DE102015004651B4 - Method for coating a component and use of the method - Google Patents

Abstract

Method for coating a component (2), in particular an electrical contact element, in which a coating (4) is applied to the component (2), which has a first material structure (M1) after application, and subsequently in a conversion region ( 6a), which comprises at least a partial region of the coating (4), a microstructure transformation is carried out on the coating (4), the coating (4) having a second material structure (M2) after the microstructure transformation, wherein the conversion region (6a) in FIG Small areas (8a-h) is divided, and the microstructure conversion takes place only in one of the small areas (8a-h) within a respective short-term period (Ta-h), outside of the respective small area (8a-h) within the short-term period (Ta h) no structural transformation takes place, characterized in that - as component (2) a connector with a press-fit zone (10) is used, and - at least one of the small regions (8a-h) is chosen such that it corresponds to the press-in zone (10) or a part of the press-in zone (10), and- as a component (2) such with an edge (12) is used, and- at least one of the small areas (8a-h) is selected such that it corresponds to an edge region (14) or a part of the edge region (14).

Description

The invention relates to a method for coating a component and the use of such a method.

In the field of strip electroplating, there is often the need in practice to treat electroplated strips after electroplating, ie after completion of the galvanic treatment, in such a way that the coating, ie the tin layer, melts. In general, the entire surface or coating is heated. The heat sources used include infrared radiators, hot air blowers or inductors. Often, however, there is a need to melt only partial areas of the galvanic coating in order to obtain the galvanic crystallization structure of the coating in other areas. The aim of a structural transformation, in particular in the form of a reflow process, is to produce a coating or layer with solidification structure from the melt, ie the molten coating, which is low in internal stresses and has an intermetallic phase which has grown at an accelerated rate. In connectors so low insertion and pulling forces are achieved and ensures a low tendency to form whiskers. For example, a reflow process with the aid of hot air blowers from the company "HAPRO Industriegeräte GmbH Solingen", Solingen, is known from practice.

From practice it is known to perform the machining of the material or the coating in two operations. In a first operation, the area of the coating that is to be remelted, ie the reflow layer or coating is applied galvanically and remelted after completion of the galvanic processing. Thereafter, in a second operation or run, the remaining area of the coating, which is to remain in the galvanic structure, is electroplated and not remelted. Due to the often good thermal conductivity of the base material such processing, depending on the melting temperatures of the coatings, rarely in a single operation possible.

From the publication DE 10 2010 042 526 A1 is a contact element of a base material having at least one conductive layer thereon made of indium or indium with an admixture or alloy of at least one of the group of elements containing copper, silver, gold, bismuth, nickel, antimony, palladium , Iron, carbon and phosphorus.

From the DE 10 2011 000 984 A1 and the EP 1 788 585 A1 For example, methods for refining a metallic coating by laser are known.

The "press-fit technology" known from practice in the automotive industry is a very reliable technique for electrically connecting or contacting electrical components, in particular connectors and circuit boards. For environmental reasons, a transition from lead-containing materials to pure tin materials has been carried out in the past. A significant problem with pure tin materials is whisker formation, ie the formation of tin chips, which can cause short circuits in the electrical system. Indium as a soldering aid has long been known in practice. It is known to apply indium in any form, but usually by electroplating, on a component. Subsequently, the indium coating is raised above its melting temperature of e.g. 150 degrees Celsius remelted. Thus, a microstructure transformation or a reflow in the indium coating is achieved.

The object of the invention is to provide an improved method for coating a component and to provide an improved use of the method.

With regard to the method, the object is achieved by a method according to claim 1. Preferred or advantageous embodiments of the invention will become apparent from the dependent claims, the following description and the accompanying drawings.

The method is used to coat a component, wherein the component is in particular an electrical contact element. In the method, a coating is applied to the component. After application, the coating has a first material structure. Subsequently, an area of the coating is selected as the conversion area. In this conversion region, a microstructure transformation is performed on the coating. The conversion region here comprises at least a portion of the coating or the entire coating. After the microstructure transformation, the coating has a second material structure in the conversion region. In the possibly remaining area of the coating, this further has the first material structure.

In the method, the conversion area is divided into small areas. The microstructure transformation takes place only in one of the small areas and within a respective short-term span. Outside the respective small area no structural transformation takes place within the short-term span. In particular, so the Dimensioning of the small area and the short-term span as a function of each other such that outside the small area, the previous material structure of the coating is maintained within the short-term span. The structural transformation in the small area is thus independent of the remaining coating, that is, the structural transformation there does not affect the rest of the coating.

In this case, the small area can also be an incoherent area, that is, the structure transformation can take place simultaneously at several locations or areas during the short-term span. In their respective environment, however, no conversion of the coating takes place during the short-term span.

If the microstructure transformation is completed in one of the small areas, it will be completed during a subsequent, i.e. later short-term span performed in another of the small areas. This is repeated until all small areas and thus the entire conversion area have been completed. Small areas can also be edited multiple times within the same or different short periods. The short-term spans can be selected differently or equally long. The small areas can be chosen differently or equally large.

In the microstructure transformation, the melting temperature of the coating is exceeded. However, due to the coordinated dimensioning of small area and short-term span, the melting temperature is only exceeded locally in the small area and only briefly during the short-term span for structural transformation, so that this is sufficient in the small area just for structural transformation. The remaining material, so the remaining coating outside the small area and the rest of the component itself are only slightly thermally stressed during the short-term.

The process provides a locally and temporally selective reflow process so that reflow within the small areas can be carried out independently of the residual coating in a plant process. Compared to a conventional large-scale or general conversion of a coating, the microstructure transformation or an energy input necessary for this purpose takes place for a short time or quickly and in a targeted or accurate location. Residual material, that is, the remaining coating, outside the respective small area and outside of the conversion area, as well as the component or to be coated base member itself, are only slightly thermally stressed, which is advantageous in terms of mechanical properties of the remaining coating and the base member, there are no changes to be expected here.

When providing accurate mechanical guidance, components may be processed statically or in a continuous manner as described.

As a component, a connector with a press-fit zone is used. At least one of the small areas is then selected so that it corresponds to the press-in zone or corresponds to a part of the press-in zone. The component is therefore in particular an element or contact element of a connection device in press-fit technology. The press-in zone comprises in particular one or more punched edges of the component. The press-in zones are or are located, for example, on pins. By the method succeeds a precise and precise microstructure transformation in the press-in zone, so that there is a high-quality coating material is made available there, which is converted in terms of its structure without, for example, melt or migrate or significantly change in shape. Thus, the press-in zone remains completely and high-quality coated even after structural transformation. As a result, an improved press-fitting behavior is achieved.

As a component such is used with an edge. At least one of the small areas is selected so that it corresponds to an edge area or a part of the edge area. As explained above for the press-in zone, in particular in the edge region, the result is that no migration of coating material takes place and the edges remain well wetted with coating material even after the structural transformation. For example, cutting edges on components do not dewet or only slightly. Especially for contact pins this is necessary in the edge area, if the coating serves as a sliding coating for easy insertion and removal of the pins. In particular stamped components have such edges, as components are thus used in particular stamped components.

In a preferred embodiment, the coating is applied to the component by a plating process. After the galvanization, the coating material has the first material structure, which is to be converted into a second material structure, as a rule only in regions, namely in the conversion region, by structural transformation. For a galvanized component, therefore, the inventive method is particularly well, since it can make the structural transformation locally in one operation, without the to convert the remaining coating outside the conversion area.

In a preferred embodiment, the microstructure transformation is carried out by a heat source, which enters only locally limited heat on the component. The local limit refers to the small area or part of the small area. By an appropriate heat source, the aforementioned method can be carried out particularly well, since only in the small area, the melting temperature of the coating is exceeded and the microstructure can only take place there, with surrounding areas of the small area are not heated appropriately and there the melting point is not exceeded and thus also no structural transformation takes place.

In a variant of this method, a laser arrangement is used as the heat source. In particular, the laser arrangement has a pulsed infrared laser. In particular, the laser operates to have an angle of incidence between 5 degrees and 90 degrees on the small area. A laser arrangement or a laser beam is particularly suitable for punctual or localized introduction of heat and for the brief introduction of heat and is therefore particularly well suited for the process. The laser beam can be dimensioned with such a small diameter that it covers at most the small area or only part of the small area and still ensures sufficient heat input. The angle at which the laser beam strikes the surface can vary between 5 degrees and 90 degrees, depending on the application.

According to the invention, therefore, the use of a laser as a very precise heat source with respect to locality and amount of energy, especially in the reflow of surfaces or coatings in press-fit zones of connectors, also to avoid dewetting of the functionally important punched edges.

In a further variant of the method, a laser source with a deflection scanner is used as the laser arrangement. The deflection scanner sweeps the small area at least once, especially several times during the short-term span. The impact location of the laser or the beam cross-section is in particular smaller, in particular substantially smaller, in particular orders of magnitude smaller than the small area and is guided over the small area by means of the deflection scanner so that it is successively swept one after the other within the short-term span at least once by the laser beam. By such a laser arrangement, a particularly well localized and temporally limited heat input into the small area during the short-term period is possible without significantly heating surrounding areas.

In particular by means of a pulsed infrared laser and an associated scanner, the energy input into a coating takes place so rapidly and so precisely that the area in which - for the purpose of microstructural transformation - the melting temperature of the coating is exceeded can be limited very precisely, especially on stamped parts.

In a preferred embodiment of the method, the coating used is an indium or indium-containing coating. In particular, indium alloys are used as a coating. Indium alloys are particularly suitable as a coating for the press-fitting or for such components, since indium (containing) coatings are prone to whisker formation. As explained above, these processes can advantageously be microstructured by the method, as a result of which whisker formation is reduced.

In particular, a melting of indium (containing) layers in the press-fitting of automotive connectors is possible by the invention.

With regard to the use of the object of the invention is achieved by a use of the method described above for a component of a connecting device in the press-fitting. In particular, in the press-fitting, it is important to coat components, especially at the press-in edges sufficiently, the coating is carried out in particular by electroplating and subsequent structural transformation.

By using the method according to the invention, particularly good components for the press-fitting technique can be produced here, since, for example, edges and press-in areas are not dewaxed by the coating or the geometric shape of the coating does not change or changes only insignificantly for the purpose of the press-fit technique.

In an alternative embodiment, the method is used for structural transformation by reflow at a conversion region, wherein the transformation region is a coating of a coating of a press-fit zone of a connector. In particular, in the press-in zone, which represents a crucial zone for corresponding connectors, the use of the method according to the invention results in a high-quality structural transformation as described above.

In an advantageous embodiment, the method is used for a microstructure conversion of an indium or indium-containing layer as a coating in the press-fit technology for connectors in the automotive sector. Particularly in the automotive sector, high-quality connectors are required, in particular in the press-fit technique, which have a layer-converted indium (containing) layer as the coating. By the method according to the invention, the above advantages also result for the corresponding connector.

• 1 ein Bauteil mit Beschichtung,
• 2 ein alternatives Bauteil mit alternativer Beschichtung und Laseranordnung.

Further features, effects and advantages of the invention will become apparent from the following description of a preferred embodiment of the invention and the accompanying figures. This shows in a schematic outline sketch:

• 1 a component with coating,
• 2 an alternative component with alternative coating and laser arrangement.

1 shows an indicated component 2 , Here is a component in the form of a plug of a connecting device in press-fit technology in the form of a connector in the automotive field. The component 2 is an electrical contact element in the form of a contact pin. On the component 2 First, a coating is galvanically applied 4 applied by means of a galvanization process, which after application of a first material structure M1 having. The coating 4 is an indium coating, alternatively an indium-containing coating. The coating 4 is a coating 4 in the press-fit technology for connectors in the automotive sector. In a conversion area 6a the coating 4, here only a portion of the entire coating 4 Subsequently, a microstructure transformation takes place on the coating 4 performed. The microstructure transformation takes place in the form of a reflow at the transformation area 6a , After microstructural transformation, the coating shows 4 in the conversion area 6a a second material structure M2. The rest of the area 6b the coating 4 remains untreated, that is, retains its first material structure M1 ,

The structural transformation becomes the structural transformation 6a divided into parts, namely small areas 8a-h. The structural transformation takes place at one time only in one of the small areas 8a-h. In each of the small regions 8a-h, the texture transformation takes place in a respective short-term span Ta-h. Within one of the short periods Ta - h, only one of the small areas 8a-h is converted. In the remaining small areas 8a-h no structural transformation takes place at this short-term span. Thus, in the short time period Ta, the small area 8a is converted. Subsequently, in the short-term span Tb different therefrom, the small area 8b is converted and so on.

The component 2 as a connector has a press-fit zone 10 on, which serves to be electrically contacted by press-fitting with a counterpart, not shown. The small areas 8a-h are chosen so that these parts of the press-fit zone 10 correspond. In the example, the conversion area 6a a coating in the area of the press-in zone 10 of the connector.

The component 2 also has an edge 12 on. In the area of the edge 12 extends an edge region 14 , The small areas 8c and 8d are chosen so that they each have a part of the edge area 14 correspond. When converting the areas 8c and 8d so only structure in the edge area 14 transformed.

2 shows a heat source 16 and schematically again shown alternative small areas 8a - i of an alternative coating 4 on an alternative component 2 , which is also only hinted at here.

The heat source 16 serves to introduce heat into each of the small areas 8a-h at a time or during one of the short-term spans Ta-i , The heat input is locally limited to one of the small areas 8a - i. For example, heat input during the short-term period Ta heats only the small area 8a, so that only there takes place a structural transformation. The remaining small areas 8b-i are not significantly heated so that no structural transformation takes place in them.

In the example, the heat source 16 a laser arrangement 18 , in particular with a pulsed infrared laser. An angle of incidence α of the laser arrangement 18 generated laser beam 24 on the coating 4 is in the example 80 degrees and describes the angle that the laser beam 24 with the tangential plane to the coating 4 at the place of impact. The laser arrangement 18 includes a laser source 20 , which is an always rectified laser beam 24 generated. A deflection scanner 22 The laser assembly 18 directs the laser beam 24 then according to one of the small areas 8a-i and also within the small areas 8a-i from. This is in 2 by a dashed curve of the location of incidence of the laser beam 24 on the coating 4 indicated.

LIST OF REFERENCE NUMBERS

2

component

4

coating

6a

transformation sector

6b

remaining area

8a-i

small area

10

press-fit zone

12

edge

14

edge region

16

heat source

18

laser assembly

20

laser source

22

deflection scanner

24

laser beam

M1.2

material structure

Ta-i

Short period

Claims (9)

Method for coating a component (2), in particular an electrical contact element, in which - on the component (2) a coating (4) is applied, which after application has a first material structure (M1), and then - in a conversion region ( 6a), which comprises at least a partial region of the coating (4), a microstructure transformation on the coating (4) is carried out, wherein the coating (4) after structural transformation, a second material structure (M2), wherein - the conversion region (6a) in Small regions (8a-h) is subdivided, and - the microstructure transformation takes place only in one of the small regions (8a-h) within a respective short-term span (Ta-h), outside of the respective small region (8a-h) within the short-term span (Ta h) no structural transformation takes place, characterized in that - a connector with a press-fit zone (10) is used as the component (2), and - at least one of the small regions (8a-h) is selected such that it corresponds to the press-in zone (10) or a part of the press-fit zone (10), and - as a component (2) with an edge (12) is used, and - at least one of the small areas (8a-h) is selected such that it corresponds to an edge region (14) or a part of the edge region (14). Method according to Claim 1 , characterized in that the coating (4) is applied to the component by a galvanization process. Method according to one of the preceding claims, characterized in that the microstructure transformation by a on the component (2) on the small area (8a-h) locally limited heat-carrying heat source (14). Method according to Claim 3 , characterized in that a laser arrangement (16) is used as the heat source (14); in particular with a pulsed infrared laser, in particular at an angle of incidence (α) on the small area (8a-i) between 5 ° and 90 °. Method according to Claim 4 , characterized in that a laser source (18) with a deflection scanner (20) is used as the laser arrangement (16), wherein the deflection scanner (20) sweeps over the small area (8a-i) during the short-term period (Ta-i). Method according to one of the preceding claims, characterized in that as coating (4) an indium or indium-containing coating is used Use of a method according to one of Claims 1 to 6 for a component (2) of a connecting device in the press-fit technique. Use after Claim 7 for a structural transformation by a reflow at the conversion region (6a), which is at least part of a coating of a press-in zone (10) of a connector. Use according to one of Claims 7 or 8th for a structural transformation of an indium or indium-containing layer as a coating (4) in the press-fit technology for connectors in the automotive sector.

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