Manufacturing process for a sensor for an automotive vehicle
The sensor manufacturing process addresses alignment and waterproofing issues by using a support structure with triangular section holding organs and metal pawns, enhancing sensor reliability and reducing defects during overmolding.
Patent Information
- Application Number
- FR2023001564
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-02-21
- Publication Date
- 2025-02-07
- Estimated Expiration
- 2043-02-21
AI Technical Summary
Existing sensor manufacturing processes for motor vehicles face challenges in ensuring waterproofing and alignment of components, particularly during the final overmolding stage, leading to potential measurement errors and defects.
A manufacturing process involving a support structure with triangular section holding organs and metal pawns that maintain alignment and provide robust protection during overmolding, ensuring geometric stability and reduced risk of defects.
The process enhances sensor alignment and waterproofing, reducing defects and ensuring reliable performance by maintaining geometric stability and protecting the support structure during the final overmolding stage.
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Abstract
Description
Title of the invention: Method for manufacturing a sensor for a motor vehicle Technical field
[0001] The present invention relates to the field of sensors for motor vehicles and more particularly to a sensor and a method of manufacturing such a sensor. The invention aims in particular to improve the sealing and alignment of the components of existing sensors. Prior art
[0002] In a known manner, a motor vehicle comprises measuring sensors making it possible, for example, to measure the rotational speed or the angular position of a drive shaft such as a crankshaft or a camshaft.
[0003] Still in a known manner, these sensors operate in association with a target fixed on the shaft of which a parameter is to be measured. The target is for example in the form of a toothed wheel whose teeth vary an electromagnetic field generated by a magnet mounted in the sensor. The variations in the magnetic field are captured by sensitive elements, called measuring cells, of the sensor.
[0004] According to a known manufacturing method, the sensor is manufactured in several stages. First, an integrated circuit is overmolded with a polyepoxy material, commonly called "epoxy", on a metal connection grid comprising connection pins, then the assembly is positioned in a mold and a magnet is optionally positioned on the integrated circuit. The assembly is overmolded leaving only the connection pins protruding. A final overmolding is applied in order to seal the sensor while forming an electrical connector of the sensor to the vehicle and a sensor fixing member, for example of the fixing ring type.
[0005] In some cases, the sensor may be in contact with a liquid, for example by being immersed in an oil bath or in a mist of oil droplets. The sealing of the final overmolding is therefore important, in particular to prevent the liquid from penetrating inside the sensor along the electrical pins and damaging the measuring cells.
[0006] Correct alignment of the sensor measuring cells on the support overmold and in the final overmold is also necessary to ensure good sensor performance and avoid measurement errors.
[0007] It is then important to be able to ensure the orientation of the first overmolded assembly, called “support overmolding”, comprising the integrated circuit and the measuring cells, and possibly a magnet, during the following overmolding operations.
[0008] One solution is to use a support overmolding comprising a foot to keep it upright. Another is to arrange cylindrical or rectangular protrusions on either side of the support overmolding, each configured to be fixed to an external pin or a cavity during the following overmolding operations to maintain the assembly supporting the measuring cells in a defined position. However, these two solutions do not make it possible to avoid orientation defects due to the final overmolding. Another known solution is to use these first two solutions simultaneously on the same support overmolding to avoid these orientation defects due to the final overmolding, but due to the resulting bulk, it limits the minimum size of the final sensor.
[0009] There is therefore a need for a solution to at least partially remedy these drawbacks. Statement of the invention
[0010] To this end, the invention firstly relates to a method for manufacturing an electronic sensor for a motor vehicle, comprising a sensitive element and connection pins, said sensitive element comprising a housing and at least one integrated circuit, said housing of the sensitive element comprising cells for measuring a parameter, said at least one integrated circuit being electrically connected to said connection pins by connection pins, said connection pins being on the one hand electrically connected to said connection pins of the integrated circuit and on the other hand intended to be connected to an electrical network of the vehicle, said method for manufacturing a sensor comprising the steps of:
[0011] - placement of the connection pins,
[0012] - positioning of a first mold, for example around the connection pins and / or a magnet and / or an integrated circuit,
[0013] - injection of material into the first mold so as to obtain an overmolding of support, said support overmolding comprising a connection face from which the connection pins extend, a receiving face opposite the connection face and configured to receive the housing of the sensitive element, an upper face configured to receive at least one connector of the sensitive element, a lower face opposite the upper face and two opposite lateral faces each extending between the connection face, the receiving face, the upper face and the lower face, the support overmolding comprising, on each lateral face, a holding member extending from said lateral face and being configured to hold the support overmolding in a mold for final overmolding, each holding member having a relief shape of triangular section delimiting a cavity in its center,
[0014] - placement of the sensitive element on the support overmolding, the at least one circuit integrated (232) being positioned so as to extend from the connection pins to the receiving face via the upper face and the housing of the sensitive element being positioned on the receiving face,
[0015] - soldering the connection tabs (232A) onto the connection pins,
[0016] - positioning of a second mold, different from the first mold, around the assembly formed by the connection pins and the support overmolding and two holding pins, one end of which, for each pin, is housed in the cavity of one of the holding members,
[0017] - injection of material into the second mold so as to obtain the final overmolding of the sensor, said final overmolding comprising an electrical connection member surrounding the free ends of the connection pins, and a member for fixing the sensor to an element of the vehicle,
[0018] - removal of the mold to obtain the sensor.
[0019] The triangular relief shape of the holding members on the side faces of the support overmolding makes it possible to limit alignment defects of this part. Unlike a cylindrical holding member, the triangular section imposes greater geometric constraints during the final overmolding step, which makes it possible to avoid a top / bottom inversion of the assembly formed by the pins and the support overmolding and better alignment of this part. The performance of the sensor is thus ensured. This invention makes it possible to have holding members of relatively large size in proportion to the reduced size of the support overmolding, which has the effect of making these holding members very robust due to the very low “overmolding flow grip”.The short length and simplicity of the reflow fins combined with the very small size of the support overmolding significantly reduces the risk of product leaks after final overmolding. The use of metal pins in the mold that fit into the cavities defined by the retaining members reinforces these members at the time of final overmolding material injection, and is also useful for conveying this sub-component into the final molding tooling. In addition, the reflow fins are protected at the time of insertion of these metal pins into the cavities by the protruding retaining members. In this way, the pins that fit into the cavities of the retaining members are not in direct contact with the mold and the overmolding material during final overmolding. They will therefore be easier to remove at the end of this step.
[0020] Advantageously, the holding members are made from the same material as the side faces of the support overmolding. This makes it possible to mold the support overmolding and the holding members in one go from the same material. The method is more efficient and the alignment of the holding members and the support overmolding is ensured.
[0021] Also preferably, the holding members of triangular section are arranged so that one face of said holding members is parallel to the upper face of the support overmolding. Thus, the upper face is wider and there is more space for the grooves receiving the electrical connection tabs connecting the housing of the sensitive element containing the measuring cells of the sensor to the connection pins.
[0022] Advantageously, the mold used during the final overmolding step comprises the definition of a triangular-shaped groove around each holding member. The stability for the alignment of the support overmolding in the final overmolding is thus reinforced due to the geometric constraints of the triangular-section holding members.
[0023] Advantageously, the step of injecting material to produce the support overmolding comprises the creation of at least one reflow fin around each holding member, preferably two reflow fins, for example with a peripheral protective rib. These reflow fins ensure sealing between the support overmolding and the final overmolding surrounding the sensor. Indeed, the support overmolding is visible on the final sensor at the holding members and is therefore exposed to the liquid.
[0024] Advantageously, the method comprises a step of inscribing an identification marking on at least one of the holding members after molding this part, preferably on its front face. This marking is useful for the logistical tracking of the sensors.
[0025] The invention relates to the first mold for shaping the support overmolding configured to, during a material injection, define a support overmolding comprising a connection face from which the connection pins extend, a receiving face, opposite the connection face and configured to receive the housing of the sensitive element, an upper face configured to receive at least one connector of the sensitive element, a lower face opposite the upper face and two opposite lateral faces each extending between the connection face, the receiving face, the upper face and the lower face, the support overmolding comprising, on each lateral face, a holding member extending from said lateral face and being configured to hold the support overmolding in a mold for final overmolding,each holding member having a raised shape of triangular section delimiting a cavity in its center.
[0026] The invention also relates to the second mold for manufacturing a sensor by the method as presented previously for the overmolding of the final overmolding. of the sensor configured to leave accessible part of the support overmolding holding members.
[0027] The invention also relates to a vehicle sensor thus obtained with the method, comprising a connector for electrical connection to the vehicle and a member for fixing to an element of said vehicle.
[0028] The invention also relates to a motor vehicle comprising a sensor as described above, fixed to an element of said vehicle and connected to a communication and electrical power supply network of said vehicle. Brief description of the drawings
[0029] Other characteristics and advantages of the invention will become apparent from reading the description which follows. This is purely illustrative and must be read in conjunction with the appended drawings in which:
[0030] [Fig-1] [Fig.l] schematically illustrates a sensor after the manufacturing process according to the invention.
[0031] [Fig.2] [Fig.2] is a perspective view of the connection pins in the first step of the method according to the invention
[0032] [Fig.3] [Fig.3] is a perspective view of the assembly formed by the connection pins and the support overmolding after the overmolding step of the method according to the invention.
[0033] [Fig.4] [Fig.4] is a sectional view in the plane of the connecting pins of the assembly formed by the connecting pins and the support overmolding as shown in [Fig.3].
[0034] [Fig.5] [Fig.5] is a perspective view of the assembly formed by the connection pins, the support overmolding, and the integrated circuit connected to measuring cells after the step of placing the sensitive element of the method according to the invention.
[0035] [Fig.6] [Fig.6] schematically illustrates an embodiment of the method according to the invention. Description of the embodiments
[0036] The sensor obtained by the method according to the invention is intended to be mounted in a motor vehicle. The sensor can be of any type. The sensor can for example be a position or speed sensor of a drive shaft such as a crankshaft or a camshaft or any other suitable shaft.
[0037] Sensor 1
[0038] As shown in [Fig.l], the sensor 1 comprises an electrical connection connector IA intended to be connected to an electrical network of the vehicle, a head IB in which the measuring cells are located and a fixing member IC which makes it possible to fix said sensor 1 in the vehicle.
[0039] The final overmolding 50 of the sensor 1 forms the external envelope at the end of the manufacturing method according to the invention.
[0040] Figures 2 to 5 show an embodiment of the sensor 1 according to the invention at different stages of the manufacturing process and [Fig.6] shows an embodiment of the process according to the invention.
[0041] First, as illustrated in [Fig.2], the connection pins 10 are arranged on a support (not shown for clarity) in a step E1.
[0042] The connection pins 10, of rectangular section, each comprise a free end 101 intended to be electrically connected to an electrical network of the vehicle (not shown), and a connection end 102 overmolded in a support overmolding 20.
[0043] Each connection pin 10 comprises a pad 103 allowing said connection pin 10 to be electrically welded with a connection tab 232A of the integrated circuit 232 (visible in [Fig.5]) of the sensor 1.
[0044] In a step E2, a two-part mold is positioned on the connection ends 102 of the connection pins 10
[0045] In a step E3, overmolding material is injected into the closed mold. The mold is configured to form a support overmolding 20 as shown in [Fig. 3] after the two parts of the mold have been removed at the end of step E3.
[0046] Advantageously during this step, identification inscriptions can be inscribed in hollow or in relief on the surface of the holding members 251, such as for example a mold identifier or the production location.
[0047] This support overmolding 20 comprises a connection face 21 from which the connection pins 10 extend, a receiving face 22, opposite the connection face 21, an upper face 23, a lower face 24 opposite the upper face 23 and two opposite lateral faces 25 each extending between the connection face 21, the receiving face 22, the upper face 23 and the lower face 24.
[0048] As shown in [Fig.4], the connection end 102 of the connection pins 10 is taken in the material of the support overmolding 20 on the connection face 21.
[0049] The receiving face 22 comprises a cavity 221 for receiving a magnet as well as supports 222 for fixing the housing of the sensitive element 223 shown in [Fig.5].
[0050] In another embodiment of the method, the magnet and / or the integrated circuit 232 of the housing of the sensitive element 223 could also be overmolded in the support overmolding 20, and this invention could be used in a sensor 1 not having a magnet.
[0051] The upper face 23 comprises several grooves 231 to receive the legs of connection 232A of the integrated circuit 232 shown in [Fig.5], which are soldered to the connection pins 10 by the pads 103 and which are connected to the housing of the sensitive element 223.
[0052] Each lateral face 25 comprises a holding member 251 configured to hold the support overmolding 20 in a mold for final overmolding 50, each holding member 251 having a relief shape of triangular section and delimiting a cavity 252 in its center.
[0053] Reflow fins 253 surround the holding members 251 on each side face 25.
[0054] In a step E4, the magnet (optional) and the housing of the sensitive element 223 are placed on the support overmolding 20, on the receiving face 22. The printed circuit 232 of the housing of the sensitive element 223 is placed in the grooves 231 and its connection tabs 232A are soldered to the pads 103 of the connection pins 10.
[0055] For the second molding of step E5, the assembly formed by the connection pins 10 and the support overmolding 20 is held in place by holding pins which are inserted into the cavities 252 of the holding members 251 of each lateral face 25.
[0056] The two parts of a second mold are positioned on the assembly, so as to be fixed around the surfaces of the holding members 251 and leave a part of these outside.
[0057] The overmolding material is injected in step E6. The second mold is configured to create the final overmolding 50 of the sensor 1 as shown in [Fig.l].
[0058] In a step E7, the walls of the mold are removed, leaving the holding members 251 visible, and the method of manufacturing the sensor 1 according to the invention is completed.
[0059] Advantageously, other identification inscriptions can be inscribed on the surface of the final overmolding 50 at the end of the process, for example by laser marking.
[0060] The invention thus proposes a reliable and effective method for reducing or even eliminating alignment defects during the manufacture of the sensor.
Claims
Claims
1. Method for manufacturing an electronic sensor (1) for a vehicle, said sensor (1) comprising a sensitive element and connection pins (10), said sensitive element comprising a housing (223) and at least one integrated circuit (232), said housing of the sensitive element (223) comprising cells for measuring a parameter, said at least one integrated circuit (232) being electrically connected to said connection pins (10) by connection lugs (232A), said connection pins (10) being on the one hand electrically connected to said connection lugs (232A) of the integrated circuit (232) and on the other hand intended to be connected to an electrical network of the vehicle, said method comprising the steps of: - placement of the connection pins (10), - positioning of a first mold, - injecting material into the first mold so as to obtain a support overmolding (20), said support overmolding (20) comprising a connection face (21) from which the connection pins (10) extend, a receiving face (22) opposite the connection face (21) and configured to receive the housing of the sensitive element (223), an upper face (23) configured to receive at least one integrated circuit (232) of the sensitive element, a lower face (24) opposite the upper face (23) and two opposite lateral faces (25) each extending between the connection face (21), the receiving face (22), the upper face (23) and the lower face (24), the support overmolding (20) comprising, on each lateral face (25) a holding member (251) extending from said lateral face (25) and being configured to hold the support overmolding (20) in a mold for final overmolding (50),each holding member (251) having a raised shape of triangular section delimiting a cavity (252) in its center, - placing the sensitive element on the support overmolding (20), the at least one integrated circuit (232) being placed so as to extend from the connection pins (10) to the receiving face (22) via the upper face (23) and the housing of the sensitive element (223) being placed on the receiving face (22), and soldering the connection tabs (232A) onto the connection pins (10), - positioning of a second mold, different from the first mold, around the assembly formed by the pins (10) and the support overmolding (20) and two holding pins, one end of which, for each pin, is housed in the cavity (252) of one of the holding members (251), - injection of material into the second mold so as to obtain the final overmolding (50) of the sensor (1), said final overmolding (50) comprising an electrical connection connector (IA) surrounding the free ends (101) of the connection pins (10), and a fixing member (IC) of the sensor (1) on an element of the vehicle, - removal of the mold to obtain the sensor (1).
2. Method according to claim 1, in which during the step of injecting the final overmolding (50), the injected material surrounds the holding members (251) so as to leave them at least partly visible on the sensor (1).
3. Method according to any one of the preceding claims, in which the holding members (251) are made from the same material as the lateral face (25) of the support overmolding (20).
4. Method according to any one of the preceding claims, in which the holding members (251) of triangular section are arranged so that one face of said holding members (251) is parallel to the upper face (23) of the support overmolding (20).
5. A method according to any preceding claim, wherein the final overmolding step (50) comprises defining a triangular-shaped groove around each holding member (251).
6. Method according to any one of the preceding claims, in which the step of injecting material to produce the support overmolding (20) comprises the creation of at least one reflow fin (253) around each holding member (251), preferably two reflow fins (253) with a peripheral protective rib.
7. A method according to any one of the preceding claims, comprising affixing an identification marking to at least one of the holding members (251), preferably to its front face.
8. Sensor (1) obtained by the method according to one of claims 1 to 7, said sensor (1) comprising an electrical connection connector (IA) to the vehicle and a fixing member (IC) for said sensor (1) to an element of the vehicle.
9. Motor vehicle comprising a sensor (1) according to claim previous, attached to an element of said vehicle and connected to a communication and electrical power network of said vehicle.