High performance interlayer connector with low stack height

Abstract

A low profile interlayer connector. The connector is simple to manufacture and can be reliably formed even if the stack height is 4 mm or less, and still has high signal integrity. The connector has a region comprising contacts of identical shape, which are functionally different by features of the housing, which features of the housing include lossy material in a block having narrower protrusions electrically coupled to contacts designated as ground contacts. The mating portion of the contact is adjacent a wall of the housing that tapers to increase the effective dielectric constant near the signal contact. Each contact may have a hole therein to engage an insertion tool to enable repeatable and stable insertion of the contact into the housing. A footprint for mounting the connector to the PCB may include signal vias offset relative to mounting pads for the signal contacts.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit and priority of U.S. Provisional Application No. 63 / 409,407, filed on September 23, 2022, entitled "HIGH PERFORMANCE MEZZANINE CONNECTOR WITH LOW STACK HEIGHT". The content of this application is incorporated herein by reference in its entirety. Technical Field

[0003] This patent application generally relates to mezzanine connectors, which can be used, for example, to connect parallel printed circuit boards. Background Art

[0004] In many electronic systems, separable electrical connectors are used to connect sub - assemblies. Integrating sub - assemblies into a device using electrical connectors can be achieved simply by pressing the sub - assemblies together so that the separable connectors mate. Fabricating an electronic system in this way can offer many advantages. Each sub - assembly can be manufactured by a company specializing in the function provided by that sub - assembly, such that the sub - assembly can provide higher performance or quality than comparable electronic circuits of an entire device manufactured by a single company. Additionally, sub - assemblies enable the device to be maintained during its service life, as sub - assemblies can be added or replaced to repair or upgrade the electronic system.

[0005] For example, a server can be assembled from two or more sub - assemblies. Each electronic sub - assembly can be formed by attaching components to a printed circuit board. One sub - assembly can be a server motherboard. The motherboard can be a printed circuit board that establishes connections between components such as a processor, memory, power supply, and network interface, which together operate to provide server functionality. Some of the components can be mounted to the motherboard, while other components can be mounted to other printed circuit boards, commonly referred to as daughter cards. The daughter - card sub - assemblies can be connected to the motherboard via separable connectors.

[0006] Connectors are configured to be mounted to a printed circuit board (PCB) in a desired orientation within a device. For example, a daughter card can be mounted with its edge facing the edge of the motherboard. A connector configured to mount sub - assemblies in this configuration can be configured as a right - angle connector or an orthogonal connector. Alternatively, a daughter card can be mounted with its surface parallel to the surface of the motherboard. A mezzanine connector is configured to connect sub - assemblies in this configuration. For example, in a server, a processor can be attached to a daughter card and attached to the motherboard via a mezzanine connector.

[0007] As electronic systems become smaller, faster, and more complex, the number of circuits in a given area of an electronic system and the frequency at which the circuits operate have increased significantly in recent years. Current systems transfer more data between PCBs and require electrical connectors that can electrically handle more data at higher speeds than even connectors just a few years ago. However, the integrity of signals passing through separable connectors is typically negatively affected by greater density and higher frequencies, making it challenging to design connectors for both high-speed signals and high density.

[0008] Miniaturization presents further design challenges for mezzanine connectors. The size of a mezzanine connector must be designed to provide a specific stack height, which is defined by the spacing between parallel printed circuit boards connected by the mezzanine connector. In some systems, miniaturization is achieved by reducing the stack height, thereby challenging the design of the mezzanine connector. For example, shortening the length of the contacts provides insufficient wiping between mating contacts, and dimensional variations can sometimes undesirably affect the integrity of high-speed signals passing through the connector. Due to these challenges, it is not easy to obtain high-performance mezzanine connectors with a stack height below about 5 mm. SUMMARY OF THE INVENTION

[0009] Concepts described herein may be embodied as a low-profile mezzanine connector. The connector may include: a housing that includes insulating material in an insulating portion and lossy material in a lossy portion, the housing including a plurality of slots arranged in a plurality of columns, wherein the lossy portion includes a plurality of protrusions adjacent to a subset of the slots in each of the plurality of columns; and a plurality of contacts, each contact including a portion in a corresponding one of the plurality of slots.

[0010] In another aspect, a low-profile mezzanine connector may include: a housing that includes insulating material in an insulating portion and lossy material in a lossy portion; and a plurality of contacts arranged in a plurality of columns. The housing may include a base having a first side and a second side opposite the first side, and a plurality of walls extending from the first side of the base. Each of the plurality of contacts may include a mating portion, a mounting portion, and an intermediate portion connecting the mating portion and the mounting portion. For each of the plurality of contacts, the intermediate portion may be disposed in the base. The mating portion may extend from the base adjacent to one of the plurality of walls. The base may include: a plurality of first-type regions in which the insulating material partially extends from the first side to the second side and the lossy material partially extends from the first side to the second side; and a plurality of second-type regions interspersed with the plurality of first-type regions in which the insulating material extends completely from the first side to the second side.

[0011] In another aspect, a low-profile mezzanine connector can include a housing and a plurality of contacts arranged in a plurality of columns. The housing can include a base having a first side and a second side opposite the first side, and a plurality of insulating walls extending from the first side of the base. Each of the plurality of contacts can include a mating portion, a mounting portion, and an intermediate portion connecting the mating portion and the mounting portion. For each of the plurality of contacts, the intermediate portion can be disposed in the base; the mating portion extends from the base adjacent to one of the plurality of walls; and for at least one subset of the plurality of contacts, a portion of the wall adjacent to the contact among the plurality of walls tapers adjacent to the base, thereby reducing the impedance of the contacts in the subset.

[0012] These techniques can be used alone or in any suitable combination. The foregoing is a non-limiting overview of the invention defined by the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The drawings are not necessarily to scale. In the drawings, each identical or nearly identical component shown in various drawings is represented by the same numeral. For clarity, not every component is labeled in every drawing. In the drawings:

[0014] Figure 1A is a perspective view of a connector configured to mate with a BGA mezzanine connector.

[0015] Figure 1B is a partial cross-section through the Figure 1A connector in a mated configuration.

[0016] Figure 2A is a top perspective view of an exemplary mezzanine connector.

[0017] Figure 2B is Figure 2A a bottom perspective view of the exemplary mezzanine connector;

[0018] Figure 3 is Figure 2A a partially exploded perspective view of the exemplary mezzanine connector.

[0019] Figure 4 is Figure 2A an enlarged view of a portion of the exemplary mezzanine connector within Figure 3 box 4 in

[0020] Figure 5 is Figure 2A an enlarged bottom perspective view of a portion of the exemplary mezzanine connector.

[0021] Figure 6 is Figure 2A a column of contacts in the exemplary mezzanine connector, where the insulating portion of the housing is cut away.

[0022] Figure 7 is Figure 2A of an exemplary mezzanine connector Figure 4 The perspective cross-sectional view of the part shown in the figure, without contacts inserted into the slots.

[0023] Figure 8 is a side view of the contacts in a part of a column, where the insulating part of the housing is cut away.

[0024] Figure 9A is a schematic diagram of pads in a part of an exemplary connector footprint area (occupation area, covering area, footprint) on the surface of a printed circuit board.

[0025] Figure 9B is in Figure 9A A schematic diagram of a printed circuit board in a part of an exemplary connector footprint area within area B of.

[0026] Figure 10 is a perspective view of two connectors, each connector having a contact area with multiple columns as shown in Figure 2A and each connector having a housing with a peripheral wall configured for mating. DETAILED DESCRIPTION

[0027] The inventors have recognized and realized the technology for providing a high-speed and high-density mezzanine connector with a low stack height. For example, these technologies can suppress resonances with low signal insertion loss, provide a consistent impedance to the signal path that matches the impedance of the printed circuit board on which the connector is mounted, enable the use of short contacts, or enable reliable assembly of the connector. These technologies can be used alone or in combination with one or more of such technologies, and in some examples, a mezzanine connector with a stack height of 5 mm or less (e.g., less than 4 mm or between 2.0 mm and 4.0 mm) can be achieved. Such a low-stack-height connector can reliably transmit data-carrying signals at a rate of 56 Gbps or greater.

[0028] Figure 1A and Figure 1B show known mezzanine connectors 10 and 20 mounted to corresponding PCBs using BGA attachment technology. In Figure 1AIn the example, connector 10 is mounted to PCB 12, and connector 20 is mounted to PCB 22. Each of the connectors has a housing, which may be made of an insulating material. Connector 10 has housing 14, and connector 20 has housing 24. In this example, housing 14 is configured to fit within and latch to housing 24 such that connectors 10 and 20 can be pressed together to effect mating. When mated, connectors 10 and 20 can jointly provide a plurality of conductive paths between PCB 12 and PCB 22.

[0029] Each of housings 14 and 24 may hold a plurality of conductive contacts 16 and 26 that establish connections through the respective connectors 10 and 20. Each of contacts 16 and 26 may have a mating contact portion. The mating contact portions of contacts 16 and 26 may be complementary such that when connectors 10 and 20 are mated, the mating contact portion of contact 16 can establish an electrical connection to the mating contact portion of the corresponding contact 26. For example, the mating contact portion of contact 26 may be shaped as a blade, and the mating contact portion of contact 16 may be shaped as a beam. Upon mating, the beam of contact 16 may deflect to apply a mating force against the blade of the mating contact portion of contact 26.

[0030] The mating contact portions of the contacts are positioned at the mating interface of each of the connectors. As Figure 1A shown, contacts 16 and 26 are arranged in a plurality of parallel columns C such that the mating interface of each connector includes an array of columns having a plurality of parallel mating contact portions.

[0031] Each of the contacts may have a tail configured to connect the contact to another structure, in this example a PCB. The tail may extend from the corresponding housing at the mounting interface of the connector. In this example, as Figure 1B shown in the partial cross-section of, the tail of contact 16 of connector 10 extends into a recess 34 formed at the mounting side of housing 14. The tail of contact 26 of connector 20 extends into a recess 44 located at the mounting side of housing 24. Each contact 16 in connector 10 has a tail to which solder ball 32 has been fused. Each contact 26 in connector 20 has a tail to which solder ball 42 has been fused. In Figure 1B the example, the tails of the contacts are bent such that the surfaces of the tails are parallel to the mounting interface, and solder balls 32 and 42 are fused to such surfaces of the corresponding contacts' tails.

[0032] Such as Figure 1A and Figure 1BConnectors such as the illustrated connector 10 or 20 can be manufactured by molding the housing as an integral structure having openings in which contacts are inserted. Alternatively, the housing can be formed of multiple components. For example, a connector can be formed by first forming contact sub-assemblies each having a plurality of contacts held in an insulating portion that serves as part of the connector housing. These contact sub-assemblies can then be secured to a support structure such that the contact sub-assemblies are held together as a connector. As an example, an insulating frame can be molded to have features (such as slots) for receiving ends of the contact sub-assemblies such that when the contact sub-assemblies are engaged in the frame, the contacts of the contact sub-assemblies form a plurality of parallel contact rows. Alternatively or additionally, the contact sub-assemblies can be held together by metal clips or adhered to one another, for example, via an adhesive or thermal riveting.

[0033] In use, these solder balls 32 and 42 can be reflow soldered to pads located on the surfaces of parallel printed circuit boards. These boards can be separated by a distance S determined by the height of the mating connectors. The distance S is sometimes referred to as the stack height of the connector. For some systems, it is desirable to have a stack height of 5 mm or less, or in some examples 4 mm or less. For example, for a dense connector that provides connections for 15 to 20 differential pairs per square centimeter (such as at least 18 differential pairs) and can operate at data rates higher than 56 Gbps, a stack height between 2 mm and 4.5 mm is desirable.

[0034] Figure 2A A mezzanine connector 110 is shown that can meet these requirements. Figure 2A A contact area in the form of an array having multiple columns is shown. For simplicity, the connector 110 is shown without peripheral walls, guiding or alignment features, and latching structures. It should be understood that these and other similar features can be incorporated. Additionally, it should be understood that Figure 2A the illustrated structure can be a complete area of contacts in a connector or can be a sub-assembly integrated with a support structure to form a complete connector.

[0035] The connector 110 has a housing that has a base 112 and a plurality of walls 114A - 114D. In this example, the base 112 is generally flat, and the walls 114A - 114D extend perpendicularly from the upper surface 128 of the base 112. A plurality of contacts 118 are held in the base 112 of the housing. In this example, the contacts 118 are held in a plurality of columns, where each column is adjacent and parallel to the surface of the walls 114A - 114D. In this example, the contacts within each column are spaced center - to - center at a consistent pitch. The center - to - center pitch along the column can be in the range of 0.8 mm to 1.2 mm, for example, it can be 1 mm. The column - to - column pitch can be in the range of 1 mm to 2 mm, for example, it can be 1.5 mm.

[0036] Figure 2A is a top view of the connector 110. In Figure 2A 's view, the mating interface of the connector 110 is visible. In the example shown, the connector 110 includes contacts that are shaped and positioned for mating with a second connector having similar contacts shaped and positioned in a similar manner. To support this mating, the walls 114A - 114D are separated by gaps 116A - 116C. The second mating connector can have a similar configuration, and when the connectors are mated, each of the walls 114A - 114D of the second connector will fit within the corresponding gaps 116A - 116C of the first connector, and vice versa. In this state, the contacts 118 of the first connector will be aligned with and press against the contacts 118 of the second connector. The contacts 118 in both connectors can deflect to produce a mating force perpendicular to the surface of each mating contact. The design described herein can support each mating contact in generating a normal force of nominally about 50 grams, with stability over the life of the connector such that the contact force is about 30 grams after 1000 hours at 105°C.

[0037] Although not shown in Figure 2A , along each side, one of the connectors can have contacts disposed along the inward - facing surface of the wall and no contacts on the outward - facing surface of the wall. This configuration can be used to ensure that the contact columns in one connector are aligned and mated with the contact columns in the other connector.

[0038] Figure 2B shows the lower surface 130 of the base 112. An array of solder balls 132 is distributed across the surface 130. Each of the contacts 118 can have a mounting portion to which the solder balls 132 are fused. Thus, the solder balls can have the same center - to - center pitch along each column and the same column - to - column pitch as the contacts 118. The diameter of the solder balls can be in the range of 20 mils to 24 mils, for example, it can be 22 mils.

[0039] Each solder ball can be partially seated within a recess 134 in the surface 130. The mounting portion of the contact 118 can extend into the corresponding recess 134, and the solder ball 132 can be fused to the mounting portion at the recess 134.

[0040] The housing of the connector 110 can be molded from one or more types of materials. In this example, the connector 110 has an insulating portion 140 formed of an insulating material and a lossy portion 142 formed of a lossy material. In this example, the insulating portion includes islands (e.g., Figure 5 510A and 510B of ) and walls 114A - 114D within the base. For example, the insulating material can be nylon or liquid crystal polymer (LCP), and can be filled with insulating fibers such as glass fibers. The insulating material can be injection molded into the desired shape to form the insulating portion 140. The lossy portion 142 can be formed separately and inserted into the insulating portion 140, or as shown in this example, as a second material injection in a secondary injection molding operation.

[0041] Such a material can be considered lossy: the material dissipates a sufficient portion of the electromagnetic energy that would otherwise interact with the material and significantly affect the performance of the connector. The significant effect is caused by attenuation within the frequency range of interest for the connector. In some configurations, the lossy material can suppress resonances within the ground structure of the connector, and the frequency range of interest can include the natural frequency of the resonant structure in the absence of the lossy material. In other configurations, the frequency range of interest can be all or part of the operating frequency range of the connector.

[0042] To test whether a material is lossy, the material can be tested over a frequency range that can be less than or different from the frequency range of interest for the connector using the material. For example, the test frequency range can be from 10 GHz to 25 GHz or from 1 GHz to 5 GHz. Alternatively, a lossy material can be identified from measurements made at a single frequency such as 10 GHz or 15 GHz.

[0043] The loss can be caused by the interaction of the electric field component of the electromagnetic energy with the material, in which case the material can be called electrically lossy. Alternatively or additionally, the loss can be caused by the interaction of the magnetic field component of the electromagnetic energy with the material, in which case the material can be called magnetically lossy.

[0044] An electrically lossy material can be formed of a lossy dielectric material and / or a poor conductor. The electrically lossy material can be formed of materials that are traditionally considered dielectric materials, such as those having an electric loss tangent greater than about 0.01, greater than 0.05, or between 0.01 and 0.2 in a frequency range of interest. The "electric loss tangent" is the ratio of the imaginary part to the real part of the complex dielectric constant of the material.

[0045] The electrically lossy material can also be formed of a material that is typically considered a conductor but is a relatively poor conductor in a frequency range of interest. These materials can conduct electricity in a frequency range of interest but have some losses such that the conductivity of the material is weaker than that of the conductor of an electrical connector but better than that of the insulator used in the connector. Such materials can include conductive particles or regions that are sufficiently dispersed so as not to provide high conductivity, or are otherwise prepared to have this property: the property results in relatively weak bulk conductivity in a frequency range of interest as compared to a good conductor such as pure copper. For example, die-cast metals or poor-conducting metal alloys can provide sufficient losses in certain configurations.

[0046] This type of electrically lossy material typically has a bulk conductivity of from about 1 siemens / meter to about 100,000 siemens / meter, or from about 1 siemens / meter to about 30,000 siemens / meter, or from 1 siemens / meter to about 10,000 siemens / meter. In some embodiments, a material having a bulk conductivity between about 1 siemens / meter and about 500 siemens / meter can be used. As a specific example, a material having a conductivity between about 50 siemens / meter and 300 siemens / meter can be used. However, it should be understood that the conductivity of the material can be selected empirically or by electrical simulation using known simulation tools to determine the conductivity that provides suitable signal integrity (SI) characteristics in the connector. For example, the measured or simulated SI characteristics can be low crosstalk combined with low signal path attenuation or insertion loss, or low insertion loss variation as a function of frequency.

[0047] It should also be understood that the lossy member does not need to have uniform properties throughout its volume. For example, the lossy member can have, for example, an insulating skin or a conductive core. If the properties of the member average out in the region where it interacts with electromagnetic energy to be sufficient to attenuate the electromagnetic energy, the member can be identified as being lossy.

[0048] In some embodiments, a lossy material is formed by adding a filler comprising particles to a binder. In such embodiments, a lossy member can be formed by molding or otherwise shaping the binder with the filler into a desired form. The lossy material can be molded onto a conductor and / or molded through an opening into a conductor, which can be a ground conductor or a shield of a connector. Molding the lossy material onto the conductor or through an opening into the conductor can ensure tight contact between the lossy material and the conductor, which can reduce the likelihood that the conductor supports resonance at the frequencies of interest. Such tight contact can, but need not, result in ohmic contact between the lossy material and the conductor.

[0049] Optionally or additionally, the lossy material can be molded onto or injected into an insulating material, for example, in a secondary injection molding operation, or vice versa. The lossy material can be positioned against or sufficiently close to a ground conductor so as to have significant coupling with the ground conductor. Tight contact does not require electrical coupling between the lossy material and the conductor, since sufficient electrical coupling such as capacitive coupling between the lossy member and the conductor can produce the desired result. For example, in some cases, a coupling of 100 pF between the lossy member and the ground conductor can have a significant effect on suppressing resonance in the ground conductor. In other examples where the frequencies employed are in the range of about 10 GHz or higher, the reduction in electromagnetic energy in the conductor can be provided by sufficient capacitive coupling between the lossy material and the conductor, which has a mutual capacitance of at least about 0.005 pF, such as in the range between about 0.01 pF and about 100 pF, between about 0.01 pF and about 10 pF, or between about 0.01 pF and about 1 pF. To determine whether the lossy material is coupled to the conductor, the coupling can be measured at a test frequency such as 15 GHz or in a test range such as 10 GHz to 25 GHz.

[0050] To form an electrically lossy material, the filler can be conductive particles. Examples of conductive particles that can be used as a filler to form an electrically lossy material include carbon or graphite formed as fibers, flakes, nanoparticles, or other types of particles. Various forms of fibers can be used, in woven or non-woven form, coated or uncoated. Non-woven carbon fibers are a suitable material. Metals in the form of powders, flakes, fibers, or other particles can also be used to provide suitable electrical loss characteristics. Optionally, a combination of fillers can be used. For example, metal-coated carbon particles can be used. Silver and nickel are suitable metal coatings for fibers. The coated particles can be used alone or in combination with other fillers such as carbon flakes.

[0051] Preferably, the filler will be present in a volume percentage sufficient to allow the formation of a conductive path from particle to particle. For example, when using metal fibers, the fibers can be present in an amount of about 3% to 30% by volume. The amount of filler can affect the conductive properties of the material, and the volume percentage of the filler will be lower within this range to provide sufficient loss.

[0052] The binder or matrix can be any material that will solidify to position the filler, cure to position the filler, or can otherwise be used to position the filler. In some embodiments, the binder can be a thermoplastic material conventionally used to manufacture electrical connectors to facilitate molding the electrically lossy material into the desired shape and molding it to the desired location as part of manufacturing the electrical connector. Examples of such materials include liquid crystal polymers (LCP) and nylon. However, many alternative forms of binder materials can be used. A curable material such as an epoxy resin can be used as the binder. Alternatively, materials such as thermosetting resins or adhesives can be used.

[0053] While the above binder materials can be used to form an electrically lossy material by forming a binder around the conductive particulate filler, the lossy material can also be formed with other binders or in other ways. In some examples, the conductive particles can be impregnated into the formed matrix material or can be coated onto the formed matrix material, for example by applying a conductive coating to a plastic part or a metal part. As used herein, the term "binder" includes materials that encapsulate the filler, are impregnated with the filler, or otherwise act as a substrate for holding the filler.

[0054] For example, a magnetically lossy material can be formed from materials that are conventionally considered ferromagnetic materials, such as those having a magnetic loss tangent value greater than about 0.05 in the frequency range of interest. The "magnetic loss tangent value" is the ratio of the imaginary part to the real part of the complex dielectric constant of the material. Materials with higher loss tangent values can also be used.

[0055] In some embodiments, the magnetically lossy material can be formed from a binder or matrix material filled with particles, where the particles impart magnetic loss characteristics to the layer. The magnetically lossy particles can be in any convenient form, such as flakes or fibers. Ferrites are common magnetically lossy materials. Materials such as magnesium ferrite, nickel ferrite, lithium ferrite, yttrium garnet, or aluminum garnet can be used. In the frequency range of interest, ferrites generally have a magnetic loss tangent value higher than 0.1. Currently preferred ferrite materials have a loss tangent value between about 0.1 and 1.0 in the frequency range of 1 GHz to 3 GHz, and more preferably have a magnetic loss tangent value higher than 0.5 in this frequency range.

[0056] Actual magnetic lossy materials or mixtures containing magnetic lossy materials can also exhibit dielectric loss or conductive loss effects of useful magnitudes over portions of the frequency range of interest. Similar to the ways in which electrically lossy materials can be formed as described above, suitable materials can be formed by adding magnetic loss-producing fillers to a binder.

[0057] The material can be simultaneously a lossy dielectric or a lossy conductor and a magnetic lossy material. For example, such a material can be formed by using a partially conductive magnetic lossy filler or by using a combination of magnetic lossy fillers and electrically lossy fillers.

[0058] The lossy portion can also be formed in a variety of ways. In some examples, the binder material and the filler can be molded into the desired shape and then fixed in that shape. In other examples, the binder material can be formed into a sheet or other shape from which lossy members of the desired shape can be cut. In some embodiments, the lossy portion can be formed by interleaving layers of lossy and conductive materials such as metal foils. These layers can be firmly attached to each other, for example, by using an epoxy resin or other adhesive, or can be held together in any other suitable way. The layers have the desired shape before they can be fixed to each other, or can be stamped or otherwise shaped after they are held together. As a further alternative, the lossy portion can be formed by plating a plastic or other insulating material with a lossy coating such as a diffused metal coating.

[0059] Figure 3 More details of the connector 110 are shown. In this view, three contacts 118 disassembled from the housing are shown to reveal the structure of the housing in region 4 where these contacts are held adjacent to the outer surface of wall 114A. Region 4 can represent the location where other contacts in the same column are mounted against the outer surface of wall 114A. Other contacts in other columns can be held in the housing in a similar manner adjacent to the inner surface of wall 114A or adjacent to the surface of any other wall.

[0060] In Figure 3 the example, all contacts 118 are stamped from a metal sheet and are formed in the same shape. In this example, the contact 118 has a mounting portion 310, a mating portion 312, and an intermediate portion 314 connecting the mating portion and the mounting portion. Each contact 118 can be formed of a conductive and elastic (spring) material such as phosphor bronze or other copper alloys.

[0061] Each contact 118 is aligned with an area 320 of the connector housing when held within the housing. In this example, the area is defined by ribs 322 formed in the outer surface of wall 114A. Although each contact 118 has the same shape, the contacts can be functionally differentiated based on the configuration of the housing within area 320 where the contacts are held by the housing.

[0062] Figure 4 is an enlarged view of connector 110 that reveals additional details of area 4 identified in Figure 3 the. Figure 4 Area 420 of a first type and area 430 of a second type are shown. Each type of area is defined by ribs 322 and is configured to receive contact 118. In area 420 of the first type, lossy portion 142 is electrically coupled to contact 118. In area 430 of the second type, contact 118 is surrounded by the insulating material of insulating portion 140. For example, area 430 of the second type can be located within island 510A or 510B ( Figure 5 ).

[0063] Area 420 of the first type can include insulating material in addition to the lossy material. Insulating portion 140 is shown extending into the area of the first type. However, in this example, there are sub-areas within area 420 of the first type where the lossy material extends completely through the thickness of base 112. These sub-areas can be formed by protrusions 442A and 442B of the lossy material that extend transversely to mounting surface 130 of connector 110. In this example, protrusions 442A and 442B extend from a flat area of the lossy material that is on lower surface 130 of connector 110 and are perpendicular to mounting surface 130.

[0064] In this example, each of area 420 of the first type and each of area 430 of the second type includes a slot into which contact 118 can be inserted. In an example where each of the areas of the first type and the second type receives a contact 118 having the same shape, slots 424 in the areas of the first type and slots 434 in the areas of the second type can have the same shape. The shape of each of slots 424 and 434 can be configured to receive intermediate portion 314 of contact 118 and hold contact 118 within the housing. Slots 424 and 434 can be arranged in a plurality of parallel columns such that contacts 118 can be held in parallel columns within the housing of connector 110. Each column can be adjacent to and extend parallel to the surface of one of walls 114A - 114D. Within area 4, as in Figure 4As can be seen, there are two slots 424 each in the first type of region 420 and a slot 434 in the second type of region 430, and the slots 424 and 434 are aligned along a column. Here, the elongated dimension of the slots is parallel to the column direction so that the contacts 118 in the column can be aligned edge-to-edge and are configured for edge coupling.

[0065] In this example, the slots 424 and 434 differ in the proximity of lossy material to the slots. Within the first type of region 420, the lossy material defines multiple portions of the slots. In Figure 4 the example of, the protrusions 442A and 442B define the upper portion of the slots. Optionally or additionally, the lossy material located within the blocks (patches) 520A or 520B of lossy material can define the lower portion of the slots. As can be seen in Figure 4 the slots 424 and 434 are elongated and have a width in the column direction, and the protrusions 442A and 442B have a width in the column direction that is less than the width of the slots in the column direction. In the illustrated configuration, the lossy material can be coupled to the contacts 118 in the first type of region 420 without significantly attenuating the signal energy carried by the contacts 118 in the second type of region 430.

[0066] In this example, the first type of region 420 and the second type of region 430 also differ in the shape of the inner surface of the wall 114A that bounds the back surface of the region. The first region has a generally flat back surface 426 and, in this example, is perpendicular to the bottom surface 130. The back surface 426 is indented from the slot 424 so that the contacts 118 inserted into the slot 424 are separated from the back surface 426 by a sufficient distance such that the mating portions 312 of the contacts 118 can deflect towards the surface 426. The deflection of the mating portions 312 creates a force for mating.

[0067] The back surface of the second type of region 430 is configured to position the insulating material of the housing closer to the contacts 118 than a flat surface (such as the back surface 426). This positioning of the insulating material can increase the effective dielectric constant of the material surrounding the contacts 118 in the second type of region 430 and reduce the impedance of the contacts 118 at frequencies within the operating range of the connector 110. As a specific example, the second type of region 430 can be positioned in pairs such that a pair of contacts can be side-by-side to provide an edge-coupled differential pair. The insulating material within each second type of region 430 can be placed to provide a differential impedance within the range of 88 to 92 ohms (e.g., between 90 and 92 ohms) for the pair.

[0068] In Figure 4In the example, by forming the back surface of the second type of region 430 into multiple segments, the insulating material is positioned closer to the contact 118 in the second type of region 430 without interfering with the movement of the mating portion 312 of the contact 118. The top segment 436 is generally parallel to the back surface 426 of the first type of region. The top segment 436 allows the tip of the contact 118 located in the second type of region 430 to have clearance to deflect to the same extent as the contact 118 inserted into the first type of region 420.

[0069] The back surface further includes a tapered segment 438. The tapered segment 438 can be tapered to match the profile of the contact 118 when the contact 118 is deflected during mating. In this example, the bottom of the tapered segment 438 extends substantially to the slot 434 where the contact 118 is anchored and does not deflect during mating. The amount of deflection of the contact can increase along the length of the contact 118 from the anchoring point provided by the slot 434 to the tip. Thus, the tapered segment 438 indents by an increasing amount from the slot 434 until the indentation of the top segment 436.

[0070] Figure 4 Features for achieving a low-profile configuration are also disclosed. The inventors have recognized and realized that tools can be used to reliably insert short contacts that implement a low-profile mezzanine connector. For example, the tool can have pins that align with each contact 118 in the slots to be inserted into the housing. Holes 450 can be included in each contact 118 to receive the pins. Having holes 450 for receiving the pins of the insertion tool enables sufficient and precise control of the downward force applied to the contact 118 to securely seat the contact 118 within the connector housing. Grooves 452 can be included in the tapered segment 438 to provide clearance for the pins inserted through the holes 450. In the assembled connector, the holes 450 are aligned with the grooves 452.

[0071] Figure 5 is a bottom perspective view of the connector 110, which shows additional details of the construction. In this view, solder balls 132 are shown as being fused to some of the mounting portions of some of the contacts 118. For some of the contacts 118, the solder balls are not shown, thus revealing the mounting portions 310 within the recesses 134 in the lower surface 120. For other positions along the columns of the slots for receiving the contacts 118, the contacts are not shown, thus revealing further details of the recesses 134.

[0072] As in Figure 5As can be seen, the base 112 includes islands 510A and 510B of insulating material and blocks (patches) 520A or 520B of lossy material. Each of the islands 510A and 510B of insulating material extends completely through the base 112. Each island is bounded by lossy material on at least three sides over at least a portion of its thickness. The lossy material is located in the blocks 520A and 520B of lossy material. In this example, the blocks 520A and 520B span the lower surface 120.

[0073] In Figure 5 the example, the islands 510A and 510B are mechanically connected as an integral insulating member. Such a configuration can be obtained by forming the insulating portion of the housing in a first molding injection. In this example, each of the blocks 520A surrounds two recesses 134. The block 520B connects the blocks 520A. The blocks 520A and 520B are mechanically connected as an integral lossy member. Although not visible in Figure 5 the projections 442A and 442B can be part of the integral lossy member. Such a configuration can be obtained by forming the lossy portion of the housing in a second molding injection. Such a configuration can also result in a lossy connection between the projections 442A and 442B.

[0074] As visible in Figure 5 the base 112 has a thickness T in a direction perpendicular to the bottom surface 120. For example, the thickness T can be about 1 mm or less, e.g., can be between 0.5 mm and 1.2 mm. The lossy blocks 520A and 520B have a thickness T2, which is a portion of the thickness T. For example, the thickness T2 can be between 10% and 30% of the thickness T. The thickness T2 can be close to the depth of the recesses 134 such that the entire recess can be formed by the lossy material in the block 520A. Such a configuration results in multiple regions of a first type where the insulating material extends partially from a first side to a second side and the lossy material in the blocks 520A and 520B extends partially from a first side to a second side. In this example, there are also multiple regions of a second type interspersed with the multiple regions of the first type where the insulating material in the islands 510A and 510B extends completely from a first side to a second side.

[0075] As in Figure 5As can be seen, the lossy blocks 520A and the insulating island portions 510A can alternate along each column in the array. The contacts 118 that are coupled to the lossy material can be designated as ground conductors. The contacts 118 within the insulating island portions 510A can be designated as signal conductors. The contact pairs in this configuration can carry differential signals, which is a form of high-speed signals in many electronic systems. With these designations, there is a repeating pattern of ground-ground-signal-signal (G-G-S-S) along each column. The pattern for adjacent columns can be staggered (shifted) in the column direction. In this example, adjacent columns are staggered (shifted) by one contact position in the column direction.

[0076] Figure 5 One end of the connector is shown where one end of the columns is visible. It can be seen that every other column starts with a lossy block 520A, such that the column starts with G-G-S-S. The intervening columns start with an island 510B having one contact 118. In some connectors, the single contact 118 within the island 510B can be designated as a low-speed conductor. In many electronic systems, low-speed conductors carry power or ground or control signals or other signals that switch at a low frequency (e.g., about 1 MHz). For columns where the end visible in [ Figure 5 does not start with such a low-speed conductor, the opposite end of the column can end with such a low-speed conductor located within the island 510B.

[0077] Figure 6 Additional details of the lossy material coupled to a subset of the contacts 118 are shown. In this view, a column of contacts 118 in the connector 110 is shown where the insulating portion of the housing is not visible. In this view, it can be seen that the lossy protrusions 442A and 442B are shaped to firmly hold the contacts 118 therebetween. In this example, the protrusion 442B has a flat surface that abuts the rear side of the contact 118. The protrusion 442A can have a narrow portion that abuts the front side of the contact 118. In this example, the narrowed portion is formed by the tapered opposing sides of the protrusion 442A. This configuration can facilitate the displacement of the material of the protrusion 442A when the contact 118 is inserted, thereby ensuring a stable electrical and mechanical connection between the contact 118 and the lossy material of the housing. Also visible is the interconnection of the lossy blocks 520A along the column.

[0078] Figure 7 Additional details of the functional differentiation provided by the first type of region and the second type of region 430 are shown. Figure 7is a portion of the connector housing taken along the column direction through the slots in the column. In this view, it can be seen that slots such as 424 and 434 extend through the base 112 of the housing. For example, the slots extend from the lower surface 120 to the upper surface 720. In this example, the slots extend through the base 112 in a direction perpendicular to each of the surfaces 120 and 720. Walls such as 114A also extend perpendicularly from the surface 720.

[0079] Figure 8 is another view of a portion of the column in the connector 110. In Figure 8 , the thickness T of the insulating portion is marked, but the insulating portion of the connector housing is not shown, thus revealing the lossy portion. Figure 8 Reveals the positioning of the protrusion 442A relative to the specific contact 818, thereby configuring these contacts as ground contacts.

[0080] Other contacts 828 are positioned within the openings 820 in the lossy material where island portions 510A may be formed, thereby configuring the contacts 828 as a pair of signal conductors. Figure 8 Shows the contact 828 separated from the lossy block 520A by a distance S1 and from the lossy protrusion 442A by a distance S2. In this example, S2 is greater than S1. This configuration enables the lossy material to be positioned to couple with the contact 818 while having little or no effect on the high-speed signals carried by the contact 828.

[0081] The inventors infer that the effect of the lossy material on the signal conductor is inversely proportional to the distance between the signal contact and the lossy material near the signal contact, and is proportional to the length of the section of the lossy material near the signal conductor. By Figure 8 The arrangement revealed shows that the lossy protrusion providing high coupling to the ground contact 818 at a relatively large distance T (which might otherwise have a large effect on the signal contact 828) is separated from the signal contact 828 by a relatively large distance. As a result, the effect of the lossy protrusion 442A on the signal contact 828 is low.

[0082] Although the lossy block 520A is closer to the signal contact 828, the lossy block 520A is close to the signal contact over a relatively short distance T2. As a result, the effect of the lossy block 520A on the signal contact 828 is low. Nevertheless, other considerations are met by the design, such as achieving the interconnection between the lossy blocks coupled to the ground contact 818, which improves the signal integrity of the connector and facilitates the manufacturability of the connector. In addition, the recesses located on the lower surface 120 are each formed of a single material, which contributes to reliability.

[0083] Figure 8Additional details of representative contacts 818 and 828 are revealed, which are identical in shape in this example but functionally differentiated by the configuration of the housing. In this example (see also Figure 4 ), the mating portion 312 of each contact is shown to have two regions. In region 812, the mating portion 312 may have a convex surface. Region 814 is generally flat. When the two contacts mate, the convex region 812 of the first contact may be seated against the generally flat region 814 of the second contact, and vice versa. Both mating portions may deflect to produce a normal force of a desired magnitude to ensure good contact. Additionally, the contact design allows for at least 1 mm of wiping of one contact relative to the other, even for a connector with a stack height of 4 mm.

[0084] The inventors have recognized the design of high-speed and high-performance electronic systems using a mezzanine connector constructed by one or more of the techniques described herein. The footprint area on a printed circuit board where a connector such as connector 110 is mounted can be configured to achieve low crosstalk and a precisely controlled impedance that matches the impedance of the connector.

[0085] Figure 9A is a schematic view of the top layer of a printed circuit board (PCB) on which connector 110 can be mounted. This view shows four pads in column C1 to which solder balls 132 can be soldered. In this example, pad 920 is configured to connect to a contact such as contact 818 that is configured as a ground contact. Although not shown in Figure 9A , each pad 920 can be positioned above a via (not shown in Figure 9A ) that extends into the PCB and connects to a ground plane within the PCB. For example, the via can have a drill size of 7 mils to 10 mils (e.g., 8 mils). Pad 920 can be formed by coating the surface of the PCB with a solder mask, with an opening at the location of pad 920. The opening can be centered above the ground via. Subsequently, solder or other metal can be deposited above the opening in the solder mask, where the solder or other metal will adhere to the PCB in the shape of pad 920.

[0086] Pads 930A and 930B can be formed in a similar manner above signal vias 932A and 932B, respectively. These vias can have a drill size of 7 mils to 10 mils (e.g., 8 mils). Signal vias 932A and 932B are connected to signal traces 950A and 950B within the PCB ( Figure 9B ). In this example, pads 930A and 930B are in column C1 with pad 920. In this example, the pads are evenly spaced along the column. For example, the pad-to-pad spacing can be a uniform spacing of 1 mm measured from the center.

[0087] In use, solder balls 132 that are fused to signal contacts such as contact 828 can be aligned with pads 930A and 930B. During a reflow process, these solder balls can be fused to pads 930A and 930B to mount the connector to the PCB. Pads 930A and 930B are electrically coupled to signal vias 932A and 932B, respectively, such that signal contacts connected to mounting pads 930A and 930B via solder balls are connected to signal vias 932A and 932B.

[0088] In this example, signal vias 932A and 932B have a center-to-center spacing, and the center-to-center spacing of signal vias 932A and 932B is different from the center-to-center spacing of pads 930A and 930B to which the solder balls are fused. In this example, the center-to-center spacing of pads 930A and 930B can match the center-to-center spacing of signal contact 828, or if the solder balls fused to signal contact 828 are not centered relative to the contact, the center-to-center spacing of pads 930A and 930B can match the center-to-center spacing of those solder balls. Instead, the center-to-center spacing of signal vias 932A and 932B can be selected to provide a desired impedance within the signal vias. In this example, the spacing between a pair of signal vias is less than the spacing between mounting pads 930A and 930B. For example, such a configuration can provide a differential impedance of 90 ohms + / - 2 ohms within the signal vias.

[0089] Figure 9B It is shown that signal vias 932A and 932B are each offset by a distance O from mounting pads 930A and 930B, respectively. In some examples, the distance O can be in the range of 5 - 15% or 8 - 12% or about 10% of the center-to-center spacing of mounting pads 930A and 930B. As a specific example, the center-to-center spacing of mounting pads 930A and 930B can be approximately 1 mm, while the center-to-center spacing of signal vias 932A and 932B can be 0.8 mm.

[0090] Such a configuration can be achieved by depositing a solder mask having openings through which pads 930A and 930B are formed that are offset relative to signal vias 934A and 934B. In the example shown, each signal via has an associated via pad 934A or 934B. Such pads can be formed during electroplating of the signal vias 932A and 932B and can have a higher copper content than mounting pads 930A and 930B, which can have a higher tin content than via pads 934A and 934B. Nevertheless, mounting pads 930A and 930B and via pads 934A and 934B can have sufficient overlap to provide an electrical connection between them and the signal vias themselves.

[0091] In addition, the footprint area may include one or more black shadow vias 940. The black shadow vias 940 may be connected to a ground plane within the PCB. The black shadow vias may have associated via pads 942, but do not have associated mounting pads in this example. The black shadow vias may improve signal integrity. In this case, four black shadow vias 940 are positioned around a pair of signal vias.

[0092] Figure 9A and Figure 9B The configurations of the signal vias, ground vias, and black shadow vias shown may extend along columns and in parallel columns, where the signal vias and ground vias match the signal contacts and ground contacts of the connector. In addition, the footprint area may include pads aligned with contacts for low-speed signals. These pads may be configured as pads 920 or 930A or 930B. In some examples, the low-speed signal contacts may be connected to a ground plane within the PCB or may be connected to traces.

[0093] The present disclosure is not limited to the details of the construction or the arrangement of the components set forth in the foregoing description and / or the drawings. The various embodiments are provided for illustrative purposes only, and the concepts described herein can be practiced or carried out in other ways. Having described several aspects of at least one embodiment of the invention as such, it should be understood that various changes, modifications, and improvements will readily occur to those skilled in the art.

[0094] For example, the solder balls attached to the contacts are shown as having the same center-to-center spacing as the mating portions of the contacts. This configuration is achieved by aligning the centers of the mating portions and features (e.g., the two "teeth" of the mounting portion of the contact) in a direction perpendicular to the mounting interface of the connector. In other examples, the centerline of the mounting portion may be offset relative to the centerline of the corresponding contact portion. For contacts configured as a differential pair, the centerlines of the mounting portions of the two contacts of the pair may be offset towards each other. In such a configuration, for example, the center-to-center spacing of the contact portions of a pair may be approximately 1 mm, and the center-to-center spacing of the mounting portions of the same pair may be 0.8 mm.

[0095] As another example, the mounting ends of the contacts may be shaped in various ways to accommodate solder ball attachment. The contacts may be bent as Figure 1B shown to facilitate attachment to a surface parallel to the mounting interface of the tail of the connector. Alternatively, the mounting ends may be shaped such that the solder balls are fused to opposite sides of the mounting ends perpendicular to the mounting interface, or preferably to the edges of the mounting ends facing the mounting interface (mounting interface). For example, the mounting ends of the contacts may have solder-wettable edges, and the solder-wettable edges have surfaces that connect to edges having non-solder-wettable (also referred to as anti-wetting) coatings.

[0096] Optionally or additionally, the mounting end of the tail may include protrusions that extend into recesses formed in the surface of the housing and configured to abut against the circuit components for mounting. These protrusions may have solder-wettable edges, which can help attach solder balls to the contacts. The edges can be made solder-wettable by applying a flux (e.g., by using a flux pin transfer technique). Optionally or additionally, the edges can be made solder-wettable by coating the edges with a solder-wettable layer (such as a layer of copper, gold, nickel, nickel vanadium alloy).

[0097] As another example, a lossy material coupled to each column of the multi-column contacts 118 is described as a connector formed as a single piece. In other examples, the lossy material coupled to the contacts in one or a subset of the columns can be formed as separate pieces, resulting in multiple such lossy members within the connector.

[0098] As another example, Figure 2A A portion of a connector having eight columns of contacts is shown. The connector can be formed with more or fewer columns and more or fewer contacts in each column.

[0099] In addition, a connector is shown in which the contacts designated as signal contacts and the contacts designated as ground contacts have the same shape. In the example shown, two ground contacts are positioned between each pair of signal contacts. Optionally, instead of these two ground contacts, a single wider ground contact can be used.

[0100] In Figure 2A the example, there is a column of contacts adjacent to each of the two opposite surfaces of each wall, but in other examples, there may be contacts adjacent to only one surface of some or all of the walls. Additionally, the columns of contacts can extend only along a portion of the wall or at discontinuous regions along the wall.

[0101] As another example, Figure 9A and Figure 9B A circular pad for solder ball attachment is shown. In other examples, the pad can have other symmetric shapes, such as square. However, it is not required that the pad be symmetric.

[0102] As yet another example, Figure 2A and Figure 2B A region of the contacts of a connector is shown. Such a contact region can be associated with other structures in the connector (e.g., Figure 10The combination of the indicated region 1012). In this example, the insulating housing of the connector 1010 includes a peripheral wall 1014 surrounding the region 1012. The second connector 1020 may similarly include a contact region and a peripheral wall 1024. To facilitate the mating of the connectors 1010 and 1020, the peripheral walls 1014 and 1024 may be complementary. In this example, the wall 1024 fits within the perimeter established by the wall 1014.

[0103] Such changes or modifications are intended to be part of this disclosure and are intended to be within the spirit and scope of the present invention. In addition, although the advantages of the present invention are indicated, it should be understood that not every embodiment of the present invention will include every advantage described. Some embodiments may not implement any of the features described as advantageous herein and in some cases. Accordingly, the foregoing description and drawings are provided by way of example only.

[0104] The various aspects of the present invention may be used alone, in combination, or in various arrangements not specifically discussed in the foregoing embodiments, and thus their application is not limited to the details and arrangements of the components set forth in the foregoing description or shown in the drawings. For example, the aspects described in one embodiment may be combined with the aspects described in other embodiments in any manner.

[0105] The use of ordinal terms such as "first", "second", "third", etc. in the claims to modify the claim elements themselves does not mean any priority, precedence, or order of one claim element with respect to another claim element, or the chronological order of acts of performing a method, but is only used as a label to distinguish one claim element having a particular name from another element having the same name (but using an ordinal term) to distinguish claim elements.

[0106] All definitions defined and used herein shall be understood to control dictionary definitions, definitions in documents incorporated by reference, and / or the ordinary meaning of defined terms.

[0107] Unless otherwise expressly stated, the indefinite articles "a" and "an" used in this specification and the claims shall be understood to mean "at least one".

[0108] As used herein in the specification and claims, the phrase "at least one" with respect to a list of one or more elements shall be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each element specifically listed within the list of elements, and not excluding any combination of elements in the list of elements. This definition also allows that elements may optionally exist in addition to those specifically identified within the list of elements referred to by the phrase "at least one", whether related or unrelated to those specifically identified elements.

[0109] As used herein in the specification and claims, the phrase "and / or" shall be understood to mean "either or both" of the elements so combined, i.e., elements that are present conjointly in some cases and separately in other cases. Multiple elements listed together with "and / or" shall be construed in the same manner, i.e., "one or more" of the elements so combined. Other elements may optionally exist in addition to the elements specifically identified by the "and / or" clause, whether related or unrelated to those specifically identified. Thus, as a non-limiting example, when used in conjunction with open-ended language such as "comprising", a reference to "A and / or B" in one embodiment may refer only to A (optionally including elements other than B); in another embodiment, only to B (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements), etc.

[0110] As used herein in the specification and claims, "or" shall be understood to have the same meaning as "and / or" as defined above. For example, when separating items in a list, "or" or "and / or" shall be interpreted inclusively, i.e., including at least one of the plurality of elements or items in the list, but also including more than one, and optionally, additional unlisted items. Terms such as "only one" or "exactly one", or when used in a claim, "consisting of" will refer to exactly one of the elements of the plurality of elements or list of elements. Generally, the term "or" as used herein will be interpreted only as indicating exclusive alternatives (i.e., "one or the other but not both"), when preceded by exclusive terms such as "either", "one", "only one" or "exactly one". When used in a claim, "consisting essentially of" shall have its ordinary meaning as used in the field of patent law.

[0111] Furthermore, the language and terminology used herein are for descriptive purposes and should not be regarded as limiting. The use herein of "including", "comprising" or "having", "containing", "involving" and variations thereof is intended to cover the items listed thereafter and their equivalents as well as additional items.

Claims

1. A low-profile mezzanine connector, comprising: a housing, the housing including insulating material in an insulating portion and lossy material in a lossy portion, the housing including a plurality of slots arranged in a plurality of columns, wherein the lossy portion includes a plurality of protrusions adjacent to a subset of the slots in each of the plurality of columns; and a plurality of contacts, each contact including a portion located in a corresponding one of the plurality of slots.

2. The low-profile mezzanine connector according to claim 1, wherein: the contacts in the subset of the slots in each of the plurality of columns among the plurality of contacts have a first width in the column direction; and the plurality of protrusions have a second width less than the first width in the column direction.

3. The low-profile mezzanine connector according to claim 2, wherein: the protrusions among the plurality of protrusions define opposite sides of each of the plurality of slots in the subset of the slots.

4. The low-profile mezzanine connector according to claim 2, wherein: the housing includes a surface; the plurality of slots extend perpendicular to the surface; the lossy portion includes a first portion extending parallel to the surface; and the plurality of protrusions extend from the first portion in a direction perpendicular to the surface.

5. The low-profile mezzanine connector according to claim 1, wherein: the subset is a first subset of the slots; each of the plurality of columns includes a second subset of slots; and within each of the plurality of columns, the slots are arranged in a repeating pattern, wherein a group of one or more slots in the second subset is disposed between a group of one or more slots in the first subset.

6. The low-profile mezzanine connector according to claim 5, wherein: the housing includes a surface; the plurality of slots extend perpendicular to the surface; the protrusions have a first height in a direction perpendicular to the surface; the lossy material adjacent to the slots in the second subset has a second height in a direction perpendicular to the surface; and the second height is less than the first height.

7. The low-profile mezzanine connector according to claim 5, wherein: the housing includes a base and a plurality of walls extending from the base; the base of the housing includes a plurality of islands of the insulating material extending through the base; the group of one or more slots in the second subset extends through a corresponding one of the plurality of islands; and each of the islands is bounded by the lossy material on at least three sides.

8. The low-profile mezzanine connector according to claim 7, wherein: the base has a first side and a second side opposite the first side; the plurality of slots extend through the base from the first side to the second side; the plurality of walls extend perpendicularly from the first side of the base; the second side of the base includes a plurality of recesses; Each of the plurality of contacts includes a mating portion, a mounting portion, and an intermediate portion connecting the mating portion and the mounting portion; and For each of the plurality of contacts: The intermediate portion is disposed within one of the plurality of slots; The mating portion extends from the base adjacent to one of the plurality of walls; And The mounting portion extends into one of the plurality of recesses.

9. The low-profile mezzanine connector according to claim 8, wherein: One of the first side and the second side of the base includes a block of the lossy portion, and the block of the lossy portion is interspersed with the plurality of islands.

10. The low-profile mezzanine connector according to claim 7, wherein: The lossy portion extends continuously across the base such that a continuous region of lossy material surrounds two or more of the islands.

11. The low-profile mezzanine connector according to claim 10, wherein: The insulating material includes a thermoplastic material filled with non-conductive fibers, and the lossy material includes a thermoplastic material filled with carbon fibers.

12. The low-profile mezzanine connector according to claim 1, wherein: The low-profile mezzanine connector is a first connector; The first connector is mated with a second connector to provide an interconnection having a stack height of 4 mm or less, and the second connector includes: A second housing including an insulating material in an insulating portion and a lossy material in a lossy portion, the second housing including a plurality of slots arranged in a plurality of columns, wherein the lossy portion includes a plurality of protrusions adjacent to a subset of the slots in each of the plurality of columns; and A plurality of contacts, each contact including a portion located in a corresponding one of the plurality of slots.

13. A low-profile mezzanine connector, comprising: A housing including an insulating material in an insulating portion and a lossy material in a lossy portion; And A plurality of contacts arranged in a plurality of columns, wherein: The housing includes a base having a first side and a second side opposite the first side; The housing includes a plurality of walls extending from the first side of the base; Each of the plurality of contacts includes a mating portion, a mounting portion, and an intermediate portion connecting the mating portion and the mounting portion; and For each of the plurality of contacts: The intermediate portion is disposed within the base; The mating portion extends from the base adjacent to one of the plurality of walls; and The base includes: A plurality of first-type regions in which the insulating material partially extends from the first side to the second side and the lossy material partially extends from the first side to the second side; and A plurality of second-type regions interspersed with the plurality of first-type regions, in which the insulating material extends completely from the first side to the second side.

14. The low-profile mezzanine connector according to claim 13, wherein: In the plurality of regions of the first type, the lossy material is exposed at the second side of the base.

15. The low-profile mezzanine connector according to claim 13, wherein: One or more of the plurality of contacts are disposed within corresponding regions of the first type; and Pairs of the plurality of contacts are disposed within corresponding regions of the second type.

16. The low-profile mezzanine connector according to claim 15, wherein: The lossy material located in the corresponding region of the first type is electrically coupled to one or more of the plurality of contacts disposed within the corresponding region of the first type.

17. The low-profile mezzanine connector according to claim 15, wherein: The lossy material located in the corresponding region of the first type contacts one or more of the plurality of contacts disposed within the corresponding region of the first type.

18. The low-profile mezzanine connector according to claim 13, wherein: The lossy material in the plurality of regions of the first type is electrically interconnected.

19. The low-profile mezzanine connector according to claim 18, wherein: The lossy material in the plurality of regions of the first type comprises a thermoplastic material with conductive filler molded into the insulating portion of the housing.

20. The low-profile mezzanine connector according to claim 13, wherein: The low-profile mezzanine connector is a first connector; The first connector is mated with a second connector to provide an interconnection having a stack height of 4 mm or less, the second connector comprising: A second housing, the second housing comprising an insulating material in an insulating portion and a lossy material in a lossy portion; and A plurality of contacts arranged in a plurality of columns, wherein: The second housing comprises a base having a first side and a second side opposite the first side; The housing comprises a plurality of walls extending from the first side of the base; Each of the plurality of contacts comprises a mating portion, a mounting portion, and an intermediate portion connecting the mating portion and the mounting portion; and For each of the plurality of contacts: The intermediate portion is disposed within the base; The mating portion extends from the base adjacent to one of the plurality of walls; and The base comprises: A plurality of regions of the first type, in the plurality of regions of the first type, the insulating material partially extends from the first side to the second side, and the lossy material partially extends from the first side to the second side; A plurality of regions of the second type interspersed with the plurality of regions of the first type, in the plurality of regions of the second type, the insulating material extends completely from the first side to the second side.

21. A low-profile mezzanine connector, comprising: A housing, the housing comprising a base having a first side and a second side opposite the first side, and a plurality of insulating walls extending from the first side of the base; And A plurality of contacts arranged in a plurality of columns, wherein: Each of the plurality of contacts includes a mating portion, a mounting portion, and an intermediate portion connecting the mating portion and the mounting portion; and For each of the plurality of contacts: The intermediate portion is disposed in the base; and The mating portion extends from the base adjacent to one of the plurality of walls; and For at least one subset of the plurality of contacts, a portion of the wall of the plurality of walls adjacent to the contact tapers near the base, thereby reducing the impedance of the contacts in the subset.

22. The low-profile mezzanine connector according to claim 21, wherein: The impedance of the contacts in the second group is between 88 ohms and 92 ohms.

23. The low-profile mezzanine connector according to claim 21, wherein: The subset is a first subset of the plurality of contacts; For a second subset of the plurality of contacts, the wall of the plurality of walls adjacent to the contact is perpendicular to the base.

24. The low-profile mezzanine connector according to claim 23, wherein: The housing further includes a lossy portion adjacent to the contacts in the second subset of the contacts.

25. The low-profile mezzanine connector according to claim 24, wherein: The contacts in the first subset of the contacts and the contacts in the second subset of the contacts have the same shape.

26. The low-profile mezzanine connector according to claim 24, wherein: The contacts in the first subset of the contacts and the contacts in the second subset of the contacts include openings extending through the contacts adjacent to the base.

27. The low-profile mezzanine connector according to claim 26, wherein: The low-profile mezzanine connector is a first connector; The first connector is mated with a second connector to provide an interconnection having a stack height of 4 mm or less, the second connector including: A second housing, the second housing including a base having a first side and a second side opposite the first side, and a plurality of insulating walls extending from the first side of the base; and A plurality of contacts arranged in a plurality of columns, wherein: Each of the plurality of contacts includes a mating portion, a mounting portion, and an intermediate portion connecting the mating portion and the mounting portion; and For each of the plurality of contacts: The intermediate portion is disposed in the base; and The mating portion extends from the base adjacent to one of the plurality of walls; and For at least one subset of the plurality of contacts, a portion of the wall of the plurality of walls adjacent to the contact tapers near the base, thereby reducing the impedance of the contacts in the subset.

28. The mated connector according to claim 27, wherein: The plurality of contacts of the first connector and the plurality of contacts of the second connector are mated to provide at least 15 differential signal connections per square centimeter.

Images