Filtering insert for electrical connectors

An electrical connector assembly includes two mating multiposition electrical connector halves 2, 4 and an insert 10 which is positioned in engagement with the terminals 8 in one of the connector halves. The insert is fabricated from a lead frame 16 which is secured between an insulative substrate 40 and a cover 48. Portions of the lead frame 16 extending into slots 44 and channels 52 on the substrate and cover are punched out to separate connecting tabs 26 from ground buses 18, 20, 22. Surface mount capacitors 38 are soldered to both the solder tab sections 30 on the connecting tabs and to solder contact sections 34 on the ground buses. The insert 10 is then positioned on the terminals 8 on one connector half with the tines 32 in a terminal socket 28 on each connecting tab 26 engaging the terminals 8.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to the addition of an insert to an electrical 
connector to alter the characteristics of the circuits to which that 
connector is attached. More specifically, this invention relates to 
filtering inserts which can be used with electrical connectors to filter 
noise on the circuit. Even more specifically, this invention relates to 
the use of stamped and formed and molded components to fabricate the 
filtering inserts. 
2. Description of the Prior Art 
One technique for filtering undesirable noise on a circuit or one or more 
individual lines is to install a capacitive element between that line or 
circuit and ground. One prior art approach to adding a filtering component 
is to incorporate that component into an electrical connector in the 
circuit. One approach to adding the filtering component to an electrical 
connector is to mount surface mount capacitors on printed circuit boards 
which are shaped to mount either between mating electrical connectors or 
to be mounted at the rear of one of the connector halves, often on a 
printed circuit board header connector. Examples of this approach are 
shown in U.S. Pat. No. 5,181,859 and in U.S. Pat. No. 5,290,191. These 
prior art devices use standard surface mount capacitors soldered to traces 
on small printed circuit boards and add pin contact terminals to the 
printed circuit board to establish electric contact with the terminals of 
the connector to which filtering is to be added. These terminal contacts 
must however be added to the printed circuit board and care must be taken 
that there is not only a reliable contact to board interface, but also 
that this interface is not damaged during other processing steps or when 
the surface mount components are added. 
SUMMARY OF THE INVENTION 
A filtering insert which can be attached to an electrical connector 
includes stamped and formed connecting tabs and ground buses which are 
secured to a substrate. Filter components are soldered between the 
connecting tabs and a corresponding ground bus. The connecting tabs 
include a socket and a solder tab section. Each ground bus includes a 
solder contact section which is aligned with a corresponding solder tab 
section on the connecting tabs. Each filter component, preferably in the 
form of a standard surface mount component such as a surface mount 
capacitor, is soldered using conventional surface mount soldering 
techniques. The socket on each connecting tab is resilient and establishes 
a resilient electrical connection with a corresponding terminal when the 
filtering insert is attached a connector. 
The connecting tabs and ground buses are initially parts of a lead frame 
which is preferably secured by a cover to an insulative substrate, which 
in the preferred embodiments is a molded member. Portions of the lead 
frame initially connecting the connecting tabs to the ground buses are 
punched out after the lead frame is secured to the substrate. Aligned 
slots and channels in the substrate and cover provide clearance for the 
punching tool. The disconnected connecting tabs are thus held in place by 
the substrate or the substrate and the cover. Sections on the opposite 
sides of the punched out portions have solder deposits and the surface 
mount components are soldered to these solder deposits. 
By fabricating the filtering insert in this manner it is possible to use 
conventional stamping and forming techniques to fabricate the filter 
insert assembly. No special manufacturing operations of any kind are 
required. Only one soldering operations is necessary and no special 
terminals must be added. A resilient contact can be established with the 
terminals in a conventional connector without the need of any hybrid 
soldering operations. A standard filter insert connector can be fabricated 
which can be subsequently loaded with individual surface mount filter 
components. Alternatively other components, besides filtering components 
can be added. 
Many different configurations can be fabricated using this approach. It is 
applicable both to filtered and unfiltered configurations. Although 
especially useful when used in conjunction with printed circuit board 
connectors, this type of connector and its assembly method are not so 
limited. This invention is suitable for retrofitting standard connectors 
where is becomes necessary, after the fact, to add filtering, and it is 
also suitable to use in entirely new connector designs. 
These and other objects of this invention are achieved in the manner 
depicted by the representative embodiments disclosed herein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The filtering insert approach disclosed herein in the form of two 
representative embodiments can be used with numerous electrical connector 
configurations to add filtering to circuits in which these otherwise 
substantially conventional electrical connectors would be used. Each of 
the two embodiments depicted herein is used with a conventional electrical 
connector configuration consisting of a multiposition electrical connector 
receptacle in which electrical terminals attached to individual wires are 
positioned in the connector in multiple rows of staggered terminals. The 
connector receptacles mate with electrical connector printed circuit board 
headers containing multiple printed circuit board pins. Although right 
angle mount headers are shown, this invention can be employed with 
straight pins in vertical mount headers. The term pin as used herein is 
intended to refer to male terminals in general and is not limited to 
specific configurations. For example, pins can have different cross 
sections including square or circular cross sections, and pins can be 
solid or formed pins, open in the center. This invention can also be used 
with other electrical connector configurations and is not limited to use 
with printed circuit board connectors. For instance this invention can be 
used with wire to wire pin and socket type electrical connectors. The 
modifications to the embodiments depicted herein would consist basically 
in redimensioning the connection to be made with the specific alternative 
electrical terminal used in other embodiments. This redesign could be 
performed without undue experimentation by one of ordinary skill in the 
art. This invention is also not limited to use with the rectangular 
configurations depicted in the two representative embodiments. For example 
a circular filtering insert could be used with circular connectors. The 
terminals also need not be configured in the staggered configurations 
shown in the representative embodiments. This invention can also be 
employed with either noble metal plated electrical terminals or with tin 
plated electrical terminals. 
The first representative embodiment of this invention shown in FIGS. 1-12 
is a filtering insert 10 which can be mounted at the mating interface 
between an electrical connector receptacle 2 and a printed circuit board 
header 4. This connector assembly in intended to connect a plurality of 
individual wires terminated to female electrical contact terminals 6 to 
circuits on a printed circuit board through individual male terminal pins 
8, each arranged here in four staggered rows. In this embodiment, adjacent 
terminals are spaced apart on centerlines of 3.00 mm. The pins 8 extend 
through the housing of the header 4 from a rear surface 12 to a mating 
surface 14, here in the form of a shrouded configuration in which the 
mating end of the connector receptacle 2 is received within the shroud at 
the mating face. The filtering insert is positioned on the pins 8 at the 
mating face 14 prior to mating the two connectors halves. 
In the embodiment of FIG. 1, discrete filtering components are positioned 
on filtering insert 10 between signal lines to be filtered and ground. 
This configuration with the filtering components 38 on the filtering 
insert 10 is shown in FIG. 2. In this embodiment, the filtering inserts 
are discrete surface mount capacitors of conventional construction. For 
example, EIA standard ceramic capacitors in an 0805 package having a 
length of 2.0 mm (0.080 in.), a width of 1.2 mm (0.050 in.), and a height 
of 1.2 mm (0.050 in.) could be used. 
These filter components are mounted on a filtering insert subassembly which 
is fabricated from a lead frame 16 which is mounted between an insulative 
substrate 40 and a cover 48. These components are shown in FIGS. 4-6. 
FIGS. 4 and 5 are front and rear views respectively of the lead frame 16, 
the insulative substrate 40 and the cover 48. The lead frame 16 is stamped 
and formed from a flat metal blank in a conventional manner from a metal 
having spring properties. Any number of standard engineering metals, for 
brass or various copper alloys, could be employed. The insulative 
substrate 40 and the cover 48 are each molded using any number of standard 
engineering plastics including thermoplastics and thermosets. These 
plastics should be compatible with the temperatures encountered during 
surface mount soldering operations. 
The lead frame 10 is stamped in a configuration to match the terminal 
arrangement in the connector with which the filter insert 10 is to be 
used. In this embodiment, the connector is a four row connector with 
staggered pins, so the lead frame is stamped in a four row configuration. 
This embodiment of the lead frame has three horizontal carrier strips 18, 
20, 22. A plurality of carrier strip extensions 24 extend from each 
carrier strip, and connecting tabs 26 will be subsequently formed from 
these extensions 24. Each of the extensions 24 has a generally circular or 
ring section located at the end of the extension. A terminal socket 28 is 
formed at the ends of the extensions 24. The preferred embodiment of this 
terminal socket 28 is formed by stamping each extension to form a central 
opening surrounded by a plurality in inwardly extending tines 32. These 
tines 32 are formed transverse to the plane of the lead frame, and each 
tine 32 comprises a resilient spring which will establish electrical 
contact with a terminal, such a printed circuit board pin 8, inserted 
through the socket 28. Openings 50 in the cover 48 provide sufficient 
clearance for the portions for the tines 32 formed out of the plane of the 
lead frame 10. These tines are preferably formed in a progressive die in 
which a continuous strip of lead frames are fabricated. 
The molded insulative substrate 40 has an inner face in which the lead 
frame 16 can be mounted in its integral configuration shown in FIGS. 4 and 
5. The substrate 40 has a plurality of substrate terminal openings 42 
which extend from the front to the rear faces of the substrate 40. Four 
slots 44 extend parallel to the rows of substrate terminal openings 42 and 
are mutually parallel. These four slots 44 are best seen in FIG. 5. The 
slots 44 are visible in FIG. 4, but the rear edge on these slots 44 on the 
rear face is not visible in FIG. 4 or in the enlarged view of FIG. 6. The 
inner face is recessed at indentations 45 which are shaped to receive the 
rounded ends of extensions 24 on the lead frame 10. The substrate terminal 
openings 42 extend through these indentations and separation or alignment 
posts 46 are located along the edge of the slots 44 between adjacent 
indentations 45. 
The lead frame 10 is positioned between substrate 40 and an insulative 
cover 48 which is preferably molded from the same material as the 
substrate 40. Cover terminal openings 50 extend through the cover from the 
front to the rear cover faces. These cover openings 50 are aligned with 
the substrate terminal openings 42. When the lead frame 10 is positioned 
between the substrate 40 and the cover 48, the terminal sockets 28 on the 
lead frame 10 are aligned with the openings 42, 50. Cover 48 also has 
three channels 52 parallel to the rows of cover terminal openings 50 and 
mutually parallel. The width of these cover channels 52 is greater than 
the width of the slots 44. The cover channels are positioned so that the 
periphery of the cover channels 52 envelope the periphery of the slots 44 
on the substrate. The two center slots 44 are enveloped by the one center 
channel 52 on the cover 48. As shown in FIG. 8, at least portions of the 
lead frame carrier strips 18, 20, 22 are enveloped by the channels 52 so 
that portions of these carrier strips are exposed on the cover side of 
this assembly. Portions of the extensions 24 are also exposed in the 
channels 52 and the separation or alignment posts 46 fit into the cover 
channel 52. FIG. 9 shows that substantially the same portions of the 
extensions 24 which are exposed in the channels 52 are also exposed in the 
slots 44, because the channels 52 overlap the slots 44 in this area. The 
cover 48 is attached to the substrate 40 to secure the lead frame 16 
between the two exterior members and the cover secures the lead frame 16 
to the substrate 40. Conversely the substrate 40 secures the lead frame 16 
to the cover 48. The cover can be attached to the substrate by any number 
of conventional techniques. For example, an adhesive can be used to secure 
the two molded members together. The cover 48 can also be ultrasonically 
bonded to the substrate 40 or they could be heat staked together. An 
interference fit would also be suitable to secure the cover to the 
substrate and conventional snap latches could also be added at the 
periphery or elsewhere. Snap latches could also be added to the separation 
posts 46. The lead frame 16 could also be attached directly to either the 
substrate 40 or the cover 48 and the other molded member could be attached 
to the lead frame 16 or to its companion molded member. Indeed the cover, 
though desirable, is not absolutely necessary and the lead frame 16 could 
be secured directly to the substrate only. Any number of other equivalent 
securing means could also be employed. 
Once the lead frame 16 has been secured to the substrate 40, portions of 
the extensions 24 are removed to separate connecting tabs 26 from ground 
buses 18, 20, 22, initially carrier strips. FIGS. 10 and 11 show the 
manner in which the connecting tabs 26 are separated from the carrier 
strips 18, 20, 22. Slots 44 serve as guides for a punch (not shown) which 
is used to punch or stamp out portions of extensions 24 adjacent the 
carrier strips 18, 20, 22. Since the channels 52 overlap slots 44 there is 
clearance for this punch. After portions of extensions 24 have been 
removed, the connecting tabs 26 are formed. These connecting tabs, one of 
which is shown in FIG. 7, include a terminal socket 28 and a solder tab 
section 30. The terminal socket 28 contains the socket tines 32 and is 
positioned in alignment with openings 42, 50 to engage a terminal, such as 
pins 8. The solder tab portion is that exposed portion of extension 24 
which remains after material is punched out of extension 24. The solder 
tab section 30 is exposed in cover channel 52 and is accessible for 
subsequent use. Solder tab section 30 is connected to the terminal socket 
28 and is opposed to a corresponding ground bus 18, 20, 22 formed when 
material is removed from the extensions 24. At least a portion of the 
ground bus is exposed or accessible in channel 52. That portion of the 
respective ground bus aligned with a solder tab section 30 is referred to 
as the solder contact section 34 and solder deposits 36 are placed on 
solder tab sections 30 or on the ground bus solder contact sections 34. 
Solder can be deposited in any of a number of conventional ways. Solder 
cream or solder paste can be screened onto the solder tab sections 30 and 
solder contact sections 34, or it can be applied by pneumatically operated 
dispensers. Solder paste can be dispensed using stencils, or solder paste 
can be dispensed using a syringe. Solder can also be plated in these areas 
to form the solder deposits 34, 36. Solder flux would be used as needed. 
FIG. 12 shows areas in which solder would be deposited. It should be noted 
that solder can be dispensed all along the exposed portions of ground 
buses 18, 20, 22 since all components are to be soldered to ground in this 
embodiment. Solder contact sections 34 would of course still be those 
portions of the ground buses to which components are to be soldered. FIG. 
12 also shows the positions occupied by selected surface mount components 
38, such as surface mount capacitors. 
FIG. 7 shows a single connecting tab 26 and the corresponding solder 
contact section 34 of the opposed ground bus. The solder deposited on 
solder tab section 30 and on aligned and opposed solder contact section 34 
will be reflowed after a surface mount component 38 is positioned. A 
conventional reflow process is used to solder the surface mount component 
between the connecting tab 26 and the ground bus 18, 20 or 22. A wave 
soldering operation would require special precautions so that solder would 
not be deposited on the terminal sockets 28, and therefore wave soldering 
would not normally be used. 
There are a number of ways in which the ground buses 18, 20, 22 can be 
connected to ground. Although not shown in this embodiment, one or more of 
the extensions 24 between a terminal socket 28 and the ground buses can be 
left intact. Since all of the ground buses are interconnecting, this one 
ground pin can effectively ground the buses. Alternatively a zero value 
surface mount resistor could be used to connect a ground pin to one of the 
interconnected ground buses 18, 20, 22. 
An alternative representative embodiment is shown in FIG. 13 and 14. In 
this second embodiment, the filter insert 110 is positioned on the rear 
face 112 of the electrical connector header 104 instead of at the mating 
face 114 between the header 104 and the receptacle. 102. This embodiment 
shows a shielded embodiment in which two shields 156 and 158 are 
positioned on the exterior of the header 104. The rear could be shielded 
by plating the exterior of the substrate (not shown). This filter insert 
110 also includes a grounding tab 154 extending from one side of the 
insert. This grounding tab is part of the lead frame used to fabricate the 
filter insert 110 and is in a position to mate with one of the two shields 
156 and 158. In this embodiment upper shield 156 and lower shield 158 fit 
around the exterior of the pin header 104. Lower shield 158 includes a 
strap 160 formed on side in position to receive grounding tab 154 and make 
resilient electrical contact to ground the ground buses (not shown, but 
otherwise the same as ground buses 18, 20, 22 for the first embodiment) to 
a ground shield which is in turn attached to a ground trace on the printed 
circuit board. In the embodiment shown herein the strap 160 forms a 
resilient contact with the grounding tab 154. Of course, solder could also 
be used to form this interconnection. This embodiment also shows the use 
of a ferrite plate 162 to add inductive filtering. Of course, both 
embodiments are compatible with the use of ferrite plates or ferrite beads 
to add filtering in this manner. 
Although the representative embodiments of this invention are intended 
primarily for use in filtering circuits using conventional electrical 
connectors, this invention provides a simple way to add filtering to 
electrical connectors to be used for new and specific applications. The 
use of an insert of this type could also be used for applications other 
than filtering, since other components could be added between lines in the 
connector. For example a diode could be mounted on the insert instead of a 
capacitor. Other slight modifications could also be made to the 
construction of these inserts. For example, a flexible film substrate with 
the lead frame bonded to one surface could be substituted for the 
thermoplastic substrate used in the representative embodiment depicted 
herein. In some cases, this approach can be used in applications where 
special terminals must be included in the connectors. For example a 
terminal having an enlarged mating section to be engaged by the socket 
tines and a smaller noble metal plated mating section can be used in those 
applications where damage to the noble metal contact plating is of 
concern. These and similar alternative embodiments within the scope of the 
following claims would be apparent to one of ordinary skill in the art.