Patent Application
20210091493
The present disclosure relates to electrical connectors, and more specifically, to card-edge connectors.
A card-edge connector is a connection type between a circuit board and a discrete component. This discrete component may take the form of a socket mounted on a second circuit board, in which case the card-edge connector can be utilized as a connection between the circuit board and second circuit board. In a typical card-edge connector, contact traces are placed directly on one or both sides of a circuit board near or at the edge of the circuit board. A corresponding socket may contain a circuit-board shaped slot and contact pins therein that may interface with the contact traces when the edge of the circuit board is inserted into the slot.
Some embodiments of the present disclosure can be illustrated as a socket for a card-edge connector, the socket comprising a bottom frame end and a top frame end. The socket may also include a first frame portion and a second frame portion. The socket may also conclude a slot between the first frame portion and the second frame portion, such that a card-edge connector proceeds from the top frame end towards the bottom frame end between the first frame portion and the second frame portion when inserted into the slot. The socket may also comprise a pin contact in the first frame portion. The pin contact may comprise a bottom pin section that protrudes out of the first frame portion into the slot near the bottom frame end. The pin contact may also comprise a pin shaft located within the first frame portion and connected to the bottom pin section. Finally, the pin contact may also comprise a top pin section connected to the pin shaft and located within the first frame portion. The socket may also comprise a pin fulcrum located within the first frame portion, wherein the pin fulcrum contacts the pin shaft at a fulcrum point. A card edge connector, when inserted into the slot, may push the bottom pin section away from the slot and towards the first frame portion when inserted into the slot. The pin fulcrum may prevent the pin shaft from moving away from the slot at the fulcrum point when the bottom pin section moves away from the slot. This may cause the top pin section to move towards the slot. Finally, the top pin section may press against the card-edge connector when it moves towards the slot.
Some embodiments of the present disclosure can also be illustrated as a card-edge connector on a circuit board, the card-edge connector comprising a first section located near an edge of the circuit board. The first section may be of a first thickness. The card-edge connector may also comprise a second section located between the first section and a center of the circuit board. The second section may be of a second thickness that is greater than the first thickness. The card-edge connector may also comprise contacts located on the second section.
Some embodiments of the present disclosure can also be illustrated as a method of assembling a card-edge connector socket, the method comprising inserting a contact pin into an opening of the socket housing. The pin may be inserted between a slot and a fulcrum. The method may also comprise connecting the contact pin to a pin base. The pin may be shaped such that a circuit board inserted into the slot displaces the pin and causes a portion of the pin to rotate towards the circuit board.
The above summary is not intended to describe each illustrated embodiment or every implementation of the present disclosure.
The drawings included in the present application are incorporated into, and form part of, the specification. They illustrate embodiments of the present disclosure and, along with the description, serve to explain the principles of the disclosure. The drawings are only illustrative of certain embodiments and do not limit the disclosure.
While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
Aspects of the present disclosure relate to electrical-connector sockets, more particular aspects relate to card-edge connector sockets. While the present disclosure is not necessarily limited to such applications, various aspects of the disclosure may be appreciated through a discussion of various examples using this context.
Typical card-edge connectors take the form of trace contacts (sometimes referred to herein as “contacts”) placed on the surface of a printed circuit board (sometimes referred to herein as a “PCB”) that is designed to be inserted into a PCB-shaped slot in a socket. The socket typically contains contact pins (sometime referred to herein as “pins”) that interface with the trace contacts when the PCB is inserted into the slot. In order to increase the likelihood of the pins making sufficient contact with the trace contacts, the pins in some card-edge connector sockets (sometimes referred to herein as “card-edge sockets” or “sockets”) protrude into the slot until a PCB is inserted into the slot. As the PCB is inserted, the PCB may force the pins away from the center of the slot and into the socket housing. At the same time, the pins may push against the PCB with an equal amount of force, causing the pins to press tightly against the trace contacts on the PCB.
Depending on the use case in which a card-edge connector is applied, there may be multiple benefits to the socket pins pushing against the trace contacts. As previously discussed, applying force to the contacts with the pins may increase the quality of the electrical connection between the pins and contacts, which may increase the integrity of a signal sent through the connection, and may therefore allow higher data rates to be communicated through the connection. Further, because the pins in typical card-edge sockets press against the surface of the PCB (and therefore, the trace contacts) while the PCB is being inserted into the socket slot, the pins often rub against the trace contacts as the PCB is being inserted. As the pins rub the trace contacts, they may wick the trace contacts clean of corrosion or coatings. This wicking, in some instances, may also increase the electrical connection between the pins and contacts, further increasing signal integrity sent through the connection.
However, the force that the socket pins apply to the trace contacts may also lead to negative consequences in some use cases. For example, while wicking trace contacts during insertion may increase signal integrity in some use cases, the amount of force that is typically required to create useful wicking is less than the force that is typically required to maintain reliable contact once the PCB is inserted. For this reason, socket pins often press against the trace contacts with significantly more force than is necessary for wicking.
However, as the force pushing two objects together increases, the friction produced when one of those objects moves in relation to the other (and at least partially perpendicular to that force) also increases. Thus, in instances in which socket pins push against the trace contacts with more force than is necessary for wicking, more friction that is necessary is also created between the socket pin and trace contacts. In some instances, the amount of friction produced may be sufficiently high to scratch, erode, or otherwise damage the trace contacts on the edge-card connector. When these trace contacts are damaged, reliability and signal integrity may be decreased.
Thus, while a high force between socket pins and trace contacts may be required for connection reliability, that same high force may also create friction during PCB insertion that negatively affects connection reliability. Where connection reliability, connector performance, and signal integrity may be particularly important, gold trace contacts may be used. However, because gold contacts are soft, they may be more susceptible to friction during PCB insertion. This has led to thicker contacts being used in use cases in high-importance use cases. Unfortunately, thicker contacts require more contact material, which increases manufacturing cost. This may be especially true when trace contacts are composed of expensive metals, such as gold.
In some use cases, the importance of wicking contacts during PCB insertion may be high enough that the benefits gained from wicking may partially offset the negative effects of the higher-than-necessary force that is used to wick the contacts. For example, in some instances an edge-card connector may be used in an environment with a high amount of airborne impurities that may tend to coat electrical components prior to insertion. In some instances, oxidizing agents may tend to oxidize the outermost layer of the atoms in a trace contact, leading to an oxidized covering over the remainder of the trace contact. In these examples, the coating or oxidized layer may partially insulate the trace contact, reducing signal integrity. In either of these (or other) examples, wicking may remove the coating/oxidized layer.
However, in many use cases wicking contacts results in very little, if any benefit. This may be, for example, because the surrounding environment is relatively clean of airborne impurities and oxidizing agents. In these use cases, the negative effects of the force applied to the trace contacts by the pins may not be significantly mitigated. Without mitigating these negative effects, the relative cost of the negative effects, and the cost required to reduce them (e.g., thicker trace contacts), may be exacerbated.
To address these and other issues, embodiments of the present disclosure utilize a low-friction pin and socket structure that reduces the force applied to trace contacts by socket pins during PCB insertion, but increases the force applied when insertion is nearly completed. Some such embodiments may utilize pin contacts with a bottom pin section, shaft, and top pin section. The bottom pin section may protrude out into the socket slot, causing an edge-card connector to make contact with and deform the pin connector upon insertion. The bottom pin section may push against a pin shaft, which may contact a fulcrum connected to the socket housing. This fulcrum may allow the bottom pin section to be deformed away from the slot, which may cause the top pin section to become deformed in the other direction. In some embodiments, this may reduce or eliminate friction between pin contacts and trace contacts during PCB insertion until shortly before the PCB is fully seated in the socket.
Socket pins 112A and 112B are located within each side of the socket housing, and are composed of pin bases 114A and 114B, bottom pin sections 116A and 116B, pin shafts 118A and 118B, and top pin sections 120A and 120B, the transitions between which are demarcated by dots on pins 112A and 112B. Bottom pin sections 116A and 116B protrude into slot 108, and would therefore be contacted by an edge-connector card that is fully inserted into slot 108 and seated on PCB seat 110. Pin bases 114A and 114B may connect contact pins 112A and 112B to another component, such as a motherboard on which the socket is installed. Pin bases 114A and 114B may also secure pins 112A and 112B to the socket (e.g., through pin base 106 and PCB seat 110).
As illustrated, a portion of pin bases 114A and 114B run behind the high portions of bottom section 106. However, in the embodiment shown, an opening is present in the socket housing in bottom section 106 near PCB seat 110. This opening may enable socket pins 112A and 112B to be easily inserted into the socket housing. This may be beneficial, for example when incorporating the embodiments of the present disclosure into current and previous manufacturing processes.
Side sections 104A and 104B may be connected to fulcra 122A and 122B respectively. Fulcra 122A and 122B may contact pin shafts 118A and 118B at fulcra points. If bottom pin sections 116A and 116B shifted away from slot 108, the bottom portion of pin shafts 118A and 118B would be pushed away from slot 108 as well. Pin shafts 118A and 118B would then press against fulcra 122A and 122B at their respective fulcra points, causing the top portions of pin shafts 118A and 118B to be pushed towards the slot. In some embodiments, this design may prevent top pin sections 120A and 120B from contacting trace contacts on an inserted PCB until that PCB is seated or nearly seated on PCB seat 110.
When edge connector 202 begins to contact pin 210, the bottom section of pin 210 is pushed away from the slot. This movement is illustrated by movement arrow 214. Due to the interaction between pin 210 and fulcrum 220, the top section of pin 210 moves towards the slot when the bottom section of pin 210 moves away from the slot. Further, as is depicted by movement arrow 214, the relative shapes of the bottom section of pin 210 and edge connector 202, as illustrated, cause a high percentage (e.g., 60-99%) of the forces, between the bottom sections of pin 210 and edge connector 202 to be in a horizontal, rather than vertical, plane. For example, 60% of the force between pin 210 and edge connector 202 may be attributed to a vector that propagates perpendicular to the direction of insertion of edge connector 202 and 40% of the force may be attributed to a vector that propagates parallel to the direction of insertion of edge connector 202 (in some use cases, parallel to the primary dimension of edge connector 202). This may be beneficial for multiple reasons. For example, reducing vertical resistance of pin 210 against edge connector 202 may reduce the force that is necessary to insert edge connector 202 into the slot. Further, increasing the horizontal forces between the bottom of edge connector 202 and the bottom of pin 210 increases the retention of edge connector 202 in the socket housing.
Also illustrated in
However, as edge connector 202 is pushed further into the housing, pin 210 is pushed closer to edge connector 202, which may bend pin 210 to increase the surface area of pin 210 that interfaces with trace contact 212. For example, as illustrated, as edge connector 202 is pushed into the slot further and further, the interaction of pin 210 with fulcrum 220 will cause the shaft portion of pin 210 to rotate clockwise. This clockwise rotation may also apply a force on the top portion of pin 210. However, because the top portion of pin 210 is contacting trace contact 212, pin 210 may bend and the top portion of pin 210 may rotate counter clockwise near the trace contact as it moves toward the trace contact. With the shape of pin 210, as illustrated, this would likely increase the surface area of pin 210 that is interface with trace contact 212. Further, this added surface area may press against a portion of trace contact 212 that had just been wiped, strengthening the electrical connection of the pin-contact interface.
In
Alternate shapes of card-edge connectors that may be inserted into a low-friction card-edge connector socket are illustrated in
The descriptions of the various embodiments of the present disclosure have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
