JP4176217B2 - Circuit board of multi-optical axis photoelectric switch - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a circuit board of a multi-optical axis photoelectric switch.
[0002]
[Prior art]
The circuit board of the multi-optical axis photoelectric switch has a plurality of photoelectric elements (light projecting elements or light receiving elements) along the longitudinal direction of the long substrate, and many electronic components such as resistors, capacitors, and transistors. Implement and prepare. In addition, the substrate is formed into a final size by cutting a portion that has been half-cut in advance after the mounting process, and is, for example, screwed to a case provided in the multi-optical axis photoelectric switch.
[0003]
[Problems to be solved by the invention]
By the way, there are the following two means for mounting the above-described photoelectric element on the substrate. One is to use a photoelectrically packaged resin element and place it at a predetermined position on the substrate for reflow soldering. However, this means may cause the photoelectric element to deviate from the normal position during soldering, resulting in optical axis misalignment. In particular, since the multi-optical axis photoelectric switch has a narrow beam, the slight optical axis deviation described above is also a problem.
[0004]
The other one uses a bare chip shape not packaged with a resin as a photoelectric element, which is fixed to a substrate with an adhesive, and further subjected to wire bonding. According to this means, although there is no problem of the above-mentioned positional deviation, since the bare chip is weaker than the chip packaged with resin, the deformation of the substrate when the substrate is cut or screwed May cause chip cracking. In addition to this, the wire by wire bonding may be pulled and cut due to the bending deformation of the substrate.
[0005]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a circuit board of a multi-optical axis photoelectric switch free from fear of chip breakage and wire breakage due to bending deformation of the substrate.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, a plurality of bare chip photoelectric elements arranged along the longitudinal direction of a long substrate are electrically connected to a conductive path on the substrate by wire bonding. In the circuit board of the multi-optical axis photoelectric switch formed, by forming a slit leaving a pair of connecting portions on both sides in the longitudinal direction of the substrate around the photoelectric element arrangement portion where the photoelectric element is arranged among the substrates, The photoelectric element placement portion is separated from the outside of the slit, and the conductive path extends to a position reaching the photoelectric element placement portion via the connecting portion, and a land is provided at the extended tip portion. The photoelectric element is characterized in that it is conductively connected to the land with a wire .
[0007]
The invention according to claim 2 is a multi-optical axis photoelectric switch in which a plurality of bare-chip photoelectric elements arranged along the longitudinal direction of a long substrate are conductively connected to a conductive path on the substrate by wire bonding. In this circuit board, a C-shaped slit that substantially surrounds each photoelectric element is formed in the substrate, so that the photoelectric element placement part inside the slit of the board is cut from the outside of the slit, leaving the connecting part. The conductive path is extended to a position reaching the photoelectric element placement part via the communication part, a land is provided at the extended tip part, and the photoelectric element is a wire. It is characterized in that it is conductively connected to the land .
[0008]
[Action and effect of the invention]
<Invention of Claim 1>
Of the substrate, the photoelectric element placement portion is connected to the outside of the slit only by the connecting portion in the width direction of the substrate, and is not connected to the outside of the slit in the longitudinal direction of the substrate. However, the photoelectric element arrangement portion does not bend and deform. Thereby, it is prevented that an excessive force is applied to the bare chip-shaped photoelectric element and the wire by wire bonding, and chip breakage and wire breakage can be prevented. In addition, since the photoelectric element placement portion is connected to the outside of the slit in a doubly supported state by the pair of connecting portions, stability is good.
[0009]
<Invention of Claim 2>
Since the photoelectric element placement portion of the substrate is separated from the outside of the slit, leaving one connecting portion, even if the substrate is bent and deformed not only in the longitudinal direction but also in any direction, the deformation is photoelectric element. It does not reach the placement section. Thereby, it is prevented that an excessive force is applied to the bare chip-shaped photoelectric element and the wire by wire bonding, and chip breakage and wire breakage can be prevented.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
<First Embodiment>
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. The multi-optical axis photoelectric switch includes a light projecting unit and a light receiving unit. The light projecting unit is shown in FIG. 1 and includes an elongated case 10, and a circuit board 11 (hereinafter simply referred to as “circuit board 11”) of the multi-optical axis photoelectric switch of the present embodiment at the back thereof. Is screwed.
[0011]
The planar shape of the circuit board 11 is shown in FIG. 2, and a plurality of photoelectric elements 13 and resistors, capacitors, transistors, and the like (not shown) are mounted on an elongated board 12.
[0012]
The plurality of photoelectric elements 13 are arranged at equal intervals in a line along the longitudinal direction of the substrate 12. Each photoelectric element 13 is configured by a bare chip-shaped LED chip that is a light projecting element, and a pair of electrodes for passing a direct current through the LED are a lower surface 13A and an upper surface 13B of the photoelectric element 13 (see FIG. 4). It is provided separately. Each electrode of the photoelectric element 13 is electrically connected to the GND level land 14A and the plus level land 14B in the conductive path printed on the substrate 12 (see FIG. 3). More specifically, the land 14A is laid on the photoelectric element placement portion 15 where the photoelectric element 13 is arranged on the substrate 12, and the lower surface 13A of the photoelectric element 13 is fixed on the land 14A by a conductive adhesive. Has been. Thereby, the electrode provided on the lower surface 13A of the photoelectric element 13 is conductively connected to the land 14A. Further, the land 14B extends to the vicinity of the place where the photoelectric element 13 is fixed in the photoelectric element arrangement portion 15, and the space between the land 14B and the upper surface 13B of the photoelectric element 13 is a wire W formed by wire bonding. Conductive connection. As shown in FIG. 4, the entire photoelectric element 13 is covered with the potting resin J.
[0013]
Now, a slit 16 is formed in the substrate 12 so as to substantially surround each photoelectric element 13 (see FIG. 3), and the above-described photoelectric element placement portion 15 leaves the connecting portion 17 from the outside of the slit 16. Separated. More specifically, the slits 16 are arranged symmetrically with respect to the photoelectric element 13 in the longitudinal direction of the substrate 12 as a pair, and each slit 16 has an angle shape composed of isosceles sides intersecting at right angles. There is no. And each edge part of both the slits 16 and 16 is mutually adjoined, and between those edge parts is the said connection parts 17 and 17. FIG. That is, in the present embodiment, the connecting portions 17 are provided in pairs on both sides of the photoelectric element placement portion 15 in the width direction of the substrate 12. Further, an electric circuit 18A from the land 14A is laid on the left connecting part 17 in FIG. 3, and an electric circuit 18B from the land 14B is laid on the right connecting part 17 in FIG.
[0014]
Next, the effect of this embodiment is demonstrated.
In the circuit board 11 of the present embodiment, in the electronic component mounting process, the plurality of boards 12 are integrally connected to each other, and the partition portions of the boards 12 are half-cut. Then, after mounting the electronic component, the long substrate 12 shown in FIG. Next, as shown in FIG. 1, the circuit board 11 is secured to the back of the case 10 of the multi-optical axis photoelectric switch with screws B, and a convex lens 20 corresponding to each photoelectric element 13 is provided on the front surface thereof. The provided closing plate 21 is attached, and the light projecting unit of the multi-optical axis photoelectric switch is completed.
[0015]
Here, when the substrate 12 is cut or screwed to the case 10, it receives an external force and bends and deforms in the longitudinal direction. However, the photoelectric element placement portion 15 is connected to the outside of the slit 16 only by the connecting portions 17 and 17 in the width direction of the substrate 12, and is not connected to the outside of the slit 16 in the longitudinal direction of the substrate 12. Even if it bends and deforms in the longitudinal direction, the photoelectric element placement portion 15 does not bend and deform. Thereby, it is possible to prevent an excessive force from being applied to the bare chip-shaped photoelectric element 13 and the wire W connecting the photoelectric element 13 and the land 14B, and it is possible to prevent chip breakage and wire breakage.
[0016]
Thus, according to the circuit board 11 of the multi-optical axis photoelectric switch of the present embodiment, there is no fear of chip breakage or wire breakage due to bending deformation of the circuit board 11. Moreover, since the photoelectric element 13 is fixed to the substrate 12 with an adhesive and wire-bonded, the position of the photoelectric element is not shifted by the melted solder as in the case of conventional reflow soldering, The optical axis can be adjusted accurately. In addition, since the photoelectric element placement unit 15 is connected to the outside of the slit 16 by a pair of connecting parts 17 and 17 arranged on both sides thereof, the photoelectric element placement unit 15 has good stability. The wobbling of the part 15 can be prevented, and the photoelectric element placement part 15 can be prevented from being deformed by being pushed. Further, under the condition that the strength is the same, the width of the connecting portion can be reduced when the number of connecting portions is two, compared with the case where there is one connecting portion. It is possible to prevent the deformation from reaching the photoelectric element placement portion 15.
[0017]
Second Embodiment
This embodiment is shown in FIG. 5, and the slit 26 is mainly configured differently from the slit 16 of the first embodiment. Hereinafter, only portions different from those of the first embodiment will be described, and the same portions are denoted by the same reference numerals, and redundant description will be omitted.
[0018]
The slits 26 of the present embodiment are formed in a C shape that substantially surrounds the periphery of each photoelectric element 13, and thus, each photoelectric element arrangement portion 27 has a single connecting portion 25. Yes. Moreover, on the connection part 25, both electric circuit 18A, 18B connected to both land 14A, 14B is extended in parallel.
[0019]
In the configuration of the present embodiment, since the photoelectric element arranging portion 27 is connected to the outside in a cantilever state via one connecting portion 25, the substrate 12 can be bent and deformed not only in the longitudinal direction but also in any direction. The deformation does not reach the photoelectric element arrangement portion 27.
[0020]
In consideration of the fact that the substrate 12 is most easily bent in the longitudinal direction, if the connecting portion 25 is arranged in the longitudinal direction of the substrate 12 with respect to the photoelectric element arranging portion 27, the substrate 12 is bent and deformed in the longitudinal direction. The influence on the photoelectric element arrangement part 27 due to the above becomes irrelevant to the width dimension of the connecting part 25, and the bending deformation in the longitudinal direction of the substrate 12 cannot be applied to the photoelectric element arrangement part 27 more effectively. .
[0021]
<Other embodiments>
The present invention is not limited to the embodiments. For example, the embodiments described below are also included in the technical scope of the present invention, and various modifications other than those described below can be made without departing from the scope of the invention. Can be implemented.
[0022]
(1) In the first embodiment, the end portions of the angle-shaped slits 16 and 16 are brought close to each other to form the pair of connecting portions 17 and 17 therebetween. For example, as shown in FIG. It is good also as a structure which provided the pair of connection parts 31 and 31 by making the both ends of a pair of slits 30 and 30 which make | form and adjoin.
Alternatively, as shown in FIG. 8, a pair of connecting portions is formed on both sides in the direction orthogonal to the longitudinal direction of the substrate 12 by forming linear slits 16 and 16 on both ends in the longitudinal direction of the photoelectric element placement portion 15. 17 and 17 may be formed to separate the photoelectric element placement portion 15 from the outside of the slit 16.
[0023]
(2) The slit according to claim 2 of the present invention does not have to be a complete alphabet C-shape like the slit 26 of the second embodiment. What is necessary is just to make a C shape. Therefore, for example, as shown in the slit 32 shown in FIG. 7, one corner portion of a rectangle may be cut out and a plurality of corner portions 33 may be provided.
[Brief description of the drawings]
FIG. 1 is a side sectional view of a light projecting unit of a multi-optical axis photoelectric switch according to a first embodiment of the present invention. FIG. 2 is a plan view of a circuit board. FIG. 5 is an enlarged side cross-sectional view of the circuit board according to the second embodiment. FIG. 6 is an enlarged plan view of the photoelectric element placement portion of the circuit board according to another embodiment. FIG. 8 is an enlarged plan view of the photoelectric element arrangement portion of the circuit boards of different embodiments. FIG. 8 is an enlarged plan view of the photoelectric element arrangement portion of the circuit boards of different embodiments.
DESCRIPTION OF SYMBOLS 11 ... Circuit board 13 ... Photoelectric element 15, 27 ... Photoelectric element arrangement | positioning part 16, 26, 30, 32 ... Slit 17, 25, 31 ... Communication part 18A, 18B ... Electric circuit W ... Wire

Claims (2)

In a circuit board of a multi-optical axis photoelectric switch in which a plurality of bare chip photoelectric elements arranged along the longitudinal direction of a long substrate are conductively connected to a conductive path on the substrate by wire bonding,
A slit is formed around the photoelectric element arrangement portion where the photoelectric element is arranged in the substrate, leaving a pair of connecting portions on both sides in the longitudinal direction of the substrate, thereby making the photoelectric element arrangement portion of the slit. Separated from the outside ,
The conductive path is extended to a position reaching the photoelectric element placement portion through the communication portion, and a land is provided at the extended tip portion.
A circuit board of a multi-optical axis photoelectric switch, wherein the photoelectric element is conductively connected to the land with a wire . In a circuit board of a multi-optical axis photoelectric switch in which a plurality of bare chip photoelectric elements arranged along the longitudinal direction of a long substrate are conductively connected to a conductive path on the substrate by wire bonding,
By forming a C-shaped slit in the substrate that substantially surrounds each photoelectric element, the photoelectric element placement portion inside the slit of the substrate is separated from the outside of the slit leaving a connecting portion. along with being,
The conductive path is extended to a position reaching the photoelectric element placement portion through the communication portion, and a land is provided at the extended tip portion.
A circuit board of a multi-optical axis photoelectric switch, wherein the photoelectric element is conductively connected to the land with a wire .

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