JP4286515B2 - Manufacturing method of light emitting / receiving element mounting substrate - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a photoelectric switch used in a production line of a factory, and particularly relates to facilitation of manufacturing and space saving of a product.
[0002]
[Prior art]
(I) Photoelectric switches for detecting an object, positioning an object, and the like are widely used in factory production lines. The retro-reflective photoelectric switch is a device in which a reflecting mirror is arranged in the direction of the detection target, and the light emitted from the light projecting unit to the detection target is reflected by the reflecting mirror and received by the light receiving unit. Detects the detected object by blocking light, and the light projecting element and the light receiving element are usually incorporated in the housing. Conventionally, these light projecting elements and light receiving elements are attached as separate parts to a substrate by soldering or the like, and are further fixed in a casing for positioning (for example, see Patent Document 1).
[0003]
(Ii) On the other hand, as a technique for directly bonding a bare chip such as an IC on a substrate, a method of covering and protecting a pair chip with a resin is known in order to prevent the bare chip from being exposed to the outside air. For example, a sealing frame is printed by screen printing to prevent the sealing material from flowing out (for example, refer to Patent Document 2), or a recess is formed at the bare chip placement location of the substrate. A material filled with a material (for example, see Patent Document 3) is known.
[0004]
[Patent Document 1]
JP-A-7-220590 (FIGS. 1 and 5)
[Patent Document 2]
JP-A-5-226517 (page 2-3, Fig. 1)
[Patent Document 3]
Japanese Patent Laid-Open No. 10-79563 (page 5, FIG. 1)
[0005]
[Problems to be solved by the invention]
However, the conventional photoelectric switch as described above (i) has a problem that the manufacturing process is complicated because the light emitting / receiving element needs to be positioned as described above.
[0006]
Moreover, if the technology as described in (ii) above is applied to a photoelectric switch and the entire light emitting / receiving element is sealed with resin, it is possible to mount the light emitting / receiving element directly on the substrate. There has been a problem that an optical interference (wraparound) phenomenon occurs. For example, the light radiated from the light projecting element is irregularly reflected on the resin surface, so that the light reaches the light receiving element without passing through the reflecting mirror, and the apparatus may malfunction.
[0007]
[Means for Solving the Problems and Effects of the Invention]
(1) The light emitting / receiving element mounting substrate of the present invention is:
A method for manufacturing a light projecting / receiving element mounting substrate, comprising at least a light projecting element and a light receiving element, wherein first and second sealing frames for optically separating the light projecting element and the light receiving element are formed on the same substrate by printing. Because
The first sealing frame and the lower layer of the second sealing frame are printed using the first sealing frame forming mold, and further, the second sealing frame is formed using the second sealing frame forming mold. By printing the upper layer of the stop frame,
Forming the first and second sealing frames having different heights on the same substrate;
It is characterized by.
[0008]
As a result, sealing frames having different heights can be accurately and reliably formed on the same substrate, and positioning between the light projecting element and the light receiving element is unnecessary, so that the manufacturing is easy and the manufacturing cost is reduced. Can do.
[0009]
(2) In the manufacturing method of the light emitting / receiving element mounting substrate according to the present invention, the first light emitting element, the light receiving element, and the display element are protected after the first, second, and third sealing frames are printed. The resin for injection | pouring was injected in the sealing frame.
Thereby, a compact light projecting / receiving element mounting apparatus can be provided by sealing the light projecting element, the light receiving element, and the display element on the substrate.
[0010]
(3) In the manufacturing method of the light emitting / receiving element mounting substrate according to the present invention, the sealing frame of the light projecting element is circular, and the resin injected into the sealing frame has a convex shape. And
[0011]
Thereby, directional light can be emitted from the light projecting element.
[0012]
(4) The method for manufacturing a light emitting / receiving element mounting substrate according to the present invention is characterized in that the sealing frame is formed by printing.
[0013]
Thereby, a sealing frame can be shape | molded correctly and reliably.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
[Configuration of retroreflective photoelectric switch]
An embodiment in which the present invention is used in a light projecting / receiving device of a retroreflective photoelectric switch will be described below with reference to FIGS.
[0017]
First, the structure of the reflective photoelectric switch will be described with reference to FIG. FIG. 1 is a perspective view showing an outer shape of a light projecting / receiving device 2 provided with a light projecting / receiving device mounting substrate and a reflecting mirror 4 according to the present invention. The regressive reflection type photoelectric switch is configured by a combination of the light projecting / receiving device 2 and the reflecting mirror 4.
[0018]
As shown in FIG. 1, the light projecting / receiving device 2 includes a light projecting window 6, a light receiving window 8, a power source display unit 10, and a detection display unit 12. The light projection window 6 is a portion from which light is emitted in order to detect an object. The light receiving window 8 is a part that receives the light emitted from the light projecting window 6 after being reflected by the reflecting mirror 4. The power supply display unit 10 is a portion that is turned on when the light emitting / receiving device 2 is turned on and is turned off when the power supply is turned off (as a stable display unit that displays a stable detection state instead of the power supply display unit 10). It is good.) The detection display unit 12 is a portion that lights up when an object is detected. Further, in order to output the light signal received by the light receiving window 8 to the outside, a cable 14 extends from the light projecting / receiving device 2 and is connected to a production line management computer, for example. The reflecting mirror 4 has a reflecting surface 4 a for reflecting light so that the light received from the light projecting unit 6 reaches the light receiving unit 8, and is disposed to face the light projecting and receiving device 2.
[0019]
The structure of the board | substrate 30 integrated in the inside of the light projection / reception apparatus 2 shown in FIG. 1 is demonstrated using FIG. As shown in FIG. 2, the substrate 30 includes a light projecting unit 26, a light receiving unit 28, a detection display lamp 20, a power display lamp 22, and a protection circuit unit 24 on the upper surface.
[0020]
As shown in FIG. 2, the light projecting unit 26 has a light projecting element (for example, a light emitting diode) L1 mounted on the substrate 30 as a center, and a transparent or light projecting convex so as to protect it. Shaped resin E4 (shaded portion) is molded. Further, a round sealing frame S3 is formed at a predetermined height so as to surround the convex resin E4. When the light projecting element L1 is turned on, light is emitted from the light projecting window 6 shown in FIG.
[0021]
A light receiving element (for example, a photo IC chip) F is incorporated in the light receiving portion 28, and a square resin E3 (shaded portion) is molded so as to protect it. In addition, a rectangular sealing frame S2 is formed at a predetermined height so as to surround the rectangular resin E3. The light receiving element F receives the light passing through the light receiving window 8 shown in FIG. 1 and outputs a detection signal.
[0022]
As shown in FIG. 2, the sealing frame S3 and the sealing frame S2 are provided at a predetermined interval, and are optically independent from each other. As long as the sealing frames S2 and S3 are optically independent, they are continuous like a sealing frame S1 (see FIG. 2) of the detection display lamp 20 and the power display lamp 22 described later. You may provide as a sealed frame. Accordingly, it is possible to reduce the amount of detection light that reaches the light receiving element F directly from the light projecting element L1 without passing through the reflecting mirror 4 (see FIG. 1).
[0023]
The detection display lamp 20 and the power display lamp 22 are mounted with a detection display element (for example, a light emitting diode) L2 and a power display element (for example, a light emitting diode) L3, respectively. It is covered and protected by the resin E2 and the resin E1 in the provided sealing frame S1. Further, protection circuit elements G1 and G2 covered and protected by a resin E5 are mounted in a rectangular sealing frame S4 of the protection circuit section 24.
[0024]
As described above, the upper surface of the substrate 30 (one of the substrate surfaces on which at least the light projecting element and the light receiving element are mounted) is suitable for a mounting method in which positioning is performed with a sealing frame and protection is performed with resin. For example, an element such as a bare chip is mounted. On the other hand, other elements (not shown) are mounted on the lower surface of the substrate 30. Thereby, there exists an advantage that manufacture of the board | substrate 30 can be performed efficiently.
[0025]
[Method of manufacturing light emitting / receiving element mounting substrate]
Next, a method for manufacturing the substrate 30 shown in FIG. 2 will be described below with reference to FIGS. In FIGS. 3a to 7, the outline of the sealing frame (S1 to S4) after the manufacture of the substrate 30 shown in FIG. 2 is indicated by dotted lines for easy understanding of the drawings.
[0026]
The manufacturing process until the substrate is completed includes (i) formation of a wiring pattern, (ii) press processing of the printed board, (iii) printing of the sealing frame (first time), and (iv) printing of the sealing frame (2 (V), (v) placement / wiring of each element and injection of sealing resin.
[0027]
(I) First, a wiring pattern indicating a main portion, which is indicated by a hatched portion in FIG. 4A, is processed on the substrate 30. In addition, since the film thickness of a wiring pattern is thin, FIG. 7B which is AA sectional drawing of the board | substrate 30 does not specifically show a wiring pattern.
[0028]
Wiring is formed as follows over almost the entire inner side of the circular sealing frame S3 so that light is easily reflected.
[0029]
As shown in FIG. 4, the light projecting portion 26 is formed with a substantially circular wiring pattern P <b> 1 partially cut into a rectangle and is plated with gold, and is provided with a predetermined interval so as to insulate it. The wiring pattern P2 is formed. With the wiring patterns P1 and P2, a wiring pattern P having a reflective surface is formed in the entire sealing frame S3 (dotted line). The reason for performing the gold plating is to increase the reflectance of light.
[0030]
(Ii) As shown in FIG. 3a, a hole for forming the outer shape of the substrate 30 (see FIG. 2) is formed in one printed circuit board 32 by pressing. In addition, from this printed circuit board 32, a total of 20 light emitting / receiving element mounting boards can be manufactured.
[0031]
4A to 7A are enlarged views of the part α in FIG. 3a. 4B to 7B show cross sections taken along line AA in FIGS. 4A to 7A, respectively.
[0032]
(Iii) After forming the wiring pattern, the first sealing frame is printed. Thereby, the sealing frames S1, S2a, S3, and S4 indicated by the hatched portions in FIGS. 5A and 5B are formed on the substrate 30.
[0033]
As a wiring pattern printing method, screen printing (silk printing) which is a printing method using a stencil is used. These methods were used because of consideration of printing accuracy and certainty.
[0034]
Specifically, as shown in FIG. 3b, a plate 34 having a hole having the same shape as the sealing frames S1, S2a, S3, and S4 (shaded portions in FIG. 5A) (first sealing frame forming mold) Use this to print. As a result, a layer having a film thickness t1 as shown in FIG. 5B (S1, S3, S4 which is the first sealing frame and S2a which is the lower layer of the second sealing frame) is printed.
[0035]
Note that the height of the sealing frame S3 of the light projecting unit 26 shown in FIG. 5B, that is, the film thickness t1 for one screen printing is designed to be larger than the height of the light projecting element L1 shown in FIG. Yes.
[0036]
(Iv) Next, the second printing of the sealing frame is performed in the same manner as in the above (iii). However, it is different from the stencil used for the first time (see FIG. 3b) in that the stencil (see FIG. 3c) shown in FIG. 3 is used.
[0037]
Specifically, as shown in FIG. 3c, a plate 36 (second sealing frame forming mold) in which only a hole having a shape of the sealing frame S2b (shaded portion shown in FIG. 6A) of the light receiving unit 28 is opened. Printing. This is because it is necessary to increase only the sealing frame of the light receiving unit 28 for design reasons such as the thickness of the light receiving element.
[0038]
By the second printing, only the sealing frame S2b (upper layer of the second sealing frame) of the light receiving unit 28 is formed on the substrate 30 as shown by the hatched portion in FIGS. 6A and 6B. As a result, the height t2 of the entire sealing frame of the light receiving unit 26 shown in FIG. 6B is twice the film thickness t1 of the first silk printing shown in FIG. 5B, and seals having different heights are formed on the same substrate. A stop frame is formed.
[0039]
(V) After the sealing frame is completed, elements such as the light projecting element L1 and the light receiving element F shown in FIG. 2 are arranged, and wire bonding (wiring) with the wiring pattern shown in FIG. 4A is performed. The light emitting diode L1 (see FIG. 2) as a light projecting element is mounted at the center of a circular wiring pattern, and one of its anode and cathode is connected to the circular wiring pattern P1, and the other is connected to the rectangular pattern portion P2. Wired.
[0040]
After the respective elements are wire-bonded to the wiring pattern, as shown in FIGS. 7A and 7B, the resins E1 to E5 (shaded portions in FIGS. 7A and B) are sealed by the sealing frames S1 to S4 (in order to protect each element). 7A and 7B).
[0041]
The resin is filled by pouring an epoxy resin into the sealing frame. Moreover, as shown to FIG. 7B, about parts other than the light projection part 26, the quantity that the height of a sealing frame and the upper surface of resin become comparable is filled. About the light projection part 26, the quantity which is a grade which can shape | mold a desired convex lens is filled. After these resins are solidified, the manufacturing process of the upper surface of the substrate 30 is completed if the light receiving unit 28 is covered with a shield.
[0042]
Further, other components are attached by soldering or the like, and when the manufacturing process of the lower surface of the substrate 30 is completed, the substrate 30 is completed by stamping by pressing. As described above, the manufacture of the substrate 30 incorporated in the light projecting / receiving device 2 is efficiently performed.
[0043]
[Operation and function of the projector]
Next, the operation and function of the light projecting unit 26 will be described with reference to FIG. FIG. 8 is an enlarged view of the cross section (corresponding to the β portion in FIG. 7) of the light projecting portion 26 shown in FIG.
[0044]
As shown in FIG. 4A, a wiring pattern P having a reflective surface is formed on the entire inside of the sealing frame S3 of the light projecting unit 26. Thereby, the light quantity from the light projection element L1 can be raised. The principle will be described below.
[0045]
As shown in FIG. 8, when the light emitting diode L1 of the light projecting unit 26 is turned on, detection light is emitted upward from the substrate surface, and most of the light passes through the resin E4 as it is toward the reflecting mirror. (See R1 in FIG. 8). On the other hand, there is also light (see R2 in FIG. 8) that reflects on the resin surface and travels downward (that is, toward the wiring pattern P1).
[0046]
However, almost all of the light reflected downward from the resin surface is reflected upward by the wiring pattern P1 shown in FIG. 8 and becomes upward light passing through the resin E4 (in FIG. 8). R3). As a result, light that passes through the substrate 30 and leaks to the lower surface or is absorbed becomes extremely small, and as a result, the amount of detection light emitted upward is increased.
[0047]
Further, as shown in FIG. 8, the resin E4 of the light projecting portion 26 is raised and shaped into a convex shape and used as a lens. Thereby, directivity can be given to the light emitted from the light projecting element. In order to easily mold the convex lens, the sealing frame S3 of the light projecting unit 26 is molded in a circular shape as shown in FIG. 7A. The diameter of the lens (diameter of the sealing frame S3) and the curvature (curvature of the surface of the resin E4) are designed so that desired light intensity and directivity can be obtained.
[0048]
In addition, as the color of the sealing frame S3 of the light projecting unit 26, it is preferable to use white having a high light reflectance when it is necessary to increase the upper brightness. When it is necessary to prevent light from entering the light receiving element, it is preferable to use black having a high light absorption rate.
[0049]
[Other embodiments]
In the above-described embodiment, the detection display lamp 20, the power display lamp 22, and the protection circuit unit 24 are provided on the upper surface of the substrate 30, but these may not be provided.
[0050]
In the above embodiment, gold plating is performed on the wiring pattern. However, it is only necessary to form a wiring pattern having a reflective surface, and other materials can be used. Further, the wiring pattern may be formed of only a single material without plating the wiring pattern.
[0051]
In addition, in the said embodiment, although the sealing frame was formed by printing, it is not limited to this, The other method which can shape | mold the same sealing frame can also be used.
[0052]
In the above embodiment, the shape of the sealing frame S3 of the light projecting unit 26 is circular. However, other shapes can be used as long as the resin E4 can be easily molded.
[0053]
In the above embodiment, the shape of the sealing frame S2 of the light receiving unit 28 is a quadrangle. However, the shape is not limited to this, and other shapes such as a pentagon may be used.
[0054]
In the above embodiment, the retroreflective photoelectric switch has been described. However, the present invention can also be applied to a polarized retroreflective charging switch and a reflective photoelectric switch. It can also be used as a type photoelectric switch. When used as such a transmissive photoelectric switch, it is possible to easily provide a device that takes advantage of the fact that position adjustment is unnecessary and that has high reliability in object detection.
[Brief description of the drawings]
FIG. 1 is a diagram showing the outer shape of a light projecting / receiving device 2 and a reflecting mirror 4 provided with a light projecting / receiving element mounting substrate according to the present invention;
FIG. 2 is a diagram showing a configuration of a substrate 30 incorporated in the light projecting / receiving device 2;
FIG. 3A is a diagram showing press processing of a printed circuit board.
FIG. 3b is a view showing a first shape for forming a sealing frame.
FIG. 3c is a view showing a second form for forming a sealing frame.
FIG. 4 is a diagram illustrating a wiring pattern printing process.
FIG. 5 is a diagram illustrating a sealing frame printing process (first time).
FIG. 6 is a diagram showing a sealing frame printing process (second time).
FIG. 7 is a diagram illustrating a process of injecting resin into the sealing frame.
FIG. 8 is a diagram illustrating an operation and a function of a light projecting unit.
[Explanation of symbols]
2... Projecting and receiving device 4... Reflecting mirror 6... Projecting window 8... Light receiving window 10. Wiring 20... Detection display lamp 22... Power supply display lamp 24... Protection circuit section 26. Light projecting section 28. Light receiving section 30 .. substrate L 1. ... Power display element L3 ... Detection display element F ... Light receiving elements G1 and G2 ... Protection circuit elements H ... Shield insertion holes P1 and P2 ... Wiring patterns S1 to S5 ... Sealing frames E1-E5 ... Resin

Claims (4)

A method for manufacturing a light projecting / receiving element mounting substrate, comprising at least a light projecting element and a light receiving element, wherein first and second sealing frames for optically separating the light projecting element and the light receiving element are formed on the same substrate by printing. Because
The first sealing frame and the lower layer of the second sealing frame are printed using the first sealing frame forming mold, and further, the second sealing frame is formed using the second sealing frame forming mold. By printing the upper layer of the stop frame,
Forming the first and second sealing frames having different heights on the same substrate;
A method of manufacturing a light emitting / receiving element mounting substrate . In the manufacturing method of the light emitting and receiving element mounting substrate of Claim 1,
The light emitting / receiving element mounting substrate further includes a display element,
Forming a third sealing frame that makes the display element optically independent by printing using the sealing frame forming mold;
A method of manufacturing a light emitting / receiving element mounting substrate .   In the manufacturing method of the light emitting and receiving element mounting substrate of Claim 2,
  After printing the first, second and third sealing frames, a resin for protecting the light projecting element, the light receiving element and the display element was injected into the sealing frame;
  A method of manufacturing a light emitting / receiving element mounting substrate.   In the manufacturing method of the light emitting and receiving element mounting substrate of Claim 3,
  The sealing frame of the light projecting element is circular, and the resin injected into the sealing frame has a convex shape;
  A method of manufacturing a light emitting / receiving element mounting substrate.

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