Plate member and method for manufacturing a plate member

Abstract

The present invention provides a plate member and a method for manufacturing the plate member that can suppress the progression of erosion in the part of a casting mold that forms a mark. [Solution] A plate member 4 constituting part of a semiconductor memory device comprises a main body 41 which is a rectangular plate-shaped casting, and a mark M having an uneven structure integrally formed on the surface of the main body 41. The main body 41 includes a pair of edges 45A extending in the Y direction and a pair of edges 45B extending in the X direction. The edges 45A include a projection 46 projecting to the positive side in the X direction. The surface is divided into a first region 48 and a pair of second regions 49, 49 by two imaginary lines L that pass through both ends 46b, 46b in the Y direction of the edges 45A and extend parallel to the X direction. The mark M is located in at least one of the pair of second regions 49, 49, in a section 49a that is at least 1 / 3 of the width W of the main body 41 along the X direction and away from the edges 45A on the negative side in the X direction.

Description

Technical Field

[0001] The present invention relates to a plate member and a method for manufacturing a plate member.

Background Art

[0002] In recent years, demand for nearline storage has been increasing, and the trend toward larger capacity and lower power consumption is growing. Under such circumstances, hard disk drives (HDDs) are becoming mainstream as storage media (see Patent Document 1).

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] On the other hand, as a storage device for nearline storage, semiconductor storage devices (so-called SSDs) have also attracted attention. A cast aluminum alloy product may be used for the housing of a semiconductor storage device. In accordance with this, there is also a demand for producing a cover member (hereinafter referred to as "cover") by casting.

[0005] Additionally, markings are sometimes applied to the housing of semiconductor storage devices for quality control purposes. The mark formed by marking is a concavo-convex structure representing identification information such as the manufacturing date and model name, and is integrally formed on the main body simultaneously with casting by providing fine concavities and convexities on the mold. The cover has a relatively thin flat plate shape, and molten metal is poured at high speed from the edge of the space in the mold that forms the cover. When forming a mark on the cover, an uneven surface for forming the mark is provided on the surface of the mold. During casting, high-speed molten metal flows into the uneven surface, so erosion damage of the uneven surface tends to progress easily.

[0006] The present invention aims to provide a plate member and a method for manufacturing a plate member that can suppress the progression of erosion in the portion of a mold used to form a mark in a casting die. [Means for solving the problem]

[0007] A plate member according to a first aspect of the present invention is a plate member that constitutes a part of a semiconductor memory device. The plate member comprises a main body which is a rectangular plate-shaped casting and a mark having an uneven structure integrally formed on the surface of the main body, the main body including an edge extending in a first direction, the edge including a projection that protrudes on the positive side of a second direction parallel to the surface and perpendicular to the first direction, the surface being divided by two imaginary lines that pass through each of the ends of the projection in the first direction and extend parallel to the second direction, into a first region located between two imaginary lines and a pair of second regions located on both sides of the first region in the first direction, the mark being formed in at least one of the pair of second regions and located in a section away from the edge on the negative side of the second direction, with respect to at least 1 / 3 of the width of the main body along the second direction.

[0008] A second aspect of the present invention relates to a method for manufacturing a plate member that constitutes a part of a semiconductor memory device. The manufacturing method involves forming an intermediate body by casting using a mold, which includes a main body formed in the shape of a rectangular plate, a mark having an uneven structure integrally formed on the surface of the main body, and a flange connected to the gate-side edge of the main body. The connection portion between the main body and the flange is cut so that a protrusion remains on the edge that protrudes in the extending direction of the main body. The extending direction of the edge is defined as the first direction, the direction perpendicular to the first direction as the second direction, the region located between two imaginary lines passing through both ends of the protrusion in the first direction and extending parallel to the second direction is defined as the first region, and a pair of regions located on both sides of the first region in the first direction are defined as the second region. The mark is formed in at least one of the pair of second regions in a section that is at least 1 / 3 of the width of the main body along the second direction and away from the edge on the negative side of the second direction. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a plate member and a method for manufacturing a plate member that can suppress the progression of erosion of the part that forms a mark in a casting mold. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a perspective view showing an example of the configuration of a semiconductor memory device in which a plate member according to the embodiment is applied as a cover. [Figure 2] Figure 2 is a perspective view of the cover shown in Figure 1, seen from the inside. [Figure 3] Figure 3 is a plan view of the cover shown in Figure 1, seen from the inside. [Figure 4] Figure 4 is a perspective view of an intermediate according to the embodiment. [Figure 5] Figure 5 is a flowchart of the manufacturing method according to the embodiment. [Figure 6A] Figure 6A is a cross-sectional view showing one step of the manufacturing method according to the embodiment. [Figure 6B] Figure 6B is a cross-sectional view showing one step of the manufacturing method according to the embodiment. [Figure 6C] Figure 6C is a cross-sectional view showing one step of the manufacturing method according to the embodiment. [Figure 6D] Figure 6D is a cross-sectional view showing one step of the manufacturing method according to the embodiment. [Figure 6E] Figure 6E is a cross-sectional view showing one step of the manufacturing method according to the embodiment. [Figure 6F] Figure 6F is a cross-sectional view showing one step of the manufacturing method according to the embodiment. [Figure 7] Figure 7 is an enlarged perspective view of the cover according to this embodiment. [Modes for carrying out the invention]

[0011] Hereinafter, several embodiments will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and repeated descriptions are omitted. Further, the plate member according to the embodiment is applied, for example, as a housing cover of a semiconductor memory device (solid state drive: SSD) (see FIG. 1). However, the application of the plate member according to the embodiment is not limited to the above-mentioned cover, and can be applied as other components in a semiconductor memory device. Hereinafter, for convenience, the semiconductor memory device is referred to as SSD.

[0012] For convenience of description, an X direction (second direction), a Y direction (first direction), and a Z direction that are mutually orthogonal are defined. The X direction is the width direction of the SSD, and the Y direction is the depth direction of the SSD. The Z direction is the thickness direction of the SSD.

[0013] First, the configuration of the SSD 1 will be described. FIG. 1 is a perspective view showing an example of the configuration of the SSD 1 to which the plate member according to the present embodiment is applied as a cover. As shown in FIG. 1, the SSD 1 includes a housing 2, a circuit section 3, and a cover 4.

[0014] The housing 2 includes a bottom wall 21 and side walls 22, 23, and has a substantially rectangular parallelepiped outer shape. The bottom wall 21 is a rectangular flat plate extending in the X direction and the Y direction. The side walls 22 and 23 are belt-shaped flat plates having a predetermined width along the Z direction. The side walls 22 are provided at both edge portions of the bottom wall 21 in the X direction, and extend in the Y direction. The side wall 23 is provided on one of both edge portions of the bottom wall 21 in the Y direction. Accordingly, an opening 20 that opens in the Y direction is formed on the other of the two edge portions of the bottom wall 21 in the Y direction. When the bottom wall 21 is rectangular, the side wall 22 is located along the long side of the rectangle, and the side wall 23 is located along the short side of the rectangle. Further, a vent hole 24 may be formed in at least one of the side walls 22 and 23.

[0015] The bottom wall 21 is provided with a plurality of bosses 25 for supporting the circuit section 3. Each boss 25 is provided with a screw hole 26 or a pin 27. When viewed from the Z direction, the position of the screw hole 26 or the pin 27 matches the position of the through hole 33 formed in the substrate 31 of the circuit section 3.

[0016] The bottom wall 21 is provided with a support portion 28 that supports the cover 4. The support portion 28 has a rectangular shape and extends from the bottom wall 21 in the Z direction. A screw hole 29 for screwing the cover 4 is formed on the upper end surface of the support portion 28.

[0017] The circuit portion 3 includes a substrate 31 and a plurality of electronic components 32 mounted on the substrate 31. The electronic components 32 are, for example, semiconductor elements such as controllers and memories, passive elements such as resistors and capacitors, and connectors. The above-described through hole 33 is formed in the substrate 31, and a screw (not shown) and a pin 27 are inserted through the through hole 33. Accordingly, the circuit portion 3 is positioned relative to the housing 2. A plurality of substrates 31 may be provided. In this case, the plurality of substrates 31 are stacked at intervals in the Z direction.

[0018] FIG. 2 is a perspective view of the cover 4 of FIG. 1 when viewed from the inner side. The cover 4 is a plate member that covers the opening of the housing 2 in the Z direction. The cover 4 is placed on the upper end surface of the support portion 28. The cover 4 is fixed to the housing 2 by, for example, screwing through the screw hole 29. However, the fixing method of the cover 4 is not limited to screwing.

[0019] The cover 4 has a main body 41 which is a metal casting. The metal is, for example, an aluminum alloy, but is not limited thereto. The main body 41 is formed, for example, in a rectangular plate shape extending in the X direction and the Y direction. Further, the main body 41 includes a thin-walled portion 42 and a thick-walled portion 43 provided on a part of the periphery of the thin-walled portion 42.

[0020] The thick-walled portions 43 are located at the four corners of the main body 41. A through hole 44 for screwing the cover 4 to the housing 2 is formed in the thick-walled portion 43. The through hole 44 is formed at a position corresponding to the screw hole 29 of the housing 2. On the other hand, the thin-walled portion 42 is a thin plate having a thickness of about 2 mm or less. The thin-walled portion 42 is provided with a concave-convex structure indicating the mark M. This concave-convex structure is formed, for example, on the surface (inner surface) of the thin-walled portion 42 facing the interior of the housing 2.

[0021] Mark M has a raised and recessed structure that represents identification information. The identification information is, for example, information to ensure the traceability of the product (i.e., SSD1 or cover 4 in this embodiment). The identification information indicates the date of manufacture, week of manufacture, year of manufacture, lot number, casting conditions, product name, product number (model number), drawing number, etc., and is composed of, for example, letters, numbers, grid patterns, or a combination thereof. Mark M is integrally formed with the main body 41 during casting. The depth or height of the recesses or protrusions constituting Mark M is, for example, 0.1 mm or more and 0.2 mm or less. The line width constituting Mark M is, for example, 0.4 mm or more and 0.7 mm or less. The thickness of the main body 41 is, for example, 0.5 mm or more and 1.0 mm or less.

[0022] The edge portion 45 of the main body 41 defines the outer circumference of the main body 41. The edge portion 45 includes a pair of edge portions 45A, 45A extending in the Y direction and a pair of edge portions 45B, 45B extending in the X direction. If the housing 2 has a rectangular parallelepiped shape, the main body 41 also has a rectangular outer shape. In this case, the edge portion 45A is located on the longer side of the rectangle, and the edge portion 45B is located on the shorter side of the rectangle. Each edge portion 45A includes a projection portion 46 that is continuous with the thin-walled portion 42. Each projection portion 46 protrudes in the extending direction of the main body 41 (a direction parallel to the XY plane). Specifically, each projection portion 46 protrudes from the edge portion 45A to the positive or negative side in the X direction.

[0023] The protrusion 46 projecting to the negative side in the X direction is formed by cutting the portion formed on the overflow side during casting. On the other hand, the protrusion 46 projecting to the positive side in the X direction is formed by cutting the portion formed on the runner side during casting (see Figure 6E). Whether the protrusion 46 was located on the runner side or the overflow side during casting can be determined by observing the flow marks (so-called traces of molten metal flow) formed on the main body 41 with a microscope or the like.

[0024] Here, we define two imaginary lines L that pass individually through both ends 46b, 46b of the edge portion 45A in the Y direction and extend parallel to the X direction (see Figures 2 and 7). The surface of the main body 41 (thin-walled portion 42) is divided into a first region 48 and a second region 49 by the two imaginary lines L (see Figures 2 and 3). As shown in Figures 2 and 3, the first region 48 is the region located between the two imaginary lines L in the Y direction. On the other hand, the second region 49 is a pair of regions located on both sides of the first region 48 in the Y direction.

[0025] The mark M according to this embodiment is formed in a section 49a in at least one of the pair of second regions 49, 49. Section 49a is a region that is located at least 1 / 3 of the width W of the main body 41 along the X direction, on the negative side (overflow side) in the X direction from the edge 45 (see Figures 2 and 3). Section 49a may also be a region that is located at least 1 / 2 of the width W from the edge 45.

[0026] Mark M may be placed in each of the pair of second regions 49, 49. In this case, the Mark M placed in one of the pair of second regions 49, 49 and the Mark M placed in the other may have different identification information. For example, one Mark M may indicate information related to manufacturing (i.e., manufacturing date, manufacturing week, manufacturing lot number, casting conditions, etc.), and the other Mark M may indicate information that identifies the product (i.e., product name, product number, drawing number, etc.).

[0027] An electrodeposited coating film 47 (see Figure 6D), an example of a coating, is formed on the surface of the main body 41. The electrodeposited coating film 47 is formed by energizing the flange 51 (see Figure 4) of the intermediate body 5 (see Figure 4) which is immersed in the paint tank. Therefore, since the main body 41 is energized via the flange 51, it does not have any contacts that are energized during electrodeposition coating.

[0028] The electrodeposited coating film 47 (see Figure 6D) is not formed on the tip surface 46a of the protruding portion 46. This is because the tip surface 46a is a cut surface formed when the connecting portion 53 is cut in the manufacturing process described later.

[0029] Next, the manufacturing process of the cover 4 according to the manufacturing method of this embodiment will be described. Figure 5 is a flowchart of the manufacturing method of the cover 4. Figures 6A to 6F are cross-sectional views showing the steps of the manufacturing method according to this embodiment. These cross-sectional views show a cross-section that passes through the flange 51 (see Figure 4) and is parallel to the XZ plane.

[0030] First, in step S1, molds 61 and 62 are positioned. Specifically, as shown in Figure 6A, the upper mold 61 and the lower mold 62 are positioned opposite each other. A cavity 63 for forming the main body 41 is defined between the upper mold 61 and the lower mold 62. A surface 61a for forming the mark M is formed on the surface of the upper mold 61 facing the cavity 63. The cavity 63 is located in the X direction between the runner 64 and the overflow 65. That is, this arrangement assumes that the molten metal 66 (see Figure 6B) flows mainly in one direction parallel to the X direction, from the runner 64 to the overflow 65.

[0031] A runner-side gate 64a is provided between the runner 64 and the cavity 63. The runner-side gate 64a is formed such that its cross-sectional area decreases as it moves from the runner 64 towards the cavity 63. Therefore, the width of the runner-side gate 64a along the Z direction narrows as it approaches the cavity 63 from the runner 64. This shape allows the runner-side gate 64a to regulate the speed and amount of molten metal 66 flowing into the cavity 63. The runner-side gate 64a is located on the side of the cavity 63 where the edge 45A (projection 46) is formed.

[0032] On the other hand, an overflow-side gate 65a is provided between the overflow 65 and the cavity 63. The overflow-side gate 65a is formed such that its cross-sectional area increases as it moves from the cavity 63 towards the overflow 65. Therefore, the width of the overflow-side gate 65a along the Z direction widens as it approaches the overflow 65 from the cavity 63. With this shape, the overflow-side gate 65a adjusts the amount of molten metal 66 flowing out of the cavity 63 so that the molten metal 66 spreads throughout the entire cavity 63.

[0033] In step S2, molten metal 66 is supplied to the mold. As shown in Figure 6B, the molten metal 66 fills the cavity 63 from the runner 64 through the runner-side gate 64a. The excess molten metal 66 flows out to the overflow 65 through the overflow-side gate 65a.

[0034] In step S3, cooling and demolding are performed. As shown in Figure 6C, after the molten metal 66 has cooled and solidified, the upper mold 61 and the lower mold 62 are separated. Then, the intermediate body 5 is removed. The intermediate body 5 includes a main body 41 and at least one flange 51 connected to the main body 41. In this example, two flanges 51 are formed. One flange 51 is the portion of the solidified molten metal 66 that was formed inside the runner 64 and is connected to the edge 45A on the runner 64 side. The other flange 51 is the portion of the solidified molten metal 66 that was formed inside the overflow 65 and is connected to the edge 45A on the overflow 65 side. The main body 41 and each flange 51 are connected to each other by connecting parts 53 (see Figure 6E). The connecting parts 53 have the same thickness as the thin-walled part 42.

[0035] As shown in Figure 6C, the flange 51 may be formed to be thicker than the main body 41. At a minimum, the flange 51 may be formed to be thicker than the thin-walled portion 42 (see Figure 2). After the molten metal 66 has solidified, a through hole 52 (see Figure 4) may be formed in the flange 51. For example, a hook for suspending the intermediate body 5 during electrodeposition coating is inserted through the through hole 52, and the intermediate body 5 is energized through the hook. Alternatively, the intermediate body 5 may be energized via a jig (not shown) such as a clamp for gripping the flange 51. In this case, the formation of the through hole 52 may be omitted.

[0036] In step S4, pre-painting treatment is performed. The surface of the intermediate material 5 is degreased. Additionally, a washing treatment is performed to remove oil and foreign matter adhering to the surface. This prepares the surface of the intermediate material 5 for electrodeposition coating.

[0037] In step S5, electrodeposition coating is performed. As shown in Figure 6D, a hook for electrodeposition coating is inserted through the through hole 52 of the flange 51, and the intermediate body 5 is immersed in the coating tank. Then, by applying current through the flange 51, an electrodeposition coating film 47 is formed on the surface of the intermediate body 5. In this way, since the current is applied through the flange 51, there is no need to provide a separate structure for current application on the main body 41.

[0038] In step S6, the main body is machined. As shown in Figure 6E, with the flange 51 held or fixed by a jig (not shown), machining such as cutting is performed on the main body 41. For example, a through hole 44 is formed in the thickened portion 43. At this time, the support device such as the jig does not come into contact with the main body 41, and no direct pressure is applied from the device.

[0039] In step S7, flange removal is performed. As shown in Figure 6E, the connecting portion 53 between the main body 41 and each flange 51 is cut, and as shown in Figure 6F, each flange 51 is separated from the main body 41. This removes the flange 51 from the intermediate body 5. At this time, the connecting portion 53 may be cut so that a protruding portion 46 remains on the edge 45 of the main body 41, projecting in the direction of extension of the main body 41. Since the tip surface 46a of the protruding portion 46 is the cut surface after electrodeposition coating, as a result, no electrodeposition coating film 47 is formed on the tip surface 46a. After these steps, the cover 4 is completed.

[0040] (1) According to this embodiment, by placing the mark M in section 49a of the second region 49 (a region that is at least 1 / 3 of the width W away from the edge 45), the frequency of direct collision of the high-speed molten metal 66 with the uneven surface 61a of the upper mold 61 during casting can be reduced. This suppresses the progression of erosion of the uneven surface 61a and extends the life of the mold 61. It also reduces the frequency of maintenance of the mold 61.

[0041] (2) The velocity of the molten metal 66 decreases further as it moves away from the gate. Therefore, by placing the mark M in a section 49a that is at least half the width W away from the edge 45, the progression of erosion of the uneven surface 61a can be further suppressed.

[0042] (3) By setting the thickness of the main body 41 to 0.5 mm or more and 1.0 mm or less, the depth or height of the indentation of Mark M to 0.1 mm or more and 0.2 mm or less, and the line width to 0.4 mm or more and 0.7 mm or less, it is possible to achieve both the identifiability of Mark M and the resistance of the mold to melting.

[0043] (4) By constructing the Mark M with letters, numbers, grid patterns, or a combination thereof, product identification information can be displayed in an easily recognizable manner. This contributes to ensuring traceability and improving quality control.

[0044] (5) By applying the plate member according to this embodiment as the cover 4 of the semiconductor memory device 1, it is possible to provide a semiconductor memory device 1 equipped with identification information while reducing mold erosion. Since the mark M is integrally formed with the main body 41 at the same time as casting, there is no need to apply the mark in a later process, and the manufacturing process can be simplified. [Explanation of symbols]

[0045] 1...Semiconductor memory device (SSD), 2...Housing, 3...Circuit section, 4...Cover (plate member), 41...Main body, 42...Thin-walled section, 43...Thick-walled section, 44...Through hole, 45A...Edge, 45B...Edge, 46...Protruding section, 46a...Tip surface, 46b...End, 48...First region, 49...Second region, 49a...Partition, 5...Intermediate body, 51...Flange, 61...Mold (upper mold), 61a...Uneven surface, 62...Mold (lower mold), 63...Cavity, 64...Runner, 64a...Runner side gate, 65...Overflow, 65a...Overflow side gate, 66...Molten metal, M...Mark, L...Dandline, W...Width

Claims

1. A plate member that constitutes part of a semiconductor memory device, The main body is a casting formed in the shape of a rectangular plate, A mark having an uneven structure integrally formed on the surface of the main body, Equipped with, The main body includes an edge extending in a first direction, The edge portion includes a projection that protrudes to the positive side in a second direction parallel to the surface and perpendicular to the first direction, The surface is divided into a first region located between two imaginary lines that pass through each of the ends of the protrusion in the first direction and extend parallel to the second direction, and a pair of second regions located on both sides of the first region in the first direction. The mark is formed on at least one of the pair of second regions and is located in a section away from the edge on the negative side of the second direction, with respect to at least one-third of the width of the body along the second direction. plate member.

2. The mark is located in a section away from the edge on the negative side of the second direction, with a width of at least half of the main body along the second direction. The plate member according to claim 1.

3. The marks are located in each of the pair of second regions, The marks located in one of the pair of second regions, and the marks located in the other region, have different identification information from each other. The plate member according to claim 1 or 2.

4. A coating is formed on the aforementioned surface. No coating is formed on the positive end face of the protruding portion in the second direction. The plate member according to claim 1 or 2.

5. The depth or height of the recess or protrusion constituting the mark is 0.1 mm or more and 0.2 mm or less. The line width constituting the aforementioned mark is 0.4 mm or more and 0.7 mm or less. The plate member according to claim 1.

6. The aforementioned mark consists of letters, numbers, grid patterns, or a combination thereof. The plate member according to claim 1.

7. A semiconductor memory device comprising the plate member described in claim 1.

8. A method for manufacturing a plate member that constitutes part of a semiconductor memory device, An intermediate body is formed by casting using a mold, which includes a main body formed in the shape of a rectangular plate, a mark having an uneven structure integrally formed on the surface of the main body, and a flange connected to the runner-side edge of the main body. The connection portion between the main body and the flange is cut such that a protruding portion remains on the edge that extends in the direction of the main body. The extension direction of the edge is defined as the first direction, the direction perpendicular to the first direction as the second direction, the region located between two imaginary lines passing through both ends of the protrusion in the first direction and extending parallel to the second direction as the first region, and the pair of regions located on both sides of the first region in the first direction as the second region. The mark is formed in at least one of the pair of second regions, in a section on the negative side of the second direction, away from the edge, for a distance of at least one-third of the width of the main body along the second direction. A method for manufacturing plate components.

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