JP2007329322A - Shielding case fitting structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the shielding case fitting structure which does not necessitate exclusive member and mounting space for positioning upon effecting the positioning of the shielding case to a printed circuit board, and which is capable of achieving the regulation of a fitting position while securing electric conduction between a ground pattern on the printed circuit board and the fitting position. <P>SOLUTION: When the printed circuit board 1 is covered by the shielding case 4 in the printed circuit board 1 with a circuit constituting component 3 mounted thereon; two points of corners which are not having the same side of inner wall of the shielding case in common are arranged, so that the grounding terminals of an electronic component having the grounding terminals comprised in the circuit constituting component 3 are abutted against the inner walls of the shielding case 4, while the abutted parts of the shielding case 4 are soldered to the soldering lands of the grounding terminals for the electronic component formed on the grounding pattern of the printed circuit board 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an attachment structure of a shield case attached to a printed circuit board used in an electronic apparatus such as a digital camera.

  In recent years, electronic devices have been reduced in size and functionality, and electronic components mounted on the devices are required to be small and compatible with high-density mounting. In addition, the generation of electromagnetic noise tends to increase due to the increase in the speed of circuit signals in electronic devices, and measures for shielding printed circuit boards are becoming essential.

  As a countermeasure for shielding a printed circuit board, a method of electromagnetically shielding the outside from the outside by covering an electronic component mounted on the printed circuit board with a shield case is common.

  Below, the attachment method of the shield case to the conventional printed circuit board is demonstrated using FIG.5 and FIG.6. In the figure, (a) shows an exploded perspective view, and (b) shows a perspective view seen from above.

  The shield case mounting structure shown in FIG. 5 includes a printed circuit board 50 on which various chip elements 51 constituting a circuit are mounted, and a metal shield case 52 (hereinafter referred to as a shield case) made of a hollow box having an open bottom. And two metal balls 53 disposed on the component mounting surface of the printed circuit board 50.

  The two metal balls 53 are arranged on the diagonal line in the rectangular printed circuit board 50 and inside the corners of the case corresponding positions indicated by the broken lines. That is, when the shield case 52 is put on the printed circuit board 50, the two metal balls 53 are in a positional relationship such that they are just fitted inside the corners of the shield case 52 as shown in FIG.

  The printed circuit board 50 is provided with a wiring pattern (not shown). After applying cream solder to a predetermined electrode pad, various chip elements 51 are mounted, and heat treatment is performed by means such as reflow. Solder mounting is performed. At this time, the metal ball 53 is also mounted together with the chip element 51. That is, an electrode pad for mounting the metal ball 53 is also provided in advance by a wiring pattern formation process (for example, photoetching).

  By connecting the electrode pads to the ground pattern, when the shield case 52 is covered, the metal ball 53 is placed in contact with the inner surface of the side wall 52a of the shield case 52 so that the shield case 52 is covered. Thereafter, the heat treatment is performed again so that the solder around the metal ball 53 is joined to the side wall 52a.

  As a result, the shield case 52 is fixed while being electrically connected to the ground pattern of the printed circuit board 50 via the metal balls 53, and an electromagnetic wave shielding effect can be secured.

  Next, the shield case attachment method shown in FIG. 6 is configured to use a 0Ω chip resistor 54 instead of the metal ball 53.

  By using the 0Ω chip resistor 54, it can be handled in the same manner as the mounting of the chip element 51 by an automatic machine (mounter or the like), and an automatic machine that is not suitable for handling the metal ball 53 having a characteristic shape of a spherical shape. It can be an effective substitute means in some cases. The 0Ω chip resistor 54 is disposed at the same position as the metal ball 53 described above.

  The 0Ω chip resistor 54 has solder plating applied to electrode terminals provided at both ends, and the printed circuit board 50 and the shield case 52 are fixed by soldering. When the shield case 52 is attached to the printed circuit board 50, In addition, the shield case 52 is electrically connected to the ground pattern in the printed circuit board 50 through the 0Ω chip resistor 54, and the electromagnetic wave shielding effect can be ensured.

Thus, by mounting the 0Ω chip resistor 54 together with the chip element 51 on the printed circuit board 50 at a predetermined position, the 0Ω chip resistor 54 functions as a guide when the shield case 52 having the side wall portion 52a is covered. The mounting position of the shield case 52 is regulated to prevent the occurrence of fixed displacement.
JP 2005-235806 JP

  However, the conventional shield case mounting structure described above has the following problems.

  That is, in either case of FIG. 5 or FIG. 6, in order to position the shield case 52, a positioning member (metal ball 53, 0Ω chip resistor 54) is required.

  For this reason, the number of components is increased and a mounting space for mounting components is required, which causes problems such as an increase in component costs and an increase in the size of the printed circuit board.

  Furthermore, when the chip resistor is used as a positioning member, the component height of the chip resistor itself is low, and the electrode surface is covered with solder after mounting the component, and the abutting surface for positioning is the two sides of the side surface. However, since it can only be used, there is a problem that it is not suitable as a positioning member.

  The present invention has been made to solve the above-described conventional problems, and does not require a dedicated member and mounting space for positioning when positioning the shield case with respect to the printed circuit board. It is an object of the present invention to provide a shield case mounting structure capable of regulating the mounting position while ensuring electrical continuity.

  A shield case mounting structure as one aspect of the present invention includes a printed circuit board on which an electronic component having a ground terminal included in a circuit component is mounted, and a shield case mounted on the printed circuit board so as to cover the electronic component. In the mounting structure, the shield case is positioned on the printed circuit board by bringing a ground terminal of the electronic component into contact with an inner wall of the shield case.

  The shield case mounting structure according to another aspect of the present invention is characterized in that a chip capacitor is used for the electronic component.

  According to the present invention, it is possible to provide a shield case mounting structure that does not require a dedicated member for positioning and a mounting space, and that can regulate the mounting position while ensuring electrical continuity with a ground pattern on a printed circuit board. This makes it possible to reduce component costs and downsize the printed circuit board.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a first embodiment according to the present invention.

  FIG. 1A is an exploded perspective view, and FIG. 1B is a perspective view seen from above. In the figure, 1 is a printed circuit board, and the printed circuit board 1 has a circuit for constituting a circuit. A chip capacitor 2 as one component and various other electronic components 3 are mounted. A shield case 4 is attached to the printed circuit board 1 so as to cover the chip capacitor 2 and the electronic component 3.

  The chip capacitor 2 has a ground electrode terminal 2a and a positive electrode terminal 2b. The mounting land 1a formed on the ground pattern of the printed circuit board 1 and the printed circuit board 1 are not shown. It is mounted on a mounting land 1b formed on the circuit pattern shown in the figure, and is electrically connected.

  The chip capacitor 2 is arranged so that the ground electrode terminal 2a faces the inside of the corner of the shield case corresponding position indicated by a broken line. That is, when the shield case 4 is put on the printed circuit board 1, the positional relationship is such that the surfaces of the ground electrode terminals 2 a of the two chip capacitors 2 fit inside the corners of the shield case 4 as shown in FIG. Thus, the shielding case 4 is positioned with respect to the printed circuit board 1 by the two chip capacitors 2.

  FIG. 1C is a detailed view showing the positional relationship between the shield case 4 and the chip capacitor 2 in a state where the shield case 4 is fitted to the printed circuit board 1.

  Arm portions 4a and 4b are formed on the side surface of the shield case 4. The arm portion 4a is in contact with the surface of the ground electrode terminal 2a and the mounting land 1a, and the arm portion 4b is in contact with the side surface of the chip capacitor. . Further, a substantially U-shaped escape portion 4c is formed on the side surface of the shield case having the arm portion 4b so as not to contact the positive electrode terminal 2b and the mounting land 1b. Prevents short circuit.

  The arm portion 4a of the shield case 4 is solder-connected to the mounting land 1a, thereby being fixed to the printed circuit board 1 while being electrically connected to the ground pattern of the printed circuit board 1, thereby shielding the electromagnetic wave. Can be secured.

  Next, Embodiment 2 according to the present invention will be described with reference to FIG.

  In addition, the same code | symbol is attached | subjected about the functional part similar to what was shown in the above-mentioned Example 1. FIG.

  2A is an exploded perspective view, and FIG. 2B is a perspective view seen from above. In the figure, reference numeral 1 denotes a printed circuit board, and the printed circuit board includes a circuit for constituting a circuit. A chip capacitor 2 as a component and various other electronic components 3 are mounted. A shield case 5 is attached to the printed circuit board 1 so as to cover the chip capacitor 2 and the electronic component 3.

  The chip capacitor 2 has a ground electrode terminal 2a and a positive electrode terminal 2b. The mounting land 1a formed on the ground pattern of the printed circuit board 1 and the printed circuit board 1 are not shown. It is mounted on a mounting land 1b formed on the circuit pattern shown in the figure, and is electrically connected.

  The chip capacitor 2 is arranged so that the surface of the ground electrode terminal 2a faces the side surface of the shield case 5 on the inner side of the four sides of the shield case corresponding position indicated by the broken line. That is, when the printed circuit board 1 is covered with the shield case 5, the ground electrode terminals 2 a of the four chip capacitors 2 are positioned so as to fit inside the four sides of the shield case 5 as shown in FIG. The shield case 5 is positioned with respect to the printed circuit board 1 by the four chip capacitors 2.

  FIG. 4C is a detailed view showing the positional relationship between the shield case 5 and the chip capacitor 2 in a state where the shield case 5 is fitted to the printed circuit board 1.

  An arm portion 5a is formed on the side surface of the shield case 5, and the arm portion 5a is in contact with the surface of the ground electrode terminal 2a and the mounting land 1a.

  The arm portion 5a of the shield case 5 is solder-connected to the mounting land 1a, so that it is fixed to the printed circuit board 1 while being connected to the ground pattern of the printed circuit board 1, thereby shielding the electromagnetic wave. Can be secured.

  By disposing the chip capacitor 2 in this manner, the substantially U-shaped escape portion of the shield case described in the first embodiment is not necessary, and thus the shield case 5 can have a more hermetically sealed structure. Can be increased.

  The direction of the chip capacitor 2 is rotated by 90 degrees with respect to the second embodiment, and a substantially U-shaped relief portion is provided on the side surface of the shield case in the same manner as the first embodiment, thereby contacting the side surface of the shield case 2. There is no problem even if it arranges so that it may make it.

  Next, a third embodiment according to the present invention will be described with reference to FIG.

  FIG. 3 is a detailed view showing the positional relationship between the shield case 6 and the chip capacitor 2 in a state where the shield case 6 is fitted to the printed circuit board 1, and the functional parts similar to those shown in the first and second embodiments. Are denoted by the same reference numerals, and the description thereof is omitted.

  The attachment structure of the shield case shown in the third embodiment is an extension of the arm shape of the shield case that contacts the chip capacitor shown in the first and second embodiments.

  In the shield case 6, the arm portion 6 a, which is a contact portion with the ground electrode terminal 2 a of the chip capacitor 2, has a shape having a spring property as shown in the figure, whereby the shield case 6 is attached to the printed circuit board 1. By energizing the chip capacitor 2, the backlash between the printed circuit board 1 and the shield case 6 is eliminated and accurate positioning is possible. Similarly to the first and second embodiments, the arm portion 6a, the ground electrode terminal 2a, and the mounting land 1a are connected by soldering, so that the printed circuit board 1 can be electrically connected to the ground pattern. Therefore, the electromagnetic wave shielding effect can be ensured.

  In the first and second embodiments described above, there is a possibility that the printed circuit board and the shield case may be loose due to variations in the component accuracy of the shield case and the chip capacitor and the mounting accuracy of the chip capacitor. For this reason, there are concerns about assembly problems such as misalignment and floating of the shield case when soldering the shield case to the substrate (soldering the arm portion). However, as in this embodiment, the arm portion is provided with a spring property. This can solve this problem.

  Next, a fourth embodiment according to the present invention will be described with reference to FIG.

  In addition, the same code | symbol is attached | subjected about the functional part similar to what was shown in the above-mentioned Examples 1-3.

  4A shows an exploded perspective view, FIG. 4B shows a perspective view seen from above, and FIG. 4C shows the shield case 5 and the chip capacitor 2 with the shield case 5 fitted to the printed circuit board 1. FIG.

  In the figure, reference numeral 1 denotes a printed circuit board on which a chip capacitor 2 which is one part for constituting a circuit and various other electronic components 3 are mounted. A shield case 7 is attached to the printed circuit board 1 so as to cover the chip capacitor 2 and the electronic component 3.

  The chip capacitor 2 has a ground electrode terminal 2a and a positive electrode terminal 2b, respectively. A mounting land 1a formed on a ground pattern (not shown) of the printed circuit board 1 and an unillustrated data on the printed circuit board 1 are shown. It is mounted on a mounting land 1b formed on the circuit pattern and is electrically connected.

  The side surface of the shield case 7 has a substantially U-shaped relief portion 7a straddling the chip capacitor 2, and the chip capacitor 2 is located on the four sides of the shield case corresponding position indicated by the broken line and When the printed board 1 is covered, it is arranged at a position where the escape portion 7a straddles as shown in FIG.

  The shield case 7 is positioned with respect to the printed circuit board 1 by the four chip capacitors 2 and the relief portions 7 a of the shield case 7.

  In addition, the peripheral portion of the escape portion 7a of the shield case 7 is connected to the ground electrode terminal 2a of the chip capacitor 2 and the mounting land 1a by soldering, so that the printed circuit board 1 can be electrically connected to the ground pattern. Fixing to the substrate 1 is performed, and an electromagnetic wave shielding effect can be secured.

  As described above, the shield case mounting structure enables reliable soldering work because the ground electrode terminal is exposed when the shield case is soldered to the ground electrode terminal and the mounting land of the chip capacitor. Become.

  In Example 4, positioning of the shield case is performed by fitting four chip capacitors into the shape of the side relief portions on the four sides of the shield case. However, positioning can be performed at least by two adjacent sides of the shield case. However, it is not necessarily limited to this embodiment.

  In addition, since the shield case is directly soldered to the chip capacitor mounting land formed on the ground pattern of the printed circuit board, there is no capacity between the printed circuit board and the shield case. There is no problem in using it as a positioning member.

  In the present invention, the positioning member of the shield case may be an electronic component having a ground terminal included in the circuit component, and is not limited to the above-described embodiment, and the function of the configuration of the embodiment is provided. Of course, as long as the configuration can be achieved, various modifications and applications are possible without departing from the spirit of the invention.

It is a figure which shows Example 1 of the shield case attachment structure which concerns on this invention. It is a figure which shows Example 2 of the shield case attachment structure which concerns on this invention. It is a figure which shows Example 3 of the shield case attachment structure which concerns on this invention. It is a figure which shows Example 4 of the shield case attachment structure which concerns on this invention. It is a figure which shows the conventional shield case attachment structure. It is a figure which shows the conventional shield case attachment structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printed circuit board 1a, 1b Chip capacitor mounting land 2 Chip capacitor 2a, 2b Chip capacitor electrode 3 Circuit component 4, 5, 6, 7 Shield case 4a, 4b, 5a, 6a Arm part 4c, 7a Escape part

Claims (8)

  In a mounting structure of a printed board on which an electronic component having a ground terminal included in a circuit component is mounted, and a shield case attached to the printed board so as to cover the electronic component, the ground terminal of the electronic component is shielded from the shield A shield case mounting structure, wherein the shield case is positioned on the printed circuit board by being brought into contact with an inner wall of the case.   The shield case mounting structure according to claim 1, wherein the electronic component is a chip capacitor.   2. The shield case mounting structure according to claim 1, wherein the electronic parts are arranged at two corners that do not share the same side of the shield case.   2. The shield case mounting structure according to claim 1, wherein the electronic parts are arranged on four sides of the inner wall of the shield case.   The contact portion of the shield case with the electronic component is soldered to a soldering land for mounting the electronic component formed on a ground pattern of the printed circuit board. Shield case mounting structure.   The shield case mounting structure according to claim 1, wherein a contact portion of the shield case with the electronic component has a spring property and biases the electronic component.   In a mounting structure of a printed board on which an electronic component having a ground terminal included in a circuit component is mounted and a shield case attached to the printed board so as to cover the electronic component, the shield cases are at least adjacent to each other. A shield case mounting structure characterized by having a U-shape straddling the outer shape of the electronic component on the side of the shield case that is equal to or greater than the side.   8. The shield case mounting structure according to claim 7, wherein a side surface of the shield case is soldered to a soldering land for mounting the electronic component formed on a ground pattern of the printed circuit board.

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