Besides the selection of the most suitable contact materials , the design and typeof attachment is critical for the reliability and electrical life of contactcomponents for electromechanical switching devices. The materials most important factors here are the material-saving useof high cost precious metals and the most economic economical manufacturing method forcontact parts are most important factors..

There are two basic manufacturing solutions available: One can start with singlecontact parts , such as contact rivets or tips , which then are attachedmechanically or by brazing or welding resp. to carrier parts. In the second case, a base material coated or clad with the precious contact metal - for specialapplications also clad with another non-precious material – in the form of stripsor profiles is manufactured as a semi-finished pre-material from which thecontact components are then stamped and formed. Besides mechanicalcladding other processes such as electroplating and deposition from the gasphase are utilized.Which of the following manufacturing processes is finally chosen , depends onthe final application of the contact components in their respective switchingdevices or electromechanical components. Other considerations , such as therequired number of electrical operations, the most economical use of preciousmetals and the anticipated volumes of parts are also important for the processselection.

===3.1 Manufacturing of Single Contact Parts===The group of single contacts includes contact rivets, contact tips, and formedparts such as weld buttons. Contact spheres (or balls) are today rarely usedbecause of economical considerations. <br>Main Articel: [[3.1 Manufacturing of Single Contact Parts| Manufacturing of Single Contact Parts]]

===3.2 Manufacturing of Semi-Finished Materials===Semi-finished contact pre-materials can be manufactured from solid preciousmetals, precious metal alloys, or precious metal containing composite materials. <br>Main Articel: [[3.2 Manufacturing of Semi-Finished Materials | Manufacturing of Semi-Finished Materials]]

===3.3 Main Articel: [[Attachment of Single Contact Parts===The following segments give an overview | Attachment of the usually applied attachmenttechnologies for contact parts to carrier components. They include mechanicalas well as brazing and welding methods used for electrical contact assemblies.Single Contact Parts]]

Main Articel: [[3== Evaluation of Braze or Weld Joints==The switching properties of brazed and welded contact assemblies is strongly dependent on the quality of the joint between the contact and the carrier.3 Attachment The required high quality is evaluated through optical methods, continuous control of Single Contact Parts | Attachment relevant process parameters and by sampling of Single Contact Parts]]finished products.

==Stamped Contact Parts==Stamped electrical contact parts typically consist of a base carrier material to which a contact material is attached by various methods (<xr id="fig:Plated and contact containing pre-stamped strips and stamped parts"/><!--(Fig. 3.4 Evaluation of Braze or Weld Joints===17)-->). The They serve as the important functional components in many switching properties and electromechanical devices for a broad range of brazed electrical and welded contact assemblies is stronglyelectronicdependent on applications. On the one hand, they perform the mostly loss-free electrical current transfer and the quality closing and opening of electrical circuits, while on the joint between other hand, the contact and carriers are important mechanical design components, selected to meet the carrier. Therequired high quality is evaluated through optical methodsrequirements on electrical, thermal, continuous controlof relevant process parameters mechanical and by sampling of finished productsmagnetic properties.

The increasing miniaturization of electromechanical components requires ever smaller stamped parts with low dimensional tolerances. Such precisionstamped parts are needed in the automotive technology for highly reliable switching and connector performance. In the information and data processingtechnology, they transfer signals and control impulses with high reliability and serve as the interface between electronic and electrical components.<figure id="fig:Plated and contact containing pre-stamped strips and stamped parts">[[File:Plated and contact containing pre-stamped strips and stamped parts.jpg|left|thumb|Figure 1: Plated and contact containing pre-stamped strips and stamped parts for different applications]]</figure><br style="clear:both;"/>Main Articel: [[3.4 Evaluation of Braze or Weld JointsStamped Contact Parts| Evaluation of Braze or Weld JointsStamped Contact Parts]]

===3.5 Stamped Contact Parts===Stamped electrical contact parts typically consist of a base carrier material towhich a contact material is attached by various methods ''(Fig. 3.17)''. They serveas the important functional components in many switching andelectromechanical devices for a broad range of electrical and electronicapplications. On the one hand they perform the mostly loss-free electricalcurrent transfer and the closing and opening of electrical circuits. In addition thecontact carriers are important mechanical design components selected to meetthe requirements on electrical, thermal, mechanical and magnetic properties. The increasing miniaturization of electromechanical components requires eversmaller stamped parts with low dimensional tolerances. Such precisionstamped parts are needed in the automotive technology for highly reliableswitching and connector performance. In the information and data processingtechnology they transfer signals and control impulses with high reliability andserve as the interface between electronic and electrical components. Fig. 3.17:Plated and contactcontaining pre-stamped strips andstamped parts for differentapplications ===3.5.1 Types of Stamped Parts===Stamped parts are produced as single pieces, in pre-stamped strip and combconfigurations. Depending on the requirements and application the contact andbase material as well as the coating and attachment technology is carefullyselected. *Coated stamped partsStamped parts can be selectively or completely coated with precious metalcontaining materials based on gold, palladium, and silver as well asnon-precious materials such as tin, nickel and copper ''(Fig. 3.17)''. For stampedparts in high volumes like those used as electrical components in automobilesthe carrier material is mostly coated in a reel-to-reel process starting with eithersolid or pre-stamped strips (see also chapter 7.1.1.3). Frequently the prestampedstrip will be used directly in further automated assembly of the finishedfunctional component. As an alternative finished stamped parts can beelectroplated using barrel and rack plating methods. Very thin coating layers with tight tolerances are deposited by electroplating. Formany applications the high mechanical wear resistance is advantageous. Sinceeven very thin layers are mostly pore-free, these coatings also act as aneffective corrosion inhibitor. The type of coatings, the sequence of multiplelayers, and the coating thickness, for example for connectors, are chosenaccording to the requirements for the end application. *Clad stamped parts For many applications thicker precious metal surfaces or AlSi layers arenecessary. These cannot be deposited by electroplating. Besides meltmetallurgicallyproduced materials on the basis of gold, palladium and silver,also powder-metallurgical materials are required frequently. The metallurgicalbond between these contact materials and the mostly copper based substratesis achieved through various mechanical cladding methods (see also chapter3.2.1). In this way also aluminum clad strips are manufactured in which thealuminum layer serves as the bondable surface in the interface betweenelectromechanical connections and electronic circuits. These clad semifinishedmaterials can be further fabricated into pre-stamped strips, in combform, or single stamped parts ''(Fig. 3.18)''. Fig. 3.18:Examples of clad stamped parts *Welded stamped parts Welded stamped parts can be fabricated by various methods (see also Chapter3.3.3). Single contact pieces can be attached to pre-stamped or finishedstamped strips as weld buttons and wire or profile segments by electricalresistance welding. Contact parts can also be stamped from seam-weldedsemi-finished strip. Fitting the end application contact materials based on gold,palladium and silver. Depending on the contact material and the design of thefinished contact component the contact bottom surface may be consist of aweldable backing material. *Brazed stamped parts Brazed stamped contact assemblies are manufactured by two joining methods(see also chapter 3.3.2). The contact material is either attached by resistanceor induction brazing to base metal carriers as prefabricated contact tip or theyare stamped from brazed semi-finished toplay strip. It is typical for brazedcontact parts that the contact material consists of silver based contact materialand a good conducting copper base material with larger cross-sectional areafor the usually higher current carrying capacity. *Stamped contact parts with rivets Riveted stamped contact parts are manufactured with the use of contact rivetswhich are transferred over suitable feed mechanisms correctly oriented intoholes punched into the carrier ''(Fig. 3.19)''. Frequently also wire or wire segmentsresp. are used which are subsequently coined and formed into the desiredcontact shape (see also chapter 3.3.1). Both attachment methods have theirdistinct advantages. Using composite or tri-metal rivets allows limiting the useof precious metal custom tailored to the volume needed for specific switchingrequirements. For wire staking the precious metal usage is usually higher butthe staking can be performed at significantly higher production ratesand the additional rivet making step is eliminated. Fig. 3.19:Examples of riveted stamped parts *Pre-mounted component stamped parts Components stamped parts consist of a minimum of two carrier parts whichdiffer in their material composition and geometrical form and the contactmaterial''(Fig. 3.21)''. The assembly of these components as single pieces or stampingprogressions is performed in a stamping die by riveting or coining. To increasethe current carrying capacity at the joining area an additional welding step canbe added. Depending on the requirements the different properties of the twocarrier components can be combined. As an example: the high electricalconductivity of a contact carrier blade is joined with the thermal or mechanicalspring properties of a second material to form a functional component. For thisprocess both carrier base materials can also be coated with additionallayers of other functional materials. Fig. 3.20:Examples of pre-mounted stampedcomponent parts Stamped parts which are insert molded into or combined with plastic parts areused in electromechanical components (see Chapter 10). ===3.5.2 Stamping Tools===For the design of stamping tools the latest CAD software systems are used.Modern stamping tools usually employ a modular design with integrateddimensional and functional controls ''(Fig. 3.21)''. Depending on the requirementson the parts and the volumes they are built with steel or carbide (-steel) insertswhich are coated with a wear resistant material such as for example TiN forlonger life. A special stamping process is precision stamping for contact parts made fromthin strip materials with thicknesses in the range of 0.05 – 2.5 mm. With highcapacity stamping technology up to 1400 strokes/min can be reached for highvolume parts. During the actual stamping operation frequently other processessuch as thread-forming, welding of contact segments and insertion and formingof contacts from wire segments are integrated. Depending on the productionvolumes these operations can also be performed in multiples. The quality of the tools used for stamping, like progressive dies and stamp-formingtools is important for the final precision and consistency of the parts. During highspeed stamping the tools are exposed to extreme mechanical stresses which mustbe compensated for to ensure the highest precision over long production runs. Withsuch high quality progressive dies parts of high precision with a cutting width of lessthan the material thickness and with strict quality requirements for the cutting surfacescan be manufactured.To ensure the highest demands on the surface quality of precision contact parts quiteoften vanishing oils are used as tool lubricants. Cleaning and degreasing operationscan also be integrated into the stamping process. Additionally most stamping linesare also equipped with test stations for a 100% dimensional and surface qualitycontrol.During the design of stamping tools for electrical contacts minimizing of processscrap and the possibility to separate the precious metal containing scrap must beconsidered. Fig. 3.21:Progressive die for stamped contact parts[[Category:Manufacturing Technologies for Contact Parts|Category]] ===References===

th Proc. 24 ^th Int. Conf.on Electr. Contacts, Saint Malo, France 2008, 206-209