Patent Application
20160330503
The present principles relate generally to electronic devices and, more particularly, to electronic devices having metal shields in the vicinity of a printed circuit board.
The market preference for set top boxes and the like (such as computers, game consoles, DVD players, CD players, etc.) is to have such devices be small, compact, and versatile. However, such preferences increasingly challenge the designers, because set top boxes and the like are required to perform more functions, which require more internal components. This results in more challenges to appropriately manage the heat generated by some of these components in these crowded devices, which is potentially detrimental to the device's longevity and performance. This crowding also results in more challenges to appropriately shield some components from the risk of electrostatic discharge and/or from interference (such as from radiofrequency interference) to and from other components and external sources.
To appropriately guard at-risk components, the common closed polygon vertical wall metal structures (i.e. shields) have been employed, which are secured generally to a printed circuit board. However, the devices that employ such shields tend to be items that are mass produced in high volume production environments. As such, the soldering of shields in high volume production environments require rapid processing that requires the need for inspection of the mounted components contained within the shields and shields themselves.
A further challenge that has been observed in some devices such as satellite receivers with at least one F-connector requiring radiofrequency (RF) interference suppression has been the need to further employ an opposing metal shield (opposite the shield on the printed circuit board) configured to be mounted on the underside of the printed circuit board. The underneath opposing shield encloses a point of connection of a center connector of the at least one F-connector to the printed circuit board.
Additionally, the need for such RF interference suppression has required the shields themselves having large vertical dimensions to adequately surround the F-connector.
In crowded devices, the F-connectors are required to be located in close proximities to other components on the printed circuit board and each of these components themselves can require shielding. However, the shielding requirements for the different component can be uniquely different. In such cases, some have employed multiple shields. While others have employed a shield assembly 200 such as that shown in
In some crowded devices that now employ F-connectors and other components that require individual shielding that sufficiently shields the components from each other and from external sources, one unitary structure is used as the shield. The unitary structures unfortunately not only require additional production time, but also make reworking and/or sample inspection more challenging. As such, the need exists for a shield and a shield cover with a more efficient design to make reworking and/or spot sample inspection easier.
With the above challenges in mind and the increasing demand of the market for set top boxes to include F-connectors and/or other components requiring shielding on printed circuit boards, the objectives of the present principles effectively address the above mentioned challenges.
A set top box is disclosed that includes a vertical chassis wall having an aperture; a horizontal circuit board that extends toward the vertical chassis wall; an F-connector connected to the horizontal circuit board (either under or over the board) and extending out of the vertical chassis wall through the aperture; and inner shield (which can generally be used to contain/shield the RF circuit components mounted on the circuit board), wherein the inner shield comprises two parts: a proximal part near the F-connector that has a larger height and a distal part away from the F-connector that has a smaller height.
The present principles can also include an electronic device (1) having an outer casing (2, 3, 4, 6); a horizontal printed circuit board (501) within the outer casing; a radiofrequency shield (312) on the printed circuit board, the radiofrequency shield having a higher height region (316) that forms a higher height shield room (313B) and a lower height shield region (317) that forms a lower height shield room (313A); a first electronic component (10) in the higher height shield room; and a second electronic component (504) in the lower height shield room. The electronic device can have at least one wall (318) of the higher height shield room being higher than all walls of the lower height shield room. A shield cover (311) can be included that covers the radiofrequency shield, the first electronic component and the second electronic component. The shield can include ribs or indents (336) that are on outside upstanding side walls (321) of the radiofrequency shield; and attachment springs (334) extending from an upper plate (331, 333, 330) of the shield cover in which the attachment springs grasp the ribs or indents to secure the shield cover to the radiofrequency shield. The upper plate (331, 333, 330) can have a contour that follows a contour of top edges of the walls that defines the higher height shield room and the lower height shield room. The principles can include at least one other first component in at least one other higher height shield room or at least one other second electronic component in at least one other lower height shield room and/or the higher height shield room and the lower height shield room share one wall (321, 322), which can be an interior wall (321). The outside upstanding side walls (321) of the radiofrequency shield can alternatively have a textured surface for the attachment springs (334) to contact and secure the cover to the shield.
The present principles can also include an electronic device (1) having an outer casing (2, 3, 4, 6); a horizontal printed circuit board (501) within the outer casing; one or more first electronic components (10) and one or more second electronic components (504) over or on the printed circuit board (501); and a radiofrequency shield (312) on the printed circuit board, the radiofrequency shield having outside upstanding side walls (321) surrounding the first and second electronic components and surrounding at least one interior upstanding wall (322), one of the outside upstanding side walls being a back wall (318). The radiofrequency shield includes a higher height region (316) that completely or partially surrounds the one or more first electronic components in which the higher height region includes at least part of the back wall and includes at least part of one other of the outside upstanding side walls or at least part of the at least one interior upstanding wall; and a lower height region (317) that completely or partially surrounds the one or more second electronic component in which the lower height region includes at least part of another of the outside upstanding side walls or at least another part of the at least one interior upstanding wall. At least part of the higher height region is taller than all of the lower height region. The higher height region can have one or more higher height shield rooms (313B) that each contain the one or more first electronic components and the lower height shield region that includes at least one lower height shield rooms (313A) that each contain the one or more second electronic components. The electronic device can include an intermediate region (315) in the radiofrequency shield between the higher height region and the lower height region, wherein at least one wall in the intermediate region slopes downward as the at least one wall extends from the higher height region to the lower height region.
The present principles may be better understood in accordance with the following exemplary figures, in which:
The invention will now be described in greater detail in which embodiments of the present principles are illustrated in the accompanying drawings.
A key advantage of the invention is that the lower height region 317 makes it easier to repair, optically inspect and troubleshoot the shield 312 and the components contained within the shield 312 after the shield is affixed. Further, this lower height region 317 makes it easier to finish and/or complete the manufacture of the electronic device 1. The lower height region 317 allows for easier soldering and inspecting of the components within the shield and the shield 312 itself, wherein the ease of soldering is enhanced, because the lower height region 317 can have relatively shallow walls. The shallow walls make it easier to see inside the walls of the shield 317 at various stages of manufacturing and after some of these stages, which include thermal processing stages that can often cause components to move and/or change in some respects.
It should be noted that the cover 311 can have holes or slots therein depending on the requirements of the electronic device and the components therein. The quantity, size, shape, orientation and position of the holes and slots that can be tolerated will depend and/or be dictated by the wavelengths of the applicable radiofrequency waves.
The shield 312 can be a unitary structure of one folded metal sheet with designed bends and joints, which can be analogous to Origami art. Folded corners 319 can be present and can increase stability. The folded corners 319 include adjacent vertical wall portions and can include a horizontal wall portion 319H extending from the vertical wall portions.
Alternatively, the shield 312 can be partly a unitary structure of one folded metal sheet with designed bends and joints and can include added vertical walls as needed which can be employed to enhance shielding or enhance stability.
The shield 312 in
In alternative embodiments, the shield 312 can be attached to the printed circuit board 501 through reflow-soldering.
Also, it should be understood that the first components 10 can be components other than an F-connectors and can be positioned at dimensions from the surface of the printed circuit such that a larger height requirement shield back wall 318 is needed. Such first components which require shielding can also be part of the other electrical connectors on the panel jack 5.
Further, the current principles are applicable to such for first components which are not F-connector and are not necessarily electrical connectors, but do require shielding and require the higher height regions 316
In alternative embodiments, the dual height shield is designed to allow the use of a standard-height swage-attached F-connector. In such cases, the majority of other components (i.e. shallow components or second components 504 that lay lower than the first components 10) contained by the shield 312 that can be shielded by lower height walls are specifically positioned away from the shield back wall 318 or further from the shield back wall 318 than the F-connector and/or other first components. With such a layout, most of the components are conveniently positioned for easy testing and rework even with the shield 312 attached.
In sum, an electronic device 1 such as a set top box is disclosed that includes a vertical chassis wall 3 having an aperture; a horizontal circuit board that extends toward the vertical chassis wall; F-connector 10 connected to the horizontal circuit board which can be under or over the horizontal circuit board and extending out of the a vertical chassis wall through the aperture; and an inner shield 312 which can generally be used to contain/shield the RF circuit components mounted on the printed circuit board on the interior side of the vertical chassis wall and connected to the F-connector. The inner shield comprises a series of vertical peripheral walls that surround components under or over the printed circuit board in which the higher height region 316 (or proximal portion of the vertical peripheral walls) that are connected or close to the F-connector are larger than the height of the lower height region 317 (or distal portion of the of the vertical peripheral walls) that is away from the F-connector.
In an alternative embodiment, the shield back wall 318 can be parallel to and adjacent to the vertical chassis rear wall 3, the shield front wall 320 can be opposite the shield back wall 318, and at least two outside vertical side wall portions 321 can extend from the shield back wall 318 to the shield front wall 320. The shield walls can be linear are can have bends. The shield back wall, shield front wall, and outside vertical side wall portions comprise the series of vertical peripheral walls. The proximal portion 316 of the vertical peripheral wall is the back wall 318 and the portions of the outside vertical side wall portions connected to the back wall 318 in proximity of the back wall. Proximal portion 316 of the shield near or toward the back wall 318 has a larger height than the distal portion 317 of the vertical peripheral wall near or toward the front wall 320. The outside vertical side wall portions 321 can have an intermediate region 315 in which the proximal portion transitions to the distal portion which is the region where the height of the peripheral wall reduces from a larger height to a lower height.
In embodiments, the shield 312 can further have interior vertical walls 322 that extend from interior sides of the shield back wall 318, front wall 320, and/or outside vertical sides wall portions 321 and/or other interior vertical walls 322. For example, some of the interior vertical walls such as those used to form shield rooms D and E as shown in
The electronic device 1 can further include a top or shield cover 311 as shown in
These portions 330, 331, 333 can be planar and the perimeter of the shield cover 311 can have generally vertical fingers or flaps or spring clips 334 and extend perpendicularly from the peripheral edge of the shield cover, wherein the fingers or flaps or spring clips 334 extend over the exterior sides of the vertical peripheral walls as shown in
There are a number of advantages to having a tuner shield with two different heights. One is the tuner shield height is reduced in the area where most of the chip components are located making it easier for the production test equipment to verify component placement and proper soldering while still allowing a standard F-connector to be used. Another is the reduced height of the tuner shield also makes it easier for product development as well as to fix solder issues and/or correct setting of components during production. Additionally, the reduced height of the tuner shield reduces the overall mass of the metal tuner shield which minimizes the amount of time needed in the reflow oven to bring the tuner wrap up to the temperature needed to solder the tuner shield to the printed circuit board. This allows the time needed in the reflow oven to be optimized for proper soldering of the components rather than just setting a minimum time to insure the shield solders.
The present principles have been developed as an improvement of prior set top box designs which employed several high order input filters. In some of these set top boxes two separate shielded areas were employed in which one area employed a standard height shielded area that contained a standard F-connector and the other area having input filters employed a second shielded area in which the shield height was roughly half the height of that of the first shielded. Applicants have recognized that this approach also led to manufacturing difficulties in that it was challenging to optically inspect the solder joints in the area with the taller shield wall around the parts. Also, it is was difficult to perform touch-up soldering in the area due to the difficulty of getting a soldering iron into the small shielded rooms within the shield, wherein the individual shielded rooms are needed to prevent the various tuner filters from talking/interfering to each other. The factory conditions are such that the large mass of the taller tuner wrap or shield controlled the amount of time the entire assembly had to dwell in the reflow oven to guarantee that the metal gets hot enough to form a good solder joint between the tuner shield and the solder connection to the ground plane on the printed circuit board.
An additional concern regarding the design according to the current principles was whether a single tuner shield cover 311 could fit over the dual-height shield 312 properly and be effective. The sloping transition between the full-height area and the reduced height shield is an embodiment in which the intermediate cover region 333 in
The design in
The design in
Further testing has shown that that having the upper plate (331, 333, 330) being solid without holes improves the rigidity of the shield cover 311 to enhance the gripping of the fingers 334.
It is recognized, however, that vent holes in the upper plate (331, 333, 330) may be necessary in some designs for heat management, because some of the components contained within the shield 312 can generate heat which may need to be dissipated. As such, having vent holes in the shield cover 311 is one embodiment of the present principles. Although the vent holes such as those shown in the known shield cover 200 in
An additional concern of the shield 312 was the capability of the shield 312 to pick up harmonics from the DDR (dual data rate memory) into the F-connector. Experimentation has, however, showed that by grounding the tuner shield 312 to a metal chassis of the set top box at the level of the printed circuit board advantageously minimizes any common-mode ground between the printed circuit board and F-connector, thereby mitigating such pick up.
Although having the F-connector 10 and its components and grounding features above the printed circuit board is preferred, the current principles include embodiments in which some components and/or grounding features can be on the opposite side of the printed circuit board 501 as shown in
Here, the F connector nut 342 is shown on the F-connector body 513. The F-connector tab 524 can have an offset 528 that starts just below the bottom edge of the printed circuit board 501. This allows the F-connector tab 524 to bend and be displaced relative to the bottom 525 of the suppressor. The F connector tab 524 can be separated from the side walls of the suppressor 523 and the side walls of the suppressor 523 can be flush with the edge of the printed circuit board 501. This prevents the side walls of the suppressor 523 from being loaded by contact with the inside wall of the vertical chassis rear wall 3, and further allows the tab 524 to be compressed between the inner tuner shield 312 and vertical chassis rear wall 3 when the nut 342 is secured onto the threaded portion of the F-connector 10 on the outside of the vertical chassis rear wall 3.
The tab 524 on the F-connector can have a preferred thickness in the range of 1.8 +0.0-0.1 mm.
A=F-connector shoulder to frame gap, which can be 0.05 mm;
B=thickness of the wall of the suppressor 523, which can be 0.25 mm to 0.5 mm;
C=the edge of the printed circuit board 501 to frame gap, which can be 0.5 mm;
D=the printed circuit board slot side for mounting the body of the F-connector to the printed circuit board 501, which can be 1.90±0.125 mm; and
E=the F-connector body tab size, which can be 1.8 +0.0-0.1 mm, inserted into the slot D.
The construction of the F-connector 10 is such that the center pin 514 can go through the printed circuit board 501 and have a solder connection on the underside thereof. The center pin 514 can be by the inner shield 312 in the region of the proximate cover portion 330 region where the vertical peripheral walls are at the highest levels. This small point of connection can be shielded to prevent pick-up of spurious signals from the high speed digital portions of a receiver, for example, that generated from the Double Data Rate synchronous dynamic random access memory (DDR), for example, and other components on the bottom side of the PCB 501 and reflected off the inside of the metal enclosure of the device which can be a satellite receiver. Such signal can be picked up on the center pin 514 of the F-connector 10 that protrudes through the printed circuit board 501.
In addition, a component of the currents from the digital portions of the receiver can be present in the ground plane surrounding the pin 514. Thus, the suppressor 523 provides a Faraday shield around the center pin 514 to reduce reflected pickup as well as preventing a current differential across the ground plane surrounding the center pin 514. The Faraday shielding also reduces a source of ingress be outside interference such as broadcast television and cell phones.
Although the illustrative embodiments have been described herein with reference to the accompanying drawings, it is to be understood that the present principles are not limited to those precise embodiments, and that various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the scope of the present principles. All such changes and modifications are intended to be included within the scope of the present principles as set forth in the appended claims.
Also, it should be noted that expressions such as “vertical,” “horizontal,” “front,” “back,” “top,” bottom,” “upper,” “lower” and “over” are used in the description and claims with regards to certain elements with respect of an arbitrary coordinate system such as that shown in some figures; however, the invention is intended for use in components and/or the electronic devices that may be rotated 90 degrees, 180 degrees or to some other value either about a vertical reference line or a horizontal reference lines. This implies that “horizontal” can mean “vertical” and vice versa, “top” can mean “bottom” and vice versa, etc.
This application claims the benefit of U.S. Provisional Application Ser. No. 61/924,905, filed Jan. 8, 2014, which is incorporated by reference herein in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US14/67272 | 11/25/2014 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 61924905 | Jan 2014 | US |
