JP2013097038A - Lens module manufacturing method - Google Patents

Abstract

Provided is a lens module manufacturing method capable of stably holding a spacer substrate and manufacturing a large number of lens modules while using a large transparent substrate.
Since a through hole ST1a of a spacer substrate ST1 is covered with an adhesive tape ATP, the spacer substrate ST1 can be held by a second suction table VT2 regardless of the through hole ST1a.
[Selection] Figure 4

Description

  The present invention relates to a method for manufacturing a wafer scale lens module suitable for mass production.

  Compact and thin imaging devices are now installed in portable terminals that are compact and thin electronic devices such as mobile phones and PDAs (Persona1 Digital1 Assistants), which enables not only audio information but also image information to remote locations. Can also be transmitted to each other.

  As an image pickup element used in these image pickup apparatuses, a solid-state image pickup element such as a CCD type image sensor or a CMOS type image sensor is used. In recent years, the number of pixels of an image sensor has been increased, and higher resolution and higher performance have been achieved. Further, as a lens for forming a subject image on these image pickup elements, a lens formed of a resin suitable for mass production has been used for further cost reduction. In particular, a lens made of resin has good workability and can meet the demand for higher performance by adopting an aspherical shape.

  As an imaging lens used in such an imaging device built in a portable terminal, a type having a configuration with three plastic lenses and an optical system having a configuration with three glass lenses, one glass lens and two plastic lenses are generally well known. It has been. However, as demands for further downsizing of these imaging lenses and mass productivity required for portable terminals are becoming stricter, it is becoming more difficult to achieve both.

  In order to overcome such problems, a large number of lens elements are simultaneously formed on a glass substrate of several inches which is a parallel plate by a replica method, and a glass substrate (lens wafer) on which a large number of these lens elements are formed is used as a sensor wafer. A method of mass-producing lens modules by combining them with each other has been proposed. A lens manufactured by such a manufacturing method is called a wafer scale lens, and a lens module is called a wafer scale lens module.

  As a method for manufacturing such a wafer scale lens, the one shown in Patent Document 1 has been proposed. According to the technique of Patent Document 1, for example, lenses for an imaging device mounted on a portable terminal can be mass-produced at low cost.

JP 2011-118423 A

  By the way, in order to improve the optical performance of the lens, the power is dispersed using a plurality of lenses. As a lens module corresponding to this, there is a lens module obtained by bonding a plurality of lens wafers and then cutting them. In such a lens module, a spacer substrate is used to maintain a predetermined interval between the lens wafers. Need to be placed. Since this spacer substrate has a through hole (portion through which subject light passes) corresponding to the lens portion formed on the lens wafer, the spacer substrate is sucked by a suction table provided with a suction groove while avoiding the through hole. Thus, the spacer substrate can be held and positioned with respect to the lens wafer.

On the other hand, when a large number of lenses are to be created from a single lens wafer in order to increase productivity, it is possible to create a larger number of lenses by keeping the pitch of lens portions formed on the lens wafer small. However, when the pitch is kept small in this way, the interval between the through holes of the spacer substrate is also narrowed, resulting in the following problems.
(A) It is necessary to make the suction groove narrow in order to avoid the current situation where the suction hole cannot interfere with the through hole, but in this case, the processing of the suction table becomes difficult and the cost increases.
(B) As the suction groove becomes thinner, the surface area and cross-sectional area decrease, and the force for holding the spacer substrate by suction decreases. Further, when the planar accuracy of the spacer substrate is poor, there is a possibility that it cannot be completely adsorbed.
(C) Furthermore, even if a thin suction groove can be created, high alignment accuracy is required for alignment of the spacer substrate and the suction table, and the through hole and the suction groove interfere with each other even if the position is slightly shifted. The risk of air leaks continues to occur.

  On the other hand, the suction groove of the suction table can be provided only around the spacer substrate. This is effective when the diameter of the lens wafer is small, but since the central region is not sucked, there is a possibility that the spacer substrate cannot be stably held when a lens wafer having a large diameter of about 8 to 12 inches is used. is there. On the other hand, in the case of using a large-diameter lens wafer, the central region of the spacer substrate can be adsorbed by eliminating the corresponding through-hole by eliminating the lens portion in the central region. Although the lens wafer is used, the number of lens modules that can be manufactured decreases and the yield deteriorates. Also, especially in the case of large-diameter wafers, the center area does not attract and the center area floats when the substrates are joined together, and the size of the product after cutting cannot be accurately manufactured. It is done.

  The present invention has been made in view of such a situation, and provides a lens module manufacturing method that can stably hold a spacer substrate and can manufacture a large number of lens modules while using a large transparent substrate. For the purpose.

The manufacturing method of the lens module according to claim 1,
Forming a plurality of lens portions on at least one of the surfaces of the transparent substrate;
Attaching a sheet-like member so as to cover at least a part of the through hole on one surface of the spacer substrate in which a plurality of through holes are formed;
A step of holding the spacer substrate by sucking a surface on which the sheet-like member on the sheet-like member side is attached by a suction table having a suction portion on the surface;
Moving the suction table relative to the transparent substrate to align the lens portion with the through hole;
Adhering the spacer substrate on the transparent substrate;
A step of simultaneously cutting the transparent substrate and the spacer substrate.

  According to the present invention, a sheet-like member is attached to one surface of a spacer substrate having a plurality of through-holes so as to cover the through-hole, and the sheet-like member is provided by a suction table having a suction portion on the surface. Since the spacer substrate is held by sucking the side, the spacer substrate can be held by the suction table regardless of the interval between the through holes. Thereby, since the surface area (for example, the groove width of the suction groove) of the suction part can be increased, the processing of the suction table becomes easy. Furthermore, since the surface area and cross-sectional area of the suction part can be increased, the suction force is increased and the holding force of the spacer substrate is increased. In addition, the permissible range for the relative displacement between the suction table and the spacer substrate is widened, and the time required for positioning is shortened.

  According to a second aspect of the present invention, there is provided a lens module manufacturing method according to the first aspect of the invention, wherein the plurality of transparent substrates on which the plurality of lens portions are formed are connected to each other through the spacer substrate. It is characterized by that. Thereby, the interval between the plurality of transparent substrates can be adjusted to a predetermined value.

  According to a third aspect of the present invention, in the lens module manufacturing method according to the first or second aspect, the sheet-like member is an adhesive tape. Therefore, the adhesive tape can be peeled off as necessary during or after the manufacturing of the lens module.

  According to a fourth aspect of the present invention, there is provided the lens module manufacturing method according to the first or second aspect, wherein the sheet-like member is a UV curable adhesive tape. Therefore, when the adhesive tape is peeled off during or after the production of the lens module, the adhesive tape can be easily peeled off by irradiating the tape with UV, and the lens module is not damaged.

  The method of manufacturing a lens module according to claim 5 is the invention according to any one of claims 1 to 4, wherein in the step of simultaneously cutting the transparent substrate and the spacer substrate, a dicing blade for cutting is used as the sheet. It is possible to reach the shaped member. Thereby, there is no possibility that the dicing blade may damage the mounting surface.

  According to a sixth aspect of the present invention, in the lens module manufacturing method according to the fifth aspect, the sheet-like member cut by the cutting dicing blade remains connected. Specifically, the sheet-like member is cut halfway through the dicing, and the dicing process is completed. Accordingly, the lens modules are surely cut individually, and the lens modules after cutting are not individually separated, and are easy to transport and manage.

  The method for manufacturing a lens module according to claim 7 is the invention according to any one of claims 1 to 6, wherein the spacer substrate is bonded to the transparent substrate using a UV curable adhesive. Features. This facilitates adhesion.

The method for manufacturing a lens module according to claim 8 is the invention according to any one of claims 1 to 7, wherein an interval Δ between the adjacent lens portions in the transparent substrate satisfies the following expression. And
0.5mm ≦ Δ ≦ 1.0mm (1)

  A large number of lens modules can be formed from a single transparent substrate because the value of equation (1) is equal to or less than the upper limit. On the other hand, if the value of the formula (1) is equal to or higher than the lower limit value, it can be easily cut with a dicing blade.

  The method for manufacturing a lens module according to claim 9 is the invention according to any one of claims 1 to 8, wherein the spacer substrate is formed on a surface on the side where the sheet-like member is attached, from the thickness of the sheet-like member. It has the convex part which protruded with the small protrusion amount, It is characterized by the above-mentioned. Thereby, when the said sheet-like member is attached so that the said convex part may be covered, the back surface side becomes flat and there is little possibility of preventing the adsorption | suction by an adsorption | suction table.

  According to a tenth aspect of the present invention, in the lens module manufacturing method according to any one of the first to ninth aspects, the lens portion is made of resin. Thereby, a lot of lens parts can be formed at once using a metallic mold.

  The method of manufacturing a lens module according to claim 11 is the invention according to any one of claims 1 to 10, wherein the diameter of the through hole is larger than the diameter of the optical surface of the lens portion viewed from the optical axis direction. It is characterized by that. Thereby, interference with the said through hole and the said optical surface can be avoided.

  ADVANTAGE OF THE INVENTION According to this invention, while using a large sized transparent substrate, the spacer substrate can be hold | maintained stably and the manufacturing method of the lens module which can manufacture a lens module in large quantities can be provided.

It is a perspective view of imaging device LU concerning this embodiment. It is sectional drawing which cut | disconnected the structure of FIG. 1 by the arrow II-II line | wire, and looked at the arrow direction. 1 is a diagram showing a mobile phone T. FIG. It is a figure which shows an example of the manufacturing process of an imaging lens. It is a figure which shows an example of the manufacturing process of an imaging lens. It is a figure which shows another example of an intermediate product. It is a figure which shows another example of a spacer board | substrate.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of an imaging apparatus LU according to the present embodiment, and FIG. 2 is a cross-sectional view of the configuration of FIG. 1 taken along line II-II and viewed in the direction of the arrow. As illustrated in FIG. 2, the imaging device LU includes a CMOS image sensor IM as a solid-state imaging device having a photoelectric conversion unit IMa, and a lens that causes the photoelectric conversion unit (light receiving surface) IMa of the image sensor IM to capture a subject image. The imaging lens LN as a module and an external connection terminal (electrode) (not shown) for transmitting and receiving the electrical signal are provided, and these are integrally formed.

  The imaging lens LN includes a wafer lens WL1 and a wafer lens WL2 in order from the object side (upper side in FIG. 2). The wafer lens WL1 includes a glass transparent substrate TP1 and a resin lens portion L1. The wafer lens WL2 includes a glass transparent substrate TP2 and a resin lens portion L2.

  In the image sensor IM, a photoelectric conversion unit IMa as a light receiving unit in which pixels (photoelectric conversion elements) are two-dimensionally arranged is formed in the center of a plane on the light receiving side, and signal processing (not shown) is performed. Connected to the circuit. Such a signal processing circuit includes a drive circuit unit that sequentially drives each pixel to obtain a signal charge, an A / D conversion unit that converts each signal charge into a digital signal, and a signal that forms an image signal output using the digital signal. It consists of a processing unit and the like. A number of pads (not shown) are arranged near the outer edge of the light receiving side plane of the image sensor IM, and are connected to the image sensor IM via wires (not shown). The image sensor IM converts a signal charge from the photoelectric conversion unit IMa into an image signal such as a digital YUV signal and outputs the image signal to a predetermined circuit via a wire (not shown). Here, Y is a luminance signal, U (= R−Y) is a color difference signal between red and the luminance signal, and V (= BY) is a color difference signal between blue and the luminance signal. Note that the solid-state imaging device is not limited to the CMOS image sensor, and other devices such as a CCD may be used.

  The image sensor IM is connected to an external circuit (for example, a control circuit included in a host device of a portable terminal mounted with an imaging device) via an external connection terminal, and a voltage or a clock for driving the image sensor IM from the external circuit. It is possible to receive a signal and to output a digital YUV signal to an external circuit.

  The upper part of the image sensor IM is sealed with a cover glass CG. Above the cover glass CG (on the object side), a parallel plate-shaped IR cut filter F is provided with a spacer SP3 interposed therebetween, and above the spacer lens SP2, the wafer lens WL2 is disposed at a predetermined distance. The transparent substrate TP2 of the wafer lens WL1 is fixed above the transparent substrate TP2 with a spacer SP1 interposed therebetween.

  The outside of these wafer lenses WL1, WL2 is covered with a housing BX, and the lower end of the housing BX is in contact with the cover glass CG. An opening formed in the upper flange BXa of the housing BX constitutes a diaphragm S.

  Next, a mobile phone as an example of a mobile terminal equipped with an imaging device will be described with reference to the external view of FIG. 3A is a view of the folded mobile phone opened from the inside and FIG. 3B is a view of the folded mobile phone opened from the outside.

  In FIG. 3, in the mobile phone T, an upper housing 71 as a case having display screens D <b> 1 and D <b> 2 and a lower housing 72 having operation buttons B are connected via a hinge 73. In the present embodiment, the main imaging device MC for photographing a landscape or the like is provided on the surface side of the upper housing 71, and the imaging device LU including the above-described wide-angle imaging lens LN is the upper housing 71. And provided on the display screen D1.

  As shown in FIG. 3A, the imaging lens LN can capture an image of the upper body of the user who holds the mobile phone T with his / her hand, with the imaging device LU facing the imaging device LU. By transmitting the image signal to the mobile phone of the other party that is communicating and displaying the image of this user, a so-called videophone can be realized by making a normal call. The mobile phone T is not limited to a folding type.

Next, the manufacturing process of the imaging lens LN will be described. 4 and 5 are diagrams showing manufacturing steps of the imaging lens LN. First, as shown in FIG. 4 (a), a transparent first suction table VT1 having a plurality of suction grooves VT1a (a suction portion connected to an external vacuum source, but may be a hole) on the upper surface is provided with glass. A transparent substrate TP1 that is a parallel plate made of glass is adsorbed. Next, a mold MD having a plurality of optical surface transfer surfaces MDa arranged in a matrix is brought into close contact with the surface of the transparent substrate TP1, and a molten resin is supplied into the formed cavity from the outside to be solidified. When the mold MD is separated, a plurality of lens portions L1 are formed on the transparent substrate TP1. At this time, an interval Δ between adjacent lens portions L1 in the transparent substrate TP1 satisfies the following expression.
0.5mm ≦ Δ ≦ 1.0mm (1)

  The thickness of the transparent substrate TP1, which is a glass parallel plate, is preferably, for example, from 0.1 mm to 1.5 mm. If it becomes thinner than this, cracks are likely to occur in the substrate, making it difficult to transport during production. In addition, the cost increases. On the other hand, if the thickness exceeds this value, the thickness becomes too large, the overall size becomes large, and the purpose of miniaturization cannot be achieved. The size of the glass wafer is preferably 4 to 12 inches. If it is too small, the number of imaging lenses that can be taken from one glass wafer will be too small to contribute to cost reduction. Conversely, if it is too large, the flatness of the lens cannot be maintained.

  In parallel with this, as shown in FIG. 4B, a sheet is formed on the spacer substrate ST1 which is a parallel plate made of glass or resin in which a plurality of through holes ST1a are formed in a matrix corresponding to the lens portion L1. Adhesive tape ATP as a member is affixed. For adhesive tape ATP, if the adhesive strength is too strong, it is difficult to remove the tape after the completion of the adhesion process, and in some cases, the spacer substrate may be damaged. After peeling, the adhesive component remains on the spacer substrate side. It can happen. On the other hand, if the adhesive force is too weak, when the adhesive tape ATP is adsorbed by the adsorption table, the adhesive tape ATP is peeled off from the spacer substrate only at the adsorbing groove portion, which causes a problem that the spacer substrate cannot be fixed to the vacuum table. Therefore, for example, trade name Y-9390 (polyester tape, thickness 50 μ, pressure-sensitive adhesive acrylic, adhesive strength 3.9 N / cm) manufactured by 3M Company is preferably used. Note that the adhesive tape ATP is a UV curable adhesive tape having a so-called UV peelability that is easily peeled off when irradiated with UV light. When UV light is applied to adhere to the spacer substrate ST1, the adhesive tape ATP is also easily peeled off, which is preferable because workability is improved. On the other hand, in the case where the adhesive tape TP is left attached until cutting, it is desirable that it does not have UV peelability. The plurality of through holes ST1a in a parallel plate made of glass or resin in which a plurality of through holes ST1a are formed in a matrix shape can be created by other blasting or the like created by edging, and the inner diameter of the through hole ST1a corresponds to the corresponding lens. It is larger than the outer diameter of the optical surface of the part.

  Thereafter, as shown in FIG. 4C, the spacer substrate ST1 is placed on the second suction table VT2 having a plurality of suction grooves VT2a (a suction portion connected to an external vacuum source, but may be a hole) on the lower surface. The adhesive tape ATP side (surface on which the sheet-like member is attached) is adsorbed. Since all the through holes ST1a of the spacer substrate ST1 are covered with the adhesive tape ATP, the spacer substrate ST1 can be held by the second suction table VT2 regardless of the through holes STa.

  Next, from the adhesive supply part FED shown in FIG.4 (d), UV curable resin UVB as an adhesive agent is dripped between the some lens parts L1 on the transparent substrate TP1 (refer FIG.4 (e)). ). In addition, you may adhere | attach using a thermosetting resin instead of UV curable resin UVB.

  After that, as shown in FIG. 5A, the second suction table VT2 is moved three-dimensionally to approach the first suction table VT1, and the lens portion L1 of the transparent substrate TP1 and the spacer substrate ST1 pass through. The hole ST1a is aligned. In this state, the spacer substrate ST1 is bonded to the transparent substrate TP1 by irradiating UV light from below the first suction table VT1 to cure the UV curable resin UVB. This is designated as a first intermediate product MX1. At this time, the suction of the second suction table VT2 is stopped and separated. The first intermediate product MX1 remains adsorbed and held on the first adsorption table VT1 (the first adsorption table VT1 is not shown in FIGS. 5B and 5C).

  Next, as shown in FIG. 5B, the adhesive tape ATP is peeled off from the spacer substrate ST1. Thereafter, in FIG. 5C, the first adsorption table VT1 is inverted together with the first intermediate product MX1.

  Furthermore, the second intermediate product MX2 formed by bonding the transparent substrate TP2 and the spacer substrate ST2 is manufactured through the same process as described above. The second intermediate product MX2 is left without removing the adhesive tape ATP from the spacer substrate ST2. Thereafter, as shown in FIG. 5 (d), the first intermediate product MX1 is bonded onto the second intermediate product MX2 by positioning the optical axes of the opposing lens portions. The body MX3 is manufactured. In such a state, the spacer substrate ST1 is interposed between the two transparent substrates TP1 and TP2.

  With respect to the third intermediate product MX3, the imaging lens LN can be manufactured by simultaneously cutting the first intermediate product MX1 and the second intermediate product MX2 between the lens portions by the dicing blade DB. At this time, the second intermediate product MX2 was cut by cutting with the adhesive tape ATP remaining (that is, the cutting edge of the dicing blade did not reach the suction table or the like that sucks the lower surface of the adhesive tape ATP). The individual imaging lenses LN are not separated apart and remain connected via the remaining adhesive tape ATP, which is advantageous in terms of conveyance and management. However, you may cut | disconnect so that it may isolate | separate completely. Thus, the imaging lens LN as a lens module is completed, and can be assembled to the housing BX as shown in FIG. At this time, the spacer substrates ST1 and ST2 cut at the same time function as the spacers SP1 and SP2.

  The inventors examined the optimum value by changing the distance Δ (mm) between the lens portions. The examination results are shown in Table 1. In Table 1, it was found that when Δ = 0.3 mm, interference with the dicing blade may occur. On the other hand, it was found that when Δ = 1.3 mm, the number of lens modules that can be manufactured from one wafer is reduced. Therefore, it can be said that the range of Δ is preferably 0.5 to 1.0 mm.

  In addition, as intermediate product MX3, as shown in FIG. 6, lens portions L1 to L4 provided on both sides of transparent substrates TP1 and TP2 may be used. This is preferable because the number of optical surfaces of the imaging lens increases and power can be dispersed. In this case, spacer substrates (one may be removed after manufacture) are required on both sides of the transparent substrate.

  FIG. 7 is an enlarged view of a spacer substrate according to a modified example. The spacer substrate ST has, for example, minute projections SPb between the through holes SPa for maintaining a distance from the cover glass CG or the like. In this case, if the protruding amount p of the convex portion SPb is smaller than the thickness t of the adhesive tape ATP, when the adhesive tape ATP is pasted so as to cover the convex portion SPb, the back side becomes flat and depends on the suction table. Less likely to interfere with adsorption.

DB Dicing blade FED Adhesive supply unit L1 Lens unit L2 Lens unit LN Imaging lens LU Sub imaging device MC Main imaging device MD Mold MDa Optical surface transfer surface MX1 First intermediate product MX2 Second intermediate product MX3 Third Intermediate product SP1 Spacer SP2 Spacer SP3 Spacer SPa Through hole SPb Protrusion ST1 Spacer substrate ST1a Through hole ST2 Spacer substrate ATP Adhesive tape TP1 Transparent substrate TP2 Transparent substrate UVB Curable resin VT1 First adsorption table VT1a Adsorption groove VT2 Second adsorption table VT2a Adsorption groove WL1 Wafer lens WL2 Wafer lens

Claims (11)

Forming a plurality of lens portions on at least one of the surfaces of the transparent substrate;
Attaching a sheet-like member so as to cover at least a part of the through hole on one surface of the spacer substrate in which a plurality of through holes are formed;
A step of holding the spacer substrate by sucking a surface on which the sheet-like member on the sheet-like member side is attached by a suction table having a suction portion on the surface;
Moving the suction table relative to the transparent substrate to align the lens portion with the through hole;
Adhering the spacer substrate on the transparent substrate;
And a step of simultaneously cutting the transparent substrate and the spacer substrate.   2. The method of manufacturing a lens module according to claim 1, further comprising a step of connecting a plurality of transparent substrates on which the plurality of lens portions are formed, with the spacer substrate interposed therebetween.   The method for manufacturing a lens module according to claim 1, wherein the sheet-like member is an adhesive tape.   The method for manufacturing a lens module according to claim 1, wherein the sheet-like member is a UV curable adhesive tape.   5. The method for manufacturing a lens module according to claim 1, wherein in the step of simultaneously cutting the transparent substrate and the spacer substrate, a cutting dicing blade is caused to reach the sheet-like member.   The lens module manufacturing method according to claim 5, wherein the sheet-like member cut by the cutting dicing blade remains connected.   The method of manufacturing a lens module according to claim 1, wherein the spacer substrate is bonded onto the transparent substrate using a UV curable adhesive. The lens module manufacturing method according to claim 1, wherein an interval Δ between adjacent lens portions in the transparent substrate satisfies the following expression.
0.5mm ≦ Δ ≦ 1.0mm (1)   The lens according to any one of claims 1 to 8, wherein the spacer substrate has a convex portion projecting with a projecting amount smaller than a thickness of the sheet-like member on a surface to which the sheet-like member is attached. Module manufacturing method.   The method for manufacturing a lens module according to claim 1, wherein the lens portion is made of resin.   11. The method of manufacturing a lens module according to claim 1, wherein a diameter of the through hole is larger than a diameter viewed from an optical axis direction of an optical surface of the lens unit.