Filter insert for an electrical connector assembly

Details Filter insert for an electrical connector assembly Filter insert for an electrical connector assembly

2003-03-19

2004-10-26

Paumen, Gary (Department: 2833)

Electrical connectors

With circuit component or comprising connector which fully...

Termination circuit

C439S067000, C439S077000

Reexamination Certificate

active

06808422

ABSTRACT:

TECHNICAL FIELD
The present invention relates to an electrical connector assembly, and more particularly to a filter insert that is electrically coupled to the connector terminals for filtering electrical signals carried by the terminals.
BACKGROUND OF THE INVENTION
Most electronic modules include a connector assembly for coupling the module to power supplies and external components such as sensors and actuators. Referring to
FIG. 1A
, a typical connector assembly
10
includes a matrix of terminals
12
supported in an insulator block
14
that passes through a wall of the module housing
16
. The inboard ends of the terminals
12
are electrically coupled to a circuit board
18
enclosed by the module housing
16
, while the outboard ends of the terminals
12
are accessible for electrical interconnection with a complementary connector and electrical cable (not shown). A filter insert
20
disposed between the insulator block
14
and the circuit board
18
is electrically coupled to the terminals
12
, and includes filter elements such as capacitors for filtering electrical signals carried by the terminals
12
. In many applications, such filtering is necessary in order to attenuate unwanted electrical noise as well as to reduce radiated electromagnetic emissions due to operation of the module. The insert
20
is provided with a matrix of openings
22
as seen in
FIG. 1B
, and is installed by aligning the openings
22
with the terminals
12
, and pushing the insert
20
onto the terminal matrix. An encapsulating material
24
is injected into the region between the circuit board
18
and the insulator block
14
as shown in
FIG. 1A
for improved environmental sealing.
The filter insert
20
can be formed on a circuit board, on a rigid plastic substrate or on a flexible substrate. In cases where the insert is formed on a circuit board or a rigid plastic substrate, the terminals
12
can be soldered to metallic pads adjacent to the openings
22
, or the openings
22
can be through-plated with metal so that a reliable electrical connection is established by virtue of an interference fit between the terminals
12
and the through-plated metal. An interference fit between the terminals
12
and the filter insert circuitry can also be achieved in cases where the insert
20
is formed on a flexible substrate by extending the circuit traces across the openings
22
, leaving an opening that is smaller than the outline of a terminal
12
. An example of a filter insert formed on a plastic substrate with through-plated openings is shown in the U.S. Pat. No. 6,413,119 to Gabrisko et al., while an example of a filter insert formed on a flexible substrate is disclosed in the U.S. Pat. No. 5,415,569 to Colleran et al.
Of the various filter insert designs discussed above, the flexible circuit approach is particularly attractive from a cost stand point, primarily because the interference fit electrical connections between the connector terminals
12
and the filter insert
20
permits low insertion force (compared to the through-plated approach) and eliminates the expense of soldering and/or through-plating. However, reliability testing has shown that when the module is subjected to extended thermal cycling, the thermal expansion and contraction of the encapsulating material
24
is transmitted to the flexible circuit, which in turn, leads to fatigue-related failures of the solder joints and traces formed on the circuit. Accordingly, what is needed is an improved filter insert having the low insertion force and low cost advantages of a flexible circuit, but with improved thermal cycle reliability.
SUMMARY OF THE INVENTION
The present invention is directed to an improved filter insert for a terminal connector, where the filter insert comprises a rigid substrate for good thermal cycle reliability and low-cost interference fit electrical connections between the filter insert and the connector terminals. In a first embodiment, the filter insert comprises a flexible circuit bonded to the rigid substrate, and the substrate is provided with over-sized openings that the terminals pass through without interference. A second embodiment is like the first, except that the filter circuit traces are formed directly on the rigid substrate, and the substrate material backing the terminal connection sites is removed to form the over-sized openings. The thermal bending stress applied to the traces and solder joints of the filter insert of this invention is considerably reduced compared to the flexible circuit approach, and the insertion force of the filter insert is essentially the same as with a flexible circuit due to the over-sized substrate openings.


REFERENCES:
patent: 4121044 (1978-10-01), Hadersbeck et al.
patent: 4950173 (1990-08-01), Minemura et al.
patent: 4970624 (1990-11-01), Arneson et al.
patent: 5384435 (1995-01-01), Fuerst et al.
patent: 5415569 (1995-05-01), Colleran et al.
patent: 6086384 (2000-07-01), Fuerst et al.
patent: 6413119 (2002-07-01), Gabrisko, Jr. et al.

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