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    Design Reference of Powder Metallurgy Electric Contact Tips  
   

Silver Electric Contact Rivets
   1. Properties of P.M. Electric Contact Tip Material:  
 
Material Series TECC No. Properties (Scores 1-9 from excellent to poor )
Anti-Erosion Anti-Welding  Electrical
 Conductivity
AgNi N30 5 5 3
AgW W50 3 3 5
W65 2 2 7
AgW+WC WK50 3 3 5
AgW K50 3 3 6-7
K60 2 2 7
AgWC+C KC15 7 3 6
KC23 7 2 7
AgC C5 8 2 5
CuW UW60 4 4 7
UW65 3-4 3-4 7
UW70 3 3 7-8
   Silver Electrical Contact Tips
  　
  　

Recommended Silver Contact Materials for Various Switches
  　
  　
  　 Silver Electric Contacts
and Switches
  　
  　
  　 Green (Environmental
Protection) Electric Contacts
  　
   
   
    Links
                
    KITCO
     
    LME
     
    COMEX
     
              China Alloy
     
              China Silver
 
   
Remark: 1. The comparison is made for above materials in table only.
  2. Above table is for reference only as switch structures differ. The design should  
      be finalized in conformity with the test result.  
 

 

The Bullion Desk

The Silver Institute
       
   2. Normal Dimension Tolerance:  

Shanghai Nonferous Metals 
 
   
(1). The dimension range of length, width or diameter of powder metallurgy contact is
  normally between 3.5mm ~ 85mm.
(2). Contact of AgNi, AgWC+C or AgC requires re-pressing process, thus, F type is a
  better choice.
 

 

 
       
       
   3. Ag Thickness ( t )：    
       
  The Ag thickness of powder metallurgy contact should be over 1.0mm minimum.(The Ag layer should be increased accordingly when contact area is enlarged.)  While Ag layer is below 1.0mm, we suggest to use internal oxidation contact instead.  While Ag layer is over 3.0mm to maximum 15mm, we suggest to use single-press mold. (Ag layer is adjusted in accordance with the contact dimension. Ag layer thickness should be finalized only after sample-producing.)    
       
       
   4. Cambered Surface (R)：    
       
  (1) Cambered surface: long-side camber, short-side camber and sphere camber.    
  (2) The curvature of cambered surface will change after oxidation process. The general    
       tolerance is ?span lang="EN-US"> 10R as it requires larger tolerance.    
       
       
   5. Corner Radius ( r )：    
       
  Corner Radius requires at least over 0.5r.  Powder metallurgy contact is crumbly.  The lack of contact corner radius might cause corner collapse for square, rectangle or trapezoid shape.    
       
       
   6. Brazing Alloy (Solder Backing)：    
       
 
(1). Cadmium-free brazing alloy - BAg-5 & BAg-6 are suggested.  But the contacts for
  MCCB could be brazed with BCuP-5  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
   
        hickness is between1/2 and 1/3 of the contact thickness).    
       
   7. Reference design of powder metallurgy contact：    
       
  (1)Tolerance of contact thickness (T):     
 

(Contact is liable to shrink and change shape in sintering.)

    
 
Thickness(mm) Contact Area(mm2) Thickness Tolerance(mm)
1.00～1.50 25～150 ±0.10
1.51～2.00 25～150 ±0.15
2.01～3.00 25～150 ±0.20
1.00～1.50 151～200 ±0.15
1.51～2.00 151～200 ±0.20
2.01～3.00 151～200 ±0.25
1.51～2.00 201～320 ±0.20
2.01～3.00 201～320 ±0.30
3.01～4.00 321～400 ±0.50
   
       
  (2)  The tolerance for length, width or diameter is ?/span>0.20mm.    
  (3)  The tolerance for surface camber ( R ) is ?/span>10R.    
  (4)  Tolerances for special dimensions or dimensions out of above range is other specified.    
  　 　

　
　
No.23, Wugong 5th Rd., Xinzhuang Dist.,New Taipei City 24890,

(New Taipei Industrial Park), Taiwan, R.O.C.
TEL：+886-2-2299-0011
FAX：+886-2-2299-0123
E-Mail:tpe@tecc.com.tw
Overseas Department：Ms. Amy Chang # 215