Patent Description:
Electronic circuit boards are one of the most important building blocks for many electronic devices, and are known in a large variety. Usually, electronic circuitry of such circuit boards is provided on a rigid carrier member that is used for mounting the circuit board to a housing of the electronic device. Moreover, flexible circuit boards are known, wherein the electronic circuitry is provided on a flexible carrier member.

The rigid carrier member is usually mounted to the housing of the electronic device via conventional mounting techniques, for example via screws, bolts, etc..

In order to ground the electronic circuit board, additional components such as conducting springs may have to be provided, which are used to electrically connect the circuit board with a housing or a ground plane of the electronic device.

Accordingly, the mounting of the electronic circuit board may be rather time-consuming, as multiple components have to be assembled or rather connected to each other.

<CIT> discloses a circuit board according to the preamble of claim <NUM>.

<CIT> discloses a rigid-flexible circuit board comprising a flexible circuit board and a rigid circuit board. The rigid circuit board is attached to the flexible circuit board by means of an adhesive layer.

Thus, the object of the present invention is to provide a circuit board as well as a method for assembling an electronic device that allow for a simpler mounting of the circuit board in the electronic device.

According to the invention, the problem is solved by a circuit board for a handheld radio according to claim <NUM>.

The circuit board according to the invention is mountable directly to a housing of an electronic device (particularly to a handheld radio) by means of the elastic mounting member in a particularly simple fashion. For example, the circuit board may be glued to the housing via the elastic mounting member.

As the mounting member is elastic, manufacturing tolerances of the electronic circuit board and/or of the housing of the electronic device are compensated at least partially by the elastic mounting member.

Moreover, the flexible connecting portion ensures that the circuit board can be connected to the other electronic components (e.g. of the handheld radio) in an easy manner, as the flexible connecting portion can simply be bent such that it contacts the corresponding electronic component.

Additionally, the flexible connecting portion also compensates for manufacturing tolerances of the circuit board, and/or for manufacturing tolerances of the handheld radio to which the circuit board is to be mounted.

Particularly, the connecting portion provides an electrical low-resistance contact to the at least one other electronic component (e.g. of the handheld radio).

According to an aspect of the invention, the elastic mounting member comprises an adhesive film. Particularly, the adhesive film is arranged on a bottom side of the elastic mounting member, wherein the bottom side faces away from the circuit board. Thus, the circuit board may be glued into the electronic device, particularly to the housing of the electronic device by means of the adhesive film. Thus, the mounting portion can be mounted to the housing in a particularly simple fashion.

Additionally, an adhesive film may be provided between the top side of the elastic mounting member and the bottom side of the circuit board. In other words, the elastic mounting member may be glued to the circuit board.

According to another aspect of the invention, the adhesive film is covered with a removable cover strip. More precisely, the removable cover strip may be arranged on the bottom side of the elastic mounting member, which faces away from the mounting portion. This way, handling of the circuit board during the manufacturing process is facilitated, as an unwanted gluing of the circuit board to other objects is prevented by the cover strip. Moreover, the cover strip effectively prevents dust or other small objects from sticking to the adhesive film before mounting of the circuit board.

In order to mount the circuit board, the cover strip is simply removed from the adhesive film, and the circuit board is glued to the housing of the electronic component by means of the adhesive film.

Particularly, the removable cover strip comprises several cover strip portions, wherein the several cover strip portions are removable individually. In other words, the removable cover strip is divided into at least two different cover strip portions, wherein each portion can be removed from the adhesive film individually.

For example, neighboring cover strip portions may be separated from each other by means of a perforation in the cover strip that facilitate individual removal of the cover strip portions.

In a further embodiment of the invention, the elastic mounting member comprises a rubber foam pad. As rubber foam is rather inexpensive, the circuit board can be manufactured in a particularly cost effective manner.

Particularly, at least a bottom side of the rubber foam pad may be covered with the adhesive film described above, wherein the bottom side of the rubber foam pad faces away from the mounting portion. Thus, the bottom side of the rubber foam pad faces away from the circuit board. For instance, the rubber foam pad is integrally connected via its top side to the circuit board, particularly the mounting portion. Put differently, the rubber foam is molded to the circuit board, for instance injection-molded.

Additionally, a top side of the rubber foam pad may be covered with an adhesive film. Accordingly, the rubber foam pad may be glued to the bottom side of the circuit board. Hence, the rubber foam pad may be manufactured separately and connected with the circuit board.

Of course, the elastic mounting member may be fabricated from any other suitable elastic material other than rubber foam.

According to another aspect of the invention, the at least one grounding portion is established as a lug being immediately connected to the circuit board. The at least one lug protrudes from the mounting portion either horizontally or at an angle with respect to a plane defined by the mounting portion.

In general, the at least one lug is electrically conductive, and is electrically connected to a ground plane of the electronic circuit. Thus, if the lug contacts a housing of an electronic device, the ground plane of the circuit board is electrically connected to the housing, thereby enhancing electromagnetic screening of the circuit board.

Particularly, the mounting portion may comprise several grounding portions, wherein each of the grounding portions may be established as a lug. Each of the grounding portions may be brought into electrical contact with the housing of the electronic device. This way, the electromagnetic screening of the circuit board is enhanced even further.

In a further embodiment of the invention, the at least one grounding portion is bendable with respect to the mounting portion. Thus, the grounding portion can be bent into a suitable positon for contacting the housing of the electronic device in a particularly simple fashion. In other words, the grounding contacts of the circuit board, i.e. the at least one grounding portion, can be adapted to the particular form of the housing to which the circuit board is mounted. Moreover, manufacturing tolerances of the circuit board and/or of the housing of the electronic device can be compensated by bending the at least one grounding portion to the needed position.

The at least one grounding portion may comprise a conductive metal, particularly gold. Particularly, the grounding portion may be covered with the conductive metal, for example with gold. Due to its low reactivity and its relative softness compared to other metals, gold is particularly suitable as a cover material for electrical contacts.

Particularly, the mounting portion has an essentially rectangular shape. Therein and in the following, the term "essentially rectangular" is understood to denote a shape that may have small deviations from an actual rectangle. For example, such deviations include one or more of the following: rounded corners, protrusions, and/or recesses.

However, it is to be understood that the mounting portion may have any other suitable shape.

According to an aspect of the invention, the mounting portion comprises at least one lateral recess or lug. The lateral recess or lug allows for a secure positioning during the mounting of the circuit board. For example, the housing of the electronic device to which the circuit board is mounted may comprise a lug or recess that corresponds to the lateral recess or lug of the circuit board, respectively. In order to securely position the circuit board, the lug of the housing is simply inserted into the recess of the circuit board, or the lug of the circuit board is inserted into the recess of the housing.

Particularly, the mounting portion may comprise two lateral recesses or two lateral lugs that are positioned at opposite lateral sides of the mounting portion. The two recesses or lugs of the mounting portion cooperate with two corresponding lugs or recesses of the housing of the electronic device. This way, the circuit board can be positioned in a particularly stable manner.

The flexible connecting portion may comprise a printed circuit board. Accordingly, a flexible electric connection is provided by means of the printed circuit board, such that manufacturing tolerances of the electronic device and/or manufacturing tolerances of the circuit board can be compensated by means of the flexible connecting portion in three dimensions.

According to another aspect of the invention, the connecting portion comprises a plug connector, particularly wherein the plug connector is arranged at an end of the connecting portion being opposite to the mounting portion. Accordingly, the full length of the connecting portion is available for compensating tolerances and for bridging the distance between the designated mounting position of the electronic circuit board and the electronic component to which the circuit board is to be connected.

According to the invention, the problem further is solved by a control unit, particularly for a handheld radio, comprising a circuit board described above, wherein the control unit is established as a switch.

The control unit may comprise at least one snap dome that is located on the circuit board, particularly at a side of the circuit board facing away from the elastic mounting member. The at least one snap dome may be used for switching operation.

Generally, the electronic circuit is configured to control at least one functionality of the electronic device.

Particularly, the electronic circuit is configured to switch between at least two different operational modes of the electronic device, such as "on" and "off", or between different channels of the handheld radio.

Alternatively or additionally, the electronic circuit may be configured to control illumination means of the electronic device, such as LEDs. For example, the electronic circuit may control the illumination means to show a certain light signal.

Alternatively or additionally, the electronic circuit may be configured to control a display of the electronic device.

Regarding the advantages and further properties of the control unit, reference is made to the explanations given above with respect to the circuit board, which also hold for the control unit and vice versa.

According to the invention, the problem further is solved by an electronic device, particularly a handheld radio, comprising a housing, a circuit board described above, and/or a control unit described above, wherein the grounding portion of the circuit board immediately abuts the housing.

Regarding the advantages and further properties of the electronic device, reference is made to the explanations given above with respect to the circuit board, which also hold for the electronic device and vice versa.

According to the invention, the problem further is solved by a method of assembling an electronic device, wherein the method comprises the steps of:.

Particularly, the circuit board or rather the mounting portion of the circuit board is glued into the housing by means of the elastic mounting member, or more precisely by means of the adhesive layer on the rubber foam pad described above.

Manufacturing tolerances of the electronic device and of the circuit board are compensated by the grounding portions in a simple manner, as the grounding portions can be bent in the needed manner such that they contact the housing irrespective of certain manufacturing tolerances.

Regarding the further advantages and further properties of the method, reference is made to the explanations given above with respect to the circuit board, which also hold for the method and vice versa.

Generally, the at least one grounding portion is bent such that it encompasses the elastic mounting member, thereby providing a sandwiched structure of the circuit board. In the sandwiched structure, the rigid mounting portion is associated with an upper layer, the elastic mounting member is associated with a medium layer, and the at least one grounding portion is associated with a lower layer, wherein the at least one grounding portion extends from the rigid mounting portion in the unfolded or rather non-bent state.

<FIG> shows a portion of an electronic device <NUM> comprising a metal housing <NUM> and a circuit board <NUM> that is mounted to the housing <NUM>.

The electronic device <NUM> may be established as a handheld radio.

The circuit board <NUM> may be established as a switch for the electronic device <NUM>, particularly as a switch for the handheld radio. This embodiment is, without restriction of generality, described below.

However, it is to be understood that the circuit board <NUM> may be configured to control any functionality of the electronic device <NUM>. For example, the circuit board <NUM> may be configured to control illumination means of the electronic device <NUM>, such as LEDs. For example, the circuit board <NUM> may control the illumination means to show a certain light signal. As a further example, the circuit board <NUM> may be configured to control a display of the electronic device <NUM>.

The housing <NUM> comprises a depression <NUM> for mounting the circuit board <NUM>. The depression <NUM> may have a stepped shape, such that an outer area of the depression <NUM> has a first depth being smaller than a second depth of an inner area of the depression <NUM>.

The circuit board <NUM> is mounted to the housing <NUM> in the inner area of the depression <NUM>.

The housing <NUM> comprises two lugs <NUM> that are provided at opposite sides of the depression <NUM>. The functionality of the lugs <NUM> will be described in more detail below.

The housing <NUM> further comprises threaded holes <NUM>, wherein a cover portion of the housing <NUM> may be screwed onto the housing <NUM> via the threaded holes <NUM>. Particularly, a thickness of the cover portion may be equal to the depth of the outer area of the depression <NUM>, such that the housing <NUM> has a level surface after the cover portion is mounted.

<FIG> shows a top side of the circuit board <NUM> in more detail. The circuit board <NUM> comprises a rigid mounting portion <NUM> and a flexible connecting portion <NUM> that is connected to the mounting portion <NUM>.

The mounting portion <NUM> has an essentially rectangular shape, wherein the mounting portion <NUM> is complementary to the inner area of the depression <NUM> of the housing <NUM>, or smaller than the inner area of the depression <NUM> of the housing <NUM>.

However, it is to be understood that the mounting portion <NUM> may also have any suitable shape other than the essentially rectangular shape.

The mounting portion <NUM> comprises at least one electronic circuit <NUM> on its top side. For example, the electronic circuit <NUM> may comprise a printed electronic circuit that is printed on the top side of the mounting portion <NUM>, and/or other electronic components, such as FPGAs, ASICs, etc..

In general, the electronic circuit <NUM> is configured to control at least one functionality of the electronic device <NUM>. Particularly, the electronic circuit <NUM> is configured to switch between at least two different operational modes of the electronic device <NUM>, such as "on" and "off", or between different channels of the handheld radio.

The mounting portion <NUM> further comprises several grounding portions <NUM> that are each electrically connected with a ground plane of the electronic circuit <NUM>.

The grounding portions <NUM> are established as bendable lugs that extend outwardly from the mounting portion <NUM>, particularly within one plane in the unfolded or rather non-bent state, which is shown in <FIG>.

The lugs may each consist out of a conductive metal, or may be covered with a conductive metal at least on their top side. Particularly, the lugs are each covered with a gold layer at least on their top side.

In general, the grounding portions <NUM> immediately abut the housing <NUM> in the mounted state of the electronic device <NUM>, which is shown in <FIG>. Thus, the grounding portions <NUM> electrically connect the ground plane of the at least one electronic circuit <NUM> with the housing <NUM>, thereby enhancing the electromagnetic screening of the circuit board <NUM>.

On the opposite side, the mounting portion <NUM> comprises one or several metallic snap domes <NUM> that are arranged at least over portions of the electronic circuit <NUM>, which are contacted by the cover portion connected with the threaded holes <NUM>, thereby establishing the switch as mentioned above.

Between the electronic circuit <NUM> and each of the snap domes <NUM>, a switching mat may be provided, respectively. When the snap domes <NUM> are actuated, an electric circuit is closed by means of the switching mat, and a switching operation may be triggered.

If the circuit board <NUM> is mounted to the housing <NUM>, and the cover portion of the housing <NUM> is attached to the housing <NUM>, the snap domes <NUM> may abut the cover portion of the housing <NUM>, such that a mechanical and/or electrical connection is established, thereby ensuring a switching operation.

The mounting portion <NUM> further comprises two lateral recesses <NUM>, which are arranged on opposite sides of the mounting portion <NUM>.

The lateral recesses <NUM> are complementary to the lugs <NUM> of the housing <NUM>, such that the circuit board <NUM> or rather the mounting portion <NUM> can be securely positioned in the depression <NUM> during assembly of the electronic device <NUM>.

In other words, the lugs <NUM> and the recesses <NUM> cooperate in order to guide the circuit board <NUM> into the correct position, and to hold the circuit board <NUM> in the correct position during the assembly of the electronic device <NUM>.

The flexible connecting portion <NUM> comprises a plug connector <NUM> and a flexible printed circuit board <NUM> for connecting the circuit board <NUM> with at least one further electronic component of the electronic device <NUM>.

The plug connector <NUM> is arranged at an end of the connecting portion <NUM> that is facing away from the mounting portion <NUM>.

The flexible printed circuit board <NUM> connects the plug connector <NUM> with the at least one electronic circuit <NUM> of the circuit board <NUM>. As the connecting portion <NUM>, particularly the printed circuit board <NUM>, is configured to be flexible, manufacturing tolerances of the electronic device <NUM> and of the circuit board <NUM> can be compensated by means of the flexible connecting portion <NUM> in three dimensions.

Accordingly, a switching operation initiated via the cover portion of the housing is transmitted to the snap dome(s) <NUM>, which interact with the switching mat(s) and the electronic components provided on the circuit board <NUM> such that signals are forwarded to the plug connector <NUM> for controlling the at least one further electronic component of the electronic device <NUM> that is connected with the plug connector <NUM>.

<FIG> shows a bottom side of the circuit board <NUM>. On its bottom side, the mounting portion <NUM> comprises at least one elastic mounting member <NUM> for mounting the circuit board <NUM> to the housing <NUM>, wherein the mounting member <NUM> is not visible in <FIG>, but it is shown in <FIG> and <FIG>.

The at least one elastic mounting member <NUM> is established as a rubber foam pad <NUM> that respectively comprises an adhesive layer on its top side, which is facing the mounting portion <NUM>, and on its bottom side, which faces away from the mounting portion <NUM>.

Accordingly, the rubber foam pad <NUM> is glued to the mounting portion <NUM> by means of the adhesive layer that is arranged on the top side of the rubber foam pad <NUM>.

Moreover, the mounting portion <NUM> can be glued into the depression <NUM> of the housing <NUM> by means of the adhesive layer that is arranged on the bottom side of the rubber foam pad <NUM>.

Before mounting of the circuit board <NUM> to the housing <NUM>, the elastic mounting member <NUM> comprises a removable cover strip <NUM> on its bottom side, wherein the cover strip <NUM> covers the adhesive layer on the bottom side of the rubber foam pad <NUM>.

As is illustrated in <FIG>, the cover strip <NUM> comprises several cover strip portions <NUM>, <NUM>, <NUM>, which are individually removable from the adhesive layer on the bottom side of the rubber foam pad <NUM>, i.e. on the side that is facing away from the mounting portion <NUM>.

It is noted that while the cover strip <NUM> comprises three covers strip portions <NUM>, <NUM>, <NUM> in the exemplary embodiment shown in <FIG>, the cover strip <NUM> may comprise any other number of cover strip portions other than three, for example one, two, or four cover strip portions.

In the exemplary embodiment shown in <FIG>, the cover strip portions <NUM>, <NUM>, <NUM> are arranged side by side along a width-dimension of the mounting portion <NUM>.

The middle cover strip portion <NUM> may be arranged adjacent to the flexible connecting portion <NUM>, while the other two cover strip portions <NUM>, <NUM> are laterally offset to the middle cover strip portion <NUM>.

Neighboring cover strip portions <NUM>, <NUM>, <NUM> may be separated from each other by means of a perforation in the cover strip <NUM> that facilitate individual removal of the cover strip portions <NUM>, <NUM>, <NUM>.

<FIG> shows a top side of the elastic mounting member <NUM>, i.e. the side of the elastic mounting member <NUM> that is facing the mounting portion <NUM>. Hence, the side shown in <FIG> is opposite to the one shown in <FIG>.

The elastic mounting member <NUM> has an overall length I that is either equal to or smaller than the overall length of the mounting portion <NUM>.

Moreover, the elastic mounting member <NUM> has an overall width b that is either equal to or smaller than the overall width of the mounting portion <NUM>.

On its opposing lateral sides, the elastic mounting member <NUM> comprises two semicircular recesses <NUM> having a diameter d, which is either equal to or bigger than a diameter of the recesses <NUM> of the mounting portion <NUM>.

The centers of the semicircular recesses <NUM> are spaced apart by a distance dc, which is equal to the distance between the centers of the lateral recesses <NUM> of the mounting portion <NUM>.

The elastic mounting member <NUM> comprises a further recess <NUM> at a lateral side that is facing the flexible connecting portion <NUM>. The recess <NUM> has a width br that is equal to or bigger than the width of the flexible connecting portion <NUM>.

A center of the recess <NUM> is spaced from the center of the nearer lateral recess <NUM> of the elastic mounting member by a distance dr, such that axial symmetry lines of the recess <NUM> and of the flexible connecting portion <NUM> coincide.

Moreover, the elastic mounting member <NUM> may have cutaways <NUM> at its corners.

Accordingly, the elastic mounting member <NUM> covers a bottom surface of the mounting portion <NUM> only partially.

However, it is also conceivable that the elastic mounting member <NUM> covers the bottom surface of the mounting portion <NUM> completely.

<FIG> shows a flow chart of a method of assembling the electronic device <NUM> described above.

The housing <NUM> and the circuit board <NUM> described above are provided (step S1).

At least on of the cover strip portions <NUM>, <NUM>, <NUM> is removed (step S2). In general, only the cover strip portions <NUM>, <NUM>, <NUM> that need to be removed for the particular mounting configuration of the electronic device <NUM> are actually removed. For example, if the flexible connecting portion <NUM> is to be (partially) glued to the bottom side of the mounting portion <NUM>, then all cover strip portions <NUM>, <NUM>, <NUM> may be removed.

If, however, the flexible connecting portion shall not be glued to the bottom side of the mounting portion <NUM>, then only the lateral cover strip portions <NUM>, <NUM> may be removed, while the center cover strip portion <NUM> may remain on the rubber foam pad <NUM>.

Accordingly, the flexible connecting portion <NUM> may be glued to the bottom side of the mounting portion <NUM>, and thus may be partially fixed to the circuit board <NUM>.

The grounding portions <NUM> are bent towards the bottom side of the mounting portion <NUM> (step S3).

If necessary, the grounding portions <NUM> may be glued to the bottom side of the rubber foam pad <NUM> by means of the adhesive layer on the rubber foam pad <NUM>. In this case, the grounding portions <NUM> are bent until they contact the adhesive layer on the bottom side of the rubber foam pad <NUM>.

The flexible connecting portion <NUM>, or more precisely the plug connector <NUM>, is connected to at least one further electronic component of the electronic device <NUM> (step S4).

It is noted that step S4 may, in principle, also be performed before step S2 and/or before step S3.

The mounting portion <NUM> is glued into the depression <NUM> by means of the adhesive layer of the rubber foam pad <NUM>, such that the grounding portions <NUM> immediately abut the housing <NUM> (step S5).

Therein, the lateral recesses <NUM> in the mounting portion <NUM> and the lateral lugs <NUM> of the housing cooperate to guide the mounting portion <NUM> into the correct position.

Finally, a cover portion of the housing <NUM> may be screwed onto the housing <NUM> via the threaded holes <NUM>, such that the housing <NUM> is closed (step S6), thereby contacting the snap dome(s) <NUM> for establishing the switch.

Summarizing, the circuit board <NUM> described above can be mounted to the housing <NUM> of the electronic device <NUM> by means of the elastic mounting member <NUM> in a particularly simple fashion. More precisely, the circuit board <NUM> or rather the mounting portion <NUM> is glued to the housing via the adhesive layer of the rubber foam pad <NUM>.

As the rubber foam pad <NUM> is elastic, manufacturing tolerances of the circuit board <NUM> and/or of the housing <NUM> of the electronic device <NUM> are compensated at least partially by the elastic mounting member <NUM>.

Moreover, the flexible connecting portion <NUM> ensures that the circuit board <NUM> can be connected to other electronic components of the electronic device <NUM> in an easy manner, as the flexible connecting portion <NUM> can simply be bent such that it contacts the corresponding electronic component.

The flexible connecting portion <NUM> also compensates for manufacturing tolerances of the circuit board <NUM> and/or for manufacturing tolerances of the housing <NUM> to which the circuit board <NUM> is mounted.

Claim 1:
A circuit board for a handheld radio, comprising a rigid mounting portion (<NUM>), a flexible connecting portion (<NUM>) for electronically connecting the circuit board (<NUM>) to other electronic components, at least one grounding portion (<NUM>) for grounding the circuit board (<NUM>), and at least one electronic circuit (<NUM>), and
wherein the at least one electronic circuit (<NUM>) is provided on a top side of the mounting portion (<NUM>),
characterized in that the mounting portion (<NUM>) comprises an elastic mounting member (<NUM>) on a bottom side of the mounting portion (<NUM>), which is opposite to the top side, wherein the circuit board (<NUM>) is mountable directly to a housing (<NUM>) of an electronic device (<NUM>) by means of the elastic mounting member (<NUM>).