DE102013100197A1 - Sensing unit for motor car, has injection molded plastic carrier which is positioned on opposite side to sensor element, and formed of electrical contacts with respect to the circuit board - Google Patents

Abstract

The sensing unit has a spatial injection molded plastic carrier (1) whose one side is arranged on the circuit board. The plastic carrier is positioned on the opposite side to the sensor element. The electrical contacts (2) of plastic carrier are formed with respect to the circuit board. The electrical contacts are formed with surface-mount device (SMD) solderable surface contacts (2.4), and soldered to the other components by reflow soldering process. Independent claims are included for the following: (1) method for manufacture of sensing unit; and (2) method for assembly of sensing unit on circuit board.

Description

The invention relates to a sensor unit for a motor vehicle for mounting on a printed circuit board and means for damping the transmission of high-frequency interference to the sensor element according to the preamble of claim 1.

From the DE 44 06499 A1 For example, it can be seen a sensor unit with a damping holder, in which the damping holder holds the sensor element in a defined angle to the circuit board against mechanical vibrations dampening. The damping holder is soldered via pins in the circuit board. With increasing miniaturization of the sensor elements and improvement of manufacturing techniques, such a damping holder proves to be unsuitable and expensive.

From the DE 10 2005 053 876 A1 is a pressure sensor component refer to, in which the housing is provided as a so-called "MID" housing ("MID" = "moldeld interconnect device"), assembly and assembly are still very expensive.

The object of the present invention is therefore to present a sensor unit which is suitable for the requirements for use in a motor vehicle and has means for damping the transmission of high-frequency interference to the sensor element, but on the other hand is easy to assemble.

This object is solved by the features of the independent claims. Advantageous developments of the invention will become apparent from the dependent claims, wherein combinations and developments of individual features are conceivable with each other.

An essential idea of the invention is that the sensor unit has a spatial, injection-molded plastic carrier, which can be arranged with one side on the circuit board and on the opposite side, the sensor element is arranged and the plastic carrier at least one electrical contact from the sensor unit to the circuit board having. Such spatial, injection-molded plastic carriers are now known as so-called "MID" = "moldeld interconnect devices".

However, the production of these plastic carriers made of an injection-molded plastic material also makes it possible, in particular, to effectively dampen the transmission of high-frequency interference to the sensor element by suitable choice of the plastic, additives in the plastic composition or even formation of cavities in the plastic carrier.

On the other hand, the production technologies developed per se for such MID can be used to inexpensively manufacture and assemble the plastic carrier.

Thus, it is provided in a preferred development that the electrical contacts of the plastic carrier to the circuit board are formed as SMD solderable surface contacts.

Accordingly, the mounting of a sensor unit on a circuit board is preferably carried out by the sensor unit is arranged with the plastic carrier on corresponding SMD solder surfaces of the circuit board and fixed together with other to be mounted on the PCB SMD components by reflow soldering and electrically connected.

Preferably, the electrical contacts of the plastic carrier each have a lateral solder control surface analogous to the so-called QFN (Quad Flat No Leads) for an automatic optical inspection (AOI = Automatic Optical Inspection) of the soldering point, so that after soldering on the circuit board, a successful soldering of Lotstelle can also be recognized optically by means of a corresponding image recognition process by a solder application on these lateral solder control surfaces.

The production as MID also allows the plastic carrier has at least one cavity, wherein preferably by the number, size, shape and location of the at least one cavity, the damping characteristic is set.

The electrical contacts can be made with the plastic carrier as a two-component injection molded part, wherein the electrical contacts are generated by an electrically conductive admixture in the plastic of these electrical contacts and the plastic of the base body of the plastic carrier is non-conductive.

Alternatively, in a further exemplary embodiment, the electrical contacts are embodied as metallizations on the surface of the plastic carrier and guided from the side directed toward the printed circuit board via at least one side wall extending at right angles to the side of the plastic carrier facing the sensor element.

For this purpose, the plastic carrier on the corresponding surfaces, for example, activated by means of a laser and subsequently galvanized locally.

Preferably, the sensor element is contacted via an electrically conductive adhesive on the plastic carrier, wherein the adhesive is reflow soldering resistant, ie in particular temperature resistant, that the sensor unit below on the PCB together with other to be mounted on the PCB SMD components by reflow soldering is fastened.

The production of such a sensor unit is preferably carried out as a plurality of plastic carriers via at least one predetermined separation point in a strip form connected to each other and is fitted in this strip form with the sensor elements and before mounting the sensor unit on the circuit board in each case a sensor unit from the strip shape by separating the predetermined separation point (n) cut free. Thus, this strip shape is suitable for the usual roller belt delivery as usual for SMD components.

The invention will now be explained in more detail by means of exemplary embodiments with the aid of the figures. In the following, functionally identical and / or identical elements may be designated by the same reference numerals. Show it

1a - 1c : 1st embodiment with plastic carrier in 2K injection molding

2a & b: Design as a strip shape

3a : Sensor unit with sensor element on the plastic carrier

3b : Sensor unit on the circuit board

4a : further alternative embodiment of the cavities in the plastic carrier

4b : further alternative embodiment of the plastic carrier

The 1a . 1b and 1c show a first embodiment of a plastic carrier, in this embodiment, the main body 1.1 the plastic carrier as well as its electrical contacts 2 are manufactured in a joint manufacturing step as a 2-component injection molding. The electrical contacts 2 are generated by an electrically conductive admixture in the plastic in the region of these electrical contacts, while the plastic of the body 1.1 the plastic carrier is non-conductive contrast. In that regard, it should be made clear that 1C the electrical contacts in the form of an exploded view detached from the body 1.1 For better visibility of the details are shown, but the production side preferably in the above-mentioned common manufacturing step are made as a 2-component injection molding.

The plastic carrier is attached to one side of the circuit board ( 4 ) and is on the opposite side of the sensor element ( 3 ), as in 3B easy to recognize.

The plastic carrier points in 1 four rectangular cavities 1.2.a on, wherein preferably influenced by the number, size, shape and position of the cavity or remaining parts of the plastic carrier, the damping characteristic and thus adjusted according to the requirements of the particular application.

The plastic carrier has at least one, here in 1 a total of 16 electrical contacts ( 2 ), which in the fully assembled state, the sensor unit ( 3 ) with electrical contacts on the printed circuit board ( 4 ) connect (see. 3b ).

The electrical contacts according to the embodiment according to 1 are to the circuit board ( 4 ) as SMD-solderable area contacts ( 2.4 ) educated. In addition, these electrical contacts on the sensor element 3 directed upper side also as area contacts ( 2.2 ) and each is a lateral solder control surface 2.3 intended for automatic optical inspection of the soldering point. The outer surfaces of these electrical contacts, so the surface contacts 2.2 and 2.4 as well as the lateral solder control surface 2.3 can be formed not only by admixing conductive particles but also have on the surface metallizations to have better electrical conductivity and low contact resistance.

In the 2A and 2 B In addition, a preferred method for manufacturing is outlined in which a plurality of plastic carriers 1 via at least one predetermined separation point ( 1.4 ) is produced in a strip form connected to each other and in this strip form with the sensor elements ( 3 ) and before assembly of the sensor unit to the circuit board in each case a sensor unit from the strip shape by separating the predetermined separation point (s) 1.4 is cut free. As already explained at the outset, the sensor units including plastic carriers, such as other SMD-capable components, can thus be fed via roller conveyors to an SMD placement machine, and the expenditure required in terms of alignment and handling of the individual sensor units is considerably reduced.

3A shows again in detail the plastic carrier 1 equipped with the sensor element 3 , where the main body 3.1 of the sensor element 3 flat on the top of the plastic carrier flies up and with its electrical contacts 3.2 with corresponding surface contacts 2.2 on the plastic carrier 1 is connected, preferably with an electrically conductive adhesive, wherein the Adhesive is so reflow solder resistant that the sensor unit ( 3 ) can be fastened by reflow soldering on the printed circuit board together with further SMD components to be mounted on the printed circuit board. For this example, a silver conductive adhesive can be used, which is conductive after curing of the adhesive, but not dissolvable at standard reflow temperatures again.

As 3B sketchy, the assembly of a sensor unit on a circuit board is carried out accordingly by the sensor unit ( 3 ) with the plastic carrier ( 1 ) on corresponding SMD solder pads of the printed circuit board ( 4 ) and together with other to be mounted on the PCB SMD components ( 5 ) is fixed by reflow soldering and electrically connected.

4A outlines an alternative embodiment of the cavities 1.2.b here parallel to the through the circuit board 4 also defined here by the number, size, shape and location of the cavities 1.2.b the damping characteristic is set. However, it should be emphasized once again, as an alternative or in addition to the excavations 1.2 also by choosing the material of the plastic carrier 1 as well as appropriate admixtures in this material already a desired damping characteristic can be achieved, so that possibly on the formation of such cavities 1.2 can be dispensed with, as again in the 4G and 4C outlined.

The 4B also has a further embodiment of the plastic carrier as 2K injection molded part, wherein the compound 2.5 between the electrical contacts 2.2 on the side facing the sensor element to the electrical contacts 2.4 on the side facing the circuit board this time runs on the surface of the side wall and not as in 1 the connection 2.1 inside the plastic carrier in an opening 1.3 , Such a connection too. 5 Through the side wall allows a simple design of the injection molding tools and also a metallization over the surface and thus better electrical conductivity.

The 4C shows now another embodiment without 2-component injection molding, in which therefore the plastic carrier 1 is made of a uniform plastic material, however, the surface of which has been metallized, for example by laser activation and subsequent galvanization and thus made electrically conductive.

The electrical contacts ( 2 ) are thus designed as metallizations on the surface of the plastic carrier and the surface contacts 2.4 from the side directed towards the printed circuit board via at least one side wall extending at right angles thereto and connecting tracks running there 2.5 to the surface contacts 2.2 led to the sensor element side of the plastic carrier. In addition, in this technique, the lateral solder control surface 2.3 also be executed.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 4406499 A1 [0002]
• DE 102005053876 A1 [0003]

Claims (10)

Sensor unit for a motor vehicle for mounting on a printed circuit board and means for damping the transmission of high-frequency interference to the sensor element, characterized in that the sensor unit is a spatial, injection-molded plastic carrier ( 1 ), which with one side on the circuit board ( 4 ) can be arranged and on opposite side of the sensor element ( 3 ) is arranged and the plastic carrier at least one electrical contact ( 2 ) from the sensor unit to the circuit board. Sensor unit according to claim 1, characterized in that the electrical contacts of the plastic carrier to the printed circuit board ( 4 ) as SMD-solderable area contacts ( 2.4 ) are formed. Sensor unit according to claim 2, characterized in that the electrical contacts of the plastic carrier each have a lateral solder control surface ( 2.3 ) for an automatic optical inspection of the Lotstelle. Sensor unit according to one of the preceding claims, characterized in that the plastic carrier at least one cavity ( 1.2.a . 1.2b ), wherein preferably by the number, size, shape and position of the at least one cavity, the damping characteristic is set. Sensor unit according to one of the preceding claims, characterized in that the electrical contacts ( 2 ) are made with the plastic carrier as a two-component injection molded part, wherein the electrical contacts ( 2 ) are produced by an electrically conductive admixture in the plastic of these electrical contacts and the plastic of the base body ( 1.1 ) of the plastic carrier in contrast is non-conductive. Sensor unit according to one of the preceding claims 1 to 4, characterized in that the electrical contacts ( 2 ) are carried out as metallizations on the surface of the plastic carrier and are guided from the side facing the printed circuit board via at least one side wall extending at right angles to the side of the plastic carrier facing the sensor element. Sensor unit according to one of the preceding claims 2 to 6, characterized in that the sensor element is contacted via an electrically conductive adhesive on the plastic carrier, wherein the adhesive is reflow solder resistant, that the sensor unit ( 3 ) can be fastened by reflow soldering on the printed circuit board together with further SMD components to be mounted on the printed circuit board. Plastic carrier for a sensor unit according to one of the preceding claims. Method for producing a sensor unit according to one of the preceding claims, a plurality of plastic carriers via in each case at least one predetermined separation point ( 1.4 ) is produced in a strip form connected to each other and fitted in this strip form with the sensor elements and before mounting the sensor unit on the circuit board in each case a sensor unit from the strip shape by separating the predetermined separation point (s) is cut free. Method for mounting a sensor unit according to one of the preceding claims on a printed circuit board, in which the sensor unit ( 3 ) with the plastic carrier ( 1 ) on corresponding SMD solder pads of the printed circuit board ( 4 ) and together with other to be mounted on the PCB SMD components ( 5 ) is fixed by reflow soldering and electrically connected.

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