Electric Contact Rivets		Electrical Contact Tips		Recommended Contact Materials for Various Switches

Electrical Contact Tips	Common types of Contact Tips
Design Reference of Internal Oxidation Contact Tips	Design Reference of Powder Metallurgy Contact Tips

Design Reference of Internal Oxidation Electric Contact Tips 1. Properties of Internal Oxidation Electric Contact Tips ： Contact Materials FECC NO. Properties (Scores 1-9 from excellent to poor ) Anti-Erosion Anti-Welding Electrical Conductivity AgCdO D10 5 5 3 D12 4-5 4-5 3-4 D15 4 4 4 X2   1-2 1-2 7-8 X2G 1-2 1-2 7 X3   1-2 1-2 7 NP6 1-2 1-2 7 AgCdOSnO2In2O3 DF15 1-2 1-2 7 AgSnO2In2O3 F11 2-3 4 6 F13 2 3 6-7 Remark: ： 1. The comparison is made for above materials only. 2. Above table is for reference only as switch structures differ from each other. The design should be made according to test result.       2. Normal Dimension Tolerance: (1). The oxidation process will cause the dimension-change after the contact is formed. Thus, except Ag layer tolerance is ± 0.1mm., other tolerances for contact dims. Below 10mm is ± 0.1mm and for contact dims. Over 10mm is ± 0.2mm. (2). The maximum width, length and diameter of contact is within 50mm. The limit of thickness is between 0.7mm~3.0mm.(The thickness and square measure need to be in direct ratio.) For special type contact or contact with over 3.0mm thickness, we suggest to produce the product by powder metallurgy method. Contact with thickness over 3mm is hard to be oxidized. (3). For AgSnO2In2O3 contacts, the dimension suggested as below as the material is liable to be deforming after oxidation process. F Type： Length, Width or Dia. Below 5.0mm: “t” is better between 0.9mm~1.2mm; Length, Width or Dia. Over 5.0mm: “t” is better between 1.2mm~3.0mm R Type ： Length, Width or Dia. Below 10.0mm: “t” is better between 1.0mm~2.0mm: Length, Width or Dia. Over 10.0mm: “t” is better between 1.5mm~2.5mm Remark: The more contact area is, the thicker the contact thickness should be to avoid the deforming due to thickness deficient. 3. Cambered Surface ( R ): (1)  Cambered surface includes： L ong-side camber, short-side camber and sphere camber. Don’t use sphere camber to the utmost. Sphere camber is hard to be produced because of its high hardness. (2) The curvature of cambered surface is easily changed after being heated and oxidized, Thus, it requires larger tolerance. The general tolerance is ± 10R. 4. Corner Radius ( r ): The natural formed corner radius after grinding process of oxidized contact tip is the first option, other wise the normal permissible corner radius 0.3r could be adopted. 5. Brazing Alloy (Solder Backing): (1) Cadmium-free brazing alloy such like BAg-5 & BAg-6 are recommended. But the contacts for MCCB could be brazed with BCuP-5 as MCCB requires less life cycle than other types of switches. (2) The utility extent of brazing alloy depends on the contact area accordingly. (The bigger area is, the larger utility extent shall be.) The brazed area should be over 50% of the contact area. After being brazed, the bonding area should be more 70% of the contact area. The thickness of brazing alloy depends on the material properties. After the welding process, the welding alloy should spills from the contact surrounding closely to be visible (the thickness is between1/2 and 1/3 of the contact thickness). back