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 ± 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
±0.20mm.
(3)The
tolerance for surface camber ( R ) is ±10R.
(4)Tolerances for special
dimensions or dimensions out of above range is other specified.
23,
Wu-Kung 5th Rd., Hsin-Chuang City, Taipei County,
Design Reference of Powder
Metallurgy Electric Contact Tips 
