CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 62/271,890, filed Dec. 28, 2015, the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a storage device.

BACKGROUND

Currently, magnetic disk devices, solid-state storage drives (SSDs) and the like are used as storage devices. An SSD comprises, for example, stacked circuit boards and an enclosure accommodating these circuit boards. Memory devices such as NAND flash memories are mounted on each circuit board. A heat-producing component such as a semiconductor device is mounted on at least one of the circuit boards. Adjacent circuit boards are connected to each other via a connector. When three or more circuit boards are stacked, the space between the circuit boards becomes narrow and the heat of the heat-producing component cannot be easily dissipated. As a result, components mounted on the circuit boards are heated and the temperature rises in some cases.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an appearance of a storage device of a first embodiment.

FIG. 2 is an exploded perspective view of the storage device.

FIG. 3 is an exploded perspective view of a circuit board assembly of the storage device.

FIG. 4 is an exploded perspective view showing the circuit board assembly from the lower surface side.

FIG. 5 is a perspective view partially showing an enclosure and the circuit board assembly of the storage device.

FIG. 6 is a cross-sectional view of the storage device seen along VI-VI of FIG. 1.

FIG. 7 is an exploded perspective view partially showing a circuit board assembly of a storage device of a second embodiment.

FIG. 8 is a cross-sectional view of the storage device of the second embodiment.

DETAILED DESCRIPTION

Various embodiments will be described hereinafter with reference to the accompanying drawings. In general, according to one embodiment, a storage device comprises an enclosure, and a circuit board assembly accommodated in the enclosure. The circuit board assembly comprises a first circuit board on which a memory device and a heat-producing component are mounted; a second circuit board opposed to the first circuit board, on which a memory device is mounted; a third circuit board opposed to the second circuit board, on which a memory device is mounted; a first connector provided between the first circuit board and the second circuit board and connecting the first circuit board to the second circuit board; a second connector provided between the second circuit board and the third circuit board and connecting the second circuit board to the third circuit board; a frame-shaped first spacer sandwiched between the first circuit board and the second circuit board; and a frame-shaped second spacer sandwiched between the second circuit board and the third circuit board. The first spacer comprises a spacer frame, a partition member extending from the spacer frame and opposed to the heat-producing component with a gap between, and a thermal transfer member attached to the partition member and in contact with the first circuit board.

As a storage device, a solid-state storage drive (SSD) of an embodiment is hereinafter described in detail.

First Embodiment

FIG. 1 is a perspective view showing an appearance of an SSD of a first embodiment. FIG. 2 is an exploded perspective view of the SSD. FIG. 3 is an exploded perspective view of a circuit board assembly of the SSD. FIG. 4 is an exploded perspective view showing the circuit board assembly from the lower surface side. FIG. 5 is a perspective view partially showing an enclosure and the circuit board assembly of the SSD. FIG. 6 is a cross-sectional view of the SSD seen along VI-VI of FIG. 1.

As shown in FIG. 1, FIG. 2, FIG. 5 and FIG. 6, an SSD 10 comprises an enclosure 12 having the shape of a rectangular box and a circuit board assembly 20 accommodated in the enclosure 12. The enclosure 12 comprises a rectangular base 12a formed of aluminum, etc., and a cover 12b fixed to the base 12a. The base 12a integrally comprises a rectangular bottom wall (first wall) 14a and a pair of long-side walls 14b provided along the long sides of the bottom wall 14a. Screw holes for fixing the cover 12b are formed on the top end of each long-side wall 14b. Screw holes for fixing the circuit board assembly 20 are formed at both side edges of the bottom wall 14a. Several (for example, two) projections (bosses) 19 are formed in the center of the bottom wall 14a. The bosses 19 are located in a position opposed to a first connector 36 of the circuit board assembly 20 to be described later. As a heat-sink member, heat-sink pads or heat-sink sheets 18a having thermal transfer and cushioning characteristics are attached to the bosses 19 and several points on the inner surface of the bottom wall 14a. When the circuit board assembly 20 is accommodated in the enclosure 12, the heat-sink sheets 18a are elastically in contact with the circuit board assembly 20.

The cover 12b integrally comprises a rectangular top plate (second wall) 15a and a pair of side plates 15b provided along the short sides of the top plate 15a. The cover 12b is put on the base 12a and fixed to the base 12a by suitable fastenings, for example, six screws 13. A label 14 is attached to the top plate 15a. Recesses (projections) 17 protruding toward the base 12a side are provided on the top plate 15a. On the inner surface side of the top plate 15a, a heat sink-pad or heat-sink sheet 18b having thermal transfer and cushioning characteristics is attached to the top of each recess 17 as a heat-sink member. When the circuit board assembly 20 is accommodated in the enclosure 12, the heat-sink sheets 18b are elastically in contact with the circuit board assembly 20. For example, three of the recesses 17 (recesses 17a) are located in a position opposed to a second connector 38 of the circuit board assembly 20 to be described later.

As shown in FIG. 2 to FIG. 4 and FIG. 6, the circuit board assembly 20 comprises several (for example, three) stacked circuit boards 24a, 24b and 24c, a first spacer 26a and a second spacer 26b sandwiched between the circuit boards and a first connector 36 and a second connector 38 electrically connecting the circuit boards, which are assembled into a stack structure. More specifically, the circuit board assembly 20 comprises a rectangular first circuit board 24a formed of a rigid printed circuit board, a rectangular second circuit board 24b located above and opposed to the first circuit board 24a and a rectangular third circuit board 24c located above and opposed to the second circuit board 24b. The first to third circuit boards 24a, 24b and 24c have approximately the same external dimensions.

NAND flash memories 30a serving as memory devices, a CPU 31 serving as a controller and other semiconductor devices are mounted on a lower surface (first principal surface) of the first circuit board 24a. The CPU 31 is a heat-producing component which produces heat by operation. An interface connector 32 is mounted on one end in the longitudinal direction of the first circuit board 24a. NAND flash memories 30b serving as memory devices and other semiconductor devices are mounted on an upper surface (second principal surface) of the first circuit board 24a. A first-board-side first connector (stacking connector or board-to-board connector) 36a constituting the first connector 36 is mounted substantially in the central portion of the upper surface of the first circuit board 24a. The first-board-side first connector 36a has an elongated rectangular shape and is located such that the longitudinal direction of the first-board-side first connector 36a corresponds to the width direction of the first circuit board 24a. Two capacitors 39 are mounted on the other end of the first circuit board 24a. Through-holes 40a for inserting screws 22 are formed on the peripheral edge of the first circuit board 24a. Notches 41a engageable with tabs of the first spacer 26a are formed on the long-side edges of the first circuit board 24a.

The second circuit board 24b is located with the lower surface (first principal surface) opposed to the upper surface of the first circuit board 24a. NAND flash memories 44a serving as memory devices are mounted on the lower surface of the second circuit board 24b. A second-board-side first connector (stacking connector or board-to-board connector) 36b constituting the first connector 36 is mounted substantially in the center of the lower surface of the second circuit board 24b. The second-board-side first connector 36b has an elongated rectangular shape and is located such that the longitudinal direction of the second-board-side first connector 36b corresponds to the width direction of the second circuit board 24b. In addition, the second-board-side first connector 36b is located in a position opposed to the first-board-side first connector 36a of the first circuit board 24a. Accordingly, when the second circuit board 24b is put on the first circuit board 24a, the second-board-side first connector 36b is engaged with the first-board-side first connector 36a to form the first connector 36.

NAND flash memories 44b serving as memory devices and other semiconductor devices are mounted on an upper surface (second principal surface) of the second circuit board 24b. A second-board-side second connector (stacking connector or board-to-board connector) 38a constituting the second connector 38 is mounted substantially in the center of the upper surface of the second circuit board 24b. The second-board-side second connector 38a has an elongated rectangular shape and is located such that the longitudinal direction of the second-board-side second connector 38a corresponds to the width direction of the second circuit board 24b. The second-board-side second connector 38a is deviated, i.e., offset relative to the second-board-side first connector 36b constituting the first connector 36 in a surface direction (X-direction) of the second circuit board 24b. The offset can be arbitrarily set, for example, such that about half the width of the second-board-side second connector 38a overlaps the second-board-side first connector 36b. Since the second-board-side first connector 36b and the second-board-side second connector 38a provided on the lower surface and the upper surface of the second circuit board 24b are offset relative to each other, flexibility in connection between the connectors 36b and 38a and interconnects on the second circuit board 24b can be improved and the interconnects can be easily routed and connected.

Through-holes 40b for inserting the screws 22 are formed on the peripheral edge of the second circuit board 24b. Notches 41b engageable with tabs of the second spacer 26b are formed on the long-side ends of the second circuit board 24b.

The third circuit board 24c is located with the lower surface (first principal surface) opposed to the upper surface of the second circuit board 24b. NAND flash memories 46a serving as memory devices are mounted on the lower surface of the third circuit board 24c. A third-board-side second connector (stacking connector or board-to-board connector) 38b constituting the second connector 38 is mounted substantially in the center of the lower surface of the third circuit board 24c. The third-board-side second connector 38b has an elongated rectangular shape and is located such that the longitudinal direction of the third-board-side second connector 38b corresponds to the width direction of the third circuit board 24c. In addition, the third-board-side second connector 38b is located in a position opposed to the second-board-side second connector 38a of the second circuit board 24b. Accordingly, when the third circuit board 24c is put on the second circuit board 24b, the third-board-side second connector 38b is engaged with the second-board-side second connector 38a to form the second connector 38. In the present embodiment, connectors having dimensions smaller than those of the first connector 36 are used for the second-board-side second connector 38a and the third-board-side second connector 38b constituting the second connector 38.

NAND flash memories 46b serving as memory devices and other semiconductor devices are mounted on the upper surface (second principal surface) of the third circuit board 24c. Through-holes 40c for inserting the screws 22 are formed on the peripheral edge of the third circuit board 24c.

As shown in FIG. 3 to FIG. 6, the first spacer 26a of the circuit board assembly 20 comprises a rectangular spacer frame 50 and a substantially-rectangular partition plate 90 coupled to the spacer frame 50, which are integrally formed of, for example, synthetic resin or metal. A thermal transfer pad 92a having thermal transfer and cushioning characteristics and serving as a thermal transfer member is attached to the lower surface of the partition plate 90.

The spacer frame 50 comprises a pair of long-side portions 50a opposed to each other and a pair of short-side portions 50b opposed to each other. The thickness (height) of the spacer frame 50 is approximately equal to the space between the first circuit board 24a and the second circuit board 24b (in the case where the first connectors 36 are connected). The spacer frame 50 has approximately the same external dimensions as the first circuit board 24a. Each long-side portion 50a of the spacer frame 50 comprises a tab 51a engageable with the notch 41a of the first circuit board 24a. Through-holes 56a for inserting the screws 22 are formed at several points on the spacer frame 50. Positioning pins (not shown) engageable with the first circuit board 24a are provided at several points on the lower surface of the spacer frame 50.

The partition plate 90 serving as a partition member is coupled to one of the short-side portions 50b of the spacer frame 50 and extends from this short-side portion 50b toward the other short-side portion 50b substantially up to the center of the spacer frame 50. The partition plate 90 has a thickness less than the thickness (height) of the spacer frame 50 and a width less than the length of the short-side portion 50b. The partition plate 90 is located between the first circuit board 24a and the second circuit board 24b substantially parallel to these circuit boards. The partition plate 90 is opposed to the upper surface of the first circuit board 24a with a gap or a space between and opposed to the lower surface of the second circuit board 24b with a gap or a space between. In addition, the partition plate 90 is opposed to all or part of an area of the first circuit board 24a in which the CPU (heat-producing component) 31 is mounted.

The thermal transfer pad 92a is attached to the lower surface (surface opposed to the first circuit board 24a) of the partition plate 90 so as to be opposed to the CPU 31. When the first spacer 26a is put on the first circuit board 24a, the thermal transfer pad 92a is in contact with the upper surface (second principal surface) of the first circuit board 24a in a position opposed to the CPU 31.

The above-described partition plate 90 of the first spacer 26a shields the second circuit board 24b and the other components against radiation of heat from the CPU 31 through the first circuit board 24a. The heat of the first circuit board 24a is transferred to the partition plate 90 through the thermal transfer pad 92a, transferred from the partition plate 90 to the spacer frame 50, further transferred to the enclosure 12 through the screws 22 to be described later and dissipated from the enclosure 12 to the outside.

The second spacer 26b of the circuit board assembly 20 comprises a spacer frame 60 obtained by forming synthetic resin into a rectangular frame. The spacer frame 60 comprises a pair of long-side portions 60a opposed to each other and a pair of short-side portions 60b opposed to each other. The thickness (height) of the spacer frame 60 is approximately equal to the space between the second circuit board 24b and the third circuit board 24c (in the case where the second connectors 38 are connected). The spacer frame 60 has approximately the same external dimensions as the second circuit board 24b. Each long-side portion 60a of the spacer frame 60 comprises a tab 51b engageable with the notch 41b of the circuit board 24b. Through-holes 56b for inserting the screws 22 are formed at several points on the spacer frame 60. Positioning pins (not shown) engageable with the second circuit board 24b are provided at several points on the lower surface of the spacer frame 60.

The second spacer 26b may comprise a coupling bead (not shown) for coupling the long-side portions 60a of the spacer frame 60.

The above-described constituent members of the circuit board assembly 20 are sequentially stacked and electrically connected to each other through the first connector 36 and the second connector 38. More specifically, as shown in FIG. 2 to FIG. 6, the first spacer 26a is put on the peripheral edge of the first circuit board 24a and the tabs 51a of the spacer frame 50 are engaged with the notches 41a and the lower surface of the first circuit board 24a. The spacer frame 50 is thereby attached to the first circuit board 24a in a state of being positioned on the peripheral edge of the first circuit board 24a. The second circuit board 24b is put on the first spacer 26a and the second-board-side first connector 36b is engaged with the first-board-side first connector 36a. In this manner, the first circuit board 24a and the second circuit board 24b are electrically and mechanically connected to each other by the first connector 36. The spacer frame 50 of the first spacer 26a is sandwiched between the peripheral edge of the first circuit board 24a and the peripheral edge of the second circuit board 24b and keeps the space between the first and second circuit boards. The partition plate 90 of the first spacer 26a is located between the first circuit board 24a and the second circuit board 24b and opposed to the mounting position of the CPU 31. The thermal transfer pad 92a of the first spacer 26a is in contact with the upper surface of the first circuit board 24a in the position opposed to the CPU 31.

The second spacer 26b is put on the peripheral edge of the second circuit board 24b and the tabs 51b of the spacer frame 60 are engaged with the notches 41b and the lower surface of the second circuit board 24b. The spacer frame 60 is thereby attached to the second circuit board 24b in a state of being positioned on the peripheral edge of the second circuit board 24b. The third circuit board 24c is put on the second spacer 26b and the third-board-side second connector 38b is engaged with the second-board-side second connector 38a.

Since the third circuit board 24c is put on the second spacer 26b and the third-board-side second connector 38b is engaged with the second-board-side second connector 38a, the spacer frame 60 of the second spacer 26b is sandwiched between the peripheral edge of the second circuit board 24b and the peripheral edge of the third circuit board 24c and keeps the space between the second and third circuit boards.

As shown in FIG. 2, the circuit board assembly 20 assembled as described above is fixed to the bottom wall 14a of the base 12a by the screws 22 inserted into the through-holes 40c, 56b, 40b, 56a and 40a of the third circuit board 24c, the second spacer 26b, the second circuit board 24b, the first spacer 26a and the first circuit board 24a from the third circuit board 24c side, and the constituent members of the circuit board assembly 20 are thereby clamped to each other.

As shown in FIG. 1 and FIG. 6, the lower surface of the first circuit board 24a of the circuit board assembly 20 fixed to the base 12a is opposed to the bottom wall 14a of the base 12a with narrow space between. The CPU 31 and the NAND flash memories 30a mounted on the first circuit board 24a are in contact with the base 12a through the heat-sink sheets 18a. Of the first circuit board 24a, the back surface of a portion equipped with the first connector 36 is in contact with the bottom wall 14a of the base 12a through the heat-sink sheets 18a.

The third circuit board 24c of the circuit board assembly 20 is opposed to the top plate 15a of the cover 12b with narrow space between. The NAND flash memories 46b mounted on the third circuit board 24c are in contact with the recesses 17 of the top plate 15a through the heat-sink sheets 18b. Of the third circuit board 24c, the back surface of a portion equipped with the second connector 38 is in contact with the recesses 17a of the top plate 15a through the heat-sink sheets 18b.

The interface connector 32 mounted on the first circuit board 24a is exposed to the outside through an opening of the enclosure 12.

According to the first embodiment, a high-capacity SSD can be realized by using a circuit board assembly in which three circuit boards are stacked. In addition, since the partition plate 90 is provided on the first spacer 26a to face a heat-producing component and a thermal transfer member is provided on the partition plate to touch the first circuit board 24a, the partition plate can shield against radiation of heat of the heat-producing component and the heat of the heat-producing component can be transferred to the first circuit board, the thermal transfer member, the partition plate and the spacer frame and dissipated. The first to third circuit boards, the components mounted thereon and the heat-producing component can be thereby prevented from temperature increase and the reliability of the SSD can be improved. The temperature increase can be prevented at low cost by integrating the partition plate and the thermal transfer member with the spacer.

Since a portion of the circuit board assembly 20 equipped with the first and second connectors 36 and 38 is supported by the recesses (projections) 17a, the heat-sink sheets 18b, the bosses 19 and the heat-sink sheets 18a from both the base 12a side and the cover 12b side of the enclosure 12, the first and second connectors 36 and 38 can be strongly kept engaged with each other and the shock resistance of the SSD can be improved.

Next, an SSD of another embodiment is described. In the embodiment described below, elements equivalent to those of the first embodiment are represented by the same reference numbers and their detailed description is omitted. Differences from the first embodiment are mainly described in detail.

Second Embodiment

FIG. 7 is an exploded perspective view partially showing a circuit board assembly of an SSD of the second embodiment. FIG. 8 is a cross-sectional view of the SSD of the second embodiment.

As shown in FIG. 7 and FIG. 8, according to the second embodiment, a first spacer 26a of a circuit board assembly 20 comprises a rectangular spacer frame 50, an elongated partition beam 94 serving as a partition member, a support beam 52 coupled to the spacer frame 50 and several (for example, three) support posts 54 provided in the support beam 52, which are integrally formed of synthetic resin or metal. The support beam 52 is provided between a pair of long-side portions 50a of the spacer frame 50 and is coupled to these long-side portions 50a. The thickness of the support beam 52 is less than that of the spacer frame 50.

The three support posts 54 are provided orthogonal to the support beam 52 and spaced out in the longitudinal direction of the support beam 52. The three support posts 54 are located in a position opposed to the second connector 38 with a second circuit board 24b between. Each support post 54 has approximately the same height as the thickness of the spacer frame 50. The upper and lower ends of each support post 54 can be in contact with the first circuit board 24a and the second circuit board 24b, respectively. The three support posts 54 constitute a support body which supports the second connector 38. The support posts 54 are coupled to the spacer frame 50 through the support beam 52 and supported by the support beam 52.

The partition beam 94 is provided between the support beam 52 and the short-side portion 50b of the spacer frame 50 and extends in the longitudinal direction of the spacer frame 50. The ends of the partition beam 94 are coupled to the short-side portion 50b and the support beam 52, respectively. The thickness of the partition beam 94 is less than that of the spacer frame 50. Accordingly, the partition beam 94 is opposed to each of the first circuit board 24a and the second circuit board 24b with narrow space between. At least part of the partition beam 94 is opposed to an area of the first circuit board 24a equipped with a CPU 31 (heat-producing component).

The first spacer 26a further comprises a first thermal transfer pad 92a attached to a lower surface (surface opposed to the first circuit board 24a) of the partition beam 94 and a second thermal transfer pad 92b attached to an upper surface (surface opposed to the second circuit board 24b) of the partition beam 94. The first thermal transfer pad 92a is in contact with the upper surface of the first circuit board 24a in a position opposed to the CPU 31. The second thermal transfer pad 92b is located on the opposite side of the first thermal transfer pad 92a and in contact with the lower surface of the second circuit board 24b.

The other elements of the circuit board assembly 20 and the SSD of the second embodiment are the same as those of the SSD of the first embodiment.

According to the second embodiment, since a partition beam 94 is provided in a spacer to face a heat-producing component and a thermal transfer member is provided on the partition beam 94 to touch the first circuit board 24a, the partition beam 94 can partially shield against radiation of heat of the heat-producing component and the heat of the heat-producing component can be transferred to the first circuit board 24a, the thermal transfer member, the partition beam and the spacer frame and dissipated. The first and second circuit boards, the components mounted thereon and the heat-producing component can be thereby prevented from temperature increase and the reliability of the SSD can be improved. Since the spacer comprising a support body for supporting connectors is provided between the circuit boards, the connectors can be prevented from being imperfectly engaged and the ease of assembly and the reliability can be improved. The temperature increase can be prevented and the connectors can be supported at low cost by integrating the supporting member and the thermal transfer member with the spacer.

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 inventions. 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 inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.

For example, the shape of the partition member of the spacer is not limited to a plate or a beam and various shapes can be adopted. The support body of the spacer is not limited to support posts and may have various shapes. The number of the circuit boards of the circuit board assembly is not limited to three and four or more circuit boards may be stacked.