DE102015111336A1 - Coating of stampings using plasma coating techniques - Google Patents

Abstract

The present invention relates to a method for producing a plastic-metal composite assembly, comprising the steps of: providing a flat metal stamping tape with a plurality of contiguous punching elements, transporting the metal stamping tape through a first processing region in which at least portions of the stamping elements coated with a coating material, in particular noble metal, using a plasma coating method, and further transport of the coated punching elements through a second processing region, in which at least a portion of the coated stamping elements is encapsulated with plastic.

Description

The present invention relates to a method for producing a plastic-metal composite assembly.

Plastic-metal composite assemblies are already widely used in a variety of areas, especially in the automotive sector. Such a composite assembly generally consists of a metal element and a plastic element that envelops at least portions of the metal element. The metal element, which has electrical plug contacts, for example, is usually produced by stamping and forming processes from a stamped strip. The wrapping of the metal element with a plastic is usually carried out by an injection molding process.

In order to improve the properties of the metal element, for example the stamped plug contacts, a coating with a noble metal, for example silver or gold, is usually carried out. For this purpose, a conventional galvanochemical process is used.

One of the problems with this is the local separation between the punching and forming processes and the galvanic coating process. The metal stamping tapes are brought to a galvanizing company after the punching process to make the coating there. Subsequently, the electroplated metal stamping tapes are transsorted back to the punching company to there take the next steps, such as forming and molding with a plastic.

This process is noticeably complex and leads on the one hand to increased delivery times for the finished plastic-metal composite product, as large transport times and lead times are to be included in the galvanizing company, and on the other hand to a dependency on third party companies, the flexible and fast processing of production orders difficult.

Against this background, an object of the present invention is to provide a method for producing a plastic-metal composite assembly, which no longer adhere to the said disadvantages. In particular, a method is to be provided that allows short delivery and production times.

This object is achieved by a method for producing a plastic-metal composite assembly with the following steps:
Providing a flat metal stamping tape having a plurality of contiguous stamping elements,
Transport of the metal stamping tape through a first processing area in which at least portions of the punching elements are coated with a coating material, in particular noble metal, using a plasma coating method, and
Further transport of the coated metal stamping elements through a second processing area in which at least a portion of the coated metal stamping elements are encapsulated with plastic.

In other words, the steps of coating and overmolding the punching tape are concatenated with a plastic so that both steps are performed in a unitary continuous process. Consequently, the metal stamping tape does not have to be removed from the process chain after punching and transported back and forth to a galvanic operation. The entire process steps, such as stamping, coating, forming and overmoulding, can be carried out directly one after the other in the same production environment. The integration of the coating process into the overmoulding of the punched strip makes the assembly highly precise and reduces the risks due to interrupted or delimited production processes. Thus, not only start-up waste and energy but also labor and set-up times are saved by the inventive method. In addition, storage space and capital costs are significantly reduced.

By using a plasma coating process, the previously required local separation of stamping and electroplating processes can be eliminated, so that the integration in a uniform production process is possible. In addition, the inventors have discovered that coating the metal stamping tape using a plasma coating process results in surfaces which can be overmoulded with plastic in a subsequent step. The plastic material adheres particularly well to the plasma-coated surfaces in comparison to galvanically coated surfaces.

For this reason, it is precisely the combination of plasma coating process and plastic extrusion in a uniform process chain that is advantageous.

In a preferred embodiment, a transport of the metal stamping tape is performed by a third processing area, which lies between the first and the second processing area and in which the metal stamping tape is formed. Preferably, at the end of the third processing area, the contiguous punching elements are separated from the punching belt. Alternatively, at the end of the second processing area, the contiguous punching elements are separated from the punching belt.

In other words, the overmolding of the stamped elements takes place either before or after the singulation.

In a preferred embodiment, the punching tape is cleaned before coating, in particular cleaned by means of plasma.

More preferably, the metal stamping tape is unwound from a roll.

In a preferred embodiment, the first processing area is preceded by a further processing area in which the metal stamping tape is punched in order to produce the stamped elements.

This measure has the advantage that the entire process of punching of the stamping elements, coating and encapsulation can be carried out in a continuous process without interruption.

In a preferred embodiment, the coating material contains gold or silver. Of course, several different precious metals can be used as a coating material.

In a preferred development, the processing region has a high-vacuum section and in each case a pre-vacuum section before and after the high-vacuum section.

More preferably, the plasma coating method comprises a sputtering method.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings. Showing:

1 a schematic representation of a portion of a punching tape;

2 a perspective schematic representation of the punching tape after a forming step;

3 a schematic representation of a plant for producing a plastic-metal composite assembly; and

4 a schematic representation of a plant for producing a plastic-metal composite assembly according to another embodiment.

So-called plastic-metal composite assemblies have long been known and are increasingly used in the automotive sector but also in other areas. The big advantage of such composite assemblies is that the stamped metal elements are encapsulated with plastic, so that a high degree of integration is possible. The stamped metal elements are generally used as electrical conductors and include, for example, plug contacts in a variety of forms.

In order to improve the properties of the base material of the punching elements produced from a stamped strip, for example in electrical terms, at least portions of a stamped element are coated with one or more noble metals. Gold or silver are typical coating materials that significantly improve the electrical properties of, for example, a plug-in contact.

The coating with a precious metal was previously in a galvanic process, which was locally and temporally decoupled from the other processes for producing the plastic-metal composite assembly. The present invention now takes a different approach and reunites the various processes in time and place to achieve a continuous "inline" manufacturing process. The production of a plastic-metal composite assembly can now be done with a single system from punching the punching tape to encapsulation with plastic and dicing.

In 3 exemplified such a system is shown schematically and with the reference numeral 10 characterized. The attachment 10 includes at least a first processing area 12 in which a coating takes place, and a second processing area 14 , in which the encapsulation with plastic is performed. The second editing area 14 joins the first editing area 12 directly or indirectly (as viewed in the direction of production).

At the in 3 shown attachment 10 is between first and second processing area 12 . 14 a third processing area is provided, in which a transformation of the coated punching elements takes place.

Finally, the attachment points 10 still a fourth processing area 18 in front of the first processing area and a fifth processing area 20 that is attached to the second editing area 14 followed.

In the fourth processing area 18 The direct provision of an already punched flat punched tape from a roll. Alternatively, in the fourth processing area 18 punched an unprocessed punching tape and then the first processing area 12 provided.

In the fifth editing area 20 a separation and / or separation of the individual plastic-metal composite assemblies can take place.

The first editing area 12 in which the coating takes place comprises a plasma coating device 22 , which makes a coating with a noble metal using a plasma. Plasma coating processes are generally known as such, so that the details and the technical equipment required for this need not be discussed further.

At the present plant 10 For example, a sputtering method which is carried out in a high vacuum is preferably integrated into the plasma coating. This coating method is also referred to as vacuum plasma spraying.

It will be understood, however, that other plasma coating methods may also be used. Basically, in a plasma coating process, the coating material is extracted from a plasma by the action of an electric voltage. As already mentioned, plasma coating methods can be combined with so-called sputter coating methods, the essence of a sputter coating being that the element to be coated is brought into the vicinity of a so-called target, so that the atoms ejected from the target condense on the element and a layer can form

The in the plant 10 provided plasma coating device 22 includes a high vacuum chamber within which the plasma coating occurs. In front of and behind the high-vacuum chamber 24 each is a pre-vacuum chamber 26 intended.

Within the high vacuum chamber 24 upstream prevacuum chamber 26 is a cleaning device 28 provided, which uses a plasma cleaning process in the present case.

The attachment 10 works as follows: In the fourth editing area 18 that is at the beginning of the plant 10 , a flat metal stamping tape [Note: Here, examples of metals used should be given] is provided on a roll. A section of a punching tape is shown schematically in FIG 1 represented and with the reference numeral 30 characterized. The punching tape 30 in 1 is already stamped and has a plurality of successive individual punching elements 32 on. The successive punching elements 32 are later separated, for example, along a dashed line L from each other. Each of the punching elements 32 has contact areas, for example 34 , which later allow a connection, for example with a plug contact.

The already processed punching tape 30 with the punching elements 32 will be in the fourth editing area 18 unwound from a roll and the first processing area 12 fed. That is, the punching tape is first in the pre-vacuum chamber 26 arrives and is cleaned there with the cleaning device. Then the punching tape arrives 30 that is the punching elements 32 in the high vacuum chamber 24 in which the plasma coating then takes place with a noble metal, for example gold or silver. The coating can be carried out selectively or completely. In other words, that means, for example, only the contact areas 34 be selectively coated. The coating is all around, so that both the top and the bottom of the contact areas and the side edges are coated. Of course, also the entire punching element 32 be coated if necessary.

After coating in the first processing area 12 gets the punching tape 30 in the subsequent fore-vacuum chamber 26 and then into the third editing area 16 ,

In this third editing area 16 can be carried out a transformation of individual elements of the punching element. In 2 is exemplified the result of such a deformation of a punching element. It can be seen in 2 that the contact areas 34 have undergone a deformation such that they have been bent 90 °.

Of course, other forming steps can be carried out on the punching elements.

Then the coated and formed punching element, which is still part of the punching tape, arrives 30 is in the second editing area 14 , There is an encapsulation of the punching element or individual areas thereof with a plastic. For this purpose, within the second processing area 14 an injection molding device 36 be provided.

After encapsulation in the injection molding apparatus 36 becomes the punching tape with the punching elements 32 in the fifth processing area 20 transported, in which a separation and / or separation of the punching elements 32 from each other, so that at the end of the plant 10 the finished plastic-metal composite assembly is present.

It turns out that the entire process, in particular the coating and the subsequent encapsulation with plastic, can take place in a continuous "inline" process. It is no longer necessary, for example, in the fourth processing area 18 supplied punching tape to a locally separate electroplating process and then bring the coated punching tape back to the overmolding.

In addition, the inventors found that the plasma coating process, that in the first processing area 12 is executed, an extremely good preparation for the injection molding in the second processing area 14 represents. The plastic material adheres much better to the plasma-coated surfaces than to electroplated coatings.

Alternatively to the provision of an already punched punching tape 30 in the fourth processing area 18 It is also conceivable to provide in this processing area a punching device, which is fed to an unpunched punching tape and then the punched punching tape 30 with the punching elements 32 the first editing area 12 provides. This embodiment again increases the degree of integration of the plant and makes the entire manufacturing process even more efficient.

In 4 is a variant of the plant 3 represented and with the reference numeral 10 ' characterized. To avoid repetition, the same reference numerals are used for the same parts, so that reference can be made to the above.

The difference of in 4 shown attachment 10 ' consists essentially in the design of the third processing area 16 that by the reference 16 ' is marked. In this third editing area 16 Now not only the transformation of the punching elements takes place 32 , but also the separation, for example along the dividing line L and the loading of the individual punching elements 32 in an injection mold of the injection molding apparatus 36 in the second processing area 14 ,

At the end of the plant 10 ' that is, at the end of the second processing area 14 , then is already the finished assembly, so that no separation is necessary at this position.

Incidentally, the system works 10 ' in the editing areas 12 . 14 and 18 just like the system 10 according to 3 ,

Overall, it is shown that compared to the previous methods for coating and subsequent encapsulation of stamped elements for the production of so-called plastic-metal composite assemblies a significant simplification and improved quality is achieved because on the one hand, the entire manufacturing process is continuously "inline" executable, so that no more transport and storage costs incurred. On the other hand, the plasma coating process provides a very good basis for the subsequent injection molding process, so that the quality of the composite of plastic and metal is very high.

Claims (11)

 Method for producing a plastic-metal composite assembly, with Providing a flat metal stamping tape having a plurality of contiguous stamping elements, Transport of the metal stamping tape through a first processing area in which at least portions of the stamping elements are coated with a coating material, in particular noble metal, using a plasma coating method, and Further transport of the coated punching elements through a second processing area, in which at least a portion of the coated punched elements is encapsulated with plastic.  The method of claim 1, including transporting the metal stamping tape through a third machining area located between the first and second machining areas, and forming the metal stamping tape in this third machining area. The method of claim 2, wherein at the end of the third processing area, the contiguous punching elements are separated from the punching belt.  The method of claim 2, wherein at the end of the second processing area, the contiguous punching elements are separated from the punching tape.  Method according to one of the preceding claims, wherein the encapsulation of the punching tape is carried out by an injection molding process.  Method according to one of the preceding claims, wherein the punching tape is cleaned before coating, in particular cleaned by means of plasma.  Method according to one of the preceding claims, wherein for providing the metal stamping tape is unwound from a roll.  Method according to one of the preceding claims, wherein the coating material contains gold or silver.  Method according to one of the preceding claims, wherein the first processing region has a high-vacuum section and each having a pre-vacuum section before and after the high-vacuum section.  The method of any one of the preceding claims, wherein the plasma coating process comprises a sputtering process.  Method according to one of the preceding claims, wherein the transport of the metal stamping tape is clocked at least through the first processing area.

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