Abstract:
The invention relates to an electrical contact, particularly designed as a press-in pin ( 16 ) for a circuit carrier ( 10 ). The press-in pin comprises at least one press-in zone ( 14 ) at which conductor traces ( 30 ) can be contacted. The press-in pin ( 16 ) is either made of solid aluminium material ( 36 ) or contains at least one aluminium material section ( 40 ) or is made of solid aluminium material ( 36, 46 ) with a copper jacket coating ( 48 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    DE 10 2009 042 385 A1 relates to a plug device for electrically connecting a conductor to a circuit board by plugging the plug device directly into a contact hole in the circuit board into a contact opening in the circuit board. For this purpose, the plug device has a fastening region and a transfer region for transferring a current from the conductor to the circuit board. The transfer region or the entire plug device can be produced from aluminum. Automotive applications are cited as the intended use for the plug device, wherein high mechanical loads are present for example and strong currents are transferred. 
         [0002]    DE 10 2005 018 780 A1 discloses a circuit board connector terminal having a stable electric contact with strong retaining force of the terminal. The terminal may be a press-fit terminal or a press-in terminal, which is inserted or clamped in a bus bar for printed circuits or a printed circuit board and is electrically connected to a circuit board. Current is thus transferred from a battery, or electrical signals are transferred without soldering points. The terminal is produced from a conductive material, for example from an aluminum alloy, and is formed by punching and pressing the conductive material. The terminal provides the electrical energy for the bus bar of a circuit in an electric connector box, for example a junction box or a fuse box, and controls electronic elements, such as a fuse or a relay. The bus bar can be provided in an electric connection box which is arranged in a machine room or beneath a vehicle interior. 
         [0003]    DE 10 2009 008 118 A1 discloses a method for producing an electric contact on a circuit board, wherein the contact is produced via a force-fit connection between a press-in pin, which has a press-in zone and a contact region, and a metallized circuit board opening. The entire press-in pin or merely the press-in zone can be formed in a manner coated with aluminum. 
         [0004]    In the case of control devices currently obtainable on the market for automotive applications, peripheral equipment and circuit carriers is/are often connected by means of press-in or insulation displacement connections, or what is known as cold contacting technology (CCT). Cold contacting technology by means of press-in connections constitutes an inexpensive and robust alternative to soldering technology, for example the THT (through-hole technology) method. With use of press-in connections, a blind joint can also be enabled, for example as is necessary when contacting components located in the cover. Copper and various copper alloys, such as CuNiSi and CuSn6, with a suitable end surface, for example galvanic tin, are currently used within the scope of press-in connections by way of cold contacting technology. 
       SUMMARY OF THE INVENTION 
       [0005]    In accordance with the invention, an electric contact, in particular a press-in pin for a circuit carrier, is proposed. The circuit carrier has at least one press-in zone, at which conductive tracks can be contacted. The press-in pin proposed in accordance with the invention can be manufactured from solid aluminum material, or the press-in pin may alternatively contain aluminum material portions, or may also be formed as a press-in pin manufactured from solid aluminum material which is provided with a coating, in particular a roll-clad copper shell coating. In a preferred variant of the press-in pin proposed in accordance with the invention, which is connected by way of cold contacting technology to the circuit carrier, the solid aluminum material can be covered by a galvanic coating in the first variant of the press-in pin. This galvanic coating may be NiAu or Sn, for example. 
         [0006]    In a further variant of the press-in pin proposed in accordance with the invention, said press-in pin is manufactured as a “sandwich” part and for example comprises, sequentially, a resilient region, which is manufactured from copper material and which is pressed in the circuit carrier into the corresponding press-in zone. For example, this first portion of the press-in pin is adjoined by an aluminum portion, within which a deflection zone of the press-in pin is arranged. For example, the term ‘deflection zone’ means a zone of the press-in pin within which the press-in pin experiences a 90° deflection for example and transitions for example from a vertical profile into a horizontal profile. Instead of the specified 90° deflection, the deflection of the press-in pin may also assume other angular profiles depending on requirements and application. 
         [0007]    This Al portion implementing the deflection of the press-in pin can be adjoined in turn by a line portion which is manufactured from Cu or from a Cu alloy. The press-in pin thus constitutes a hybrid component in its second variant. 
         [0008]    In a further, third variant of the press-in pin proposed in accordance with the invention, said pin can likewise be manufactured from solid Al material for example, similarly to the first variant. In accordance with the third variant, a Cu shell coating can be applied to the outer surface of this Al material. This Cu shell coating is preferably applied by way of roll cladding. In accordance with the third variant a press-in pin of which the mechanical properties are to be characterized substantially by the Al material is obtained. 
         [0009]    The resilient region, that is to say the region of the press-in pin in which said pin is pressed into the circuit carrier, is formed by two side walls which are separated from one another by an opening. Due to the resilience of the side walls, these can be mounted for example by ultrasound assistance in the corresponding press-in zones of the circuit carrier, such that oxides can be better separated from the aluminum material. 
         [0010]    The solution proposed in accordance with the invention is characterized in particular in that, due to the use of aluminum instead of copper, or copper alloys, the aluminum material has a lower modulus of elasticity and therefore a lower rigidity than Cu. With identical geometry, improved values in terms of the modulus of elasticity and rigidity compared with copper material are provided. This in turn leads to the fact that thermomechanically induced stresses caused by temperature changes can be better reduced. The press-in pin proposed in accordance with the invention can advantageously still be produced from strip-like material, which accompanies the advantage that tools or proven manufacturing processes do not have to be changed. In order to remove oxides reliably, the press-in pin proposed in accordance with the invention, in its three variants presented above, can be mounted in the corresponding press-in zones of the circuit carrier with ultrasound assistance. 
         [0011]    With regard to the producibility of the press-in pin proposed in accordance with the invention, it is emphasized that an electric contact or a plug connection may require a surface that is resistant to fretting corrosion. A surface of this type can be manufactured for example by finishing the complete strips, that is to say the raw material or partly already stamped-out press-in pins, by means of a galvanically applied coating. The galvanic coating may be, for example, NiAu, Sn, NiPdAu or the like. 
         [0012]    As a result of the solution proposed in accordance with the invention, the robustness or durability of an electric connection produced by way of cold contacting, this robustness or durability being provided by a plug connection between peripheral equipment, structural component and a circuit carrier, can be considerably improved. As a result of the variants according to the present invention, an existing press-in pin portfolio in electronic control units can be replaced or developed. 
         [0013]    The solution proposed in accordance with the invention can be used as media-resistant press-in technology, for example with use in vehicle transmissions, and a cost advantage can be achieved in that the replacement material aluminum can be used instead of copper. 
         [0014]    Due to the hybrid form of the press-in pin, an optimal ratio between the mechanically necessary stability on the one hand and the electrical conductivity required in accordance with the specific application can be achieved. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The invention will be described in greater detail hereinafter with reference to the drawings. 
           [0016]    In the drawings: 
           [0017]      FIG. 1  shows a first variant of a press-in pin proposed in accordance with the invention, produced from solid aluminum material, 
           [0018]      FIG. 2  shows a further, second variant of the press-in pin proposed in accordance with the invention, formed here as a hybrid or sandwich part, and 
           [0019]      FIG. 3  shows a third variant of the press-in pin proposed in accordance with the invention, in which the solid aluminum material is provided with a galvanic coating. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    A first variant of the press-in pin proposed in accordance with the invention made of solid aluminum material can be inferred from the illustration according to  FIG. 1 . 
         [0021]      FIG. 1  shows a circuit carrier  10 , wherein conductive tracks  30  are embedded in the carrier substrate of the circuit carrier  10 . The conductive tracks  30  running within the circuit carrier  10  are connected to contact faces  32 . The contact faces  32  are in turn surrounded by bearing faces  28 , which supplement a press-in opening  12  in the circuit carrier  10 . It is clear from the sectional illustration according to  FIG. 1  that the press-in opening  12  extends continuously through the circuit carrier  10  from the upper face thereof to the lower face thereof. The press-in opening  12  constitutes a press-in zone  14 , into which a press-in pin  16  is pressed. The press-in pin  16  according to the illustration in  FIG. 1  is a press-in pin that is manufactured continuously from aluminum material  36 . The continuous press-in pin  16  manufactured from solid aluminum material is pressed with ultrasound assistance into the press-in zone  14  of the circuit carrier  10 . Oxides can be removed reliably from the aluminum material  36  of the continuous press-in pin  34  due to the ultrasound assistance. In accordance with the first variant of the solution proposed in accordance with the invention, the press-in pin  16  is pressed in by way of cold contacting technology. 
         [0022]    It is clear from the illustration according to  FIG. 1  that the press-in pin has a 90° deflection  18 . This is formed from solid aluminum material  36  of the press-in pin  16 , as can be inferred from  FIG. 1 . At the end of the press-in pin  16  which protrudes into the press-in opening  12  of the press-in zone  14 , the press-in pin  16  has a resilient region  20 . The resilient region  20  is defined in the aluminum material  36  by a first side wall  22  and a second side wall  24 . An opening  26  is present between the side walls  22  and  24 . The two side walls  22  and  24  have resilient properties and contact the contact faces  32  once the press-in pin  16  has been mounted in the press-in opening  12 . The press-in pin manufactured from solid aluminum material  36  illustrated in  FIG. 1  may have a complete or partial galvanic coating. Suitable surfaces are NiAu and Sn, for example. 
         [0023]      FIG. 2  shows a further, second variant of the press-in pin proposed in accordance with the invention, said pin being formed as a hybrid or sandwich part. 
         [0024]    As can be inferred from the illustration according to  FIG. 2 , this press-in pin  16  is a press-in pin that has a Cu spring region  38 , which is adjoined by a deflection region  40  that is manufactured from solid aluminum material and that in turn transitions into a Cu line portion  42 . The geometry of the press-in pin in accordance with the illustration in  FIG. 2  according to the second variant of the solution proposed in accordance with the invention is identical to the geometry of the press-in pin  16  according to the illustration in  FIG. 1 , in which the press-in pin is manufactured from solid aluminum material  36 . 
         [0025]    As shown in  FIG. 2 , the deflection  18  according to the second variant of the press-in pin  16  is likewise arranged in the portion  40  manufactured from aluminum of the press-in pin  16 . The circuit carrier  10  in accordance with the variant according to  FIG. 2  is structured similarly to the circuit carrier  10  according to  FIG. 1 . Conductive tracks  30  run in an embedded manner in the carrier substrate of the circuit carrier  10  and are connected to contact faces  32 , which are surrounded by bearing faces  28 . The bearing faces  28  ultimately delimit the press-in opening  12 , which is arranged within the press-in zone  14  of the circuit carrier  10 . Similarly to the illustration according to  FIG. 1 , the press-in opening  12  extends completely through the circuit carrier  10 , that is to say from the upper face thereof to the lower face thereof. 
         [0026]    In contrast to the illustration according to  FIG. 1 , in the case of the press-in pin  16  according to the second variant, which is illustrated in  FIG. 2 , the Cu spring region  38  is not manufactured from aluminum, but from copper. The aluminum deflection region  40  according to the illustration in  FIG. 2  has the advantage that a lower modulus of elasticity and therefore a lower rigidity with identical geometry compared with copper is provided in the region of the deflection  18 . Thermomechanically induced stresses caused by temperature changes can also be better reduced with the configuration of the press-in pin  16  in accordance with the second variant according to  FIG. 2 . 
         [0027]      FIG. 3  shows a further, third variant of the press-in pin proposed in accordance with the invention made of solid aluminum material having a roll-clad coating. 
         [0028]    It can be inferred from  FIG. 3  that the press-in pin  16  illustrated there is likewise manufactured substantially from Al basic material  36 , but is provided over its entire surface with a shell coating  48 , which for example can be roll-clad from copper. The mechanical properties of the press-in pin  16  according to the variant reproduced in  FIG. 3  are defined substantially by the aluminum material  36 ,  46 . Also in the third variant according to  FIG. 3 , the geometry of the press-in pins  16  is substantially identical to the geometries of the press-in pin  16  in accordance with the variants described above according to  FIGS. 1 and 2 . 
         [0029]    Similarly, a resilient region  20  of the press-in pin  16  is formed and is provided in the region of the opening  26  on the inner side and on the outer side of the first side wall  22  or the second side wall  24  with a shell coating  48 , for example made of copper. The circuit carrier  10  according to  FIG. 3  comprises individual conductive tracks  60 , which are embedded in the interior of the circuit carrier and are electrically connected to contact faces  32 , which are in turn surrounded by bearing faces  28  which delimit the press-in opening  12  of the press-in zone  14  in the circuit carrier  10 . 
         [0030]    It should also be mentioned in conjunction with the variants of the press-in pin  16  according to  FIGS. 2 and 3  that said press-in pin is mounted with ultrasound assistance in the press-in opening  12  of the press-in zone  14 . Due to the use of ultrasound with the cold mounting of the press-in pin  16 , oxides remaining on the aluminum material can alternatively be removed reliably. 
         [0031]    A feature common to all variants of the press-in pins  16  according to  FIGS. 1 to 3  is that the press-in pins  16  can be produced, as previously, from strip-like material. This provides the advantage that tools and a proven manufacturing process can remain unchanged. For the case that a plug connection requires a surface that is resistant to fretting corrosion, the above-mentioned strip-like material or already partly stamped-out press-in pins can be finished by means of a galvanically applied coating. Surfaces of this type that are resistant to fretting corrosion include NiAu, Sn and NiPdAu for example, to name a few. As a result of the press-in pins  16  proposed in accordance with the invention according to the described variants, the robustness and therefore the service life of a connection point can be considerably increased. The connection point may be a connection point that constitutes a plug connection between a piece of peripheral equipment and a component on the one hand to the circuit carrier  10  on the other hand. As a result of the solution proposed in accordance with the invention, an existing press-in pin portfolio in electronic control units can be supplemented advantageously. The solution proposed in accordance with the invention can be used in particular within the scope of media-resistant press-in technology, as is necessary for example with use in transmission control units of vehicles. The replacement material aluminum is used instead of the previously used material copper, whereby material costs can be saved in a significant amount since aluminum is a more cost-effective basic material compared with copper. As a result of the solution proposed in accordance with the invention, thermomechanically induced loads can be damped or reduced, and therefore an electric plug connection, which is produced by way of cold contacting technology, is considerably improved in terms of its durability. It would likewise be conceivable to also provide layer sequences, that is to say a layered composite of Cu, Al, Cu and Al. Instead of Cu and Al, other material pairings are also conceivable in the present context for producing hybrid press-in pins, for example Ni, Cu and Au.