DE102016215414A1 - Screw dome for an electronic module and electronic module with a screw dome - Google Patents

Abstract

The invention relates to a screw dome (1) for an electronic assembly (3) and such an electronic assembly (3). The screw dome (1) comprises a threaded element (4) having a preformed thread. Furthermore, the screw dome (1) comprises a jacket (6) of thermoplastic material, which surrounds the threaded element (4) at least on the shell side, and which is adapted for fastening the threaded element (4) to a carrier component (2). The electronic assembly (3) comprises in addition to the separately manufactured screw dome (1), the support member (2) on which electrical components are mounted. The screw dome (1) is attached to the carrier component (2) by means of a laser beam joining method.

Description

The invention relates to a Schraubdom for an electronic module. Furthermore, the invention relates to an electronic assembly with such a screw dome.

Electronic assemblies used in motor vehicles, e.g. Due to their location (in the area of the engine or gearbox), control devices for engines or / gearboxes are usually subject to comparatively high temperature values of, for example, 80 to 150 ° C. during operation. These temperature values must withstand the control devices, in particular their electrical, in particular electronic components, which often comprise elements made of plastic. In addition, the electrical components of such control devices often generate heat themselves in operation, which must be derived via a suitable design of the housing of such control units. As housing materials, therefore, metals or thermally conductive filled plastics (i.e., plastics having a comparatively high thermal conductivity filler, eg, a metal or a ceramic) are often used. The electrical components of the control units are often connected via heat contact surfaces with such housings, so that the heat generated by the electrical components can be dissipated with high efficiency.

In order to enable maintenance and / or retrofitting of the control units if necessary, the housing of the control units are usually (reversibly) closed by means of screw. Similarly, often attachments or the electrical components bearing circuit boards (circuit boards) are attached by screws to the housings. In order to enable the most stable possible screw connection to the comparatively thin-walled housing walls which are frequently produced by means of casting methods (for example plastic injection molding or metal die casting), so-called screw domes are usually used. These are cylindrical or conical extensions of the housing, in which a (threaded) bore is introduced for receiving the screws. In particular, in plastic injection molding is due to the Wanddickensprünge at the transition to the screw domes often expected to delay, so that an exact alignment of the screw and thus precise positioning of the parts to be screwed only with relatively high effort, especially in the production of the corresponding injection mold (also known as Tool referred) is connected. In the case of metal diecasting, the problem often arises that the mandrels used for forming the screw domes, in particular their threaded bores, can be washed out and / or broken by repeated overflowing through the metal, so that expensive and expensive maintenance of the corresponding tool is required.

The invention has for its object to allow for an electronic assembly in a simple way a screw with high positioning accuracy.

This object is achieved by a Schraubdom with the features of claim 1. Furthermore, this object is achieved by an electronic assembly with the features of claim 6. Advantageous and sometimes inventive embodiments and refinements of the invention are in the dependent claims and the set forth below description.

The Schraubdom invention is intended for use on an electronic module. The screw dome is preferably designed and provided for (preferably "subsequent" and) free positioning on a carrier component of such an electronic assembly. In the intended mounting state of the screw dome is used in particular for holding a (fastening) screw and thus indirectly for holding a component of the electronic module to the support member. The screw dome in this case comprises a threaded element which has a preformed thread, in particular an internal thread. Furthermore, the screw dome comprises a jacket of thermoplastic material which surrounds the threaded element at least on the shell side. The jacket is set up for fastening the threaded element to the carrier component of the electronic assembly. Consequently, the screw dome is a component manufactured separately from the carrier component.

Preferably, the threaded element for forming the shell with the plastic encapsulated in an injection molding process. Ie. it is in the threaded element to an insert.

Because the screwing dome is designed separately from the carrier component, it can advantageously be positioned on the carrier component as required (in particular as desired). For this reason in particular, comparatively small positional tolerances (and thus a high accuracy of fit) can advantageously be achieved with a subsequent attachment of the screw dome or, if appropriate, a plurality of screw domes on the support component, without requiring a high outlay in the production of the entire support component. By wrapping the threaded element with thermoplastic material can further easily a If necessary, geometry required for fastening the threaded element can be formed, while a standard component can preferably be used as the threaded element. As a result, in turn costs for storage of many different threaded elements can be saved.

In a preferred embodiment, the plastic of the shell is a laser-weldable thermoplastic material. The screw dome is in this case in particular adapted to be fixed by means of a laser beam joining method to the support member. Preferably, the plastic of the jacket of the screw dome is a laser-transparent plastic. This is expedient, for example, in the case where the carrier component is formed from a laser-beam-weldable, laser-beam-absorbing thermoplastic material. Correspondingly, conversely, the jacket of the screw dome is made of a laser-beam-absorbing (laser-beam-weldable) plastic, when the carrier component is formed from a laser-beam-transparent (laser-beam-weldable) plastic.

In an expedient embodiment, the jacket of the screw dome has a flange-like projection on an end designated as "fastening end". For the preferred case that the screw dome has an approximately cylindrical basic shape, this projection is in particular formed as a radial projection (hereinafter referred to briefly as "flange"). On this flange a - preferably aligned transversely to a screwing of the threaded element - bearing surface is formed on which in the intended mounting state is formed a cohesive and / or positive connection with the support member. The bearing surface is suitably formed by a transversely extending to the screw surface of the flange itself. However, the flange preferably has a web projecting along the screwing direction, which web is designed to be closed in an annular manner in particular, and at the free end of which the bearing surface is formed. In the event that the screw dome attached by means of the laser beam joining method to the support member, advantageously sufficient thermoplastic material is held by the web, so that for a joint connection with sufficient strength a correspondingly long "sweat path" (also: Einsinkweg) is possible.

In an expedient embodiment, the threaded element is a particular metallic threaded bushing. As a result, an automatic screwing in the screwed dome to be screw is advantageously simplified during assembly of the electronic module.

In a further expedient embodiment, the threaded element, in particular the threaded bush, is anchored positively and materially in the shell. This means that the threaded element has on its outer side projections and / or cuts, in which the thermoplastic material of the shell "claw" can, so even at high screw-in and / or axial forces twisting of the threaded member in or a withdrawal of the threaded element the coat is effectively prevented. The cohesive anchoring is formed by an adhesion of the thermoplastic material to the metallic threaded element.

The electronic assembly according to the invention comprises a carrier component to which electrical components, such as e.g. at least one printed circuit board, circuit components and the like are held. Furthermore, the electronic assembly comprises at least one screw dome of the type described above, which is manufactured separately from the carrier component. The screw dome is fastened to the carrier component by means of a laser beam joining method.

Preferably, the electronic assembly also includes other components, such as e.g. one or more housing cover for preferably media-tight housing of the electrical components, a heat sink, plug contacts for electrically connecting the electrical components to a power source and / or other electronic components. Preferably, at least one of the components and / or the electrical components is fastened by means of a screw to the screw dome or one of the possibly more screw domes.

The carrier component is preferably a housing element of a housing of the electronic module. By way of example, the carrier component forms a "housing pan" in which the electrical components are arranged and held and, by means of the housing cover described above, are enclosed in a media-tight manner.

In an expedient embodiment, the carrier component is formed from the laser-beam-weldable, in particular the laser-beam-absorbing thermoplastic material. This makes it possible in a particularly simple manner a joint connection with the screw dome, the jacket is preferably formed in this case from the laser-transparent thermoplastic. To form the joint connection is preferably the laser-transparent shell, in particular its flange, placed on the support member and irradiated by means of a laser beam. In this case, the laser-beam-absorbing plastic of the carrier component heats up to its melting temperature (ie, up to the temperature value at which the plastic melts). In particular, the laser-beam-transparent plastic of the screw-type dome is heated up to its melting temperature by the laser-beam-absorbing plastic, so that a plastic laser weld seam is formed between the two components.

In an alternative embodiment, the carrier component is made of metal, for example aluminum or steel. Also in this case, the screw dome is fixed to the support member by means of laser beam joining. For this purpose, the joining surface of the carrier component is first (micro) structured, in particular immediately prior to placement of the screw dome. This structuring takes place in particular by means of a laser beam. In this case, a wavy or sawtooth-like surface structure is preferably formed with undercuts, wherein the size of the structure in the range of less than 1 mm, preferably in the range of less than 0.3 mm. Subsequently, the flange of the screw dome is placed on the structured surface of the carrier component and irradiated by means of a laser beam, so that the metal of the carrier component heats up locally. As a result, the laser-transparent plastic of the screw dome is indirectly heated to its melting temperature. The molten plastic then flows into the surface structure of the carrier component, under the action of a joining pressure which is preferably applied between the screw dome and the carrier component, thereby forming a connection, in particular a material and positive connection. Due to the design of the carrier component made of metal, a comparatively stable design of the electronic assembly is made possible, in particular even in the case of the usually high operating temperatures in the engine or gear compartment of a motor vehicle. Furthermore, a heat dissipation from the electrical components of the electronic assembly through the metal of the support member is made possible. The joining connection formed in this embodiment is referred to here and below as a metal-plastic laser joining connection.

In an expedient embodiment, the screw dome, in particular its flange, rests on the carrier component from a screw-in side of the threaded element.

In a particularly preferred embodiment, the screw dome engages through the carrier component. As a result, at least part of the length of the screw dome is arranged in the carrier component, so that a comparatively flat design of the unit consisting of carrier component and screw dome is made possible.

In a preferred embodiment of the embodiment described above, the flange of the jacket of the screw is located on a rear side in the screwing direction (hereinafter also referred to as "back") of the support member on this. In other words, the screw dome with its flange engages behind the carrier component and thus forms a (in particular additional) positive connection with the carrier component, so that in particular a recording of axial tensile forces which are introduced by the screw is improved.

Hereinafter, embodiment of the invention will be explained in more detail in a drawing. Show:

1 in a schematic cross section a screw dome,

2 in view according to 1 a section of an electronic module with the Schraubdom after 1 , and

3 to 6 in view according to 2 in each case an alternative embodiment of the electronic module.

Corresponding parts are always provided with the same reference numerals in all figures.

In 1 is a screw dome 1 shown in a schematic cross section. The screw dome 1 represents a fastener that flexible yet precise on a support member 2 an electronic assembly 3 (see. 2 ) can be positioned and fixed. The screw dome 1 includes a metallic threaded bush 4 , which is cylindrical in the present embodiment and has a not-shown inner thread. The threaded bush 4 is on the outside, ie concrete coat side with a jacket formed of thermoplastic material 6 molded. The screw dome 1 is also for attachment by means of a laser beam joining method to the support member 2 furnished and provided. This is the coat 6 of the screw dome 1 formed from a laser-transparent thermoplastic. Furthermore, the coat includes 6 one below as a collar or flange 8th designated, radially from the jacket 6 protruding projection, which at one end (as attachment end 10 referred to) of the screw 1 is arranged. At the flange 8th is a support surface 12 trained, with the screw dome 1 in the intended installation condition (cf. 2 ) on the carrier component 2 is applied. Im in 1 illustrated embodiment is the support surface 12 on a ring walkway 14 arranged along a screwing 16 the threaded bush 4 extending from the flange 8th protrudes.

In 2 is part of the electronic assembly 3 shown in a schematic cross section. The screw dome 1 is in the illustrated, intended mounting state of the module 3 by means of a laser beam joining connection 18 on the support component 2 attached. In the illustrated embodiment, the support member 2 formed from a laser beam weldable and laser beam absorbing thermoplastic material.

The laser beam joint 18 is made by the screw dome 1 with the flange 8th , specifically with the support surface 12 of the ring walkway 14 , on a surface 20 of the carrier component 2 is put on. Subsequently, the flange 8th , and with it the ring bridge 14 , irradiated with a laser beam. Due to the absorption of the laser beam in the plastic of the carrier component 2 becomes the carrier component 2 locally heated. By thermal conduction is thereby also the laser-transparent plastic of the jacket 6 in the area of the bearing surface 12 heated. The respective plastic of the carrier component 2 and the coat 6 is chosen such that they melt at a comparable temperature value, for example. Within a temperature difference of about 5 to 20 ° C. As a result, melt the two plastics of the carrier component 2 and the coat 6 approximately simultaneously, whereby a cohesive, permanent connection is formed. In this case, the laser beam joint is used 18 specifically a "plastic laser weld".

In an alternative, also based on 2 illustrated embodiment is the support member 2 formed from a laser-transparent, thermoplastic material. Accordingly, the coat 6 of the screw dome 1 formed from a laser beam absorbing thermoplastic material. In the manufacture of the laser beam joint 18 in this case becomes the carrier component 2 irradiated with the laser beam.

In another, also based on 2 illustrated embodiment is the support member 2 made of metal, concretely made of aluminum. In this case, the coat is 6 of the screw dome 1 Made of laser-transparent, thermoplastic material. For the formation of the laser beam joint connection 18 is doing before putting the screw dome 1 on the carrier component 2 its surface 20 in the area where the screw dome 1 is surface-structured by means of a laser beam (specifically microstructured). Subsequently, the flange 8th of the screw dome 1 placed on this area and irradiated with a laser beam. Because of the carrier component 2 absorbed energy of the laser beam, the carrier component heats up 2 locally and due to heat conduction also the plastic of the jacket 6 , Upon reaching the melting temperature of the plastic of the jacket 6 This melts locally and flows into the surface structure of the carrier component 2 a, so that a Verkrallung, ie a positive connection, as well as a manner of a hot-melt adhesive bond between the Schraubdom 1 and the carrier component 2 forms.

In 3 is an alternative embodiment of the electronic assembly 3 shown. In this case, the flange is 8th flat on both sides. Thus, the entire, in a radial plane represents the screwing direction 16 lying surface of the flange 8th the bearing surface 12 In order to provide plastic for a sufficient "sweat path" for a sufficiently strong plastic laser weld, is a ring land 21 on the (in this case laser-weldable plastic molded) support member 2 educated.

In a further embodiment according to 4 is in the carrier component 2 a hole 22 arranged, which are aligned with the screwing direction 16 is executed. This can also be compared to the Schraubdom 1 longer screws in the threaded bushing 4 be screwed or alternatively a screw from the the screw dome 1 opposite surface 24 of the carrier component 2 be trained forth.

In addition to the laser beam joint 18 a form fit across the screw 16 is the ring bridge 14 of the coat 8th extended over the preceding embodiments and is located in an annular groove 26 of the carrier component 2 one. The laser beam joint 18 is at the groove bottom of the annular groove 26 educated.

In a further embodiment of the electronic module 3 according to 6 is the screw dome 1 partly in a through hole 28 of the carrier component 2 arranged. In this case, essentially only the attachment end 10 with the flange 8th over the surface 20 of the carrier component 2 above. This embodiment is particularly useful in the event that a screw from the (the flange 8th opposite) surface 24 done here. Because in this case, from the screw into the Schraubdom 1 introduced tensile forces form fit of the flange 8th in the carrier component 2 initiated. Furthermore, the height of the carrier component 2 with the attached screw dome 1 reduced compared to the embodiment described above.

In the embodiments according to 4 to 6 this is the laser beam joint 18 either in the context of the embodiment according to 2 described plastic laser welding connection or formed by means of a laser beam metal-plastic laser bond.

In the carrier component 2 it is a housing element of the electronic module 3 on which electrical components such as circuit boards, circuit carriers, circuit components and / or microprocessors or integrated circuits (eg ASICs or combinations thereof) are mounted.

The object of the invention is not limited to the embodiments described above. Rather, other embodiments of the invention may be derived by those skilled in the art from the foregoing description. In particular, the individual features of the invention described with reference to the various exemplary embodiments and their design variants can also be combined with one another in a different manner.

LIST OF REFERENCE NUMBERS

1

screw boss

2

support component

3

electronic assembly

4

threaded bushing

6

coat

8th

flange

10

attachment end

12

bearing surface

14

ring land

16

screwing

17

Laser beam joint connection

20

surface

21

ring land

22

drilling

24

surface

26

ring groove

28

Through Hole

Claims (10)

Screw dome ( 1 ) for an electronic assembly ( 3 ), - with a threaded element ( 4 ), which has a preformed thread, - with a jacket ( 6 ) made of thermoplastic material, the threaded element ( 4 ) surrounds at least on the shell side, and for fastening the threaded element ( 4 ) on a carrier component ( 2 ) is set up. Screw dome ( 1 ) according to claim 1, wherein the plastic of the shell ( 6 ) is a laser beam weldable, in particular a laser-transparent plastic. Screw dome ( 1 ) according to claim 1 or 2, wherein the jacket ( 6 ) at an attachment end ( 10 ) a flange-like projection ( 8th ), on which a bearing surface ( 12 ) is formed on the in the intended mounting state a cohesive and / or positive connection with the carrier component ( 2 ) is trained. Screw dome ( 1 ) according to one of claims 1 to 3, wherein the threaded element is a metallic threaded bushing ( 4 ). Screw dome ( 1 ) according to one of claims 1 to 4, wherein the threaded element ( 4 ) positively and cohesively in the shell ( 6 ) is anchored. Electronic assembly ( 3 ), - with a carrier component ( 2 ), are supported on the electrical components, and - at least one separately from the support member ( 2 ) screwed dome ( 1 ) according to one of claims 1 to 5, wherein the screw dome ( 1 ) by means of a laser beam joining method on the carrier component ( 2 ) is attached. Electronic assembly ( 3 ) according to claim 6, wherein the carrier component ( 2 ) is formed from laser beam weldable, in particular laser-absorbing thermoplastic material. Electronic assembly ( 3 ) according to claim 6, wherein the carrier component ( 2 ) is formed of metal. Electronic assembly ( 3 ) according to one of claims 6 to 8, wherein the screw dome ( 1 ) the carrier component ( 2 ). Electronic assembly ( 3 ) according to claim 9, wherein the flange-like projection ( 8th ) of the jacket ( 6 ) of the screw dome ( 1 ) on a rearward in the screwing of a screw surface ( 20 ) of the carrier component ( 2 ) rests on this.

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