A of the second lead  42  protrude from the upper surface  10   a  and the lower surface  10   b  of the eyelet  10 . In the first part  41 A of the first lead  41  and the first part  42 A of the second lead  42 , an amount of protrusion of the portions protruding from the upper surface  10   a  of the eyelet  10  is in a range of approximately 1 mm to approximately 3 mm, for example. In the first part  41 A of the first lead  41  and the first part  42 A of the second lead  42 , an amount of protrusion of the portions protruding from the lower surface  10   b  of the eyelet  10  is in a range of approximately 0.5 mm to approximately 1.5 mm, for example. 
     Portions of the second part  41 B of the first lead  41  and the second part  42 B of the second lead  42  protrude from the side surface of the eyelet  10  in the plan view. In the second part  41 B of the first lead  41  and the second part  42 B of the second lead  42 , an amount of protrusion of the portions protruding from the side surface of the eyelet  10  in the plan view is in a range of approximately 1 mm to approximately 3 mm, for example. However, in the second part  41 B of the first lead  41  and the second part  42 B of the second lead  42 , the amount of protrusion of the portions protruding from the side surface of the eyelet  10  in the plan view may be varied appropriately according to usage. The usage includes a case where the first lead  41  and the second lead  42  are inserted into a socket, a case where wires are soldered onto the first lead  41  and the second lead  42 , or the like. 
     The first lead  41  and the second lead  42  are formed of a metallic material, such as a 50%iron-nickel alloy, Kovar, or the like, for example. The sealer  50  is formed of an insulating material, such as a glass material or the like, for example. The first lead  41  and the second lead  42  are electrically connected to a semiconductor device mounted on the semiconductor package header  1 , for example. The number of leads may be increased or decreased according to the specification of the semiconductor device to be mounted on the semiconductor package header  1 . 
     The metal base  60  is bonded to the lower surface  10   b  of the eyelet  10 , so as to cover and close one end of the through hole  10   x . For example, in the plan view, an outer contour of the metal base  60  is smaller than an outer contour of the eyelet  10 , and the metal base  60  does not have a portion that protrudes from the outer contour of the eyelet  10 . The metal base  60  is spaced apart from the first lead  41  and the second lead  42 . That is, the metal base  60  is not provided at portions where the first lead  41  and the second lead  42  pass through. In other words, the metal base  60  does not have the through holes  10   y  for receiving the first lead  41  and the second lead  42  to pass through. 
     The first lead  41  and the second lead  42  located at the positions overlapping the eyelet  10  in the plan view, are disposed within a thickness range of the metal base  60  in a side view. That is, the first lead  41  and the second lead  42  located at the positions overlapping the eyelet  10  in the plan view, are disposed closer to the eyelet  10  than to a lower surface  60   b  of the metal base  60  in the side view. The side view of an object refers to a view of the object viewed in a direction strictly parallel to the upper surface  10   a  of the eyelet  10 . 
     Portions of the first lead  41  and the second lead  42  that do not overlap the eyelet  10  in the plan view, may be located below the lower surface  60   b  of the metal base  60  in the side view. For example, portions of the first lead  41  and the second lead  42  protruding from the side surface of the eyelet  10  in the plan view, may be located below the lower surface  60   b  of the metal base  60 . 
     A thickness of the metal base  60  can be appropriately determined within a range thicker than the diameters of the first lead  41  and the second lead  42 , and can be set in a range of approximately 0.5 mm to approximately 3 mm, for example. The thickness of the metal base  60  may be greater or smaller than the thickness of the eyelet  10 . A thermal conductivity of the metal base  60  is higher than or equal to a thermal conductivity of the eyelet  10 . For example, in a case where the material used for the eyelet  10  is iron, the material used for the metal base  60  may be copper having higher thermal conductivity than that of the eyelet  10 . In this case, it is possible to improve a heat dissipation performance of the semiconductor package header  1 . 
     In the case where the material used for the metal base  60  is copper, the metal base  60  is preferably not disposed at the outer periphery of the lower surface  10   b  of the eyelet  10 . In other words, the outer periphery of the lower surface  10   b  of the eyelet  10  is preferably exposed from the metal base  60 . When manufacturing a semiconductor package using the semiconductor package header  1 , a cap may be welded to the outer periphery of the upper surface  10   a  of the eyelet  10 . The outer periphery of the lower surface  10   b  of the eyelet  10  is used as a portion for receiving a tool that fixes the eyelet  10 , and if the copper is present at the outer periphery of the lower surface  10   b  of the eyelet  10 , the copper, which is soft, may become deformed during the welding of the cap. 
     However, when not using a cap similar to the conventional cap described above, the metal base  60  may be disposed on the outer periphery of the lower surface  10   b  of the eyelet  10 , and the metal base  60  may protrude outside the eyelet  10  in the plan view. In these cases, it is possible to improve the heat dissipation performance of the semiconductor package header  1 , because a volume of the metal base  60  increases. 
     In a case where the material used for the eyelet  10  is iron, the material used for the metal base  60  may be iron. In the case where the eyelet  10  and the metal base  60  are formed of the same material as described above, the thermal expansion coefficients of the eyelet  10  and the metal base  60  become the same. For this reason, deformation of the eyelet  10  and the metal base  60  caused by heat can be reduced, and it is possible to improve a hermetic seal of the semiconductor package when manufacturing the semiconductor package in which the semiconductor device is mounted on the semiconductor package header  1 . 
     The metal base  60  may be formed integrally with the metal block  30 . 
       FIG.  4   , and  FIG.  5 A  through  FIG.  5 C  are diagrams illustrating manufacturing processes of the header for the semiconductor package according to the first embodiment. 
     In order to manufacture the semiconductor package header  1 , first, as illustrated in  FIG.  4   , the metal block  30 , provided with the pedestal  31 , and the columnar part  32  protruding from the pedestal  31 , is formed (or prepared).The metal block  30  may be formed (or prepared) by forming a rod-shaped material into a predetermined shape by a drawing process, and cutting the material having the predetermined shape by a singulating process. The singulated material becomes the pedestal  31  and the columnar part  32 . Thereafter, a forming process is performed on each singulated material using a die. More particularly, with respect to each singulated material, the forming process presses a periphery of a portion of each singulated material, which becomes the columnar part  32 , using the die, and a planarizing process is performed to planarize a portion of the columnar part  32 , which becomes the device mounting surface  30   r . Hence, the pressed portion becomes smaller than the non-pressed portion. In other words, the pressed portion becomes the columnar part  32 , the non-pressed portion becomes the pedestal  31 , thereby completing the shape illustrated in  FIG.  4   . In the plan view, the outer periphery of the pedestal  31  is exposed around the columnar part  32 . In the present specification, a “flat surface” refers to a surface having a maximum flatness of approximately 0.005 mm. In  FIG.  4   , a flat portion of the device mounting surface  30   r  is indicated by a dot pattern. 
     Next, as illustrated in  FIG.  5 A , the eyelet  10 , having the through hole  10   x , and the through holes  10   y  for inserting the first lead  41  and the second lead  42 , penetrating the eyelet  10  from the upper surface  10   a  to the lower surface  10   b , is formed (or prepared) by a stamping process or the like. Then, the first lead  41  and the second lead  42 , that are bent in advance to a predetermined shape, are inserted into the through holes  10   y  of the eyelet  10 , and the peripheries of the first lead  41  and the second lead  42  are sealed by the sealer  50  inside the through holes  10   y . Alternatively, the first lead  41  and the second lead  42 , that are not bent, may be inserted into the through holes  10   y  of the eyelet  10 , the peripheries of the first lead  41  and the second lead  42  may be sealed by the sealer  50  inside the through holes  10   y , before bending the first lead  41  and the second lead  42  to the predetermined shape. 
     Next, as illustrated in  FIG.  5 B , a metal bonding material (not illustrated) is disposed on an upper surface  60   a  of the metal base  60 , and further, the structure illustrated in  FIG.  5 A  is disposed on the metal bonding material. Then, the pedestal  31  of the metal block  30  is inserted into the through hole  10   x  of the eyelet  10 , and disposed so that at least a portion of the columnar part  32  protrudes from the upper surface  10   a  of the eyelet  10 . The lower surface  30   b  of the metal block  30  makes contact with the metal bonding material. 
     Next, as illustrated in  FIG.  5 C , the metal bonding material is heated to a temperature higher than a melting point of the metal bonding material, to melt the metal bonding material and thereafter solidify the metal bonding material. In this state, the eyelet  10  and the metal block  30  may be pressed toward the metal base  60 . Because the metal bonding material melts and becomes thin to a substantially uniform thickness, the lower surface  30   b  of the metal block  30  and the lower surface  10   b  of the eyelet  10  approximately coincide. In addition, a portion of the melted metal bonding material enters a gap between a side surface of the pedestal  31  (that is, a portion of a side surface  30   c  of the metal block  30 ) and an inner wall surface  10   c  of the through hole  10   x  of the eyelet  10  due to capillary action, and solidifies in a state filling this gap. Hence, the eyelet  10 , the metal base  60 , and the metal block  30  are bonded. 
     Accordingly, the lower surface  30   b  of the metal block  30  is bonded to the upper surface  60   a  of the metal base  60  by the metal bonding material, and the side surface  30   c  of the metal block  30  is bonded to the inner wall surface  10   c  of the through hole  10   x  of the eyelet  10  by the metal bonding material. Moreover, the lower surface  10   b  of the eyelet  10  is bonded to the upper surface  60   a  of the metal base  60  by the metal bonding material. As a result, the semiconductor package header  1  is completed. 
     The process of manufacturing the semiconductor package, having the semiconductor device mounted on the semiconductor package header  1 , may include a heating process of heating the semiconductor package to approximately 300° C. For this reason, a material used for the metal bonding material which bonds the eyelet  10 , the metal base  60 , and the metal block  30 , preferably has a melting point of 350° C. or higher. For example, a silver solder having a melting point of approximately 800° C. may be used for the metal bonding material. 
     As described above, in the semiconductor package header  1 , the first lead  41  and the second lead  42  are bent at the lower surface  10   b  of the eyelet  10 , and protrude from the side surface of the eyelet  10  in the plan view. In addition, the first lead  41  and the second lead  42 , that are located at positions overlapping the eyelet  10  in the plan view, are disposed within the thickness range of the metal base  60  in the side view. 
     Accordingly, when disposing a heat sink, such as a heat spreader or the like, on the lower surface  60   b  of the metal base  60 , it becomes unnecessary to form holes in the heat spreader or the like for passing through the first lead  41  and the second lead  42 . As a result, the heat sink, such as the heat spreader or the like, can easily be disposed on the lower surface  10   b  of the eyelet  10 . In addition, it is possible to improve the heat dissipation performance, because a contact area between the lower surface  60   b  of the metal base  60  and the heat sink, such as the heat spreader or the like, can be increased. 
     The semiconductor package header  1  may include a single lead, or may include three or more leads. 
       FIG.  6    is perspective view illustrating an example of a state of use of the header for the semiconductor package. The first lead  41  and the second lead  42  of the semiconductor package header  1  illustrated in  FIG.  6    are inserted into a socket  100 . The socket  100  can be mounted on a wiring board, for example. By connecting the semiconductor package header  1  to the socket  100 , it becomes possible to easily replace the semiconductor package header  1 . 
     In the semiconductor package header  1 , the first lead  41  and the second lead  42  protrude from the side surface of the eyelet  10 . Hence, tips of the first lead  41  and the second lead  42  can be visually recognized when viewing the upper surface  10   a  of the eyelet  10 . For this reason, it is possible to easily connect the first lead  41  and the second lead  42  to the socket  100 , connect the first lead  41  and the second lead  42  to wirings by solder, or the like. 
     Moreover, the semiconductor package header  1  has a configuration in which the metal block  30  including the pedestal  31  and the columnar part  32  protruding from the pedestal  31  is manufactured in advance, and the pedestal  31  is inserted into the through hole  10   x  of the eyelet  10  so that a portion of the columnar part  32  protrudes from the upper surface  10   a  of the eyelet  10 . As a result, it is possible to obtain the semiconductor package header  1  capable of securing a sufficiently large area for the flat region of the device mounting surface  30   r . In addition, it is possible to solve the problem of cracks being generated in the sealer  50 . Further, as illustrated in  FIG.  3   , in a case where the device mounting surface  30   r  is formed to a position below the upper surface  10   a  of the eyelet  10 , it is possible to secure an even larger area for the flat region of the device mounting surface  30   r . 
     In the semiconductor package header  1 , the metal base  60  having the thermal conductivity higher than or equal to that of the eyelet  10  is bonded to the lower surface  10   b  of the eyelet  10 , so as to cover and close one end of the through hole  10   x . One end (or the lower surface  30   b ) of the metal block  30  is inserted into the through hole  10   x , and bonded to the metal base  60  inside the through hole  10   x . On the other hand, the other end (or the upper surface  30   a ) of the metal block  30  protrudes from the upper surface  10   a  of the eyelet  10 . Further, the lower surface  30   b  of the metal block  30  approximately coincides with the lower surface  10   b  of the eyelet  10 . 
     According to the configuration of the semiconductor package header  1  described above, the lower surface  30   b  of the metal block  30  can be disposed to a position close to the metal base  60  that functions as the heat sink, when mounting the semiconductor device on the device mounting surface  30   r  of the metal block  30 . Moreover, by inserting the metal block  30  into the through hole  10   x , it is possible to increase the volume of the metal block  30 . As a result, it is possible to improve the heat dissipation performance of the semiconductor package header  1 . 
     Accordingly to each of the embodiments described above, it is possible to provide a header for a semiconductor package that enables a heat sink to be easily disposed on a lower surface of an eyelet. 
     All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.