Connector molding method and shielded waferized connector made therefrom

[0001] BACKGROUND OF THE INVENTION

[0002] This invention relates generally to electrical interconnects and more specifically to high speed, high density electrical connectors used to interconnect printed circuit boards.

[0003] Modem electronic circuitry is often built on printed circuit boards. The printed circuit boards are then interconnected to create a complete system, such as a computer work station or a router for a communications network. Electrical connectors are often used to make the interconnections. In general, the connectors come in two pieces, with one piece on each board. The connector pieces mate to provide signal paths between the boards.

[0004] A good connector must have a combination of several properties. It must provide signal paths with appropriate electrical properties such that the signals are not unduly distorted as they move between boards. In addition, the connector must ensure that the pieces mate easily and reliably. Further, the connector must be rugged, so that it is not damaged by handling of the printed circuit boards. In many systems, it is also important that the connectors have a high density, meaning they can carry a large number of electrical signal per unit length.

[0005] Examples of very successful high speed, high density electrical connectors are the VHDM™ and VHDM-HSD™ connectors sold by Teradyne Connection Systems of Nashua, N.H., USA.

[0006] It would, however, be desirable to provide an even better electrical connector. It is also desirable to provide simplified methods of manufacturing connectors.

SUMMARY OF THE INVENTION

[0007] It is an object of the present invention to provide an improved high speed, high density electrical connector.

[0008] The foregoing and other objects are achieved in an electrical connector assembled from wafers. Each wafer includes a shield member, signal members and an insultaive housing. The wafers are formed in a plurality of molding steps that encapsulate the shield member and signal members in the insulative housing in a predetermined relationship.

[0009] In the preferred embodiment, insulator is molded around the shield, leaving spaces to receive the signal contacts. The signal contacts are then placed into the spaces and a second molding operation is performed, leaving an interlocked molded housing.

[0010] According to other features of the preferred embodiment, the shield and plastic housing are shaped to provide mechanical integrity for the wafers.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a shielded waferized connector, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. For clarity and ease of description, the drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.

[0012]FIG. 1 is a diagram of a two piece, modular electrical connector.

[0013]FIG. 2 is a diagram of a wafer of FIG. 1 assembled according to one embodiment of the invention.

[0014]FIG. 3 is a diagram of a shield plate.

[0015]FIG. 4 is a diagram of a wafer subassembly including the shield plate of FIG. 3.

[0016]FIG. 5 is a diagram of a signal lead frame.

[0017]FIG. 6 is a diagram of the signal lead frame of FIG. 5 positioned on the wafer subassembly of FIG. 4.

[0018]FIG. 7 depicts the assembly of FIG. 6 after the signal lead frame carrier strip tie bars have been severed.

[0019]FIG. 8 is a diagram showing the wafers mated with the backplane connector;

[0020]FIG. 9 shows the wafers mated with the backplane connector from the reverse angle; and

[0021]FIG. 10 shows an exploded view of alternative embodiment of the backplane connector.

DETAILED DESCRIPTION OF THE INVENTION

[0022] Referring to FIG. 1, a two piece electrical connector <b>100</b> is shown to include a backplane connector <b>105</b> and a daughtercard connector <b>110</b>. The backplane connector <b>105</b> includes a backplane shroud <b>102</b> and a plurality of signal contacts <b>112</b>, here, arranged in an array of differential signal pairs. A single-ended ended configuration of the signal contacts <b>112</b> is also contemplated. In the illustrated embodiment, the backplane shroud <b>102</b> is molded from a dielectric material such as a liquid crystal polymer (LCP), a polyphenyline sulfide (PPS) or a high temperature nylon.

[0023] The signal contacts <b>112</b> extend through a floor <b>104</b> of the backplane shroud <b>102</b> providing a contact area both above and below the floor <b>104</b> of the shroud <b>102</b>. Here, the contact area of the signal contacts <b>112</b> above the shroud floor <b>104</b> are in the form of a blade contact <b>106</b>. The tail portion <b>114</b> contact area of the signal contact <b>112</b> which extends below the shroud floor <b>104</b> here, is in the form of a press fit, “eye of the needle” compliant contact. However, other configurations are also suitable such as surface mount elements, spring contacts, solderable pins, etc. In a typical configuration, the backplane connector <b>105</b> mates with the daughtercard connector <b>110</b> at the blade contacts <b>106</b> and connects with signal traces in a backplane (not shown) through the tail portions <b>114</b> which are pressed into plated through holes in the backplane.

[0024] The backplane shroud <b>102</b> further includes side walls <b>108</b><i>a</i>, <b>108</b><i>b </i>which extend along the length of opposing sides of the backplane shroud <b>102</b>. The side walls <b>108</b><i>a</i>, <b>108</b><i>b </i>include grooves <b>118</b> which run vertically along an inner surface of the side walls <b>108</b><i>a</i>, <b>108</b><i>b</i>. Grooves <b>118</b> serve to guide the daughter card connector <b>110</b> into the appropriate position in shroud <b>102</b>. Running parallel with the sides walls <b>108</b><i>a</i>, <b>108</b><i>b </i>are a plurality of shield plates <b>116</b> located here, between rows of pairs of signal contacts <b>112</b>. In a presently preferred single ended configuration, the plurality of shield plates <b>116</b> would be located between rows of signal contacts <b>112</b>. However, other shielding configurations could be formed, including having the shield plates <b>116</b> running between the walls of the shrouds, transverse to the direction illustrated.

[0025] Each shield plate <b>116</b> includes a tail portion <b>117</b> which extends through the shroud base <b>104</b>. Here, the tail portion <b>117</b> is formed as an “eye of the needle” compliant contact which is press fit into the backplane however, other configurations are also suitable such as surface mount elements, spring contacts, solderable pins, etc.

[0026] The daughtercard connector <b>110</b> is shown to include a plurality of modules or wafers <b>120</b> which are supported by a stiffener <b>130</b>. Each wafer <b>120</b> includes features <b>44</b> which are inserted into apertures (not numbered) in the stiffener to locate each wafer <b>120</b> with respect to another and further to prevent rotation of the wafer <b>120</b>.

[0027] Referring now to FIG. 2, a single wafer is shown. Wafer <b>120</b> is shown to include a dielectric housing <b>132</b>, <b>134</b> which is formed around both a daughtercard shield plate <b>10</b> (FIG. 3) and a signal lead frame <b>60</b> (FIG. 5). A preferred manner of forming the dielectric housing around the shield plate <b>10</b> and signal lead frame <b>60</b> will be discussed in detail in conjunction with FIGS. <b>3</b>-<b>9</b>.

[0028] Extending from a first edge of each wafer <b>120</b> are a plurality of signal contact tails <b>128</b><i>a</i>-<b>128</b><i>d</i>, which extend from the signal lead frame <b>60</b>, and a plurality of ground contact tails <b>122</b><i>a</i>-<b>122</b><i>d</i>, which extend from a first edge of the shield plate <b>10</b>. In the preferred embodiment, the plurality of signal contact tails <b>128</b><i>a</i>-<b>128</b><i>d </i>and the plurality of ground contact tails <b>122</b><i>a</i>-<b>122</b><i>d </i>are arranged in a single plane.

[0029] Here, both the signal contact tails <b>128</b><i>a</i>-<b>128</b><i>d </i>and the ground contact tails <b>122</b><i>a</i>-<b>122</b><i>d </i>are in the form of press fit “eye of the needle” compliants which are pressed into plated through holes located in a printed circuit board (not shown). Other configurations for the signal contact tails <b>128</b><i>a</i>-<b>128</b><i>d </i>and ground contact tails <b>122</b><i>a</i>-<b>122</b><i>d </i>are also suitable such as surface mount elements, spring contacts, solderable pins, etc. Here, the signal contact tails <b>128</b> are configured to provide a differential signal and, to that end, are arranged in pairs <b>128</b><i>a</i>-<b>128</b><i>d. </i>

[0030] Near a second edge of each wafer <b>120</b> are mating contact regions <b>124</b> of the signal contacts which mate with the signal contacts <b>112</b> of the backplane connector <b>105</b>. Here, the mating contact regions <b>124</b> are provided in the form of dual beams to mate with the blade contact <b>106</b> end of the backplane signal contacts <b>112</b>. The mating contact regions are positioned within openings in dielectric housing <b>132</b> to protect the contacts. Openings in the mating face of the wafer allow the signal contacts <b>112</b> to also enter those openings to allow mating of the daughter card and backplane signal contacts.

[0031] To carry a differential signal, the beams <b>124</b> are configured in pairs <b>124</b><i>a</i>-<b>124</b><i>d, </i><b>124</b><i>a</i>′-<b>124</b><i>d</i>′. In a single-ended configuration, the beams <b>124</b> are not provided in pairs.

[0032] Provided between the pairs of dual beam contacts <b>124</b> and also near the second edge of the wafer are shield beam contacts <b>126</b><i>a</i>-<b>126</b><i>c</i>. Shield beam contacts are connected to daughter card shield plate <b>10</b> and are preferably formed from the same sheet of metal used to from shield plate <b>10</b>. Shield beam contacts <b>126</b><i>a </i>. . . <b>126</b><i>c </i>engage an upper edge of the backplane shield plate <b>116</b> when the daughter card connector <b>110</b> and backplane connector <b>105</b> are mated. In an alternate embodiment (not shown), the beam contact is provided on the backplane shield plate <b>116</b> and a blade is provided on the daughtercard shield plate <b>10</b> between the pairs of dual beam contacts <b>124</b>. Thus, the specific shape of the shield contact is not critical to the invention.

[0033] As mentioned above, the wafers include a dielectric housing <b>132</b>, <b>134</b>. The wafers <b>120</b> are, in the preferred embodiment, produced by a two step molding process. The first housing <b>132</b> of dielectric material is formed over the top surface of the daughtercard shield <b>10</b>. The signal lead frame <b>60</b> (FIG. 5) is placed on the surface of the first housing <b>132</b> and the second dielectric housing <b>134</b> is formed over the signal lead frame <b>60</b>, encapsulating the signal lead frame <b>60</b> between the first and second dielectric housings <b>132</b>, <b>134</b>. The two-step molding process is described in further detail in conjunction with FIGS. <b>3</b>-<b>9</b>.

[0034] Referring now to FIG. 3, the daughtercard shield <b>10</b> is shown attached to a carrier strip <b>12</b>. Typically, a plurality of daughtercard shields are provided on a carrier strip <b>12</b> which can be fed into assembly equipment. The carrier strip <b>12</b> is shown to include a series of apertures. Here, the apertures located at each end of the carrier strip are used as alignment holes <b>13</b>. In a preferred embodiment, the plurality of shields and the carrier strip are stamped and formed from a long sheet of metal.

[0035] In the illustrated embodiment, the daughtercard shield <b>10</b> is attached to the carrier strip <b>12</b> at two locations, generally referred to as tie bars <b>14</b><i>a, </i><b>14</b><i>b. </i>Adjacent shields <b>10</b> are attached at points indicated by carrier strips <b>30</b><i>a </i>and <b>30</b><i>b. </i>The carrier strips <b>14</b> and <b>30</b> are left in place to provide mechanical support and to aid in handling the wafer during manufacturing, but are severed at any convenient time before daughter card connector <b>110</b> (FIG. 1) is assembled.

[0036] Various features are formed into daughter card shield <b>10</b>. As described above, dielectric housing <b>132</b> is molded on the upper surface of shield <b>10</b>. A plurality of tabs <b>18</b> and <b>20</b> are formed in shield <b>10</b> and bent above the upper surface. When dielectric housing <b>132</b> is molded on this surface of shield plate <b>10</b>, tabs <b>18</b> and <b>20</b> become embedded in dielectric housing and secure shield <b>10</b> to dielectric housing <b>132</b>. Thus, these features enhance the mechanical integrity of the wafer <b>120</b>.

[0037] A second group of tabs <b>320</b> is also formed on the upper surface of shield <b>10</b>. As will be shown more clearly in connection with FIG. 4, tabs <b>320</b> become embedded in dielectric housing <b>134</b> and further promote mechanical integrity of wafer <b>120</b> by ensuring the shield and both dielectric housings are secured together.

[0038] Additionally, tabs <b>318</b> are formed from the plate. Tabs <b>318</b> serve multiple purposes. As with tabs <b>18</b>, <b>20</b> and <b>320</b>, tabs <b>318</b> assist in securing the plate <b>10</b> to the dielectric housing. Additionally, tabs <b>318</b> serve as a point of attachment for contact tails <b>122</b><i>a </i>. . . <b>122</b><i>d</i>. Because tabs <b>318</b> are bent above the plane of shield <b>10</b>, contact tails <b>122</b><i>a </i>. . . <b>122</b><i>d </i>align with signal contact tails <b>128</b><i>a </i>. . . <b>128</b><i>d </i>to form a single column of contact tails for each wafer. As a further benefit, tabs <b>318</b> position the contact tails <b>122</b><i>a </i>. . . <b>122</b><i>d </i>within the dielectric housing and make them less susceptible to bending when the contact tails <b>122</b><i>a </i>. . . <b>122</b><i>d </i>are pressed into a printed circuit board. As a result, the connector is more robust.

[0039] Ring <b>16</b> is an example of an alignment feature that can be used during manufacture of the connector elements. At various steps in the manufacture of the connector, the components need to be aligned relative to tooling or to each other.

[0040] For example, the shield <b>10</b> needs to be aligned relative to the mold or to tools when selective metalization of the contract regions on the shield plate are required. Ring <b>16</b> is outside of the path of the signal contacts and therefore has little impact on the shielding effectiveness of shield <b>10</b> and is preferably severed when no longer needed for alignment. Ring <b>16</b> includes tabs (not numbered) that become embedded into the housing to hold ring <b>16</b> in place after it is severed, thereby keeping ring <b>16</b> from interfering with operation of the connector.

[0041] Shield <b>10</b> contains additional features. Holes <b>22</b> are included in shield plate <b>10</b> to allow access to the internal portions of wafer <b>120</b> at later steps of the manufacturing operation. Their use is described later in conjunction with FIG. 7.

[0042] The front edge of shield plate <b>10</b> includes slots <b>332</b>. Each of the slots <b>332</b> receives a backplane shield <b>116</b> when the connector pieces are mated. Also, the metal cut out to form the slot <b>332</b> is formed into a shield beam contact <b>126</b>.

[0043] Because cutting slots <b>332</b> reduces the mechanical integrity of the front of shield <b>10</b>, raised portions <b>330</b> and raised ribs <b>333</b> can be formed near the front edge of shield <b>332</b>. Forming raised portions increases the stiffness of the shield in this region. The raised portions also move the shield plate <b>10</b> of one wafer away from the adjacent wafer and create a recessed area. During molding, the recessed area becomes filled with molding material to create a dielectric region (element <b>912</b>, FIG. 9). As shown in FIG. 1, signal contacts <b>124</b> are exposed at the top of the wafer. When the daughter cared and backplane connectors mate, blades <b>106</b> will press signal contacts <b>124</b> will be biased upward, or toward the shield plate of the adjacent wafer. Dielectric region <b>912</b> prevents the signal contacts on one wafer from contacting the shield plate of the adjacent wafer.

[0044] In the illustrated embodiment, slot <b>332</b> does not extend the entire length of raised portions <b>330</b>. There is a flat region <b>331</b> above each slot <b>332</b>. Flat region <b>331</b> is included for engaging a backplane connector having a castellated upper edge as shown in FIG. 1.

[0045] Holes <b>26</b> are also included in the plate in raised portions <b>330</b>. As dielectric housing <b>132</b> is molded onto shield <b>10</b>, dielectric material will flow through holes <b>26</b>, thereby locking the dielectric to the shield <b>10</b>, providing greater stiffness at the front end of the connector. Holes <b>24</b> are also included in shield <b>10</b>. Holes <b>24</b>, like holes <b>26</b>, are used to lock the pieces of the connector together. Holes <b>24</b> are filled when dielectric housing <b>134</b> is molded, thereby locking dielectric housing to shield <b>10</b>.

[0046] Shield <b>10</b> also may include features to increase the signal integrity of the connector. Projections <b>28</b><i>a </i>and <b>28</b><i>b </i>are included to provide shielding around the end row contacts. When the connector halves are mated, the interior mating contact regions <b>124</b><i>b </i>and <b>124</b><i>c </i>will each be between shield plates <b>116</b> from the backplane connector. However, the exterior mating contact regions <b>124</b><i>a </i>and <b>124</b><i>d </i>will each have a shield plate <b>116</b> from the backplane connector on only one side. Because the spacing and shape of the ground conductors around a conductor influence the signal carrying properties of that conductor, it is sometimes desirable to have grounded conductors on all sides of a conductor, particularly in the mating contact region.

[0047] For the interior mating contact regions <b>124</b><i>b </i>and <b>124</b><i>c, </i>the shield <b>10</b> of the wafer <b>120</b> in which the signal contacts are attached and the shield <b>10</b> of the adjacent wafer provide a ground plane on two sides of the mating contacts. The other two sides are shielded by two of the backplane shields <b>116</b>, to create a grounded-box around the mating portions of the signal conductors. For the exterior mating contact portions, a grounded box around the mating portions is also created, with the four sides being made up of the shields <b>10</b> from two adjacent wafers <b>120</b>, a backplane shield <b>116</b> and one of the projections <b>28</b><i>a </i>or <b>28</b><i>b</i>. Thus, the exterior mating contact portions <b>124</b><i>a </i>and <b>124</b><i>d </i>benefit from ground conductors on all four sides. Overall, it is desirable that all signal conductors have symmetric shielding that is similar for all pairs of conductors.

[0048] Turning now to FIG. 4, a wafer in the next step of manufacture is shown. In this figure, dielectric housing <b>132</b> is shown molded over a shield <b>10</b>. Insert molding is known in the art and is used in the connector art to provide conductors within a dielectric housing. In contrast with prior art connectors, dielectric material is molded over the majority of the surface of shield <b>10</b>. Additionally, the dielectric is largely on the upper surface of shield, leaving the lower surface of the shield exposed.

[0049] Tabs <b>18</b>, <b>318</b> and <b>20</b> are not visible in FIG. 4. Tabs <b>18</b>, <b>318</b> and <b>20</b> are embedded in dielectric housing <b>132</b>. Tabs <b>322</b> are visible because dielectric housing <b>132</b> is molded to leave windows <b>424</b> around tabs <b>322</b>. Likewise, holes <b>22</b> and <b>24</b> are visible because no dielectric housing has been molded around them. Holes <b>26</b> are not visible, however, because dielectric housing <b>132</b> has been molded to fill those holes and to fill the open spaces behind raised portions <b>330</b>.

[0050] Various features are molded into dielectric housing <b>132</b>. Cavity <b>450</b> bounded by walls <b>452</b> is left generally in the central portions of the housing <b>132</b>. Channels <b>422</b> are formed in the floor of cavity <b>450</b> by providing closely spaced projecting portions of dielectric housing. As shown more clearly in FIG. 6, channels <b>422</b> are used to position signal conductors. Also, openings <b>426</b> are molded to allow a mating contact area for each signal contact. The front face of dielectric housing <b>132</b> creates the mating face of the connector and contains holes to receive blades <b>106</b> from the backplane connector, as is known in the art. The walls of opening <b>426</b> protect the mating contact area.

[0051] In the illustrated embodiment, the floor of opening <b>426</b> has a recess <b>454</b> formed therein. Shield plate <b>10</b> is visible through recess <b>454</b>. When the connector pieces are mated, a blade <b>106</b> enters opening <b>426</b> through the front mating face and is pressed against the floor of opening <b>426</b> by a signal contact <b>124</b>. Thus a recess <b>454</b> will be between the blade <b>106</b> and the shield, leaving an air space. The air space formed by recess <b>454</b> increases the impedance of the signal path in the vicinity of the mating interface, which is otherwise a low impedance section of the signal path. It is desirable to have the impedance of the signal path uniform throughout.

[0052] Slots <b>410</b> are molded to expose slots <b>332</b> and shield beam contacts <b>126</b>. Slots <b>410</b> receive shield plates <b>116</b> from the backplane connector, which make electrical connection to shield beam contacts <b>126</b>. Slots <b>410</b> each have a tapered surface <b>412</b> opposing the shield beam contact <b>126</b>. As the backplane and daughter card connectors mate, a shield plate <b>116</b> will enter a slot <b>410</b>. The shield plate <b>116</b> could be pressed towards tapered surface <b>412</b> by the spring action of shield beam contacts <b>126</b>. The taper of tapered surface <b>412</b> guides the leading edge of the backplane shield plate <b>116</b> into position at the far end of slot <b>410</b>, thereby preventing stubbing of the shield plate during mating of the connectors.

[0053] Hole <b>430</b> is left in dielectric housing <b>132</b> to allow access to ring <b>16</b> for the purpose of severing tie bar <b>14</b>a from shield plate <b>10</b>. Severing the tie bars close to the signal and ground contacts reduces the stubs attached to the signal and ground members. Stubs are sometimes undesirable at high frequencies because they change the electrical properties of the device.

[0054] Turning now to FIG. 5, signal contact blank <b>510</b> is shown. Signal contact blank <b>510</b> is stamped and formed from a long sheet of metal. Numerous signal contact blanks are formed from a sheet of metal, with the signal contact blanks being held together on carrier strips <b>512</b>. The carrier strips <b>512</b> can include holes for indexing or to otherwise facilitate handling on the carrier strips.

[0055] As can be seen in FIG. 5, each of the signal contacts is stamped and formed to have the required mating contact region <b>124</b> and contact tail <b>128</b>. Additionally, each signal contact has an intermediate portion <b>518</b> joining the contact region and the contact tail.

[0056] As initially formed, the signal contacts are held together with tie bars <b>516</b> and held to the carrier strips with tie bars <b>514</b>. These tie bars provide mechanical stability to signal contact blank while the connector is being assembled. However, they must be severed before the connector is used. Otherwise, they would short out the signal contacts. A method of severing the tie bars is shown in connection with FIG. 7.

[0057] Signal contact blank <b>510</b> is preferably stamped from metal. A metal traditionally used in the connector is preferred, with a copper based beryllium alloys and phosphor-bronze being suitable metals. Portions of the signal contacts, particularly the contact region can be coated with gold if desired to reduce oxidation and improve the reliability of the electrical connections.

[0058] The signal contacts also include projections <b>520</b>. As described above, the signal contacts are placed into channels <b>422</b> in dielectric housing <b>132</b>. Projections <b>520</b> grip the walls of the channels <b>422</b> to hold the signal contacts in place.

[0059] In the next step of the manufacturing operation, the signal contact blank <b>510</b> is overlaid on the dielectric housing <b>132</b> as shown in FIG. 4. Wafer <b>120</b> in this state of manufacture is shown in FIG. 6. Note that the holes in the carrier strips <b>12</b> and <b>512</b> are used to line up the signal contacts with the carrier strips for shield <b>10</b>. Because the molding operation that molded dielectric housing <b>132</b> over shield <b>10</b> was also based on the holes in carrier strip <b>12</b>, precise alignment of all parts of the connector is achieved. Tooling to press the signal contacts into the channels <b>422</b> can also use those holes for positioning.

[0060] Turning to FIG. 7, the severing of the tie bars is illustrated. Those tie bars <b>514</b> that extend beyond the dielectric housing <b>132</b> can be easily sheared at a point outside the housing <b>132</b>. Preferably, they are sheared as close to the housing as possible.

[0061] Each of the tie bars <b>516</b> that is internal to the dielectric housing <b>132</b> passes over a hole <b>22</b>. A tool can be inserted through the hole, thereby severing the tie bars <b>516</b>.

[0062] Then, the wafer is subjected to a second molding operation. In this operation, cavity <b>450</b> is filled to create dielectric housing <b>134</b> (FIG. 2). Openings <b>426</b> are not filled, however, to allow mating contact regions <b>124</b> to move freely and provide the required mating force.

[0063]FIG. 8 shows the wafers <b>120</b> assembled into a connector mated to a backplane connector. Blades <b>106</b> engage with the signal contacts <b>124</b>. The backplane shield plates <b>116</b> are inside slots <b>410</b> and engage with shield beam contacts <b>126</b>.

[0064] In the illustrated embodiment, the shield plates <b>116</b> have a plurality of slots <b>812</b>, to form castellations along the upper edges of shield plates <b>116</b>. Each of the slots <b>812</b> engages a flat region <b>331</b> (FIG. 3), which is left exposed in slot <b>410</b> (FIG. 4) when housing <b>132</b> is molded. Slots <b>812</b> reduces the required depth of slots <b>332</b> formed in shield plate <b>10</b> (FIG. 3), but allows the shield plates <b>116</b> to be longer in the regions where they mate with shield beam contacts <b>126</b>. Reducing the required depth of slots <b>332</b> improves the mechanical integrity of the wafer. Allowing longer shield plates increases the amount of “advance mating,” which can be desirable. Advance mating refers to the distance between the point where the ground contacts mate and the signal contacts mate as the daughter card and the backplane connectors are being pushed together during connector mating.

[0065] Turning now to FIG. 9, a mated wafer <b>120</b> is shown from the shield side. As described above, dielectric housing <b>132</b> is molded on the upper surface of shield <b>10</b>. Thus, on the side of wafer <b>120</b> visible in FIG. 9, the lower surface <b>910</b> of shield <b>10</b> is visible. Raised portions <b>330</b> (FIG. 3) and raised ribs <b>333</b> (FIG. 3) on the upper surface of shield <b>10</b> create recesses on the lower surface <b>910</b>. These recesses are filled with dielectric during the molding of dielectric housing <b>132</b>, leaving dielectric regions <b>912</b>. Dielectric regions <b>912</b> serve multiple purposes. They interact with the plastic that has filled holes <b>26</b> (FIG. 3) to lock the dielectric housing <b>132</b> to shield plate <b>10</b> along the upper edge of wafer <b>120</b>. They also insulate shield plate <b>10</b> from signal contacts <b>124</b> in an adjacent wafer. Thus, they reduce the chance that signal contacts will be shorted to ground.

[0066] Turning now to FIG. 10, an alternative embodiment of the backplane connector is shown. In this embodiment, the shroud <b>1002</b> is formed from a conductive material. In the preferred embodiment, the conductive material is a metal, such as die cast zinc. Possibly, the metal is coated with chromate or nickel to prevent anodization.

[0067] To prevent the blades from shorting to the conductive shroud, dielectric spacers can be inserted into the shroud <b>1002</b> and then the blades <b>106</b> can be inserted into the spacers. In the preferred embodiment, the dielectric strips are pushed into holes <b>1012</b> in the floor of shroud <b>1002</b>. Each dielectric strip is molded from plastic and includes plugs <b>1014</b> on the lower surface to make an interference fit with the holes <b>1012</b>. Holes <b>1016</b> in dielectric strips <b>1010</b> receive blades <b>106</b>. Dielectric strips <b>1010</b> simplify manufacture in comparison to traditional dielectric spacers.

[0068] There are several advantages of a connector made as described above. One advantage results from the multi-step molding process. The spacing between the signal contacts and the ground plane formed by shield <b>10</b> is very tightly controlled. Controlled spacing results in better impedance control, which is desirable.

[0069] As another advantage, molding the dielectric housing onto the shield plate <b>10</b> reduces the overall thickness of the wafers, allowing a connector with higher density to be formed.

[0070] Also, molding dielectric material over dielectric material allows for advantages during the manufacture of the connector. The perimeter of the second dielectric housing <b>134</b> overlaps places where the first dielectric housing <b>132</b> is already molded. The perimeter of dielectric housing <b>134</b> is formed where a wall of a mold shuts off the flow of plastic material during the molding operation. Thus, when second dielectric housing <b>124</b> is molded, the mold is clamping down on the dielectric housing <b>134</b>. Less precision is needed in the molding operation and also greater mold life can be expected when the mold clamps down on plastic, as is the case when second dielectric housing <b>134</b> is molded.

[0071] Another advantage is that making wafers through an overmolding operation allows a family of connectors to be inexpensively made on different pitches between columns of contacts. The inter-column pitch can be changed by changing the thickness of the overmolding <b>134</b>. Increasing the pitch might, for example, be done to reduce cross-talk and thereby increase the speed of the connector. It might also be desirable to increase the pitch to allow <b>10</b> mil traces to be routed to the connector rather than more stand <b>8</b> mil traces. As operating speeds increase, thicker traces are sometimes needed. Using the disclosed design, the same tooling can be used to form housing <b>132</b>, shields <b>10</b> and signal contact blank <b>510</b> regardless of the thickness of the wafer. Also, the same assembly tooling might be used. Having so much of the manufacturing process and tooling in common for connectors on different pitches is an important advantage.

[0072] further, the two step molding operation securely locks the contacts tails into the insulative housing for both the shield and signal contacts. Securely locking the contact tails into the housing is particularly important for connectors made with press fit contacts. The contacts receive very high force when the connector is mounted onto a printed circuit board. If the tails are not securely locked into the insulative housing, there is an increased risk that the contacts will bend or crumble, preventing adequate interconnection of the connector to the board.

[0073] While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.

[0074] For example, the invention is described as applied to a right angle backplane connector. The invention might be employed with connectors in other configurations, such as mezzanine or stacking connectors, which join printed circuit boards that are parallel to each other. The invention might also be used to manufacture cable connectors. To make a cable connector, the contact tails use to attach the connector would be replaced by cables. Often, cables are shielded and the shields of the cable attach to the shields of the connectors. Often the signal contacts of the power connectors do not bend at right angles. The mating interface of a power connector, is however, usually the same as the mating interface of the right angle daughter card connector. Having the same interface allows the power connector to plug into the same backplane connector as the daughter card connector.

[0075] As another example, the order of various manufacturing steps might be interchanged. The order in which the tie bars <b>514</b> and <b>516</b> are severed is not critical to the manufacture of the connector. Tie bars <b>514</b> could be severed first and then carrier strips <b>512</b> might be removed before dielectric housing <b>134</b> is molded. In this way, tie bars can be removed when carrier strips <b>512</b> are removed.

[0076] Likewise, carrier strips <b>516</b> might be severed to separate the signal contacts in a signal contact blank before dielectric housing <b>134</b> is molded. If carrier strips <b>516</b> are severed after the molding operation, holes <b>22</b> are left exposed.

[0077] Further, it should be appreciated that the specific shapes of the contact elements are illustrative. Various shapes, sizes and locations for contact elements would be suitable in a connector according to the invention. For example, the shield member does not have to be a single plate, but could instead be formed from a plurality of shield segments. Further, slots could be formed in the shield plate to reduce resonance in the plate.

[0078] As another example, it should be appreciated that tabs, such as <b>18</b> and <b>322</b> are shown as attachment features that serve to attach the dielectric housings to the shield plate <b>10</b>. Holes <b>26</b> are also illustrations of attachment features. Tabs right be interchanged for holes. Alternatively, attachment features with other shapes might be used.

[0079] Also, thermoplastic material is generally used for injection molding, which can be used for the molding steps. Other types of molding could be used. In addition, dielectric housing <b>134</b> might not be formed by molding. Rather, it could be formed by filling cavity <b>450</b> with an epoxy or other settable material.

[0080] Yet further modifications are possible. In the above-described embodiment, a metal stiffener is shown. Other methods of attaching the wafers are possible, including attaching them to plastic support structures or otherwise securing the wafers together.

[0081] It should also be appreciated that all of the listed features and advantages described need to be present simultaneously to get benefit of the invention.