Circuit board mounting methods

[0001] The following is a divisional of application Ser. No. 09/523,835, filed on Mar. 13, 2000 now U.S. Pat. No. 6,385,051.

[0002] 1. Field of the Invention

[0003] The present invention generally relates to electronic apparatus and, in a preferred embodiment thereof, more particularly relates to apparatus and methods for operatively mounting circuit boards on support structures such as computer chassis walls.

[0004] 2. Description of Related Art

[0005] For many years, the conventional method of installing a circuit board, such as the motherboard, in a computer was to simply screw the board substrate to bosses or other mounting structures suitably mounted on a chassis wall portion of the computer. This circuit board installation method substantially increased the time, and thus the cost, required to construct the computer in addition to adding to the complexity and difficulty of assembling, and later disassembling and servicing the computer.

[0006] A relatively recent improvement in the mounting of a main circuit board in a computer is illustrated and described in U.S. Pat. No. 5,754,396 to Felcman et al entitled “MODULAR DESKTOP COMPUTER HAVING ENHANCED SERVICEABILITY In the desktop computer illustrated and described in this patent, the motherboard is mounted on a tray structure which may be slid into and out of the computer chassis to install and later remove the motherboard for access and service purposes.

[0007] While this tray support concept hastens and reduces the cost associated with initially installing the motherboard in the chassis and subsequently removing the motherboard for service and replacement, it also increases the manufacturing cost of the computer since the motherboard must be produced and spared with this auxiliary support tray secured thereto.

[0008] It thus can be seen from the foregoing that it would be desirable to provide for the cost effective, screwless installation and removal of a circuit board within a computer without the necessity of securing to the computer an auxiliary support tray or other cost increasing mounting structure. It is to this design goal that the present invention is directed.

[0009] In carrying out principles of the present invention, in accordance with a preferred embodiment thereof, electronic apparatus is provided which is representatively in the form of a desktop computer. The computer has a circuit board, illustratively a motherboard, and a support structure, representatively a chassis wall. According to a key aspect of the present invention, the circuit board is operatively secured to the chassis wall without the use of screws or any sort of support tray secured to the circuit board.

[0010] Using a screwless circuit board attachment technique of the present invention, cooperatively engaged locking structures are carried by the circuit board and the support structure. The cooperatively engaged locking structures releasably hold the circuit board on the support structure and permit removal of the circuit board from the support structure in response to sequential movement of the circuit board relative to the support structure in (1) a first direction and (2) a second direction transverse to the first direction. A retaining structure releasably blocks movement of the circuit board in the first direction relative to the support structure, thereby releasably retaining the circuit board on the support structure.

[0011] In a preferred embodiment of the screwless circuit board attachment apparatus, the openings have generally keyhole-shaped configurations and are formed in a substrate body portion of the circuit board, and the projections are carried on the chassis wall portion, extend partly through the substrate openings and have notch portions receiving opening edge portions of the substrate body portion.

[0012] To rapidly install the circuit board on the chassis wall projections, the substrate body openings are moved over outer end portions of the projections, and the substrate body is moved parallel to its plane to cause the opening edge portions to enter the notches on the projections and thereby block removal of the circuit board from the projections in a direction parallel to their lengths. A retaining bracket member is then moved into a position in which it blocks movement of the circuit board to move its opening edge portions out of the projection notches.

[0013] When it is later desired to remove the circuit board, the retaining bracket is simply moved away from its circuit board blocking position, the circuit board is moved transversely to the projections to remove its opening edge portions out of the projection notches, and the circuit board is lifted off the projections.

[0021] Perspectively illustrated in FIGS. 1, 3 and 4 is a bottom portion of a generally rectangular sheet metal chassis section 10 of a representative desktop computer 12 which also includes a main circuit board or “motherboard” 14. Motherboard 14 is installable in the chassis 10 using unique screwless installation apparatus and methods of the present invention as subsequently described herein. AS will be readily appreciated by those of skill in this particular art, various computer components, such as drive units and other components and interconnecting cabling and the like have been removed from the chassis interior for purposes of illustrative clarity. Additionally, the top cover portion of the overall chassis structure has been removed for illustrative purposes.

[0022] Chassis 10 has a bottom wall 16 with a rear side edge 18, left and right upstanding side walls 20 and 22, and an upstanding front wall 24 extending between the side walls 20 and 22. An electrical power supply unit 25 of conventional construction is supported on the left side wall 20 for pivotal movement relative thereto between a solid line vertically extending access orientation, and a dashed line operating orientation in which the power supply unit 25 is swung down into the chassis interior in an upwardly spaced relationship with the bottom chassis wall 16.

[0023] The motherboard 14 has a generally planar rectangular substrate body 26 having front and rear side edges 28 and 30, with various electronic components, including a central processing unit 32, being operatively mounted on the top side of the substrate body 26. Also mounted on the substrate body 26, along its rear edge 30 are a series of various input/output components 33. Formed through the substrate body 26 are several spaced apart mounting holes 34 which form part of the specially designed circuit board mounting system of the present invention. The mounting system also includes spaced apart, upstanding mounting bosses 36 secured to the bottom chassis wall 16, upstanding left and right rear corner plate portions 38 and 40 of the chassis, and an elongated retaining bracket structure 42.

[0024] As best illustrated in FIG. 2, each of the motherboard substrate body mounting holes 34 is generally keyhole-shaped, having a circular main portion 44 from which a narrowed straight portion 46 radially outwardly projects. Each of the upwardly projecting mounting bosses (see FIG. 3) Includes a cylindrical base portion 48, an annular, vertically intermediate notch 50, and a generally conically-shaped upper end portion 52. A reduced diameter intermediate cylindrical portion 54 vertically extends between the base portion 48 and the conical upper end portion 52, and annular upper and lower ledges 56,58 are formed by the notch 50.

[0025] To rapidly mount the motherboard 14 within the interior of the chassis 10, without the use of separate fasteners of any sort or securing a tray or other type of mounting structure to the motherboard, the motherboard 14 is simply placed above the bottom chassis wall 16, with the upstanding chassis mounting bosses 36 in alignment with the circular portions 44 of the substrate body holes 34 (see FIG. 2). Next, the motherboard 14 is lowered to cause the conical upper end portions of 52 of the mounting bosses 36 (see FIG. 3) to extend upwardly through the hole portions 44, and then forwardly shifted relative to the mounting bosses 36 to cause the vertically intermediate boss portions 54 to enter the narrowed radial substrate body hole portions 46, with the upper and lower annular boss portions 56,58 respectively overlying and underlying top and bottom side portions of the substrate body 26 as cross-sectionally illustrated in FIG. 6.

[0026] As described above, the substrate body 26, and thus the entire motherboard 14, are releasably locked to the bottom chassis wall 16 via the interlockable, or cooperatively engaged, locking assembly comprising the mounting holes 34 and the bosses 36.

[0027] The substrate body 26, and corresponding mounting holes 34, is disposed onto the bosses 36 in a manner such that, to remove the substrate body 26 from the bosses 36, the substrate body 26 must be moved rearwardly to remove the intermediate boss portions 54 from the radial hole portions 46, and then lifted to move the circular hole portions 44 upwardly past the upper conical boss portions 52 to free the substrate body 26 from the bosses 36.

[0028] Such rearward shifting of the installed motherboard 14 relative to the bosses 36 is releasably prevented, thereby captively retaining the motherboard 14 on the bosses 36, using the retaining bracket 42. After the motherboard 14 is dropped onto and forwardly shifted relative to the bosses 36 as just described, a small outwardly projecting tab 60 on the right end of the retaining bracket 42 (see FIGS. 1, 4 and 5) is inserted into a vertical slot 62 formed in the right rear corner plate portion 40 of the chassis 10 (see FIGS. 1, 3 and 5). The retaining bracket 42 is then pivoted horizontally toward the rear edge 30 of the motherboard 14, as indicated by the arrow 64 in FIG. 4, until an outwardly projecting tab 66 on the left end of the retaining bracket 42 enters and is latchingly received in a vertical slot 68 in the left rear corner plate portion 38 of the chassis 10 (see FIG. 4). This releasably locks the retaining bracket 42 in its FIG. 7 installed position in which it extends outwardly along and parallel to the rear side edge 30 (see FIG. 4) of the motherboard substrate body 26.

[0029] With the retaining bracket 42 in this installed orientation, an inner or front side portion of the bracket defines an abutment which prevents the substrate body 26 from being rearwardly shifted in a manner unlocking it from and permitting it to be lifted off of the chassis bosses 36. Additionally, suitable openings 33a are formed in the bracket 42 that, with the bracket 42 in its installed orientation, complementarily receive rear portions of the various input/output devices as illustrated in FIG. FIG. 7.

[0030] When it is desired to remove the motherboard 14 from the chassis 10, the retaining bracket 42 is simply pivoted outwardly and removed from the chassis 10, thereby permitting the motherboard 14 to be rearwardly shifted relative to and lifted off the bosses 36 to quickly and easily remove the motherboard 14 from the computer 12.

[0031] As can readily be seen from the foregoing, the present invention provides for the screwless installation and removal of a circuit board on and from a support structure in an electronic device such as a computer, without the use of a support tray attached to the circuit board. While the present invention has been representatively illustrated as being used in conjunction with a computer motherboard attachable to a sheet metal chassis wall, it will be readily appreciated by those of skill in this particular art that principles of the invention could also be advantageously employed in an application involving other types of circuit boards attachable to other types of support structures.

[0032] Additionally, while the interlocking structures used on the circuit board to effect this screwless circuit board mounting representatively comprised projections on the support structure and cooperating openings on the circuit board, it will be readily be appreciated that the projections could alternatively be formed on the circuit board, and the cooperating openings associated with the support structure, if desired.

[0033] The foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims.