Patent Description:
Radio frequency (RF) connectors can be mounted to printed circuit boards (PCB) of electronic devices, e.g. measurement instruments, in order to contact the respective apparatus with coaxial cables or the like. On the one hand, it is beneficial if the installation process of these connectors is kept as quick and simple as possible without the need for complex and expensive mounting tools. On the other hand, the mechanical and electrical contact should be stable and durable. Amongst others, the RF connection should be reasonably free of mechanical stress.

Such a PCB may be accommodated within a cover or enclosure, e.g. of a device housing, which may be used to dissipate heat from the PCB. Consequently, if an RF connector is attached directly at or near such a part of the enclosure, the temperature may rise also at contact surfaces of the RF connector.

<CIT> describes a coaxial connector with thermal decoupling.

<CIT> describes a coaxial connector for a PCB for providing a reliable signal connection to the PCB while isolating the PCB from mechanical loads that are applied to the connector.

<CIT> describes an apparatus for regulating temperature of a process kit in a semiconductor wafer-processing chamber.

Against this background, there is a need to find solutions for thermally decoupled RF connections to PCBs that are resilient against mechanical stress and yet simple in construction.

To this end, the present invention provides an RF connection system and an electronic device with the features of the independent claims.

According to a first aspect of the invention, an RF connection system for contacting a printed circuit board (PCB) comprises an RF connector configured to be mounted to the PCB; and a mounting element configured to be mounted between a heat sink of the PCB and the RF connector to thermally decouple the RF connector from the heat sink, wherein the mounting element comprises at least one alignment interface for aligning the RF connector with respect to the heat sink. The mounting element comprises a thermally insulating material. The at least one alignment interface comprises several fastening portions for fastening the RF connector to the mounting element the mounting element to the heat sink, respectively. Each fastening portion is configured as a fastening hole for receiving a fastening element.

According to a second aspect of the invention, an electronic device comprises a PCB; a heat sink connected to the PCB and configured to dissipate heat generated by the PCB; and an RF connection system according to the invention mounted between the heat sink and the PCB.

The present invention is based on the insight that both thermal and mechanical stability can be achieved in a very simple manner by decoupling the RF connector from the heat sink with a mechanical element that can be used at the same time to align the RF connector relative to the heat sink. Mechanical tolerances can thus be compensated and the mechanical rigidity of the connection between the RF connector and the electronic device can be improved on a general level.

Further embodiments of the present invention are subject of the subordinate claims and of the following description, referring to the drawings.

According to the invention, the mounting element comprises a thermally insulating material.

For example, the mounting element may comprise and/or be made of a plastic or composite material with relatively low thermal conductivity and yet high rigidity. On the other hand, also metal materials, that is, metals, metal alloys or metal composites, may be suitable in case their thermal conductivity is relatively low (e.g. steel in contrast to aluminum alloys that are usually used for heat sinks due to their very high thermal conductivity).

According to the invention, the at least one alignment interface comprises several fastening portions for fastening the RF connector to the mounting element and the mounting element to the heat sink, respectively.

Each fastening portion may be used individually to compensate tolerances between the RF connector and the heat sink and/or to align both components with each other.

According to the invention, each fastening portion is configured as a fastening hole for receiving a fastening element.

According to an embodiment of the invention, the PCB may be configured with at least one groove or elongated hole running alongside a mounting portion of the PCB, on which the RF connector is mounted to the PCB.

For example, two elongated holes, grooves or slits may run along both sides of the mounted RF connector basically parallel to a plug-in direction of the connector, that is, perpendicular to the direction of maximal stress (e.g. in case of joggling or pulling at a plugged-in cable). These structures may help to compensate, for example, for distortions and other mechanical stress when assembling the mounting element, the heat sink and the RF connector within the electronic device. On the other hand, such mechanical stress may also be relocated to areas of the PCB where they are not an issue in order to keep away mechanical loads from the RF connector and the mounting portion of the PCB.

According to an embodiment of the invention, the mounting element may be configured with at least one tooth configured to engage the at least one groove or elongated hole to deflect mechanical stress from the mounting portion.

In a particular example, the mounting element may be configured as a plate arranged horizontally on a recess of the heat sink (e.g. a housing) and having several protrusions at an underside (e.g. teeth or webs), which may engage corresponding slits or holes within the PCB adjacent to the installed RF connector in order to deflect and compensate any mechanical stress occurring at the mounting portion of the PCB.

According to an embodiment of the invention, the heat sink may be a thermally conductive enclosure of the PCB.

In an example, an upper or lower cover shell of the housing may serve as heat sink and may be made from a highly conductive material in order to dissipate heat, e.g. an aluminum alloy. The cover shell may feature a recess and/or opening into which the mounting element may be placed adjacent to the PCB with the RF connector.

For a more complete understanding of the present invention and advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings. The invention is explained in more detail below using exemplary embodiments which are specified in the schematic figures of the drawings, in which:.

The appended drawings are intended to provide further understanding of the embodiments of the invention. They illustrate embodiments and, in conjunction with the description, help to explain principles and concepts of the invention. Other embodiments and many of the advantages mentioned become apparent in view of the drawings. The elements in the drawings are not necessarily shown to scale.

In the drawings, like, functionally equivalent and identically operating elements, features and components are provided with like reference signs in each case, unless stated otherwise.

<FIG> and <FIG> show explosive perspective views of electronic devices <NUM> being equipped with RF connection systems <NUM> according to embodiments of the present invention.

Radio frequency (RF) and/or coaxial connectors are a key component in RF and microwave applications where they are frequently used in test and measurement equipment to connect coaxial cables with the respective read-out or signal generating system components, e.g. in signal and spectrum analyzers and/or generators, test systems for antennas and other electromagnetic equipment, oscilloscopes etc. In most of these applications it is paramount to utilize connectors that allow accurate and repeatable measurements while being durable and highly performant at the same time.

In light of the above, a suitable RF connection should not only be easy to assemble in order to safe costs and manufacturing time but should also provide a connection that is mechanically and electrically stable.

On the other hand, outer portions of such measuring instruments (e.g. a cover, an enclosure, assembly portions, modules etc.) are often used as heat sinks for cooling the electronic circuits within the respective instrument. If an RF socket is connected directly to such a portion, high temperatures could occur at the RF socket that could adversely affect manual handling of these devices. Hence, also cooling issues should be taken into account when providing a suitable RF connector.

With reference to the embodiments shown in <FIG> and <FIG>, electronic devices <NUM>, e.g. measuring instruments, are described in the following that offer improvements to the above mentioned issues. In both cases, the respective electronic device <NUM> comprises a PCB <NUM> housed between an upper enclosure cover <NUM> and a lower enclosure cover <NUM>. All three of these components are recessed on one side (right-hand side in <FIG>) to accommodate the RF connection system <NUM>.

In order to dissipate heat generated by the PCB <NUM> during operation, the upper enclosure cover <NUM> is made from a material with suitable thermal conductivity, e.g. an aluminum alloy or similar, such that it functions as a heat sink <NUM> for the PCB <NUM>. However, it is to be understood that in other embodiments also the lower enclosure cover <NUM> may additionally or alternatively be provided with these properties accordingly.

Specifically, the RF connector <NUM> of the exemplary embodiments of <FIG> and <FIG> comprises an RF connector <NUM> mounted on top of the PCB <NUM> within a mounting portion of the PCB <NUM>. The RF connector <NUM> may be an integrated component that is soldered (or otherwise fastened) to the PCB <NUM> as one part. However, the RF connector <NUM> may also be assembled from several subcomponents on top of the PCB <NUM>, e.g. by first soldering a basic RF socket to the PCB featuring a pre-installed coaxial terminal and subsequently attach an RF port to the RF socket that may adapt the coaxial terminal for larger connectors/cables, for example.

The RF connector <NUM> provides a plug-in port <NUM> with a coaxial terminal inside (the latter is not visible in the figures). The RF connector <NUM> in the shown embodiment features a small box-like or cuboid housing portion resting upon the mounting portion <NUM> of the PCB <NUM> and a plate-shaped flange portion arranged on an outer side of the electronic device <NUM> and having a cylindrical extension with a through-hole serving as plug-in port <NUM> for other RF connectors, via which coaxial cables and the like may contact the PCB <NUM>. The PCB <NUM> is configured with two elongated holes <NUM> or slits running alongside the mounting portion <NUM> of the PCB <NUM>, that is, adjacent to the RF connector <NUM> and parallel to a plug-in direction of the same.

The electronic devices <NUM> of <FIG> and <FIG> each further comprise a mounting element <NUM> mounted between the upper enclosure cover <NUM> serving as heat sink <NUM> and the RF connector <NUM> to thermally decouple the RF connector <NUM> from the heat sink <NUM>. To this end, each mounting element <NUM> is formed from a thermally insulating material, e.g. plastic.

The mounting elements <NUM> of both embodiments are configured with alignment interfaces <NUM> for aligning the RF connector <NUM> with respect to the heat sink <NUM>. More specifically, the alignment interfaces <NUM> comprise several fastening portions <NUM> configured as fastening holes for receiving fastening elements <NUM> in order to fasten the RF connector <NUM> to the mounting element <NUM> and the mounting element <NUM> to the heat sink <NUM>, respectively. The alignment interfaces <NUM> thus serve as alignment and/or tolerance compensation means during installation of the assembly.

The purpose of the mounting elements <NUM> is thus twofold. On the one hand, they are used to thermally decouple the RF connector <NUM> from the heat sink <NUM>. On top of that, they are used as alignment means to compensate potential tolerances within the assembly.

As can be seen in the figures, the mounting elements <NUM> are accommodated in a graded recess within the upper enclosure cover <NUM>, which also features correspondingly formed fastening holes such that the mounting elements <NUM> may be fixed in the recess by means of fastening elements <NUM>. It is to be understood of course that the depicted configurations are mere examples. In a similar vein, the mounting elements <NUM> could also be mounted in/on the lower enclosure cover <NUM> or in other portions of a housing of the electronic device <NUM>.

As can be seen in <FIG> and <FIG>, the mounting elements <NUM> are provided with different shapes in both embodiments. In the embodiment of <FIG>, the mounting element <NUM> has an elongated rectangular bar-like shape where the fastening portions <NUM> are arranged at both distal ends (two on top for fixing the mounting element <NUM> to the upper enclosure cover <NUM> and two on a lateral side for attaching the RF connector <NUM>).

In the embodiment of <FIG>, the mounting element <NUM> has a plate-shaped upper portion resting on the graded recess in the upper enclosure cover <NUM> and fastened there by means of four fastening holes at each corner. Two teeth <NUM> protrude from a lower side of the plate-shaped portion, each tooth <NUM> configured with two fastening holes for attachment of the RF connector <NUM>. The teeth <NUM> are adapted to engage the elongated holes <NUM> at each lateral side of the mounting portion <NUM>. In this vein, mechanical stress may be deflected from the mounting portion <NUM>. For example, mechanical loads induced in the RF connector <NUM> from the outside may be absorbed and/or compensated by the teeth <NUM> of the mounting element <NUM> such that mechanical stress can be kept away from the mounting portion <NUM>.

Claim 1:
RF connection system (<NUM>) for contacting a printed circuit board, PCB, (<NUM>), the RF connection system (<NUM>) comprising:
an RF connector (<NUM>) configured to be mounted to the PCB (<NUM>); and
a mounting element (<NUM>) configured to be mounted between a heat sink (<NUM>) of the PCB (<NUM>) and the RF connector (<NUM>) to thermally decouple the RF connector (<NUM>) from the heat sink (<NUM>), wherein the mounting element (<NUM>) comprises at least one alignment interface (<NUM>) for aligning the RF connector (<NUM>) with respect to the heat sink (<NUM>);
wherein the mounting element (<NUM>) comprises a thermally insulating material;
characterized in that the at least one alignment interface (<NUM>) comprises several fastening portions (<NUM>) for fastening the RF connector (<NUM>) to the mounting element (<NUM>) and the mounting element (<NUM>) to the heat sink (<NUM>), respectively;
wherein each fastening portion (<NUM>) is configured as a fastening hole for receiving a fastening element (<NUM>).