Injection-Molded Component with Insert Part, Method for Producing Same, and Uses Thereof

Abstract

The invention relates to a method for producing an injection-molded component with an insert part. An insert part is provided with an inorganic surface, and the insert part is at least partly overmolded during the injection-molding process. The region, which is overmolded during the injection-molding process, of the inorganic surface of the insert part is coated at least in some regions prior to being overmolded, wherein the inorganic surface is supplied with an atmospheric plasma beam and a precursor. The invention further relates to an injection-molded component with an insert part, said insert part having an at least partly overmolded inorganic surface. A layer which is applied by means of a plasma coating process, in particular a plasma polymerization process, is arranged at least in some regions between the inorganic surface and the overmolded plastic.

Claims

1. A method for producing an injection-moulded component with an insert comprising: providing the insert with an inorganic surface, wherein the insert is at least partly overmoulded in an injection moulding process, and wherein an area of the inorganic surface of the insert, which area is overmoulded during the injection moulding process, is at least in certain areas coated prior to being overmoulded by impinging the inorganic surface with an atmospheric plasma beam and a precursor, and wherein an organosilicon-functionalized precursor is used as the precursor.

2. The method according to claim 1, wherein the insert is only partly overmoulded in the injection moulding process, so that an area of the insert is exposed after the injection moulding process.

3. The method according to claim 1, wherein the inorganic surface is a metal surface, a glass surface, or a ceramic surface.

4. The method according to claim 1, wherein the insert is an electrical component to be overmoulded.

5. The method according to claim 1, wherein a plasma nozzle generates the atmospheric plasma beam, wherein the plasma nozzle has a nozzle opening, out of which the plasma beam emerges in operation.

6. The method according to claim 1, wherein the atmospheric plasma beam is generated by means of an arc-like discharge in a working gas, wherein the arc-like discharge is generated by applying a high-frequency high voltage between electrodes.

7. The method according to claim 1, wherein the precursor is fed into the plasma beam.

8. (canceled)

9. The method according to claim 1, wherein the insert is overmoulded with a thermoplastic synthetic material.

10. An injection-moulded component comprising an insert, wherein the insert has an at least partly overmoulded, inorganic surface, wherein a layer applied by plasma coating is arranged at least in certain areas between the inorganic surface and an overmoulded plastic.

11. The injection-moulded component according to claim 10, wherein the insert is only partly overmoulded, so that an area of the insert is exposed.

12. The injection-moulded component according to claim 10, wherein the insert is an electrical component comprising at least one of an overmoulded plug element, an overmoulded sensor, or an overmoulded conductor configuration.

13. The injection-moulded component according to claim 10, wherein the injection-moulded component is designed for application in an environment which is wet or contains solvents.

14. A method of using the injection-moulded component according to claim 10, the method comprising applying the injection-moulded component in an environment which is wet and contains solvents.

15. The method according to claim 4, wherein the electrical component comprises at least one of a plug element, a sensor, or a conductor structure.

16. The method according to claim 4, wherein the electrical component is a lead frame.

17. The method according to claim 9, wherein the thermoplastic synthetic material comprises at least one of polyamide, polybutylene terephthalate, polyethylene terephthalate, polycarbonate, or a liquid crystal polymer.

18. The method according to claim 1, wherein the insert is overmoulded with a thermosetting plastic.

19. The method according to claim 18, wherein the thermosetting plastic comprises polyurethane or epoxy resin.

20. The method according to claim 13, wherein the environment is a motor vehicle or an aircraft.

Description

[0041] Further features and advantages of the invention result from the following description of exemplary embodiments, in which reference is made to the attached figures.

[0042] FIG. 1 shows an exemplary embodiment for a plasma nozzle which can be used for the method,

[0043] FIGS. 2a-d show an exemplary embodiment of the method for producing an injection-moulded component with insert and an exemplary embodiment of the injection-moulded component with insert,

[0044] FIG. 3 shows a further exemplary embodiment of the injection-moulded component with insert,

[0045] FIG. 4 shows a further exemplary embodiment of the injection-moulded component with insert,

[0046] FIG. 5 shows a further exemplary embodiment of the injection-moulded component with insert,

[0047] FIG. 6 shows a diagram with results of shear tension tests on injection-moulded components and

[0048] FIG. 7 shows a diagram with results of shear tension tests on injection-moulded components after ageing in various media.

[0049] FIG. 1 firstly shows, in a schematic sectional view, a plasma nozzle which can be used in the described method for producing an injection-moulded component with insert.

[0050] The plasma nozzle 2 has a nozzle tube 4 consisting of metal which tapers towards a nozzle opening 6. At the end opposite the nozzle opening 6 the nozzle tube 4 has a swirling device 8 with an inlet 10 for a working gas, for example for nitrogen.

[0051] An intermediate wall 12 of the swirling device 8 has a ring of holes 14 which are positioned obliquely in the circumferential direction and through which the working gas is swirled. The working gas hence flows through the downstream, tapered part of the nozzle tube in the form of a vortex 16, the core of which runs on the longitudinal axis of the nozzle tube. An electrode 18 is arranged centrally on the underside of the intermediate wall 12 and protrudes coaxially in the direction of the tapered section into the nozzle tube. The electrode 18 is electrically connected to the intermediate wall 12 and to the other parts of the swirling device 8. The swirling device 8 is electrically insulated from the nozzle tube 4 by a ceramic tube 20. A high-frequency high voltage, which is generated by a transformer 22, is applied to the electrode 18 via the swirling device 8. The inlet 10 is connected via a hose (not shown) to a pressurised working gas source with variable throughput. The nozzle tube 4 is earthed. A high-frequency discharge in the form of an electric arc 24 is generated between the electrode 18 and the nozzle tube 4 by the applied voltage.

[0052] The term electric arc is used here as a phenomenological description of the discharge, since the discharge occurs in the form of an electric arc. The term electric arc is otherwise understood in the context of direct voltage discharges with essentially constant voltage values.

[0053] Due to the swirling flow of the working gas, this electric arc is, however, channelled in the vortex core on the axis of the nozzle tube 4, so that it only branches out in the area of the nozzle opening 6 to the wall of the nozzle tube 4. The working gas, which rotates with high flow velocity in the area of the vortex core and hence in close proximity to the electric arc 24, comes into intimate contact with the electric arc and is thereby partly converted to the plasma state, so that an atmospheric plasma beam 26 emerges out of the plasma nozzle 2 through the nozzle opening 6.

[0054] In order to plasma coat a surface, the surface is impinged with the plasma beam 26 and a suitable precursor 28. The precursor 28 can in particular be introduced into the plasma beam 26. A precursor feed line, which feeds the precursor 28 into the plasma beam 26, can be arranged, for example, in the area of the nozzle opening 6 for this purpose. Such a precursor feed line can also be integrated into the plasma nozzle 2. For example, a tube with a precursor feed line can be attached to the nozzle opening 6, so that the plasma beam 26 is conducted through the tube and the precursor is introduced into the plasma beam in the tube. A precursor feed line which introduces the precursor into the interior of the nozzle tube 4 is also conceivable. The precursor can also be introduced together with the working gas through the inlet 10 into the nozzle tube 4. However, it is preferable to introduce the precursor 28 into the plasma beam 26 outside the nozzle tube 4, so that the precursor 28 is not affected by the electric arc 24 or the high temperatures within the nozzle tube 4.

[0055] The interaction of the plasma beam 26 with the precursor 28 results in an activation and possible fragmentation of the precursor 28. The activated precursor 28 then forms a uniform layer when it strikes the surface to be coated.

[0056] FIGS. 2a-d now show an exemplary embodiment of the method for producing an injection-moulded component with insert and an exemplary embodiment of the injection-moulded component with insert.

[0057] In a first step, illustrated in a schematic sectional view in FIG. 2a, an insert 40 is firstly provided. In this exemplary embodiment, the insert is a plug pin. The method can also be carried out in a corresponding manner with other inserts. The plug pin consists of metal and therefore has a metal surface as the inorganic surface 42.

[0058] It became apparent that a direct connection of the metal surface 42 to a plastic, which connection has long-term durability and is media-tight, is difficult to achieve. Therefore, in the second step, illustrated in a schematic partial sectional view in FIG. 2b, the metal surface 42 is provided with a layer 44 applied by atmospheric plasma coating. For this purpose, an atmospheric plasma beam 48 is generated using a plasma nozzle 46 and directed onto the metal surface 42. The plasma nozzle 46 can in particular be designed like the plasma nozzle 2 illustrated in FIG. 1 and the plasma beam 48 can thus correspond to the plasma beam 26.

[0059] A precursor 50 is fed to the plasma beam 48, so that it is activated by the plasma beam 48 and reaches the metal surface together with the plasma beam 48, where it forms the layer 44 by plasma polymerisation. The precursor 50 can preferably be an organic compound, in particular an organosilicon compound.

[0060] Before the plasma coating, the metal surface can optionally be subjected to plasma pre-cleaning. For example, for the pre-cleaning the metal surface can firstly just be impinged with the plasma beam 48, without the addition of the precursor 50, before the precursor 50 is added to the plasma beam 48.

[0061] In the third step shown in a schematic sectional view in FIG. 2c, the coated insert 40 is arranged in an injection mould 52. The injection mould 52 consists of two halves 54a-b which when put together enclose a cavity 56 which defines the outer form of the injection-moulded component to be produced. The insert 40 is positioned in the injection mould 52 in such a way that an overmould area 58 of the insert 40 is arranged within the cavity 56 and a connection area 60 of the insert 40 is closely encompassed by the injection mould 52, so that it lies outside the cavity 56. The overmould area 58 at least partly encompasses the area of the metal surface 42 coated with the layer 44, so that the layer 44 is at least partly arranged within the cavity 56.

[0062] During the injection moulding process, liquid plastic is injected under pressure into the injection mould 52 by means of a sprue 62, so that the plastic fills up the cavity 56. The insert 40 is thereby embedded by the plastic in the overmould area 58, wherein the layer 44 provides a good adhesion between the metal surface 42 and the plastic. The connection area 60 of the insert 40 remains free of plastic during the injection moulding process.

[0063] After the plastic has solidified, the complete injection-moulded component 64 can be removed from the injection mould 52. The complete injection-moulded component 64 is illustrated in FIG. 2d in a schematic sectional view. A connection between the insert 40 and the plastic 66, which connection has long-term durability and is media-tight, is ensured by the layer 44. In this way, infiltration of the connection between the insert 40 and the plastic 66 from the connection area 60, e.g. by wetness, oil or organic solvents, is prevented. The injection-moulded component 64 produced in this way is therefore particularly suitable for use in an environment which is wet, contains oil or solvents, for example in the engine compartment of a motor vehicle or inside a coolant, lubricant or fuel line system or tank.

[0064] FIG. 3 shows a further exemplary embodiment of an injection-moulded component 70 with insert 72 in a schematic view. The insert 72 is a lead frame for a microchip 74. The lead frame 72 comprises a conductor configuration 76 consisting of metal with a plurality of conductors which in each case lead outwards from a contact point of the microchip 74 to a solderable contact foot 78. The conductor configuration 76 is embedded in a frame 80 for better handling.

[0065] When encasing microchips, the microchip 74 is placed in the middle of the conductor configuration 76 and the contact points of the microchip are bonded with gold wires to the individual conductors of the conductor configuration 76. In order to protect the microchip from environmental influences, the microchip 74 and the conductor configuration 76 are then encapsulated with a plastic casing 82 in an injection moulding process, in which the contact feet 78 remain free. After the injection moulding, the fully encased microchip, i.e. the complete injection-moulded component 70, can be separated from the frame 80.

[0066] In order to prevent wetness or other media infiltrating the connection between the contact feet 78 and the plastic casing 82, before the injection moulding the lead frame 72 is plasma coated in the area 84 adjoining the exposed contact feet 78 by impinging this area 84 of the lead frame 72 with a plasma beam and a precursor. The layer produced in this way guarantees a connection between the conductor configuration 76 and the plastic casing 82 which has long-term durability and is media-tight.

[0067] FIG. 4 shows a further exemplary embodiment of an injection-moulded component 90 with insert 92 in a schematic view. The insert 92 is a lead frame for producing a plurality of plugs. The lead frame 92 has a plurality of conductor structures 92 which for easier handling are arranged on a comb-shaped frame 94. In order to produce the plugs, the lead frame 92 is arranged in an injection mould which has a separate cavity for each conductor structure 92, so that each conductor structure 92 is embedded in a separate plastic casing 96 during the injection moulding process, wherein in each case a connection area 98 remains free. After the injection moulding, the complete plugs can be separated from the frame 94.

[0068] In order to prevent wetness or other media infiltrating the connection between the conductor structures 92 and the plastic casing 96, before the injection moulding the lead frame 92 is plasma coated in the area 100 adjoining the exposed connection areas 98 by impinging this area 100 of the lead frame 92 with a plasma beam and a precursor. For the complete plug, the layer produced in this way guarantees a connection between the conductor structure 92 and the plastic casing 96 which has long-term durability and is media-tight.

[0069] FIG. 5 shows a further exemplary embodiment of an injection-moulded component 110 with insert 112 in a schematic sectional view. The insert 112 is a sensor having a sensor area 114 arranged on an outer face of the injection-moulded component 110, via which the sensor 112 can measure a property of the surroundings, for example the temperature or the brightness. The sensor 112 is embedded by means of injection moulding in a plastic casing 116 which protects the electronics of the sensor 112 from environmental influences. In order to prevent infiltration of the connection between the sensor 112 and the plastic casing 116 from the side of the sensor area 114, before the injection moulding the sensor 112 is plasma coated in the area 118 adjoining the sensor area 114 by impinging this area 118 with a plasma beam and a precursor. The layer produced in this way guarantees a connection between the sensor 112 and the plastic casing 116 which has long-term durability and is media-tight.

[0070] Shear tension tests were carried out according to DIN EN 1465 in order to examine the media-tightness of the connection between a metal insert and the overmoulded plastic produced using the previously described method.

[0071] For this purpose, metal samples consisting of different materials (DC04 steel, 1.4301 stainless steel, 1.4031 polished stainless steel, 6016 aluminium) were produced and in the injection moulding process were overmoulded in certain areas with polyamide 6 having a 30% glass fibre proportion (PA6 GF30) or with polybutylene terephthalate (PBT). The sample geometry in each case corresponded to DIN EN 1465.

[0072] A share of the metal samples was impinged with an atmospheric plasma beam and with -methacryloxypropyltrimethoxysilane as the precursor according to the previously described method before the overmoulding took place; another share of the metal samples remained untreated for comparison.

[0073] Shear tension tests were subsequently carried out on the partly overmoulded metal samples according to DIN EN 1465.

[0074] FIG. 6 shows a diagram with the results of the shear tension tests on the partly overmoulded metal samples which were impinged with an atmospheric plasma beam and with -methacryloxypropyltrimethoxysilane according to the previously described method before the overmoulding took place. As the diagram shows, good tensile shearing strengths were obtained throughout.

[0075] In contrast, the comparison samples without plasma treatment and precursor impingement came apart straightaway after the injection moulding process or as soon as very low force loads were applied (tensile shearing strengths<1 MPa).

[0076] In addition, some of the metal samples impinged with the atmospheric plasma beam and -methacryloxypropyltrimethoxysilane and overmoulded with PA6 GF30 were aged before carrying out the shear tension tests, in order to test the long-term durability and media-tightness of the connection between the insert and the plastic.

[0077] FIG. 7 shows a diagram with the results of these shear tension tests. The left side of the diagram shows the results for overmoulded metal samples consisting of steel (from left to right) without ageing, after carrying out the pressure cooker test (using water with 15% common salt (NaCl) and 0.15% hydrochloric acid (HCl) instead of pure water) and after ageing for four weeks in a 5% aqueous NaCl solution. The right side of the diagram shows the results for overmoulded metal samples consisting of stainless steel (from left to right) without ageing, after carrying out the pressure cooker test, after ageing for four weeks in a 5% aqueous NaCl solution, after storing for two weeks in ethanol and after storing for two weeks in engine oil.

[0078] The results show that even after the different ageing processes good tensile shearing strengths were obtained throughout. Hence, the tests prove that the described method for producing an injection-moulded component produces a connection between the (metal) insert and the overmoulded plastic which has long-term durability and is media-tight. Particularly good results were obtained in particular using functionalised organosilicon precursors like -methacryloxypropyltrimethoxysilane.

[0079] Thus, using the previously described method for producing an injection-moulded component with insert, injection-moulded components can be produced which have long-term durability and are media tight and which are particularly suitable for use in an environment which is wet or contains solvents, in particular in a vehicle, such as in a motor vehicle or in an aircraft.