Nickel – B
Special Electroless Nickel – Boron
For High Electrical Conductivity and Oxidation Resistance
Transene’s electroless nickel-boron process, NICKEL-B, offers unique characteristics (not equalled by nickel-phosphorous formulations) which are required by many electrical contact and bonding applications. NICKEL-B plates directly on oxide-free nickel / kovar / copper / tin. Plating on non-metallic surfaces may be accomplished by using Transene’s RTM Activator and Sensitizer.
Transene’s NICKEL-B metallization resists oxidation, has excellent electrical conductivity and may be plated, soldered, brazed or welded. The NICKEL-B plate has a boron content of 2-3%, electrical conductivity approximately equal to 60/40 tin-lead solder and plate hardness of 500 Vickers. NICKEL-B metallizations are more readily soldered than electrolytic nickel and electroless nickel-phosphorus, easily die-bonded using gold-silicon preforms and completely compatible with die attach epoxies.
Ultrasonic or thermal-compression wire bonding of aluminum to NICKEL-B bonding pads can be accomplished with results superior to those employing gold bonding pads. Electrical contacts plated with 0.20 mil NICKEL-B and 10 micro-inches of gold exhibit characteristics (conductivity / hermeticity) equivalent to 50 micro-inches of gold plated on electrolytic nickel.
PROPERTIES OF NICKEL-B
|Appearance||Blue solution, pH 8|
|pH control||Ammonium Hydroxide pH range 7-10|
|Operating Temperature||60-70 °C|
|Plating Capacity (50% depletion)||1200 in2/0.5 mil/gal|
|Nickel metal content||.65 oz/gal|
|Deposition rate||0.45 mil/hr|
|Composition of deposit||98% Ni, 2% Boron|
PROPERTIES OF DEPOSITED NICKEL-B
|Coeff. of Expansion||130 x 10-6 in/in/°C|
|Hermeticity (0.15 mils)||Leak rate: 10-8 cc helium/sec|
|Elect. resistivity (0.20 mil)||30 milliohm/sq.|
|Thermal conductivity||0.01 cal/cm2/cm/°C/sec|
|Hardness (as plated)||500 Vickers|
|Solderability (tin-lead)||Excellent-flux not required|
|Brazing-silver (hydrogen/forming gas)||Excellent @ 500-850|
NICKEL-B operates @ 60-65 °C depositing autocatalytically on appropriate metallic surfaces. (RTM Activator and Sensitizer may be used on non-metallic surfaces.) Applications include: Burn-in contacts, connector pins and sockets, diode cans and transistor headers, heat sinks, lead frames, PC board fingers, capacitor bodies and ceramics.