Method for suppressing electromagnetic interference of electronic device and electronic device with suppressed electromagnetic interference by the method

[00002] 1. Field of the Invention

[00003] The present invention relates generally to the elimination of electromagnetic interference (EMI) induced in an electronic device, such as a notebook computer, and in particular to eliminating EMI by forming a grounding path between a main board and a conductive casing.

[00004] 2. The Related Art

[00005] Electromagnetic interference (EMI) is a great concern for designers and manufacturers of electronic devices operating at high frequency and speed. For example, a notebook computer is subject to EMI when not properly protected. Meanwhile, EMI caused by the operation of the notebook computer may also lead to serious interference with other electronic devices, such as medical equipments. Thus, eliminating EMI is a very important issue for notebook computer designers and manufacturers.

[00006] Electronic devices like notebook computers comprise a main board housed in a casing, which is at least partly constituted by a conductive member. To suppress EMI, the notebook computer is provided with a grounding path between the casing and the main board. A conventional way to establish the grounding path between the casing and the main board is to secure a conductive grounding member between the main board and the casing. The conductive grounding member may assume a U- or V-shape having two opposite limbs, a first one of which is soldered to the main board and a second one of which is resilient and is subject to an elastic deformation caused by engaging the casing. Since a great number of electronic parts are soldered to the main board by the surface mounting technique (SMT), conventionally, the grounding member is also mounted to the main board by SMT. SMT requires high positioning precision and small dimension tolerance, which makes the mounting of the grounding member sophisticated and costly.

[00007] Thus, an object of the present invention is to provide a method for simplifying the establishment of grounding path between a main board of an electronic device and a casing of the device whereby electromagnetic interference is effectively suppressed. The present invention also provides an electronic device with reduced electromagnetic interference by means of the method of the present invention.

[00008] To achieve the above object, in accordance with the present invention, there is provided a method for suppressing electromagnetic interference in an electrical device, such as a notebook computer, comprising a main board housed in a casing that is at least partly constituted by a conductive member. The method comprises forming a grounding path between the main board and the casing by arranging a resilient grounding tab, made of a conductive material, between the main board and the casing. The grounding tab has a U- or V-shape including first and second limbs. The first limb is positioned on the main board with a free end of the second limb engaging the casing and maintaining secured engagement with the casing by means of elastic deformation thereof. The first limb has legs perpendicularly extending therefrom for inserting into through holes defined in the main board. The method also comprises a step of soldering the legs to the main board by through-hole techniques to fixedly mount the grounding tab to the main board. A secured grounding path is thus established between the main board and the casing for suppressing electromagnetic interference of the electronic device.

[00015] With reference to the drawings and in particular to FIGS. 2, 2A and 3, an electronic device, such as a notebook computer as shown in the drawings, generally designated with reference numeral 10, comprises a main board 12 on which electronic parts (not shown), such as integrated circuits and transistors, are mounted. The main board 12 is housed in a casing 14, which is at least partly constituted by a conductive material, such as metal alloy, or which comprises a conductive member. To establish a grounding path between the casing 14 and the main board 12, a number of grounding tabs 16, made of a conductive material, are secured between the casing 14 and the main board 12 and engage the casing 14 or the conductive member of the casing 14.

[00016] Also referring to FIGS. 1 and 4, the grounding tab 16 is made in the form of a U- or V-shaped, having opposite first and second limbs 18, 20 connected together by a resilient connection 22. The first limb 18 of the grounding tab 16 is mounted to the main board 12 by soldering with the second limb 20 resiliently supported by the connection 22 above and spaced from the main board 12. The second limb 20 is sized to have a free end 26 thereof engaging the casing 14 and the connection 22 is subject to an elastic deformation as indicated by the phantom lines of FIG. 4. The elastic deformation of the connection 22 makes the engagement between the free end 26 of the second limb 20 with the casing sound and secured.

[00017] The first limb 18 forms two legs 24 extending from and substantially perpendicular to the first limb 18. The perpendicular extension of the legs 24 from the first limb 18 allows the legs 24 to be inserted into through holes 28 defined in the main board 12 while the first limb 18 is resting on the main board 12. The extension of the legs 24 through the holes 28 fixedly secures the grounding tab 16 in position, which allows for efficient soldering of the grounding tab 16 to the main board 12 by the through-hole techniques. As can be seen from FIG. 4, the first limb 18 is placed flatly on the main board 12. The second limb 20 faces the first limb 18 and is biased against the top of the casing 14 to cause the elastic deformation of the connection 22.

[00018] Thus, the present invention provides a method for suppressing EMI of an electronic device by establishing a grounding path between a main board and a casing of the electronic device. The method comprises the steps of (1) defining holes in the main board of the electronic device, (2) providing a grounding tab having first limb positionable on the main board and a second limb resiliently supported above and spaced from the main board for engaging the casing of the electronic device, the first limb forming legs perpendicular to the first limb, (3) inserting the legs through the holes of the main board and (4) soldering the legs to the main board by means of the through-hole techniques. The method may further comprise a step of inserting legs of an additional grounding tab into corresponding holes defined in the main board before the step of soldering the legs to the main board for mounting more grounding tabs between the main board and the casing.

[00019] The best mode for carrying out the present invention has been described as an illustration of the present invention. It is apparent that modifications and changes may be made without departing from the scope of the present invention which is intended to be defined by the appended claims.