Electronic-Grade Coatings with HVAF
Preventing Galvanic Corrosion, Providing Electrical and Thermal Conductive Layers.
Kermetico HVAF industrial equipment provides a cost-effective way to deposit 50+ µm (0.002” +) thick conductive coatings of copper and aluminum onto electronic components.
Kermetico's HVAF copper coatings are characterized by less than 1% porosity, low (0.30-0.40 wt.%) oxygen level, high (>75 MPa | 10,000 PSI) adhesion and electrical resistivity of 0.03 micro-Ohm*m. They could be used as a heat conductive coating in electronic packaging devices, brazing layers over aluminum heat sinks and high electrical conductivity layers.
Preventing Galvanic, Bimetallic or Contact Corrosion with Coatings
Bimetallic corrosion is also referred to as a galvanic corrosion, dissimilar metal corrosion or contact corrosion.
Bimetallic corrosion occurs when two metals with different potentials, are in electrical contact while immersed in an electrically conducting corrosive liquid. Because the metals have different natural potentials in the liquid, a current will flow from the anode (more electronegative) metal to the cathode (more electropositive), which will increase the corrosion on the anode.
In general, the reactions which occur are similar to those that would occur on single, uncoupled metal, but the rate of attack is increased, sometimes dramatically.
Preventing liquid from an appearance at the point of contact mitigates galvanic corrosion. HVAF sprayed Cu on Al surfaces provide this result.
Kermetico's HVAF equipment deposits bulk-like Al, Cu, brass and bronze coatings up to several millimeters thick. They exhibit excellent machinability (turning, grinding, finishing) and are as engravable as electroplated copper.
Kermetico HVAF equipment deposits up to 10 kg (22 lbs.) of copper coating per hour, offering the shortest production time. Good solderability and heat conductivity of our coatings allow their use for heat sinks in power electronic applications.
HVAF High Velocity Thermal Spraying of Low Oxidation Coatings of Copper, Bronze and Brass Alloys
A Micrograph of a Kermetico HVAF Copper Conductive Coating
We have a time-proven approach for the high velocity thermal spray application of copper coatings with the Kermetico HVAF SL thermal spray system.
Our systems allow the deposition of copper and its alloys, including brass, bronze and some individual grades like Cu-In-Ga.
High heat conductivity copper application onto balls and other spherical parts with thicknesses of 6-mm (0.240”) and more is an easy task for the Kermetico HVAF SL system.
A customer requested the application of a high electrical conductivity copper layer with a particular pattern, 0.2 mm (0.008”) thick and the width of each band was about 2.5 mm (0.100”).
The first approach used machining and milling the copper coating to achieve the required pattern.
The Kermetico HVAF Copper coating behaves as a “solid” metal during machining. And milling through the coating down to the substrate was performed without the remaining copper layer delaminating. (This should give you some idea about the bonding and cohesive strength of the copper coating.)
Bond strength measurements report over 11,000 PSI (over 75 MPa) on carbon steel, the majority related to breaking the glue used for ASTM 633C testing.
Spraying of brass and bronze thermal spray coatings is even simpler than the pure copper.
For more on the HVAF SL Specialised System, Click Here.
