Patent Application
20240128664
The present invention relates to a coaxial electrical connector connected to a circuit board.
An example of this type of coaxial electrical connector, i.e., a coaxial electrical connector in which a dielectric body (insulating member), a center conductor, and an annular fitting are provided within an interior space of an outer conductor, has been disclosed in Patent Document 1. The interior space of the outer conductor is formed extending through the outer conductor in the vertical direction perpendicular to a mounting face on a circuit board. The dielectric body, which has a tubular configuration and is made of plastic, is disposed within said interior space at a location proximal to its bottom end, and the decoupling of the dielectric body and the center conductor is prevented by the fact that, after having been inserted into a retaining hole in the dielectric body, the vertically extending center conductor is retained in place by said dielectric body and, furthermore, by the fact that the annular fitting is attached from below.
The center conductor has a beveled protrusion protruding radially outwardly of said center conductor in the section inserted and retained within the retaining hole of the dielectric body, and, in a state in which the beveled protrusion abuts a stepped portion (indentation) formed in the inner peripheral surface of the retaining hole from below, is supported by the stepped portion from above. When the coaxial electrical connector is mounted to a circuit board, the center conductor, whose bottom end portion slightly protrudes from the bottom face of the outer conductor, is adapted to make contact with circuitry on the mounting face of the circuit board under contact pressure from above. At this time, contact pressure is generated between the center conductor and the circuitry of the circuit board because while the center conductor is constantly acted upon by a reaction force directed upwardly from the mounting face of the circuit board, the stepped portion of the dielectric body counteracts the above-mentioned reaction force by supporting the beveled protrusion of the center conductor from above.
According to Patent Document 1, the dielectric body, which is constructed as a single member, has the function of retaining the center conductor as well as the function of generating contact pressure between the center conductor and the circuitry of the circuit board. This dielectric body, which has a tubular configuration extending lengthwise in the vertical direction, is provided so as to fill the space between the inner peripheral surface of the outer conductor and the outer peripheral surface of the center conductor in the radial direction thereof. Consequently, within the vertical extent of the dielectric body, the band of usable frequencies becomes narrower in proportion to the absence of airspace in the above-mentioned radial direction between the inner peripheral surface of the outer conductor and the outer peripheral surface of the center conductor, which leads to a degradation of the broadband signal transmission quality in the coaxial electrical connector.
With such considerations in mind, it is an object of the present invention to provide a coaxial electrical connector that makes it easy to ensure excellent signal transmission quality even in broadband mode.
(1) The inventive coaxial electrical connector, which is a coaxial electrical connector connected to a circuit board, has: a metallic outer conductor, in which an interior space having an axis extending in the vertical direction perpendicular to the mounting face of the circuit board is formed disposed therethrough in the vertical direction; dielectric bodies, which are directly or indirectly retained within the interior space by the outer conductor; and a metallic center conductor, which extends in the vertical direction within the interior space, is retained by the dielectric bodies, and makes contact with the mounting face by means of its bottom end portion.
In the present invention, such a coaxial electrical connector is characterized by the fact that the dielectric bodies include a first dielectric body and a second dielectric body provided such that a space is formed within an offset from the first dielectric body at a location spaced apart from the first dielectric body in the vertical direction, the center conductor has an abutment portion abutting the second dielectric body from below, the first dielectric body retains the center conductor in the radial direction, and the second dielectric body, when pressed from below by the abutment portion, is resiliently deformable toward a space formed directly above the second dielectric body.
In the invention of (1), the dielectric bodies include a first dielectric body and a second dielectric body, with the first dielectric body having the function of retaining the center conductor in the radial direction, and the second dielectric body having the function of supporting the abutment portion of the center conductor from above. When the coaxial electrical connector is mounted to a circuit board, the bottom end portion of the center conductor is acted upon by a force (reaction force) directed upward from the circuit board. At this time, the second dielectric body is pressed by the abutment portion of the center conductor and is resiliently deformed upward, and the above-mentioned reaction force is counteracted by a resilient force generated by the second dielectric body. As a result, a state of contact under appropriate contact pressure is maintained between the contact portion of the center conductor and the circuit board.
In the invention of (1), the first dielectric body and second dielectric body are provided in a spaced relationship in the vertical direction, and a space is formed between the first dielectric body and second dielectric body. This means that within the extent in which this space is formed in the vertical direction, an airspace is present in the radial direction between the inner peripheral surface of the outer conductor and the outer peripheral surface of the center conductor. Therefore, in comparison with the conventional case, in which a single dielectric body extending lengthwise in the vertical direction is provided between the outer conductor and the center conductor, the band of usable frequencies becomes wider in proportion to the presence of the above-mentioned airspace, which makes it possible to ensure excellent signal transmission quality even in broadband mode.
(2) In the invention of (1), the first dielectric body may be provided downwardly of the second dielectric body.
(3) In the inventions of (1) or (2), the second dielectric body may have a higher deflection temperature under load than the first dielectric body. When the deflection temperature under load of the second dielectric body is higher than the deflection temperature under load of the first dielectric body, plastic deformation becomes unlikely even if the environment of use of the coaxial electrical connector becomes hotter. Therefore, with the abutment portion supported by the second dielectric body from above, the center conductor is unlikely to be moved upward from the regular position and the above-mentioned reaction force can be adequately counteracted by the resilient force of the second dielectric body. As a result, it becomes easier to maintain a state of contact under appropriate contact pressure between the contact portion of the center conductor and the circuit board.
(4) In the inventions of (1) through (3), the first dielectric body may have a lower dielectric permittivity than the dielectric permittivity of the second dielectric body. In the dielectric bodies, when the dielectric permittivity of the first dielectric body is made lower than the dielectric permittivity of the second dielectric body, the band of usable frequencies of the coaxial connector becomes wider than when the dielectric bodies are constituted by the second dielectric body alone and, as a result, makes it possible to ensure excellent signal transmission quality even in broadband mode.
(5) In the invention of (4), the first dielectric body may be made of polytetrafluoroethylene, and the second dielectric body may be made of polyetherimide.
The present invention can provide a coaxial electrical connector that makes it easy to ensure excellent signal transmission quality even in broadband mode.
A perspective view showing a coaxial electrical connector according to an embodiment of the present invention along with a circuit board, as viewed obliquely from above.
A perspective view showing the coaxial electrical connector of
(A) is a cross-sectional view of the coaxial electrical connector of
An embodiment of the present invention will be described below with reference to the accompanying drawings.
The circuit board P, on which the coaxial connector 1 is mounted, is a so-called “test board” used for performance testing of electronic components such as IC chips (not shown). In addition, the coaxial connector 1 is a so-called “test connector,” which is mounted to the circuit board P and is connected via a counterpart coaxial connector (not shown) and a coaxial cable (not shown) to measurement equipment (not shown) used to measure the electrical characteristics of the electronic components. As is shown in
The coaxial connector 1, which has an axis extending in the vertical direction (Z-axis direction) perpendicular to the mounting face of the circuit board P, has a symmetrical shape in the Y-axis direction. As shown in
The outer conductor 10 has a plate-shaped base portion 11, which extends parallel to the circuit board P, and a cylindrical barrel portion 12, which extends upward from the top face of the base portion 11. As shown in
As shown in
In addition, as shown in
The barrel portion 12 has a cylindrical configuration that has an axial centerline extending in the vertical direction and rises upwardly from the top face of the base portion 11. The barrel portion 12 has a larger diameter in the vertically intermediate portion thereof than in other portions.
The outer conductor 10 has formed therein an interior space 16, which has an axial centerline extending in the vertical direction and, as shown in
The large diameter space 16A is a cylindrical space formed within a vertical range spanning from the location of the top end of the barrel portion 12 to a location proximal to the bottom end. As shown in
The small diameter space 16B, which has a smaller diameter than the large diameter space 16A, is formed within a vertical range spanning from the location of the bottom end of the large diameter space 16A to the location of the top end of the bottom groove portion 14 of the base portion 11. As shown in
The center conductor 20, which has a pin-like configuration extending in the vertical direction, is provided at a location concentric with the interior space 16 when viewed in the vertical direction. As shown in
As shown in
As is shown in
As shown in
As shown in
The first dielectric body 31 is made, for example, of polytetrafluoroethylene (PTFE), and is fabricated by molding in an annular plate-like configuration. In the present embodiment, polytetrafluoroethylene, i.e., the material of the first dielectric body 31, has a dielectric permittivity of about 2.1 and a deflection temperature under load of about 55° C. As shown in
The first dielectric body 31, which is formed with an outside diameter that is slightly larger than the inside diameter of the hereinafter-described lower space 43B of the support 40, is press-fitted and accommodated within the lower space 43B. As is shown in
Although in the present embodiment the first dielectric body 31 has an annular plate-like configuration that is continuous around its entire circumference, as an alternative, for example, a notch portion may be formed at a single location in the circumferential direction. In such a case, the above-mentioned notch portion may be formed such that the first dielectric body 31 is completely severed in the circumferential direction, but it may instead be formed partially such that only a portion thereof is severed.
The second dielectric body 32 is made, for example, of polyetherimide (PEI), and is fabricated by molding in an annular plate-like configuration. In the present embodiment, polyetherimide, i.e., the material of the second dielectric body 32, has a higher dielectric permittivity than the dielectric permittivity of the first dielectric body 31 (about 3.1) and a higher deflection temperature under load than the deflection temperature under load of the first dielectric body 31 (about 197 to 200° C.). The second dielectric body 32, which is a separate component from the first dielectric body 31, is provided upwardly of the first dielectric body 31 at a location spaced apart from the first dielectric body 31. The second dielectric body 32 is formed with an outside diameter that is slightly smaller than the outside diameter of the first dielectric body 31. In addition, the second dielectric body 32, which is slightly smaller than the inside diameter of the hereinafter-described lower space 43B of the support 40, has a slight gap formed in the radial direction between the outer peripheral surface of the second dielectric body 32 and the inner peripheral surface of the lower space 43B. It should be noted that the outside diameter of the second dielectric body 32 may be equal to the inside diameter of the lower space 43B. The second dielectric body 32 has a second through-hole portion 32A formed through said second dielectric body 32 in the vertical direction. The second through-hole portion 32A is formed with an inside diameter that is substantially equal to the outside diameter of the second attachment portion 23B of the center conductor 20.
In addition, a notch portion (not shown) is formed in the second dielectric body 32 at a single location in the circumferential direction. Therefore, the second dielectric body 32 is rendered discontinuous at the location of the above-mentioned notch portion in the circumferential direction. It should be noted that the above-mentioned notch portion may be formed such that the second dielectric body 32 is completely severed in the circumferential direction, but it may instead be formed partially such that only a portion thereof is severed.
The support 40, which has a substantially cylindrical configuration, is accommodated within the interior space 16 of the outer conductor 10. As shown in
An interior space 43, which is coaxial with the interior space 16 of the outer conductor 10 and is disposed through the support 40, is formed in the support 40. As shown in
A supporting portion 44 radially inwardly protruding from the inner peripheral surface of the interior space 43 is provided at a location between the upper space 43A and the lower space 43B in the vertical direction. The supporting portion 44 is formed around the entire circumference of the interior space 43, and the space enclosed by this supporting portion 44 constitutes an intermediate space 43C. The intermediate space 43C, which has a smaller diameter than the upper space 43A and lower space 43B, accommodates the top end portion of the coupling portion 23 of the center conductor 20. In addition, as described below, the intermediate space 43C is adapted to permit resilient deformation of the second dielectric body 32 by receiving from below a portion of the second dielectric body 32 resiliently deformed upward. As shown in
The coaxial connector 1 is manufactured in accordance with the following procedure. First, the second dielectric body 32 is attached to the second attachment portion 23B by inserting the center conductor 20, at the bottom end side, i.e., the side of the contact portion 22, through the second through-hole portion 32A of the second dielectric body 32. Although in the present embodiment the second through-hole portion 32A has a smaller diameter than the intermediate portion 23C of the coupling portion 23, a notch portion is formed in the second dielectric body 32 and, as the intermediate portion 23C is inserted through the second through-hole portion 32A, the second dielectric body 32 is deformed to produce an opening at the location of the notch portion in the circumferential direction, thereby permitting insertion of the intermediate portion 23C. Further, when the second dielectric body 32 passes through the area of the intermediate portion 23C and reaches the area of the second attachment portion 23B, the second dielectric body 32 deforms and closes at the location of the notch portion. As a result, the inner peripheral surface of the second dielectric body 32 makes surface contact with the outer peripheral surface of the second attachment portion 23B, and the second dielectric body 32 retains the second attachment portion 23B in place. In this condition, the notch portion of the second dielectric body 32 may be completely closed or may be slightly open.
Once the second dielectric body 32 is attached to the second attachment portion 23B, the top face of the second abutment portion 23C-2 of the center conductor 20 makes surface contact with, and abuts, the bottom face of the second dielectric body 32. It should be noted that at this time it is not essential for the second abutment portion 23C-2 to abut the second dielectric body 32, and the second abutment portion 23C-2 may be adapted to abut the second dielectric body 32 and support said second dielectric body 32 from below only when the coaxial connector 1 is mounted to the circuit board P.
Next, the center conductor 20 having the second dielectric body 32 attached thereto is inserted into the interior space 43 of the support 40 from below. At this time, the center conductor 20 is inserted until the second dielectric body 32 reaches the top portion of the lower space 43B of the interior space 43. As a result, the coupling portion 23 of the center conductor 20 is accommodated within the lower space 43B and intermediate space 43C.
Next, the first dielectric body 31 is attached to the first attachment portion 23A from below. At this time, the center conductor 20 is inserted at the bottom end side, i.e., the side of the contact portion, through the through-hole portion 31A of the first dielectric body 31. Once attached to the first attachment portion 23A, the first dielectric body 31 makes surface contact with, and abuts, the first abutment portion 23C-1 from below. In addition, in the present embodiment, the first dielectric body 31, whose outside diameter is slightly larger than the inside diameter of the intermediate space 43C, is press-fitted into the lower space 43B of the interior space 43 from below. Therefore, the first dielectric body 31 is acted upon and compressed by a pressure force directed radially inwardly by the inner peripheral surface of the lower space 43B, and the outer peripheral surface of the first attachment portion 23A is firmly retained by the inner peripheral surface of the first through-hole portion 31A.
On the other hand, in the present embodiment, the outside diameter of the second dielectric body 32 is slightly smaller than the inside diameter of the intermediate space 43C. Therefore, the second dielectric body 32 is not acted upon by the pressure force from the inner peripheral surface of the lower space 43B. It should be noted that the second dielectric body 32 may be formed such that its outside diameter is slightly larger than the inside diameter of the intermediate space 43C, in which case the second dielectric body 32 is subject to and compressed by a pressure force directed radially inwardly by the inner peripheral surface of the lower space 43B and the outer peripheral surface of the second attachment portion 23B is firmly retained by the inner peripheral surface of the second through-hole portion 32A. In addition, the second dielectric body 32 is supported by the supporting portion 44 of the support 40 from above.
With the center conductor 20 and the dielectric bodies 30 accommodated within the interior space 43, the second dielectric body 32 has its radially inner section supported by the second abutment portion 23C-2 from below while its radially outer section is supported by the supporting portion 44 of the support 40 from above (see
Next, the support 40 is press-fitted and accommodated within the interior space 16 of the outer conductor 10 from above. The support 40 is press-fitted until its bottom face abuts the top face of the stepped portion 17 of the outer conductor 10. As a result, as shown in
The manner of use of the coaxial connector 1 will be described next. In the present embodiment, during use, the coaxial connector 1 is mounted to a connector pattern portion of a circuit board P (test board) on which electronic components to be performance tested (IC chips, etc.) are mounted. First, the coaxial connector 1 is disposed on the circuit board P such that the mounting hole portions 13 of the outer conductor 10 are aligned with screw holes (not shown) provided in the circuit board P. The coaxial connector 1 disposed on the circuit board P in this manner is attached to the circuit board P by screwing screw members (not shown) from below into the mounting hole portions 13 and the screw holes in the circuit board P.
When the coaxial connector 1 is attached to the circuit board P, the bottom end face of the contact portion 22 of the center conductor 20 is pressed from above against the signal pattern P1 on the circuit board P, while the bottom end face of the protrusion 15 of the outer conductor 10 is pressed from above against the ground pattern P2 on the circuit board P. As a result, the center conductor 20 and the signal pattern P1, as well as the outer conductor 10 and the ground pattern P2, make contact with each other under contact pressure and enter an electrically conductive state.
As discussed previously, because the bottom end face of the contact portion 22 of the center conductor 20 is located slightly downwardly of the bottom end face of the protrusion 15 of the outer conductor 10, when the bottom end face of the contact portion 22 is pressed against the signal pattern P1 of the circuit board P from above, the bottom end portion of the contact portion 22 is acted upon by a force (reaction force) directed upward from the signal pattern P1, and the center conductor 20 moves upward. As the center conductor 20 moves upward, the radially inner section of the first dielectric body 31, under the action of friction with the outer peripheral surface of the first attachment portion 23A, undergoes resilient deformation so as to be displaced upward.
In addition, when the center conductor 20 moves upward, the second abutment portion 23C-2 of the center conductor 20 presses against the radially inner section of the second dielectric body 32 from below. The inner section of the second dielectric body 32 subject to pressure undergoes resilient deformation so as to be displaced upward, and a portion of said inner section enters the intermediate space 43C of the support 40 from below. In other words, resilient deformation of the second dielectric body 32 is made possible by the intermediate space 43C. Such resilient deformation of the second dielectric body 32 enables upward movement of the center conductor 20. In the present embodiment, vertical resilient deformation is facilitated by the fact that the second dielectric body 32, which has an annular plate-like configuration, is relatively thin in the through-thickness direction, i.e., in the vertical direction. When the second dielectric body 32 undergoes upward resilient deformation, the above-mentioned reaction force is counteracted by the resilient force generated by the second dielectric body 32. A state of contact between the contact portion 22 and the signal pattern P1 is maintained under appropriate contact pressure as a result of counteracting the above-mentioned reaction force with the help of the resilient force generated by the second dielectric body 32.
In the present embodiment, the first dielectric body 31 and second dielectric body 32 are provided in a spaced relationship in the vertical direction and, as shown in
In addition, a counterpart coaxial connector (not shown) attached to one end of a coaxial cable (not shown) is matingly connected to the coaxial connector 1 from above. As a result, a counterpart center conductor (not shown) of the counterpart coaxial connector is connected to the connection portion 21 of the center conductor 20 of the coaxial connector 1, and a counterpart outer conductor (not shown) of the counterpart coaxial connector is connected to the barrel portion 12 of the outer conductor 10 of the coaxial connector 1. In addition, the other end of the coaxial cable is connected to measurement equipment (not shown) used to measure electrical characteristics. When testing the performance of electronic components, a voltage is applied to electronic components mounted to a test board and their electrical characteristics are measured using measurement equipment.
The above-described performance testing of electronic components (IC chips, etc.) is conducted based on a hypothetical environment of use with a wide temperature range (e.g., −55° C. to 105° C.). Therefore, in the coaxial connector 1 used for performance testing, it is highly desirable to prevent the state of contact with the circuit board P from being influenced by temperature changes in the above-mentioned temperature range as much as possible. In the present embodiment, the dielectric bodies 30 include two members, i.e., the first dielectric body 31 and the second dielectric body 32, that are made of different materials. The second dielectric body 32, which supports the second abutment portion 23C-2 of the center conductor 20 from above, is made of polyetherimide and has a higher deflection temperature under load than the first dielectric body 31, which is made of polytetrafluoroethylene. Accordingly, since the second dielectric body 32 is unlikely to undergo plastic deformation even if the thermal environment becomes hotter, the center conductor 20 that is acted upon by the reaction force from the circuit board P is unlikely to be moved upward from the regular position, and the above-mentioned reaction force can be adequately counteracted by the supporting force of the second dielectric body 32. As a result, it becomes easier to maintain a state of contact under appropriate contact pressure between the contact portion 22 of the center conductor 20 and the signal pattern P1 of the circuit board P.
In the present embodiment, since the first dielectric body 31 that retains the outer peripheral surface of the first attachment portion 23A of the center conductor 20 is made of polytetrafluoroethylene and has a higher resilience than the second dielectric body 32, which is made of polyetherimide, it can make contact with the outer peripheral surface of the first attachment portion 23A at a higher contact pressure and, therefore, can retain the center conductor 20 more firmly than when the dielectric bodies 30 are constituted by the second dielectric body 32 alone.
In addition, of the two dielectric bodies 30 in the present embodiment, the first dielectric body 31 has a lower dielectric permittivity than the second dielectric body 32, and for this reason, the band of usable frequencies of the coaxial connector 1 becomes wider than when the dielectric bodies 30 are constituted by the second dielectric body 32 alone, which makes it possible to ensure excellent signal transmission quality even in broadband mode.
Although in the present embodiment the dielectric bodies 30 are retained directly by the support 40, in other words, the dielectric bodies 30 are retained indirectly by the outer conductor 10 through the medium of the support 40, it is not essential to provide a support and, for example, the dielectric body may be adapted to be retained directly by the outer conductor without providing a support.
Although in the present embodiment the coaxial connector 1 is used for the purpose of performance testing of electronic components mounted to the circuit board P, the test objects are not limited thereto, and the connector may be employed, for instance, for the purpose of performance testing of the circuit board itself. At this time, it is not essential to mount electronic components on a circuit board.
Although in the present embodiment the second dielectric body 32 is provided upwardly of the first dielectric body 31, as an alternative, the second dielectric body may be provided downwardly of the first dielectric body. In this case, a second abutment portion may be provided in the center conductor at a location that permits abutment against the second dielectric body from below. In addition, upward resilient deformation of the second dielectric body may be enabled by the space (airspace) formed between the first dielectric body and the second dielectric body in the vertical direction, i.e., below the first dielectric body and above the second dielectric body.
Although the present embodiment describes an example in which the coaxial connector 1 is used as a so-called test connector, its uses are not limited thereto and it may, for example, be mounted on circuit boards provided in electronic products.
Although in the present embodiment the entire signal pattern P1 and the entire ground pattern P2 are provided on the mounting face (top face) of the circuit board P, as an alternative, at least a portion of the signal pattern and ground pattern may be provided, for example, such that the patterns extend along the surface of a circuit board on the backside (bottom face) or in the interior of the circuit board. In this case, corresponding patterns positioned differently in the through-thickness direction of the circuit board may be connected by vias and the like.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-166708 | Oct 2022 | JP | national |
