JP4740220B2 - Filter connector with high frequency shield - Google Patents

Description

  One type of filter connector described in US Pat. No. 6,896,552 includes a pair of flexible circuit boards or substrate portions having holes through which pins extend. A signal trace extending annularly around each hole is electrically connected to the corresponding pin by a solder joint. In a filter component such as a capacitor, each has one terminal connected to the signal trace and the other terminal connected to the ground plane. There is a gap between the signal trace and the ground plane, and a high frequency (500 MHz to 1000 MHz) stray signal passes through the gap to a circuit connected to one end of the pin. can do. Such stray signals constitute EMI (electromagnetic interference) that results in “noise” in the circuit. A device that blocks the majority of such EMI from passing through such a gap would be valuable.

[Outline of the present invention]
In accordance with one embodiment of the present invention, a high frequency EMI (electromagnetic interference) shield is provided for a type of filter connector in which a gap exists between the ground trace and each of the plurality of signal traces. In addition, the EMI shield is configured to facilitate soldering of the signal trace to a projecting pin that projects through a hole in the signal trace. A filter connector places a filter component, such as a capacitor, on a first insulating substrate with one capacitor terminal connected to a signal trace (connecting to a pin) and a second terminal connected to the ground plane of the substrate. Format. A gap must be left between ground and signal traces to prevent short circuits. High frequency EMI can pass through such a gap to a circuit connected to one end of the pin. The present invention provides a second insulating substrate that holds conductive traces that function as EMI shields. The shield trace is located on a surface that is only slightly spaced from the first substrate (with a dielectric layer between them). The shield trace covers the gap and the shield trace can be coupled to the signal trace. Any EMI that passes through the gap between ground and the signal trace is blocked by the shield trace and does not reach the circuit connected to one end of the pin.

  Each pin is soldered to a signal trace located on a first circuit board located below the second board. In order to allow solder to be applied to the signal traces of the first substrate through the second substrate, the pin-receiving holes of the second substrate have notches. Each hole in the second substrate includes a circular portion that closely receives the pins and a notch extending from the circular portion. A dispenser that dispenses the amount of solder (and solder flux) can be inserted through the notch to dispense solder to the signal trace level of the first board so that a large area connection can be ensured there. . The solder can further flow through the portion of the shield trace in the circular portion of the hole to connect the shield trace with the pin and signal trace.

  The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when read in conjunction with the accompanying drawings.

[Description of preferred embodiments]
FIG. 1 illustrates a prior art filtered connector 10 that includes a plurality of pins 12 attached to a combination of a pair of circuit board assemblies 14,16. The filter connected to each pin includes a ferrite bead 20 and a pair of capacitors each attached to one of the circuit board assemblies. The ferrite bead and the pair of capacitors form a Pi filter as described in US Pat. No. 6,896,552. The filtered connector is configured to be attached to a grounded metal shell 18 as shown in FIG. One end of the pin is connected to sensitive circuitry 22 located on an extension of a grounded metal shell that protects the circuit from electromagnetic interference (EMI). However, electromagnetic interference can reach this circuit by leaking through the connector 10, and the present invention leads to a connector structure that minimizes leakage of such electromagnetic interference.

FIG. 3 shows a portion of one of the pins 12 and a combination of two circuit board assemblies 14, 16 located along the pins. Each circuit board combination, such as 14, includes a first circuit board assembly 24 including a dielectric first circuit board 26, which may be a flexible board. The substrate 26 has pin-receiving holes 28 that each receive one of the conductive pins 12. A ground plane 30 in the form of a conductive layer or trace is inherently located on the top surface of the first substrate, and a plurality of conductive signal traces 32, 60 are each located on the first substrate. Each upper signal trace 60 extends to a ring around the pin hole. The lower signal trace 32 can be located on only one side of the pin hole to reach the capacitor terminal 44.

Filter component 40, such as a capacitor, has one terminal 42 connected to ground plane 30 and another terminal 44 connected to signal trace 32. The circuit board has a plated-through aperture 50 with a ground plane extending to the ground plane 52 on the lower surface of the first board to facilitate soldering to the capacitor terminals. The upper signal trace is connected to the lower signal trace through a solder joint 90. There is a gap 62 between the upper ground plane 30 and the upper signal trace 60.

  High frequency electromagnetic interference (EMI) in the order of magnitude of 750 MHz, and particularly in the range of 500 MHz to 1000 MHz, can pass through gaps 54, 62 and connect to one end of the pin And then upsets such a circuit. The present invention is directed to an improvement to prevent most of such EMI from passing through the connector and reaching such a circuit.

Applicants provide a pair of second circuit board assemblies 70, each having a dielectric second substrate 75 and conductive shield traces 72 thereon that act as electromagnetic interference shields. Each second substrate assembly is attached to a corresponding first substrate assembly facewise adjacent and desirably opposite. Here, the first substrate is a flexible circuit board, and the second substrate is preferably a stiffener board. Conductive shield trace 72 acts as an EMI shield trace and is positioned over the gap 62 between each upper signal trace 60 and ground plane 30. Some of the high frequency EMI in the environment travels along the path 76, 78 through the gap 62. In this way, EMI is blocked by shield trace 72 and prevented from reaching a sensitive circuit connected to the pin. A dielectric cover layer 74 is located against the shield race 72 and electrically isolates it from the ground plane 30 and the signal trace 60 at the top surface of the first substrate.

  Applicants provide a shield trace having overlapping ends 80, 82 that extend beyond a shield trace central portion 84 located directly on top of the gap 62. Overlapping ends 80, 82 are located directly above the ground and signal and race. Overlapping edges prevent EMI from passing along an angle with respect to vertical V. The amount of overlap required for a good shield depends on how the shield trace closes from the gap. Applicant places the shield trace vertically so that it does not exceed 1 mm, and preferably does not exceed 0.5 mm from the nearest gap, and the shield trace is spaced from the gap. It is arranged to be closer than 1/10 of the width. In some cases, the shield traces will preferably be located at the top of most of each gap, and preferably at least 90% of each gap, if not all.

Although not necessarily necessary, the shield trace 72 is preferably electrically connected to the pin 12 and to the signal trace 32. However, it is essential that signal trace 32 (and 60) be connected to the pins. Such a connection is usually made through a solder joint 90. In the arrangement of FIG. 3, the second circuit board assembly 70 tends to obstruct downward vertical access to the area between the pin 12 and the hole wall 32h of the signal trace 32 where the solder is to be deposited. There will be. The deposition of the applicant solder (which is melted by wave soldering (wave SOLDERING) in an oven after), the pin having a notch in the dielectric second base plate 75 - by forming a receiving hole 92, facilitating To. A dispenser 102 with a thin dispenser nozzle 104 dispenses solder into or against the region 106 located adjacent to both the pin 12 and the signal trace hole wall 32h (preferably within 1 mm). In order to pass through the notch.

FIG. 5 shows pin-receiving holes 92 in the dielectric second substrate 75. Each pin-receiving hole 92 includes a circular hole portion 110 that extends around the axis 112 of the hole, preferably at an angle A greater than 180 °. Angle A is desirably at least 220 ° and in practice is 300 °. The notches 100 protrude radially away from the axis. The circular hole portion 110 precisely positions the holes of the second substrate around the pins. The notch 100 receives the nozzle 104 of the dispenser 102 as shown in FIG. 3, and an amount of small solder balls surrounded by the solder flux is deposited on the wall of the hole. FIG. 3 shows that in many cases the solder 90 further has a portion 114 that solders the pin to the shield trace 72 at the side of the hole opposite the notch, which connects the shield trace to the signal trace 32. . The solder joint solder will always make a connection for the upper and lower signal traces 60, 32.

To assemble the connector of FIG. 3, the applicant first assembles the lower and upper assemblies. Subsequently, the applicant assembles the lower circuit board assembly 16 on the plurality of pins 12. This includes placing a second circuit board assembly 70, which is the dielectric second base plate 75, the shield traces 72, and the upper dielectric cover layer 74 of the first circuit board assembly 24 in the lower The lower first circuit board assembly 24 includes ground and signal traces 50, 32 on the dielectric first circuit board 26 and capacitors 40 soldered in place at each pin-receiving hole, With a pin protruding through. Subsequently, a dispenser 102 (and preferably having a number of the same) is used to place a solder deposit on the wall of the hole in the signal trace. Next, a ferrite bead 20 is placed on the pin and an upper circuit board assembly identical to the lower board assembly is placed on the pin. A dispenser is used to place the solder deposit on the wall of the signal trace hole. This assembly is placed in an oven to melt the solder to produce the final assembly shown in FIG.

The fact that solder deposits (solder balls and flux) were first deposited in the region of the first circuit board assembly 24 located in or under the notch is determined from close observation of the solder joints. be able to. The solder joint 90 is usually slightly higher in the initially deposited configuration.

  In the connector of the type shown in FIG. 3 designed by the applicant, each pin-receiving hole at 32 h has a diameter of 30 mils (1 mil equals 1/1000 inch) (= 0.762 mm). The first substrate 26 has a thickness of 5 mils (= 0.127 mm) and each second substrate has a thickness of 30 mils (= 0.762 mm).

  Even if directions such as “vertical”, “up”, “bottom”, etc. are used as illustrated to describe the invention, the invention should be used in any direction. Can do.

  Thus, the present invention has at least one first circuit board assembly having a ground and a signal trace and a gap between them through which high frequency EMI (electromagnetic interference) energy can pass if not shielded. An improvement is provided for a connector of the type having a body. The present invention provides a second circuit board, such as a reinforcement substrate, having shield traces thereon and preferably having a dielectric isolation layer over the shield traces. The second circuit board is disposed to face the first circuit board, and preferably the isolation layer is disposed opposite the surface of the first circuit board (such as the surface of a ground trace). . The shield traces cover most and preferably all of the gap between the signal on the first circuit board and the ground trace to prevent EMI that would otherwise pass through the gap, and preferably the majority of the gap. And overlap. The second circuit board desirably has a pin-receiving hole having a circular portion and having a notch extending radially away from the axis of the hole. A dispenser can be inserted through each notch to place solder deposits on the walls of the signal trace holes located on the first substrate.

  It will be appreciated that modifications and changes can be readily made by those skilled in the art, even if specific embodiments of the invention have been described and illustrated, and the claims are intended to make such modifications and changes. It is intended to be construed as included in the scope.

FIG. 3 is an isometric view of a filtered connector in the present invention. FIG. 2 is a side elevational view of the connector of FIG. 1. FIG. 2 is a cross-sectional side view of a portion of the connector of FIG. 1 showing one pin and two circuit board assembly portions connected to the pin. FIG. 4 is a view on the line 4-4 of FIG. 3 showing the underside of the first circuit board. FIG. 5 is a view on the line 5-5 of FIG. 3 showing the underside of the second circuit board.

Claims (5)

A filtered connector,
A first circuit board assembly (24) including a dielectric first circuit board (26) having opposing faces;
The dielectric first circuit board includes a plurality of pin-receiving holes (28) and a plurality of pins (12) each protruding through one of the pin-receiving holes, each at least partially. A plurality of signal traces (60) extending around one of the pin-receiving holes and connected to one of the pins projecting through the pin-receiving hole ; and the first dielectric circuit A ground plane (30) located on one of the surfaces of the substrate but spaced from the pin-receiving hole and from the signal trace, and the ground plane is the ground plane and the ground plane Leaving the gap with a gap region by a gap (62) located between the signal trace and one of the signal trace and the first terminal (42) each connected to the ground plane Connected And a plurality of filter elements (40) having two terminals (44),
Said dielectric located adjacent with respect to the first circuit board and the surface, and a dielectric second substrate (75), a second and a plurality of second holes, each receiving one of said pins (92) A circuit board assembly (70);
Connector comprising a plurality of shield traces (72) and extending over the majority of the located on the dielectric second substrate and each of the regions of the gap.   The connector of claim 1, wherein each of the plurality of shield traces is electrically connected to a corresponding one of the pins. Wherein each of said dielectric second substrate said second hole (92) is circular in shape having a notch (100) extending radially outwardly from the axis (112) and a circular hole,
Each of the signal traces is soldered to a corresponding one of the pins by a solder joint (90) that includes an amount of solder originally deposited through one of the notches.
The connector according to claim 1. Said first circuit board assembly includes a dielectric first circuit board (26) having an upper surface and a lower surface, said ground plane (30) is located on the upper surface of the original said dielectric first circuit board and the dielectric A plated through hole (50) extending to the lower surface in the first circuit board, and a ground plane portion (52) connecting to the filter component on the lower surface;
The dielectric second substrate (75) is a reinforcing substrate, the shield trace (72) is located on the lower surface of the dielectric second substrate, and a dielectric cover layer (located on the lower surface of the shield trace). 74),
It said dielectric second substrate is located above the dielectric first circuit board having the dielectric cover layer positioned adjacent relationship to the plane to the ground plane, and the said ground plane (30) Having said shield trace located within 1 mm of signal trace (60);
The connector according to claim 1. Each of the signal traces is soldered to a corresponding one of the pins by a solder joint (90), and the location (114) of each of the plurality of solder joints is further in contact with a corresponding shield trace (72). Item 1. The connector according to item 1.

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