When changing devices in your rectifier, it is important to consider which kind of compound is appropriate. There are two types. One is electrically conductive and the other thermally conductive. While some have other properties such as corrosion inhibitors, the main concerns when changing internal rectifier components that utilize compounds are whether the part conducts heat or electrical current.
Electrically conductive applications such as mounting the “Hockey Puck” style and stud mount type SCR’s and Diodes; current passes through the device so the compound used should also be electrically conductive. ALCOA EJC#2 is a brownish color compound and is acceptable and available for this purpose. There are other appropriate compounds such as Dow Corning DC 200 or JET LUBE SCX13 but EJC#2 is the most readily available of the options.
The other type of compound is for thermal conduction. Components such as thermal switches, Power Block® Diodes, and IGBT’s use an electrically insulated base intended for conduction of heat into a heatsink. For this application, use the white colored thermal paste manufactured by Timtronics called White Ice 517. Another source for this compound is Wakefield 120. Both are simply sourced.
There are other compounds promoted for use with rectifier connections and buss work where corrosion inhibitors are of concern such as NOALOX anti- oxidant. Although this is good for dissimilar metal buss connections, it is not recommended for use on SCR’s and diodes. Also, do not use the white colored thermal paste when mounting “Hockey Puck” or stud mount diodes. It is an electrical INSULATOR and can cause devices to overheat and fail prematurely. Inversely, using the EJC#2 to mount IGBT’s or other thermally conductive applications will cause improper heat transfer and premature failure.
Proper and timely device maintenance will extend the life of your components and maximize the reliability in your rectifiers. Please let us know if there is a topic that you would like covered in future APP newsletters.
These compounds are available via our web store store.americanplatingpower.com or by calling Scott Brown, our Spare Parts Manager, at 239-275-5877. For more information please contact us at info@americanplatingpower.com.
