Patent Application
20130288534
The number and types of electronic devices available to consumers have increased tremendously the past few years, and this increase shows no signs of abating. Devices such as portable computers; tablet, desktop, and all-in-one computers; cell, smart, and media phones; storage devices; portable media players; navigation systems; monitors; and others have become ubiquitous.
The complexity of these devices has similarly been increasing. Additional functionality, such as graphics processing, networking, increases in memory size, and others, has led to an increase in the number and types of circuits included in these devices. These circuits may be located on boards, such as main-logic boards, in these devices.
However, due to increases in complexity, it is becoming more difficult to include all these needed circuits on one board. Also, there is a desire to be able to customize devices to target user preferences and varying price points. These factors have led to an increase in the use of daughter or riser cards. These cards may include various circuits. A card may connect to main-logic board via contacts along an edge of the card, where the edge of the card may plug into a corresponding connector on the main-logic board. Use of these cards allows functionality to be moved off the main-logic board, and also allows different cards to be used in different device configurations.
Unfortunately, these connectors may consume space on the main-logic board. This increased space means the main-logic board can either support less functionality or has to grow correspondingly larger. The latter may also mean that the entire electronic device may have to increase in size.
Also, these connectors may degrade signal quality and high-speed performance. Specifically, a signal traveling from a circuit on a card to a circuit on a main-logic board may need to travel along a trace on the card to a contact at an edge of the card, then through a connector joining the card to the main-logic board. From there, the signal needs to travel along a trace on the main-logic board itself. These multiple connections may increase signal path resistance and reactance, as well as signal coupling, thereby degrading signal quality.
Cards supported by these connectors may also be of considerable size, weight, and complexity. A large mass may place high rotational, lateral, and other forces on the connector.
Thus, what is needed are connectors having a high density of contacts that may also provide improved performance at high-speeds and be robust enough for use with large, heavy cards.
Accordingly, embodiments of the present invention may provide high-speed connectors that may have a high density of contacts, may provide improved performance at high speeds, and may be robust for use with large, complex cards.
An illustrative embodiment of the present invention may provide a connector for mating a daughter, riser, or other board, card, or device to a printed circuit board, flexible circuit board, or other appropriate substrate. In various embodiments of the present invention, the daughter, riser, or other board, card, or device may be a memory card, audio card, central processing unit or other processor card, graphics card, wired or wireless networking card, memory device, or other type of board, card, or device. The printed circuit board, flexible circuit board, or other appropriate substrate may be a main-logic board, motherboard, or other board.
An illustrative embodiment of the present invention may provide a connector having a housing with a slot forming an opening in a top side. The slot and opening may be arranged to receive a daughter, riser, or other card, board, or device. This connector may provide a high density of contacts by arranging contacting portions of contacts in multiple rows in the slot. Tail portions of the contacts may emerge from a bottom of the housing. The tail portions may be through-hole, surface-mount, or other type of contacting portion, or combination thereof. The tail portions may be soldered or otherwise fixed to a printed circuit board, flexible circuit board, or other appropriate substrate.
Another illustrative embodiment of the present invention may provide a connector having a slot forming an opening in a top of a housing. The slot may accept or receive an edge of a daughter or riser card. Contacting portions of contact pins in the connector housing may be arranged to mate with surface contacts near the edge of the daughter card. To improve high-speed performance, these contacting portions and corresponding surface contacts may be arranged in various patterns to provide shielding for signals, such as differential pair signals.
In one example, contacting portions and surface contacts may be arranged in two or more rows, and these rows may be at least approximately aligned, or they may be offset. Where contacts in these rows may be aligned, a first contact in a first row may be aligned with a second contact in a second row. These contacts may have a ground contact on each side, where the ground contact runs the length of both contacts and the space between them. This configuration may be used to carry differential signals. Where contacts are offset, two adjacent contacts may be used to carry a differential signal. These adjacent contacts may have a ground contact on each side, and a third ground contact below (or above). By positioning ground contacts in these ways, differential pair signals may be shielded to reduce cross-talk and to improve signal quality. To further improve signal quality, the ground contacts may include one or more contacting points to form electrical connections to a shield around a housing of the connector. Air gaps may be placed between contacts to reduce pin-to-pin capacitive coupling.
Embodiments of the present invention may improve high-speed performance by shielding signals as described above. Further shielding, for example, by providing a conductive shield around the housing, may further improve high-speed performance. Again, further shielding may be provided by embodiments of the present invention where ground contacts have one or more contacting portions forming electrical connections with a shield. In other embodiments of the present invention, shielding is omitted to prevent coupling through the shield between signal lines. In these embodiments, a nonconductive frame or shell may be placed around a housing of the connector. In a specific embodiment of the present invention, the nonconductive frame or shell is stretched before being placed over the housing for increased mechanical durability. The nonconductive frame or shell may be placed over the housing during manufacturing before reflow, or after reflow so that the nonconductive frame or shell may avoid the intense heat of this manufacturing step.
Another embodiment of the present invention may provide improved high-speed performance by simplifying an interconnect between a daughter or riser board and a main-logic board. In one specific embodiment of the present invention, a single contact may be used to convey a signal from a surface contact on a card or board to a surface contact on a main-logic board. This interconnect may reduce a number of contact points that may otherwise be needed, thus reducing the impendence and reactance of the interconnect path and improving high-speed performance.
Another embodiment of the present invention may provide a robust connector by including one or more barbs extending from the contacts, where the one or more barbs are inserted into a housing of the connector. These barbs may each include one or more teeth that may be used to secure the barb in place. These teeth may help to reduce or prevent movement of the contact in the housing that may otherwise occur due to forces placed on the contact by a card inserted into the connector. Durability of these connectors may be further enhanced by embodiments of the present invention, where one or more metal pins are used to provide mechanical support for a housing. These pins may be spot or laser welded or otherwise fixed to a shield. The pins may extend through the housing and emerge from a bottom of the connector, where they may be inserted into openings or make contact with contacts of a printed circuit board or other appropriate substrate. The pins may also be soldered to traces around the openings, or to contacts on a surface of the printed circuit board. Similarly, a key may be made of metal or other durable material in embodiments of the present invention to prevent damage to the connector or card by improper insertion of a card.
Another embodiment of the present invention may provide a method of manufacturing a robust connector. This method may include receiving a housing having central passage to accept a card, the central passage having a first side and a second side. The housing may further have a first outside side and a second outside side. A first plurality of contacts may be inserted into slots in the first outside side and the second outside side of the housing. Some or all of the first plurality of contacts may include one or more barbs that may extend into the housing. The barbs may include one or more teeth along a top or bottom edge, or along both edges, of the barb. A second plurality of contacts may be inserted into slots in the first side and the second side of the central passage. The second plurality of contacts may include contacts of a first type and a second type, where a difference between the types is a position of a contact tail. Where these contact tails are through-hole contact tails, varying the type of contact, and therefore the position of the contact tail, may space the through-hole contacts apart from each other. This may aid in construction of a printed circuit board on which the connector may reside.
This method may further include inserting side panels over the first outside side and the second outside side of the housing. These side panels may be insulative to isolate the first plurality of contacts from a shield and from each other. Dovetailed notches in the housing may be used to help secure the side panels in place. Metal pins may be inserted through the housing. A shell or shield may be placed over the housing and spot or laser welded, or otherwise fixed, to the metal pins. The shell or shield may be conductive or nonconductive.
Another embodiment of the present invention may route traces to provide shielding on a daughter or riser board or card. These techniques may also be applied to routing traces on main-logic boards. In a specific embodiment, traces on a card that are connected to contacts for a differential pair may be routed under a ground pad on the card. The ground pad may be further connected to ground on other layers of a printed circuit board of the daughter or riser card. Such grounding may provide shielding, improve signal quality, and decrease crosstalk.
Another embodiment of the present invention may provide a connector having a high-density of contacts. This embodiment may provide a high density of contacts by providing multiple rows of contacts on each side of an opening arranged to receive a card. Density may be further increased by close spacing of contacts that is achieved by placing air-gaps between contacts to reduce coupling. Density may also be improved by using side panels and a shell or shield to secure contacts in place. Barbs on some contacts may be used to further secure contacts. Mechanical stability may be improved by the use of pins and one or more keying features located in a housing of the connector. A use of a mix of through-hole and surface-mount contacts may be used to enable the routing of signals away from the connector and may help to improve the ability of the connector to be mounted on a printed circuit board or other substrate.
Various embodiments of the present invention may incorporate one or more of these and the other features described herein. A better understanding of the nature and advantages of the present invention may be gained by reference to the following detailed description and the accompanying drawings.
In various embodiments of the present invention, daughter or riser card 120 may be a memory card, audio card, central processing unit or other processor card, graphics card, wired or wireless networking card, memory device, or other type of board, card, or device. Main-logic board 130 may be a printed circuit board, flexible circuit board, or other appropriate substrate. While in this example, connector 110 is shown as providing an orthogonal connection between card 120 and main-logic board 130, in other embodiments of the present invention, card 120 and main-logic board 130 may be parallel or have other orientations.
Embodiments of the present invention may also provide an improved high-speed performance. This may be done by simplifying interconnect between card 120 and main-logic board 130. High-speed performance may also be improved through improved arrangements of contacts in connector 110. Examples are shown in the following figures.
While the various ground contacts shown herein may be connected to ground, in various embodiments of the present invention they may be connected to other low-impedance paths, or AC grounds. For example, they may be connected to a power supply, bias line, control signal, or other appropriate line.
In various embodiments of the present invention, contact pins in connector 110 may have various shapes. Examples are shown in the following figures.
Contact 520 may include contacting portion 522 and tail portion 524. Contacting portion 522 may form electrical connections with surface contact 224 on card 120. Tail portion 524 may contact a surface contact (not shown) on a main-logic board or other substrate (not shown). In other embodiments of the present invention, one or more of these contacts may have through-hole tail portions. For example, contact 510, which may be located at an edge of the housing, may have surface-mount tail portion 514, while interior contact 520 may have through-hole tail portion 524. This arrangement may facilitate inspection of a finished device by having surface-mount contacts visible at an edge of the housing and through-hole contacts under the housing where they would otherwise not be visible. In still other embodiments of the present invention, the interior contact 520 may have a tail portion 524 extending into a central opening in the housing where it may be inspected. Contacts 550 and 560 may be similarly arranged to have contacting portions 552 and 562, as well as surface-mount tail or contacting portions 554 and 564.
In various embodiments of the present invention, one or more contacts in connector 110 may have different width. For example, a power or ground contact in connector 110 may have a wide width to handle large currents, or to provide increased isolation between adjacent pins on each of its sides. These wider connector contacts may have correspondingly wide surface contacts on a card 120 and main-logic board 130.
While in these examples, tail portions are shown as surface-mount portions, other types of tail portions, such as through-hole portions, may be used consistent with embodiments of the present invention.
Again, these contacts may be arranged in ways to improve signal performance. Signal performance and shielding may be further improved by employing ground tabs in connector 110 below card 120. An example is shown in the following figure.
Again, surface contacts on a card and corresponding contacts in a connector may be arranged in various ways consistent with embodiments of the present invention. Another example is shown in the following figure.
Again, embodiments of the present invention may provide a high degree of ground shielding and crosstalk isolation. For example, as shown in
In some embodiments of the present invention, the impedance (Zo) requirements are such that the ground plane under contacts for differential pair DP4 and DN4 should be removed. Since the ground plane does not shield the surface from inner route layers, the signal traces 1020 may be routed beneath ground pad 1050. In this way, traces 1020 are at least partially shielded by ground pad 1050. This shielding may be further enhanced by connecting ground pad 1050 to grounds on one or more other layers through vias 1030. By burying traces 1020 beneath ground pad 1050, cross talk and isolation to differential pairs DP1 and DN1, and DP2 and DN2, which are routed on traces 1040, may be improved.
To further improve signal quality, stub portions of vias 1010 may be avoided. Specifically, printed circuit boards may be manufactured where vias, such as vias 1010, traverse through all layers of the board. These multilayer vias are then connected to traces on intermediate layers, thereby leaving stubs above or below the traces on these intermediate levels. These stubs may emit radio-frequency interference, degrading the signal and increasing crosstalk. Accordingly, embodiments of the present invention may route signals such that they change layers through vias which begin and terminate on the individual layers where traces 1020 are routed.
Again, contacts in various embodiments of the present invention may have various shapes. Further examples are shown in the figures below.
Contact 1110 may include contacting portion 1118 to mate (form an electrical connection) with a contact on a card (not shown.) Contact 1110 may also include contacting portion 1112, which may contact shield 1130, and surface-mount contact portion 1115.
One or more barbs 1114 may be included as part of contact 1110. These one or more barbs 1114 may be inserted into housing 1120 for mechanical stability. To provide further stability, one or more teeth 1116 may be provided along edges of barbs 1114. In a specific embodiment of the present invention, teeth 1116 may be located along a top edge of an upper barb 1114 and a lower edge of a lower barb 1114. When a card is inserted into central passage 1190, rotational stresses due to the force from the card on contact 1110 may have a tendency of driving teeth 1116 into housing 1120. This may further secure the position of contacts 1110 in housing 1120.
Contacts 1150 may include contacting portions 1152 to mate with corresponding contacts on a card (not shown.) Contacts 1150 may further include through-hole contacting portions 1152. Contacts 1150 may further include contacting portion 1154 to mate with a contact on a board inserted in central opening or passage 1190.
Again, power and ground contacts in connectors according to embodiments the present invention may be formed to have an additional width. This additional width may increase current carrying capabilities of the contacts. Also, the additional width may increase isolation between contacts on each side of the wider contact. An example is shown in the following figure.
In the above examples, the barbs on the various contacts may extend horizontally into a housing of the connector. In this way, if various ones of the contacts are inserted into the housing at different depths, the surface-mount portions of the contacts may remain aligned. For example, in
Again, shield 1130 may be connected to a ground of a board to which it is mounted via tabs 1132. That is, tabs 1132 may be inserted into openings on the board which may be plated with metal that is connected to ground. Tabs 1132 may be soldered to the plating of the openings to make an electrical connection between shield 1130 and ground. Also, as shown above, internal contacts 1110 and 1310 may include contacting portions, such as contacting portions 1112, 1132, and 1319, that make electrical connections to shield 1130. Contacts 1110 and 1310 may further connect to ground, thereby providing a ground path from the shield 1130, through contacts 1110 or 1310, to ground. This arrangement provides several parallel ground paths from shield 1130 to ground. In still other embodiments of the present invention, a conductor, such as a flexible or elastic conductor, may be used to connect shield 1130 to ground. Such a conductor may similarly be used to connect a ground on a card inserted into connector 110 to shield 1130.
Outer surface-mount contacting portions 1115 and inner through-hole contacting portions 1152 may emerge from the underside of connector 110. Surface-mount contacting portions 1115 may emerge from the underside of the connector near an edge of the connector 110 and extend away from the connector 110, and may be soldered to corresponding contacts on a surface of a printed circuit board. Through-hole contacting portions 1152 may emerge from the underside of the connector near a center of the connector and may be inserted into corresponding holes in a printed circuit board.
This arrangement may facilitate inspection of the finished product. Specifically, surface-mount contacts 1115 are readily visible along edges of connector 110. Through-hole contact portions 1152 may be inspected by viewing an underside of a printed circuit board supporting connector 110. If through-hole contact portions 1152 were instead surface-mount contacting portions, they would not be visible for inspection. Further, having that many rows of surface-mount contact portions would greatly increase the co-planarity requirement that would result from a pure surface mount design. Not exceeding two rows of surface-mount contact portions helps to avoid the difficulty of aligning a high number of surface-mount contact portions to a single plane.
It should be noted that inspection could also be accomplished by making all contacting portions through-hole contact portions. For example, surface-mount contacting portions 1115 could be replaced with through-hole contact portions and all contacts could be inspected. However, the use of through-holes near the edges of the connector 110 would block route paths from through-hole contact portions 1152 through a printed circuit board on which connector 110 is mounted. Also, the use of this many through-hole contacts would result in a high true position requirement. Using a mix of surface-mount and through-hole contact portions relaxes the requirement for co-planarity or positioning that would result from a design that uses only surface-mount or through-hole contact portions.
Again, contacts 1150 may include through-hole contacting portions 1152. However, there are physical limitations as to how close through holes can be located on a printed circuit board. Accordingly, embodiments of the present invention alternate the positions of these through-hole portions 1152 in order to spread out their locations. This may aid in the manufacture of a printed circuit board designed to have this connector reside on it. An example is shown in the following figure.
Again, embodiments of the present invention may provide connectors having conductive or nonconductive shells or shields. A conductive shield may contact contacting portions of contacts inside the connector, thus providing good ground shielding. However, when contacting portions of contacts are not used to contact a shield, a connecting shield may instead provide a pathway for increased signal coupling among contacts. In these situations, a nonconductive shell or shield may be used. Since either a shield or shell may be used, embodiments the present invention may provide a housing that may be used with either one. An example of such a housing is shown in the following figure.
Again, dovetailed portions 1128 of housing 1120 may be used to secure side panels 1170 in place. An example is shown in the following figure.
Again, embodiments of the present invention may provide a connector having a nonconductive shell. An example is shown in the following figure.
Again, embodiments of the present invention may optionally include one or more metal pins in a housing to provide additional mechanical stability. An example is shown in the following figure.
Again, embodiments of the present invention may include one or more keying features to assure that a card is inserted properly into the connector. In various embodiments of the present invention, this keying feature may be formed of metal to provide additional stability and mechanical support. An example is shown in the following figure.
In various embodiments of the present invention, connectors may be formed of various materials. For example, a housing for a connector may be formed of one or more types of plastics, nylons, or other materials or combination of materials. The contact pins and ground tabs for the connector may be formed of stainless steel, copper, brass, aluminum, or other materials or combination of materials. These contact pins and ground tabs may be at least partially plated with nickel, gold, palladium-nickel, or other plating materials or combination of materials.
In various embodiments of the present invention, signal isolation may be improved and crosstalk reduced through selective use of these materials. For example, some plastics and other materials may have dielectric constants that are three to four times that of air. Accordingly, the use of such materials in a housing for connector 110 may increase pin-to-pin capacitance or coupling capacitance. Such an increase may be useful between differential signal pairs, such as DP4 and DN4 in the example in
While an increase in coupling capacitance may be useful between contact pins for signals of a differential pair, it may not be useful between contact pins for signals of different differential pairs or between contact pins for signals of a differential pair and ground or other unassociated signal. Specifically, such an increase in coupling capacitance may increase crosstalk or slow edge rates. In such a situation, embodiments of the present invention may use an air gap, or a lower-dielectric material, between these contact pins. These air gaps or areas of lower-dielectric material may also be placed between rows of contact pins. By using higher-dielectric material between contact pins for differential signal pairs and lower-dielectric material or air gaps between contact pins for differential pairs and grounds, and between rows of contact pins, coupling may be concentrated between contact pins for signals in differential pairs and reduced elsewhere. It should be noted that in various embodiments of the present invention, the use of air gaps or lower-dielectric materials may be limited by the need for a certain level of mechanical stability and durability.
The above description of embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form described, and many modifications and variations are possible in light of the teaching above. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Thus, it will be appreciated that the invention is intended to cover all modifications and equivalents within the scope of the following claims.
This application is a nonprovisional of U.S. provisional patent No. 61/639,061, filed Apr. 26, 2012, which is incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61639061 | Apr 2012 | US |
