JP4374155B2 - Screw mounting structure of printed wiring board, grounding structure of printed wiring board, and thin plate member - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a screw mounting structure of a printed wiring board for fixing a printed wiring board that can be used in various electronic devices, and a grounding structure of a printed wiring board using the mounting structure.
[0002]
[Prior art]
Conventionally, a printed wiring board is generally fixed to a case by mounting holes provided at each corner. In this case, the diameter of the mounting hole of the printed wiring board is larger than the outer diameter of the screw, that is, the diameter of a virtual cylinder in contact with the top of the screw, and after passing the screw through the mounting hole of the printed wiring board, By tightening the screw with respect to the case, the printed wiring board is sandwiched and fixed between the screw plate and the case.
[0003]
[Problems to be solved by the invention]
However, if the screw is loosened due to vibration or the like, the diameter of the mounting hole is larger than the outer diameter of the screw, so that the printed wiring board is not sufficiently fixed by the screw. In other words, the printed wiring board is rattled by the looseness of the screws by the amount of the mounting holes that are rough.
[0004]
In particular, the printed wiring board pattern (ground pattern) may be grounded by such a screw itself or by a lead wire attached to the screw. Under the circumstances where the printed wiring board is not sufficiently fixed as described above. There is a risk that a good grounding state may not be ensured.
[0005]
The present invention has been made to solve the above-described problems, and an object thereof is to securely fix a printed wiring board when the printed wiring board is fixed with screws.
[0006]
The screw mounting structure for a printed wiring board according to the present invention includes a printed wiring board, screws, and a thin plate member.
A mounting hole and a pattern corresponding to the mounting hole are formed on the printed wiring board. The screw is for passing through a mounting hole formed in the printed wiring board and fixing the printed wiring board to the case. When the thin plate-like member is soldered to the pattern on the printed wiring board, it covers the edge part of the mounting hole of the printed wiring board by the surface tension of the solder by reflow soldering using cream solder. Is positioned. Thereby, when the printed wiring board is fastened and fixed to the case by the screw, the thin plate-like member is engaged with the bottom of the screw, and the displacement of the screw with respect to the printed wiring board is restricted. Making it a part of the end edge means that the thin plate-like member is not in a ring shape covering the entire end edge.
[0007]
In particular, the pattern is formed in accordance with the outer shape of at least both ends in the region on the printed wiring board in which the thin plate-like member is arranged so as to cover a part of the edge of the mounting hole. Thus, when positioning the thin plate member on the printed wiring board using the surface tension of the solder, both end portions of the thin plate member are securely fixed to the printed wiring board. As a result, when positioning due to the surface tension of the solder, wobbling of both ends of the thin plate-like member is suppressed, and the thin plate-like member is reliably arranged at a position covering a part of the edge of the mounting hole. is there. Also, since reflow soldering using cream solder is used for soldering thin plate members, soldering work can be easily performed even when soldering small thin plate members. The positioning to the printed wiring board is ensured. For example, as shown in claim 2, both end portions of the thin plate member may be soldered to the pattern, and an unsoldered intermediate portion of the thin plate member may be engaged with the valley of the screw. As a result, the stability of positioning of the thin plate member to the printed wiring board is ensured, and the intermediate portion of the thin plate member is not fixed with solder, so that elastic deformation of the intermediate portion is sufficiently allowed. By engaging the part with the bottom of the screw, the effect of preventing the loosening of the screw can be obtained more effectively by utilizing the reaction force caused by the elastic deformation of the intermediate part.
[0008]
The technical idea here focuses on the miniaturization of the thin plate member accompanying the miniaturization of the electronic device as described above, and is positioned by the surface tension of the melted solder, that is, the self-alignment effect can be obtained. Thus, a thin plate member is formed. For example, as shown in claim 3 , it is conceivable to use a thin plate member having a substantially square shape. Specifically, small and thin metal members each having a length and width of several millimeters are used so that the self-alignment effect can be obtained. Note that the term “substantially” is used here because it does not have to be a strict square shape.
[0009]
If such a thin plate member is used, positioning by the self-alignment effect is possible, and the mounting accuracy for the pattern formed corresponding to the mounting hole can be improved. Therefore, if this pattern is formed accurately with respect to the mounting hole, the thin plate-like member is mounted with high precision in the mounting hole.
[0010]
Thereby, the edge part of a thin plate-shaped member can be engaged with the valley bottom of the screw which penetrates an attachment hole, and the displacement of a screw is controlled. Therefore, even if the screw is loosened by vibration, the printed wiring board is not rattled. Further, since the thin plate-like member is soldered to the printed wiring board surface, it is positioned slightly above the mounting surface of the printed wiring board. Therefore, when the screw is tightened, it is elastically deformed toward the printed wiring board centering on the engaging portion, and the reaction force exerts a force in the direction of pulling out the screw. Accordingly, there is a high possibility that the screw can be prevented from loosening due to vibration.
[0011]
Note that the use of the substantially square-shaped thin plate member is an example. For example, as shown in claim 4 , the end portion of the thin plate member is formed in an arc shape, and the end portion of the screw is formed at the arc-shaped end portion. You may make it engage with a valley bottom. If the arc-shaped end portion is formed in accordance with the diameter of the valley of the screw, the engagement portion with the valley of the screw is increased, and the fixing effect of the screw is increased.
[0012]
From the viewpoint of increasing the screw fixing effect, the structure shown in claim 5 may be employed. That is, the thin plate-like member is arranged on both sides of the screw. In this case, the thin plate member sandwiches the valley of the screw from both sides. This further increases the screw fixing effect. In addition, if the thin plate-like member is elastically deformed toward the printed wiring board around its engaging portion, it can be said that the loosening of the screw due to vibration can be prevented, but in this case, since the thin plate-like member is on both sides of the screw, The reaction force due to elastic deformation acts in parallel with the screwing direction, and the effect of preventing loosening of the screw is outstanding.
[0013]
If attention is paid to the elastic deformation of the thin plate-like member, as shown in claim 6 , the thin plate-like member is formed by bending in the direction away from the mounting surface of the printed wiring board around the engagement portion with the screw. Good. In this way, the thin plate member is sufficiently elastically deformed in the direction approaching the printed wiring board with the engaging portion as the center, and the reaction force acting in the direction of pulling out the screw becomes large. It is possible to reliably prevent the screws from loosening.
[0014]
Although the above has been described as an invention of a screw mounting structure, it can also be realized as an invention of a grounding structure of a printed wiring board using such a screw mounting structure. That is, a grounding structure configured using the above-described screw mounting structure as shown in claim 7 , wherein the case is realized as a grounding conductor, and the thin plate member is realized as a conductive member. The printed wiring board grounding structure is characterized in that the pattern of the printed wiring board and the grounding conductor are electrically connected via each other. In such a grounding structure, as described above, the printed wiring board does not rattle and the possibility of loosening of the screw due to vibration is reduced, so that good grounding can be realized.
[0015]
It can also be realized as an invention of an effective thin plate member used in the above-described screw mounting structure. That is, it is a thin plate member as shown in claim 8 . It goes without saying that the operation and effect of such a thin plate member are the same as the operation and effect of the thin plate member of the screw mounting structure described above.
[0016]
Of course, also in this thin plate-shaped member, it can also be set as a substantially square shape, or the edge part engaged with the valley bottom of a screw can also be made into circular arc shape. Further, it may be formed by being bent away from the mounting surface of the printed wiring board around the engaging portion with the screw. Furthermore, on the premise that the case is realized with a ground conductor, it is also possible to realize it with a member having conductive performance so that conduction through a screw is achieved between the pattern on the printed wiring board and the ground conductor. It is done.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view showing a printed wiring board 10 and a thin plate member 30 constituting the grounding structure of the embodiment.
[0018]
The printed wiring board 10 is provided with mounting holes 11 and patterns 12a, 12b, 12c, and 12d corresponding to the mounting holes 11. The mounting hole 11 is a circular hole that penetrates the printed wiring board 10.
The thin plate member 30 is a rectangular thin plate metal member. For example, beryllium copper may be used as the metal member. If beryllium copper is used, not only conductivity but sufficient elasticity can be secured. Of course, materials other than beryllium copper may be used.
[0019]
Such a thin plate member 30 is soldered to the patterns 12 a to 12 d formed on the printed wiring board 10. Specifically, it is soldered at both ends 30a in the longitudinal direction of one surface, and one set includes two patterns 12a and 12b, and another set includes two patterns 12c and 12d different from these. One is soldered. That is, a total of two thin plate members 30 are soldered to the mounting holes 11 formed in the printed wiring board 10. In FIG. 1, a state where one thin plate member 30 is arranged on the printed wiring board 10 is indicated by a two-dot chain line.
[0020]
The thin plate member 30 is placed on the printed wiring board 10 by an automatic mounting machine. At this time, cream solder is supplied in advance to the patterns 12 a to 12 d of the printed wiring board 10. Then, the cream solder is melted by reflow soldering to solder the thin plate member 30. At this time, the thin plate member 30 is positioned by the surface tension of the molten solder. In other words, the thin plate member 30 is formed in such a size that such a self-alignment effect can be obtained.
[0021]
2 is a plan view showing a state in which the thin plate-like member 30 is mounted on the printed wiring board 10, FIG. 3A is a cross-sectional view taken along line AA in FIG. 2, and FIG. FIG. 3 is an explanatory diagram showing a cross section taken along line B-B in FIG. 2 in a state where the printed wiring board 10 is fixed to the case with screws 20. The screw 20 and the printed wiring board 10 and the thin plate member 30 constitute the grounding structure of the present embodiment.
[0022]
As shown in FIG. 2, thin plate-like members 30 are mounted on both sides of the mounting hole 11 formed in the printed wiring board 10. In FIG. 2, the patterns 12 a to 12 d hidden in the thin plate member 30 are shown by hatching. Then, as shown in FIG. 3A, in the mounted state, the thin plate member 30 is positioned slightly above the mounting surface of the printed wiring board 10 by the solder that fixes the thin plate member 30.
[0023]
After the thin plate-like member 30 is mounted on the printed wiring board 10 in this way, the screw 20 is passed through the mounting hole 11 from the mounting side of the printed wiring board 10, and the screw 20 is fastened and fixed to the case as the ground conductor. Thus, the printed wiring board 10 is fixed. As shown in FIG.
[0024]
The two thin plate-like members 30 on the printed wiring board 10 have a screw 20 that is narrower than the outer diameter of the screw 20 (indicated by a two-dot chain line in FIG. 2) due to the relationship between the mounting hole 11 and the patterns 12a to 12d. Are arranged at a width of the diameter of the valley (shown by a one-dot chain line in FIG. 2). Therefore, as shown in FIG. 3B, when tightening and fixing with the screw 20, the inner end 30 b of the central portion in the short direction of the thin plate-like member 30 engages with the valley bottom 20 a of the screw 20, and the printed wiring board 10. The movement of the screw 20 with respect to is controlled. Further, by tightening and fixing the screw 20, the thin plate member 30 is elastically deformed in the screw insertion direction around the inner end portion 30 b, and the reaction force acts in a direction in which the screw 20 is pulled out.
[0025]
The case as the ground conductor and the patterns 12 a to 12 d of the printed wiring board 10 are electrically connected via the screw 20 by the tightening and fixing with the screw 20.
According to this embodiment, the thin plate member 30 is positioned on the printed wiring board 10 by the surface tension of the melted solder during reflow soldering. Thus, if the relationship between the mounting hole 11 and the patterns 12a to 12d is appropriately set, the thin plate-like member 30 can be mounted on the printed wiring board 10 with high accuracy, and the inner end of the thin plate-like member 30 is fixed when the screw 20 is fixed. It becomes possible to engage the part 30 b with the valley bottom 20 a of the screw 20. As a result, even if the screw 20 is loosened due to vibration or the like, the movement of the screw 20 with respect to the printed wiring board 10 is restricted, and the printed wiring board 10 is not rattled and a good grounding state can be ensured.
[0026]
Further, by tightening and fixing the screw 20, the thin plate-like member 30 is elastically deformed around the inner end 30 b that engages with the valley bottom 20 a of the screw 20, and the reaction force acts in a direction in which the screw 20 is pulled out. Therefore, there is a high possibility that the screw 20 can be prevented from loosening due to vibration or the like. This also ensures a good grounding condition. In addition, one thin plate member 30 is arranged on each side of the screw 20 on the printed wiring board 10. As a result, the reaction force due to the elastic deformation of the thin plate member 30 acts substantially parallel to the screwing direction, so that the possibility of preventing loosening of the screw is further increased.
[0027]
As described above, the present invention is not limited to such embodiments, and can be implemented in various forms without departing from the spirit of the present invention.
(A) In the above embodiment, the thin plate-like members 30 are arranged one by one on both sides of the mounting hole 11 of the printed wiring board 10, but the mounting hole 11 of the printed wiring board 10 is shown in FIG. It is also conceivable that the two patterns 12e and 12f are formed corresponding to the above and the thin plate member 30 is arranged on one side of the mounting hole 11. In this case, when the outer diameter of the screw 20 (indicated by a two-dot chain line in FIG. 4) is in contact with the end of the mounting hole 11, the diameter of the valley of the screw 20 (indicated by the one-dot chain line in FIG. 4). What is necessary is just to arrange | position the thin plate-shaped member 30 so that the inner side edge part 30b may contact from the other side.
[0028]
(B) In the above embodiment, both end portions 30a in the longitudinal direction of one surface of the thin plate member 30 are soldered. However, the entire one surface may be soldered. .
(C) Furthermore, instead of the thin plate member 30 of the above embodiment, various shapes of thin plate members can be employed.
[0029]
For example, when viewed from the direction indicated by the symbol α in FIG. 1, the thin plate-like members 31 and 32 having the inner end portions 31b and 32b in an arc shape as shown in FIGS. 5 (a) and 5 (b). It may be adopted. If the inner end portions 31b and 32b are formed in an arc shape according to the diameter of the valley of the screw 20, the engagement portion of the screw 20 with the valley bottom 20a is increased, and the fixing effect of the screw 20 is increased.
[0030]
Further, for example, when viewed from the direction indicated by symbol β in FIG. 1, both longitudinal end portions 33b are bent substantially vertically from the central portion 33a as shown in FIG. You may employ | adopt the thin plate-shaped member 33 bent to the side substantially perpendicular | vertical. Further, as shown in FIG. 5D, a thin plate-like member 34 in which a central portion 34a is formed by being gently inclined upward from both end portions 34b may be employed. Further, it is bent substantially vertically upward from one end portion 35b, and the bent portion is bent to the opposite side to form a central portion 35a. The thin plate-like shape is smoothly connected from the central portion 35a to the other end portion 35c. The member 35 may be adopted. Thus, if the thin plate-like members 33 to 35 bent so as to be mounted away from the mounting surface of the printed wiring board 10 around the center portions 33a, 34a and 35a engaged with the valley bottom 20a of the screw 20 are used. Since it is sufficiently elastically deformed in the direction approaching the printed wiring board 10, the reaction force acting in the direction of pulling out the screw 20 is increased, and loosening of the screw 20 due to vibration or the like can be reliably prevented.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a thin plate member and a printed wiring board according to an embodiment.
FIG. 2 is a plan view showing a mounted state of a thin plate member.
3A is a cross-sectional view taken along the line AA in FIG. 2, and FIG. 3B is an explanatory view showing a cross section taken along the line BB in FIG. 2 in a screw insertion state.
FIG. 4 is a plan view showing a mounted state of a thin plate member in another embodiment.
FIG. 5 is an explanatory view showing variations of a thin plate member.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Printed wiring board 11 ... Mounting hole 12a, 12b, 12c, 12d ... Pattern 20 ... Screw 20a ... Screw valley bottom 30 ... Thin plate-like member 30a ... Both ends 30b ... Inner edge 31, 32, 33, 34, 35 ... Thin plate-like members 31b, 32b ... inner end portions 33a, 34a, 35a ... central portions 33b, 34b, 35b, 35c ... end portions

Claims (8)

A printed wiring board on which a mounting hole and a pattern corresponding to the mounting hole are formed;
A screw for passing through the mounting hole and fixing the printed wiring board to the case;
A thin plate-like member that covers a part of the edge of the mounting hole and engages with a valley bottom of the screw that passes through the mounting hole to restrict displacement of the screw with respect to the printed wiring board when tightening and fixing with the screw. A screw mounting structure composed of
According to the outer shape of at least both ends in the region on the printed wiring board where the thin plate-like member is arranged so as to cover a part of the edge of the mounting hole, the pattern is formed,
The thin plate member includes wherein the solder surface tension caused by melting the cream solder supplied to the pattern by reflow soldering, are soldered being positioned in a pattern on the printed circuit board Screw mounting structure for printed wiring boards. 2. The screw mounting structure according to claim 1, wherein the pattern has an outer shape of both end portions in an area on the printed wiring board in which the thin plate-like member is disposed so as to cover a part of an end edge portion of the mounting hole. Formed together, both end portions of the thin plate member are soldered to the pattern,
A screw mounting structure for a printed wiring board, wherein an intermediate portion of the thin plate member that is not soldered is engaged with a bottom of the screw. 3. The screw mounting structure according to claim 1 , wherein the thin plate member has a substantially square shape. The screw mounting structure according to claim 1 or 2 , wherein the thin plate-like member has an arcuate end, and engages with a valley bottom of the screw at the end. Construction. In screw mounting structure according to any one of claims 1 to 4, wherein the thin plate member is disposed on both sides of the screw, screw mounting structure of a printed wiring board, characterized in that sandwich the root of the screw. The screw mounting structure according to any one of claims 1 to 5 , wherein the thin plate-like member is bent in a direction away from a mounting surface of the printed wiring board around an engagement portion with the screw. The printed wiring board screw mounting structure characterized by A grounding structure configured using the screw mounting structure according to any one of claims 1 to 6 ,
The case is realized as a ground conductor, and the thin plate member is realized as a conductive member, whereby the pattern of the printed wiring board and the ground conductor are electrically connected via the screw. The printed wiring board grounding structure. A printed wiring board on which a mounting hole and a pattern corresponding to the mounting hole are formed;
The screw mounting structure of the printed wiring board is configured together with a screw for passing through the mounting hole and fixing the printed wiring board to the case,
A thin plate-like member that covers a part of the edge of the mounting hole and engages with a valley bottom of the screw that passes through the mounting hole to restrict displacement of the screw with respect to the printed wiring board when tightening and fixing with the screw. Because
According to the outer shape of at least both ends in the region on the printed wiring board arranged to cover a part of the edge of the mounting hole, the pattern is formed,
A thin plate-like member characterized by being positioned and soldered to a pattern on the printed wiring board by a surface tension of solder generated by melting cream solder supplied to the pattern by reflow soldering .

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