JP2012129380A - Sensor configuration without housing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor which enables small production with low production cost and provides additive benefits obtained by loading the sensor to customers.SOLUTION: This invention relates to a manufacturing method of a housingless sensor, especially a manufacturing method of a proximity sensor. According to the manufacturing method, all components required for mechanical and electrical functions are assembled on a pedestal of one sensor. Then, a compound of resin is injected around the components.

Description

  The present invention relates to a method of manufacturing an electronic sensor, in particular a method of packaging a sensor, and a sensor manufactured by the method.

  In general, electronic sensors are used to quantitatively and / or qualitatively detect physical measurement variables from their environment, and the detected measurement variables are converted into electrical signals and transmitted for further processing. Is done. In principle, it is possible to distinguish between active and passive sensors, which comprise an additional primary electronics in addition to the actual transducer and are powered by external auxiliary energy. Examples of such electronic sensors include inductive proximity switches or capacitive proximity switches, magnetic sensors, optical sensors, light barriers, fiber optic sensors, inductive distances. Sensors (inductive distance sensors), triangulation distance sensors, and phase-measuring optical distance sensors are listed, but these are not exhaustive.

  In general, the technical configuration of such sensors comprises a rugged housing that includes a transducer and corresponding electronics on a printed circuit board, with the sensor electronics contacts being guided out through the housing. Possible sensor structures established on the market include sensors having both cylindrical and polygonal housing types. Typically, the housings are preassembled from metal or resin so that the transducers, sensor electronics, and contacts, for example in the form of cables or plug contacts, are in these housings. Can be installed. Typically, the sensor component installed in the housing is contained in a casting compound for protection from environmental influences and for mechanical stability of the sensor structure. Enclosed.

  Each transducer can be made from both individual electronic, electromechanical, or optoelectronic components, and groups assembled with electronic, mechanical, and / or optical components.

  Within the scope of the present invention, a polygonal sensor structure is usually understood as a sensor having a generally polyhedral housing body substantially having the shape of one block or several blocks nested together. . The corresponding polygonal structure is suitable in a particularly advantageous manner for assembling in a T-groove profile system, which is often found, for example, in the field of special mechanical structures. In principle, the polygonal sensor can also be mounted on any support element for the system or machine.

  A disadvantage compared to the cylindrical sensor structure is the complex machining of the polygonal sensor metal or resin housing, and the production of the polygonal sensor is relatively costly. Alternatively, the polygonal sensor housing may be produced from a zinc die-cast material, and the expensive housing problem is transferred to the expensive initial cost of the mold. The problem of high production costs for small volumes and limited flexibility remains in polygonal sensor structures.

  Another disadvantage of the polygonal sensor structure is that these sensors must be mounted on a flat surface of the machine or system housing with at least two mounting screws, which are cylindrically shaped. Represents increased complexity compared to sensors.

  So-called “housing-less” sensors have their electronic components in mechanical contact with each other, so that the electronic components are placed in an injection mold where they are fixed. ) Represents another structure in which electronic components can initially move relative to each other in a production process before being held in place by a fixing element. The plastic compound is then completely injection molded around the component, and the molded body is formed of the resin compound, the outer dimension of the body being that of the injection mold. Corresponds to internal dimensions.

  The disadvantage of this method is that individual components, such as sensor transducers, primary electronics and printed circuit boards with contacts, must be installed and fixed in a complex and accurate manner in the injection mold. It is not to be. Furthermore, these fasteners must be provided on the molded housingless body of the polygonal sensor so that the fasteners can be mounted in their use position. Fasteners constructed as threaded inserts, threaded through holes, or threaded struts, etc. must be installed and secured in the corresponding mold before being injection molded.

  The present invention is therefore based on the problem of disclosing sensors that can be produced at low production costs, especially in small quantities, and provide additional mounting benefits to the customer.

  This problem is solved by the subject matter of the method claims, which are independent claims, and by the associated device claims.

  Preferred and / or advantageous constructions and improvements are the subject matter of the corresponding dependent claims.

  The present invention includes a method for producing a sensor, and a molded body having a polygonal shape, for example, is formed by injecting a resin composite around a plurality of components, and the outer dimensions of the body. The dimensions correspond to the internal dimensions of the injection mold. In general, the components may be any optical, electronic, mechanical, and / or hybrid-integrated components required for each sensor's function and handling or assembly. In particular, these components include a transducer built for each measurement task. In the first step, the optical, electronic, and / or mechanical components of the sensor are mechanically secured to the top and / or back of the printed circuit board. In another step, the mounted printed circuit board is placed in an injection mold. Within the injection mold, the printed circuit board is held in a defined position relative to the wall of the injection mold by support fingers. The resin composition is then injected in a fluid state into an injection mold, whereby the printed circuit board with the components is at least partially injection molded at this fixed location.

  The transducer comprises a plurality of electronic, mechanical and / or optical components for its part corresponding to each measurement task, and thus for individual printed circuit board assemblies It is preferably constructed as a hybrid integrated component that forms the component.

  If necessary, it is desirable that the transducer is not covered with the resin composition or is not completely embedded in the resin composition. This may be the case, for example, for an optical sensor, where the beam path should not be realized through the molding compound to the optical sensor. To this end, an improvement of the present invention provides for embedding a conduit element in a resin composition that forms a conduit in the resin composition. The transducer is here arranged in a conduit. The conduit element is mounted on the circuit board prior to being molded with a resin composite, so that when viewed in a top view of the circuit board, the wall of the conduit surrounds the transducer. When injecting the resin, the resin composition does not penetrate or completely penetrate the interior of the conduit, so that the conduit remains free of resin composition or thereby injects. Later, a composite of resin surrounds the conduit formed by the conduit elements. For this purpose, the conduit element is generally mounted in a sealing manner on the circuit board, so that, during the injection molding, between the end of the conduit element facing the circuit board and the circuit board itself. It is preferable that the resin composition is prevented from penetrating. Other elements can then also be placed in the conduit. For example, the conduit may be closed with a window made of a suitable material or optical element for sealing.

  In a similar but different embodiment of the preferred or improved embodiment of the present invention, the optical sensor transducer comprises an optoelectronic component mechanically secured on a printed circuit board, and a lens carrier and at least An assembled lens unit with one lens can be provided. The lens carrier can be placed in the groove of the printed circuit board in an injection mold and at least partially injection molded. Here, advantageously, the lens carrier forms a conduit in the resin composition as described above.

  This two-part or multi-part structure of the optical converter allows the use of optoelectronic standard components, such as photodiodes and application specific optical elements, so that a special pre-assembled hybrid integrated configuration Elements can be eliminated.

  By holding the lens carrier during injection molding, the still fluid resin composition can penetrate between the printed circuit board and the optical element or between the optoelectronic component and the optical element, thereby The possibility of blocking the light beam path is prevented. The lens carrier is injection molded only around its side perpendicular to the printed circuit board, so that the outer side of the lens carrier faces away from the optoelectronic component and the body of the sensor molded with resin. It is preferable that sealing can be performed with substantially perfect overlap.

  In comparison with the prior art, the method according to the invention enables the production of “housing-less”, eg polygonal sensors, and usually the printed circuit board already required for primary electronics is simultaneously machined. It can be used as a chassis for a dynamic sensor structure, i.e. as a mounting platform.

  The mechanical component comprises at least one attachment element provided for attachment of the sensor. As such an attachment element, a threaded insert or a threaded sleeve may be clipped to the printed circuit board, and this insert or sleeve is completely or at least partially made of a resin composite in the injection molding process. Injection molded. Thus, a non-positive-fit connection and a positive-fit connection are created between the mounting element and the molded sensor body, so that during sensor assembly Is absorbed in the molded body and optimally distributed.

  Electronic and mechanical components can be installed on printed circuit boards with pick-and-place techniques common in electronics, and in typical attachment processes such as clipping, bonding, and / or soldering The ability to be fixed on a printed circuit board is particularly advantageous. Thus, the sensor pedestal can be mounted using all of the components in a conventional automatic pick-and-place device.

  One particularly advantageous improvement of the present invention is a printed circuit board panel comprising a plurality, usually the same printed circuit board, which are simultaneously injection molded in an injection mold to form a panel having a composite of resins. It is. Using a full or half circuit-board-plate panel as a mounting platform, a corresponding number of sensors are provided simultaneously, for example with a polygonal injection molded housing Can be done. The individual sensors are then disconnected from the printed circuit board panel.

  Another structure of the present invention provides that the circuit board of each mounted sensor is injection molded with a composite of transparent or translucent resin. It is therefore possible to apply labeling to the sensor, for example type and / or connection markings, directly on the printed circuit board, which remains visible through the body of the transparent molded sensor. Thus, in a particularly advantageous manner, additional labeling printing on the surface of the molded body can be eliminated.

  Similarly, the present invention includes a housingless, eg polygonal sensor that can be produced by the method according to the present invention. Such a sensor comprises a printed circuit board with mechanical and electronic components mounted on its top and / or back, the printed circuit board and mechanical components being surrounded by a molded body made of resin. The molded body can have, for example, a polygonal shape in one refinement of the invention. Thus, for example, for inductive proximity sensors, all of the components including the transducer constructed as a coil are placed directly on a flat printed circuit board.

  At least one mounting element is provided in the mechanical component on the printed circuit board, which can be constructed as a threaded insert.

  Many sensor structures, especially polygonal shaped structures, should usually have at least two screw connections, with each sensor housing being mounted on a machine or system part. Preferably, an additional alignment pin used for accurate positioning of the sensor is provided on the mounting surface / back surface of the molded sensor body according to the invention, whereby a second screw for mounting Connections can be eliminated. Thus, for the customer, only one borehole is required on the machine or system. The alignment pins are preferably constructed so that they can be easily broken and removed or detached during assembly and easily removed.

  As an alternative to a threaded insert, the sensor can be constructed with a threaded sleeve on its back that can be used as a sensor attachment while at the same time providing an electrical connection. The sensor connection can thus be transmitted into a protected part of the machine or system in a particularly advantageous manner.

  In a preferred embodiment, the molded sensor body is constructed of a transparent or translucent resin. Therefore, the sensor can be labeled on the printed circuit board and need not be applied to the surface of the molded body in an extra step. In addition, light emitting diodes or other display elements may be arranged and used as a functional indication of the sensor. The display element may be installed mechanically during the production of the sensor and can be viewed at a wide angle through the body of the molded sensor, transparent or translucent, without additional components such as optical fiber or transparent coating it can.

  These and other features of the invention, as well as other related advantages, result from the following detailed description of the preferred embodiments in connection with the accompanying drawings. What is shown in the drawings is as follows.

FIG. 3 shows a housingless inductive proximity sensor having a polygonal housing and an encapsulated threaded insert. FIG. 4 shows a housingless inductive proximity sensor having a polygonal housing and a threaded sleeve disposed on the back. FIG. 3 is a diagram illustrating a housingless optical proximity sensor having a polygonal housing and an optical converter.

  FIG. 1 shows an inductive proximity sensor in a polygonal sensor structure with a threaded insert that is used to mount the sensor in place for use. Further, instead of the screw-type insert, a screwless through hole for screw connection or rivet connection may be provided at this position.

  The sensor 1 comprises a printed circuit board 2 mounted by hand or preferably with an automatic pick-and-place system, and the components may be placed on both the top surface 3 and the back surface 4 of the printed circuit board 2. . The surface of the printed circuit board, in this example, is a typical track for the contacts of the transducer 5 which substantially comprises a coil for the connection cable 6 and a light emitting diode 7 not explicitly shown in the figure. ) Conductor.

  In addition to the typical contact holes in the printed circuit board that can be used to make contacts for the coil 5 and the connecting cable 6, the printed circuit board includes an additional assembly opening through the opening. Or in the opening, different components can be guided and mounted using an expanding rivet connection. Relevant components can be additionally or alternatively mounted on the printed circuit board with adhesive or solder connections.

  The threaded insert 8 is guided through an opening in the printed circuit board and is later used to accommodate mounting screws for assembling the sensor. The threaded insert may have a one-part or two-part structure and may be clipped, riveted, glued and / or soldered to the printed circuit board. Furthermore, although not shown in detail, a tension-reducing device for the connecting cable 6 may be integrated into the screw-type insert 8. If necessary, the connecting cable 6 can also be fixed on the printed circuit board with an additional clamping device, also not shown.

  The printed circuit board is sealed with a resin molded body 9 which can be produced in an injection molding process. Here, the connecting cable 6 is guided through one end face out of the substantially block-shaped molded body 9.

  The upper surface 11 of the molded body 9 has a greater distance to the printed circuit board in order to completely seal the coil in the region of the coil 5 built upward. The threaded insert 8 forms a coplanar seal with the surfaces of the upper and lower surfaces 11 and 12 of the molded body 9.

  Additional alignment pins 10 are provided on the back surface 12 of the molded body 9 that can be used to accurately position the sensor during sensor assembly. The alignment pin 10 is constructed so that it can be easily removed if it is not needed by breaking or cutting it off.

  The molded body 9 has recesses 13 on its upper surface 11 and its lower surface 12 in which the printed circuit board 2 is held by support fingers of an injection mold during injection molding.

  The light-emitting diode 7 provided on the back of the printed circuit board can be easily seen even from the top through the transparent or translucent molded body of the sensor.

  In addition to the coil for the inductive proximity sensor, the sensor shown in the figure can also comprise an electrode arrangement, for example as a transducer 5 in which a capacitive proximity sensor can be realized.

  FIG. 2 shows another embodiment of the inductive proximity sensor, the basic structure of which is substantially the same as the sensor described above.

  A substantial difference exists in the means for mounting the sensor, in which case this means is provided as a mounting sleeve 14 on the lower surface 12 of the molded body 9.

  The mounting sleeve 14 is provided with two locking pegs 15 which are guided from the back side 4 through the printed circuit board 2 and through corresponding openings. The electrical connection of the sensor is preferably provided by a mounting sleeve 14, for example a connection cable is guided through the interior of the mounting sleeve 14. Alternatively, plug contacts may also be provided in the mounting sleeve 14. The electrical connection of the upper surface 3 of the circuit board 2 to the conductors of the conductive path, not shown in detail, is guided from the back side 4 through the printed circuit board through the corresponding contact holes, and in the upper surface 3 the conductor of the conductive path Provided by contact legs 16 which are soldered to the surface.

  This construction is particularly advantageous for guiding the sensor connection through the housing wall into the protected machine part.

  FIG. 3 illustrates another embodiment of the present invention and illustrates an optical sensor.

  In turn, the sensor 1 comprises a printed circuit board 2 on which a transducer 5 and other mechanical and electrical components, which are also not shown in detail, are mounted. To mount such a sensor, both a threaded insert 8 and a mounting sleeve 14 as shown in FIGS. 1 and 2 may be used.

  The converter 5 comprises, for example, a photodiode 17 or other optoelectronic component that is soldered onto the printed circuit board 2. The electrical contact of the photodiode 17 is preferably realized via the back surface 4 of the printed circuit board 2 and is not shown in the drawing and is known to those skilled in the art of printed circuit board technology. contact) is used.

  The transducer also comprises a lens unit that includes a lens carrier 18 and at least one lens 19. The lens carrier has the shape of a tube and, after injecting the resin, is embedded in a resin composite to define a conduit 180, the inner wall of which surrounds the transducer. Thus, the lens unit represents an assembled optical component that is placed in the groove 20 on the printed circuit board 2 above the photodiode 17 before injection molding.

  With corresponding support points in an injection mold not shown, the groove 20 ensures that the lens unit is mechanically sufficiently fixed. Adequate sealing is ensured through the appropriate contact pressure, thus preventing the resin composition from penetrating between the printed circuit board 2 and the lens carrier 18.

Claims (17)

Via at least partially injecting a composite of resin around a plurality of components comprising optical, electronic, mechanical and / or hybrid components in addition to at least one transducer A method of producing at least one sensor, wherein a polygonal shaped body is advantageously formed, the outer dimension of the body corresponding to the inner dimension of the injection mold,
The component is mechanically secured to the top and / or back of at least one printed circuit board prior to injection molding, and the at least one printed circuit board fitted with the component is injection molded The at least one printed circuit board, which is placed in a mold, where it is held by support fingers in a defined position relative to the wall of the casting mold and having the components, is fixed A method characterized by being injection molded in position.   The component of claim 1, wherein the component is installed, pressed, clipped, glued, or soldered onto the printed circuit board. Method.   As a transducer, an assembled hybrid integrated component is mechanically fixed on the printed circuit board, which component comprises the optical, electronic and / or mechanical component, at least partly 3. A method according to any one of claims 1 to 2, characterized in that it is injection molded.   A conduit element is mounted on the circuit board prior to the injection molding with the resin composite, whereby, in a top view of the circuit board, the wall of the conduit surrounds the transducer, thereby 4. A method according to any one of the preceding claims, wherein, after injection molding, the composite of resin surrounds a conduit formed by the conduit element.   A transducer comprising an optoelectronic component mechanically fixed on the printed circuit board and an assembled lens unit having a lens carrier and at least one lens, the lens carrier comprising the injection mold 5. A method according to any one of the preceding claims, characterized in that it is placed in a groove of the circuit board in a mold and is at least partially injection molded.   The mechanical component comprises at least one attachment element that is at least partially injection molded with the resin, thereby forming a mechanically rigid connection to the molded body. The method according to any one of claims 1 to 5.   The printed circuit board is assembled with a plurality of identical printed circuit boards to form a single printed circuit board panel, and the printed circuit board in the printed circuit board panel is placed in the injection mold. 7. The printed circuit board panel according to claim 1, wherein the printed circuit board is installed and injection-molded, and the encapsulated printed circuit board is separated from the printed circuit board panel. Method.   The method according to claim 1, wherein a transparent or translucent resin is used as a composite of the resin.   9. A sensor advantageously made by the method according to any one of claims 1 to 8, wherein at least one optical, mechanical, electronic and / or hybrid integration on the top and / or back side. A printed circuit board on which is mounted a component, wherein the printed circuit board and the component are at least partially surrounded by a molded resin body.   Sensor according to claim 9, characterized in that the component comprises at least one transducer, which is constructed as an electronic, mechanical and / or hybrid integrated component.   A conduit element embedded in the resin composition and forming a conduit in the resin composition, wherein the transducer is disposed in the conduit. Item 11. The sensor according to any one of Items 9 to 10.   12. The component of claim 9, wherein the component comprises an optoelectronic component and a light converter with a lens unit having a lens carrier and at least one lens extending over the lens unit. The sensor according to any one of claims.   Sensor according to any one of claims 9 to 12, characterized in that at least one mechanical component is constructed on the printed circuit board as an attachment element.   14. A sensor according to any one of claims 9 to 13, characterized in that an additional alignment pin is provided on the molded body in order to accurately position the sensor.   15. Sensor according to any one of claims 13 or 14, characterized in that the mounting element comprises a threaded insert or a threaded sleeve.   Sensor according to any one of claims 9 to 15, characterized in that an electrical connection is guided through the threaded sleeve.   17. The molded body according to any one of claims 9 to 16, characterized in that the molded body is made of a transparent or translucent resin, and advantageously a light emitting diode is provided on the printed circuit board. Sensor.

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