Patent Application
20250007196
The present invention generally relates to connectors in electrical devices, and more particularly to supporting cantilever beam connectors.
For making electrical connections with electrical components, such as electrical plugs and/or printed circuit boards (PCBs), it can desirable to provide socket contacts with two spaced-apart metal cantilever beams for gripping male contact posts. Cantilever beam connectors are fastening devise used to connect cantilever beams to supporting structures. They provide stability and transfer loads from the cantilever beam to the support. Cantilever beams can function similar to springs that apply a normal force to the mating contacts. A cantilever beam may include a minimum of two contact beams inside a mating window. However, in cantilever beam construction, the deformable beams employed to oppose the gripping force has a tendency to degrade with age and thereby reduce the life and reliability of the socket. It is also desirable to provide a compact socket structure, for space considerations typically require that the socket contacts be tightly stacked into overlaying rows adjacent one board edge.
In one aspect, an electrical connector structure is provided including a cantilever contact with a memory metal support that provides for improved cantilever contact mating. In one embodiment, the electrical contact structure includes cantilever beam having a contact portion for engaging a pin structure and a non-contact portion that is mechanical support with the contact portion. An insulated memory metal support beam is positioned adjacent to the non-contact portion of cantilever beam, wherein the insulated memory metal support beam transitions from a first geometry to a second geometry with the application of a transition element. The first geometry of the insulated memory metal support beam provides that the insulating memory metal support beam does not engage the non-contact portion of the cantilever beams. The second geometry of the insulated memory support beam contacts the non-contact portion of the cantilever beam producing a force that supports the contact portion of the cantilever contacts.
In another embodiment, the electrical contact structure includes deformable contacts having a contact portion for engaging a pin structure and a non-contact portion that is mechanical support for the contact portion. A memory metal support beam is positioned adjacent to the non-contact portion of the deformable contacts, wherein the memory metal support beam transitions from a first geometry having a first curvature to a second geometry having a second curvature with the application of a transition element. The first curvature of the memory metal support does not engage the non-contact portion of the cantilever beams. The second curvature of the memory support beam contacts the non-contact portion of the cantilever beam.
In another aspect, a method for reinforcing contacts in electrical connectors is provided that includes positioning an insulated memory metal support beam adjacent to the non-contact portion of a cantilever beam. The cantilever beam includes a contact portion for engaging a pin structure that is mechanically supported by the non-contact portion. The method further includes engaging the pin structure to the contact portion of the cantilever beam, wherein engagement of the pin structure to the contact portion includes inducing a normal force from the cantilever beam on the pin structure. The method may further include applying a transition element to the insulated memory metal support beam, wherein the transition element induces a geometry change in the insulated memory metal support beam that causes the insulated memory metal support beam to apply a force to the cantilever beam that reinforces the normal force on the pin structure.
In another aspect, a method of providing mechanical support for cantilever beam connectors is provided. In one embodiment, the methods includes installing a male connector into a female connector that includes a memory metal support beams adjacent to deformable cantilever beams of the cantilever beam connector, wherein a contact portion of the deformable cantilever beams directly contacts the pin connector. Applying a transition temperature to the memory metal support beams, wherein the transition temperatures causes a geometry change in the memory metal support beams from a relaxed position to a reinforcing position, wherein the reinforcing position includes the memory metal support beam directly contacting the formable cantilever beams while the contact portion of the deformable cantilever beams is directly contacting the pin connector.
These and other features and advantages will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings.
The following description will provide details of preferred embodiments with reference to the following figures wherein:
Detailed embodiments of the claimed structures and methods are disclosed herein; however, it is to be understood that the disclosed embodiments are merely illustrative of the claimed structures and methods that may be embodied in various forms. In addition, each of the examples given in connection with the various embodiments is intended to be illustrative, and not restrictive. Further, the figures are not necessarily to scale, some features may be exaggerated to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the methods and structures of the present disclosure. For purposes of the description hereinafter, the terms “upper”, “lower”, “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, and derivatives thereof shall relate to the embodiments of the disclosure, as it is oriented in the drawing figures. The terms “positioned on” means that a first element, such as a first structure, is present on a second element, such as a second structure, wherein intervening elements, such as an interface structure, e.g., interface layer, may be present between the first element and the second element. The term “direct contact” means that a first element, such as a first structure, and a second element, such as a second structure, are connected without any intermediary conducting, insulating or semiconductor layers at the interface of the two elements.
The methods and structures of the present disclosure are directed to electrical connectors including deformable beams, e.g., cantilever beams, for providing the electrical contact surfaces of the electrical connectors. The electrical contact structures disclosed herein employ memory metal support structures to mechanically support the deformable beams, e.g., cantilever beams. By providing mechanical support, the memory metal support structures provide for improved mating of the contacts to the electrical structures they are intended to provide electrical communication to.
It has been determined that as electrical connectors go through plug cycles, the contact normal force decreases over time. The contact normal force is a result of the deflection undergone of the receptable contact beam by the plug contact as its inserted into the connector. This force is what dominates the integrity and reliability of a connector. Loss of normal force may result from changes in temperature. As a connector is exposed to extended periods of elevated temperatures there can be an effect on the normal force interface material within the product. Loss of normal force may also result from the time the piece is in service. For example, even if the piece remains in the elastic region, some factors can still cause the normal force to decrease over time. If there is a constant force applied to the contact, over time stress relaxation will occur. Additionally multiple plug cycles can reduce the normal force. Connectors with higher normal force will have a low cycle life. Housing relaxation may also contribute to loss of normal force. High normal force is undesirable, because it increases mating forces, stresses on the contact springs/housings and wear. Over time, if the normal force degrades too much, electrical resistance may increase to insurmountable levels resulting in various circuit errors, signal errors, and other negative issues.
The methods and structures of the present disclosure integrate memory metals into the design of a connection such that the deflection undergone during mating cycles is counteracted. A memory metal would be used as small springs, constricting two adjacent contact beams or as a cantilever beam laying across all the contact cantilevered beams. As the contact beams are deflected during plugging (assembly of male and female electrical plugs), the memory metals normal force in a directional opposing the deflection of the cantilever beam would help return the cantilever beam to its original position, hence elongating the contact force of the overall connector, as well as increasing the connector's reliability. The methods and structures of the present disclosure are now described in greater detail with reference to
The term “memory metal” refers to a metal alloy composition that “remembers” its original shape, i.e., pre-deformed shape, and that when deformed returns to its pre-deformed shape when heat energy or magnetic energy is applied to it (depending on the alloy). The heat energy or magnetic energy is the “transition element”. For example, ferromagnetic shape-memory metals are the group of alloys that react to magnetic fields. In some embodiments, the composition for the memory metal that is employed in the memory metal support beam 50 is a composition in the copper-aluminum-nickel alloy type or the composition is in nickel-titanium (NiTi) alloy type. However, memory shape metals can also be created by alloying zinc, copper, gold and iron. Memory shape metals can exist in two different phases, with three different crystal structures (i.e. twinned martensite, detwinned martensite, and austenite) and six possible transformations. The thermo-mechanic behavior of the memory shaped metals is governed by a phase transformation between the austenite and the martensite.
Referring to
Applying a mechanical load to the martensite leads to re-orientation of the crystals or “de-twinning” which results to a deformation, which is not recovered (remembered) after releasing the mechanical load. Detwinning starts at a certain stress σs and ends at σf above which martensite continue exhibiting only elastic behavior (as long as the load is below the yield stress). The memorized deformation from detwinning is recovered after heating to austenite.
The phase transformation from austenite to martensite can also occur at constant temperature by applying a mechanical load above a certain level. The transformation is reversed when the load is released.
The transition from the martensite phase to the austenite phase is only dependent on temperature and stress, not time, as most phase changes are, as there is no diffusion involved. Similarly, the austenite structure receives its name from steel alloys of a similar structure. It is the reversible diffusionless transition between these two phases that results in the memory shape properties.
The shape memory effect (SME) occurs because a temperature-induced phase transformation reverses deformation, as shown in
Martensite is thermodynamically favored at lower temperatures, while austenite (B2 cubic) is thermodynamically favored at higher temperatures. Since these structures have different lattice sizes and symmetry, cooling austenite into martensite introduces internal strain energy in the martensitic phase. To reduce this energy, the martensitic phase forms many twins—this is called “self-accommodating twinning” and is the twinning version of geometrically necessary dislocations. Since the shape memory alloy will be manufactured from a higher temperature and is usually engineered so that the martensitic phase is dominant at operating temperature to take advantage of the shape memory effect, memory metals “start” highly twinned.
When the martensite is loaded, these self-accommodating twins provide an easy path for deformation. Applied stresses will detwin the martensite, but all of the atoms stay in the same position relative to the nearby atoms—no atomic bonds are broken or reformed (as they would be by dislocation motion). Thus, when the temperature is raised and austenite becomes thermodynamically favored, all of the atoms rearrange to the B2 structure which happens to be the same macroscopic shape as the B19′ pre-deformation shape. This phase transformation happens extremely quickly and gives SMAs their distinctive “snap”.
Repeated use of the shape-memory effect may lead to a shift of the characteristic transformation temperatures (this effect is known as functional fatigue, as it is closely related with a change of microstructural and functional properties of the material). The maximum temperature at which a memory metal can no longer be stress induced is called Md, where the SMAs are permanently deformed.
In one example, a memory metal alloy has an original crystal structure. Then metal is deformed and causes a different crystal structure to form. Depending on the alloy, heat energy or magnetic energy is applied and the metal goes back to its original crystal structure. The heat energy or magnetic energy is a “transition element”. Unlike most crystal structure changes in metals, this crystal structure change does not require diffusion.
Embodiments are described herein, in which the memory metal support beams 50 employ either a one way memory effect or a two way memory effect. In one embodiment, a one way memory effect is when a shape-memory alloy is in its cold state (below As). In this example, the metal can be bent or stretched and will hold those shapes until heated above the transition temperature. Upon heating, the shape changes to its original. When the metal cools again, it will retain the shape, until deformed again.
In one embodiment, a two-way memory effect is the effect that the material remembers two different shapes: one at low temperatures, and one at the high temperature. A material that shows a shape-memory effect during both heating and cooling is said to have two-way shape memory. The memory metal of the memory metal support beams 50 may also be referred to as a shape-memory alloy (SMA), smart metal, muscle wire, or smart alloy.
In one embodiment, an electrical connector is provided that includes a cantilever beam 55 having a contact portion 57 for engaging a pin structure 75 and a non-contact portion 56 that is mechanical support with the contact portion 55. The cantilever beams 55 may be composed of an electrically conductive material. Some examples of electrically conductive materials that may be suitable for the cantilever beams 55 include copper, aluminum, gold and combinations thereof. The contact portion 57 may have an apex that is configured to be the contact surface with the pin structure 75. For example, when an electrical contact include two cantilever beams 55, the apex's of the contact portions 57 should be positioned facing one another to provide the minimum distance between the separated cantilever beams 55 prior to the insertion of the pin structure 75 into engagement with the cantilever beams.
The non-contact portion 56 can be a continuous part of the contact portion 57, wherein the difference in the structures being that the non-contact portion 56 does not directly contact the pin structure 75. By “mechanical support” it is meant that the non-contract portion 56 provides the portion of the cantilever beam that is engaged to the housing 58 of the connector, and therefore connects the contact portion 57 to the housing 58.
Referring to
In one embodiment, the insulated memory metal support beam 50 transitions from a first geometry having a first curvature that does not engage the non-contact portion of the cantilever beams 55. In the embodiment depicted in
The transition element that causes the change between the two geometries illustrated in
The metal composition of the memory metal support beam 50 can be any composition that has been provided above in the description of memory metals. For example, the memory metal that is employed in the insulated memory metal support beam 50 can selected from the group consisting of nickel titanium alloys, copper-aluminum-nickel alloys and combinations thereof. In another embodiment, the metal composition of the memory metal support beam 50 is an alloy of elements selected from the group consisting of zinc, copper, gold, iron and combinations thereof. In one example, the memory metal composition of the insulated memory metal support beam 50 is Nitonol. NiTi alloys (Nitinol) may contain 45% titanium and 55% nickel.
The memory metal support beam 50 is insulated to reduce the possibility of interference with the cantilever beams 55. The memory metal component of the insulated memory metal support beam 50 may be in an insulating jacket having a composition selected from the group consisting of polyvinyl chloride (PVC), cross-linked polyethylene (XLPE), fluoroplastics, rubber, ethylene-propylene rubber, silicone rubber insulation and combinations thereof.
The designs illustrated in
In some embodiments, the geometries for the insulated memory metal support beams can use simple metal arc/radial beams for the shaping of the memory metals, but other shapes could be done. The shape can be constructed so as to interfere with connector housing 58 for additional support.
Actuation of the memory metal can take place any time after installation. For example, when connectors are used for a long period of time and there is a loss of contact normal force—the connector can be heated to actuate the memory metal to improve the retention force for further connector use.
Broadly the method may include positioning an insulated memory metal support beam 55 adjacent to the non-contact portion 56 of a cantilever beam 55, wherein the cantilever beam 55 includes a contact portion 57 for engaging a pin structure 75 that is mechanically supported by the non-contact portion 56. The method may further include engaging the pin structure 75 to the contact portion 57 of the cantilever beam 55, wherein engagement of the pin structure 75 to the contact portion 57 includes inducing a normal force from the cantilever beam 55 on the pin structure 75. Finally, the method may include applying a transition element, e.g., heat and/or magnetic field, to the insulated memory metal support beam 50. The transition element induces a geometry change in the insulated memory metal support beam 50 that causes the insulated memory metal support beam 50 to apply a force to the cantilever beam 55 that reinforces the normal force on the pin structure 75. The method is now described with greater detail with reference to
The method illustrated as beginning in
The method illustrated in
It is to be appreciated that the use of any of the following “/”, “and/or”, and “at least one of”, for example, in the cases of “A/B”, “A and/or B” and “at least one of A and B”, is intended to encompass the selection of the first listed option (A) only, or the selection of the second listed option (B) only, or the selection of both options (A and B). As a further example, in the cases of “A, B, and/or C” and “at least one of A, B, and C”, such phrasing is intended to encompass the selection of the first listed option (A) only, or the selection of the second listed option (B) only, or the selection of the third listed option (C) only, or the selection of the first and the second listed options (A and B) only, or the selection of the first and third listed options (A and C) only, or the selection of the second and third listed options (B and C) only, or the selection of all three options (A and B and C). This may be extended, as readily apparent by one of ordinary skill in this and related arts, for as many items listed.
Having described preferred embodiments of a system and method (which are intended to be illustrative and not limiting), it is noted that modifications and variations can be made by persons skilled in the art in light of the above teachings. It is therefore to be understood that changes may be made in the particular embodiments disclosed which are within the scope of the invention as outlined by the appended claims. Having thus described aspects of the invention, with the details and particularity required by the patent laws, what is claimed and desired protected by Letters Patent is set forth in the appended claims.
