Image sensor unit, optical unit and method for manufacturing an image sensor unit

Abstract

The invention relates to an image sensor unit (10) comprising an image sensor (12) and a protective glass (14), wherein the protective glass (14) covers a light-sensitive area of ​​the image sensor (12), and wherein the protective glass (14) is connected to the image sensor (12) by means of a pressure-sensitive adhesive (16). The invention further relates to an optical unit comprising an image sensor unit (10) and a method for manufacturing an image sensor unit (10).

Description

State of the art The invention relates to an image sensor unit, an optical unit and a method for manufacturing an image sensor unit. WO 2006 / 128 765 A1 discloses a method for manufacturing an optical system in which at least one optical element having a dust protection function is arranged in front of a light-sensitive surface of an image sensor via a deformable sealing element. Disclosure of the invention Advantages of the invention The image sensor unit according to the invention, comprising an image sensor and a protective glass, wherein the protective glass covers a light-sensitive area of ​​the image sensor and is connected to the image sensor by means of a pressure-sensitive adhesive, has the advantage that the assembly of the image sensor unit is simplified by directly fixing the protective glass after the assembly process. Furthermore, no curing times are necessary, since a high initial adhesion is already present during assembly. In addition, the protective glass is supported over its entire surface during assembly, so that it cannot tilt. A further advantage is the high robustness of the process chain in the manufacture of the image sensor unit, resulting in a low reject rate. It is particularly advantageous that the pressure-sensitive adhesive is arranged between the image sensor and the protective glass. Pressure-sensitive adhesives (PSAs) exhibit pronounced initial adhesion in the form of tackiness and / or stickiness. Furthermore, pressure and time increase the adhesion to the component being bonded. Elevated process and / or ambient temperatures can accelerate this adhesion development. Preferably, the pressure-sensitive adhesives are designed as follows: - A single-sided, pressure-sensitive adhesive tape in which a carrier material is coated with an adhesive. The single-sided adhesive tape has adhesive properties on one side. The other side of the carrier is tack-free. - A pressure-sensitive transfer adhesive tape consists of a pure adhesive layer. A liner is applied to one side for handling. Preferably, the other side of the adhesive layer is covered by a removable protective film.The liner and protective film are removed during the application process to a component surface. - A double-sided, pressure-sensitive adhesive tape has a carrier (backing material). The carrier is coated on both sides with the same or different pressure-sensitive adhesive compounds. Handling is similar to transfer tape, except that the carrier remains in the adhesive bond. The double-sided adhesive tape is covered on both adhesive sides with protective films, which are removed before application to a component surface. - Reactive, pressure-sensitive adhesives also exhibit high initial tack and are processed similarly to pressure-sensitive adhesives.In addition to pressure-sensitive adhesives, these include a chemical composition that causes the adhesive to further crosslink within the adhesive bond before and / or after the joining process through a suitable curing and / or activation step, for example, thermal energy input as post-curing and / or irradiation with a suitable UV light source as activation, so that a bonding layer with higher crosslinking is formed. After crosslinking, the bonding layer preferably exhibits elastomeric or thermosetting properties. An advantageous feature is an image sensor unit in which the pressure-sensitive adhesive is applied across the entire surface between the image sensor and the protective glass. This full-surface bonding ensures particularly strong adhesion between the protective glass and the image sensor. In this variant, the pressure-sensitive adhesive is preferably an optically clear, highly transparent, pressure-sensitive adhesive. A further advantage is that the pressure-sensitive adhesive also functions as an optical filter, for example, by containing additives with optical filter properties, such as those for filtering infrared light. Alternatively or additionally, the pressure-sensitive adhesive is formulated with a UV blocker additive. The pressure-sensitive adhesive with the UV blocker additive is designed to prevent glare and reflections and / or to filter out light in the UV wavelength range.Alternatively or additionally, the optical path of the overall system is adjusted and / or influenced using the pressure-sensitive adhesive via defined optical properties of the adhesive, for example by a predetermined refractive index. A particularly advantageous image sensor unit is one in which the pressure-sensitive adhesive is arranged in a frame-like fashion, surrounding the light-sensitive area of ​​the image sensor, between the image sensor and the protective glass. This saves adhesive material and is therefore cost-effective. A further advantage is that less expensive pressure-sensitive adhesives without special optical properties can be used. Furthermore, an image sensor unit is advantageous in which the image sensor and the protective glass are encapsulated with a potting compound. Preferably, the protective glass is not covered by the potting compound. This has the advantage that, in particular, the image sensor and the connecting wires, such as bond wires, are protected from mechanical influences and environmental stresses. Furthermore, an image sensor unit in which the pressure-sensitive adhesive has predetermined optical refractive properties is particularly advantageous. By using a pressure-sensitive adhesive for surface fixation, the optical path of the overall system can be advantageously influenced and / or modified by ensuring that the adhesive has predetermined and / or specially adapted optical refractive properties. The invention further relates to an optical unit comprising the described image sensor unit. Preferably, the optical unit is configured as a camera and / or a LiDAR unit. The use of the invention in a camera as a driver assistance camera, as an interior camera, and / or as a reversing camera in a motor vehicle is particularly advantageous. Furthermore, the invention relates to a method for manufacturing an image sensor unit, in particular the described image sensor unit, comprising the steps of: - providing an image sensor and a protective glass, - applying a pressure-sensitive adhesive to the image sensor and / or to the protective glass, - arranging the image sensor to the protective glass such that the pressure-sensitive adhesive is arranged between the image sensor and the protective glass, - preferably conditioning the pressure-sensitive adhesive, and - pressing the image sensor and the protective glass together. Protective lenses consist of or comprise glass, for example borosilicate glass, quartz glass, crown glass and / or flint glass, and / or consist of or comprise transparent plastics, for example PMMA (polymethyl methacrylate), PC (polycarbonate), PET (polyethylene terephthalate) and / or PE (polyethylene), which in particular meet the predetermined optical properties. The pressure-sensitive adhesive consists of or comprises, for example, acrylate adhesives, particularly highly transparent acrylate adhesives. Preferably, the pressure-sensitive adhesive has a transmission greater than 90%, preferably greater than 95%. In particular, the pressure-sensitive adhesive is designed to be non-yellowing over the long term. In particular, the pressure-sensitive adhesive is bubble-free. Alternatively or additionally, the pressure-sensitive adhesive consists of or comprises silicone adhesives. In the optional process step of conditioning the pressure-sensitive adhesive before, during, or after pressing the image sensor and protective glass together, air bubbles are removed and / or prevented. This conditioning step is preferably carried out at an elevated temperature and / or pressure, particularly using an autoclave. This has the advantage of improving image quality. A method is advantageous in which the pressure-sensitive adhesive is applied over the entire surface of the image sensor and / or the protective glass in such a way that, after joining, the pressure-sensitive adhesive is located between the image sensor and the protective glass, and / or In which the pressure-sensitive adhesive is applied in a frame-like manner, surrounding a light-sensitive area of ​​the image sensor, to the image sensor and / or to the protective glass in such a way that the pressure-sensitive adhesive is located between the image sensor and the protective glass after joining. Furthermore, an image sensor unit or a method is advantageous in which the pressure-sensitive adhesive is designed in the form of a pressure-sensitive adhesive tape, in particular in the form of a pressure-sensitive transfer adhesive tape and / or a pressure-sensitive double-sided adhesive tape and / or as a reactive pressure-sensitive adhesive. The advantages described with reference to the image sensor unit apply accordingly to the optical unit and to the method for manufacturing the image sensor unit. Further advantages will result from the following description of exemplary embodiments with reference to the figures and from the dependent claims. Brief description of the drawings Exemplary embodiments of the invention are illustrated in the drawings with reference to several figures and are explained in more detail in the following description. Figure 1 shows an image sensor unit of a first embodiment, Figure 2 shows a top view of the image sensor unit of the first embodiment in a first variant, Figure 3 shows a top view of the image sensor unit of the first embodiment in a second variant, Figure 4 shows an image sensor unit of a second embodiment, Figure 5 shows an optical unit, and Figure 6 shows a method for manufacturing an image sensor unit. Description of exemplary implementations The following describes an image sensor unit comprising an image sensor and a protective glass, wherein the protective glass covers a light-sensitive area of ​​the image sensor and is connected to the image sensor by means of a pressure-sensitive adhesive. Furthermore, an optical unit comprising an image sensor unit and a method for manufacturing an image sensor unit is described. The protective glass is bonded to the image sensor using a full-surface or frame-shaped PSA adhesive tape (PSA: pressure-sensitive adhesive tape) by directly mounting the protective glass after the PSA tape has been applied. Preferably, the PSA adhesive tape is an OCA tape (optical clear adhesive) with particularly high transparency, ensuring that the suitable optical properties are maintained throughout the tape's service life. Preferably, after assembly, the protective glass and image sensor are encapsulated in a package. Fig. 1 shows an image sensor unit 10 of a first embodiment. The image sensor unit 10 comprises an image sensor 12 and a protective glass 14, the protective glass 14 covering a light-sensitive area 26 of the image sensor 12. The image sensor unit 10 also includes a pressure-sensitive adhesive 16. The pressure-sensitive adhesive 16 bonds the protective glass 14 to the image sensor 12. The pressure-sensitive adhesive 16 is arranged between the image sensor 12 and the protective glass 14. Furthermore, the image sensor unit 10 includes bond pads 18 and / or bond balls and bond wires 20 by means of which the image sensor 12 is electrically and data-wise contacted with a circuit board (not shown). Fig. 2 shows a top view of the image sensor unit 10 of the first embodiment in a first variant. In this first variant of the image sensor unit 10, the pressure-sensitive adhesive 16 is arranged over the entire surface between the image sensor 12 and the protective glass (not shown), which lies above the image sensor 12. The pressure-sensitive adhesive 16 completely covers the light-sensitive area 26 of the image sensor 12. Preferably, the pressure-sensitive adhesive 16 extends laterally beyond the light-sensitive area 26 of the image sensor 12 on all sides. Furthermore, Fig. 2 shows, as in Fig. 1, bond pads 18 and / or bond balls and bond wires 20 of the image sensor unit 10 by means of which the image sensor 12 is electrically and data-wise contacted with a circuit board (not shown). Fig. 3 shows a top view of the image sensor unit 10 of the first embodiment in a second variant. In this second variant of the image sensor unit 10, the pressure-sensitive adhesive 16 is arranged in a frame-like form between the image sensor 12 and the protective glass (not shown), which lies above the image sensor 12. The pressure-sensitive adhesive 16 surrounds the light-sensitive area 26 of the image sensor 12. In particular, the pressure-sensitive adhesive 16 does not touch the light-sensitive area 26 of the image sensor 12. A cavity, defined by the pressure-sensitive adhesive 16 and preferably filled with air, is formed between the light-sensitive area 26 of the image sensor 12 and the protective glass. The frame-like pressure-sensitive adhesive 16, which is formed in the shape of a rectangular contour, has rounded corners.Preferably, the frame-shaped contour of the pressure-sensitive adhesive 16 follows the contour of the light-sensitive area 26 of the image sensor 12. Furthermore, Fig. 3 shows, corresponding to Fig. 1, bond pads 18 and / or bond balls and bond wires 20 of the image sensor unit 10 by means of which the image sensor 12 is electrically and data-wise contacted with a circuit board not shown. Fig. 4 shows an image sensor unit 10 of a second embodiment. The image sensor unit 10 comprises an image sensor 12 and a protective glass 14, the protective glass 14 covering a light-sensitive area 26 of the image sensor 12. The image sensor unit 10 also includes a pressure-sensitive adhesive 16. The pressure-sensitive adhesive 16 bonds the protective glass 14 to the image sensor 12. The pressure-sensitive adhesive 16 is arranged between the image sensor 12 and the protective glass 14. The image sensor unit also includes a circuit board 22. In this embodiment, the circuit board 22 is multilayered. The image sensor 12, with the protective glass 14 and the pressure-sensitive adhesive 16, is mechanically connected to the circuit board via an adhesive 14. The image sensor unit 10 also includes bond wires 20 by means of which the image sensor 12 is electrically and data-wise contacted with the circuit board 22.The circuit board 22 further includes electrical vias for electrically connecting the bond wires 20 arranged on the upper side of the circuit board 22 to solder balls 19 on the underside of the circuit board 22. The image sensor unit 10 also includes a potting compound 28. The potting compound 28 encapsulates the image sensor 12 with the protective glass 14 to the circuit board 22 in such a way that the aforementioned components, in particular the bond wires 20, are protected from environmental influences. Fig. 5 shows an optical unit 30. The optical unit 30 comprises the image sensor unit 10 described above with reference to Figs. 1, 2, 3 to 4. Furthermore, the optical unit 30 comprises at least one lens 32 and a housing 34. The lens 32 is arranged in the housing 34 such that the lens 32 focuses ambient light onto the light-sensitive surface of the image sensor of the image sensor unit 10 via the protective glass. Preferably, the optical unit 30 is a camera and / or a LiDAR unit (LiDAR: Light Detection and Ranging). Fig. 6 shows a method for manufacturing an image sensor unit as described with reference to Figs. 1, 2, 3 to 4. In a first process step 40, an image sensor and a protective glass for the image sensor are provided. Preferably, the image sensor is a CMOS image sensor. In a second process step 42, a pressure-sensitive adhesive is applied to the image sensor. Alternatively or additionally, the pressure-sensitive adhesive is applied to the protective glass. In a first embodiment, the pressure-sensitive adhesive is applied over the entire surface of the image sensor and / or the protective glass. In a second embodiment, the pressure-sensitive adhesive is applied in a frame-like pattern surrounding the light-sensitive area of ​​the image sensor to the image sensor and / or the protective glass.For this purpose, the frame shape of the pressure-sensitive adhesive is pre-cut from a pressure-sensitive adhesive as a closed contour using a die-cutting tool and / or a laser cutter. In both variants, the pressure-sensitive adhesive is applied in such a way that, after assembly, it is located between the image sensor and the protective glass. In a third process step 44, the image sensor and the protective glass with the applied pressure-sensitive adhesive are positioned relative to each other such that the pressure-sensitive adhesive is located between the image sensor and the protective glass. In a fourth process step 46, the image sensor and the protective glass are pressed together by a predetermined pressure, so that an adhesive bond is created between the image sensor and the protective glass via the pressure-sensitive adhesive. In the described embodiments, the pressure-sensitive adhesive is designed as an optically clear, pressure-sensitive adhesive. Alternatively or additionally, the pressure-sensitive adhesive in the described embodiments is designed as an optical filter. Preferably, the pressure-sensitive adhesive comprises additives that exhibit and / or influence the optical filter properties. In the aforementioned embodiments, the pressure-sensitive adhesive is designed in the form of a pressure-sensitive adhesive tape, preferably in the form of a pressure-sensitive transfer tape without a carrier layer and / or as a pressure-sensitive, double-sided adhesive tape with or without a carrier layer. The use of the invention can be demonstrated on an image sensor unit by, for example, performing a metallographic section, a chemical analysis and / or a non-destructive testing procedure, such as a radiographic test.

Claims

Image sensor unit (10) comprising an image sensor (12) and a protective glass (14), wherein the protective glass (14) covers a light-sensitive area (26) of the image sensor (12), characterized in that the protective glass (14) is connected to the image sensor (12) by means of a pressure-sensitive adhesive (16). Image sensor unit (10) according to claim 1, characterized in that the pressure-sensitive adhesive (16) is arranged between the image sensor (12) and the protective glass (14). Image sensor unit (10) according to one of the preceding claims, characterized in that the pressure-sensitive adhesive (16) is arranged over the entire surface between the image sensor (12) and the protective glass (14). Image sensor unit (10) according to one of claims 1 or 2, characterized in that the pressure-sensitive adhesive (16) is arranged in a frame-like manner, surrounding the light-sensitive area (26) of the image sensor (12), between the image sensor (12) and the protective glass (14). Image sensor unit (10) according to one of the preceding claims, characterized in that the pressure-sensitive adhesive (16) is designed as an optically clear, in particular highly transparent, pressure-sensitive adhesive. Image sensor unit (10) according to one of the preceding claims, characterized in that the pressure-sensitive adhesive (16) is designed as an optical filter. Image sensor unit (10) according to one of the preceding claims, characterized in that the pressure-sensitive adhesive (16) has predetermined optical refractive properties. Image sensor unit (10) according to one of the preceding claims, characterized in that the image sensor (12) is encapsulated with the protective glass (14) by a potting compound (28). Optical unit (30) comprising an image sensor unit (10) according to one of the preceding claims. Optical unit (30) according to claim 9, characterized in that the optical unit (30) is designed as a camera and / or a LIDAR unit. Method for manufacturing an image sensor unit (10), in particular an image sensor unit (10) according to one of claims 1 to 8, comprising the steps: - providing an image sensor (12) and a protective glass (14), - applying a pressure-sensitive adhesive (16) to the image sensor (12) and / or to the protective glass (14), - arranging the image sensor (12) to the protective glass (14) such that the pressure-sensitive adhesive (16) is arranged between the image sensor (12) and the protective glass (14), and - pressing the image sensor (12) and the protective glass (14) together. The method according to claim 11, characterized in that the pressure-sensitive adhesive (16) is applied over the entire surface of the image sensor (12) and / or the protective glass (14) such that the pressure-sensitive adhesive (16) is located between the image sensor (12) and the protective glass (14) after assembly, and / or that the pressure-sensitive adhesive (16) is applied in a frame-like manner, surrounding a light-sensitive area (26) of the image sensor (12), to the image sensor (12) and / or to the protective glass (14) such that the pressure-sensitive adhesive (16) is located between the image sensor (12) and the protective glass (14) after assembly. Method according to one of the preceding claims 11 or 12, characterized in that the pressure-sensitive adhesive (16) is designed in the form of a pressure-sensitive adhesive tape, in particular in the form of a pressure-sensitive transfer adhesive tape and / or a pressure-sensitive double-sided adhesive tape and / or as a reactive pressure-sensitive adhesive (16). Method according to any of the preceding claims 11 to 13, characterized in that the pressure-sensitive adhesive (16) is conditioned after application.

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