TW201435379A - Optical proximity sensor and assembling method thereof - Google Patents

Abstract

The present invention relates to an optical proximity sensor and assembling method thereof. The optical proximity sensor comprises a first substrate, on which a light emitting unit and a light sensing unit are mounted. The light emitting unit and the light sensing unit are electrically connected with the first substrate. The light emitting unit comprises a second substrate and a light emitting element electrically connected with the second substrate. The light sensing unit comprises a third substrate, an opaque lid and a light sensing element electrically connected with the third substrate. The opaque lid contacted with the third substrate is above the light sensing element, and an opening corresponding to the light sensing element is formed in the opaque lid. A light signal emitted from the light emitting element could enter to the light sensing unit through the opening, but the emitted light signal beside the light sensing element is shielded by the opaque lid.

Description

Optical distance sensing device and assembling method thereof

The present invention relates to an optical distance sensing device and an assembly method thereof, and more particularly to an optical distance sensing device for reassembling a plurality of semiconductor packaged wafers and a method of assembling the same.

Optoelectronic devices are widely used, and optical sensing is one of the indispensable roles in many automated machinery, industrial machinery, semiconductor equipment, machine tools, etc. For example, proximity sensing passes through two optical components. a light-emitting component, such as a light-emitting diode (LED) and a light-sensing component, which captures and processes the light signal from the light-emitting component to detect the presence of an object, so that the controller can know whether the current mechanism is present or not. The location or number of passes, etc. In detail, a light-emitting element, such as an infrared light-emitting diode, emits an infrared signal, and if an object approaches in the detection range, and some of the infrared signal is incident on the object, the light-receiving element, such as the photosensitive element, : The infrared sensor can detect reflected infrared signals. After signal conditioning, analog-to-digital conversion, and other processing, the microprocessor or microcontroller can apply digital signals for subsequent processing.

Several assembly structures that are currently common are proposed here. First, as shown in FIG. 1, the conventional optical distance sensing device 1 is composed of a light emitting unit 40 and a light emitting unit 50. Similar to a general electronic chip, the light-emitting element 42 and the light-receiving element 52 After being cut into dies from the wafer, it is also required to be mounted on the substrates 41, 51 via a semiconductor packaging process to increase the mechanical strength thereof, and the power connection relationship and signal output are constructed by the gold wires 44 and 54 by the gold wire process. The connection channel is input, and the light-emitting element 42 and the light-receiving element 52 are sealed in the transparent substances 43 and 53 to maintain their barrier property against moisture and air, thereby forming the light-emitting unit 40 and the light-receiving unit 50. Thereafter, the light-emitting unit 40 and the light-receiving unit 50 are mounted on the printed circuit board 10 via the board-level assembly, and the solder materials 41 and 51 are electrically connected to the printed circuit board 10 to form the optical distance sensing device 1. However, since there is no shielding element between the light emitting unit 40 and the photosensitive unit 50, the light signal emitted by the light emitting unit 40 does not need to pass through the protective cover 30 and the path reflected back to the photosensitive unit 50 via the object 20 (in real terms). The line arrow indicates that it can be directly incident into the photosensitive unit 50 from the lateral direction or reflected at a large angle on the protective cover 30 into the photosensitive unit 50 (indicated by a dotted arrow). This can lead to misjudgment of objects due to misreading or excessive background noise, which is not a reliable design.

In order to improve the disadvantages of the above first figure, it is common practice to install a light-shielding rubber 60 between the printed circuit board 10 and the protective cover 30, as shown in the optical distance sensing device 2 and the third figure shown in FIG. Optical distance sensing device 3. The difference between the second embodiment and the third embodiment is that the light-emitting unit 40 and the photosensitive unit 50 of FIG. 2 are directly mounted on the printed circuit board 10. The light-emitting unit 40 and the photosensitive unit 50 of FIG. 3 are mounted on the same. On the flexible printed circuit board 13, the flexible printed circuit board 13 is further passed through a connecting unit 14 to be mounted on the printed circuit board 10. However, regardless of the structure of Figure 2 or Figure 3, the shading rubber 60 is illuminated. The unit 40 and the photosensitive unit 50 are directly connected to the printed circuit board 10 and the protective cover 30 to prevent the optical signal from passing between the light emitting unit 40 and the photosensitive unit 50 and entering the photosensitive unit 50 or protecting at a large angle. The cover 30 is reflected and enters the photosensitive unit 50. However, since the assembly process of the light-shielding rubber 60 can only be performed manually, it cannot be integrated with current industrial machines, and it is difficult to assemble, time-consuming, and costly.

Therefore, the industry has proposed an architecture that can improve the foregoing problems. For example, the optical distance sensing device 4 shown in FIG. 4 mounts a light-emitting element 72 and a photosensitive element 73 on the substrate 71 in a polycrystalline semiconductor package. . Similar to the single crystal semiconductor package, the power connection relationship and the signal output/input connection channel are also constructed by the gold wire 74 by the gold wire process, and then the light emitting element 72 and the photosensitive element 72 are sealed in the transparent substance 77. Maintain its barrier with moisture and air. However, after the gold wire process, the optical distance sensing device 4 is further provided with a light shielding cover 75 directly connected to the substrate 71. Two openings 76 are formed on the light-shielding cover 75, so that the light signal emitted from the light-emitting element 72 can be emitted from an opening 76 and enter the photosensitive element 73 from the other opening 76. The light-shielding cover 75 can shield between the light-emitting element 72 and the photosensitive element 73. Or the optical signal coming from the outside. Thereafter, the polycrystalline optical distance sensing unit 70 is mounted on the printed circuit board 10 by a surface mount technology, and is electrically connected to the printed circuit board 10 through the solder material 17.

If the optical signals reflected from the protective cover 30 are also shielded together, we need to assemble the optical distance sensing device 5 shown in FIG. number 5 In comparison with Fig. 4, a light-shielding rubber 61 is added to the light-shielding cover 75. However, it is conceivable that the assembly process of the shading rubber 60 can only be carried out manually, and cannot be integrated with the current industrial machine, and the assembly is difficult, time consuming and costly.

Therefore, how to deal with the optical characteristics, cost, and complexity of the assembly of the optical distance sensing device is an urgent issue.

An object of the present invention is to provide an optical distance sensing device and an assembly method thereof for shielding optical noise to maintain good signal quality through an opaque cover that is mounted in a photosensitive unit during semiconductor packaging.

Another object of the present invention is to provide an optical distance sensing device and an assembly method thereof for semiconductor packaging with an opaque upper cover that can be matched with current industrial machines, which simplifies the assembly process and reduces the process cost.

According to the present invention, an optical distance sensing device and an assembly method thereof are provided. The optical distance sensing device includes: a first substrate on which an illumination unit is mounted and a photosensitive unit is disposed adjacent to the illumination unit, and the illumination unit and the photosensitive unit are both The light-emitting unit is electrically connected to the first substrate, and the light-emitting unit includes a second substrate and a light-emitting element electrically connected to the second substrate. The photosensitive unit comprises a third substrate, an opaque upper cover and a photosensitive element electrically connected to the third substrate The opaque upper cover is connected to the third substrate to be disposed above the photosensitive element, wherein an opening corresponding to the photosensitive element is formed, wherein an optical signal emitted by the light emitting element can be incident into the photosensitive element through the opening, however The light signal in the direction of the side of the photosensitive unit is shielded by the opaque upper cover.

According to the present invention, there is provided an optical distance sensing device assembly method comprising the steps of: (A) mounting a light-emitting element on a second substrate and electrically connecting the second substrate to form a light-emitting unit; A photosensitive element is electrically connected to the third substrate, and an opaque upper cover is disposed above the photosensitive element to form a photosensitive unit, and an opening corresponding to the photosensitive element is formed in the opaque upper cover; and (C) is on the first substrate The light-emitting unit and the photosensitive unit are disposed adjacent to the light-emitting unit, and the light-emitting unit and the light-sensing unit are electrically connected to the first substrate, so that an optical signal emitted by the light-emitting element can be incident into the photosensitive element through the opening, but adjacent to the photosensitive unit. The optical signal in the direction of the side is obscured by the opaque upper cover.

Preferably, the light-emitting unit and the photosensitive unit are configured by a semiconductor package. In the semiconductor packaging process, the light-emitting element and the photosensitive element are better sealed by a transparent substance to block moisture and air. The formulation of the transparent substance is not limited, and it may be a single component compound or a mixture of a plurality of compounds in a plurality of ratios, such as a mixture of a plastic, a hardener, a catalyst, an epoxy, and a transparent gel. The formation of the transparent material can also be formed by a molding process and/or other forming processes, and is not limited thereto.

The second and third substrates are substrates used in a semiconductor package level, and the first substrate is a substrate used in a board-level assembly level. The first, second, and third substrates can protect the components disposed thereon and enlarge the size of the electrodes. The type of the electrodes is not limited thereto. For example, it can be a Ball Grid Array substrate or a lead frame. , copper foil substrate, resin substrate, printed circuit board substrate, soft printed Since the circuit board substrate or other types of substrates are brushed, a specific type of substrate can be selected depending on the light-emitting unit provided thereon, the pin size of the photosensitive unit, or the specifications of the semiconductor substrate.

The material of the opaque upper cover is not limited, and may be made of any opaque material that blocks light. For example, it may be made of resin, nylon, plastic, metal, liquid crystal polymer, or other opaque material. It is a black opaque top cover made of a material resistant to high temperature, and the invention is not limited. For example, nylon can be selected from PA6T, PA9T, PA66, PPA, HTN, PA46, etc., the resin can be selected from polyphenylene sulfide (PPS) resin, and the plastic can be selected from PEK, PEEK, TPI, and the like. Secondly, the opaque upper cover may optionally include other detailed structures, such as additionally forming a front plate and at least one side wall connected to the front plate, the front plate partially shielding the upper surface of the photosensitive unit to block part of the light reflected from the protective cover. The signal side wall may be connected to the third substrate via an adhesive substance on the outer side of the photosensitive unit to block the ambient light source from interfering with the photosensitive element from the outer side. Similarly, the formulation of the aforementioned adhesive substance is not limited, but is preferably an epoxy resin. The opaque upper cover can be made by molding, injection molding or other processes, and is not limited herein.

Therefore, the present invention shields the optical noise by the opaque cover with the semiconductor package process, and improves the optical component reflected from the approaching object into the photosensitive element, thereby improving the quality of the optical distance sensing device for reading the optical signal, and at the same time simplifying The assembly process of the optical distance sensing device and the reduction of the process cost.

To further illustrate the various embodiments, the invention is provided with the drawings. The drawings are a part of the disclosure of the present invention, and are mainly used to explain the embodiments, and the operation of the embodiments may be explained in conjunction with the related description of the specification. With reference to such content, those of ordinary skill in the art should be able to understand other possible embodiments and advantages of the present invention. Elements in the figures are not drawn to scale, and similar elements are generally used to represent similar elements.

First, please refer to FIG. 6 , which shows a cross-sectional structural diagram of an optical distance sensing device according to an embodiment of the present invention. Here, an optical distance sensing device 6 including one light emitting unit 40 and one photosensitive unit 57 is used as an example. However, the present invention is not limited thereto, and may be other aspects including a combination of one or more light emitting units 40 or photosensitive cells 57. As shown in the figure, the optical distance sensing device 6 includes a first substrate 18, a light emitting unit 40, a photosensitive unit 57, and a protective cover 30. The light-emitting unit 40 and the light-receiving unit 57 are preferably firstly packaged by a semiconductor package, and then mounted on the first substrate 18 through the solder materials 11 and 12 in a board-level assembly process. The light-emitting unit 40 exemplarily includes a second substrate 41, a light-emitting element 42, a transparent material 43 and a plurality of gold wires 44. The photosensitive unit 57 includes a third substrate 51, a photosensitive element 52, and a plurality of gold wires 54. , a transparent substance 55 and an opaque upper cover 56.

The semiconductor package process of the light-emitting unit 40 is first to mount the light-emitting element 42 on the second substrate 41. It should be noted that the type of the second substrate 41 is not limited herein, for example, a ball grid array (Ball Grid Array) a substrate, a lead frame, a copper foil substrate, a resin substrate, a printed circuit board substrate, or the like For a substrate of the type, a specific type of substrate can be selected depending on the pin size of the light-emitting element 42 disposed thereon. The second substrate 41 can protect the light-emitting elements 42 disposed thereon and amplify the electrodes of the light-emitting elements 42. The process of assembling the light-emitting element 42 on the second substrate 41 is also not limited. The second substrate 41 is exemplified as a lead frame, and the light-emitting element 42 is exemplified by an infrared ray cut from the wafer. Diode wafer. The light-emitting element 42 may be first fixed on the second substrate 41 via a die bonding process, and then subjected to a wire bounding process to pass the light-emitting element 42 and the output electrode on the second substrate 41 through a bonding wire 44. (not shown) is electrically connected to achieve electrical connection between the light-emitting element 42 and the conductor medium on the second substrate 41, such as a pin, a ball, or other form of conductor medium.

Next, the light-emitting element 42 is sealed in the transparent substance 43 by a molding process. The formulation of the transparent substance 4 is not limited, and it may be a single component compound or a mixture of a plurality of compounds in a plurality of ratios, such as a mixture of a plastic, a hardener, a catalyst, an epoxy resin, and a transparent gel. The light-emitting element 42 is sealed to block substances such as moisture that affect the normal operation of the light-emitting element 42.

The semiconductor package process of the photosensitive unit 57 is mainly to mount the photosensitive element 52 on the third substrate 51 to be electrically connected to the third substrate 51, and the opaque upper cover 56 is disposed above the photosensitive element 52 to form a photosensitive unit 57, in the opaque upper cover 56. An opening 563 is formed corresponding to the photosensitive member 52. In detail, there are several variations: the first one is to perform a molding process on the semiconductor packaging process of the photosensitive unit 57, and then perform a molding process to seal the photosensitive unit 57 to the transparent object. In the substance 55, the opaque upper cover 56 is connected to the third substrate 51 via an adhesive substance (not shown) on the third substrate 51, and the opaque upper cover 56 is disposed on the photosensitive unit 57 to shield the optical noise. The second method is to connect the opaque upper cover 56 to the third substrate 51 via an adhesive substance (not shown) on the third substrate 51 after performing the solid crystal and gold wire process in the semiconductor package process of the photosensitive unit 57. The opaque upper cover 56 is disposed on the photosensitive unit 57 to shield the optical noise, and then seals the photosensitive unit 57 into a transparent substance 55 such as a transparent adhesive. The third method is to seal the photosensitive unit 57 into a transparent substance 55 such as a transparent adhesive after the solid-state and gold-line process of the semiconductor package process of the photosensitive unit 57, and then form an opaque upper cover 56 via the molding to form a photosensitive Unit 57 is used to shield the optical noise. The fourth is to form the transparent substance 55 in the first molding process to seal the photosensitive unit 57 in the transparent substance 55 after the solid-state and gold-line process in the semiconductor packaging process of the photosensitive unit 57, and then through the second mold. The plastic process forming opaque upper cover 56 is disposed on the photosensitive unit 57 to shield the optical noise. Both the first and fourth semiconductor packaging processes described above can be used to form a structure that modulates the light, such as a condensable lens structure, or other type of structure, in the transparent material 55 during the molding step.

The material of the opaque upper cover 56 is not limited, and may be made of any opaque material that blocks light. For example, it may be made of resin, nylon, plastic, metal, liquid crystal polymer, or other opaque material. It is a black opaque top cover made of a material resistant to high temperature, and the invention is not limited. For example, nylon can be selected from PA6T, PA9T, PA66, PPA, HTN, For PA46, etc., the resin can be selected from polyphenylene sulfide (PPS) resin, and the plastic can be selected from PEK, PEEK, TPI, and the like. Here, the opaque upper cover 56 illustratively includes a side wall 561 and a front plate 562. The edge of the front plate 562 is formed with an opening 563 corresponding to the photosensitive unit 57 below. The sidewall 561 may be connected to the third substrate 51 via an adhesive substance (not shown) on the outer side of the photosensitive unit 57 to block the ambient light source from interfering with the photosensitive element 52 from the outer direction, and the front plate 562 may partially shield the photosensitive unit 57. The surface enters the photosensitive unit 57 with a light signal that is partially reflected from the protective cover 30. The formulation of the adhesive substance is not limited, but is preferably an epoxy resin. The opaque upper cover 56 can be formed by molding, injection molding, or other processes without limitation.

It should be noted that the present embodiment does not limit the type of the third substrate 51. For example, it may be a Ball Grid Array substrate, a lead frame, a copper foil substrate, a resin substrate, or a printed circuit board. For a substrate or other kind of substrate, a specific type of substrate can be selected depending on the pin size of the photosensitive member 52 provided thereon. Then, a board-level assembly process is performed, and the light-emitting unit 40 and the photosensitive unit 57 are mounted on the first substrate 18 adjacent to the light-emitting unit 40, and the light-emitting unit 40 and the photosensitive unit 57 are electrically connected to the first substrate 18 to emit light. The optical signal from element 40 can be incident on photosensitive element 52 via opening 563, however the optical signal in the direction of the side of photosensitive unit 57 is obscured by opaque upper cover 56. The board-level assembly process here firstly fixes the light-emitting unit 40 and the photosensitive unit 57 to the reserved position of the first substrate 18 with the solder materials 11, 12, and usually the corresponding position has been configured at the reserved position, so that the soldering is performed. After that, the light emitting unit 40 is formed. The electrical connection relationship between the photosensitive unit 57 and the first substrate 18. At this time, the light emitting unit 40 and the photosensitive unit 57 are transmitted through a conductor medium on the first substrate 40, such as a connector or other form of conductor medium to output/input an electronic signal or a power source to perform an operation of emitting light or sensitizing, so that the light emitting element 42 The emitted optical signal is reflected by an object 20 located within a range of distances and can be incident on the photosensitive unit 57 via the opening 563. However, the light signals emitted from the side of the light-emitting element 42 and most of the light signals (shown by broken lines) reflected from the protective cover 30 are blocked by the opaque upper cover 56 without being detected by the photosensitive unit 57. When detecting the reflected optical signal, the photosensitive unit 57 supplies the optical signal conversion electronic signal output to the rear end component (not shown) to confirm that the object 20 is in proximity.

It should be noted that the first substrate 18 is a substrate used for the board-level assembly level, and the light-emitting unit 40 and the photosensitive unit 57 disposed thereon can be protected and the electrode size can be enlarged. The type of the electrode is not limited herein, for example, In the case of a printed circuit board substrate, a flexible printed circuit board substrate, or other types of substrates, a specific type of substrate can be selected depending on the specifications of the second substrate 41 or the third substrate 51 provided thereon.

Therefore, the present invention shields the optical noise by the opaque cover with the semiconductor package process, and improves the optical component reflected from the shield into the photosensitive element, thereby improving the quality of the reading signal of the photosensitive element, and at the same time simplifying the assembly process and reducing the assembly process. Process cost.

The above description is based on a number of different embodiments of the invention, wherein the features may be implemented in a single or different combination. Therefore, the disclosure of the embodiments of the present invention is intended to be illustrative of specific embodiments of the present invention and should not be construed as example. Further, the foregoing description and the accompanying drawings are merely illustrative of the invention and are not limited. Variations or combinations of other elements are possible and are not intended to limit the spirit and scope of the invention.

1, 2, 3, 4, 5, 6‧ ‧ optical distance sensing device

10‧‧‧Printed circuit board

11, 12, 15, 16, 17‧‧‧ welding materials

13‧‧‧Soft printed circuit board

14‧‧‧ Connection unit

18‧‧‧First substrate

20‧‧‧ objects

30‧‧‧ protective cover

40‧‧‧Lighting unit

41‧‧‧second substrate

42‧‧‧Lighting elements

43‧‧‧Transparent substances

44‧‧‧ Gold wire

50, 57‧‧‧Photosensitive unit

51‧‧‧ Third substrate

52‧‧‧Photosensitive elements

53‧‧‧Transparent substances

54‧‧‧ Gold wire

55‧‧‧Transparent substances

56‧‧‧opaque cover

60, 61‧‧‧ shading rubber

70‧‧‧Polycrystalline optical distance sensing unit

71‧‧‧Substrate

72‧‧‧Lighting elements

73‧‧‧Photosensitive elements

74‧‧‧ Gold wire

75‧‧‧Lighting cover

76‧‧‧ openings

77‧‧‧Transparent substances

561‧‧‧ side wall

562‧‧‧ front board

563‧‧‧ openings

Fig. 1 is a schematic cross-sectional view showing one of the conventional optical distance sensing devices.

Figure 2 is a schematic cross-sectional view showing one of the conventional optical distance sensing devices.

Figure 3 is a schematic cross-sectional view showing one of the conventional optical distance sensing devices.

Figure 4 is a schematic cross-sectional view showing one of the conventional optical distance sensing devices.

Figure 5 is a schematic cross-sectional view showing one of the conventional optical distance sensing devices.

Figure 6 is a cross-sectional view showing one of the optical distance sensing devices according to an embodiment of the present invention.

6‧‧‧Optical distance sensing device

11, 12‧‧‧ welding materials

18‧‧‧First substrate

20‧‧‧ objects

30‧‧‧ protective cover

40‧‧‧Lighting unit

41‧‧‧second substrate

42‧‧‧Lighting elements

43‧‧‧Transparent substances

44‧‧‧ Gold wire

51‧‧‧ Third substrate

52‧‧‧Photosensitive elements

54‧‧‧ Gold wire

55‧‧‧Transparent substances

56‧‧‧opaque cover

57‧‧‧Photosensitive unit

561‧‧‧ side wall

562‧‧‧ front board

563‧‧‧ openings

Claims (16)

An optical distance sensing device includes: a first substrate on which a light emitting unit and a photosensitive unit are disposed adjacent to the light emitting unit, wherein the light emitting unit and the photosensitive unit are electrically connected to the first substrate, and the light is emitted The unit includes a second substrate and a light-emitting component electrically connected to the second substrate, the photosensitive unit includes a third substrate, an opaque upper cover, and a photosensitive element electrically connected to the third substrate, the opaque upper cover and the The third substrate is connected to be disposed above the photosensitive element, wherein an opening is formed corresponding to the photosensitive element; wherein an optical signal emitted by the light emitting element can be incident into the photosensitive element through the opening, but beside the photosensitive unit The optical signal in the direction is obscured by the opaque cover. The optical distance sensing device of claim 1, wherein the opaque upper cover further comprises a front plate and at least one side wall is connected to the front plate, the side wall is past an adhesive substance on the outer side of the photosensitive unit Three substrate connections. The optical distance sensing device of claim 2, wherein the adhesive substance is an epoxy resin. The optical distance sensing device of claim 1, wherein the opaque upper cover is a black opaque upper cover. The optical distance sensing device of claim 1, wherein the opaque upper cover is a nylon, a plastic, a metal, or a liquid crystal polymer. The optical distance sensing device of claim 1, wherein the opaque upper cover is molded. The optical distance sensing device of claim 1, wherein the first substrate is a copper foil substrate, a lead frame, a resin substrate, a printed circuit board substrate or a flexible printed circuit board substrate. The optical distance sensing device of claim 1, wherein the second substrate is a copper foil substrate, a lead frame, a resin substrate, a printed circuit board substrate or a flexible printed circuit board substrate. The optical distance sensing device of claim 1, wherein the third substrate is a copper foil substrate, a lead frame, a resin substrate, a printed circuit board substrate or a flexible printed circuit board substrate. The optical distance sensing device of claim 1, wherein the light-emitting element and the photosensitive element are sealed by a transparent substance. The optical distance sensing device of claim 10, wherein the transparent material comprises a mixture of plastic, hardener, catalyst, epoxy resin, and transparent glue mixed in any ratio. A method for assembling an optical distance sensing device, comprising the steps of: (A) mounting a light-emitting element on a second substrate and electrically connecting the second substrate to form a light-emitting unit; and (B) assembling on a third substrate a photosensitive element is electrically connected to the third substrate, and an opaque upper cover is disposed over the photosensitive element to form a photosensitive unit, an opening is formed in the opaque upper cover to correspond to the photosensitive element; and (C) is on the first substrate The light-emitting unit is mounted on the light-emitting unit, and the light-emitting unit and the light-sensing unit are electrically connected to the first substrate, so that an optical signal emitted by the light-emitting element can be incident through the opening. The photosensitive element, however, the optical signal in the direction of the side of the photosensitive unit is shielded by the opaque upper cover. The method of assembling an optical distance sensing device according to claim 12, wherein the step (B) further comprises: bonding at least one side wall of the front plate of the opaque upper cover to an outer side of the photosensitive unit; A substance is coupled to the third substrate. The assembly method of the optical distance sensing device according to claim 13 of the patent application scope The method, wherein the step B) further comprises: connecting the sidewall of the opaque upper cover to the third substrate with an epoxy resin as the adhesive substance. The method of assembling an optical distance sensing device according to claim 12, wherein the step (B) further comprises: forming the opaque upper cover with a nylon, a plastic, a metal, or a liquid crystal polymer. The method of assembling an optical distance sensing device according to claim 12, wherein the step (B) further comprises: manufacturing the opaque upper cover by a molding process.