Patent Publication Number: US-2023135950-A1

Title: Semiconductor storage device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2021-180483, filed Nov. 4, 2021, the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate generally to a semiconductor storage device. 
     BACKGROUND 
     A semiconductor storage device that includes a nonvolatile memory and a memory controller for controlling the nonvolatile memory can be mounted on a printed circuit board. A capacitor for supplying power to the nonvolatile memory and the memory controller may also be mounted on the same printed circuit board. 
     A size and a weight of the capacitor are larger than those of the nonvolatile memory and the memory controller configured as, for example, a semiconductor package. Therefore, how to mount the capacitor on the printed circuit board may raise issues. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a block diagram showing an example of a functional configuration of a semiconductor storage device, which is connected to a host, according to an embodiment. 
         FIGS.  2 A,  2 B, and  2 C  are diagrams showing an example of a physical configuration of the semiconductor storage device according to the embodiment. 
         FIGS.  3 A and  3 B  are diagrams showing an example of a physical configuration of a semiconductor storage device according to a first modification of the embodiment. 
         FIGS.  4 A and  4 B  are diagrams showing an example of a physical configuration of a semiconductor storage device according to a second modification of the embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments provide a semiconductor storage device in which a capacitor is mounted compactly at low cost. 
     In general, according to one embodiment, a semiconductor storage device includes: a printed circuit board; a nonvolatile memory disposed on the printed circuit board; a memory controller disposed on the printed circuit board and configured to operatively control the nonvolatile memory; a capacitor disposed on the printed circuit board and configured to supply power to the nonvolatile memory and the memory controller; and at least one holder that holds the capacitor at an end portion of the printed circuit board. The holder includes a connecting portion connected to the end portion of the printed circuit board, and a pair of arm portions extending from the connecting portion toward an outside of the printed circuit board and configured to sandwich a body portion of the capacitor from both sides in a thickness direction of the printed circuit board. 
     Hereinafter, an embodiment will be described in detail with reference to the drawings. The present disclosure is not limited to the following embodiment. Components in the following embodiment include those that can be easily conceived by those skilled in the art or those that are substantially the same. 
     Functional Configuration Example of Semiconductor Storage Device 
       FIG.  1    is an example of a functional configuration of a semiconductor storage device  1  according to an embodiment, and is a block diagram showing the semiconductor storage device  1  connected to a host. As shown in  FIG.  1   , the semiconductor storage device  1  includes a memory controller  10 , a nonvolatile memory  20 , and a capacitor  30 . 
     The semiconductor storage device  1  is, for example, a solid state drive (SSD) in which the memory controller  10  and the nonvolatile memory  20  are configured as one or a plurality of semiconductor packages. The semiconductor storage device  1  can be connected to a host HST. The host HST may be, for example, an information processing device such as a personal computer, a server, or a storage box. The host HST may be a mobile terminal such as a mobile phone, a tablet computer, or a smartphone. The host HST may be an imaging device or a game device. The host HST may be an in-vehicle terminal such as a car navigation system. 
     The nonvolatile memory  20  stores data in a nonvolatile manner. An example of the nonvolatile memory  20  is a NAND flash memory having a two-dimensional structure or a three-dimensional structure. The nonvolatile memory  20  may be a memory other than the NAND flash memory. For example, the nonvolatile memory  20  may be any of various memory media such as a NOR flash memory, a resistance random access memory (ReRAM), and a ferroelectric random access memory (FeRAM). The nonvolatile memory  20  is unnecessarily a semiconductor memory, and various memory media other than the semiconductor memory may be used. Hereinafter, the nonvolatile memory  20  is simply referred to as a NAND memory  20 . 
     The NAND memory  20  includes a memory cell array  201 . In the memory cell array  201 , a plurality of memory cells are arranged in a matrix. Data from the host HST is stored in a nonvolatile manner in the individual memory cells of the memory cell array  201 . The memory cell array  201  includes a plurality of blocks  202  each including a plurality of memory cells. 
     As described above, the block  202  is a set of nonvolatile memory cells. The number of blocks  202  in the memory cell array  201  may be any number. In the NAND memory  20 , data is generally erased in units of the blocks  202 , and data is written and read in units of pages. 
     The NAND memory  20  may include a peripheral circuit in addition to the memory cell array  201 . The peripheral circuit includes, for example, a row decoder and a sense amplifier. The row decoder specifies an area of memory cells to be read and written. The sense amplifier senses data stored in memory cells to be read. 
     The memory controller  10  is, for example, a semiconductor integrated circuit configured as a system-on-a-chip (SoC). The memory controller  10  may be configured as a field-programmable gate array (FPGA) or an application specific integrated circuit (ASIC). 
     Functions of the memory controller  10  may be implemented by, for example, a processor that executes a program (firmware), a dedicated hardware circuit, or a combination thereof. 
     The memory controller  10  controls an operation of the NAND memory  20 . That is, the memory controller  10  controls the writing of data to the NAND memory  20  according to a write request from the host HST. The memory controller  10  controls the reading of data from the NAND memory  20  according to a read request from the host HST. 
     To implement the above functions, the memory controller  10  includes a control unit  101 , a host interface (host I/F) circuit  102 , a memory interface (memory I/F) circuit  103 , and a RAM  104 . The control unit  101 , the host I/F circuit  102 , the memory I/F circuit  103 , and the RAM  104  are connected to each other by an internal bus. 
     The host I/F circuit  102  performs processing according to an interface standard that is used to be connected with the host HST. The interface standard is, for example, serial-attached SCSI (SAS™), serial ATA (SATA™), PCI express (PCIe™) or NVM express (NVMe™). The host I/F circuit  102  outputs, to the internal bus, a request received from the host HST, data to be written (user data), and the like. The host I/F circuit  102  transmits, to the host HST, read data (user data) from the NAND memory  20 , a response from the control unit  101 , and the like. 
     The memory I/F circuit  103  exchanges various signals with the NAND memory  20  based on an instruction from the control unit  101 . The signals include, for example, a ready busy signal R/B, an input/output signal I/O, a command latch enable signal CLE, or an address latch enable signal ALE. The ready busy signal R/B indicates whether the NAND memory  20  is in a state of being able to receive a command from the memory controller  10 . The input/output signal I/O is data transmitted and received between the NAND memory  20  and the memory controller  10 . The input/output signal I/O includes a command, an address, write data, read data, and the like. The input/output signal I/O is, for example, an 8-bit width signal. The command latch enable signal CLE notifies the NAND memory  20  that the input signal I/O is a command. The address latch enable signal ALE notifies the NAND memory  20  that the input signal I/O is an address. 
     By transmitting and receiving these signals, the memory I/F circuit  103  writes data to the NAND memory  20  and erases data in the NAND memory  20  based on an instruction from the control unit  101 . The memory I/F circuit  103  reads data from the NAND memory  20  based on an instruction from the control unit  101 . 
     The control unit  101  is, for example, a central processing unit (CPU). The control unit  101  operates based on firmware. For example, the firmware is stored in the NAND memory  20  at the time of the manufacture or shipment of the semiconductor storage device  1 . When the semiconductor storage device  1  starts operation, the control unit  101  loads the firmware from the NAND memory  20  into the RAM  104  provided in the memory controller  10 . The control unit  101  implements various functions by executing the firmware loaded into the RAM  104 . 
     The control unit  101  integrally controls the components of the semiconductor storage device  1 . When the control unit  101  receives a request from the host HST via the host I/F circuit  102 , the control unit  101  performs control according to the request. For example, the control unit  101  instructs the memory I/F circuit  103  to write data to the NAND memory  20  according to a write request from the host HST. The control unit  101  instructs the memory I/F circuit  103  to read data from the NAND memory  20  according to a read request from the host HST. The control unit  101  instructs the memory I/F circuit  103  to erase data in the NAND memory  20 . 
     The RAM  104  is, for example, a general-purpose memory such as a static random access memory (SRAM) or a dynamic random access memory (DRAM). The RAM  104  is used as, for example, a work area of the control unit  101 . 
     The capacitor  30  is, for example, an aluminum electrolytic capacitor or a tantalum electrolytic capacitor having a metal thin film or the like as an electrode. For example, when power supplied from the outside is suddenly lost, the capacitor  30  maintains the power supplied to the memory controller  10  and the NAND memory  20 , That is, the capacitor  30  functions as a power loss protection (PLP) capacitor. Thus, even when the power supplied from the outside is suddenly lost, it is possible to prevent loss of data stored in the RAM  104 . 
     Physical Configuration Example of Semiconductor Storage Device 
       FIGS.  2 A,  2 B, and  2 C  are diagrams showing an example of a physical configuration of the semiconductor storage device  1  according to the embodiment.  FIG.  2 A  is a top view of the semiconductor storage device  1 .  FIG.  2 B  is a side view of the semiconductor storage device  1  as viewed from a side on which the capacitor  30  is mounted (i.e., in a direction of an arrow in  FIG.  2 A ).  FIG.  2 C  is a cross-sectional view of the semiconductor storage device  1  as viewed from one end portion of the capacitor  30 . More specifically,  FIG.  2 C  is a cross-sectional view taken along line A-A of  FIG.  2 A .  FIG.  2 C  shows, by dotted lines, lead wires  31   p  and  31   n  that are provided at the one end portion of the capacitor  30  but do not exist on the cross section. 
     As shown in  FIG.  2 A , the semiconductor storage device  1  includes the memory controller  10 , the NAND memory  20 , the capacitor  30 , a substrate (e.g., a printed circuit board (PCB))  40 , and a plurality of holders  50 . 
     The memory controller  10  and the NAND memory  20  are each accommodated in a semiconductor package having electrodes (not shown) and mounted on the printed circuit board  40 . The electrodes of the memory controller  10  and the NAND memory  20  are electrically connected to terminals (not shown) of the printed circuit board  40 , respectively. 
     The number of memory controllers  10  and the number of NAND memories  20  to be mounted on the printed circuit board  40  are not limited to the example of  FIGS.  2 A,  2 B, and  2 C . For example, a plurality of NAND memories  20  may be mounted on the printed circuit board  40 . A plurality of memory controllers  10  may be mounted on the printed circuit board  40  so as to correspond to the NAND memories  20  in a one-to-one or many-to-one manner, for example. In this case, at least one of the memory controllers  10  and at least one of the NAND memories  20  may be mounted on both surfaces of the printed circuit board  40 , respectively. 
     The capacitor  30  has, for example, a cylindrical shape. The positive lead wire  31   p  and the negative lead wire  31   n  protrude from the one end portion of the capacitor  30  in an extending direction. The lead wires  31   p  and  31   n  are provided separately from each other on a diameter of the end portion of the capacitor  30  having a circular shape. 
     However, the capacitor  30  may not have a cylindrical shape. The capacitor  30  may have, for example, an elliptic cylindrical shape or a rectangular parallelepiped shape. One of the lead wires  31   p  and  31   n  of the capacitor  30  may be provided at one end portion in the extending direction of the capacitor  30 , and the other of the lead wires  31   p  and  31   n  may be provided at the other end portion in the extending direction of the capacitor  30 . In this case, the lead wires  31   p  and  31   n  may be provided at the center positions of the two end portions of the capacitor  30 , respectively. 
     In addition, the length of the capacitor  30  in the extending direction, the length of the capacitor  30  in a direction intersecting the extending direction, and the like may vary depending on a type of the capacitor  30 , an amount of electric power that the capacitor  30  can store, and the like. Hereinafter, the length of the capacitor  30  in the extending direction may be referred to as a length of a body portion of the capacitor  30 , and the length of the capacitor  30  in the direction intersecting the extending direction may be referred to as a thickness of the body portion of the capacitor  30 . 
     As will be described later, the capacitor  30  is held by the plurality of holders  50  and mounted on the printed circuit board  40 . 
     The printed circuit board  40  is a board on which the memory controller  10 , the NAND memory  20 , and the capacitor  30  are mounted. The printed circuit board  40  has a substantially rectangular flat plate shape. One of the four sides of the printed circuit board  40  is provided with a recess portion  40   r  having a size capable of holding the capacitor  30  in a rectangular region of the printed circuit board  40 . 
     In other words, the size of the recess portion  40   r  may be determined based on, for example, a size of a standard capacitor or a size of the largest capacitor among the capacitors that can be used as the capacitor  30  in the semiconductor storage device  1 . 
     The recess portion  40   r  of the printed circuit board  40  has a shape formed by cutting one side (referred to as a first side) of the printed circuit board  40  in a substantially rectangular shape. The recess portion  40   r  includes an edge portion  40   d  extending in the same direction as a direction in which the first side extends at a position inside the printed circuit board  40  from the first side, and a pair of edge portions  40   s  extending from both ends of the edge portion  40   d  toward the first side. The pair of edge portions  40   s  face each other. One of the pair of edge portions  40   s  faces one end portion of the capacitor  30  from which the lead wires  31   p  and  31   n  protrude. 
     The shape of the recess portion  40   r  is not limited to the example of  FIGS.  2 A,  2 B, and  2 C  as long as the capacitor  30  can be held in the rectangular region of the printed circuit board  40 . For example, a corner portion where the edge portions  40   d  and  40   s  intersect may have a curved surface shape or another shape. A corner portion where the edge portion  40   s  and a side (first side) of the printed circuit board  40  intersect may also have a curved surface shape or another shape. In addition, the recess portion  40   r  itself may have various shapes. 
     The printed circuit board  40  includes a plurality of terminals (not shown) on a surface thereof. The plurality of terminals include terminals  41   p,    41   n,    42   t,  and  42   b.    
     The terminals  41   p  and  41   n  are provided in the vicinity of a side facing one end portion of the capacitor  30  from which the lead wires  31   p  and  31   n  protrude, of the pair of edge portions  40   s  constituting the recess portion  40   r.  The terminals  41   p  and  41   n  are connected to the lead wires  31   p  and  31   n  of the capacitor  30  with solder balls  61 , respectively. 
     The terminals  41   p  and  41   n  are electrically connected to the memory controller  10  and the NAND memory  20  with wires (not shown) provided on the surface of the printed circuit board  40  or provided inside the printed circuit board  40 . Thus, the power from the capacitor  30  can be supplied to the memory controller  10  and the NAND memory  20 . 
     As described above, in a case where the capacitor  30  includes the lead wires  31   p  and  31   n  at the respective two end portions, the terminal  41   p  is provided in the vicinity of one of the pair of edge portions  40   s,  and the terminal  41   n  is provided in the vicinity of the other of the pair of edge portions  40   s.  In this case, the capacitor  30  is mounted on the printed circuit board  40  such that the positions of the lead wires  31   p  and  31   n  on the two end portions of the capacitor  30  match the arrangement of the terminals  41   p  and  41   n.    
     The terminals  42   t  and  42   b  are dummy terminals that are in an electrically floating state. As shown in  FIG.  2 C , the terminals  42   t  and  42   b  are respectively provided on both surfaces of the printed circuit board  40  in the vicinity of the edge portion  40   d  constituting the recess portion  40   r.  The terminals  42   t  and  42   b  are connected to a connecting portion  51  of the holder  50  with solder balls  62 , respectively. That is, at least the same number of a plurality of pairs of terminals  42   t  and  42   b  as the number of holders  50  are arranged along the edge portion  40   d  of the printed circuit board  40 . 
     Other terminals (not shown) are appropriately disposed at predetermined positions on the surface of the printed circuit board  40 , and connected to, for example, electrodes (not shown) of the memory controller  10  and the NAND memory  20 . Electronic components other than the memory controller  10 , the NAND memory  20 , and the capacitor  30  described above may be mounted on the printed circuit board  40 . In this case, terminals (not shown) of the printed circuit board  40  are electrically connected to these electronic components, respectively. 
     A main body portion of the holder  50  is made of, for example, elastic resin. The holder  50  includes the connecting portion  51  and a pair of arm portions  52   t  and  52   b.  The main body portion of the holder  50  includes, for example, the pair of arm portions  52   t  and  52   b,  and a pair of claw portions  511   t  and  511   b  which will be described later. The main body portion of the holder  50  does not include metal covers  512   t  and  512   b  which will be described later. 
     The connecting portion  51  includes the pair of claw portions  511   t  and  511   b.  The pair of claw portions  511   t  and  511   b  are disposed at positions separated from each other in the thickness direction of the printed circuit board  40 . The claw portion  511   t  protrudes from one end of the arm portion  52   t . The claw portion  511   b  protrudes from one end of the arm portion  52   b.  The pair of claw portions  511   t  and  511   b  are covered with the metal covers  512   t  and  512   b,  respectively. The pair of claw portions  511   t  and  511   b  sandwich the edge portion  40   d  of the printed circuit board  40  from both sides in the thickness direction of the printed circuit board  40 . 
     As described above, the metal covers  512   t  and  512   b  covering the pair of claw portions  511   t  and  511   b  are respectively connected to the terminals  42   t  and  42   b  provided on both surfaces of the printed circuit board  40  in the vicinity of the edge portion  40   d  with the solder balls  62 . As described above, the terminals  42   t  and  42   b  of the printed circuit board  40  are in a floating state. Therefore, even if the metal covers  512   t  and  512   b  of the holder  50  are connected to the terminals  42   t  and  42   b,  the metal covers  512   t  and  512   b  do not affect the electrical characteristics of the printed circuit board  40 . 
     The pair of arm portions  52   t  and  52   b  are disposed at positions separated from each other in the thickness direction of the printed circuit board  40 . The pair of arm portions  52   t  and  52   b  extend from the connecting portion  51  toward a side opposite to the pair of claw portions  511   t  and  511   b.  That is, the pair of arm portions  52   t  and  52   b  extend from the edge portion  40   d  of the printed circuit board  40  toward the outside of the recess portion  40   r.    
     As shown in  FIG.  2 B , a width L 1  of the pair of arm portions  52   t  and  52   b,  that is, a length in a direction intersecting an extending direction of the pair of arm portions  52   t  and  52   b  and along the first side of the printed circuit board  40  is shorter than a length L 2  of the body portion of the capacitor  30 . 
     In the example of  FIGS.  2 A,  2 B, and  2 C , a width of the pair of claw portions  511   t  and  511   b  of the connecting portion  51  is also set to be substantially equal to the width L 1  of the pair of arm portions  52   t  and  52   b.  However, the width of the pair of claw portions  511   t  and  511   b  may not be equal to the width L 1  of the pair of arm portions  52   t  and  52   b.  For example, the width of the pair of claw portions  511   t  and  511   b  may be longer than the width L 1  of the pair of arm portions  52   t  and  52   b.  Accordingly, the holder  50  can be more firmly connected to the printed circuit board  40 . 
     As shown in  FIG.  2 C , the pair of arm portions  52   t  and  52   b  respectively include bent portions  521   t  and  521   b  in the vicinity of a substantially center portion in the extending direction. In the pair of arm portions  52   t  and  52   b,  a distance between the arm portions  52   t  and  52   b  in the thickness direction of the printed circuit board  40  is, for example, the maximum at the bent portions  521   t  and  521   b.    
     On a side closer to the connecting portion  51  than to the bent portions  521   t  and  521   b,  the distance between the pair of arm portions  52   t  and  52   b  decreases toward the connecting portion  51 . On a side farther from the connecting portion  51  than from the bent portions  521   t  and  521   b,  the distance between the pair of arm portions  52   t  and  52   b  decreases toward end portions of the pair of arm portions  52   t  and  52   b.    
     Accordingly, the pair of arm portions  52   t  and  52   b  have a substantially C-shaped cross section as shown in  FIG.  2 C . 
     With such a shape, the pair of arm portions  52   t  and  52   b  sandwich the body portion of the capacitor  30  from both sides in the thickness direction of the printed circuit board  40 . As described above, the arm portions  51   t  and  51   b  provided in the main body portion of the holder  50  are made of, for example, elastic resin. Therefore, the pair of arm portions  51   t  and  51   b  can hold the capacitor  30  by sandwiching the body portion of the capacitor  30  by elastic force. 
     The distance between the pair of arm portions  52   t  and  52   b  in the thickness direction of the printed circuit board  40  may be set based on, for example, the thickness of the body portion of a standard capacitor or the thickness of the body portion of the smallest capacitor among the capacitors that can be used as the capacitor  30  in the semiconductor storage device  1 . 
     As long as the body portion of the capacitor  30  can be sandwiched by elastic force, the shapes of the pair of arm portions  52   t  and  52   b  are not limited to the example shown in  FIGS.  2 A,  2 B, and  2 C . In the example of  FIGS.  2 A,  2 B, and  2 C , each of the pair of arm portions  52   t  and  52   b  has substantially the same length, but one of the arm portions  52   t  and  52   b  may be longer than the other of the arm portions  52   t  and  52   b.  Further, at least one of the pair of arm portions  52   t  and  52   b  may include the plurality of bent portions  521   t  and  521   b.  Alternatively, at least one of the pair of arm portions  52   t  and  52   b  may have a smooth arc shape partially or entirely. In addition, the pair of arm portions  52   t  and  52   b  may have various shapes. The shapes of the pair of arm portions  52   t  and  52   b  may be the same or different from each other. 
     The plurality of holders  50  configured as described above are provided on the printed circuit board  40  at predetermined intervals along the edge portion  40   d  of the recess portion  40   r . Thus, the capacitor  30  is held in the recess portion  40   r  of the printed circuit board  40  by the plurality of holders  50  such that the extending direction of the capacitor  30  is along the extending direction of the edge portion  40   d.    
     In the example of  FIGS.  2 A,  2 B, and  2 C , two holders  50  are provided on the printed circuit board  40  to hold the capacitor  30 . However, the number of holders  50  may be three or more, and may be one as long as the capacitor  30  can be reliably held. 
     As described above, the number of holders  50  may be appropriately selected depending on, for example, a size or a weight of the capacitor  30 . Alternatively, in accordance with the length of the body portion of the largest capacitor among the capacitors that can be used as the capacitor  30  in the semiconductor storage device  1 , as many holders  50  as required may be provided on the printed circuit board  40 . In this case, when the capacitor  30  having a shorter body portion than the largest capacitor is held, one or more holders  50  among the plurality of holders  50  may not hold the capacitor  30 . 
     When the capacitor  30  is held on the printed circuit board  40  as described above, the lead wires  31   p  and  31   n  at the end portion of the capacitor  30  face the edge portion  40   s  of the printed circuit board  40  on which the terminals  41   p  and  41   n  are provided. Accordingly, the lead wires  31   p  and  31   n  of the capacitor  30  and the terminals  41   p  and  41   n  of the printed circuit board  40  can be easily connected to each other with the solder balls  61 , respectively. 
     Here, as shown in  FIG.  2 C , the holder  50  holds the capacitor  30  such that, for example, a center axis of the capacitor  30 , that is, a center position in the thickness direction of the body portion of the capacitor  30 , and a center position in the thickness direction of the printed circuit board  40  substantially coincide with each other in the thickness direction of the printed circuit board  40 . Therefore, the lead wires  31   p  and  31   n,  which are provided on a line passing through the center position in the thickness direction of the body portion of the capacitor  30 , and the terminals  41   p  and  41   n , which are provided on the surface of the printed circuit board  40 , are disposed at positions slightly shifted from each other in the thickness direction of the printed circuit board  40 . 
     Therefore, as shown in  FIG.  2 B , when the lead wires  31   p  and  31   n  of the capacitor  30  are connected to the terminals  41   p  and  41   n  of the printed circuit board  40 , the lead wires  31   p  and  31   n  are slightly bent in the thickness direction of the printed circuit board  40 . Thus, distal end portions of the lead wires  31   p  and  31   n  are aligned with the positions of the terminals  41   p  and  41   n  in the thickness direction of the printed circuit board  40 . 
     At this time, the lead wires  31   p  and  31   n  are preferably bent at positions as close as possible to the body portion of the capacitor  30 . This enables the capacitor  30  to be mounted on the printed circuit board  40  more compactly, and the semiconductor storage device  1  can be downsized. 
     As described above, the plurality of holders  50  hold the capacitor  30  in the recess portion  40   r  of the printed circuit board  40 . The lead wires  31   p  and  31   n  of the capacitor  30  are connected to the terminals  41   p  and  41   n  of the printed circuit board  40 , so that the capacitor  30  is mounted on the printed circuit board  40 . 
     That is, when mounting the capacitor  30  on the printed circuit board  40 , the plurality of holders  50  are soldered to the printed circuit board  40  in advance. After the capacitor  30  is mounted so as to be sandwiched between the arm portions  52   t  and  52   b  of the holders  50 , the lead wires  31   p  and  31   n  of the capacitor  30  are soldered to the terminals  41   p  and  41   n  of the printed circuit board  40 , respectively. 
     The holder  50  can be manufactured by injection molding using a mold, for example. That is, a manufacturer prepares a mold having a cavity of the shape of the main body portion of the holder  50 . Then, the manufacturer injects resin into the cavity of the mold and solidifies the resin. 
     Meanwhile, the manufacturer manufactures the metal cover  512   t  having an insertion hole for the claw portion  511   t  and the metal cover  512   b  having an insertion hole for the claw portion  511   b,  and inserts the claw portions  511   t  and  511   b  into the metal covers  512   t  and  512   b,  respectively. The claw portions  511   t  and  511   b  may have the same shape. In this case, the manufacturer can manufacture a pair of metal covers having the same shape, and can fit one of the metal covers into the claw portion  511   t  and fit the other of the metal covers into the claw portion  511   b.    
     As described above, the manufacturer can manufacture the holder  50  of the embodiment. 
     Comparative Example 
     In a semiconductor storage device according to a comparative example, a dedicated socket corresponding to a size of a capacitor is attached onto a surface of a printed circuit board, and the capacitor is mounted in a state of being laid down on the socket. The socket has, for example, a recess portion larger than the body portion of the capacitor, and a terminal is provided on a side wall on one end portion of the recess portion. When the capacitor is fitted into the recess portion of the socket, a lead wire of the capacitor and the terminal of the socket are connected to each other. 
     However, in the configuration according to the comparative example, it is necessary to manufacture a socket for each capacitor in accordance with the size of the capacitor, which increases the cost of the semiconductor storage device. Since the capacitor is mounted on the printed circuit board in a state of being laid down horizontally, an area for mounting various electronic components on the printed circuit board is reduced. A degree of freedom in the arrangement of these electronic components on the printed circuit board is also limited. 
     According to the semiconductor storage device  1  of the embodiment, the holder  50  includes the pair of arm portions  52   t  and  52   b  that extend from the connecting portion  51  connected to an end portion of the printed circuit board  40  toward the outside of the printed circuit board  40  and sandwich the body portion of the capacitor  30  from both sides in the thickness direction of the printed circuit board  40  by elastic force. 
     Since the holder  50  sandwiches and holds the capacitor  30  from both sides in the thickness direction of the printed circuit board  40 , the holder  50  can hold various capacitors  30  having different lengths of the body portion. Since the holder  50  sandwiches and holds the capacitor  30  by elastic force, the holder  50  can also hold various capacitors  30  having different thicknesses of the body portion. Accordingly, it is not necessary to manufacture different holders  50  for each capacitor  30 , and the capacitor  30  can be mounted on the printed circuit board  40  at low cost. 
     The holder  50  holds the capacitor  30  on an outer side deviated from the surface of the printed circuit board  40 . Therefore, for example, compared to a case where the capacitor  30  is mounted on the surface of the printed circuit board  40 , it is possible to prevent a reduction in an area for mounting various electronic components on the printed circuit board  40 . That is, it is possible to improve the degree of freedom in the arrangement of various electronic components on the printed circuit board  40 . 
     As described above, with the holders  50  of the embodiment, the capacitor  30  can be mounted compactly on the printed circuit board  40  at low cost. 
     According to the semiconductor storage device  1  of the embodiment, the printed circuit board  40  includes the recess portion  40   r.  The capacitor  30  is held with the holders  50  connected to the edge portion  40   d  located on an inner side with respect to one side of the printed circuit board  40 , and is disposed in the recess portion  40   r  of the printed circuit board  40 . 
     Accordingly, an increase in an area of the entire printed circuit board  40  due to the mounting of the capacitor  30  is prevented. Therefore, it is easy to downsize the semiconductor storage device  1 . For example, as compared with a case where the capacitor  30  is mounted so as to protrude from the rectangular region of the printed circuit board  40 , the risk of vibration and impact being applied to the capacitor  30  is reduced, and the capacitor  30  can be stably held on the printed circuit board  40 . 
     According to the semiconductor storage device  1  of the embodiment, the lead wires  31   p  and  31   n  of the capacitor  30  are respectively connected to the terminals  41   p  and  41   n  disposed on the surface of the printed circuit board  40  in the vicinity of the edge portion  40   s  facing the end portion of the capacitor  30 . Accordingly, a connection distance between the lead wires  31   p  and  31   n  and the terminals  41   p  and  41   n  can be shortened, and the capacitor  30  can be mounted on the printed circuit board  40  more compactly. 
     According to the semiconductor storage device  1  of the embodiment, the width of the pair of arm portions  52   t  and  52   b  is shorter than the length of the capacitor  30  in the extending direction. The printed circuit board  40  is provided with the plurality of holders  50  at the end portion of the printed circuit board  40  so that the plurality of holders  50  are arranged in the extending direction of the capacitor  30 . 
     Accordingly, the number of holders  50  and an interval between the holders  50  can be adjusted in accordance with the length of the body portion of the capacitor  30 , which makes it easier to cope with capacitors of various sizes. By adjusting the number of holders  50  and the interval between the holders  50 , the capacitor  30  can be held more firmly and stably. 
     According to the semiconductor storage device  1  of the embodiment, the holder  50  includes the pair of claw portions  511   t  and  511   b  that sandwich the printed circuit board  40  from both sides in the thickness direction of the printed circuit board  40 . The pair of claw portions  511   t  and  511   b  sandwich and connect the printed circuit board  40  from both sides in the thickness direction, so that the holder  50  can be more firmly fixed to the printed circuit board  40 . 
     According to the semiconductor storage device  1  of the embodiment, the pair of claw portions  511   t  and  511   b  are covered with the metal covers  512   t  and  512   b,  and are connected to the end portion of the printed circuit board  40  with the solder balls  62 . Thus, by providing the metal covers  512   t  and  512   b , the pair of claw portions  511   t  and  511   b  can be connected to the dummy terminals  42   t  and  42   b  of the printed circuit board  40  with the solder balls  62 . Thus, the holder  50  can be more firmly fixed to the printed circuit board  40 . 
     In the semiconductor storage device  1  of the above embodiment, the connecting portion  51  of the holder  50  is connected to the end portion of the printed circuit board  40  with the solder balls  62 . However, the connecting portion  51  may be connected to the end portion of the printed circuit board  40  with an adhesive or the like. In this case, the holder  50  may not include the metal covers  512   t  and  512   b,  and the pair of claw portions  511   t  and  511   b  may be directly connected to the printed circuit board  40  with the adhesive. In this case, the dummy terminals  42   t  and  42   b  of the printed circuit board  40  may not be provided. 
     First Modification 
     Next, a semiconductor storage device  2  according to a first modification of the embodiment will be described with reference to  FIGS.  3 A and  3 B . In the semiconductor storage device  2  of the first modification, a holding position of the capacitor  30  with respect to the printed circuit board  40  is different from that of the semiconductor storage device  1  of the above embodiment. 
       FIGS.  3 A and  3 B  are diagrams showing an example of a physical configuration of the semiconductor storage device  2  according to the first modification of the embodiment.  FIG.  3 A  is a side view of the semiconductor storage device  2  as viewed from a side on which the capacitor  30  is mounted, and is a diagram corresponding to  FIG.  2 B  of the above embodiment.  FIG.  3 B  is a cross-sectional view of the semiconductor storage device  2  as viewed from one end portion side of the capacitor  30 , and is a diagram corresponding to  FIG.  2 C  of the above embodiment. In  FIGS.  3 A and  3 B , the same components as those of the above embodiment are denoted by the same reference numerals, and the description thereof may be omitted. 
     As shown in  FIGS.  3 A and  3 B , holders  50   a  provided in the semiconductor storage device  2  of the first modification include arm portions  152   t  and  152   b  having shapes different from those of the arm portions  52   t  and  52   b  of the holder  50  of the above embodiment. That is, the pair of arm portions  152   t  and  152   b  extend from the edge portion  40   d  of the printed circuit board  40  toward the outside of the recess portion  40   r  at an angle different from that of the arm portions  52   t  and  52   b  of the embodiment. Hereinafter, the difference in shape will be described in more detail. 
     The arm portion  152   t  includes a bent portion  522   t  in the vicinity of a substantially center portion in the extending direction. The inclination from the connecting portion  51  to the bent portion  522   t  with respect to the surface of the printed circuit board  40  is steeper than the inclination of the arm portion  52   t  from the connecting portion  51  to the bent portion  521   t.  Accordingly, the bent portion  522   t  of the arm portion  152   t  is located at a position farther from the center position in the thickness direction of the printed circuit board  40  (i.e., at a position shifted upward in the drawing) than the bent portion  521   t  of the arm portion  52   t  is. 
     The arm portion  152   b  includes a bent portion  522   b  in the vicinity of a substantially center portion in the extending direction. The inclination from the connecting portion  51  to the bent portion  522   b  with respect to the surface of the printed circuit board  40  is gentler than the inclination of the arm portion  52   b  from the connecting portion  51  to the bent portion  521   b.  Accordingly, the bent portion  522   b  of the arm portion  152   b  is located at a position closer to the center position in the thickness direction of the printed circuit board  40  (i.e., at a position shifted upward in the drawing) than the bent portion  521   b  of the arm portion  52   b  is. 
     Since the pair of arm portions  152   t  and  152   b  have such a shape, the holders  50   a  of the first modification hold, in the thickness direction of the printed circuit board  40 , the capacitor  30  in a state where the center position in the thickness direction of the body portion of the capacitor  30  and the center position in the thickness direction of the printed circuit board  40  are shifted from each other. 
     More specifically, the center position in the thickness direction of the body portion of the capacitor  30  is disposed at a position shifted from the center position in the thickness direction of the printed circuit board  40  toward the surface of the printed circuit board  40  on which the terminals  41   p,    41   n , and  42   t  are mounted. Thus, the center position in the thickness direction of the body portion of the capacitor  30  is disposed at a position substantially aligned with the terminals  41   p  and  41   n  in the thickness direction of the printed circuit board  40 . 
     As described above, the lead wires  31   p  and  31   n  are provided at an end portion of the capacitor  30 , for example, on a line passing through the center position in the thickness direction of the body portion of the capacitor  30 . Accordingly, the lead wires  31   p  and  31   n  are also disposed at positions substantially aligned with the terminals  41   p  and  41   n  in the thickness direction of the printed circuit board  40 . 
     Therefore, in the semiconductor storage device  2  of the first modification, the lead wires  31   p  and  31   n  of the capacitor  30  can be connected to the terminals  41   p  and  41   n  of the printed circuit board  40  while maintaining a substantially linear state without being bent. 
     In the holder  50   a  of the first modification, a plurality of bent portions  522   t  and  522   b  may be provided, and the shapes of the pair of arm portions  152   t  and  152   b  may be made different in various ways, such as an arc shape. 
     In the example of  FIGS.  3 A and  3 B , the arm portion  152   b  is shorter than the arm portion  152   t.  Accordingly, distances from the end portion of the printed circuit board  40  to the respective distal end portions of the arm portions  152   t  and  152   b  are substantially equal to each other in the protruding direction of the arm portions  152   t  and  152   b,  that is, in a direction along the surface of the printed circuit board  40 . However, for example, lengths of the arm portions  152   t  and  152   b  may be equal to each other. That is, the distal end portion of one of the arm portions  152   t  and  152   b  may protrude from the distal end portion of the other of the arm portions  152   t  and  152   b.  Even in this case, it is preferable that both the distal end portions of the arm portions  152   t  and  152   b  are accommodated in the recess portion  40   r  of the printed circuit board  40 . 
     According to the semiconductor storage device  2  of the first modification, the holders  50   a  hold the capacitor  30  at a position where the lead wires  31   p  and  31   n  of the capacitor  30  and the terminals  41   p  and  41   n  of the printed circuit board  40  are aligned in the thickness direction of the printed circuit board  40 . 
     Accordingly, when the capacitor  30  is mounted on the printed circuit board  40 , the lead wires  31   p  and  31   n  do not need to be bent. Therefore, manufacturing processes of the semiconductor storage device  2  can be reduced, the time required for manufacturing can be shortened, and manufacturing costs can be reduced. 
     Since the capacitor  30  is mounted on the printed circuit board  40  while the lead wires  31   p  and  31   n  are substantially linear, for example, it is possible to reduce loads on the lead wires  31   p  and  31   n  due to bending. Accordingly, for example, it is possible to prevent a gap from being formed at joint portions between the lead wires  31   p  and  31   n  and the body portion of the capacitor  30 , and to prevent moisture or the like from entering the capacitor  30  through such a gap. 
     According to the semiconductor storage device  2  of the first modification, effects similar to those of the semiconductor storage device  1  of the above embodiment can be obtained. 
     Second Modification 
     Next, a semiconductor storage device  3  according to a second modification of the embodiment will be described with reference to  FIGS.  4 A and  4 B . In the semiconductor storage device  3  of the second modification, the structure of a connecting portion  151  of a holder  50   b  is different from that of the semiconductor storage device  1  of the above embodiment. 
       FIGS.  4 A and  4 B  are diagrams showing an example of a physical configuration of the semiconductor storage device  3  according to the second modification of the embodiment. More specifically,  FIGS.  4 A and  4 B  are cross-sectional views of the semiconductor storage device  3  as viewed from one end portion of the capacitor  30 , and are diagrams corresponding to  FIG.  2 C  of the above embodiment.  FIG.  4 A  shows a state in which press-contact connectors  514   t  and  514   b  of the holder  50   b  are released, and  FIG.  4 B  shows a state in which the press-contact connectors  514   t  and  514   b  are press-contacted. In  FIGS.  4 A and  4 B , the same components as those of the above embodiment are denoted by the same reference numerals, and the description thereof may be omitted. 
     As shown in  FIGS.  4 A and  4 B , the holder  50   b  of the second modification includes the connecting portion  151  including a pair of claw portions  513   t  and  513   b  and the press-contact connectors  514   t  and  514   b.  These portions are all made of, for example, resin, and the connecting portion  151  does not include the metal covers  512   t  and  512   b  as in the holder  50  of the above embodiment. Accordingly, the entire holder  50   b  of the second modification is made of, for example, resin. 
     The pair of claw portions  513   t  and  513   b  protrude toward the printed circuit board  140  at positions separated from each other in the thickness direction of the printed circuit board  140 . The press-contact connector  514   t  is provided in the vicinity of a distal end portion of the claw portion  513   t  so as to protrude from a surface of the claw portion  513   t  facing the printed circuit board  140 . The press-contact connector  514   b  is provided in the vicinity of a distal end portion of the claw portion  513   b  so as to protrude from a surface of the claw portion  513   b  facing the printed circuit board  140 . 
     That is, the press-contact connectors  514   t  and  514   b  are disposed to face each other with the printed circuit board  140  interposed therebetween. The press-contact connectors  514   t  and  514   b  mesh with each other by being fastened with pliers or the like. Of the press-contact connectors  514   t  and  514   b,  the press-contact connector  514   t  is a receiving connector, and the press-contact connector  514   b  is an inserting connector. 
     However, the arrangement of the press-contact connectors  514   t  and  514   b  may be reversed. For example, the inserting press-contact connector may be provided in the claw portion  513   t,  and the receiving press-contact connector may be provided in the claw portion  513   b.    
     The printed circuit board  140  of the second modification includes a through hole  140   t  in the vicinity of the edge portion  40   d.  The printed circuit board  140  may not include the terminals  42   t  and  42   b  in the vicinity of the edge portion  40   d.    
     When the holder  50   b  is connected to the printed circuit board  140 , as shown in  FIG.  4 A , the pair of claw portions  513   t  and  513   b  of the connecting portion  151  are disposed to sandwich the printed circuit board  140  from both sides in the thickness direction. As shown in  FIG.  4 B , the press-contact connectors  514   t  and  514   b  are inserted into the through hole  140   t  of the printed circuit board  140  from both sides in the thickness direction of the printed circuit board  140 , and the press-contact connector  514   b  is fitted into the press-contact connector  514   t.    
     As described above, the holder  50   b  of the second modification is pressed against the printed circuit board  140  by the press-contact connectors  514   t  and  514   b.    
     According to the semiconductor storage device  3  of the second modification, the pair of claw portions  513   t  and  513   b  are pressed against an end portion of the printed circuit board  140 . By configuring the holder  50   b  in this manner, the holder  50   b  can be easily connected to the printed circuit board  140  without undergoing a process such as soldering or the like. Since soldering or the like is not performed, the holder  50   b  can be easily detached from the printed circuit board  140  when the holder  50   b  is replaced. 
     According to the semiconductor storage device  3  of the second modification, effects similar to those of the semiconductor storage device  1  of the above embodiment can be obtained. 
     In the semiconductor storage device  3  of the second modification, the holder  50   b  may be configured to hold the capacitor  30  at a position slightly shifted from the center position in the thickness direction of the printed circuit board  140  as the holder  50   a  of the first modification. 
     In the semiconductor storage devices  1  to  3  of the above embodiment and the first and second modifications, the main body portions of the holders  50 ,  50   a,  and  50   b  are made of, for example, resin. However, a main body portion of a holder, that is, a pair of claw portions, a pair of arm portions, and the like may be made of, for example, elastic metal. 
     When the main body portion of the holder is made of metal, the holder can be connected to a printed circuit board by soldering even if the pair of claw portions of the holder do not include metal covers as in the embodiment and the first modification. That is, the metal claw portions can be directly soldered to terminals of the printed circuit board. However, even if the main body portion of the holder is made of metal, the claw portions may be connected to the printed circuit board with adhesive or the like. 
     As described above, the metal holder can also be connected to the printed circuit board by soldering or pressure contacting, or with adhesive. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure.