SKEW CONTROLLED LEADFRAME FOR A CONTACT MODULE ASSEMBLY

[0001] The invention relates to a leadframe for a contact module assembly.

[0002] With the ongoing trend toward smaller, faster, and higher performance electrical components such as processors used in computers, routers, switches, etc., it has become increasingly important for the electrical interfaces along the electrical paths to also operate at higher frequencies and at higher densities with increased throughput.

[0003] In a traditional approach for interconnecting circuit boards, one circuit board serves as a back plane and the other as a daughter board. The back plane typically has a connector, commonly referred to as a header, which includes a plurality of signal contacts which connect to conductive traces on the back plane. The daughter board connector, commonly referred to as a receptacle, also includes a plurality of contacts. Typically, the receptacle is a right angle connector that interconnects the back plane with the daughter board so that signals can be routed therebetween. The right angle connector typically includes a mating face that receives the plurality of signal pins from the header on the back plane, and contacts on a mounting face that connect to the daughter board.

[0004] At least some right angle connectors include a plurality of contact modules that are received in a housing. The contact modules typically include a leadframe encased in a dielectric body. The leadframe includes a plurality of terminals that interconnect electrical contacts held on a mating edge of the contact module with corresponding contacts held on a mounting edge of the contact module. Different contact modules of the same connector sometimes have different patterns, sometimes referred to as wiring patterns, of the terminals and/or the mating and mounting edge contacts. For example, adjacent contact modules within the housing may have different patterns of signal, power, and/or ground terminals and/or contacts to enhance the electrical performance of the connector by reducing crosstalk between the adjacent contact modules. However, different leadframes must be designed and manufactured for each of the contact modules having different terminal and/or contact patterns, which may increase the difficulty and/or cost of manufacturing the connector.

[0005] Another problem associated with known right angle contact modules is that the terminals have different lengths between the corresponding contacts. The different lengths of the terminals, particularly with respect to terminals carrying differential signals, provide two different path lengths for the signals. When the differential signals are transmitted along different path lengths, the signal is degraded, also referred to as skew. Signal skew results from a difference in the time that a pair of identical signals takes to get from the mating edge to the mounting edge of the contact module. Skew is typically the result of different electrical lengths, which in turn are the result of different physical lengths of terminals. At least some known contact modules have addressed the skew problem by physically lengthening the shorter terminal of the pair of terminals carrying the differential signals. However, due to the size of the contact assemblies, it is difficult and costly to exactly match the lengths of each of the terminals. As such, skew remains a problem in many contact modules today.

[0006] There is a need to reduce signal skew in a contact module assembly without increasing cost.

[0007] This problem is solved by a leadframe for a contact module assembly, the leadframe comprising a terminal set having first, second and third terminals configured to operate in one of a signal-signal-ground pattern and a ground-signal-signal pattern. Each of the terminals has a length that extends between a mating end and a mounting end. A difference in the lengths between the first terminal and the second terminal is the same as a difference in the lengths between the second terminal and the third terminal such that the terminal set has the same amount of skew between the terminals defining signal contacts in both the signal-signal-ground pattern and the ground-signal-signal pattern.

[0008] The invention will now be described by way of example with reference to the accompanying drawings wherein:

[0009] Figure 1 is a perspective view of an exemplary embodiment of an electrical connector.

[0010] Figure 2 is a rear perspective view of an exemplary housing of the electrical connector shown in Figure 1.

[0011] Figure 3 is a side view of an exemplary embodiment of a contact module that may be used with the electrical connector shown in Figure 1.

[0012] Figure 4 is a side view of an exemplary embodiment of a leadframe for the contact module shown in Figure 3.

[0013] Figure 5 is a side view of a portion of an alternative leadframe similar to the leadframe shown in Figure 4.

[0014] Figure 6 is a side view of the leadframe shown in Figure 5 having a different pattern of terminals.

[0015] Figure 7 is a perspective view of an exemplary embodiment of a commoning member that may be used with the contact module shown in Figure 3.

[0016] Figure 8 is a perspective view of the commoning member shown in Figure 7 mounted on the contact module shown in Figure 3.

[0017] Figure 1 illustrates an exemplary embodiment of an electrical connector 10. While the connector 10 will be described with particular reference to a receptacle connector, it is to be understood that the benefits herein described are also applicable to other connectors in alternative embodiments. The following description is therefore provided for purposes of illustration, rather than limitation, and is but one potential application of the inventive concepts herein.

[0018] The connector 10 includes a dielectric housing 12 having a forward mating end 14 that includes a shroud 16 and a mating face 18. The mating face 18 includes a plurality of mating contacts 20 (shown in Figures 3 and 4), such as, for example, contacts within contact cavities 22, that are configured to receive corresponding mating contacts (not shown) from a mating connector (not shown). The shroud 16 includes an upper surface 26 and a lower surface 28 between opposed sides 30, 32. The upper and lower surfaces 26 and 28, respectively, each include a chamfered forward edge portion 34. An alignment rib 36 is formed on the upper shroud surface 26 and lower shroud surface 28. The chamfered edge portion 34 and the alignment ribs 36 cooperate to bring the connector 10 into alignment with

the mating connector during the mating process so that the contacts in the mating connector are received in the contact cavities 22 without damage.

[0019] The housing 12 also includes a rearwardly extending hood 38. A plurality of contact module assemblies 50 are received in the housing 12 from a rearward end 52. The contact module assemblies 50 define a connector mounting face 54. The connector mounting face 54 includes a plurality of contacts 56, such as, but not limited to, pin contacts, or more particularly, eye-of-the-needle-type contacts, that are configured to be mounted to a substrate (not shown), such as, but not limited to, a circuit board. In an exemplary embodiment, the mounting face 54 is substantially perpendicular to the mating face 18 such that the connector 10 interconnects electrical components that are substantially at a right angle to one another. In one embodiment, the housing 12 holds two or more different types of contact module assemblies 50, such as, but not limited to, contact module assemblies 50A, 5OB. Alternatively, the housing 12 may hold only a single type of contact module assembly 50, such as, but not limited to, any of the contact module assemblies 50A, 50B.

[0020] Figure 2 illustrates a rear perspective view of the housing 12. The housing 12 includes a plurality of dividing walls 64 that define a plurality of chambers 66. The chambers 66 receive a forward portion of the contact module assemblies 50 (Figure 1). A plurality of slots 68 are formed in the hood 38. The chambers 66 and slots 68 cooperate to stabilize the contact module assemblies 50 when the contact module assemblies 50 are loaded into the housing 12. In an exemplary embodiment, the chambers 66 each have about an equal width and the slots 68 each have about an equal width. However, some or all of the chambers 66, and/or some or all of the slots 68, may different widths for accommodating differently sized contact module assemblies 50. The chambers 66 and slots 68 may optionally extend substantially an entire length of the contact module assemblies 50 such that the chamber walls separate adjacent contact module assemblies 50.

[0021] Figure 3 illustrates an exemplary embodiment of one of the contact modules 50 that includes an exemplary embodiment of an internal leadframe 100, shown in phantom outline, and a dielectric body 102. Figure 4 illustrates the leadframe 100 that is held within the contact module 50. The leadframe 100 includes a plurality of terminals 116 enclosed within the body 102. The mating contacts 20 extend from a mating edge portion 104 of the body 102 and the leadframe 100, and the mounting contacts 56 extend from a mounting edge

portion 106 of the body 102 and the leadframe 100. The mating edge portion 104 and the mounting edge portion 106 generally meet at an intersection area 105 proximate a lower- front portion of the contact module 50. In an exemplary embodiment, the mounting edge portion 106 intersects with a rearward facing end wall 107 proximate the mating edge portion 104. Alternatively, the mating edge portion 104 may intersect the mounting edge 106. The mating contacts 20 are positioned successively upward from the intersection area 105, while the mounting contacts are positioned successively rearward from the intersection area 105, however, alternative orientations are possible in alternative embodiments. In the illustrated embodiment, a mating contact 2OA defines a radially inner mating contact, while a mating contact 2OB defines a radially outer mating contact. Similarly, a mounting contact 56A defines a radially inner mounting contact, while a mounting contact 56B defines a radially outer mounting contact.

[0022] The body 102 includes opposite side portions 108 and 110 that extend substantially parallel to and along the leadframe 100. hi some embodiments, the body 102 is manufactured using an over-molding process. During the molding process, the leadframe 100 is encased in a dielectric material, which forms the body 102. As illustrated in Figure 4, prior to over-molding, the leadframe 100 is preferably stabilized by an integral carrier strip 121 which is removed and discarded after the over-molding process that creates the body 102. In an exemplary embodiment, the mating and mounting edge portions 104 and 106, respectively, extend substantially perpendicular to each other. However, the mating and mounting edge portions 104 and 106, respectively, may extend any direction relative to each other, such as, but not limited to, substantially parallel.

[0023] The leadframe 100 includes the plurality of terminals 116 that extend along predetermined paths to electrically connect each mating contact 20 to a corresponding mounting contact 56. The terminals 116 include the mating and mounting contacts 20 and 56, respectively, and an intermediate section 118, which extends between the mating and mounting contacts 20 and 56, respectively. In some embodiments, the intermediate section 118 extends obliquely between the mating and mounting contacts 20 and 56, respectively. For example, in an exemplary embodiment, the intermediate section 118 extends at approximately a forty-five degree angle between the mating and mounting contacts 20 and 56, respectively. The terminals 116 may be either signal terminals, ground terminals, or

power terminals. The leadframe 100 may include any number of terminals 116, any number of which may be selected as signal terminals, ground terminals, or power terminals according the desired pinout selected for the contact module 50. Optionally, adjacent signal terminals may function as differential pairs, and each differential pair may be separated by a ground terminal.

[0024] In an exemplary embodiment, such as illustrated in Figures 3 and 4, each of the terminals 116 includes a necked-down portion 120 that may be engaged to a commoning member 124 (shown in Figure 7), as will be described in more detail below. Optionally, select ones of the terminals 116 are engaged to the commoning member 124 to selectively interconnect those terminals 116. The dielectric body 102 includes a plurality of openings 126 that each exposes the necked-down portion 120 of a corresponding one of the terminals 116. Portions of the commoning member 124, such as tabs, may extend into the openings 126 to engage the terminals 116. Alternative configurations are possible that enable the terminals 116 to directly physically engage and electrically connect to the commoning member 124. For example, the terminals 116 may include openings therein for receiving portions of the commoning member 124.

[0025] Figure 5 is a side view of an alternative leadframe 100 similar to the leadframe 100 shown in Figure 4, and includes like elements having like reference numerals. The leadframe illustrates the intermediate sections 118 of the terminals 116. As described above, the intermediate sections 118 extend between the mating contacts 20 (shown in Figure 4) and the mounting contacts 56 (shown in Figure 4). The intermediate sections 118 each include a first transition section 140 and a second transition section 142. Additional transition sections may also be provided.

[0026] The first transition section 140 generally extends between the mating contact 20 and the second transition section 142. The first transition section 140 includes a mating contact end 144 and a second transition section end 146. Similarly, the second transition section 142 generally extends between the mounting contact 58 and the first transition section 140. The second transition section 140 includes a mounting contact end 148 and a first transition section end 150.

[0027] In an exemplary embodiment, the terminals 116 are arranged in terminal sets, such as the terminal sets TSi - TS ₅ . The terminal sets TS _f - TS ₅ each include three terminals, namely a first or outer terminal, a second or middle terminal, and a third or inner terminal, numbered Ti-T ₃ , respectively. Each of the terminal sets include signal terminals, ground terminals, or power terminals arranged in patterns. For example, in the illustrated embodiment, the terminal sets TSi - TS ₅ are arranged in a first pattern of ground and signal terminals. When viewed from the outer terminal Ti to the inner terminal T ₃ , the terminals 116 are arranged as signal, signal and ground terminals, respectively. Such a pattern is referred to hereinafter as a signal-signal-ground pattern. Other patterns are possible in alternative embodiments. For example, the terminal sets may include more than three terminals, such as four terminals, arranged in one of a signal-signal-ground-ground, a ground- signal-signal-ground, a ground-ground-signal-signal and a ground-signal-ground-signal pattern. The terminal sets may include more terminals in alternative embodiments, and adjacent terminal sets may include different numbers of terminals therein in alternative embodiments. Optionally, only one terminal set may be provided.

[0028] Figure 6 illustrates the same intermediate sections 118 of the leadframe 100 arranged in a second, different pattern. The terminal sets TSi - TS ₅ are arranged in a second pattern of ground and signal terminals. When viewed from the outer terminal Ti to the inner terminal T ₃ , the terminals 116 are arranged as ground, signal, and signal terminals, respectively. Such a pattern is referred to hereinafter as a ground-signal-signal pattern. As shown with reference to Figures 5 and 6, the leadframe 100 may be used in two different pinouts when mated with contacts of mating connectors by providing multiple terminal patterns. Additionally, the terminals 116 may be arranged in more than two patterns, depending on the pinouts of the mating connectors.

[0029] Returning to Figure 5, the terminals 116 within the terminal sets TSi - TS ₅ have different lengths. When referring to the length of the terminal 116, the length may define either the physical length of the terminal or the electrical length of the terminal. The electrical length is determined based on factors such as the physical length, the dielectric, the material of the terminal, and the like. The length relates to the amount of skew in that a signal requires more time to travel along a longer terminal than a shorter terminal. In the illustrated embodiment, referring to the physical length of the terminals 116, each of the first

transition portions 140 may have a first transition length 152 and each of the second transition portions 142 may have a second transition length 154. The first transition length 152 is less than the second transition length 154. Optionally, the first transition length 152 may be substantially less than the second transition length 154. A section length of each intermediate section is the sum of the lengths 152, 154. Generally, the section lengths of inner ones of the terminal sets (e.g. ones closer to the intersection area 105) are shorter than outer ones of the terminal sets (e.g. ones further from the intersection area 105). The section lengths of terminals 116 within a given terminal set are approximately the same to reduce skew created between the terminals 116 within the terminal set. However, the section lengths may not be exactly equal due to physical size constraints of the body section 102 (shown in Figure 3), but may be within an acceptable tolerance.

[0030] In the illustrated embodiment, referring specifically to the outermost terminal set TS ₁ , the second transition portion 142 of the outer terminal Ti has a first length 156 between the ends 148, 150, the second transition portion 142 of the middle terminal T ₂ has a second length 158 between the ends 148, 150 shorter than the first length 156, and the second transition portion 142 of the inner terminal T ₃ has a third length 160 between the ends 148, 150 shorter than the second length 158. Optionally, the difference between the lengths 156 and 158 (outer and middle) may be approximately the same as the difference between the lengths 158 and 160 (middle and inner). The difference between the lengths 156 and 158 (between the two signal terminals within the terminal set TSi) corresponds to a predetermined amount of skew potentially created within the second transition portion 142. Similarly, referring to Figure 6, the difference between the lengths 158 and 160 (between the two signal terminals within the terminal set TSj) corresponds to a predetermined amount of skew potentially created within the second transition portion 142.

[0031] The first transition portion 140 of the outer terminal Ti has a first length 162 between the ends 144, 146, the first transition portion 140 of the middle terminal T ₂ has a second length 164 between the ends 144, 146 longer than the first length 162, and the first transition portion 140 of the inner terminal T ₃ has a third length 166 between the ends 144, 146 longer than the second length 164. As such, the inner terminal T ₃ , which has the shortest overall section length, has the longest first section portion 140 to make up for the shorter overall length. The difference between the lengths 162, 164 (between the two signal

terminals within the terminal set TSi) corresponds to a predetermined amount of skew potentially created within the first transition portion 140. However, the skew potentially created within the first transition portion 140 is generally opposite to, and attempts to compensate for, the skew potentially created within the second transition portion 142. As such, the total amount of skew between the signal terminals of the terminal set TS ₁ having the signal-signal-ground pattern is reduced by lengthening the middle terminal T ₂ .

[0032] Similarly, referring to Figure 6, the middle terminal T ₂ , which has a shorter overall section length than the outer terminal T ₁ , has a longer first section portion 140 to make up for the shorter overall section length of the middle terminal T ₂ as compared to the outer terminal T ₁ . The difference between the lengths 164, 166 (between the two signal terminals within the terminal set TS ₁ ) corresponds to a predetermined amount of skew potentially created within the first transition portion 140. However, the skew potentially created between the middle terminal T ₂ as compared to the inner terminal T ₃ within the first transition portion 140 is generally opposite to, and attempts to compensate for, the skew potentially created within the second transition portion 142. As such, the total amount of skew between the signal terminals of the terminal set TSi having the ground-signal-signal pattern is reduced by lengthening the inner terminal T ₃ .

[0033] In an exemplary embodiment, the lengths 162, 164 and 166 of the first transition portions 140 of the terminals 116 are selected such that the difference between the lengths 162, 164 of the outer terminal Ti and the middle terminal T ₂ are substantially the same as the difference between the lengths 164, 166 of the middle terminal T ₂ and the inner terminal T ₃ . As such, the terminal set TS ₁ has substantially the same amount of skew reduction created within the first transition portions 140 between the terminals 116 defining the signal contacts independent of the pinout or pattern. For example, the skew reduction created within the first transition portions 140 between the signal terminals Ti and T ₂ in the signal-signal-ground pattern is substantially the same as the skew reduction created within the first transition portions 140 between the signal terminals T ₂ and T ₃ in the ground-signal- signal pattern. Thus, the leadframe 100 may be used independent of the pinout and have substantially the same electrical performance and characteristics.

[0034] Optionally, the first transition portion 140 of the middle terminal T ₂ may be longer than the first transition portion 140 of the outer terminal Ti by a first amount, and the

first transition portion 140 of the third terminal T ₃ may be longer than the first transition portion 140 of the first terminal T ₁ by a second amount that is approximately twice the first amount. The lengths 162, 164 and 166 of the first transition portions 140 of the terminals 116 may be selected such that the difference between the overall section lengths of the outer terminal Ti and the middle terminal T ₂ is approximately zero and the difference between the overall section lengths of the middle terminal T ₂ and the inner terminal T ₃ is approximately zero. As such, the overall skew may be substantially eliminated.

[0035] In an exemplary embodiment, the first transition portions 140 are also used to control a pitch between each of the terminals 116 within a given terminal set (e.g. TSi) and/or to control the pitch between each of the terminals within all of the terminal sets (e.g. TSi-TS ₅ ). Again, with reference to the first terminal set TS ₁ , the mating contact ends 144 extend along a common plane extending perpendicularly with respect to the terminals 116 at the mating contact ends 144. The terminals 116 are each spaced apart from one another by a predetermined first pitch 170 at the mating contact ends 144. Similarly, the second transition portion ends 146 of each terminal 116 within a terminal set extend along a common plane extending perpendicularly with respect to the terminals 116 at the second transition portion ends 146. The terminals 116 are each spaced apart from one another by a predetermined second pitch 172 at the second transition portion ends 146. The second pitch 172 is less than the first pitch 170. Optionally, the terminals may substantially maintain the second pitch 172 along the second transition portion 142. Optionally, each of the terminals 116 within all of the terminal sets may have substantially the same first pitch 170 and/or substantially the same second pitch 172. The change in pitch may be accomplished by changing the length of the terminals 116 within the first transition portions 140.

[0036] Figure 7 is a perspective view of an exemplary embodiment of the commoning member 124. Figure 8 is a perspective view of the commoning member 124 mounted on the contact module 50. The commoning member 124 may be fabricated in a similar manner and may be used in a similar manner as the commoning member described and illustrated in the copending U.S. Patent Application titled "ELECTRICAL CONNECTOR WITH PROGRAMMABLE LEAD FRAME", the disclosure of which is incorporated by reference herein.

[0037] The commoning member 124 includes a body 232 having opposite side portions 234 and 236, which extends parallel to the leadframe 100 (shown in Figure 4) when the commoning member 124 is mounted on the contact module 50. The commoning member 124 also includes a plurality of the electrically conductive tabs 222 extending outwardly on the side portion 234. In the exemplary embodiment of Figure 7, the tabs 222 are each insulation displacement contacts (IDCs) that include a forked portion 240 that defines an. opening 242.

[0038] When the commoning member 124 is mounted on the contact module, the necked-down portion 120 (Figures 3 and 4) of the corresponding terminal 116 (Figures 3 and 4) is received within the opening 242 and engages the forked portion 240 of each tab 222 to directly physically engage and electrically connect the tab 222 to the corresponding terminal 116. However, the tabs 222 may each be any suitable type of electrical contact. The commoning member 124 may have any number of the tabs 222, and the tabs 222 may have any suitable relative arrangement and/or pattern on the commoning member 124 that configures the leadframe 100 with the desired pattern of commoned terminals 116. For example, the tabs 222 may be configured to engage all or at least a sub-set of the terminals 116 that define ground terminals, such that each of the ground terminals may be electrically commoned. Additionally, different commoning members 124 may be used, depending on the pinout pattern of the contact module 50. For example, a first commoning member 124, having a particular pattern of tabs 222, is used with a signal-signal-ground pattern and a second commoning member 124, having a different pattern of tabs 222, is used with a ground-signal-signal pattern.

[0039] The contact module and leadframe embodiments described and/or illustrated herein provide contact modules having a leadframe structure that may be selectively programmable with a plurality of different wiring patterns. Specifically, each of the leadframe terminals 116 is selectively configurable as a signal terminal, a ground terminal, or a power terminal. The leadframe 100 is designed to control the skew between adjacent signal terminals carrying differential pair signals. For example, within each terminal set (e.g. a single ground terminal and two signal terminals), the skew between adjacent ones of the terminals are controlled within the first transition portion 140 to make up for the skew created within the second transition portion 142. The lengths of the first transition portions 140 are

controlled such that the amount of skew between each of the terminals within a terminal set is reduced by substantially the same amount independent of the pattern. For example, the skew between the signal contacts in the signal-signal-ground pattern is the same as the skew between the signal contacts in the ground-signal-signal pattern. Thus, the leadframe 100, by specifically controlling lengths of the terminals within the first transition portion, is adapted for compensating for intra-set skew, or skew within a given terminal set. hi an exemplary embodiment, the leadframe 100, within the first transition portions, reduces the skew by an equal amount, in that the skew is reduced by substantially the same amount within an acceptable tolerance. The leadframe 100 may be used independent of the pinout and has the same electrical performance and characteristics within different pinouts. Optionally, commoning members 124 may be used to interconnect certain ones of the terminals 116 depending on the pattern.