JPH0695464B2 - Electric filter connector - Google Patents

Abstract

A filter connector (8) for attentuating electromagnetic interference up to 1000 MHz having a housing (10), a filter element (16) enclosed within the housing (10) and electrically conductive pins (18) mounted within the filter element (16). The filter element (16) contains an alumina substrate (42) with thick film layers (44, 50) of a metallization forming pin and ground electrodes, and a dielectric layer (46, 48) separating the electrodes screen printed over the substrate and a glass encapsulant (52, 54). The ground electrode (44) substantially covers a horizontal surface of the substrate (42).

Description

The present invention relates to a filter connector for reducing electromagnetic interference of an electrical device, and in particular each housings a conductive pin and controls the different frequencies applied to the conductive pin. It relates to a filter connector having a series of thick film capacitors with holes inside the various elements for damping.

Filter connectors for attenuating high frequency interference from electrical equipment have been described in several patents, such as US Pat. No. 3,538,464.
No. 4,126,840, No. 4,144,509 and No. 4,18
It is well known from the specifications of 7,481. In each of these U.S. patents, the capacitor used with the filter is a series of ceramic layers forming a monolithic structure. Thick film capacitors are also US Pat. No. 4,27.
It is well known from 4,124. Although monolithic capacitors are currently used in filter connectors, U.S. Pat.
Substitution of the thick film capacitors shown in 4,274,124 has not been previously practiced. Problems have arisen when designing thick film capacitors for filter connectors that have sufficiently low inductance to attenuate high frequencies.

In recent years, with the widespread use of computers, especially household computers, a significant additional amount of high frequency electromagnetic signals has been generated that can interfere with other electrical devices. For the purpose of reducing the output of such signals, the United States Federal Communications Commission (FCC) has a rule (47CFR15, Subpart) that requires attenuation at the source.
J) was distributed.

Commercially available monolithic capacitor structures used in filters are not cost effective for use in low cost electronic devices such as personal computers.

Since the cost of manufacturing a filter connector can be significantly reduced by using a thick film capacitor, a filter connector such as a thick film capacitor having such a low inductance is needed. Useful commercial filters attenuate electromagnetic signals to at least 30 decibels (dB) at a frequency of 1000 megahertz (MHZ).

The present invention is a cost effective electrical filter connector for waving broadband frequencies up to 1000 MHz using a particular design of thick film capacitors in an iterative sequence to form a filter element. The filter element comprises a number of closely spaced thick film capacitors with conductive pins mounted in the holes of each of these capacitors.
This capacitor has multiple layers of screen printed material across an alumina substrate that has two horizontal surfaces and is generally rectangular in shape. One layer is a metallization that forms the ground electrode.
ion). This electrode is grounded to the connector housing. The electrode has holes sufficiently large to substantially cover the entire horizontal surface of the alumina substrate and accommodate the conductive pins in contact with none of these pins.

Another layer is the metallization forming the pin electrode, but its area is limited to a portion of the substrate around a given hole. This layer is in electrical contact with the pin via the solder joint. Between these two electrodes,
There is a dielectric layer applied directly to one of the electrodes. This layer substantially overlaps the horizontal plane of the ground electrode when it is the first layer and exposes the two longest edges on each side of the ground electrode. This layer also has holes that are barely large enough to allow the conductive pins to pass through without contacting the dielectric material. This dielectric material also covers the vertical plane of the ground electrode closest to each hole.

The fourth and final layer is an electrically non-conductive encapsulant to exclude moisture covering all layers except electrical contact or solder areas. This filter connector can maintain substantial attenuation in the ultra high frequency range up to at least 1000 MHZ.

The invention will be best understood by those of ordinary skill in the art by reference to the following detailed description in connection with the accompanying drawings.

First, referring to FIG. 1, a filter connector 8 includes a housing 10 having a top shell 12 and a bottom shell 14.
Is equipped with. The housing 10 surrounds two rows of pins 18 mounted on the filter member 16. The inside of the connector 8 is protected by a top insulator 20 and a bottom insulator 38. The pins 18 are individually attached to the filter element 16 by solder joints 22.

A threaded insert 28 can be optionally attached to the connector as a fixture for the cabinet. The ground contact 32 can be used on the top shell 12 to form a ground contact for a female plug (not shown) inserted into the pin 18. The two shells 12 and 14 are pleated together by a tab 40. The pin 18 may be straight, as shown in FIGS. 1-3, or may be square, as shown at 34. 2-4 show the solder joint 22 when the pin 18 is attached to the filter element 16. Hole 31 in bottom insulator 38 provides a bottom outlet for pin 18. The hole 30 in the filter element 16 provides a means for threading the pin 18 through the filter member and positions the solder joint 22.

The structure of the filter element 16 will be understood with reference to FIGS. 4 and 5. FIG. 4 shows for illustration purposes only one of the capacitor units inside the filter element 16. The filter element 16 comprises an alumina substrate 42.
A metallization is formed on one horizontal surface of the alumina substrate 42.
44 is screen printed. The metallization 44 forms a grounding electrode which is then welded to the shell 14 with solder 36. The ground electrode 44 is an alumina base 42.
Substantially covers the entire surface of. Ground electrode 44 is the fifth
As can be seen, it has a hole 24 large enough to accommodate the pin 18 without contacting it.

The ground electrode 44 is partially covered by a screen-printed layer of dielectric 46. Although this specification refers to a single layer of dielectric for purposes of illustration, in practice the two layers of dielectric 46 and 48 are grounded to provide more than sufficient protection against short circuits between the electrodes. Screen printed on the electrodes 44. The dielectric layer 46/48 also has holes 26 slightly larger than the diameter of the pin 18, as can be seen in FIG. The dielectric layer 46/48 covers the horizontal plane of the ground electrode 44 except for the edges 43 and 45. The edges 43, 45 are areas used for soldering the ground electrode 44 to the shell 14. Insulator layers 46/48 are also applied to the vertical edge of ground electrode 44 adjacent hole 24, as can be seen in FIG.

A second metallization 50 is intermittently screen-printed on the dielectric layer 48 in a regular arrowhead pattern. This forms a series of pin electrodes 50. Pin electrode
Each of the 50 is in electrical contact with the pin 18 via a solder joint 22. The pin electrode 50 is designed to form a series of individual spaced arrowhead-shaped layers distributed over the surface of the dielectric layer 46/48, as can be seen from FIGS. 5 and 6. Screen printed on. An electrode 50 is adjacent to each hole 26 and annularly surrounds hole 41.
A final layer, encapsulation molded glass 52/54, covers both electrode 50 and dielectric layer 46/48. Although only one layer is shown in FIG. 5, in practice two layers of glass encapsulant are typically screen printed on the electrode 50 for added safety. For the purposes of this specification,
When referring to a layer of encapsulant, we mean one or more layers of encapsulant. The arrowhead design of the electrodes 50 allows for the arrangement of closely spaced capacitors used in filter connectors, thus increasing the area of the capacitors and hence the capacitance value. Of course, other designs could be used that meet the purpose of producing capacitors of the type used in the present invention.

The metallization used for the first and third layers is preferably formed of a noble metal or an alloy of noble metals.
However, copper metallization compositions could also be used. Palladium-silver alloy metallization is particularly preferred. Each layer is applied using conventional screen printing methods. The dielectric used may be of any type commonly used in capacitors. However, barium titanate is preferred.

The glass encapsulant can be any of the types used in capacitors having expansion coefficients compatible with the other components used.

As can be seen from FIG. 8, the ferrite sleeve 19 can be attached to the pin 18. Such sleeves are well known as can be seen from U.S. Pat. No. 4,144,509. By using the particular filter member of the present invention, the filter action of the filter connector using ferrite is increased.

The metallization used in the present invention is composed of a fine metal powder of noble metal or copper, a binder for the metal and a composition containing a vehicle for uniformly dispersing the metal fine particles. The composition is applied by a screen printing method, and the vehicle is removed from the applied composition by baking the screen printed composition onto a layer by conventional techniques.

4 and 5 show the grounding electrode applied as the first metallization layer and the pin electrode 50 applied as the third metallization layer, but in reverse. be able to. Therefore, the pin electrodes 50 can be screen printed directly on the alumina 42 around each hole 41. Dielectric layers 46 and 48 are then applied overlying electrode layer 50 except at solder regions 22. The ground electrode 44 is then screen printed onto the dielectric layers 46 and 48 and all exposed horizontal surfaces of the alumina substrate 42. Encapsulant 52/54 is applied in the same manner as in FIG. The encapsulant 52/54 covers all exposed surfaces except the edges 43 and 45, which are the soldering areas.

The low inductance at high frequencies obtained by the present invention is a direct result of the geometry of the ground electrode associated with the pin electrode. If the grounding electrode and the dielectric were placed on only one side of the pin, the decay curve (a) of FIG. 9 would be obtained. This attenuation curve is especially over 200MHZ,
And more specifically, it exhibits a reduced attenuation curve in the ultrahigh frequency range above 700 MHZ, and thus a reduced filter action. The reason for this reduction in attenuation is that the capacitor produces a series of resonances around 200 MHZ (indicated by the sharp peak in the attenuation curve (a)) caused by the inductance of its electrodes.

If the grounding electrode extends substantially across the entire substrate and the dielectric surrounds the hole, the current from the pin can be split into two components, each component being a ground connection on each side of the filter element 16. It flows to the club once. As a result, the effective inductance of the electrodes is reduced by providing two parallel current paths. As a result of this decrease in inductance, a series of resonance frequencies increase and the curve (b) in FIG.
An increase in damping occurs as indicated by.

[Brief description of drawings]

1 is an isometric view of the filter connector assembly shown in partial cross section, FIG. 2 is a partial elevational view of the filter connector assembly in cross section, and FIG. 3 shows the filter connector assembly of FIG.
-3 is a cross-sectional view cut along line 3, FIG. 4 is a sectional view of a single capacitor unit of the filter element combined with the pin, and FIG. 5 is a filter element accommodating the multiple capacitor unit shown in FIG. 6 is a perspective view of the filter element member shown in FIG. 5, and FIG. 7 is a perspective view of FIG.
7 is an enlarged view of a cross section cut along line 7, FIG. 8 is a partial sectional view of a filter connector having a ferrite sleeve around each pin, and FIG. 9 is a grounding electrode shown in FIGS. 4 is a graph showing the attenuation curve of the filter connector when the substrate is not covered with the substrate shown in FIG. 8 ... Filter connector, 10 ... Housing, 12 ... Top shell, 14 ... Bottom shell, 16 ... Filter element, 18
...... Pin, 20 …… Top insulator, 22 …… Solder joint, 24,2
6 …… hole, 28 …… insert, 30 …… hole, 32 …… ground contact, 38 …… bottom insulator, 41 …… hole, 42 …… alumina substrate, 44 …… metallization, 43, 45 …… Edge, 46,48
…… Dielectric, 50 …… Electrode, 52,54 …… Glass encapsulant.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Arthur Thomas Murphy-Pennsylvania, USA (17033) Hershey Edgehill Road 18 (72) Inventor Frederic Zyon Young United States of America State of Pennsylvania (16801) State Caletage Devonshire Road 762 (56) References: Actually open 54-111741 (JP, U) Actually open 55-142891 (JP, U) Actually open 56-4181 (JP) , U) Actual development Sho 56-37281 (JP, U) Actual development Sho 57-135080 (JP, U)

Claims (13)

[Claims] 1. A conductive housing (10, 12, 14) having a filter element (16) surrounded by the housing and a plurality of conductive pins (18) mounted on the filter element (16), The filter element (16) has a through hole (41) to which a conductive pin (18) is attached, an alumina substrate (42), and an alternating layer of a conductive layer and a dielectric layer formed on the substrate by screen printing. A plurality of thick film capacitors arranged in close proximity to each other, each capacitor being associated with one conductive pin (18), and the first layer (44) of the alternating layers being A thick film metallization that forms a grounding electrode that makes electrical contact with the connector housing (14) along two opposing edges, and the grounding electrode (44) surrounds the alumina substrate (42). Extended and conductive pins (18)
Are continuous except for a hole (24) large enough to pass through the electrodes without contacting the electrodes, the third layer of the alternating layers making electrical contact with each of the conductive pins (18). But a thick film metallization that forms individual pin electrodes (50) that make electrical contact with the housings (10, 12, 14), and the second layer of the alternating layers is those electrodes (44 and 50). A thick film dielectric (46 and / or 48) between which the current from the conductive pin (18) can be split into two components through the ground electrode (44) to the housing (44). 10,1
An electric filter connector, characterized in that it flows to each ground connection on the two sides of (2,14). 2. A grounding electrode layer is a first layer applied to an alumina substrate, and a second layer is applied to the grounding electrode so as to be close to, but spaced from, each hole of the substrate. An insulating dielectric material, and a third layer is a thick film metallization layer forming inwardly around each hole of the substrate a respective pin electrode provided on the second layer, and the pin is The electrical filter connector according to claim 1, wherein the electrical filter connector is attached to the hole by soldering. 3. The electrical filter connector of claim 2 wherein a non-conductive encapsulant having a coefficient of expansion compatible therewith is applied over the third layer. 4. The electrical filter connector of claim 3 wherein the first layer of the planar array of capacitors is a noble metal metallization. 5. The capacitor according to claim 3, wherein the first layer of the planar array of the capacitor is a metallized material of a palladium / silver alloy.
The electric filter connector according to the item. 6. The electrical filter connector of claim 3 wherein the third layer of the planar array of capacitors is a noble metal metallization. 7. The third layer of the planar array of the capacitor is a metallization of palladium / silver alloy.
The electric filter connector according to the item. 8. The electrical filter connector according to claim 3, wherein the first layer of the planar array of capacitors is a metallized material made of copper. 9. The electrical filter connector according to claim 3, wherein the third layer of the planar array of the capacitors is a metallization made of copper. 10. The electrical filter connector according to claim 2, wherein the metallization of the third layer has an arrowhead shape. 11. The electrical filter connector of claim 1 in which a ferrite sleeve surrounds each conductive pin. 12. A conductive housing (10, 12, 14) having a filter element (16) enclosed within the housing and a plurality of conductive pins (18) mounted on the filter element (16), The filter element (16) is composed of a plurality of thick film capacitors arranged in close proximity, and each capacitor houses one pin (18) in each hole (41) penetrating the alumina substrate (42). Each capacitor has an alternating layer (44) of screen-printed conductive and dielectric layers on an alumina substrate (42), the first layer of which is located along two opposing edges of the connector housing. (10,12,14) is a metallization of a noble metal forming an electrode grounded, the grounding electrode (44) extends around the alumina substrate (42) and the conductive pin (18) is connected to the electrode. Continuous except for holes (41) large enough to pass without contact with The second layer is a dielectric insulating material and substantially covers the first layer and overlaps the first layer around each hole (41), and the third layer is each hole in the substrate (42). A metallization forming individual pin electrodes (50) around and inside (41) and overlying the second layer and in electrical contact with the individual pins (18); The layer is a non-conductive encapsulant having a coefficient of expansion compatible with the other layers applied on the third layer, and the first layer is a housing (10,12,1) along two opposite edges.
4) has an exposed end in electrical contact with which allows the current from the conductive pin (18) to split into two components, through the ground electrode (44) of the housing (10, 12, 14) An electrical filter connector, characterized in that it flows to each ground connection on two sides. 13. A conductive housing (10, 12, 14), a filter element (16) enclosed within the housing and a plurality of conductive pins (18) mounted on the filter element (16), The filter element (16) has a plurality of thick film capacitors arranged in close proximity, and each capacitor accommodates one pin (18) in each hole (41) penetrating the alumina substrate (42). Each capacitor then has an alternating layer of conductive and dielectric layers screen-printed on the substrate (42), the first layer of which is applied to the substrate around and inside each hole (41). A noble metal metallization forming individual pin electrodes (50), the first layer being in electrical contact with individual pins (18),
The second layer is a dielectric insulating material overlying the first layer, the third layer is a noble metal metallization forming a ground electrode overlapping the second layer, and the fourth layer is applied over the third layer. A non-conductive encapsulant having a coefficient of expansion compatible with the other layers, and large enough to allow the ground electrode to extend around the substrate and pass through the pin (18) without contacting the electrode. Continuous except for the holes in the hole and in electrical contact with the housing (10,12,14) along the two opposite edges, thereby splitting the current from the conductive pin (18) into two components Through the ground electrode (44) to the housing (10,12,1
The electric filter connector according to claim 12, wherein the electric filter connector flows to each ground connection portion on two sides of 4).